Research On Control Strategy Of Prevention Power Oscillation Of Hydropower Unit And Thermal Power Unit In Yunnan

Power oscillation of prime motor can cause the oscillation of the entire powergrid, so ensure the stable output of the unit is very important to the safe and stableoperation of the power system. Thermal power and hydropower are the two mostimportant forms of electricity generation, so the power control of hydropower unitand thermal power unit must meet high accuracy requirements.The operating condition of hydropower unit and thermal power unit oftenchange, the main steam pressure of thermal power unit, the delivery head and guidevane opening of hydroturbine would change according to the operating condition,lead to the change of the controlled object of unit power control loop. The Parametersof traditional PID controller are fixed, so traditional PID controller cannot ensurebetter control quality to the time-varying, nonlinear power control system. The outputof the unit may overshoot or even fluctuate, threaten the normal operation of the grid.The fuzzy self-tuning PID controller can adjust its output according to error anderror change of the system, to adapt to the change of operating condition, ensurebetter control quality of the time-varying system. But it is difficult to confirm thequantization factor and scale factor of the fuzzy self-tuning PID controller, it requiresa lot of repeated trial and error. This paper uses particle swarm optimization to get thequantization factor and scaling factor, off-line determine the optimal parameters. Themethod avoids a large number of experiments, saving much time and effort. Thesimulation results show that the fuzzy self-tuning PID controller which quantizationfactor and scaling factor achieved by particle swarm optimization can ensure bettercontrol quality. It can ensure better control accuracy to the power control of the uniteven when the operating condition of hydropower unit or thermal power unit change,it can ensure the stable output of the unit.As the fuzzy self-tuning PID is complex, its practical application is difficult, thispaper presents a control plan that add an adaptive factor at the output of thecontroller，and use inverse function to revise the non-linear relation between theoutput and the guide vane opening of hydropower. These plans are more suitable forpractical application. The PID controller can adjust its output according to thechanges of the controlled object, ensure better control quality of the unit powercontrol.