Study On The Transition Process Of Switching10KV Shunt Capacitor Banks

With the increasingly complexity of power grid structure and load changes, thefailure phenomena haven’t shown the closing operations or opening operations simply,but have shown some fault signatures, such as fast opening after closing operations. Andthis similar studies more complicated.Starting with physical faults, this paper have considered various factors andadapted combination of method of the basic circuit theory, simulations of ATP-EMTPand field tests to analysis the transition process of switching10kV shunt capacitors,especially fast opening after closing operations. The paper have presented innovativeconclusion, such as over-voltage caused by chopping current with switching inrushcurrent or high-frequency current of operation is the probable reason for the failure. Thefollowing work has been carried out.Described influence mechanism of asynchronous operation, arc reignition, groundcapacitance with study method of the basic circuit theory. A series of special operationsincluding operation of fast switching on-off, opening operation with change of busbar’sstray capacitance are proposed. The paper suggested that switching inrush current andhigh-frequency current of operation are new motivators of chopping current excepthigh-frequency current of arc reignition. The operation of fast switching on-off wasdefined firstly in this paper.The new simulation models of single-phase circuit and three-phases circuit wereestablished to analyze the impacts of main influence factors. The models of ATP-EMTPcompleted the simulation of special operations and phenomenon of chopping current.The calculated value of over-voltage caused by chopping current is very large. Theconclusions from above were proved by the comparison between the calculations ofsimulation and the theoretical result.The author invented a transient test system, including current and voltage sensorsand structure of signal acquisition system were improved specially. This paperintroduced key module of this system, including sensors, structure, system software, andso on.And some coordinated control systems of Vacuum breakers were designed.By field experiment, the peper got a series of data of overvoltage and overcurrentwith closing operations, opening operation with arc reignition.The actual experimentproved some conclusions including opening operation with change of busbar’s stray capacitance, high-frequency current of operation, and so on.In summary, the paper summarizes the following conclusions: The paper got thetransient characteristics of switching10kV shunt capacitors. The existence ofhigh-frequency current of operation and impacts of switching inrush current andhigh-frequency current of operation motivate the phenomenon of chopping current wereproved.This work is very meaningful for finding out the true reason of the actualfailures and and show a new way for overvoltage study.