New Family of Microgrid Control and Management Strategies in Smart Distribution Grids—Analysis, Comparison and Testing

Abstract

This paper presents a new family of universal control and management strategies for microgrids in smart distribution grids. The paper also provides a general and computationally-efficient framework for modeling and analysis of power management strategies in a microgrid with multiple-distributed generation (DG) units which eases microgrid dynamic studies and controller parameters selection in large microgrids with multiple DG units. Three different approaches for real and reactive power management are proposed. The controllers offer the following advantages: 1) the proposed topologies can be applied to both voltage-controlled (VC) and current controlled (CC) voltage source converters (VSCs). 2) The controllers are universal and realize requirements of both grid-connected and islanded modes, i.e., they share real and reactive power during islanding with constant frequency operation and act as grid supporting VSCs in the grid connected mode. 3) The drooping variables can be either power or current, thus VC-power drooping, VC-current drooping and CC-power drooping are different available variants. 4) The concept of hybrid polar-vector control is developed in this paper. Thus, it can combine the benefits of both types of controllers in one augmented strategy. 5) The controller emulates the behavior of conventional synchronous generators (SGs) which in turn results in better integration of electronically-interfaced DG units into the power system and prevents instabilities due to interaction of fast response DGs and SGs. 6) The controllers realize seamless and robust transition to the islanding mode. The controllers are developed under new concept of synchronous converters. A theoretical analysis and simulation results show that the proposed controllers yield the aforementioned requirements in one compact structure.