Research On Vacuum Switches' Switching Overvoltages And Its Protection

Vacuum switches have their own features on construction and interrupting characteristics, and can bring different overvoltages compared with other switches operation. The production of overvoltages can be systemic analysis, and effectual repressive measures can be discussed. It's very significance for vacuum switch's promotion and operation security.System failure or switch operation caused transitional process overvoltages, which also called switching overvoltages. Because of operation, transient process can make the energy storage components in the power system working state changed. Magnetic field energy that stored in inductance components can transformed into electric field energy stored in capacitor element. Electric filed energy that stored in capacitor element also can transient into magnetic field energy stored in inductance components a moment in time. In this case, transitional process overvoltages that several times of supply voltage can be generated. To ensure the power system safe, reliable and economy operation, it requires that temporary overvoltages can be monitor and analysis research.In this paper, the data of overvoltages that were measured online in power system are regarded as research object. The data of overvoltages can be reverted to real-time waveform. Parameters of overvoltages can be obtained. So overvoltages'analysis and protection research can be in progress. At first, theoretical analyses are discussed about various VCB switching overvoltages'generating process. This can provide theoretical basis for overvoltages'analysis and protection research. After that, the data of overvoltages can be statistics and analysis, which were measured online at the substation of a corporation in PanZhihua. The parameter, such as amplitude, duration, and gradient and so on, can be obtained through the real-time overvoltages'waveforms. Mathematical statistics method can be used to statistical analysis the three correspondingly switching overvoltages. A multiple of overvoltages amplitude probability density is obtained. An advice is put forward about substation's insulation coordination. It can be avoided that the insulation level of electrical equipment is weakening gradually due to accumulation effect of overvoltages. These have a certain engineering significance. At last, ATPDraw soft can be used to simulate three types switching overvoltages and protection research. Controlled resistance is advised to simulate the characteristic of vacuum arc. The switch with closing resistor, RC equipment and MOA are used to limit switching overvoltages. Certain effect is obtained. Those that generating process of vacuum switches'switching overvoltages have been discussed, waveform analysis and protection measures have been researched, can offer important directive significance for overvoltages protection.