EPE Association: EPE 2019 - DS2g: Application of Control Methods

EPE 2019 - DS2g: Application of Control Methods
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2019 ECCE Europe - Conference > EPE 2019 - Topic 03: Measurement and Control > EPE 2019 - DS2g: Application of Control Methods

   [return to parent folder]

   Advantages of Communication in Double Three-Phase Surface Permanent Magnet Machines Fed by Independent Inverters
By Giacomo SALA [View]
[Download]

Abstract: This paper deals with a double three-phase Surface Permanent Magnet (SPM) drive where two independent three-phase inverters are supplying the same electrical machine. This work highlights how the magnetic coupling of the two windings affects the control performance. A new control strategy based on a low bandwidth communication, aiming to improve the performance of the system, is presented and validated by numerical simulations.

   Analysis and Control of DC-link Oscillations of Voltage Source Inverters during Unbalanced Grid Faults
By Hendrik JUST [View]
[Download]

Abstract: The increasing amount of renewable energy sources in power systems requires more stringent rules for the grid connected power converters. Especially the Fault Ride-Through during unbalanced grid faults is critical for the converter and its control. These unbalanced grid faults result in power oscillations, which propagate to the DC-link, leading to double-fundamental-frequency oscillations of the DC-link voltage, affecting the aging of the capacitors and performance of the converter control. Hence, limiting these oscillations is crucial for the reliability and performance of the overall inverter system. To understand the reason why these oscillations occur, this paper derives an analytical model of the DC-link voltage oscillations based on the Instantaneous Power Theory for multiphase AC systems. The model is used to identify the ratio of positive to negative sequence currents as suitable mean to determine the DC-link oscillations during unbalanced grid faults. A control strategy is presented, which sufficiently rejects the DC-link oscillations for all power operation points and fault types. Recent grid codes demand maximum current injection of the inverter to improve the grid voltage support in most applications. This makes it necessary to implement a suitable Peak-Current Limitation. This limitation must guarantee the rejection of DC-link voltage oscillations even in current limitation mode. As opposed to conventional approaches, a positive and negative sequence current vector limitation is proposed. This sufficiently limits the maximum output current and maintains the AC and DC-power oscillation characteristics of the inverter. In summary, the DC-link oscillations are analytically described. The proposed control strategy with a Peak Current Limitation completely rejects the double-fundamental frequency DC-link oscillations during all fault types and operation points. These results are validated in a numerical simulation and an experimental setup under various fault scenarios and operation points.

   Analysis of a Novel Method for Reducing DC Bus Capacitance in the Three-Phase Power Electronic Transformer
By Yao RUIDI [View]
[Download]

Abstract: This paper provides a detailed analysis of a novel method for reducing DC bus capacitance in the three-phase power electronic transformer (PET). In order to further improve power density, a double-frequency power transmission (DFPT) control method is proposed. The voltage fluctuation can be partly reduced by DFPT method but with a certain price. In this paper, on the basis of previous studies, the effects of this method on DAB efficiency, device capacity and stability are studied in detail. Simulation and practical experiments are carried out to verify the analysis results.

   Application of Clustered Multi-port Active-bridge Converters in Micro-grids
By Soleiman GALESHI [View]
[Download]

Abstract: In addition to classical loads and sources, a micro-grid includes local generation and storage devices. An energy system, composed of converters is needed to connect all these objects together and facilitate energy exchange between them. Classical solutions for micro-grids with renewable energy resources, involve multiple energy conversion steps. Due to intermittent nature of renewable resources and fluctuations in consumption profiles, the converters usually work in power levels that are lower than their nominal power and with low efficiency. This paper proposes a cluster of multi-port converters in order to have smart and efficient energy exchanges in micro-grids. Using a cluster of converters, instead of a single one, proposes several advantages including higher efficiency, reliability and flexibility. Moreover, modular clusters of converters connected on different parts of a network, which do both control of the flow energy and current state data exchange, can be regarded as a well-structured hardware-level infrastructure for realization of internet of energy. A study case is simulated to better assess the efficiency gain when using a cluster of converters.

   Current Sharing Method Using Secondary Voltage Ripple for an Interleaved LLC Resonant Converter
By Takae SHIMADA [View]
[Download]

Abstract: A circuit topology and its control for an interleaved LLC resonant converter are proposed. In general, the LLC converter achieves high efficiency, but the ripple current of the output capacitor is large, so a number of interleaving methods for the ripple current cancellation of LLC converters have been proposed. Output of the LLC converter is basically controlled by switching frequency modulation; therefore, the interleaving requires current sharing while operating at the same switching frequency. In the present study, a common LC filter is connected to the rectification outputs of two parallel-connected LLC modules and passively achieves the current sharing by the output voltage ripple of each other's modules. The switching phase difference between the two LLC modules is slightly shifted from 90 degrees for further improvement of the current balance. The proposed method is evaluated by simulation under the condition of a resonant inductances mismatch of the two LLC modules. The simulated results show that the appropriate value of the proposed common filter prevents the current imbalance due to the inductances mismatch.

   Energy Management of isolated DC microgrids with hybrid batteries-hydrogen storage system using Model Predictive Control and Wavelet Neural Networks based forec
By David MORIN [View]
[Download]

Abstract: The intermittency of renewable energy production is still a serious impediment for their development, and thus must be mitigated by efficient energy storages and adapted energy management systems. In this context, a novel control strategy for an islanded microgrid with a hybrid batteries-hydrogen energy storage is proposed. It is a model predictive control which originality lies simultaneously in the objective function formulation that does not focus on economic considerations and the use of wavelet neural network as a forecasts model. In order to validate our approach, three simulations have been done under realistic working conditions, comparing performances of the control with a classical ruled based control, and evaluating its potential for improvement. The results confirm that this method outclasses the ones usually used, but can still be enhanced by improving the forecast model.

   Experimental validation of a novel angular estimator for synthetic inertia support under disturbed network conditions
By Alberto BOLZONI [View]
[Download]

Abstract: This paper proposes a novel estimation scheme for angular quantities extraction under disturbed network conditions; a robust identification of the network angular frequency and of its derivative are crucial for the synthetic inertia provision from grid-connected converters. The newly proposed architecture is derived from the Second Order / Second Order Generalized Integrator scheme (SOSOGI), an algorithm exploited to extract the fundamental harmonic component from phase voltages measurements, with the introduction of an additional decoupling feedback for negative sequence compensation. The effectiveness and robustness of the proposed technique are compared, both analytically and experimentally, with other schemes already available in literature.

   Investigation on a Three-Phase Inverter with LC Output Filter for Machine Emulation
By Manuel FISCHER [View]
[Download]

Abstract: In addition to a real-time operating machine model an applicable power electronic device is required to emulate the electric behavior of machines. Typically, multilevel inverters are utilized for this purpose. This power electronic device comes with the problem of switched-mode operation which leads to additional disturbing ripple content in the output current. In order to damp the negative influence of switched-mode operation, the suitability of a three-phase inverter with LC output filter for use in a power-hardware-in-the-loop machine emulator is analyzed within this paper. At first the setup of this inverter concept is presented. Afterwards, the paper describes a strategy to control the inverter's output voltages achieving machine-emulating behavior. The operation as machine emulator is demonstrated in simulation results, finally.

   Model Predictive Control of an Active Capacitor for Ripple Energy Compensation in Single-Phase DC-to-AC Converters
By Macyln CHINGWENA [View]
[Download]

Abstract: Single-phase dc-to-ac converters produce second-order harmonic currents on the dc side. To reducethis low-frequency ripple current, normally a bulky electrolytic capacitor is used, which contributessignificantly to the increase in size and weight of the overall system. In order to reduce the ripple current and simultaneously reduce the size of the electrolytic capacitor, a dc-to-dc boost converter is employed. The capacitor of the dc-to-dc boost converter, the active capacitor, is used for ripple energy compensation.This paper presents a model predictive control (MPC) strategy of the active capacitor. The dc-to-dcboost converter switches are directly manipulated in order to divert the ripple current to the activecapacitor. To improve the system performance, long prediction horizons are required. However, itbecomes computationally challenging to solve the underlying optimization problem for long prediction horizons. Therefore, a branch-and-bound method is employed along with a move blocking strategy to solve the optimization problem in a practically realizable time. Simulation results are provided to verify the effectiveness of the proposed control strategy.

   New Control Concept for a Safety-critical Actuator in Highly Automated or Autonomous Cars
By Tim BUCHALI [View]
[Download]

Abstract: This paper introduces a new fault-tolerant control concept for a safety-critical actuator in an autonomous car. The system has a robust and flexible architecture that can be reconfigured intelligently after faults in order to provide safe operation and the maximum possible power without causing disturbing torque ripples.

   Novel Five-Level Space Vector Modulation for Parallel Three-Level Inverters with Smaller AC Side Current Ripples and Circulating Current
By Zhang XUEGUANG [View]
[Download]

Abstract: A novel five-level space vector modulation method is proposed for two parallel three-level inverters, which can provide reduced line current distortion, smaller circulating current and less switching transitions. Detailed analysis and implementation process are presented, and the experimental results verify the effectiveness and advantages of the proposed method.

   Repetitive Observer design for torque ripple reduction in PMSM drives
By Mi TANG [View]
[Download]

Abstract: Control strategies aimed at the suppression of periodic disturbance, such as Repetitive Controller (RC) and disturbance observer (DO) have been used in many applications in the past few years. A traditional RC and a conventional DO can be merged into a novel repetitive observer (RO). This paper provides tools to design a RO and proves mathematically that the separation principle used in the DO design is also valid for the RO. The effects of each control parameter on the system performance are also studied and the RO approach is then tested for torque ripple reduction in permanent magnet synchronous machine (PMSM) drives.

EPE 2019 - DS2g: Application of Control Methods
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2019 ECCE Europe - Conference > EPE 2019 - Topic 03: Measurement and Control > EPE 2019 - DS2g: Application of Control Methods
	[return to parent folder]

	Advantages of Communication in Double Three-Phase Surface Permanent Magnet Machines Fed by Independent Inverters By Giacomo SALA	[View] [Download]
Abstract: This paper deals with a double three-phase Surface Permanent Magnet (SPM) drive where two independent three-phase inverters are supplying the same electrical machine. This work highlights how the magnetic coupling of the two windings affects the control performance. A new control strategy based on a low bandwidth communication, aiming to improve the performance of the system, is presented and validated by numerical simulations.

	Analysis and Control of DC-link Oscillations of Voltage Source Inverters during Unbalanced Grid Faults By Hendrik JUST	[View] [Download]
Abstract: The increasing amount of renewable energy sources in power systems requires more stringent rules for the grid connected power converters. Especially the Fault Ride-Through during unbalanced grid faults is critical for the converter and its control. These unbalanced grid faults result in power oscillations, which propagate to the DC-link, leading to double-fundamental-frequency oscillations of the DC-link voltage, affecting the aging of the capacitors and performance of the converter control. Hence, limiting these oscillations is crucial for the reliability and performance of the overall inverter system. To understand the reason why these oscillations occur, this paper derives an analytical model of the DC-link voltage oscillations based on the Instantaneous Power Theory for multiphase AC systems. The model is used to identify the ratio of positive to negative sequence currents as suitable mean to determine the DC-link oscillations during unbalanced grid faults. A control strategy is presented, which sufficiently rejects the DC-link oscillations for all power operation points and fault types. Recent grid codes demand maximum current injection of the inverter to improve the grid voltage support in most applications. This makes it necessary to implement a suitable Peak-Current Limitation. This limitation must guarantee the rejection of DC-link voltage oscillations even in current limitation mode. As opposed to conventional approaches, a positive and negative sequence current vector limitation is proposed. This sufficiently limits the maximum output current and maintains the AC and DC-power oscillation characteristics of the inverter. In summary, the DC-link oscillations are analytically described. The proposed control strategy with a Peak Current Limitation completely rejects the double-fundamental frequency DC-link oscillations during all fault types and operation points. These results are validated in a numerical simulation and an experimental setup under various fault scenarios and operation points.

	Analysis of a Novel Method for Reducing DC Bus Capacitance in the Three-Phase Power Electronic Transformer By Yao RUIDI	[View] [Download]
Abstract: This paper provides a detailed analysis of a novel method for reducing DC bus capacitance in the three-phase power electronic transformer (PET). In order to further improve power density, a double-frequency power transmission (DFPT) control method is proposed. The voltage fluctuation can be partly reduced by DFPT method but with a certain price. In this paper, on the basis of previous studies, the effects of this method on DAB efficiency, device capacity and stability are studied in detail. Simulation and practical experiments are carried out to verify the analysis results.

	Application of Clustered Multi-port Active-bridge Converters in Micro-grids By Soleiman GALESHI	[View] [Download]
Abstract: In addition to classical loads and sources, a micro-grid includes local generation and storage devices. An energy system, composed of converters is needed to connect all these objects together and facilitate energy exchange between them. Classical solutions for micro-grids with renewable energy resources, involve multiple energy conversion steps. Due to intermittent nature of renewable resources and fluctuations in consumption profiles, the converters usually work in power levels that are lower than their nominal power and with low efficiency. This paper proposes a cluster of multi-port converters in order to have smart and efficient energy exchanges in micro-grids. Using a cluster of converters, instead of a single one, proposes several advantages including higher efficiency, reliability and flexibility. Moreover, modular clusters of converters connected on different parts of a network, which do both control of the flow energy and current state data exchange, can be regarded as a well-structured hardware-level infrastructure for realization of internet of energy. A study case is simulated to better assess the efficiency gain when using a cluster of converters.

	Current Sharing Method Using Secondary Voltage Ripple for an Interleaved LLC Resonant Converter By Takae SHIMADA	[View] [Download]
Abstract: A circuit topology and its control for an interleaved LLC resonant converter are proposed. In general, the LLC converter achieves high efficiency, but the ripple current of the output capacitor is large, so a number of interleaving methods for the ripple current cancellation of LLC converters have been proposed. Output of the LLC converter is basically controlled by switching frequency modulation; therefore, the interleaving requires current sharing while operating at the same switching frequency. In the present study, a common LC filter is connected to the rectification outputs of two parallel-connected LLC modules and passively achieves the current sharing by the output voltage ripple of each other's modules. The switching phase difference between the two LLC modules is slightly shifted from 90 degrees for further improvement of the current balance. The proposed method is evaluated by simulation under the condition of a resonant inductances mismatch of the two LLC modules. The simulated results show that the appropriate value of the proposed common filter prevents the current imbalance due to the inductances mismatch.

	Energy Management of isolated DC microgrids with hybrid batteries-hydrogen storage system using Model Predictive Control and Wavelet Neural Networks based forec By David MORIN	[View] [Download]
Abstract: The intermittency of renewable energy production is still a serious impediment for their development, and thus must be mitigated by efficient energy storages and adapted energy management systems. In this context, a novel control strategy for an islanded microgrid with a hybrid batteries-hydrogen energy storage is proposed. It is a model predictive control which originality lies simultaneously in the objective function formulation that does not focus on economic considerations and the use of wavelet neural network as a forecasts model. In order to validate our approach, three simulations have been done under realistic working conditions, comparing performances of the control with a classical ruled based control, and evaluating its potential for improvement. The results confirm that this method outclasses the ones usually used, but can still be enhanced by improving the forecast model.

	Experimental validation of a novel angular estimator for synthetic inertia support under disturbed network conditions By Alberto BOLZONI	[View] [Download]
Abstract: This paper proposes a novel estimation scheme for angular quantities extraction under disturbed network conditions; a robust identification of the network angular frequency and of its derivative are crucial for the synthetic inertia provision from grid-connected converters. The newly proposed architecture is derived from the Second Order / Second Order Generalized Integrator scheme (SOSOGI), an algorithm exploited to extract the fundamental harmonic component from phase voltages measurements, with the introduction of an additional decoupling feedback for negative sequence compensation. The effectiveness and robustness of the proposed technique are compared, both analytically and experimentally, with other schemes already available in literature.

	Investigation on a Three-Phase Inverter with LC Output Filter for Machine Emulation By Manuel FISCHER	[View] [Download]
Abstract: In addition to a real-time operating machine model an applicable power electronic device is required to emulate the electric behavior of machines. Typically, multilevel inverters are utilized for this purpose. This power electronic device comes with the problem of switched-mode operation which leads to additional disturbing ripple content in the output current. In order to damp the negative influence of switched-mode operation, the suitability of a three-phase inverter with LC output filter for use in a power-hardware-in-the-loop machine emulator is analyzed within this paper. At first the setup of this inverter concept is presented. Afterwards, the paper describes a strategy to control the inverter's output voltages achieving machine-emulating behavior. The operation as machine emulator is demonstrated in simulation results, finally.

	Model Predictive Control of an Active Capacitor for Ripple Energy Compensation in Single-Phase DC-to-AC Converters By Macyln CHINGWENA	[View] [Download]
Abstract: Single-phase dc-to-ac converters produce second-order harmonic currents on the dc side. To reducethis low-frequency ripple current, normally a bulky electrolytic capacitor is used, which contributessignificantly to the increase in size and weight of the overall system. In order to reduce the ripple current and simultaneously reduce the size of the electrolytic capacitor, a dc-to-dc boost converter is employed. The capacitor of the dc-to-dc boost converter, the active capacitor, is used for ripple energy compensation.This paper presents a model predictive control (MPC) strategy of the active capacitor. The dc-to-dcboost converter switches are directly manipulated in order to divert the ripple current to the activecapacitor. To improve the system performance, long prediction horizons are required. However, itbecomes computationally challenging to solve the underlying optimization problem for long prediction horizons. Therefore, a branch-and-bound method is employed along with a move blocking strategy to solve the optimization problem in a practically realizable time. Simulation results are provided to verify the effectiveness of the proposed control strategy.

	New Control Concept for a Safety-critical Actuator in Highly Automated or Autonomous Cars By Tim BUCHALI	[View] [Download]
Abstract: This paper introduces a new fault-tolerant control concept for a safety-critical actuator in an autonomous car. The system has a robust and flexible architecture that can be reconfigured intelligently after faults in order to provide safe operation and the maximum possible power without causing disturbing torque ripples.

	Novel Five-Level Space Vector Modulation for Parallel Three-Level Inverters with Smaller AC Side Current Ripples and Circulating Current By Zhang XUEGUANG	[View] [Download]
Abstract: A novel five-level space vector modulation method is proposed for two parallel three-level inverters, which can provide reduced line current distortion, smaller circulating current and less switching transitions. Detailed analysis and implementation process are presented, and the experimental results verify the effectiveness and advantages of the proposed method.

	Repetitive Observer design for torque ripple reduction in PMSM drives By Mi TANG	[View] [Download]
Abstract: Control strategies aimed at the suppression of periodic disturbance, such as Repetitive Controller (RC) and disturbance observer (DO) have been used in many applications in the past few years. A traditional RC and a conventional DO can be merged into a novel repetitive observer (RO). This paper provides tools to design a RO and proves mathematically that the separation principle used in the DO design is also valid for the RO. The effects of each control parameter on the system performance are also studied and the RO approach is then tested for torque ripple reduction in permanent magnet synchronous machine (PMSM) drives.