【目的】为应对高比例可再生能源接入导致的电力系统源荷波动问题，应保证多区域电网备用的合理配置与有效调用。在此背景下，提出了考虑短时线路动态增容（short-term dynamic line rating，SDLR）的多区域电网备用优化方法。【方法】首先，构建了基于机会约束的全网源荷波动场景，并通过预留区域备用容量来保障各区域的调节能力，实现全网与区域的风险协同。然后，提出了考虑SDLR和需求侧资源的日内备用优化方法，实现线路传输能力的高效利用，以保证备用有效调用。最后，以某省简化的输电网为例进行验证分析。【结果】算例结果表明，通过考虑SDLR，全网备用的实际调用比例由传统静态安全约束下的4.73%提升至20.06%，系统运行风险成本下降了58.30%。【结论】所提方法能减缓线路阻塞，降低失负荷与弃电风险，有效提升了多区域电网的供电可靠性与运行经济性。

[Objective] To address source-load fluctuations in systems with high-penetration renewable energy， the rational arrangement and effective dispatch of power reserves should be ensured. Given this background， a multi-area power grid reserve optimization method considering short-term dynamic line rating （SDLR） is proposed. [Methods] Firstly， a network-wide source-load fluctuation scenario based on chance constraints is constructed. By pre-scheduling regional reserve capacity to guarantee the regulation capability of each area， network-wide and regional risk coordination is achieved. Secondly， an intra-day reserve optimization method considering SDLR and demand-side resources is proposed to realize the efficient utilization of line transmission capacity and ensure the effectiveness of reserve dispatch. Finally， the proposed method is verified and analyzed using a simplified provincial transmission network. [Results] The result demonstrate that by integrating SDLR， the actual reserve dispatch ratio increases from 4.73% under traditional static security constraints to 20.06%， and the system operation risk cost is reduced by 58.3%. [Conclusions] The proposed method can mitigate line congestion and reduce the risks of load shedding and renewable energy curtailment， effectively improving the power supply reliability and operational economic efficiency of multi-area power grids.