Improved control method for multi-energy storage independent DC microgrid considering unmatched line resistance

Abstract

The invention relates to an improved control method for a multi-energy storage independent DC microgrid of considering mismatched line resistance for achieving SOC balancing of various battery energystorage units in the microgrid. The improved control method is characterized by comprising the following steps of (1) adding multiple groups of battery energy storage units which are connected in parallel and are equal in capacity to a DC bus in a DC microgrid structure; (2) building an improved droop control model for the multi-energy storage independent DC microgrid of considering the mismatchedline resistance; and (3) feeding differences between an ESOC average value and an output current average value in a current sampling period and current ESOC values and output current values of the battery energy storage units into a sampling holder separately according to the improved droop control model and then modifying a reference voltage offset in real time according to the output result ofthe sampling holder, thereby achieving SOC balancing of the battery energy storage units. Compared with the prior art, the improved control method has the advantages of considering the mismatched lineresistance and avoiding over-charging and over-discharging.

Description

technical field [0001] The invention relates to the technical field of optimization strategy design for microgrid droop control, in particular to an improved control method for a multi-energy storage independent DC microgrid considering mismatched line resistance. Background technique [0002] With the aggravation of energy and environmental problems worldwide, microgrids have received extensive attention from scholars from all over the world. DC microgrid does not consider the problems existing in AC microgrid such as reactive power, harmonic current, DC / AC conversion loss, etc., so the research on DC microgrid is gradually increasing. Due to the intermittent and random characteristics of distributed generation (DistributedGeneration, DG) output power, its security and reliability are weak. Therefore, a battery energy storage system (BESS) composed of a battery energy storage unit (BESU) needs to be added to ensure the power balance of the microgrid. [0003] When multipl...

AI Technical Summary

Problems solved by technology

However, the influence of line impedance on current load distribution cannot be completely eliminated, and the control parameter k D needs to be large enough, which is bound to cause a certain degree of bus voltage drop

Images