适用于母线保护的电子互感器采样频率转换算法

A Sampling Frequency Conversion Algorithm of Electronic Transducer for Bus Protection

在电子式互感器应用环境中,母线保护连接不同采样频率的电子式电流互感器(ECT)时,需要将原始采样频率不同的采样数据转换为同一采样频率。文中提出了时域连续有限冲激响应滤波器的概念,并以此为基础构造了连续数字低通滤波器,从电子式互感器输出的离散采样数据恢复出连续信号,重新计算出任意时刻的采样值。用含丰富谐波信号的1000kV线路故障电流进行的计算分析表明,4kHz/2.4kHz采样频率转换,该算法在数据窗长6个采样间隔(延时为0.75ms)时,其峰值瞬时值误差均小于0.66%,精度和实时性能满足母线保护的要求。

when electronic transducer is used for different applications, it is often necessary to convert the sampling data of different sampling frequency to that with a same sampling frequency if the bus protection device is connected to electronic current transformers （ECTs） of different rated sampling frequency. This paper presents the concept of time-domain continuous finite impulse response （TCFIR） filter. A continuous digital low pass filter based on TCFIR is proposed to acquire continuous signal from electronic potential transformer （EPT）/ECT discrete sampling data and to calculate instantaneous value at any moment. Simulation using 1 000 kV transmission line fault current with strong harmonics shows that the proposed sampling frequency conversion from 4 kHz to 2.4 kHz is of only a peak error less than 0.66%. Meanwhile, the data window length is 6 points and the time delay is only 0.75 ms. The accuracy and real-time characteristics of the algorithm meet the requirement of bus protection.