Sensor-Ball system based on IEEE 1451 for monitoring the condition of power transmission lines

Sensors and Actuators A 154 (2009) 157–168

Contents lists available at ScienceDirect

Sensors and Actuators A: Physical journal homepage: www.elsevier.com/locate/sna

Sensor-Ball system based on IEEE 1451 for monitoring the condition of power transmission lines Jeong-Do Kim a , Jung-Hwan Lee a , Yu-Kyung Ham a , Chul-Ho Hong b , Byoung-Woon Min c , Sang-Goog Lee d,∗ a

Department of Electronic Engineering, Hoseo University, Asan, Chungnam, South Korea Department of System and Control Engineering, Hoseo University, Asan, Chungnam, South Korea Department of System Control Research, Electro-Mechanical Research Institute, Hyundai Heavy Industries co., ltd., 1 Jeonhadong Ulsan-city 682-060, South Korea d Department of Multimedia System Engineering, The Catholic University of Korea, Bucheon, Gyeonggi, South Korea b c

a r t i c l e

i n f o

Article history: Received 4 March 2009 Received in revised form 19 June 2009 Accepted 21 June 2009 Available online 27 June 2009 Keywords: Sensor-Ball IEEE 1451 TEDS Power transmission IEC 61850

a b s t r a c t The energy industry is developing it safety methods so that it can prevent accidents, diagnose the conditions of power utilities and identify any problems that might arise. In other words, the industry is trying to increase the reliability of power utilities and improve the quality of power utilities by conducting monitoring and diagnosis tasks in real-time by building a sensor network in order to monitor the status of power utilities. This study has applied IEEE 1451, an interface standard of sensor network, for the diagnosis, information exchange and compatibility of the Sensor-Ball, which is a sensor unit that constructs a sensor network for the status monitoring of power transmission lines. In order to accomplish these objectives, we applied IEEE 1451.0 and IEEE 1451.5 to the Sensor-Ball, suggested a reference model, and represented the characteristic information of the Sensor-Ball by use of IEEE 1451 TEDS (Transducer Electronic Data Sheet). By constructing a Sensor-Ball system that has a connected sensor for measuring the atmospheric temperature and line slope, we have identified the operational status and sensor data of TEDS applied through a monitoring program. © 2009 Elsevier B.V. All rights reserved.

1. Introduction The energy industry today is characterized by an electric power IT system that digitalizes and promotes the efficiency of the existing power system in order to supply and maintain a reliable output of high quality, clean power. The system collectively gathers and manages status information generated throughout the system, such as power generation, power transmission, power transformation, and power distribution, which are the major components of the power system, in order to prevent accidents like large power failures and to reduce power dissipation through a smart, efficient grid network [1,2]. Since the power transmission function responsible for the power transportation in the power system transmits a high voltage of power, various problems can arise. In addition, since most of the facilities are exposed to the external environment, it is necessary to monitor the conditions of power transmission lines in real-time to achieve reliable power transmission [3,4].

∗ Corresponding author. Tel.: +82 2 2164 4909; fax: +82 2 2164 4991. E-mail address: [email protected] (S.-G. Lee). 0924-4247/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.sna.2009.06.009

To achieve an efficient monitoring status, the standardization measuring method of using IEC 61850 is applied to the automation of transformer substations and power transmission lines [5–15]. The main purpose of IEC 61850 is to abstract the data items and services that create data items, objects and services regardless of the communication protocol in use. IEC 61850 was established to resolve the issues needed for the interoperability and free configuration of transformer substation automation. As for the use of IEC 61850, the manufacturer provides ease of information exchange and replacement between other IEDs while enabling performance improvements and cost savings. As for the major monitoring items of power transmission lines, these are temperature, current, wind direction, wind speed, and the tension of power transmission lines, and the slope, insulation, corrosion, and line environment monitoring of the iron tower. Several kinds of sensors are used for the monitoring of these various items. To transmit the sensor data by integrating these sensors into one device is beneficial for the improvement of the efficiency of IT utilities. In order to achieve this goal, Hyundai Heavy Industries of Korea is developing the Sensor-Ball. Several types of sensor are placed on the inside and outside of Sensor-Ball and are connected to another Sensor-Ball and FJB (Joint Box for OPGW) through a wireless communication.

158

J.-D. Kim et al. / Sensors and Actuators A 154 (2009) 157–168

However, as the Sensor-Ball is installed onto the power transmission line that is easily accessible, the diagnosis of various sensors should be easily accomplished and, at the same time, the status information of the sensor can be checked when replacing or adding

a sensor. This diagnosis and information checking should be made possible by the FJB or upper-level system connected to the SensorBall. Also, in the case of one type of sensor, it can be manufactured by a number of companies and so there may be differences in the

Fig. 1. Sensor-Ball for monitoring power transmission lines. (a) Exterior of Sensor-Ball (version 1), (b) Exterior of Sensor-Ball (version 2), (c) Structure of Sensor-Ball, (d) Architecture of Sensor-Ball.

J.-D. Kim et al. / Sensors and Actuators A 154 (2009) 157–168

159

Fig. 2. Structure of control circuit board. (a) Main control board, (b) Sensor control board, (c) Structure of main control board, (d) Structure of sensor control board.

characteristics of the sensor. Since the Sensor-Ball can be installed on a large number of power transmission lines, it is not an easy task to build a database by using the characteristic information of all the sensors.

In order to meet these criteria and to solve relevant problems, not only the characteristics of the Sensor-Ball but also the characteristic information and calibration information of each sensor should be provided to the upper-level system. Furthermore, in order to

Fig. 3. Architecture of sensor network.

160

J.-D. Kim et al. / Sensors and Actuators A 154 (2009) 157–168

Fig. 4. Reference model of IEEE 1451 [17].

maintain compatibility between the Sensor-Ball and FJB, it is necessary to have a common data structure and interface. However, in the case of IEC 61850, the representative standard of IT power, a limitation exists in providing the characteristic sensor information, calibration information and common interface method. The IEEE 1451 is used as the interface standard for maintaining sensor intelligence and compatibility between the sensor and device [16–22]. IEEE 1451 is an interface standard smart sensor that defines the standard interface between the network and sensor as well as the intelligent information of the sensor. In other words, it provides the standard interface regardless of the type of sensor and

network and provides the transducer electronic data Sheet (TEDS), an electronic data sheet that allows data to be saved to the memory bank by digitalizing the sensor and calibration information. In addition to the common interfaces such as serial and multi-drop, this supports various wireless communication methods such as WLAN (IEEE 802.11), Bluetooth, 6LoWPAN (IPv6 over low-power WPAN) and Zigbee. Currently, many applications on smart sensors using IEEE 1451 are being developed rapidly [23–28]. And, web-sensors and sensor systems for quality power application that use IEEE 1451 are also being developed [29–35]. Application of IEEE 1451 to the Sensor-Ball is represented as a common data format by digitalizing the characteristic information of the Sensor-Ball, allowing connection regardless of the interface type. The intelligence of the Sensor-Ball obviates unnecessary tasks when making the connection between Sensor-Ball and other devices. Since it automatically provides the interface information at the time of connection, the plug and play function of the SensorBall can work. Since the user can easily check the status of the

Fig. 5. IEEE 1451 reference model of Sensor-Ball.

Fig. 6. IEEE 1451 TEDS of Sensor-Ball.

J.-D. Kim et al. / Sensors and Actuators A 154 (2009) 157–168

161

Table 1 Overall structure of META-TEDS. Field type

Field name

Description

Data type

#Byte

3 4

TEDSID UUID

Length TEDS identification header Globally unique identifier

UInt32 UInt8 UUID

4 4 10

Timing-related information 10 OHoldOff 12 TestTime

Operational time-out Self-test time

Float32 Float32

4 4

13

MaxChan

Number of implemented TransducerChannels

UInt16

2

17

Proxies

TransducerChannel proxy definition sub-block

–

–

UInt16 UInt8 Array of UInt16

1 1 NTv

UInt8 UInt8 UInt8 UInt8 UInt8Array UInt8Array UInt16

1 1 1 1 8 8 2

Types 22, 23 and 21 define one TransducerChannel proxy 22 ChanNum TransducerChannel number of the TransducerChannel proxy 23 Organize TransducerChannel proxy data-set organization 21 MemList TransducerChannel proxy member list 25–127 – Open to manufacturers 128 NumofZigbee 129 NumofISen 130 NumofESen 133 BattLimit 134 InBallSenList 135 ExBallSenList – –

Number of Zigbee Number of internal sensors Number of external sensors Battery limitation of ball Internal sensor list connected to the ball External sensor list connected to the ball CheckSum

Sensor-Ball, the operational status of various sensors, and errors in the sensor value, it can reduce false diagnosis caused by the erroneous operation of a sensor. In addition, since it holds common information between the Sensor-Ball and the upper-level system, the problem of incompatibility can be eliminated. This paper has implemented and checked the operational status of the system by applying the IEEE 1451 in order to provide for the compatibility of the Sensor-Ball and the characteristic information of the sensor so that the status monitoring of power transmission lines can be accomplished. As for the basic characteristics of the Sensor-Ball and characteristics of various sensors controlled by the Sensor-Ball, the system was designed according to IEEE 1451.0 specifications. Since IEEE 1451.0 accommodates all other specifications of IEEE 1451.x except for IEEE 1451.4, the design should be based on IEEE 1451.0. The characteristics of various sensors under the influence of the Sensor-Ball consist of TransducerChannel TEDS. The communication between the Sensor-Balls and the communication interface between ball and FJB were designed according to IEEE 1451.5 specifications. In order to provide compatibility and a common design interface in the design of the Sensor-Ball, this study has presented a reference model of the Sensor-Ball while making use of IEEE 1451.0 and IEEE 1451.5. Also, through this reference model, this paper has designed the hardware prototype and TEDS of a standardized Sensor-Ball that can support IEEE 1451 and its operability was proven through an experiment. 2. Construction of Sensor-Ball system In order to provide power reliably, an online monitoring and diagnosis function is needed at all times throughout the power system. Since the transmission facilities responsible for power transmission are mostly installed in an outdoor environment, most accidents occur from a change in the external environment such as a short circuit at a power transmission line or a natural disaster. Furthermore, because of the characteristics of power transmission lines, it is difficult to find the point of accident and to take appropriate action, like making fast repairs/maintenance. Therefore, in order to prevent an accident like a large-scale power failure in advance and to find the point of accident quickly and accurately, it is necessary to have a sensor device that allows for the check-

ing of the status information of the power transmission line in real-time. Fig. 1 shows the appearance and construction diagram of the Sensor-Ball under development for line monitoring. The unit has a small-sized structure, is light in weight, thunderbolt and waterproof resistant and is insulated from the power transmission line. The inner part of the Sensor-Ball consists of a built-in power module that can independently operate without an external power supply, a microprocessor that controls the Sensor-Ball, and a wireless communication module for communication with other devices. Sensors for temperature, current, wind direction, wind speed, and slope are present in the inner part of Sensor-Ball and a camera is also installed. In addition, the Sensor-Ball allows the connection of up to a maximum of 14 external sensors through Zigbee. The external sensors designed at this point are the defective insulator detection sensor, tension sensor, iron tower slope detection sensor, iron tower corrosion detection sensor, and external temperature/humidity sensor. Hyundai Heavy Industries co., ltd. of Korea designed mechanical parts, each sensor modules and power module. We took charge of design of control board, IEEE 1451, control program and communication program. Fig. 2 shows two control boards for Sensor-Ball. The control board was composed of main board and sensor board for minimizing power consumption, and the sensor board is connected to main board thru an UART. Because WiFi, GPS and camera on main board and main board are sometimes worked, they are placed into sleep mode for minimizing power consumption until a working command is given by sensor board. And sensor board consists of two parts for minimizing power consumption, since CT sensor ought to work at all time and other sensor modules can be worked in sleep mode except for their regularly scheduled time. Sensor board has a Zigbee module using ZigBit of Meshnetics that can transmit data up to 4000 m. It can arouse main board from sleep mode as well as communicate with external sensor for status monitoring of power line tower. Fig. 3 shows the method that constructs the status monitoring sensor network of power transmission lines. Each cluster is constructed with an external sensor module that is connected to the Sensor-Ball and Zigbee. The Sensor-Ball connected to other SensorBalls plays a relay role by using WLAN (IEEE 802.11). Of these, the

162

J.-D. Kim et al. / Sensors and Actuators A 154 (2009) 157–168

Table 2 Structure of TEDS identifier. Field

Contents

Function

Family Class Version Tuple length

0 0–255 0–255 Number of octets

IEEE 1451.0 TEDS access code TEDS version The total length of TEDS

hub ball is responsible for sending data to FJB (joint box for OPGE) by combining the data of other Sensor-Balls. FJB collects the information of surrounding Sensor-Balls and transmits it to the upper-level system. 3. Reference model for the Sensor-Ball system 3.1. Smart sensor interface specification IEEE 1451 The Sensor-Ball developed to monitor the status of power transmission lines is linked to several types of sensors. The Sensor-Ball is also responsible for sensor function. In order to have confidence in the sensor data provided by the Sensor-Ball and to evaluate them, characteristic information such as the output range of the

sensor devices and sensors and whether the sensor is defective or not should be provided together with other basic information so that the system using the sensor data may be evaluated. Also, to achieve compatibility between the Sensor-Ball and FJB, it is necessary to have data construction and a standard interface that is commonly supported regardless of the properties of the sensors in the Sensor-Ball. The IEEE 1451 is the international standard that provides compatibility for sensor intelligence and between sensor devices. The IEEE 1451 specification as an interface standard for smart sensors defines the common communication interfaces for the network connection of sensors and microprocessor-based devices. Currently, the specification has been standardized from IEEE 1451.0 up to IEEE 1451.5. IEEE 1451.1 defines the network capable application processor (NCAP) and object model for network communication, IEEE 1451.2 for the point-to-point communication interface, 1451.3 for the distributed multi-drop interface, and IEEE 1451.4 for the mixed-mode interface (MMI) of analog and digital communication. In addition, the characteristic information of general sensors is defined by using a sensor TEDS template. IEEE 1451.5 supports the wireless communication interfaces of IEEE 802.11, IEEE 8021.15.4, Bluetooth, and Zigbee; the IEEE P1451.6 specification for CAN communication is yet to be specified. IEEE 1451.0 was stan-

Table 3 Overall structure of TransducerChannel TEDS. Field type

Field name

Description

Data type

#Byte

TEDSID

TEDS length Globally unique identifier

UInt32 UInt8

4 4

TransducerChannel related information 10 Calkey 11 ChanType 12 PhyUint 50 UintType 51 Radians 52 SterRad 53 Meters 54 Kilogram 55 Seconds 56 Amperes 57 Kelvins 58 Moles 59 Candelas 13 LowLimit 14 HiLimit 15 OError 16 SelfTest

Calibration key TransducerChannel type key Physical units Physical units interpretation enumeration The exponent for radians The exponent for steradians The exponent for meters The exponent for kilograms The exponent for seconds The exponent for amperes The exponent for Kelvins The exponent for moles The exponent for candelas Design operational lower range limit Design operational upper range limit Worst-case uncertainty Self-test key

UInt8 UInt8 UINTS UInt8 UInt8 UInt8 UInt8 UInt8 UInt8 UInt8 UInt8 UInt8 UInt8 Float32 Float32 UInt8 UInt8

1 1 11 1 1 1 1 1 1 1 1 1 1 4 4 1 1

Data converter-related information 18 Sample 40 DatModel 41 ModeLenth 42 SignBit

Data model Data model length Model significant bits

– UInt8 UInt8 UInt16

– 1 1 2

Timing-related information 20 21 22 23 24 25 26

UpdateT WSetupT RSetupT Speriod WarmUpT RDelayT TestTime

TransducerChannel update time (tu) TransducerChannel write setup time (tws) TransducerChannel read setup time (trs) TransducerChannel sampling period (tsp) TransducerChannel warm-up time TransducerChannel read delay time (tch) TransducerChannel self-test time requirement

Float32 Float32 Float32 Float32 Float32 Float32 Float32

4 4 4 4 4 4 4

Attribute 31 48 49

Sampling SampMode SDefault

Sampling attribute Sampling mode capacity Default sampling mode

– UInt8 UInt8

– 1 1

Sensitivity (optional) 37 38

Direction Dangles

Sensitivity direction Direction angles

Float32 Two Float32

4 8

Open to manufacturers 128 –

SenID –

Sensor ID CheckSum

UInt8 UInt16

1 2

3

J.-D. Kim et al. / Sensors and Actuators A 154 (2009) 157–168

163

Table 4 Overall structure of User’s Transducer Name TEDS. Field type

Field name

Description

Data type

#Byte

0–2 3 4

– TESDID Format

Length Reserved Globally unique identifier Format description of this TEDS

UInt32 – UInt8 UInt8 String String String : UInt16

4 – 4 1 32 32 32 : 2

5

TCName

TIM or TransducerChannel name

–

–

CheckSum

TIM name Internal sensor External sensor :

Table 5 Overall structure of PHY TEDS. Field type

Description

Data type

#Byte

UInt32 UInt8

4 4

UInt8 UInt32 UInt16 UInt16 UInt16 Boolean UInt16 UInt16 UInt16 UInt32 UInt32 UInt8

1 4 2 2 2 1 2 2 2 4 4 1

UInt8 UInt16 UInt16

1 2 2

25–31 48–54

TEDS length TEDS identification header Reserved Radio type Max data throughput Max connected devices Max registered devices Encryption Authentication Min key length Max key length Max SDU size Min access latency Min transmit latency Max simultaneous transactions Device is battery powered Radio version # Maximum retries before disconnect Reserved 802–11 Radio specific

Open to manufacturers 128 PhyAddress 129 IPAddress – –

Physical address IP address CheckSum

– 3 4–9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Field name TEDSID Radio MaxBPS MaxCDev MaxRDev Encrypt Authent MinKeyL MaxKeyL MaxSDU MinALat MinTLat MaxXact Battery RadioVer MaxRetry

UInt8 UInt8 UInt16

6 4 2

dardized for the flexible interoperability and compatibility of IEEE 1451 standards. IEEE 1451.0 defines the common instruction set for controlling IEEE 1451.x and holds the 1451.0 TEDS structure that commonly supports the characteristic information of all the transducers connected with IEEE 1451.x. 1451.0 TEDS not only supports the four essential TEDS of META-TEDS, TransducerChannel TEDS, User’s Transducer Name TEDS, and PHY TEDS, but also several other kinds of TEDS such as Calibration TEDS, Frequency Response

Fig. 7. Sensor-Ball system for experiment.

TEDS, Transfer Function TEDS, Text-based TEDS, End User Application Specific TEDS, and Manufacture-defined TEDS. Fig. 4 shows the reference model of IEEE 1451 specification [9–15]. 3.2. IEEE 1451 reference model of Sensor-Ball Sensor-Ball and FJB play the roles of wireless transducer interface module (WTIM) and network capable application processor, which are defined in the IEEE 1451 specification. The Sensor-Ball is based on the IEEE 1451.0 and IEEE 1451.5 specifications. IEEE 1451.5 supports the API functions and PHY TEDS in relation to wireless communication (WLAN, Zigbee and Bluetooth) between NCAP and WTIM. IEEE 1451.0 provides an interface between the physical layer and application layer of IEEE 1451.5 and provides the API functions related to the TEDS and sensor data. The Sensor-Ball (WTIM) converts the basic information of the Sensor-Ball and characteristic information of connected sensors into a form of TEDS and saves this information. When connecting to NCAP (FJB) or receiving a request from NCAP, it reads data from the memory and transmits them. FJB reads in TEDS from WTIM and saves to the TEDS cache. The read-in TEDS is interpreted through the TEDS template and

Table 6 Data structure between Sensor-Ball and FJB. Division

Contents

Details

Note

TEDS information

META-TEDS TransducerChannel TEDS User’s Transducer Name TEDS Physical TEDS

Ball’s fundamental DataSheet

At the first connection and power confirmation or when requested

Battery status Charge status Sensor status Register data Periodic data

Raw data Non-periodic data

Zigbee status

Internal sensor data External sensor data Poor insulator monitoring data Camera data

Register showing ball’s battery value Register showing ball’s charging value 0: Error 1: No error 00: No signal 01: Poor 10: Medium 11: Good Number of sensors: 7 Number of sensors: 7 1280 bytes JPEG (640 × 480), 9 Hz

164

J.-D. Kim et al. / Sensors and Actuators A 154 (2009) 157–168

Transducer Name TEDS defines the name of the Sensor-Ball and name of the sensors connected to the Sensor-Ball. The PHY TEDS is the TEDS that defines the characteristics of the physical layer regarding WLAN (IEEE 802.11). Fig. 6 shows the IEEE 1451 TEDS construction of the Sensor-Ball.

Fig. 8. An installation of ball-sensor on power transmission line for experiment.

is transmitted to the upper-level system through Ethernet. Fig. 5 shows the model that has applied the IEEE 1451 specification of the Sensor-Ball.

4.1.1. META-TEDS Table 1 shows the overall structure of META-TEDS. The Type 3 “TEDSID,” as the TEDS identifier header, is comprised of properties such as family, class, version, and TEDS length. If the property ‘family,’ as the value indicating IEEE 1451.0, is always ‘0,’ the property ‘class’ shows the TEDS access code. And, the property ‘version’ represents the IEEE 1451.0 standard version. Lastly, the property ‘TEDS length’ indicates the entire length of TEDS data. Table 2 shows the TEDS identification header. The Type 4 “UUID,” a globally unique identifier, can display the location information (such as latitude and longitude) of the installed sensor unit, the unique ID of the sensor unit, and the date of manufacture. Additionally, it holds property types such as information related to time, maximum number of sensors that can be connected to the Sensor-Ball, number of internal and external sensors connected to the Sensor-Ball, battery status, and the list of connected sensors. The types 128–135 are the types added for the Sensor-Ball.

4. Sensor-Ball system based on IEEE 1451 4.1. TEDS design of Sensor-Ball In addition to the four essential TEDS such as META-TEDS, TransducerChannel TEDS, User’s Transducer Name TEDS and PHY TEDS, IEEE 1451.0 TEDS supports various kinds of TEDS such as Calibration TEDS, Frequency Response TEDS, Transfer Function TEDS, Text-based TEDS, End User Application Specific TEDS, and Manufacture-defined TEDS. The TEDS of the Sensor-Ball consists of META-TEDS, TransducerChannel TEDS, User’s Transducer Name TEDS, and PHY TEDS. META-TEDS defines the positional information of a sensor, worstcase scenario information, timing information, communication status, battery and sensor status. The TransducerChannel TEDS, the TEDS that shows the characteristics of the sensors that the SensorBall takes charge of, requires a TEDS memory equivalent to the number of the sensors connected to the Sensor-Ball. The User’s

4.1.2. TransducerChannel TEDS Table 3 shows the overall structure of TransducerChannel TEDS. This TEDS shows the characteristic information of the sensors connected to the sensor unit. It holds TransducerChannel blocks equivalent to the number of connected sensors. Type 10, as a calibration key, shows the calibration applicability of this sensor and the location of calibration information. The calibration key of Type 11 shows whether the calibration information is supported as a standard/non-standard TEDS and the calibration position. Since each sensor connected to the Sensor-Ball basically sends calibrated data to the Sensor-Ball, the Calibration TED of each sensor is not needed. The Calibration TEDS of the Sensor-Ball was not applied. Type 13, 14 and 15 indicates the output range and error of a sensor. And, Type 31, 48 and 49 of sensor attributes shows information like the sampling mode of a sensor (such as trigger mode, free-running mode, continuous mode and immediate operation mode). Lastly, the “SenID” of Type 128 represents the ID of a connected sensor.

Fig. 9. Monitoring program of Sensor-Ball.

J.-D. Kim et al. / Sensors and Actuators A 154 (2009) 157–168

165

Table 7 Type of Sensor-Ball and connected sensors. Sensor Temperature sensor

The displacement sensor

Type

Feature

Room temperature

- Range: −40 ◦ C to +80 ◦ C - Accuracy: ±1 ◦ C

The parallelism with line

- Range: ±90◦ (the droop of cable, line tilt) - Accuracy: 0.01◦ /digit - Range: ±90◦ (the twist of cable) - Accuracy: 0.01◦ /digit

The right angle with line

4.1.3. User’s Transducer Name TEDS Table 4 shows the overall structure of User’s Transducer Name TEDS. This TEDS informs the names of TIM and TransducerChannel to the system or user. The first data from “TCName” of Type 5 represents the name of TIM or the name of the Sensor-Ball, followed by the respective names of connected external/internal sensors.

see the status of the Sensor-Ball. The periodic data, as the data of transmitting data periodically to FJB, include the register data and actual sensor data. The non-periodic data, as the data sent to the Sensor-Ball from a request from FJB, has a very large capacity of data compared to the periodic data.

4.1.4. PHY TEDS Table 5 shows the overall structure of PHY TEDS. This TEDS defines the characteristics of physical layers regarding the wireless communication of the Sensor-Ball based on IEEE 802.11. Items such as Types 10, 21, 22, 23 and 24 represent the basic information needed in the data transmission of IEEE 802.11 wireless communication. Types 128 and 129, as those defined for the Sensor-Ball, represent the physical address of a wireless module and allocated IP address of the Sensor-Ball.

5. Experimental result

4.2. Data structure of Sensor-Ball Table 6 shows the data structure for the data processing of the Sensor-Ball. The data is largely divided into TEDS information, periodic data and non-periodic data. The periodic data includes the register information for the status of the Sensor-Ball. The register information shows the status information of the Sensor-Ball, battery charge status, sensor status, and Zigbee connection status. This is one very important component of information that allows us to

5.1. Implementation of Sensor-Ball system Figs. 7 and 8 show the construction diagram and installation looks of the Sensor-Balls and FJB used for this experiment. Two Sensor-Balls with a built-in WiFi communication module are mounted on power transmission lines for our experiment. The information of Ball-Sensor 1 is transmitted to FJB thru Ball-Sensor. The distance between Ball-Sensors is about 500 m and the BallSensor 2 and FJB is 200 m. For this experiment, we connected and used two external sensors (temperature sensor and slope sensor) to the Sensor-Ball. Table 6 shows the data structure between Sensor-Ball and FJB. The specifications of these sensors are shown in Table 7. The ARM board in charge of the Sensor-Ball and FJB operates by an embedded LINUX. For the reliable communication between the Sensor-Ball and FJB, the TCP/IP (Transmission Control Protocol/Internet Protocol) protocol was used).

Fig. 10. Operational sequence of Sensor-Ball.

166

J.-D. Kim et al. / Sensors and Actuators A 154 (2009) 157–168

In addition, the Sensor-Ball system operates based on server/client architecture. The Sensor-Ball becomes the server and FJB becomes the client. From the perspective of the IEEE 1451, the Sensor-Ball and FJB play the respective roles of wireless transducer interface module and network capable application processor. Applying IEEE 1451.0 and 1451.5 to the Sensor-Ball and checking its status can be identified through an external server linked to FJB. Fig. 9 shows the program that monitors the TEDS information of the Sensor-Ball and sensor data. 5.2. Operational sequence When the Sensor-Ball and FJB are initially connected or a power source is newly applied to the Sensor-Ball, the Sensor-Ball transmits its own TIM information and TEDS to FJB upon a request from FJB. The operational sequence of the Sensor-Ball is shown in Fig. 10 and it performs the following server/client tasks. (1) Open/connect a socket for communication between client and server. (2) Obtain TIM information from the client. By using this information, the server places a TEDS request from TIM. (3) The client that has received a TEDS request from the server reads in TEDS from the memory and sends the result sequentially to

the server. The META-TEDS is sent first and the TransducerChannel TEDS is sent as many times as the number of sensor channels connected with the Sensor-Ball. Then, the User’s Transducer TEDS and PHY TEDS are sent. (4) After obtaining the channel information from TEDS, the server requests for the sensor data periodically or non-periodically through the Sensor-Ball.

5.3. Checking the TEDS information of Sensor-Ball and the sensor data Fig. 11 shows the TEDS of the Sensor-Ball sent to FJB and the sensor data. The Sensor-Ball TEDS is interpreted by the TEDS template of FJB. Fig. 11(a) shows the META-TEDS. This shows the basic information of the Sensor-Ball and connected sensor list such as the type of IEEE 1451 applied to the Sensor-Ball and the Sensor-Ball ID. Fig. 11(b) shows the connected temperature sensor of the SensorBall, each TransducerChannel TEDS of slope sensor and requested sensor data. This TEDS shows the application status for the Calibration TEDS of sensor, measurement range and error of sensor data, and sensor number. As for the sensor data to be added in the future, a metadata area holding a data space of 20 bytes was allocated for the entry of additional data.

Fig. 11. Checking Sensor-Ball TEDS and sensor data. (a) Result of META-TEDS, (b) Checking the TransducerChannel TEDS result and sensor data of temperature sensor and slope sensor.

J.-D. Kim et al. / Sensors and Actuators A 154 (2009) 157–168

167

6. Conclusion

Acknowledgements

In order to solve the compatibility problem of the Sensor-Ball so that the status of power transmission lines can be monitored and to provide the characteristic information of the Sensor-Ball and sensors conveniently to a user, this paper has designed the SensorBall system based on IEEE 1451.0. First, this paper has suggested the reference model that applies IEEE 1451 to the Sensor-Ball by using the IEEE 1451.0 and IEEE 1451.5 standards specified newly in 2007. Compatibility between Sensor-Balls can be maintained by following this reference model in building the Sensor-Ball system and this can obviate additional development needs for replacing or adding a Sensor-Ball. Second, this paper has defined the Sensor-Ball and the characteristic information of an external sensor with the TEDS format of IEEE 1451.0 specification. The plug and play function was enabled by providing the Sensor-Ball information with TEDS, thus reducing unnecessary tasks in the connection. Also, by providing the information that can diagnose the Sensor-Ball and operational status of the sensor with TEDS, the user can judge the reliability of the Sensor-Ball and sensor data. Third, this paper has applied the IEEE 1451.0 APIs for the control of the Sensor-Ball from FJB and has designed the API functions for controlling the TEDS of the Sensor-Ball. By applying the API functions for the initialization and transmission of TEDS within the Sensor-Ball, this paper allows for the transmission of the TEDS information in a common format structure. This paper has used these API functions in the control of the Sensor-Ball and TEDS transmission by applying them to the Sensor-Ball system structured for this experiment and has checked their normal operation. Application of IEEE 1451 in the Sensor-Ball system may have the following advantages. First, it is possible to diagnose the status of the Sensor-Ball system and sensors by sending the detailed information of the Sensor-Ball and sensors connected to the Sensor-Ball to the upperlevel system. Second, when the sensor included in the Sensor-Ball is changed or undergoes a change in its characteristic information, it is possible to control this in the upper-level system. Third, the interoperability between the Sensor-Ball and connected sensors can be secured. This paper has designed the Sensor-Ball system based on IEEE 1451 by using the information of sensors connected to the SensorBall while making use of virtual TEDS. However, this can not be a definite alternative to the saving of the information of sensors connected to the Sensor-Ball while making use of virtual TEDS. The reason being is that the Sensor-Balls connected with various types of sensors can not update virtual TEDS whenever the sensor is changed. Therefore, it should be changed in a way so that the sensor itself can provide its own TEDS information. In order to achieve this, the sensor manufacturers responsible for the SensorBall should provide sensors with built-in TEDS. However, it is not realistic for sensor manufacturers to apply IEEE 1451. Therefore, the IEEE 1451 conversion API or software should be provided so that the manufacturer can easily convert the sensor information suitable to the IEEE 1451 TEDS format. In the future, the Sensor-Ball system may be applied in various fields other than the monitoring of power utilities. In connection with various sensors, the Sensor-Ball system can be used in the monitoring of important areas or facilities related to military or security needs in addition to the monitoring of power transmission lines. Also, this technology can be used for the monitoring of forest fires. Additionally, by dividing the whole country into several regional circles, this system can also be used for providing detailed information suited to each circle by collecting necessary information such as weather and traffic conditions.

This Work was supported by Hoseo University’s World Class 2030 project and Power-IT National Program.

References [1] U.S. Department of Energy, Office of Electric Transmission and Distribution, “Grid 2030” A National Vision for Electricity’s Second 100 Years, July 2003. [2] T.J. Hammons, Integrating renewable energy sources into European grids, International Journal of Electrical Power & Energy Systems 30 (2008) 462–475. [3] USI: http://www.usi-power.com/. [4] Valley Group: http://www.cat-1.com/. [5] IEC 61850-1, Communication networks and system in substation—Part 1: Introduction and overview, 2003. [6] IEC 61850-2, Communication networks and system in substation—Part 2: Glossary, 2003. [7] IEC 61850-3, Communication networks and system in substation—Part 3: General requirements, 2002. [8] IEC 61850-4, Communication networks and system in substation—Part 4: System and project management, 2002. [9] IEC 61850-5, Communication networks and system in substation—Part 5: Communication requirements for functions and device models, 2003. [10] IEC 61850-6, Communication networks and system in substation—Part 6: Configuration language for electrical substation IEDs, 2004. [11] IEC 61850-7-1, Communication networks and system in substation—Part 7: Basic communication structure for substation and feeder, 2003. [12] IEC 61850-8-1, Communication networks and system in substation—Part 8-1: Mapping to MMS and ISO/IEC 8802-3, 2004. [13] IEC 61850-9-1, Communication networks and system in substation—Part 9-1: Sampled values over serial unidirectional multidrop point-to-point link, 2003. [14] IEC 61850-9-2, Communication networks and system in substation—Part 9-2: Sampled values over ISO/IEC 8802-3, 2004. [15] IEC 61850-10, Communication networks and system in substation—Part 10: Conformance testing, 2005. [16] IEEE1451, Standard working group: http://grouper.ieee.org/groups/1451/0/, http://grouper. Ieee.org/groups/1451/6/. [17] IEEE Std 1451.0-2007, A Smart Transducer Interface for Sensors and Actuators—Common Functions, Communication Protocols, and Transducer Electronic Data Sheet (TEDS) Formats. [18] IEEE Std 1451.1-1999, A Smart Transducer Interface for Sensors and ActuatorsNetwork Capable Application Processor (NCAP) Information Model. [19] IEEE Std 1451.2-1997, A smart transducer interface for sensors and actuators—transducer to microprocessor communication protocols and Transducer Electronic Data Sheet (TEDS) formats. [20] IEEE Std 1451.3-2003, A Smart Transducer Interface for Sensors and Actuators—Digital Communication and Transducer Electronic Data Sheet (TEDS) Formats for Distributed Multidrop Systems. [21] IEEE Std 1451.4-2004, A Smart Transducer Interface for Sensors and Actuators—Mixed-Mode Communication Protocols and Transducer Electronic Data Sheet (TEDS) Formats. [22] IEEE Std 1451.5-2007, A Smart Transducer Interface for Sensors and Actuators—Wireless Communication Protocols and Transducer Electronic Data Sheet (TEDS) Formats. [23] P. Hu, R. Robinson, J. Indulska, Sensor Standards: Overview and Experiences, Intelligent Sensors, Sensor Networks and Information 12 (2007) 485–490. [24] J. Wei, N. Zhang, N. Wang, D. Lenhert, M. Neilsen, M. Mizuno, Use of the “smart transducer” concept and IEEE 1451 standards in system integration for precision agriculture, Computers and Electronics in Agriculture 48 (2005) 245–255. [25] A. Pardo, L. Cámara, J. Cabré, A. Perera, X. Cano, S. Marco, J. Bosch, Gas measurement systems based on IEEE 1451.2 standard, Sensors and Actuators B 7 (2006) 11–16. [26] L. Bissi, P. Placidi, A. Scorzoni, I. Elmi, S. Zampolli, Environmental monitoring system compliant with the IEEE 1451 standard and featuring a simplified transducer interface, Sensors and Actuators A 137 (2007) 175–184. [27] N. Ulivieri, C. Distante, T. Luca, S. Rocchi, P. Siciliano, IEEE 1451.4: a way to standardize gas sensors, Sensor and Actuators B 3 (2006)141–151. [28] J-D. Kim, et al., The definition of basic TEDS of IEEE 1451.4 for sensors for an electronic tongue and the proposal of new template TEDS for electrochemical devices, Talanta 71 (2007) 1642–1651. [29] M. Armson, The status of IEEE 1451.4. Plug and Play, Honeywell Sensotec, Inc., Tech. Report 2003. [30] E. Song, Y. Kang Lee, An implementation of the proposed IEEE 1451.0 and 1451.5 standards, Sensors Application Symposium (2006) 72–77. [31] D. Sweetser, V. Nemeth-Johannes, A modular approach to IEEE-1451. 5 wireless sensor development, in: Sensors Applications Symposium, 2006, pp. 82–87. [32] A. Flammini, P. Ferrari, E. Sisinni, D. Marioli, A. Taroni, Sensor integration in industrial environment: from fieldbus to web sensors, Computer Standards & Interfaces 25 (2003) 183–194. [33] E.F. Sadok, R. Liscano, A Web-Services Framework for 1451 Sensor Networks, in: Instrumentation and Measurement Technology Conference, 2005, pp. 554–559. [34] G. Bucci, F. Ciancetta, E. Fiorucci, D. Gallo, G. Landi, A Low Cost Embedded Web Services for Measurements on Power Systems, in: VECIMS, 2005, pp. 2–7.

168

J.-D. Kim et al. / Sensors and Actuators A 154 (2009) 157–168

[35] D. Castaldo, D. Gallo, C. Landi, Collaborative Multi-sensor Network Architecture Based On Smart Web Sensors For Power Quality Applications, IMTC (2004) 1361–1366.

Yu-Kyung Ham received BS and MS Degree in Department of control and measurement Engineering from Samcheok National University in 2000 and 2002. He received his PhD degree in Electronic Engineering from Hoseo University in 1994. He is now senior engineer at Samsung Electronics Co.

Biographies

Chul-Ho Hong was born in Chong Ju, Korea in 1954. He received BS, MS and PhD his degrees in Electronic Engineering at the University of Sungkyunkwan, Korea in 1977, 1982, and 1989 respectively. His interests are application of sensor and control of robot.

Jeong-do Kim received his BS, MS and PhD Degrees in Electronic Engineering at the University of Sungkyunkwan, Korea in 1987, 1990 and 1994 respectively. He received his PhD in Electronic Engineering from Sungkyunkwan University in 1994. He was associate professor at department of electronics Engineering in Samcheok National University, Korea from 1995 to 1999. Since 2004, he is associate professor at Hoseo University. His research interests are sensor network, pattern recognition and signal processing based on artificial neural network. He specializes in sensor systems, which include hardware and software implementation of smart sensor system. Jung-Hwan Lee received BS and MS Degree in Electronic Engineering from Hoseo University in 2004 and 2006. He is now the doctor course in Department of Electronic Engineering at Hoseo University.

Byoung-Woon Min is now principal engineer at Hyundai Heavy Industries Co., ltd. Sang-Goog Lee received his BS and MS Degree in Electric Engineering from Inha University in 1988 and 1990. He received his PhD degree in Electronic Engineering from Rouen National University of France, 1994. He was assistant professor at department of electronics and information in Rouen National University, France from 1995 to 1999. He worked at Samsung Electronics Co. as a principle researcher from 1999 to 2006 in Suwon, Korea. His research interests are smart sensor, wearable computer, augmented reality and human computer interaction. Since 2006, he served as professor at the department of multimedia eng., Catholic University of Korea.