Distributed energy storage SOC control and integration method in AC microgrid island mode

Abstract

The invention relates to the technical field of electrical engineering, and aims to provide a distributed energy storage SOC control and integration method in an AC microgrid island mode. This method can rationally distribute the output power of multiple energy storages in the network by designing a decentralized control method combined with droop control. The control process does not require a central controller, which saves the cost of communication cables and eliminates the adverse effects caused by communication delays. The energy storage will jointly support the voltage and frequency of the busbar, realizing the plug-and-play function of multi-energy storage and real-time cut-out function. By monitoring the output power of the DC side of the energy storage, the real-time change of the SOC value of the energy storage state of charge can be calculated, and the inverter frequency offset based on the SOC variable droop control can be introduced to achieve faster balance of SOC between multiple energy storages and effectively improve the overall energy storage work efficiency. By integrating the SOC state of the energy storage under this control method, the voltage frequency change model and the voltage amplitude change model of the network area are established, so that the energy storage can reasonably regulate the active and reactive power output by other micro sources in the network.

Description

technical field [0001] The invention relates to the technical field of electrical engineering, and more specifically, to a distributed energy storage SOC control and integration method in an AC microgrid island mode. Background technique [0002] With the increasing development of society, the construction of micro-grids that generate electricity from renewable energy such as wind power, hydropower, and photovoltaics has become an important strategy for the development of new energy in countries around the world. A large number of micro-grid demonstration projects have been built around the world, and micro-grid construction will be an important direction for the future development of power grids. AC micro-grid is a micro-grid form in which micro-power sources, energy conversion devices, energy storage devices and loads are all connected to the AC busbar. It can effectively integrate the relationship between source-storage-load, and there is little modification to the tradit...

AI Technical Summary

Problems solved by technology

[0003] The support control of traditional energy storage in the AC microgrid island mode is generally host-type control. This control emphasizes that a single energy storage adopts the V / F control mode to support the bus voltage and frequency. It is necessary to quickly respond to voltage and frequency fluctuations in the grid. Make suppression adjustments, which have high requirements for the power capacity of a single energy storage and external power regulation capabilities, and once the energy storage fails, the system will be difficult to continue to operate

At the same time, in the current distributed control or centralized control, it is often necessary to consider the delay of communication information, which is not conducive to the realization of plug-and-play energy storage and disconnection at any time.

In addition, when there are multiple energy storage systems operating at the same time in the grid, there is often an imbalance in the SOC state among multiple energy storage units, which can easily lead to overcharging and overdischarging of the energy storage, resulting in low overall energy storage efficiency and shortened service life.

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