A Methodology for Unified Assessment of Physical and Geographical Dependencies of Wide Area Measurement Systems in Smart Grids

Wide Area Measurement Systems (WAMS) enable real time monitoring and control of smart grids by combining digital measurement devices, communication and control systems. As WAMS consist of various infrastructures, they imply complex dependencies among their underlying systems and components of different types, such as cyber, physical and geographical dependencies. Although several works exist in the literature that study cyber dependencies, other types of dependencies, such as geographical dependencies have not been studied. In addition, there is a lack of dependency modeling methodologies that simultaneously capture different dependency types for WAMS. The main goal of this paper is to simultaneously model the geographical and physical dependencies of WAMS infrastructures, based on simple and well defined rules. We define a probability density function to quantify the dependencies. Such a unified approach may support the design of WAMS infrastructures that are inherently more resilient to disruptions caused by different kinds of unwanted events that may affect geographically dependent WAMS components. Through simulations, we demonstrate the applicability of the proposed methodology.