The Model Study Of An Over Speed Control System In Power System Middle-long Term Stability Simulations

The basic method of improving the stability of power system is decreasing thedifference between the power of turbine and the active power of the generator whenthere is short circuit. There are two methods, one is diminishing the power of turbine,the other is increasing the active power of the generator. The utility of the over speedcontrol system is diminishing the power of turbine. There are four modules of theover speed control system: closing the middle pressure gate quickly, forecast of thedecreasing of the load, 103% of the over speed control, 110% of the over speedcontrol. EUROSTAG uses interface variables to build new models. The model of overspeed control system uses CM, CV, IV of the interface variables of the standardmodels of EUROSTAG.. The over speed control system is composed by six partsrepresenting the function of the four modules. This article uses testing methods to testthe six models, proving that they are right. The chapter 4 of this article analyzing the action conditions of the four modulesof the over speed control system. There are tow reasons that the 110% over speedcontrol will be active: one is that the 103% over speed control will not be active whenthe short circuit occurs, the other is the relay time of the closing of the middle andhigh pressure gate is too long. The chapter 5 analyzing the effect of over speed control system to the powersystem stability, especially to the stability to the rotor angel. In some case, the powersystem will keep stable when it has over speed control, otherwise it can not.