一種基于混合數(shù)字濾波器的過零檢測技術(shù)

傳統(tǒng)過零檢測技術(shù)主要存在不能消除諧波、電壓切痕，脈沖等噪音造成的虛假過零現(xiàn)象，給系統(tǒng)引入遲
延、相移，并對電力系統(tǒng)頻率變化敏感等弱點(diǎn)。根據(jù)預(yù)測FIR 濾波理論，中值濾波技術(shù)，提出了在數(shù)字信號處
理器（DSP）上實(shí)現(xiàn)基于混合數(shù)字濾波器的過零檢測方法，能夠消除虛假過零，補(bǔ)償延遲和相移，對電力系統(tǒng)頻
率±0.2Hz 變化魯棒性強(qiáng)，并提出了確定預(yù)測FIR 濾波器階數(shù)的一般方法。最后仿真實(shí)驗(yàn)證明了方法的先進(jìn)性。
關(guān)鍵詞：過零檢測混合數(shù)字濾波 預(yù)測 FIR 濾波中值濾波 補(bǔ)償延時 魯棒性
中圖分類號：TM935 文獻(xiàn)標(biāo)識碼：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