Symmetrical components in the time domain and their application to power network calculations

Paap, G.C.

doi:10.1109/59.867135

Cited by 257 publications

(137 citation statements)

References 8 publications

(10 reference statements)

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“…By comparing (26) with (28) we see that the expressions are identical. Hence, it is proven that the stability analysis in the modified sequence domain predicts marginal stability if and only if the analysis by accurate models in the original sequence domain predicts marginal stability.…”

Section: Marginal Stability Equivalence Proofmentioning

confidence: 57%

“…It is also remarked that the 2x2 modified impedance domain matrix has similarities to the method involving complex transfer matrices in [25], especially concerning the definition of dq unsymmetric systems. Other works relating the dq and sequence domains to each other can be found in [26] and [27].…”

Section: Impedance Model In the Modified Sequence Domain -A Bridgementioning

confidence: 99%

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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.

104

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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: Marginal Stability Equivalence Proofmentioning

confidence: 57%

Section: Impedance Model In the Modified Sequence Domain -A Bridgementioning

confidence: 99%

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.

104

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show abstract

“…Low-pass filters have been tested for this purpose, however they caused instability problems. Finally to remove double frequency component Delayed Signal Cancellation (DSC) method is employed [18]. The DCS is the realtime sequence extraction method, based on combination of time delayed synchronous frame magnitudes.…”

Section: Control Of Ac-dc Converter Under Grid Voltage Dipsmentioning

confidence: 99%

“…To analyze the dip phenomena, the Symmetrical Component Theory [17,18] was employed. It claims that three-phase system can be represented as three sequences: positive, negative and zero.…”

Section: Voltage Dips In Power Systemmentioning

confidence: 99%

Control of PWM rectifier under grid voltage dips

Bobrowska-Rafał¹,

Rafał²,

Abad³

et al. 2009

Bulletin of the Polish Academy of Sciences: Technical Sciences

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Abstract. This paper investigates control structure for grid connected three-phase two-level Voltage Source Converter (VSC) under distorted grid voltage conditions. Grid voltage is distorted by balanced and unbalanced voltage dips and higher harmonics. To address the problem, the control structure of converter is presented. The control system is a modification of Voltage Oriented Control (VOC) based on Dual Vector Current Controllers (DVCC). Grid synchronization under distorted voltage is achieved by employing Phase Locked Loop (PLL). Simulation and experimental results, which illustrate properties of proposed system, are presented.

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“…Approaches based on artificial intelligence techniques such as genetic algorithms, fuzzy logic and neural networks are also proposed to detect and identify voltage and current sequence components, [10], [11], [12].Many other techniques are suggested and implemented in the time domain [13], [14]. This paper presents a novel technique based on recursive algorithm which can be used for digital identification of the symmetrical components of the harmonic contaminated voltage or current waveforms in electrical power systems.…”

Section: Introductionmentioning

confidence: 99%

New digital filter for unbalance distorted current and voltage estimation in power systems

Al-Hasawi

El-Naggar

2008

Electric Power Systems Research

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Abstract:-This paper presents a novel algorithm for identifying and measuring the symmetrical components of distorted three phase voltage or current waveforms in electrical power systems. The proposed algorithm is capable of estimating the symmetrical components as well as the harmonic contents of a given unbalanced distorted signal. The proposed technique is based on stochastic estimation theorem. The problem is formulated as an estimation problem and presented in state space form. The proposed algorithm used to estimate the positive, negative and zero components of unsymmetrical waveforms as well as the harmonic content of a given distorted signal. Application of the proposed algorithm has been conducted on various test cases. Among which a practical simulated power system has been implemented using EMTP. Various scenarios are carried out to simulate realistic situations of unsymmetrical waveforms. Effects of bad data on the solution accuracy are also studied. The speed of convergence is examined by changing the estimator initial conditions. Results obtained show that the proposed technique can estimate and track the symmetrical components of non-stationary three phase unbalance voltage or current waveforms in noisy environments. Fast accurate solutions are guaranteed regardless of the initial conditions. It is also shown that bad measurements have no effects on the final accuracy of the estimation.

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Symmetrical components in the time domain and their application to power network calculations

Cited by 257 publications

References 8 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

Control of PWM rectifier under grid voltage dips

New digital filter for unbalance distorted current and voltage estimation in power systems

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