CQR: a hybrid expert system for security assessment

An offline prototype, called CQR, of a system for online security assessment has been built and tested in conjunction with a western Pennsylvania utility. CQR is a hybrid of rule-based programs written in OPS5 and numerical tools written in FORTRAN. CQR uses the utility´s full power system model, accepts arbitrary operating conditions, evaluates the base case, evaluates a small number of AC contingency list using distribution factors, selects and evaluates a small number of AC contingencies, makes an explicit assessment of power system security, and presents results to the operator in a compact and understandable report. Security is decomposed into components that are evaluated independently, allowing separate criteria to be applied to the base case and contingencies. Transient stability is dealt with through dynamically imposed operating limits. CQR´s strong points are the correctness, consistency, and compactness of its reports. Run times are acceptable for real time operation