Structured Optimization for Parameter Selection of Frequency-Watt Grid Support Functions for Wide-Area Damping

Deployment of distributed renewable energy resources is increasing rapidly, which is leading to growing concerns over the impact of distributed power electronics energy converters on grid stability. In general, power electronic coupled systems do not provide frequency or voltage support through feedback compensation. This is leading to changes in utility interconnection requirements for distributed generation systems to provide voltage and frequency regulation ability through the use of newly developed advanced grid functions (AGFs). In this paper, the types of grid stability problems which can be mitigated by AGFs is expanded; in particular, it is demonstrated that the energy storage function which adjusts active power injection
as a function of grid frequency, i.e., P(f) or freq-watt, can provide damping control using local frequency information. Specifically, a structured optimization scheme is presented that is scalable to multi-node distributed damping applications. An algorithm computes optimal damping controller gains for distributed resources that use only local frequency feedback. The local control may be implemented using the freq-watt AGF recently defined by the International Electrotechnical Commission (IEC). The proposed approach is applicable to local and inter-area oscillation damping and could be valuable for utility operations centers to identify appropriate gains for installed systems that implement AGFs.