Hybrid energy storage system and energy management method thereof in micro-grid

Abstract

The present invention relates to a hybrid energy storage system and an energy management method thereof in a micro-grid. The system comprises a lithium iron phosphate energy storage system equipped with a lithium iron phosphate storage battery, a bidirectional energy storage AC / DC, and a super capacitor energy storage system equipped with a super capacitor, and is characterized by comprising a bidirectional energy storage DC / DC of which one side is connected with the super capacitor, and the other side is connected with a DC bus distribution line, wherein the DC bus distribution line is connected with one side of the bidirectional energy storage AC / DC, and the other side of the bidirectional energy storage AC / DC is connected with an AC bus distribution line. An energy management system detects and judges the charge states of the energy storage units of the hybrid energy storage system separately and real-timely, adjusts and controls the energy flow directions and amplitudes of the energy storage units of the hybrid energy storage system separately and real-timely, gives full play to the function that the super capacitor compensates the fluctuation of a power grid rapidly, satisfies the seamless switching and island transient operation requirements, keeps the uninterrupted power supply, enables the power supply reliability to be improved substantially, and realizes the operation benefit and cost optimization of the micro-grid.

Description

technical field [0001] The invention relates to a microgrid, in particular to a hybrid energy storage system and its energy management method in the microgrid. Background technique [0002] Microgrid is an organizational form of distributed power generation. It consists of distributed power sources, energy storage devices, energy conversion devices, related loads, monitoring systems, and protection devices to form a small power generation and distribution system, which can realize self-control, protection and management. , it can be connected to the external power grid for steady-state operation, or it can be operated in isolation. The output power of distributed power generation units such as wind power and solar photovoltaic in the microgrid is intermittent and random, and the change of load is also random, which has a negative impact on the stable operation of the microgrid. However, with the large-scale development of renewable energy distributed power generation system...

AI Technical Summary

Problems solved by technology

During frequent high-power charge and discharge and deep discharge, temperature rise and active materials on the positive and negative plates will fall off, resulting in cumulative loss of battery capacity and rapid decline in a short period of time, seriously affecting the service life of the battery , and the normal and stable operation of the microgrid

In addition, the existing first lithium iron phosphate energy storage system with a lithium iron phosphate battery on the DC side and its bidirectional energy storage AC / DC converter (Alternate Current / Direct Current converter, abbreviated as AC / DC) In a hybrid energy storage system consisting of an energy storage unit and a second energy storage unit including a DC-side supercapacitor energy storage system with a supercapacitor, the lithium iron phosphate battery and the supercapacitor are directly connected to the DC bus power distribution line, and then Two-way energy storage AC / DC is connected, and the two-way energy storage AC / DC is connected to the AC bus distribution line. This topology cannot give full play to the function of supercapacitors to quickly compensate for grid fluctuations.

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