| The substitution of the renewable energy sources（RESs）units for traditional thermal power units is an effective way to alleviate the greenhouse effect.However,it leads to the lack of the inertia response and the primary frequency reserve for the system.At the same time,the fluctuation and the uncertainty of the output of the RESs will increase the generation frequency of the unbalanced power,bring the energy waste,and reduce the stability and the economy of the operation.Nowadays,with the maturity of large-scale energy storage technology,the energy storage system（ESS）has attracted extensive attention in the frequency modulation and the planning of the grid.Based on the frequency response requirements of the system in the stage of the inertia support and the primary frequency regulation,the paper makes an in-depth study on the configuration method and the modulation characteristics of the ESS.Firstly,taking the rate of change of frequency（ROCOF）and the steady-state frequency deviation（SSFD）as the limit,the linear relationship between the maximum unbalanced power that the system can withstand and the known parameters such as the equivalent inertia constant,the adjustment coefficient and the proportion of RESs is established.The regulation quantity of the contribution of the ESS to the frequency response is defined,and the influence of the ESS capacity on the regulation is discussed.That is,the necessity of the ESS input and the reasonable allocation of the capacity has been proved.Secondly,through the analytical method,the capacity and the control parameters of the ESS meeting the requirements of the system frequency support are quantitatively configured to supplement the lack of theoretical support in the current ESS configuration process and improve the reliability of the configuration results.The third-order virtual synchronous generator control model of the ESS grid-connected inverter is built for simulation,and the accuracy of the configuration results is proved in different RESs proportion systems.In addition,taking the equivalent unit regulation power contributed by the ESS in the frequency support as a reference,the frequency response contribution,the frequency modulation output ratio and the output power characteristics of the ESS under different unbalanced power are characterized and analyzed.Based on the above research,considering the influence of dynamic frequency dispersion in the system,the steady-state recovery time and the amplitude coefficient are defined as evaluation indexes.The action mechanism and regulation effect of the virtual inertia constant,the virtual damping coefficient and the virtual frequency modulation coefficient in the ESS grid-connected inverter are deeply analyzed and compared from the two aspects of the system and the ESS,and the inertia configuration results of the ESS are optimized while considering the demand of the frequency response.Finally,a multi area 12 node power system is built in DIg SILENT/Power Factory to simulate and verify the relevant research.The results show that the ESS under the proposed configuration method has strong controllability.It can accurately provide the inertia and the primary frequency reserve required by the power grid,and improve the renewable energy grid connection environment effectively.The proposed frequency response evaluation index can further optimize the configuration results of the ESS,and provide a reference for the ESS to participate in the frequency modulation of the power grid. |
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