Stability Analysis And Control Of The District Grid Containing Large-scale Wind Power

As the development of wind power technology and the implementation of renewable energy policies, China’s wind power construction has entered a stage of rapid development. However, most wind farms are located in the end of the grid and have weak links with the main network, as a result, the integration of wind power will bring a lot of problems. In order to ensure that wind farm has a positive effect on the power system, it is necessary to analyze the influence of the wind power integration on the power system stability (including static voltage stability, small-signal stability and transient stability) and propose coordinating control strategy based on the existing problems. Based on an actual technical project, this paper takes an actual region grid with large-scale wind power as the object of the research, analyzes the stability of this grid and proposes voltage coordinating control strategy applying to this region grid. The major work of this paper as follows:(1) Establish a dynamic model of doubly-fed wind power generator. Control block diagrams and principles of the aerodynamics module, shaft system module, pitch control module, electric control module and the generator/inverter module are analyzed.(2) Propose the method of wind farm transient model selection applying to the large system simulation. From the aspects of the installed capacity, integration location and the type of wind farm and the arrangement mode of the wind turbine generators, issues which need to be considered when selecting a transient model for the wind farm are discussed. The influence of using different transient models on the planning network is evaluated by diversity index, and the method of wind farm transient model selection applying to the large system simulation is proposed.(3) Based on the wind power planning data of a region grid, the static voltage stability of region grid with large-scale wind power is analyzed by the method of P-V, V-Q curve analysis, and the small-signal stability of the region grid under different wind power output ratio is calculated by BPA software simulation.(4) Measured by the critical clearing time, the influence of thermal power and large-scale wind power on the transient stability of the region grid is investigated by time-domain simulation.(5) Coordinating control strategy applying to the current region grid is proposed based on the problems brought by the wind power integration, the validity of the strategy proposed is verified.Scientific achievements of this paper are validated by a provincial planning department as a part of the technical project.