Optimal operation for district cooling systems coupled with ice storage units based on the per-unit value form

The integration of non-dispatchable renewable resources into the power system, as part of efforts to mitigate carbon emissions and achieve carbon neutrality, presents a significant problem in maintaining the balance between generation and consumption within multi-energy complementary systems. The widespread adoption of district cooling systems (DCS) with ice storage units has proven to be a highly effective approach for enhancing flexibility by changing the operating schedule or adopting different control strategies to participate in demand response, reducing load peaks or peaking and filling to improve system economy. However, the nonlinearity and the presence of multiple variables with different orders of magnitude of the DCS model pose a significant challenge for arithmetic operations well. The present study establishes models based on per-unit value for DCS coupled with ice storage units, and employes several objective functions to validate the selection of base values, demonstrating the superiority of the calculation process for per-unit value model. Simulation results show that, the adoption of per-unit value models of DCS significantly reduce the calculation time, particularly for large systems where it would be possible to have a reduction in time-consuming by more than 68%. Additionally, this paper suggests an operational strategy for real DCS that incorporates demand response by per-unit value models, demonstrating the efficacy of the proposed approach in achieving a reduction of 11.17% in operating costs, while simultaneously enhancing flexibility to meet the load demands of multi-energy complementary systems.