Pub Date : 2015-12-03DOI: 10.1109/RTUCON.2015.7343116
G. Georgiev, I. Kryuchkov, I. Zicmane, S. Kovalenko
In the paper the application of Monte Carlo approach for random search algorithms to finding a pair of conjugated roots of a characteristic polynomial (ChP) is presented. The proposed technique is oriented only to ChPs with real coefficients. The search is produced on the basis of random numbers with uniform distribution in a rather narrow bounded region of the complex plane. Two search methods are considered here: 1) Indirect method to finding a pair of complex conjugate roots; 2) Direct method which results are coefficients of the trinomial divisor of the ChP. Then the conjugated roots can be easily found as roots of the trinomial divisor. If high precision is necessary then the best random hit is used as good initial estimate for further specification of better results by the iterative Newton's method for two equations with two unknowns (the Jacobian is a 2×2 matrix). The specified techniques can be very easily and simply realized in the environment of MS Excel or MATLAB functions at minimum computing resource. The both proposed here methods can be used in the educational process providing good visualization of the study area. Irrespective of the high degree of ChP it is possible to direct the search process so that to find at once only those roots that are of interest in connection with the problem of stability of the corresponding electrical system. The offered algorithms allow creating effective software products.
{"title":"Factorization of a characteristic polynomial by random search one of its trinomial divisors","authors":"G. Georgiev, I. Kryuchkov, I. Zicmane, S. Kovalenko","doi":"10.1109/RTUCON.2015.7343116","DOIUrl":"https://doi.org/10.1109/RTUCON.2015.7343116","url":null,"abstract":"In the paper the application of Monte Carlo approach for random search algorithms to finding a pair of conjugated roots of a characteristic polynomial (ChP) is presented. The proposed technique is oriented only to ChPs with real coefficients. The search is produced on the basis of random numbers with uniform distribution in a rather narrow bounded region of the complex plane. Two search methods are considered here: 1) Indirect method to finding a pair of complex conjugate roots; 2) Direct method which results are coefficients of the trinomial divisor of the ChP. Then the conjugated roots can be easily found as roots of the trinomial divisor. If high precision is necessary then the best random hit is used as good initial estimate for further specification of better results by the iterative Newton's method for two equations with two unknowns (the Jacobian is a 2×2 matrix). The specified techniques can be very easily and simply realized in the environment of MS Excel or MATLAB functions at minimum computing resource. The both proposed here methods can be used in the educational process providing good visualization of the study area. Irrespective of the high degree of ChP it is possible to direct the search process so that to find at once only those roots that are of interest in connection with the problem of stability of the corresponding electrical system. The offered algorithms allow creating effective software products.","PeriodicalId":389419,"journal":{"name":"2015 56th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130349583","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 : 2015-12-03DOI: 10.1109/RTUCON.2015.7343135
K. Baltputnis, A. Sauhats, O. Linkevičs, R. Petrichenko, R. Varfolomejeva, Z. Broka
In this paper the task of modeling water utilization in the hydroelectric power plants on the Daugava River is outlined. Difficulties caused by the complexity of the task are discussed and the necessity to decompose it is considered. Unit commitment proves to be especially important subtask as it introduces several constraints and limitations. A possibility to solve it using dynamic programming approach has been offered and the veracity of the mathematical model of reservoirs has been tested in this paper.
{"title":"Modeling of water utilization in hydroelectric power plants on the Daugava River","authors":"K. Baltputnis, A. Sauhats, O. Linkevičs, R. Petrichenko, R. Varfolomejeva, Z. Broka","doi":"10.1109/RTUCON.2015.7343135","DOIUrl":"https://doi.org/10.1109/RTUCON.2015.7343135","url":null,"abstract":"In this paper the task of modeling water utilization in the hydroelectric power plants on the Daugava River is outlined. Difficulties caused by the complexity of the task are discussed and the necessity to decompose it is considered. Unit commitment proves to be especially important subtask as it introduces several constraints and limitations. A possibility to solve it using dynamic programming approach has been offered and the veracity of the mathematical model of reservoirs has been tested in this paper.","PeriodicalId":389419,"journal":{"name":"2015 56th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)","volume":"74 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116230949","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 : 2015-12-03DOI: 10.1109/RTUCON.2015.7343128
K. Vītols
Modern lithium ion batteries such as LiFePO4 are an active topic because of their good parameters. Yet as all lithium based batteries they need battery management systems for proper operation. The design and testing of such systems is very time consuming and additionally the cell testing and deep discharge or full charge can become dangerous because of cell operational limits. Typically battery models are used for simulation of such systems, yet the manufacturers do not provide all the necessary information to construct the models. This article is intended to provide some information such as cell capacity dispersion and open circuit voltage necessary for the development of a cell model. The same information can be used to develop state of charge estimator as well.
{"title":"Lithium ion battery parameter evaluation for battery management system","authors":"K. Vītols","doi":"10.1109/RTUCON.2015.7343128","DOIUrl":"https://doi.org/10.1109/RTUCON.2015.7343128","url":null,"abstract":"Modern lithium ion batteries such as LiFePO4 are an active topic because of their good parameters. Yet as all lithium based batteries they need battery management systems for proper operation. The design and testing of such systems is very time consuming and additionally the cell testing and deep discharge or full charge can become dangerous because of cell operational limits. Typically battery models are used for simulation of such systems, yet the manufacturers do not provide all the necessary information to construct the models. This article is intended to provide some information such as cell capacity dispersion and open circuit voltage necessary for the development of a cell model. The same information can be used to develop state of charge estimator as well.","PeriodicalId":389419,"journal":{"name":"2015 56th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126706537","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 : 2015-12-03DOI: 10.1109/RTUCON.2015.7343158
A. Anuchin, F. Briz, L. Rassudov, I. Gulyaev
This paper deals with the method of fast and accurate modeling of electric drives. The existing methods of modeling of variable speed electric drives are considered, their strong and weak sides are shown. The proposed method is based on simplified model of the inverter with integration step size snapped to actual changes of the inverter state. Method takes into account dead time and voltage drops in transistors and diodes and obtained current curve is in good agreement with experimentally measured currents. It may be used for control system design and modeling of the drive in virtual instructional laboratories.
{"title":"Implementation of fast and accurate modeling method of electric drives","authors":"A. Anuchin, F. Briz, L. Rassudov, I. Gulyaev","doi":"10.1109/RTUCON.2015.7343158","DOIUrl":"https://doi.org/10.1109/RTUCON.2015.7343158","url":null,"abstract":"This paper deals with the method of fast and accurate modeling of electric drives. The existing methods of modeling of variable speed electric drives are considered, their strong and weak sides are shown. The proposed method is based on simplified model of the inverter with integration step size snapped to actual changes of the inverter state. Method takes into account dead time and voltage drops in transistors and diodes and obtained current curve is in good agreement with experimentally measured currents. It may be used for control system design and modeling of the drive in virtual instructional laboratories.","PeriodicalId":389419,"journal":{"name":"2015 56th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115287569","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 : 2015-10-01DOI: 10.1109/RTUCON.2015.7343121
J. Survilo
Proposed by producers price is a major factor in determining the nodal price, next transport losses, congestion costs and other paying. In the paper, main attention is paid to accounting producer prices and losses to the node in question. Each producer sends its share of power (reciprocal power) in the considered node while on the road he needs extra energy (reciprocal losses) to reach the node. Thus consumer which feeds from the node is to pay for received energy and the losses of its transportation to the node. The reciprocal power is defined by proposed node voltage method but reciprocal losses are defined by node current increment method. Reciprocal losses can rarely be also negative, that is caused by redistribution of the branch currents in a closed network. Nodal price takes into consideration all suppliers by calculating an average value. If congestion is expressed by current limitation in a line, then there is additional condition that causes recalculation of reciprocal quantities.
{"title":"A method for node prices formation","authors":"J. Survilo","doi":"10.1109/RTUCON.2015.7343121","DOIUrl":"https://doi.org/10.1109/RTUCON.2015.7343121","url":null,"abstract":"Proposed by producers price is a major factor in determining the nodal price, next transport losses, congestion costs and other paying. In the paper, main attention is paid to accounting producer prices and losses to the node in question. Each producer sends its share of power (reciprocal power) in the considered node while on the road he needs extra energy (reciprocal losses) to reach the node. Thus consumer which feeds from the node is to pay for received energy and the losses of its transportation to the node. The reciprocal power is defined by proposed node voltage method but reciprocal losses are defined by node current increment method. Reciprocal losses can rarely be also negative, that is caused by redistribution of the branch currents in a closed network. Nodal price takes into consideration all suppliers by calculating an average value. If congestion is expressed by current limitation in a line, then there is additional condition that causes recalculation of reciprocal quantities.","PeriodicalId":389419,"journal":{"name":"2015 56th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128724151","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 : 2015-10-01DOI: 10.1109/RTUCON.2015.7343179
M. Gutten, Richard Janura, J. Jurcik
Article presents effects caused by electromagnetic forces on the transformer windings. It shows dimensions, direction and of course caused mechanical stress. Equation shows basic dependencies of these mechanical forces created in the transformer windings. The last part of the article is focused to the simulation method which shows the mechanical stress caused by the short circuit-currents. This method is preferred for analysis of power transformer.
{"title":"Determination of the electromagnetic forces caused by short-circuit currents","authors":"M. Gutten, Richard Janura, J. Jurcik","doi":"10.1109/RTUCON.2015.7343179","DOIUrl":"https://doi.org/10.1109/RTUCON.2015.7343179","url":null,"abstract":"Article presents effects caused by electromagnetic forces on the transformer windings. It shows dimensions, direction and of course caused mechanical stress. Equation shows basic dependencies of these mechanical forces created in the transformer windings. The last part of the article is focused to the simulation method which shows the mechanical stress caused by the short circuit-currents. This method is preferred for analysis of power transformer.","PeriodicalId":389419,"journal":{"name":"2015 56th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130623821","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 : 2015-10-01DOI: 10.1109/RTUCON.2015.7343141
M. Stfelec, Andrea Zápotocká, P. Janeček, E. Janecek
Dispersed generation sources are slowly penetrating into distribution power networks. Renewables represent the majority of newly installed energy sources, which are of stochastic nature. With this phenomenon, new technical challenges are rising up, where appropriate impact assessment of volatile dispersed generation on voltage quality stands for one of them. Current planning tools and optimization methods mostly rely on the deterministic key performance indicators (KPI), which assesses the power quality in a distribution network. These indicators may not be sufficient for power network with high presence of uncertainty. In this paper, power network model with emphasis on probabilistic description of power injections is described. Correlation among stochastic power injection is discussed and consequently this correlation is categorized into several groups. Main focus of the paper is on design of probabilistic key performance indicators for assessment of power quality in a distribution network. Two probabilistic load flow methods used for computation of introduced KPIs are presented and their performance is analyzed on selected test case. On the test case, KPIs evaluation is demonstrated and the results are analyzed.
{"title":"Probabilistic assessment of the impact of dispersed generation on voltage quality","authors":"M. Stfelec, Andrea Zápotocká, P. Janeček, E. Janecek","doi":"10.1109/RTUCON.2015.7343141","DOIUrl":"https://doi.org/10.1109/RTUCON.2015.7343141","url":null,"abstract":"Dispersed generation sources are slowly penetrating into distribution power networks. Renewables represent the majority of newly installed energy sources, which are of stochastic nature. With this phenomenon, new technical challenges are rising up, where appropriate impact assessment of volatile dispersed generation on voltage quality stands for one of them. Current planning tools and optimization methods mostly rely on the deterministic key performance indicators (KPI), which assesses the power quality in a distribution network. These indicators may not be sufficient for power network with high presence of uncertainty. In this paper, power network model with emphasis on probabilistic description of power injections is described. Correlation among stochastic power injection is discussed and consequently this correlation is categorized into several groups. Main focus of the paper is on design of probabilistic key performance indicators for assessment of power quality in a distribution network. Two probabilistic load flow methods used for computation of introduced KPIs are presented and their performance is analyzed on selected test case. On the test case, KPIs evaluation is demonstrated and the results are analyzed.","PeriodicalId":389419,"journal":{"name":"2015 56th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128154633","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 : 2015-10-01DOI: 10.1109/RTUCON.2015.7343163
O. Tetervenoks
The rapid development of LED lighting technology as well as increasing demand on new energy efficient lighting devices contribute to the appearance of new companies on the market of solid state lighting. Growing competition enforce these companies to reduce production costs, at the same time keeping the functionality and quality of products at high level. The paper deals with low cost LED driving solutions currently available on the market. They are classified in the scope of the paper. Advantages and drawbacks as well as typical problems of these solutions are discussed.
{"title":"Assessment of low cost high power factor electrical ballasts for LED lamps","authors":"O. Tetervenoks","doi":"10.1109/RTUCON.2015.7343163","DOIUrl":"https://doi.org/10.1109/RTUCON.2015.7343163","url":null,"abstract":"The rapid development of LED lighting technology as well as increasing demand on new energy efficient lighting devices contribute to the appearance of new companies on the market of solid state lighting. Growing competition enforce these companies to reduce production costs, at the same time keeping the functionality and quality of products at high level. The paper deals with low cost LED driving solutions currently available on the market. They are classified in the scope of the paper. Advantages and drawbacks as well as typical problems of these solutions are discussed.","PeriodicalId":389419,"journal":{"name":"2015 56th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114690272","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 : 2015-10-01DOI: 10.1109/RTUCON.2015.7343157
P. Farhang, A. Drimus, S. Mátéfi-Tempfli
In this paper, a new technique is proposed to design a Modified PID (MPID) controller for a Boost converter. An interface between LTspice and MATLAB is carried out to implement the Particle Swarm Optimization (PSO) algorithm. The PSO algorithm which has the appropriate capability to find out the optimal solutions is run in MATLAB while it is interfaced with LTspice for simulation of the circuit using actual component models obtained from manufacturers. The PSO is utilized to solve the optimization problem in order to find the optimal parameters of MPID and PID controllers. The performances of the controllers are evaluated for a wide range of operating conditions and different disturbances. The comprehensive simulation results demonstrate the effectiveness and robustness of the proposed method which are also explained through some performance indices.
{"title":"New technique for voltage tracking control of a boost converter based on the PSO algorithm and LTspice","authors":"P. Farhang, A. Drimus, S. Mátéfi-Tempfli","doi":"10.1109/RTUCON.2015.7343157","DOIUrl":"https://doi.org/10.1109/RTUCON.2015.7343157","url":null,"abstract":"In this paper, a new technique is proposed to design a Modified PID (MPID) controller for a Boost converter. An interface between LTspice and MATLAB is carried out to implement the Particle Swarm Optimization (PSO) algorithm. The PSO algorithm which has the appropriate capability to find out the optimal solutions is run in MATLAB while it is interfaced with LTspice for simulation of the circuit using actual component models obtained from manufacturers. The PSO is utilized to solve the optimization problem in order to find the optimal parameters of MPID and PID controllers. The performances of the controllers are evaluated for a wide range of operating conditions and different disturbances. The comprehensive simulation results demonstrate the effectiveness and robustness of the proposed method which are also explained through some performance indices.","PeriodicalId":389419,"journal":{"name":"2015 56th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117030346","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 : 2015-10-01DOI: 10.1109/RTUCON.2015.7343171
A. Chub, Liisa Liivik, J. Zakis, Dmitri Vinnikon
The quasi-switched-boost inverter is an alternative to the quasi-Z-Source inverter. Its passive component number is two times smaller but it contains two additional semiconductor components. Earlier the switched-inductor cell was applied in this topology to enhance dc voltage gain at the cost of high input current ripple. This paper proposes a novel switched-inductor quasi-switched-boost inverter topology with low input current ripple and enhanced dc voltage gain. It is based on a modified switched-inductor cell where the input source is connected in series with an inductor. Operation principle is described through separation of the switching period into three intervals. Equivalent circuits and circuit equations are shown for each interval. Simulation study corroborates theoretical predictions.
{"title":"Improved switched-inductor quasi-switched-boost inverter with low input current ripple","authors":"A. Chub, Liisa Liivik, J. Zakis, Dmitri Vinnikon","doi":"10.1109/RTUCON.2015.7343171","DOIUrl":"https://doi.org/10.1109/RTUCON.2015.7343171","url":null,"abstract":"The quasi-switched-boost inverter is an alternative to the quasi-Z-Source inverter. Its passive component number is two times smaller but it contains two additional semiconductor components. Earlier the switched-inductor cell was applied in this topology to enhance dc voltage gain at the cost of high input current ripple. This paper proposes a novel switched-inductor quasi-switched-boost inverter topology with low input current ripple and enhanced dc voltage gain. It is based on a modified switched-inductor cell where the input source is connected in series with an inductor. Operation principle is described through separation of the switching period into three intervals. Equivalent circuits and circuit equations are shown for each interval. Simulation study corroborates theoretical predictions.","PeriodicalId":389419,"journal":{"name":"2015 56th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115879054","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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