Research On Reliability Of Power System Protection

Protection devices is an important measure to ensure the normal operation of the power grid,when the system fails,the protection device can promptly cut out fault,it is essential to power system devices.In recent years,power system of the main protection correct action rate is not high,In order to more effectively guarantee the reliability of protection devices,it has a very important theoretical and practical value to pre-simulation and research for the main power system protection configuration.Transformers and transmission lines as the two main power system protection configuration,bears an important role in transform voltage?exchange of power and transmission of electrical energy,which directly affect the whole system safe and stable operation of power.Three-phase transformers and transmission lines for the study,a detailed description of the transformer main protection and backup protection of fundamental principles,Phase Current Protection Principle,distance protection and longitudinal current differential protection principles of transmission Line,it describes the mechanism of excitation transformer inrush current,it also describes the lockout criterion and current imbalance in the differential circuit,meanwhile it briefly introducts two common reliability analysis,fault tree analysis and markov state space analysis.Use of MATLAB/Simulink in the SPS module,built the external fault model and the internal fault model of the transformer,built the longitudinal differential simulation model of transmission lines.When setting up longitudinal current differential protection model of transmission line,which contains a detailed description of the start element,algorithm section and differential relay module.Using simulation models,we do a lot of simulation and research for a variety of failures lot of transformers and transmission line,effective simulation of transformer no-load operation state,short circuit state and interturn short circuit state,meanwhile,the transmission line protection devices have also been effective simulation.The simulation results consistent with the theoretical analysis.Verifing the correctness and effectiveness of fault simulation model.