Pub Date : 2004-05-12DOI: 10.1109/MELCON.2004.1348203
J. L. Santos, F. Barbosa
The increasing loads, the great distances between the production and consumption centers as well as the state of the transport and distribution networks turns the electrical power system operating near its stability limit. When the system gets unstable a blackout situation may occur, which is critical to the system operator and consumers. We have recent examples in United States and Italy where the system was without power for several hours, causing serious problems in hospitals and public transportations. One of the causes of a blackout may be the voltage instability, which turns this subject widely discussed and studied. The speed of evolution of the voltage stability phenomenon allows us to analyze the problem as a static problem rather than a transitory one Kundur, P et al. (1983). This article will show one way to "measure" locally the proximity of the system to the voltage stability limit.
{"title":"Voltage stability evaluation using the the relation between impedances","authors":"J. L. Santos, F. Barbosa","doi":"10.1109/MELCON.2004.1348203","DOIUrl":"https://doi.org/10.1109/MELCON.2004.1348203","url":null,"abstract":"The increasing loads, the great distances between the production and consumption centers as well as the state of the transport and distribution networks turns the electrical power system operating near its stability limit. When the system gets unstable a blackout situation may occur, which is critical to the system operator and consumers. We have recent examples in United States and Italy where the system was without power for several hours, causing serious problems in hospitals and public transportations. One of the causes of a blackout may be the voltage instability, which turns this subject widely discussed and studied. The speed of evolution of the voltage stability phenomenon allows us to analyze the problem as a static problem rather than a transitory one Kundur, P et al. (1983). This article will show one way to \"measure\" locally the proximity of the system to the voltage stability limit.","PeriodicalId":164818,"journal":{"name":"Proceedings of the 12th IEEE Mediterranean Electrotechnical Conference (IEEE Cat. No.04CH37521)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124512244","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 : 2004-05-12DOI: 10.1109/MELCON.2004.1348219
N. Berbic, A. Nuhanovic, V. Madžarević
The common cases of a nonselective operation of the phase to ground fault protection in the insulated power grids, which utilize inductive sensors for a voltage unbalance indication, are explained by ferroresonant processes in voltage transformers of healthy drains. This paper deals with phase to ground faults simulations in a known grid, that provide information about possible nonselective phase to ground faults protection operation.
{"title":"Analysis of the insulated power-grid transient behavior after faulted phase tripping","authors":"N. Berbic, A. Nuhanovic, V. Madžarević","doi":"10.1109/MELCON.2004.1348219","DOIUrl":"https://doi.org/10.1109/MELCON.2004.1348219","url":null,"abstract":"The common cases of a nonselective operation of the phase to ground fault protection in the insulated power grids, which utilize inductive sensors for a voltage unbalance indication, are explained by ferroresonant processes in voltage transformers of healthy drains. This paper deals with phase to ground faults simulations in a known grid, that provide information about possible nonselective phase to ground faults protection operation.","PeriodicalId":164818,"journal":{"name":"Proceedings of the 12th IEEE Mediterranean Electrotechnical Conference (IEEE Cat. No.04CH37521)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124804283","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 : 2004-05-12DOI: 10.1109/MELCON.2004.1346879
M. Rao, H. Hassan
In the design of model reference adaptive control (MRAC) schemes, adaptive laws have been developed based on Lyapunov stability theory. Over the past few decades, it has been a common practice to use quadratic Lyapunov functions (QLF). In contrast to such development, using a new nonquadratic Lyapunov function (NQLF), this paper presents new adaptive laws for the MRAC. These new laws have the same advantage of assurance of stability of the overall system, as the earlier adaptive laws developed using the QLF. Over and above, they have an additional advantage of improved performance: in fact, the use of NQLF improved the system output error signal converging to zero. Finally, this paper also presents simulation results supporting the arguments.
{"title":"New adaptive laws for model reference adaptive control using a non-quadratic Lyapunov function","authors":"M. Rao, H. Hassan","doi":"10.1109/MELCON.2004.1346879","DOIUrl":"https://doi.org/10.1109/MELCON.2004.1346879","url":null,"abstract":"In the design of model reference adaptive control (MRAC) schemes, adaptive laws have been developed based on Lyapunov stability theory. Over the past few decades, it has been a common practice to use quadratic Lyapunov functions (QLF). In contrast to such development, using a new nonquadratic Lyapunov function (NQLF), this paper presents new adaptive laws for the MRAC. These new laws have the same advantage of assurance of stability of the overall system, as the earlier adaptive laws developed using the QLF. Over and above, they have an additional advantage of improved performance: in fact, the use of NQLF improved the system output error signal converging to zero. Finally, this paper also presents simulation results supporting the arguments.","PeriodicalId":164818,"journal":{"name":"Proceedings of the 12th IEEE Mediterranean Electrotechnical Conference (IEEE Cat. No.04CH37521)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129809058","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 : 2004-05-12DOI: 10.1109/MELCON.2004.1346794
A. Hatzopoulos, P. Bougia
A design tool in skill language is described in this work, which enhances the RF design and simulation capabilities of the Cadence software. The tool can design the layout of planar inductors and patterned ground shields (at poly layer and also at the n-diffusion or n-well layer) which improve the performance of the inductor. The electrical models that have been included for the simulations are described. Comparative simulation results verify the proper operation of the tool and, thus, it can be included in the Cadence software to facilitate RF designers.
{"title":"A design tool for planar inductors using Cadence software","authors":"A. Hatzopoulos, P. Bougia","doi":"10.1109/MELCON.2004.1346794","DOIUrl":"https://doi.org/10.1109/MELCON.2004.1346794","url":null,"abstract":"A design tool in skill language is described in this work, which enhances the RF design and simulation capabilities of the Cadence software. The tool can design the layout of planar inductors and patterned ground shields (at poly layer and also at the n-diffusion or n-well layer) which improve the performance of the inductor. The electrical models that have been included for the simulations are described. Comparative simulation results verify the proper operation of the tool and, thus, it can be included in the Cadence software to facilitate RF designers.","PeriodicalId":164818,"journal":{"name":"Proceedings of the 12th IEEE Mediterranean Electrotechnical Conference (IEEE Cat. No.04CH37521)","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127032332","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 : 2004-05-12DOI: 10.1109/MELCON.2004.1346780
M. Loikkanene, J. Kostamovaara
An adaptively biased amplifier and an adaptive biasing block with almost supply independent behavior are described. Bias currents of the amplifier are adjusted by sensing the input signal amplitude. This adjustment together with a time dependency added to the biasing network causes the adaptively biased amplifier to have approximately the same bandwidth and the same relative stability for large signals as its linear counterpart biased with much higher currents. Simulation results in a 0.35/spl mu/m CMOS process show that in this way significant power reduction can be achieved, especially in applications where load capacitance is large.
{"title":"Adaptively biased two-stage amplifier","authors":"M. Loikkanene, J. Kostamovaara","doi":"10.1109/MELCON.2004.1346780","DOIUrl":"https://doi.org/10.1109/MELCON.2004.1346780","url":null,"abstract":"An adaptively biased amplifier and an adaptive biasing block with almost supply independent behavior are described. Bias currents of the amplifier are adjusted by sensing the input signal amplitude. This adjustment together with a time dependency added to the biasing network causes the adaptively biased amplifier to have approximately the same bandwidth and the same relative stability for large signals as its linear counterpart biased with much higher currents. Simulation results in a 0.35/spl mu/m CMOS process show that in this way significant power reduction can be achieved, especially in applications where load capacitance is large.","PeriodicalId":164818,"journal":{"name":"Proceedings of the 12th IEEE Mediterranean Electrotechnical Conference (IEEE Cat. No.04CH37521)","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129014117","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 : 2004-05-12DOI: 10.1109/MELCON.2004.1346987
A. Michalas, M. Louta, V. Loumus
In order to achieve absolute QoS guarantees in the DiffServ architecture, admission control procedures have been developed. Their role is to ensure that the admittance of a new flow into the network does not violate service commitments of already established flows and the network could satisfy the constraints of the new flow. In this paper we discuss related work of parameter and measurement based admission control techniques, while a set of results indicative of their performance is provided.
{"title":"Efficient call admission control methods in DiffServ architecture","authors":"A. Michalas, M. Louta, V. Loumus","doi":"10.1109/MELCON.2004.1346987","DOIUrl":"https://doi.org/10.1109/MELCON.2004.1346987","url":null,"abstract":"In order to achieve absolute QoS guarantees in the DiffServ architecture, admission control procedures have been developed. Their role is to ensure that the admittance of a new flow into the network does not violate service commitments of already established flows and the network could satisfy the constraints of the new flow. In this paper we discuss related work of parameter and measurement based admission control techniques, while a set of results indicative of their performance is provided.","PeriodicalId":164818,"journal":{"name":"Proceedings of the 12th IEEE Mediterranean Electrotechnical Conference (IEEE Cat. No.04CH37521)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126649603","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 : 2004-05-12DOI: 10.1109/MELCON.2004.1348248
B. Blazic, I. Papič
This paper proposes a control technique for minimizing the effect of a distorted DC-bus voltage on the operation of a PWM controlled STATCOM. A DC-bus voltage ripple occurs as a consequence of harmonic or unbalanced currents exchange between the compensator and the network and causes additional harmonic distortion on the AC side, which is not permissible for compensator operation. The proposed DC-ripple mitigation technique is based on the modulation of the switching function enabling the device operation with distorted DC-bus voltage and allowing the use of a relatively small capacitor on the DC side. The derived control algorithm is validated by means of digital simulation in the PSCAD/EMTDC program where a case of a STATCOM operating under unbalanced conditions (unbalanced network voltage) was evaluated.
{"title":"Minimizing the effect of a distorted DC-bus voltage of a STATCOM","authors":"B. Blazic, I. Papič","doi":"10.1109/MELCON.2004.1348248","DOIUrl":"https://doi.org/10.1109/MELCON.2004.1348248","url":null,"abstract":"This paper proposes a control technique for minimizing the effect of a distorted DC-bus voltage on the operation of a PWM controlled STATCOM. A DC-bus voltage ripple occurs as a consequence of harmonic or unbalanced currents exchange between the compensator and the network and causes additional harmonic distortion on the AC side, which is not permissible for compensator operation. The proposed DC-ripple mitigation technique is based on the modulation of the switching function enabling the device operation with distorted DC-bus voltage and allowing the use of a relatively small capacitor on the DC side. The derived control algorithm is validated by means of digital simulation in the PSCAD/EMTDC program where a case of a STATCOM operating under unbalanced conditions (unbalanced network voltage) was evaluated.","PeriodicalId":164818,"journal":{"name":"Proceedings of the 12th IEEE Mediterranean Electrotechnical Conference (IEEE Cat. No.04CH37521)","volume":"470 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123879826","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 : 2004-05-12DOI: 10.1109/MELCON.2004.1346990
I. Dudas, L. Bokor, Gabor Bilek, S. Imre, Sandor Szab, G. Jeney
This paper introduces a new method how mobile IPv6 protocol can be extended easily to work efficiently in the case of micromobility environment. The proposed method reduces the volume of control messages during the mobile operation and results more seamless handover helping real-time applications.
{"title":"Examining anycast address supported mobility management using mobile IPv6 testbed","authors":"I. Dudas, L. Bokor, Gabor Bilek, S. Imre, Sandor Szab, G. Jeney","doi":"10.1109/MELCON.2004.1346990","DOIUrl":"https://doi.org/10.1109/MELCON.2004.1346990","url":null,"abstract":"This paper introduces a new method how mobile IPv6 protocol can be extended easily to work efficiently in the case of micromobility environment. The proposed method reduces the volume of control messages during the mobile operation and results more seamless handover helping real-time applications.","PeriodicalId":164818,"journal":{"name":"Proceedings of the 12th IEEE Mediterranean Electrotechnical Conference (IEEE Cat. No.04CH37521)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131195340","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 : 2004-05-12DOI: 10.1109/MELCON.2004.1348083
M. Glavic, I. Džafić, S. Tesnjak
In this paper a methodology that handles a wide range of flow limits by extension and formulation of a continuation power flow so that include generator redispatch when a flow on a given line exceeds some specified limit, is proposed. Four options for active generation redispatch are introduced: based on topology analysis, sensitivity studies, generator margins, and cost considerations. The applicability of the methodology in deregulated environments for operating a power system within its security constraints is discussed in the paper. The power system model is based on a computationally efficient point of collapse power flow. Results of the tests obtained with help of the IEEE-39 and IEEE-118 bus systems are given to illustrate the performance of the methodology.
{"title":"Handling flow limits during maximum loadability determination","authors":"M. Glavic, I. Džafić, S. Tesnjak","doi":"10.1109/MELCON.2004.1348083","DOIUrl":"https://doi.org/10.1109/MELCON.2004.1348083","url":null,"abstract":"In this paper a methodology that handles a wide range of flow limits by extension and formulation of a continuation power flow so that include generator redispatch when a flow on a given line exceeds some specified limit, is proposed. Four options for active generation redispatch are introduced: based on topology analysis, sensitivity studies, generator margins, and cost considerations. The applicability of the methodology in deregulated environments for operating a power system within its security constraints is discussed in the paper. The power system model is based on a computationally efficient point of collapse power flow. Results of the tests obtained with help of the IEEE-39 and IEEE-118 bus systems are given to illustrate the performance of the methodology.","PeriodicalId":164818,"journal":{"name":"Proceedings of the 12th IEEE Mediterranean Electrotechnical Conference (IEEE Cat. No.04CH37521)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131643588","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 : 2004-05-12DOI: 10.1109/MELCON.2004.1346876
Ž. Jurić, B. Perunicic
This paper proposes a generalization of the Ziegler-Nichol's (ZN) method which allows parametric identification of a linear plant modeled with one of the simplified standard models of the transfer function. The proposed method, like the standard ZN method, requires only a standard PI or PID controller, without any extra equipment. Moreover, the proposed method allows the identification even if the sustained undamped oscillations are not allowed in the plant. However, more experiments are required in this case.
{"title":"An extension of the Ziegler-Nichol's method for parametric identification of standard plants","authors":"Ž. Jurić, B. Perunicic","doi":"10.1109/MELCON.2004.1346876","DOIUrl":"https://doi.org/10.1109/MELCON.2004.1346876","url":null,"abstract":"This paper proposes a generalization of the Ziegler-Nichol's (ZN) method which allows parametric identification of a linear plant modeled with one of the simplified standard models of the transfer function. The proposed method, like the standard ZN method, requires only a standard PI or PID controller, without any extra equipment. Moreover, the proposed method allows the identification even if the sustained undamped oscillations are not allowed in the plant. However, more experiments are required in this case.","PeriodicalId":164818,"journal":{"name":"Proceedings of the 12th IEEE Mediterranean Electrotechnical Conference (IEEE Cat. No.04CH37521)","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127566895","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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