Modeling and Stability Analysis of VSC Internal Voltage in DC-Link Voltage Control Timescale

Huang, Yunhui; Zhai, Xuebing; Hu, Jiabing; Liu, Dong; Chang, Lin

doi:10.1109/jestpe.2017.2715224

Cited by 55 publications

(59 citation statements)

References 21 publications

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“…For VSC control loops as introduced in Section 2.1, the response time constant of current control is often designed around 10ms (which is closely related to the switching frequency), and those of DVC, TVC, and PLL are selected to be about ten times larger [23]. Considering the designed response time constant of different controllers, stability issues related to VSC can be classified into the DVC timescale stability problems [14][15][16]24] and the current control timescale stability problems [22,25]. For simplicity, the dynamics in these two timescales can be analyzed individually due to their relatively separated response times.…”

Section: Definition Of Dvc Timescalementioning

confidence: 99%

“…For simplicity, the dynamics in these two timescales can be analyzed individually due to their relatively separated response times. Therefore, for stability analysis in the DVC timescale, AC currents can be considered to instantaneously track their reference values [14][15][16]24]. Besides, since the filter capacitor C f mainly contributes to the high-frequency oscillations, which belong to the current control timescale [22,25], for stability analysis in the DVC timescale, the effect of the filter capacitor can be neglected [14][15][16]24].…”

Section: Definition Of Dvc Timescalementioning

confidence: 99%

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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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Section: Definition Of Dvc Timescalementioning

confidence: 99%

Section: Definition Of Dvc Timescalementioning

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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“…DC/AC converters are one of the most common interfaces between the distributed generation system and the power grid. Traditional vector control strategies of DC/AC converters mainly aim to achieve a fast dynamic response [1]. Moreover, the power control of renewable energy is often set as maximum power point tracking (MPPT) in order to harvest as much energy as possible [2,3].…”

Section: Introductionmentioning

confidence: 99%

A Modified Self-Synchronized Synchronverter in Unbalanced Power Grids with Balanced Currents and Restrained Power Ripples

et al. 2019

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This paper proposes a modified self-synchronized synchronverter for unbalanced power grids. Small signal analysis of the conventional synchronverter shows that its stability margin around 50 Hz is very limited. Thus, power ripples will be caused at the frequency of 50 Hz. Filter- based current feeding loops are adopted in the conventional synchronverter in order to enhance its stability and eliminate power ripples. In addition, the characteristics of the conventional synchronverter in unbalanced power grids are analyzed, and an improved strategy using a resonant controller is proposed to restrain the current harmonics and power ripples. The parameter design is also studied for the proposed synchronverter. Experimental studies prove that the proposed strategy can achieve precise self-synchronization when the grid voltage is unbalanced, and the power-control performance is also improved significantly.

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“…Thus, the need of capable control for CHBMLI is necessary to correct the output converter voltage, even under changing environmental conditions. Many control strategies and power conditioning schemes are used for controlling the dc‐link voltages of CHB‐MLI and minimizing the power quality problems in its output as reported in literature …”

Section: Introductionmentioning

confidence: 99%

Capacitor voltage balancing in cascaded H‐bridge multilevel inverter and its modelling analysis for grid integrated wind energy conversion system application

Sharma

Dahiya

Nakka

2019

Circuit Theory & Apps

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windmills may operate at variable speeds. 5 Because of variable speed operation and better performance, the doubly fed induction generator (DFIG) has been conventionally used in WECSs. However, permanent magnet synchronous generator (PMSG) has gained broad attention in wind energy applications due to its high efficiency operation, extended speed operating range, self-excitation capability, and leading to a high power factor. For obtaining high efficiency in WECS, it is essential to manage WT such that they can produce maximum power. MPPT algorithm is required for maximal power extraction from the wind energy sources (WES). 1,[6][7][8][9] The output of wind turbine generator (WTG) coupling are inherently unstable dc voltage. The unstable output of WTG contribute to the power quality and stability issues like voltage variations, harmonic generation, and flickers in the grid network. Unwanted harmonics are produced due to the presence of power converters. In addition, due to the varying wind speed, flicker or voltage variation occurs in output power supply. Thus, for the grid integration of WECS, the need of advanced power electronic converters (rectifier, boost converters, and inverters) under transient and steady-state operating condition configuration and their proficient control are necessary to standardize the converter output voltage, even under changing environmental conditions. 3,10 Nowadays, in this type of applications, the multilevel inverters are mostly used in comparison to elementary two-level inverters due to several advantages. [11][12][13][14] Among all standard MLI topologies, "cascaded H-bridge inverter (CHBI)" is primarily used for grid-integrated WECS applications owing to its simpler layout, modular design, reduced number of components as compared with other classical MLI topologies and the use of low voltage rated switches for achieving high or medium power level. [14][15][16][17][18][19] In proposed WECS, WTG coupled systems are connected to two individual H-bridges per phase of CHBMLI through isolated dc link along with respective independent boost converter-based maximum power point tracking (MPPT) system. In addition, by cascading these two H-bridges, the desired five-level output phase voltage is obtained.The major advantage of adopted CHBMLI topology possessing the isolated dc links plays the prominent role to legitimate in connecting two WECS with unequivocal power generation because of deviation of the wind speeds among the windmills at any point of time. In addition, this MLI support to adjoin two medium voltage WECS to feed the total power generated into the high voltage grid without any transformers, but at the same time, the system achieves the better synchronization along with calibrated and controlled power flow. It is an important note to consider that either the CHB topology used as an inverter or a rectifier the mandate of possessing equal dc link voltages is essential to justify identical permissible voltage stress among all switching devices in multilevel topologies at high ...

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Modeling and Stability Analysis of VSC Internal Voltage in DC-Link Voltage Control Timescale

Cited by 55 publications

References 21 publications

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

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

A Modified Self-Synchronized Synchronverter in Unbalanced Power Grids with Balanced Currents and Restrained Power Ripples

Capacitor voltage balancing in cascaded H‐bridge multilevel inverter and its modelling analysis for grid integrated wind energy conversion system application

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