Economic Modeling of the Energy Management System for a Battery-solar Building-integrated Microgrid: A Comparison Between Lead-acid and Lithium Ion Battery Systems

Open Access
Author:
Udegbe, Egbadon Ajibola
Graduate Program:
Energy and Mineral Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
July 17, 2014
Committee Members:
  • Seth Adam Blumsack, Thesis Advisor
  • Mort D Webster, Thesis Advisor
  • Dr David Riley, Thesis Advisor
Keywords:
  • microgrid
  • solar
  • energy management system
  • backup power
  • smart grid
  • grid stability
  • frequency regulation
  • peak-shaving
Abstract:
The present-day commercial building sector is characterized by high expenditure on electricity as a source of energy, and an accompanying increase in greenhouse gas emissions. Moreover, traditional backup infrastructure aimed at promoting power quality and surety for business operations fail to maximize cost and operational efficiency, while offering limited ancillary benefits related to revenue generation, environmental footprint, and grid stability. These challenges have the potential to be addressed through the integration of grid-interactive storage and solar photovoltaic (PV) on-site generation with the building electrical systems. This research focuses on modeling the energy management system (EMS) for a commercial building microgrid capable of performing peak-shaving and providing backup reserve power, while participating in the PJM frequency regulation market. This has been achieved by defining the operational framework and control strategy for the EMS, by utilizing system data and information from the ongoing Building 7R microgrid development at the GridSTAR Center in the Philadelphia Navy Yard. Based on these, a MATLAB model has been developed to simulate annual energy transfers between the building, the local utility and PJM. Using the EMS model simulation results, a methodology has been developed to assess the economical tradeoffs between various operational modes, and also technological choice between lithium-ion and lead-acid batteries. These have been analyzed by considering market revenues and backup cost mitigation provided by the building-integrated microgrid. Within the proposed framework, it has been determined that lead-acid systems provide more peak-shaving revenues and building demand curtailment, while a comparable lithium-ion system yields more annual revenues. Overall, allocation of battery capacity away from frequency regulation operation has been observed to reduce total revenues, under all conditions.