Pricing Short-Circuit Current via a Primal-Dual Formulation for Preserving Integrality Constraints
This addresses the problem of optimizing SCC procurement for power system operators as synchronous generators are replaced, offering a more effective pricing method than existing approaches, though it appears incremental in nature.
The paper tackles the challenge of pricing Short-Circuit Current (SCC) services in power systems due to integrality constraints in Unit Commitment, proposing a primal-dual formulation that preserves binary variables and results in adequate, intuitive prices without uplift payments, as demonstrated on a modified IEEE 30-bus system.
Synchronous Generators (SGs) currently provide important levels of Short-Circuit Current (SCC), a critical ancillary service that ensures line protections trip during short-circuit faults. Given the ongoing replacement of SGs by power-electronics-based generation, which have a hard limit for current injection, it has become relevant to optimize the procurement of SCC provided by remaining SGs. Pricing this service is however challenging due to the integrality constraints in Unit Commitment (UC). Existing methods, e.g., dispatchable pricing and restricted pricing, attempt to address this issue but exhibit limitations in handling binary variables, resulting in SCC prices that either fail to cover the operating costs of units or lack interpretability. To overcome these pitfalls, we adopt a primal-dual formulation of the SCC-constrained dispatch that preserves the binary UC while effectively computing shadow prices of SCC services. Using a modified IEEE 30-bus system, a comparison is carried out between the proposed approach and the previously developed pricing schemes. It demonstrates that, under the proposed pricing method, adequate and intuitive service prices can be computed without the need for uplift payments, an advantage that cannot be achieved by other pricing approaches.