Toward A Framework for Sustainable Cyber-Physical Energy Systems: Frequency Regulation Revisited

Abstract

AbstractIn this paper we propose a possible framework for sustainable cyber-physical energy systems. Given any physical ecological system and its social governance which defines its objectives, the two combined represent a Socio-Ecological System (SES). Motivated by the general SES framework for sustainability proposed by a recent Nobel Prize winner Elinor Ostrom, we define a Socio-Ecological Energy System (SEES) framework first, its core variables and second-order variables whose characteristics can be used to assess the likelyhood of an SEES being sustainable. We then propose that such system can be greatly shaped by directly embedding cyber into its core variables, resources, governance and users. However, due to vast spatial dispersion of core variables and their poor mobility, it is not possible to align the second-order variables within an SEES without engineering a network system, both physical and cyber. This leads to introducing the taxonomy of deeper-order variables and interaction variables relevant for modeling the physical system. The objectives of cyber system design are to use sensing, communications, computing and control to coordinate the physical interactions variables to best align temporal and spatial characteristics of the core variables. Examples of several qualitatively different SEES architectures are shown in support of the main conjecture in this paper that not all architectures need the same cyber. Cyber, as everything else, must be designed with clear objectives. Recent trends toward smart grids are discussed using the proposed taxonomy. Simple examples are shown to illustrate the type of sensing and observation required by the controllers to ensure pre-defined performance. The inter-dependencies between the complexity of observation and control, on one side, and the performance are illustrated in light of frequency regulation for qualitatively different power grid architectures.