Fully distributed DC-OPF approach for power flow control

The recent interest in distributed control strategies is motivated by the fact that the future electric power grid is expected to accommodate significantly more distributed resources. This future distributed infrastructure requires more autonomous control schemes for its scattered components, e.g., power flow control devices as considered in this paper. To this end, this paper presents a distributed control scheme for solving the DC Optimal Power Flow problem for an electricity network in which transmission lines are potentially instrumented with Distributed Flexible AC Transmission Systems (D-FACTS). Our approach constitutes a distributed iterative procedure which aims to solve the first order optimality conditions of the corresponding optimization problem. In this iterative algorithm, the responsibility of each bus includes updating a few local variables and exchanging updated variables with a few neighboring buses. Specifically, the updates at each bus include local innovation terms that are derived from the first order optimality conditions and preserve the coupling between the neighboring Lagrange multipliers and enforce the supply/demand balance. Due to the non-convexity of the primal problem, global optimality is not guaranteed, however, our results show that the distributed procedure converges to a solution of the first order optimality conditions yielding a local optimum. The performance of this algorithm is evaluated using the IEEE 14-bus and the IEEE-118 bus test systems.