Small-Signal Stability Analysis of the Standalone Single-Phase Parallel Inverter with BPF-based Droop Control Scheme

As a supplementary part of the droop control, the secondary control is widely utilized in the control of the microgrid, however, its reliability is susceptible due to the possible communication delay and data drop-out. In our recent work, the steady-state amplitude and frequency deviation of voltage can be restored by using the band-pass filter (BPF)-based improved droop control, without any communication links and additional control loop. In this paper, the BPF-based improved droop control is first employed for the two parallel-connected islanded inverters, and its small-signal model is derived in this case. Furthermore, the impact of the active power droop coefficient, the cutoff frequency of high-pass filter and the load impedance on system stability and dynamic performance are further analyzed based on the established model. Finally, the stability and dynamic response performance of the system under different control parameters is compared by simulation in PLECS software, which validates the effectiveness of this method in single-phase inverter system and the derived small-signal model.