电容式电压互感器谐波测量方法研究

针对电容式电压互感器(capacitor voltage transformer,CVT)谐波测量数据准确度无法满足电能质量监测系统要求的问题,文中提出了一种具有谐波测量功能的CVT的实现方案,通过在常规CVT的分压器低压端串入电容C3,利用电容分压原理获得电网谐波测量信号。建立了该CVT的宽频等效电路模型,分析电容C3两端输出电压在谐波频段内的变化情况,明确了影响其频率特性的关键参数。并基于此方案研制了1台110 kV具有谐波测量功能的CVT样机,通过了型式试验并开展了谐波准确度试验,试验结果表明,在2~50次谐波信号测量范围内,该样机满足电能质量监测设备谐波要求,进一步验证了所提方案的有效性。

Study on Harmonic Measurement Method of Capacitor Voltage Transformer

In view of such issue that the accuracy of harmonic measurement data for capacitive voltage transformer(capacitor voltage transformer,CVT)has no way to meet the requirement of power quality mon?itoring system,a kind of implementation scheme of CVT with harmonic measurement function is proposed in this paper.The harmonic measurement signal of power grid is obtained by way of connecting capacitor C3 in series at the low voltage end of voltage divider of conventional CVT and by the use of voltage division principle.The broadband equivalent circuit model of the CVT is set up so to analyze the variation of output voltage on both sides of capacitor C3 in the harmonic frequency band and the key parameters affecting its frequency characteristic is defined.On the base of this proposal,1 sets of 110 kV CVT prototype with harmonic measurement is developed.The type test is passed and the harmonic accuracy test is performed.It is shown by the test result that the prototype in the range of 2th to 50th order harmonic signal measure?ment meets the harmonic requirements of power quality monitoring equipment and the effectiveness of the proposedschemeisverified further.