An Optimal Secondary Multi-Bus Voltage and Reactive Power Sharing Control Based on Non-Iterative Decoupled Linearized Power Flow for Islanded Microgrids

Abstract

The subject of optimal secondary control of power-electronic-interfaced distributed energy resources (DERs) in droop-controlled microgrids has garnered significant research attention in recent years. While the feasibility of optimal secondary control based on non-linear power flow has been proven, the power flow algorithm is essentially iterative in nature. This work proposes an optimal secondary control with non-iterative power flow to regulate multi-bus voltages and DERs' reactive powers. The control scheme incorporates a modified Decoupled Linearized Power Flow that is known to be superior in terms of reactive power and bus voltage magnitude estimation, as compared to classical DC power flow, into a constrained quadratic programming. Q-V droop is integrated into the linear power flow in place of the slack bus. The proposed optimal scheme is provably accurate for maintaining reactive power sharing while regulating multiple load-bus voltages. The additional degrees of freedom enabled by the weighting factors significantly improve the control flexibility of the secondary controller. The allowable bus voltages and DER kVar capacity limits have also been considered by the control algorithm. The work is proven through an accurate co-simulation study comprising an 18-bus network and a full primary control models in PowerFactory, interfaced through industrial communication tool MatrikonOPC.INDEX TERMS Microgrid, droop control, reactive power sharing, voltage regulation, optimal secondary control, decoupled linearized power flow.

In-Line Distributed Dispatch of Active and Reactive Power Based on ADMM and Consensus Considering Battery Degradation in Microgrids

“…Additionally, voltage magnitude and angle are not absolutely decoupled. These variables are related by quadratic functions that make the classical PF nonlinear, complex, and low-efficient [34]. In order to formulate an optimization problem considering a complete PF model, we use a linear PF with decoupled variables, high accuracy, and computational efficiency.…”

“…This relaxation allows the problem to integrate the PF in the constraints of the optimization, mantaining the desirable relationship between voltages and active and reactive power flows. In addition, this model can be used in radial, and meshed distribution systems conserving the accuracy and improving computation efficiency [34].…”

Performance Enhancement of an Islanded Microgrid with the Support of Electrical Vehicle and STATCOM Systems

“…Various strategies have been used to increase MG stability. The major methods are focused on enhancing control strategies of shading load control concepts and reactive power compensation techniques [25][26][27]. When the larger generator is lost, a backup energy storage supply is inserted for the load shading process.…”