introduction
The purpose of this analysis is to validate the long-term thermal viability of operating the facility under the proposed 8,760-hour dispatch model. The Project main step-up transformer, manufactured by Virginia Transformer (VTC), possesses specific thermodynamic design features that actively protect the transformer core from excessive heat during short periods during nameplate overloading in Imperial County. Specifically, this report demonstrates that pushing the 50.0 MVA nameplate transformer to a peak of 53.5 MVA (1.07 per-unit load) over a continuous 3-hour evening window during extreme summer conditions (49.0°C / 120.2°F peak ambience) does not cause any critical thermal degradation or catastrophic damage. As proven by the dynamic thermal modeling detailed below, this operational profile remains 100% compliant with “IEEE C57.91” continuous Normal Life and ANSI, IEC 60076-7-2018 guidelines.
This case study examines a 50 MW AC solar and energy storage project located in Imperial County, California. By simulating the project’s optimized annual dispatch, ZGlobal analyzed the resulting transformer loading, internal oil temperatures, and the overall impact on equipment lifespan. Because the facility is scheduled to dispatch at levels exceeding the transformer’s 50.0 MVA nameplate rating during specific evening hours, initial assessments might suggest the unit is undersized. However, our analysis demonstrates that the 50.0 MVA rating is fully adequate to handle these peak loads, provided a 55°C temperature rise liquid-filled transformer is utilized.