面向逆变器型微电网的方向性元件

Renewable energy sources integrated into the system via power electronic interfaces are becoming increasingly common in both power transmission and microgrids. These sources have different fault current characteristics compared to synchronous generators, primarily due to the current limit of the power electronic switches and the control systems of their power electronic interfaces. Due to the unique fault current characteristics of inverters, conventional directional elements might malfunction when inverter-based distributed energy resources are present in a microgrid. Therefore, this paper proposes a directional element to identify the current direction during fault. The proposed directional element determines the fault current direction by evaluating shifts in the current phase angle. In addition, a protection scheme is introduced to protect the microgrid against short circuit faults. The effectiveness of the proposed directional element and protection scheme are evaluated by the simulation of an inverter-based benchmark microgrid under different scenarios in MATLAB Simulink software. The performance of the proposed method is also experimentally validated and compared with directional overcurrent protection (ANSI code: 67) and voltage restrained overcurrent protection (51 V) in controller hardware in the loop setup using an FPGA-based controller and physical relays.