Small-Signal Disturbance Compensation Control for <i>LCL</i>-Type Grid-Connected Converter in Weak Grid

Zhu, Donghai; Zhou, Shiying; Zou, Xudong; Kang, Yong; Zou, Kaifeng

doi:10.1109/tia.2020.2980729

Cited by 41 publications

(20 citation statements)

References 30 publications

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“…where U is the inverter output voltage, R and L are the resistance and inductance of the grid side. Through (29), (31), where pk K and ik K are the first and second resonance coefficients, and the relationship between them is pk = ik K K R L [20] . c  is the bandwidth parameter, and the general value range is 5~15rad/s.…”

Section: Control Systemmentioning

confidence: 99%

“…The main factors affecting the transient response capability of the inverter are the digital delay process, the control parameter design of the current loop, and the phase lock speed of the PLL. [20] optimizes the current loop parameters through a multi-objective function to improve the transient response capability of the inverter, a simple small signal supplementary control is proposed.…”

Section: Introductionmentioning

confidence: 99%

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Virtual Frequency Construction-Based Vector Current Control for Grid-Tied Inverter Under Imbalanced Voltage

YiShui

Chen

et al. 2020

IEEE Access

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This paper proposes a fast phase capture (FPC) scheme and applies it to the control strategy of grid-tied inverters under imbalanced voltage. Firstly, a method for quickly extracting sequence components of power signals is derived through the symmetrical component method, and a real-time phase calculation method is proposed based on the rotating reference frame, thus avoiding the phase-locked loop (PLL) closed-loop adjustment process. Secondly, the grid-tied inverter suppresses the negative sequence current or power fluctuations through the direct resonance controller, so there is no need to separate the dynamically changing sequence current components. Finally, the experimental comparison with the PLL control strategy is carried out based on the RT-LAB platform. Compared with the previous phase-locking scheme, the FPC scheme has a faster phase-locking speed. Therefore, the fault ride-through capability of the grid-tied inverter is improved. INDEX TERMS Current control, Grid-tied inverter, Imbalanced grid, Phase detection.

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Section: Control Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Virtual Frequency Construction-Based Vector Current Control for Grid-Tied Inverter Under Imbalanced Voltage

YiShui

Chen

et al. 2020

IEEE Access

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“…However, the PLL-based synchronization strategy may suffer from stability issues, especially when the VSC is connected to a weak grid [9], [10]. To address the instability issue induced by the PLLs, one solution is to introduce extra feedforward or feedback terms in the current control loop, such as the output impedance reshaping method [11] and small-signal disturbance compensation control [12]. However, these solutions increase the implementation complexity of the current control loop and are dependent on the operating point of the system.…”

Section: Introductionmentioning

confidence: 99%

A Lyapunov-Based Nonlinear Power Control Algorithm for Grid-Connected VSCs

Fan

Wang

2022

IEEE Trans. Ind. Electron.

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For grid-connected voltage source converters (VSCs), it is commonly required that its power outputs can track the power references given by operators under various grid conditions. To achieve this objective, this article presents a Lyapunov-based nonlinear power control algorithm. The system dynamics is developed in the stationary frame, which facilitates the design of the control algorithm in the absence of phase-locked loops (PLLs) that may cause instability issues in ultra-weak grids. A virtual resistance is then introduced to allow fast power tracking performance and relax the requirement on accurate system parameters. Further, to simplify the control design, the quasi-stationary line (QSL) impedance model is applied, based on which a nonlinear control algorithm that only utilizes the output voltage and current information is developed. Afterward, the stability of the closed-loop system is analyzed via the Lyapunov theory. The theoretical results illustrate that the power regulation goal can be achieved and the VSC can maintain synchronization with the power grid. Finally, experimental results demonstrate the effectiveness of the proposed control algorithm under temporary grid faults and various short circuit ratios (SCRs).

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“…However, this method often results in a PLL with a very slow dynamic response which is not desirable (see e.g., [5], [32], [33]). Modifying the structure of the outer control loops, the AVC and PLL, by adding linear functions of output voltage and currents has been proposed to improve the VSC-WG stability [15], [26], [32], [34]. Essentially, these methods change the output impedance of the VSC such that the sourceload admittance matching holds between the VSC and WG.…”

Section: Introductionmentioning

confidence: 99%

Dual Active Compensation for Voltage Source Rectifiers Under Very Weak Grid Conditions

Rezaee¹,

Radwan

Moallem

et al. 2021

IEEE Access

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DC subgrids consisting of modern active loads (ALs) and local dc distributed generation (DG) units are normally interfaced with the main ac grid by utilizing bidirectional voltage source converters (VSCs). Under the very weak grid (VWG) conditions, the integration of voltage-oriented controlled (VOC) VSCs in the inversion mode becomes very challenging and therefore undamped oscillations in the power and angle responses are yielded. Most of the existing works address this issue for VSCs in the inversion mode of operation. However, integration of VSCs in the rectification mode with the consideration of the outer loop controllers into the VWGs has not been reported. To fill up this gap, a state-space model of the bidirectional VSC-to-weak grid (VSC-WG) system is developed in this work with an emphasis on the rectification mode of operation. A modal-sensitivity analysis is then utilized to evaluate small-signal stability of the system, identify the dominant modes, and investigate the system states that have a major influence on these modes. The results reveal two pairs of unstable complex modes that are correlated with the dynamic interaction between the VOC-based VSCs and the VWG impedance. It is also shown that the stability margin of VSCs in the rectification mode is less than that of the inversion mode under the same VWG conditions. To enhance the integration of the VSCs in the rectification mode, a dual-active compensation (DAC) scheme is proposed to mitigate the instabilities under VWG conditions. Several time-domain simulation results are presented to verify the validity of the small-signal model and demonstrate the effectiveness of the DAC scheme under the VWG conditions. Finally, hardware-in-the-loop (HIL) real-time experimental results are presented to validate the simulation results.INDEX TERMS Dual active compensation (DAC), dynamic interaction, rectification mode, short circuit ratio (SCR), small-signal stability, voltage source converter (VSC), very weak grid (VWG).

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Small-Signal Disturbance Compensation Control for LCL-Type Grid-Connected Converter in Weak Grid

Cited by 41 publications

References 30 publications

Virtual Frequency Construction-Based Vector Current Control for Grid-Tied Inverter Under Imbalanced Voltage

Virtual Frequency Construction-Based Vector Current Control for Grid-Tied Inverter Under Imbalanced Voltage

A Lyapunov-Based Nonlinear Power Control Algorithm for Grid-Connected VSCs

Dual Active Compensation for Voltage Source Rectifiers Under Very Weak Grid Conditions

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