Study And Application On The Control Of Overvoltage Based On Controlled Switching Shunt Reactor

In a reactive power compensation system,we need to switch shunt capacitors according to demand on reactive power of power grid.The severe overvoltage,caused by conventional circuit breaker switching shunt capacitor,threatens safe operation of power grid.In this paper,based on research on the mechanism of overvoltage caused by switching shunt capacitors,we analyze several kinds of technology currently used to deal with switching shunt capacitor overvoltage and put forward a solution to tackle the overvoltage by using phase selection switching technology.There are already a lot of research on cause of switching shunt capacitor overvoltage,conclusions of which point to chopping current when switching shunt capacitors.Based on the already exiting research materials,we conduct experiments and make depth analysis on mechanism of overvoltage caused by switching shunt capacitors.Moreover,we propose control strategy for phase selection when switching shunt capacitor.Phase selection switching technology for circuit breaker is mainly applied in shunt capacitors,capacitor bank,transformers and long transmission line,aimed to switch at the best phase angle by controlling load in order to proactively eliminate or reduce the harmful transient process such as inrush current and overvoltage during the switching process.Phase selection switching technology has strict requirements regarding arc extinguishing chamber of circuit breaker and mechanical properties of circuit break operation instrument.Excessive deviation of the phase selection switching actuation time will make it impossible to switch load in default phase angle,which may reduce efficacy of switching.In this paper,we mainly analyze major factors that affect the deviation of circuit breaker actuation time and optimize circuit breaker's spring operating mechanism.Experiments prove that deviation of spring operating mechanism switching is within ±1ms,which satisfies the demand of phase selection circuit breaker.In this paper,based on theoretical research,we design and product device to tackle switching overvoltage of shunt capacitors.The device has been applied in a certain 220 kV electricity substation and field experiment results show the device successfully solve switching overvoltage problem of 35 k V shunt capacitors.