A microgrid hybrid energy storage system and its control method

Abstract

The invention relates to a microgrid hybrid energy storage system and a control method thereof. The system comprises a power grid, wherein the power grid is connected with a microgrid common ac bus, the microgrid common ac bus is connected with a first subcircuit bus and a second subcircuit bus through microgrid energy management systems respectively, and the microgrid common ac bus is also connected with the first subcircuit bus through a transformer TM4; the microgrid common ac bus is also connected with the first subcircuit bus through a transformer TM5; the first subcircuit bus is connected with a lithium battery energy storage module, a super-capacitor energy storage module and a lead-acid cell energy storage module; the second subcircuit bus is connected with a load module. A microgrid internal energy storage system and loads are predicted, internal energy storage devices and loads are optimized and controlled during grid-connected operation, isolated network operation and state switching of a microgrid according to an energy storage power source and load characteristics, system output is smooth, and then intermittency and volatility of renewable energy sources are effectively inhibited.

Description

technical field [0001] The invention relates to the field of hybrid energy storage, in particular to a microgrid hybrid energy storage system and a control method thereof. Background technique [0002] The operation of distributed power in the microgrid system is mainly random and intermittent. When the harmonic content is large or the power fluctuation exceeds the load constraint range, it will cause damage to the corresponding sensitive load and even cause the microgrid system to collapse. [0003] The Chinese invention patent with application number 201310704335.7 "A Hybrid Energy Storage System Applied to Microgrid" has the following technical problems when the microgrid is transferred to the island operation mode: [0004] First, due to the fast charging and discharging speed of the supercapacitor, it cannot continuously support the power fluctuation in the network; [0005] Second, when the isolated grid is running, the VF operation of the battery is used to establish...

AI Technical Summary

Problems solved by technology

[0004] First, due to the fast charging and discharging speed of the supercapacitor, it cannot continuously support the power fluctuation in the network;

[0005] Second, when the isolated grid is running, the VF operation of the battery is used to establish the power supply in the microgrid, and at the same time stabilize the low-frequency active and reactive power in the grid. This requires high performance for the battery and the corresponding bidirectional converter. The accuracy of the algorithm is high. When there are power quality problems such as voltage swell, sag, unbalance and harmonics in the large power grid or planned maintenance, the battery will not be able to quickly establish a power supply and provide voltage and frequency support;

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