A dual-threshold judgment switch circuit for microgrid anti-backflow device

Abstract

The invention discloses a dual-threshold judgment switching circuit for a micro grid backflow protection device. The dual-threshold judgment switching circuit comprises a first voltage comparison module, a second voltage comparison module, a third voltage comparison module, a current sensor, an energy storage device and a direct current bus. The first voltage comparison module works in a two-way selection switching mode, and the second voltage comparison module and the third voltage comparison module work in a one-way comparison switching mode. The second voltage comparison module and the third voltage comparison module are connected in parallel and then connected with the first voltage comparison module in series, so that a switching circuit body is formed. The energy storage device, the current sensor and the switching circuit body are sequentially connected in series and then connected with the direct current bus, and a voltage signal output by the current sensor is transmitted to the first voltage comparison module. According to the dual-threshold judgment switching circuit, when a micro grid generates reverse power, the energy storage device is connected to the switching circuit to consume the reverse power, and the energy storage device is switched off after the reverse power is eliminated, so that renewable energy power generation is utilized to the maximum degree and meanwhile repeated switching-on and switching-off of the energy storage device is avoided.

Description

technical field [0001] The invention relates to the field of electrical engineering, in particular to a dual-threshold judging switch circuit used in a microgrid anti-backflow device. Background technique [0002] At present, energy conservation and emission reduction, and green distributed energy have become the focus of attention all over the world. However, distributed power sources such as photovoltaics have the characteristics of intermittent, random, slow response, and small inertia. After grid connection, they are prone to voltage fluctuations and flicker, especially when large-capacity distributed power sources are integrated into medium and low voltage distribution networks. , it is difficult to realize the power balance of the distribution network and ensure the reliability and quality of power supply. In order to reduce the impact and negative impact of large-scale distributed power grid connection on the external public grid, the integration of distributed power...

AI Technical Summary

Problems solved by technology

[0004] First, the harmonics generated by a large number of power electronic devices in the microgrid have an impact on the power quality of the public grid

[0005] Second, when the public power grid fails, the reverse power generated by the microgrid will cause damage to the machinery and equipment, and even endanger the personal safety of maintenance personnel

[0006] Third, due to the power supply characteristics of the microgrid, the characteristics of single power supply, radiation type, and unidirectional power flow of the public grid have been changed, so that the existing current protection measures are no longer applicable

[0008] First, this technology eliminates reverse power by limiting the output of distributed power sources or even cutting off distributed power sources, and does not make full use of the energy storage system in the microgrid, resulting in waste of renewable energy

[0009] Second, the switching action determination of this technology is a traditional single-threshold determination. Due to the fluctuation of photovoltaic power supply, in some cases, it may lead to repeated switching of reverse power protection devices, which shortens the service life of the device and affects the microgrid. Stability of operation

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