Haruhito Taniguchi

Estimation of power system inertia constant and capacity of spinning-reserve support generators using measured frequency transients

A procedure for estimating the inertia constant M(=2H) of a power system and total on-line capacity of spinning-reserve support generators, using transients of the frequency measured at an event such as a generator load rejection test, is presented. A polynomial approximation with respect to time is applied to the waveform of the transients in estimating the inertia constant, and a simple model based on the idea of average system frequency is assumed in estimating the capacity of the generators. Results of the estimation using the transients at 10 events show that the inertia constant of the 60 Hz power system of Japan is around 14 to 18 seconds in the system load base, and the capacity of the spinning-reserve support generators is 20 to 40% of the system load. The proposed procedure is expected to be tested by Kansai Electric Power Company with increased number of events. This effort will contribute to estimate and evaluate the dynamic behavior of the system frequency in loss of generation or load.

FCL location selection in large scale power system

Maximum short circuit current of a modern power system is becoming so large that the current should be reduced to make more efficient use of power system transmission capability. The fault current limiter (FCL) is a promising solution of this problem and it can be categorized into two types: constant impedance type FCL and current limiting type FCL. Current limiting type FCL such as rectifier type superconducting FCL (RSFCL) has variable equivalent impedance depending on the limit of the current through FCL and power system impedances. In this paper, a method is proposed to incorporate RSFCL into short circuit current analysis, which is needed to evaluate the effectiveness of FCL installed in a large scale power system. Also, an efficient method to find FCL locations suitable for reduction of short circuit currents of more than one fault location is developed. The efficiency and effectiveness of these methods are shown by numerical examples.

A model of fossil fueled plant with once-through boiler for power system frequency simulation studies

A model of a fossil fueled generating power plant with a once-through boiler for power system frequency simulation studies is presented. In the model, the plant control system is modeled to represent the fundamental response of the coordinated boiler-turbine control in the large-size supercritical plants under changes in the system frequency. The model is based on a survey of configurations of the plant control systems used in the major units commercially operated in Japan. The values of the parameters in the model are described through the comparisons with plant responses in a field test and with simulation results from a detailed model of the plant manufacturer. Sample simulation results from the model are presented for demonstrating the fundamental response of the once-through plants under change in system frequency.

Setting method of specific parameters of a superconducting fault current limiter considering the operation of power system protection-resistance-type and rectifier-type SFCLs in overhead transmission systems

We have developed an EMTP model of a resistance-type and a rectifier-type super-conducting fault current limiter (SFCL) and defined their parameters which a user specifies when he plans to introduce an SFCL into a power system. Using these models, we propose the setting method of these parameters so as not to affect the response of protective relays when SFCLs operate.

Experimental verification of fuzzy excitation control system for multi-machine power system

A fuzzy excitation control system (FECS), based on the fuzzy theorem and having the function of both AVR and PSS, was established to improve power system stability. This paper includes the results of experiments of the FECS on the AC/DC power system simulator of the CRIEPI. The FECS is compared with the conventional quick-response excitation system with optimized PSSs on a 4-machine long distance fish-bone type power system and various system configurations. The results show that the FECS increases the power transfer limit more than 20 (%) without any parameter tuning.

The setting method of the specific parameters of a superconducting fault current limiter installed at the bus-tie and response of protective relays at operation of the SFCL

We have investigated the setting method of specific parameters for a resistance-type and a rectifier-type superconducting fault current limiter (SFCL) installed in trunk transmission lines and the response of protective relays when SFCLs operate against a system fault. This paper describes the setting method of specific parameters of an SFCL installed at a bus-tie in a trunk substation, response of protective relays such as bus protection and line protection when the SFCL operates against a system fault and countermeasure of preventing tripping a sound line due to unwanted operation of some distance relays resulted by reverse current at operation of the SFCL.