The COVID-19 pandemic led to partial or total lockdowns in several countries during the first half of 2020, which in turn caused a depressed electricity demand. In Great Britain (GB), this low demand combined with large renewable output at times, created conditions that were not expected until renewable capacity increases to meet emissions targets in coming years. The GB system experienced periods of very high instantaneous penetration of non-synchronous renewables, compromising system stability due to the lack of inertia in the grid. In this paper, a detailed analysis of the consequences of the lockdown on the GB electricity system is provided, focusing on the ancillary services procured to guarantee stability. Ancillary-services costs increased by £200m in the months of May to July 2020 compared to the same period in 2019 (a threefold increase), highlighting the importance of ancillary services in low-carbon systems. Furthermore, a frequency-secured scheduling model is used in the present paper to showcase the future trends that GB is expected to experience, as penetration of renewables increases on the road to net-zero emissions by 2050. Several sensitivities are considered, demonstrating that the share of total operating costs represented by ancillary services could reach 35%.

2020 年上半年，COVID-19 大流行导致多个国家部分或全部封锁，进而导致电力需求低迷。在英国 (GB)，这种低需求有时与大量可再生能源输出相结合，创造了在未来几年可再生能源容量增加以达到排放目标之前无法预料的条件。GB 系统经历了非同步可再生能源瞬时渗透率非常高的时期，由于电网缺乏惯性而损害了系统稳定性。本文详细分析了封锁对英国电力系统的影响，重点是为确保稳定而采购的辅助服务。与 2019 年同期相比，2020 年 5 月至 7 月的辅助服务成本增加了 2 亿英镑（增长了三倍），强调辅助服务在低碳系统中的重要性。此外，本文还使用频率安全调度模型来展示 GB 预计将经历的未来趋势，因为可再生能源的普及率在 2050 年实现净零排放的道路上有所增加。考虑了多种敏感性，表明辅助服务占总运营成本的比例可能达到 35%。