Power Plant AC Emergency Power Supply Optimal Design

At present, the capacity of generator and transformer of power plant increases ceaselessly, electric power system is moving in the "big unit,ultra high voltage, large power grid" direction, power plant appears to be more important in power system. Power plant costs expensively, the fault that occurs in power plant can affect the reliable operation of the power systemseriously and lead to great losses. Power plant emergency power supply supplies the accident emergency load in accident, the optimal design of emergency power supply appears to be more important to enhance the reliability of the power system and decrease the accident losses.Through the comparison of the two mode of connection of AC emergency power supply and the analysis of the reliability, and the power grid company charges the unit capacity cost, the AC emergency power supply of 300MW and above power unit being in operation, being installed and being designed almost adopts the special diesel generator set. Therefore, the emergency power supply discussed in this thesis refers to special diesel generators as the connection mode of emergency power supply.According to the analysis of the operation characteristics of the 300MW heat supply unit and auxiliary, propose the economical and reasonable kinds of AC emergency power supply, choice of diesel generator set and wiring plan, but except the AC uninterrupted power supply system.According to the analysis of AC emergency power load, and the demand of the shutdown process, the invest time of the AC emergency power load is disperse, and the operation period of the AC emergency power load is different, therefore, the load statistics should be divided in different period. This thesis uses the heavy load such as AC oil pump, battery float charging device, jacking oil pump, jigger invest time as starting time segment to gather AC emergency load statistics.Diesel generator set is composed of a generator, alternator, control and switching device. Diesel generator used for emergency power supply is different from the normal diesel generator, this thesis will discuss the choice of type, startup characteristics, power, performance, loading capacity of diesel generator used for emergency power supply.Taking Hebei Datang international Zhangjiakou thermal power plant and Tianjin Beitang thermal power plant as an example, analyze the wiring plan of the AC emergency power supply, the calculation of emergency PC segment and emergency MCC load capacity, the choice and check of the diesel generator capacity of the two thermal power plants, then compare the two wiring plans of the AC emergency power supply, put forward the wiring plan suitable for new power plant.