Research On Coordinated Reactive Power Optimization Of Distributed Wind Farms And Regional Network Under Uncertainty

Recently, the utilization of wind power, which is one of effective paths to settle the problem of energy shortage, is growing rapidly in regional network. However, new problems have been brought to the reactive power/voltage control of regional network due to the uncertainty of wind power. In order to solve the voltage problem to a better acceptance of wind power and make full use of the reactive power regulation capability of doubly-fed and direct drive wind turbines, the reactive power optimization of regional network with wind farms has become the current research focus. In this paper, the research on coordinated reactive power optimization model of regional network and wind farms under uncertainty is done, and the following aspects are included:Firstly, the feature of regional reactive power optimization and reactive power regulation means of regional network with wind power are discussed, then the regulation characteristic of these means are analyzed and reactive power range of doubly-fed and direct drive wind turbines are obtained;Secondly, the reactive power output of wind farm is considered as coordinating variable and the calculation model of its range is proposed considering the wind farm internal wiring. Then the day-ahead reactive power optimization model of regional network side is constructed taking capacitor and tap as decision variables and their action times as constraints. On this basis, treating the uncertainty of wind output and load as the interval constraint, a bi-level real-time reactive power optimization model of regional network is proposed, where the up-level is to minimize the power loss and the sublevel is to find the worst operation scenario of regional network, thus reducing the losses while meeting the voltage operation requirements;Thirdly, the reactive power allocation strategy of wind farm to minimize power loss is proposed in which the control variables are determined according to the regional dispatch target;Finally, a regional network with several wind farms is applied for the case study. The results show that the day-ahead and real-time model are helpful to deal with uncertainty and solve the voltage problem. The analysis also shows the capacity calculation model of wind farm can improve the accuracy of regional scheduling and the allocation model can improve economy on the basis of meeting schedule instructions.