ADMM-based Distributed Active and Reactive Power Control for Regional AC Grid with Wind Farms

A distributed active and reactive power control (DARPC) strategy based on the alternating direction method of multipliers (ADMM) is proposed for regional AC transmission system (TS) with wind farms (WFs). The proposed DARPC strategy optimizes the power distribution among the WFs to minimize the power losses of the AC TS while tracking the active power reference from the transmission system operator (TSO), and minimize the voltage deviation of the buses inside the WF from the rated voltage as well as power losses of the WF collection system. The optimal power flow (OPF) of the TS is relaxed by using the semidefinite programming (SDP) relaxation while the branch flow model is used to model the collection system of the WF. In the DARPC strategy, the large-scale strongly coupled optimization problem is decomposed by using the ADMM, which are solved in the regional TS controller and WF controllers in parallel without loss of the global optimality. The boundary information is exchanged between the regional TS controller and WF controllers. Compared to the conventional OPF method of the TS with WFs, the optimality and accuracy of the system operation can be improved. Moreover, it efficiently reduces the computation burden of the system controller and eliminates the need of a central controller. The protection of the information privacy can be enhanced. A modified IEEE 9-bus system with two WFs consisting of 64 wind turbines (WTs) is used to validate the proposed DARPC strategy.