Toward Sensing, Communications and Control Architectures for Frequency Regulation in Systems with Highly Variable Resources

Abstract

The basic objective of this chapter is to rethink frequency regulation in electric power systems as a problem of cyber system design for a particular class of complex dynamical systems. It is suggested that the measurements, communications, and control architectures must be designed with a clear understanding of the temporal and spatial characteristics of the power grid as well as of its generation and load dynamics. The problem of Automatic Generation Control (AGC) and frequency regulation design lends itself well to supporting this somewhat general observation because its current implementation draws on unique structures and assumptions common to model aggregation in typical large-scale dynamic network systems. We describe how these assumptions are changing as a result of both organizational and technological industry changes. We propose the interactions variable-based modeling framework necessary for deriving models, which relax conventional assumptions when that is needed. Using this framework, we show that the measurements, communications, and control architectures key to ensuring acceptable frequency response depend on the types of disturbances, the electrical characteristics of the interconnected system and the desired technical and economic performance. The simulations illustrate several qualitatively different electric energy systems. This approach is by and large motivated by today’s AGC and its measurement, communications and control architectures. It is with this in mind that we refer to our interactions variable-based frequency regulation framework as “enhanced AGC” (E-AGC). The enhancements come from accounting for temporal and spatial characteristics of the system which require a more advanced frequency regulation design than the one presently in place. Our proposed interactions variable-based aggregation modeling could form the basis for a coordination of interactions between the smart balancing authorities (SBAs) responsible for frequency regulation in the changing industry. Given the rapid deployment of synchrophasors, the proposed E-AGC can be easily implemented.