| With the large-scale access of renewable energy such as wind power and photovoltaics to power systems,the weak inertia,volatility,and uncertainty of these renewable energy pose a great challenge to grid stability.Because of inherent defects of the synchronous generator itself,such as low ramp rate and slow response speed,the performance of the synchronous generator cannot meet the frequency regulation requirements of the rapidly developing power grid.Therefore,it is necessary to introduce more high-quality frequency adjustment resources to improve the frequency quality index of the power grid.In recent years,the energy storage technology represented by electrochemical batteries has developed rapidly,and it has rapidly increasing scaled application in power systems.Because the battery energy storage system has the characteristics of fast response and accurate tracking,it can effectively improve the frequency adjustment effect in the grid frequency regulation.According to the problems of energy storage with conventional generators participating in secondary frequency regulation,this paper studies related technical and theoretical issues from four aspects: control method,simulation model,output design,and energy storage participation in secondary frequency control strategy.From the principle of frequency adjustment in the power system,this article analyze the frequency characteristics of load and power in the power system.Based on the secondary frequency modulation process of power system,a control method for energy storage to participate in the secondary frequency regulation of power system is selected and proved,and a control block diagram for energy storage to participate in secondary frequency regulation of power system is constructed.Constructing an equivalent energy storage simulation model for secondary frequency regulation of power systems.According to the existing problems in the energy storage simulation model proposed in the current research,this paper analyze the energy output involved in the second power frequency characteristics of the power system,study the internal structure of the energy storage battery system and ach module participates in the frequency adjustment process.On these foundations,an equivalent simulation model of energy storage is proposed to meet the demand of power system frequency regulation.And determine and verify the value of its model parameters.Finally,a frequency response model of two-area interconnected system with energy storage is established.In order to solve the problem of coordination between the need of frequency adjustment and the need of energy storage recovery,realizing the complementary advantages of energy storage and conventional generators.In view of the study in the relationship between the ACE status and the frequency regulation residual capacity,the operating status of battery energy storage is divided into three typical operating modes: self-recovery operating conditions,frequency regulation operating conditions and integrated operating conditions.Uising the characteristics of Logistic regression function to propose a comprehensive control strategy of energy storage battery-assisted thermal power generators participating in secondary frequency regulation of power system,which can realize the organic unity of the self-adaptive output of battery energy storage participating in frequency regulation and the self-recovery requirements of battery energy storage improving the effectiveness of battery energy storage capacity and can effectively improve the frequency regulation effect.The simulation model was built in MATLAB/Simulink,which perform the secondary frequency regulation of the battery energy storage cooperating conventional thermal generator in the short time step and long time continuous disturbance,and the results show that it is correct and effective that the simulation model and control strategy of battery energy presented in this paper. |
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