A Review on Challenges and Techniques for Secondary Control of Microgrid

Abstract

Environmental concern, limited availability of fossil fuel and economic aspects have resulted in increasing interest in microgrid technology comprising of various renewable energy based distributed generators such as PV, wind, fuel cell and biomass. Microgrid provides various advantages such as higher combined heat and power efficiency, high reliability and lesser carbon emission and also reduction in technical losses. However, microgrid operation and control is associated with various challenges such as power quality issues, bidirectional power flow, voltage and frequency variations, coordinated operation of multiple distributed generators, stability, power management and economic operation. In this paper, a brief discussion on these challenges is presented. A classification of various control principles on the basis of their controller function, connection with grid and response time is also presented. The paper classifies and compares microgrid hierarchical control into three levels, i.e. primary, secondary and tertiary control. Also, a detailed discussion on various schemes of secondary centralized, decentralized and distributed control has been presented. Finally, an attempt has been made to identify research gaps in various control strategies.