Pub Date : 2022-09-14DOI: 10.1109/BulEF56479.2022.10021163
Z. Zarkov, V. Milenov
Self-consumption for residential and industrial buildings is important in order to reduce energy consumption from the electricity grid. As energy prices rise, more and more consumers are installing PV systems for their self-consumption. Self-consumption systems have a number of specific difficulties to solve related to variations in solar energy production and the user's load profile. Each installed system will contribute to the reduction of CO2 emissions and encourage the installation of low-power PV systems to produce green energy. In this way, users will reduce their dependence on the use of energy from the mains. The aim of this work is to develop simulation model for calculation of energy balance of PV system for self-consumption. Comparison of performance of two PV system types is done - without and with battery storage.
{"title":"Study of PV System for Electricity Production for Self-Consumption","authors":"Z. Zarkov, V. Milenov","doi":"10.1109/BulEF56479.2022.10021163","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10021163","url":null,"abstract":"Self-consumption for residential and industrial buildings is important in order to reduce energy consumption from the electricity grid. As energy prices rise, more and more consumers are installing PV systems for their self-consumption. Self-consumption systems have a number of specific difficulties to solve related to variations in solar energy production and the user's load profile. Each installed system will contribute to the reduction of CO2 emissions and encourage the installation of low-power PV systems to produce green energy. In this way, users will reduce their dependence on the use of energy from the mains. The aim of this work is to develop simulation model for calculation of energy balance of PV system for self-consumption. Comparison of performance of two PV system types is done - without and with battery storage.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133899733","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 : 2022-09-14DOI: 10.1109/BulEF56479.2022.10021203
K. Milanov, A. Georgieva
The article describes a practical optimization of a single-phase electric motor's control using a three-phase frequency converter and a choke. The value of the inductance of the choke used in the circuit diagram was optimized using three values. The goal is to choose an inductance value that brings the form of an electric motor's supply voltage as close to the parameters of a conventional supply network as possible. The waveforms of the single-phase motor's input voltage are captured with an oscilloscope as the primary criterion for successful optimization. The fact that the electric motor is a component of a larger, more sophisticated robotic system that requires robust control makes speed control of the electric motor necessary.
{"title":"Optimization of an Electric Motor Control System for a Robotic System","authors":"K. Milanov, A. Georgieva","doi":"10.1109/BulEF56479.2022.10021203","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10021203","url":null,"abstract":"The article describes a practical optimization of a single-phase electric motor's control using a three-phase frequency converter and a choke. The value of the inductance of the choke used in the circuit diagram was optimized using three values. The goal is to choose an inductance value that brings the form of an electric motor's supply voltage as close to the parameters of a conventional supply network as possible. The waveforms of the single-phase motor's input voltage are captured with an oscilloscope as the primary criterion for successful optimization. The fact that the electric motor is a component of a larger, more sophisticated robotic system that requires robust control makes speed control of the electric motor necessary.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129806189","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 : 2022-09-14DOI: 10.1109/BulEF56479.2022.10021156
Margreta P. Vasileva, Iva Draganova-Zlateva, Neli Zafiroska
Partial discharges are electrical discharges in an insulation system confined to only a portion of the dielectric. They develop into gas bubbles formed in the volume of the solid dielectric. The Partial discharges are one of the main causes of insulation aging. Their single action has no practical effect on the insulation, but their prolonged action, accompanied by an increase in their intensity, leads to a slow destruction of the insulation and to its complete penetration. The article proposes a modeling of an insulation system with the development of a partial discharge in a solid dielectric.
{"title":"Simulation modeling of an insulation system with the development of a partial discharge in the volume of a solid dielectric","authors":"Margreta P. Vasileva, Iva Draganova-Zlateva, Neli Zafiroska","doi":"10.1109/BulEF56479.2022.10021156","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10021156","url":null,"abstract":"Partial discharges are electrical discharges in an insulation system confined to only a portion of the dielectric. They develop into gas bubbles formed in the volume of the solid dielectric. The Partial discharges are one of the main causes of insulation aging. Their single action has no practical effect on the insulation, but their prolonged action, accompanied by an increase in their intensity, leads to a slow destruction of the insulation and to its complete penetration. The article proposes a modeling of an insulation system with the development of a partial discharge in a solid dielectric.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116018507","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 : 2022-09-14DOI: 10.1109/BulEF56479.2022.10021177
B. Boychev
The paper discusses ways to reduce electricity costs by using solar energy.
本文讨论了利用太阳能降低电费的方法。
{"title":"Reducing electricity costs in a hospital","authors":"B. Boychev","doi":"10.1109/BulEF56479.2022.10021177","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10021177","url":null,"abstract":"The paper discusses ways to reduce electricity costs by using solar energy.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"173 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116134300","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 : 2022-09-14DOI: 10.1109/BulEF56479.2022.10021206
B. Boychev
Elegas (SF6) exhibits very good insulating properties. Unfortunately, it has a global warming potential (GWP), which is 23,500 times greater than the respective one of carbon dioxide. Recently, however, due to the controversial qualities of the gas, the EU has banned many of the F-gases, and SF6 is now banned for many applications. This means that it is highly necessary to look for alternative gases to SF6 that have the same insulating qualities, but without causing an increase in the greenhouse effect. Perfluorinated ketones (C5F10O and C6F12O) and fluoronitrile (C4F7N) gases are an equal competitor to SF6 due to their insulating properties. In this sense, these gases can be used in some electrical devices instead of elegas SF6.
{"title":"Comparison of SF6 alternative gases","authors":"B. Boychev","doi":"10.1109/BulEF56479.2022.10021206","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10021206","url":null,"abstract":"Elegas (SF6) exhibits very good insulating properties. Unfortunately, it has a global warming potential (GWP), which is 23,500 times greater than the respective one of carbon dioxide. Recently, however, due to the controversial qualities of the gas, the EU has banned many of the F-gases, and SF6 is now banned for many applications. This means that it is highly necessary to look for alternative gases to SF6 that have the same insulating qualities, but without causing an increase in the greenhouse effect. Perfluorinated ketones (C5F10O and C6F12O) and fluoronitrile (C4F7N) gases are an equal competitor to SF6 due to their insulating properties. In this sense, these gases can be used in some electrical devices instead of elegas SF6.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132251733","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 : 2022-09-14DOI: 10.1109/BulEF56479.2022.10021167
M. Zlateva
The article presents the results of the research and analysis of the influence of some major design and operational parameters of thermal solar systems on the conversion efficiency of the solar radiation into heat. For a long-term evaluation, the solar fraction and efficiency criteria were used, as well as the specific annual energy converted by the system. With the help of the financial analysis, in terms of the maximum net present value, the optimal specific storage tank volume was determined in systems with different daily consumption profile and substituted energy electricity.
{"title":"Influence of some operational and economic parameters on the optimal storage tank volume in thermal solar systems","authors":"M. Zlateva","doi":"10.1109/BulEF56479.2022.10021167","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10021167","url":null,"abstract":"The article presents the results of the research and analysis of the influence of some major design and operational parameters of thermal solar systems on the conversion efficiency of the solar radiation into heat. For a long-term evaluation, the solar fraction and efficiency criteria were used, as well as the specific annual energy converted by the system. With the help of the financial analysis, in terms of the maximum net present value, the optimal specific storage tank volume was determined in systems with different daily consumption profile and substituted energy electricity.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"166 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132035021","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 : 2022-09-14DOI: 10.1109/BulEF56479.2022.10021154
Margreta P. Vasileva, Iva Draganova-Zlateva, Neli Zafiroska
Different types of dielectrics are used in the manufacture of insulation systems of electrical equipment. Each individual facility may have a different type of insulation defect. On the basis of a developed simulation model, the report presents a variant study of partial discharge in different dielectric media, at different sizes of the applied voltage and different sizes of air inclusion.
{"title":"Results of simulation modeling of an insulation system with the development of a partial discharge in the volume of a solid dielectric","authors":"Margreta P. Vasileva, Iva Draganova-Zlateva, Neli Zafiroska","doi":"10.1109/BulEF56479.2022.10021154","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10021154","url":null,"abstract":"Different types of dielectrics are used in the manufacture of insulation systems of electrical equipment. Each individual facility may have a different type of insulation defect. On the basis of a developed simulation model, the report presents a variant study of partial discharge in different dielectric media, at different sizes of the applied voltage and different sizes of air inclusion.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"141 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114222493","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 : 2022-09-14DOI: 10.1109/BulEF56479.2022.10021159
Nikolai Vitkov
The purpose of this paper is to formulate guidelines on the selection of battery chemistry for stationary renewable energy storage in relation to National Plan for Recovery and Sustainability of the Republic of Bulgaria, version 1.5 of 06.04.2022 [1]. The main technical characteristics of traditional chemical sources of electricity, lead-acid and Li-ion batteries are discussed. The main technical characteristics of traditional power chemistries, lead-acid and Li-ion batteries are discussed with the comparative review highlighting LTO and LFP as the most suitable among lithium chemistries and VRLA among lead-acid battery designs. LTO chemistry was rejected as potentially feasible due to its high cost. Economic considerations are set out on the rationale for the selection of battery chemistry for RES for the period 2020–2030. The comparison of the two chemistries LFP and LA shows a marginal economic advantage of LFP towards 2020 with a trend towards increasing by 2030 due to the forecast in [4] of cheaper LFP technology in the coming years. LFP technology has been recommended as the most promising for the construction of electricity storage facilities in Bulgaria, but without denying the future of LA chemistry.
{"title":"Energy Storage in Bulgaria - Lead Acid or Lithium - Ion Chemistry","authors":"Nikolai Vitkov","doi":"10.1109/BulEF56479.2022.10021159","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10021159","url":null,"abstract":"The purpose of this paper is to formulate guidelines on the selection of battery chemistry for stationary renewable energy storage in relation to National Plan for Recovery and Sustainability of the Republic of Bulgaria, version 1.5 of 06.04.2022 [1]. The main technical characteristics of traditional chemical sources of electricity, lead-acid and Li-ion batteries are discussed. The main technical characteristics of traditional power chemistries, lead-acid and Li-ion batteries are discussed with the comparative review highlighting LTO and LFP as the most suitable among lithium chemistries and VRLA among lead-acid battery designs. LTO chemistry was rejected as potentially feasible due to its high cost. Economic considerations are set out on the rationale for the selection of battery chemistry for RES for the period 2020–2030. The comparison of the two chemistries LFP and LA shows a marginal economic advantage of LFP towards 2020 with a trend towards increasing by 2030 due to the forecast in [4] of cheaper LFP technology in the coming years. LFP technology has been recommended as the most promising for the construction of electricity storage facilities in Bulgaria, but without denying the future of LA chemistry.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122191434","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 : 2022-09-14DOI: 10.1109/BulEF56479.2022.10021185
Gergana Vacheva, Plamen Stanchev, N. Hinov
In this research a mathematical model of a coupled permanent magnet synchronous machines is realized in MATLAB/Simulink environment. In the model of the machines are included the aerodynamic force and the friction force as a resistance moment. For the simulation are used two different international driving cycle: WLTC class 1 and WLTC class3. The characteristics of the electric vehicles are provided by the manufacturer.
{"title":"Modeling and Simulation of Coupled PMSM","authors":"Gergana Vacheva, Plamen Stanchev, N. Hinov","doi":"10.1109/BulEF56479.2022.10021185","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10021185","url":null,"abstract":"In this research a mathematical model of a coupled permanent magnet synchronous machines is realized in MATLAB/Simulink environment. In the model of the machines are included the aerodynamic force and the friction force as a resistance moment. For the simulation are used two different international driving cycle: WLTC class 1 and WLTC class3. The characteristics of the electric vehicles are provided by the manufacturer.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130248295","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 : 2022-09-14DOI: 10.1109/BulEF56479.2022.10021186
Georgi Ivanov, V. Mateev, I. Marinova
This paper presents some transient and static characteristics of hybrid high temperature superconducting (HTS) flat coil prototypes. Two HTS coil prototypes were designed using 3D CAD software for working in hybrid HTS system consisting of superconducting part (in cold condition) and nonsuperconducting part (in warm condition). The coils consist of HTS flat composite wires with superconducting layer of GdBCO. Inductance of the created coils was calculated using existing analytical formulas and measured experimentally in warm and cold (superconducting) state. Theoretically, calculated inductance was compared with measured values. Critical temperature and resistance were measured during the transition from superconducting to nonsuperconducting state. A design for coreless superconducting transformer was proposed and tested. This design is suitable for superconducting wireless power transfer with very high efficiency.
{"title":"Static and Transient Characteristics of Hybrid HTS Coils","authors":"Georgi Ivanov, V. Mateev, I. Marinova","doi":"10.1109/BulEF56479.2022.10021186","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10021186","url":null,"abstract":"This paper presents some transient and static characteristics of hybrid high temperature superconducting (HTS) flat coil prototypes. Two HTS coil prototypes were designed using 3D CAD software for working in hybrid HTS system consisting of superconducting part (in cold condition) and nonsuperconducting part (in warm condition). The coils consist of HTS flat composite wires with superconducting layer of GdBCO. Inductance of the created coils was calculated using existing analytical formulas and measured experimentally in warm and cold (superconducting) state. Theoretically, calculated inductance was compared with measured values. Critical temperature and resistance were measured during the transition from superconducting to nonsuperconducting state. A design for coreless superconducting transformer was proposed and tested. This design is suitable for superconducting wireless power transfer with very high efficiency.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122354071","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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