Dynamic breaking resistor based control of generator for improved dynamics

Abstract

This paper discusses modeling and tuning of a hydro turbine governor and a design of dynamic braking resistor to improve transient stability of a generator. In traditional power system, the generator can regain stability after disturbance alone with the PID governor. However over speed limit has to be focused more as its variation is defined by relevant authority. Generally those limits are difficult to achieve in practice for a sensible load disturbance. In the paper, a dynamic breaker resistor is proposed together with a tuned-existing governor to improve the stability margin of a hydro generator. Here root locus and Routh's stability criterion are used to obtain PID parameters of the governor. The dynamic breaker resistor was designed to operate with reduced harmonic injection during its operation. Finally the simulation results confirmed that the proposed technique prevents the speed going beyond its limit, when load rejection takes place due to fault in the power system. Therefore the total or partial system failures can be avoided.