【目的】随着我国全国统一电力市场建设的不断加快，我国已在省间电力现货市场建设上取得一定成效。为应对多时空市场下多主体的竞争、支撑电网企业省间现货购电，首先通过分析省级电网参与省间现货市场的购电机制以及路径组合情况，提出了电网企业省间现货购电决策框架。【方法】在该框架下，对购电相关数据进行了预处理，并通过构建上层为电网企业购电决策、下层为省间现货市场交易的双层优化模型，对多电网企业参与的两级电力市场购电决策进行协同；然后通过强对偶原理和KKT（Karush-Kuhn-Tucker）条件将所构建的双层优化模型转化为单层优化问题，并对其进行线性化处理求解电网企业购电策略。【结果】最后算例分析表明，相比于传统购电方案，所提方案有助于降低综合购电成本，能够应对送端省份减少外送及购电通道容量缩减10%以内的极端情况并维持综合购电成本稳定。【结论】所提方法具有参与两级电力市场的经济性，通过提高报价能够应对一定范围内的变动情况，具有一定适用性。

[Objective] With the continuous acceleration of the construction of China’s national unified power market，significant progress has been made in the development of the inter-provincial power spot market. To cope with the competition among multiple power grids in the multi-temporal market and to support the inter-provincial spot power purchases of power grids，a decision framework has first been proposed by analyzing the purchasing mechanisms and path combinations of provincial grids participating in the inter-provincial spot market. [Methods] Under this framework，data related to power purchases were preprocessed，and a bi-level optimization model was constructed for inter-provincial spot power purchases by power grid companies. The upper level addressed power purchase decision-making，while the lower level represented inter-provincial spot market transactions. This model aimed to synergize the power purchase strategies of the two-tier power market with the participation of multiple market players. Then，the bi-level optimization model is transformed into a single-layer model through strong duality theory and the Karush-Kuhn-Tucker（KKT）condition，and is then linearized to solve the power purchase strategies for power grid companies. [Results] Finally，it is verified through case studies that，compared to traditional power purchase schemes，the proposed method helps reduce overall power purchase costs and can address extreme scenarios where sending provinces reduce power exports and power purchase channel capacities by up to 10% while still maintaining stable overall power purchase costs. [Conclusions] The proposed method makes participation in the two-tier power market economically viable for power grid companies. It can cope with extreme fluctuations within a certain range by raising the bidding price，making it applicable to a certain extent.