186 IEEE Transactions on Power Delivery, Vol. 13, No. 1, January 1998

Takamu Genji Technical Research Center

The Kansai Electric Power Co., Inc. Nakoji, 3-Chome, Amagasaki 661, Japan

Abstract-This paper describes a high-speed switching sys- tem for distribution networks which has been developed with the aim of improving power supply reliability (reducing the number of supply interruptions) of distribution systems. When a fault occurs in conventional distribution systems, the fault section is isolated using a sequential time-out control scheme which requires the reclosing and re-reclosing of the entire system. A major drawback of such systems is that normal sections are also subjected to unnecessary power supply interruptions. In order to resolve this problem, we have developed a high-speed switching system which isolates only the fault section without interrupting the power supply to normal sections. This new system can fully restore power to the normal sections and completely isolate the fault section within 500 ms in the case of a ground fault.

1. INTRODUCTION

Today’s highly information- and technology-oriented soci- ety is steadily increasing its dependence on electric power. At the same time, the requirement for high quality and highly reli- able power supplies is also increasing as the demand for power increases.

In response to this requirement, conventional distribution sys- tems have used an automatic switching system with a sequential time-out control scheme, which allows the isolation of fault sec- tions and normal sections by automatically opening and closing the switching system at the source side of the fault section.

In recent years the duration of power interruptions between a fault section and the end of load side sections has been sig- nificantly reduced by controlling the power supply after sepa- ration of the sections through the introduction of a remote con- trol switching system to the automated distribution system. Even with this automated system, a minimum of two power interruptions are unavoidable at the fault feeder. Taking into

PE-1 70-PWRD-0-03-1997 A paper recommended and approved by the lEEE Transmission and Distribution Committee of the IEEE Power Engineering Society for publication in the IEEE Transactions on Bower Delivery. Manuscript submitted July 8, 1996; made available for printing March 26, 1997.

Masao Shimamoto, Control & Telecom Department

DAIHEN Corporation Tagawa, Yodogawa-ku, Osaka 532, Japan

account the greater complexity and diversity of activities in metropolitan areas, the advent of the information-oriented society, advances in electric equipment, etc., society’s demand for less frequent power interruptions is expected to grow fur- ther in the near future.

In this context, the authors have developed a high-speed switching system for distribution networks which offers fewer and briefer power interruptions than existing switching control systems. The new system is intended to quickly obtain fault data and isolate a fault section, while maintaining uninterrupt- ed power supply to other normal sections without the need to operate the substation’s circuit breaker.

Since the high-speed switching system requires faster switching operations as well as interruption of fault current, the authors have also developed a switching control algorithm and a high-speed circuit breaker. This paper describes the outline of the high-speed switching system and the test results, with emphasis on the fault detection method and the section identi- fication algorithm.

2. CONVENTIONAL DISTRIBUTION LINE FAULT SECTIONALIZING SYSTEM

Existing distribution systems are divided into sections by automatic sectionalizing switches. If a fault occurs, these auto- matic sectionalizing switches and the sequential time-out con- trol system are coordinated with the reclosing system of the substation’s circuit breaker, so that the automatic switches are successively closed to isolate the fault section while continuing to supply power to the normal sections.

The supply of power to the normal sections located beyond the fault section is achieved through remote control of the switching systems linked to other distribution lines, based on the operation procedures prepared using system information stored in the office computer’s database.

The operation of the components of the system shown in Figure 1 when a fault occurs at point A is explained below. 1. A fault is detected at the substation and the circuit breaker

(FCB) is tripped. 2. Automatic sectionalizing switches SW1-SW3 are the no-

voltage opening type, and open simultaneously after a delay time limit has elapsed. SW4 is a connecting switch linked to other distribution lines.

3. After the reclosing time has elapsed (normally 1 min.) the FCB is reclosed.

0885-8977/98/$10.00 0 1997 IEEE

4. SW1 is charged and time limit has elapse

5. Similarly, SW2 closm limit has elapsed.

6. FCB is reopened SW2 has closed, it i,; within the detection

7. After the second rec ly 3 min.), FCB is

8. As with the reclosing supplied up to SW2.

9. The office’s comp operation procedures system information.

10. Following the opera1 er (SW4) is closed

As the above operai.ion unavoidable with tions (1 min. and 3 mir section isolation and required for preparing ti tions located beyond the tems can only perform determined system COI

determine operation pro

station

closes automatically after the closing d.

automatically after the closing time

once the fault section is charged. After locked open by a power interruption

time limit. osing time limit has elapsed (normal-

above, SW1 is closed and power is (SW2 is locked open.) iter system automatically prepares

for power supply redirection, using

ion procedures, the connecting break- a id SW3 is opened via remote control.

shows, power interruptions are conventional systems: two power interrup-

.) before the completion of the fault another 5-6 min. power interruption

e operation procedures in normal sec- fault section. Such conventional sys-

wtomatic fault sectionalizing on pre- figurations and take a long time to Sedures for redirection.

reclosed.

Figure 1: Aut matic Sectionalizing System for a 1 s istribution Network

dure (determination and the re-supplied (overloading of norral is made faster throu and monitoring of di:

3. OBJECTIVES AX D TARGET PERFORMANCE OF THE HIGH-SPI b ED SWITCHING SYSTEM

of the appropriate connecting switches c,ections) and processing of overloads

feeders caused by load redirection) zh simplification of the management tribution network status information.

In response to the ani

fault is expected to beco

requirement for more reliable

as well as the reduction

the following func- systems and to tions to eliminate

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3.2 System Configuration

System configuration is based on the existing automated distribution system and, as shown in Figure 2, is composed of the central station (1) in the office, a terminal (2) installed at the substation, pole-mounted terminal (3) and pole-mounted circuit breaker (4) connected to the terminal. Fault information from the sensor (CT, ZCT) installed in the pole-mounted cir- cuit breaker is detected by the pole-mounted terminal and obtained at the substation terminal.

The substation terminal recognizes the current configura- tion of the distribution system using system configuration information preset by the central station, and performs the fault section isolation, load redirection and re-supply proce- dures, together with the fault information obtained above.

Coaxial aahle Suhstation terminal 9’

unit (feeder fault detection unit)

Coaxial aahle Suhstation terminal 9’

unit (feeder fault detection unit)

Figure 2: System Block Diagram

Major Functions of Main Components Central Station: Responsible for sending system configura- tion information to the substation terminals, in addition to the standard central station functions of CRT display of dis- tribution line and switch status, and transmission of the sys- tem’s database information and remote commands. Substation Terminal: The system’s most highly functional component, responsible for detecting feeder faults, recog- nizing the system configuration, high-speed communica- tion, troubleshooting (fault section identification, isolation and re-supply, overload processing), in addition to the stan- dard functions of relaying monitor and control signals and transmitting substation status information. These functions are designed to speed up fault processing

by assigning some of the standard central station functions to the substation terminal, thus eliminating the transmission delay between the substation terminal and the central station.

Pole-mounted Terminal: Responsible for high-speed com- munication, fault processing (sensor information process- ing; opening when short-circuit currents are detected) and identifying the direction of ground faults, in addition to the standard functions of transmitting distribution line and switch status information to the office, and controlling the switch using signals from the substation. Pole-mounted Circuit Breaker: Capable of faster switching than conventional automatic switches, also responsible for interrupting short-circuit currents.

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3.3 Performance Requirement

3.3.1 Constraints

In the course of developing this system, the following goals were set, taking into account the ease of migrating from exist- ing automated distribution systems in actual use, and develop- ing a system as highly functional as possible. (1) In the event of ground and short-circuit faults, the fault section is isolated without operating the substation circuit breaker.

Since the substation circuit breaker operates in the event of ground and short-circuit faults for intervals of 0.5 sec. and 0.1 sec., respectively, the system must complete isolation of the fault section within these intervals. (2) The system promptly recognizes system configuration, which changes frequently.

Even when the normal system configuration temporarily changes for some reason (e.g. distribution line work), the sys- tem is able to accurately recognize the system status informa- tion required for fault processing. Therefore, pole-mounted breaker operation procedures for all system configurations must be determined to permit fault isolating and power supply redirection within the intervals specified above. (3) A maximum of 30 breakers controlled per distribution line are assumed.

Thirty controlled breakers are assumed to be installed per distribution line, taking into account the number of breakers necessary to sectionalize long-span dj stribution lines plus that for customers’ drop wires. (4) Existing communication lines are affected as little as pos- sible, and their reliability must not be affected even if addi- tional hardware is introduced. ( 5 ) The operation time limit of the substation circuit breaker remains unchanged, and the substation components (e.g. relays) must not require modification.

3.3.2 Function of the Algorithm

To implement high-speed isolaticin of a fault section and power supply redirection, it is essenti,al to identify a fault sec- tion and determine breaker operation procedures within an extremely short time.

One method of achieving this is to predetermine the opera- tion procedures for each potential fault section in a fixed system configuration, and tabulate them for quick reference. This method, however, cannot handle situations where system con- figurations diverge from those tabulated, or where there are multiple faults. Consequently, easy-to-use methods supporting complex and constantly changing system configurations were required, together with a universal algorithm capable of identi- fying a fault section while allowing sectional re-supply based on the system information. The basic functions of the algorithm developed are described below. The details of the algorithm and communication speed are described in the next section.

(1) System Configuration Recognition Logic Each breaker is assigned a unique breaker no. (e.g. pole

no.). In addition, the breaker nos. connected to the breaker’s source side (side 1) and load side (side 2), and the breaker’s Qn/Qff status are also stored in the substation terminal. By using this data, connections between the breakers are identi- fied and the overall configuration is recognized.

(2) Universal Identification Logic A fault distribution line is identified through the substation

relay information, and the fault information is then obtained via high-speed communication (polling) of the pole-mounted ter- minal installed on that line. This is a general-purpose technique for identifying a fault section using the fault information detect- ed at each breaker together with the system configuration infor- mation obtained in (1) above. (Identified using the breaker nos. on the source side and load side of the fault section.)

(3) Determination Logic for Sectionalizing and Re-supply Procedures

The connection between individual breakers is identified using the system configuration information obtained in (I), with the breaker number on the load side of the fault section identified in (2) as the origin. After power supply on the load side of the fault section is ensured by closing the appropriate breakers connecting the fault distribution line with other nor- mal lines, the load-side breaker is opened together with the breaker on the source side of the fault section.

Following the procedures in this order, it is possible to sec- tionalize the fault section while maintaining an uninterrupted power supply to the normal sections.

(4) Coping with Various Types of Fault The occurrence of faults at multiple points can be classified

as simultaneous and sequential. In either case, identification, isolation of the fault section and re-supply must be performed properly.

Based on the fail-safe principle, system configuration must ensure that the area affected by a power interruption is mini- mized and normal sections are never affected by the power inter- ruption, even if the fault section cannot be properly isolated.

3.3.3 Performance of the Communication System

Conventional systems use distribution line carrier systems and communication lines (pair, coaxial and optical cables) with low communication speeds of several hundred bps and 1200 bps, respectively. The polling transfer method is used, with the area defined by the central station and within which information is collected. This type of system requires consid- erable time to collect information from its terminals and does not meet the time requirements for the high-speed switching system. This is the reason a higher system communication speed must be used. The communication system adopted is described below.

~

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(1) Communication Spee As a criterion for

and based on the assumpt trol breakers per distribution each procedure was calculated detection, data collection ing breaker closing, and side of the fault section. cation speed must be 64 tion speed of 64 kbps cable, coaxial and optica nication media.

1 detlermining the communication speed,

on mentioned previously of “30 con- line,” the processing time for in the following sequence: fault

fault section identification, connect- lpening of the breaker on the source

The results showed that the communi- kbps or higher. Since a communica-

cannot be achieved currently using pair cables were adopted as the commu-

Communication is no1 ally performed using polling (half- systems, and in the event of a

(2) Communication Mod

duplex mode) as in fault, full-duplex

3.3.4 Operation Time

substation relay is 500 terms of system operatioi opening the breaker on the the time of fault detecticn Fault detection - Data tion - Connecting break the source side of the fa1 the load side of the fault

are described below. The results of estimating

two actions (selection and control) to one action (control only). This change is expected to result in an operation time at each point of approximately 100 ms.

ris. Therefore, target performance in time must meet the requirement of source side of the fault section from within 500 ms in the sequence of

collection - Fault section identifica- er closing - Opening the breaker on It section - Opening the breaker on section.

the respective processing times

(5) Open Time of the Breaker on the Source Side of the Fault Section

Approximately 90 ms is estimated, assuming the breaker’s operation time is a maximum of 50 ms.

The overall time required for the above steps is 430 ms, which satisfies the target operation time of less than 500 ms.

In the event of a short-circuit fault, the breaker on the source side of the fault section must open within 100 ms of the fault being detected. However, as shown above, data collection alone takes more than 100 ms.

For this reason, the following system configuration was implemented to handle short-circuit faults. The pole-mounted terminal is responsible for autonomous opening when a short- circuit fault occurs (i.e. the pole-mounted terminal makes its own decision and gives instructions for opening). In the event of a fault, therefore, the pole-mounted terminal that has detect- ed a short-circuit current on the source side of the fault section opens the breaker on its own initiative, then collects data on

In of a ground f ult the delay from Occurrence of a the side of the power interruption, identifies and sectionalizes

fault to the time when b i eaking signal is sent to FCB by the the section and thus the system.

(1) Fault Circuit Identific A maximum of 60 IT

requirement for the sub! function to identify a fa voltage data for each disi

supporting the relay

All data can be obtai ed within 170 ms, assuming a full- duplex polling mode of 3 0 units is performed at a communica-

(2) Data Collection Time

tion speed of 64 kbps. “ (3) Fault Section Identifi ation Time

The substation termii a1 recognizes the system configura- tion of a distribution lin fault, and identifies a fault section using the collected data. ’ he CPU processing time required for this is estimated to be ap i roximately 10 ms.

(41 Connecting Breaker i To save time the step changed from the usual

4. FAULT DETECTION PROCEDURE

4.1 Ground Fault

The substation terminal identifies a fault feeder using a combination of the zero-phase voltage of the transformer bus bar and the zero-phase current of each feeder. The terminal also recognizes a pole-mounted terminal used for polling to obtain fault information. The continued existence of the fault is confirmed by the presence of zero-phase voltage.

Detection by breakers sectionalizing a distribution line is performed by calculating the phase difference (Io - Vca) between the zero-phase current of the pole-mounted terminal which was input from the ZCT contained within the breaker and the voltage Vca supplied from PT (control power trans- former) also contained within the breaker. The pole-mounted terminal detects the ground fault phase information (detected at the substation terminal) contained in the polling signal from the substation terminal, and compares it with reference data and the above phase difference data, to determine the direction of ground fault occurrence. The result is returned as polling response.

The substation terminal identifies a fault section according to the universal identification algorithm using the fault infor- mation obtained above.

4.2 Short-circuit Fault

In the event of detection by each feeder at the substation, a short-circuit fault is identified when each feeder’s fault current exceeds the detection level. In the event of detection at the

190

breaker sectionalizing a distribution line, the value of the cur- rent running the distribution line is input to the pole-mounted terminal from the CT built in the breaker, and is taken to indi- cate a short-circuit fault when the current exceeds the detection level. The pole-mounted terminal that has detected a short-cir- cuit fault controls the breakers after the time limit determined according to the input current has elapsed. The terminal responds to the fault polling from the substation terminal by indicating detection of a short-circuit. The substation terminal that has collected fault information from the breaker connect- ed to the fault feeder thus identifies a fault section according to the universal identification algorithm.

5. DEVELOPED ALGORITHM

To meet the above performance requirement, an “algo- rithm for recognizing the system configuration and identifying fault sections using indexes representing connections” has been developed.

The overall basic flowchart for fault occurrence is shown in Figure 3.

Start

Self-decay timer start I

Universal identification logic I

Sectionalizing/re-supply procedures I I

I Closing of connecting breaker I L-

vnr 1

Restore to the or1 inal system by remote contropfrom the substation termnal

Isolatmg fault section I

G

;TYes I Closine of the breaker on the power source side I I -

I

Fault remains?

VpGnAng of ShG brSUhSr on the power source side Restore tn the original system by remote

control from the substation ternunal

End

Figure 3: Flowchart for Ground Fault

5.1 System Configuration Recognition Method For each of the breakers sectionalizing a distribution line,

the following information is recorded: breaker no.; address no.; openlclose status; the numbers of the breakers connected to the power source and load sides; and the operation mode. In addition, the openlclose status and operation mode are refreshed by regular polling and response to instructions. The latest system configuration can thus easily be recognized by checking the connections and the openlclose status of the breakers using this information. Examples of a system config- uration and its configuration information are shown in Figure 4 and Table 1, respectively.

Figure 4: System Configuration Example

Table 1: Data Indicating Distribution Network Structure

Breaker Normally closed Party Side 1 Side 2 Opedclose No normally opened line Address Breaker No Breaker No status

SI s2 s 3 s4 s5 S6 S l S8 s9 s10 s11 s12 S13

Closed Closed Closed Closed Closed Closed Closed Opened Opened Closed Closed Closed Opened

1 1 F11 1 2 S1, S5 1 3 s 2 1 4 s3, s9 1 5 s1, s 2 1 6 s5, SI 1 1 S5, S6 1 8 S l 1 9 s3, s4 1 10 F2 1 1 11 s10 1 12 s9,s11 1 13 s4

s 2 , s5 s 3

s4, s9 S13

S6, S l None

S8 F12

s11, s12 SI 1

s9, s12 None F22

On On On On On On On Off Off On On On Off

5.2 Fault Section Identification and Load Redirection Algorithm

When a fault has occurred, fault information is obtained from all breakers connected to the fault feeder, and the data of the breakers connected to the fault FCB is checked successive- ly. Based on this data and according to the universal identifi- cation logic, the fault section is searched for. Following the universal identification logic, at that point tho system configu- ration is interpreted as a tree-like structure as shown in Figure 5. Identification of a fault section is made from the terminal’s polling response information in the order indicated by the arrows. At this point, the breakers connected to one branch- point in the system are grouped by their index (n-value). A fault section among the circuit breakers is identified as shown in Figure 6. One circuit breaker is set as a reference point, and

191

if there is no “fault” polling circuit breakers (grouped the reference breaker, thc tion immediately following if there is a “fault” response the next group’s pollin); breaker as a new reference thus examined continuoiisly On the other hand, the ‘ updated through regular to examine the “on” roul above-mentioned status information. Consequently, the latest information, any system configuration, changed,

Fault 1st level

response received from any of the circuit breakers) connected beyond fault section is identified as the sec-

the reference breaker. Conversely, received from any of the breakers,

responses are examined using this breaker. The polling responses are

until a fault section is identified. openklose status” of the breakers is 3olling, and this algorithm is designed es successively while recognizing the according to the system configuration

since the substation terminal has fault sections can be identified within

even if the system configuration has

2nd level W‘th level ..................

Fault on s i d 2

Fault point

‘or Fault Section Identification Search

b Fault on side 2

Figure 5: Procedurc

Side 1 or I

Side 1 or I

Figure6: Fau

Next, in order to points with normal fe are searched accordinl cedures, and redirecte connecting breakers. system configuration ing from the fault sect tion are examined bas tion shown in Table 1. is connected to the Fc closed. From this poi nized by tracing the ‘ The same procedures I nized as being in the redirection has been E fault point.

..........

No fu l t

........ rlB-

etection No detection

etection No detecuon *2

Section Identification Procedure

rform load redirection, connection ers on the load side of a fault section 3 the sectionalizing and re-supply pro- jections are recognized by closing the onsequently, as Figure 7 shows, the interpreted as tree-like structure start- I, and link points beyond the fault sec- on the system configuration informa-

fter confirming that the circuit breaker I of the normal feeder, the breaker is the redirected section can be recog-

I” breakers back to the fault section. : performed for all the breakers recog- :cond level group, to check whether formed in all the sections beyond the

1st level 2nd level ”n“th1evel FCB connection Swconnection SW connection SW .............

_.

-7 Ld .............

f + Fault section

Figure 7: Sectional Re-supply Procedures

As previously mentioned, an algorithm with the following features was obtained by grouping the connections at the sys- tem’s branch-points using their indexes.

Simple data structure and low amount of data allow recog-

Real-time recognition of changes in the system configura-

Identification of a fault section and determination of re-sup-

nition of various system configurations.

tion is possible.

ply procedures can be performed in less than 10 ms.

6. DEMONSTRATION TEST RESULTS

A simple simulated system using a prototype apparatus (one substation terminal, four pole-mounted terminals, four pole-mounted breakers) was constructed to demonstrate the basic operation of the developed algorithm and the system operation time.

6.1 Test Conditions

A test circuit in Figure 8 was constructed using four high- speed circuit breakers in an isolated neutral system with a three- phase 200-V source voltage. Capacitors were connected between the lines and earth to produce the fault current. Since the fault feeder detection unit at the substation terminal comprised a 200- V simulated distribution line, a simulated fault information gen- erator was designed, capable of providing fault information by synchronizing it with the start of fault occurrence.

sw3 Ll̂ .̂:.._ 1 sw4 4

Figure 8: Simulated Test Circuit

F11, SW1, SW2 and SW4 in Figure 8 comprise a single distribution line, which was taken as fault distribution line. F11 and SW3 were taken as normal distribution lines and were assigned the role of load redirection.

6.2 Test Results

(1) Operation at Ground Fault Occurrence

a fault occurs at section 2. The results showed that the follow- Figure 9 shows the operational status of each section when

192

ing procedures were performed. Closing of normally open point (SW4) - 400 ms delay for

natural decay -Fault point power source side (SW1) opening - Fault point load side (SW2) opening - Reclosing timer (5s) delay - Reclosing (SW1 closing) - Fault continuation - SWI opening

The time required for each step measured from Figure 9 is shown Table 2 .

Time (ms) Item

Expanded waveform

Cumulative time h i s )

Figure 9 Operation Time Waveform (Ground Fault)

Table 2. Time Required lor Each Processing Step

0 Start of fault urocessine

Item

3 1 51

(0 Ground fault detection 12) Start of fault nrocessine

@ Re-supply procedure processing

@ Completion of universal identification procedure (3 completion of isolation and re-supply procedures (5) Natural decav time-out

35 506

I161 SWI off

Time (ms)

47 3

I (2%) Ground fault current termination

( 2 ) Operation for Short-circuit Fault

Cumulative time (ms)

47 50 +--p

300 394

Figure 10 shows the operational status of each section when a short circuit occurred at section 2. The results showed the following procedures were performed. Local opening (SW1) - Fault polling - Fault section identi- fication - Fault point source side (SWI) opening - Fault

point (SW4) - Reclosing timer (5s) delay - Reclosing (SWl closing) - Fault continuation - SWl opening (local opening)

The time required for each step measured from Figure 10 is shown in Table 3 .

point load side (SW2) opening ~ Closing of normally open

Figure 10: Operation Time Waveform (Short Circuit)

Table 3: Tiine Required for Each Processing Step

@ Completion of universal identification procedure I 180 I 231 @ Completion of isolation and re-supply procedures I 240 I 471

I o Short-circuit cui~ent termination 1 9 8 1 - 1

(3) Observations a. As seen from the above results, it was confirmed that €or a

ground fault occurring at a single point, the operation from identification of the fault section to power supply to the normal sections could be performed within the planned procedures and time.

b. The cumulative time up to breaking of the ground fault cur- rent in Table 2 does not include the arc extinction time of the breaker. However, even if the maximum value of the arc extinction time is assumed to be 10 ms, the cumulative time will be 479 ms, within the target system operation time of 500 ms.

c. It was confirmed that even if another fault occurred in the system after a fault section had already been sectionalized, the isolation of the fault section was possible. From this fact, i t was verified that fault sections could be correctly identified even if a system configuration change has been necessary. However, when there are ground laults at multiple points, especially at the same branch-point, the direction of the fault current is determined by the earth capacity in the fault section. This fact results in sections where faults cannot be identified, and thus the substation circuit breakers must be tripped.

However, if a faul was confirmed thai possible even if mi

d. Although the elap: cuit fault current ii target system time included.

The authors have d for distribution netwo its basic operation. 1 about the distribution the fault sections, whi ply to the normal sect breakers at the substat

This system is mor1 the following respects

Even if the system': this can be recogni: tion can thus be ide Load redirection brc ing to the identifica Reclosing is perfon five-second period, ing of an entire dist The authors intend

designed for actual a using actual voltage more complicated sysl

ection can be identified normally, it olation and re-supply processing was ple faults had occurred. time until breaking of the short-cir-

'able 3 is 98 ms, this may exceed the ' 100 ms if the arc extinction time is

CONCLUSION

doped an advanced switching system L and have successfully demonstrated s system collects fault information es at high speed and can isolate only naintaining uninterrupted power sup- IS, without the need to operate circuit

ivanced than conventional systems in I.

stribution line configuration changes, I almost immediately and a fault sec- Fied. ers can be identified quickly, accord- n of the fault section. d only in fault sections within a brief is avoiding the reclosing or re-reclos- ution network. conduct performance evaluation tests lications, including demonstrations stems and universal algorithms for is configurations.

193

BIOGRAPHY

Takamu Genji was born in Hyogo Prefecture, Japan on January 30, 1951. He received the B.S. and M.S. degrees in electrical engineer- ing from Okayama University, Okayama, Japan in 1973 and 1975 respectively.

In 1975 he joined the Kansai Electric Power Co., Inc. From 1978 to 1983 he was engaged in develop-

ment of distribution systems and equipment in the Distribution Department. Since 1985 he has been engaged mainly in research and development of distribution control systems using a two-way communication system at the Technical Research Center.

Mr. Genji is a member of the Institute of Electrical Engineers of Japan.

Masao Shimamoto was born in Wakayama Prefecture, Japan on December 8, 1963. He received the B.S. degree in electronic engineer- ing from Himeji Institute of Technology, Hyogo, Japan in 1987.

In 1987 he joined DAIHEN Corporation. Since 1987, he has been engaged in development of distribution equipment.

Koichi Kishida was born in Osaka Prefecture, Japan on October 22, 1952. He received the B.S. degree in electronic engineering from Kansai University, Osaka, Japan in 1975.

In 1975 he joined DAIHEN Corporation. Since 1975 he has been engaged in development of distribution equipment.

Mr. Kishida is a member of the Institute of Electrical Engineers of Japan.