Study On The Power Quality Disturbance Detection Considering Wind Power Integration

As the large-scale wind farms are connected to the grid,it will inevitably have a major impact on the stability, economy and power quality (PQ) of power system.Meanwhile,with the power system’s higher requirementsfor PQ, the effect of wind power grid to PQ will become the researchhotspot and difficulty.Hence the detections on PQ disturbancesproduced by grid-connected wind power system, including the disturbance amplitude, disturbance frequency and disturbance duration which can provide basis for fault diagnosis of wind power systems, have great research value.The wind power grid model is established based on the Real Time Digital Simulator (RTDS) in this paper. Based on the analysis of disturbance signals produced by wind power system’s fault, theTsallis entropy, HHT detection algorithm based on EEMD and SK based on Morlet areappliedto detect PQ in this paper.The doubly fed induction generator(DFIG)is chosen to study the effect of wind power grid to PQ, and a DFIG modelis builtby the RSCAD software in this paper.Then,the model runs with the combination of RTDS hardware, and corresponding PQ signals can becollectedfor the detection and analysis of PQ signals.If the traditional methods are used to detect PQ disturbances produced by grid-connected wind power system, it will produce some problems, such as easily affected by noise,large detection error and difficult to decompose mix disturbance. In order to solve these problems, the Tsallis entropy is applied to disturbance location;the HHT detection algorithm based on EEMD is applied in this paper, first, the disturbance signals are decomposed into different intrinsic mode functions (IMFs), and make a model superposition with the IMFs which characterized the same modelto produce the final IMFs, then, the instantaneous frequency and instantaneous amplitude of the IMFs are obtained via Hilberttransform,so thatthe detection of disturbance parameters can be achieved.Since thetransient oscillation widely exists in disturbance signals produced by wind power grid, a method based on Morlet Wavelet-based-Spectral Kurtosis (SK)combined with the EEMD methodis usedto precisely detect the disturbance frequency oftransient oscillation.The DFIG grid model built in this paper can produce a lot of mixing PQdisturbances composed of five PQ signals,includingvoltage swell, voltage sag, voltage interruption, harmonic and transient oscillation. The HHT detection algorithm based on EEMD,which can successfully detect the disturbance duration and amplitude,can decompose the disturbance signals into different intrinsic mode functions (IMFs).The SK method is used to detect the disturbance frequency of transient oscillation precisely.The results of detection show that the method in this paper has smallerrorand high reliability.