Modeling and Simulation of a Distributed Generation-Integrated Intelligent Microgrid
Dr. Saifur Rahman | Virginia Tech - Advanced Research Institute
The electric power system supports the continuous operation of military installations, including mission-critical facilities, at both the component and systems levels. A reliable, efficient, and secure power system is necessary for the operation of critical buildings within a base as well as for the operation of the base as a whole. The same requirement is true for deployed forces in forward operating bases, which must be put into service quickly and reliably. Distributed and autonomous subsets of larger electric power grids, known as microgrids, can increase the security and reliability of electricity supply for such facilities, provided they are capable of intelligently networking and controlling a variety of local distributed energy resources (DER), particularly renewable energy resources.
The objective of this SERDP proof-of-concept project was to model and simulate a specialized microgrid called an Intelligent Distributed Autonomous Power System (IDAPS) to evaluate opportunities for power consumption or load control and the dispatch of DERs. The intent was to determine the capability of IDAPS for integrating renewable energy technologies and thus minimizing reliance on energy sources external to a military installation.
An IDAPS microgrid consists of hardware as well as software systems. Researchers developed models of IDAPS physical components using the SimPowerSystems toolbox in the Matlab/Simulink environment. IDAPS hardware components included distribution circuits, DERs (solar photovoltaic modules, wind turbine generators, microturbines, fuel cells, and battery storage), and power loads. They also developed local control algorithms to control each DER and load. The research team then developed an IDAPS energy management system (EMS) based on a multi-agent technology that included decision criteria during normal operation as well as during outages. This was followed by the development and demonstration of Internet protocol (IP)-based communication interfaces between IDAPS hardware and the EMS. Upon completion of this design work, the research team simulated several scenarios and evaluated the IDAPS microgrid in both parallel and islanded operations (i.e., disconnected from the main power grid), using data from a small local electric utility to ensure that proper IEEE interconnection standards were observed.
The simulation results demonstrated that the proposed IDAPS microgrid could include a variety of DER sources, including renewable energy sources such as solar photovoltaics, wind turbines, microturbines, fuel cells, and battery storage technologies, to be integrated into the network in an efficient manner. This project achieved its objective by illustrating that the IDAPS microgrid could: (1) successfully manage electricity demand during normal operating conditions; (2) island the microgrid off of the main grid once an upstream fault or interruption in power supply is detected; (3) secure critical loads and shed non-critical loads according to the installation’s priority list during emergencies; and (4) resynchronize the microgrid to the main grid after an upstream fault is cleared. Several technical challenges were addressed by this work, including analyzing the dynamic response of agent-based control strategies, defining the multi-agent system’s role and definition, and evaluating the on- and off-grid operation of a microgrid with renewable distributed generation systems.
Implementation of an IDAPS microgrid in a mission-critical facility optimizes the operation of internal power generation and demand loads during normal conditions and increases the security of energy supply to critical loads by shedding noncritical loads during emergencies. The IDAPS control agents have an embedded intelligence that works in collaboration with local controllers to coordinate both DERs and loads to achieve any mission-based environmental, operational, and economic performance criteria. This approach will help remove certain barriers in the interconnection and control of DER units in a microgrid environment. As a result, the IDAPS model will facilitate the use of cleaner and more efficient DER, including renewable energy technologies, microturbines, fuel cells, storage devices, and plug-in hybrid electric vehicles, thus enhancing energy security and reliability for the mission-critical components of military bases. In a follow-on SERDP project ( EW-1710), the research team is extending the modeling and simulation development based on this work to explore the feasibility of the development of microgrids in a campus-type facility.