Electric power systems are rapidly changing in response to a variety of goals related to reliability, resilience, and the environment. Distributed energy resources (DERs), such as distributed renewable energy sources, energy storage, and flexible loads, have a significant role to play in meeting those goals; however, we need to be careful that DERs do not cause more issues than they fix. For example, most distribution networks were not designed to accommodate high penetrations of DERs, which change power flows and can cause voltage fluctuations and current overloading. Network-safe coordination of DERs impose some form of constraint set to guarantee the safe operation of a distribution network. In this talk, I will present a comparative analysis of two distinct approaches that leverage a constraint set for network-safe coordination: nodal operating envelopes versus network-wide constraints on the action of a DER aggregator. We investigate their respective strengths and limitations by considering information and communication requirements and the resulting aggregate flexibility from the resources. The availability of potentially private information to the aggregator or to the distribution system operator determines which of the approaches is feasible. The results of the case studies suggest that if the exchange of information is not a concern and the goal is to maximize the flexibility of the DER power consumptions, a nodal constraint approach should be used. However, if equity is a concern, the network-wide approach constraining an aggregator's control input provides the best balance of fairness and flexibility.

Johanna Mathieu is an associate professor of Electrical Engineering and Computer Science at the University of Michigan, Ann Arbor. Prior to joining Michigan, she was a postdoctoral researcher at ETH Zurich, Switzerland. She received her PhD and MS from the University of California at Berkeley and her SB in Ocean Engineering from MIT in 2004. She is the recipient of an NSF CAREER Award, the Ernest and Bettine Kuh Distinguished Faculty Award, the UM Henry Russel Award, and a 2023 R&D 100 Award. Her research focuses on ways to reduce the environmental impact, cost, and inefficiency of electric power systems via new operational and control strategies. She is particularly interested in developing new methods to actively engage distributed flexible resources such as energy storage, electric loads, and distributed renewable resources in power system operation, which are especially important in power systems with high penetrations of intermittent renewable energy resources such as wind and solar.