CAJ | 학술논문

介绍了一种新的非线性、非平稳信号分析方法--局部均值分解(local mean decomposition，LMD)，分析了LMD用于扰动信号检测时的优缺点及原因。在此基础上，提出一种改进的局部均值分解(improved local mean decomposition，ILMD)电能质量扰动检测及时频分析新方法，该方法由LMD和希尔伯特变换(Hilbert Transform，HT)2部分组成。先用 LMD 提取信号的乘积函数(product function，PF)，由PF分量的调幅函数可得信号瞬时幅值；再对PF分量进行HT求取瞬时频率。ILMD方法可有效定位发生扰动的起止时刻，克服LMD在定位能力上的不足。与采用希尔伯特黄变换(Hilbert Huang transform，HHT)方法相比，ILMD具有瞬时幅值函数端部失真小、瞬时幅频曲线波动小和幅值与频率检测精度高等优点。仿真信号和500 kV变电站电容器组投切时的电压信号分析结果证明所提方法的可行性和有效性。
개소료일충신적비선성、비평은신호분석방법--국부균치분해(local mean decomposition，LMD)，분석료LMD용우우동신호검측시적우결점급원인。재차기출상，제출일충개진적국부균치분해(improved local mean decomposition，ILMD)전능질량우동검측급시빈분석신방법，해방법유LMD화희이백특변환(Hilbert Transform，HT)2부분조성。선용 LMD 제취신호적승적함수(product function，PF)，유PF분량적조폭함수가득신호순시폭치；재대PF분량진행HT구취순시빈솔。ILMD방법가유효정위발생우동적기지시각，극복LMD재정위능력상적불족。여채용희이백특황변환(Hilbert Huang transform，HHT)방법상비，ILMD구유순시폭치함수단부실진소、순시폭빈곡선파동소화폭치여빈솔검측정도고등우점。방진신호화500 kV변전참전용기조투절시적전압신호분석결과증명소제방법적가행성화유효성。
A new signal analysis method of non-linear, non-stationary-local mean decomposition (LMD) was introduced. The advantages and disadvantages of the application of LMD in the disturbance signal detection were analyzed. On this basis, the paper presented an improved local mean decomposition (ILMD) power quality disturbance detection and time-frequency analysis method. The method was composed of two parts:LMD and Hilbert transform. Firstly, to extract the product function (PF) of the signal based on LMD, and to obtain the instantaneous amplitude of the signal from the PF components of the amplitude modulation function. Then, to apply the Hilbert transform to obtain the instantaneous frequency of PF. The improved LMD method could effectively locate the beginning and ending time of the disturbances occurred and overcome the deficiencies of the LMD positioning capability. By using the method, the curves of the instantaneous amplitude had less distortion in wave head and that of the instantaneous frequency had shorter swings, and detection results for magnitude and frequency of disturbance signal had higher accuracy, compared with the HHT method. The simulation and experimental results of the switch voltage analysis of capacitor group from 500 kV transformer substation prove the feasibility and effectiveness of the proposed method.