三相电压不对称时谐波和无功电流的准确检测

Accurate detection for harmonics and reactive currents in the case of unsymmetrical three phase voltages

讨论了三相电网电压不对称情况下对非线性负荷合理的补偿方案，对基于“瞬时无功功率理论”的谐波检测方法所存在的不足进行了分析，继而提出了一种新的基波无功和高次谐波电流检测方法。由于采用了双闭环方式，使得在三相电压不对称并含有高次谐波的情况下，也可以对基波无功和高次谐波电流进行准确的检测，检测精度受元件参数变化影响小，具有较强的适应性。另外，按照功率平衡的原理，对补偿电流进行了修正。仿真分析对该方法的正确性和可行性进行了证明。

The proper compensation method for nonlinear loads in the case of unsymmetrical threephase voltages is discussed. Limitations of the detecting method based on the theory of instantaneous reactive power for harmonics and reactive currents are analyzed, then a novel detecting method is presented. Due to the use of double close loop control in this method, the fundamental reactive current and high frequency harmonics also can be detected accurately when three phase voltages are unsymmetrical. The changes of circuit parameters only have small influence on the accuracy of the detecting system. According to the power equation, the compensating current is modified. Simulations are carried out to verify the feasibility and correctness of this method.