DSpace Collection:
http://hdl.handle.net/2117/3834
Sun, 21 Dec 2014 11:31:45 GMT
20141221T11:31:45Z
webmaster.bupc@upc.edu
Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació
no

SiC modular multilevel converters: submodule voltage ripple analysis and efficiency estimations
http://hdl.handle.net/2117/24867
Title: SiC modular multilevel converters: submodule voltage ripple analysis and efficiency estimations
Authors: Perez Basante, Angel; Pou Félix, Josep; Ceballos Recio, Salvador; Gil De Muro, Asier; Pujana, Ainhoa; Ibañez, Pedro
Abstract: Two important technical challenges associated with the Modular Multilevel Converter (MMC) are the reduction of the voltage ripple of the SubModule (SM) capacitors and the reduction of the converter losses. This paper conducts a study focused on these two topics. Firstly, the effect of a circulating current with a predefined second harmonic on the SM voltage ripple is assessed. Secondly, an efficiency study for two different MMCs, one with silicon (Si) and the other with silicon carbide (SiC) devices is carried out. Results suggest that a SiC MMC converter with a circulating current including a second harmonic represent a good solution since it achieves a reduction of the SM capacitors together with a high efficiency operation.
Thu, 27 Nov 2014 12:04:46 GMT
http://hdl.handle.net/2117/24867
20141127T12:04:46Z
Perez Basante, Angel; Pou Félix, Josep; Ceballos Recio, Salvador; Gil De Muro, Asier; Pujana, Ainhoa; Ibañez, Pedro
no
Engineering controlled terms: Capacitors, Efficiency, Electric converters, Energy management, Intelligent robots, Power electronics
Two important technical challenges associated with the Modular Multilevel Converter (MMC) are the reduction of the voltage ripple of the SubModule (SM) capacitors and the reduction of the converter losses. This paper conducts a study focused on these two topics. Firstly, the effect of a circulating current with a predefined second harmonic on the SM voltage ripple is assessed. Secondly, an efficiency study for two different MMCs, one with silicon (Si) and the other with silicon carbide (SiC) devices is carried out. Results suggest that a SiC MMC converter with a circulating current including a second harmonic represent a good solution since it achieves a reduction of the SM capacitors together with a high efficiency operation.

Varying and unequal carrier frequency PWM techniques for modular multilevel converters
http://hdl.handle.net/2117/24865
Title: Varying and unequal carrier frequency PWM techniques for modular multilevel converters
Authors: Konstantinou, Georgios; Darus, Rosheila; Pou Félix, Josep; Ceballos Recio, Salvador; Agelidis, Vassilios
Abstract: Carrierbased pulsewidth modulation (PWM) strategies are commonly applied to modular multilevel converters (MMC). This paper proposes a modified PWM technique with unequal and varying carrier frequencies between consecutive levels. The variation between two consecutive carriers is calculated in order to maintain a constant average switching frequency regardless of modulation index and number of levels in the output. The proposed method effectively shifts the major harmonic content of output waveforms to higher frequencies at the cost of a slight increase in low order harmonics. Details on the derivation of the carrier frequencies as well as simulation and experimental results of the proposed method demonstrate the viability of the method as an alternative modulation technique for the MMC.
Thu, 27 Nov 2014 11:44:49 GMT
http://hdl.handle.net/2117/24865
20141127T11:44:49Z
Konstantinou, Georgios; Darus, Rosheila; Pou Félix, Josep; Ceballos Recio, Salvador; Agelidis, Vassilios
no
carrier frequency, modular multilevel converter, multilevel converters, Pulsewidth modulation
Carrierbased pulsewidth modulation (PWM) strategies are commonly applied to modular multilevel converters (MMC). This paper proposes a modified PWM technique with unequal and varying carrier frequencies between consecutive levels. The variation between two consecutive carriers is calculated in order to maintain a constant average switching frequency regardless of modulation index and number of levels in the output. The proposed method effectively shifts the major harmonic content of output waveforms to higher frequencies at the cost of a slight increase in low order harmonics. Details on the derivation of the carrier frequencies as well as simulation and experimental results of the proposed method demonstrate the viability of the method as an alternative modulation technique for the MMC.

Comparison of phaseshifted and levelshifted PWM in the modular multilevel converter
http://hdl.handle.net/2117/24595
Title: Comparison of phaseshifted and levelshifted PWM in the modular multilevel converter
Authors: Darus, Rosheila; Konstantinou, Georgios; Pou Félix, Josep; Ceballos Recio, Salvador; Agelidis, Vassilios
Abstract: This paper reports a comparison study of different carrierbased PWM techniques applied to the modular multilevel converter. Phasedisposition PWM (PDPWM) and phaseshifted pulsewidth modulation (PSPWM) with noninterleaving and interleaving are considered in this study. In PSPWM, two cases are evaluated. In the first case, the particular SMs that have to be activated/deactivated are defined by a voltage balancing algorithm, which is the same one implemented in PDPWM. In addition, an algorithm to restrict the number of switching SMs is also implemented to reduce the switching frequency of the power devices. In the other case of PSPWM, each submodule (SM) has a carrier signal associated to it and capacitor voltage balance is achieved by individual control of its capacitor voltage. The circulating current is controlled to be a dc component in all the cases. Simulation and experimental results are presented to evaluate the quality of the linetoline output voltages and SM capacitor voltage ripples for the different cases under study. © 2014 IEEE.
Fri, 07 Nov 2014 10:53:48 GMT
http://hdl.handle.net/2117/24595
20141107T10:53:48Z
Darus, Rosheila; Konstantinou, Georgios; Pou Félix, Josep; Ceballos Recio, Salvador; Agelidis, Vassilios
no
Capacitor voltage balancing, Circulating current control, Modular multilevel converter, Modulation technique
This paper reports a comparison study of different carrierbased PWM techniques applied to the modular multilevel converter. Phasedisposition PWM (PDPWM) and phaseshifted pulsewidth modulation (PSPWM) with noninterleaving and interleaving are considered in this study. In PSPWM, two cases are evaluated. In the first case, the particular SMs that have to be activated/deactivated are defined by a voltage balancing algorithm, which is the same one implemented in PDPWM. In addition, an algorithm to restrict the number of switching SMs is also implemented to reduce the switching frequency of the power devices. In the other case of PSPWM, each submodule (SM) has a carrier signal associated to it and capacitor voltage balance is achieved by individual control of its capacitor voltage. The circulating current is controlled to be a dc component in all the cases. Simulation and experimental results are presented to evaluate the quality of the linetoline output voltages and SM capacitor voltage ripples for the different cases under study. © 2014 IEEE.

A modified voltage balancing sorting algorithm for the modular multilevel converter: Evaluation for staircase and phasedisposition PWM
http://hdl.handle.net/2117/23161
Title: A modified voltage balancing sorting algorithm for the modular multilevel converter: Evaluation for staircase and phasedisposition PWM
Authors: Darus, Rosheila; Pou Félix, Josep; Konstantinou, Georgios; Ceballos Recio, Salvador; Agelidis, Vassilios
Abstract: This paper introduces a low complexity implementation of the voltage balancing sorting algorithm to reduce the switching frequency of the power devices in modular multilevel converters (MMCs). Two modulation techniques are evaluated; staircase modulation and phasedisposition pulsewidth modulation (PDPWM) under the conventional and the proposed algorithm. Using a circulating current controller in an MMC with 12 submodules per arm, PDPWM yields better results compared to the staircase modulation technique. The test condition for this comparison is such that the power devices operate at a similar switching frequency and produce similar amplitudes to the capacitor voltage ripples in both modulation techniques. The results are verified through extensive simulations and experimentally using a phaseleg MMC laboratory prototype.
Thu, 05 Jun 2014 09:20:58 GMT
http://hdl.handle.net/2117/23161
20140605T09:20:58Z
Darus, Rosheila; Pou Félix, Josep; Konstantinou, Georgios; Ceballos Recio, Salvador; Agelidis, Vassilios
no
Capacitor voltage balancing, Modular multilevel converter, Modulation technique, Pulsewidth modulation
This paper introduces a low complexity implementation of the voltage balancing sorting algorithm to reduce the switching frequency of the power devices in modular multilevel converters (MMCs). Two modulation techniques are evaluated; staircase modulation and phasedisposition pulsewidth modulation (PDPWM) under the conventional and the proposed algorithm. Using a circulating current controller in an MMC with 12 submodules per arm, PDPWM yields better results compared to the staircase modulation technique. The test condition for this comparison is such that the power devices operate at a similar switching frequency and produce similar amplitudes to the capacitor voltage ripples in both modulation techniques. The results are verified through extensive simulations and experimentally using a phaseleg MMC laboratory prototype.

Operators to calculate the derivative of digital signals
http://hdl.handle.net/2117/22001
Title: Operators to calculate the derivative of digital signals
Authors: Ferrer Arnau, Luis Jorge; Mon González, Juan; Parisi Baradad, Vicenç
Abstract: This paper presents an FIR operator with a very low computational cost for calculating the first derivative of discrete bandlimited signals. The basic idea is to use cubic spline polynomials for interpolating
among the samples and estimate the derivative of the discrete signal as a derivative of the polynomial. This method also allows estimating the derivative at the points between samples. The main contribution of this work is to develop a highly efficient FIR operator with only 9 coefficients for implementing the derivative operator algorithm. The resulting filter can be easily implemented in a microcontroller or an FPGA since only 5 additions and 3 fixedpoint multiplications are necessary. If the frequency range of the input signal is between 0 and 0.2 times the sampling frequency (taking 5 samples per cycle), the maximum error in calculating the derivative does not exceed 1.03 %.
Wed, 12 Mar 2014 11:22:00 GMT
http://hdl.handle.net/2117/22001
20140312T11:22:00Z
Ferrer Arnau, Luis Jorge; Mon González, Juan; Parisi Baradad, Vicenç
no
First derivative operator, cubic Bsplines, FIR filters, low computational cost, detecting singular points of a discrete signal, DA conversion
This paper presents an FIR operator with a very low computational cost for calculating the first derivative of discrete bandlimited signals. The basic idea is to use cubic spline polynomials for interpolating
among the samples and estimate the derivative of the discrete signal as a derivative of the polynomial. This method also allows estimating the derivative at the points between samples. The main contribution of this work is to develop a highly efficient FIR operator with only 9 coefficients for implementing the derivative operator algorithm. The resulting filter can be easily implemented in a microcontroller or an FPGA since only 5 additions and 3 fixedpoint multiplications are necessary. If the frequency range of the input signal is between 0 and 0.2 times the sampling frequency (taking 5 samples per cycle), the maximum error in calculating the derivative does not exceed 1.03 %.

Decimator filter based on Bsplines
http://hdl.handle.net/2117/21852
Title: Decimator filter based on Bsplines
Authors: Ferrer Arnau, Luis Jorge; Roset Juan, Francesc Xavier; Mon González, Juan; Parisi Baradad, Vicenç
Abstract: The cascaded integratorcomb (CIC) filters are widely used as decimators in many applications, such
as in delta sigma AD converters to decimate the sampled signal on its output. One problem with these filters is that by increasing its order to improve the signal attenuation in the stop band, worsens the passband response. In this paper we propose a socalled leastsquares filters (LSF) based on Bsplines to improve that response, compensating for CIC filter drop and flattening the magnitude response of the pass band. We also study the relationship between the CIC filters, otherwise called moving average, and the Bsplines expanded by an integer factor. We show that the leastsquares filters based on Bsplines can be decomposed in CIC filters, with a higher order than the splines used, plus a compensator filter. Another important contribution of this work are the FIR approximations of anticausal IIR filters needed to implement LSFs.
Tue, 04 Mar 2014 16:18:35 GMT
http://hdl.handle.net/2117/21852
20140304T16:18:35Z
Ferrer Arnau, Luis Jorge; Roset Juan, Francesc Xavier; Mon González, Juan; Parisi Baradad, Vicenç
no
Decimator filters, Cubic Bsplines, Least squares filters, Cascaded integratorcomb filters, AD Sigma delta converters
The cascaded integratorcomb (CIC) filters are widely used as decimators in many applications, such
as in delta sigma AD converters to decimate the sampled signal on its output. One problem with these filters is that by increasing its order to improve the signal attenuation in the stop band, worsens the passband response. In this paper we propose a socalled leastsquares filters (LSF) based on Bsplines to improve that response, compensating for CIC filter drop and flattening the magnitude response of the pass band. We also study the relationship between the CIC filters, otherwise called moving average, and the Bsplines expanded by an integer factor. We show that the leastsquares filters based on Bsplines can be decomposed in CIC filters, with a higher order than the splines used, plus a compensator filter. Another important contribution of this work are the FIR approximations of anticausal IIR filters needed to implement LSFs.

A new method to improve the total efficiency of parallel converters
http://hdl.handle.net/2117/21717
Title: A new method to improve the total efficiency of parallel converters
Authors: Hoff Dupont, Fabrício; Zaragoza Bertomeu, Jordi; Rech, Cassiano; Pinheiro, José Renes
Abstract: This paper proposes a new methodology for
efficiency optimization in systems composed by parallel
converters. The proposed methodology takes into account
the individual efficiency curves and determines the
optimum operating point for each converter such that
the maximum efficiency of the arrangement is achieved
for the entire load range. Due to the nonlinearity of the
problem and the complexity of the solution hyperplane,
the optimization process is divided into stages of global
optimization, local optimization and ambiguity resolutio
n.
This latter verifies the existence of multiple global
minima and selects the most appropriate in function of
previous power distributions. Case studies demonstrates
the validity of the proposed methodology for different
systems configurations.
Mon, 24 Feb 2014 10:41:24 GMT
http://hdl.handle.net/2117/21717
20140224T10:41:24Z
Hoff Dupont, Fabrício; Zaragoza Bertomeu, Jordi; Rech, Cassiano; Pinheiro, José Renes
no
Parallel converters
supervisory control
efficiency maximization
photovoltaic systems
This paper proposes a new methodology for
efficiency optimization in systems composed by parallel
converters. The proposed methodology takes into account
the individual efficiency curves and determines the
optimum operating point for each converter such that
the maximum efficiency of the arrangement is achieved
for the entire load range. Due to the nonlinearity of the
problem and the complexity of the solution hyperplane,
the optimization process is divided into stages of global
optimization, local optimization and ambiguity resolutio
n.
This latter verifies the existence of multiple global
minima and selects the most appropriate in function of
previous power distributions. Case studies demonstrates
the validity of the proposed methodology for different
systems configurations.

A simple control strategy to increase the total efficiency of multiconverter systems
http://hdl.handle.net/2117/21712
Title: A simple control strategy to increase the total efficiency of multiconverter systems
Authors: Hoff Dupont, Fabrício; Zaragoza Bertomeu, Jordi; Rech, Cassiano; Pinheiro, José Renes
Abstract: This paper presents a simple control
strategy that is employed together with an optimization
methodology to achieve optimal efficiency in systems
composed by multiple parallel converters. An external
loop is responsible for regulating the dc bus voltage
and providing a current reference that is weighted in
function of the power processed by the system, and then
generating optimal current references for each converter.
This enable the system to operate with optimal efficiency
for all its load range. Experimental results demonstrate th
e
superior performance of the proposed strategy, improving
the efficiency of the system in almost
10
% under light load
operation in comparison with the conventional strategy of
equal power sharing among converters
Mon, 24 Feb 2014 09:57:49 GMT
http://hdl.handle.net/2117/21712
20140224T09:57:49Z
Hoff Dupont, Fabrício; Zaragoza Bertomeu, Jordi; Rech, Cassiano; Pinheiro, José Renes
no
Parallel converters, digital control
efficiency maximization
supervisory control
active
current sharing
photovoltaic systems
This paper presents a simple control
strategy that is employed together with an optimization
methodology to achieve optimal efficiency in systems
composed by multiple parallel converters. An external
loop is responsible for regulating the dc bus voltage
and providing a current reference that is weighted in
function of the power processed by the system, and then
generating optimal current references for each converter.
This enable the system to operate with optimal efficiency
for all its load range. Experimental results demonstrate th
e
superior performance of the proposed strategy, improving
the efficiency of the system in almost
10
% under light load
operation in comparison with the conventional strategy of
equal power sharing among converters

Analysis of a voltage balancing technique with reduced switching transitions in a flying capacitor multilevel converter
http://hdl.handle.net/2117/21711
Title: Analysis of a voltage balancing technique with reduced switching transitions in a flying capacitor multilevel converter
Authors: Ghias, Amer M.Y.M.; Pou Félix, Josep; Agelidis, Vassilios; Ciobotaru, M.
Abstract: This paper reports the analysis of a voltage balancing technique based on optimal switching transitions for a flying capacitor (FC) multilevel converter using phase disposition pulsewidth modulation. Since multiple switching transitions between two consecutive voltage levels may be available, such a redundancy is used to regulate the FC voltages at their desired levels. For the selection of the transitions, two techniques are studied and compared in terms of capacitor voltage ripples and switching frequencies. In the first technique, called optimum transition voltage balancing technique, the transitions between two consecutive voltage levels that produce high switching frequencies are avoided. On the other hand, all the transitions between consecutive levels are considered in the second technique. It is therefore called unrestricted voltage balancing technique. Study analyses are conducted by simulation considering all the possible modulation indices and load power factors.
Mon, 24 Feb 2014 09:39:05 GMT
http://hdl.handle.net/2117/21711
20140224T09:39:05Z
Ghias, Amer M.Y.M.; Pou Félix, Josep; Agelidis, Vassilios; Ciobotaru, M.
no
Flying capacitor converter
Multilevel converter
Pulsewidth modulation
Switching transition
Voltage control
This paper reports the analysis of a voltage balancing technique based on optimal switching transitions for a flying capacitor (FC) multilevel converter using phase disposition pulsewidth modulation. Since multiple switching transitions between two consecutive voltage levels may be available, such a redundancy is used to regulate the FC voltages at their desired levels. For the selection of the transitions, two techniques are studied and compared in terms of capacitor voltage ripples and switching frequencies. In the first technique, called optimum transition voltage balancing technique, the transitions between two consecutive voltage levels that produce high switching frequencies are avoided. On the other hand, all the transitions between consecutive levels are considered in the second technique. It is therefore called unrestricted voltage balancing technique. Study analyses are conducted by simulation considering all the possible modulation indices and load power factors.

Positive and negativesequence control of gridconnected photovoltaic systems under unbalanced voltage conditions
http://hdl.handle.net/2117/21710
Title: Positive and negativesequence control of gridconnected photovoltaic systems under unbalanced voltage conditions
Authors: Mirhosseini, Mitra; Pou Félix, Josep; Karanayil, Baburaj; Agelidis, Vassilios
Abstract: This paper discusses the control of the positive and negativesequence components of a largescale gridconnected photovoltaic system (GCPS) under unbalanced voltage sag conditions in the grid. Some issues regarding stability and dynamic performance of the system occur when applying PI controllers in the current control loops. The reason is the delay that the filtering method imposes when extracting the current/voltage sequences. Because of such a delay, the dynamic response of the system becomes slower compared with the case when no filtering technique is needed. Furthermore, there is a strong restriction on choosing suitable parameters for the current/voltage loop controllers without compromising system stability. All these issues are discussed in this paper on a 1MVA GCPV system using MATLAB/Simulink software.
Mon, 24 Feb 2014 09:16:51 GMT
http://hdl.handle.net/2117/21710
20140224T09:16:51Z
Mirhosseini, Mitra; Pou Félix, Josep; Karanayil, Baburaj; Agelidis, Vassilios
no
Moving average filter
Photovoltaic system
Power system dynamics
Power system faults
This paper discusses the control of the positive and negativesequence components of a largescale gridconnected photovoltaic system (GCPS) under unbalanced voltage sag conditions in the grid. Some issues regarding stability and dynamic performance of the system occur when applying PI controllers in the current control loops. The reason is the delay that the filtering method imposes when extracting the current/voltage sequences. Because of such a delay, the dynamic response of the system becomes slower compared with the case when no filtering technique is needed. Furthermore, there is a strong restriction on choosing suitable parameters for the current/voltage loop controllers without compromising system stability. All these issues are discussed in this paper on a 1MVA GCPV system using MATLAB/Simulink software.

Characterization of conducted emission at high frequency under different temperature
http://hdl.handle.net/2117/21690
Title: Characterization of conducted emission at high frequency under different temperature
Authors: Berbel Artal, Néstor; Fernández García, Raúl; Gil Galí, Ignacio
Abstract: Download Citation
Email
Print
Request Permissions
Save to Project
In this paper, the characterization of the EMC conducted emissions of integrated circuits under different temperature stress condition, up to 3 GHz is presented. The impact of high temperature has been measured on the input impedance of propagation paths of the electromagnetic conducted emissions, as well as on the electromagnetic noise of a clock generator.
Fri, 21 Feb 2014 13:00:35 GMT
http://hdl.handle.net/2117/21690
20140221T13:00:35Z
Berbel Artal, Néstor; Fernández García, Raúl; Gil Galí, Ignacio
no
EMC, Integrated circuit, conducted emission, switching noise, temperature impact
Download Citation
Email
Print
Request Permissions
Save to Project
In this paper, the characterization of the EMC conducted emissions of integrated circuits under different temperature stress condition, up to 3 GHz is presented. The impact of high temperature has been measured on the input impedance of propagation paths of the electromagnetic conducted emissions, as well as on the electromagnetic noise of a clock generator.

PWM algorithm with adaptive offset for threelevel multiphase neutralpointclamped converters
http://hdl.handle.net/2117/21364
Title: PWM algorithm with adaptive offset for threelevel multiphase neutralpointclamped converters
Authors: López, Iraide; Ceballos Recio, Salvador; Andreu, Jon; Kortabarria, Iñigo; Pou Félix, Josep
Abstract: This paper proposes a PWM based modulation strategy particularly useful for threelevel multiphase NeutralPointClamped Converters. It achieves similar results to those obtained with the space vector modulation but allowing a very fast and simple implementation in a digital controller. The proposed algorithm is able to maintain the neutralpoint voltage under control by the addition of a zerosequence voltage component to the modulation signals. A simple and efficient methodology to calculate the most appropriate zerosequence component is described. In addition the modulation strategy is completely general, regardless the number of phases of the converter, and therefore it is easy extendible to nphase converters.
Mon, 27 Jan 2014 08:17:56 GMT
http://hdl.handle.net/2117/21364
20140127T08:17:56Z
López, Iraide; Ceballos Recio, Salvador; Andreu, Jon; Kortabarria, Iñigo; Pou Félix, Josep
no
This paper proposes a PWM based modulation strategy particularly useful for threelevel multiphase NeutralPointClamped Converters. It achieves similar results to those obtained with the space vector modulation but allowing a very fast and simple implementation in a digital controller. The proposed algorithm is able to maintain the neutralpoint voltage under control by the addition of a zerosequence voltage component to the modulation signals. A simple and efficient methodology to calculate the most appropriate zerosequence component is described. In addition the modulation strategy is completely general, regardless the number of phases of the converter, and therefore it is easy extendible to nphase converters.

Interleaved selective harmonic elimination PWM for singlephase rectifiers in traction applications
http://hdl.handle.net/2117/21363
Title: Interleaved selective harmonic elimination PWM for singlephase rectifiers in traction applications
Authors: Konstantinou, Georgios; Agelidis, Vassilios; Pou Félix, Josep
Abstract: Interleaved fourquadrant, singlephase rectifiers are widely used in traction applications as part of an ACDCAC conversion system. This paper presents selective harmonic elimination pulsewidth modulation (SHEPWM) patterns for singlephase interleaved PWM rectifiers based on both Hbridges and fullbridge NPCs (HNPCs). SHEPWM waveforms are defined so that the loworder harmonics of the combined voltage and input currents on the primary of the supply transformer are eliminated. The formulation of the problem and the acquisition of solutions becomes more challenging as the number of levels in the voltage waveform increases. Solutions based on reduced eliminated harmonics are proposed in order to increase the number of solutions as well as their continuity. It is shown that the proposed formulation improves the available solution space with minimal effect to the output. The theoretical analysis are verified through simulation studies.
Mon, 27 Jan 2014 08:10:24 GMT
http://hdl.handle.net/2117/21363
20140127T08:10:24Z
Konstantinou, Georgios; Agelidis, Vassilios; Pou Félix, Josep
no
Interleaved converters, multilevel converters, pulsewidth modulation (PWM), PWM rectifiers, selective harmonic
elimination (SHE), traction applications
Interleaved fourquadrant, singlephase rectifiers are widely used in traction applications as part of an ACDCAC conversion system. This paper presents selective harmonic elimination pulsewidth modulation (SHEPWM) patterns for singlephase interleaved PWM rectifiers based on both Hbridges and fullbridge NPCs (HNPCs). SHEPWM waveforms are defined so that the loworder harmonics of the combined voltage and input currents on the primary of the supply transformer are eliminated. The formulation of the problem and the acquisition of solutions becomes more challenging as the number of levels in the voltage waveform increases. Solutions based on reduced eliminated harmonics are proposed in order to increase the number of solutions as well as their continuity. It is shown that the proposed formulation improves the available solution space with minimal effect to the output. The theoretical analysis are verified through simulation studies.

Singlestage inverterbased gridconnected photovoltaic system with ridethrough capability over different types of grid faults
http://hdl.handle.net/2117/21358
Title: Singlestage inverterbased gridconnected photovoltaic system with ridethrough capability over different types of grid faults
Authors: Mirhosseini, Mitra; Pou Félix, Josep; Agelidis, Vassilios
Abstract: In this paper the control of a singlestage gridconnected photovoltaic power plant (GCPPP) is developed to address the issue of inverter disconnection under various grid faults. There are three main reasons for inverter disconnection which are (i) excessive dclink voltage, (ii) excessive ac currents and (iii) loss of gridvoltage synchronization. The control of the inverter incorporates reactive power support in the case of voltage sags based on grid code requirements to ridethrough the faults and support the grid voltages. Accordingly, another requirement of the grid codes is to control the reactive current injection under unbalanced voltage sags so that the voltages in the nonfaulty phases do not exceed the specified limitations. All these issues are discussed in this paper for a case study of 1MVA GCPPP using MATLAB/Simulink. The results illustrate the capability of the developed GCPPP to ridethrough different types of faults occurred on the grid side.
Fri, 24 Jan 2014 11:36:54 GMT
http://hdl.handle.net/2117/21358
20140124T11:36:54Z
Mirhosseini, Mitra; Pou Félix, Josep; Agelidis, Vassilios
no
Faultridethrough, Largescale systems, Photovoltaic systems, Power system faults, Reactive power support
In this paper the control of a singlestage gridconnected photovoltaic power plant (GCPPP) is developed to address the issue of inverter disconnection under various grid faults. There are three main reasons for inverter disconnection which are (i) excessive dclink voltage, (ii) excessive ac currents and (iii) loss of gridvoltage synchronization. The control of the inverter incorporates reactive power support in the case of voltage sags based on grid code requirements to ridethrough the faults and support the grid voltages. Accordingly, another requirement of the grid codes is to control the reactive current injection under unbalanced voltage sags so that the voltages in the nonfaulty phases do not exceed the specified limitations. All these issues are discussed in this paper for a case study of 1MVA GCPPP using MATLAB/Simulink. The results illustrate the capability of the developed GCPPP to ridethrough different types of faults occurred on the grid side.

Voltage balancing method for a sevenlevel stacked multicell converter using minimumswitching transitions
http://hdl.handle.net/2117/21357
Title: Voltage balancing method for a sevenlevel stacked multicell converter using minimumswitching transitions
Authors: Ghias, Amer M.Y.M.; Pou Félix, Josep; Agelidis, Vassilios; Ciobotaru, Mihai
Abstract: This paper presents a voltage balancing method for stacked multicell converters based on phase disposition pulsewidth modulation. This method is based on minimizing a cost function to determine the optimum redundant state for capacitor voltage balance for each particular voltage level. The robustness of the proposed voltage balancing method is verified against static and dynamic unbalanced load conditions. Furthermore, a significant reduction in the switching frequencies of the power devices is achieved by using sawtooth carriers instead of standard triangular carriers without affecting the voltage balancing capability.
Fri, 24 Jan 2014 11:21:50 GMT
http://hdl.handle.net/2117/21357
20140124T11:21:50Z
Ghias, Amer M.Y.M.; Pou Félix, Josep; Agelidis, Vassilios; Ciobotaru, Mihai
no
Multilevel converter, Stacked multicell converter, Capacitor voltage balancing, Pulsewidth modulation.
This paper presents a voltage balancing method for stacked multicell converters based on phase disposition pulsewidth modulation. This method is based on minimizing a cost function to determine the optimum redundant state for capacitor voltage balance for each particular voltage level. The robustness of the proposed voltage balancing method is verified against static and dynamic unbalanced load conditions. Furthermore, a significant reduction in the switching frequencies of the power devices is achieved by using sawtooth carriers instead of standard triangular carriers without affecting the voltage balancing capability.