Abstract
The virtual synchronous generator (VSG) is an attractive interfacing technique for high-penetration renewable generation. By incorporating the inertia control, the grid-connected voltage-source converter can behave in a similar way with the SGs, which is helpful to enhance the stability of the power system. However, it is reported that the synchronous frequency resonance (SFR) can be aroused in the VSG due to the resonance peaks in the power control loops at the fundamental frequency. By modelling the power control loop in the dq domain, the mechanism underlying the SFR is studied. It reveals the frequency shift of the grid impedance in dq frame is the origin of SFR. Moreover, the phase-amplitude cross-regulation scheme is proposed to suppress the SFR. In this way, the resonance peaks in the power control loops are completely removed, and the coupling effects between the active power and reactive power loops are also eliminated. Therefore, superior power control performances can be achieved. Simulation results verify the effectiveness of the theoretical analysis and both dynamic performance and stability of the power loops are greatly improved by the proposed cross-regulation scheme.
Highlights
Over the past decade, renewable energy-based distributed power generations have been continuously integrated into power grids [1]
The dynamic interactions among the voltage-source converters (VSCs) and the grid tend to bring in various resonance and stability issues, challenging stable operations of modern power systems [2]
The stability of virtual synchronous generator (VSG) is greatly enhanced over the wideband frequency range and it is more flexible for VSG to choose power regulation parameters to achieve superior control performance
Summary
Renewable energy-based distributed power generations have been continuously integrated into power grids [1]. Controlled as the current source, the VSC is incapable of providing the independent voltage support for the loads [8] These issues impede the further increase of the renewable penetration level. To address the SR, the virtual resistance can be implemented by control and inserted into line impedance, so that the SR can be retrained without introducing power loss [13] This damping method will equivalently increase the R/X ratio of line impedance, which would inevitably make the coupling effects between the active and reactive powers more seriously. The coupling effects between the active and reactive power control loops are greatly eliminated In this way, the stability of VSG is greatly enhanced over the wideband frequency range and it is more flexible for VSG to choose power regulation parameters to achieve superior control performance
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