Short-circuit Current Calculation And Low Voltage Ride Through Capability Analysis Of Grid Connected Wind Farms

Currently, wind energy is the most valuable renewable energy, which has been rapidly developed in China. However, with the wind power penetration level increasing, the uncertainty of wind power and its own features brought a great impact on the stability and power quality of grid. Many foreign countries with advanced wind power technology have a higher requirement for wind power integration:on the one hand, the transient characteristics of wind turbines should be great improved. the other hand, protection and other measures are also required. Therefore, in-depth research on short-circuit current characteristics of grid connected wind farms and how to achieve low-voltage ride through capability have important practical significance.In this paper, the double-fed wind turbine is studied as the research object. Firstly, a detailed mathematical model is established and the control strategy of wind turbine generator is studied deeply. Secondly, the short-circuit current formula of double-fed induction wind generator are derived. Later the equivalent method of wind farm is proposed and the impact of wind farm integration into power system on voltage stability of power system based on short-circuit capacity ratio is analysised. Then propose a control strategy in response to a DFIGs-wind farm including fast-pitch-control, optimal reactive power control scheme and reactive power compensation based on SVC to achieve its low voltage ride through capability. Finally carried out simulation in the actual system.