Transient Angle Stability of Virtual Synchronous Generators Using Lyapunov’s Direct Method

Shuai, Zhikang; Shen, Chao; Li, Xuan; Li, Zuyi; Shen, Z. John

doi:10.1109/tsg.2018.2866122

Cited by 303 publications

(163 citation statements)

References 31 publications

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“…As an alternative, Lyapunov's direct method can be adopted for the transient stability assessment. Yet, it requires the derivation of a candidate Lyapunov function, which is challenging to obtain in practice [81]. In contrast, phase portraits that provides a graphical solution of first-and second-order nonlinear systems, are more intuitive and can be readily implemented.…”

Section: ) Large-signal Modeling and Analysis Methodsmentioning

confidence: 99%

“…Since grid-forming converters with the second-order power control loops exhibit similar dynamics as SGs, the existing methods for stabilizing SGs, e.g., controlling the governor to reduce the accelerating power and/or injecting additional reactive power to boost the output voltage during grid faults, can be directly adopted. As pointed out in [81], [82], the transient stability of grid-forming converters can also be enhanced by reducing the active power reference and/or increasing the reactive power reference during grid voltage sags, as shown in Fig. 26(a)-(b).…”

Section: I) Change Active and Reactive Power Referencesmentioning

confidence: 98%

“…In the former case, the grid-forming control turns into the grid-following mode and its transient stability characteristic is detailed in Section III-B. Further, during the fault recovery stage, switching [81] Increasing the reactive power reference [82] Modify control loops or controller parameters Coordinate the design of virtual inertia and damping term [24] Gain scheduled inertia and damping [83] Mode-switching control [80] back to the grid-forming control may also cause instability issues [85]. In the latter case, the maximum power transfer capability is reduced due to the current limitation, and the grid-forming converter is prone to the LOS due to the higher risk of loss of equilibrium points [84].…”

Section: ) Current Limiting Controlmentioning

confidence: 99%

See 2 more Smart Citations

Grid-Synchronization Stability of Converter-Based Resources—An Overview

Wang¹,

Taul²,

Wu³

et al. 2020

IEEE Open J. Ind. Applicat.

498

237

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This paper presents an overview of the synchronization stability of converter-based resources under a wide range of grid conditions. The general grid-synchronization principles for grid-following and grid-forming modes are reviewed first. Then, the small-signal and transient stability of these two operating modes are discussed, and the design-oriented analyses are performed to illustrate the control impact. Lastly, perspectives on the prospects and challenges are shared.

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Section: ) Large-signal Modeling and Analysis Methodsmentioning

confidence: 99%

Section: I) Change Active and Reactive Power Referencesmentioning

confidence: 98%

Section: ) Current Limiting Controlmentioning

confidence: 99%

See 1 more Smart Citation

Grid-Synchronization Stability of Converter-Based Resources—An Overview

Wang¹,

Taul²,

Wu³

et al. 2020

IEEE Open J. Ind. Applicat.

498

237

View full text Add to dashboard Cite

show abstract

“…Recently, X. Wang's research group [17]- [20] created a new perspective by using the phase portrait method to analyze the transient stability of grid-connected converters, though the method has high complexity and low physical insight [20]. Besides, the Lyapunov's direct method have also been applied to investigate the transient stability of voltage-controlled grid-connected converters [21], [22]. However, it is still an unresolved problem to develop a proper Lyapunov function candidate specially for assessing the transient stability of PLL-synchronized current-controlled converters [20].…”

Section: Introductionmentioning

confidence: 99%

Transient Stability Analysis and Enhancement of Renewable Energy Conversion System During LVRT

Geng

et al. 2020

IEEE Trans. Sustain. Energy

124

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Grid-connected renewable energy conversion systems (RECSs) are usually required by grid codes to possess the low voltage ride through (LVRT) and reactive power support capabilities so as to cope with grid voltage sags. During LVRT, RECS's terminal voltage becomes sensitive and changeable with its output current, which brings a great challenge for the RECS to resynchronize with the grid by means of phase-locked loops (PLLs). This paper indicates that loss of synchronism (LOS) of PLLs is responsible for the transient instability of grid-connected RECSs during LVRT, and the LOS is essentially due to the transient interaction between the PLL and the weak terminal voltage. For achieving a quantitative analysis, an equivalent swing equation model is developed to describe the transient interaction. Based on the model, the transient instability mechanism of RECSs during LVRT is clarified. Furthermore, a transient stability enhancement method is proposed to avoid the possibility of transient instability. Simulations performed on the New England 39-bus test system verify the effectiveness of the method.  Index Terms-Renewable energy conversion system, grid faults, low voltage ride through, transient stability, power converter.

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“…Among various TEF methods, the boundary of stability based controlling unstable equilibrium point (BCU) method appears to be a credible approach as it contains a strong theoretical background for the evaluation of critical energy. 29 The BCU method evaluates critical energy at the CUEP and the iso-energetic plane of CUEP ∂S(V(X 1 )) can be approximated as a stable boundary. 30 However, obtaining the correct CUEP may be difficult due to the complex computation required.…”

mentioning

confidence: 99%

A simultaneous phase sequence exchange control method based on transient energy function

Huang

2020

Int Trans Electr Energ Syst

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Emergency control systems can ensure the power grid stable operation. Phase sequence exchange (PSE) is a recently developed emergency control technology. In this article, a numerical search algorithm for finding PSE is proposed to reduce the maximum unbalanced energy of the system. This method can quickly identify the generator requiring PSE and obtain its power angle threshold without traversing all critical units. After fault clearance, taking the energy at the closest unstable equilibrium point as the critical energy of PSE, even if it is conservative when assessing the system stability, PSE is still conducive to the system stability. The complex search process of the controlling unstable equilibrium point is thus unnecessary. When the power angle reaches the threshold value, the selected generator PSE at the same time, which reduces the unbalanced energy and restrains the out-of-step system. Three test systems verified the proposed control method is effective.

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Transient Angle Stability of Virtual Synchronous Generators Using Lyapunov’s Direct Method

Cited by 303 publications

References 31 publications

Grid-Synchronization Stability of Converter-Based Resources—An Overview

Grid-Synchronization Stability of Converter-Based Resources—An Overview

Transient Stability Analysis and Enhancement of Renewable Energy Conversion System During LVRT

A simultaneous phase sequence exchange control method based on transient energy function

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