Energy Manager Design for Microgrids

On-site energy production, known as distributed energy resources (DER), offers consumers many benefits, such as bill savings and predictability, improved system efficiency, improved reliability, control over power quality, and in many cases, greener electricity. Additionally, DER systems can benefit electric utilities by reducing congestion on the grid, reducing the need for new generation and transmission capacity, and offering ancillary services such as voltage support and emergency demand response. Work within the CERTS DER team at the Ernest Orlando Lawrence Berkeley National Laboratory has led to development of software tools for microgrid design and operation. The DER Customer Adoption Model (DER-CAM) chooses economically optimal sets of DER devices to install for a given site. Additionally, the Site Energy Supply and Use Model (SESU) simulates operation of an installed microgrid and can be used as a testing ground for proposed EM strategies. These tools are of immediate use for assessing potential microgrids and to assist in the development of an EM. The authors expect microgrids to be installed in large numbers within a decade and the control approach embedded in them may endure for the foreseeable future. To demonstrate how these tools can aid in microgrid development, examples provided in this report introduce some of the concepts of the EM and microgrid design, and they illustrate some issues that arise. The optimal constrained economic dispatch decision from an EM may be made over many discontinuous sets of options and may depend on past, present, and future conditions, suggesting overwhelming computation and data requirements. Therefore, the central question that must be addressed becomes what EM setup can deliver exactly the cost effective level of control; that is, one that meets all basic requirements and to which no added capability or data access adds a net energy bill savings, after the costs of implementation and operation are deducted.