Formal specifications for an electrical power grid system stability and reliability

Abstract

This thesis provides natural language requirements and associated formal specifications for an electric power grid. These specifications are the first step in using bounded constraint solving to detect early bleak states in an electric power grid system. We analyze several methods of software verification and validation including Theorem Proving, Model Checking, and Execution-based Model Checking before determining that Execution-based Model Checking is the most suitable for specifying properties of a power grid. The requirements and specifications are broken into four categories: undesirable events, downward trends, failure to recover, and undesirable fluctuations. All specifications are focused on system stability and reliability as indicated by system frequency and operating in a secure N-1 state. Specifications from three out of the four categories were tested to ensure they meet the spirit and letter of the natural language requirements while eliminating ambiguity inherent to natural languages. Finally, we show how a Hidden Markov Model can be used to perform run-time monitoring in the presence of hidden states, thereby enabling run-time monitoring of systems where monitored artifacts are not all perfectly visible.