Study On Overvoltage And Insulation Coordination Of Series Compensator

Using series compensation in large capacity AC transmission system can increase theline transport capacity and improve the balance of the reactive power. It can also greatlyimprove the security and stability of the power system. But series compensation system willbe affected by system fault. The overvoltage causing by fault can damage equipment inseries compensation, especially capacitor. Therefore, research on series compensationsystem overvoltage protection has important significance.This paper in-depth describes the overvoltage protection and control strategy based on500kV Baise series compensation. The MOV-parallel gap protection is selected as theprimary protection of Baise series compensation. The MOV is the primary protection of thecapacitor to limit capacitor overvoltage. And the spark gap is the back-up protection of theMOV and of the capacitor; Damping circuit can rapid decay the discharge current toprevent equipment damage in the discharge process. Based on this protection strategy, thispaper studies the MOV protection level and the influence factors of its energy demand. Andput forward a MOV&damping circuit parameter design method in series compensationbased on regional fault and external fault simulation.As the main protection of series compensation, MOV will be impact by the faultcurrent and absorb a great deal of energy. Considering with system operation mode, faulttype, fault location, fault moment, fault duration, overvoltage protection level, overvoltageprotection&control strategy and MOV parameters, we get the suitable MOV parametersfor Baise station.Damping circuit parameter design is another difficulty in series voltage protection.Taken into account of the damping circuit capacitor, MOV, spark gap, as well asrestrictions on its bypass switch, we get the just good damping circuit parameters to meetthe requirements of the decay rate based on the simulation analysis, while the parameters avoid the system background harmonic wave resonance point, to prevent the occurrence ofresonance.