A Power Quality Detection Method Based On Strong Tracking Taylor Extended Kalman Filter

With the rapid development of social economy and technology,electric energy has become one of the most important energy sources for human survival.Power quality has gradually attracted more and more attention.Nowadays,the widely use of a large number of nonlinear power-electronic equipment has brought lots of disturbances to the power system.The presence of disturbances may cause power quality problems,affect the normal and stable operation of the power system,and even endanger our safety,leading to huge loss in economic.Therefore,it is essential to find a suitable power quality detection method in order to detect power quality parameters in real time and improve power quality.Actually,power quality detection is about detecting and analyzing power quality signals,so a large number of signal processing methods have been applied to the field of power quality detection.In order to solve the problems caused by power quality,deep studies of power quality have been made by researchers from home and abroad with some great achievement.Detecting power quality disturbance signals quickly and accurately is the key to improve power quality.Four kinds of common power quality detection methods,including root mean square(RMS)algorithm,Fourier transform(FT),wavelet transform(WT)and recursive least square(RLS)algorithm,are introduced in this paper.Simple simulation examples are given for these four algorithms in order to illustrate their advantages and disadvantages as well as their applications in the fields of power quality detection.Then the fundamental of Taylor extended Kalman filter is emphasized on the basis of Kalman filter(KF)and extended Kalman filter(EKF).TEKF is small in the number of state variables that contains less dimension of state transition matrix and reducing computational burden,but fail to track mutation signal quickly and accurately.Therefore,a power quality detection based on strong tracking Taylor extended Kalman filter is purposed,combining TEKF with strong tracking filter(STF).First,amplitude and phase angle are truncated at the second order Taylor expansion separately.Then,with the help of a scaling factor,the covariance matrix is adjusted according to the theoretical residual and the actual residual so that the ability of the algorithm tracking mutation signal can be enhanced.After giving the flow of power quality detectionbased on STEKF,four kinds of signals are simulated on the Matlab platform,such as amplitude modulation signal,phase modulation signal,voltage sag fault signal and rectifying harmonic signal.The former two signals are generated by analytical functions and the left two are generated by a three-phase system built in Simulink.Finally,STEKF algorithm is implemented on DSP chip TMS320F28335.Simulation and experiment results show that the purposed STEKF algorithm is faster in tracking speed,higher in detection accuracy and more suitable for the real-time application of power quality detection.