Pub Date : 2018-09-01DOI: 10.1109/BULEF.2018.8646938
Nikolay Matanov, S. Dimitrova
The reactive load regime in the electric power systems of the economic sites determines the electrical energy quality (voltage deviation), the power losses in the individual elements of the power supply system, the electricity cost. From this point of view, the compensation of reactive loads is a major task in the design and operation of power supply systems.In order to increase the efficiency of reactive power compensation, it is necessary to optimize the operating mode of the installed power factor (PF) correction devices. In the report, the capacitor banks are presented as widely applicable in the industry and as an effective and easy-to-use tool for reactive power compensation.This report presents the development of an objective function for operating modes optimization of the capacitor banks in a case of centralized management. The optimization criterion is to minimize the cost of reactive power transmission in the power distribution system. The constraints for the objective function are also considered here.
{"title":"Operating Modes Optimization of the Capacitor Banks in Electrical Power Systems","authors":"Nikolay Matanov, S. Dimitrova","doi":"10.1109/BULEF.2018.8646938","DOIUrl":"https://doi.org/10.1109/BULEF.2018.8646938","url":null,"abstract":"The reactive load regime in the electric power systems of the economic sites determines the electrical energy quality (voltage deviation), the power losses in the individual elements of the power supply system, the electricity cost. From this point of view, the compensation of reactive loads is a major task in the design and operation of power supply systems.In order to increase the efficiency of reactive power compensation, it is necessary to optimize the operating mode of the installed power factor (PF) correction devices. In the report, the capacitor banks are presented as widely applicable in the industry and as an effective and easy-to-use tool for reactive power compensation.This report presents the development of an objective function for operating modes optimization of the capacitor banks in a case of centralized management. The optimization criterion is to minimize the cost of reactive power transmission in the power distribution system. The constraints for the objective function are also considered here.","PeriodicalId":416020,"journal":{"name":"2018 10th Electrical Engineering Faculty Conference (BulEF)","volume":"141 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131867200","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 : 2018-09-01DOI: 10.1109/BULEF.2018.8646954
P. Danchev, Daniel Dobrilov, A. Tsolov
Given the relatively low cost of dry power transformers compared to shunt reactors, a non-standard, but technically efficient and cost-effective solution for regulating the power consumption to compensate for medium voltage cable lines is the use of dry power transformers. To investigate this possibility, the report explores a sub magnetization of one of the coils of power distribution transformers by means of a frequency controller for asynchronous motors controlled by an programmable logic controller.
{"title":"Innovative method of compensating reactive capacitive power in distribution networks","authors":"P. Danchev, Daniel Dobrilov, A. Tsolov","doi":"10.1109/BULEF.2018.8646954","DOIUrl":"https://doi.org/10.1109/BULEF.2018.8646954","url":null,"abstract":"Given the relatively low cost of dry power transformers compared to shunt reactors, a non-standard, but technically efficient and cost-effective solution for regulating the power consumption to compensate for medium voltage cable lines is the use of dry power transformers. To investigate this possibility, the report explores a sub magnetization of one of the coils of power distribution transformers by means of a frequency controller for asynchronous motors controlled by an programmable logic controller.","PeriodicalId":416020,"journal":{"name":"2018 10th Electrical Engineering Faculty Conference (BulEF)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125634684","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 : 2018-09-01DOI: 10.1109/BULEF.2018.8646931
M. Mehmed-Hamza, Plamen Stanchev, M. Yordanova
In the medium voltage power lines there is a tendency of enlargement of the cable part. This in turn leads to increase of the earth-fault currents. The practical experience has shown that it is important to consider that enlargement when designing the grounding of the neutral of mixed or cable power lines for medium voltage (normally through an active resistance). The value of the earth-fault current Ig has to be limited in view of limitation the level of the overvoltages and the damages of the equipment, the requirements for the selectiveness and the sensitiveness of the relay protection, the permissible touch Ut and step Us voltages at the earth-fault place. The purpose of the paper is to investigate the operation of the relay protection and the electrical safety in the conditions of enlargement of the share of the cable part in the medium voltage power lines. The values of the possible touch and step voltages have been compared with the maximum permitted values, calculated according to the international IEEE 80-2000 standard Guide for Safety in AC Substation Grounding.
{"title":"Investigation of the Relay Protection Operation and the Electrical Safety at the Presence of Predominant Cable Part in Medium Voltage Power Lines","authors":"M. Mehmed-Hamza, Plamen Stanchev, M. Yordanova","doi":"10.1109/BULEF.2018.8646931","DOIUrl":"https://doi.org/10.1109/BULEF.2018.8646931","url":null,"abstract":"In the medium voltage power lines there is a tendency of enlargement of the cable part. This in turn leads to increase of the earth-fault currents. The practical experience has shown that it is important to consider that enlargement when designing the grounding of the neutral of mixed or cable power lines for medium voltage (normally through an active resistance). The value of the earth-fault current Ig has to be limited in view of limitation the level of the overvoltages and the damages of the equipment, the requirements for the selectiveness and the sensitiveness of the relay protection, the permissible touch Ut and step Us voltages at the earth-fault place. The purpose of the paper is to investigate the operation of the relay protection and the electrical safety in the conditions of enlargement of the share of the cable part in the medium voltage power lines. The values of the possible touch and step voltages have been compared with the maximum permitted values, calculated according to the international IEEE 80-2000 standard Guide for Safety in AC Substation Grounding.","PeriodicalId":416020,"journal":{"name":"2018 10th Electrical Engineering Faculty Conference (BulEF)","volume":"349 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116316899","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 : 2018-09-01DOI: 10.1109/BULEF.2018.8646957
Margreta P. Vasileva, Danail Stanchev
Lightning strokes on overhead transmission lines cause overvoltage surges, which propagate along the power line in the form of traveling waves. These overvoltages endangered the reliability of overhead transmission line and substation equipment. Lightning overvoltages are one of the most important factors in designing of substation and overhead lines insulation. This paper presents various lightning overvoltages in real electrical substation 220 kV due to shielding failure of overhead transmission line based on model study with ATP-EMTP software.
{"title":"Lightning overvoltages in electrical substation 220 kv due to shielding failure of overhead transmission line","authors":"Margreta P. Vasileva, Danail Stanchev","doi":"10.1109/BULEF.2018.8646957","DOIUrl":"https://doi.org/10.1109/BULEF.2018.8646957","url":null,"abstract":"Lightning strokes on overhead transmission lines cause overvoltage surges, which propagate along the power line in the form of traveling waves. These overvoltages endangered the reliability of overhead transmission line and substation equipment. Lightning overvoltages are one of the most important factors in designing of substation and overhead lines insulation. This paper presents various lightning overvoltages in real electrical substation 220 kV due to shielding failure of overhead transmission line based on model study with ATP-EMTP software.","PeriodicalId":416020,"journal":{"name":"2018 10th Electrical Engineering Faculty Conference (BulEF)","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121895578","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 : 2018-09-01DOI: 10.1109/BULEF.2018.8646928
Danail Stanchev
Lightning performance of transmission network and power substations has a huge significance for power system reliability and national economic. Back flashover phenomenon is one of the major factors for overhead line outages. In order to achieve minimum of these disturbance there are a lot of lightning studies. This paper presents analysis and evaluation of the incoming surges at air-insulated outdoor 220 kV power substation due to back flashover through ATP-EMTP based model study.
{"title":"Model study of lightning overvoltages in substation due to back flashover of overhead transmission line 220 kv","authors":"Danail Stanchev","doi":"10.1109/BULEF.2018.8646928","DOIUrl":"https://doi.org/10.1109/BULEF.2018.8646928","url":null,"abstract":"Lightning performance of transmission network and power substations has a huge significance for power system reliability and national economic. Back flashover phenomenon is one of the major factors for overhead line outages. In order to achieve minimum of these disturbance there are a lot of lightning studies. This paper presents analysis and evaluation of the incoming surges at air-insulated outdoor 220 kV power substation due to back flashover through ATP-EMTP based model study.","PeriodicalId":416020,"journal":{"name":"2018 10th Electrical Engineering Faculty Conference (BulEF)","volume":"149 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122458146","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 : 2018-09-01DOI: 10.1109/BULEF.2018.8646923
S. Tzvetkova, A. Georgieva, Angel Petleshkov
The report gives results of measuring and analyzing the quality indicators of electrical energy in the power supply system of an optical cable manufacturer. The purpose of the survey is to evaluate the quality indicators of electrical energy and to prove or disapprove the good quality of the electrical energy supplied to the company.
{"title":"Estimation of the electrical energy quality indicators in the power supply system of an optical cable manufacturer","authors":"S. Tzvetkova, A. Georgieva, Angel Petleshkov","doi":"10.1109/BULEF.2018.8646923","DOIUrl":"https://doi.org/10.1109/BULEF.2018.8646923","url":null,"abstract":"The report gives results of measuring and analyzing the quality indicators of electrical energy in the power supply system of an optical cable manufacturer. The purpose of the survey is to evaluate the quality indicators of electrical energy and to prove or disapprove the good quality of the electrical energy supplied to the company.","PeriodicalId":416020,"journal":{"name":"2018 10th Electrical Engineering Faculty Conference (BulEF)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125086485","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 : 2018-09-01DOI: 10.1109/BULEF.2018.8646959
L. Antonova
Partial discharge (PD) signals and monitoring are used to evaluate the condition of insulation in several power devices. This is the dominant investigation tool for condition monitoring of insulation is PD measurements in high voltage equipment. There are several noises like White noise, Random noise, Discrete Spectral Interferences (DSI) that severely polluted the PD signal. This pollution noise is the major problem behind PD signal and the big challenge is to removing these noise from the onsite PD data effectively. Removing it will leads to preserving the signal for feature extraction. Compared to conventional signal processing techniques, the use of the wavelet transform (WT) technology offers many advantages and is ideally suited for processing high voltage transients and measurements. In analyzing signals with interesting transient information such as PD signals WT seems to be more suitable than traditional Fourier Transform.
{"title":"The Wavelet Filters Recognising of Partial Discharge Location","authors":"L. Antonova","doi":"10.1109/BULEF.2018.8646959","DOIUrl":"https://doi.org/10.1109/BULEF.2018.8646959","url":null,"abstract":"Partial discharge (PD) signals and monitoring are used to evaluate the condition of insulation in several power devices. This is the dominant investigation tool for condition monitoring of insulation is PD measurements in high voltage equipment. There are several noises like White noise, Random noise, Discrete Spectral Interferences (DSI) that severely polluted the PD signal. This pollution noise is the major problem behind PD signal and the big challenge is to removing these noise from the onsite PD data effectively. Removing it will leads to preserving the signal for feature extraction. Compared to conventional signal processing techniques, the use of the wavelet transform (WT) technology offers many advantages and is ideally suited for processing high voltage transients and measurements. In analyzing signals with interesting transient information such as PD signals WT seems to be more suitable than traditional Fourier Transform.","PeriodicalId":416020,"journal":{"name":"2018 10th Electrical Engineering Faculty Conference (BulEF)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129245737","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 : 2018-09-01DOI: 10.1109/BULEF.2018.8646960
Valentin Kolev, S. Sulakov
During the summer heats, the power system loads reach winter peaks values due to the air-conditioning. In the same time the routine network maintenance is at its culmination, respectively the network resistance is lower than the winter values. As result, during two years of experience in forecasting hourly transmission losses an increasing is detected when extreme heats are happen. In order to detect accurately losses dependence on combination between network maintenance and summer heats, statistical techniques are applied. Finally, the existing forecasting model of the transmission system operator is upgraded.
{"title":"The transmission losses increasing during the summer network maintenance","authors":"Valentin Kolev, S. Sulakov","doi":"10.1109/BULEF.2018.8646960","DOIUrl":"https://doi.org/10.1109/BULEF.2018.8646960","url":null,"abstract":"During the summer heats, the power system loads reach winter peaks values due to the air-conditioning. In the same time the routine network maintenance is at its culmination, respectively the network resistance is lower than the winter values. As result, during two years of experience in forecasting hourly transmission losses an increasing is detected when extreme heats are happen. In order to detect accurately losses dependence on combination between network maintenance and summer heats, statistical techniques are applied. Finally, the existing forecasting model of the transmission system operator is upgraded.","PeriodicalId":416020,"journal":{"name":"2018 10th Electrical Engineering Faculty Conference (BulEF)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129195258","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 : 2018-09-01DOI: 10.1109/BULEF.2018.8646935
E. Dimitrova, Plamen Atanasov
DFTCalc and YAMS (using the model drawn in KB3) can simulate models - static as well as dynamic fault trees with unrepairable elements. It is necessary for this to build the fault tree and to enter the failure rates of the individual elements (basic events). In KB3 this is done by means of a graphical user interface (GUI), after that the model is simulated by YAMS. In DFTCalc this is achieved by writing in the Galileo language, which reflects the structure and parameters of the tree.
{"title":"Transition between languages for description of probabilistic models","authors":"E. Dimitrova, Plamen Atanasov","doi":"10.1109/BULEF.2018.8646935","DOIUrl":"https://doi.org/10.1109/BULEF.2018.8646935","url":null,"abstract":"DFTCalc and YAMS (using the model drawn in KB3) can simulate models - static as well as dynamic fault trees with unrepairable elements. It is necessary for this to build the fault tree and to enter the failure rates of the individual elements (basic events). In KB3 this is done by means of a graphical user interface (GUI), after that the model is simulated by YAMS. In DFTCalc this is achieved by writing in the Galileo language, which reflects the structure and parameters of the tree.","PeriodicalId":416020,"journal":{"name":"2018 10th Electrical Engineering Faculty Conference (BulEF)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128670226","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 : 2018-09-01DOI: 10.1109/BULEF.2018.8646934
Y. Shopov, S. Filipova-Petrakieva
In the present paper the influence of the working conditions on the parameters of the transformers is analyzed. The main dependencies between electrical and magnetic quantities are given. The conditions of open circuit and circuit under load are analyzed based on the processes, in the magnetic core. On this base some conclusions about the influence of these two conditions on the inductance of the coils in transformers are made.
{"title":"Influence of the Working Conditions on the Parameters of the Transformers","authors":"Y. Shopov, S. Filipova-Petrakieva","doi":"10.1109/BULEF.2018.8646934","DOIUrl":"https://doi.org/10.1109/BULEF.2018.8646934","url":null,"abstract":"In the present paper the influence of the working conditions on the parameters of the transformers is analyzed. The main dependencies between electrical and magnetic quantities are given. The conditions of open circuit and circuit under load are analyzed based on the processes, in the magnetic core. On this base some conclusions about the influence of these two conditions on the inductance of the coils in transformers are made.","PeriodicalId":416020,"journal":{"name":"2018 10th Electrical Engineering Faculty Conference (BulEF)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133128887","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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