Katsuhiko Sekiguchi

A remote supervisory system for a power system protection and control unit applying mobile agent technology

We apply mobile agent technology, which has attracted attention in the field of distributed software system, to a power system protection and control system. We have developed a system which can reduce the total cost of maintenance and management of protection and control equipment. We have proposed an Intranet Power System which performs supervisory control of a power system using Internet technology. We have proposed a mobile agent for power system protection and control system as part of the Intranet Power System. Although an agent is powerful in its ability to perform processing in a distributed network environment, a normal agent for business use does not offer a guarantee of operation within several milliseconds and real time performance. In this paper we propose the Real Time Mobile Agent Platform (RTMAP) which provides more powerful functions to synchronize between two or more agents in a distributed node, and redundancy to deal with unexpected communication failure. So the agent can now be applied to the power system protection and control system for which real time operation and advanced reliability are required. At present, a remote operating and monitoring system for protection and control equipment has been verified for real use and put into service. However, in order to perform maintenance or event analysis for two or more equipments, it is necessary for the operator to use the terminal (PC) for data collection and analysis, connecting and communicating each equipment individually. If we can use the agent proposed in this paper, then the information or equipment at two or more substations can be collected and analyzed automatically. Moreover if the database on a PC server performs further intensive management of data, then a full maintenance support system can be developed, and an increase more efficient maintenance work can be expected.

Live line measurement of untransposed three phase transmission line parameters for relay settings

The purpose of this study is to develop a method to measure untransposed transmission line parameters for protection relay setting. For relaying schemes such as distance relays, current differential relays and fault locators, it is very useful to ascertain the precise setting values in service, without the need for setting calculations prior to installation, and also for the relays to be able to adaptively change their settings as the system configuration changes. This paper describes a method of live line measurement of the parameters of an untransposed three phase one circuit transmission line and untransposed two parallel transmission lines and necessary conditions to measure line parameters. We propose a mathematical approach using synchronous voltages and line currents at both ends of the line in different states, where two models, the equivalent PI circuit and distributed constant line, are employed. For two parallel transmission lines, applying a mode decomposition, we show that two parallel transmission lines can be transformed into double independent three phase circuits. The efficiency and issues are shown using several simulation examples in MATLAB.

Information-theoretic approach to authentication codes for power system communications

The purpose of this study is to realize a practical method of providing cyber security for power system communications. Considering communication requirements needed for Smart Grids, power system communications can be classified into five main categories: real-time protection, supervisory control and data acquisition (SCADA), remote access, demand management system (DMS) and advanced metering infrastructure (AMI) . This paper describes a concept and method of effectively applying information-theoretic cryptography to these power system communications. From the requirements of real-time communication and long-term maintenance of such systems, we explore a novel scheme based on unconditionally secure authentication codes (A-codes) having short authenticators (authentication tags) and a feasible number of keys, and have developed a data format for the scheme. The efficiency of the scheme is illustrated using several examples and experimental results.

A recent trends in the implementation of Intranet based measurement and monitoring

The Internet is an attractive system that can link protection and control systems widely distributed within the power system. The implementation of Internet technologies in protection and control systems and in power equipment monitoring devices will allow free and flexible acquisition of power system information and equipment sensor information at remote locations. By utilizing general-purpose Internet technologies such as IP telecommunication and browsers, widely distributed data can be collected easily. The implementations of Internet technologies within products that feature these characteristics are already at commercial stage in their application to the electric power systems. This paper describes basic technologies applying the Internet technologies in protection and control systems and power equipment monitoring devices and provides practical systems using the basic technologies.

A method of measuring three phase transmission line parameters for relay settings

The purpose of this study is to develop a method to measure transmission line parameters for protection relay setting. For relaying schemes such as distance relays, current differential relays and fault locators, it is very useful to ascertain the precise setting values in service, without the need for setting calculations prior to installation, and also for the relays to be able to adaptively change their settings as the system configuration changes. This paper describes a method of untransposed live line measurement of the parameters of a three phase transmission line. We propose a mathematical approach using synchronous voltages and line currents at both ends of the line in different states, where two models, the equivalent PI circuit and distributed constant circuit, are employed. The efficiency and issues are shown using several simulation examples in MATLAB.

Protection relay systems employing unconditionally secure authentication codes

The purpose of this study is to produce practical cyber security for protection relay systems using communication channels, such as pilot protection schemes or wide area protection systems. This paper describes a concept and method of effectively applying unconditionally secure authentication codes (A-codes) to such protection relay systems. From the requirements of real-time communication and long-term maintenance of protection relays, we propose a novel scheme based on A-codes having short authenticators (authentication tags) and a feasible number of keys. The efficiency of the scheme is shown by several examples of pilot protection systems and wide area protection systems. The performance and the key management of the proposed algorithm are also discussed.

Adaptive filtering for noise reduction in the input circuits of protection relay systems

This paper describes an adaptive filtering to reduce noise in the analog input circuits of microprocessor-based protection relay (digital relay) systems. Considering that digital relays tend to have multiple functions, it is important to raise signal to noise ratios (SNR) in analog input circuits to a level that will satisfy the requirements of these functions. We have realized a noise reduction method employing an adaptive filter which can be generally applied; not only within digital relays but also for IEDs in substations and independent of protection schemes. This paper presents the concept of this method and illustrates this effectiveness using a number of examples and experimental results.

Power system communications and information-theoretic cryptography

The purpose of this study is to realize a practical method of providing cyber security for power system communications. Power system communications can be classified into three main categories: real-time protection, supervisory control and data acquisition (SCADA), and remote access. This paper describes a concept and method of effectively applying information-theoretic cryptography to real-time protection and control systems, such as pilot protection schemes, wide area protection systems etc. From the requirements of real-time communication and long-term maintenance of such systems, we propose a novel scheme based on unconditionally secure authentication codes (A-codes) having short authenticators (authentication tags) and a feasible number of keys. The efficiency of the scheme is illustrated using several examples of protection and control systems.

Network Computing Terminal as an Intelligent Information Terminal for Power Systems

Abstract The IT has been progressing rapidly, and all devices can be connected to networks, in order to realize anytime and anywhere computer-supported environment. In such situation, we propose the architecture of NCT (Network Computing Terminal) as an information terminal for power systems, and show some application examples. The NCT exactly acquires the phenomenon generated in power systems as digital raw data, edits it autonomously, and cooperates with other NCTs or PC servers if necessary. It can be applied for broad uses, such as fault analysis, measurement of power quality, and remote maintenance servicing.