基于二层规划的交直流混合输电网最优潮流计算

建立了交直流混合输电网等值数学模型,提出了交直流混合输电网最优潮流二层规划数学模型。该模型的上层目标函数为总燃料费用最小,变量为系统中有功与无功出力;下层目标函数为各节点电压偏移最小,变量为变压器分接头档位,上下层变量相互影响,交替迭代。采用跟踪中心轨迹内点法和萤火虫算法相结合的混合算法对该模型进行求解,上层模型利用跟踪中心轨迹内点法处理连续变量,能快速收敛至全局最优解;下层模型采用萤火虫算法求解,能较好处理离散变量。最后采用IEEE 30节点系统和IEEE 118节点系统为算例进行仿真计算,验证了该二层规划模型的有效性和正确性,对比了交流线路和直流线路功率传输方式,验证了直流系统输电的优势。

Optimal Power Flow of AC-DC Power Grid Based on Bi-Level Programming Method

This paper establishes the equivalent mathematical model of AC-DC power grid, and proposes the bi-level programming mathematical model for the optimal power flow ( OPF) of AC-DC power grid. The upper objective function of the bi-level programming model is the minimization of total fuel costs, and sets the active power and reactive power as variables;the lower objective function is the minimum voltage offset between different nodes, and sets the taps position of transformer as variables. The upper and lower variables are interactional, alternative and iterative. We adopt the hybrid algorithm including the interior point method with tracking center path and the firefly algorithm to solve this model. The interior point method is used in the upper model, which can converge to the global optimal solution in short time. At the same time the firefly algorithm is used in the lower model, which can deal with discrete variables better. Finally, the simulation results of the IEEE 30 nodes system and IEEE 118 nodes system verify the validity and correctness of the bi-level programming algorithm. Through the power transmission way comparison between AC and DC line, the advantage of DC power transmission system is verified.