Power electronics solution to dust emissions from thermal power plants

Thermal power stations emit significant amounts of fly ash and ultra fine particles into the atmosphere. Electrostatic precipitators (ESP) or electro filters remove flying ashes and fine particles from the flue gas before passing the gas into the chimney. Maximum allowable value of dust is 50 mg/m3 and it requires that the efficiency of the ESPs better than 99 %, which calls for an increase of active surface of the electrodes, hence increasing the filter volume and the weight of steel used for the filter. In previous decades, electrostatic precipitators in thermal power plants were fed by thyristor controlled, single phase fed devices having a high degree of reliability, but with a relatively low collection efficiency, hence requiring large effective surface of the collection plates and a large weight of steel construction in order to achieve the prescribed emission limits. Collection efficiency and energy efficiency of the electrostatic precipitator can be increased by applying high frequency high voltage power supply (HF HV). Electrical engineering faculty of the University of Belgrade (ETF) has developed technology and HF HV equipment for the ESP power supply. This solution was subjected to extensive experimental investigation at TE Morava from 2008 to 2010. High frequency power supply is proven to reduce emission two times in controlled conditions while increasing energy efficiency of the precipitator, compared to the conventional thyristor controlled 50Hz supply. Two high frequency high voltage unit AR70/1000 with parameters 70 kV and 1000 mA are installed at TE Morava and thoroughly testes. It was found that the HF HV power supply of the ESP at TE Morava increases collection efficiency so that emission of fine particles and flying ashes are halved, brought down to only 50 % of the emissions encountered with conventional 50 Hz thyristor driven power supplies. On the basis of this study, conclusion is drawn that the equipment comprising HF HV supplies are the best solution for new ESP installations, as well as for the reconstruction of existing facilities. The paper describes the topology of the HF HV power supply, power management and controls, and brings the most important details of the implementation. It is found that the HF HV solution achieves several significant improvements over the conventional thyristor system. It is possible to provide more precise control of the ESP parameters such as the output voltages and currents. It is also possible to make a rapid increase or decrease in voltage and to effectuate a very fast response to load changes. Due to this advantages it is possible to suppress the supply quickly in the case of sparking, reducing the spark energy and the quantity of ionized gasses produced by the electric arc. Reduction in the spark energy is up to 10 times compared to conventional thyristors solution. This means that the erosion of the electrode system is significantly reduced, and that the quality of the collection plates is preserved for much longer periods. At the same time, lower quantity of ionized gasses produced by the spark contribute to much shorter deionization intervals, required to quit sparking and evacuate charged particles in order to reinstate the voltage and proceed with the operation. In addition, HF HV power supply provides a significant reduction in size and weight of the complete ESP installation, hence reducing the tons of steel that has to be built in. Therefore, the HF HV power supply may be the key instrument to reducing the cost of the dedusting ecological equipment. Besides, size and weight reduction leads to cost savings of installation and maintenance. According to estimates, savings in steel may reach 30%, contributing to the overall cost savings of roughly 20%. Within this paper, in addition to describing the AR70/1000 unit topology and principles of operation, the paper presents the results and measurements obtained during extensive experimental investigations wherein performances of 50 Hz based thyristor units with T/R sets are compared to HF HV power supply

Modeliranje i upravljanje tokom rasutog materijala na elektromagnetskoj vibrirajućoj hranilici

This paper presents the results of modeling, simulation and experimental research of the bulk material flow on the electromagnetic vibratory feeder (EVF). The model of the EVF was implemented in Simulink/Matlab and verified in the experimental research. It has been experimentally confirmed that the bulk material flow rate has its maximal value as far as excitation frequency is equal to the EVF mechanical resonant frequency. For certain bulk material flow rate, average value of excitation coil current of EVF has minimal value when named frequencies are equal. In addition to modeling of the EVF, the main contribution of this paper is implementation of flow control algorithm of bulk material on EVF, experimental verification of the adopted model and defines parameters that enable the selection of energy-efficient operating point of the EVF.U ovom radu su predstavljeni rezultati modeliranja, simulacije i eksperimentalnog istraživanja toka rasutog materijala na elektromagnetskoj vibrirajućoj hranilici (EVF). Model EVF-a je implementiran u Simulinku/Matlabu i eksperimentalno provjeren. Eksperimentalno je potvrđeno da brzina toka rasutog materijala ima maksimalnu vrijednost dok je uzbudna frekvencija jednaka mehaničkoj rezonantnoj frekvenciji EVF-a. Za određene brzine tokova rasutog materijala, srednja vrijednost uzbudne struje zavojnice EVF-a ima minimalnu vrijednost u trenutku kada su nazivne frekvencije jednake. Uz model EVF-a glavni doprinosi ovog rada su implementacija algoritma za upravljanje tokom rasutog materijala na EVF-u, eksperimentalna potvrda razvijenog modela i definiranje parametara koji omogućuju izbor energetski efikasne radne točke EVF-a

Mathematical modeling of resonant linear vibratory conveyor with electromagnetic excitation: simulations and experimental results

Vibratory conveyors are commonly used in industry for transporting a wide variety of bulk and particulate materials. Various control structures based on state observers can be found in the literature. However, they are mostly based on simplified mathematical models. In order to obtain a more precise state observer, and consequently better performance and (or) control quality, more detailed mathematical model of the resonant vibratory conveyor is required. Mathematical model of a resonant linear vibratory conveyor driven by an electromagnetic excitation force is presented. Derivation of the mathematical model is based on the kinetic and potential energies, dissipative function of the mechanical system, and Lagrangian formulation. A simulation model is implemented on the basis of the derived mathematical equations. The simulation results are presented and compared to the experimental results obtained by a real industrial vibratory conveyor

Vibration control of resonant vibratory feeders with electromagnetic excitation

Vibracioni dodavači sa elektromagnetnom pobudom, odnosno elektromagnetni vibracioni dodavači (EMVD) su najčešće korišćeni u procesnoj industriji za obezbeđenje gravimetrijskog protoka sitnozrnih i rasutih materijala. Ovi pogoni obezbeđuju laku i jednostavnu kontrolu masenog protoka transportujućih materijala. U poređenju sa ostalim pogonima (pneumatskim, inercionim, centrifugalnim, itd.), oni su jednostavnije i kompaktnije konstrukcije, robusni i pouzdani u radu. Odsustvo habajući mehaničkih delova kao što su reduktori, kišnici, ekscentri i sl., čine EMVD veoma ekonomičnom opremom. Standardni pretvarački izlazni stepeni namenjeni za kontrolu EMVD su bazirani na SCR elementima (tiristorima i trijacima). Njihovo korišćenje podrazumeva korišćenje kontrole faznog ugla (KFU) i stoga konstantnu učestanost vibracija. Na ovaj način kontrolno kolo mora biti sinhronizovano sa mrežnom učestanošću 50(60)Hz. Uz pomoć KFU je jedino moguće ostvariti podešavanje amplitude vibracija, ali ne i njihove učestanosti. Primena prekidačkih tranzistorskih (IGBT ili MOSFET) energetskih pretvarača, omogućava amplitudsku i (ili) frekventnu kontrolu EMVD. Njihovo korišćenje podrazumeva pobudu EMVD nezavisno od mrežne učestanosti. Dodatno, frekventna kontrola dozvoljava rad u oblasti mehaničke rezonance. Rad u ovoj oblasti je veoma efikasan, pošto je moguće obezbediti značajne izlazne pomeraje, veoma malom ulaznom snagom. Optimalan i efikasan rad zahteva praćenje rezonantne učestanosti. U ovom radu su predstavljeni jedno moguće rešenje vibracione kontrole EMVD, kao i odgovarajući simulacioni i eksperimentalni rezultati.The vibratory feeders with electromagnetic excitation called electromagnetic vibratory feeders (EMVF) are commonly used for performing gravimetric flow of granular and particulate materials in processing industry. This drives offer easy and simple control the mass flow of conveying materials. In comparison with other drives (pneumatics, inertial, centrifugal, etc...), these have a more simple construction and they are compact, robust and reliable in operation. The absence of wearing mechanical part, such as gears, cams belts, bearings, eccentrics, etc., makes EMVF, most economical equipment. Standard power electronic output stages intended for control of the EMVF using SCR devices (thyristors and triacs). This implies phase angle control (PAC) and constant frequency of vibration. In this way control circuit must be synchronized to the mains supply frequency 50(60) Hz. PAC can only accomplish tuning amplitude of vibration, but not vibratory frequency. Application of transistor (IGBT or MOSFET) switch mode power converters enables accomplishing the amplitude and (or) frequency control of EMVF. Their use implies the excitation of an EMVF independent of the mains supply frequency. In addition, the frequency control ensures operation in the region of mechanical resonance. This operation is highly efficient, because large output displacement is provided by small input power. An optimal and efficient operation requires tracking of resonant frequency. This paper presents possible solution of the amplitude frequency control of EMVF and corresponding simulation and experimental results

Vibration control of resonant vibratory feeders with electromagnetic excitation

Vibracioni dodavači sa elektromagnetnom pobudom, odnosno elektromagnetni vibracioni dodavači (EMVD) su najčešće korišćeni u procesnoj industriji za obezbeđenje gravimetrijskog protoka sitnozrnih i rasutih materijala. Ovi pogoni obezbeđuju laku i jednostavnu kontrolu masenog protoka transportujućih materijala. U poređenju sa ostalim pogonima (pneumatskim, inercionim, centrifugalnim, itd.), oni su jednostavnije i kompaktnije konstrukcije, robusni i pouzdani u radu. Odsustvo habajući mehaničkih delova kao što su reduktori, kišnici, ekscentri i sl., čine EMVD veoma ekonomičnom opremom. Standardni pretvarački izlazni stepeni namenjeni za kontrolu EMVD su bazirani na SCR elementima (tiristorima i trijacima). Njihovo korišćenje podrazumeva korišćenje kontrole faznog ugla (KFU) i stoga konstantnu učestanost vibracija. Na ovaj način kontrolno kolo mora biti sinhronizovano sa mrežnom učestanošću 50(60)Hz. Uz pomoć KFU je jedino moguće ostvariti podešavanje amplitude vibracija, ali ne i njihove učestanosti. Primena prekidačkih tranzistorskih (IGBT ili MOSFET) energetskih pretvarača, omogućava amplitudsku i (ili) frekventnu kontrolu EMVD. Njihovo korišćenje podrazumeva pobudu EMVD nezavisno od mrežne učestanosti. Dodatno, frekventna kontrola dozvoljava rad u oblasti mehaničke rezonance. Rad u ovoj oblasti je veoma efikasan, pošto je moguće obezbediti značajne izlazne pomeraje, veoma malom ulaznom snagom. Optimalan i efikasan rad zahteva praćenje rezonantne učestanosti. U ovom radu su predstavljeni jedno moguće rešenje vibracione kontrole EMVD, kao i odgovarajući simulacioni i eksperimentalni rezultati.The vibratory feeders with electromagnetic excitation called electromagnetic vibratory feeders (EMVF) are commonly used for performing gravimetric flow of granular and particulate materials in processing industry. This drives offer easy and simple control the mass flow of conveying materials. In comparison with other drives (pneumatics, inertial, centrifugal, etc...), these have a more simple construction and they are compact, robust and reliable in operation. The absence of wearing mechanical part, such as gears, cams belts, bearings, eccentrics, etc., makes EMVF, most economical equipment. Standard power electronic output stages intended for control of the EMVF using SCR devices (thyristors and triacs). This implies phase angle control (PAC) and constant frequency of vibration. In this way control circuit must be synchronized to the mains supply frequency 50(60) Hz. PAC can only accomplish tuning amplitude of vibration, but not vibratory frequency. Application of transistor (IGBT or MOSFET) switch mode power converters enables accomplishing the amplitude and (or) frequency control of EMVF. Their use implies the excitation of an EMVF independent of the mains supply frequency. In addition, the frequency control ensures operation in the region of mechanical resonance. This operation is highly efficient, because large output displacement is provided by small input power. An optimal and efficient operation requires tracking of resonant frequency. This paper presents possible solution of the amplitude frequency control of EMVF and corresponding simulation and experimental results

Merenja na Beogradskom kanalizacionom sistemu

The installation of monitoring system at 8 sewer outlets of Belgrade Sewer System has started during 2007. In this paper the extension of that process is presented, where 5 new monitoring sites were equipped and new Supervisory and Control unit established with powerful SCADA and network-based software. All hardware and software were developed in Serbia, which leads to lower installation and maintenance costs and easier customization to locale needs. It is concluded at the end of the paper that Belgrade Sewer System has just started the process of systematic monitoring and that new monitoring sites are to be introduced, mostly at the larger storm water outlets and within the system itself. .Monitoring izliva Beogradskog Kanalizacionog Sistema (BKS) je započeo 2007. godine postavljanjem prvih 8 mernih mesta. U radu se daje prikaz nastavka procesa uspostavljanja monitoringa. Postavljeno je 5 novih mernih mesta i napravljen je Kontrolno Upravljački Centar opremljen savremenim SCADA sistemom sa odgovarajućom programskom podrškom. Sva razvijena oprema je domaće proizvodnje, čime se omogućava jeftinije održavanje i lakše prilagođavanje lokalnim uslovima. Na kraju rada se zaključuje da je BKS uspešno započeo svoje opremanje monitoring sistema, ali da treba da nastavi i sa monitoringom kišnih izliva kao i stanja unutar same mreže.

Merenja na Beogradskom kanalizacionom sistemu

The installation of monitoring system at 8 sewer outlets of Belgrade Sewer System has started during 2007. In this paper the extension of that process is presented, where 5 new monitoring sites were equipped and new Supervisory and Control unit established with powerful SCADA and network-based software. All hardware and software were developed in Serbia, which leads to lower installation and maintenance costs and easier customization to locale needs. It is concluded at the end of the paper that Belgrade Sewer System has just started the process of systematic monitoring and that new monitoring sites are to be introduced, mostly at the larger storm water outlets and within the system itself. .Monitoring izliva Beogradskog Kanalizacionog Sistema (BKS) je započeo 2007. godine postavljanjem prvih 8 mernih mesta. U radu se daje prikaz nastavka procesa uspostavljanja monitoringa. Postavljeno je 5 novih mernih mesta i napravljen je Kontrolno Upravljački Centar opremljen savremenim SCADA sistemom sa odgovarajućom programskom podrškom. Sva razvijena oprema je domaće proizvodnje, čime se omogućava jeftinije održavanje i lakše prilagođavanje lokalnim uslovima. Na kraju rada se zaključuje da je BKS uspešno započeo svoje opremanje monitoring sistema, ali da treba da nastavi i sa monitoringom kišnih izliva kao i stanja unutar same mreže.

Hardware and Software Implementations of Measuring System for Resonant Electromagnetic Vibratory Conveyor

Vibratory movements are one of the most ways for conveying and transportation of granular and particulate materials.Vibratory conveyors and feeders with electromagnetic excitation belong to a group of mechatronic devices that in an efficient wayprovides drive force and oscillations for this conveying. They have an important role in framework of the many industrial process inwhich are dominant the particulate materials: food processing, cement production, certain product line in steel industry,pharmaceutical industry, agriculture, etc. Therefore, they are representing a very important element of above mentioned technologicprocesses and production line. Especially, the vibratory conveyors and feeders that operate in the resonant mode are used in industrialapplications because of their energy efficiency increasing. The relatively small input energy of actuator drive causes intensivelyvibrations of load carry element (LCE) of vibratory conveyor. The intensity of the vibrations directly affects on gravimetric flow (massflow) and therefore on the productivity of vibratory conveyors. To ensure a reliable and energy-efficient operation of vibratoryconveyors, it is necessary to have a reliable and accurate measurement and testing of electrical and mechanical quantities. A hardwareand software implementation of the testing and measurement system of resonant vibratory conveyor with electromagnetic drive, andtheir corresponding data acquisition platform are presented in this paper. The experimental results obtained on a real laboratory setupof resonant vibratory conveyor are also shown

Possibilities of Applying Robotic Systems and Smart Sensor Networks in Integrated Agricultural Apple Production

This paper presents an intelligent approach to integrated data collection and management system for irrigation and fertilisation of plants in agricultural production (specifically in apple plantations) applied to control and optimization of all parameters necessary for an adequate level of agricultural production. The approach tends to reduce investment costs, minimize power consumption and implement environmentally clean power production methods, as well as to apply proper treatment of chemical preparations in order to achieve economically viable integrated food production. Application of modern systems of complex sensor networks connected via mobile solar power generators as main node connection allows the collection of all data and parameters necessary for the continuity of integrated agricultural production. The mobile robotized solar power generator is also the executive device that manages complex hydraulic system for irrigation and fertilisation, treating the field with chemicals depending on available land, meteorological and environmental conditions

Epidemiology and risk factors of trichinellosis in Bosnia and Herzegovina from 1961 to 2021

This study is a retrospective analysis of social, economic, political, and cultural events on the annual incidence of trichinellosis in Bosnia and Herzegovina (BiH). It highlights the importance of specific regulations, which have been incorporated into developing preventive protection against this human disease for the last 61 years since it has been monitored by law. In the period, 1961–2021, 3828 people became infected. The first outbreak of trichinellosis was documented in 1965, and the incidence peaked during the war and post-war period at the end of the twentieth century. At that time, outbreaks with hundreds of cases and five deaths were recorded. In the first decade of the twenty-first century, the incidence decreased, and at the end of the second decade, two consecutive years without trichinellosis cases were finally registered. The analysis shows that a significantly higher incidence rate was recorded between the two political entities of BiH, the Republic of Srpska (4.97% 000) versus the Federation of BiH (0.9% 000) and that the occurrence of trichinellosis in humans in BiH is related to the presence of Trichinella spp. in animals, of a degree of biosecurity on pig farms, population’s awareness of safe food, the impact of tradition and religion on eating habits, doctors’ awareness of the symptomatology, and the Trichinella spp. larva detection method in muscle samples. The spread risk of trichinellosis requires meat inspection for Trichinella spp. larvae to be mandatory in Bi