| With the continuous implementation of the national new energy policy,vigorous development of wind power has become the trend to solve China's energy problems.However,due to the influence of natural factors,the output power of wind power has a series of uncontrollable characteristics,such as fluctuation and inaccurate prediction,which reduces the reliability of wind farm power generation.In order to solve the problem of frequency instability caused by single wind power connected to power system,the energy storage system is integrated into the wind power generation system,and the excellent technical characteristics such as fast output and stable operation of the energy storage system are utilized to compensate for the uncontrollable shortcomings of wind turbines and to support the frequency of the system in a stable state in time.However,considering the high cost of energy storage,it is necessary to study the optimal control strategy of coordinated frequency modulation for wind storage in order to reduce the allocation of energy storage capacity in wind farms and improve economic benefits.This paper is based on the virtual synchronous generator technology.The main research contents are as follows:First of all,energy storage virtual synchronous generator control strategy is studied.By discussing the control principle of energy storage virtual synchronous generator,the control strategy of energy storage virtual synchronous generator under different technical routes is analyzed in detail.Secondly,the parameter setting and stability analysis are carried out by establishing the grid-connected transfer function model of energy storage virtual synchronous generator under different technical routes.The electromagnetic transient model of power system is constructed by Simulink,and the stability of energy storage system is simulated and analyzed when the control parameters and grid parameters change.Thirdly,the optimal control strategy of coordinated frequency modulation for wind storage is studied.A power simulation system covering wind power,energy storage,synchronous generator and load is built.The possibility of providing inertia and primary frequency modulation for the grid under the rotor inertia control mode of the wind power virtual synchronous generator is studied and analyzed.It is found that there is a secondary frequency drop problem when the wind power is separately involved in the power grid frequency modulation.In order to improve the frequency secondary drop problem,the parameters of frequency modulation support strategy are optimized based on the comprehensive speed recovery strategy.In order to truly solve the problem of secondary frequency drop,the system frequency supported by energy storage alone is used as a benchmark.Under the condition that the original wind storage coordination frequency modulation strategy can not meet the demand,the wind storage coordination frequency optimization strategy is proposed.Finally,optimal allocation of energy storage capacity is studied.Due to the high cost of energy storage,this paper considers the characteristics and economics of frequency modulation technology,and proposes an optimal allocation method for energy storage capacity.Firstly,according to the requirements of frequency modulation,the design method of energy storage rated power and rated capacity is determined.Then,in order to improve the economics of energy storage participating in frequency modulation,a theoretical model of life cycle cost is established.Finally,the capacity allocation is based on different optimization goals,and the optimal energy storage capacity configuration of the coordinated frequency modulation control strategy is obtained. |
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