2020 IEEE 61th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)
This paper compares the performance and power losses of Silicon (Si) semiconductor based Modular ... more This paper compares the performance and power losses of Silicon (Si) semiconductor based Modular Mutilevel Converter (MMC) and Silicon-Carbide (SiC) semiconductor based MMC in a 22kV-2SMVA Static Synchronous Compensator (STATCOM) application in Matlab/Simulink environment. Semiconductor switching and conduction losses are compared at different operating points for both types of the semiconductors. The study result suggests SiC semiconductor based MMC can reduce the converter power losses significantly compared to Si semiconductor based MMC.
2021 23rd European Conference on Power Electronics and Applications (EPE'21 ECCE Europe)
With the increasing penetration of renewable energy systems into the power grid, stability and sa... more With the increasing penetration of renewable energy systems into the power grid, stability and safe operation during grid faults have become a great challenge. The phase and frequency of the grid voltage are the important information for the acquisition of the reference value of the grid-connected converter control signal and ensure the smooth, reliable and stable operation of the grid-connected converter system. In this paper, a new concept the frequency locked loop with frozen mechanism is proposed, which is used for solving the grid synchronization problem of the power grid under unbalanced and distorted operating conditions. The frequency locked loop with frozen mechanism consists of the frequency-locked loop (FLL) based on the Second-order generalized integrator (SOGI) which tuned at grid frequency and the frequency frozen mechanism which guarantee the stability during the severe faults.
Grid-forming inverters are sensitive to large grid disturbances that may engender overcurrent due... more Grid-forming inverters are sensitive to large grid disturbances that may engender overcurrent due to their voltage source behavior. To overcome this critical issue and ensure the safety of the system, current limitation techniques have to be implemented. In this context, the variable virtual impedance (VI) appears as a suitable solution for this problem. The design of the variable virtual impedance basically rests on static considerations, while, its impact on the system stability and dynamics considering both small-signal and large-signal aspects can be significant. This paper proposes small-signal and nonlinear power models to assess the impact of the virtual impedance parameters on the grid current dynamics and on the angle stability. Thanks to the developed theoretical approaches in this paper, the virtual impedance ratio X/R, which is the unique degree of freedom has shown a contradictory effect on the small and large signal stability. To overcome this constraint, a Variable Tr...
The research activities for maximum energy absorption from wave energy converters (WECs) are very... more The research activities for maximum energy absorption from wave energy converters (WECs) are very often limited to hydrodynamic control and performance of the power take-off (PTO) which mostly simplifies the power electronics conversion systems. There are only few studies that show deep analysis of connecting the generated voltage to the grid by using the most developed power electronics technologies. The main objective of this study is (i) to develop a full wave-to-grid model to show all conversion stages from ocean waves to the electricity network, (ii) to combine the WEC with neutral point clamped (NPC) inverter which uses advanced nearest three vector–space vector–pulse width modulation (NTV-SV-PWM) method based on a look-up table that can build up a sinusoidal voltage waveform at the inverter output with the least number of switching in the power circuit and the best possible harmonic spectrum without the need for any big filtering.
IECON 2020 The 46th Annual Conference of the IEEE Industrial Electronics Society, 2020
Modular Multilevel Converter (MMC) has gained popularity in the last decade since it is a transfo... more Modular Multilevel Converter (MMC) has gained popularity in the last decade since it is a transformer-less multilevel converter topology most commonly used in medium and high voltage power conversion applications. There are several component values as well as control parameters which contribute to the operation of MMC. However, the submodule capacitor which is used for energy storage during AC/DC or DC /AC power conversion is one of the most important components in MMC that has a very big impact on the system performance and contributes to large share of the total weight and volume. Under dimensioning the submodule capacitance causes a high capacitor voltage ripple and deteriorate the system performance and on the other hand over dimensioning the submodule capacitance results in higher system cost and system oversize. It is therefore of great importance to dimension the capacitor optimally.
IECON 2021 – 47th Annual Conference of the IEEE Industrial Electronics Society, 2021
This work analyzes the operation of a Modular Multilevel Converter (MMC) Single Delta Bridge Cell... more This work analyzes the operation of a Modular Multilevel Converter (MMC) Single Delta Bridge Cell (SDBC) Static Synchronous Compensator (STATCOM) under unbalanced grid conditions based on different sequence extraction methods: Decoupled Double Synchronous Reference Frame (DDSRF), Dual Second Order Generalized Integrator (DSOGI), and Fortescue matrix-based filter in αβ frame. The conventional Voltage Oriented Control (VOC) cannot eliminate the 2ω components caused by unbalanced grid disturbances, which leads to the obstruction of the system along with its control operations. Moreover, under such conditions, the phase-locked loop (PLL) fails to provide an accurate frequency and phase angle of the AC voltage resulting in synchronization failure and non-accurate current injections. Sequence extraction aids the PLL to maintain the synchronization with the grid by following the fundamental component of the voltage positive sequence and allows for the appropriate injection of active and reactive currents. In this paper, the system behavior based on each sequence extraction method is investigated and its impact on the dynamic performances is highlighted through time-domain simulations performed in MATLAB/Simulink.
IECON 2021 – 47th Annual Conference of the IEEE Industrial Electronics Society, 2021
This paper presents an implementation methodology to model a single delta bridge cell (full-bridg... more This paper presents an implementation methodology to model a single delta bridge cell (full-bridge) modular multilevel converter static synchronous compensator (SDBC-MMC-STATCOM) in FPGA based real-time simulator. Mathematical modeling of full-bridge submodule and equivalent circuit-based modeling of single delta bridge cell modular multilevel converter is presented. This paper also discusses about different discretization strategies to convert continuous time equations into z-domain equations for implementation in field programmable gate array (FPGA). The discretized equations are verified by comparing its voltage and current waveforms with its equivalent model developed using the Simscape Electrical Specialized Power Systems library in Simulink. The testing is carried out with 4kV, 2MVA STATCOM model with phase-shifted carrier-based modulation. The model is then implemented in FPGA to perform real-time simulation in OPAL-RT real -time simulator. The tests verify that the real-time model of the STATCOM behaves similar to the Simulink reference model for positive sequence reactive power compensation with no voltage unbalance at the point of common coupling (PCC).
IECON 2021 – 47th Annual Conference of the IEEE Industrial Electronics Society, 2021
In this paper, a common current control structure in the stationary reference frame, comprising a... more In this paper, a common current control structure in the stationary reference frame, comprising a proportional resonant (PR-)controller and additional resonant control units for harmonic suppression, is applied to a modular multilevel converter (MMC). Discretization of the controllers as well as different control targets in the context of distorted grid quantities are addressed. Current harmonic rejection is achieved applying a resonant band-pass unit to generate the according references for the current control. Simulations are performed to evaluate the designed control.
2018 7th International Conference on Renewable Energy Research and Applications (ICRERA), 2018
Modular Multilevel Converter (MMC) are increasingly used in Medium Voltage and High Voltage indus... more Modular Multilevel Converter (MMC) are increasingly used in Medium Voltage and High Voltage industries for various applications. In this paper, averaging and circulating current control integrated with Selective Harmonic Elimination (SHE) modulation based on Nearest Level Control (NLC) is proposed in order to improve the performance of MMC in terms of stable operation and harmonic performance compared to existing state of art. The methodology to design the parameters of averaging and circulating current controller based on pole-zero cancellation is expounded. Further, the control techniques are integrated with SHE based NLC in order to achieve good control of state variables and superior harmonic performance. The simulation studies are carried out for a 11kV, 25MVA MMC in MATLAB/Simulink. The performance of the proposed SHE-NLC is compared with conventional NLC in terms harmonic performance in the output parameters such as voltage and current.
2020 22nd European Conference on Power Electronics and Applications (EPE'20 ECCE Europe), 2020
Temperature control was integrated to an experimentally verified hybrid modulation scheme driving... more Temperature control was integrated to an experimentally verified hybrid modulation scheme driving a modular multilevel converter. It was shown that it has 11% lower total harmonic distortion and 16% lower losses in comparison with the phase shifted carrier methodology while maintaining a temperature difference of 1°C.
The modular multilevel converter (M2C) will play an important role in the future especially for h... more The modular multilevel converter (M2C) will play an important role in the future especially for high-voltage and highpower applications where controllability is a key factor. Although a lot of research has been carried out on this topic, little has been done to understand how different system parameters, like the arm reactor, the submodule capacitor, number of submodules and switching frequency, influence the performance of the converter. In this study, a robust model of a M2C was presented and used to perform an extensive parametric sweep versus the variables mentioned above. It has been shown that by implementing an anti-windup scheme, the model remains stable over a large range of parameters. It has also been shown that an optimum knee point exists in all total harmonic distortion (THD) graphs versus inductance, capacitance, number of submodules and switching frequency. Finally, it has been shown that to decrease THD, the number of submodules can be increased while making sure the effective arm capacitance is maintained constant.
2016 57th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON), 2016
In this study, the power extraction from oscillating water column device is done by using three l... more In this study, the power extraction from oscillating water column device is done by using three level active rectifier and three level inverter which is controlled by using NTV-SV-PWM method. The mid-point balancing of the DC-link is achieved by using a look-up table, aiming to improve the efficiency, the response time of the system and the quality of the power transferred to the grid.
By using an accurate switching model it's possible to adjust the thermal distribution between... more By using an accurate switching model it's possible to adjust the thermal distribution between the semiconductors and increase the output power of the converter for Active Neutral Point Clamped converters [1]. In this paper the study of switching sequence optimization for 3 Level ANPC converters is extended to analyze the performance of the converter under different cooling water inlet temperatures and different water/glycol mixtures of the cooling water.
2008 IEEE International Conference on Sustainable Energy Technologies, 2008
The submarine lead acid batteries require high current (~8 kA) and low voltage (~10 V) battery ch... more The submarine lead acid batteries require high current (~8 kA) and low voltage (~10 V) battery chargers because of their high capacities. The need to install the power converters in small place is the driving force for reduced volume and high efficiency. Moreover, the high power lead acid batteries require very low voltage and current ripples and a very high
2018 IEEE Energy Conversion Congress and Exposition (ECCE), 2018
The modular multilevel converter is advantageous in medium and high voltage applications with AC/... more The modular multilevel converter is advantageous in medium and high voltage applications with AC/DC-coupling capability. In medium voltage converters both phase shift pulse-width modulation (PSPWM) and nearest-level control (NLC) methods are feasible. The modulation approach is a key factor for the current control, submodule voltage equalization, semiconductor losses, and total harmonic distortion (THD). In this work aforementioned criteria are analyzed for two converters with parameters in the region where the decision between the two modulation methods is not clear at a first glance. The aim of the work was to evaluate the overall losses and THD performance from the design perspective of a 11 kV, 25 MVA converter. The results showed that after changing the modulation method from PSPWM to NLC the overall system losses decreased in average by 6.3% for the 1.7 kV design and by 32.2% for the 4.5 kV design. Using NLC is beneficial for high voltage class IGBTs where switching losses dominate. This however comes at the expense of higher voltage and current harmonics.
Under grid distortions, Modular Multilevel Converters (MMC) must adopt proper control strategies ... more Under grid distortions, Modular Multilevel Converters (MMC) must adopt proper control strategies to fulfill the power system requirements and ensure a stable operation. An inappropriate control under such conditions may lead to energy unbalances between the MMC legs, inaccurate current injection, and failure in the synchronization process. In this context, sequence extraction methods play a critical role in enhancing the performance of the control, firstly, by aiding the Phase-Locked Loop (PLL) to maintain the synchronization with the AC grid by following the positive sequence fundamental component of the voltage, secondly, by allowing an accurate active and reactive currents injection via the decoupled Voltage Oriented Control (dVOC), thirdly, by properly managing the internal energy of the MMC through the circulating current control. In prior researches, some sequence extraction methods have been used for MMC STATCOM. However, the sequence extraction was not the core of the perfor...
Ocean wave energy is one of the high potential renewable energy sources. Due to the recent progre... more Ocean wave energy is one of the high potential renewable energy sources. Due to the recent progresses in the OWEC devices higher power extraction is possible which also brings the need of using multilevel converters to increase the voltage together with power. In this study, adaption of a sophisticated NTV-SV-PWM method to the multilevel converter is proposed, aiming to improve the energy extraction efficiency and the quality of the power transferred to the grid.
2015 56th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON), 2015
Ocean wave energy is one of the high potential renewable energy sources. Due to the recent progre... more Ocean wave energy is one of the high potential renewable energy sources. Due to the recent progresses in the OWEC devices higher power extraction is possible which also brings the need of using multilevel converters to increase the voltage together with power. In this study, adaption of a sophisticated NTV-SV-PWM method to the multilevel converter is proposed, aiming to improve the energy extraction efficiency and the quality of the power transferred to the grid.
The ANPC topology was developed to overcome the unequal power distribution among the semiconducto... more The ANPC topology was developed to overcome the unequal power distribution among the semiconductors in NPC topology. By using an accurate switching model it's possible to adjust the thermal distribution between the semiconductors and increase the output power of the converter. This study focuses on the PWM-3 (fpwm = 350Hz), PWM-5 (fpwm = 550Hz), and PWM-7 (fpwm = 750Hz) and defines the optimum switching sequence for each frequency and specifies the maximum current rating of IGCT based ANPC converter for the mentioned optimum switching sequence.
Iecon 2010 36th Annual Conference on Ieee Industrial Electronics Society, Nov 1, 2010
Abstract-Supplying regulated voltage to critical loads is an important topic for several years. T... more Abstract-Supplying regulated voltage to critical loads is an important topic for several years. This paper presents a single-phase electronic voltage regulator based on high frequency switching of an isolated transformer where primary side voltage is controlled by two full-bridge ...
2020 IEEE 61th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)
This paper compares the performance and power losses of Silicon (Si) semiconductor based Modular ... more This paper compares the performance and power losses of Silicon (Si) semiconductor based Modular Mutilevel Converter (MMC) and Silicon-Carbide (SiC) semiconductor based MMC in a 22kV-2SMVA Static Synchronous Compensator (STATCOM) application in Matlab/Simulink environment. Semiconductor switching and conduction losses are compared at different operating points for both types of the semiconductors. The study result suggests SiC semiconductor based MMC can reduce the converter power losses significantly compared to Si semiconductor based MMC.
2021 23rd European Conference on Power Electronics and Applications (EPE'21 ECCE Europe)
With the increasing penetration of renewable energy systems into the power grid, stability and sa... more With the increasing penetration of renewable energy systems into the power grid, stability and safe operation during grid faults have become a great challenge. The phase and frequency of the grid voltage are the important information for the acquisition of the reference value of the grid-connected converter control signal and ensure the smooth, reliable and stable operation of the grid-connected converter system. In this paper, a new concept the frequency locked loop with frozen mechanism is proposed, which is used for solving the grid synchronization problem of the power grid under unbalanced and distorted operating conditions. The frequency locked loop with frozen mechanism consists of the frequency-locked loop (FLL) based on the Second-order generalized integrator (SOGI) which tuned at grid frequency and the frequency frozen mechanism which guarantee the stability during the severe faults.
Grid-forming inverters are sensitive to large grid disturbances that may engender overcurrent due... more Grid-forming inverters are sensitive to large grid disturbances that may engender overcurrent due to their voltage source behavior. To overcome this critical issue and ensure the safety of the system, current limitation techniques have to be implemented. In this context, the variable virtual impedance (VI) appears as a suitable solution for this problem. The design of the variable virtual impedance basically rests on static considerations, while, its impact on the system stability and dynamics considering both small-signal and large-signal aspects can be significant. This paper proposes small-signal and nonlinear power models to assess the impact of the virtual impedance parameters on the grid current dynamics and on the angle stability. Thanks to the developed theoretical approaches in this paper, the virtual impedance ratio X/R, which is the unique degree of freedom has shown a contradictory effect on the small and large signal stability. To overcome this constraint, a Variable Tr...
The research activities for maximum energy absorption from wave energy converters (WECs) are very... more The research activities for maximum energy absorption from wave energy converters (WECs) are very often limited to hydrodynamic control and performance of the power take-off (PTO) which mostly simplifies the power electronics conversion systems. There are only few studies that show deep analysis of connecting the generated voltage to the grid by using the most developed power electronics technologies. The main objective of this study is (i) to develop a full wave-to-grid model to show all conversion stages from ocean waves to the electricity network, (ii) to combine the WEC with neutral point clamped (NPC) inverter which uses advanced nearest three vector–space vector–pulse width modulation (NTV-SV-PWM) method based on a look-up table that can build up a sinusoidal voltage waveform at the inverter output with the least number of switching in the power circuit and the best possible harmonic spectrum without the need for any big filtering.
IECON 2020 The 46th Annual Conference of the IEEE Industrial Electronics Society, 2020
Modular Multilevel Converter (MMC) has gained popularity in the last decade since it is a transfo... more Modular Multilevel Converter (MMC) has gained popularity in the last decade since it is a transformer-less multilevel converter topology most commonly used in medium and high voltage power conversion applications. There are several component values as well as control parameters which contribute to the operation of MMC. However, the submodule capacitor which is used for energy storage during AC/DC or DC /AC power conversion is one of the most important components in MMC that has a very big impact on the system performance and contributes to large share of the total weight and volume. Under dimensioning the submodule capacitance causes a high capacitor voltage ripple and deteriorate the system performance and on the other hand over dimensioning the submodule capacitance results in higher system cost and system oversize. It is therefore of great importance to dimension the capacitor optimally.
IECON 2021 – 47th Annual Conference of the IEEE Industrial Electronics Society, 2021
This work analyzes the operation of a Modular Multilevel Converter (MMC) Single Delta Bridge Cell... more This work analyzes the operation of a Modular Multilevel Converter (MMC) Single Delta Bridge Cell (SDBC) Static Synchronous Compensator (STATCOM) under unbalanced grid conditions based on different sequence extraction methods: Decoupled Double Synchronous Reference Frame (DDSRF), Dual Second Order Generalized Integrator (DSOGI), and Fortescue matrix-based filter in αβ frame. The conventional Voltage Oriented Control (VOC) cannot eliminate the 2ω components caused by unbalanced grid disturbances, which leads to the obstruction of the system along with its control operations. Moreover, under such conditions, the phase-locked loop (PLL) fails to provide an accurate frequency and phase angle of the AC voltage resulting in synchronization failure and non-accurate current injections. Sequence extraction aids the PLL to maintain the synchronization with the grid by following the fundamental component of the voltage positive sequence and allows for the appropriate injection of active and reactive currents. In this paper, the system behavior based on each sequence extraction method is investigated and its impact on the dynamic performances is highlighted through time-domain simulations performed in MATLAB/Simulink.
IECON 2021 – 47th Annual Conference of the IEEE Industrial Electronics Society, 2021
This paper presents an implementation methodology to model a single delta bridge cell (full-bridg... more This paper presents an implementation methodology to model a single delta bridge cell (full-bridge) modular multilevel converter static synchronous compensator (SDBC-MMC-STATCOM) in FPGA based real-time simulator. Mathematical modeling of full-bridge submodule and equivalent circuit-based modeling of single delta bridge cell modular multilevel converter is presented. This paper also discusses about different discretization strategies to convert continuous time equations into z-domain equations for implementation in field programmable gate array (FPGA). The discretized equations are verified by comparing its voltage and current waveforms with its equivalent model developed using the Simscape Electrical Specialized Power Systems library in Simulink. The testing is carried out with 4kV, 2MVA STATCOM model with phase-shifted carrier-based modulation. The model is then implemented in FPGA to perform real-time simulation in OPAL-RT real -time simulator. The tests verify that the real-time model of the STATCOM behaves similar to the Simulink reference model for positive sequence reactive power compensation with no voltage unbalance at the point of common coupling (PCC).
IECON 2021 – 47th Annual Conference of the IEEE Industrial Electronics Society, 2021
In this paper, a common current control structure in the stationary reference frame, comprising a... more In this paper, a common current control structure in the stationary reference frame, comprising a proportional resonant (PR-)controller and additional resonant control units for harmonic suppression, is applied to a modular multilevel converter (MMC). Discretization of the controllers as well as different control targets in the context of distorted grid quantities are addressed. Current harmonic rejection is achieved applying a resonant band-pass unit to generate the according references for the current control. Simulations are performed to evaluate the designed control.
2018 7th International Conference on Renewable Energy Research and Applications (ICRERA), 2018
Modular Multilevel Converter (MMC) are increasingly used in Medium Voltage and High Voltage indus... more Modular Multilevel Converter (MMC) are increasingly used in Medium Voltage and High Voltage industries for various applications. In this paper, averaging and circulating current control integrated with Selective Harmonic Elimination (SHE) modulation based on Nearest Level Control (NLC) is proposed in order to improve the performance of MMC in terms of stable operation and harmonic performance compared to existing state of art. The methodology to design the parameters of averaging and circulating current controller based on pole-zero cancellation is expounded. Further, the control techniques are integrated with SHE based NLC in order to achieve good control of state variables and superior harmonic performance. The simulation studies are carried out for a 11kV, 25MVA MMC in MATLAB/Simulink. The performance of the proposed SHE-NLC is compared with conventional NLC in terms harmonic performance in the output parameters such as voltage and current.
2020 22nd European Conference on Power Electronics and Applications (EPE'20 ECCE Europe), 2020
Temperature control was integrated to an experimentally verified hybrid modulation scheme driving... more Temperature control was integrated to an experimentally verified hybrid modulation scheme driving a modular multilevel converter. It was shown that it has 11% lower total harmonic distortion and 16% lower losses in comparison with the phase shifted carrier methodology while maintaining a temperature difference of 1°C.
The modular multilevel converter (M2C) will play an important role in the future especially for h... more The modular multilevel converter (M2C) will play an important role in the future especially for high-voltage and highpower applications where controllability is a key factor. Although a lot of research has been carried out on this topic, little has been done to understand how different system parameters, like the arm reactor, the submodule capacitor, number of submodules and switching frequency, influence the performance of the converter. In this study, a robust model of a M2C was presented and used to perform an extensive parametric sweep versus the variables mentioned above. It has been shown that by implementing an anti-windup scheme, the model remains stable over a large range of parameters. It has also been shown that an optimum knee point exists in all total harmonic distortion (THD) graphs versus inductance, capacitance, number of submodules and switching frequency. Finally, it has been shown that to decrease THD, the number of submodules can be increased while making sure the effective arm capacitance is maintained constant.
2016 57th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON), 2016
In this study, the power extraction from oscillating water column device is done by using three l... more In this study, the power extraction from oscillating water column device is done by using three level active rectifier and three level inverter which is controlled by using NTV-SV-PWM method. The mid-point balancing of the DC-link is achieved by using a look-up table, aiming to improve the efficiency, the response time of the system and the quality of the power transferred to the grid.
By using an accurate switching model it's possible to adjust the thermal distribution between... more By using an accurate switching model it's possible to adjust the thermal distribution between the semiconductors and increase the output power of the converter for Active Neutral Point Clamped converters [1]. In this paper the study of switching sequence optimization for 3 Level ANPC converters is extended to analyze the performance of the converter under different cooling water inlet temperatures and different water/glycol mixtures of the cooling water.
2008 IEEE International Conference on Sustainable Energy Technologies, 2008
The submarine lead acid batteries require high current (~8 kA) and low voltage (~10 V) battery ch... more The submarine lead acid batteries require high current (~8 kA) and low voltage (~10 V) battery chargers because of their high capacities. The need to install the power converters in small place is the driving force for reduced volume and high efficiency. Moreover, the high power lead acid batteries require very low voltage and current ripples and a very high
2018 IEEE Energy Conversion Congress and Exposition (ECCE), 2018
The modular multilevel converter is advantageous in medium and high voltage applications with AC/... more The modular multilevel converter is advantageous in medium and high voltage applications with AC/DC-coupling capability. In medium voltage converters both phase shift pulse-width modulation (PSPWM) and nearest-level control (NLC) methods are feasible. The modulation approach is a key factor for the current control, submodule voltage equalization, semiconductor losses, and total harmonic distortion (THD). In this work aforementioned criteria are analyzed for two converters with parameters in the region where the decision between the two modulation methods is not clear at a first glance. The aim of the work was to evaluate the overall losses and THD performance from the design perspective of a 11 kV, 25 MVA converter. The results showed that after changing the modulation method from PSPWM to NLC the overall system losses decreased in average by 6.3% for the 1.7 kV design and by 32.2% for the 4.5 kV design. Using NLC is beneficial for high voltage class IGBTs where switching losses dominate. This however comes at the expense of higher voltage and current harmonics.
Under grid distortions, Modular Multilevel Converters (MMC) must adopt proper control strategies ... more Under grid distortions, Modular Multilevel Converters (MMC) must adopt proper control strategies to fulfill the power system requirements and ensure a stable operation. An inappropriate control under such conditions may lead to energy unbalances between the MMC legs, inaccurate current injection, and failure in the synchronization process. In this context, sequence extraction methods play a critical role in enhancing the performance of the control, firstly, by aiding the Phase-Locked Loop (PLL) to maintain the synchronization with the AC grid by following the positive sequence fundamental component of the voltage, secondly, by allowing an accurate active and reactive currents injection via the decoupled Voltage Oriented Control (dVOC), thirdly, by properly managing the internal energy of the MMC through the circulating current control. In prior researches, some sequence extraction methods have been used for MMC STATCOM. However, the sequence extraction was not the core of the perfor...
Ocean wave energy is one of the high potential renewable energy sources. Due to the recent progre... more Ocean wave energy is one of the high potential renewable energy sources. Due to the recent progresses in the OWEC devices higher power extraction is possible which also brings the need of using multilevel converters to increase the voltage together with power. In this study, adaption of a sophisticated NTV-SV-PWM method to the multilevel converter is proposed, aiming to improve the energy extraction efficiency and the quality of the power transferred to the grid.
2015 56th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON), 2015
Ocean wave energy is one of the high potential renewable energy sources. Due to the recent progre... more Ocean wave energy is one of the high potential renewable energy sources. Due to the recent progresses in the OWEC devices higher power extraction is possible which also brings the need of using multilevel converters to increase the voltage together with power. In this study, adaption of a sophisticated NTV-SV-PWM method to the multilevel converter is proposed, aiming to improve the energy extraction efficiency and the quality of the power transferred to the grid.
The ANPC topology was developed to overcome the unequal power distribution among the semiconducto... more The ANPC topology was developed to overcome the unequal power distribution among the semiconductors in NPC topology. By using an accurate switching model it's possible to adjust the thermal distribution between the semiconductors and increase the output power of the converter. This study focuses on the PWM-3 (fpwm = 350Hz), PWM-5 (fpwm = 550Hz), and PWM-7 (fpwm = 750Hz) and defines the optimum switching sequence for each frequency and specifies the maximum current rating of IGCT based ANPC converter for the mentioned optimum switching sequence.
Iecon 2010 36th Annual Conference on Ieee Industrial Electronics Society, Nov 1, 2010
Abstract-Supplying regulated voltage to critical loads is an important topic for several years. T... more Abstract-Supplying regulated voltage to critical loads is an important topic for several years. This paper presents a single-phase electronic voltage regulator based on high frequency switching of an isolated transformer where primary side voltage is controlled by two full-bridge ...
EPE´19 - European Conference on Power Electronics and Applications, 2019
Insulation and coordination design is one of the most important topics which needs to be consider... more Insulation and coordination design is one of the most important topics which needs to be considered at the beginning stage of a power electronics system design. This tutorial reviews the fundamentals of insulation and coordination and defines the relevant norms, requirements and standards for high power medium voltage power electronics systems. The tutorial is intended to address the design steps to provide required clearance and creepage distances through some examples. This guide covers also the electrical tests and measurements to fulfil the electrical withstand capability for a given medium voltage application example. Finally, the insulation and coordination regulations for medium voltage power electronics systems and the differences between the regulations are presented in the tutorial. The scope of the lecture would be very valuable to those power electronics engineers, mechanical engineers and students from university and industry who face with the design problems of implementing insulation and coordination requirements in their applications and who need a guide to the methods that can be used straight away without performing complex mathematics.
This tutorial is intended to address the EMC problems in the high power medium voltage converters... more This tutorial is intended to address the EMC problems in the high power medium voltage converters and explain the related EMC design steps based on IEC standards. It describes how EMC applies to systems and installations, and also explains proven best EMC practices (implementation of EMC zones, bonding, earthing, when to use filter or shielding, cable layout and cable segregation, preventing grounding loop, routing within the system) in design, assembly and installation to optimize the essential reduction and conform to the standards of electromagnetic compatibility. The tutorial also covers the mechanical instructions when developing new converter design or evaluating existing solutions. The scope of the lecture would be very valuable to those power electronics engineers, mechanical engineers and researchers who are confronted with the practical problems of implementing EMC requirements in their applications and who need a guide to the methods that can be used immediately without performing complex mathematics.
This tutorial is intended to address the EMC problems in the high power medium voltage converters... more This tutorial is intended to address the EMC problems in the high power medium voltage converters and explain the related EMC design steps based on IEC standards. It describes how EMC applies to systems and installations, and also explains proven best EMC practices (implementation of EMC zones, bonding, earthing, when to use filter or shielding, preventing grounding loop, cable layout, segregation, routing within the system) in design, assembly and installation to optimize the essential reduction and conform to the standards of electromagnetic compatibility. The tutorial covers also the mechanical instructions when developing new converter design or evaluating existing solutions. The scope of the lecture would be very valuable to those power electronics engineers, mechanical engineers and students who face with the practical problems of implementing EMC requirements in their applications and who need a guide to the methods that can be used straight away without performing complex mathematics.
Insulation and coordination design is one of the most important topics which needs to be consider... more Insulation and coordination design is one of the most important topics which needs to be considered at the beginning stage of a power electronics system design. This tutorial reviews the fundamentals of insulation and coordination and defines the relevant norms, requirements and standards for high power medium voltage power electronics systems. The tutorial is intended to address the design steps to provide required clearance and creepage distances through some examples. This guide covers also the electrical tests and measurements to fulfil the electrical withstand capability for a given medium voltage application example. Finally, the insulation and coordination regulations for medium voltage power electronics systems and the differences between the regulations are presented in the tutorial. The scope of the lecture would be very valuable to those power electronics engineers, mechanical engineers and students from university and industry who face with the design problems of implementing insulation and coordination requirements in their applications and who need a guide to the methods that can be used straight away without performing complex mathematics.
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Papers by Ilknur Colak
The scope of the lecture would be very valuable to those power electronics engineers, mechanical engineers and students from university and industry who face with the design problems of implementing insulation and coordination requirements in their applications and who need a guide to the methods that can be used straight away without performing complex mathematics.
The scope of the lecture would be very valuable to those power electronics engineers, mechanical engineers and students from university and industry who face with the design problems of implementing insulation and coordination requirements in their applications and who need a guide to the methods that can be used straight away without performing complex mathematics.