为协调交直流电力系统的各种控制手段,减少系统的稳态运行费用,建立了交直流电力系统最优潮流计算的数学模型.模型中考虑了变压器变比（包括换流变压器变比）和并联电容器组补偿电纳的离散特性,为非线性混合整数规划模型.采用内嵌二次罚函数处理离散控制变量的非线性原对偶内点法进行求解,并讨论了迭代过程中二次罚函数的引入时机和罚因子的取值方案.对11节点和39节点2个交直流系统的计算表明,所提出的模型和算法能够可靠地收敛到系统可实施的、经济的运行方式.

In order to coordinate various control methods of AC/DC power systems and reduce the operation cost in steady state,a mathematical model is established to calculate the optimal power flow of AC/DC power systems.The proposed model,which is characterized by its nonlinear mixed integer programming considers not only the discrete characteristics of transformers（including converter transformers） ratio but also the shunt capacitor switching susceptance.The model is then solved by using the nonlinear primal-dual interior-point algorithm incorporating a quadratic penalty function to deal with the discrete control variables.Moreover,the introducing occasion of the quadratic penalty function and the valuating strategy of the penalty factors during the iteration are discussed.Calculation instances of two AC/DC power systems with 11 buses and 39 buses show that both the proposed optimal model and the algorithm can reliably converge to the enforceable and economic operation mode of the system.