Study On Configuration Of Relay Protection In A Small Thermal Power Plant

One of the fundamental and technical works in power system is the setting and configuration of power plant relay protection. Because there are all kinds of equipments in a power plant, the setting of the object which will be protected is complex, and it requires high automation, there usually exist difficulties for the professionals to do the relay protection properly. This paper does some research on the setting and configuration of secondary relay protection for a small power system combining with the project of the Stainless Steel Company called combined heat and power generation. The capability of the relay protection is studied and judged by tracking the feature of electrical variables during the course of fault happening to make sure that the setting satisfies the basic requirement of reliability, selectivity, speed and sensitivity for power system relay protection. The main results consist of three parts:Firstly, the protection theory and method of the setting and calculation for the main equipments of the power plant are studied, including the generator set, the transformer, the generator transformer set and the motor and a theoretical model of configuration of power system relay protection for the generator set is built up. Then the setting and configuration of power system relay protection for the generator set is worked over by calculating and analyzing the short circuit current of a small thermal power plant and some examples of the main protection and reserve protection of the generator for the small thermal power plant are analyzed;Secondly, the configuration of the small generator set relay protection is analyzed and designed, including ratio differential protection, scalar product differential protection, compound voltage lockout overcurrent protection, and loss-of-excitation protection. Compared with the setting of the generator differential protection, the setting models of the small power plant relay protection for the main equipments including the generator transformer set, the transformer and the motor are set up. Besides, by combining the setting theory with the microcomputer integrated protection, the application of the Siemens 7UM62 integrated protection device in the setting of the generator protection is studied, and an optimized model which is based on the technology of SEL microcomputer integrated protection in the main protection of transformer and a thermal overload model of the motor which is based on the technology of AREVA microcomputer integrated protection are built up.Finally, chapter 5 talks about the technical problems of electrical breakdown and voltage sags in detail which affect the long term stable operation of the power system. Then the theory of quick switch of the power and configuration of relay protection is closely combined and a analysis of coordination is also done between the parameter of the power with quick switch and the theory of relay protection, which solve the problems of the electrical breakdown and voltage sags effectively;This paper does some research on the configuration of the small power plant relay protection and the problems of the electrical breakdown and voltage sags combining with the project of the Stainless Steel Company called heat and power generation and establishes a control model of the secondary protection for the small thermal power plant, which make great contributions to the synthetic application of the configuration of relay protection and microcomputer protection in the thermal power plant of the same kind.