Improved droop control based microgrid auxiliary master-slave control method

Abstract

The invention relates to an improved droop control based microgrid auxiliary master-slave control method. The method is used for maintaining stability of the voltage and power of the microgrid. The microgrid comprises multiple DGs connected with alternating current buses respectively; each DG comprises a master-control DG, an auxiliary DG and a slave-control DG; the master-control DG and the slave-control DG are used as a master-control unit and a slave-control unit in the master-slave control method respectively; the inverter in the auxiliary DG adopts voltage and current dual-loop control; a load current io is multiplied by a dynamic virtual impedance Zvir, and the obtained product is used as an instruction voltage to be added in a feedback signal to a voltage loop, so that the output impedance of the inverter is sensitive. Compared with the prior art, the inverter of the auxiliary DG adopts the dynamic virtual impedance, so that matching between the output impedance of the inverter and the circuit impedance can be ensured, voltage drop can be effectively relieved, and the power quality is ensured; and in addition, the improved droop control is adopted, and an integral link is introduced in the reactive power control link, so that steady state voltage without static errors is realized, and the steady state performance of the system is improved.

Description

Technical field [0001] The invention relates to a coordinated control method for a microgrid, in particular to an auxiliary master-slave control method for a microgrid based on improved droop control. Background technique [0002] With the rapid development of the national economy, energy and environmental issues have become increasingly prominent, and the microgrid technology based on renewable energy has emerged as the times require. The proposal of the microgrid concept helps to improve the utilization and flexibility of distributed power sources (DG). How to control the coordinated control of multiple distributed power sources in the microgrid and smoothly switch between grid-connected / islanding modes is an urgent problem to be solved. [0003] Microgrid control modes are mainly divided into peer-to-peer control, hierarchical control, and master-slave control. The peer-to-peer control strategy considers that the internal power supply status of the microgrid is equal, and “plug...

AI Technical Summary

Problems solved by technology

[0004] Droop control (droop) technology draws on the idea of ​​parallel control of synchronous generators, which can realize the peer-to-peer parallel connection of multiple inverters, and can automatically distribute the active and reactive power of DG, but the classic droop control has limitations for power distribution.

Due to the uncertainty of the line impedance of the microgrid and the output impedance of the inverter, the inverter cannot achieve output power coupling, and the droop characteristics need to be different according to the inductive, resistive, and capacitive properties of the line. In addition, as a droop control The power control loop of the outer loop structure of the system also plays an important role in the stable control of the system frequency, etc., but the power control is essentially a differential regulation, and a large load change in the island will cause a deviation of the frequency, etc., and it is necessary to ensure the droop characteristics and regulation rapidity

Images