Lazhar Ben-Brahim | Qatar University (original) (raw)

Papers by Lazhar Ben-Brahim

2022 3rd International Conference on Smart Grid and Renewable Energy (SGRE)

2022 3rd International Conference on Smart Grid and Renewable Energy (SGRE)

IEEE Access, 2022

This paper proposes an enhanced Deadbeat Controller (DBC) for a grid-tied Flying Capacitors Inver... more This paper proposes an enhanced Deadbeat Controller (DBC) for a grid-tied Flying Capacitors Inverter (FCI). The proposed DBC guarantees the balancing of the capacitors' voltages while injecting current to the grid with lower Total Harmonics Distortion (THD). The proposed controller has the following advantages: 1) Improved current tracking quality even at zero crossing instants by using a weighted statespace model, 2) Superior steady-state performance (lower current THD) compared to other prediction-based control techniques such as Finite-Control-Set Model Predictive Control, 3) The generated duty cycles are normalized to the common base when the desired state is out of reach within the sampling time, 4) Voltage Ride-Through (VRT) capability, and 5) Robustness to parameters variation. Theoretical analysis, simulation, and experimental results are presented to show the effectiveness of the proposed control technique in ensuring uninterruptible and smooth transfer of energy to the grid during normal/abnormal operating conditions (severe voltage sags, parameters variation, etc.).

2017 9th IEEE-GCC Conference and Exhibition (GCCCE), 2017

The potential of Photovoltaic (PV) panels as a main tool of harnessing solar energy is increasing... more The potential of Photovoltaic (PV) panels as a main tool of harnessing solar energy is increasing with the advancements in their power conditioning and conversion stages that vary based on applications. This paper focuses on the conversion of a 22kW PV array output from low-voltage to medium-voltage level (400V to 7kV). This high voltage conversion ratio is difficult to achieve using conventional single-stage DC-DC converters. Thus, different alternatives are proposed and compared here, namely, the Parallel-Input Series-Output (PISO) connection of two different stages using both isolated (full-bridge) and non-isolated DC-DC converters. The converters are compared on the basis of efficiency, footprint, components rating and reliability. Thus, the isolated DC-DC converter system efficiency was estimated at 797%, compared to 93 % for the non-isolated system, keeping into account the variations in terms of the filtering capacitor requirements to maintain a constant minimal voltage ripple at the output which is in favor of the non-isolated systems.

IEEE Transactions on Industry Applications, 2019

Requirement of large number of levels with lower number of switching devices has made asymmetrica... more Requirement of large number of levels with lower number of switching devices has made asymmetrical converters more popular than the symmetrical ones. Asymmetrical cascaded multilevel inverters (ACMLI) can achieve high efficiency by combining switching devices with different voltage ratings and technologies. The proposed ACMLI cascades two or more units of packed U-Cell (PUC) inverters using two or more isolated dc link supplies. In this article, one of the PUC unit is controlled using high switching frequency while the other PUCs are operated in a step mode at low switching frequencies, thus operating them in a variable frequency control mode. The cascading of two 7-level PUC inverters with dc link voltage ratio of 1:7 can produce an output voltage with 49 (7x7) levels. The multilevel output voltage waveform is nearly sinusoidal with very low THD content, and the low switching frequency operation leads to lower power dissipation and greater system efficiency. However, each PUC module requires two dc voltage sources. To address this concern, in this article, each PUC module consists of one dc voltage source and one dc bus capacitor. With the cascaded PUC topology and proposed control algorithm, load current and dc bus capacitor voltage control is achieved simultaneously. The proposed converter and its control technique lead to the breaking of the design tradeoff rule between switching frequency (efficiency) and filter size. This is very useful in various applications such as uninterruptible power supplies and grid-tie inverters. The converter and its control technique are simulated using MATLAB/Simulink software and simulation results for both open loop and closed loop are discussed. Hardware results are obtained by developing a 1-kW experimental prototype. Simulation and experimental results confirm the usefulness and effectiveness of the proposed topology and its control technique.

IET Power Electronics, 2017

Multiphase power converters generate common mode voltage due to switching actions of the power sw... more Multiphase power converters generate common mode voltage due to switching actions of the power switches. The resulting common mode current in multiphase motor drives flow through the bearing and shaft. Continuous flow of common mode current gradually weakens the performance of the drives. A space vector pulse width modulation (SVPWM) technique is developed to reduce Common mode voltage (CMV) in a three-to-five-phase matrix converter-based five-phase induction motor drive system. The principle of CMV reduction lies in the selection of proper space vectors for implementation of SVPWM. The proposed technique achieves reduction in the CMV without affecting other performances, i.e. loss in output voltage, total harmonic distortion in the output voltages and currents. The common mode voltage is reduced by selecting a set of proper zero space vectors and placing them in a suitable position within a switching cycle. Using this approach, CMV is reduced by ∼30%. Simulation and experimental results are provided for a five-phase induction motor drive fed using a three-to-five-phase matrix converter.

Electronics

An ultra-high step-up, non-isolated DC–DC converter with a continuous input current was developed... more An ultra-high step-up, non-isolated DC–DC converter with a continuous input current was developed as a result of this research. This converter’s architecture consists of a voltage multiplier cell (VMC), a positive output super lift Luo converter (POSLLC), and a quadratic boost converter (QBS) (also referred to as a cascaded boost topology (CBT)). Thus, the bold points of the topologies mentioned earlier enhance the voltage gain of the proposed topology. It is important to note that when the duty cycle is at 50%, the converter attains a voltage gain of ten. Additionally, the constant input current of the topology reduces the current stress on the input filter capacitor. This converter’s topology was investigated and studied under various operating conditions: ideal and non-ideal modes, as well as continuous and discontinuous current modes (CCM/DCM). The converter’s efficiency and voltage gain were also compared to those of newly proposed converters. PLECS and MATLAB software tools we...

2018 IEEE 12th International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG 2018), 2018

The shoot-through problem of conventional H-Bridge inverters imposes a threat to system's rel... more The shoot-through problem of conventional H-Bridge inverters imposes a threat to system's reliability and efficiency. This is because the unintentional shoot-through state short-circuits the DC-Link capacitor. To overcome the severity of the shoot-through state, Dual Buck Inverters (DBIs) were introduced. These topologies have at least one inductor connected in-parallel with the DC-Link capacitor at accidental shoot-through states' activation; thus, preventing the DC-side from getting short-circuited. Besides, DBIs' circulate inherently low ground leakage current and thereby they are considered as attractive choices in single-phase non-isolated grid-connected Photovoltaic (PV) applications. Therefore, this work proposes a modified non-isolated grid-tied LCL-filter based DBI with a control scheme that improves the reliability and the stability. Specifically, adopting an appropriate Active Power Decoupling Control (APDC) scheme enhances the reliability. This scheme utilizes the Common-Mode (CM) operation of the DBI. As for stability assurance, an Active Resonance Damping Control (ARDC) is developed. This ARDC is deployed in both inverter modes, the CM and the Differential-Mode (DM). Eventually, the theoretical analyses are confirmed on a 3 kW / 30 μΚ electrolytic capacitor-less system. The results showed that the single-phase low frequency ripples of the DC-bus voltage were negligible. Meaning that, the input capacitance requirement of the system is reduced about 40–50 times compared to the conventional methodology. Consequently, utilizing reliable polypropylene film capacitors for effective DC-Linking.

International Journal of Electrical Power & Energy Systems

Abstract Compared to conventional multilevel topologies, the Packed U-Cell multilevel topology ut... more Abstract Compared to conventional multilevel topologies, the Packed U-Cell multilevel topology utilizes the minimum number of components and provides both maximum voltage levels and high reliability. When used in a battery energy storage system, its dc-link consists of a top branch battery storage and bottom branch flying capacitors, whose state of charge and voltages must be balanced.This paper proposes a novel control scheme with two cascaded controllers: the inner loop regulates the output filter current and dc-link voltages using a novel finite-set model predictive control, the outer one is fully integrated with the model predictive controller and regulates the battery state of charge by injecting a zero-sequence voltage. The proposed control scheme was successfully implemented and tested through simulation and real-time testing. The obtained results highlight good dynamic performance and robustness of the proposed scheme during active power injection/absorption and low voltage ride-through capability.

2019 IEEE 28th International Symposium on Industrial Electronics (ISIE), 2019

A novel configurations of a non-isolated Modified SEPIC Converter with two Voltage Lift Switched ... more A novel configurations of a non-isolated Modified SEPIC Converter with two Voltage Lift Switched Inductor (MSCVLSI) modules namely MSCVLSI-XYL, MSCVLSI-LYZ and MSCVLSI-XLZ are presented in the paper. The key features of these configurations are, 1) high voltage conversion ratio, 2) single controlled switch, 3) high-value input inductor to smooth the input current, 4) maximum utilization of input source, 5) continuous input current. With these notable features, proposed configurations are more convenient for high voltage renewable energy applications to boost the low voltage of photovoltaic array/fuel cell. The feasibility of these converter configurations are verified by mathematical analysis and simulation results. MSCVLSI configurations are simulated for 250 W resistive load and at 50 kHz switching frequency.

2018 IEEE 12th International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG 2018), 2018

The Quasi-Z-Source (QZS) inverters are the promising topology for the renewable integration with ... more The Quasi-Z-Source (QZS) inverters are the promising topology for the renewable integration with the grid. QZSI achieves the MPPT during the shoot through state, without additional DC-DC converter, and simultaneously delivering the AC power to the grid or motor load. The quasi components (L and C) sizes are reduced by increasing the switching frequency of the converters. But the switching losses of the converter will dominate at the higher frequencies. To minimize the switching losses of the converter, this paper proposes reduced switching loss single stage inverter for high power applications. Using only six devices rated at supply voltage, the QZS resonant converter can operate properly by adding resonant inductor and capacitor to the ac side of each phase. The proposed converter can control the output with true pulse width modulation (PWM) at high frequency and the Zero Voltage Switching (ZVS) and Zero Current Switching is achieved at every switching cycle. The detailed analysis, modulation and simulation are presented to verify the operating principle of the QZS resonant converter.

2017 IEEE Energy Conversion Congress and Exposition (ECCE), 2017

In this paper, Solar powered Single-Phase Capacitor Start Induction motor for water pump applicat... more In this paper, Solar powered Single-Phase Capacitor Start Induction motor for water pump application is discussed. Output of solar panel is connected to quasi Z Source Inverter (qZSI). Three modules of qZSI are connected in cascade to give seven level output voltage. Single phase motor is powered with cascaded qZSI to obtain the improved performance due to multilevel inverter. As the power generated from PV system is highly variable due to its dependency on various parameters, qZSI with variable boosting is controlled for achieving the desired rms voltage. Voltage boosting feature of qZSI allows for reliable operation of Single Phase Induction motor. Closed loop control of virtual dc bus voltage is achieved. Simulation results showing the performance of single phase motor powered with cascaded qZSI for various load torque are shown and discussed. Model of Solar panel is used as input supply for qZSI. Experimental results for closed loop voltage control of multilevel qZSI for RL load are discussed. Future work includes the development of hardware setup for observation of Single phase capacitor start Induction motor when it powered with Cascaded multilevel qZSI.

2018 IEEE 12th International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG 2018), 2018

Modular multilevel converter is becoming a great candidate for high power applications due to its... more Modular multilevel converter is becoming a great candidate for high power applications due to its valuable features. However, its higher performance comes at the expenses of higher complexity, which increases the risks of failures. Power switches can be accounted among the most vulnerable components in this converter and their failure can lead to the regular functioning destabilization and eventual shutdowns. Failures in power switches can be induced by either open or short circuits faults. This paper presents the principle component analysis, which is a data-driven approach, to tackle the open circuit faults detection in modular multilevel converters. The results were compared to the performance of a model-based technique, the sliding mode observer, and showed a better performance of the adopted approach.

ArXiv, 2017

We consider multiple source nodes (consumers) communicating wirelessly their energy demands to th... more We consider multiple source nodes (consumers) communicating wirelessly their energy demands to the meter data-management system (MDMS) over the subarea gateway(s). We quantify the impacts of passive and active security attacks on the wireless communications system's reliability and security as well as the energy-demand estimation-error cost in dollars paid by the utility. We adopt a multiple-input multiple-output multi-antenna-eavesdropper (MIMOME) wiretap channel model. To secure the MIMO wireless communication system, the legitimate nodes generate artificial noise (AN) vectors to mitigate the effect of the passive eavesdropping attacks. In addition, we propose a redundant design where multiple gateways are assumed to coexist in each subarea to forward the consumers' energy-demand messages. We quantify the redundant designs impact on the communication reliability between the consumers and the MDMS and on the energy-demand estimation-error cost.

2018 IEEE 12th International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG 2018), 2018

Medium-Voltage (MV) DC grids for collecting and integrating Photovoltaic (PV) systems offer an ef... more Medium-Voltage (MV) DC grids for collecting and integrating Photovoltaic (PV) systems offer an effective solution to overcome the problems introduced due to AC grid. The direct conversion of the PV power to MV DC grid increases the efficiency and reduces the cost when compared to MV AC grid. In MV DC grid connected PV systems, a high gain DC-DC converter is required to convert the unregulated PV DC voltage to a regulated MV DC voltage. In this paper, voltage Re-Lift and Super Re-Lift Luo converters, are used as high-gain DC-DC converters to integrate the solar energy into the MV DC grid. Design, modelling and analysis of the operation of these converters at MV high-power levels are presented. Also, performance assessment for the two different DC-DC converter topologies is conducted. Both the voltage Re-Lift and the Super Re-Lift Luo converters have high output voltage transfer gain, high power density, high efficiency, and high output voltage with small ripples. However, the Voltage-Lift Luo converter increases the output voltage in arithmetic progression, while the Super Lift Luo converter increases the output voltage in geometric progression. Digital simulations are carried out to validate the analysis and the comparison of the two converters performance using Matlab/Simulink platform for 10kV DC grid and 1MW PV power plant.

This abstract proposes a high brightness, high efficiency, dimmable LED driver based on linear cu... more This abstract proposes a high brightness, high efficiency, dimmable LED driver based on linear current regulator technology for DC grid distribution systems. The proposed driver has excellent characteristics like the highest lumen per watt, long lifetime, high reliability, compact, low cost, both environmental and user-friendly which makes it suitable for lighting applications. Steady state and small-signal models of the proposed driver are performed which help in minimizing ground current and accurate compensator design, respectively. These two modeling approaches result in the optimization of both the footprint and cost of the driver. The performance of the proposed experimental prototype of the 20W driver is developed to validate the performance at different dimming levels and achieves maximum efficiency of 97%. The applications of the proposed converter are: dimmable home lighting system, advertisement boards and hoardings, industrial lighting systems, road transport indication ...

2016 4th International Conference on the Development in the in Renewable Energy Technology (ICDRET), 2016

In this work, a study of a silicon carbide power modules in power inverter is presented. Voltage/... more In this work, a study of a silicon carbide power modules in power inverter is presented. Voltage/Current/power and switching energy loss characteristics based on experimental data are detailed. A comparative study of total power losses and efficiency of a silicon carbide based three phase inverter with silicon base is analyzed and studied. The efficiency of the silicon carbide based inverters based on Semi-south manufactured device is found to be about 99%, and is more efficient than known conventional silicon based inverters, especially at high frequency.

Electric Power Systems Research, 2020

Abstract With the advent of SiC devices, the packed U-Cell converter has become a promising topol... more Abstract With the advent of SiC devices, the packed U-Cell converter has become a promising topology among the multilevel converters for medium voltage DSTATCOM application. It utilizes fewer components while achieving the maximum voltage levels with higher reliability. However, as a reactive power compensator, its dc-link consists of flying capacitors, whose voltages must be balanced which presents a challenging problem for a seven-level packed U-Cell inverter, as there are no-redundant switching states. This paper proposes a novel control scheme to keep these flying capacitors balanced under normal/abnormal grid conditions. It consists of a standard cascaded: inner and outer controllers. The inner current controller regulates both the active and reactive currents and the outer controller regulates the upper flying capacitor voltage. In parallel with the cascaded controllers, a novel model predictive voltage balancing controller is proposed to maintain the lower flying capacitor voltage at a given setpoint. To cope with the unbalance grid conditions, an additional zero-sequence injection regulator is also integrated into the designed control scheme. The proposed control scheme was simulated and real-time tested on the Hardware-In-the-Loop system. The results show that the proposed controller effectively balances the two flying capacitor voltages while controlling the reactive power.

International Transactions on Electrical Energy Systems, 2017

Summary This paper proposes an enhancement of the low-voltage ride-through (LVRT) capability of m... more Summary This paper proposes an enhancement of the low-voltage ride-through (LVRT) capability of multilevel flying capacitors inverter using an improved model predictive control (MPC). The proposed solution is a multiobjective control strategy ensuring simultaneous capacitors' voltages balancing and grid current injection with reduced total harmonics distortion (THD) and unity power factor even under severe voltage sags. The proposed MPC technique makes use of a multioptimization solution for the common problem of weight dissimilarity of the control objectives. The first optimization is achieved by the inclusion of the state variables normalization within the cost function computation. This will provide to the proposed MPC technique more robustness with the ability to take into consideration external disturbances (grid voltage sag) while ensuring the meeting of the state variables constraints. The second one is achieved through accurately tuning the weighting factor based on minimizing the grid current total harmonics distortion and the maximal errors on the capacitors' voltages. Theoretical analysis and simulation results are presented to prove that the presented solution guarantees continuous and smooth power transfer to the grid even under severe voltage sags. The obtained results are validated on a 1-kW experimental prototype.

2022 3rd International Conference on Smart Grid and Renewable Energy (SGRE)

2022 3rd International Conference on Smart Grid and Renewable Energy (SGRE)

IEEE Access, 2022

This paper proposes an enhanced Deadbeat Controller (DBC) for a grid-tied Flying Capacitors Inver... more This paper proposes an enhanced Deadbeat Controller (DBC) for a grid-tied Flying Capacitors Inverter (FCI). The proposed DBC guarantees the balancing of the capacitors' voltages while injecting current to the grid with lower Total Harmonics Distortion (THD). The proposed controller has the following advantages: 1) Improved current tracking quality even at zero crossing instants by using a weighted statespace model, 2) Superior steady-state performance (lower current THD) compared to other prediction-based control techniques such as Finite-Control-Set Model Predictive Control, 3) The generated duty cycles are normalized to the common base when the desired state is out of reach within the sampling time, 4) Voltage Ride-Through (VRT) capability, and 5) Robustness to parameters variation. Theoretical analysis, simulation, and experimental results are presented to show the effectiveness of the proposed control technique in ensuring uninterruptible and smooth transfer of energy to the grid during normal/abnormal operating conditions (severe voltage sags, parameters variation, etc.).

2017 9th IEEE-GCC Conference and Exhibition (GCCCE), 2017

The potential of Photovoltaic (PV) panels as a main tool of harnessing solar energy is increasing... more The potential of Photovoltaic (PV) panels as a main tool of harnessing solar energy is increasing with the advancements in their power conditioning and conversion stages that vary based on applications. This paper focuses on the conversion of a 22kW PV array output from low-voltage to medium-voltage level (400V to 7kV). This high voltage conversion ratio is difficult to achieve using conventional single-stage DC-DC converters. Thus, different alternatives are proposed and compared here, namely, the Parallel-Input Series-Output (PISO) connection of two different stages using both isolated (full-bridge) and non-isolated DC-DC converters. The converters are compared on the basis of efficiency, footprint, components rating and reliability. Thus, the isolated DC-DC converter system efficiency was estimated at 797%, compared to 93 % for the non-isolated system, keeping into account the variations in terms of the filtering capacitor requirements to maintain a constant minimal voltage ripple at the output which is in favor of the non-isolated systems.

IEEE Transactions on Industry Applications, 2019

Requirement of large number of levels with lower number of switching devices has made asymmetrica... more Requirement of large number of levels with lower number of switching devices has made asymmetrical converters more popular than the symmetrical ones. Asymmetrical cascaded multilevel inverters (ACMLI) can achieve high efficiency by combining switching devices with different voltage ratings and technologies. The proposed ACMLI cascades two or more units of packed U-Cell (PUC) inverters using two or more isolated dc link supplies. In this article, one of the PUC unit is controlled using high switching frequency while the other PUCs are operated in a step mode at low switching frequencies, thus operating them in a variable frequency control mode. The cascading of two 7-level PUC inverters with dc link voltage ratio of 1:7 can produce an output voltage with 49 (7x7) levels. The multilevel output voltage waveform is nearly sinusoidal with very low THD content, and the low switching frequency operation leads to lower power dissipation and greater system efficiency. However, each PUC module requires two dc voltage sources. To address this concern, in this article, each PUC module consists of one dc voltage source and one dc bus capacitor. With the cascaded PUC topology and proposed control algorithm, load current and dc bus capacitor voltage control is achieved simultaneously. The proposed converter and its control technique lead to the breaking of the design tradeoff rule between switching frequency (efficiency) and filter size. This is very useful in various applications such as uninterruptible power supplies and grid-tie inverters. The converter and its control technique are simulated using MATLAB/Simulink software and simulation results for both open loop and closed loop are discussed. Hardware results are obtained by developing a 1-kW experimental prototype. Simulation and experimental results confirm the usefulness and effectiveness of the proposed topology and its control technique.

IET Power Electronics, 2017

Multiphase power converters generate common mode voltage due to switching actions of the power sw... more Multiphase power converters generate common mode voltage due to switching actions of the power switches. The resulting common mode current in multiphase motor drives flow through the bearing and shaft. Continuous flow of common mode current gradually weakens the performance of the drives. A space vector pulse width modulation (SVPWM) technique is developed to reduce Common mode voltage (CMV) in a three-to-five-phase matrix converter-based five-phase induction motor drive system. The principle of CMV reduction lies in the selection of proper space vectors for implementation of SVPWM. The proposed technique achieves reduction in the CMV without affecting other performances, i.e. loss in output voltage, total harmonic distortion in the output voltages and currents. The common mode voltage is reduced by selecting a set of proper zero space vectors and placing them in a suitable position within a switching cycle. Using this approach, CMV is reduced by ∼30%. Simulation and experimental results are provided for a five-phase induction motor drive fed using a three-to-five-phase matrix converter.

Electronics

An ultra-high step-up, non-isolated DC–DC converter with a continuous input current was developed... more An ultra-high step-up, non-isolated DC–DC converter with a continuous input current was developed as a result of this research. This converter’s architecture consists of a voltage multiplier cell (VMC), a positive output super lift Luo converter (POSLLC), and a quadratic boost converter (QBS) (also referred to as a cascaded boost topology (CBT)). Thus, the bold points of the topologies mentioned earlier enhance the voltage gain of the proposed topology. It is important to note that when the duty cycle is at 50%, the converter attains a voltage gain of ten. Additionally, the constant input current of the topology reduces the current stress on the input filter capacitor. This converter’s topology was investigated and studied under various operating conditions: ideal and non-ideal modes, as well as continuous and discontinuous current modes (CCM/DCM). The converter’s efficiency and voltage gain were also compared to those of newly proposed converters. PLECS and MATLAB software tools we...

2018 IEEE 12th International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG 2018), 2018

The shoot-through problem of conventional H-Bridge inverters imposes a threat to system's rel... more The shoot-through problem of conventional H-Bridge inverters imposes a threat to system's reliability and efficiency. This is because the unintentional shoot-through state short-circuits the DC-Link capacitor. To overcome the severity of the shoot-through state, Dual Buck Inverters (DBIs) were introduced. These topologies have at least one inductor connected in-parallel with the DC-Link capacitor at accidental shoot-through states' activation; thus, preventing the DC-side from getting short-circuited. Besides, DBIs' circulate inherently low ground leakage current and thereby they are considered as attractive choices in single-phase non-isolated grid-connected Photovoltaic (PV) applications. Therefore, this work proposes a modified non-isolated grid-tied LCL-filter based DBI with a control scheme that improves the reliability and the stability. Specifically, adopting an appropriate Active Power Decoupling Control (APDC) scheme enhances the reliability. This scheme utilizes the Common-Mode (CM) operation of the DBI. As for stability assurance, an Active Resonance Damping Control (ARDC) is developed. This ARDC is deployed in both inverter modes, the CM and the Differential-Mode (DM). Eventually, the theoretical analyses are confirmed on a 3 kW / 30 μΚ electrolytic capacitor-less system. The results showed that the single-phase low frequency ripples of the DC-bus voltage were negligible. Meaning that, the input capacitance requirement of the system is reduced about 40–50 times compared to the conventional methodology. Consequently, utilizing reliable polypropylene film capacitors for effective DC-Linking.

International Journal of Electrical Power & Energy Systems

Abstract Compared to conventional multilevel topologies, the Packed U-Cell multilevel topology ut... more Abstract Compared to conventional multilevel topologies, the Packed U-Cell multilevel topology utilizes the minimum number of components and provides both maximum voltage levels and high reliability. When used in a battery energy storage system, its dc-link consists of a top branch battery storage and bottom branch flying capacitors, whose state of charge and voltages must be balanced.This paper proposes a novel control scheme with two cascaded controllers: the inner loop regulates the output filter current and dc-link voltages using a novel finite-set model predictive control, the outer one is fully integrated with the model predictive controller and regulates the battery state of charge by injecting a zero-sequence voltage. The proposed control scheme was successfully implemented and tested through simulation and real-time testing. The obtained results highlight good dynamic performance and robustness of the proposed scheme during active power injection/absorption and low voltage ride-through capability.

2019 IEEE 28th International Symposium on Industrial Electronics (ISIE), 2019

A novel configurations of a non-isolated Modified SEPIC Converter with two Voltage Lift Switched ... more A novel configurations of a non-isolated Modified SEPIC Converter with two Voltage Lift Switched Inductor (MSCVLSI) modules namely MSCVLSI-XYL, MSCVLSI-LYZ and MSCVLSI-XLZ are presented in the paper. The key features of these configurations are, 1) high voltage conversion ratio, 2) single controlled switch, 3) high-value input inductor to smooth the input current, 4) maximum utilization of input source, 5) continuous input current. With these notable features, proposed configurations are more convenient for high voltage renewable energy applications to boost the low voltage of photovoltaic array/fuel cell. The feasibility of these converter configurations are verified by mathematical analysis and simulation results. MSCVLSI configurations are simulated for 250 W resistive load and at 50 kHz switching frequency.

2018 IEEE 12th International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG 2018), 2018

The Quasi-Z-Source (QZS) inverters are the promising topology for the renewable integration with ... more The Quasi-Z-Source (QZS) inverters are the promising topology for the renewable integration with the grid. QZSI achieves the MPPT during the shoot through state, without additional DC-DC converter, and simultaneously delivering the AC power to the grid or motor load. The quasi components (L and C) sizes are reduced by increasing the switching frequency of the converters. But the switching losses of the converter will dominate at the higher frequencies. To minimize the switching losses of the converter, this paper proposes reduced switching loss single stage inverter for high power applications. Using only six devices rated at supply voltage, the QZS resonant converter can operate properly by adding resonant inductor and capacitor to the ac side of each phase. The proposed converter can control the output with true pulse width modulation (PWM) at high frequency and the Zero Voltage Switching (ZVS) and Zero Current Switching is achieved at every switching cycle. The detailed analysis, modulation and simulation are presented to verify the operating principle of the QZS resonant converter.

2017 IEEE Energy Conversion Congress and Exposition (ECCE), 2017

In this paper, Solar powered Single-Phase Capacitor Start Induction motor for water pump applicat... more In this paper, Solar powered Single-Phase Capacitor Start Induction motor for water pump application is discussed. Output of solar panel is connected to quasi Z Source Inverter (qZSI). Three modules of qZSI are connected in cascade to give seven level output voltage. Single phase motor is powered with cascaded qZSI to obtain the improved performance due to multilevel inverter. As the power generated from PV system is highly variable due to its dependency on various parameters, qZSI with variable boosting is controlled for achieving the desired rms voltage. Voltage boosting feature of qZSI allows for reliable operation of Single Phase Induction motor. Closed loop control of virtual dc bus voltage is achieved. Simulation results showing the performance of single phase motor powered with cascaded qZSI for various load torque are shown and discussed. Model of Solar panel is used as input supply for qZSI. Experimental results for closed loop voltage control of multilevel qZSI for RL load are discussed. Future work includes the development of hardware setup for observation of Single phase capacitor start Induction motor when it powered with Cascaded multilevel qZSI.

2018 IEEE 12th International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG 2018), 2018

Modular multilevel converter is becoming a great candidate for high power applications due to its... more Modular multilevel converter is becoming a great candidate for high power applications due to its valuable features. However, its higher performance comes at the expenses of higher complexity, which increases the risks of failures. Power switches can be accounted among the most vulnerable components in this converter and their failure can lead to the regular functioning destabilization and eventual shutdowns. Failures in power switches can be induced by either open or short circuits faults. This paper presents the principle component analysis, which is a data-driven approach, to tackle the open circuit faults detection in modular multilevel converters. The results were compared to the performance of a model-based technique, the sliding mode observer, and showed a better performance of the adopted approach.

ArXiv, 2017

We consider multiple source nodes (consumers) communicating wirelessly their energy demands to th... more We consider multiple source nodes (consumers) communicating wirelessly their energy demands to the meter data-management system (MDMS) over the subarea gateway(s). We quantify the impacts of passive and active security attacks on the wireless communications system's reliability and security as well as the energy-demand estimation-error cost in dollars paid by the utility. We adopt a multiple-input multiple-output multi-antenna-eavesdropper (MIMOME) wiretap channel model. To secure the MIMO wireless communication system, the legitimate nodes generate artificial noise (AN) vectors to mitigate the effect of the passive eavesdropping attacks. In addition, we propose a redundant design where multiple gateways are assumed to coexist in each subarea to forward the consumers' energy-demand messages. We quantify the redundant designs impact on the communication reliability between the consumers and the MDMS and on the energy-demand estimation-error cost.

2018 IEEE 12th International Conference on Compatibility, Power Electronics and Power Engineering (CPE-POWERENG 2018), 2018

Medium-Voltage (MV) DC grids for collecting and integrating Photovoltaic (PV) systems offer an ef... more Medium-Voltage (MV) DC grids for collecting and integrating Photovoltaic (PV) systems offer an effective solution to overcome the problems introduced due to AC grid. The direct conversion of the PV power to MV DC grid increases the efficiency and reduces the cost when compared to MV AC grid. In MV DC grid connected PV systems, a high gain DC-DC converter is required to convert the unregulated PV DC voltage to a regulated MV DC voltage. In this paper, voltage Re-Lift and Super Re-Lift Luo converters, are used as high-gain DC-DC converters to integrate the solar energy into the MV DC grid. Design, modelling and analysis of the operation of these converters at MV high-power levels are presented. Also, performance assessment for the two different DC-DC converter topologies is conducted. Both the voltage Re-Lift and the Super Re-Lift Luo converters have high output voltage transfer gain, high power density, high efficiency, and high output voltage with small ripples. However, the Voltage-Lift Luo converter increases the output voltage in arithmetic progression, while the Super Lift Luo converter increases the output voltage in geometric progression. Digital simulations are carried out to validate the analysis and the comparison of the two converters performance using Matlab/Simulink platform for 10kV DC grid and 1MW PV power plant.

This abstract proposes a high brightness, high efficiency, dimmable LED driver based on linear cu... more This abstract proposes a high brightness, high efficiency, dimmable LED driver based on linear current regulator technology for DC grid distribution systems. The proposed driver has excellent characteristics like the highest lumen per watt, long lifetime, high reliability, compact, low cost, both environmental and user-friendly which makes it suitable for lighting applications. Steady state and small-signal models of the proposed driver are performed which help in minimizing ground current and accurate compensator design, respectively. These two modeling approaches result in the optimization of both the footprint and cost of the driver. The performance of the proposed experimental prototype of the 20W driver is developed to validate the performance at different dimming levels and achieves maximum efficiency of 97%. The applications of the proposed converter are: dimmable home lighting system, advertisement boards and hoardings, industrial lighting systems, road transport indication ...

2016 4th International Conference on the Development in the in Renewable Energy Technology (ICDRET), 2016

In this work, a study of a silicon carbide power modules in power inverter is presented. Voltage/... more In this work, a study of a silicon carbide power modules in power inverter is presented. Voltage/Current/power and switching energy loss characteristics based on experimental data are detailed. A comparative study of total power losses and efficiency of a silicon carbide based three phase inverter with silicon base is analyzed and studied. The efficiency of the silicon carbide based inverters based on Semi-south manufactured device is found to be about 99%, and is more efficient than known conventional silicon based inverters, especially at high frequency.

Electric Power Systems Research, 2020

Abstract With the advent of SiC devices, the packed U-Cell converter has become a promising topol... more Abstract With the advent of SiC devices, the packed U-Cell converter has become a promising topology among the multilevel converters for medium voltage DSTATCOM application. It utilizes fewer components while achieving the maximum voltage levels with higher reliability. However, as a reactive power compensator, its dc-link consists of flying capacitors, whose voltages must be balanced which presents a challenging problem for a seven-level packed U-Cell inverter, as there are no-redundant switching states. This paper proposes a novel control scheme to keep these flying capacitors balanced under normal/abnormal grid conditions. It consists of a standard cascaded: inner and outer controllers. The inner current controller regulates both the active and reactive currents and the outer controller regulates the upper flying capacitor voltage. In parallel with the cascaded controllers, a novel model predictive voltage balancing controller is proposed to maintain the lower flying capacitor voltage at a given setpoint. To cope with the unbalance grid conditions, an additional zero-sequence injection regulator is also integrated into the designed control scheme. The proposed control scheme was simulated and real-time tested on the Hardware-In-the-Loop system. The results show that the proposed controller effectively balances the two flying capacitor voltages while controlling the reactive power.

International Transactions on Electrical Energy Systems, 2017

Summary This paper proposes an enhancement of the low-voltage ride-through (LVRT) capability of m... more Summary This paper proposes an enhancement of the low-voltage ride-through (LVRT) capability of multilevel flying capacitors inverter using an improved model predictive control (MPC). The proposed solution is a multiobjective control strategy ensuring simultaneous capacitors' voltages balancing and grid current injection with reduced total harmonics distortion (THD) and unity power factor even under severe voltage sags. The proposed MPC technique makes use of a multioptimization solution for the common problem of weight dissimilarity of the control objectives. The first optimization is achieved by the inclusion of the state variables normalization within the cost function computation. This will provide to the proposed MPC technique more robustness with the ability to take into consideration external disturbances (grid voltage sag) while ensuring the meeting of the state variables constraints. The second one is achieved through accurately tuning the weighting factor based on minimizing the grid current total harmonics distortion and the maximal errors on the capacitors' voltages. Theoretical analysis and simulation results are presented to prove that the presented solution guarantees continuous and smooth power transfer to the grid even under severe voltage sags. The obtained results are validated on a 1-kW experimental prototype.