A GPS-Based Control Framework for Accurate Current Sharing and Power Quality Improvement in Microgrids

Abstract

This paper proposes a novel hierarchical control strategy for improvement of load sharing and power quality in ac microgrids. This control framework is composed of a droop based controller at the primary level, and a combination of distributed power sharing and voltage conditioning schemes at the secondary level. The controllers in the primary level use GPS timing technology to synchronize the local reference angles. The voltage reference of each Distributed Generation (DG) is adjusted according to a voltage-current (V-I) droop characteristic to enable proper current and power sharing with a fast dynamic response. The droop coefficient, which acts as a virtual resistance is adaptively changed as a function of the peak current. This strategy not only simplifies the control design but also improves the current sharing accuracy at high loading conditions. The distributed power sharing scheme uses consensus protocol to ensure proportional sharing of average power. The voltage conditioning scheme produces compensation signals at fundamental and dominant harmonics to improve the voltage quality at a sensitive load bus. Experimental results are presented to validate the efficacy of the proposed method.

Analysis and implementation of virtual impedance for fixed‐frequency control strategy in microgrid

“…Large disturbance ride-through capability of GPS-based control is neglected in current literature yet is rather critical for microgrids to function robustly [11,[15][16][17]. Since frequency is fixed at nominal value and power calculation loops are excluded in V -I control method [18], dynamic responses are sped up which makes DG units even more vulnerable to disturbances like point of common coupling (PCC) voltage fluctuations or drastic load changes.…”

Improved secondary control for optimal total harmonic distortion compensation of parallel connected DGs in islanded microgrids

“…Many recent studies, mention different voltage quality limitations in different microgrid areas and have mainly focused on controlling the most sensitive load bus (SLB) of the microgrid. Golsorkhi et al [16] propose a voltage compensation scheme, which generates compensation gains at fundamental and dominant harmonics to enhance the quality of voltage at SLB.…”

“…Golsorkhi et al . [16] propose a voltage compensation scheme, which generates compensation gains at fundamental and dominant harmonics to enhance the quality of voltage at SLB.…”

Voltage quality and load sharing improvement in islanded microgrids using distributed hierarchical control

“…Furthermore, in this scheme, using the dynamic consensus algorithm, an approach has been presented for sharing the FCNS of current. In [30], an HC strategy has been presented, which consists of droop controllers at primary level and a combination of power sharing and voltage quality improving schemes in secondary levels. In this structure, the controllers in primary level use the global positioning system timing technology to coordinate local reference angles, and the consensus protocol has been used for improving power sharing.…”