Control method for micro-grid hybrid energy storage system

Abstract

The invention relates to a control method for a micro-grid hybrid energy storage system. The control method comprises the following steps: selecting inductive current i L (lower coordinate) and capacitor voltage u c (lower coordinate) as state variables, and energy storage unit voltage u i (lower coordinate) and load current i Load (lower coordinate) as input variables for a buck / boost power converter in the micro-grid hybrid energy storage system; building a small signal model of buck / boost power converter based on PWM (Pulse-Width Modulation) complementary control; respectively designing control circuits for a storage battery and a super capacitor; controlling the charging and discharging of the storage battery and stabilize low-frequency component of synthetic load through a single current loop; stabilizing the difference between the synthetic load power and storage battery power through the upper capacitor; adding power feed-forward to the voltage-current double closed-loop control so as to inhibit the fluctuation of the voltage of a DC bus. According to the control method for the micro-grid hybrid energy storage system, each load power in a micro-grid is taken into full account, a plurality of control methods are carried out to stabilize the high-frequency fluctuation of power, thus the fluctuation of the voltage of the DC voltage is inhibited, and the stability of the voltage of the DC bus in working is maintained.

Description

technical field [0001] The invention relates to a control method for a microgrid, in particular to a control method for a hybrid energy storage system of a microgrid. Background technique [0002] In order to ensure the stability of microgrid operation and maintain real-time power supply balance, it is necessary to control the hybrid energy storage system reasonably. Microgrid power distribution as figure 1 shown. The energy storage units (battery and supercapacitor) in the system are connected to the DC bus through a buck / boost power converter to realize bidirectional flow of power. [0003] At present, research on the control strategy of microgrid energy storage system has been carried out at home and abroad. Chen Yizhe proposed an active control strategy for the microgrid energy storage system based on short-term load forecasting. Considering the battery capacity and the limit of charge and discharge times, according to the load forecast results, the charge and dischar...

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Problems solved by technology

[0004] The present invention is aimed at the problem of real-time power balance and voltage stability of the independently operated micro-grid, and proposes a micro-grid hybrid energy storage system control method. Based on the complementary PWM small-signal model, control circuits are designed for the battery and the supercapacitor, and the battery The low-frequency fluctuation of power is well stabilized by using a single current loop, and the supercapacitor adopts a double-loop control with feedforward to stabilize the high-frequency fluctuation of power and effectively maintain the stability of the DC bus voltage

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