A Cost Surrogate Model for TSO-DSO Coordination Based on Polynomial Chaos Expansion

An accurate aggregated flexibility cost of distribution network is essential for the coordination of transmission system operator (TSO) and distribution system operator (DSO). However, existing methods face accuracy and computational efficiency challenges in capturing the nonlinear characteristic of the aggregated flexibility cost through multi-segment linear approximation. Therefore, this letter proposes a cost surrogate model to replace the original total cost of generators, controlled loads, and other operational cost in the distribution grid, using polynomial chaos expansion (PCE). This cost surrogate model is represented as a nonlinear analytical function between the total cost and the exchange power at the interface of TSO-DSO. The accurate cost surrogate model can avoid considering the detailed model of the whole distribution network. The simulation results demonstrate the effectiveness of the proposed model.