use of internet technologies in relaying and control

USE OF INTERNET TECHNOLOGIES IN RELAYING AND CONTROL Hiroshi Watanabe, Katsuhiko Sekiguchi Phil Beaumont TM T&D Corporation, Japan Toshiba International Limited, United Kingdom

Abstract: The Internet is an attractive system that can link data measurement terminals widely distributed in a power system. The implementation of Internet technologies in protection and control systems can enable free and flexible acquisition of power system information from remote locations. By utilizing general-purpose Internet technologies such as IP telecommunication and browsers, widely distributed data can be easily collected. The implementation of Internet technologies within IEDs that feature these characteristics are already at a commercial stage in their application to the electric power system. This paper shows how the basic technologies have been utilized when applying Internet technologies to protection and control systems and briefly provides examples of practical systems using the basic technologies. Copyright © 2002 IFAC Keywords: Power system, IED, Networks, Measurement, Monitoring, Internet, Intranet

1. INTRODUCTION In view of the sweeping changes that have taken place in the electricity supply industry it is now, more than ever before, of vital importance that senior managers have easy access to processed data and information. This must provide them with knowledge about their systems and its constituent components. The implementation of Internet/Intranet technologies in protection and control systems can enable free and flexible acquisition of power system information at the appropriate location. There has been continued pressure on power utilities to enhance the availability and prolong the service life of their assets, reduce investment in equipment and personnel and to continue initiatives to further enhance operational efficiency. At the same time, customer expectations in respect to the reliability and quality of the power supply are higher than ever before. Consumers have become much less tolerant to power system outages and voltage dips and sags that can often severely affect industrial and commercial operations. One of the key approaches to accomplishing cost reduction, increased operational efficiency and an enhanced quality of power supply is in the

implementation of information oriented systems to collect widely distributed data and to process valuable information. It is also essential that the acquired data is shared, processed, analysed and diagnosed freely at the appropriate location. The utilisation of the Internet with protection and control is attractive in that it can be used to link systems that are widely distributed throughout the power system. The implementation of Internet technologies in protection and control systems and in plant monitoring devices has been proposed and are now already at commercial stage. [1][2][3][4][5][6] Effectively, the protection relay can be used as a data terminal. Internet technologies are being adopted at device level hence, individual protection and control systems handling real time power system data can now be connected to communication networks as servers that are autonomous in all respects. Each IED can function as an information terminal that delivers power system information. 2. BASE TECHNOLOGIES Figure 1 shows the basic architecture of the protection and control system applying Internet technology. The architecture separates the protection

and control equipment into a core area and a web area. The core area performs real-time protection and control for the power system. The web area is connected with servers and browsers through a communication network. The software of the web area is described in Java. This enhances conformity with the network environment and enables interoperability between different equipment types. Java is an object-oriented, safe, secure language that is hardware independent. The web area is realized by hardware which supports a Java virtual machine (JavaVM).

Fig. 1.

Basic architecture of the web-based IEDs

3.1 Remote Operation and Monitoring: The requirement to operate and monitor protection and control equipment from remote offices is becoming increasingly desirable. Some potential applications and benefits are listed below:• Substation information can be readily observed at different substations or remote locations using a general-purpose browser. • Information on measurement, monitoring, control, equipment status and protection, handled separately in the past can now be integrated. • Using the information determined from the data, remote maintenance and equipment monitoring can be readily performed. • Integrated management of electronic drawing systems can be effected using a database server; for example relay manuals can be accessed from the database server via the internet using browser software. Access to documents can be instant with electronic delivery straight to the location where they are required. Although more emotive, the actual software employed in protection and control equipment can be managed from a central location using the Intranet. Software changes necessitated by updating of a specification can be distributed to the relevant devices from the station server without interruption to in-service power apparatus. Clearly, the security of such systems is extremely important. However, manufacturers are examining methods that will impose strict access control. Remote Control Center

Remote Maintenance Center Browser

SCADA System

Server

WAN

GPS

Substation Browser RTU

Server GW

Substation

Figure 2 shows the software configuration of the web-based IED. The basic software includes the following features: - A data management system to provide real-time data access to the protection and control equipment - A server platform (Web server) that transmits real-time data from the core area - A communication platform that has a real-time event delivery function - A security system for access authority control and network management that notifies equipment problems - An agent platform to manage mobile agents

3. APPLICATIONS

Protection relays

Bay control un its

Fig.3 Web-based control and protection system

Core area

Web area

Fig. 2 Basic architecture of web-based IED

3.2 Fault Location and Disturbance Analysis Power system data is captured in the web-based protection relay. A GPS time stamp is added and the stored data is transferred to the server in the regional office by way of the Intranet. The server executes the processing of fault location calculations and undertakes waveform analysis simultaneously. High accuracy fault location, fault analysis and power system monitoring at remote offices can be achieved using wide area data. [7] Users at other locations could also access the result of the fault location calculation or waveform analysis. By adopting this approach, there are possibilities for power utilities to reduce the number of dedicated fault locators and

fault recorders and also improve the fault locator function for potentially a relatively small investment. FL/oscillograph Server at regional office

Browser

電力所 サーバ

GPS

GPS

Intranet GW

GW

Web applied relay

Web applied relay

Fig. 4 Web-based fault location and analysis 3.3 Power Quality Monitoring System Increases in the demand for electricity in urban areas, remote siting of large-scale power plants and IPP plants have all contributed to the increased complexity of power systems. To monitor the quality and stability of electricity in such complex power networks, systems are needed that have the ability to collect measured data that includes active and reactive power, frequency and voltage from many locations. Symptoms of power system abnormality can also be detected at an early stage. By installing web-based devices at data acquisition locations, power system data that is necessary to monitor power quality can be obtained in real time. 3.4 Power Equipment Monitoring System Routine maintenance of switchgear, transformers and other power system equipment has generally necessitated periodic visits to site. However, more recently condition-based maintenance approaches are attracting attention. This method regularly monitors the condition of plant and detects symptoms of failure in advance to optimise maintenance and service intervals. Various monitoring techniques are used for condition-based maintenance; for example the monitoring of SF6 gas density, partial discharges and circuit breaker contact wear. By adding web-based devices to existing power system equipment or by providing a web-based bay control unit with power equipment monitoring functionality, data for condition-based maintenance can be obtained through an Intranet system. The number of visits to site can be reduced and enable the mapping of planned maintenance. 4. SUMMARY Application of Internet technologies is spreading rapidly on a global scale and in various fields. The system shown in this paper is a typical application. IEDs embedding Internet technologies will evolve further and utilisation of power system wide information will expand in many fields.

5. REFERENCES [1] David G. Hart, William Peterson, David Uy, Jochen Scheneider, Damir Novosel, Ray Wright, “Tapping Protective Relaying for Power Quality Information,” IEEE CAP, 45-49, Jan. 2000 [2] K. Sekiguchi, et al., “Power System Protection and Control System Based on Intranet Technology - Concept and Basic Architecture,” in Proc. ICEE2000, E-2-04 [3] Z. B. Shukri et al., “Experience in Integrating Protective Relay Communication and Protocol Needs in Substation Automation Environment for the Grid Protection Integration and Monitoring Center,” in Proc. CIGRE Session - 2000, 34-105 [4] K. Hamamatsu, et al “A new approach to the implementation of intranet-based measurement and monitoring”, IEE DPSP, 2001 [5] R. Tsukui, et al, “Intranet-Based Protection and Control”, IEEE CAP, April 2001. [6] J.V. Hughes et al, “Substation information project – intranet trials”, CIGRE 2000 Session 23/39-04 [7] S. Imai, et al., “A Newly Developed Web-based Fault Locating Technology for Transmission Lines and Its Experience in the Field,” IEEE T&D Asia and Pacific Region, Oct. 2002 6. BIOGRAPHIES Hiroshi Watanabe received his B.S. degree in electronic engineering from Ehime University in 1979. In the same year he joined Toshiba Corporation. Since then he has been engaged in the engineering of power system protection and substation control, development of the numerical relays and also of the power system stabilizing systems. Hiroshi Watanabe is a member of IEEE. Katsuhiko Sekiguchi received the BS and MS degrees in communication engineering from the university of Tohoku, Sendai, Japan, in 1979 and 1981 respectively. He joined Toshiba Corporation in the same year and has been engaged in the development of protective relays and network computing applications for power system protection & monitoring. He is a chief engineer of Engineering & Manufacturing Department in TM T&D Corporation, Protection & Control Systems Division. He is a member of IEEJ and IEEE. Phil Beaumont is a technical director of Toshiba International (Europe) Ltd. He is principally responsible for product development and technical marketing of protection and control systems collaborating with TM T&D Corporation. Phil Beaumont is an IEEE Member and also an IEE Member.