EPE Association: EPE 2011 - LS1d: Topic 06: Converter Control, Current/Voltage Control

EPE 2011 - LS1d: Topic 06: Converter Control, Current/Voltage Control
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2011 ECCE Europe - Conference > EPE 2011 - Topic 06: Modulation Strategies and Specific Control Methods for Static Converters > EPE 2011 - LS1d: Topic 06: Converter Control, Current/Voltage Control

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   Control Scheme for a Single Phase Hybrid Multilevel Converter using Repetitive and Resonant Control Approaches
By Mohamed RASHED, Christian KLUMPNER, Greg ASHER [View]
[Download]

Abstract: Converters for power grid interface are required to operate under abnormal operating conditions such as unbalanced and non-sinusoidal grid voltage waveforms and hence, the multilevel types of converters offer a good solution to achieve high power and high voltage and that modular control consisting of cascaded structures seems the most appropriate solution towards decentralising the control per individual phases as well. This paper investigates the use of the proposed hybrid repetitive-resonant control in a control scheme for a single phase converter designed to interface with power grids of highly distorted voltage waveform. The proposed hybrid repetitive-resonant control is employed into two places of the system to act in one place as a harmonics filter and in the second place as a current controller to provide respectively:- i) high performance extraction of clean and reliable phase angle information and magnitude of the fundamental grid voltage component and ii) control of grid current and the mitigation of harmonics. Grid voltage control is also considered. The Repetitive Controller RPC is known to reject all the harmonics content but with slow dynamics, [25] while the Resonant Controller RSC is faster but rejects only a single frequency component, [16]. Hence, a hybrid RPC/RSC control approach is proposed where the RSC network is tuned at a number of selected low order frequencies and operated in parallel with a full range RPC. The hybrid RPC/RSC control approach is applied to compensate the grid current harmonics and to eliminate the harmonics distortion of the estimated phase angle and magnitude of the fundamental grid voltage component. Detailed modelling and simulation of the proposed control scheme are carried out using PSIM and the results show excellent performance.

   Predictive Control of a Grid-Connected Cascaded H-Bridge Multilevel Converter
By Patricio CORTES, Francisco QUIROZ, Jose RODRIGUEZ [View]
[Download]

Abstract: A predictive control scheme for a three-phase cascaded h-bridge rectifier is presented. The main objectives of this control scheme is to minimize the error between the input active and reactive power and their references, and to balance the dc-link capacitor voltages. These objectives are expressed as a cost function to be minimized. A model of the converter is used for calculation of the predicted value of the controlled variables for a set of switching states. The switching state that minimizes the cost function is selected and applied. In order to reduce the number of calculations needed to select the optimal state, a method for reduction of the evaluated switching states is also proposed.Results show that the proposed control scheme achieves fast control of the active and reactive power and keeps the capacitor voltages balanced.

   The Effects and Models of Different Updating and Sampling Concepts to the Control of Grid-Connected PWM Converters – A Study Based on Discrete Time Domain Analy
By Nils HOFFMANN, Jörg DANNEHL, Friedrich W. FUCHS [View]
[Download]

Abstract: PI-based current control of voltage source pulsewidth-modulation (PWM) converters with L- and LCL-filters is addressed. The design and analysis of these systems require proper system modeling. Computational and sampling delays are most important in this context. Three widely used PWM and sampling concepts are considered: single-update PWM with sampling at the start of the switching period, single-update PWM with sampling in the middle of the switching period, and double-update PWM with updating and sampling twice per switching period. For each, the resulting delay is accurately modeled. Moreover, this paper presents a design method, in all three cases, of a PI-based current-control using discrete-time analysis. The derived models are analyzed by root-locus and step response analysis and thoroughly verified by measurements. Additionally, the impact of updating and sampling strategy on an LCL filter system with different characteristic resonance frequencies is analyzed.

EPE 2011 - LS1d: Topic 06: Converter Control, Current/Voltage Control
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2011 ECCE Europe - Conference > EPE 2011 - Topic 06: Modulation Strategies and Specific Control Methods for Static Converters > EPE 2011 - LS1d: Topic 06: Converter Control, Current/Voltage Control
	[return to parent folder]

	Control Scheme for a Single Phase Hybrid Multilevel Converter using Repetitive and Resonant Control Approaches By Mohamed RASHED, Christian KLUMPNER, Greg ASHER	[View] [Download]
Abstract: Converters for power grid interface are required to operate under abnormal operating conditions such as unbalanced and non-sinusoidal grid voltage waveforms and hence, the multilevel types of converters offer a good solution to achieve high power and high voltage and that modular control consisting of cascaded structures seems the most appropriate solution towards decentralising the control per individual phases as well. This paper investigates the use of the proposed hybrid repetitive-resonant control in a control scheme for a single phase converter designed to interface with power grids of highly distorted voltage waveform. The proposed hybrid repetitive-resonant control is employed into two places of the system to act in one place as a harmonics filter and in the second place as a current controller to provide respectively:- i) high performance extraction of clean and reliable phase angle information and magnitude of the fundamental grid voltage component and ii) control of grid current and the mitigation of harmonics. Grid voltage control is also considered. The Repetitive Controller RPC is known to reject all the harmonics content but with slow dynamics, [25] while the Resonant Controller RSC is faster but rejects only a single frequency component, [16]. Hence, a hybrid RPC/RSC control approach is proposed where the RSC network is tuned at a number of selected low order frequencies and operated in parallel with a full range RPC. The hybrid RPC/RSC control approach is applied to compensate the grid current harmonics and to eliminate the harmonics distortion of the estimated phase angle and magnitude of the fundamental grid voltage component. Detailed modelling and simulation of the proposed control scheme are carried out using PSIM and the results show excellent performance.

	Predictive Control of a Grid-Connected Cascaded H-Bridge Multilevel Converter By Patricio CORTES, Francisco QUIROZ, Jose RODRIGUEZ	[View] [Download]
Abstract: A predictive control scheme for a three-phase cascaded h-bridge rectifier is presented. The main objectives of this control scheme is to minimize the error between the input active and reactive power and their references, and to balance the dc-link capacitor voltages. These objectives are expressed as a cost function to be minimized. A model of the converter is used for calculation of the predicted value of the controlled variables for a set of switching states. The switching state that minimizes the cost function is selected and applied. In order to reduce the number of calculations needed to select the optimal state, a method for reduction of the evaluated switching states is also proposed.Results show that the proposed control scheme achieves fast control of the active and reactive power and keeps the capacitor voltages balanced.

	The Effects and Models of Different Updating and Sampling Concepts to the Control of Grid-Connected PWM Converters – A Study Based on Discrete Time Domain Analy By Nils HOFFMANN, Jörg DANNEHL, Friedrich W. FUCHS	[View] [Download]
Abstract: PI-based current control of voltage source pulsewidth-modulation (PWM) converters with L- and LCL-filters is addressed. The design and analysis of these systems require proper system modeling. Computational and sampling delays are most important in this context. Three widely used PWM and sampling concepts are considered: single-update PWM with sampling at the start of the switching period, single-update PWM with sampling in the middle of the switching period, and double-update PWM with updating and sampling twice per switching period. For each, the resulting delay is accurately modeled. Moreover, this paper presents a design method, in all three cases, of a PI-based current-control using discrete-time analysis. The derived models are analyzed by root-locus and step response analysis and thoroughly verified by measurements. Additionally, the impact of updating and sampling strategy on an LCL filter system with different characteristic resonance frequencies is analyzed.