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A fuzzy logic rule-based damping controller for STATCOM has been proposed in this paper. The proposed controller has two control loops. One is voltage control, with traditional PI control; the other is damping control, with the proposed rule-based controller. The input signal to the voltage control loop is the terminal voltage, and the input signal to the damping control loop is the generator speed, which can calculated from local variables. The effectiveness of the proposed controller was demonstrated in a single machine infinite bus system with Siemens NETOMAC. Further study will focus on the control strategy of STATCOM on multi-machine system.

For the purpose of Static Synchronous Compensator (STATCOM) control, an improved PI control method is developed based on fuzzy set and auto-tuning techniques. A fuzzy rule base is used to adapt the parameter varying characteristics of the power system and various operation points of STATCOM. The relay-based auto-tuning scheme is used to find out the appropriate PI gains with respect to a set of operating points, consequently to facilitate the establishment of the desired fuzzy rule base. To test this control strategy, digital simulation on MATLAB as well as field experiments on a real ±10kvar STATCOM developed in Tsinghua University has been done. Both the results show that the proposed control strategy is much more effective than fixed parameter PI control.

This paper is a summary of our research work for seven years in applying the theory of optimal control to the excitation system of a generator (Optimal Excitation Controller, OEC). It analyzes problems of OEC by means of digital simulating and physical modelling. It also points out the merits of OEC and what research works should be done in the future.