Optimal Placement of GIC Blocking Devices Considering Transformer Thermal Limit Using Surrogate Optimization

This paper presents an approach for the optimal placement of Blocking Devices (BD) on the neutral of high voltage transformers to prevent the power system from the impacts of geomagnetically induced current (GIC) caused by geomagnetic disturbance (GMD). GIC flowing along transmission lines and through the transformers in power systems can be attributed to problems ranging from overheating of power transformers, harmonic generation, and voltage collapse due to half-cycle saturation of power transformers. To prevent the power system and its equipment from the adverse effects of GMD, blocking devices (BD) can be placed to block the GIC flow in the transformers. However, the BD placement is a complex problem, so an optimization technique is employed for BD placement using Surrogate Optimization in MATLAB that minimizes the number and costs of BDs, maintaining the hotspot temperature of transformers below the maximum limit and voltage profile of the power system above minimum permissible voltage. The results illustrate the effectiveness of the approach in the IEEE 118 bus benchmark system for different levels of GMD and show a noticeably different solution when considering transformer hotspot heating,