基于低延迟有限冲击响应滤波器的差动保护采样率转换算法

FIR Filter with Reduced Group Delay Based a Sampling Frequency Conversion Algorithm for Differential Protection

智能变电站中,电子式电流互感器(ECT)取代传统的电磁式电流互感器向差动保护装置提供电流信息。工程中,不同采样频率的ECT要求保护装置重采样,统一多路电流数据的采样频率。为解决此问题,本文提出了一种改进的差动保护采样率转换算法。该算法基于低延迟有限冲击响应滤波器原理,并以此为基础构造了基于约束最小二乘法设计的可用于信号抽取和插值环节级联的低通滤波器,实现了任意有理数倍频率转换的快速响应。仿真结果表明,较基于切比雪夫逼近原理的传统低通滤波器,采用改进算法的低通滤波器的数据输出响应速度提高了37.5%,峰值瞬时误差可控在3.683%以内,可以有效地减少数据传输延迟,提高差动保护动作的快速性。

In intelligent substations, current digital sampled data are presented by electronic current transducers（ECTs） to the differential protection device. When the ECTs＇ sampling rates are not all the same, it is compelled to convert different sampling rates to the same one. In this paper, the concept of low-delay finite impulse response filter is presented. Furthermore, a low-pass filter for signal decimation and interpolation link cascade is designed based on the constrained least squares method, which has realized the fast response of any rational multiple rate conversion. A model of 500kV transformer system model is built for simulation analysis. Compared with the traditional low-pass filter based on the Chebyshev approximation principle, output data response of the designed filter is faster by 37.5%.And peak instantaneous error is Controlled within 3.683%, which can effectively reduce the output delay and improve the operating speed of the differential protection.