Load Dispatch Optimization using Dynamic Rating and Optimal Lifetime Utilization of Transformers

Power transformers are critical power system components that are generally loaded conservatively, resulting in marginal utilization of their designed lifetime. Dynamic Transformer Rating (DTR) allows increased utilization of this asset by limiting its Hot Spot Temperature (HST) instead of the per unit load, thereby increasing available network capacity.

However, residual lifetime would still be unutilized according to current dimensioning criteria and state-of-the-art lifetime aging models. Therefore, this paper proposes a novel methodology for DTR which assesses thermal aging based on HST history and allows optimal lifetime utilization by loading the transformer beyond its continuous HST limit.

The proposed methodology is tested in the day-ahead market using a multi-period DCOPF formulation that accounts for power losses while preserving convexity. The IEEE RTS 24-bus network with additional wind generation is used as a test system using actual weather, load and generation data from Denmark for the period 2014-2016.

The proposed DTR approach favours the integration of wind power generation and decreases the cost of load dispatch. This novel DTR approach can be beneficial for applications with limited asset lifetime like offshore windfarms or for postponing necessary grid reinforcements for short period of time.