| As the most developed and profitable form of distributed generations at the present hour, wind generation arouses widely concern both in production and science research with wide application prospect. Due to randomness and volatility of wind power, it not only provides power to the grid, but also brings impacts and challenges to planning and operation of electric power grid, which are different from conventional electricity generation. The voltage/ reactive power control strategy of high-voltage distribution network with wind farm is mostly voltage/ reactive power control(VQC), but the current VQC strategy exits some serious defects, such as rigescent parameter and the aggressively over-pursuing for zero exchanging of gateway reactive power, which will reduce the compatibility of power network to wind farms. With the growth of wind power capacity, the technical issues of wind power connecting to power grid will become the bottleneck to restrict the development of wind power. Therefore, it is important for studying the parameter dynamic setting of VQC strategy in high-voltage distribution network with wind farm to improve the utilization of wind power resources and ensure economic and security, especially the gateway reactive power parameter. This paper is focused on the method of line planning and the dynamic setting of gateway reactive power interval of VQC of high-voltage distribution network with wind farm.Firstly, the influence of wind power on voltage and line power flow in high-voltage distribution network is analyzed, and then the power lines are divided into wind power branch and wind power parallel one. From the analysis, we can see that wind power brings great influence on wind power branch but nearly no influence on wind power parallel branch. Therefore, when wind farm is connected to the grid, we just need to consider its influence on wind power branch.In the network planning, a line planning method of high-voltage distribution network with wind farm is proposed. For wind power branch, the mathematical model for load and active power of transmission line is set up. According to this model, the maximum transmission capacity of lines is calculated, and then types of conductors are selected. This new method will be more economy and won’t lead to line overload comparing to traditional line planning, which meets the requirements of safely and stably operation of power grid.In the network operation, the defects of the current VQC strategy is deeply analyzed at first, and then the mathematical model of dynamic reactive power/ voltage optimization based on quantifying the objectives of VQC. The model is built according to one-day energy loss of network, the adjusting cost of regulating equipment, the penalty of voltage constraint and the cost of reactive power releasing, which decouples the each period of optimization and superimpose sub-period so that it takes account of the four control objection of VQC and is measured by economic cost. Then, the dynamic setting of gateway reactive power interval of VQC of high-voltage distribution network with wind farm based on the mathematical model is proposed. For wind power parallel branch, the gateway reactive interval of VQC should be changed with load fluctuation; while for wind power branch, the gateway reactive interval should be dynamic adjusted with wind farm operation besides load fluctuation. At last, the simulation results conducted by programming with C# language show that the effectiveness and practicability of the mathematical model and the proposed method, and it significantly improves adaptability of VQC for the accessing of wind power.This paper is funded by the National High Technology Research and Development of China(863 Programme)(2012AA050201) and National Natural Science Foundation of China(No. 51377060). |
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