EPE Association: EPE 2017 - DS2j: Power Electronics in T&D Systems II

EPE 2017 - DS2j: Power Electronics in T&D Systems II
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 - DS2j: Power Electronics in T&D Systems II

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   A New Analysis for Finding the Optimum Power Rating of Low Voltage Distribution Power Electronics Based on Statistics and Probabilities
By Amin GANJAVI [View]
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Abstract: The continuing trend toward heavier load and high penetration of Distribution Generation (DG) units in low voltage rural distribution feeders requires power electronic-based solution alternatives for voltage regulation purposes. The design of power electronics in terms of size and cost used for feeder voltage regulation is proportional to their KVA ratings. An iterative optimisation algorithm known as Expectation Maximization (EM) is used to identify a powerful probability model known as Gaussian Mixture Model (GMM). This leads to find an optimum KVA rating based on probabilities.

   A simple DC-link balancing controller for a solid-state transformer using cascaded H-bridge rectifiers
By Hyeok Jin YUN [View]
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Abstract: In this paper, a simple voltage balance controller for a SST using cascaded H-bridge rectifiers is proposed to deal with voltage unbalance problem of DC-links. The tolerance of parameters on DC-DC stage, which consists of parallel-connected DAB converters, can cause the unbalance problem of output voltage on H-bridge rectifiers. In order to solve this unbalance problem, an additional voltage balance controller is merged in conventional output voltage PI controller of DAB converter. By using this proposed voltage balance controller, a modified independent phase-shift angle is applied to each DAB converters. Through this process, the voltage of DC-links and power of DAB converters can be balanced. Compared to the conventional voltage balance methods, the proposed balance controller does not require additional current sensor or other devices. The performance of proposed balance controller is verified by experimental results using a 5kW SST prototype.

   Active Harmonic Current Elimination and Reactive Power Compensation using Modular Multilevel Cascaded Converter
By Han HUANG [View]
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Abstract: This paper presents a new application of modular multilevel cascaded converters (MMCC) for combined active harmonic current elimination and reactive power compensation in a power distribution line. A technique for simultaneous extracting harmonic components and reactive element in the load current is presented. A novel voltage control scheme for balancing the module intra-cluster capacitor voltages under distorted load current is incorporated. Simulation studies show the desired performance of the MMCC-based active power conditioning operating under PCC current distortion and varying load conditions.

   Current Progressive Balancing of Three Phase Converter Operating with Unbalanced Grid
By Grzegorz IWANSKI [View]
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Abstract: The paper deals with the current progressive balancing from the target of constant p or constant qcomponent of instantaneous power to symmetrical current target. Referenced current imbalancedepends on the operation mode and whether the current reaches the limit. The fixed p component ofpower is selected for the inverter operation mode. The fixed q component of power is selected for therectifier operation. In both targets, the current is sinusoidal, however unbalanced. It does not providethe maximum possible power transfer available at given voltage imbalance. The maximum power canbe reached at sinusoidal current. Thus in the case in which the current vector length reaches instantlythe maximum value, the current is progressively balanced to increase the value of transferred power.Symmetrical components decomposition based proposed control provides management of the semiminorand semi-major axes of elliptical hodograph of unbalanced

   Design and Control of Modular Multilevel DC Converter (M2DC)
By Yafang LI [View]
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Abstract: DC/DC converters are necessary in HVDC networks to adapt different voltage levels, different configurations or to participate in power flow control. This paper focuses on a recent DC/DC converter topology, called Modular Multilevel DC Converter (M2DC), which uses direct DC/DC connection without galvanic separations. A general analysis of the topology is firstly discussed. Afterwards a decoupled mathematical model, reducing the control complexity is proposed. To improve converter's performances and limit AC constraints on each leg, parameters adjust and inductor sizing are explored. Finally, simulation results are presented to validate the proposed decoupled model and the control. The impact of optimized parameters are shown on AC components values.

   Model Order Reduction for a Full Scale Grid Converter for Grid Simulations
By Malte JOHN [View]
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Abstract: The simulation of transmission and distribution grids comes with a trade-off between the number ofmodeled components and the modeling depth on the one hand and the simulation speed on the otherhand. An example system of a grid converter of a 2MW full scale converter system is used to showa step-by-step model order reduction. Starting from a detailed switched model the order reduction isshown in two steps. First, the well-known averaging method is used to provide a time-continuous modeland a time-continuous approximation of non-linear effects for the low-frequency range, that are usuallylost due to averaging, are included.In a second step the model order reduction is continued based on the analytical equations of the continuoussystem. An order reduction method for linear systems is applied on a linear, time-invariant subsystemof the converter. The application of mathematical order reduction methods on the full average model revealsthe limitation of these methods for the system in view, which stands in contrast to standard orderreduction examples. An outlook is given on the application of advanced order reduction methods.

EPE 2017 - DS2j: Power Electronics in T&D Systems II
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 - DS2j: Power Electronics in T&D Systems II
	[return to parent folder]

	A New Analysis for Finding the Optimum Power Rating of Low Voltage Distribution Power Electronics Based on Statistics and Probabilities By Amin GANJAVI	[View] [Download]
Abstract: The continuing trend toward heavier load and high penetration of Distribution Generation (DG) units in low voltage rural distribution feeders requires power electronic-based solution alternatives for voltage regulation purposes. The design of power electronics in terms of size and cost used for feeder voltage regulation is proportional to their KVA ratings. An iterative optimisation algorithm known as Expectation Maximization (EM) is used to identify a powerful probability model known as Gaussian Mixture Model (GMM). This leads to find an optimum KVA rating based on probabilities.

	A simple DC-link balancing controller for a solid-state transformer using cascaded H-bridge rectifiers By Hyeok Jin YUN	[View] [Download]
Abstract: In this paper, a simple voltage balance controller for a SST using cascaded H-bridge rectifiers is proposed to deal with voltage unbalance problem of DC-links. The tolerance of parameters on DC-DC stage, which consists of parallel-connected DAB converters, can cause the unbalance problem of output voltage on H-bridge rectifiers. In order to solve this unbalance problem, an additional voltage balance controller is merged in conventional output voltage PI controller of DAB converter. By using this proposed voltage balance controller, a modified independent phase-shift angle is applied to each DAB converters. Through this process, the voltage of DC-links and power of DAB converters can be balanced. Compared to the conventional voltage balance methods, the proposed balance controller does not require additional current sensor or other devices. The performance of proposed balance controller is verified by experimental results using a 5kW SST prototype.

	Active Harmonic Current Elimination and Reactive Power Compensation using Modular Multilevel Cascaded Converter By Han HUANG	[View] [Download]
Abstract: This paper presents a new application of modular multilevel cascaded converters (MMCC) for combined active harmonic current elimination and reactive power compensation in a power distribution line. A technique for simultaneous extracting harmonic components and reactive element in the load current is presented. A novel voltage control scheme for balancing the module intra-cluster capacitor voltages under distorted load current is incorporated. Simulation studies show the desired performance of the MMCC-based active power conditioning operating under PCC current distortion and varying load conditions.

	Current Progressive Balancing of Three Phase Converter Operating with Unbalanced Grid By Grzegorz IWANSKI	[View] [Download]
Abstract: The paper deals with the current progressive balancing from the target of constant p or constant qcomponent of instantaneous power to symmetrical current target. Referenced current imbalancedepends on the operation mode and whether the current reaches the limit. The fixed p component ofpower is selected for the inverter operation mode. The fixed q component of power is selected for therectifier operation. In both targets, the current is sinusoidal, however unbalanced. It does not providethe maximum possible power transfer available at given voltage imbalance. The maximum power canbe reached at sinusoidal current. Thus in the case in which the current vector length reaches instantlythe maximum value, the current is progressively balanced to increase the value of transferred power.Symmetrical components decomposition based proposed control provides management of the semiminorand semi-major axes of elliptical hodograph of unbalanced

	Design and Control of Modular Multilevel DC Converter (M2DC) By Yafang LI	[View] [Download]
Abstract: DC/DC converters are necessary in HVDC networks to adapt different voltage levels, different configurations or to participate in power flow control. This paper focuses on a recent DC/DC converter topology, called Modular Multilevel DC Converter (M2DC), which uses direct DC/DC connection without galvanic separations. A general analysis of the topology is firstly discussed. Afterwards a decoupled mathematical model, reducing the control complexity is proposed. To improve converter's performances and limit AC constraints on each leg, parameters adjust and inductor sizing are explored. Finally, simulation results are presented to validate the proposed decoupled model and the control. The impact of optimized parameters are shown on AC components values.

	Model Order Reduction for a Full Scale Grid Converter for Grid Simulations By Malte JOHN	[View] [Download]
Abstract: The simulation of transmission and distribution grids comes with a trade-off between the number ofmodeled components and the modeling depth on the one hand and the simulation speed on the otherhand. An example system of a grid converter of a 2MW full scale converter system is used to showa step-by-step model order reduction. Starting from a detailed switched model the order reduction isshown in two steps. First, the well-known averaging method is used to provide a time-continuous modeland a time-continuous approximation of non-linear effects for the low-frequency range, that are usuallylost due to averaging, are included.In a second step the model order reduction is continued based on the analytical equations of the continuoussystem. An order reduction method for linear systems is applied on a linear, time-invariant subsystemof the converter. The application of mathematical order reduction methods on the full average model revealsthe limitation of these methods for the system in view, which stands in contrast to standard orderreduction examples. An outlook is given on the application of advanced order reduction methods.