- Email: [email protected]
Dynamic evaluation of maximum power point tracking operation with PV array simulator
Solar Energy Materials & Solar Cells 75 (2003) 537–546
Dynamic evaluation of maximum power point tracking operation with PV array simulator Hiroshi Matsukawaa,*, Koukichi Koshiishib, Hirotaka Koizumib, Kosuke Kurokawab, Masayasu Hamadac, Liu Boc a
Resources Total System Co. Ltd., 5 Floor Kyoritsu Building, 2-3-11 Shinkawa Chuo-ku, Tokyo 140-0033, Japan b Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan c Myway Labs Co., Ltd., 1-19-3 Shinyokohama, Kohoku-ku, Yokohama, Kanagawa 222-0033, Japan
Abstract This paper presents an innovative method to measure the dynamic control ability of maximum power point tracking for PV inverters under the condition of irradiance fluctuation. The PV array I–V curve simulator is a kind of indoor testing facility and easy to be adopted by industries. Basic functions are given by a specially designed PV array I–V curve simulator composed of the active power load. Most of the parameters are controllable by sophisticated software with capability of treating a lot of 1-s data for a very long period of time. In this paper, detailed structure of the equipment is described and test examples are also given by using a commercial PV inverter. r 2002 Elsevier Science B.V. All rights reserved. Keywords: Photovoltaic system; Inverter; MPPT; Array simulator; I–V curve; Irradiance
1. Introduction It is effective for the test of PV inverter using PV array I–V curve simulator which is able to reproduce variable conditions. Tokyo University of Agriculture and Technology (TUAT) and Myway Labs Co., Ltd. have developed a PV array I–V curve simulator. The simulator is based on the active power load (APL) of Myway and software for I–V curve simulation of TUAT. The basic functions of APL allow several modes such as constant voltage and/or current power supply, active load without power consumption. Another control loop was provided for allowing PV array I–V curve mode. The definition of I–V curve can be made through specially *Corresponding author. Tel.: +81-3-3551-6345; fax: +81-3-3553-8954. E-mail address: [email protected] (H. Matsukawa). 0927-0248/03/$ - see front matter r 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 7 - 0 2 4 8 ( 0 2 ) 0 0 1 8 5 - X
538
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
developed program on a PC. Matsukawa et al. [1,2] have reported that the I–V curve can be simulated by using this program. So, irregular pattern caused by shading etc., can also be simulated. PV array structure is arranged freely. Furthermore, when an I–V curve data set is formed, irradiance fluctuation is easily treated. In this paper, detailed structure of the equipment is described. Then, results of tests are also introduced. Effectiveness of the dynamic evaluation of maximum power point tracking (MPPT) operation with this simulator has been cleared.
2. PV array I–V curve simulator A basic structure of PV array I–V curve simulator including APL [3] is shown in Fig. 1. The APL connected PC by optical fiber to RS-232C. At first, an I–V curve is generated on the PC. Then the data of the I–V curve is transmitted to APL. Following the data, the APL performs as a PV array simulator. While its operation, parameters of APL are transmitted to PC and monitored every 1 s. The I–V, P–V characteristics, value of Pmax and output power are also indicated. Characteristics of the PV array I–V curve simulator are summarized as follows: * *
Simulating irradiance every 1 s for 9-h operation. Preinstalled standard patterns of irradiance fluctuation (additional files are installed).
Fig. 1. Basic structure of PV array I–V curve simulator.
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
539
Table 1 Specification of APL Heading
Specification
Utility side
Grid voltage (V) Grid frequency (Hz) Power factor of power grid Current harmonic distortion factor Rated capacity (kVA)
3f/200710% 50/60 Over 0.98 THD p5%, each p3% 710
DC side
DC input/output voltage (V) DC input/output current (A) Input/output capacity
DC 1–400 DC 0B725 77.5 kW continuous (max. 710 kW/10 min)
Other specification
Maximum efficiency Permissible temperature range (1C) Permissible humidity range Size (mm) Weight (kg)
89% (powering/regenerative) 0–40 10–80% RH W430, D550, H305 52
* * * * *
Faithfully simulated output characteristics of PV array (parameters are set). Size, weight, and cost reduction. Operation by a PC with easy handling. Simulating an enough scale of PV array for a standard housing. Further utilization as constant voltage and/or current power supply. Specification of this PV array I–V curve simulator was shown in Table 1.
3. Tests of APL response time The PV array I–V curve simulator (APL) was tested using an experimental circuit model shown in Fig. 2. 3.1. Tests for sudden irradiance fluctuation Fig. 3 shows the output voltage and current waveforms observed by PV array I–V curve simulator. In this test, irradiance was stepped down from 1.0 to 0.5 kW/m2. The load resistance was set to have Pmax at 0.5 kW/m2 of irradiance. The measured response time in this test was approximately 25 ms. 3.2. Tests for rapid load variation Fig. 4 shows output voltage and current waveforms observed by the simulator in the test for rapid load variation from 1 k O to 100 O (a), and from 100 O to 1 k O (b). The measured response time was 16 and 25 ms, respectively.
540
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546 3 AC200V ±10% 3φ R
AC
S T
APL
200V : 200V
+
VDC IDC
Fig. 2. Circuit model for measurement.
Fig. 3. Result of sudden irradiance fluctuation test.
4. Tests of PV inverter for MPPT control with the simulator 4.1. Default data of irradiance fluctuation The commercial PV inverter was tested with the simulator for MPPT control. Fig. 5 shows the default data sets prepared for a typical clear sky pattern ‘‘Clear’’ and three kinds of fluctuating patterns, ‘‘Vary-1’’, ‘‘Vary-2’’ and ‘‘Vary-3’’. Table 2 shows proportion of the fluctuation for default irradiance patterns. These patterns can examine MPPT function of PV inverter very realistically. These are chosen from actual observation with 1 s sampling at Tsukuba around 4 years since 1996. Relatively, irradiance fluctuation frequency is defined in the following equations. Maximum irradiance fluctuation rate means maximum value of irradiance fluctuation in a second and average irradiance fluctuation means the average value. PN Gi AVR ¼ i¼1 ; ð1Þ N Fi ¼
m X Gi 1 Gi ; AVR 2m þ 1 i¼m AVR
rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 1 XN sðFi Þ ¼ ðF Fi Þ2 ; i¼1 i N
ð2Þ
ð3Þ
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
Fig. 4. Result of rapid load variation test.
541
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
irradiance
542 1.2
1.2
1
1
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0 7:00:00
0 7:00:00
9:00:00 11:00:00 13:00:00 15:00:00 17:00:00 (1) Clear
9:00:00 11:00:00 13:00:00 15:00:00 17:00:00 (2) Vary-1 time
time 1.2
irradiance
1.2 1
1
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0 7:00:00
9:00:00 11:00:00 13:00:00 15:00:00 17:00:00 (3) Vary-2 time
0 7:00:00
9:00:00 11:00:00 13:00:00 15:00:00 17:00:00 (4) Vary-3 time
Fig. 5. Default irradiance patterns.
Table 2 Proportion of fluctuation for default irradiance patterns
Relatively irradiance fluctuation frequency (W/m2)
at 8 a.m.–4 p.m. at 11 a.m.–1 p.m. Maximum irradiance fluctuation rate (W/m2/s) Average irradiance fluctuation rate (W/m2/s) at 8 a.m.–4 p.m. Daily amount of irradiance (Wh/day) at 8 a.m.–4 p.m
Clear
Vary-1
Vary-2
Vary-3
100
363
173
138
100
397
182
169
10 0.55
681 19.94
249 8.31
220 2.59
6500
3930
4840
5150
where AVR is the average of irradiance, Gi the irradiance and Fi the irradiance fluctuating factor. We define a factor KPM for evaluating the inverter’s MPPT control capability P KPM ¼
PVArray Output Power P 100ð%Þ: Pmax
ð4Þ
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
543
4.2. Calculation of array temperature variation The resumption of array temperature usually requires many parameters and it is very difficult to simulate the temperature. However, we can easily calculate the temperature by the following equations: TCR ¼ TA þ DT;
ð5Þ
DT ¼ ð6:036 þ 0:274V þ 0:071V 2 Þ þ HAE ð45:63 5:91V þ 0:333V 2 Þ;
ð6Þ
where TCR ; TA ; V ; and HAE are, respectively, array temperature, ambient temperature, wind velocity, and irradiance. TA ¼ 251C and V ¼ 1:0 m/s are assumed. The developed simulator allows an operational mode of high-speed fluctuation of irradiance and corresponding temperature variation.
inverter
3 AC200V ±10% 3φ
1 AC100V 1φ
-
R
AC
S T
200V : 200V
APL
+
_ñ
V I
4.0kW
I0
Fig. 6. Circuit model for measurement at interactive connected.
Table 3 Specification and rating of the inverter used for the test Rated capacity (kW) Rated input voltage (V) Rated AC output voltage (V) Rated frequency (Hz) Power conversion efficiency Output power factor at fundamental frequency Current harmonic distortion Permissible temperature range (1C) Permissible humidity range (%) Inverter mode
Control method Switching mode Isolation mode Output mode
4.0 DC240 AC202712 50/60 95% (max) Over 95% THDo5%, Eacho3% 10–40 25–85 Utility interactive operating: voltage stiff current control Independency operating: voltage stiff voltage control Maximum power point tracking control leading reactive power control PWM mode Transformerless mode (booster chopper mode) Single-phase two-wire system
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
544
4.3. Circuit model of the test for PV inverter’s MPPT control The commercial PV inverter was connected to APL, and the PV inverter was tested for MPPT control. Fig. 6 shows the experimental circuit model and Table 3 shows specification and rating of this PV inverter. 4.4. Experimental results
250
2500
200
2000
150
1500
100
1000
50
500 0 11:00:00
11:30:00 12:00:00
0 12:30:00 13:00:00
250
2500
200
2000
150
1500
100
1000
50
500 0 11:00:00
11:30:00 12:00:00
0 12:30:00 13:00:00
250
2500
200
2000
150
1500
100
1000
50
500 0 11:00:00
11:30:00 12:00:00
0 12:30:00 13:00:00
3500
300
3000
250
2500
200
2000
150
1500
100
1000
50
500 0 11:00:00
11:30:00 12:00:00
0 12:30:00 13:00:00
Voltage [V] Temp. [deg]
300
3000
Power[W] Deviation[W] iation[W]
3500
(c) 300
3000
250
2500
200
2000
150
1500 100
1000
50
500 0 11:00:00
11:30:00 12:00:00
0 12:30:00 13:00:00
(e (e)
3500
300
3000
250
2500
200
2000
150
1500
100
1000
50
500 0 11:00:00
11:30:00 12:00:00
0 12:30:00 13:00:00
Voltage [V] Temp. [deg]
3500
Power[W] Deviation[W] iation[W]
(d)
Voltage [V] Temp. [deg]
Power[W] Deviation[W] iation[W]
300
3000
(b)
Voltage [V] Temp. [deg]
Power[W] Deviation[W] iation[W]
(a (a)
3500
Voltage [V] Temp. [deg]
300
3000
Power[W] Deviation[W] iation[W]
3500
Voltage [V] Temp. [deg]
Power[W] Deviation[W] iation[W]
Using the irradiance data of array temperature, a commercial inverter has been tested. The results are shown in Fig. 7. The power Pmax and voltage VPmax at Pmax
(f (f) Pmax Vpmax
Parray Varray
Deviation Temp.
Fig. 7. Measured and calculated parameters of the tests as functions of time. For the irradiance data: (a) and (b) Vary-1 with 1 and 10 min, (c) and (d) Vary-2 with 1 and 10 min and (e) and (f) Vary-3 with 1 and 10 min.
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
545
MPPT Matching Factor [%]
98 Vary-1 Vary-1
97
Vary-2 Vary-2 Vary-3 Vary-3
96 95 94 93 92 0
2
4 6 Temperature Fluctuation Factor[%]
8
10
Fig. 8. An example of array temperature fluctuation effects on MPPT.
point, the output power Parray and voltage Varray of PV array, deviation of Parray from Pmax ; and temperature are shown as functions of time for the irradiance data, Vary-1, Vary-2, and Vary-3. For each case, two sets of data are shown by moving average of irradiance data with 1 and 10 min averaging spans. All the data are stored in the monitoring PC. From the results of these tests, using Eq. (4), KPM for evaluating the inverter’s MPPT control capability of the inverter is calculated and is shown in Fig. 8. Transient control mismatch can be clearly observed by the PV array I–V curve simulator. These results show that MPPT control capability decreases as irradiance of temperature increases.
5. Conclusions The detailed structure of the PV array I–V curve simulator including APL has been described. The results of tests have been shown. The dynamic evaluation of MPPT operation has become possible by means of using this simulator. That is very effective for testing commercial inverters with MPPT control function.
References [1] H. Matsukawa, M. Shioya, T. Yamada, T. Sugiura, K. Kurokawa, Investigation of photovoltaic array simulation method for architecture, Proceedings of the JSES/JWEA Joint Conference’99, November 1999, pp. 57–60 (in Japanese).
546
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
[2] H. Matsukawa, M. Shioya, K. Kurokawa, Study on simple assessment method of BIPV power generation for architects, Proceedings of the 28th IEEE PVSC-2000, September 2000, pp. 1648–1651. [3] K. Koshiishi, H. Matsukawa, K. Kurokawa, M. Hamada, Liu bo, Evaluation of maximum power point tracking operation with PV array I–V curve simulator, National convention record IEEJ, March 2001, p. 3042 (in Japanese).
Dynamic evaluation of maximum power point tracking operation with PV array simulator Hiroshi Matsukawaa,*, Koukichi Koshiishib, Hirotaka Koizumib, Kosuke Kurokawab, Masayasu Hamadac, Liu Boc a
Resources Total System Co. Ltd., 5 Floor Kyoritsu Building, 2-3-11 Shinkawa Chuo-ku, Tokyo 140-0033, Japan b Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan c Myway Labs Co., Ltd., 1-19-3 Shinyokohama, Kohoku-ku, Yokohama, Kanagawa 222-0033, Japan
Abstract This paper presents an innovative method to measure the dynamic control ability of maximum power point tracking for PV inverters under the condition of irradiance fluctuation. The PV array I–V curve simulator is a kind of indoor testing facility and easy to be adopted by industries. Basic functions are given by a specially designed PV array I–V curve simulator composed of the active power load. Most of the parameters are controllable by sophisticated software with capability of treating a lot of 1-s data for a very long period of time. In this paper, detailed structure of the equipment is described and test examples are also given by using a commercial PV inverter. r 2002 Elsevier Science B.V. All rights reserved. Keywords: Photovoltaic system; Inverter; MPPT; Array simulator; I–V curve; Irradiance
1. Introduction It is effective for the test of PV inverter using PV array I–V curve simulator which is able to reproduce variable conditions. Tokyo University of Agriculture and Technology (TUAT) and Myway Labs Co., Ltd. have developed a PV array I–V curve simulator. The simulator is based on the active power load (APL) of Myway and software for I–V curve simulation of TUAT. The basic functions of APL allow several modes such as constant voltage and/or current power supply, active load without power consumption. Another control loop was provided for allowing PV array I–V curve mode. The definition of I–V curve can be made through specially *Corresponding author. Tel.: +81-3-3551-6345; fax: +81-3-3553-8954. E-mail address: [email protected] (H. Matsukawa). 0927-0248/03/$ - see front matter r 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 7 - 0 2 4 8 ( 0 2 ) 0 0 1 8 5 - X
538
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
developed program on a PC. Matsukawa et al. [1,2] have reported that the I–V curve can be simulated by using this program. So, irregular pattern caused by shading etc., can also be simulated. PV array structure is arranged freely. Furthermore, when an I–V curve data set is formed, irradiance fluctuation is easily treated. In this paper, detailed structure of the equipment is described. Then, results of tests are also introduced. Effectiveness of the dynamic evaluation of maximum power point tracking (MPPT) operation with this simulator has been cleared.
2. PV array I–V curve simulator A basic structure of PV array I–V curve simulator including APL [3] is shown in Fig. 1. The APL connected PC by optical fiber to RS-232C. At first, an I–V curve is generated on the PC. Then the data of the I–V curve is transmitted to APL. Following the data, the APL performs as a PV array simulator. While its operation, parameters of APL are transmitted to PC and monitored every 1 s. The I–V, P–V characteristics, value of Pmax and output power are also indicated. Characteristics of the PV array I–V curve simulator are summarized as follows: * *
Simulating irradiance every 1 s for 9-h operation. Preinstalled standard patterns of irradiance fluctuation (additional files are installed).
Fig. 1. Basic structure of PV array I–V curve simulator.
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
539
Table 1 Specification of APL Heading
Specification
Utility side
Grid voltage (V) Grid frequency (Hz) Power factor of power grid Current harmonic distortion factor Rated capacity (kVA)
3f/200710% 50/60 Over 0.98 THD p5%, each p3% 710
DC side
DC input/output voltage (V) DC input/output current (A) Input/output capacity
DC 1–400 DC 0B725 77.5 kW continuous (max. 710 kW/10 min)
Other specification
Maximum efficiency Permissible temperature range (1C) Permissible humidity range Size (mm) Weight (kg)
89% (powering/regenerative) 0–40 10–80% RH W430, D550, H305 52
* * * * *
Faithfully simulated output characteristics of PV array (parameters are set). Size, weight, and cost reduction. Operation by a PC with easy handling. Simulating an enough scale of PV array for a standard housing. Further utilization as constant voltage and/or current power supply. Specification of this PV array I–V curve simulator was shown in Table 1.
3. Tests of APL response time The PV array I–V curve simulator (APL) was tested using an experimental circuit model shown in Fig. 2. 3.1. Tests for sudden irradiance fluctuation Fig. 3 shows the output voltage and current waveforms observed by PV array I–V curve simulator. In this test, irradiance was stepped down from 1.0 to 0.5 kW/m2. The load resistance was set to have Pmax at 0.5 kW/m2 of irradiance. The measured response time in this test was approximately 25 ms. 3.2. Tests for rapid load variation Fig. 4 shows output voltage and current waveforms observed by the simulator in the test for rapid load variation from 1 k O to 100 O (a), and from 100 O to 1 k O (b). The measured response time was 16 and 25 ms, respectively.
540
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546 3 AC200V ±10% 3φ R
AC
S T
APL
200V : 200V
+
VDC IDC
Fig. 2. Circuit model for measurement.
Fig. 3. Result of sudden irradiance fluctuation test.
4. Tests of PV inverter for MPPT control with the simulator 4.1. Default data of irradiance fluctuation The commercial PV inverter was tested with the simulator for MPPT control. Fig. 5 shows the default data sets prepared for a typical clear sky pattern ‘‘Clear’’ and three kinds of fluctuating patterns, ‘‘Vary-1’’, ‘‘Vary-2’’ and ‘‘Vary-3’’. Table 2 shows proportion of the fluctuation for default irradiance patterns. These patterns can examine MPPT function of PV inverter very realistically. These are chosen from actual observation with 1 s sampling at Tsukuba around 4 years since 1996. Relatively, irradiance fluctuation frequency is defined in the following equations. Maximum irradiance fluctuation rate means maximum value of irradiance fluctuation in a second and average irradiance fluctuation means the average value. PN Gi AVR ¼ i¼1 ; ð1Þ N Fi ¼
m X Gi 1 Gi ; AVR 2m þ 1 i¼m AVR
rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 1 XN sðFi Þ ¼ ðF Fi Þ2 ; i¼1 i N
ð2Þ
ð3Þ
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
Fig. 4. Result of rapid load variation test.
541
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
irradiance
542 1.2
1.2
1
1
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0 7:00:00
0 7:00:00
9:00:00 11:00:00 13:00:00 15:00:00 17:00:00 (1) Clear
9:00:00 11:00:00 13:00:00 15:00:00 17:00:00 (2) Vary-1 time
time 1.2
irradiance
1.2 1
1
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0 7:00:00
9:00:00 11:00:00 13:00:00 15:00:00 17:00:00 (3) Vary-2 time
0 7:00:00
9:00:00 11:00:00 13:00:00 15:00:00 17:00:00 (4) Vary-3 time
Fig. 5. Default irradiance patterns.
Table 2 Proportion of fluctuation for default irradiance patterns
Relatively irradiance fluctuation frequency (W/m2)
at 8 a.m.–4 p.m. at 11 a.m.–1 p.m. Maximum irradiance fluctuation rate (W/m2/s) Average irradiance fluctuation rate (W/m2/s) at 8 a.m.–4 p.m. Daily amount of irradiance (Wh/day) at 8 a.m.–4 p.m
Clear
Vary-1
Vary-2
Vary-3
100
363
173
138
100
397
182
169
10 0.55
681 19.94
249 8.31
220 2.59
6500
3930
4840
5150
where AVR is the average of irradiance, Gi the irradiance and Fi the irradiance fluctuating factor. We define a factor KPM for evaluating the inverter’s MPPT control capability P KPM ¼
PVArray Output Power P 100ð%Þ: Pmax
ð4Þ
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
543
4.2. Calculation of array temperature variation The resumption of array temperature usually requires many parameters and it is very difficult to simulate the temperature. However, we can easily calculate the temperature by the following equations: TCR ¼ TA þ DT;
ð5Þ
DT ¼ ð6:036 þ 0:274V þ 0:071V 2 Þ þ HAE ð45:63 5:91V þ 0:333V 2 Þ;
ð6Þ
where TCR ; TA ; V ; and HAE are, respectively, array temperature, ambient temperature, wind velocity, and irradiance. TA ¼ 251C and V ¼ 1:0 m/s are assumed. The developed simulator allows an operational mode of high-speed fluctuation of irradiance and corresponding temperature variation.
inverter
3 AC200V ±10% 3φ
1 AC100V 1φ
-
R
AC
S T
200V : 200V
APL
+
_ñ
V I
4.0kW
I0
Fig. 6. Circuit model for measurement at interactive connected.
Table 3 Specification and rating of the inverter used for the test Rated capacity (kW) Rated input voltage (V) Rated AC output voltage (V) Rated frequency (Hz) Power conversion efficiency Output power factor at fundamental frequency Current harmonic distortion Permissible temperature range (1C) Permissible humidity range (%) Inverter mode
Control method Switching mode Isolation mode Output mode
4.0 DC240 AC202712 50/60 95% (max) Over 95% THDo5%, Eacho3% 10–40 25–85 Utility interactive operating: voltage stiff current control Independency operating: voltage stiff voltage control Maximum power point tracking control leading reactive power control PWM mode Transformerless mode (booster chopper mode) Single-phase two-wire system
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
544
4.3. Circuit model of the test for PV inverter’s MPPT control The commercial PV inverter was connected to APL, and the PV inverter was tested for MPPT control. Fig. 6 shows the experimental circuit model and Table 3 shows specification and rating of this PV inverter. 4.4. Experimental results
250
2500
200
2000
150
1500
100
1000
50
500 0 11:00:00
11:30:00 12:00:00
0 12:30:00 13:00:00
250
2500
200
2000
150
1500
100
1000
50
500 0 11:00:00
11:30:00 12:00:00
0 12:30:00 13:00:00
250
2500
200
2000
150
1500
100
1000
50
500 0 11:00:00
11:30:00 12:00:00
0 12:30:00 13:00:00
3500
300
3000
250
2500
200
2000
150
1500
100
1000
50
500 0 11:00:00
11:30:00 12:00:00
0 12:30:00 13:00:00
Voltage [V] Temp. [deg]
300
3000
Power[W] Deviation[W] iation[W]
3500
(c) 300
3000
250
2500
200
2000
150
1500 100
1000
50
500 0 11:00:00
11:30:00 12:00:00
0 12:30:00 13:00:00
(e (e)
3500
300
3000
250
2500
200
2000
150
1500
100
1000
50
500 0 11:00:00
11:30:00 12:00:00
0 12:30:00 13:00:00
Voltage [V] Temp. [deg]
3500
Power[W] Deviation[W] iation[W]
(d)
Voltage [V] Temp. [deg]
Power[W] Deviation[W] iation[W]
300
3000
(b)
Voltage [V] Temp. [deg]
Power[W] Deviation[W] iation[W]
(a (a)
3500
Voltage [V] Temp. [deg]
300
3000
Power[W] Deviation[W] iation[W]
3500
Voltage [V] Temp. [deg]
Power[W] Deviation[W] iation[W]
Using the irradiance data of array temperature, a commercial inverter has been tested. The results are shown in Fig. 7. The power Pmax and voltage VPmax at Pmax
(f (f) Pmax Vpmax
Parray Varray
Deviation Temp.
Fig. 7. Measured and calculated parameters of the tests as functions of time. For the irradiance data: (a) and (b) Vary-1 with 1 and 10 min, (c) and (d) Vary-2 with 1 and 10 min and (e) and (f) Vary-3 with 1 and 10 min.
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
545
MPPT Matching Factor [%]
98 Vary-1 Vary-1
97
Vary-2 Vary-2 Vary-3 Vary-3
96 95 94 93 92 0
2
4 6 Temperature Fluctuation Factor[%]
8
10
Fig. 8. An example of array temperature fluctuation effects on MPPT.
point, the output power Parray and voltage Varray of PV array, deviation of Parray from Pmax ; and temperature are shown as functions of time for the irradiance data, Vary-1, Vary-2, and Vary-3. For each case, two sets of data are shown by moving average of irradiance data with 1 and 10 min averaging spans. All the data are stored in the monitoring PC. From the results of these tests, using Eq. (4), KPM for evaluating the inverter’s MPPT control capability of the inverter is calculated and is shown in Fig. 8. Transient control mismatch can be clearly observed by the PV array I–V curve simulator. These results show that MPPT control capability decreases as irradiance of temperature increases.
5. Conclusions The detailed structure of the PV array I–V curve simulator including APL has been described. The results of tests have been shown. The dynamic evaluation of MPPT operation has become possible by means of using this simulator. That is very effective for testing commercial inverters with MPPT control function.
References [1] H. Matsukawa, M. Shioya, T. Yamada, T. Sugiura, K. Kurokawa, Investigation of photovoltaic array simulation method for architecture, Proceedings of the JSES/JWEA Joint Conference’99, November 1999, pp. 57–60 (in Japanese).
546
H. Matsukawa et al. / Solar Energy Materials & Solar Cells 75 (2003) 537–546
[2] H. Matsukawa, M. Shioya, K. Kurokawa, Study on simple assessment method of BIPV power generation for architects, Proceedings of the 28th IEEE PVSC-2000, September 2000, pp. 1648–1651. [3] K. Koshiishi, H. Matsukawa, K. Kurokawa, M. Hamada, Liu bo, Evaluation of maximum power point tracking operation with PV array I–V curve simulator, National convention record IEEJ, March 2001, p. 3042 (in Japanese).