The sharing of the routes for transmission overhead lines operated at different voltages and frequencies is a popular technical solution. Often the circuits of extra high and high voltage lines are installed on the same towers. This causes the electromagnetic interaction between corresponding power transmission systems. Earth fault currents and neutral point displacement voltages can be increased in electrical networks with resonant earthed neutral due to the electromagnetic influence from parallel located power transmission lines. Theoretical mechanism of the interaction, some practical examples based on investigations in German transmission networks and possible measures for the reduction of negative influences will be considered in the offered paper.
{"title":"Interaction of multi-circuit overhead transmission lines of different voltages located on the same pylons","authors":"A. Novitskiy, D. Westermann","doi":"10.1109/PQ.2012.6256240","DOIUrl":"https://doi.org/10.1109/PQ.2012.6256240","url":null,"abstract":"The sharing of the routes for transmission overhead lines operated at different voltages and frequencies is a popular technical solution. Often the circuits of extra high and high voltage lines are installed on the same towers. This causes the electromagnetic interaction between corresponding power transmission systems. Earth fault currents and neutral point displacement voltages can be increased in electrical networks with resonant earthed neutral due to the electromagnetic influence from parallel located power transmission lines. Theoretical mechanism of the interaction, some practical examples based on investigations in German transmission networks and possible measures for the reduction of negative influences will be considered in the offered paper.","PeriodicalId":185013,"journal":{"name":"2012 Electric Power Quality and Supply Reliability","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128102093","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 flowing of molten metal in a novel electric arc furnace. Combined AC and DC components are used in the supply system for the furnace. Finite element method is used to investigate the impact of AC component frequency on the flowing of molten metal.
{"title":"Investigation of molten metal mixing in a DC electric arc furnace with added AC component on different frequencies","authors":"H. Mõlder, J. Jarvik, T. Vaimann, R. Gordon","doi":"10.1109/PQ.2012.6256196","DOIUrl":"https://doi.org/10.1109/PQ.2012.6256196","url":null,"abstract":"This paper describes flowing of molten metal in a novel electric arc furnace. Combined AC and DC components are used in the supply system for the furnace. Finite element method is used to investigate the impact of AC component frequency on the flowing of molten metal.","PeriodicalId":185013,"journal":{"name":"2012 Electric Power Quality and Supply Reliability","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124426227","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}
I. Asmontas, S. Gudzius, L. Markevicius, A. Morkvėnas, V. Tička
Modern railway signaling and traction control systems are complex automated systems. Digital electronics allow the realization of intelligent and sophisticated control features, which are widely used for railway. When using latest automation, alarm and control systems issues related to the reliability and security emerge due to its low resistance to electromagnetic interference. Before coordinating protection from lightning induced surge or switching overvoltages it is essential to investigate the levels of the overvoltage and work conditions of surge protections after replacing some of the network subsystems with modern electronic devices. This paper analyzes the levels of overvoltage transient processes in the different points of the electrical network by taking into account the assessment of surge protection devices characteristics.
{"title":"The investigation of overvoltage transient processes in railway electric power feeding systems","authors":"I. Asmontas, S. Gudzius, L. Markevicius, A. Morkvėnas, V. Tička","doi":"10.1109/PQ.2012.6256237","DOIUrl":"https://doi.org/10.1109/PQ.2012.6256237","url":null,"abstract":"Modern railway signaling and traction control systems are complex automated systems. Digital electronics allow the realization of intelligent and sophisticated control features, which are widely used for railway. When using latest automation, alarm and control systems issues related to the reliability and security emerge due to its low resistance to electromagnetic interference. Before coordinating protection from lightning induced surge or switching overvoltages it is essential to investigate the levels of the overvoltage and work conditions of surge protections after replacing some of the network subsystems with modern electronic devices. This paper analyzes the levels of overvoltage transient processes in the different points of the electrical network by taking into account the assessment of surge protection devices characteristics.","PeriodicalId":185013,"journal":{"name":"2012 Electric Power Quality and Supply Reliability","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124816495","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 a method to calculate the individual flicker emission of specific disturbers by means of simultaneous flicker level measurements in different bus bars of a meshed grid. The method is based on former investigations regarding the flicker propagation in meshed networks. With adequate flicker level measurements, the cubic flicker summation law and the specific flicker transfer factors which result out of the grid's impedance matrix, a detailed analysis of the flicker emission situation in a grid can be done. A case study with electric arc furnaces in a 110 kV grid is presented as application example, including a sensitivity analysis.
{"title":"Flicker source identification in meshed high voltage grids","authors":"H. Renner","doi":"10.1109/PQ.2012.6256213","DOIUrl":"https://doi.org/10.1109/PQ.2012.6256213","url":null,"abstract":"This paper describes a method to calculate the individual flicker emission of specific disturbers by means of simultaneous flicker level measurements in different bus bars of a meshed grid. The method is based on former investigations regarding the flicker propagation in meshed networks. With adequate flicker level measurements, the cubic flicker summation law and the specific flicker transfer factors which result out of the grid's impedance matrix, a detailed analysis of the flicker emission situation in a grid can be done. A case study with electric arc furnaces in a 110 kV grid is presented as application example, including a sensitivity analysis.","PeriodicalId":185013,"journal":{"name":"2012 Electric Power Quality and Supply Reliability","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127696496","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 presents the analytical analysis of different eccentricities in the rotor of a novel slotless wind power generator. The analytical expressions for the air gap eccentricity have been derived and the effects of these eccentricities on the air gap flux density, the resultant unbalanced magnetic pull and the induced emf are investigated. The analysis shows a strong pull in the case of static eccentricity, which is not seen when the case of elliptic eccentricity for example. The analysis shows also that the induced emf per coil can vary very much but due to the series connection of the coil per phase emf is uniform but has higher rms value than in the case of healthy machine. The analytical equations are verified for the case of healthy machine on a constructed laboratory prototype.
{"title":"Analysis of the eccentricity in a low-speed slotless permanent-magnet wind generator","authors":"A. Kallaste, A. Belahcen, A. Kilk, T. Vaimann","doi":"10.1109/PQ.2012.6256199","DOIUrl":"https://doi.org/10.1109/PQ.2012.6256199","url":null,"abstract":"This paper presents the analytical analysis of different eccentricities in the rotor of a novel slotless wind power generator. The analytical expressions for the air gap eccentricity have been derived and the effects of these eccentricities on the air gap flux density, the resultant unbalanced magnetic pull and the induced emf are investigated. The analysis shows a strong pull in the case of static eccentricity, which is not seen when the case of elliptic eccentricity for example. The analysis shows also that the induced emf per coil can vary very much but due to the series connection of the coil per phase emf is uniform but has higher rms value than in the case of healthy machine. The analytical equations are verified for the case of healthy machine on a constructed laboratory prototype.","PeriodicalId":185013,"journal":{"name":"2012 Electric Power Quality and Supply Reliability","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129391056","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}
Many companies engaged in wind generator development are investigating permanent magnet generators (PMG) mainly because of higher efficiency over a broad range of wind speed and reduced costs of maintenance. One important parameter of PM generators is the primary magnetic flux that has certain influence to no load voltage of the machine. Thus, needs for efficient calculation methods for primary magnetic field is required. Finite element method is one of the most common and efficient way to analyze the magnetic flux of the machine. But on the other hand it is relatively complicated calculation method and it might be incomprehensible. Analytic calculation or calculations based on reluctance network are comprehensive and suitable for engineers-designers. This paper deals with the primary magnetic field analysis and basic winding calculations by an example of 54 slots and 20 poles PM synchronous generator. Modeling of the primary magnetic field distribution by the finite element method in software FEMM is described. Results from the analytic calculations and the finite element method are compared with experimental data of PM prototype generator study.
{"title":"Analysis and prototyping of a low-speed small scale permanent magnet generator for wind power applications","authors":"E. Lepa, A. Kilk","doi":"10.1109/PQ.2012.6256193","DOIUrl":"https://doi.org/10.1109/PQ.2012.6256193","url":null,"abstract":"Many companies engaged in wind generator development are investigating permanent magnet generators (PMG) mainly because of higher efficiency over a broad range of wind speed and reduced costs of maintenance. One important parameter of PM generators is the primary magnetic flux that has certain influence to no load voltage of the machine. Thus, needs for efficient calculation methods for primary magnetic field is required. Finite element method is one of the most common and efficient way to analyze the magnetic flux of the machine. But on the other hand it is relatively complicated calculation method and it might be incomprehensible. Analytic calculation or calculations based on reluctance network are comprehensive and suitable for engineers-designers. This paper deals with the primary magnetic field analysis and basic winding calculations by an example of 54 slots and 20 poles PM synchronous generator. Modeling of the primary magnetic field distribution by the finite element method in software FEMM is described. Results from the analytic calculations and the finite element method are compared with experimental data of PM prototype generator study.","PeriodicalId":185013,"journal":{"name":"2012 Electric Power Quality and Supply Reliability","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132366527","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}
A connection between a phase conductor and the ground in MV networks is called earth fault. The fault current in this case does not depend on the point of the fault, but only on the total capacity (size) of a network. Distribution system operator (DSO) sometimes needs to operate the large network which means operating of the network with big capacitive current (in Czech Republic more than 800A). This operation puts the emphasis not only on the setting of the earth fault relays but on the safety of the point of fault too. The paper describes the tests in real compensated distribution network with capacitive currents 300A and 800A. There were tested low-ohmic and arc fault. The first results show that the operation of large network is possible with using of the automatics of additional earthing of affected phase. The touch and step voltages were reduced under level allowed by standard EN 50522.
{"title":"Experimental measuring of the touch voltages in large compensated networks","authors":"P. Toman, D. Topolanek, J. Orságová, J. Dvorak","doi":"10.1109/PQ.2012.6256227","DOIUrl":"https://doi.org/10.1109/PQ.2012.6256227","url":null,"abstract":"A connection between a phase conductor and the ground in MV networks is called earth fault. The fault current in this case does not depend on the point of the fault, but only on the total capacity (size) of a network. Distribution system operator (DSO) sometimes needs to operate the large network which means operating of the network with big capacitive current (in Czech Republic more than 800A). This operation puts the emphasis not only on the setting of the earth fault relays but on the safety of the point of fault too. The paper describes the tests in real compensated distribution network with capacitive currents 300A and 800A. There were tested low-ohmic and arc fault. The first results show that the operation of large network is possible with using of the automatics of additional earthing of affected phase. The touch and step voltages were reduced under level allowed by standard EN 50522.","PeriodicalId":185013,"journal":{"name":"2012 Electric Power Quality and Supply Reliability","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123492926","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 presents the experimental study of induction motor broken rotor bars diagnostics. Fault tests are performed on a machine with 3 broken bars, driven through a frequency converter. Park's vector approach is used as an analyzing tool to detect the broken rotor bars. Park's vector patterns in case of stator current and voltage are investigated. Results of the tests and discussion are presented. Necessity for further study is pointed out.
{"title":"Detection of broken bars in frequency converter fed induction motor using Park's vector approach","authors":"T. Vaimann, A. Belahcen, J. Martinez, A. Kilk","doi":"10.1109/PQ.2012.6256204","DOIUrl":"https://doi.org/10.1109/PQ.2012.6256204","url":null,"abstract":"This paper presents the experimental study of induction motor broken rotor bars diagnostics. Fault tests are performed on a machine with 3 broken bars, driven through a frequency converter. Park's vector approach is used as an analyzing tool to detect the broken rotor bars. Park's vector patterns in case of stator current and voltage are investigated. Results of the tests and discussion are presented. Necessity for further study is pointed out.","PeriodicalId":185013,"journal":{"name":"2012 Electric Power Quality and Supply Reliability","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125740315","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}
Usually, when performing network dynamic studies fault duration times and network configuration are selected based on predefined conditions. In this paper, the approach is to complement the conventional approach by considering actual relay protection operation. In addition, also possible failures of relay protection and circuit breaker operation are taken into account, i.e., additional fault clearing time causing different transient behaviour, is included. This paper gives an overview and discussion about the development of combined relay protection and dynamics modelling methodology and it is focused on the verification of relay protection and dynamic electromechanical transient model against actual field measurements during the wind power plant commissioning tests.
{"title":"Model verification for analysis of wind power impact to transient stability in isolated power system using combined relay protection and dynamics modelling approach","authors":"R. Maripuu, O. Tsernobrovkin, I. Palu, J. Kilter","doi":"10.1109/PQ.2012.6256222","DOIUrl":"https://doi.org/10.1109/PQ.2012.6256222","url":null,"abstract":"Usually, when performing network dynamic studies fault duration times and network configuration are selected based on predefined conditions. In this paper, the approach is to complement the conventional approach by considering actual relay protection operation. In addition, also possible failures of relay protection and circuit breaker operation are taken into account, i.e., additional fault clearing time causing different transient behaviour, is included. This paper gives an overview and discussion about the development of combined relay protection and dynamics modelling methodology and it is focused on the verification of relay protection and dynamic electromechanical transient model against actual field measurements during the wind power plant commissioning tests.","PeriodicalId":185013,"journal":{"name":"2012 Electric Power Quality and Supply Reliability","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133210692","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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