Electrical Engineering Department
PhD Thesis Defense Session
Coordinated Control Design of Distributed Generators Interface Converters and Power Quality Conditioners in Microgrids
Abstract: In recent years, distributed generators have proliferated in electrical systems. In this regard, the concept of microgrid has been newly proposed. A microgrid is a small local grid which comprises distributed resources and loads and is able to operate in grid-connected and islanded modes. Distributed generators are often interfaced to the electrical system by power-electronic converters. The main role of the interface converter is to control power injection. In the present thesis, the control of distributed generators interface converters in order to improve microgrid power quality is addressed. This way, the need for dedicated power quality conditioners such as active power filters will be alleviated. The control of interface converters is coordinated in a way that the distributed generators cooperate in compensating power quality problems and supporting loads demands in proportion with their rated powers. The proposed control structures can be classified as hierarchical (centralized) and local (decentralized) control schemes. In the hierarchical scheme, the power quality enhancement is managed by a central controller which sends proper control signals to distributed generators while in the other scheme local controllers are in charge of compensation control. Various methods are proposed to provide virtual impedance by distributed generators aiming to improve the sharing of load current components and to enhance microgrid power quality. Furthermore, the coordinated control of distributed generators converters and active filters is presented in order to provide more options for power quality compensation. The proposed approaches are applicable in both grid-connected and islanded operation modes of microgrid. Control systems design procedures are discussed in detail and simulations (using Matlab/Simulink software package) and experiments are performed in different cases to validate the proposed control approaches.
Ph.D. Candidate : Mehdi Savaghebi Firoozabadi
Supervisor : Dr. Alireza Jalilian
Advisor: Dr. Josep M. Guerrero
