Research On Power Quality Analysis Methods Of Distribution Network

With more and more non-linear and high-power electron devices are putting into use inthe distribution network, the harm of power quality has been becoming more and moreserious. Detecting and analyzing power quality parameters of distribution network can graspthe quality of power supply in real time then reduce all kinds of power quality problems indistribution network. Therefore, in allusion to detecting and analyzing methods of steady stateand transient power quality parameters in the distribution network, this paper will do thefollowing researches:This paper presents an improved harmonic and inter harmonic analysis algorithm basedon Hilbert huang transform. The algorithm adopts the piecewise cubic hermite interpolatiionto fit extreme point curve for the empirical mode decomposition then through HT to calculatethe frequency and the amplitude of signal. Simulation results of analyzing35kV distributionnetwork signal show that the method has high frequency and amplitude resolution. Thepracticality of method is higher and it is applicable to the complex non-stationary signal.Voltage and frequency deviation, three-phase unbalanced analysis methods are also studied.The study is basd on db4of WT to realize the analysis and location of transientdisturbance. Compared with other db series, db4is more accurate on transient disturbance.Algorithm is based on sampling frequency and sampling data of signal, and then it determinesthe decomposition scale of WT, and judges the mutation points of signal, then judges thetypes and the moment of disturbance. The simulation results show that the algorithm caneffectively detect voltage sag, swell, interruption and instantaneous pulse power disturbanceproblem and it can be accurately on the location of all kinds of transient power disturbancebegin-end time, fully meet the real demand of distribution network detection system.Design project of35kV distribution network power quality analysis device is gived.Design of hardware system uses IPC+PCI of the high-speed acquisition card architecture atthe same time software system applies the algorithm gived in this paper to realize the datacollection, parameter calculation, real time detection and other functions based on PCplatform.In a word, this paper does a detailed study which is aimed at the parameters detectingand analyzing methods of steady state and transient power quality in the distribution networkand the analyzing device design of35kV distribution network power quality. It providesaccurate and efficient methods for analyzing power quality in distribution network.