Feedforward Control of DGs for a Self-healing Microgrid

TL;DR

This paper introduces a real-time feedforward control strategy for distributed generators in reconfigurable microgrids, enhancing their ability to quickly and proactively maintain frequency stability during network reconfiguration and load changes.

Contribution

It develops an analytical dynamic model and a small-signal analysis framework for coordinated feedforward and feedback control of DGs in self-healing microgrids, which is a novel approach.

Findings

Improved frequency regulation during load restoration.

Effective compensation for load demand variations.

Robust performance under model errors and delays.

Abstract

Network reconfiguration (NR) has recently received significant attention due to its potential to improve grid resilience by realizing self-healing microgrids (MGs). This paper proposes a new strategy for the real-time frequency regulation of a reconfigurable MG, wherein the feedforward control of synchronous and inverter-interfaced distributed generators (DGs) is achieved in coordination with the operations of sectionalizing and tie switches (SWs). This enables DGs to compensate more quickly, and preemptively, for a forthcoming variation in load demand due to NR-aided restoration. An analytical dynamic model of a reconfigurable MG is developed to analyze the MG frequency response to NR and hence determine the desired dynamics of the feedforward controllers, with the integration of feedback loops for inertial response emulation and primary and secondary frequency control. A small-signal analysis is conducted to analyze the contribution of the supplementary feedforward control to the MG frequency regulation. Simulation case studies of NR-aided load restoration are also performed. The results of the small-signal analysis and case studies confirm that the proposed strategy is effective for improving the MG frequency regulation under various conditions of load demand, model parameter errors, and communication time delays.