A Stability Enhancement Method for Inverter-Based Distributed Generation Systems

Large-scale integration of distributed generations (DGs) may degrade the stability of the power distribution system. This paper proposes a control method to improve the system stability of grid-connected inverter-based distributed generation (DG) systems. The proposed method is to add a stabilizer inside the inverter interface controller of a DG unit to supply auxiliary current reference signal for the inverter current controller and thus improve the stability performance. The input signal of the stabilizer is the grid frequency. A series of small-signal analysis and time-domain simulations have been conducted to verify the effectiveness of the proposed stabilizer. The oscillations of the DG system are greatly damped with the stabilizer.