Reduced and Aggregated Distribution Grid Representations Approximated by Polyhedral Sets
For power system operators, this provides a computationally efficient way to represent distribution grid flexibility in transmission-distribution coordination.
The paper presents a tractable method using polyhedral sets to compute reduced PQ capability areas for distribution grids, enabling efficient TSO-DSO interaction. Compared to OPF-based methods, it significantly reduces computational complexity with reasonable approximation errors, especially for low voltage grids.
In this paper we present a novel tractable method to compute reduced and aggregated distribution grid representations that provide an interface in the form of active and reactive power (PQ) capability areas for improving transmission service operator - distribution service operator (TSO-DSO) interactions. Based on a lossless linear power flow approximation we derive polyhedral sets to determine a reduced PQ operating region capturing all voltage magnitude and branch power flow constraints of the entire distribution grid. To demonstrate the usefulness of our method, we compare the capability area obtained from the polyhedral approximation with an area generated by multiple optimal power flow (OPF) solutions for different distribution grids. While the approximation errors are reasonable, especially for low voltage (LV) grids, the computational complexity to compute the PQ capability area can be significantly reduced with our proposed method.