Development and evaluation of a power management system for an off-grid power system with PV generation and energy storage

Abstract

Utilization of locally available solar energy resources alongside energy storage has emerged as a feasible renewable retrofit to the solely diesel generation-based remote off-grid power systems. The declining cost and improving reliability of photovoltaic (PV) systems, battery energy storage systems (BESS), and power electronics components have contributed to accelerate this trend. The integration of inverter-interfaced Distributed Energy Resources (DERs) such as solar PV systems and BESS along with conventional generation resources significantly increases the complexity of these isolated power grids. Therefore, a hierarchical control system consisting of an energy management system, a power management system and the local controllers of generating and storage resources is often employed to achieve a reliable, secure, and stable power system operation. This thesis develops a real-time simulation model of an isolated power system based on the typical configuration of power systems in remote communities of Northern-Canada. The isolated grid includes a diesel generation plant, a PV system and a BESS with the diesel generators forming the grid under normal operation. Control strategies for the PV system and the BESS under both grid-following and grid-forming modes of operation are discussed. This thesis develops a secondary control layer of a hierarchical microgrid control system to perform power management functions and implements them on a digital automation controller. In order to demonstrate the functionality of the proposed microgrid controller, a Controller Hardware in the Loop (CHIL) simulation testbed is developed. The structure of the testbed, the development and coordination of different levels in the hierarchical control system, and the integration of the IEC-61850 communication for information exchange among various components are discussed. The overall study confirms the effectiveness of the proposed hierarchical controller as well as the applicability of the developed testbed in providing a realistic operation evaluation platform.