Coordinated optimization of unit commitment and DC transmission power scheduling using benders decomposition

In response to the challenges brought by generation scheduling with hybrid AC/DC transmission system, this paper presents a hybrid scheduling mode for coordinated optimization of unit commitment and DC transmission power scheduling. Considering the characteristics of both units and DC transmission system, the optimal unit commitment and operation state of DC transmission system are acquired to achieve the best system economic profit, while AC/DC transmission constraints are also delicate formulated in the model to ensure the security of scheduling results. Since this coordinated optimization model is a large scale mixed integer nonlinear optimization problem, the Benders decomposition method is employed to tackle the computational difficulties. The coordinated optimization model is decomposed into a master problem to optimize unit commitment and DC transmission power without considering AC/DC transmission constraints, and hourly security check sub-problems which check the power flow violations caused by inappropriate results of unit commitment and DC transmission power schedule obtained by the master problem. Corresponding solution procedure and iteration algorithm are proposed to enhance convergence and computation efficiency, in which parallel computation technique is implemented to accelerate the convergence. Numerical results based on the CEPRI 22-bus system validate the effectiveness of our proposed method.