Research on Distributed wind Power Reactive Voltage Coordinated Control Strategy Connected to Distribution Network

Abstract

Distributed wind power generation access to the distribution network will affect the power flow of the distribution network. It will definitely affect the voltage stability. Based on this, this paper proposes a reactive power control strategy based on the power prediction of wind turbines that applies to the distribution network. The structure of the reactive power control strategy is divided into three layers, including the reactive power prediction layer, the reactive power setting layer and the reactive power distribution layer. The reactive power prediction layer considers the random characteristics and fluctuation characteristics of the wind speed, and carries on the power prediction of wind turbines. According to the predicted information on the active and reactive power of ultra-short-term wind turbines, it will reduce the voltage fluctuation caused by the change of wind speed varying with time. The reactive power setting layer proposes an improved reactive power setting method considering multiple time scales. The reactive power distribution layer is divided into three levels: the first level is the reactive power distribution between different nodes, the second level is the reactive power distribution between different wind turbines connected to the same node, and the third level is the reactive power distribution between the stator side and the converter on the grid side inside the DFIG. Based on the output reactive power of each node in the distribution network has different influences on the voltage and also consider the reactive power margin of each wind turbine, different reactive power allocation strategies are adopted at the above three levels. The analysis is performed by improved IEEE 14-node system. The example shows that the reactive power control strategy of distributed wind power generation connected to the distribution network based on the power prediction of wind turbines can provide more reactive power support to the distribution network, and improve the voltage drop in the distribution network. The output reactive power of the doubly-fed wind turbine can be fully utilized. And it enhances the flexibility of the reactive voltage regulation in the distribution network.