Pub Date : 2022-09-14DOI: 10.1109/BulEF56479.2022.10021204
Orlin Tomov
The paper justifies the motivation behind a research and development project for a burner for pelletized agricultural waste - wheat straw, rapeseed straw, cornstalks, sunflower husks and many others. The result of an experiment made with different traditional constructions of burners for burning straw pellets has been discussed and the results have been summarized. An analysis of the energy density of these products and a comparison with the traditional products for pellets production is provided. In the paper are discussed the reasons why this waste is problematic for the agricultural producers, and why until now it was not used as a fuel for heating appliances. A chemical analysis of the waste products from the burning of straw pellets is presented, and the result is compared with the optimal soil content for growing wheat. Discussed are the benefits from this process for the ecology, farmers, households and last but not least - economic benefits
{"title":"A Background Research Behind the Development of a Straw Pellet Burner","authors":"Orlin Tomov","doi":"10.1109/BulEF56479.2022.10021204","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10021204","url":null,"abstract":"The paper justifies the motivation behind a research and development project for a burner for pelletized agricultural waste - wheat straw, rapeseed straw, cornstalks, sunflower husks and many others. The result of an experiment made with different traditional constructions of burners for burning straw pellets has been discussed and the results have been summarized. An analysis of the energy density of these products and a comparison with the traditional products for pellets production is provided. In the paper are discussed the reasons why this waste is problematic for the agricultural producers, and why until now it was not used as a fuel for heating appliances. A chemical analysis of the waste products from the burning of straw pellets is presented, and the result is compared with the optimal soil content for growing wheat. Discussed are the benefits from this process for the ecology, farmers, households and last but not least - economic benefits","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"42 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":"124765002","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/BulEF56479.2022.10021161
Nikolai Vitkov
The purpose of this report is to investigate and compare the environmental and health risks of the selection of chemistry for electrical energy storage in Bulgaria at the end-of-life stage of the batteries and the inevitable decommissioning that must be followed by safe transportation and recycling. According to National Plan for Recovery and Sustainability of the Republic of Bulgaria, version 1.5 of 06.04.2022 [1], is expected to be generated large quantities of hazardous waste from electric batteries in the not too distant future. The choice of battery chemistry is determinant for the recycling procedures of these wastes. Two battery chemistries considered most promising for stationary electrical energy storage - Lead Acid (LA) and Lithium-ion-Iron (Ferrous) -Phosphate (LFP). Lead-acid chemistry is well developed in the western world, including Bulgaria, and would be a logical choice, but is many times less efficient than lithium chemistry, which can only be imported from the major producers in the East. The recycling of the waste from the two chemistries is fundamentally different - the lead chemistry can be recycled in Bulgaria in compliance with environmental and health standards or in neighboring European countries, while the lithium is likely to be recycled where it is produced (if there will obtain technological breakt$h$roug$h$) - in a country in the Far East with the corresponding transport and processing costs to be budgeted in the financial assessment of the projects. Unless a technological breakthrough occurs, there remains disposal of LFPs batteries with a high risk of large-scale explosions and fires at disposal sites with the risk of harm to people and severe environmental consequences.
{"title":"Environmental and Health Challenges in Battery Recycling in Bulgaria","authors":"Nikolai Vitkov","doi":"10.1109/BulEF56479.2022.10021161","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10021161","url":null,"abstract":"The purpose of this report is to investigate and compare the environmental and health risks of the selection of chemistry for electrical energy storage in Bulgaria at the end-of-life stage of the batteries and the inevitable decommissioning that must be followed by safe transportation and recycling. According to National Plan for Recovery and Sustainability of the Republic of Bulgaria, version 1.5 of 06.04.2022 [1], is expected to be generated large quantities of hazardous waste from electric batteries in the not too distant future. The choice of battery chemistry is determinant for the recycling procedures of these wastes. Two battery chemistries considered most promising for stationary electrical energy storage - Lead Acid (LA) and Lithium-ion-Iron (Ferrous) -Phosphate (LFP). Lead-acid chemistry is well developed in the western world, including Bulgaria, and would be a logical choice, but is many times less efficient than lithium chemistry, which can only be imported from the major producers in the East. The recycling of the waste from the two chemistries is fundamentally different - the lead chemistry can be recycled in Bulgaria in compliance with environmental and health standards or in neighboring European countries, while the lithium is likely to be recycled where it is produced (if there will obtain technological breakt$h$roug$h$) - in a country in the Far East with the corresponding transport and processing costs to be budgeted in the financial assessment of the projects. Unless a technological breakthrough occurs, there remains disposal of LFPs batteries with a high risk of large-scale explosions and fires at disposal sites with the risk of harm to people and severe environmental consequences.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"56 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":"130376544","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/BulEF56479.2022.10020198
Y. Shopov, S. Filipova-Petrakieva
In some situations, the electrical consumers are supplied by the reduced power supply voltage. According to the standard, the permissible variation of its effective value is $+/-10$ % of 230 V. However, in some small rural villages remote from the power supply it may be reduced to 150 V. In this case the increase in the nominal values can be realized by the use of booster transformers, so the supply voltage is kept within the acceptable range of variation defined in the standards. In this paper, a solution to control the supply voltage with a step of 5 % between 5 % to 35 % is suggested. It is realized by three transformers with secondary windings connected in series to the network voltage. When the voltage is within the acceptable range, the transformers are switched off. When the voltage supplied to the consumers falls below the permissible value, switching off one, two, or three of the transformers is carried out. As a result, additional voltage is added to the network supply. This ensures that the supply voltage is always within the acceptable range. A problem of the functioning of transformers is the switching between on and off state. During the commutation, they are in “a current transformer” mode. It means that unacceptable over-voltages, including insulation breakdowns, are possible. In this paper, a solution to this problem is proposed and an analysis is performed to study the progress of transient responses in the circuit related to the primary of the transformer. The efficiency of the suggested solution is confirmed by simulations with software OrCAD PSpice 9.1. The results of the simulations confirm the reliability and effectiveness of the under-voltage compensation solution.
{"title":"Supply Voltage Control Using Booster Transformers","authors":"Y. Shopov, S. Filipova-Petrakieva","doi":"10.1109/BulEF56479.2022.10020198","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10020198","url":null,"abstract":"In some situations, the electrical consumers are supplied by the reduced power supply voltage. According to the standard, the permissible variation of its effective value is $+/-10$ % of 230 V. However, in some small rural villages remote from the power supply it may be reduced to 150 V. In this case the increase in the nominal values can be realized by the use of booster transformers, so the supply voltage is kept within the acceptable range of variation defined in the standards. In this paper, a solution to control the supply voltage with a step of 5 % between 5 % to 35 % is suggested. It is realized by three transformers with secondary windings connected in series to the network voltage. When the voltage is within the acceptable range, the transformers are switched off. When the voltage supplied to the consumers falls below the permissible value, switching off one, two, or three of the transformers is carried out. As a result, additional voltage is added to the network supply. This ensures that the supply voltage is always within the acceptable range. A problem of the functioning of transformers is the switching between on and off state. During the commutation, they are in “a current transformer” mode. It means that unacceptable over-voltages, including insulation breakdowns, are possible. In this paper, a solution to this problem is proposed and an analysis is performed to study the progress of transient responses in the circuit related to the primary of the transformer. The efficiency of the suggested solution is confirmed by simulations with software OrCAD PSpice 9.1. The results of the simulations confirm the reliability and effectiveness of the under-voltage compensation solution.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"47 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":"127492356","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/BulEF56479.2022.10021152
R. Stanev, Dimo Siderov, Kostadin Viglov, V. Efthymiou, S. Khadem, C. Charalambous
The massive presence of DC Distributed Energy Resources (DER), the fast growing Electric Vehicle (EV) infrastructure and the dominance of DC based consumers gave significant pace for development of Low Voltage Direct Current (LVDC) grids. This paper presents a new concept, control paradigm and Dynamic Pricing Scheme for Low Voltage Direct Current Networks. The concept and market scheme rely on a leading signal based on the network parameters at the point of common coupling (PCC) which makes it simple, safe, easy to implement and reliable. The main methodological and economic concepts are presented after which a Power Hardware in the Loop (PHiL) laboratory demonstration experiment with flexible load control is performed and presented. Based on the results obtained some valuable conclusions are made.
{"title":"New Control Paradigm and Dynamic Pricing Scheme for Low Voltage Direct Current Networks","authors":"R. Stanev, Dimo Siderov, Kostadin Viglov, V. Efthymiou, S. Khadem, C. Charalambous","doi":"10.1109/BulEF56479.2022.10021152","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10021152","url":null,"abstract":"The massive presence of DC Distributed Energy Resources (DER), the fast growing Electric Vehicle (EV) infrastructure and the dominance of DC based consumers gave significant pace for development of Low Voltage Direct Current (LVDC) grids. This paper presents a new concept, control paradigm and Dynamic Pricing Scheme for Low Voltage Direct Current Networks. The concept and market scheme rely on a leading signal based on the network parameters at the point of common coupling (PCC) which makes it simple, safe, easy to implement and reliable. The main methodological and economic concepts are presented after which a Power Hardware in the Loop (PHiL) laboratory demonstration experiment with flexible load control is performed and presented. Based on the results obtained some valuable conclusions are made.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"11 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":"125633664","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/BulEF56479.2022.10020205
Milen Duganov, V. Gyurov, P. Parushev
The paper presents the results of research into the influence of a controllable reactive power source on a series compensator in a electric power supply system. The main objective is to achieve assessment about the impact on the overload capability of power capacitors and non-sinusoidal current consumption modes. A simulation of this system was made using MATLAB Simulink, where the parameters of the real facilities are used. Having a physical and simulation model allows for more accurate calibration and creates a flexible research environment.
{"title":"Study on Influence of RL Load on the Operation Conditions of Capacitor Banks in a TCSC","authors":"Milen Duganov, V. Gyurov, P. Parushev","doi":"10.1109/BulEF56479.2022.10020205","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10020205","url":null,"abstract":"The paper presents the results of research into the influence of a controllable reactive power source on a series compensator in a electric power supply system. The main objective is to achieve assessment about the impact on the overload capability of power capacitors and non-sinusoidal current consumption modes. A simulation of this system was made using MATLAB Simulink, where the parameters of the real facilities are used. Having a physical and simulation model allows for more accurate calibration and creates a flexible research environment.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"24 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":"126901709","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/BulEF56479.2022.10020201
M. Ivanova, Emil Barudov
The issue of energy efficiency in water transport has become increasingly important over the years. A particularly popular method is the introduction of electric propulsion systems. Electric motors have much higher efficiency, low vibrations and noise, precise control and high power. Due to the high power of propulsion engines up to $130text{MW}$, it is necessary to introduce systems operating at high voltage. Modern ships use voltages of 6.6 $text{kV}$ and 11 $text{kV}$. Power transformers, generators and other electrical equipment generate low frequency electromagnetic fields. Due to the characteristics of ship spaces and the lack of enough distance from the equipment, a detailed study of the magnitude of the electromagnetic field created and introduction of adequate protections for the serving ship personnel are required. The work is dedicated to the research of the electromagnetic field created by the ship's power transformers and proposing adequate procedures and protection measures.
{"title":"Investigation of the electromagnetic field of marine high-voltage power transformers regarding the safety of the ship personnel","authors":"M. Ivanova, Emil Barudov","doi":"10.1109/BulEF56479.2022.10020201","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10020201","url":null,"abstract":"The issue of energy efficiency in water transport has become increasingly important over the years. A particularly popular method is the introduction of electric propulsion systems. Electric motors have much higher efficiency, low vibrations and noise, precise control and high power. Due to the high power of propulsion engines up to $130text{MW}$, it is necessary to introduce systems operating at high voltage. Modern ships use voltages of 6.6 $text{kV}$ and 11 $text{kV}$. Power transformers, generators and other electrical equipment generate low frequency electromagnetic fields. Due to the characteristics of ship spaces and the lack of enough distance from the equipment, a detailed study of the magnitude of the electromagnetic field created and introduction of adequate protections for the serving ship personnel are required. The work is dedicated to the research of the electromagnetic field created by the ship's power transformers and proposing adequate procedures and protection measures.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":"14 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":"121692485","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/BulEF56479.2022.10021195
R. Spasov, P. Rizov, V. Petrov
This research presented in this paper is focused on the magnetic field in synchronous generators with high power, in which the rotor slots are open and the rotor winding is strengthened by nonmagnetic metallic wedges. Using numerical modeling of the magnetic field the spatial distribution of magnetic induction was studied. The force effect of the magnetic field on the rotor wedges during rotor swing caused by short-term electrical grid disturbances has been determined.
{"title":"RESEARCH OF THE FORCE EFFECT ON THE ROTOR WEDGES IN SYNCHRONOUS GENERATORS","authors":"R. Spasov, P. Rizov, V. Petrov","doi":"10.1109/BulEF56479.2022.10021195","DOIUrl":"https://doi.org/10.1109/BulEF56479.2022.10021195","url":null,"abstract":"This research presented in this paper is focused on the magnetic field in synchronous generators with high power, in which the rotor slots are open and the rotor winding is strengthened by nonmagnetic metallic wedges. Using numerical modeling of the magnetic field the spatial distribution of magnetic induction was studied. The force effect of the magnetic field on the rotor wedges during rotor swing caused by short-term electrical grid disturbances has been determined.","PeriodicalId":375606,"journal":{"name":"2022 14th Electrical Engineering Faculty Conference (BulEF)","volume":" 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113951700","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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