On the assessment of voltage unbalance

Seiphetlho, T. E.; Rens, Johan

doi:10.1109/ichqp.2010.5625366

Cited by 43 publications

(34 citation statements)

References 9 publications

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“…Actually, based on the Kirhoff's current law, the unbalance current flowing in feeder k is the collective effect of all unbalanced sources in the system, and it can be calculated according to Equation (18): (18) . …”

Section: Contribution Determination For Concentrated-multiple Unbalanmentioning

confidence: 99%

“…According to Equation (18), the difference between "actual current" and "individual current" is affected by both the load impedance and the equivalent unbalanced voltage source. The equivalent voltage source represents the unbalance level of the Energies 2017, 10, 171 7 of 17 corresponding unbalanced source, while the impedance represents the load level.…”

Section: Kmentioning

confidence: 99%

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Contribution Determination for Multiple Unbalanced Sources at the Point of Common Coupling

Sun

et al. 2017

Energies

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Three-phase unbalance is an important power quality issue that can cause many negative effects to the power system. Effective mitigation and management of voltage unbalance will benefit from the knowledge of how the unbalanced sources contribute to the voltage asymmetry at the point of evaluation (POE). In this paper, a method is proposed to assess the overall unbalance contribution of the multiple unbalanced sources at the point of common coupling (PCC). Firstly, the equivalent circuit for analysis is established and the unbalance contribution indices are proposed. Then a method is proposed to determine whether the dominant unbalanced polluter is at the upstream or downstream of POE. If the main unbalanced source is identified to be downstream of POE, a procedure is further proposed to determine the individual contribution of the multiple unbalanced sources. Moreover, for the multiple unbalanced source condition, the current flowing in each feeder is proposed to be used for the contribution estimation instead of the current actually emitted by the unbalanced source. Finally, a method is proposed to estimate the equivalent negative sequence impedance of the aggregate loads. Simulation and field analysis results validate the effectiveness and accuracy of the method.

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Section: Contribution Determination For Concentrated-multiple Unbalanmentioning

confidence: 99%

Section: Kmentioning

confidence: 99%

Contribution Determination for Multiple Unbalanced Sources at the Point of Common Coupling

Sun

et al. 2017

Energies

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“…However, this model does not present an adequate assessment of the unbalance produced by the load, [2]. This is specially significant respect to the contribution to the unbalance introduced by the set of harmonics different from the fundamental.…”

Section: Introductionmentioning

confidence: 99%

Assessment of unbalance and distortion in power systems that include active power line conditioners.

Prieto¹,

Revuelta²,

Vallés³

et al. 2024

RE&PQJ

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This paper presents a decomposition of the apparent power of a system that allows to separate the contribution to the unbalance of the whole set of harmonics of voltages and currents. From this set of power terms, the unbalanced fundamental, balanced harmonics and unbalanced harmonic indices are derived, that allow to evaluate separately the distortion and the unbalance. This procedure gives a more appropriate way to characterize the mitigation obtained using modern equipments with active compensation. These new indicators of the electric power quality have been applied here to a system with unbalance and distortion in the supply and the load, before and after the connection of a parallel active compensator, and with the connection of a series-parallel active compensator. The results obtained with a dedicated experimental platform have allowed to verify the validity of the new proposed indices.

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“…Assessment of VU emission at the PCC with the help of the sequence energies is discussed in [6] and prediction of VU emission given by loads through unbalanced fundamental power is presented in [7]. None of the above work discuss or give methodologies that can be used to separate the individual emission contributions made by different sources of unbalance.…”

Section: Introductionmentioning

confidence: 99%

Voltage unbalance emission assessment in interconnected power systems

Jayatunga

Perera

Ciufo

et al. 2014

2014 IEEE PES General Meeting | Conference &Amp; Exposition

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The International Electrotechnical Commission (IEC) Technical Report IEC/TR 61000-3-13:2008 considers voltage unbalance (VU) emission assessment as a key aspect of the VU management of power systems. Compliance assessment of unbalanced installations at the post connection stage is essential to ensure that the limits set by the IEC VU emission allocation methodology in the pre-connection stage are met. Although VU is known to be caused by load asymmetries and inherent network asymmetries, locating all VU emission sources is not a straightforward process, especially in a network with interconnections. Such assessment methodologies should ensure that the contributions from various sources of unbalance to the total VU emission are determined using data which is not overly demanding. This paper presents deterministic methodologies which can be used to assess constituent components of post-connection VU level at the point of evaluation in an interconnected network utilising post connection voltage/current measurements and known system parameters. The theoretical bases are developed to cover different load types including induction motors. Emission assessment outcomes of different study systems obtained by employing the proposed methodologies are verified using unbalanced load flow analysis. Abstract-Voltage unbalance (VU) emission assessment is an integral part in the VU management process where loads are allocated a portion of the unbalance absorption capacity of the power system. The International Electrotechnical Commission Report IEC/TR 61000-3-13:2008 prescribes a VU emission allocation methodology establishing the fact that the VU can arise at the point of common connection (PCC) due to both upstream network unbalance and load unbalance. Although this is the case for emission allocation, approaches for post connection emission assessment do not exist except for cases where the load is the only contributor to the VU at the PCC. Such assessment methods require separation of the post connection VU emission level into its constituent parts. In developing suitable methodologies for this purpose, the pre-and post-connection data requirements need to be given due consideration to ensure that such data can be easily established. This paper presents systematic, theoretical bases which can be used to assess the individual VU emission contributions made by the upstream source, asymmetrical line and the load for a radial power system. The methodology covers different load configurations including induction motors. Assessments obtained employing the theoretical bases on the study system were verified by using unbalanced load flow analysis in MATLAB and using DIgSILENT PowerFactory software.

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On the assessment of voltage unbalance

Cited by 43 publications

References 9 publications

Contribution Determination for Multiple Unbalanced Sources at the Point of Common Coupling

Contribution Determination for Multiple Unbalanced Sources at the Point of Common Coupling

Assessment of unbalance and distortion in power systems that include active power line conditioners.

Voltage unbalance emission assessment in interconnected power systems

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