Hierarchical Control for Effective Power Management and to Improve Voltage Regulation in DC Multi-Microgrid System

In the past few years, the DC microgrid has become popular and preferable due to the advancement in controlled operation of converters and DC loads. This leads to multiple DC microgrids and their combined operation. In this paper, a hierarchical control method is proposed to achieve effective power management among multiple DC microgrids. It also improves the bus voltage regulation of the system. Every microgrid consists of renewable energy sources (RESs), energy storage system (ESS) and loads. The proposed control scheme operates in coordination with local controller of individual microgrid. It achieves power sharing among various microgrids based on power availability and local load demand. The local controller for microgrid mitigates the disturbance locally. The combined operation along with communicated signals achieves the effective power management. The proposed control technique is tested under diversified operating condition in real time simulator.

I. Introduction

In the past few years, due to high efficiency, high power density, high flexibility, and simple control, the implementation of DC microgrid has increased exponentially [1]. Moreover, the DC microgrid allows the integration of resources such as solar photovoltaic (PV), fuel cells, battery storage, etc. without converting it to AC. In addition, the development of DC technology has led to the development of DC loads. The efficient converters designing, system voltage control, power flow control with sharing between sources, energy management, etc. [2]–[3] are the major issues in DC microgrid. The available source power in every renewable energy source (RES) is an important feature need to be considered for the effective power management in microgrid. The challenges in the control of microgrid arises from uncertainties in RESs such as, solar PV and wind due to intermittent power generation, uncertainties in load demands and schedules. This leads to combined operation of multiple DC microgrids and its effective power management [4].