Research On Self-start Strategy Of Storage-based Wind Farm For Black-start

When making the black-start plan,the system should be divided into several subsystems which can achieve self-start by the black-start power source in the local area,then the whole system can recover by interconnection of these subsystems.Hydroelectric plant(Pumped storage power station contained)is the best choice for black-start power source,but because of the restriction of regional source,water source is shortage in Inner Mongolia and northwest China.Once blackouts occurs,the recovery of power grid would depend on the major grid,which would cost a longer time.Wind resource is rich in these area and wind power becomes the major generation type.It would add the capacity of black-start power source and enhance the fault recovery speed if wind farm occupied with high capacity battery storage system is used as the black-start power source of local grid.The self-start of storage-based wind farm is the key procedure for black-start,so a deep research of self-start strategy is made in this paper:(1)Simulation model of storage-based wind farm is established: the mathematical model of DFIG in no-load and grid-connected condition is established by analyzing the operation principle;then the mathematical model of DFIG is discretized by implicit trapezoid method,based on which the dual operation simulation model is established;simulation model of battery storage system is established by operation principle analysis.From the above,the whole simulation mo del of storage-based wind farm is established to research the self-start strategy.(2)The self-start strategy of storage-based wind farm is researched.Firstly,the self-start scheme is designed.Then battery storage system’s control strategy of rising voltage from zero is proposed.The optimal transformer energization scheme is made by analyzing production mechanism of magnetizing rush current and sympathetic rush current and comparison of three different box type transformer charging scheme.Finally,the idle load grid-connection process of DFIG is simulated.The research indicates that storage-based wind farm can achieve self-start with application of the proposed scheme.(3)The coordinated power control strategy of battery storage system and wind farm in islanded condition is researched,which contains the local control strategy,active power and negative power controller,and power distribution module.With application of this strategy,energy storage system’s state of charge can be maintained in the pre-set section,and power adjustment margin can be enlarged,the voltage and frequency of system would be stable and auxiliary engine of thermal power unit can be started.By research in this paper,with the assist of energy storage system,wind farm can achieve self-start,then it can act as black-start power source to start the nearby thermal power unit coordinating with energy storage system.