Direct-current microgrid power and voltage regulation method considering line impedance and local load

Abstract

The invention relates to a direct-current microgrid power and voltage regulation method considering line impedance and a local load. The method is used for an island operation mode of the direct-current microgrid. A plurality of groups of DGs and different types of loads are contained in the direct-current microgrid. Theh DGs are connected in parallel to a common DC bus through the corresponding converter. According to the method, an improved droop control strategy is adopted, so that each DG distributes load power according to the rated capacity of the DG, the influence of line impedance andlocal load on power distribution is eliminated, and the voltage stability of the bus is maintained. Compared with the prior art, the island direct-current microgrid power distribution control and voltage recovery control strategy provided by the invention can effectively improve the load power distribution precision among multiple parallel distributed power supplies in the island direct-current microgrid, improves the efficiency of the distributed power supplies, and gives full play to the plug-and-play characteristic of the DG. And meanwhile, the DC bus voltage is maintained, so that the microgrid system can stably operate.

Description

technical field [0001] The invention relates to a coordinated output power control and bus voltage stabilization of a DC microgrid connected in parallel to a common DC bus, in particular to a DC microgrid power and voltage regulation method considering line impedance and local load. Background technique [0002] Considering the current environmental pollution and the shortage of fossil fuels, distributed power generation technology based on renewable energy sources (RES) has been proposed and widely used. Connecting distributed generation (DG) to the distribution network in the form of a microgrid is generally considered to be one of the effective ways to utilize distributed generation. Traditionally, microgrids are divided into DC microgrids and AC microgrids according to the type of access bus. Compared with the AC microgrid, the DC microgrid has no problems such as phase and reactive power, which makes the voltage distribution independent of the inductance and capacitanc...

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Problems solved by technology

The literature "Yang Jie, Jin Xinmin, Wu Xuezhi, et al. An improved current load distribution control strategy for DC microgrid [J]. Chinese Journal of Electrical Engineering, 2016, 36(1): 59-67" proposed a A droop control strategy that uses the voltage change rate instead of the voltage to realize the precise distribution of the load current, but there is still a large deviation in the bus voltage

The literature "Jiang Weiming, Zhao Jinbin, Gao Mingming, et al. Research on the control strategy of independent DC microgrid with voltage self-recovery characteristics [J]. Grid Technology, 2019.1315: 1-9" obtains line impedance information through the method of single pulse injection, and It is introduced into the droop coefficient in the form of negative compensation to suppress the adverse effects of line impedance inconsistency on current distribution, but this strategy has high requirements for the selection of measurement interval time after pulse injection

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