Coordinated control for distributed generation in microgrids

• Main Author: Xu, Xin
• Other Authors: Tang Yi
• Format: Thesis-Master by Coursework
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Electrical and electronic engineering
• Online Access: https://hdl.handle.net/10356/150436
• Institution: Nanyang Technological University

Distributed generation system based on microgrid technology is an essential approach to develop renewable energy, improve the reliability of the power supply and expand the supply capacity of the power system. The power supply of distributed grid can be formed by a variety of energy resources through power transformation, and these power supply units are decentralized and are connected to the grid. The power supply unit of the microgrid based on distributed generation is generally the power supply with power electronic converters. The power converter is the core of the whole distributed generation system, which is responsible for converting distributed energy into electric power and realizing the grid-connection of the distributed generator. This thesis analyzes the distributed generation system with the characteristics of the converter, introduces the concept of virtual synchronous machine, and establishes the control strategy of power electronic converter based on droop characteristics. This strategy has significant characteristics in improving the stability of the microgrid and realizes the smooth transition in the network structure or state transition process of the microgrid. The thesis studies the virtual synchronous machine, the characteristics and controls of the grid-feeding converter, and grid-forming converter, and elaborates the control schemes of the system coordinated control strategy. The phase-locked loop parameters, three-phase grid-feeding converter controller, and three-phase grid-forming converter controller are specifically designed. The mathematical model of the control strategy of the microgrid distributed generation system based on droop characteristics is established, and the controller parameters are analyzed and designed. Finally, the PLECS simulation model of the microgrid control system based on distributed generators is established, and the simulation is carried out for verification. The results show that the coordinated control strategy proposed in the thesis has good performances on both the dynamic and steady states of the system.