Modeling Of Main Equipment And PCOV Simulation Of Arrester In ±1100kV UHVDC Converter Station

UHVDC power transmission has the advantages of long distance,large capacity and low loss.It is an effective way to realize the optimal allocation of energy resources,promote energy conservation and emission reduction policies and low-carbon economy.Changji-guquan±1100kV UHVDC power transmission project is an important measure to implement the national energy development strategy.It is of great significance in promoting the development of Xinjiang energy base,implementing the action plan for air pollution prevention and control,ensuring reliable power supply in eastern China,driving economic growth and leading technological innovation.With the improvement of voltage level,whether the insulation coordination design of converter station is reasonable or not will directly affect the economy and even the safety of the whole project.Therefore,it is of great engineering value to accurately calculate the PCOV level and influencing factors of each type of arrester in converter station.This paper focuses on the modeling of key main equipment of ±1100kV UHVDC converter station,the PCOV level of each type of arrester and its influencing factors.Firstly,the equivalent model of converter valve integrated wide band for PCOV calculation is established.An accurate model was established for each componet in the converter valve,considering the reverse recovery characteristics of thyristor and the nonlinearity of the saturation teactor,the intergrated wide-band equivalent model of converter valve was established after the integration and the equivalent parasitic capacitance,and the accuracy of the model was verified by comparing the impedance characteristics.Then,a modeling method using voltage transmission characteristics to built broadband model of the flat wave reactor and PLC filter of the ±1100kV UHVDC converter station.The accuracy of the model is verified by comparing the simulation results with the measured results.Combined with the AC and DC filter model and the converter transformer model considering leakage inductance,the equivalent system model of UHVDC converter station is built.Finally,based on the above model,the PCOV level of each type of arrester in the±1100kV UHVDC converter station and its influencing factors were analyzed.Compared with the low-frequency model,the validity of the model was verified.Compared with the results of formula method,it shows that the formula method has a certain safety margin.Through the simulation calculation,the effect to the calculation of PCOV are mainly in the damping valve damping resistorand damping capacitor,saturated reactor inductance,flat-wave reactor inductance and leakage inductance of the converter transformer,the influence of earth capacitance of converter valve,flat wave reactor and PLC filter on earth capacitance loss resistance is small,the influence of the rest of the parameters for PCOV calculation almost had no effect.