测量介质损耗角的高阶正弦拟合算法

在介质损耗角的数字化测量中 ,数据采样频率与电网频率间不同步的问题 ,以及电网中存在的高次谐波都会给介质损耗的测量带来误差。为了提高测量的准确度 ,论文研究了一种新的计算方法即高阶正弦拟合法。它利用高阶正弦模型 ,将电网频率视为未知参数 ,对采样数据进行最小二乘意义上的非线性拟合计算。并使用离散 Fourier变换 (DFT)方法求取迭代初值 ,以加快计算速度。研究表明 ,这种方法能够较好地解决上述问题 ,在噪声较强的情况下 ,准确度误差不超过 0 .0 0 0 3,而且计算速度快 ,完成一次计算的时间小于2 0 m s,满足介质损耗角在线监测的要求

Higher-order sine fitting algorithm for dielectric loss measurement

In the digital measurement of dielectric loss angle, the non synchronisation between the data sampling rate and the frequency of the power network as well as the network's various harmonic components can cause remarkable error. The accuracy can be improved with a new method, the higher order sine fitting algorithm. The method takes the power frequency as an unknown parameter and uses a nonlinear least squares fitting procedure based on a higher order model to process the sampling data. The discrete Fourier transform (DFT) method is also used to calculate the initial value and speed for the iterative computation. Studies show that the maximum measurement error is limited to 0.0003 even in noisy conditions, and it takes less than 20ms for one calculation. Therefore, the algorithm can be used for on line measurements of dielectric loss angle.