一种基于混合数字滤波器的过零检测技术

传统过零检测技术主要存在不能消除谐波、电压切痕，脉冲等噪音造成的虚假过零现象，给系统引入迟
延、相移，并对电力系统频率变化敏感等弱点。根据预测FIR 滤波理论，中值滤波技术，提出了在数字信号处
理器（DSP）上实现基于混合数字滤波器的过零检测方法，能够消除虚假过零，补偿延迟和相移，对电力系统频
率±0.2Hz 变化鲁棒性强，并提出了确定预测FIR 滤波器阶数的一般方法。最后仿真实验证明了方法的先进性。
关键词：过零检测混合数字滤波 预测 FIR 滤波中值滤波 补偿延时 鲁棒性
中图分类号：TM935 文献标识码：A
Zero-Crossing Detecting Technique Based on Hybrid Digital Filter
PENG GUO-FU， ZHOU HONG，DAN WEI, XIA MING-YE, YU LI
(Automation Department，College of Dynamics and Machinery, Wuhan University, Wuhan, Hubei, 430072)
Abstract: Traditional zero-crossing methods have following weak points: can not diminish false zero-crossing caused by
harmonics, notch etc., phase shift and delay added in, sensitive to variation of power system frequency. A method,
implemented on digital signal processor (DSP), based on hybrid digital filter that consists of median filter and predictive
finite impulse response (FIR) filter, for zero-crossing detection is introduced, which can overcome weak points of
traditional zero-crossing detecting techniques. The method for selecting the order of predictive FIR filter is advanced.
Simulation result show that this method can suppress disturbances caused by background noise, impulse, harmonics,
notch effectively, diminish false zero-crossing, compensate delay, and judge zero-cross precisely, with high robustness.
Key words: zero-crossing detecting; hybrid digital filtering; predictive FIR filter; median filter; compensate delay;
robustness