Optimal Voltage Control of PJM Smart Transmission Grid: Study, Implementation, and Evaluation

PJM Interconnection operates the largest synchronized transmission system in North America, where one of the great challenges is being able to meet the system-wide voltage control performance requirements both pre- and post-contingency. Based on a characteristic analysis of the contingencies distribution, a practical method using an iteration scheme between the optimal power flow (OPF) and a contingency assessment (CA) is proposed to develop a control strategy, so that the calculated optimal voltage schedule solutions are better not only for pre-contingency system conditions, also for the post-contingency (N-1) system conditions. At step T, a CA considering all contingencies is carried out and those that may lead to the maximized voltage violations are saved as active contingencies for step T+1. At the same time, another CA, considering only the current active contingencies, is computed in parallel using a trial OPF result as input. According to the post-contingency indices, the new voltage constraints will be compressed and the final OPF is called again to calculate the optimal strategies. The detailed architecture of the PJM optimal voltage control (OVC) system is presented in this paper. The system has completed four-months of online operation, and the results have been evaluated using third-party software. It has been proven that the OVC system presented here will greatly improve both the pre- and post-contingency performance. The PJM OVC is a typical application of a smart transmission grid. Phase III of this study is currently under way.