Seamless Transition in Grid-connected Microgrid System using Proportional Resonant Controller

Abstract

In this paper, the design of an inverter control structure based on the Proportional Resonant (PR) controller is dealt with in detail for attaining smooth transitions between the operating modes of a gridconnected microgrid system. The control strategy applied for the inverter is cascaded three-loop control viz., the grid current, voltage across the load, and the inverter output current loops. The inverter control is mainly focused to retain the voltage magnitude within the prescribed set limits and to have a good quality of the voltage across the load under all the modes of operation. A proportional resonant controller is designed by considering the transients and stability criteria into account under varying modes of operation. The design procedure of the Proportional resonant controller is given in detail. The threephase grid-connected microgrid system considered under study is simulated in MATLAB/Simulink environment to operate under islanding condition as well as grid-connected condition and also changing modes from islanding to grid connected and vice versa. The simulation results are presented under various modes of operation to validate the controller design for a smooth transition between the modes of operation.

An Improved Hierarchical Control Structure for Robust Microgrid Operation and Seamless Mode Transfer under Linear and Nonlinear Loads conditions

“…The other reason for MG and power system transitions is load type. There are different load types in power system such as linear [10][11][12][13], nonlinear [2,8,9], balanced [2,11], unbalanced [3,14] loads. Two adaptive and smart controllers are planned to regulate the MG frequency and voltage accurately in IM [10].…”

“…As the power network and microgrids are regularly under linear and balanced load conditions and consequently without any harmonic distortion, to make restoration and synchronization in such system. The only positive sequence of fundamental components were reported in literature [10][11][12][13][14]. A master-slave controller type was proposed by Imran et al [15].…”

A New Consensus-based Distributed Adaptive Control for Islanded Microgrids

“…In grid-connected mode, the main grid directly control the frequency and voltage (f & V) of MG, whereas, in islanded mode, all DGs are responsible to maintain these quantities within pre-specified limits [2,3]. Proper control of microgrid is a prerequisite for stable and economically efficient operation [4,5]. To maximize the use of resources and improve the effectiveness of DGs, a modern control approach is required to increase the microgrid reliability and to provide global stability for the system [6,7].…”