An Online Feedback-Based Local Method for Topology Identification and Var/Volt Control in Radial Wind Farms

The knowledge about a network model is essential for control. However, the topology of wind farms (WFs) may be changed due to random off-grid events of wind turbines. This article develops a two-stage local method for WFs to achieve the Var/Volt coordinated optimization with consideration of topology changes, which provides an efficient solution when limited data are available for identification and control. In the first stage, considering the operational characteristics of WFs, a mixed integer optimization problem is formulated in each local controller to uncover the physical network topology. The problem is then solved and driven toward the optimum by an online recursive search algorithm. The proposed algorithm is intended to identify the physical network layout only using local measurements at no loss of accuracy. In the second stage, a completely decentralized Var/Volt control method is designed with the updated topological knowledge, aiming to achieve a fast Var response and to reduce voltage deviation caused by the stochastic wind power and voltage disturbance of external girds. Case studies in MATLAB/Simulink verify the robustness and effectiveness of the proposed method within a wide range of working conditions.