Umashankar Subramaniam (SMIEEE) is working as Associate Professor in Renewable energy and Modern Control Research Group, College of Engineering, Prince Sultan University, Saudi Arabia. He is reviewer in reputed journals like Elsevier, IEEE and IET. He has published/presented 148 papers, 10 books/chapters and 10 technical articles. His areas of research interests include power electronics applications renewable energy and energy storage, VFD, smart grid and power quality.
This paper presents field-oriented control (FOC) strategy to improve the performance of a synchro... more This paper presents field-oriented control (FOC) strategy to improve the performance of a synchronous reluctance motor (SynRM) drive system. In this article, the synchronous reluctance motor is used to drive the centrifugal pump that requires high power density . A mathematical model of SynRM is formed using dynamic equations of the motor. This motor model is then simulated using MATLAB Simulink. The suggested control strategy is reviewed, and its control performances (flux and current along direct and quadrature axes) are analyzed. Simulation results are presented to show the efficacy of the approach.
One of the most critical elements in the connection of photovoltaic (PV)-based systems used to ge... more One of the most critical elements in the connection of photovoltaic (PV)-based systems used to generate electricity from solar energy is the inverter. The harmonic effects of the inverters to be connected to the grid should be as low as possible, and the total harmonic distortion (THD) should be less than 10%. A high THD value will distort the power quality on the grid side. For this reason, the THD value of the inverters in the grid connection approaches must be determined by spectral analysis to ensure that the necessary protection and improvements are made technically. In this study, a novel inverter topology, including six power switches and two power diodes, is presented, and the voltage data obtained from a grid-connected inverter are acquired in real time, and spectrum analysis is performed with the software developed with LabVIEW. The power efficiency of the proposed inverter is compared with conventional inverter types such as HERIC, H5, and H6 inverters. One of the novelty aspects of the proposed inverter topology is forming a proper freewheeling path including switches and diodes in the inverter branches that can provide a separate DC and ac components, and as a result, this prevents the following the PV side leakage currents to the ac grid side. In the spectrum analysis, the chirp Z-transformation (CZT) was used along the contours of the Z-transformation outside the unit circle. Using CZT, the z-transform was calculated for the inverter output voltage along the spiral lines in the z-plane. Besides, spectrum analysis was performed with fast Fourier transform (FFT) and compared with CZT. The results show that the CZT transformation is more efficient than the FFT algorithm and is useful in calculating a subset of FFT for a sequence. The performance of the proposed inverter is compared with conventional topologies. Hardware implementation and the output signals and the leakage current waveforms are also presented.
The use of a Doubly Fed Asynchronous Machine (DFAM) provides attractive characteristics and offer... more The use of a Doubly Fed Asynchronous Machine (DFAM) provides attractive characteristics and offers operational flexibility in many variable speed generation applications, such as in a hydroelectric pumped storage plant. In a variable speed hydroelectric pumped storage plant, the start-up process of DFAM is identical to the conventional singly fed asynchronous machine, wherein a significant amount of energy is wasted. This paper introduces an energy-efficient start-up strategy in DFAM based hydroelectric pump-turbine. The back-to-back voltage source converter connected to the rotor side is amenable for speed control (real power), braking (regenerative/dynamic), and starting the unit. Further, in this starting technique, the stator circuit of the machine is injected with a low voltage DC supply at starting instead of short-circuiting the windings. This DC injection reduces the slip losses and cuts down the magnetizing current requirement. The magnitude of the required DC supply is est...
The recent growth of battery-powered applications has increased the need for high-efficiency step... more The recent growth of battery-powered applications has increased the need for high-efficiency step-up dc-dc converters. The step-up conversion is commonly used in several applications, such as electric vehicle (EV); plug-in hybrid electric vehicles (PHEV); photovoltaic (PV) systems; uninterruptible power supplies (UPS); and fuel cell systems. The input current is shared among inductors by paralleling the converters; resulting in high reliability and efficiency. In this paper; a detailed analysis for reducing power loss and improving efficiency is discussed. In continuous conduction mode; the converters are tested with a constant duty cycle of 50%. The multi phase interleaved boost converter (MPIBC) is controlled by interleaved switching techniques; which have the same switching frequency but phases are shifted. The efficiency of the six phase IBC model is 93.82% and 95.74% for an input voltage of 20 V and 200 V, respectively. The presented six phase MPIBC is validated by comparing it...
Advances in Power Systems and Energy Management, 2017
There are number of studies based on power quality events, but very few literatures are focused o... more There are number of studies based on power quality events, but very few literatures are focused only on the discrete disturbances which also known as events of power quality disturbances. To answer several questions about the discrete disturbances, the power quality survey was conducted at VIT University, India. This survey intended to lay out information related to power quality disturbances mainly focused on swells, dips, transients, rapid voltage changes, voltage interruptions, and other parameters. The result from the survey will give a better knowledge and understanding about the above parameters.
Computational and Mathematical Methods in Medicine, 2022
SARS-CoV-2 is a novel virus, responsible for causing the COVID-19 pandemic that has emerged as a ... more SARS-CoV-2 is a novel virus, responsible for causing the COVID-19 pandemic that has emerged as a pandemic in recent years. Humans are becoming infected with the virus. In 2019, the city of Wuhan reported the first-ever incidence of COVID-19. COVID-19 infected people have symptoms that are related to pneumonia, and the virus affects the body’s respiratory organs, making breathing difficult. A real-time reverse transcriptase-polymerase chain reaction (RT-PCR) kit is used to diagnose the disease. Due to a shortage of kits, suspected patients cannot be treated promptly, resulting in disease spread. To develop an alternative, radiologists looked at the changes in radiological imaging, like CT scans, that produce comprehensive pictures of the body of excellent quality. The suspected patient’s computed tomography (CT) scan is used to distinguish between a healthy individual and a COVID-19 patient using deep learning algorithms. A lot of deep learning methods have been proposed for COVID-19...
2019 IEEE 13th International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG), 2019
Among the total energy consumed by presently installed utilities, pumping systems contributes nea... more Among the total energy consumed by presently installed utilities, pumping systems contributes nearly 30% of them that are controlled through induction motor. The flow rate of centrifugal pump is directly proportional to the speed of induction motor. Induction motor based electric drives are a complex nonlinear system to control due to their varying nature of speed with respect to changes in load. Thus, controllers are required for the speed control and performance enhancement of the induction motors. In this paper, a comparison of various controllers is discussed for the flow rate control of the pumping system. Among all the conventional controllers the proportional integral derivative (PID) is the mostly preferred for induction motor speed control. However, high overshoot, fixed gain constants and sluggish response are the disadvantages of the PID controller. So, automatic gain tuned PI controllers (i.e., adaptive PI controllers) are introduced to overcome the drawbacks of the conventional PID controllers. Further advancements in the field of artificial intelligence lead to the development of fuzzy logic based controllers. These controllers are simple, compatible and can be modelled without detailed mathematical model of the system. Thus, they are gaining more popularity than other controllers. The rules and membership functions (MFs) are responsible for performance of fuzzy logic controllers are designed using trial and error method. The result comparison of all the controllers is presented and the performance of each controller is analyzed. From the observations, fuzzy logic controller provides better performance than the conventional controllers.
2021 7th International Conference on Electrical Energy Systems (ICEES), 2021
As the growth of battery powered electric vehicles is increasing, a high boost in the DC voltage ... more As the growth of battery powered electric vehicles is increasing, a high boost in the DC voltage is essential before interfacing the high gain converter to the grid through an inverter. Apart from this, the role choppers in PV systems and energy storage purposes also serves good. The input current among inductors can be shared by paralleling the converters, making the power electronic systems to be highly reliable and efficient. This paper discusses the circuit model and performance of a bidirectional chopper with coupled inductor for electric vehicle applications. The coupled inductor operates as the filter inductor for non-isolated part of the converter and as a transformer for the isolated converter topology. The reduction of switching voltage stress across the power semiconductor devices is achieved by series connection of two switch bridges. This converter is further tested with a nine level inverter. The bidirectional converter designed for electric vehicles is further interfaced with a multilevel inverter (nine level). The implementation of the converter design is simulated using MATLAB/SIMULINK
2019 International Conference on Electrical Drives & Power Electronics (EDPE), 2019
Pumps playa pivotal role in both energy and water conservation. They account for the 20% of the w... more Pumps playa pivotal role in both energy and water conservation. They account for the 20% of the world's total energy consumption and thus monitoring it becomes more relevant to decrease an energy wastage. The performance of the pump deteriorates for various reasons, such as cavitation, sedimentation of silt and water hammering, electrical and mechanical faults. Performance of the pump under silt-laden and identification of silt is seldom studied. It causes severe damage in the pumping system. Identification of sludge particles can productively result in energy savings, water conservation, and energy efficiency. With the advent of machine learning and artificial intelligence, pumps can incorporate these methods to become self-reliant in the identification of type and concentration of silt while pumping the fluid. Machine learning is a modern advanced technology, which leads to predict the anomalies of the machine in ground level. This paper presents the how to identify and predict sludge problem in water pumping system using machine learning algorithm.
In this study, a modified non-uniform adiabatic section in a Two-Phase Closed Thermosiphon (TPCT)... more In this study, a modified non-uniform adiabatic section in a Two-Phase Closed Thermosiphon (TPCT) is proposed where the uniform section was replaced by convergent and divergent (C-D) sections. The heat transfer analysis was performed on the modified TPCT and their findings were compared with standard TPCT. The deionized water (DI) in the proportion of 30 vol% is filled in both the TPCTs. Further, the heat transfer performance analysis was carried out for three different orientations, such as 0°, 45° and 90°, and heat input was varied from 50 to 250 W. The effect of these geometrical changes and inclination angles on the heat transfer performance of both the TPCT were evaluated to compare the thermal resistance, wall temperature variation and heat transfer coefficient. The non-dimensional numbers such as Weber (WE), Bond (BO), Condensation (CO) and Kutateladze (KU) were investigated based on heat fluxes for both TPCTs. By introducing the convergent-divergent section nearer to the con...
2020 IEEE International Conference on Environment and Electrical Engineering and 2020 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe), 2020
Machine learning is a fast-computational method and data analytics technique by which information... more Machine learning is a fast-computational method and data analytics technique by which information be learned directly from the data without any predetermined equation as a model. The algorithms improve their performance as the number of samples available for learning increases. Todays' challenge is energy-efficient technology and conservation of energy. Machine learning technology is the part of artificial intelligence, which helps to keep the devices more energy-efficient and can be applied in various fields like agriculture, industry, medical sector etc. Since pumping system plays a significant role in the agricultural sector and most of the industrial fields, continuous monitoring is necessary to keep the system safe and reliable. The problems like sludge, cavitation, water hammering, rotor bearing fault, and impeller breaking are the significant causes of the damage of the pump. To detecting these problems, machine learning technique can be applied. There are various algorithms of machine learning like Support Vector Machine, Neural Network, Empirical Mode of Decomposition method, K-Nearest Neighbor method etc. This paper concentrates on detecting cavitation fault in pumping system by machine learning algorithm mainly by SVM algorithm and K-Nearest Neighbor Method and on a comparative study of SVM and K Nearest Neighbor algorithm.
This paper presents field-oriented control (FOC) strategy to improve the performance of a synchro... more This paper presents field-oriented control (FOC) strategy to improve the performance of a synchronous reluctance motor (SynRM) drive system. In this article, the synchronous reluctance motor is used to drive the centrifugal pump that requires high power density . A mathematical model of SynRM is formed using dynamic equations of the motor. This motor model is then simulated using MATLAB Simulink. The suggested control strategy is reviewed, and its control performances (flux and current along direct and quadrature axes) are analyzed. Simulation results are presented to show the efficacy of the approach.
One of the most critical elements in the connection of photovoltaic (PV)-based systems used to ge... more One of the most critical elements in the connection of photovoltaic (PV)-based systems used to generate electricity from solar energy is the inverter. The harmonic effects of the inverters to be connected to the grid should be as low as possible, and the total harmonic distortion (THD) should be less than 10%. A high THD value will distort the power quality on the grid side. For this reason, the THD value of the inverters in the grid connection approaches must be determined by spectral analysis to ensure that the necessary protection and improvements are made technically. In this study, a novel inverter topology, including six power switches and two power diodes, is presented, and the voltage data obtained from a grid-connected inverter are acquired in real time, and spectrum analysis is performed with the software developed with LabVIEW. The power efficiency of the proposed inverter is compared with conventional inverter types such as HERIC, H5, and H6 inverters. One of the novelty aspects of the proposed inverter topology is forming a proper freewheeling path including switches and diodes in the inverter branches that can provide a separate DC and ac components, and as a result, this prevents the following the PV side leakage currents to the ac grid side. In the spectrum analysis, the chirp Z-transformation (CZT) was used along the contours of the Z-transformation outside the unit circle. Using CZT, the z-transform was calculated for the inverter output voltage along the spiral lines in the z-plane. Besides, spectrum analysis was performed with fast Fourier transform (FFT) and compared with CZT. The results show that the CZT transformation is more efficient than the FFT algorithm and is useful in calculating a subset of FFT for a sequence. The performance of the proposed inverter is compared with conventional topologies. Hardware implementation and the output signals and the leakage current waveforms are also presented.
The use of a Doubly Fed Asynchronous Machine (DFAM) provides attractive characteristics and offer... more The use of a Doubly Fed Asynchronous Machine (DFAM) provides attractive characteristics and offers operational flexibility in many variable speed generation applications, such as in a hydroelectric pumped storage plant. In a variable speed hydroelectric pumped storage plant, the start-up process of DFAM is identical to the conventional singly fed asynchronous machine, wherein a significant amount of energy is wasted. This paper introduces an energy-efficient start-up strategy in DFAM based hydroelectric pump-turbine. The back-to-back voltage source converter connected to the rotor side is amenable for speed control (real power), braking (regenerative/dynamic), and starting the unit. Further, in this starting technique, the stator circuit of the machine is injected with a low voltage DC supply at starting instead of short-circuiting the windings. This DC injection reduces the slip losses and cuts down the magnetizing current requirement. The magnitude of the required DC supply is est...
The recent growth of battery-powered applications has increased the need for high-efficiency step... more The recent growth of battery-powered applications has increased the need for high-efficiency step-up dc-dc converters. The step-up conversion is commonly used in several applications, such as electric vehicle (EV); plug-in hybrid electric vehicles (PHEV); photovoltaic (PV) systems; uninterruptible power supplies (UPS); and fuel cell systems. The input current is shared among inductors by paralleling the converters; resulting in high reliability and efficiency. In this paper; a detailed analysis for reducing power loss and improving efficiency is discussed. In continuous conduction mode; the converters are tested with a constant duty cycle of 50%. The multi phase interleaved boost converter (MPIBC) is controlled by interleaved switching techniques; which have the same switching frequency but phases are shifted. The efficiency of the six phase IBC model is 93.82% and 95.74% for an input voltage of 20 V and 200 V, respectively. The presented six phase MPIBC is validated by comparing it...
Advances in Power Systems and Energy Management, 2017
There are number of studies based on power quality events, but very few literatures are focused o... more There are number of studies based on power quality events, but very few literatures are focused only on the discrete disturbances which also known as events of power quality disturbances. To answer several questions about the discrete disturbances, the power quality survey was conducted at VIT University, India. This survey intended to lay out information related to power quality disturbances mainly focused on swells, dips, transients, rapid voltage changes, voltage interruptions, and other parameters. The result from the survey will give a better knowledge and understanding about the above parameters.
Computational and Mathematical Methods in Medicine, 2022
SARS-CoV-2 is a novel virus, responsible for causing the COVID-19 pandemic that has emerged as a ... more SARS-CoV-2 is a novel virus, responsible for causing the COVID-19 pandemic that has emerged as a pandemic in recent years. Humans are becoming infected with the virus. In 2019, the city of Wuhan reported the first-ever incidence of COVID-19. COVID-19 infected people have symptoms that are related to pneumonia, and the virus affects the body’s respiratory organs, making breathing difficult. A real-time reverse transcriptase-polymerase chain reaction (RT-PCR) kit is used to diagnose the disease. Due to a shortage of kits, suspected patients cannot be treated promptly, resulting in disease spread. To develop an alternative, radiologists looked at the changes in radiological imaging, like CT scans, that produce comprehensive pictures of the body of excellent quality. The suspected patient’s computed tomography (CT) scan is used to distinguish between a healthy individual and a COVID-19 patient using deep learning algorithms. A lot of deep learning methods have been proposed for COVID-19...
2019 IEEE 13th International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG), 2019
Among the total energy consumed by presently installed utilities, pumping systems contributes nea... more Among the total energy consumed by presently installed utilities, pumping systems contributes nearly 30% of them that are controlled through induction motor. The flow rate of centrifugal pump is directly proportional to the speed of induction motor. Induction motor based electric drives are a complex nonlinear system to control due to their varying nature of speed with respect to changes in load. Thus, controllers are required for the speed control and performance enhancement of the induction motors. In this paper, a comparison of various controllers is discussed for the flow rate control of the pumping system. Among all the conventional controllers the proportional integral derivative (PID) is the mostly preferred for induction motor speed control. However, high overshoot, fixed gain constants and sluggish response are the disadvantages of the PID controller. So, automatic gain tuned PI controllers (i.e., adaptive PI controllers) are introduced to overcome the drawbacks of the conventional PID controllers. Further advancements in the field of artificial intelligence lead to the development of fuzzy logic based controllers. These controllers are simple, compatible and can be modelled without detailed mathematical model of the system. Thus, they are gaining more popularity than other controllers. The rules and membership functions (MFs) are responsible for performance of fuzzy logic controllers are designed using trial and error method. The result comparison of all the controllers is presented and the performance of each controller is analyzed. From the observations, fuzzy logic controller provides better performance than the conventional controllers.
2021 7th International Conference on Electrical Energy Systems (ICEES), 2021
As the growth of battery powered electric vehicles is increasing, a high boost in the DC voltage ... more As the growth of battery powered electric vehicles is increasing, a high boost in the DC voltage is essential before interfacing the high gain converter to the grid through an inverter. Apart from this, the role choppers in PV systems and energy storage purposes also serves good. The input current among inductors can be shared by paralleling the converters, making the power electronic systems to be highly reliable and efficient. This paper discusses the circuit model and performance of a bidirectional chopper with coupled inductor for electric vehicle applications. The coupled inductor operates as the filter inductor for non-isolated part of the converter and as a transformer for the isolated converter topology. The reduction of switching voltage stress across the power semiconductor devices is achieved by series connection of two switch bridges. This converter is further tested with a nine level inverter. The bidirectional converter designed for electric vehicles is further interfaced with a multilevel inverter (nine level). The implementation of the converter design is simulated using MATLAB/SIMULINK
2019 International Conference on Electrical Drives & Power Electronics (EDPE), 2019
Pumps playa pivotal role in both energy and water conservation. They account for the 20% of the w... more Pumps playa pivotal role in both energy and water conservation. They account for the 20% of the world's total energy consumption and thus monitoring it becomes more relevant to decrease an energy wastage. The performance of the pump deteriorates for various reasons, such as cavitation, sedimentation of silt and water hammering, electrical and mechanical faults. Performance of the pump under silt-laden and identification of silt is seldom studied. It causes severe damage in the pumping system. Identification of sludge particles can productively result in energy savings, water conservation, and energy efficiency. With the advent of machine learning and artificial intelligence, pumps can incorporate these methods to become self-reliant in the identification of type and concentration of silt while pumping the fluid. Machine learning is a modern advanced technology, which leads to predict the anomalies of the machine in ground level. This paper presents the how to identify and predict sludge problem in water pumping system using machine learning algorithm.
In this study, a modified non-uniform adiabatic section in a Two-Phase Closed Thermosiphon (TPCT)... more In this study, a modified non-uniform adiabatic section in a Two-Phase Closed Thermosiphon (TPCT) is proposed where the uniform section was replaced by convergent and divergent (C-D) sections. The heat transfer analysis was performed on the modified TPCT and their findings were compared with standard TPCT. The deionized water (DI) in the proportion of 30 vol% is filled in both the TPCTs. Further, the heat transfer performance analysis was carried out for three different orientations, such as 0°, 45° and 90°, and heat input was varied from 50 to 250 W. The effect of these geometrical changes and inclination angles on the heat transfer performance of both the TPCT were evaluated to compare the thermal resistance, wall temperature variation and heat transfer coefficient. The non-dimensional numbers such as Weber (WE), Bond (BO), Condensation (CO) and Kutateladze (KU) were investigated based on heat fluxes for both TPCTs. By introducing the convergent-divergent section nearer to the con...
2020 IEEE International Conference on Environment and Electrical Engineering and 2020 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe), 2020
Machine learning is a fast-computational method and data analytics technique by which information... more Machine learning is a fast-computational method and data analytics technique by which information be learned directly from the data without any predetermined equation as a model. The algorithms improve their performance as the number of samples available for learning increases. Todays' challenge is energy-efficient technology and conservation of energy. Machine learning technology is the part of artificial intelligence, which helps to keep the devices more energy-efficient and can be applied in various fields like agriculture, industry, medical sector etc. Since pumping system plays a significant role in the agricultural sector and most of the industrial fields, continuous monitoring is necessary to keep the system safe and reliable. The problems like sludge, cavitation, water hammering, rotor bearing fault, and impeller breaking are the significant causes of the damage of the pump. To detecting these problems, machine learning technique can be applied. There are various algorithms of machine learning like Support Vector Machine, Neural Network, Empirical Mode of Decomposition method, K-Nearest Neighbor method etc. This paper concentrates on detecting cavitation fault in pumping system by machine learning algorithm mainly by SVM algorithm and K-Nearest Neighbor Method and on a comparative study of SVM and K Nearest Neighbor algorithm.
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