Abstract
By introducing a feedback path in the conventional droop control loop of islanded microgrid, the voltage amplitude and frequency restoration can be effectively achieved by using the secondary control. However, the usage of low bandwidth communication (LBC) links, the communication delays and the underlying data drop, would increase the system complexity and reduce its reliability. In our previous studies, it is found that the voltage and frequency deviation of islanded three-phase microgrid in synchronous reference frame can be restored by utilizing a band-pass filter (BPF)-based improved droop control strategy, without any communication lines and additional control loops. For more general scenarios, the BPF-based droop control scheme is first extended to islanded single-phase microgrid in hybrid frame in this paper to achieve deviation restoration. Moreover, the dynamic stability of the studied system is addressed by the derived reduced-order small-signal model in this paper, which simplify the modeling process and theoretical analysis. Followed by the system model, the impact of system parameters variation on the stability and dynamic performance of the microgrid are subsequently predicted by applying the eigenvalue-based analysis approach. Consequently, the analytical results show an overdamped system with good stability and robustness against system parameters drift. Finally, the effectiveness of eigenvalue analysis is verified by simulation results, and the experiment results are provided to further validate the feasibility of BPF-based droop control method in islanded single-phase microgrid.
Highlights
With the increased penetration of distributed generation (DG) units, the inverter-dominated microgrid is drawing more and more attention to promote the utilization of renewable energy, which moderates the dependency on fossil fuels
2) The reduced-order small-signal model of standalone single-phase microgrid with band-pass filter (BPF)-based droop control is derived, and the impact of system parameters shifting, including the active and reactive droop control coefficients, the bandwidth of BPF and the load resistance, on the stability and dynamic performance of system are analytically predicted by using eigenvalue loci of the system matrix, which provide a basis for the selection of system parameters
In this paper, the BPF-based droop control is first extended to single-phase microgrid with synchronous reference frame (SRF) voltage control loop to achieve deviation restoration, which is universal and scalable both in the single-phase and three-phase microgrid
Summary
With the increased penetration of distributed generation (DG) units, the inverter-dominated microgrid is drawing more and more attention to promote the utilization of renewable energy, which moderates the dependency on fossil fuels. 2) The reduced-order small-signal model of standalone single-phase microgrid with BPF-based droop control is derived, and the impact of system parameters shifting, including the active and reactive droop control coefficients, the bandwidth of BPF and the load resistance, on the stability and dynamic performance of system are analytically predicted by using eigenvalue loci of the system matrix, which provide a basis for the selection of system parameters. In order to implement the stability analysis of islanded single-phase microgrid system, a reduced-order small-signal model of the system is derived which consists of two parts, including the active and reactive power of inverters and the BPF-based droop control loop. A. SMALL-SIGNAL MODEL OF ACTIVE AND REACTIVE POWER When the islanded microgrid composed of two parallelconnected single-phase inverters operating in the steadystate, the inverters can be equivalent to ideal voltage sources seen from the filter output terminal.
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