ABSTRACT

Recently, due to concerns about the liberalization of electricity supply,

deregulation, and global impact on the environment, securing a reliable power

supply has become an important social need worldwide. To ensure this need is

fulfilled, detailed investigations and developments are in progress on power

distribution systems and the monitoring of apparatus. These are on (1) “digital

technology” based on the application of semiconductor high-speed elements, (2)

intelligent substations applying IT (information technology), and (3) system

configurations aimed at high-speed communication. Incorporated in these are

demands for the future intelligent control of substations, protection, monitoring,

and communication systems that have advantages in terms of high performance,

functional distribution, information-sharing and integrated power distribution

management. Today’s conventional apparatus also requires streamlining of

functions, improvements in sensor technology, and standardized interfaces. By

promoting these developments, the following savings for the whole system can

be expected: (1) reduced costs in remote surveillance in the field of apparatus

monitoring, operation, and maintenance, (2) reduced maintenance costs based on

the integrated management of equipment, and (3) reduced costs due to space

saving as a result of miniaturizing equipment.

CONTENTS

1. INTRODUCTION………………………………………………

…………………… 6

2. SUBSTATION…………………………………………………

………………………. 7

2.1. TRANSMISSION

SUBSTATION…………………………………………… 8

2.2. DISTRIBUTION

SUBSTATION……………………………………………. 8

3. INTELLIGENT

SUBSTATION……………………………………………….

10

3.1. CONCEPT OF INTELLIGENT

SUBSTATIONS…………………… 10

3.2. APPARATUS MONITORING

SYSTEM……………………………….. 10

3.3. POWER SYSTEM

CONTROLS……………………………………………. 12

4. DEVICES THAT CAN CONTRIBUTE

TO AN INTELLIGENT

SUBSTATION………………………….… 14

4.1. SWITCHGEAR AND

TRANSFORMER……………………………..… 14

4.2. PROTECTION AND

CONTROL………………………………………... 15

5. LATEST PROTECTION AND CONTROL

SYSTEM……………..… 16

5.1. UNIFIED PROTECTION AND CONTROL

UNIT……………….. 17

5.2. REMOTE CONTROL FUNCTIONS

BY WEB

CORRESPONDENCE………………………………………….. 19

5.3. CONNECTION BETWEEN PROTECTION/

CONTROL EQUIPMENT AND

APPARATUS……………………. 21

6. TASK FORCE SCOPE AND GENERAL

GUIDELINES…………… 24

6.1. TASK FORCE REPORT

OUTLINE……………………………………... 26

6.2. SUMMARY OF PANEL

PRESENTATIONS……………………….. 29

7. CONCLUSIONS………………………………………………

……………………. 31

8. REFERENCE……………………………………………………

……………………. 32

1. INTRODUCTION

The upgradation of our 500-kV trunk transmission system has almost been

completed, and the electricity system has been considerably improved. Yet, cost

reductions are required to cope with the entry of IPP (Independent Power

Producer) and the introduction of power source distributors caused by the

deregulation of electric utilities. To achieve this, each electricity supply company

is decreasing expenditure by efficiently using equipment, improving operations,

and effectively controlling plant-and-equipment investment. In addition, power

systems will become more complex, requiring operation in an uncertain and less

structured environment. Consequently, secure and economic operation of power

systems requires improved and innovative methods of control. The power

distribution system also requires reductions in initial investments, such as the unit

price of apparatus and miniaturization, and reduced costs for the whole life cycle,

including the operation/maintenance costs of the substation system. The

construction of a new power distribution system has been considered to meet

these requirements. It will adopt “digital technology” and “IT-related

technology,” which has made rapid advances in recent years.

This system aims at minimizing the total cost, not only reducing of the

unit price but also the cost of installation, construction, operation, and

maintenance. This article discusses the construction of intelligent substations in

the power distribution system, as well as protection/control-unified equipment as

examples of the new technology.

2. SUBSTATION

A substation is a part of an electrical generation, transmission, and

distribution system. Substations transform voltage from high to low, or the

reverse, or perform any of several other important functions. Electric power may

flow through several substations between generating plant and consumer, and its

voltage may change in several steps.

A substation that has a step-up transformer increases the voltage while

decreasing the current, while a step-down transformer decreases the voltage

while increasing the current for domestic and commercial distribution. The word

substation comes from the days before the distribution system became a grid. The

first substations were connected to only one power station, where the generators

were housed, and were subsidiaries of that power station.

Substations generally have switching, protection and control equipment,

and transformers. In a large substation, circuit breakers are used to interrupt any

short circuits or overload currents that may occur on the network. Smaller

distribution stations may use recloser circuit breakers or fuses for protection of

distribution circuits. Substations themselves do not usually have generators,

although a power plant may have a substation nearby. Other devices such as

capacitors and voltage regulators may also be located at a substation.

Substations may be on the surface in fenced enclosures, underground, or

located in special-purpose buildings. High-rise buildings may have several indoor

substations. Indoor substations are usually found in urban areas to reduce the

noise from the transformers, for reasons of appearance, or to protect switchgear

from extreme climate or pollution conditions.

Where a substation has a metallic fence, it must be properly grounded

(UK: earthed) to protect people from high voltages that may occur during a fault

in the network. Earth faults at a substation can cause a ground potential rise.

Currents flowing in the Earth's surface during a fault can cause metal objects to

have a significantly different voltage than the ground under a person's feet; this

touch potential presents a hazard of electrocution.

2.1.TRANSMISSION SUBSTATION

A transmission substation connects two or more transmission lines. The

simplest case is where all transmission lines have the same voltage. In such

cases, the substation contains high-voltage switches that allow lines to be

connected or isolated for fault clearance or maintenance. A transmission station

may have transformers to convert between two transmission voltages, voltage

control/power factor correction devices such as capacitors, reactors or static VAr

compensators and equipment such as phase shifting transformers to control

power flow between two adjacent power systems. Transmission substations can

range from simple to complex. A small "switching station" may be little more

than a bus plus some circuit breakers. The largest transmission substations can

cover a large area (several acres/hectares) with multiple voltage levels, many

circuit breakers and a large amount of protection and control equipment (voltage

and current transformers, relays and SCADA systems). Modern substations may

be implemented using International Standards such as IEC61850.

2.2.DISTRIBUTION SUBSTATION

A distribution substation transfers power from the transmission system to

the distribution system of an area. It is uneconomical to directly connect

electricity consumers to the main transmission network, unless they use large

amounts of power, so the distribution station reduces voltage to a value suitable

for local distribution.

The input for a distribution substation is typically at least two transmission

or subtransmission lines. Input voltage may be, for example, 115 kV, or whatever

is common in the area. The output is a number of feeders. Distribution voltages

are typically medium voltage, between 2.4 and 33 kV depending on the size of

the area served and the practices of the local utility.

The feeders run along streets overhead (or underground, in some cases)

and power the distribution transformers at or near the customer premises.

In addition to transforming voltage, distribution substations also isolate

faults in either the transmission or distribution systems. Distribution substations

are typically the points of voltage regulation, although on long distribution

circuits (of several miles/kilometers), voltage regulation equipment may also be

installed along the line.

The downtown areas of large cities feature complicated distribution

substations, with high-voltage switching, and switching and backup systems on

the low-voltage side. More typical distribution substations have a switch, one

transformer, and minimal facilities on the low-voltage side.

3. INTELLIGENT SUBSTATION

3.1.CONCEPT OF INTELLIGENT

SUBSTATIONS

In conventional substations, substation apparatus, such as switchgear and

transformer, control, protection and monitoring equipment is independent of

every other device, and connection is based on the signals coming through the

cable. On the other hand, an intelligent substation shares all information on

apparatus, control, protection, measurement and apparatus monitoring equipment

through one bus by applying both “digital technology” and “IT-related

technology.”

Moreover, high efficiency and miniaturization can be achieved because

the local cubicle contains unified control/protection and measurement equipment

that is one integrated system (see Fig. 1). Since an optical bus shares the

information between the apparatus and equipment, the amount of cable is sharply

reduced. Moreover, as international standards (IEC 61850 and 61375 etc.) are

adopted and the system conforms to the telecommunications standard, equipment

specifications can be standardized for different vendors.

3.2.APPARATUS MONITORING SYSTEM

All the data from each monitoring and measuring device is transmitted and

used for a higher-level monitoring system via an optical bus. The required data is

accessed through the Intranet or the Internet at the maintenance site of an

electricity supply company or a manufacturer and the apparatus can be monitored

from a remote location. The construction, analysis and diagnosis of the database

including trend management and history management also become possible. As a

result, signs of abnormalities can be checked out well in advance, and prompt

action can be taken in times of emergency.

Maintenance plans can also be drafted to ensure reliability, by inspecting

revision description and parts management, efficient maintenance planning and

reliability maintenance are also realized simultaneously.

Fig. 1—Intelligent Substation System Configuration (Image). The whole substation system is combined by optical LAN, and apparatus composition is

simplified.

3.3.POWER SYSTEM CONTROLS

Power system controls can be broadly classified into two categories: local

and area (regional/system-wide). The boundary between these two categories is

not precise as area controls are often implemented by optimally adjusting local

control parameters and set points. Area controls main characteristic is the need to

process information gathered at various points of the network and to model the

behavior of large parts of the power system. This type of control is usually not

limited to the automatic feedback type but often includes strategies based on

empirical knowledge and human intervention. Local control, on the other hand, is

typically implemented using conventional automatic control rules, such as, PID

control, which are believed to offer adequate performance in most applications.

Still, this is not to discount the usefulness of new intelligent methodologies, such

as, fuzzy logic controllers, for local controls.

For convenience, power system higher level controls are classified here as:

Generation scheduling and automatic control: includes unit commitment,

economic dispatch, and automatic generation control; in the past, well

established control methods were used but this situation has been changing to

deal with the new scenario created by the power industry restructuring;

Voltage control: is mostly of the local type but some systems have already

gone to a higher coordinated secondary control to allow a more effective use

of reactive power sources and increase stability margins;

Preventive security control: has the objective to detect insecure operating

points and to suggest corrective actions; the grand challenges in this area are

on-line Dynamic and Voltage Security Assessment (DSA and VSA);

Emergency control: manages the problem of controlling the system after a

large disturbance; it is an event driven type of control and includes special

protection schemes;

Restorative control: its main function is to re-energize the system after a

major disturbance followed by a partial or total blackout.

Intelligent system techniques may be of great help in the implementation

of area power system controls. Most of these applications require large quantities

of system information, which can be provided by modern telecommunications

and computing technology, but require new processing techniques able to extract

salient information from these large sets of raw data. Importantly, such large data

sets are never error free and often contain various types of uncertainty. Finally,

control actions may be based on operating strategies specified in qualitative form,

which need to be translated into quantitative decisions.

An important aspect to be considered in the implementation of power

systems controls is that, in the restructured power system environment, several of

these activities will fall under the category of ancillary services. Therefore,

besides the technical issues, economic and financial infrastructure should be

taken into account in the design and implementation of control schemes.

Information regarding the state-of-the-art in the application of intelligent systems

to power system problems can be found on the bibliography listed in section VII.

4. DEVICES THAT CAN

CONTRIBUTE TO AN INTELLIGENT

SUBSTATION

4.1.SWITCHGEAR AND TRANSFORMER

The burden can be drastically decreased because the sensor signal from

the PCT is digitized at the sensor output edge and the load on the PCT only

reaches that of an A-D (analog-to-digital) converter. Rogowski coils are used as

the current sensors and capacitive potential dividers are used as the voltage

sensors. These sensors drastically reduce the size of the switchgear (see Fig. 2).

Fig. 2—Gas Combined Switchgear Miniaturization by Digital Correspondence

Sensor. 550-kV GCS (gas combined switchgear) is shown as an example.

GCB: gas circuit breaker

CT: current transformer

PT: potential transformer

Present studies on miniaturizing conventional equipment have so far been

aimed at standardizing series. Advanced miniaturization will be attempted by

digitizing this system, corresponding to its need.

4.2.PROTECTION AND CONTROL

Intelligent substations require protection and control equipment to be

installed outdoors and this needs to be compact so that the local cubicle is able to

contain them. Outdoor installation requires improvements in insulation against

heat and airtightness besides parts reliability. Compact protection and control

equipment will generate demand for unified fabrication of protection/control and

high-density components. The current protection/control system that uses

compact equipment is described below.

5. LATEST PROTECTION AND

CONTROL SYSTEM

Trends in Protection and Control Systems :

Due to the rapid progress in today’s information field, applying digital

technology and adding IT function to the protection/control system are possible,

to support stable power supply, and improve maintenance. In Japanese

protection/control systems, digitization has made advances since the last half of

the 1980s. Digital technology has unique advantages, namely minimizing

maintenance and improving reliability, and it has speeded up the conversion from

individual analog-type to digital-type relays.

Now, however, digitization is not only required for independent single-

function equipment, but for the “systematic operation and employment” of the

whole substation. Such systems have greatly improved efficiency in employment

and maintenance using IT. The key phrases to fulfill these needs are as follows:

(1) Slimming of total system as a protection control equipment

→ Unification of equipment

(2) High efficiency of employment/maintenance support using IT

technology

→ Extended employment/maintenance by remote control

(3) System directly linked to the equipment for protection/control

→ Distributed installation near the apparatus

Thus, there has been a need for constructing a high efficiency system

through system-wide miniaturization and integration of IT.

5.1.UNIFIED PROTECTION AND

CONTROL UNIT

The protection and control units of the substation are designed and

allocated with respect to individual functions and uses.

Units are made according to their respective protection and control object.

A cable or an exclusive-use LAN transfers the information between the

protection/control equipment (see Fig. 3).

Fig. 3—Example of Combination of Optical LAN Application and Protection/Control Equipment, and Problems of Large-scale System.

The present substation system consists of exclusive use of LAN (local-area network) for every information unit.

In detail, the information from the protective unit is transmitted to DAU

(data acquisition unit) by optical transmission, and is then forwarded to the

control room terminal, which has superior control. Such method is generally and

commonly used.

This system’s digital equipment, protection, control, and information

object equipment have a common basis. Therefore, combining the control/

protection equipment of every circuit unit can slim the total system.

This equipment is compact, and configures the protection and the control

units in one cubicle. Thus, hardware is reduced and there are considerable

savings in power consumption.

The functions of the operation unit, which is the central component of the

equipment, can be improved and shared, reducing the number of sections. As the

dimensions of the whole unit are reduced by 50%, both the protection and control

units can be configured into a single unit. The characteristics of this single unit

are discussed below:

(1) Operation unit

The protection and control units need to be separated in the operation unit,

which is equivalent to the center of the unit.

Therefore, the CPU (central processing unit) was separate and the use of a

high-performance 32-bit RISC (reduced instruction set computer) processor

enabled us to reduce the total number of boards to 70%.

(2) Input Transducer

The input transducer, providing input current and voltage to the system,

was until now, individually mounted away from the operation unit. However

adopting a toroidal coil reduced the space by half, but doubled the number of

mountings. The input section was improved to the extent that it is only a card

mounted in the operation unit.

(3) Power unit

The power unit supplies power to the operation unit. As the number of

CPU boards applied to the operation unit has been reduced and the application

circuit for the protection/control unit has been standardized, the power supply

capacity is halved as is the mounting space. Consequently, the power unit has

become so compact that it can be mounted in the operation unit.

(4) Interface

By mounting the Ethernet* LAN port in the operation unit, it can now

respond to a flexible network configuration. Ethernet LAN is based on the TCP

(transmission control protocol)/IP (Internet protocol), which is a general-purpose

standard network interface. This is a high performance all-in-one operation unit.

We slimmed down the system by mounting the protection and control equipment,

which until now had been independent, into a single 350-mm width panel (see

Fig. 4). The advantages of this equipment are as follows:

(a) Perfect isolation between protection and control unit from input to

output

(b) Large reduction in installation space (Half the conventional space)

(c) Direct coupling between protection and control unit by an isolated

interface

5.2.REMOTE CONTROL FUNCTIONS BY

WEB CORRESPONDENCE

The amount of operation and maintenance needs to be reduced and

detailed information in real time is required on the digital protection and control

unit, during disturbances, or when the operations manager is notified of changes

in the status of local equipment to ensure system stability. Also, there have been

demands for remote operation, and manned-control-station operation to remote

unmanned substations. A conventional digital panel saves and analyzes system

information (the current/voltage data) when faults occur, and the CPU has highly

automated observation functions.

However, our system collects the voltage and current data that is saved

inside the panel, in the remote maintenance section, and the results of automatic

observation are analyzed and applied immediately. The system has an interface,

which directly acquires the data via the network from the protection and control

units in the substation.

It is normally situated in the processing unit and the various kinds of

information and operations supplied from the remote end, enable us to view

progress in the network (see Fig. 5).

Fig. 4: Compact Type Operation Unit and Single Protection/ Control Equipment.

The protection and control part are separated by independent structure,

and CPU, input transducer and power supply unit are mounted in equipment. A

protection unit is shown in the right of this figure.

The interface characteristics are as follows:

(1) The TCP/IP which is widely used as the standard network interface has

been adopted, improving operability enabling easy access to exclusively

used networks. By using an ordinary browser, most personal computers

can access the network easily.

(2) The server is in the panel, and individual and detailed information is

disclosed to the operator as web-site information. Also, the information is

accessible by many clients at the same time via an exclusive-use network,

and the data is the same even when faults occur.

(3) By using an ordinary browser, connection using a general public circuit is

possible without limiting the communication medium or use of the

exclusive network.

The cost of the communication and network equipment is reduced, and as

the system is highly efficient, it further reduces costs.

5.3.CONNECTION BETWEEN

PROTECTION/CONTROL EQUIPMENT

AND APPARATUS

In this system, the substation and the maintenance site are connected with

the exclusive-use network in random time. The system can be constructed with

shared and same-time data. Furthermore, the control and protection units are

dispersed on the outside of the cubicle, with the units and the equipment

communicating directly to one another. As a result, a large-scale substation

system can be constructed at low a cost (see Fig. 6).

The system has the following advantages because the protection and

control units are placed near the equipment:

(1) Reduced mounting space for the protection and control units

(2) Reduced construction costs by shortening the cable route from the

equipment to the units, and the construction period

(3) Higher reliability of information because the e information from the

equipment is directly transmitted to the network.

Fig. 5— The Example of Construction of a Network and Simultaneous

Employment of Data.

By mounting general-purpose network interfaces as standard, it is possible

to carry out operation and check the data simultaneously with the equipment of

the other site by the ordinary browser. From now on, the system configuration

increasing operation efficiency is also expected.

Increased reliability is expected, as a higher class network is multiplexed

with one for waiting and the f other for regular use. Here, the regular diagnosis

for t each unit is possible, by establishing an exclusive-use a server in both the

maintenance site and the substation.

Utilizing the system for future diagnoses is possible.

Fig. 6—Direct Combination of Apparatus, and an Example of Network

Application.

Intensive management of equipment and protection/control information is

attained by arranging cubicle type protection/ control equipment near the

apparatus, and carrying out network combination of this equipment.

6. TASK FORCE SCOPE AND

GENERAL GUIDELINESThe established scope for TF 38.02.20 is as follows :

To review the current implementation of power system controls, including the

role of human operators;

To review changes in the operation and control requirements of future power

systems and identify the limitations of existing methods of control in meeting

these requirements;

To review advances in intelligent system techniques and identify how they

may be applied to meet the expanded control requirements of future power

systems by complementing conventional controls and replacing some of the

functions performed by human operators;

To develop guidelines for implementation of advanced controls using

intelligent systems to assist in the secure and economic operation of power

systems in the new electric utility environment.

In order to narrow the broad range of topics that may be included under

the topics in the TF scope, some general guidelines were established with the

intention of helping the TF members on focusing their work on aspects of the

problem considered more relevant. These guidelines are:

Emphasis will be on operator decision aids as opposed to feedback control

methods or design. Operators are seen by many to have taken a great amount

of new responsibilities in the deregulated environment without appropriate

advances in decision aids and so there is a clear need of improvement in

operator tools.

Further, there is less consensus surrounding the use of intelligent closed loop

control in reliability critical systems, such as the power system, although

intelligent controls are generally accepted as useful in consumer product

applications.

All intelligent system methods will be considered, which includes as a

minimum symbolic processing (e.g., rule-based systems, logic programming,

model-based reasoning), computational approaches (e.g., fuzzy sets, artificial

neural nets), evolutionary programming, and genetic algorithms. The lines of

separation among the various categories of intelligent approaches have

blurred in recent years. In addition, these methodologies are more easily

linked in the types of complex problems to which they are applied and thus

for completeness in the applications, all methods should be considered.

Consideration should be given to fundamental understanding of operator

needs and operational requirements, including interpretation of output and

presentation of analysis. There has been some concern that operator needs

have not been given the proper emphasis in prototype control center

applications, which has limited the usefulness of the developed tools. There

may be a need to initiate a survey of operator needs and experience.

Intelligent systems as an assistant for training operators should be included in

the report. This may also be the natural link for including operator experience

in developed systems. Training is seen by many as one of the most useful and

important applications of intelligent system techniques.

Management of uncertainties should be carefully considered, including

probabilistic techniques and risk analysis. There appears to be greater need

within the control center for understanding of risk and uncertainties that will

arise in a competitive environment. This is particularly true as it relates to

financial risks. There appears to be some role for intelligent systems in

assisting the operators in the management of risk.

The scope of the report should be limited to operations with minor

consideration of operational planning but specifically does not include

planning. In the interest of time and focus, the report will serve a better

purpose by avoiding the broader issues that develop under planning.

6.1.TASK FORCE REPORT OUTLINE

The authors believe that an efficient way for the TF to perform its duties is to

agree upon a report outline and to assign writing responsibilities to chapter lead

editors and contributors. Later, the work performed by the members responsible

for each chapter will be reviewed and re-oriented, if necessary, at the TF

meetings. Most of the cooperative writing work is expected to be performed by e-

mail. In the following, a first draft of the report outline is presented to be used as

a starting point for the definition of its final version.

BACKGROUND

Scope of applications :

Limiting to power system operations

Power system planning outside scope

Scope considered for intelligent system methods :

Rule-based methods/Logic programming Model-based reasoning

Artificial neural nets

Evolutionary programming

Approximate reasoning (fuzzy sets, certainty factors, etc.)Sumary of report conclusions

POWER SYSTEM OPERATION

Control functions and time frames :

Open and closed loop

Time frames of interest

Decision requirements in operations :

Operator responsibilities

Centralized vs. decentralized

Limitations of existing tools :

Response to changing and unforeseen conditions

Usefulness of infrequently used applications

Complexity of system prevents possibility of all situations being fully

analyzed

Inability to improve with experience or easily incorporate experience

Trends in operations :

State of the art

Recent computational advancements

Developments in static and dynamic security methodologies

Survey (or discussion) of operator needs

Movement towards real-time controls

Challenges arising from the new utility environment :

New operator responsibilities

Increasingly stressed systems

Possibility of broader fluctuations in system operating conditions arising

from power sales and contracts

Data limitations; concerns of proprietary data

Regulatory requirements/restrictions on centralized decisions

Variations in regulations from region to region

APPLICATION OF INTELLIGENT CONTROL METHODS FOR OPERATIONS

Review of previous CIGRÉ and other historical

efforts :

Preventive/security control: Static and Dynamic

Emergency controls

Restoration control

Operational planning

System design aids vs. decision aids

State of the art and applicability :

Review of methods

Rule-base/logic approaches

Artificial neural nets

Approximate reasoning

Evolutionary programming and genetic algorithms

Limitation of methods :

Limits of formal performance measures

Concerns with reliability of adaptive/learning methods

Computational concerns for faster controls

Implementation concerns

New application areas identified by report :

Economic controls – interaction with trading and contracts

Controls as ancilary services

IMPLEMENTATION

Guidelines/requirements :

Hardware

Software

Control center integration

Operator training/user interface

Evaluation/testing methodologies :

Logical verification methods

Simulation approaches

Software maintenance and updates :

Regular improvements in knowledge base

6.2.SUMMARY OF PANEL

PRESENTATIONS

This panel presents five papers. The papers concern topics related to

security assessment, emergency control and control center operations under

deregulation. These provide a sampling of problems appropriate for application

of Intelligent Systems techniques. The papers are summarized in the following:

On-line Dynamic Security Assessment :

This paper describes experiences in developing an efficient and effective

tool for online DSA and points out problems that can be solved with artificial

intelligence. Traditionally, the primary difficulty for on-line dynamic security lay

in the required computational speed. Recently, technological advances have

greatly increased processor power and some former barriers have been removed.

Still, there are areas tasks that cannot be managed effectively on computations

alone but require engineering judgement, experience and analysis. These tasks

may be best addressed by Artificial Intelligence programming techniques.

Using a Neural Network to Predict the Dynamic

Frequency Response of a Power System to an Under-

Frequency Load Shedding Scenario : This paper proposes a

method to quickly and accurately predict the dynamic response of a power

system during an underfrequency load-shedding scenario. Emergency actions in a

power system, due to loss of generation, typically, calls for underfrequency load

shedding measures. Due to the slow and repetitious use of dynamic simulators,

the need for a fast and accurate procedure is evident when calculating optimal

loadshedding strategies. A neural network (NN) seems to be an ideal solution for

a quick and accurate way to replace standard dynamic simulations. The steps

taken to produce a viable NN and corresponding results will be discussed.

Intelligent systems applications to emergency

control :

This paper discusses the needs for more effective emergency control

systems and the possibilities of using intelligent systems to reach this goal. The

paper provides also pointers to already published work on using intelligent

systems in this context.

Control Centre Operations and Training under Deregulation A New Zealand Example :

This paper presents an overview of the control centre operation

environment after deregulation in New Zealand. New Zealand is one of leading

countries that has deregulated the power industry. As a result, the transmission

network operation has become more market driven. The control centre operation

environment has subsequently changed from low cost based to market based

optimization. The roles of the control centre personnel have changed. There is

more focus on risk analysis, real time operational planning and real-time power

system security. A brief review of the changes followed by some valid opinion of

the control centre personnel are also discussed in this paper.

7. CONCLUSIONS

We described the emerging new technology in the electricity supply

system. With the progress in communication technology and expansion of IT-

related technology, research and development have also been progressing based

on the concept of an intelligent system, not only on units or equipment, but also

the constitution of the system itself. It is entirely conceivable that the needs of

future clients will become even more diversified in this field. We will have to

speed up the development and release of products that have compatibility and are

low in cost, in accordance with the demands of these future clients.

8. REFERENCE

1. F. Iwatani et al., “Protective Relaying System Technologies Contributed

to Optimum Equipment Configuration in Electric Power Network

Systems,” Protective Relaying System Study Group, Asian Conf. on

Power System Protection (Oct. 2001)

2. www.ieee.org