Impact Of Doubly-fed Wind Power Grid Integration On Transmission Line Relay Protection And Improvement Measures

In recent years, in response to the worldwide problems caused by environmental pollution and energy shortage, can scale development and utilization of wind power with its own advantages in the rapid development. However, wind power has randomness, volatility. And mainstream fan for the doubly-fed induction wind turbine, which fault characteristics and traditional synchronous generators are significantly different. With the increasing penetration of wind power in power grid, considering the impact of wind power grid integration on transmission line relay protection based on conventional configuration is necessary. In this paper, doubly-fed wind turbine with rotor Crowbar protection and wind farm in the time domain simulation model, the fault features were studied. On this basis, the impact of large-scale doubly-fed wind power grid integration on more than110kV voltage class line conventional protection were researched, and proposes the corresponding improvement measures.First of all, for wind machine, doubly-fed induction generator and converter control system mathematical model has carried on the comprehensive research. For doubly-fed induction wind generator, its complete simulation model has established with DIgSILENT simulation software, including wind turbine model, model of shaft system, variable pitch model, inverter control system and protection system control. Besides, short circuit current characteristics of doubly-fed generator has analyzed.Secondly, On the basis of our current wind farms typical connection form and the current equivalent model, the transient equivalent model of doubly-fed wind farm with DIgSILENT simulation software has established. Short-circuit current calculation formula, positive and negative sequence impedance characteristics were analyzed. Under various wind farms short circuit fault, the fault voltage and short current characteristics has researched by electromagnetic transient simulation. Besides, weak power characteristics of wind farms were studied.Finally, Analyses the conventional relay protection configuration of wind farm transmission line more than110kV class. Based on fault feature analysis, the influence of wind power on current differential protection, pilot protection, distance protection and fault phase selector has researched. Combined with a wind farm in ningxia has carried on the simulation test. According to the impact of wind power on transmission line protection, the improvement measures of transmission line relay protection configuration and a fault phase selection principle were proposed.