P. Georgilakis, N. Hatziargyriou, D. Paparigas, J. Bakopoulos
A new approach using neural networks and genetic algorithms to solve the transformer iron loss reduction problem is proposed in this paper. Neural networks are used to predict iron losses of wound core distribution transformers at the early stages of transformer construction. Moreover, genetic algorithms are combined with neural networks in order to improve the grouping process of the individual cores by reducing iron losses of assembled transformers. Results from the application of the proposed method on a transformer industry demonstrate the feasibility and practicality of this approach.
{"title":"On-line combined use of neural networks and genetic algorithms to the solution of transformer iron loss reduction problem","authors":"P. Georgilakis, N. Hatziargyriou, D. Paparigas, J. Bakopoulos","doi":"10.1109/PTC.1999.826586","DOIUrl":"https://doi.org/10.1109/PTC.1999.826586","url":null,"abstract":"A new approach using neural networks and genetic algorithms to solve the transformer iron loss reduction problem is proposed in this paper. Neural networks are used to predict iron losses of wound core distribution transformers at the early stages of transformer construction. Moreover, genetic algorithms are combined with neural networks in order to improve the grouping process of the individual cores by reducing iron losses of assembled transformers. Results from the application of the proposed method on a transformer industry demonstrate the feasibility and practicality of this approach.","PeriodicalId":101688,"journal":{"name":"PowerTech Budapest 99. Abstract Records. (Cat. No.99EX376)","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122677419","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}
Transformer technology is a mature technology. A characteristic of such technologies is that most advances tend to be incremental. Improvements also are often related to the demands of the 20th century manufacturing techniques rather than to the fundamental physics governing the concept. Returning to basic physics and for example reconsidering Maxwell's equations opens new possibilities for efficient design. Additionally, safety and environmental issues, much more relevant now than in the early 1900s, can be addressed in a new way. The new technology that is presented in this work describes the resulting revolutionary changes for both manufacturer and user. High voltage dry power transformers replace conventional power transformer technology based on oil/cellulosic insulation. The marriage of the well-proven high voltage power cable technology with transformer technology sets a new standard in reaching the environmental goals of the 21st century.
{"title":"Power transformers for the 21st century","authors":"A. Jaksts, S. Forsmark, M. Leijon","doi":"10.1109/PTC.1999.826483","DOIUrl":"https://doi.org/10.1109/PTC.1999.826483","url":null,"abstract":"Transformer technology is a mature technology. A characteristic of such technologies is that most advances tend to be incremental. Improvements also are often related to the demands of the 20th century manufacturing techniques rather than to the fundamental physics governing the concept. Returning to basic physics and for example reconsidering Maxwell's equations opens new possibilities for efficient design. Additionally, safety and environmental issues, much more relevant now than in the early 1900s, can be addressed in a new way. The new technology that is presented in this work describes the resulting revolutionary changes for both manufacturer and user. High voltage dry power transformers replace conventional power transformer technology based on oil/cellulosic insulation. The marriage of the well-proven high voltage power cable technology with transformer technology sets a new standard in reaching the environmental goals of the 21st century.","PeriodicalId":101688,"journal":{"name":"PowerTech Budapest 99. Abstract Records. (Cat. No.99EX376)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126093404","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}
D. Popović, D. Dobrijević, N. Mijuskovic, D.J. Vlaisuvijevic
The relevant methodological and practical aspects of steady-state security assessment of Yugoslav Power System are presented in this paper. This methodology consists of a procedure for forming the unified external network equivalents, procedure for fast contingency selection and simple method for the fast assessment of dynamic change of power system frequency. Full contingency analysis is based on a specially developed method, which enables successive solution of the load-flow problem for a set of characteristic post-dynamic quasi-stationary states. The characteristics of the developed methodology are tested on the example of the existing electric power interconnection in the Balkans.
{"title":"Methodological and practical aspects of steady-state security assessment of Yugoslav Power System","authors":"D. Popović, D. Dobrijević, N. Mijuskovic, D.J. Vlaisuvijevic","doi":"10.1109/PTC.1999.826627","DOIUrl":"https://doi.org/10.1109/PTC.1999.826627","url":null,"abstract":"The relevant methodological and practical aspects of steady-state security assessment of Yugoslav Power System are presented in this paper. This methodology consists of a procedure for forming the unified external network equivalents, procedure for fast contingency selection and simple method for the fast assessment of dynamic change of power system frequency. Full contingency analysis is based on a specially developed method, which enables successive solution of the load-flow problem for a set of characteristic post-dynamic quasi-stationary states. The characteristics of the developed methodology are tested on the example of the existing electric power interconnection in the Balkans.","PeriodicalId":101688,"journal":{"name":"PowerTech Budapest 99. Abstract Records. (Cat. No.99EX376)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122978711","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}
The paper deals with the sensitivity of the flicker measurement according to IEC 868 and EN 50160 requirements on the start time at the measurement. Furthermore evaluation methods are introduced to improve the stability of the long term flicker sensitivity factor relative to the start time of the measurement.
{"title":"Improved method for flicker evaluation","authors":"A.M. Dan, G. Dan, S. Ríos","doi":"10.1109/PTC.1999.826603","DOIUrl":"https://doi.org/10.1109/PTC.1999.826603","url":null,"abstract":"The paper deals with the sensitivity of the flicker measurement according to IEC 868 and EN 50160 requirements on the start time at the measurement. Furthermore evaluation methods are introduced to improve the stability of the long term flicker sensitivity factor relative to the start time of the measurement.","PeriodicalId":101688,"journal":{"name":"PowerTech Budapest 99. Abstract Records. (Cat. No.99EX376)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126552446","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}
The main purpose of this paper is to investigate the power flow regulating capabilities of an UPFC's injection model by using all three UPFC's control parameters simultaneously. The control system of the model is developed and its contributions to power flow regulation are explored on a multi-machine test system. The analysis is carried out from dynamic aspect utilising time-domain simulations. With the UPFC being embedded in the system, the analysis is concentrated on a transmission system compensation issues. It is shown that the model can fulfil functions of reactive shunt compensation, series compensation and phase shifting meeting multiple control objectives by applying boosting transformer injected voltage and exciting transformer reactive current.
{"title":"Power flow regulation by use of UPFC's injection model","authors":"N. Dizdarević, S. Tesnjak, G. Andersson","doi":"10.1109/PTC.1999.826538","DOIUrl":"https://doi.org/10.1109/PTC.1999.826538","url":null,"abstract":"The main purpose of this paper is to investigate the power flow regulating capabilities of an UPFC's injection model by using all three UPFC's control parameters simultaneously. The control system of the model is developed and its contributions to power flow regulation are explored on a multi-machine test system. The analysis is carried out from dynamic aspect utilising time-domain simulations. With the UPFC being embedded in the system, the analysis is concentrated on a transmission system compensation issues. It is shown that the model can fulfil functions of reactive shunt compensation, series compensation and phase shifting meeting multiple control objectives by applying boosting transformer injected voltage and exciting transformer reactive current.","PeriodicalId":101688,"journal":{"name":"PowerTech Budapest 99. Abstract Records. (Cat. No.99EX376)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129161284","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}
For AC networks with large amounts of induction generators-in case of e.g. windmills-the paper demonstrates a significant discrepancy in the simulated voltage recovery after faults in weak networks, when comparing result obtained with dynamic stability programs and transient programs, respectively with and without a model of the mechanical shaft. The reason for the discrepancies are explained, and it is shown that the phenomenon is due partly to the presence of DC offset currents in the induction machine stator, and partly to the mechanical shaft system of the wind turbine and the generator rotor. It is shown that it is possible to include a transient model in dynamic stability programs and thus obtain correct results also in dynamic stability programs. A mechanical model of the shaft system has also been included in the generator model.
{"title":"Modelling of windmill induction generators in dynamic simulation programs","authors":"Vladislav Knudsen Akhmatov, Hans","doi":"10.1109/PTC.1999.826539","DOIUrl":"https://doi.org/10.1109/PTC.1999.826539","url":null,"abstract":"For AC networks with large amounts of induction generators-in case of e.g. windmills-the paper demonstrates a significant discrepancy in the simulated voltage recovery after faults in weak networks, when comparing result obtained with dynamic stability programs and transient programs, respectively with and without a model of the mechanical shaft. The reason for the discrepancies are explained, and it is shown that the phenomenon is due partly to the presence of DC offset currents in the induction machine stator, and partly to the mechanical shaft system of the wind turbine and the generator rotor. It is shown that it is possible to include a transient model in dynamic stability programs and thus obtain correct results also in dynamic stability programs. A mechanical model of the shaft system has also been included in the generator model.","PeriodicalId":101688,"journal":{"name":"PowerTech Budapest 99. Abstract Records. (Cat. No.99EX376)","volume":"46 11","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131436182","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}
This paper describes steady state and dynamic induction motor reduced order models improvement for the simulation of the dynamic performance of power systems. The steady state model is suited for power flow programs and is one solution to the problem of initializing the dynamic models of the induction motor. Dynamic models are in a reference frame that takes into account the transient frequency changes of the system and represent the damping effects of these devices correctly.
{"title":"Improvement of induction motors models for power system transient stability studies","authors":"D. Ruiz, T. Asiain, D. Olguin","doi":"10.1109/PTC.1999.826501","DOIUrl":"https://doi.org/10.1109/PTC.1999.826501","url":null,"abstract":"This paper describes steady state and dynamic induction motor reduced order models improvement for the simulation of the dynamic performance of power systems. The steady state model is suited for power flow programs and is one solution to the problem of initializing the dynamic models of the induction motor. Dynamic models are in a reference frame that takes into account the transient frequency changes of the system and represent the damping effects of these devices correctly.","PeriodicalId":101688,"journal":{"name":"PowerTech Budapest 99. Abstract Records. (Cat. No.99EX376)","volume":"134 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122703638","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}
Deregulation is causing a great impact on the electric power industry around the world. Many transactions in electric power markets are based on bidding competition after deregulation. The nodal price plays an important role in such a kind of market to reflect the bidding strategy for a market participant. This paper investigates the impact of ancillary service, security constraint, and MW loss on nodal prices in the system. The causes for the variation of nodal prices are explained. The problem is formulated with DC models and solved by simplex linear programming. The simulation results help understand the meaning of the nodal prices and help develop bidding strategies for the market participants.
{"title":"Investigation of nodal prices in a deregulated competitive market-case studies","authors":"Yingyi Hong, M. Weng","doi":"10.1109/PTC.1999.826592","DOIUrl":"https://doi.org/10.1109/PTC.1999.826592","url":null,"abstract":"Deregulation is causing a great impact on the electric power industry around the world. Many transactions in electric power markets are based on bidding competition after deregulation. The nodal price plays an important role in such a kind of market to reflect the bidding strategy for a market participant. This paper investigates the impact of ancillary service, security constraint, and MW loss on nodal prices in the system. The causes for the variation of nodal prices are explained. The problem is formulated with DC models and solved by simplex linear programming. The simulation results help understand the meaning of the nodal prices and help develop bidding strategies for the market participants.","PeriodicalId":101688,"journal":{"name":"PowerTech Budapest 99. Abstract Records. (Cat. No.99EX376)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124086301","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}
In recent years, there has been an increasing interest for the analysis of dynamic voltage stability on power systems. It is well known that induction motor loads have a particularly hazardous role in the voltage stability. On the other hand, in transmission systems loaded by induction motor loads, configuration changes such as line tripping, may cause voltage collapse. Moreover, if there is a fault on transmission lines, the disturbance effect will then significantly increase the possibility of voltage collapse. In this study, a transmission system subjected to different faults on different locations is examined from the viewpoint of voltage stability. The study shows that in the certain cases of paralleled transmission lines, single or double phase tripping of a faulted line will have positive effects on voltage stability, instead of all three phase tripping.
{"title":"Effects of transmission line faults on dynamic voltage stability","authors":"M. Yalçin, M. Turan, Z. Demir","doi":"10.1109/PTC.1999.826511","DOIUrl":"https://doi.org/10.1109/PTC.1999.826511","url":null,"abstract":"In recent years, there has been an increasing interest for the analysis of dynamic voltage stability on power systems. It is well known that induction motor loads have a particularly hazardous role in the voltage stability. On the other hand, in transmission systems loaded by induction motor loads, configuration changes such as line tripping, may cause voltage collapse. Moreover, if there is a fault on transmission lines, the disturbance effect will then significantly increase the possibility of voltage collapse. In this study, a transmission system subjected to different faults on different locations is examined from the viewpoint of voltage stability. The study shows that in the certain cases of paralleled transmission lines, single or double phase tripping of a faulted line will have positive effects on voltage stability, instead of all three phase tripping.","PeriodicalId":101688,"journal":{"name":"PowerTech Budapest 99. Abstract Records. (Cat. No.99EX376)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128995486","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}
In this paper, a modification to the optimal power flow problem, which accounts for the presence of wind parks and independent power producers (IPP) operation under large-scale integration of dispatchable wind energy resource in the power system, is described. A successive linear programming approach is utilized for the solution of the problem.
{"title":"Consideration of wind parks operation in the optimal power flow problem","authors":"G. Contaxis, Andreas Vlachos","doi":"10.1109/PTC.1999.826494","DOIUrl":"https://doi.org/10.1109/PTC.1999.826494","url":null,"abstract":"In this paper, a modification to the optimal power flow problem, which accounts for the presence of wind parks and independent power producers (IPP) operation under large-scale integration of dispatchable wind energy resource in the power system, is described. A successive linear programming approach is utilized for the solution of the problem.","PeriodicalId":101688,"journal":{"name":"PowerTech Budapest 99. Abstract Records. (Cat. No.99EX376)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128532419","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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