Secondary control of voltage & current unbalance in a multi-bus microgrid using cooperative adjustment of Q⁻droop gains

Abstract

This paper describes a combined current and voltage unbalance compensation scheme for static power converters on a multi-bus microgrid utilizing cooperative regulation on a sparse ad-hoc communication network. The proposed control scheme is both robust to changing network conditions and corrects for sub-optimal gain settings at each distributed generation unit. The scheme is based on local voltage and current measurements by each distributed generation unit on the network, and utilizes a primary and secondary control hierarchy. The scheme is then simulated using Matlab SimPowerSystem to demonstrate operation of the compensation scheme and evaluate its performance.

On the Secondary Control Architectures of AC Microgrids: An Overview

“…Control Method References CSC Centralized [30]- [47] DISC Averaging [14], [48]- [56] Consensus [57]- [121] Event-triggered [122]-[134] DESC Washout-filter based [135]- [138] Local measurement based [139]- [145] State-estimation / observer based [146]- [152] characteristics of a synchronous generator [7]. However, nondroop methods have also been introduced as alternatives [8]- [11].…”

Unbalance mitigation strategies in microgrids

“…The objective of the unbalance compensation or mitigation depends upon the conditions of the MG and the operating mode (islanded or grid‐connected). Unbalance mitigation in islanded MGs [18, 21, 22, 23, 25, 27–32, …”

“…The NS conductance versus NS reactive power (G versus Q) droop with a NS current controller and adaptive VI is discussed in [41], which achieves minimised circulating current. The virtual conductance is drooped over the NS reactive power along with an ad hoc communication network in [42]. A new droop control for four‐leg inverters using voltage angle control for per‐phase real power‐sharing in the unbalanced condition is discussed in [43].…”