Analysis Of Relay Protection For Generator Transformer Unit And Research On Loss Of Excitation Protection

In the development of the whole country,electric power occupies an important position,the safe and stable operation of the power system affects all aspects of the people's livelihood.As the first line of defense in the three major lines of power system,the relay protection provides an important guarantee for the safe and stable operation of the power system.As an important part of the power system,the power plan developed rapidly in China,the impact to the entire power system is growing also,so the rational allocation and calculation of generator transformer unit of relay protection is essential.Although the relevant guidelines,provisions for the generator transformer unit relay protection provides the basis for the analysis,but the guidelines are not comprehensive enough,rich,but the guidelines,provisions are not comprehensive enough,rich,and some places even wrong,so we can not just rely on the guidelines,but also need to combine the actual situation of the power plant,in-depth study and analysis of the protection configuration and setting calculation.Combined with the project experience of the author,this paper first elaborated the purpose of the relay unit relay protection,significance and research status at home and abroad;Then summed up the general steps,basic principles of setting calculation and configured protections for the generator transformer unit relay protection;Then,the principle of complete vertical differential protection of generators,negative sequence overload protection of generator and low voltage branch backup protection is analyzed,the examples of setting calculation are given,the problems needing attention are put forward and the solutions are given.The protection scheme,setting value,especially the solution to the problem of all examples in this paper have been examined,and the power plant has been operated and provided a good reference for the subsequent setting.This paper focuses on the research about loss of excitation protection of generator,in the case of loss of excitation protection using the asynchronous circle criterion,innovatively proposed the calibration method of sensitivity and the action of the loss of excitation protection is correct or not when the generator is running in phase,and the concrete case analysis is given;The low-voltage criterion of variable-flux protection rotor is further studied;The conversion derivation process of the loss-free protection impedance circle from the R-jX coordinate plane to the P-jQ coordinate plane is improved,which provides a basis for the coordination under the same coordinate plane between the loss of excitation protection and automatic excitation regulator,and summarizes the principles of cooperation between them.