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. The method comprises an outer loop control part and an inner loop control part. Through designing a distributed control method combining droop control, a plurality of energy storage output powers in a network canbe reasonably distributed. A central controller is not needed in the control process, the adverse effect caused by communication delay is eliminated while the cost of the communication cable is saved, the multiple energy storage units jointly support the bus voltage frequency, and the multi-energy-storage plug-and-play and real-time switching-out functions are achieved. By monitoring the output power of the energy storage direct current side, the real-time change of the SOC value of the energy storage charge state can be calculated, and the inversion frequency offset based on SOC variable droop control is introduced, so that the SOC among multiple energy storage can be balanced more quickly, and the overall working efficiency of energy storage can be effectively improved. By integrating the SOC state of energy storage under the control method, a network area voltage frequency change model and a voltage amplitude change model are built, and active power and reactive power output by other micro-sources in the network can be reasonably regulated and controlled through energy storage.

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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