Microgrids are small-scale power systems that, to a large degree, have the same challenges as utility systems when it comes to achieving their operational objectives. In my previous blog post, I covered generation scheduling or generation adequacy, in the near real-time and real-time periods. Today, I will focus on the importance of resource scheduling and dispatch control in a microgrid.
 
Generally, microgrids provide four key operational benefits, both to their native customers and other external systems. These benefits include:

• Improving reliability through a highly available electric supply
• Increasing resiliency through their ability to absorb disruptive events and recover rapidly from them.
• Maximizing efficiency and optimizing economic benefits
• Minimizing environmental impacts

To achieve these operational objectives, microgrid resources need to be scheduled in real-time and near real-time and dispatched in real-time using one of the following diverse optimization strategies:

• Cost and Environmental Impact: In this optimization strategy, resources are scheduled and dispatched to minimize the operational cost of a microgrid. These resources include microturbines, solar, wind, storage systems, and dispatchable loads, as well as purchases from the utility. Under this strategy, resources can be optimized considering their environmental impact, cost, or a combination of the two.

• Utility Program Optimization: In this strategy, a microgrid can expose itself as a resource in a utility program, such as Demand Response (DR). The microgrid can act as a Virtual Power Plant (VPP) and can respond to control signals for changing its generation within maximum and minimum limits. Once the program is called by the utility, the microgrid must fulfill the required amount of generation change.

• Electricity Market Participation: In this optimization strategy, the microgrid exposes itself as a VPP, participating in an electricity market by offering energy, Ancillary Services (AS), or both, within the maximum and minimum VPP operating limits. The external entity (market operator) will call on the energy and AS required, and the microgrid will respond appropriately. The AS may include conventional reserves (regulation, spinning reserve, and non-spinning/supplemental reserves) and emerging grid services (such as flexible ramping/load following and Primary Frequency Response (PFR)). 

To achieve some of the transactive strategies described above, microgrids need a sophisticated controller to deal with forecasting, microgrid optimization, scheduling, and dispatch of conventional resources as well as Distributed Energy Resources (DERs). The microgrid controller needs to collaborate with a Distributed Energy Resource Management System (DERMS) to facilitate participation in utility programs and electricity markets.

About the Author:
Dr. Ebrahim Vaahedi is Associate Vice President of Smart Grid Software Development at OATI. Dr. Vaahedi has more than 30 years of experience in different segments of the energy industry, specializing in the development and execution of technology strategies for utility industry. Dr. Vaahedi joined OATI following his prior position with a major Canadian utility as Chief Technology Officer, where he was accountable for developing and executing a consolidated technology plan, including the delivery of a $140 million Control Center project. Dr. Vaahedi is the author of a recent book on modern power system operation, titled “Practical Power System Operation.” Dr. Vaahedi earned his B.S. in Electrical Engineering from the Sharif University of Technology in Tehran and went on to earn his M.S. in Power Systems and Electrical Machines and Ph.D. in Optimal Control of Power from the Imperial College of Science and Technology in London.