Distributed DCOPF with flexible transmission

Power system operation models are becoming increasingly more complex, as their capabilities improve. One particular area that has received significant attention over the last decade is inclusion of flexible transmission in power system operation software. Co-optimization of generation dispatch and flexible transmission can provide unprecedented levels of economic efficiency and reliability. However, modeling the additional flexibility comes at the expense of further computational complexity. Distributed optimization is one effective way of handling such complexities. This paper develops a fully-distributed DC optimal power flow method that incorporates flexible transmission, including reactance and phase controllers. The model employs linear update rules at each bus, which can be calculated efficiently, and requires communication of information only to the neighboring buses. Convergence to the optimal power flow solution is achieved through iterating between the bus-level sub-problems. Simulation studies, carried out on an RTS 96 and IEEE 118-bus systems, confirm the effectiveness of the method. The developed model is able to find the optimal solution even under a cold-start scenario. However, the convergence properties are significantly improved if an initial close-to-optimal guess is available, similar to real-time operations, where the last run's solution can be used as the initial point.