DC micro-grid system and variable droop coefficient control method thereof

Abstract

The invention discloses a DC micro-grid system and a variable droop coefficient control method thereof. The DC micro-grid system comprises three converter units, two resistive loads, a TMS320F28335 controller and its accessory circuit. The variable droop coefficient control method, compared with the conventional droop control, incorporates voltage recovery control and droop coefficient correctioncontrol. The method performs voltage compensation control on the output voltage minimum value, achieves a control objective that the converter output voltage minimum value is the same as a set reference value, and solves the large deviation of the conventional droop control DC bus voltage and the set voltage reference value. The method fixes the droop coefficient of one converter, and obtains thedroop coefficient compensation terms of the remaining converters by the droop coefficient correction control. The droop coefficient reference value is superimposed onto the droop coefficient compensation terms so as to form a corrected droop coefficient. Then the droop control is performed, thereby achieving a control objective that the converters equally distribute the load current under the condition that the line resistances have a large difference, and solving the problem that the shunt accuracy decreases when the line resistances of the converters are inconsistent.

Description

Technical field [0001] The invention belongs to the field of DC microgrid control of electric power system, and relates to an improved droop control method, in particular to a variable droop coefficient control method based on output voltage compensation control and droop coefficient correction control and a microgrid controlled by the method system. Background technique [0002] With the integration of a large number of renewable energy sources, the concept of microgrid was proposed. Microgrids can be divided into AC microgrids and DC microgrids. Compared with the AC microgrid, the DC microgrid has attracted more and more attention due to its lower control complexity, higher reliability and higher energy transmission efficiency. A key issue in the DC microgrid is how to coordinate and control the DC converters, so as to realize the load current equally or proportionally. The current distribution strategies proposed at present mainly include average current control, master-sla...

AI Technical Summary

Problems solved by technology

However, when using this method, the output voltage of the DC converter with the smallest line resistance in the DC microgrid will be lower than the set reference value

[0005] Some of the above methods have unsatisfactory shunt accuracy when there is a large difference in converter line resistance, some methods have unsatisfactory control effects when the load changes rapidly, and some methods are too complicated to be suitable for a large number of converters

Images