Kazuya Omata

Development of transient stability control system (TSC system) based on on-line stability calculation

This paper describes a new transient stability control system named the TSC system developed for application to the trunk power system of Chubu Electric Power Co. (CEPCO). The TSC system prevents wide-area power system blackout by shedding optimal generators when a serious fault occurs. This system has the following features: (1) the TSC system performs detailed stability calculations based on online information telemetered from the actual network, and it periodically evaluates the stability of the power system against contingencies with a high degree of accuracy. The system selects the optimum generators to be shed; (2) if a contingency actually occurs, the generators to be shed that were determined in advance are shed about 150 ms after fault occurrence to maintain the stability of the power system; and (3) the system can be applied to any power system configuration of CEPCO, such as a loop network, radial network, etc. The TSC system will be put into regular service in June 1995. It will be the worlds first real-time stability control system that performs detailed transient stability calculations on a large power system online.

Operator training simulator with real-time transient stability analysis

The operator training simulator (OTS) system, which is integrated with a real-time transient stability analysts program, has been in operation at the training center of Hokuriku Electric Power Company since July, 1990. The developed OTS system achieves real-time transient stability analysis with approximately 100 generator and 400 node power systems by parallel processing performed on a computer system with multiprocessor architecture. This paper outlines the developed OTS system and describes the requirements, design concepts, modeling and parallel calculation method of transient stability analysis and the verification result of the developed transient stability analysis program. >

Short circuit current estimation using PMU measurements during normal load variation

This paper purposes a short circuit current estimation method using phasor measurement unit (PMU) measurements (synhcrophasors, hereafter called as phasors) of voltages and currents obtained during normal load variation. The method follows the basic concept of representing the source side of power system by an equivalent circuit with a voltage behind back impedance and employs a set of voltage and current phasors measured at substations over a certain period. In order to improve an accuracy of the proposed estimation method, the concept of using a difference between the two consecutive phasors is introduced. Furthermore, to make the method applicable to a real world system, the estimation process is augmented by implementing a reference phasor concept to remove the effects of system wide frequency variations and a filtering process to filter out the outlier phasors. Finally, the validity and effectiveness of the purposed methods were checked and confirmed using field tests.