UHV Capacitance Voltage Transformer Suitable for Series Compensation Platform

Using ultra high voltage disconnector to switch the fixed series compensation capacitors platform may induce fast transient phenomenon and repetitive strikings of disconnector, the high amplitude and steepness current may damage adjacent CVT. This paper build the simulation calculation model by ATP-draw of the resonance circuit consist of capacitance of series compensation platform to earth, inductance of transmission lines and CVT, the simulation results show that decreasing the rated capacitance of CVT can reduce the amplitude of transient impulse current effectively. This paper analyses the rated capacitance effecting on the error characteristics of UHV CVT, determines to decreasing the rated capacitance of UHV CVT from 5000pF to 2000pF, which will have no effects to the error performance of CVT needed by engineering, and develops the prototype of UHV CVT with rated capacitance of 2000pF. At last, this paper builds a transient impulse current measuring system, and measures the transient impulse current through the CVT with main capacitance of 2000pF and the CVT with main capacitance of 5000pF under the lightning impulse overvoltage, the measuring results indicate that the amplitude of transient impulse current that through the 2000pF CVT is 1.46kA, the amplitude of transient impulse current that through the 5000pF CVT is 2.66kA. The study result indicates that the UHV CVT with small rated capacitance we developed can decrease the transient impulse current amplitude, the reliability under the transient state will be improved.