Distributed Secondary Voltage and Frequency Control for Islanded Microgrids With Uncertain Communication Links

Abstract

Abstract-This paper presents a robust distributed secondary control (DSC) scheme for inverter-based microgrids (MGs) in a distribution sparse network with uncertain communication links. By using the iterative learning mechanics, two discrete-time DSC controllers are designed, which enable all distributed energy resources (DERs) in a MG to achieve the voltage/frequency restoration and active power sharing accuracy, respectively. In special, the secondary control inputs are merely updated at the end of each round of iteration, and thus each DER only needs to share information with its neighbors intermittently in a lowbandwidth communication manner. This way, the communication costs are greatly reduced, and some sufficient conditions on the system stability and robustness to the uncertainties are also derived by using the tools of Lyapunov stability theory, algebraic graph theory, and matrix inequality theory. The proposed controllers are implemented on local DERs, and thus no central controller is required. Moreover, the desired control objective can also be guaranteed even if all DERs are subject to internal uncertainties and external noises including initial voltage and/or frequency resetting errors and measurement disturbances, which then improves the system reliability and robustness. The effectiveness of the proposed DSC scheme is verified by the simulation of an islanded MG in MATLAB/SimPowerSystems.

A Novel Distributed Secondary Coordination Control Approach for Islanded Microgrids

“…A finite-time frequency and active power control strategy is proposed to ensure the frequency regulation and active power sharing accuracy within a finite time, which enables the voltage and reactive power control to be achieved in a slow time scale. Compared with the asymptotic convergence schemes [21], [39], [40], this approach can reduce the inherent frequency and voltage coupling in case of non-uniform line impedances to some extent, then the voltage and reactive power control strategy can be designed separately.…”

“…2. An observer-based voltage controller involving reactive power constraints is designed to regulate the weighted average voltage of all DGs to their reference and thus, the issue of accurate reactive power sharing in case of strongly nonuniform line impedances can be addressed, which is different from the schemes [22]- [24], [40] that did not consider voltage regulation and/or reactive power sharing.…”

MAS-Based Distributed Coordinated Control and Optimization in Microgrid and Microgrid Clusters: A Comprehensive Overview

“…In order to describe the switching characteristics of the topologies in MAS, the graph theory is widely adopted to represent the communication topologies [115,116], and the communication links among agents are bidirectional and weighted in a graph model [117]. Meanwhile, the Algebraic Riccati Equation (ARE) based on the graph theory is used to analyze the characteristics of the time-varying effects in the MAS [118,119].…”

“…In addition, if one microgrid plugs in or plug out from the microgrid clusters, the topology and structure of the system will be inevitably different. Due to the access of DG system, the study of the switching characteristics for the communication topologies in MAS is a critical problem to be solved [115][116][117][118][119][120][121].…”

A Hybrid Constraints Handling Strategy for Multiconstrained Multiobjective Optimization Problem of Microgrid Economical/Environmental Dispatch

“…Therefore, the forecast load demands and the predicted environmental data should be obtained first. Besides, the structure and the operation mode of the MG may also change [26,27] according to the operators' requirement, which would cause the change in the optimization models. So the optimization objectives and constraints should also be updated before applying the optimization algorithm.…”