DC micro-grid improved multi-gradient droop control system and DC micro-grid improved multi-gradient droop control method with multi-grade bus voltage compensation

Abstract

The invention discloses a DC micro-grid improved multi-gradient droop control system and a DC micro-grid improved multi-gradient droop control method with multi-grade bus voltage compensation. For radically setting bus voltage deviation caused by a droop coefficient, load current is divided into three areas, namely a light load area, a rated load area and a heavy load area. Then improved droop control is performed on the different load areas, thereby improving current sharing performance and furthermore reducing the bus voltage deviation caused by droop. According to an improved droop control strategy, an output characteristic curve of each bus voltage control unit is different from that on the condition of a traditional constant droop output characteristic. In the rated load area and the heavy load area, not only is relatively high droop coefficient realized for overcoming a current sharing problem caused by line impedance, but also multi-grade compensation module voltage reference is added according to the load amount for reducing the micro-grid bus voltage deviation, and therefore a problem of contradiction between current sharing and the voltage deviation caused by droop control can be radically controlled.

Description

technical field [0001] The invention relates to the technical field of power output balance of micro-source converters in a DC micro-grid and improvement of system bus voltage adjustment rate design, in particular to a system current sharing and bus voltage deviation control method when multiple micro-source bus control units operate in parallel. Background technique [0002] With the development of new energy and people's increasing awareness of energy conservation and emission reduction, power system energy is moving towards green and sustainable development. As an important component of smart grid, microgrid is an effective form to realize the integration and utilization of distributed energy. The influence of reactive power and frequency is not considered in the DC microgrid system, which improves the efficiency and power supply quality of the system. Its main control goal is to obtain a lower bus voltage regulation rate and power sharing of each distributed power suppl...

AI Technical Summary

Problems solved by technology

[0007] Aiming at the contradictory relationship between improving the current sharing performance and improving the bus voltage adjustment rate in the traditional droop control, the present invention provides an improved multi-slope droop control method with multi-level bus voltage compensation DC microgrid; the present invention especially considers that the line impedance is large , it is necessary to increase the droop coefficient to improve the current sharing performance, which will lead to the problem of large bus voltage deviation. Therefore, according to the load, the load current is divided into light load area, rated load area and heavy load area, respectively in the heavy load area Increase the system reference voltage in the rated load area and the rated load area, focus on improving the current sharing performance and the bus voltage deviation of the rated load area and the heavy load area system, and reduce the pressure of the secondary control in the layered control; and the light load in the load area of ​​the present invention zone, rated load zone and heavy load zone can be flexibly allocated to achieve theoretically optimal configuration and design

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