재생에너지 출력제어 환경에서 CHP-HP-TES 통합 운영의 유연성 및 경제성 분석

Abstract

With the rapid expansion of renewable energy in Korea, the curtailment caused by grid limitations has become a challenge, and the heating sector remains heavily dependent on fossil fuels. This study proposes a sector-coupling strategy involving combined heat and power (CHP), heat pump (HP), and thermal energy storage (TES) technologies as a practical way to address these issues, and quantifies the flexibility and fuel-cost savings associated with this strategy. A mixed-integer linear programming model with two-stage lexicographic optimization was developed with 540 scenarios, considering various HP capacities, renewable capacities, grid-hosting ratios, and LNG prices. HP technology is limited to consuming only surplus renewable electricity, ensuring that the system operates solely on internally available renewable electricity. The results show that adopting an HP at 10 MW reduces curtailment by up to 96.3% and fuel costs by 42.7% at an LNG price of 75,000 KRW/Gcal. HP-TES integration decouples CHP from thermal demand, with a correlation of between 0.772 and 0.430, thereby expanding the flexibility range from 6.73 to 8.07 MW. Furthermore, 63% of HP energy absorption at 10 MW is enabled solely by TES, confirming TES's role as a prerequisite for large-scale HP operation, rather than as an auxiliary component. Payback periods of 0.78–1.43 years indicate the economic viability of HP across all capacities.