| With the rapid growth of new energy sources such as photovoltaic and wind power,while solving the increasing demand for electricity,due to its own weak inertia and vulnerability to external influences,when it is connected to the grid on a large scale,it brings a series of hazards to the power system,affecting the safe and stable operation of the power grid,while the traditional frequency modulation units such as thermal power units with low climbing speed and slow response can no longer meet the new requirements.In the case of frequency modulation requirements,it will be of great significance to improve the performance of power grid frequency modulation through a new type of frequency modulation means.In recent years,energy storage technology represented by lithium batteries has developed rapidly,and the cost and technology of its participation in frequency modulation have been feasible.Because of the advantages of accurately tracking and quick response of energy storage power supply,assisting traditional frequency modulation units such as thermal power to participate in power frequency modulation can significantly improve the frequency modulation capability of the system.On the basis of systematically summarizing the research status of energy storage power supply participating in power grid frequency modulation and defining the main problems,this paper focuses on the secondary frequency modulation of hybrid energy storage power supply auxiliary power grid,and studies four aspects of control mode,frequency modulation selection,frequency response model and output control strategy.The background of this paper is introduced.When the global new energy generation is increasing rapidly,but the conventional frequency modulation units are not enough to complete the task of frequency modulation,energy storage assisted power grid frequency modulation has become the current research hotspot.The necessity and feasibility of energy storage participating in power grid frequency modulation are analyzed.Finally,the current research situation of energy storage participating in power grid frequency modulation is analyzed and the existing shortcomings are summarized.Starting from the frequency characteristics of load and generator set are expounded,and the main frequency modulation types and control modes of power system are analyzed.On this basis,the model control mode and block diagram of secondary frequency modulation for auxiliary conventional units of energy storage power supply are constructed.Starting from the types of energy storage suitable for power system frequency modulation,this paper determines the type selection of hybrid energy storage frequency modulation combined with frequency modulation technology and economic indicators.Based on the analysis of the internal structure of energy storage and its participation in the frequency modulation coordinated response process,an equivalent simulation model of hybrid energy storage system is proposed to meet the requirements of power system frequency modulation,and then the frequency response of dual-area power network with hybrid energy storage is constructed.Model.In order to combine the advantages of high response speed of energy storage power and large sustained output of power storage capacity in hybrid energy storage system,the output control strategies of hybrid energy storage under normal frequency modulation scenario and special scenario are constructed respectively,taking into account the operation status of power grid,the demand of frequency modulation and the frequency modulation capability of hybrid energy storage itself.The strategy synthetically judges the system's FM requirement and the energy and power energy storage FM capability,and achieves the complementary and coordinated operation between the hybrid energy storage system and the power grid.The rationality and validity of the control strategy constructed in this paper are verified by simulation under typical continuous disturbance conditions. |
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