串联阻尼元件的特高压小电容量电容式电压互感器的设计及性能验证

Design and Performance Verification of Small Capacitance UHV CVT Series with Damping Elements

为降低隔离开关切合串补平台时通过邻近特高压电容式电压互感器（CVT）冲击电流的幅值,利用ATP-draw建立了特高压串补平台侧隔离开关操作的等效模型,经计算得到,降低CVT额定电容量和在CVT顶端串联电阻或电感元件可以有效降低通过其本体的冲击电流幅值。研制了额定电容量为2000pF的小电容量特高压CVT样机,建立了其宽频等效电路模型,选取5组具有不同参数的串联阻尼元件,通过仿真计算与实测的比较,验证了仿真的合理性,并确定了阻尼元件参数。搭建了雷电冲击电压下特高压CVT冲击电流测量系统,分别测量了雷电冲击下通过带有阻尼元件的额定电容量为2000pF特高压CVT及工程用额定电容量为5000pF的特高压CVT的冲击电流。测量结果表明：在特高压CVT高压端施加幅值为1550kV,波前/全波时间为5.5/67μs的雷电冲击过电压时,通过前者的冲击电流幅值为0.82kA,通过后者的冲击电流幅值为2.66kA。该研究结果表明,采用串联阻尼元件的小电容量特高压CVT,可有效降低通过其本体的冲击电流幅值,提高特高压串补隔离开关操作时邻近特高压CVT的可靠性。

In order to reduce the transient impulse current amplitude through capacitor voltage transformer（CVT） while switching fixed series capacitors platform, we established an equivalent model using a disconnector to switch fixed series capacitors platform by ATP-draw. The simulation results show that decreasing the rated capacitance of CVT and seriesing inductance or resistance in CVT can reduce the amplitude of transient impulse current effectively. First, we developed the UHV CVT with a rated capacitance of 2 000 pF, and built the broadband equivalent circuit of it. Then, we chose five sets of damping elements with different parameters, compared with the calculation results and measuring results, verified the rationality of calculation model, and confirmed the parameters of damping elements. At last, we set up an impulse current testing system under lightning impulse voltage, and measured the transient impulse current through the UHV CVT with a rated capacitance of 2 000 p F and damping device integrated developed in this paper and the UHV CVT with a rated capacitance of 5 000 pF used in UHV engineering under the same lightning impulse overvoltage. The measurement results indicate that applying the lightning impulse overvoltage with a amplitue of 1 550 kV and wave-head time/full wave time is 5.5/67 μs on UHV CVT, the amplitude of transient impulse current through the CVT developed in this paper is 0.82 kA, and the amplitude of transient impulse current through the CVT used in UHV engineering is 2.66 kA. The study results indicate that the small rated capacitance UHV CVT series with damping device developed in this paper can decrease the amplitude of transient impulse current effectively. Its reliability under the transient state will be improved.