Research On Black-Start Coordinated Control Technology Of Offshore Wind Farm Based On Diesel-Storage Combined System

The bright prospect of high-quality energy development relies on the construction of new power systems.In the future,the scale of energy generation,transmission,transformation,and distribution systems oriented toward new energy will become more and more complex,gradually changing the traditional operation mode of the power system,which is dominated by thermal power units before.Risk of failure and large-scale power outages,so more black-start power supplies and emergency plans adapting to them are needed.As a representative of new energy,wind power has rapidly expanded its application scale in recent years,and it is feasible to explore wind power as a black-start power source.To enable wind farms to have black start capability,it is urgent to carry out in-depth research on auxiliary power supply configuration,control loop design,and start-up path planning.This thesis takes the participation of offshore wind farms in the black start as the starting point,and exploratively carries out the work of the research on black-start coordinated control technology of offshore wind farms based on the diesel-storage combined system.The specific contents of this thesis are as follows:(1)An offshore wind power black start auxiliary power configuration strategy based on the Copula method is proposed.Firstly,the wavelet transform method extracts the turbulent signal in wind power,qualitatively analyzing the modulation characteristics of turbulent power and mean power.Then analyze the calculation method of rated capacity and rated power of the battery energy storage system(BESS),analyze the correlation between rated capacity and rated power caused by wind power characteristics,and then use the diesel generator set and BESS.The objective function comprises the configuration and operating cost of auxiliary power units.Finally,the diesel generator and BESS configuration results are given based on the Copula fitting distribution method,the Empirical Copula distribution method,and the marginal distribution method.The diesel generator and BESS suitable for wind farm black start are given under the 95% confidence level.(2)A start-up method and control strategy suitable for the black start process of offshore wind farms are proposed.Firstly,the minimum recommended standby power of the BESS before the black start is given by using the wind power value at risk method.Then the selfstarting scheme suitable for the wind-storage-diesel combined system is proposed,and the control strategy of BESS is improved to realize zero voltage start reducing the inrush current of the system.Then use active power coordination control technology to avoid overcharge of the battery and continuous jumping of wind turbine instructions under traditional strategies,and realize the smooth switching of wind power control instructions according to the state of charge(SOC).Finally,the reactive power coordinated control technology is proposed to improve the control strategy of the BESS and realize the phase-adjusted operation mode of the wind turbines improving the voltage quality of the system.(3)A path optimization method is proposed in the black start process of offshore wind power systems.This method firstly carries out data-driven modeling on the normal operation status of wind turbines.The operation statuses of the wind turbines are evaluated by the residual errors between data predicted by normal models and actual data.Then,the operation statuses of the turbines are used as a reference for black start path planning to achieve a balanced startup sequence between the shortest electrical distance and the largest total power generated.Finally,according to the results of load flow calculation,the optimal point of the wind turbines with phase-adjusted operation mode is found for reactive power compensation.Overall,the black-start scheme of the wind farm is obtained,which provides a reference for the selection and start-up sequence of turbines in the black start process.