Impedance Analysis and Stabilization of Virtual Synchronous Generators With Different DC-Link Voltage Controllers Under Weak Grid

Guo, Jian; Chen, Yandong; Wang, Lei; Wu, Wenhua; Wang, Xiangyu; Shuai, Zhikang; Guerrero, Josep M.

doi:10.1109/tpel.2021.3070038

Cited by 54 publications

(28 citation statements)

References 38 publications

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“…A common way is to cascade the DVC with the PSC, where the output of DVC generates the active power reference for the PSC [10]- [12]. Another method is to configure the DVC and PSC in parallel [13], which is recently named as the dual-port grid-forming control in [14]. Besides, the dc-link voltage dynamics can be directly linked to the frequency of ac output of VSC, without involving the PSC loop [15]- [18].…”

Section: Introductionmentioning

confidence: 99%

“…The small-signal stability of the cascaded DVC and PSC scheme is analyzed by the impedance method in [12], which reveals the oscillations caused by the interaction between DVC and PSC loops in weak grids. The subsynchronous oscillations that are caused by the interaction between paralleled DVC and PSC loops are discussed in [13]. Yet, the VSCs in those works only operate in the rectifier mode, and only the resistive and constant-current loads at the dc-link are considered.…”

Section: Introductionmentioning

confidence: 99%

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Analysis and Damping of Low-Frequency Oscillation for DC-Link Voltage-Synchronized VSCs

Zhao

Jin

Wang

2023

IEEE Trans. Power Electron.

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The power-synchronization control has been proven effective to enhance the stability of voltage-source converters (VSCs) in weak grids. This method can be realized with the dc-link voltage control for VSCs with regulated dc-link dynamics, which leads to the dc-link voltage-synchronization control. This paper analyzes the small-signal stability of dc-link voltage-synchronized VSCs, considering the effect of constant power load/source at the dc link. It is found that low-frequency oscillations may arise with dc-link constant-power dynamics. To dampen the oscillation, an active damping control method based on the active power feedforward (PFF) control is proposed. A notch filter tuned at the synchronous frequency is embedded in the PFF loop to avoid the adverse effect on synchronous oscillation. Design guideline for the PFF control parameters is formulated. Experimental tests of VSC operating in the rectifier and the inverter modes are performed. The results validate the theoretical analysis and the effectiveness of the control approach.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis and Damping of Low-Frequency Oscillation for DC-Link Voltage-Synchronized VSCs

Zhao

Jin

Wang

2023

IEEE Trans. Power Electron.

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“…To improve the stability of dc‐link voltage control under weak grid, a virtual synchronous control which utilizes the dynamics of the dc‐link capacitor to realize self‐synchronization is proposed for voltage‐source converters [32]. And in [33], the stability analyses of the virtual synchronous generators with different dc‐link voltage controllers were studied and compared, via the wideband dq ‐frame impedance models. The control strategies of dc‐link voltage that has been proposed in [32] and [33] are effective for voltage‐source converters.…”

Section: Introductionmentioning

confidence: 99%

Stability analysis of DFIG controlled by hybrid synchronization mode and its improved control strategy under weak grid

Xie

Mengjie

Yang

et al. 2023

IET Renewable Power Gen

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In order to improve the stability of doubly‐fed induction generator (DFIG)‐based wind turbines under weak grid, previous works have proposed the power synchronization control strategy in the rotor side converter (RSC). However, the potential instability risk of dc‐link voltage control in the grid side converter (GSC) has been neglected. Here, DFIG with power synchronization and phase‐locked synchronization for RSC and GSC respectively, is called as hybrid synchronization mode (HSM)‐controlled DFIG and, the full‐order state space model of HSM‐controlled DFIG are established. Eigenvalue and participation factor analysis shows that the HSM‐controlled DFIG is unstable under extremely weak grid due to the interaction of phase‐locked loop (PLL) and current‐loop in GSC. Furthermore, dominant pole analysis indicates that the HSM‐controlled DFIG exhibits weak damping at the AC side in strong grid. To enhance the stability of HSM‐controlled DFIG under extremely weak grid, an improved hybrid synchronization control strategy is proposed. The improved control strategy utilizes active power and dc‐link voltage to achieve PLL‐free operation of DFIG. The effects of the parameters in dc‐link voltage synchronous loop on control bandwidth, system stability and dynamic coupling are analysed. Finally, the validity of the theoretical analysis is investigated with experiments based on 2MW control‐hardware‐in‐loop platform.

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“…A few research works on the DVC of GFM converters can be found in [3], [10]- [14]. A common approach is to cascade the DVC and active power control (APC) loops [3], [10], [11], such that the grid synchronization is still realized by the active power loop.…”

Section: Introductionmentioning

confidence: 99%

Robust Synchronization Control for Grid-Forming Converters with Regulated DC-Link Dynamics

Zhao¹,

Jin²,

Wang³

2022

Preprint

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<p>For grid-forming (GFM) converters, the dc-link voltage control (DVC) can directly generate the frequency that is used for the grid synchronization. However, this method suffers from low-frequency oscillations (LFO). To tackle this challenge, this paper proposes a robust synchronization control for GFM converters. In the approach, the DVC and the <em>q</em>-axis voltage feedforward control loops are connected in parallel for the synchronization purpose. Compared with the conventional single-loop DVC scheme, the proposed synchronization approach can dampen the LFO. Compared with conventional cascaded or paralleled DVC and active power control schemes, the proposed synchronization approach can avoid the trade-off between LFO and synchronous resonance issues. Experimental tests of GFM converters are performed in rectifier and inverter modes. The results confirm the effectiveness of theoretical analysis and the performance of the proposed control approach. </p>

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Impedance Analysis and Stabilization of Virtual Synchronous Generators With Different DC-Link Voltage Controllers Under Weak Grid

Cited by 54 publications

References 38 publications

Analysis and Damping of Low-Frequency Oscillation for DC-Link Voltage-Synchronized VSCs

Analysis and Damping of Low-Frequency Oscillation for DC-Link Voltage-Synchronized VSCs

Stability analysis of DFIG controlled by hybrid synchronization mode and its improved control strategy under weak grid

Robust Synchronization Control for Grid-Forming Converters with Regulated DC-Link Dynamics

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