Chihiro Fukui

Principle and characteristics of a fault current limiter with series compensation

A power system fault current limiter with series compensation, which is composed of a compensation capacitor and a limiting reactor in series, is proposed. A solid-state switch connected in parallel with the capacitor controls either the ordinal series compensation or fault current limitation. A feasibility study of the current limiter by simulation analysis is presented and the effectiveness of the current limiter is evaluated from the viewpoints of transient stability improvement and device capacity. The current limiter is a useful protection device for large, high power transmission systems.

Development of restoration guidance system for control centres

Abstract This paper presents a newly developed intelligent restoration guidance system for control centres. This system distinguishes the fault section with model-based reasoning and plans the restoration operation by fuzzy inference. We have developed the expert system to prevent human errors, improve restoration time, standardize restoration procedures, and accumulate and inherit the expertise of operators. This guidance system will be installed as additional functions to the supervisory control and data acquisition system for a control centre that handles approximately 16 unattended substations.

Fault current limiting system for 500‐kV power systems

Recently, expansion in the scale of power systems and development of localized power sources are leading to an increase in fault current of 500-kV systems. In the future, it is quite likely that the fault current at the interconnection of such power systems may exceed the rated short-time current of existing electric power facilities. As one of the solutions of this problem, a thyristor-controlled series-resonant-type fault current limiter (FCL) is proposed to restrain the fault current. This paper deals with the FCL system configuration, the placement method of the FCL in power systems, the outline of the FCLs specification, and the operation method of the protective relay in the multimachine system. Finally, the effectiveness of the FCL is evaluated from the viewpoints of limiting the fault current by simulation analysis. The FCL is shown to be a useful protection device for large, high-capacity power systems.

A Game-theoretic Stochastic Agents Model for Enterprise Risk Management

A model of business scenario simulation is developed by applying game theory to the stochastic agents described by the Langevin equations for enterprise risk management (ERM). Business scenarios of computer-related industries are simulated using the developed model, and are compared with real market data. Economic capital was calculated based on the business scenario, as the most basic requisite of ERM.

Feasibility study of a feed-forwarding voltage-reactive power control method based on linear programming for a central control facility

Voltage–reactive power control (VVC) on power systems becomes difficult when a load increases or decreases rapidly, especially in the morning and at noon. This is caused mainly by two problems. One is delayed operation and the other is noncooperative operation of facilities. To solve these problems, an advanced method and algorithms for a centralized feed-forwarding control system are presented. They are based on two main steps: forecasting the power system state for several minutes and dispatching reactive power sources optimally based on stepwise linear programming. The proposed method is evaluated and tested for data of a large-scale power system. The results show that the proposed method keeps the voltage constraints well and reduces redundant operation of facilities.