计及潮流约束的水火电力系统机组组合问题的分解–协调算法

A Decomposition-coordination Algorithm Applied to Hydro-thermal Unit Commitment Problems With Power Flow Constraints

针对传统机组组合研究中因模型不够完善、约束过于简化而引起的计算准确度低和系统安全性差的缺陷,建立了考虑潮流方程和水电精确出力的水火机组组合(hydrothermal unit commitment,HTUC)模型。围绕该模型,文中首先采用广义Benders分解算法将其划分为一个混合整数线性规划主问题和一个非线性规划子问题;然后将该子问题按时段进一步分解为T个规模较小的子问题,T为调度周期。其中,主问题对应于传统的水火联合调度(hydrothermal scheduling,HTS),子问题则是包含电压、无功等变量的约束潮流(constrained power flow,CPF)。主子问题之间通过可行割进行协调,并以交替迭代的方式获得原问题的解。最后对含有46台火电机组、8个梯级水电厂的IEEE 118节点系统进行计算,测试结果表明所提算法能在较少的时间内获得高质量的解,从而为大规模机组组合问题的求解提供参考。

In the traditional research, unit commitment is typically modeled in a simplified form. However, this modeling usually comes at the cost of low computational accuracy and poor system security. This work presented a refined hydro-thermal unit commitment （HTUC） model that included AC power flow constraints and an accurate expression of hydro plants to overcome the above problem. Based on generalized Benders decomposition, this paper divided the HTUC problem into a master problem and a sub-problem, and the sub-problem was decomposed into T smaller-scale sub-problems further, where T is the number of time periods. The master problem applied mixed-integer linear programming method to solve hydro-thermal scheduling while the sub-problems applied nonlinear programming method to determine constrained power flow for each time period. The master problem and the sub-problems were coordinated by feasible cuts. With alternate iterations between them, the solution of the original problem was finally obtained. In order to confirm the validity of the developed approach, a numerical test was presented on the IEEE 118-bus system with 46 thermal plants and 8 cascaded plants. The test results show that the proposed algorithm can obtain high quality solutions in a reasonable time. It provides a reference for solving large-scale unit commitment problems.