Research On The Start Control Strategy Of VSC-based DC Grid With Large-Scale Wind Power

The energy structure of present world is undergoing transformation.Predictably,renewable energy would replace traditional fossil energy as the main source of the electric power supply in the future decades of electrical power system development.In this process,how to achieve the connection of large-scale renewable energy and improve the consumption ability on renewable energy of regional power grid is a problem that energy development would face.With the rapid development of VSCHVDC,DC Grid based on this technology would solve the problem effectively.In this paper,the start process of VSC-based DC Grid with large-scale wind power is researched.First of all,the precharging process of single converter station is considered.The precharging theories of active converter station through ac side and passive converter station through dc side are analyzed respectively.Then,the connection technology of wind farm through VSC-HVDC is researched.The passive inverting control strategy of wind farm side converter station and integration control strategy of wind farm are designed and achieved.Finally,Zhangbei VSC-based DC Grid demonstration project is taken as study background,and the coordinated start control strategy of the whole system after several converter stations are composed together through the overhead lines and HVDC circuit breakers is discussed.The start process of DC Grid under normal condition and several typical operation mode switchovers are designed.Corresponding simulation models are structured in PSCAD/EMTDC in the processes of the research works above,and the correctness of theoretical analyses and the effectiveness of control strategies are verified.