Large Signal Synchronizing Instability of PLL-Based VSC Connected to Weak AC Grid

Hu, Qi; Fu, Lijun

doi:10.1109/tpwrs.2019.2892224

Cited by 250 publications

(121 citation statements)

References 19 publications

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“…This section aims at demonstrating the previously mentioned indefinite damping effect and its impacts on the accuracy of EAPbased ROA estimation. To this end, the GSS problem, along with its analysis models, will be first introduced, although in a concise manner as this has been well-examined in existing works (e.g., Zhang et al, 2017bZhang et al, , 2020Geng et al, 2018;Hu et al, 2019;Taul et al, 2019). The study system adopted is shown in Figure 1; it is composed of a three-phase VSC and a Thevenin equivalent grid.…”

Section: Gss Problem and The Indefinite Damping Effectmentioning

confidence: 99%

“…This is an open question in the field of coupled oscillators and, although it is not the topic of this paper, the behavioral characterization and understanding of the diverse non-linear oscillators existing in various types of VSCs seems to be crucial to answering this question. To this end, this paper will dig into a non-linear stability phenomenon associated with the PLL that is emerging in grid-feeding VSCs, i.e., gridsynchronizing stability (GSS) (Zhang et al, 2017b(Zhang et al, , 2020Geng et al, 2018;Han et al, 2018;Hu et al, 2019;Taul et al, 2019;Wu and Wang, 2020;He et al, 2020). Please note that for brevity, the term "grid-feeding" will be omitted in later analysis.…”

Section: Introductionmentioning

confidence: 99%

“…To understand the GSS issue, a concise system model, preferably possessing a certain level of physical implication, needs to be developed. To this end, authors in Zhang et al (2017bZhang et al ( , 2020, Hu et al (2019), and Taul et al (2019) have developed a simplified model of the grid-VSC system for the GSS analysis, which is essentially a second-order and autonomous nonlinear equation, referred to as the GSS model in later analysis. More appealingly, this GSS model is similar to the classic swing equation of the SG, due to which the GSS mechanism can be qualitatively elucidated according to the theory of SG.…”

Section: Introductionmentioning

confidence: 99%

“…More appealingly, this GSS model is similar to the classic swing equation of the SG, due to which the GSS mechanism can be qualitatively elucidated according to the theory of SG. For example, the Equal Area Principle (EAP) developed for the SG can be used for this purpose (Zhang et al, 2017b(Zhang et al, , 2020Hu et al, 2019). The obtained mechanism of GSS inspires many studies on stability-oriented control and parameter designs, e.g., the coordinated control schemes for the Low Voltage Ride Through (LVRT) (Geng et al, 2018;Han et al, 2018;He et al, 2020) and the PLL parameter design (Wu and Wang, 2020).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Synchronizing Stability Analysis and Region of Attraction Estimation of Grid-Feeding VSCs Using Sum-of-Squares Programming

Zhang

Molinas

et al. 2020

Front. Energy Res.

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Grid-synchronizing Stability (GSS) is an emerging issue related to grid-feeding voltage-source converters (VSCs). Its occurrence is primarily related to the non-linear dynamics of a type of vastly applied synchronization unit-Phase-locked Loops (PLL). Dynamic characterization and modeling for the GSS analysis can be achieved using a simplified system model, which is a second-order and autonomous non-linear equation, but with the presence of an indefinite damping term. As revealed and demonstrated in this work, this indefinite damping effect can result in an inaccurate Region-of-Attraction (ROA) estimation of the traditional Equal Area Principle (EAP)-based method. To overcome this issue and achieve a valid ROA estimation, this paper adopts the sum-of-squares (SOS) programming technique, which is a numeric optimization method with SOS relaxations. The development and implementation of the SOS program for ROA estimation are presented. Numerical case studies and time-domain verifications demonstrate that this method is valid for GSS analysis, and an almost precise estimation is achieved in the first quadrant. This evidence makes the SOS method a promising tool for GSS analysis because the GSS problem is most concerned with the stability within the first swing cycle, i.e., in the first quadrant.

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Section: Gss Problem and The Indefinite Damping Effectmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Synchronizing Stability Analysis and Region of Attraction Estimation of Grid-Feeding VSCs Using Sum-of-Squares Programming

Zhang

Molinas

et al. 2020

Front. Energy Res.

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show abstract

“…It is concluded that the positive-feedback loop threatened the system's small-signal stability. In reference [8], it was found that the additional feedback loop by frequency variation may have deteriorated the system's large-signal stability. In reference [9], an impedance-based VSC model was developed, and the effect of frequency variation on system stability was explored from the perspective of impedance interaction.…”

Section: Introductionmentioning

confidence: 99%

Modeling and Analyzing the Effect of Frequency Variation on Weak Grid-Connected VSC System Stability in DC Voltage Control Timescale

Yang

Yuan

2019

Energies

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The effect of frequency variation on system stability becomes crucial when a voltage source converter (VSC) is connected to a weak grid. However, previous studies lack enough mechanism cognitions of this effect, especially on the stability issues in DC voltage control (DVC) timescale (around 100 ms). Hence, this paper presented a thorough analysis of the effect mechanism of frequency variation on the weak grid-connected VSC system stability in a DVC timescale. Firstly, based on instantaneous power theory, a novel method in which the active/reactive powers are calculated with the time-varying frequency of voltage vectors was proposed. This method could intuitively reflect the effect of frequency variation on the active/reactive powers and could also help reduce the system order to a certain extent. Then, a small-signal model was established based on the motion equation concept, to depict the effect of frequency variation on the weak grid-connected VSC system dynamics. Furthermore, an analytical method was utilized to quantify the effect of frequency variation on the system’s small-signal stability. The quantitative analysis considered the interactions between the DC voltage control, the terminal voltage control, phase-locked loop, and the power network. Finally, case studies were conducted, and simulation results supported the analytical analyses.

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Control strategies for permanent magnet synchronous generator‐based wind turbine with independent grid‐forming capability in stand‐alone operation mode

Yuan

Zhang

et al. 2021

Int Trans Electr Energ Syst

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Large Signal Synchronizing Instability of PLL-Based VSC Connected to Weak AC Grid

Cited by 250 publications

References 19 publications

Synchronizing Stability Analysis and Region of Attraction Estimation of Grid-Feeding VSCs Using Sum-of-Squares Programming

Synchronizing Stability Analysis and Region of Attraction Estimation of Grid-Feeding VSCs Using Sum-of-Squares Programming

Modeling and Analyzing the Effect of Frequency Variation on Weak Grid-Connected VSC System Stability in DC Voltage Control Timescale

Control strategies for permanent magnet synchronous generator‐based wind turbine with independent grid‐forming capability in stand‐alone operation mode

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