一种改进的瞬时导数法计算阻抗

Improved Instantaneous Derivative Method for Computing Impedance

阻抗的精确测量有利于提高继电器动作速度和准确性。导数法是微机保护中最常用的一种算法之一。传统的导数法计算阻抗精度对滤波器滤高频能力和采样频率有较高的要求。无误差修正思想虽能克服该不足,然而实时性较差。为了提高导数法计算阻抗的精度和实时性,提出了一种改进的瞬时导数法计算阻抗方法。理论推理和仿真结果都证明了该方法所需的数据窗少,有利于降低运算精度对数字滤波器滤高频能力和采样频率的高度依赖,可以实时的计算阻抗。

Accurate impedance measurement can improve the speed and precision of relay performance. Derivative method is one of the widely used computer protection algorithms. The traditional derivative method for computing impedance is strongly dependent on the sampling and the ability of high wavelet. Error amending can overcome the two shortcomings, but is worse in real-time performance. An improved instantaneous derivative method of computing impedance is suggested to improve the precisin and real-time performance. The extent of dependence on the sampling and the ability of high wavelet can be lowered. Mathematical reasoning progress and simulation results show that the method has better real-time performance and less length of digital filter window.