Evaluation And Control Measures On Power Quality Of Wind Power Grid

As a clean and efficient new energy resource, wind power has developed rapidly in recent years. Along with the increase of wind farm capacity, the influence brought by large wind farms to power system has become greater and greater. The power quality issues of wind power grid, such as the voltage deviation, voltage fluctuations, harmonics and three-phase imbalance, give a serious impact to the safe and stable operation of the grid. The power quality issues of wind power grid involve technical problems and management challenges of power grid in our country, thus the research subjects about the wind farm power quality assessment and control measures own important theoretical and practical significance.(1) The thesis analyzes changing speed and constant frequency operation principle and mathematical model of double-fed wind turbine, and investigates power quality issues of wind power grid, and summarizes the relevant national standards of these four power quality indicators.(2) The thesis builds a power quality comprehensive level evaluation model by Least Squares Support Vector Machine (LSSVM) algorithm in MATLAB, and divides power quality into eight grades which can evaluate the power quality levels of each node in wind power grid.(3) The thesis builds wind power farms considering wake effects and wind power grid simulation model in MATLAB/Simulink platform, gathering and calculating power quality data for each node of the system at run time through MATLAB programming, and uses LSSVM power quality comprehensive evaluation model to evaluate the level of power quality grade of each node of the systems. By evaluating power quality for each node of wind power farm access to the system from different nodes and different capacity, which can provide reference for optimization sitting and capacity of wind power farms.(4) The thesis uses LSSVM power quality comprehensive evaluation model to evaluate the level of power quality grade of wind power grid installing SVC and STACOM, and get the quantitative improved level of power quality, which can verify the control effects of power quality by the two devices.(5) Based on analyzing power quality control device costs, the thesis builds the model of wind power pricing by different quality, through investing and allocating reasonable of the limited funds, achieves a best balance between control levels and costs of the wind power farm, and realizes better power quality at a higher price of wind power, and verifies the model is feasible from economic benefits promoting power quality control of wind power farm.