- Email: [email protected]
A Study on the Voltage Control Method of Primary Feeder by the Energy Storage System and Step Voltage Regulator
2019 IFAC Workshop on 2019 IFAC Workshop Control of Smart Gridon and Renewable Energy Systems 2019 IFAC Workshop on online at www.sciencedirect.com 2019 IFAC Workshop on Control of Smart Grid and RenewableAvailable Energy Systems 2019 IFAC Workshop on Jeju, Korea, June 10-12, 2019 Control of Smart Grid and Renewable Energy Systems 2019 IFAC Workshop on Control of Smart and Renewable Energy Systems Jeju, Korea, JuneGrid 10-12, 2019 Control of Smart Grid and Renewable Energy Systems Jeju, Korea, JuneGrid 10-12, 2019 Control of Smart and Renewable Energy Systems Jeju, Korea, Korea, June 10-12, 10-12, 2019 Jeju, June 2019 Jeju, Korea, June 10-12, 2019
ScienceDirect
IFAC PapersOnLine 52-4 (2019) 431–436
A Study on the Voltage Control Method of Primary Feeder by the Energy A Study on the Voltage Control Method of Primary Feeder by the Energy A Study on the Voltage Control Method of Primary Feeder by the Energy Storage System and Step Voltage Regulator A Study on the Voltage Control Method of Primary Feeder by the Energy System and Step Voltage Regulator A Study on the Storage Voltage Control Method of Primary Feeder by the Energy Storage System and Step Voltage Regulator Storage System and Step Voltage Regulator Storage System andRyu*, StepDae-Jin Voltage Byungki Kim*, Kyung-Sang Kim*,Regulator Yang-Hyun Nam*,
Byungki Kim*, Kyung-Sang Ryu*, Dae-Jin Kim*, Yang-Hyun Nam*, Byungki Kim*, Kyung-Sang Ryu*, Dae-Jin Kim*, Yang-Hyun Nam*, Heesang Ko*, Ho-Chan Kim** Byungki Kim*, Kyung-Sang Ryu*, Dae-Jin Kim*, Yang-Hyun Nam*, Byungki Kim*, Kyung-Sang Ryu*, Dae-Jin Kim*, Yang-Hyun Nam*, Heesang Ko*, Ho-Chan Kim** Byungki Kim*, Kyung-Sang Ryu*, Dae-Jin Kim*, Yang-Hyun Nam*, Heesang Ko*, Ho-Chan Kim** Heesang Ko*, Ho-Chan Kim** Heesang Ko*, Ho-Chan Kim** Heesang Ko*, Ho-Chan Kim** *Energy Systems Integration Laboratory, Korea Institute of Energy Research, Jeju, Korea *Energy Systems Integration Laboratory, Korea Institute of Energy Research, Jeju, Korea *Energy Systems Integration Laboratory, Korea Institute of Energy Research, Jeju, Korea (e-mail:[email protected], [email protected], [email protected], [email protected], [email protected] ) *Energy Systems Integration Laboratory, Korea Institute of Energy Research, Jeju, Korea *Energy Systems Integration Laboratory, Korea Institute of Energy Research, Jeju, Korea (e-mail:[email protected], [email protected], [email protected], [email protected], [email protected] )) *Energy Systems Integration Laboratory, Korea Institute of Energy Research, Jeju, Korea (e-mail:[email protected], [email protected], [email protected], [email protected], [email protected] **Department of Electrical Engineering, Jeju National University, Jeju, Korea (e-mail:[email protected], [email protected], [email protected], [email protected], [email protected] )) (e-mail:[email protected], [email protected], [email protected], [email protected], [email protected] **Department of Electrical Engineering, Jeju National University, Jeju, Korea (e-mail:[email protected], [email protected], [email protected], [email protected], [email protected] ) **Department of Engineering, Jeju University, Korea (e-mail: [email protected]) **Department of Electrical Electrical Engineering, Jeju National National University, Jeju, Jeju, Korea **Department of Electrical Engineering, Jeju National University, Jeju, Korea (e-mail: [email protected]) **Department of Electrical Engineering, Jeju National University, Jeju, Korea (e-mail: [email protected]) (e-mail: [email protected]) [email protected]) (e-mail: (e-mail: [email protected]) Abstract: In order to keep the customer voltages within nominal voltage boundary (220±6%), operation Abstract: In order to keep the customer voltages within nominal voltage boundary (220±6%), operation Abstract: order to keep the customer voltages within voltage boundary (220±6%), operation method ofIn SVR(Step Voltage Regulator) at primary feedernominal is very important considering the scheduled tap Abstract: In order to keep the customer voltages within nominal voltage boundary (220±6%), operation Abstract: In order to keep the customer voltages within nominal voltage boundary (220±6%), operation method of SVR(Step Voltage Regulator) at primary feeder is very important considering the scheduled tap Abstract: In order toof keep theHowever, customerthe voltages within nominal voltage boundary (220±6%), operation method of SVR(Step Voltage Regulator) at primary feeder is very important considering the scheduled tap time delay(120 sec) SVR compensation of voltage during the tap delay time of SVR is method of SVR(Step Voltage Regulator) at primary feeder is very important considering the scheduled tap method of SVR(Step Voltage Regulator) at primary feeder is very important considering the scheduled tap time delay(120 sec) of SVR However, the compensation of voltage during the tap delay time of SVR is method of SVR(Step Voltage Regulator) at primary feeder is very important considering the scheduled tap time delay(120 sec) of SVR However, the compensation of voltage during the tap delay time of SVR is being required at primary feeder introduced in RES (Renewable Energy Recourse). Because customer time delay(120 sec) of SVR However, the compensation of voltage during the tap delay time of SVR is time delay(120 sec) of SVR However, the compensation of voltage during the tap delay time of SVR is being required at primary feeder introduced in RES (Renewable Energy Recourse). Because customer time delay(120 sec) of SVR However, the compensation of voltage during the tap delay time of SVR is being required at primary feeder introduced in RES (Renewable Energy Recourse). Because customer voltage should be to exceed nominal voltage boundary during the operated time of RES. Therefore, in order being required required at to primary feeder introduced in RES RES during (Renewable Energytime Recourse). Because customer customer being at primary feeder introduced in (Renewable Energy Recourse). Because voltage should be exceed nominal voltage boundary the operated of RES. Therefore, in order being required at primary feeder introduced in RES (Renewable Energy Recourse). Because customer voltage should be to exceed nominal voltage boundary during the operated time of RES. Therefore, in order to keep the secondary feeder voltage within nominal voltage boundary at all the time, this paper proposed voltage should be to to exceed exceed nominal voltage boundary during boundary the operated operated time oftime, RES.this Therefore, in order order voltage be nominal voltage boundary during the time of RES. Therefore, in to keep should the secondary feeder voltage within nominal voltage at all the paper proposed voltage should be tomethod exceed during boundary the operated time RES. Therefore, in order to the secondary feeder voltage within nominal at the this paper the voltage innominal primary feeder boundary by using voltage coordination control algorithm between ESSproposed (Energy to keep keep the control secondary feeder voltagevoltage within nominal voltage boundary at all all theoftime, time, this paper proposed to keep the secondary feeder voltage within nominal voltage boundary at all the time, this paper proposed the voltage control method in primary feeder by using coordination control algorithm between ESS (Energy to keep the secondary feeder voltage within boundary at all the time, paper the voltage control method in primary feeder by coordination control algorithm between ESS (Energy Storage System) and SVR. From the simulation resultsvoltage analysis of customer voltages bythis presenting voltage the voltage control method in primary feeder nominal by using using coordination control algorithm between ESSproposed (Energy the voltage control method in primary feeder by using coordination control algorithm between ESS (Energy Storage System) and SVR. From the simulation results analysis of customer voltages by presenting voltage the voltage control method in primary feeder by using coordination control algorithm between ESS (Energy Storage System) and SVR. From the simulation results analysis of customer voltages by presenting control method between ESS and SVR based on the PSCAD/EMTDC, it is confirmed that customer voltage Storage System) and SVR. From the simulation results analysis of customer voltages by presenting voltage Storage System) and SVR. From the simulation results analysis of customer voltages by presenting control method between ESS and SVR based on the PSCAD/EMTDC, it is confirmed that customer voltage Storage System) and SVR. From the simulation results analysis voltages by presenting control method between ESS and SVR based on the PSCAD/EMTDC, it is confirmed that customer voltage in distribution system can be maintained within allowable limit.of customer control method between ESS and SVR based on the PSCAD/EMTDC, it is confirmed that customer voltage control method between ESS and SVR on PSCAD/EMTDC, it in distribution can be maintained within allowable limit. control methodsystem between ESS and SVR based based on the the PSCAD/EMTDC, it is is confirmed confirmed that that customer customer voltage voltage in distribution system can be maintained within allowable limit. in distribution system can be maintained within allowable limit. in distribution system can be maintained within allowable limit. © 2019, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved. Keywords: Step Voltage Regulator, Coordination Contorl Algorithm, Energy Storage System, in distribution system can be maintained within allowable limit. Keywords: Step Voltage Regulator, Coordination Contorl Algorithm, Energy Storage System, Keywords: Step Step Voltage Voltage Regulator, Regulator, Coordination Coordination Contorl Contorl Algorithm, Algorithm, Energy Energy Storage Storage System, System, PSCAD/EMDC Keywords: Keywords: Step Voltage Regulator, Coordination Contorl Algorithm, Energy Storage System, PSCAD/EMDC Keywords: Step Voltage Regulator, Coordination Contorl Algorithm, Energy Storage System, PSCAD/EMDC PSCAD/EMDC PSCAD/EMDC PSCAD/EMDC during the tap change delay time of SVR. That is, when the 1. INTRODUCTION during the tap change delay time of SVR. That is, when the during the tap change delay of SVR. That when the acceptance voltage is out of time tolerance during theis, tap change 1. INTRODUCTION during the tap change delay time of SVR. That is, when the 1. INTRODUCTION during the tap change delay time of SVR. That is, when the acceptance voltage is out of tolerance during the tap change 1. INTRODUCTION the tap change delay time of SVR. That is, when the acceptance voltage is out of tolerance during the tap change delay time of SVR to solve the voltage problem due to As power systems 1. have been decentralized according to the during INTRODUCTION acceptance voltage is out of tolerance during the tap change 1. INTRODUCTION acceptance voltage is out of tolerance during the tap change delay time of SVR to solve the voltage problem due to the As power systems have been decentralized according to the acceptance voltage is out of tolerance during the tap change delay time of SVR to solve the voltage problem due to the renewable energy and the load fluctuation, the voltage problem As power systems have been decentralized according to the technology development of renewable energy resource, RES delay time of SVR to solve the voltage problem due to the As power systems have been decentralized according to the delay time of SVR to solve the voltage problem due to the renewable energy and the load fluctuation, the voltage problem As power systems have been decentralized according to the technology development of renewable energy resource, RES delay time of SVR to solve the voltage problem due to renewable energy and the load fluctuation, the voltage problem is solved through charging and discharging operation of the As power systems have been decentralized according to the technology development of renewable energy resource, RES have been actively introduced and operated in primary feeder. renewable energy and the load fluctuation, the voltage problem technology development of renewable energy resource, RES renewable energy and the load fluctuation, the voltage problem is solved through charging and discharging operation of the technology development of renewable energy resource, RES have been actively introduced and operated in primary feeder. renewable energy and the load fluctuation, the operation voltage problem is through charging and discharging of having a quick response. technology development of renewable energy resource, RES have been actively introduced and operated in primary feeder. However, many power quality problems case RES are ESS is solved solved through charging and discharging operation of the the have been actively introduced and operated in primary feeder. is solved through charging and discharging operation of ESS having aa quick response. have been actively introduced and operated in primary feeder. However, many power quality problems case RES are is solved through charging and discharging operation of the the ESS having quick response. Based on the issues earlier, this paper proposes the optimal have been actively introduced and operated in primary feeder. However, many power quality problems case RES are connected in primary feeder including secondary feeder may ESS having a quick quick response. However, in many power quality problems in case casefeeder RES may are ESS having a response. Based on the issues earlier, this paper proposes the optimal However, many power quality problems in RES are connected primary feeder including secondary ESS having a quick response. Based on the issues earlier, this paper proposes the optimal voltage control method in primary feeder by using ESS and However, many power quality problems in case RES are connected in primary feeder including secondary feeder may be occurred such as voltage variations, flicker and harmonic in Based on on the issues issues earlier, this paper paper proposes theESS optimal connected insuch primary feedervariations, includingflicker secondary feeder may may Based the earlier, this proposes the optimal voltage control method in primary feeder by using and connected in primary feeder including secondary feeder be occurred as voltage and harmonic in Based on thetoissues earlier, this paper proposes theESS optimal voltage control method in feeder by using and in order maintain theprimary customer voltage within nominal connected insuch primary feeder including secondary feeder may be occurred as variations, flicker and harmonic in variety. Where, this paper deals with voltage management of voltage control method in primary feeder by using ESS and be occurred such as voltage voltage variations, flicker and harmonic in SVR voltage control method in primary feeder by using ESS and SVR in order to maintain the customer voltage within nominal be occurred such as voltage variations, flicker and harmonic in variety. Where, this paper deals with voltage management of control method in primary feeder by using ESS and SVR in order to maintain the customer voltage within nominal voltage boundary at all the time. From the modeling by the be occurred such as voltage variations, flicker and harmonic in variety. Where, this paper deals with voltage management of the many issues in order to keep the secondary feeder voltage SVR in order to maintain the customer voltage within nominal variety. Where, this paper deals with voltage management of SVR in order to maintain the customer voltage within nominal voltage boundary at all the time. From the modeling by the variety. Where, this paper deals with voltage management of the many issues in order to keep the secondary feeder voltage SVR in order to maintain the customer voltage within nominal voltage boundary at all the time. From the modeling by the PSCAD/EMTDC and simulation analysis adapted in operation variety. Where, this paper deals with voltage management of the many issues in order to keep the secondary feeder voltage voltage boundary at all the time. From the modeling by the within nominal voltage boundary (allowable limit: 220±6%) the many issues in order to keep the secondary feeder voltage voltage boundary at all the time. From the modeling by the PSCAD/EMTDC and simulation analysis adapted in operation the many issues in order to keep the secondary feeder voltage within nominal voltage boundary (allowable limit: 220±6%) voltage boundary at all the time. From the modeling by the PSCAD/EMTDC and simulation analysis adapted in operation strategy of SVR and ESS, it is confirmed that customer voltage the many issues in order to keep the secondary feeder voltage within nominal voltage boundary (allowable limit: 220±6%) PSCAD/EMTDC and simulation analysis adapted in operation PSCAD/EMTDC and simulation analysis adapted in operation using SVR and ESS. strategy of SVR and ESS, it is confirmed that customer voltage within nominal voltage boundary (allowable limit: 220±6%) within nominal voltage boundary (allowable limit: 220±6%) PSCAD/EMTDC and simulation analysis adapted in operation strategy of SVR and ESS, it is confirmed that customer voltage in primary feeder can be kept within nominal voltage boundary. using SVR and ESS. within nominal voltage (allowable limit: 220±6%) of SVR and ESS, it iswithin confirmed that customer voltage using and strategy of SVR ESS, it confirmed that customer voltage In a SVR distribution systemboundary where existing renewable energy is strategy in primary can be kept nominal boundary. using SVR and ESS. ESS. strategy of feeder SVR and and it is iswithin confirmed that voltage customer voltage in feeder can be nominal voltage boundary. using and ESS. In aa SVR distribution system where existing renewable energy is in primary primary feeder canESS, be kept kept within nominal voltage boundary. using SVR and ESS. In distribution system where existing renewable energy is in primary feeder can be kept within nominal voltage boundary. not linked, the SVR is installed and operated at a point where In a distribution system where existing renewable energy is in primary feeder can be kept within nominal voltage boundary. In a distribution system where existing renewable energy is not linked, the SVR is installed and operated at a point where 2. VOLTAGE CONTROL OF ESS DEPENDING ON SVR In linked, avoltage distribution system where existing renewable energy is not the SVR is installed and operated at aa point where the drop exceeds 5% in the long distance primary not linked, the SVR is installed and operated at where 2. VOLTAGE CONTROL OF ESS DEPENDING ON SVR not linked, the SVR is installed and operated at aa point point where the voltage drop exceeds 5% in the long distance primary 2. VOLTAGE CONTROL OF ESS DEPENDING ON SVR CONTROL MODE not linked, the SVR is installed and operated at point where the voltage drop exceeds 5% in the long distance primary feeder. In addition, studies are underway to stabilize the 2. VOLTAGE CONTROL OF ESS DEPENDING ON SVR the voltage drop exceeds 5% in the long distance primary 2. VOLTAGE CONTROL OF ESS DEPENDING ON SVR CONTROL MODE the voltage drop exceeds 5% in the long distance primary feeder. In addition, studies are underway to stabilize the 2. VOLTAGE CONTROL OF ESS DEPENDING ON SVR CONTROL MODE the voltage drop exceeds 5% in the long distance primary feeder. In addition, studies are underway to stabilize the voltage instability of the distribution system caused by CONTROL MODE feeder. In addition, studies are underway to stabilize the Generally, Tap position decision of SVR is considered by CONTROL MODE feeder. In addition, studies are underway to stabilize the voltage instability of the distribution system caused by CONTROL MODE feeder. In addition, studies are underway to stabilize the voltage instability of the distribution system caused by linkage of RES through various operation algorithms of SVR. Generally, Tap position decision of SVR is considered by voltage instability of the distribution system caused by the Generally, Tap position decision of SVR is considered by compensation-rate according to the relationship between voltage instability of the distribution system caused by the linkage of RES through various operation algorithms of SVR. Generally, Tap position decision of SVR is considered by voltage instability of the distribution system caused by the linkage of RES through various operation algorithms of SVR. However, since the SVR installed in the current distribution Generally, Tap position decision of SVR is considered by compensation-rate according to the relationship between linkage of RES RES through various operation algorithms of SVR. SVR. sending Generally, Tap position decision of SVR is considered by compensation-rate according to the relationship between voltage by Line Drop Compensation method and linkage of through various operation algorithms of However, since the SVR installed in the current distribution compensation-rate according to the relationship between linkage of RES through various operation algorithms of SVR. However, since the SVR installed in the current distribution system is composed of mechanical elements, the tap change to compensation-rate according to the relationship between sending voltage by Line Drop Compensation method and However, since the theofSVR SVR installedelements, in the the current current distribution compensation-rate according to the relationship between sending voltage by Line Drop Compensation method and reference tap (13200V) among the 17 tap of SVR. And then, However, since installed in distribution system is composed mechanical the tap change to sending voltage by Line Drop Compensation method and However, since the installed in the current distribution system is of mechanical the change to solve the voltage problem does notelements, operate immediately sending voltage by Drop Compensation method and reference tap (13200V) among the 17 tap of SVR. And then, system is composed composed ofSVR mechanical elements, the tap tap changeand to tap sending voltage by Line Line Droptime Compensation method and reference tap (13200V) the 17 tap of SVR. And then, is controlled after theamong delay (120sec) of SVR after tap system is composed of mechanical elements, the tap change to solve the voltage problem does not operate immediately and reference tap (13200V) among the 17 tap of SVR. And then, system is composed of mechanical elements, the tap change to solve the voltage problem does not operate immediately and operates after a delay time of about 120 seconds. For this reference tap (13200V) among the 17 tap of SVR. And then, tap is controlled after the delay time (120sec) of SVR after tap solve the voltage problem does not operate immediately and reference tap (13200V) among the 17 tap of SVR. And then, tap is controlled after the delay time (120sec) of SVR after tap operation decision according to the voltage variation rate. solve the voltage problem does not operate immediately and operates after a delay time of about 120 seconds. For this tap is controlled controlled afteraccording the delay delay to time (120sec) ofvariation SVR after afterrate. tap solve the voltage problem does not operate immediately and operates after time of about 120 seconds. For this reason, there isaaa delay possibility that the voltage will deviate from tap is after the time (120sec) of SVR tap operation decision the voltage operates after delay time of about 120 seconds. For this tap is controlled after the delay time (120sec) of SVR after tap operation decision according to the voltage variation rate. However under voltage and over voltage could be occurred operates after a delay time of about 120 seconds. For this reason, there is a possibility that the voltage will deviate from operation under decision according to the the voltage variation rate. operates after a delay time of about 120 seconds. For this reason, there is a possibility that the voltage will deviate from the allowable limit during the delay time for the tap change of operation decision according to voltage variation rate. However voltage and over voltage could be occurred reason, there is aa possibility that the voltage will deviate from operation decision according to the voltage variation rate. However under voltage and over voltage could be occurred during the delay time when is state before tap operation of reason, there is possibility that the voltage will deviate from the allowable limit during the delay time for the tap change of However under voltage and over over voltage could be occurred occurred reason, there islimit a possibility that the time voltage will deviate from the allowable during the delay for the tap change of SVR. However under voltage and voltage could be during the delay time when is state before tap operation of the allowable limit during the delay time for the tap change of However under voltage and over voltage could bethis occurred during the delay time when is state before tap operation of SVR. In order to overcome these problems, paper the allowable limit during the delay time for the tap change of SVR. during the delay time when is state before tap operation of the allowable limit during the delay time for the tap change SVR. Therefore, the voltage compensation during the delay time of during the delay time when is state before tap operation of SVR. In order to overcome these problems, this paper SVR. during the delay time when is state before tap operation of SVR. In order to overcome these problems, this paper presents voltage control method by ESS during the time delay SVR. Therefore, the voltage compensation during the delay time of SVR. In order to overcome these problems, this paper SVR. Therefore, the voltage compensation during the delay time of SVR is being required because the customer voltages have a SVR. In order to overcome these problems, this paper presents voltage control method by ESS during the time delay Therefore, therequired voltage because compensation during the the delay time time ofa of SVR. In order to overcome these problems, this paper presents voltage control method by ESS during the time delay SVR tap operation as shown in Fig. 1. Therefore, the voltage compensation during delay of SVR is being the customer voltages have voltage control method by ESS during the time delay Therefore, voltage compensation during the delay time ofaa presents SVR is because the voltages have difficultly tothe berequired kept within the nominal voltage boundary. presents voltage control method by ESS during of SVR tap operation as shown in SVR is being being required because the customer customer voltages haveIn presents voltage control method byFig. ESS1. during the the time time delay delay SVR tap operation as shown in Fig. 1. SVR is being required because the customer voltages have aa of difficultly to be kept within the nominal voltage boundary. In of SVR tap operation as shown in Fig. 1. SVR is being required because the customer voltages have difficultly be within nominal voltage In this paper,to is used to the solve problems thatboundary. may occur difficultly toESS be kept kept within the nominal voltage boundary. In of of SVR SVR tap tap operation operation as as shown shown in in Fig. Fig. 1. 1. difficultly to be kept within the nominal voltage boundary. In this paper, ESS is used to solve problems that may occur difficultly be kept within nominal voltage In this paper, is to solve problems that may this paper,toESS ESS is used used to the solve problems thatboundary. may occur occur this this paper, paper, ESS ESS is is used used to to solve solve problems problems that that may may occur occur
2405-8963 © IFAC (International Federation of Automatic Control) Copyright © 2019, 2019 IFAC 466Hosting by Elsevier Ltd. All rights reserved. Copyright 2019 responsibility IFAC 466Control. Peer review©under of International Federation of Automatic Copyright © 2019 IFAC 466 Copyright © 466 10.1016/j.ifacol.2019.08.248 Copyright © 2019 2019 IFAC IFAC 466 Copyright © 2019 IFAC 466
2019 IFAC CSGRES 432 Jeju, Korea, June 10-12, 2019
Byungki Kim et al. / IFAC PapersOnLine 52-4 (2019) 431–436
Fig.3 LDC Modeling of SVR Using the electrical modeling for LDC method of SVR as mentioned earlier, the control modeling for tap up and tap down with the bandwidth of 50% and scheduled delay time of 120 seconds is designed as shown in Fig.4.
Fig. 1. Voltage control in primary feeder by the SVR and ESS First of all, if the secondary feeder voltages are dropped than lower limit, ESS is carried out chagrining state. And also, when secondary feeder voltage should be raised than upper limit, ESS is operated as discharging state. As mentioned earlier, role of ESS as voltage stabilization function is kept within the nominal voltage boundary at secondary feeder voltage during the time delay (120sec) of SVR tap. 3. MODELING OF PRIMARY FEEDER WITH SVR AND ESS USING PSCAD/EMTDC
(a) Up tap logic
In order to analyze characteristic of customer voltage according to ESS and SVR operation, modeling of primary feeder with ESS, SVR and RES is designed by PSCAD/EMTDC as shown in Fig.2. Here, primary and secondary feeder are composed of total 6 section with RES at the end section And also, ESS and SVR are located in end point of section 3 in primary feeder. (b) Down tap logic Fig.4. Tap up and tap down logic of SVR 3.2 Modeling of ESS ESS is modeled with battery, DC-DC converter, inverter and transformer. Firstly, the battery that can adjust the parameters such as the initial SOC(State Of Charge) and the capacity is connected to the DC-DC converter. The DC-DC converter can determine the charging / discharging of the ESS. It operates as a buck converter when charging, and as a boost converter when discharging as shown in Fig. 5.
Fig. 2. Distribution system using the PSCAD/EMTDC 3.1 Modeling of SVR Decision for optimal sending voltage of SVR is very important to modeling of SVR. Therefore this paper presents modeling method for optimal sending voltage setting values of LDC method by the statistical analysis compared with ideal optimal sending voltages and total load currents. Under these concept, the SVR for electrical factor of LDC method is modeled by PSCAD/EMTDC as shown in Fig. 3. 467
2019 IFAC CSGRES Jeju, Korea, June 10-12, 2019
Byungki Kim et al. / IFAC PapersOnLine 52-4 (2019) 431–436
433
(a) Buck/Boost converter modeling
(b) Control algorithm (b) Upper level control of DC-DC converter Fig. 6. ESS modeling Fig. 5. Modeling of ESS 4. VOLTAGE CONTROL METHOD OF SVR AND ESS
The output of the DC-DC converter is connected to the inverter through a DC-link, and the inverter controls the DC voltage on DC link and reactive power. The AC / DC conversion of voltage and current is also performed in the inverter and the output of inverter is connected to the transformer. The transformer converts the voltage level to the system and transfers power to the system. Figure 6 shows the overall configuration of an ESS consisting of a battery, a converter, an inverter, and a transformer.
4.1 SVR control algorithm LDC method of SVR which is located in primary feeder to compensate the voltage variations is to find the optimal setting values (Vce, Zeq) and optimal sending voltages in order to deliver suitable voltages to many customers as possible as shown in Eq. (1). It firstly determines the ideal optimal sending voltages which can be expressed by the optimal compensation rates of SVR, and then obtains optimal setting values by statistical analysis according to the relationship between ideal optimal sending voltages and total load currents. 𝑉𝑉𝑉𝑉𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (𝑡𝑡𝑡𝑡) = 𝑉𝑉𝑉𝑉𝑐𝑐𝑐𝑐𝑠𝑠𝑠𝑠 + 𝑍𝑍𝑍𝑍𝑠𝑠𝑠𝑠𝑒𝑒𝑒𝑒 × 𝐼𝐼𝐼𝐼𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑠𝑠𝑠𝑠𝑏𝑏𝑏𝑏 (𝑡𝑡𝑡𝑡)
Fig. 6. ESS modeling
(1)
As mentioned earlier, tap decision of SVR is considered by compensation-rate according to the relationship between sending voltage for LDC method and reference tap(13200V) of SVR, and then tap should be operated when is violated to bandwidth(50%) during the time delay(120sec) as shown in Fig.7. Here, left box is SVR control part by input of LDC method including measuring element and predetermined, Vce and Zeq, and also right box is tap operation part by control signal to be occurred in the control part.
3.3 Modeling of PV PV is briefly modeled using VSC(Voltage Source Converter) and a current source, and the power from solar power is replaced by a current source as shown in Fig 7(a). The current source depends on the amount of power. The control strategy is presented in Fig. 7(b). The voltage and current of the grid are decomposed into a direct component and a quadrature component through a park transform and PLL. Here, The direct component of current id regulates the active power and the quadrature component of current iq controls the reactive power. On the other hand, the six pulse waveforms for driving the IGBT are obtained by using the inverse Park transform of id, iq and set point values vd, vq.
Fig. 7. Operation block diagram of SVR (a) PV system
468
2019 IFAC CSGRES 434 Jeju, Korea, June 10-12, 2019
Byungki Kim et al. / IFAC PapersOnLine 52-4 (2019) 431–436
Here, 𝑓𝑓𝑓𝑓𝑏𝑏𝑏𝑏 (t) is tap operation signal for motor drive unit of. And also 𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏 (t) is tap changing signal according to tap position determination as follows Eq. (2) 𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏 (t) =
𝑉𝑉𝑉𝑉𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (𝑡𝑡𝑡𝑡)−𝑉𝑉𝑉𝑉𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 𝑉𝑉𝑉𝑉𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠−𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏𝑇𝑇𝑇𝑇𝑖𝑖𝑖𝑖𝑠𝑠𝑠𝑠𝑖𝑖𝑖𝑖
mode operation (σ(t) = 1) is performed when the voltage is kept below the lower limit (207V). Where, in order to operate the ESS installed on the primary feeder, it is assumed that the first customer voltage and last customer voltage of secondary feeder terminal can be checked in real time by the measuring device.
(2)
−1 𝑖𝑖𝑖𝑖𝑓𝑓𝑓𝑓 𝑉𝑉𝑉𝑉𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 ≥ 233𝑉𝑉𝑉𝑉 𝐸𝐸𝐸𝐸𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (t) = � 1, 𝑖𝑖𝑖𝑖𝑓𝑓𝑓𝑓 𝑉𝑉𝑉𝑉𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 ≤ 207𝑉𝑉𝑉𝑉 0, 𝑜𝑜𝑜𝑜𝑡𝑡𝑡𝑡ℎ𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑖𝑖𝑖𝑖𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒
Where, 𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏 (t) : Desired tap position of SVR, 𝑉𝑉𝑉𝑉𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (t) : Optimal sending voltage, 𝑉𝑉𝑉𝑉𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (t) : Reference voltage of SVR(13,200V), 𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑖𝑖𝑖𝑖𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 : Tap interval of SVR(1.25%)
And also, when the SVR tap position is determined, the tap operation of the SVR is performed through comparison with the SVR tap position (𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏 𝑆𝑆𝑆𝑆𝑉𝑉𝑉𝑉𝑆𝑆𝑆𝑆 ). The conditional expression for the signal to be tap operated can be expressed by Eq. (3). That is, the tap operation is performed when the SVR tap operation signal is 1, and when the SVR tap operation signal 𝑒𝑒𝑒𝑒𝑏𝑏𝑏𝑏 (t)) is 0, the tab operation is not performed. 𝑒𝑒𝑒𝑒𝑏𝑏𝑏𝑏 (t) = �
1 𝑖𝑖𝑖𝑖𝑓𝑓𝑓𝑓 |𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏 (𝑡𝑡𝑡𝑡) − 𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏 𝑆𝑆𝑆𝑆𝑉𝑉𝑉𝑉𝑆𝑆𝑆𝑆 | ≠ 0 � 0 𝑜𝑜𝑜𝑜𝑡𝑡𝑡𝑡ℎ𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑖𝑖𝑖𝑖𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒
Where, 𝐸𝐸𝐸𝐸𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 : determination signal for charging and discharging of ESS, 𝑉𝑉𝑉𝑉𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 : customer voltage for i section in secondary feeder Under these concept, equation for the operation of the ESS is shown in Eq. (5). As final operation signal of ESS, it is occurred in case Tap operation signal and determination signal for charging and discharging of ESS Eq. (3) are determinate by violation of customer voltage. Here, when customer voltage is satisfied in nominal voltage boundary during the operation of SVR tap, ESS should be not operated.
(3)
Where, 𝑒𝑒𝑒𝑒𝑏𝑏𝑏𝑏 (t): tap operation signal of SVR, 𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏 𝑆𝑆𝑆𝑆𝑉𝑉𝑉𝑉𝑆𝑆𝑆𝑆 : existing tap location of SVR
σ(t) = 𝐸𝐸𝐸𝐸𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (𝑡𝑡𝑡𝑡) × 𝑒𝑒𝑒𝑒𝑏𝑏𝑏𝑏 (𝑡𝑡𝑡𝑡)
(5)
Where, σ(t) : Final operation signal for charging and discharging of ESS
4.2 Voltage control algorithm by SVR and ESS Operation of ESS by using the SVR control mode is shown in Fig. 8. At first, Load current of SVR which is calculated by load flow is assumed as operation reference value of BESS when customer voltage is exceeded to nominal voltage
Therefore, as mentioned earlier SVR and ESS operation procedure, This paper proposes the voltage control algorithm using the SVR and ESS as shown in Fig. 9. In other words, tap of SVR should be operated by LDC method when voltage problem like voltage fluctuation is occurred at the distribution system. In this case, tap is operated after the delay time (120sec) of SVR. Therefore, to keep customer voltage within nominal voltage boundary during the delay time of SVR, ESS is operated as charging mode when customer voltage should be lower than 207V or discharge mode when customer voltage should be upper than 213V.
boundary(220 ± 13V). And then, the compensation rate is calculated by relationship between operation reference value of ESS and load current per hours. After that, the operation (charging or discharging) of ESS should be determined. Finally, ESS is only operated by SVR tap signal and BESS signal during the delay time (120sec) of SVR.
Fig. 8. Operation block diagram of ESS Meanwhile, as shown in Eq. (4), when the consumer voltage is exceed than the upper limit value (233V), the ESS operation is determined as charging (σ(t) = −1) and the discharging
(4)
469
2019 IFAC CSGRES Jeju, Korea, June 10-12, 2019
Byungki Kim et al. / IFAC PapersOnLine 52-4 (2019) 431–436
435
Fig. 9. Voltage control algorithm by SVR and ESS
5. CASE STUDIES 5.1 Other Recommendations Based on the model primary feeder of Fig. 10, distribution parameter and section data of primary feeder are assumed as Table 1, respectively. The turn ratio of pole transformer (P.tr) is considered as 13200V/230V and also voltage drops at the first and last customers of secondary feeder are considered as 2% and 8% of rated voltage (220V). And also, load pattern and output of RES considering Photovoltaic system is assumed as shown in Fig.11.
(b) Output characteristic of PV system Fig. 11. Output pattern of PV system and customer 5.2 Verification for operation strategy of ESS and SVR In order to perform simulation analysis for customer voltage characteristic in secondary feeder introduced SVR and ESS, this paper confirms the operating characteristics of the ESS when the customer voltage should be lower than 233V or upper than 207V during the time delay of SVR using the PSCAD/EMTDC. Where, the operating time of the ESS is assumed to be from 12:00 to 18:00, considering the output pattern of the RES (Photovoltaic system). In case the customer voltage is not kept allowable limit, ESS can be operated during the only time delay of SVR by operation signal of ESS (σ(t)) in Fig. 12(a) by the determination signal of ESS (𝐸𝐸𝐸𝐸𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (𝑡𝑡𝑡𝑡)) as shown in Fig. 12(b) operation signal of tap operation signal of SVR(𝑒𝑒𝑒𝑒𝑏𝑏𝑏𝑏 (t)) expressed in Fig 12(c). Therefore, it is confirmed that the voltage control method by ESS and SVR based on the PSCAD/EMTDC has a validity and useful tool.
Fig. 10. Voltage control algorithm by SVR and ESS
Table 1. Simulation Data
(a) Charging and discharging operation signal of ESS(σ(t))
(a) Load characteristic of customer side
470
(b) Determination signal of ESS (𝐸𝐸𝐸𝐸𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (𝑡𝑡𝑡𝑡))
2019 IFAC CSGRES 436 Jeju, Korea, June 10-12, 2019
Byungki Kim et al. / IFAC PapersOnLine 52-4 (2019) 431–436
(c) Tap operation signal of SVR(𝑒𝑒𝑒𝑒𝑏𝑏𝑏𝑏 (t))
Fig. 14. Analysis of customer voltage characteristic by ESS and SVR operation
Fig. 12. Operation characteristic by the control modelling of ESS
6. CONCLUSIONS
5.3 Analysis of customer voltage characteristic by ESS and SVR operation
This paper has proposed the modeling of SVR and ESS based on the PSCAD/EMTDC and optimal coordination control method of SVR and ESS in primary feeder connected with the RES. The main results are summarized as follows.
(1) Customer voltage of primary feeder with SVR
(1) When SVR and ESS are introduced in primary feeder with RES, it is clear that customer voltage can be keep as reasonable conditions. And also, customer voltage can be exactly maintained within nominal voltage boundary according to operation of ESS during time delay of SVR.
Fig.13 is the customer voltage characteristic of secondary feeder at the end section in primary feeder interconnected with RES, and also SVR is located at section 3. Where, voltage characteristic is analyzed from 7 am to 2pm hourly considering output pattern of RES and load pattern, respectively. As a result of the simulation, it is confirm that customer voltage can be maintained as reasonable conditions. However, customer voltage cannot be exactly kept within nominal voltage boundary because voltage is not compensated during delay time of SVR.
(2) In order to analyze the criteria of customer voltage distributions, a performance index is carried out by 3 kinds method (Without SVR, With SVR, and With SVR and ESS). As result of the analysis, it is confirmed that voltage control method of SVR and ESS is improved more than existing SVR operation method. ACKNOWLEDGEMENTS This work was conducted under framework of the research and development program of the Korea Institute of Energy Research (B9-2421). REFERENCES [1] M.Y. Kim, Y.U. Song and K.H. Kim, “The Advanced Voltage Regulation Method for ULTC in Distribution Systems with DG”, JEET, vol. 8 issue 4, pp. 737-743,2013
Fig. 13. Analysis of customer voltage characteristic by SVR operation (2) Customer voltage of primary feeder with SVR and ESS Fig.14 is the customer voltage characteristic of secondary feeder at the end section in primary feeder connected with RES. And also, SVR and ESS is located at section 3. As a result of the simulation, it is clear that customer voltage can be maintained as proper conditions when SVR and ESS is introduced in primary feeder with RES, and also, customer voltage can be exactly maintained within nominal voltage boundary during delay time of SVR by coordination operation of SVR and ESS. Therefore, it is confirmed that the coordination operation of SVR and BESS can make the customer voltage of primary feeder with RES keep better voltage conditions.
471
[2] C. Kao and C.-L. Chyu, “Least-squares estimate in fuzzy regression analysis,” European Journal of Operational Research”, vol. 148, no. 2, pp. 426-435, 2003. [3] D.S. Rho, K.S. Kook and Y.P. Wang, “Optimal Algorithms for Voltage Management in Distribution Systems Interconnected with New Dispersed Sources”, JEET, vol. 6, No 2, pp. 192-201, 2011 [4] Vasileios A. Evangelopoilos et al. “Optimal operation of smart distribution networks: A review of models, methods and future research”, Electric Power Systems Research 140, pp.95106, 2016.
ScienceDirect
IFAC PapersOnLine 52-4 (2019) 431–436
A Study on the Voltage Control Method of Primary Feeder by the Energy A Study on the Voltage Control Method of Primary Feeder by the Energy A Study on the Voltage Control Method of Primary Feeder by the Energy Storage System and Step Voltage Regulator A Study on the Voltage Control Method of Primary Feeder by the Energy System and Step Voltage Regulator A Study on the Storage Voltage Control Method of Primary Feeder by the Energy Storage System and Step Voltage Regulator Storage System and Step Voltage Regulator Storage System andRyu*, StepDae-Jin Voltage Byungki Kim*, Kyung-Sang Kim*,Regulator Yang-Hyun Nam*,
Byungki Kim*, Kyung-Sang Ryu*, Dae-Jin Kim*, Yang-Hyun Nam*, Byungki Kim*, Kyung-Sang Ryu*, Dae-Jin Kim*, Yang-Hyun Nam*, Heesang Ko*, Ho-Chan Kim** Byungki Kim*, Kyung-Sang Ryu*, Dae-Jin Kim*, Yang-Hyun Nam*, Byungki Kim*, Kyung-Sang Ryu*, Dae-Jin Kim*, Yang-Hyun Nam*, Heesang Ko*, Ho-Chan Kim** Byungki Kim*, Kyung-Sang Ryu*, Dae-Jin Kim*, Yang-Hyun Nam*, Heesang Ko*, Ho-Chan Kim** Heesang Ko*, Ho-Chan Kim** Heesang Ko*, Ho-Chan Kim** Heesang Ko*, Ho-Chan Kim** *Energy Systems Integration Laboratory, Korea Institute of Energy Research, Jeju, Korea *Energy Systems Integration Laboratory, Korea Institute of Energy Research, Jeju, Korea *Energy Systems Integration Laboratory, Korea Institute of Energy Research, Jeju, Korea (e-mail:[email protected], [email protected], [email protected], [email protected], [email protected] ) *Energy Systems Integration Laboratory, Korea Institute of Energy Research, Jeju, Korea *Energy Systems Integration Laboratory, Korea Institute of Energy Research, Jeju, Korea (e-mail:[email protected], [email protected], [email protected], [email protected], [email protected] )) *Energy Systems Integration Laboratory, Korea Institute of Energy Research, Jeju, Korea (e-mail:[email protected], [email protected], [email protected], [email protected], [email protected] **Department of Electrical Engineering, Jeju National University, Jeju, Korea (e-mail:[email protected], [email protected], [email protected], [email protected], [email protected] )) (e-mail:[email protected], [email protected], [email protected], [email protected], [email protected] **Department of Electrical Engineering, Jeju National University, Jeju, Korea (e-mail:[email protected], [email protected], [email protected], [email protected], [email protected] ) **Department of Engineering, Jeju University, Korea (e-mail: [email protected]) **Department of Electrical Electrical Engineering, Jeju National National University, Jeju, Jeju, Korea **Department of Electrical Engineering, Jeju National University, Jeju, Korea (e-mail: [email protected]) **Department of Electrical Engineering, Jeju National University, Jeju, Korea (e-mail: [email protected]) (e-mail: [email protected]) [email protected]) (e-mail: (e-mail: [email protected]) Abstract: In order to keep the customer voltages within nominal voltage boundary (220±6%), operation Abstract: In order to keep the customer voltages within nominal voltage boundary (220±6%), operation Abstract: order to keep the customer voltages within voltage boundary (220±6%), operation method ofIn SVR(Step Voltage Regulator) at primary feedernominal is very important considering the scheduled tap Abstract: In order to keep the customer voltages within nominal voltage boundary (220±6%), operation Abstract: In order to keep the customer voltages within nominal voltage boundary (220±6%), operation method of SVR(Step Voltage Regulator) at primary feeder is very important considering the scheduled tap Abstract: In order toof keep theHowever, customerthe voltages within nominal voltage boundary (220±6%), operation method of SVR(Step Voltage Regulator) at primary feeder is very important considering the scheduled tap time delay(120 sec) SVR compensation of voltage during the tap delay time of SVR is method of SVR(Step Voltage Regulator) at primary feeder is very important considering the scheduled tap method of SVR(Step Voltage Regulator) at primary feeder is very important considering the scheduled tap time delay(120 sec) of SVR However, the compensation of voltage during the tap delay time of SVR is method of SVR(Step Voltage Regulator) at primary feeder is very important considering the scheduled tap time delay(120 sec) of SVR However, the compensation of voltage during the tap delay time of SVR is being required at primary feeder introduced in RES (Renewable Energy Recourse). Because customer time delay(120 sec) of SVR However, the compensation of voltage during the tap delay time of SVR is time delay(120 sec) of SVR However, the compensation of voltage during the tap delay time of SVR is being required at primary feeder introduced in RES (Renewable Energy Recourse). Because customer time delay(120 sec) of SVR However, the compensation of voltage during the tap delay time of SVR is being required at primary feeder introduced in RES (Renewable Energy Recourse). Because customer voltage should be to exceed nominal voltage boundary during the operated time of RES. Therefore, in order being required required at to primary feeder introduced in RES RES during (Renewable Energytime Recourse). Because customer customer being at primary feeder introduced in (Renewable Energy Recourse). Because voltage should be exceed nominal voltage boundary the operated of RES. Therefore, in order being required at primary feeder introduced in RES (Renewable Energy Recourse). Because customer voltage should be to exceed nominal voltage boundary during the operated time of RES. Therefore, in order to keep the secondary feeder voltage within nominal voltage boundary at all the time, this paper proposed voltage should be to to exceed exceed nominal voltage boundary during boundary the operated operated time oftime, RES.this Therefore, in order order voltage be nominal voltage boundary during the time of RES. Therefore, in to keep should the secondary feeder voltage within nominal voltage at all the paper proposed voltage should be tomethod exceed during boundary the operated time RES. Therefore, in order to the secondary feeder voltage within nominal at the this paper the voltage innominal primary feeder boundary by using voltage coordination control algorithm between ESSproposed (Energy to keep keep the control secondary feeder voltagevoltage within nominal voltage boundary at all all theoftime, time, this paper proposed to keep the secondary feeder voltage within nominal voltage boundary at all the time, this paper proposed the voltage control method in primary feeder by using coordination control algorithm between ESS (Energy to keep the secondary feeder voltage within boundary at all the time, paper the voltage control method in primary feeder by coordination control algorithm between ESS (Energy Storage System) and SVR. From the simulation resultsvoltage analysis of customer voltages bythis presenting voltage the voltage control method in primary feeder nominal by using using coordination control algorithm between ESSproposed (Energy the voltage control method in primary feeder by using coordination control algorithm between ESS (Energy Storage System) and SVR. From the simulation results analysis of customer voltages by presenting voltage the voltage control method in primary feeder by using coordination control algorithm between ESS (Energy Storage System) and SVR. From the simulation results analysis of customer voltages by presenting control method between ESS and SVR based on the PSCAD/EMTDC, it is confirmed that customer voltage Storage System) and SVR. From the simulation results analysis of customer voltages by presenting voltage Storage System) and SVR. From the simulation results analysis of customer voltages by presenting control method between ESS and SVR based on the PSCAD/EMTDC, it is confirmed that customer voltage Storage System) and SVR. From the simulation results analysis voltages by presenting control method between ESS and SVR based on the PSCAD/EMTDC, it is confirmed that customer voltage in distribution system can be maintained within allowable limit.of customer control method between ESS and SVR based on the PSCAD/EMTDC, it is confirmed that customer voltage control method between ESS and SVR on PSCAD/EMTDC, it in distribution can be maintained within allowable limit. control methodsystem between ESS and SVR based based on the the PSCAD/EMTDC, it is is confirmed confirmed that that customer customer voltage voltage in distribution system can be maintained within allowable limit. in distribution system can be maintained within allowable limit. in distribution system can be maintained within allowable limit. © 2019, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved. Keywords: Step Voltage Regulator, Coordination Contorl Algorithm, Energy Storage System, in distribution system can be maintained within allowable limit. Keywords: Step Voltage Regulator, Coordination Contorl Algorithm, Energy Storage System, Keywords: Step Step Voltage Voltage Regulator, Regulator, Coordination Coordination Contorl Contorl Algorithm, Algorithm, Energy Energy Storage Storage System, System, PSCAD/EMDC Keywords: Keywords: Step Voltage Regulator, Coordination Contorl Algorithm, Energy Storage System, PSCAD/EMDC Keywords: Step Voltage Regulator, Coordination Contorl Algorithm, Energy Storage System, PSCAD/EMDC PSCAD/EMDC PSCAD/EMDC PSCAD/EMDC during the tap change delay time of SVR. That is, when the 1. INTRODUCTION during the tap change delay time of SVR. That is, when the during the tap change delay of SVR. That when the acceptance voltage is out of time tolerance during theis, tap change 1. INTRODUCTION during the tap change delay time of SVR. That is, when the 1. INTRODUCTION during the tap change delay time of SVR. That is, when the acceptance voltage is out of tolerance during the tap change 1. INTRODUCTION the tap change delay time of SVR. That is, when the acceptance voltage is out of tolerance during the tap change delay time of SVR to solve the voltage problem due to As power systems 1. have been decentralized according to the during INTRODUCTION acceptance voltage is out of tolerance during the tap change 1. INTRODUCTION acceptance voltage is out of tolerance during the tap change delay time of SVR to solve the voltage problem due to the As power systems have been decentralized according to the acceptance voltage is out of tolerance during the tap change delay time of SVR to solve the voltage problem due to the renewable energy and the load fluctuation, the voltage problem As power systems have been decentralized according to the technology development of renewable energy resource, RES delay time of SVR to solve the voltage problem due to the As power systems have been decentralized according to the delay time of SVR to solve the voltage problem due to the renewable energy and the load fluctuation, the voltage problem As power systems have been decentralized according to the technology development of renewable energy resource, RES delay time of SVR to solve the voltage problem due to renewable energy and the load fluctuation, the voltage problem is solved through charging and discharging operation of the As power systems have been decentralized according to the technology development of renewable energy resource, RES have been actively introduced and operated in primary feeder. renewable energy and the load fluctuation, the voltage problem technology development of renewable energy resource, RES renewable energy and the load fluctuation, the voltage problem is solved through charging and discharging operation of the technology development of renewable energy resource, RES have been actively introduced and operated in primary feeder. renewable energy and the load fluctuation, the operation voltage problem is through charging and discharging of having a quick response. technology development of renewable energy resource, RES have been actively introduced and operated in primary feeder. However, many power quality problems case RES are ESS is solved solved through charging and discharging operation of the the have been actively introduced and operated in primary feeder. is solved through charging and discharging operation of ESS having aa quick response. have been actively introduced and operated in primary feeder. However, many power quality problems case RES are is solved through charging and discharging operation of the the ESS having quick response. Based on the issues earlier, this paper proposes the optimal have been actively introduced and operated in primary feeder. However, many power quality problems case RES are connected in primary feeder including secondary feeder may ESS having a quick quick response. However, in many power quality problems in case casefeeder RES may are ESS having a response. Based on the issues earlier, this paper proposes the optimal However, many power quality problems in RES are connected primary feeder including secondary ESS having a quick response. Based on the issues earlier, this paper proposes the optimal voltage control method in primary feeder by using ESS and However, many power quality problems in case RES are connected in primary feeder including secondary feeder may be occurred such as voltage variations, flicker and harmonic in Based on on the issues issues earlier, this paper paper proposes theESS optimal connected insuch primary feedervariations, includingflicker secondary feeder may may Based the earlier, this proposes the optimal voltage control method in primary feeder by using and connected in primary feeder including secondary feeder be occurred as voltage and harmonic in Based on thetoissues earlier, this paper proposes theESS optimal voltage control method in feeder by using and in order maintain theprimary customer voltage within nominal connected insuch primary feeder including secondary feeder may be occurred as variations, flicker and harmonic in variety. Where, this paper deals with voltage management of voltage control method in primary feeder by using ESS and be occurred such as voltage voltage variations, flicker and harmonic in SVR voltage control method in primary feeder by using ESS and SVR in order to maintain the customer voltage within nominal be occurred such as voltage variations, flicker and harmonic in variety. Where, this paper deals with voltage management of control method in primary feeder by using ESS and SVR in order to maintain the customer voltage within nominal voltage boundary at all the time. From the modeling by the be occurred such as voltage variations, flicker and harmonic in variety. Where, this paper deals with voltage management of the many issues in order to keep the secondary feeder voltage SVR in order to maintain the customer voltage within nominal variety. Where, this paper deals with voltage management of SVR in order to maintain the customer voltage within nominal voltage boundary at all the time. From the modeling by the variety. Where, this paper deals with voltage management of the many issues in order to keep the secondary feeder voltage SVR in order to maintain the customer voltage within nominal voltage boundary at all the time. From the modeling by the PSCAD/EMTDC and simulation analysis adapted in operation variety. Where, this paper deals with voltage management of the many issues in order to keep the secondary feeder voltage voltage boundary at all the time. From the modeling by the within nominal voltage boundary (allowable limit: 220±6%) the many issues in order to keep the secondary feeder voltage voltage boundary at all the time. From the modeling by the PSCAD/EMTDC and simulation analysis adapted in operation the many issues in order to keep the secondary feeder voltage within nominal voltage boundary (allowable limit: 220±6%) voltage boundary at all the time. From the modeling by the PSCAD/EMTDC and simulation analysis adapted in operation strategy of SVR and ESS, it is confirmed that customer voltage the many issues in order to keep the secondary feeder voltage within nominal voltage boundary (allowable limit: 220±6%) PSCAD/EMTDC and simulation analysis adapted in operation PSCAD/EMTDC and simulation analysis adapted in operation using SVR and ESS. strategy of SVR and ESS, it is confirmed that customer voltage within nominal voltage boundary (allowable limit: 220±6%) within nominal voltage boundary (allowable limit: 220±6%) PSCAD/EMTDC and simulation analysis adapted in operation strategy of SVR and ESS, it is confirmed that customer voltage in primary feeder can be kept within nominal voltage boundary. using SVR and ESS. within nominal voltage (allowable limit: 220±6%) of SVR and ESS, it iswithin confirmed that customer voltage using and strategy of SVR ESS, it confirmed that customer voltage In a SVR distribution systemboundary where existing renewable energy is strategy in primary can be kept nominal boundary. using SVR and ESS. ESS. strategy of feeder SVR and and it is iswithin confirmed that voltage customer voltage in feeder can be nominal voltage boundary. using and ESS. In aa SVR distribution system where existing renewable energy is in primary primary feeder canESS, be kept kept within nominal voltage boundary. using SVR and ESS. In distribution system where existing renewable energy is in primary feeder can be kept within nominal voltage boundary. not linked, the SVR is installed and operated at a point where In a distribution system where existing renewable energy is in primary feeder can be kept within nominal voltage boundary. In a distribution system where existing renewable energy is not linked, the SVR is installed and operated at a point where 2. VOLTAGE CONTROL OF ESS DEPENDING ON SVR In linked, avoltage distribution system where existing renewable energy is not the SVR is installed and operated at aa point where the drop exceeds 5% in the long distance primary not linked, the SVR is installed and operated at where 2. VOLTAGE CONTROL OF ESS DEPENDING ON SVR not linked, the SVR is installed and operated at aa point point where the voltage drop exceeds 5% in the long distance primary 2. VOLTAGE CONTROL OF ESS DEPENDING ON SVR CONTROL MODE not linked, the SVR is installed and operated at point where the voltage drop exceeds 5% in the long distance primary feeder. In addition, studies are underway to stabilize the 2. VOLTAGE CONTROL OF ESS DEPENDING ON SVR the voltage drop exceeds 5% in the long distance primary 2. VOLTAGE CONTROL OF ESS DEPENDING ON SVR CONTROL MODE the voltage drop exceeds 5% in the long distance primary feeder. In addition, studies are underway to stabilize the 2. VOLTAGE CONTROL OF ESS DEPENDING ON SVR CONTROL MODE the voltage drop exceeds 5% in the long distance primary feeder. In addition, studies are underway to stabilize the voltage instability of the distribution system caused by CONTROL MODE feeder. In addition, studies are underway to stabilize the Generally, Tap position decision of SVR is considered by CONTROL MODE feeder. In addition, studies are underway to stabilize the voltage instability of the distribution system caused by CONTROL MODE feeder. In addition, studies are underway to stabilize the voltage instability of the distribution system caused by linkage of RES through various operation algorithms of SVR. Generally, Tap position decision of SVR is considered by voltage instability of the distribution system caused by the Generally, Tap position decision of SVR is considered by compensation-rate according to the relationship between voltage instability of the distribution system caused by the linkage of RES through various operation algorithms of SVR. Generally, Tap position decision of SVR is considered by voltage instability of the distribution system caused by the linkage of RES through various operation algorithms of SVR. However, since the SVR installed in the current distribution Generally, Tap position decision of SVR is considered by compensation-rate according to the relationship between linkage of RES RES through various operation algorithms of SVR. SVR. sending Generally, Tap position decision of SVR is considered by compensation-rate according to the relationship between voltage by Line Drop Compensation method and linkage of through various operation algorithms of However, since the SVR installed in the current distribution compensation-rate according to the relationship between linkage of RES through various operation algorithms of SVR. However, since the SVR installed in the current distribution system is composed of mechanical elements, the tap change to compensation-rate according to the relationship between sending voltage by Line Drop Compensation method and However, since the theofSVR SVR installedelements, in the the current current distribution compensation-rate according to the relationship between sending voltage by Line Drop Compensation method and reference tap (13200V) among the 17 tap of SVR. And then, However, since installed in distribution system is composed mechanical the tap change to sending voltage by Line Drop Compensation method and However, since the installed in the current distribution system is of mechanical the change to solve the voltage problem does notelements, operate immediately sending voltage by Drop Compensation method and reference tap (13200V) among the 17 tap of SVR. And then, system is composed composed ofSVR mechanical elements, the tap tap changeand to tap sending voltage by Line Line Droptime Compensation method and reference tap (13200V) the 17 tap of SVR. And then, is controlled after theamong delay (120sec) of SVR after tap system is composed of mechanical elements, the tap change to solve the voltage problem does not operate immediately and reference tap (13200V) among the 17 tap of SVR. And then, system is composed of mechanical elements, the tap change to solve the voltage problem does not operate immediately and operates after a delay time of about 120 seconds. For this reference tap (13200V) among the 17 tap of SVR. And then, tap is controlled after the delay time (120sec) of SVR after tap solve the voltage problem does not operate immediately and reference tap (13200V) among the 17 tap of SVR. And then, tap is controlled after the delay time (120sec) of SVR after tap operation decision according to the voltage variation rate. solve the voltage problem does not operate immediately and operates after a delay time of about 120 seconds. For this tap is controlled controlled afteraccording the delay delay to time (120sec) ofvariation SVR after afterrate. tap solve the voltage problem does not operate immediately and operates after time of about 120 seconds. For this reason, there isaaa delay possibility that the voltage will deviate from tap is after the time (120sec) of SVR tap operation decision the voltage operates after delay time of about 120 seconds. For this tap is controlled after the delay time (120sec) of SVR after tap operation decision according to the voltage variation rate. However under voltage and over voltage could be occurred operates after a delay time of about 120 seconds. For this reason, there is a possibility that the voltage will deviate from operation under decision according to the the voltage variation rate. operates after a delay time of about 120 seconds. For this reason, there is a possibility that the voltage will deviate from the allowable limit during the delay time for the tap change of operation decision according to voltage variation rate. However voltage and over voltage could be occurred reason, there is aa possibility that the voltage will deviate from operation decision according to the voltage variation rate. However under voltage and over voltage could be occurred during the delay time when is state before tap operation of reason, there is possibility that the voltage will deviate from the allowable limit during the delay time for the tap change of However under voltage and over over voltage could be occurred occurred reason, there islimit a possibility that the time voltage will deviate from the allowable during the delay for the tap change of SVR. However under voltage and voltage could be during the delay time when is state before tap operation of the allowable limit during the delay time for the tap change of However under voltage and over voltage could bethis occurred during the delay time when is state before tap operation of SVR. In order to overcome these problems, paper the allowable limit during the delay time for the tap change of SVR. during the delay time when is state before tap operation of the allowable limit during the delay time for the tap change SVR. Therefore, the voltage compensation during the delay time of during the delay time when is state before tap operation of SVR. In order to overcome these problems, this paper SVR. during the delay time when is state before tap operation of SVR. In order to overcome these problems, this paper presents voltage control method by ESS during the time delay SVR. Therefore, the voltage compensation during the delay time of SVR. In order to overcome these problems, this paper SVR. Therefore, the voltage compensation during the delay time of SVR is being required because the customer voltages have a SVR. In order to overcome these problems, this paper presents voltage control method by ESS during the time delay Therefore, therequired voltage because compensation during the the delay time time ofa of SVR. In order to overcome these problems, this paper presents voltage control method by ESS during the time delay SVR tap operation as shown in Fig. 1. Therefore, the voltage compensation during delay of SVR is being the customer voltages have voltage control method by ESS during the time delay Therefore, voltage compensation during the delay time ofaa presents SVR is because the voltages have difficultly tothe berequired kept within the nominal voltage boundary. presents voltage control method by ESS during of SVR tap operation as shown in SVR is being being required because the customer customer voltages haveIn presents voltage control method byFig. ESS1. during the the time time delay delay SVR tap operation as shown in Fig. 1. SVR is being required because the customer voltages have aa of difficultly to be kept within the nominal voltage boundary. In of SVR tap operation as shown in Fig. 1. SVR is being required because the customer voltages have difficultly be within nominal voltage In this paper,to is used to the solve problems thatboundary. may occur difficultly toESS be kept kept within the nominal voltage boundary. In of of SVR SVR tap tap operation operation as as shown shown in in Fig. Fig. 1. 1. difficultly to be kept within the nominal voltage boundary. In this paper, ESS is used to solve problems that may occur difficultly be kept within nominal voltage In this paper, is to solve problems that may this paper,toESS ESS is used used to the solve problems thatboundary. may occur occur this this paper, paper, ESS ESS is is used used to to solve solve problems problems that that may may occur occur
2405-8963 © IFAC (International Federation of Automatic Control) Copyright © 2019, 2019 IFAC 466Hosting by Elsevier Ltd. All rights reserved. Copyright 2019 responsibility IFAC 466Control. Peer review©under of International Federation of Automatic Copyright © 2019 IFAC 466 Copyright © 466 10.1016/j.ifacol.2019.08.248 Copyright © 2019 2019 IFAC IFAC 466 Copyright © 2019 IFAC 466
2019 IFAC CSGRES 432 Jeju, Korea, June 10-12, 2019
Byungki Kim et al. / IFAC PapersOnLine 52-4 (2019) 431–436
Fig.3 LDC Modeling of SVR Using the electrical modeling for LDC method of SVR as mentioned earlier, the control modeling for tap up and tap down with the bandwidth of 50% and scheduled delay time of 120 seconds is designed as shown in Fig.4.
Fig. 1. Voltage control in primary feeder by the SVR and ESS First of all, if the secondary feeder voltages are dropped than lower limit, ESS is carried out chagrining state. And also, when secondary feeder voltage should be raised than upper limit, ESS is operated as discharging state. As mentioned earlier, role of ESS as voltage stabilization function is kept within the nominal voltage boundary at secondary feeder voltage during the time delay (120sec) of SVR tap. 3. MODELING OF PRIMARY FEEDER WITH SVR AND ESS USING PSCAD/EMTDC
(a) Up tap logic
In order to analyze characteristic of customer voltage according to ESS and SVR operation, modeling of primary feeder with ESS, SVR and RES is designed by PSCAD/EMTDC as shown in Fig.2. Here, primary and secondary feeder are composed of total 6 section with RES at the end section And also, ESS and SVR are located in end point of section 3 in primary feeder. (b) Down tap logic Fig.4. Tap up and tap down logic of SVR 3.2 Modeling of ESS ESS is modeled with battery, DC-DC converter, inverter and transformer. Firstly, the battery that can adjust the parameters such as the initial SOC(State Of Charge) and the capacity is connected to the DC-DC converter. The DC-DC converter can determine the charging / discharging of the ESS. It operates as a buck converter when charging, and as a boost converter when discharging as shown in Fig. 5.
Fig. 2. Distribution system using the PSCAD/EMTDC 3.1 Modeling of SVR Decision for optimal sending voltage of SVR is very important to modeling of SVR. Therefore this paper presents modeling method for optimal sending voltage setting values of LDC method by the statistical analysis compared with ideal optimal sending voltages and total load currents. Under these concept, the SVR for electrical factor of LDC method is modeled by PSCAD/EMTDC as shown in Fig. 3. 467
2019 IFAC CSGRES Jeju, Korea, June 10-12, 2019
Byungki Kim et al. / IFAC PapersOnLine 52-4 (2019) 431–436
433
(a) Buck/Boost converter modeling
(b) Control algorithm (b) Upper level control of DC-DC converter Fig. 6. ESS modeling Fig. 5. Modeling of ESS 4. VOLTAGE CONTROL METHOD OF SVR AND ESS
The output of the DC-DC converter is connected to the inverter through a DC-link, and the inverter controls the DC voltage on DC link and reactive power. The AC / DC conversion of voltage and current is also performed in the inverter and the output of inverter is connected to the transformer. The transformer converts the voltage level to the system and transfers power to the system. Figure 6 shows the overall configuration of an ESS consisting of a battery, a converter, an inverter, and a transformer.
4.1 SVR control algorithm LDC method of SVR which is located in primary feeder to compensate the voltage variations is to find the optimal setting values (Vce, Zeq) and optimal sending voltages in order to deliver suitable voltages to many customers as possible as shown in Eq. (1). It firstly determines the ideal optimal sending voltages which can be expressed by the optimal compensation rates of SVR, and then obtains optimal setting values by statistical analysis according to the relationship between ideal optimal sending voltages and total load currents. 𝑉𝑉𝑉𝑉𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (𝑡𝑡𝑡𝑡) = 𝑉𝑉𝑉𝑉𝑐𝑐𝑐𝑐𝑠𝑠𝑠𝑠 + 𝑍𝑍𝑍𝑍𝑠𝑠𝑠𝑠𝑒𝑒𝑒𝑒 × 𝐼𝐼𝐼𝐼𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑠𝑠𝑠𝑠𝑏𝑏𝑏𝑏 (𝑡𝑡𝑡𝑡)
Fig. 6. ESS modeling
(1)
As mentioned earlier, tap decision of SVR is considered by compensation-rate according to the relationship between sending voltage for LDC method and reference tap(13200V) of SVR, and then tap should be operated when is violated to bandwidth(50%) during the time delay(120sec) as shown in Fig.7. Here, left box is SVR control part by input of LDC method including measuring element and predetermined, Vce and Zeq, and also right box is tap operation part by control signal to be occurred in the control part.
3.3 Modeling of PV PV is briefly modeled using VSC(Voltage Source Converter) and a current source, and the power from solar power is replaced by a current source as shown in Fig 7(a). The current source depends on the amount of power. The control strategy is presented in Fig. 7(b). The voltage and current of the grid are decomposed into a direct component and a quadrature component through a park transform and PLL. Here, The direct component of current id regulates the active power and the quadrature component of current iq controls the reactive power. On the other hand, the six pulse waveforms for driving the IGBT are obtained by using the inverse Park transform of id, iq and set point values vd, vq.
Fig. 7. Operation block diagram of SVR (a) PV system
468
2019 IFAC CSGRES 434 Jeju, Korea, June 10-12, 2019
Byungki Kim et al. / IFAC PapersOnLine 52-4 (2019) 431–436
Here, 𝑓𝑓𝑓𝑓𝑏𝑏𝑏𝑏 (t) is tap operation signal for motor drive unit of. And also 𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏 (t) is tap changing signal according to tap position determination as follows Eq. (2) 𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏 (t) =
𝑉𝑉𝑉𝑉𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (𝑡𝑡𝑡𝑡)−𝑉𝑉𝑉𝑉𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 𝑉𝑉𝑉𝑉𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠−𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏𝑇𝑇𝑇𝑇𝑖𝑖𝑖𝑖𝑠𝑠𝑠𝑠𝑖𝑖𝑖𝑖
mode operation (σ(t) = 1) is performed when the voltage is kept below the lower limit (207V). Where, in order to operate the ESS installed on the primary feeder, it is assumed that the first customer voltage and last customer voltage of secondary feeder terminal can be checked in real time by the measuring device.
(2)
−1 𝑖𝑖𝑖𝑖𝑓𝑓𝑓𝑓 𝑉𝑉𝑉𝑉𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 ≥ 233𝑉𝑉𝑉𝑉 𝐸𝐸𝐸𝐸𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (t) = � 1, 𝑖𝑖𝑖𝑖𝑓𝑓𝑓𝑓 𝑉𝑉𝑉𝑉𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 ≤ 207𝑉𝑉𝑉𝑉 0, 𝑜𝑜𝑜𝑜𝑡𝑡𝑡𝑡ℎ𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑖𝑖𝑖𝑖𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒
Where, 𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏 (t) : Desired tap position of SVR, 𝑉𝑉𝑉𝑉𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (t) : Optimal sending voltage, 𝑉𝑉𝑉𝑉𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (t) : Reference voltage of SVR(13,200V), 𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑖𝑖𝑖𝑖𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 : Tap interval of SVR(1.25%)
And also, when the SVR tap position is determined, the tap operation of the SVR is performed through comparison with the SVR tap position (𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏 𝑆𝑆𝑆𝑆𝑉𝑉𝑉𝑉𝑆𝑆𝑆𝑆 ). The conditional expression for the signal to be tap operated can be expressed by Eq. (3). That is, the tap operation is performed when the SVR tap operation signal is 1, and when the SVR tap operation signal 𝑒𝑒𝑒𝑒𝑏𝑏𝑏𝑏 (t)) is 0, the tab operation is not performed. 𝑒𝑒𝑒𝑒𝑏𝑏𝑏𝑏 (t) = �
1 𝑖𝑖𝑖𝑖𝑓𝑓𝑓𝑓 |𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏 (𝑡𝑡𝑡𝑡) − 𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏 𝑆𝑆𝑆𝑆𝑉𝑉𝑉𝑉𝑆𝑆𝑆𝑆 | ≠ 0 � 0 𝑜𝑜𝑜𝑜𝑡𝑡𝑡𝑡ℎ𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑖𝑖𝑖𝑖𝑒𝑒𝑒𝑒𝑒𝑒𝑒𝑒
Where, 𝐸𝐸𝐸𝐸𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 : determination signal for charging and discharging of ESS, 𝑉𝑉𝑉𝑉𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 : customer voltage for i section in secondary feeder Under these concept, equation for the operation of the ESS is shown in Eq. (5). As final operation signal of ESS, it is occurred in case Tap operation signal and determination signal for charging and discharging of ESS Eq. (3) are determinate by violation of customer voltage. Here, when customer voltage is satisfied in nominal voltage boundary during the operation of SVR tap, ESS should be not operated.
(3)
Where, 𝑒𝑒𝑒𝑒𝑏𝑏𝑏𝑏 (t): tap operation signal of SVR, 𝑇𝑇𝑇𝑇𝑏𝑏𝑏𝑏 𝑆𝑆𝑆𝑆𝑉𝑉𝑉𝑉𝑆𝑆𝑆𝑆 : existing tap location of SVR
σ(t) = 𝐸𝐸𝐸𝐸𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (𝑡𝑡𝑡𝑡) × 𝑒𝑒𝑒𝑒𝑏𝑏𝑏𝑏 (𝑡𝑡𝑡𝑡)
(5)
Where, σ(t) : Final operation signal for charging and discharging of ESS
4.2 Voltage control algorithm by SVR and ESS Operation of ESS by using the SVR control mode is shown in Fig. 8. At first, Load current of SVR which is calculated by load flow is assumed as operation reference value of BESS when customer voltage is exceeded to nominal voltage
Therefore, as mentioned earlier SVR and ESS operation procedure, This paper proposes the voltage control algorithm using the SVR and ESS as shown in Fig. 9. In other words, tap of SVR should be operated by LDC method when voltage problem like voltage fluctuation is occurred at the distribution system. In this case, tap is operated after the delay time (120sec) of SVR. Therefore, to keep customer voltage within nominal voltage boundary during the delay time of SVR, ESS is operated as charging mode when customer voltage should be lower than 207V or discharge mode when customer voltage should be upper than 213V.
boundary(220 ± 13V). And then, the compensation rate is calculated by relationship between operation reference value of ESS and load current per hours. After that, the operation (charging or discharging) of ESS should be determined. Finally, ESS is only operated by SVR tap signal and BESS signal during the delay time (120sec) of SVR.
Fig. 8. Operation block diagram of ESS Meanwhile, as shown in Eq. (4), when the consumer voltage is exceed than the upper limit value (233V), the ESS operation is determined as charging (σ(t) = −1) and the discharging
(4)
469
2019 IFAC CSGRES Jeju, Korea, June 10-12, 2019
Byungki Kim et al. / IFAC PapersOnLine 52-4 (2019) 431–436
435
Fig. 9. Voltage control algorithm by SVR and ESS
5. CASE STUDIES 5.1 Other Recommendations Based on the model primary feeder of Fig. 10, distribution parameter and section data of primary feeder are assumed as Table 1, respectively. The turn ratio of pole transformer (P.tr) is considered as 13200V/230V and also voltage drops at the first and last customers of secondary feeder are considered as 2% and 8% of rated voltage (220V). And also, load pattern and output of RES considering Photovoltaic system is assumed as shown in Fig.11.
(b) Output characteristic of PV system Fig. 11. Output pattern of PV system and customer 5.2 Verification for operation strategy of ESS and SVR In order to perform simulation analysis for customer voltage characteristic in secondary feeder introduced SVR and ESS, this paper confirms the operating characteristics of the ESS when the customer voltage should be lower than 233V or upper than 207V during the time delay of SVR using the PSCAD/EMTDC. Where, the operating time of the ESS is assumed to be from 12:00 to 18:00, considering the output pattern of the RES (Photovoltaic system). In case the customer voltage is not kept allowable limit, ESS can be operated during the only time delay of SVR by operation signal of ESS (σ(t)) in Fig. 12(a) by the determination signal of ESS (𝐸𝐸𝐸𝐸𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (𝑡𝑡𝑡𝑡)) as shown in Fig. 12(b) operation signal of tap operation signal of SVR(𝑒𝑒𝑒𝑒𝑏𝑏𝑏𝑏 (t)) expressed in Fig 12(c). Therefore, it is confirmed that the voltage control method by ESS and SVR based on the PSCAD/EMTDC has a validity and useful tool.
Fig. 10. Voltage control algorithm by SVR and ESS
Table 1. Simulation Data
(a) Charging and discharging operation signal of ESS(σ(t))
(a) Load characteristic of customer side
470
(b) Determination signal of ESS (𝐸𝐸𝐸𝐸𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (𝑡𝑡𝑡𝑡))
2019 IFAC CSGRES 436 Jeju, Korea, June 10-12, 2019
Byungki Kim et al. / IFAC PapersOnLine 52-4 (2019) 431–436
(c) Tap operation signal of SVR(𝑒𝑒𝑒𝑒𝑏𝑏𝑏𝑏 (t))
Fig. 14. Analysis of customer voltage characteristic by ESS and SVR operation
Fig. 12. Operation characteristic by the control modelling of ESS
6. CONCLUSIONS
5.3 Analysis of customer voltage characteristic by ESS and SVR operation
This paper has proposed the modeling of SVR and ESS based on the PSCAD/EMTDC and optimal coordination control method of SVR and ESS in primary feeder connected with the RES. The main results are summarized as follows.
(1) Customer voltage of primary feeder with SVR
(1) When SVR and ESS are introduced in primary feeder with RES, it is clear that customer voltage can be keep as reasonable conditions. And also, customer voltage can be exactly maintained within nominal voltage boundary according to operation of ESS during time delay of SVR.
Fig.13 is the customer voltage characteristic of secondary feeder at the end section in primary feeder interconnected with RES, and also SVR is located at section 3. Where, voltage characteristic is analyzed from 7 am to 2pm hourly considering output pattern of RES and load pattern, respectively. As a result of the simulation, it is confirm that customer voltage can be maintained as reasonable conditions. However, customer voltage cannot be exactly kept within nominal voltage boundary because voltage is not compensated during delay time of SVR.
(2) In order to analyze the criteria of customer voltage distributions, a performance index is carried out by 3 kinds method (Without SVR, With SVR, and With SVR and ESS). As result of the analysis, it is confirmed that voltage control method of SVR and ESS is improved more than existing SVR operation method. ACKNOWLEDGEMENTS This work was conducted under framework of the research and development program of the Korea Institute of Energy Research (B9-2421). REFERENCES [1] M.Y. Kim, Y.U. Song and K.H. Kim, “The Advanced Voltage Regulation Method for ULTC in Distribution Systems with DG”, JEET, vol. 8 issue 4, pp. 737-743,2013
Fig. 13. Analysis of customer voltage characteristic by SVR operation (2) Customer voltage of primary feeder with SVR and ESS Fig.14 is the customer voltage characteristic of secondary feeder at the end section in primary feeder connected with RES. And also, SVR and ESS is located at section 3. As a result of the simulation, it is clear that customer voltage can be maintained as proper conditions when SVR and ESS is introduced in primary feeder with RES, and also, customer voltage can be exactly maintained within nominal voltage boundary during delay time of SVR by coordination operation of SVR and ESS. Therefore, it is confirmed that the coordination operation of SVR and BESS can make the customer voltage of primary feeder with RES keep better voltage conditions.
471
[2] C. Kao and C.-L. Chyu, “Least-squares estimate in fuzzy regression analysis,” European Journal of Operational Research”, vol. 148, no. 2, pp. 426-435, 2003. [3] D.S. Rho, K.S. Kook and Y.P. Wang, “Optimal Algorithms for Voltage Management in Distribution Systems Interconnected with New Dispersed Sources”, JEET, vol. 6, No 2, pp. 192-201, 2011 [4] Vasileios A. Evangelopoilos et al. “Optimal operation of smart distribution networks: A review of models, methods and future research”, Electric Power Systems Research 140, pp.95106, 2016.