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P. Paranavithana - One of the best experts on this subject based on the ideXlab platform.
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Management of Voltage Unbalance Through Allocation of Emission Limits to Installations
Australian journal of electrical and electronics engineering, 2015Co-Authors: Sarath Perera, P. Paranavithana, Danny SutantoAbstract:The International Electrotechnical Commission (IEC) has recently released the Technical Report IEC/TR 61000-3-13 for the assessment of Voltage Unbalance emission by installations connected to medium Voltage (MV), high Voltage (HV) and extra high Voltage (EHV) power systems, which is expected to provide the basis for developing a compatible Australian Standard. The philosophy of the approach described in this report is similar to the IEC recommendations for harmonics and flicker allocation. In addition, this involves a unique aspect, the contribution to global Voltage Unbalance by system inherent asymmetries, noting the fact that the Voltage Unbalance at a busbar can arise due to both load and system (essentially lines) asymmetries. Although the concepts and the basic principles used in this approach are widely accepted, the Technical Report IEC/TR 61000-3-13 is seen to require further refinements and original developments in relation to some of the key aspects. This paper reports, in summary, the work that has been carried out addressing: (a) propagation of Voltage Unbalance from MV to low Voltage (LV) levels; and (b) global emission in MV systems due to line asymmetries, with the view to make contributions for further improving the present technical report.
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A review of recent investigations with reference to IEC/TR 61000-3-13 on Voltage Unbalance emission allocation
Proceedings of 14th International Conference on Harmonics and Quality of Power - ICHQP 2010, 2010Co-Authors: P. Paranavithana, Sarath Perera, Upuli Jayatunga, Phil CiufoAbstract:The Technical Report IEC/TR 61000-3-13:2008 provides guiding principles for coordinating Voltage Unbalance between various Voltage levels of a power system through the allocation of emission limits to installations. This report is based on widely accepted concepts and principles in relation to Voltage Unbalance. With regard to some of the key ideas used in this report, investigations have been carried out which have enabled the development of deeper insights making the Voltage Unbalance allocation process more comprehensive. The key aspects which have been considered in detail include: Voltage Unbalance which arises as a result of lines and Voltage Unbalance propagation in HV-MV, MV-LV power systems. In addition, a robust Voltage Unbalance allocation method has been developed which overcomes some difficulties associated where a uniform Voltage Unbalance planning level is adopted across all bus bars with the same Voltage level classification (ie, MV or HV or EHV). With regard to Voltage Unbalance emission assessment a novel technique has also been developed which was verified through the application to an interconnected power system where the methodology allows identification of the contributors to Voltage Unbalance at a selected bus bar.
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global Voltage Unbalance in mv networks due to line asymmetries
IEEE Transactions on Power Delivery, 2009Co-Authors: P. Paranavithana, Sarath Perera, Robert Koch, Z EminAbstract:The International Electrotechnical Commission (IEC) has recently released the Technical Report IEC/TR 61000-3-13 for the assessment of Voltage Unbalance emission limits to individual customer installations connected to medium-Voltage (MV), high-Voltage, and extra-high-Voltage power systems. As in the counterpart IEC technical reports for harmonics (IEC 61000-3-6) and flicker (IEC 61000-3-7) allocation, IEC/TR 61000-3-13 also apportions the global emission allowance to customers in proportion to their agreed apparent power. However, noting that Voltage Unbalance at a busbar can arise due to load and system (essentially lines) asymmetries, IEC/TR 61000-3-13 applies a scaling factor Kue to the apportioned allowance. This factor Kue represents the fraction of the global emission allowance that can be allocated to installations. Conversely, the factor K'ue = 1 - Kue accounts for the emission arising as a result of system inherent asymmetries. This paper addresses the global Voltage Unbalance emission in MV power systems arising as a result of line asymmetries on which a systematic evaluation method is not given in IEC/TR 61000-3-13. First, a detailed study with the view to investigate the influence of line asymmetries on the global emission and its dependency on various load types is carried out by employing a simple radial network. Second, a matrix-based methodology, covering radial and interconnected networks, for the assessment of this emission at the nodal level taking line, system and load characteristics, system operating conditions, and downstream load composition into account are proposed. The methodology is verified by using Unbalance load-flow analysis.
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A robust Voltage Unbalance allocation methodology based on the IEC/TR 61000-3-13 guidelines
2009 IEEE Power & Energy Society General Meeting, 2009Co-Authors: P. Paranavithana, S. PereraAbstract:The International Electrotechnical Commission (IEC) has introduced approaches for managing continuous power quality disturbances (harmonics, flicker and Voltage Unbalance) in power systems through the allocation of emission limits to customer installations, which are based on a common philosophy. However, it has been found that these harmonics and flicker allocation methods lead to planning levels being exceeded even when no customer exceeds the allocated emission limit. Subsequently, an alternative allocation policy which is referred to as the dasiaconstraint bus Voltagepsila (CBV) method has been developed to overcome this problem. This paper examines the application of the recently introduced IEC Voltage Unbalance allocation procedure (IEC/TR 61000-3-13) which involves an additional aspect ie. the emission arising from system inherent asymmetries. Paper identifies that this Voltage Unbalance allocation method also leads to a problem similar to above employing a simple 3-bus test system. A new Voltage Unbalance allocation policy based on the CBV method is suggested. It is demonstrated that this new Voltage Unbalance allocation technique satisfies the key allocation objective of complying with the set planning levels.
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Location of sources of Voltage Unbalance in an interconnected network
2009 IEEE Power & Energy Society General Meeting, 2009Co-Authors: P. Paranavithana, Sarath PereraAbstract:Identification of principal contributors to Voltage Unbalance and hence the implementation of suitable corrective measures has become an issue of concern for some network providers. In order to comply with stipulated limits, these network service providers require the development of quantitative measures that are reliable. For simple radial networks, the identification of sources may be seen as a trivial task. However, for interconnected networks which contain untransposed transmission lines and Unbalanced loads, the identification of sources of Unbalance is a non-trivial task. This paper gives a systematic theoretical approach that can be used to study the Voltage Unbalance behaviour exhibited by line and load asymmetries in interconnected network environments. A study network is initially analysed, and the outcomes are employed to develop a new concept termed ‘Voltage Unbalance emission vector’ to ascertain the overall influence made by an asymmetrical line or a load on Voltage Unbalance in a global sense. Using the Voltage Unbalance emission vectors of individual lines and loads, a technique has been developed which enables the identification of dominant contributors to Voltage Unbalance levels. Assessments made employing the above technique on the study system are confirmed using Unbalanced load flow analysis.
Sarath Perera - One of the best experts on this subject based on the ideXlab platform.
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Sensitivity of Network Wide Voltage Unbalance Levels to Variations in Unbalanced Installations
2020 19th International Conference on Harmonics and Quality of Power (ICHQP), 2020Co-Authors: T. D. Kahingala, Sarath Perera, Ashish P. Agalgaonkar, Upuli JayatungaAbstract:Voltage Unbalance (VU) emission assessment is a challenging task due to the complex interactions between the sources of Voltage Unbalance. Consequently, to account for transferred Voltage Unbalance from neighbouring busbars, IEC/TR 61000-3-13 has introduced influence and transfer coefficients in the VU allocation and emission assessment process. However, no generalised practical approaches exist to evaluate these coefficients where as IEC guidelines suggest some approximations based on simulations and field measurements. As an alternative, this paper proposes a sensitivity analysis of network VU to Unbalanced installations that can be employed in VU emission assessment. The proposed methodology uses readily available inputs and utilises a linearised approach to determine the network wide sensitivity of VU to Unbalanced installations which makes it feasible for practical implementation.
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Determining the Impact of Line Asymmetries on Network Voltage Unbalance based on Balanced Load Flow Studies
2018 Australasian Universities Power Engineering Conference (AUPEC), 2018Co-Authors: T. D. Kahingala, Sarath Perera, Ashish P. Agalgaonkar, Upuli JayatungaAbstract:Determining the impact of the individual contributors to network Voltage Unbalance (VU) is a complex task due to the interaction between the sources of Voltage Unbalance in power systems. This becomes further complicated as the network itself contributes to network Voltage Unbalance when it is not symmetrical which is mostly the case in real networks. To account for the network asymmetry, the Technical Report IEC/TR 61000-3-13 which is used for the assessment of Voltage Unbalance emission limits applies a scaling factor K ue when apportioning the global allowance to end user consumers. Studies on the impact of the untransposed overhead lines on each and every individual busbar and on the overall network Voltage Unbalance are essential in: emission allocation studies, identification of power flow constraints, and in decision making related to future investments on VU mitigation. This paper proposes an effective methodology to determine the influence of different untransposed lines based on the results of balanced load flow studies. The methodology can be easily extended to obtain the influence of the other contributors as well.
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Management of Voltage Unbalance Through Allocation of Emission Limits to Installations
Australian journal of electrical and electronics engineering, 2015Co-Authors: Sarath Perera, P. Paranavithana, Danny SutantoAbstract:The International Electrotechnical Commission (IEC) has recently released the Technical Report IEC/TR 61000-3-13 for the assessment of Voltage Unbalance emission by installations connected to medium Voltage (MV), high Voltage (HV) and extra high Voltage (EHV) power systems, which is expected to provide the basis for developing a compatible Australian Standard. The philosophy of the approach described in this report is similar to the IEC recommendations for harmonics and flicker allocation. In addition, this involves a unique aspect, the contribution to global Voltage Unbalance by system inherent asymmetries, noting the fact that the Voltage Unbalance at a busbar can arise due to both load and system (essentially lines) asymmetries. Although the concepts and the basic principles used in this approach are widely accepted, the Technical Report IEC/TR 61000-3-13 is seen to require further refinements and original developments in relation to some of the key aspects. This paper reports, in summary, the work that has been carried out addressing: (a) propagation of Voltage Unbalance from MV to low Voltage (LV) levels; and (b) global emission in MV systems due to line asymmetries, with the view to make contributions for further improving the present technical report.
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Deterministic methodologies for the quantification of Voltage Unbalance propagation in radial and interconnected networks
Iet Generation Transmission & Distribution, 2015Co-Authors: Upuli Jayatunga, Sarath Perera, Phil Ciufo, Ashish P. AgalgaonkarAbstract:Voltage Unbalance propagation is an important aspect in relation to the Voltage Unbalance management process which aims to maintain acceptable Voltage Unbalance levels in the power system. The IEC Technical Report IEC/TR 61000-3-13:2008 incorporates the effects of Voltage Unbalance propagation in the Voltage Unbalance emission allocation methodology by introducing the Voltage Unbalance transfer coefficient, in order to evaluate the influence made by background Voltage Unbalance at the point of evaluation. However, no comprehensive approaches exist in the literature to evaluate these coefficients and the IEC work follows some approximations, which are deduced based on simulations and practical measurements. Recent work completed on Voltage Unbalance emission assessment at the post-connection stage of Unbalanced installations allows separation of the Voltage Unbalance emission contribution made by upstream/surrounding Unbalance sources as a constituent component of the resultant Voltage Unbalance emission level at the point of evaluation. These new methodologies implicitly deal with the important aspects of Voltage Unbalance propagation and allow the quantification of coefficients associated with Voltage Unbalance propagation, which is the main thrust of this study. The theoretical work completed by considering different types of loads in radial and interconnected networks is supplemented by the simulation results.
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Impact of mains connected three-phase induction motor loading levels on network Voltage Unbalance attenuation
2012 IEEE International Conference on Power System Technology (POWERCON), 2012Co-Authors: Upuli Jayatunga, Sarath Perera, Phil CiufoAbstract:Voltage Unbalance (VU) in power systems should be managed in a systematic manner in order to minimise its adverse effects on both customer equipment and supply utilities. It is a well known fact that three-phase induction motor performance can be significantly affected in the presence of supply Voltage Unbalance. It is also known that three-phase induction motors can help to reduce pre-existing network Voltage Unbalance levels. Recently undertaken research aligned with IEC/TR 61000-3-13:2008 Technical Report on Voltage Unbalance management (emission allocation and emission assessment) have quantified the contribution made by induction motors to the net Voltage Unbalance at a point of connection. It is perceived that loading level of three-phase induction motors will have an influence on this contribution. Hence, this study focuses on a sensitivity analysis of induction motor loading level on the Voltage Unbalance emission contribution to the point of connection. Simulation work undertaken indicates that increased loading levels on induction motors tend to exacerbate negative sequence Voltage Unbalance factor (VUF) at the point of connection in comparison to lightly loaded induction motors.
Josep M. Guerrero - One of the best experts on this subject based on the ideXlab platform.
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A control scheme for Voltage Unbalance compensation in an islanded microgrid
Electric Power Systems Research, 2019Co-Authors: Sajad Hoseinnia, Akhbari, Mohsen Hamzeh, Josep M. GuerreroAbstract:Abstract One of the major power quality issues in low-Voltage (LV) microgrids is the Voltage Unbalance which has adverse effects on electrical devices. This paper presents a novel control scheme to mitigate the Voltage Unbalance by a photovoltaic (PV) system. In this study, load current sensors are eliminated and the PV system mitigates the Voltage Unbalance by analyzing its terminal Voltage. This could effectively reduce the cost and complexity of compensation system because of the difficulties of load current sensors. The proposed control strategy is developed for a three-phase PV. As the inverter detects the Voltage Unbalance at its terminal, the proposed control algorithm calculates the compensation reference currents based on the double synchronous reference frame (DSRF) analysis of the PV terminal Voltage. Therefore, the PV inverter injects the compensating currents to the microgrid. The effectiveness of the control scheme is verified by simulation studies in the PSCAD/EMTDC environment.
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autonomous Voltage Unbalance compensation in an islanded droop controlled microgrid
IEEE Transactions on Industrial Electronics, 2013Co-Authors: Mehdi Savaghebi, Alireza Jalilian, Juan C. Vasquez, Josep M. GuerreroAbstract:Recently, there has been an increasing interest in using distributed generators (DGs) not only to inject power into the grid but also to enhance the power quality. In this paper, a stationary-frame control method for Voltage Unbalance compensation in an islanded microgrid is proposed. This method is based on the proper control of DGs interface converters. The DGs are properly controlled to autonomously compensate for Voltage Unbalance while sharing the compensation effort and also active and reactive powers. The control system of the DGs mainly consists of active and reactive power droop controllers, a virtual impedance loop, Voltage and current controllers, and an Unbalance compensator. The design approach of the control system is discussed in detail, and simulation and experimental results are presented. The results demonstrate the effectiveness of the proposed method in the compensation of Voltage Unbalance.
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SmartGridComm - Secondary control for Voltage Unbalance compensation in an islanded microgrid
2011 IEEE International Conference on Smart Grid Communications (SmartGridComm), 2011Co-Authors: Mehdi Savaghebi, Alireza Jalilian, Josep M. Guerrero, Juan C. VasquezAbstract:In this paper, the concept of secondary control is applied for Voltage Unbalance compensation in an islanded microgrid. The aim of the proposed control approach is to enhance the Voltage quality at the point of common coupling (PCC). Unbalance compensation is achieved by proper control of distributed generators (DGs). The DGs control structure mainly consists of active and reactive power controllers, virtual impedance loop and Voltage and current proportional-resonant controllers. Simulation results are presented for different cases. The results show the effectiveness of the proposed approach in the compensation of Voltage Unbalance.
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Hierarchical control scheme for Voltage Unbalance compensation in islanded microgrids
IECON 2011 - 37th Annual Conference of the IEEE Industrial Electronics Society, 2011Co-Authors: Mehdi Savaghebi, Alireza Jalilian, Josep M. Guerrero, Juan C. VasquezAbstract:The concept of microgrid hierarchical control is presented, recently. In this paper, a hierarchical scheme which includes primary and secondary control levels is proposed for islanded microgrids. The primary control level consists of DG local controllers. Local controller of each DG comprises active and reactive power controllers, virtual impedance loop and Voltage and current controllers. The secondary level is designed to compensate the Voltage Unbalance at the load bus (LB) of the islanded microgrid. Also, restoration of LB Voltage amplitude and microgrid frequency to the rated values is considered in the secondary level. These functions are achieved by proper control of distributed generators (DGs) interface converters. The presented simulation results show the effectiveness of the proposed control structure in compensating the Voltage Unbalance and restoring the Voltage amplitude and system frequency.
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experimental evaluation of Voltage Unbalance compensation in an islanded microgrid
International Symposium on Industrial Electronics, 2011Co-Authors: Mehdi Savaghebi, Alireza Jalilian, Josep M. Guerrero, Juan C. VasquezAbstract:In this paper, a method for Voltage Unbalance compensation in an islanded microgrid based on the proper control of distributed generators (DGs) interface converter is proposed. In this method, active and reactive power control loops are considered to control the power sharing among the DGs. Also, a virtual impedance loop and Voltage and current proportional-resonant controllers are included. Experimental results show the effectiveness of the proposed method for compensating Voltage Unbalance to an acceptable level.
Upuli Jayatunga - One of the best experts on this subject based on the ideXlab platform.
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Sensitivity of Network Wide Voltage Unbalance Levels to Variations in Unbalanced Installations
2020 19th International Conference on Harmonics and Quality of Power (ICHQP), 2020Co-Authors: T. D. Kahingala, Sarath Perera, Ashish P. Agalgaonkar, Upuli JayatungaAbstract:Voltage Unbalance (VU) emission assessment is a challenging task due to the complex interactions between the sources of Voltage Unbalance. Consequently, to account for transferred Voltage Unbalance from neighbouring busbars, IEC/TR 61000-3-13 has introduced influence and transfer coefficients in the VU allocation and emission assessment process. However, no generalised practical approaches exist to evaluate these coefficients where as IEC guidelines suggest some approximations based on simulations and field measurements. As an alternative, this paper proposes a sensitivity analysis of network VU to Unbalanced installations that can be employed in VU emission assessment. The proposed methodology uses readily available inputs and utilises a linearised approach to determine the network wide sensitivity of VU to Unbalanced installations which makes it feasible for practical implementation.
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Determining the Impact of Line Asymmetries on Network Voltage Unbalance based on Balanced Load Flow Studies
2018 Australasian Universities Power Engineering Conference (AUPEC), 2018Co-Authors: T. D. Kahingala, Sarath Perera, Ashish P. Agalgaonkar, Upuli JayatungaAbstract:Determining the impact of the individual contributors to network Voltage Unbalance (VU) is a complex task due to the interaction between the sources of Voltage Unbalance in power systems. This becomes further complicated as the network itself contributes to network Voltage Unbalance when it is not symmetrical which is mostly the case in real networks. To account for the network asymmetry, the Technical Report IEC/TR 61000-3-13 which is used for the assessment of Voltage Unbalance emission limits applies a scaling factor K ue when apportioning the global allowance to end user consumers. Studies on the impact of the untransposed overhead lines on each and every individual busbar and on the overall network Voltage Unbalance are essential in: emission allocation studies, identification of power flow constraints, and in decision making related to future investments on VU mitigation. This paper proposes an effective methodology to determine the influence of different untransposed lines based on the results of balanced load flow studies. The methodology can be easily extended to obtain the influence of the other contributors as well.
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Deterministic methodologies for the quantification of Voltage Unbalance propagation in radial and interconnected networks
Iet Generation Transmission & Distribution, 2015Co-Authors: Upuli Jayatunga, Sarath Perera, Phil Ciufo, Ashish P. AgalgaonkarAbstract:Voltage Unbalance propagation is an important aspect in relation to the Voltage Unbalance management process which aims to maintain acceptable Voltage Unbalance levels in the power system. The IEC Technical Report IEC/TR 61000-3-13:2008 incorporates the effects of Voltage Unbalance propagation in the Voltage Unbalance emission allocation methodology by introducing the Voltage Unbalance transfer coefficient, in order to evaluate the influence made by background Voltage Unbalance at the point of evaluation. However, no comprehensive approaches exist in the literature to evaluate these coefficients and the IEC work follows some approximations, which are deduced based on simulations and practical measurements. Recent work completed on Voltage Unbalance emission assessment at the post-connection stage of Unbalanced installations allows separation of the Voltage Unbalance emission contribution made by upstream/surrounding Unbalance sources as a constituent component of the resultant Voltage Unbalance emission level at the point of evaluation. These new methodologies implicitly deal with the important aspects of Voltage Unbalance propagation and allow the quantification of coefficients associated with Voltage Unbalance propagation, which is the main thrust of this study. The theoretical work completed by considering different types of loads in radial and interconnected networks is supplemented by the simulation results.
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Impact of mains connected three-phase induction motor loading levels on network Voltage Unbalance attenuation
2012 IEEE International Conference on Power System Technology (POWERCON), 2012Co-Authors: Upuli Jayatunga, Sarath Perera, Phil CiufoAbstract:Voltage Unbalance (VU) in power systems should be managed in a systematic manner in order to minimise its adverse effects on both customer equipment and supply utilities. It is a well known fact that three-phase induction motor performance can be significantly affected in the presence of supply Voltage Unbalance. It is also known that three-phase induction motors can help to reduce pre-existing network Voltage Unbalance levels. Recently undertaken research aligned with IEC/TR 61000-3-13:2008 Technical Report on Voltage Unbalance management (emission allocation and emission assessment) have quantified the contribution made by induction motors to the net Voltage Unbalance at a point of connection. It is perceived that loading level of three-phase induction motors will have an influence on this contribution. Hence, this study focuses on a sensitivity analysis of induction motor loading level on the Voltage Unbalance emission contribution to the point of connection. Simulation work undertaken indicates that increased loading levels on induction motors tend to exacerbate negative sequence Voltage Unbalance factor (VUF) at the point of connection in comparison to lightly loaded induction motors.
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A review of recent investigations with reference to IEC/TR 61000-3-13 on Voltage Unbalance emission allocation
Proceedings of 14th International Conference on Harmonics and Quality of Power - ICHQP 2010, 2010Co-Authors: P. Paranavithana, Sarath Perera, Upuli Jayatunga, Phil CiufoAbstract:The Technical Report IEC/TR 61000-3-13:2008 provides guiding principles for coordinating Voltage Unbalance between various Voltage levels of a power system through the allocation of emission limits to installations. This report is based on widely accepted concepts and principles in relation to Voltage Unbalance. With regard to some of the key ideas used in this report, investigations have been carried out which have enabled the development of deeper insights making the Voltage Unbalance allocation process more comprehensive. The key aspects which have been considered in detail include: Voltage Unbalance which arises as a result of lines and Voltage Unbalance propagation in HV-MV, MV-LV power systems. In addition, a robust Voltage Unbalance allocation method has been developed which overcomes some difficulties associated where a uniform Voltage Unbalance planning level is adopted across all bus bars with the same Voltage level classification (ie, MV or HV or EHV). With regard to Voltage Unbalance emission assessment a novel technique has also been developed which was verified through the application to an interconnected power system where the methodology allows identification of the contributors to Voltage Unbalance at a selected bus bar.
Robert Koch - One of the best experts on this subject based on the ideXlab platform.
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global Voltage Unbalance in mv networks due to line asymmetries
IEEE Transactions on Power Delivery, 2009Co-Authors: P. Paranavithana, Sarath Perera, Robert Koch, Z EminAbstract:The International Electrotechnical Commission (IEC) has recently released the Technical Report IEC/TR 61000-3-13 for the assessment of Voltage Unbalance emission limits to individual customer installations connected to medium-Voltage (MV), high-Voltage, and extra-high-Voltage power systems. As in the counterpart IEC technical reports for harmonics (IEC 61000-3-6) and flicker (IEC 61000-3-7) allocation, IEC/TR 61000-3-13 also apportions the global emission allowance to customers in proportion to their agreed apparent power. However, noting that Voltage Unbalance at a busbar can arise due to load and system (essentially lines) asymmetries, IEC/TR 61000-3-13 applies a scaling factor Kue to the apportioned allowance. This factor Kue represents the fraction of the global emission allowance that can be allocated to installations. Conversely, the factor K'ue = 1 - Kue accounts for the emission arising as a result of system inherent asymmetries. This paper addresses the global Voltage Unbalance emission in MV power systems arising as a result of line asymmetries on which a systematic evaluation method is not given in IEC/TR 61000-3-13. First, a detailed study with the view to investigate the influence of line asymmetries on the global emission and its dependency on various load types is carried out by employing a simple radial network. Second, a matrix-based methodology, covering radial and interconnected networks, for the assessment of this emission at the nodal level taking line, system and load characteristics, system operating conditions, and downstream load composition into account are proposed. The methodology is verified by using Unbalance load-flow analysis.
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A generalised methodology for evaluating Voltage Unbalance influence coefficients
IET Conference Publications, 2009Co-Authors: P. Paranavithana, Sarath Perera, Robert KochAbstract:The recently released IEC Technical Report IEC/TR 610003-13 for Voltage Unbalance allocation requires quantitative measures of the propagation of Voltage Unbalance from one busbar to other neighbouring busbars of a sub-system in terms of influence coefficienst. However, IEC/TR 61000-313 does not prescribe a method for their evaluation. This paper carries out preliminary studies in order to investigate the dependency of these influence coefficients on various load types/bases, and proposes a systematic method for estimating them. Proposed method is applied to a 3-bus MV test system and also to the IEEE 14-bus test system of which the results are verified using Unbalanced load flow analysis. This new approach could be considered in future updates of IEC/TR 61000-3-13.
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Propagation of Voltage Unbalance from HV to MV power systems
IET Conference Publications, 2009Co-Authors: P. Paranavithana, Sarath Perera, Robert KochAbstract:The recently released IEC Technical Report IEC/TR 61000-3-13 for Voltage Unbalance allocation requires quantitative measures of the propagation of Voltage Unbalance from higher Voltage to lower Voltage power systems in terms of transfer coefficients. IEC/TR 61000-3-13 indicates a method for estimating the MV to LV transfer coefficient giving it a value of unity for passive loads in general. This value has been seen to be conservative in the presence of commonly prevailing constant power loads. As a continuation of the work that has been carried out to develop an improved method which overcomes the above limitation for estimating the MV to LV transfer coefficient, this paper addresses the propagation of Voltage Unbalance from HV to MV power systems. Paper reports on a systematic method for estimating the HV to MV transfer coefficient in terms of system and load characteristics and downstream load composition, which could be considered in future updates of IEC/TR 61000-3-13.
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An improved methodology for determining MV to LV Voltage Unbalance transfer coefficient
2008 13th International Conference on Harmonics and Quality of Power, 2008Co-Authors: P. Paranavithana, Sarath Perera, Robert KochAbstract:The International Electrotechnical Commission (IEC) has recently released a technical report (IEC/TR 61000-3-13, Ed. 1.0, 2008) in relation to the assessment of Voltage Unbalance emission by installations connected to MV, HV and EHV power systems. As in the cases of harmonics and flicker, this requires a quantitative measure of propagation of Voltage Unbalance from upstream (higher Voltage) to downstream (lower Voltage) systems in terms of transfer coefficients. Naturally, these transfer coefficients depend on the downstream load composition. The existing method for determining MV to LV Voltage Unbalance transfer coefficient suggests a value of unity in relation to passive loads in general. However, this paper reports that MV to LV transfer coefficient of unity is conservative in the presence of commonly prevailing constant power loads. Further, the paper reports on an improved methodology for estimating MV to LV Voltage Unbalance transfer coefficient taking system and load characteristics into account.
