EPE Association: EPE 2022 - DS3b: Grid Connected Converters

EPE 2022 - DS3b: Grid Connected Converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2022 ECCE Europe - Conference > EPE 2022 - Topic 02: Power Converter Topologies and Design > EPE 2022 - DS3b: Grid Connected Converters

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   A Novel Modified-TOGI based PLL for the Three-Phase Unbalanced and Distorted Grid Conditions
By Khanh-Hung NGUYEN [View]
[Download]

Abstract: This paper proposes a novel modified third-order generalized integrator phase-locked loop (TOGI-PLL) for balanced, unbalanced, and distorted grid conditions. This technique also eliminates the error factors that cause in experimental such as DC-offset and removing the second-order oscillation noise by adding the low-pass filter when generating the estimated filtered frequency. A step-by-step controller design procedure, system stability analysis, and comparison with the traditional second-order generalized integrator (SOGI), dual second-order generalized integrator (DSOGI), and decoupled double synchronous reference frame PLL (DDSRF-PLL) are carried out. The proposed PLL approach is simulated and experimentally implemented on a three-phase 7.5kW grid-connected inverter system.

   A Simplified Braking Method for Direct Matrix Converter-Fed PMSM Drives with Consideration of Avoiding Regenerative Energy
By Jun XIE [View]
[Download]

Abstract: This paper presents a simplified braking method for direct matrix converter (DMC) - fed permanent magnet synchronous motor (PMSM) drives with special consideration of avoiding the regenerative energy from feeding back to the grid. As a four-quadrant converter, the DMC has the bidirectional energy-flow capability, which is seen as a great benefit. However, the regenerative energy feeding back to the grid is not always needed, in some cases might be not allowed or not possible. These could happen due to the grid load status, strict quality specifications of the grid current or grid failure, where the DMC needs to be decoupled from the grid. In order to avoid the regenerative energy temporarily or completely, a three-phase diode bridge (B6) with chopper resistance on the motor side is employed together with the traditional B12-clamp circuit, which is used for overvoltage protection. Furthermore, the motor torque during braking could be controlled without large fluctuation and within the required limitation. The principle of the proposed strategy is described in detail. Simulation results are used to verify the feasibility of the proposed strategy.

   Analysis and Estimation of Neutral-Point Voltage Balancing Ability of an Optimized Balancing Algorithm for Grid Connected Active-NPC converter
By Joseph Kiran BANDA [View]
[Download]

Abstract: Neutral-point (NP) voltage balancing is a well-known challenge associated with Neutral Point Clamped (NPC) multi-level voltage source converters. Most of the literature on multilevel NPC converters discusses on multiple balancing techniques that are used to nullify dc or ac unbalance and claims the adaptability of these techniques over wide range of modulation indices and power factors. This paper details out the analysis for estimating the maximum balancing ability of an optimized neutral point balancing technique applied on a grid connected 3-Level Active-NPC (ANPC) converter with supporting simulation and experimental results. Also, a simplified analysis to study the impact of grid harmonics on the neutral point potential is presented and validated with the help of simulation results.

   Analysis of the Loss Distribution of a 6 kW two Stage Power Supply for 600 V DC Applications
By Lukas FRÄGER [View]
[Download]

Abstract: This paper presents a two-stage AC/DC power supply consisting of a silicon carbide powersemiconductor based active front end and a dual active bridge DC/DC converter. The paper presents thedesign considerations, efficiency and loss analysis based on measurements. The focus is specially drawnto the influence of the variable DC-link voltage on the overall efficiency and loss distribution amongthe two stages.

   Design of a Robust Voltage Control for Inverters with LC Filter based on the Internal Model Control
By Frederik STALLMANN [View]
[Download]

Abstract: Voltage-controlled inverters with an LC filter are widely used in uninterruptable power supplies anddroop-controlled inverters. However, as inverters usually have an operational lifetime of several years,important plant parameters such as the inductance and capacitance of the LC filter may diminish due to aging. In this paper, deviations in the LC filter parameters and their effect on the stability and robustness of the control are analyzed. An internal model control is designed for the inverter and a robust stability analysis is carried out. Furthermore, different controller designs for increased robustness are discussed and validated by simulations. Finally, the robust internal model control developed, is implemented in an FPGA-based system and used in an experimental setup to investigate the controller performance.

   Experimental Evaluation on Observer-Based Delay-Compensating Active Damping for LC-Filters
By Michael SCHUETT [View]
[Download]

Abstract: This work presents experimental results of a discrete-time observer-based delay-compensating active damping technique for LC filters. This method is state-feedback-based and consequently very robust regarding the system parameter such as the grid impedance. Nonetheless, the limits of this strategy are discussed. The experimental setup is a low voltage representation of a 5 MW wind converter. Much know-how was invested in transferring the electrical conditions from high to low power. Particular mention should be made of the adaptation concerning the naturally slower switches in the high voltage and the compensation of the higher damping of the passive components in the low voltage class.

   Four-Level Boost Inverter Based on ANPC Topology with Switched-Capacitor Branch
By Robert STALA [View]
[Download]

Abstract: This paper presents a novel single-stage four-level inverter with voltage-boosting ability. Incomparison to the cascaded topology, the proposed converter allows for the elimination of a powerchoke on the DC side. The inverter topology and its special switching algorithm are demonstrated andverified by simulations and experiments.

   Measurement results of Multilevel Hysteresis Control for paralleled Two-Level Converters
By Magdalena GIERSCHNER [View]
[Download]

Abstract: The multilevel hysteresis control strategy was adjusted to four paralleled two-level converters. Simulationswere done to compare it with uncoordinated hysteresis control and current control with pulsewidth modulation. Although this novel control strategy has its greatest advantages for several parallelconverters and was originally designed for 14 parallel converters, the results for four converters are stillsignificantly better than state of the art hysteresis cotrol. Furthermore, a test bench with four paralleledconverter was build up to prove the simulation results.

   Neural Networks-Generalized Predictive Control for MIMO Grid-Connected Z-Source Inverter Model
By Herminio MARTINEZ-GARCIA [View]
[Download]

Abstract: This paper presents a neural network-generalized predictive control (NN-GPC) for a single-phase grid-connected z-source inverter. The NN forecasts the predictive horizon, and the conventional GPC algorithm calculates the control horizon. The results verify the proposed NN-GPC effectively enhances the dynamic operation of z-source inverter regarding the non-minimum phase characteristics of these converters.

EPE 2022 - DS3b: Grid Connected Converters
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2022 ECCE Europe - Conference > EPE 2022 - Topic 02: Power Converter Topologies and Design > EPE 2022 - DS3b: Grid Connected Converters
	[return to parent folder]

	A Novel Modified-TOGI based PLL for the Three-Phase Unbalanced and Distorted Grid Conditions By Khanh-Hung NGUYEN	[View] [Download]
Abstract: This paper proposes a novel modified third-order generalized integrator phase-locked loop (TOGI-PLL) for balanced, unbalanced, and distorted grid conditions. This technique also eliminates the error factors that cause in experimental such as DC-offset and removing the second-order oscillation noise by adding the low-pass filter when generating the estimated filtered frequency. A step-by-step controller design procedure, system stability analysis, and comparison with the traditional second-order generalized integrator (SOGI), dual second-order generalized integrator (DSOGI), and decoupled double synchronous reference frame PLL (DDSRF-PLL) are carried out. The proposed PLL approach is simulated and experimentally implemented on a three-phase 7.5kW grid-connected inverter system.

	A Simplified Braking Method for Direct Matrix Converter-Fed PMSM Drives with Consideration of Avoiding Regenerative Energy By Jun XIE	[View] [Download]
Abstract: This paper presents a simplified braking method for direct matrix converter (DMC) - fed permanent magnet synchronous motor (PMSM) drives with special consideration of avoiding the regenerative energy from feeding back to the grid. As a four-quadrant converter, the DMC has the bidirectional energy-flow capability, which is seen as a great benefit. However, the regenerative energy feeding back to the grid is not always needed, in some cases might be not allowed or not possible. These could happen due to the grid load status, strict quality specifications of the grid current or grid failure, where the DMC needs to be decoupled from the grid. In order to avoid the regenerative energy temporarily or completely, a three-phase diode bridge (B6) with chopper resistance on the motor side is employed together with the traditional B12-clamp circuit, which is used for overvoltage protection. Furthermore, the motor torque during braking could be controlled without large fluctuation and within the required limitation. The principle of the proposed strategy is described in detail. Simulation results are used to verify the feasibility of the proposed strategy.

	Analysis and Estimation of Neutral-Point Voltage Balancing Ability of an Optimized Balancing Algorithm for Grid Connected Active-NPC converter By Joseph Kiran BANDA	[View] [Download]
Abstract: Neutral-point (NP) voltage balancing is a well-known challenge associated with Neutral Point Clamped (NPC) multi-level voltage source converters. Most of the literature on multilevel NPC converters discusses on multiple balancing techniques that are used to nullify dc or ac unbalance and claims the adaptability of these techniques over wide range of modulation indices and power factors. This paper details out the analysis for estimating the maximum balancing ability of an optimized neutral point balancing technique applied on a grid connected 3-Level Active-NPC (ANPC) converter with supporting simulation and experimental results. Also, a simplified analysis to study the impact of grid harmonics on the neutral point potential is presented and validated with the help of simulation results.

	Analysis of the Loss Distribution of a 6 kW two Stage Power Supply for 600 V DC Applications By Lukas FRÄGER	[View] [Download]
Abstract: This paper presents a two-stage AC/DC power supply consisting of a silicon carbide powersemiconductor based active front end and a dual active bridge DC/DC converter. The paper presents thedesign considerations, efficiency and loss analysis based on measurements. The focus is specially drawnto the influence of the variable DC-link voltage on the overall efficiency and loss distribution amongthe two stages.

	Design of a Robust Voltage Control for Inverters with LC Filter based on the Internal Model Control By Frederik STALLMANN	[View] [Download]
Abstract: Voltage-controlled inverters with an LC filter are widely used in uninterruptable power supplies anddroop-controlled inverters. However, as inverters usually have an operational lifetime of several years,important plant parameters such as the inductance and capacitance of the LC filter may diminish due to aging. In this paper, deviations in the LC filter parameters and their effect on the stability and robustness of the control are analyzed. An internal model control is designed for the inverter and a robust stability analysis is carried out. Furthermore, different controller designs for increased robustness are discussed and validated by simulations. Finally, the robust internal model control developed, is implemented in an FPGA-based system and used in an experimental setup to investigate the controller performance.

	Experimental Evaluation on Observer-Based Delay-Compensating Active Damping for LC-Filters By Michael SCHUETT	[View] [Download]
Abstract: This work presents experimental results of a discrete-time observer-based delay-compensating active damping technique for LC filters. This method is state-feedback-based and consequently very robust regarding the system parameter such as the grid impedance. Nonetheless, the limits of this strategy are discussed. The experimental setup is a low voltage representation of a 5 MW wind converter. Much know-how was invested in transferring the electrical conditions from high to low power. Particular mention should be made of the adaptation concerning the naturally slower switches in the high voltage and the compensation of the higher damping of the passive components in the low voltage class.

	Four-Level Boost Inverter Based on ANPC Topology with Switched-Capacitor Branch By Robert STALA	[View] [Download]
Abstract: This paper presents a novel single-stage four-level inverter with voltage-boosting ability. Incomparison to the cascaded topology, the proposed converter allows for the elimination of a powerchoke on the DC side. The inverter topology and its special switching algorithm are demonstrated andverified by simulations and experiments.

	Measurement results of Multilevel Hysteresis Control for paralleled Two-Level Converters By Magdalena GIERSCHNER	[View] [Download]
Abstract: The multilevel hysteresis control strategy was adjusted to four paralleled two-level converters. Simulationswere done to compare it with uncoordinated hysteresis control and current control with pulsewidth modulation. Although this novel control strategy has its greatest advantages for several parallelconverters and was originally designed for 14 parallel converters, the results for four converters are stillsignificantly better than state of the art hysteresis cotrol. Furthermore, a test bench with four paralleledconverter was build up to prove the simulation results.

	Neural Networks-Generalized Predictive Control for MIMO Grid-Connected Z-Source Inverter Model By Herminio MARTINEZ-GARCIA	[View] [Download]
Abstract: This paper presents a neural network-generalized predictive control (NN-GPC) for a single-phase grid-connected z-source inverter. The NN forecasts the predictive horizon, and the conventional GPC algorithm calculates the control horizon. The results verify the proposed NN-GPC effectively enhances the dynamic operation of z-source inverter regarding the non-minimum phase characteristics of these converters.