A Coordinated Control Method for Island DC Microgrid

Abstract

The invention discloses a coordination control method of an isolated island DC micro grid. The method comprises the following steps: aiming at the isolated island DC micro grid composed of a renewable energy power generation unit, an accumulator energy storage unit, and an AC / DC load unit, firstly performing charging / discharging control on an accumulator so as to enable the DC bus voltage to change along the accumulator SOC according to segmented drooping characteristics; and then realizing the autonomous running of the renewable energy power generation unit and the AC / DC load unit by taking the DC bus voltage as a coordination signal; enabling the renewable energy power generation unit to run in reduced power when the SOC approaches the upper limit to cause the boosting of the DC bus voltage; and enabling the load unit to run in load shedding when the SOC approaches the lower limit to cause the stepping down of the DC bus voltage. By use of the coordination control signal disclosed by the invention, the accumulator SOC is used for controlling the DC bus voltage and the DC bus voltage is used as the coordination signal between the micro sources in a power grid, the autonomous running of each micro source is realized; the deep charging / discharging of the accumulator is avoided by reducing the power of the renewable energy power generation unit or shedding the load of the load unit when the SOC approaches to the limit value.

Description

technical field [0001] The invention relates to a method for controlling an island DC micro-grid, which can realize the autonomous operation of each micro-source in the grid and avoid deep charging and discharging of a storage battery during operation, and belongs to the field of control technology. Background technique [0002] The island DC microgrid needs to introduce energy storage link to cope with the intermittent, unpredictability of wind power, photovoltaic and other renewable energy generation and the fluctuation of load demand. The energy storage link is the power and voltage support of the island DC microgrid. Compared with emerging energy storage technologies such as supercapacitor energy storage and flywheel energy storage, battery energy storage has the advantages of mature technology, high reliability, low cost, and suitable for large-scale energy storage. Therefore, batteries have become the energy storage link of island DC microgrids. first choice. [0003]...

AI Technical Summary

Problems solved by technology

However, this method relies heavily on communication, and the loss of the mode switching signal will cause the battery to fail to enter the standby or standby state, so that the deep charge and discharge of the battery cannot be avoided.

At present, droop control is generally used in microgrids to realize the autonomous and coordinated operation of each micro-source, but the SOC of the battery is rarely considered in this kind of decentralized control strategy, which seriously affects the control effect.

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