| The rapid enhancement of offshore wind power manufacturing and grid-connected technology,as well as the characteristic of rich offshore wind resources lead to the installed capacity of offshore wind power continue to increase.Due to the complexity of sea conditions and the variability of climatic conditions,the large-sacle grid-connected offshore wind power has increased the requirements for power flow control in power system,becoming an important factor affecting the security and stability of power grid.Fully coordinating various resources in power system is an effective measures to improve the safety and stability of offshore wind power connected system.In addition,the development of smart grids has further improved the ability of the grid to respond to various faults.In order to maintain the economic distribution of power flow in power system and the security and stability operation of power grid,the grid resilient coordinated control technology is utilized to effectively dispatch the active control capabilities of generators,loads and even offshore wind farms in the power system,which not only has theoretical value for studying the interaction between offshore wind farms and power grids,but also provides practical guidance for power flow and safety and stability control in large-scale offshore wind farms grid-connected system.Based on the impact of large-sacle grid-connected offshore wind power on the power flow and secriuty of power system,this paper exploratively carries out revelant research on“Research on resilient coordinated control of power system containing large-sacle offshore wind power”.Aiming at the wind power accommodation problem brought about by large-scale grid-connected offshore wind power,and the safety and stability issues in power system under extreme weather conditions,the offshore wind power accomodation technology based on flexible control capabilities of power grid devices is studied in this paper.Futhermore,the active power control strategy for offshore wind power considering flexible control capabilities of wind turbines and the ordered curtailment strategy for offshore wind power based on source-load resilient coordinated control capabilities are developed.The main work and innovation of this paper are as follows:(1)An offshore wind power modeling technique considering the space-time characteristics of wind power is proposed.Considering the wake eddect of wind turbines,and the output characteristics of offshore wind power under various wind conditions are analyzed.In addition,the impact of offshore wind power on power flow and stability of the system is analyzed,it is pointed out that large-scale offshore wind power will change the power flow distribution,which may cause uneven power flow distribution,and the offshore wind power exit operation in extreme weather will seriously affect the safe and stable operation of the power grid.(2)An optimal allocation and operation control strategy of DSSC considering flexible control capability is proposed.As for transmission line congestion problem caused by high penetration of offshore wind power,the proposed strategy responds to flexible control capabilities from the aspect of power system devices.The first stage is optimal allocation of DSSCs considering multiple scenes,with the target of minimizing line congestion rate,so as to determine the location and capacity of the DSSCs.The second stage is operation control of DSSCs,in which DSSC’s power flow control capability can be utilized to achieve optimal system operation costs under normal operation mode as well as increase renewable ernegy comsuption under abnormal mode.(3)An active power control strategy for offshore wind power considering flexible control capability of wind power is proposed.Aiming at the wind energy loss caused by the abandonment of offshore wind power,this strategy considers the utilization of the flexible control capability of wind turbines to reduce the wind energy loss and provide a certain power support for power grid.Considering the advantages of rotor speed control in reducing wind energy loss,when the rotor speed control can meet the demand of wind curtailment for wind farm,the optimal rotor speed control is utilized to determine the amount of wind curtailment for each wind turbine,thereby maximizing rotor rotational kinetic energy.The optimal pitch angle control will be carried out when the rotor speed control reaches the limit,during which the target of active power control for wind power can be achieved while minimizing the adjustment of pitch angle.Therefore,the mechanical damage of wind turbines caused by frequent adjustment of the pitch angle,can be effectively reduced.(4)An ordered curtailment strategy for offshore wind power based on source-load resilient coordinated control capabilities is proposed,in order to achieve offshore wind power ramp control under extreme weather conditions.First,based on the actual typhoon path,the timesequence characteristics of offshore wind farms exited in typhoon condition is analyzed.On this basis,the operating cost of generators,the cost of wind power curtailment,and the cost of demand response are comprehensively taking into consideration,in order to optimize and orderly exit the offshore wind turbines before the typhoon approaches.Therefore,the adjustment capacity of the thermal turbine can be scheduled in advance,and the adjustment capacity of hydro power and responsive load in the system can be fully utilized to reduce the operating cost of the system on the premise of ensuring the safety and stability of the system. |
