Analysis Of Power Quality Transient Disturbance Signals Based On HF-HHT

Power quality is an important indicator of whether the power system is stable.With the rapid development of production capacity and technological level,people have become increasingly demanding on the power quality of power systems.How to improve the quality of power quality has become the majority of scholars worldwide.the direction of joint research.The current problems of power quality are mainly divided into steady-state and transient power quality problems.The steady-state power quality problem is relatively simple,and its research is more mature,but the transient power quality is difficult to detect due to the randomness and uncertainty of the disturbance.Therefore,the detection and location of transient power quality disturbances is the key to improving power quality.The research on transient power quality disturbance detection algorithm has important theoretical significance and practical value.Based on the current research on power quality detection algorithms at home and abroad,this paper selects 4 types of typical single disturbance signals and 3 types of compound disturbance signals.Through theoretical analysis and simulation experiments.the detection and location of transient disturbance signals are thoroughly studied the study.The following two studies have been carried out,and certain results have been achieved,and corresponding contributions have been made to the detection and location of transient disturbance signals in power systems.(1)Aiming at the mode mixing phenomenon of traditional EMD when decomposing transient disturbance signals,studying a new auxiliary signal injection method—the Hilbert Yellow Transform(HF-HHT).This method analyzes the transient disturbance signal by setting the frequency of the injected high-frequency signal.combined with HHT,and achieves the purpose of suppressing mode mixing.The key of HF-HHT algorithm is the selection of high-frequency harmonic injection frequency.Through the simulation signal analysis,the simulation results are combined with the theoretical analysis,and the principle of effective and universal frequency selection for transient disturbance signals is obtained.The measured power quality signals are analyzed,which verifies that HF-HHT is used in transient conditions with validity and universality in disturbance signal detection.(2)Aiming at the mode mixing phenomenon of EMD decomposition when HF-HHT detects composite disturbance signals containing harmonics/inter-harmonics.according to(1)high-frequency harmonic injection method,a new Harmonic detection method—Complementary ensemble empirical mode decomposition(HF-CEEMD)based on the high-frequency harmonic injection method.This method first injects high-frequency harmonic signals according to the frequency selection principle of transient disturbance signals to decompose high-frequency disturbance signals,then performs CEEMD decomposition on the remaining signals,and finally obtains the components of the composite disturbance signal by Hilbert transform.By analyzing the steady-state and time-varying harmonic/inter-harmonic composite disturbance signals,the validity and accuracy of HF-CEEMD-HT in the detection of composite disturbance signals containing harmonic/inter-harmonics are verified.