Research On The Over Voltage Of The Compensation Capacitor In Distribution Network Caused By Switching

Aiming at solving the problem of dash current and over voltage of parallel reactive compensation capacitor group in power system, this paper research on the phase control synchronous switch and the current-limiting reactor.With the simulation of a 110kV system, research uses phase control synchronous switch to diminish the over voltage and the current-limiting reactor to diminish the dash current. Two groups of result shows that when used alone, the reactor and the phase control switch can effectively protect the capacitor from the dash current and the overvoltage. Further, to prove that they can together protect the capacitor, this paper simulate with the power system involves both of the protection tools. Simulation result again demonstrates that dash current and the over voltage would be limited by the corporation of the phase control synchronous switch and the current-limiting reactor.On the basis of the results obtained from the 110kV system simulation, the maximum allowable time error is obtained. If the time error is more than this, the synchronous closing device will not be effective in limiting the overvoltage and inrush current when closing.In order to make sure the generality of the study, we continue study the switching overvoltage and inrush current using 220kV system. The simulation results show that the error value for this system can effectively limit the switching overvoltage. Based on this system, the paper makes research on the closing shunt resistance.In power system, metal oxide arrester (MOA) is widely used in the over-voltage protection for the parallel reactive compensation capacitor group. Three-star wiring and four-star wiring is used widely in protection. These ways of wiring can effectively protect the capacitor group but they need more arresters. The load rate is high making the arrester easy to break. This paper demonstrates the feasibility of the new connection method of the neutral point L connection on. This paper uses ATP/EMTP to build the 220kV power system with the capacitor, simulating the restrike that usually appears in the power system. It compares the protection result, load rate and power to bear in 3 kinds of connections. The simulation result shows that L connection can restrict one phase restrike and restrike when grounding. And the plate passes the power exam with the low load rate in normal state making the arrester slow in breaking. According to the result,it is demonstrated that L connection can be used as over voltage protection effectively. With the result from simulation, the paper lists out the system in which each kind of connection mode should be used.