EPE Association: EPE 2017 - DS3k: Power Quality Issues

EPE 2017 - DS3k: Power Quality Issues
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2017 ECCE Europe - Conference > EPE 2017 - Topic 06: Grids and Smart Grids > EPE 2017 - DS3k: Power Quality Issues

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   A Lyapunov Approach Based Higher Order Sliding Mode Controller for Grid Connected Shunt Active Compensators with a LCL Filter
By Mohamad Alaaeddin ALALI [View]
[Download]

Abstract: A Lyapunov approach based homogeneous higher order SM-Controller (HOSMC) is considered here, for grid connected three phases three wires shunt active filter (SAF) via LCL filter. This nonlinear controller is an alternative solution to overcome phase shift caused by a linear controller and a chattering effect caused by a 1st order sliding mode controller that is supposed to be of relative degree 1. The last fact requires a special sliding variable design that yields asymptotic convergence of the tracking error to zero versus a finite time convergence provided by HOSMC. On the other hand, it is well known that VSI based SAFs compensate for the main types of current perturbations in the electrical power systems, while generate some undesired components caused by switching frequency. In order to avoid the spreading of these components to the grid side, a VSI connected to the grid via a LCL output filter is largely proposed, but for renewable energy systems, where the component to be injected into the grid is only the fundamental. Unfortunately, when the currents to be generated by SAF include both fundamental and harmonics, and for a LCL output filter associated to linear controllers, a phase shift appears, between the identified harmonics current and the injected current, and impacts negatively, harmonic current filtration of the SAF.In this article, a PWM-HOSMC is proposed to operate in a fixed frequency without chattering, preventing a variable switching frequency effects. In addition, this article proposes a solution for the non-robustness drawback, from disturbances point of view, of the used control method. The rapidity, tracking and effectiveness of this proposed controller, within the SAF, are validated by simulations carried out by Matlab, Simulink, Simscape-SimPower System code.

   A network-wide harmonic predictive control method for SAPF based on online harmonic impedance measurement
By Zhai HAO [View]
[Download]

Abstract: Shunt active power filters (SAPF) generally compensate harmonic current of centralized non-linearloads, which may cause undesired economical burden for networks with distributed harmonic sources.This paper proposed an SAPF predictive control method based on online impedance measurementwhich can suppress the network-wide harmonics systematically in an optimized way.

   A New Control Scheme for Harmonic Power Sharing and PCC Voltage Harmonics Compensation Based on Controlling the Equivalent Harmonic Impedance of DGs in Islanded
By Zhirong ZENG [View]
[Download]

Abstract: Harmonic power sharing and PCC voltage quality are both important issues for the power quality of islanded microgrids. This paper proposes a new control scheme to deal with those two issues based on controlling the equivalent harmonic impedance of DGs. With the proposed control scheme, harmonic power is shared according to remaining power capacities of DGs and PCC voltage harmonics are effectively compensated. Simulation results verify the effectiveness of the proposed control scheme.

   Analytical Model of EMI Sources on the Network Level Including Power Electronic Converters
By Achour ALES [View]
[Download]

Abstract: Since studies are intended to be used to predict the compliance with electromagnetic standards, an accurate computing of both common and differential mode conducted noise is necessary. Nowadays, modern networks -as car's network supplying many electrical actuators- include many power converters to manage efficiently power transfer, as well as a long cable (conductors), which creates new issues (e.g. interaction between cable and converter's noise sources). Hence, the ElectroMagnetic Compatibility 'EMC' study becomes more complex. For this reason, in this paper we propose an analytical model to compute noise sources generating conducted signals within the network, at any site (all along the cable). Firstly, noise sources modelling the EMC behaviour of converters connected to the DC-network, are extracted and identified in both frequency and time domains. As a result, converter's electric equations modelling its behaviour are performed by defining a mathematical switching function. The model is assessed with time domain simulations and validated by experimental measurements. Secondly, the extracted converter's model, based on equivalent noise sources, is used to predict the conducted noise inside a defined network, at any location of the cable (network). The process of the network's modelling is done by using the Transmission Line theory (TL) of lossless bifilar lines. This network's model is crucial for EMC analysis, to evaluate the interaction degree between both noise sources and cable parameters. Finally, the network's model is tested by a time domain simulation (LTSpice), and validated by an experimental setup.

   Method for DC-Link Voltage Balancing for a Grid-Connected Inverter in Case of Asymmetric Operation
By Patricio CORTES [View]
[Download]

Abstract: A grid-connected inverter with energy storage and active DC-link voltage balancer circuit is presented. The system is implemented with two identical 100kW three-phase converters. The operating limits of the system under asymmetric grid currents with the given hardware architecture are considered and solutions for symmetrisation of the DC-link are proposed.

   Reduction of voltage and power oscillation in the two-phase shorting of a grid inverter
By Wojciech JARZYNA [View]
[Download]

Abstract: The paper examines the work of the microgenerator inverter during two-phase short circuits. It has been shown that the cause of the oscillation is incorrect synchronization of the inverter. It has been demonstrated that the reduction of the oscillations can be achieved by adapting the synchronization signal to the representation of unbalanced system voltages.

   The compensator of voltage sage/swell installed in connection terminals of small industrial plant or selected loads
By Pawel SZCZESNIAK [View]
[Download]

Abstract: This paper presents the concept of a compensator of voltage sage/swell installed in connection terminals of small industrial plant or selected loads. This compensator based on a three-phase hybrid transformer with matrix converter. Presented in this paper is an approach for obtaining continuous control of the voltage magnitude and phase shift using a conventional transformer with two windings and power electronics converter, referred to as a matrix converter. By adjustment of these voltage parameters we can reduce the effects of overvoltage and voltage sags. Proposition of a close loop control algorithm are discussed in this paper.

   WAVELET TRANSFORM FOR VOLTAGE DIPS DETECTION IN A MICROGRID WITH DISTRIBUTED GENERATION
By Vladimir KATIC [View]
[Download]

Abstract: The paper examines application of wavelet transform for voltage dips detection in microgrids withdistributed generation. IEEE13 test grid with added 1.6 MW distribution generators is used forevaluation. Distribution generators are two 0.8 MW doubly-fed induction generators. Matlab/Simulinkenvironment is used for modelling and evaluation of proposed algorithm for voltage dips detection.Six types of fault are examined and conclusions are derived. As a further confirmation of the obtainedresults, authors utilized the existing laboratory setup at the Faculty of Technical Sciences, in order toget as realistic as possible voltage dips signals from the grid, recorded over distribution transformer(small scale distribution transformer). Voltage dips are produced with grid emulator. These signals arethen used for emulation, and analyzed with different wavelet methods. In paper is shown that waveletis not appropriate solution as part of control of distribution generator grid-tie inverter in order to fastdetect voltage dips, if the measurement is performed in place of inverter. None of the wavelets whenusing highest frequency band can't detect voltage dips fast and accurate at this spot in the grid.Solution to this problem can be to use signals that are measured at the connection point of thegenerators to the grid.

EPE 2017 - DS3k: Power Quality Issues
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2017 ECCE Europe - Conference > EPE 2017 - Topic 06: Grids and Smart Grids > EPE 2017 - DS3k: Power Quality Issues
	[return to parent folder]

	A Lyapunov Approach Based Higher Order Sliding Mode Controller for Grid Connected Shunt Active Compensators with a LCL Filter By Mohamad Alaaeddin ALALI	[View] [Download]
Abstract: A Lyapunov approach based homogeneous higher order SM-Controller (HOSMC) is considered here, for grid connected three phases three wires shunt active filter (SAF) via LCL filter. This nonlinear controller is an alternative solution to overcome phase shift caused by a linear controller and a chattering effect caused by a 1st order sliding mode controller that is supposed to be of relative degree 1. The last fact requires a special sliding variable design that yields asymptotic convergence of the tracking error to zero versus a finite time convergence provided by HOSMC. On the other hand, it is well known that VSI based SAFs compensate for the main types of current perturbations in the electrical power systems, while generate some undesired components caused by switching frequency. In order to avoid the spreading of these components to the grid side, a VSI connected to the grid via a LCL output filter is largely proposed, but for renewable energy systems, where the component to be injected into the grid is only the fundamental. Unfortunately, when the currents to be generated by SAF include both fundamental and harmonics, and for a LCL output filter associated to linear controllers, a phase shift appears, between the identified harmonics current and the injected current, and impacts negatively, harmonic current filtration of the SAF.In this article, a PWM-HOSMC is proposed to operate in a fixed frequency without chattering, preventing a variable switching frequency effects. In addition, this article proposes a solution for the non-robustness drawback, from disturbances point of view, of the used control method. The rapidity, tracking and effectiveness of this proposed controller, within the SAF, are validated by simulations carried out by Matlab, Simulink, Simscape-SimPower System code.

	A network-wide harmonic predictive control method for SAPF based on online harmonic impedance measurement By Zhai HAO	[View] [Download]
Abstract: Shunt active power filters (SAPF) generally compensate harmonic current of centralized non-linearloads, which may cause undesired economical burden for networks with distributed harmonic sources.This paper proposed an SAPF predictive control method based on online impedance measurementwhich can suppress the network-wide harmonics systematically in an optimized way.

	A New Control Scheme for Harmonic Power Sharing and PCC Voltage Harmonics Compensation Based on Controlling the Equivalent Harmonic Impedance of DGs in Islanded By Zhirong ZENG	[View] [Download]
Abstract: Harmonic power sharing and PCC voltage quality are both important issues for the power quality of islanded microgrids. This paper proposes a new control scheme to deal with those two issues based on controlling the equivalent harmonic impedance of DGs. With the proposed control scheme, harmonic power is shared according to remaining power capacities of DGs and PCC voltage harmonics are effectively compensated. Simulation results verify the effectiveness of the proposed control scheme.

	Analytical Model of EMI Sources on the Network Level Including Power Electronic Converters By Achour ALES	[View] [Download]
Abstract: Since studies are intended to be used to predict the compliance with electromagnetic standards, an accurate computing of both common and differential mode conducted noise is necessary. Nowadays, modern networks -as car's network supplying many electrical actuators- include many power converters to manage efficiently power transfer, as well as a long cable (conductors), which creates new issues (e.g. interaction between cable and converter's noise sources). Hence, the ElectroMagnetic Compatibility 'EMC' study becomes more complex. For this reason, in this paper we propose an analytical model to compute noise sources generating conducted signals within the network, at any site (all along the cable). Firstly, noise sources modelling the EMC behaviour of converters connected to the DC-network, are extracted and identified in both frequency and time domains. As a result, converter's electric equations modelling its behaviour are performed by defining a mathematical switching function. The model is assessed with time domain simulations and validated by experimental measurements. Secondly, the extracted converter's model, based on equivalent noise sources, is used to predict the conducted noise inside a defined network, at any location of the cable (network). The process of the network's modelling is done by using the Transmission Line theory (TL) of lossless bifilar lines. This network's model is crucial for EMC analysis, to evaluate the interaction degree between both noise sources and cable parameters. Finally, the network's model is tested by a time domain simulation (LTSpice), and validated by an experimental setup.

	Method for DC-Link Voltage Balancing for a Grid-Connected Inverter in Case of Asymmetric Operation By Patricio CORTES	[View] [Download]
Abstract: A grid-connected inverter with energy storage and active DC-link voltage balancer circuit is presented. The system is implemented with two identical 100kW three-phase converters. The operating limits of the system under asymmetric grid currents with the given hardware architecture are considered and solutions for symmetrisation of the DC-link are proposed.

	Reduction of voltage and power oscillation in the two-phase shorting of a grid inverter By Wojciech JARZYNA	[View] [Download]
Abstract: The paper examines the work of the microgenerator inverter during two-phase short circuits. It has been shown that the cause of the oscillation is incorrect synchronization of the inverter. It has been demonstrated that the reduction of the oscillations can be achieved by adapting the synchronization signal to the representation of unbalanced system voltages.

	The compensator of voltage sage/swell installed in connection terminals of small industrial plant or selected loads By Pawel SZCZESNIAK	[View] [Download]
Abstract: This paper presents the concept of a compensator of voltage sage/swell installed in connection terminals of small industrial plant or selected loads. This compensator based on a three-phase hybrid transformer with matrix converter. Presented in this paper is an approach for obtaining continuous control of the voltage magnitude and phase shift using a conventional transformer with two windings and power electronics converter, referred to as a matrix converter. By adjustment of these voltage parameters we can reduce the effects of overvoltage and voltage sags. Proposition of a close loop control algorithm are discussed in this paper.

	WAVELET TRANSFORM FOR VOLTAGE DIPS DETECTION IN A MICROGRID WITH DISTRIBUTED GENERATION By Vladimir KATIC	[View] [Download]
Abstract: The paper examines application of wavelet transform for voltage dips detection in microgrids withdistributed generation. IEEE13 test grid with added 1.6 MW distribution generators is used forevaluation. Distribution generators are two 0.8 MW doubly-fed induction generators. Matlab/Simulinkenvironment is used for modelling and evaluation of proposed algorithm for voltage dips detection.Six types of fault are examined and conclusions are derived. As a further confirmation of the obtainedresults, authors utilized the existing laboratory setup at the Faculty of Technical Sciences, in order toget as realistic as possible voltage dips signals from the grid, recorded over distribution transformer(small scale distribution transformer). Voltage dips are produced with grid emulator. These signals arethen used for emulation, and analyzed with different wavelet methods. In paper is shown that waveletis not appropriate solution as part of control of distribution generator grid-tie inverter in order to fastdetect voltage dips, if the measurement is performed in place of inverter. None of the wavelets whenusing highest frequency band can't detect voltage dips fast and accurate at this spot in the grid.Solution to this problem can be to use signals that are measured at the connection point of thegenerators to the grid.