Unified Impedance Model of Grid-Connected Voltage-Source Converters

Wang, Xiongfei; Harnefors, Lennart; Blaabjerg, Frede

doi:10.1109/tpel.2017.2684906

Cited by 701 publications

(496 citation statements)

References 24 publications

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“…• Phasor-based 2x2 impedance matrix [29] • Modified sequence domain based transfer matrix including also DC-terminals [23] • Modified sequence domain impedance matrix referred to phase domain frequency [30] In [29] an impedance model based on phasors is derived, and the equivalence with the dq-and modified sequence domain matrix is proven. The previous work by the same authors [23] extends the modified sequence domain definition to also include DC-terminals.…”

Section: Impedance Models Comparison a Comparison Of Matrix Impedmentioning

confidence: 99%

“…In [30] a sequence domain impedance matrix is derived that is slightly different than the modified sequence domain matrix. Actually, the modified sequence domain matrix is an intermediate step in their derivation, as can be seen by equation (31) in [30].…”

Section: Impedance Models Comparison a Comparison Of Matrix Impedmentioning

confidence: 99%

“…Actually, the modified sequence domain matrix is an intermediate step in their derivation, as can be seen by equation (31) in [30]. The final step is to frequency shift the elements in the matrix, e.g.…”

Section: Impedance Models Comparison a Comparison Of Matrix Impedmentioning

confidence: 99%

“…The final step is to frequency shift the elements in the matrix, e.g. equations (32)- (34) in [30]. Consequently, the matrix elements are all referred to the phase domain frequency and not to the dq-domain frequency.…”

Section: Impedance Models Comparison a Comparison Of Matrix Impedmentioning

confidence: 99%

See 3 more Smart Citations

On the Equivalence and Impact on Stability of Impedance Modeling of Power Electronic Converters in Different Domains

Rygg

Molinas

Zhang

et al. 2017

IEEE J. Emerg. Sel. Topics Power Electron.

108

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Abstract-Small-signal analysis of power electronic converters and systems is often carried out by impedance-based methods. At the core of these methods lies the impedance modelling, which can either be obtained through analytical calculations, simulations or measurements. The impedance models can be obtained into two main domains -the dq-domain and the sequence domain. In the dq-domain the impedance model is a 2x2 matrix, while in the sequence domain it is composed by the positive and negative sequence impedance. Recently, a third domain called the modified sequence domain was defined as an extension to the sequence domain, but also with clear similarities to the dq-domain. The objective of this paper is to unambiguously relate to each other the impedances in these three domains, and to show how this equivalence translates into their respective stability assessments. It is also proven that the sequence domain impedance has the same marginal stability condition as the dq-domain impedance matrix.The three-phase Voltage Source Converter is used as an example converter in this paper, as its impedance model in all three domains is well established and reported by previous research. The results in this paper shows that the modified sequence domain model can be derived from the dq-domain model (and vice versa), and that the stability analysis will be identical in these two domains. It is also shown how the original sequence domain model can be derived from the two other models through a model reduction. However, a small discrepancy between the two Nyquist plots is observed in the presence of components such as phase lock loop or DC-link control.

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Section: Impedance Models Comparison a Comparison Of Matrix Impedmentioning

confidence: 99%

Section: Impedance Models Comparison a Comparison Of Matrix Impedmentioning

confidence: 99%

Section: Impedance Models Comparison a Comparison Of Matrix Impedmentioning

confidence: 99%

Section: Impedance Models Comparison a Comparison Of Matrix Impedmentioning

confidence: 99%

See 2 more Smart Citations

On the Equivalence and Impact on Stability of Impedance Modeling of Power Electronic Converters in Different Domains

Rygg

Molinas

Zhang

et al. 2017

IEEE J. Emerg. Sel. Topics Power Electron.

108

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“…Micro grid can be operated in grid connected or islanded mode [3,4]. Numerous control strategies are implemented and developed for integrating DERs with central grid system [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Fixed frequency sliding mode control of renewable energy resources in DC micro grid

Yasin

Ashraf

Bhatti

et al. 2019

Asian Journal of Control

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The rising cost of fossil fuels, their high depleting rate and issues regarding environmental pollution have brought the attention of the researchers towards renewable energy technologies. Different renewable energy resources like wind turbines, fuel cells and solar cells are connected to DC micro grid through controllable power electronic converters. In presence of these diverse generation units, robust controllers are required to ensure good power quality and to regulate grid voltage. This paper presents a sliding mode control based methodology to address the above mentioned challenges. The proposed technique keeps the switching frequency constant so that electromagnetic compatibility (EMC) issues can be solved with conventional filter design. Parallel operation of converter in DC micro gird is considered. Chattering reduction and power quality improvement by harmonic cancellation is proposed. A scaled down hardware for unregulated 11.5 V to 17.5 V input and 24V output is designed and tested.The experimental results show good performance of the controller under different loads and uncertain input voltage conditions. Moreover, the results show the robustness of the closed loop system to sudden variations in load conditions. Furthermore, a significant improvement in power quality is achieved by harmonic cancellation of chattering in the output of the converters.

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An improved power control strategy for grid‐connected hybrid microgrid without park transformation and phase‐locked loop system

Ahmad

Mekhilef

Mokhlis

2021

Int Trans Electr Energ Syst

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Summary Voltage source converters are important elements of grid‐connected microgrid, as these integrate distribution generators of microgrid with utility grid. Often due to lack of efficient and flexible control, these converters do not perform as per expectations. Many control methods based on dq current control theory had been developed for grid‐connected microgrids inverters to control power flow between microgrid and grid. However, all these controllers used phase locked loop systems for grid synchronization purposes, which possess slow dynamics and transient response. To overcome these issues, in this article, an improved real and reactive power control method for grid‐connected hybrid microgrid's bidirectional voltage source converter is proposed which is based on the dq current control theory without using phase locked loop system and Park transformation. The proposed power controller has possessed better dynamic performance compared with the conventional power controllers consisted of phase locked loop system. In addition, due to the elimination of phase locked loop system and park transformation not only the computational burden is reduced with the implementation of the proposed power controller, but also steady state performance is enhanced. The control hardware‐in‐loop real time simulation is carried out using real time digital simulator to validate the performance of the proposed power controller during transient state, steady state and power transfer mode by modeling a grid‐connected hybrid microgrid. From the simulation results, it has been observed that the settling time has improved to 0.08 second compared to 0.15 second of conventional controller, power ripples are significantly reduced, and total harmonic distortion of converter output current obtained is 2.226%.

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Unified Impedance Model of Grid-Connected Voltage-Source Converters

Cited by 701 publications

References 24 publications

On the Equivalence and Impact on Stability of Impedance Modeling of Power Electronic Converters in Different Domains

On the Equivalence and Impact on Stability of Impedance Modeling of Power Electronic Converters in Different Domains

Fixed frequency sliding mode control of renewable energy resources in DC micro grid

An improved power control strategy for grid‐connected hybrid microgrid without park transformation and phase‐locked loop system

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