Stability Analysis of the Virtual Inductance for <i>LCL</i> Filtered Droop-Controlled Grid-Connected Inverters

Wang, Kai; Yuan, Xibo

doi:10.1109/jestpe.2021.3058810

Cited by 7 publications

(3 citation statements)

References 32 publications

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“…The designer duplicates an actual system impedance under steady-state conditions by simulating impedance as a quasi-stationary virtual impedance. Since the real impedances behave differently during the transient period, an increase in the rate of change of current will result in an increase in the voltage drop across the inductor [36]. On the other hand, the voltage quality could deteriorate as a result of adding virtual impedance [37].…”

Section: Virtual Impedance Droop Controlmentioning

confidence: 99%

Augmented Two-Stage Hierarchical Controller for Distributed Power Generation System Powered by Renewable Energy: Development and Performance Analysis

Bhutto

2024

Preprint

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The sustainable development of an area is highly dependable on reliable electrical energy supply. Microgrids are important in integrating distributed energy resources (DERs) using power electronic converters. However, microgrid control becomes challenging with the increasing number of distributed generators and loads. With the conventional droop control method, power contributions from DER converters cannot be accurately shared due to a mismatch of line impedances. In this paper, an augmented hierarchical control mechanism is proposed to solve the issues mentioned above. This hierarchical control mechanism consists of primary and secondary controllers. The primary stage utilized the droop controller to improve optimal power flow, mainly for the resistive network. The secondary stage is based on an improved methodology to compensate for the voltage and frequency variations during small and large signal disturbances. Moreover, the modelling and analysis for PMSG-based wind energy conversion systems are also presented. The response of the primary controller for the active and reactive power sharing is investigated. The analysis emphasizes the demonstration of optimal power-sharing under normal and abnormal conditions for the considered load. Finally, the suggested robust controller's performance is evaluated in MATLAB environment and simulation results show the proposed scheme's superiority under different operating conditions.

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Section: Virtual Impedance Droop Controlmentioning

confidence: 99%

Augmented Two-Stage Hierarchical Controller for Distributed Power Generation System Powered by Renewable Energy: Development and Performance Analysis

Bhutto

2024

Preprint

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“…It should be noted that the virtual inductance is implemented by the control loop, which does not add hardware costs. Besides, the principle as well as architecture of virtual inductance is different from that in [19], [20], since that no architecture of dual-loop control is contained in this type of VSG. The equivalent power with consideration of virtual inductance can be rewritten as:…”

Section: A Operation Principle Of Virtual Inductance Controlmentioning

confidence: 99%

A New Virtual Inductance Control Method for Frequency Stabilization of Grid-Forming Virtual Synchronous Generators

Yang

et al. 2023

IEEE Trans. Ind. Electron.

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Frequency stabilization is the premise of guaranteeing grid-friendly integration of virtual synchronous generator (VSG). Based on that premise, this study, focused on frequency stability, establishes the small signal model of grid-forming VSG system. At first, the mechanism of frequency oscillation occurring in system of active-and reactive-power coupling is analyzed by the defined feedback effect factor (FEF) in this study. Besides, a new dynamic model is established for identifying dynamic interaction of voltage magnitudes and frequency by means of feedback effect. The analytical results of established models agree with that of eigenvalue analysis. Furthermore, a new virtual inductance control strategy is proposed to mitigate the unstable oscillation of frequency and powers, enhance damping performance, and improve stability margins. Unlike the conventional virtual inductance control, which is reliable on dual-loop control framework, the proposed virtual inductance control in this study is based on principle of energy conservation and can be applicable for the grid-forming inverter without inner dual-loop control structure. Finally, the proposed modeling as well as virtual inductance control method is experimentally verified.

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“…Inevitably, the design of the three-order LCL filter is extremely complex. It is worth noting that, even if the LCL filter is designed with various constraints, there are stability problems in the GCI due to the inherent resonance phenomenon of the LCL filter [15][16][17]. Generally, active damping solutions are used to suppress the resonance of the LCL filter, which only change the control loops without damping resistance.…”

Section: Introductionmentioning

confidence: 99%

Grid Harmonics Suppression for Three Phase Dual-Frequency Grid-Connected Inverter Based on Feedforward Compensation

Chen,

Ma,

Yang

et al. 2023

Symmetry

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Using a low pulse ratio, the electromagnetic interference and switching loss of an inverter can be effectively reduced, particularly in high-power applications. However, due to variations in grid impedance, it is a challenging task to achieve stable operation of an LCL-type grid-connected inverter (GCI) using the active damping method with low pulse ratio. Thus, a novel three-phase dual-frequency GCI is presented to ensure the symmetry of the output power and the stable operation of the system address stability issues. The proposed inverter topology in this article is composed of two inverters in parallel, which are, respectively, a power inverter unit (PIU) and an auxiliary harmonic elimination unit (AHEU). To reduce the switching loss and improve the inverter efficiency, the switching frequency of the PIU is relatively low, injecting current into the grid. Moreover, the feedforward compensation method is used in AHEU. AHEU operates at high switching frequency to generate a current component that is symmetrical with the ripple com-ponent, improving the power quality, without extracting the current harmonic as the current reference. The operating principle of feedforward compensation is explained, and a proper parameter design procedure is presented in this paper. Since L filters are used for the proposed inverter, the system can operate stably where the ratio of switching frequency to fundamental frequency is low. A 10 kW laboratory prototype was built. The experimental results showed that the grid current ripple could be effectively eliminated and the THD of the grid current was 3.01%. The proposed inverter has good stability in a weak grid, and the efficiency of the proposed inverter is 95.98% at rated current, which is 0.81% higher than the traditional GCI, effectively increasing the efficiency of the system.

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Stability Analysis of the Virtual Inductance for LCL Filtered Droop-Controlled Grid-Connected Inverters

Cited by 7 publications

References 32 publications

Augmented Two-Stage Hierarchical Controller for Distributed Power Generation System Powered by Renewable Energy: Development and Performance Analysis

Augmented Two-Stage Hierarchical Controller for Distributed Power Generation System Powered by Renewable Energy: Development and Performance Analysis

A New Virtual Inductance Control Method for Frequency Stabilization of Grid-Forming Virtual Synchronous Generators

Grid Harmonics Suppression for Three Phase Dual-Frequency Grid-Connected Inverter Based on Feedforward Compensation

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