电压不平衡度的准同步采样快速测量方法

采用IEC 61000-4-27所推荐方法进行电压不平衡度测量时,复杂的开方运算是不可避免的。提出一种电压不平衡度的准同步采样快速测量方法,该方法首先采用准同步采样算法计算三相电压相量(幅值和初相角),然后利用几何原理将开方运算转化为三角函数计算,并最终利用代数多项式简化三角函数式,实现电压不平衡度的快速、准确测量。与IEC 61000-4-27所推荐方法相比,提出的电压不平衡度的准同步采样快速测量方法避免了傅里叶变换和复杂的开方运算,减少了运算量。仿真和实际测量结果表明,电压不平衡度的准同步采样快速测量方法与IEC 61000-4-27所推荐方法具有相同的测量准确度,为电压不平衡度的快速测量提供新的思路。

Fast measurement method for voltage unbalance factor based onquasi synchronous sampling algorithm

The complex square root operation is inevitable during the measurement of the voltage unbalance factor using the method recommended in IEC61000 4 27. This paper proposes a fast measurement method for the voltage unbalance factor based on the quasi synchronous sampling algorithm, which calculates the voltage phasors, i.e., the magnitudes and initial phase angles, in three phase system with the quasi synchronous sampling algorithm firstly; then transforms the complex square root operation to simple trigonometric function calculation based on the geometric principle; and at last, the trigonometric function equations are approximated by the algebraic polynomial operation; the fast and accurate measurement of voltage unbalance factor is achieved. Compared with the method recommended in IEC61000 4 27, the proposed method avoids FFT and complex square root operation and reduces the computation burden sufficiently. The simulation and actual measurement results show that the proposed method can achieve the same level of precision as the method recommended in IEC61000 4 27, and provides a new idea for fast voltage unbalance factor calculation.