Direct Methods to Estimate the Most Limiting Voltage Level and Thermal Violations in Coordinates of Power Transfers on Critical Transmission Paths

Power system operational nomograms calculated in near-real-time will be more accurate, less conservative and adaptive to changing system conditions compared to the traditionally used pre-calculated nomograms (e.g., seasonal nomograms). In the near-real-time process of exploring multi-dimensional nomograms in coordinates of meaningful power system parameters (such as transmission path flows), multiple stress directions (loading patterns) should be explored for multiple contingencies. Thermal and voltage violations (TVs and VVs) must be taken into account along with the voltage and transient stability limits. Usually, the TV and VV limits are explored by applying a step-by-step iterative searching procedure helping to locate the exact position of the most limiting violation along each stress direction for the most severe in each contingency being studied. In the near-real-time implementation, the search time for all these limits must be heavily optimized. This paper presents a direct method (DM) to locate the most limiting violation for varying stress directions and multiple contingencies. The method has been tested on the full 2014 Western Interconnection planning model. The test results are provided in the paper.