This study proposes an integrated energy system that combines photovoltaic power, wind power, battery storage, and ice storage to meet the electricity and cooling demands of buildings. The model for the ice storage tank incorporates the nonlinear ice-melting characteristics. An improved Multi-Objective Proximal Policy Optimization algorithm is employed for multi-objective optimization. In a case study of an office building in Shanghai, the optimization results demonstrate that the proposed method reduces daily operating costs by 6.52% and improves the CO2 emission reduction rate by 9.54%. The results demonstrate that the synergistic operation of electrical and ice storage effectively maintains supply-demand balance across different seasons. Sensitivity analysis further reveals that a 40% reduction in the unit cost of ice storage leads to a 5.7% decrease in battery capacity and a significant drop in grid dependency from 28.9% to 15.3%, highlighting the critical role of reducing ice storage costs in improving the system’s economic viability and renewable energy integration capability.
Renewable virtual power plants (VPPs) require day-ahead schedules that coordinate renewable generation, storage, gas turbines, and demand-side flexibility while retaining interpretable operating signals. This paper develops a normalized source-storage-load flexibility-loss-indicator (FLI) framework for renewable VPP scheduling. The indicators are engineering proxies for renewable-curtailment value loss, storage availability loss, and interruptible-load activation burden, rather than market-settled opportunity costs or a complete uncertainty-risk measure. The scalar objective combines net operating cost, operating coordination cost, and normalized FLI terms with reference scales fixed within each comparative setting. In a PJM-scaled day-ahead scheduling case, the baseline, scalarized multi-term reference, and proposed FLI schedules achieved net operating profits of 69,590.98 USD, 60,377.26 USD, and 66,856.81 USD. The proposed schedule reduced SOC boundary contacts from 9 to 3 and equivalent full cycles from 1.7253 to 1.6647, with a 3.93% profit concession relative to the baseline. Weight sensitivity, channel ablation, and eight representative operating and stress-test scenarios show state-dependent effects: the storage channel was active in seven scenarios, the interruptible-load channel under peak and flexibility-stressed conditions, and the renewable channel remained weak because curtailment was nearly zero. The framework provides a diagnostic coordination signal for renewable VPP operation.
