The Study To The Power Quality Problems Of Wind Farm Connected To The Grid

Along with the capacity of the wind form are bigger than before , the influence to the system is also more and more obvious. The research of the influence to the grid has become an important topic. In early days the capacity of the single machine is smaller. The machine mostly adopted asynchronous generators because of simple structure and connecting to the grid easily. It directly linked to the distribution network. The wind form is often in sparsely populated at the end of the power supply network, and the capability of supporting impact is very weak. With the application of the constant frequency and variable-speed generator and other new generating units, harmonic pollution, voltage fluctuations and flicker coming from the wind farm to the grid, and other power quality is becoming increasingly serious. With the scale of the wind farm expanding, power quality problems caused by large power grid caused to be the extensive attention.This paper analyzes the wind turbine on and power quality of the power grid, thoroughly studies the cause, harm, relevant knowledge of voltage fluctuations and flicker, the bias voltage as well as power harmonics. Accurate fault location and feature extraction of the power quality provide necessary basis in order to effectively assess the quality of power quality, can promote the quality of the analysis of the theory, as well as the level of power quality detection and treatment.This paper includes:(1) Analyze reasons of the voltage deviation caused by the wind farm to grid, and to find effective methods of wavelet transform, position the disturbance voltage waveform of the deviation effectively.(2) Analyze reasons of the voltage fluctuations and flicker caused by the wind farm and focus on the effect of tower shadow and wind shear on the output power. Compared with analysis of the flicker monitor of IEC , provide detection method flicker problem.(3) Analyze reasons of harmonics caused by the wind farm, provide detection and location method caused by large-scale wind farm problems, isolate the effective harmonic element.(4) According to the signal characteristics and singularity detection principle, combining the wavelet transform modulus maxima theory, multi-resolution decomposition, extract wavelet transform modulus maxima of signal singularity, achieve the exact location of the failure.