A Novel Framework of Communication-Free Coordinated Voltage and Frequency Control for Islanded Microgrid

  • Hebatallah Ibrahim

Student thesis: Master's Thesis

Abstract

The increasing concerns on the environment, growing population and insufficiency in natural resources induced the use of renewable energy resources (RESs). As a result, the integration of RES generation units into the distribution networks close to the loads has been increasing lately as a corresponding infrastructure to the traditional central power plants to reduce the dependence on fossil fuels. A microgrid (MG) is viewed as a group of RES generation units that can potentially operate in two modes; either grid connected or isolated. Hence, a group of RES generation units connected to a distribution feeder and operated based on Energy Management System (EMS) and can be disconnected by circuit breaker is considered as a MG. The islanded MG is a very weak grid, which is very sensitive to the intermittency of RES generation units, voltage and frequency variations that can easily result in system instability. Therefore, the coordination among the MG components to achieve stable operation has been deployed based on centralized coordinated voltage and frequency sophisticated controllers using high bandwidth communication infrastructure resulted in burden on cost and reliability as plug and play MG concept. In the view of the aforementioned challenges, this thesis introduced a novel framework of coordinated voltage and frequency control methodology designed for Islanded MG relies on a communication-free control approach. The control strategy is developed to manage the active and reactive power flow and transient response in adherence to IEEE standards (1547 and 927) and enhancing the system stability and reliability. Thus, the distributed controllers of the MG components have been utilized based on their slow, medium and fast dynamic responses to maintain the voltage and frequency within the acceptable operating boundaries in steady state, dynamic and transient operation based on well-defined states of operation. In each state, the roles of each device for voltage and frequency regulations are defined with its regulation capability and response time. Consequently, the fast dynamic reactive power reserve and rapid frequency regulation are obtained at all operating conditions resulted in improving the transient response, system stability and reliability. The comprehensive simulation studies have verified the superior performance of the communication-free coordinated voltage and frequency controllers in steady state, dynamic and transient operation of the islanded MG.
Date of Award2014
Original languageAmerican English
SupervisorMohamed El Moursi (Supervisor)

Keywords

  • Frequency control; Microgrid (MG); Renewable Energy Resources.

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