Abstract

Virtual synchronous generator (VSG) control lacks voltage inertia and powerful decoupling capabilities. The voltage of the distributed generator (DG) unit controlled by the VSG will be easily affected by power fluctuations and high-frequency noise, and the DG coupling usually makes the VSG control effect unsatisfactory. In order to effectively reduce power fluctuations, the influence of high-frequency noise on voltage, the influence of coupling on the power regulation, and effectively improve the economy of the economic system, the improved VSG control that combines voltage inertia and virtual impedance is proposed in this paper. The second-order inertia in the proposed VSG control strategy can minimize the voltage change rate and filter high-frequency noise from the excitation and virtual impedance. The virtual impedance in the proposed VSG control strategy can simulate the actual impedance to change the line characteristics, so the coupling of the DG unit can be reduced. Experimental results based on the microgrid platform prove the feasibility of improving the VSG control.

Highlights

  • Virtual synchronous generator (VSG) control simulates the dynamic droop characteristic and steady-state droop characteristic of the synchronous generator, which adjusts the voltage amplitude and frequency by means of calculating the reactive power and active power separately

  • Units will be affected by the power fluctuations, resulting in the fluctuations of the voltages, and if the line impedance reflects the characteristics of resistance and inductance, there is a strong coupling in the distributed generator (DG) unit

  • In order to solve the disadvantages of the dynamic performance of VSG control and the poor accuracy of microgrid power distribution, and realize the stable power regulation of DG units, this paper proposes an improved VSG control that combines voltage inertia and virtual impedance

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Summary

Introduction

Virtual synchronous generator (VSG) control simulates the dynamic droop characteristic and steady-state droop characteristic of the synchronous generator, which adjusts the voltage amplitude and frequency by means of calculating the reactive power and active power separately. In [19], a first-order inertia is introduced into the excitation block and virtual impedance It enhances the inertia of the voltage and reduces the influence of the high frequency noises from the excitation block and virtual impedance. The first-order inertia in these papers can enhance the inertia of the voltage in some extent, and it can filter out the high frequency noises, its inertia and filtering performance are greatly limited by the stability of the DG units adopting the VSG control. In order to solve the disadvantages of the dynamic performance of VSG control and the poor accuracy of microgrid power distribution, and realize the stable power regulation of DG units, this paper proposes an improved VSG control that combines voltage inertia and virtual impedance.

VSG Control
Comparisons of First-Order Inertia and Second-Order Inertia
Comparison of Bode Diagram
Comparison of Positions of Poles
Improved VSG Control
Stability Analysis and Experiment
Stability Analysis
Performance Comparisons of Different VSG Control
Active Power Regulation of Islanded Microgrid
Findings
Conclusions
Full Text
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