Phase-Locked Loop Small-Signal Disturbance Compensation Control for Three-Phase LCL-Type Grid-Connected Converter under Weak Grid

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

doi:10.1109/ecce.2018.8558372

Cited by 14 publications

(4 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To mitigate this influence, study [3] introduces a strategy devoid of a phase-locked loop, effectively sidestepping its impact on grid-connected current. In accordance with the insights presented in study [4], it is elucidated that the principal instigator of current resonance in inverters, particularly under conditions of substantial grid impedances, is attributed to high bandwidth phase-locked loops. Furthermore, the article asserts that a reduction in the bandwidth of phase-locked loops serves as an effective means to diminish their impact on grid-connected currents.…”

Section: Introductionsupporting

confidence: 81%

Designing Parameters to Reshape the Inverter Output Impedance Based on the D-Split Method under Weak Grid Conditions

Wang,

Zhou,

Hao

et al. 2023

Electronics

View full text Add to dashboard Cite

Novel energy generation technologies, such as high-permeability wind power and photovoltaic systems, exhibit inherent intermittency, randomness, and volatility. During periods of energy production from these sources, the impedance of the electrical grid frequently experiences significant fluctuations. Consequently, the grid manifests characteristics akin to a weak grid, highlighting the challenges associated with integrating renewable energy sources with variable output profiles. These fluctuations lead to a shift in resonance spikes of the LCL-type filter towards the lower frequency band, consequently impacting the stability of inverter grid connections. To mitigate this issue, the present study introduces a novel approach integrating the D-split method and a proportional–differential feedforward strategy. This combination aims to reshape the inverter’s output impedance, ensuring its consistent stability even amidst significant fluctuations in grid impedance. In this research, the optimal controller parameters for systems operating under robust grid conditions are initially determined. This selection process involves the application of the D-split method, supported by graphical visualization. Additionally, the amplitude and phase angle margin tester is employed while considering the system bandwidth as a limiting constraint. Moreover, accounting for the influence of grid impedance, the D-split method is reapplied to ascertain the most suitable values for the proportional–differential feedforward parameters. This adjustment aims to enhance the adaptability of the grid-connected inverter specifically in scenarios characterized by a weak grid. The hardware-in-the-loop (HIL) simulation results demonstrate that despite the presence of harmonics within the grid and a short circuit impedance ratio (SCR) of 3, the inverter maintains grid stability and effectively suppresses harmonics. Moreover, the total harmonic distortion factor (THD) of the grid-connected current remains below 5%.

show abstract

Section: Introductionsupporting

confidence: 81%

Designing Parameters to Reshape the Inverter Output Impedance Based on the D-Split Method under Weak Grid Conditions

Wang,

Zhou,

Hao

et al. 2023

Electronics

View full text Add to dashboard Cite

show abstract

“…In the weak grid studies, a robust current control is used to improve the converter's stability [14], a grid impedance estimation based adaptive control is used to maintain the converter's stable operation in [15], a quasi-proportional resonance feedforward control is used to enhance the converter's robust ability [16], a small-signal disturbance compensation control is used to mitigate the weak grid's influence [17], a novel grid voltage feedforward control is used to suppress the effect of grid voltage harmonics [18], all these studies greatly improve the performance of the converter in weak grid. However, the studies are mainly based on traditional nonlinear control, some complex models are needed, and a large amount of computation are also needed in practical application.…”

Section: An Improved Three-stages Cascading Passivity-based Control Of Grid-connected Lcl Converter In Unbalanc -Ed Weak Grid Conditionmentioning

confidence: 99%

An Improved Three-Stages Cascading Passivity-Based Control of Grid-Connected LCL Converter in Unbalanced Weak Grid Condition

Zhao

Ren

et al. 2021

IEEE Access

View full text Add to dashboard Cite

This paper proposes an improved three-stages cascading passivity-based control (PBC) for a grid -connected LCL converter in unbalanced weak grid condition. In general, the traditional double-loop control based on positive and negative sequence transformations is used in grid-connected converter control in unbalanced weak grid condition. However, it is time consuming for second harmonic filtering, and positive and negative sequence currents need to be controlled separately. The PBC has strong robustness to interference, and the line voltage based PBC can deal with the voltage unbalance effectively and easily without negative sequence transformation. But the traditional PBC needs six variables and three damping coefficients for the grid-connected LCL converter in unbalanced grid condition, and it has the disadvantage of difficult implementation. The improved PBC can realize the same control effect with three-stages cascading PBCs of two variables and one damping coefficient, and it has the advantages of easy implementation, good performance and high stability. First, the modeling and controller design are detailed described. Then the SIMULINK simulation results demonstrate the benefits of the improved control strategy. Finally, a grid-connected LCL converter prototype of 5kW is built and the experimental results verify the correctness and effectivity of the improved three-stages PBC strategy.INDEX TERMS improved passivity-based control, LCL converter, unbalanced weak grid.

show abstract

“…Finally, combining equations (14), (19) and (21), the overall state-space model of the grid-connected converter with current control and PLL, derived in the CRF, is given by (22). It should be pointed out that all the elements in column five of the state matrix are zeros because the state ∆θ represents the difference between the converter reference frame and the actual reference frame (see Figure 3 and 5).…”

Section: Pll and Converter Modelsmentioning

confidence: 99%

“…Reference [17] concluded that the stability of a grid-tied inverter remains unchanged with increasing PLL bandwidth. Finally, in [18][19][20][21] feedforward control methods were proposed to reduce the impact of the PLL bandwidth on the stability of the system. These methods all model the output impedance of the converter in the Laplace domain and analyse its dependence on the PLL parameters.…”

Section: Introductionmentioning

confidence: 99%

Small-Signal Modelling and Stability Assessment of Phase-Locked Loops in Weak Grids

et al. 2019

View full text Add to dashboard Cite

This paper proposes a low-complexity small signal model for a 3-leg converter connected to a balanced three-phase, three-wire weak grid and synchronised to this grid using a PLL implemented in a synchronous rotating d-q axis. A thorough analysis of the system stability as a function of the PLL bandwidth and the short circuit ratio (SCR) of the grid is performed based on a linearised model. By using the proposed model, an improved design process is proposed for the commonly used dq-PLL that accounts for the potential stability issues which may occur in weak grids. Using the proposed approach, it is possible to optimise the PLL design to find the fastest PLL that can operate stably considering the SCR of the grid. In addition, the proposed model is very simple, resulting in a straightforward design tool that could also be used for online stability monitoring. The method is validated through simulations and experimental results from a 5kW laboratory system.

show abstract

Phase-Locked Loop Small-Signal Disturbance Compensation Control for Three-Phase LCL-Type Grid-Connected Converter under Weak Grid

Cited by 14 publications

References 20 publications

Designing Parameters to Reshape the Inverter Output Impedance Based on the D-Split Method under Weak Grid Conditions

Designing Parameters to Reshape the Inverter Output Impedance Based on the D-Split Method under Weak Grid Conditions

An Improved Three-Stages Cascading Passivity-Based Control of Grid-Connected LCL Converter in Unbalanced Weak Grid Condition

Small-Signal Modelling and Stability Assessment of Phase-Locked Loops in Weak Grids

Contact Info

Product

Resources

About