The Study Of High Voltage Shunt Capactitor Switching Over-voltage Suppression Method

Shunt capacitors as the main reactive power compensators, are widelyused in substation. Substation capacitor failures occur frequently, resulting ingreater economic losses to the power companies, to pose a great threat to thesafe operation of the power grid. The main cause of failure is shunt capacitorswitch restrike overvoltage. With the manufacturing process improved andmaking a series of tests to the vacuum breaker before running into the grid canreduce the probability of its restrike, but there is not the vacuum circuit breakerwithout restrike, which requires measures to reduce the overvoltage. In thispaper, following work has done on this issue.Firstly, vacuum circuit breakers require switching shunt capacitorsfrequently, theoretically analysis the shunt capacitor switching transients,including closed overvoltage and restrike overvoltage. Then use simplifiedmodel of the system and circuit equations to create various conditionsswitching overvoltage model by EMTDC/PSCAD simulation tool, verify theextent of damage.Secondly, combine simulation and experiment restrike overvoltage dateof shunt capacitor switch, mainly for two main parameters of the switchrecovery overvoltage and ground to pole overvoltage of capacitor, whichthrough statistical analysis, get its variation, which require manufacturingprocess to provide technical requirements to control the overvoltage andreduce the probability of restrike.Thirdly, in order to accelerate the speed of release residual pressure ofcapacitors, reduces the probability of restrike, design a discharge coil withcore of the amorphous alloy material, with magnetic properties analysis andparameter optimization. At the same time, propose a Composite Structure ofzero-switching devices and switching recovery overvoltage suppressors to curb closing surge and reduce the switching recovery overvoltage, reduce theprobability of shunt capacitor switch restrike overvoltage.Finally, through the test of switch recovery overvoltage suppressors,verify the suppressor can accelerate the release rate of residual pressure,reduce the switch recovery overvoltage, reduce the probability of shuntcapacitor switch restrike.