A DC microgrid group energy storage optimization and coordinated control method

Abstract

The invention relates to an energy storage optimization and coordination control method for a direct-current micro grid group. When multiple sub micro grids are operated in parallel, an energy storage system in each sub micro grid automatically adjusts power distribution according to the maximum charging and discharging power and the state of charge (SOC) of the corresponding energy storage system, and therefore the safety of the energy storage systems is improved while distributed generated power fluctuation can be smoothed and the bus voltage quality can be improved; when the energy storage systems of all the sub micro grids cannot effectively buffer the system power supply and demand, an energy storage power station needs to be connected to control stabilization of the bus voltage. According to the energy storage optimization and coordination control method for the direct-current micro grid group, the virtual impedance of droop controllers of all energy storage units in the energy storage power station is adjusted by adopting fuzzy control to achieve automatic distribution of the power among the different energy storage units and SOC balance, fuzzy input is segmented, the SOC balancing speed of the fuzzy input in different ranges is increased by adopting fuzzy control, bus voltage drop caused by droop control is compensated by adopting a bus voltage feedback control method, and the bus voltage quality is improved.

Description

technical field [0001] The invention relates to a design technology of a micro-grid coordination controller, in particular to a DC micro-grid group energy storage optimization and coordination control method. Background technique [0002] As an autonomous system with self-control and self-energy management, microgrid can work in both grid-connected mode and off-grid mode (Wang Chengshan, Wu Zhen, Li Peng. Research on key technologies of microgrid[J]. Electrotechnical Technology Journal, 2014, 29(2):1-12). like figure 1 It is the structure diagram of the microgrid system. Compared with the AC microgrid, the DC microgrid formed by establishing a DC transmission line in the microgrid and connecting various distributed power sources and energy storage systems can improve the utilization rate of the converter and reduce losses. It is conducive to the complementary advantages and coordinated control among micro-sources (Wang Yi, Zhang Lirong, Li Heming, etc. Voltage layered coor...

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Problems solved by technology

Literature (Zhou Niancheng, Jin Ming, Wang Qianggang, et al. Multi-microgrid system hierarchical coordination control strategy with series and parallel structure [J]. Electric Power System Automation, 2013, 37(12): 13-18) proposed a multi-microgrid system The tie-line power and grid-connected synchronous coordinated control strategy can reduce the amplitude difference, frequency difference and phase difference of the voltage on both sides of the closing switch to the synchronization range. Microgrid system operation control still needs to be studied

However, few existing researches involve the coordinated control of multiple sub-microgrid systems in different operating states, which is crucial for the normal operation of multi-sub-microgrid systems and efficient and reliable power supply for loads (Liang Che, MohammadShahidehpour.DC Microgrids : Economic Operation and Enhancement of Resilience by Hierarchical Control. IEEE Trans. on Smart Grid, 2014, 5(5): 2517-2526)

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