Study On Correlative Technique For Grid-related Protection Of Generation Side

With the development of the electric power system, especially the application of the new transmission technology such like HVDC and FACTS as well as the large-scale grid connection of the new energy farms, the power grid becomes huger and its operation environment is more and more complicated, which makes the coordination between generation side and grid side the key point for the stability and security of the power system. However, as the technical progress and operational independence of generation side, it's hard to get the coordinated operation between generation side and grid side, which reflects the significance of the grid-related protection. To satisfy the technical requirements of the stability and security of the power system, this paper explores and expounds the connotation of the grid-related protection of the generation side, and then makes further research of out-of step protection and excitation loss protection.Firstly, expound the present research status and the limits of the current grid-related protection for generator, and then put forward the concepts of grid-related protection of the generation side with corresponding protection construction scheme. Analyses the connotation and the emphasis of the current study of the grid-related protection and point out its limits under the new situation of the power system. With the the features of the power system, propose the definition of the grid-related protection of generation side, and then come up with the hierarchical grid-related protection scheme based on multi-information acquisition to meet the technical requirements of grid-related protection of generation side, which effectively makes use of the information of generator states, power plant and the grid side.Secondly, study the influence of generator out-of-step patterns under the operation mode that multi-generating units with common bus to the out-of-step protection and figure out the limits of the current out-of-step protection under this operation mode with putting forward a solution scheme. Research the relationship between the equivalent impedance outside the generating unit and the out-of-step mode and study the connection of impedance locus with the equivalent impedance outside the generating unit, and then figure out the limits of the current out-of-step protection. To break through the limits within the current protection mode, propose a solution scheme, which is called three-stage out-of-step protection. With differentiation slip pole times setting and generating unit tripping strategy, this scheme ensures the generator provides sufficient supply to the grid side while in oscillation periods.Finally, analyze the factors that limit the degreed of leading phase operation of the generator and study the coordination between the minimum excitation limit and excitation loss protection. Research the shortage of the excitation loss protection under the situation that the generator is in leading phase operation or heavy loading, and then propose an improvement project with great reliability.