Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398645
L. Shpanin, G. Jones, N. Shammas, J. Humphries, S. Tennakoon, J. W. Spencer
This paper describes a novel technique for interrupting direct currents (D.C.) with an electromagnetically convoluted arc in air at atmospheric pressure. Investigations are reported on the effects of using a separate current for producing the arc convolving electromagnetic field (B-field) to that being interrupted and using a separate R, L, C circuit in parallel with the arc contacts. Experimental results are presented for the time variation of currents flowing through the arc gap, the B-field coil and the parallel R, L, C circuit, along with the voltage across the arc gap.
{"title":"Electromagnetically convoluted arcs for the interruption of quasi direct current","authors":"L. Shpanin, G. Jones, N. Shammas, J. Humphries, S. Tennakoon, J. W. Spencer","doi":"10.1109/UPEC.2012.6398645","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398645","url":null,"abstract":"This paper describes a novel technique for interrupting direct currents (D.C.) with an electromagnetically convoluted arc in air at atmospheric pressure. Investigations are reported on the effects of using a separate current for producing the arc convolving electromagnetic field (B-field) to that being interrupted and using a separate R, L, C circuit in parallel with the arc contacts. Experimental results are presented for the time variation of currents flowing through the arc gap, the B-field coil and the parallel R, L, C circuit, along with the voltage across the arc gap.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"227 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134481995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398421
P. Mikropoulos, V. Zagkanas, T. S. Koustoulidis
Knowledge on the effects of air density on corona discharge is of great importance for many practical applications, including overhead transmission lines. In the present study the salient characteristics of both positive and negative DC corona on 7-stranded conductors, namely the corona inception voltage, corona current and the associated power losses, are experimentally investigated in the coaxial cylindrical electrode arrangement under variable air density. Theoretical predictions of the corona current and losses are in good agreement with experimental values for an ion mobility decreasing with relative air density according to a power law, the rate of decrease being higher for negative than positive ions. Irregularity factors for the 7-stranded conductors have been obtained based on electric field simulations and Peek's formula for smooth conductors. Logarithmic expressions, describing well the dependence of the irregularity factor on the product of relative air density and conductor radius, allow for a satisfactory estimation of the corona inception field strength of 7-stranded conductors.
{"title":"Experimental investigation of DC corona on stranded conductors under variable air density","authors":"P. Mikropoulos, V. Zagkanas, T. S. Koustoulidis","doi":"10.1109/UPEC.2012.6398421","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398421","url":null,"abstract":"Knowledge on the effects of air density on corona discharge is of great importance for many practical applications, including overhead transmission lines. In the present study the salient characteristics of both positive and negative DC corona on 7-stranded conductors, namely the corona inception voltage, corona current and the associated power losses, are experimentally investigated in the coaxial cylindrical electrode arrangement under variable air density. Theoretical predictions of the corona current and losses are in good agreement with experimental values for an ion mobility decreasing with relative air density according to a power law, the rate of decrease being higher for negative than positive ions. Irregularity factors for the 7-stranded conductors have been obtained based on electric field simulations and Peek's formula for smooth conductors. Logarithmic expressions, describing well the dependence of the irregularity factor on the product of relative air density and conductor radius, allow for a satisfactory estimation of the corona inception field strength of 7-stranded conductors.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133498322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398652
I. Zamani, M. Irving
Increasing share of distribution generation in electrical energy supply has made the distributed energy resource planning (DER) more significant as improper placement, capacity or number of distributed generation (DG) units in power systems would increase power loss as well as jeopardizing the system operation. Diversities and conflicting nature of objectives, uncertainties about benefits or drawbacks of the existing optimization techniques, and suitability for discreet domain problems project more appeal in the invention of efficient and robust techniques in resource planning. In this paper, a new application of multi-objective optimization techniques for sitting and sizing of potential resources (DGs) has been investigated. The system is modeled in Matlab using a fast non-dominated sorting genetic algorithm (NSGA-II) and Matpower within a planning horizon. The capital and running cost of DGs have been considered in the planning period. The results show that the proposed multi-objective framework permits diversity of solutions, requiring minimum number of objective functions to yield a better voltage profile and more independency from the main grid.
{"title":"A novel approach to distributed energy resource planning using NSGA-II","authors":"I. Zamani, M. Irving","doi":"10.1109/UPEC.2012.6398652","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398652","url":null,"abstract":"Increasing share of distribution generation in electrical energy supply has made the distributed energy resource planning (DER) more significant as improper placement, capacity or number of distributed generation (DG) units in power systems would increase power loss as well as jeopardizing the system operation. Diversities and conflicting nature of objectives, uncertainties about benefits or drawbacks of the existing optimization techniques, and suitability for discreet domain problems project more appeal in the invention of efficient and robust techniques in resource planning. In this paper, a new application of multi-objective optimization techniques for sitting and sizing of potential resources (DGs) has been investigated. The system is modeled in Matlab using a fast non-dominated sorting genetic algorithm (NSGA-II) and Matpower within a planning horizon. The capital and running cost of DGs have been considered in the planning period. The results show that the proposed multi-objective framework permits diversity of solutions, requiring minimum number of objective functions to yield a better voltage profile and more independency from the main grid.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117268427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398633
K. Elnaddab, A. Haddad, H. Griffiths
In many cases, large renewable energy sources of electrical power such as offshore wind farms will need to be connected to existing onshore transmission networks. Several gigawatts of electrical power need to be transferred from the wind farms to the grid, which requires reliable, low loss and high transmission capacity networks. Gas Insulated Transmission Lines (GILs) have higher transmission capacities, low losses, and higher overload capacities than other cable technologies which are needed to transmit offshore generated power to the mainland. This paper gives an overview of existing GIL and explores the challenges for long distance applications. Furthermore, analytical and computer models have been developed to assess the suitability of GIL and quantify the voltage, current and power transfer characteristics of the GIL with length. The paper describes the computed results of voltage, current and power profiles for a case study GIL operating at 400 kV for lengths up to 500 km.
{"title":"The transmission characteristics of gas insulated lines (GIL) over long distance","authors":"K. Elnaddab, A. Haddad, H. Griffiths","doi":"10.1109/UPEC.2012.6398633","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398633","url":null,"abstract":"In many cases, large renewable energy sources of electrical power such as offshore wind farms will need to be connected to existing onshore transmission networks. Several gigawatts of electrical power need to be transferred from the wind farms to the grid, which requires reliable, low loss and high transmission capacity networks. Gas Insulated Transmission Lines (GILs) have higher transmission capacities, low losses, and higher overload capacities than other cable technologies which are needed to transmit offshore generated power to the mainland. This paper gives an overview of existing GIL and explores the challenges for long distance applications. Furthermore, analytical and computer models have been developed to assess the suitability of GIL and quantify the voltage, current and power transfer characteristics of the GIL with length. The paper describes the computed results of voltage, current and power profiles for a case study GIL operating at 400 kV for lengths up to 500 km.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115368822","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398425
F. Moore, A. Haddad, H. Griffiths, M. Osborne
The inductive voltage transformers (VTs) used on the power system are primarily designed for protection or metering at 50Hz. The leakage inductance of the VT windings and stray capacitances can form a resonant circuit. When subjected to AC voltages at frequencies well below resonance, the VT can be assumed to behave linearly giving accurate measurements. The resonance of the VT limits the bandwidth over which it may be used to provide accurate measurements. This is of particular importance when taking harmonic and transient measurements. This paper reviews the different kinds of VT model available. A model is selected for transient simulation in EMTP, and the influence of the VT model on switching transients is examined. A key observation is that when the inductive VT model is subjected to a step change in voltage, a voltage ripple is introduced at the VT's resonant frequency to its secondary winding. The aim of this work is to quantify the influence of the inductive VTs on measured transient voltage waveforms.
{"title":"Influence of inductive voltage transformers on the measurement of switching transients","authors":"F. Moore, A. Haddad, H. Griffiths, M. Osborne","doi":"10.1109/UPEC.2012.6398425","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398425","url":null,"abstract":"The inductive voltage transformers (VTs) used on the power system are primarily designed for protection or metering at 50Hz. The leakage inductance of the VT windings and stray capacitances can form a resonant circuit. When subjected to AC voltages at frequencies well below resonance, the VT can be assumed to behave linearly giving accurate measurements. The resonance of the VT limits the bandwidth over which it may be used to provide accurate measurements. This is of particular importance when taking harmonic and transient measurements. This paper reviews the different kinds of VT model available. A model is selected for transient simulation in EMTP, and the influence of the VT model on switching transients is examined. A key observation is that when the inductive VT model is subjected to a step change in voltage, a voltage ripple is introduced at the VT's resonant frequency to its secondary winding. The aim of this work is to quantify the influence of the inductive VTs on measured transient voltage waveforms.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"428 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115648188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398422
A. Cagnano, E. De Tuglie, M. Dicorato, G. Forte, M. Trovato
This paper deals with the development of a centralized nonlinear auto-adaptive controller able to optimize the network voltage profile by managing the reactive power supplied by PV inverters. The control design is based on a realtime optimization procedure involving the sensitivity theory in conjunction with the Lyapunov function and produces the control laws that must be sent to local controllers of PV-inverters. The derived controller is implemented and tested on a MV distribution network.
{"title":"PV plants for voltage regulation in distribution networks","authors":"A. Cagnano, E. De Tuglie, M. Dicorato, G. Forte, M. Trovato","doi":"10.1109/UPEC.2012.6398422","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398422","url":null,"abstract":"This paper deals with the development of a centralized nonlinear auto-adaptive controller able to optimize the network voltage profile by managing the reactive power supplied by PV inverters. The control design is based on a realtime optimization procedure involving the sensitivity theory in conjunction with the Lyapunov function and produces the control laws that must be sent to local controllers of PV-inverters. The derived controller is implemented and tested on a MV distribution network.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122010954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398572
F. Pellitteri, V. Boscaino, R. L. Rosa, G. Capponi
In this paper, a wireless charger for portable electronics devices is presented. A power transmitter, also known as the magnetic pad, and a power receiver are magnetically coupled. A receiver architecture which improves the power conversion efficiency is proposed. All advantages brought by the proposed architecture are discussed and standard constraints are presented as well. The receiver is fully standard-compliant. A wireless station for mobile application is designed and tested. Simulation and experimental results are compared. As shown by experimental results, thanks to the proposed architecture the power conversion efficiency of the receiver section is really close to a unit value. Power losses on the receiver side could be reasonably neglected. The wireless station efficiency now depends on the inductive coupling losses only.
{"title":"Improving the efficiency of a standard compliant wireless battery charger","authors":"F. Pellitteri, V. Boscaino, R. L. Rosa, G. Capponi","doi":"10.1109/UPEC.2012.6398572","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398572","url":null,"abstract":"In this paper, a wireless charger for portable electronics devices is presented. A power transmitter, also known as the magnetic pad, and a power receiver are magnetically coupled. A receiver architecture which improves the power conversion efficiency is proposed. All advantages brought by the proposed architecture are discussed and standard constraints are presented as well. The receiver is fully standard-compliant. A wireless station for mobile application is designed and tested. Simulation and experimental results are compared. As shown by experimental results, thanks to the proposed architecture the power conversion efficiency of the receiver section is really close to a unit value. Power losses on the receiver side could be reasonably neglected. The wireless station efficiency now depends on the inductive coupling losses only.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125073547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398685
S. Armstrong, D. Mollaghan, A. Blavette, D. O'Sullivan
Environmental concerns, coupled with dwindling fossil fuel supplies, and growing government support, have resulted in increasing amounts of electricity generated from renewable energy. As the number of these installations rise, their influence on the behaviour of the electrical power system becomes more apparent. Transmission System Operators (TSO) carry out power system dynamic simulations in order to investigate the effect of renewable energy systems on the stability and reliability of the grid under varying operating conditions. Correct initialisation is an essential step in the dynamic model. This paper describes a three step methodology for correct initialisation of power systems dynamic model for an ocean energy system. The methodology is validated using DIgSILENT Power Factory simulations.
对环境的担忧，再加上化石燃料供应的减少，以及政府越来越多的支持，导致了可再生能源发电量的增加。随着这些装置数量的增加，它们对电力系统行为的影响变得更加明显。输电系统运营商(TSO)对电力系统进行动态仿真，以研究可再生能源系统在不同运行条件下对电网稳定性和可靠性的影响。正确的初始化是动态模型中必不可少的一步。本文介绍了海洋能源系统动力系统动力学模型正确初始化的三步法。该方法通过DIgSILENT Power Factory仿真得到验证。
{"title":"An initialisation methodology for ocean energy converter dynamic models in power system simulation tools","authors":"S. Armstrong, D. Mollaghan, A. Blavette, D. O'Sullivan","doi":"10.1109/UPEC.2012.6398685","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398685","url":null,"abstract":"Environmental concerns, coupled with dwindling fossil fuel supplies, and growing government support, have resulted in increasing amounts of electricity generated from renewable energy. As the number of these installations rise, their influence on the behaviour of the electrical power system becomes more apparent. Transmission System Operators (TSO) carry out power system dynamic simulations in order to investigate the effect of renewable energy systems on the stability and reliability of the grid under varying operating conditions. Correct initialisation is an essential step in the dynamic model. This paper describes a three step methodology for correct initialisation of power systems dynamic model for an ocean energy system. The methodology is validated using DIgSILENT Power Factory simulations.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123320554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398654
F. Parillo
In this paper are described a PI controller and an Active Filtering control strategy, applied to a Dual Boost Power Factor Correction (PFC) implementation, on a low cost FPGA device, using a custom developed sfloat24 math library. The implemented control strategy consists in an optimized power sharing where the active filtering approach is used to increase the current quality and at the same time to reduce the switching losses. The simulation results show that the sfloat24 floating point, IEEE 754 compliant, digital PI controller and the active filtering approach outperform by high-speed response, better precision, minor error and high dynamic range. Both the simulation and experimental results show that the adopted control strategy for PFC achieves near unity power factor and a not negligible switching losses reduction.
{"title":"Dual boost high performances Power Factor Correction (PFC) control strategy implemented on a low cost FPGA device, using a custom sfloat24 developed math library","authors":"F. Parillo","doi":"10.1109/UPEC.2012.6398654","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398654","url":null,"abstract":"In this paper are described a PI controller and an Active Filtering control strategy, applied to a Dual Boost Power Factor Correction (PFC) implementation, on a low cost FPGA device, using a custom developed sfloat24 math library. The implemented control strategy consists in an optimized power sharing where the active filtering approach is used to increase the current quality and at the same time to reduce the switching losses. The simulation results show that the sfloat24 floating point, IEEE 754 compliant, digital PI controller and the active filtering approach outperform by high-speed response, better precision, minor error and high dynamic range. Both the simulation and experimental results show that the adopted control strategy for PFC achieves near unity power factor and a not negligible switching losses reduction.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128986375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-12-31DOI: 10.1109/UPEC.2012.6398587
F. Olobaniyi, Hassan NOURI, S. Ghauri
The resourcefulness of Diakoptics as a tool with the potential ability to meet the challenges of modern power system analysis is outlined. The benefits include the generally accepted saving in computation time, but higher accuracy and the ability to use multicomputer configurations in analyses are highlighted. One of the reasons for the non-acceptance of Diakoptics as a universal tool is said to be the difficulty in understanding the concept. The concept is demonstrated using simple illustrative examples that are easy to understand and verify.
{"title":"Investigation of Diakoptics as a resourceful tool in power system analysis","authors":"F. Olobaniyi, Hassan NOURI, S. Ghauri","doi":"10.1109/UPEC.2012.6398587","DOIUrl":"https://doi.org/10.1109/UPEC.2012.6398587","url":null,"abstract":"The resourcefulness of Diakoptics as a tool with the potential ability to meet the challenges of modern power system analysis is outlined. The benefits include the generally accepted saving in computation time, but higher accuracy and the ability to use multicomputer configurations in analyses are highlighted. One of the reasons for the non-acceptance of Diakoptics as a universal tool is said to be the difficulty in understanding the concept. The concept is demonstrated using simple illustrative examples that are easy to understand and verify.","PeriodicalId":326950,"journal":{"name":"2012 47th International Universities Power Engineering Conference (UPEC)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130507950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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