Electric power transmission systems are large electrical networks spread over a vast geographic area that deliver electricity produced by thermal and hydro-electric generators to the wide variety of customer loads distributed along the network. Because these systems are so large and dispersed, it is extremely difficult to know how the system is behaving at any moment in time. In spite of extensive metering and powerful computers, the best we can do is estimate the state of the power system. Since certain electrical laws must be obeyed that constrain and govern its behavior, and we are seeking the best estimate given an abundance of telemetered measurements, we can write the State Estimation problem as a very large optimization problem that seeks to determine the most likely electrical state of the network given the data available. Current power system State Estimators solve a simplified optimization problem that ignores certain aspects of a real utility's practice. For example, common system devices such as transformer taps, phase shifters, or series capacitors are either treated as fixed variables or are heuristically accommodated in the optimization process. Physically discrete variables and inequality constraints imposed by physical or operational limits are ignored. Current solution methods are based on first derivative information and ignore the important effects of second derivatives which can have a profound impact on computational robustness. These shortcomings have resulted in an industry-wide dissatisfaction with the current state- of-the-art, in spite of significant gains in computational speed made by algorithmic research and faster computers. We propose to construct a State Estimation model that directly includes essential characteristics that are now ignored, with the premise that a more accurate and robust model is of greater concern than a faster solution method. A software prototype for numerical experimentation is proposed, which will also serve as a benchmark debugger for commercial software development in Phase II.
