Application Of Energy Storage System In Power System Peak And Frequency Regulation

In recent years,the proportion of wind power integration in power system has been continuously increasing,making bad influence in the performance of peak and frequency regulation in power grid.In order to avoid frequent start-stop or depth peak regulation in general units,it is necessary to improve the system's ability to integrate wind power.In this thesis,the most widely used battery energy storage system is used to improve the system absorptive capability and the capacity configuration method of it is analyzed.In addition,a modified grid converter control strategy based on virtual synchronous generator is utilized to improve the grid frequency stability while peak regulation.The main research contents of this thesis are as follows.(1)Based on the historical data of wind power and load in Beijing-Tianjin-Hebei(Tangshan)in 2016,the distribution of wind power fluctuation is analyzed to lay the foundation for frequency stability of grid with high proportion of wind power integration and the variation of peak-valley difference before and after wind power generation is calculated.The probability density function and the cumulative probability distribution function of the grid peak-valley difference are estimated based on the nuclear density to analyze the influence of wind power integration on the system peak regulation,which lays the foundation for peak regulation research of the grid.(2)In order to fully improve the life cycle of the decommissioned battery,the characteristics of decommissioned batteries is analyzed and the service life of the echelon-used battery is calculated.A double-layer optimization model using the battery storage system is designed based on the system peak regulation.Capacity configuration of the battery storage system is solved in the model using genetic algorithm with serveral iterations,and the method is verified in MATLAB.Through the example analysis,it is proved that the double-layer optimization model of battery energy storage system can improve the wind power absorptive capability and the load volatility of power grid.(3)A modified grid converter control strategy based on virtual synchronous generator is utilized to improve the grid frequency stability while peak regulation.The model of the traditional generator is analyzed,including the electrical part and the mechanical part,as well as the control system of the generator-the speed governing system and the excitation control system.The control strategy of the virtual synchronous generator is designed,including the virtual synchronous generator algorithm,the virtual speed regulation system and virtual excitation control system.The feasibility of virtual synchronous generator control strategy is verified in MATLAB/Simulink.The simulation results show that the converter based on virtual synchronous generator can participate in the peak regulation of power system.In addition,the energy storage system can be regarded as a generator with the frequency regulation characteristics,and the grid converter can make quick response while the frequency changes to realize the frequency regulation.