Study And Application Of Optimal Setting Of Underfrequency Load Shedding In Power System

Underfrequency Load Shedding (UFLS), which is the third defensive line of power system, is one of effective methods to mitigate the frequency collapses. UFLS could relieve the continued dropping of frequency and avoid collapses or blackouts in case of the mass real power mismatches. In this thesis the optimal setting of ULFS scheme is studied and its application on the Jiangsu power grid is carried out. It comprises three parts:At first, the Time-Domain Dynamic Simulation (TDDS) method used for the optimal setting of UFLS scheme is introduced and compared with the traditional Single Generator Single Load Analysis (SGSLA) method. The SGSLA method is simple, easy to use and its less dependency of the models and parameters. However, the errors resulted from the SGSLA method are bigger and only the post-fault static frequency is obtained while the whole dynamic response process is ignored. The TDDS method can consider all models and parameters in power system and give the detailed dynamic frequency characteristic. However, it is more complicated and the computational demands are huge. Especially, it is dependent on the definition of the contingency set. The simulation results shown that the TDDS method is reasonable for optimal setting of the UFLS scheme while the SGSLA method is used as an complementary tool.Secondly, the sensitivities of the dynamic frequency characteristic with respect to the models and parameters of all equipments are studied. The models and parameters, which are suitable for the optimal setting of UFLS scheme in Jiangsu power grid in 2007, are obtained by using the TDDS method. The main parameters...