Research on Networked Protection Scheme of Active Distribution Networks With Doubly-Fed Wind Turbines and Electric Vehicles

With the increasing complexity of system operations, large-scale integration of distributed generation (DG) and electric vehicles (EVs), and frequent adjustments to feeder topology, distribution networks face challenges such as wide variations in equivalent impedance and the dual effects of DG on short-circuit currents. Traditional stage-based current protection may result in malfunction or failure to operate, struggling to meet the new demands of active distribution networks. This paper analyzes the short-circuit current characteristics of various DG and EV types, proposing a highly sensitive local protection criterion based on voltage direction and low current. Additionally, it introduces a networked forward-tripping matrix utilizing local high-sensitivity protection information and a networked protection approach considering both islanding and non-islanding modes. To address potential misjudgments in local high-sensitivity protection, a fault identification method for DFIG grid-connected lines is proposed. Finally, the proposed schemes are validated using PSCAD. Simulation results demonstrate the effectiveness of the proposed schemes in adapting to various operational modes and facilitating the integration of large-scale DG and EVs into distribution networks.