Microgrid current conversion and energy storage apparatus and energy management method therefor

Abstract

The invention relates to the fields of new energy power generation and energy management thereof, specifically to a microgrid current conversion and energy storage apparatus and an energy management method therefor. The microgrid current conversion and energy storage apparatus comprises a six-switch seven-level single-phase inverter unit, a bidirectional DC/AC converter unit for a storage battery, a bidirectional DC/AC converter unit for a supercapacitor, a micro current converter energy storage apparatus control and energy management unit, a photovoltaic MPPT unit, a storage battery charging-discharging management unit, a supercapacitor charging-discharging management unit and a load management unit. By adoption of the microgrid current conversion and energy storage apparatus and the energy management method therefor, photovoltaic energy can be converted into electric energy to be connected to a power grid; power fluctuation balance of the system through peak-load shifting can be realized by the energy storage apparatus according to the energy flowing condition of the system; by adoption of the six-switch seven-level single-phase inverter, the apparatus is less in required power switching devices, low in switching loss, and high in output electric energy quality; the energy storage apparatus adopts the bidirectional DC/AC converters, so that compared with the conventional current converter, the energy storage apparatus has the advantages of less switching devices, wide voltage output range, simple SPWM modulation and the like; and therefore, the energy storage apparatus has wide application prospect in the microgrid application field.

Description

technical field [0001] The invention relates to the field of new energy power generation and its energy management, in particular to a micro-grid variable current energy storage device and its energy management method. Background technique [0002] With the strong support of national policies in recent years, more and more distributed power generation such as household photovoltaic power generation, community photovoltaic power generation, and enterprise office building photovoltaic power generation has been incorporated into the public grid. Although the use of these new energy sources is conducive to low-carbon emission reduction and increased economic benefits, they are obviously intermittent and unstable due to environmental conditions. To impact and interfere. Microgrid technology is an ideal means to solve the above contradictions. Microgrid is a small power generation and distribution system that can realize self-control and management. It usually includes distribute...

AI Technical Summary

Problems solved by technology

Most of the current low-power photovoltaic systems use non-isolated inverter structures, such as single-phase full-bridge inverters. This type of non-isolated inverter has disadvantages such as poor output common-mode voltage characteristics and high leakage current to ground. The average number is low, harmonics are injected to the grid side, and the filter device is bulky

In addition, the access of large-scale distributed photovoltaic power generation systems also brings challenges to grid energy management. Intermittent distributed power sources affect the voltage stability of local micro-grids. The role of power supply peak shaving and valley filling requires the arrangement of energy storage devices in the microgrid

Most of the energy storage devices of existing small and medium power grid-connected systems are installed on the side of the DC bus, with small capacity, multi-level energy conversion, and low efficiency. At the same time, the decentralized arrangement is not conducive to unified energy management

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