Study On Identification Method Of Power System Leading Node For Wind Power Generation Group

With the country’s support for renewable energy development, China’s wind power industry grows up rapidly. At present, China has successively built seven "10,000,000kW wind power base", most of which are at the end of the grid, the grid structure is weak. Recently, several cascading failures of wind farms occurred in domestic, which made wind turbines trip off from grid and become a threat to security and stability operation of grid. One of the reasons is unreasonable configuration and control of reactive power. Considering the voltage control problem of large-scare wind power accessing to the regional power grid, from the system’s point of view, the key of reactive power voltage control is to find pilot nodes. This paper studies the voltage distribution characteristics of wind farms based on the actual data of wind power base. On this basis, an approach to pilot node identification is proposed. The main works are as follows:At first, this paper studies the basic operation theory of doubly-fed induction generator, including its wind speed model, wind turbine model, generator model and control system model. And this establishes the foundations for follow-up studies.Then, several models are set up according to the actual data of wind farms with the software called DIgSILENT PowerFactory, such as the doubly-fed induction generator model, the wind farm model and the regional power grid model with large-scale wind farms. Then, the voltage distribution characteristics of regional power grid with large-scale wind farms under a different output mode and the wind power active output fluctuations are analyzed. The results show that after the large-scale wind power integration, the grid voltage will decrease with the wind power’s increase, and wind farms can easily separate from the power network under large fluctuation of wind speed.Next, an approach to pilot node identification is proposed by considering the relevancy among wind farms. The main electrical characteristic parameters are obtained by adopting the bidirectional electrical dissection method for use in calculating the index of electrical correlation among wind farms and that of pilot node evaluation, thus pilot nodes are identified properly.In the end, analysis results from the IEEE 39-bus system show that the approach used to select pilot nodes is rational and effective.