The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Hans-peter Nee - One of the best experts on this subject based on the ideXlab platform.
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Modeling and control of VSC-HVDC links connected to island Systems
IEEE Transactions on Power Systems, 2011Co-Authors: Lidong Zhang, Lennart Harnefors, Hans-peter NeeAbstract:The recently proposed power-synchronization control for grid-connected voltage-source converters (VSCs) has been shown to be a feasible solution for high-voltage direct-current (HVDC) transmission connected to high-impedance weak Ac Systems. In this paper, power-synchronization control is investigated for VSC-HVDC links connected to another type of weak Ac System, i.e., low-inertia or island Systems. As an example, a linear model of a typical island System feeding by a VSC-HVDC link, including a synchronous generator, an induction motor, and some passive loads, is developed for tuning the control parameters of the VSC-HVDC link. Time simulations in PSCAD/EMTDC demonstrate that VSC-HVDC Systems using power-synchronization control are flexible for various network conditions, such as large-Ac-System connection, island Systems, or passive networks. The time simulations also show that power-synchronization control can seamlessly handle transitions between operation modes, as well as ride through Ac-System faults in all network conditions.
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power synchronization control of grid connected voltage source converters
IEEE Transactions on Power Systems, 2010Co-Authors: Lidong Zhang, Lennart Harnefors, Hans-peter NeeAbstract:In this paper, a novel control method of grid-connected voltage-source converters (VSCs) is proposed. The method can be generally applied for all grid-connected VSCs but may be of most importance in high-voltage dc (HVDC) applications. Different from the previous control methods, the proposed method utilizes the internal synchronization mechanism in Ac Systems, in principle, similar to the operation of a synchronous mAchine. By using this type of power-synchronization control, the VSC avoids the instability caused by a standard phase-locked loop in a weak Ac-System connection. Moreover, a VSC terminal can give the weak Ac System strong voltage support, just like a normal synchronous mAchine does. The control method is verified by both analytical models and time simulations.
Balarko Chaudhuri - One of the best experts on this subject based on the ideXlab platform.
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System frequency support through multi terminal dc mtdc grids
Power and Energy Society General Meeting, 2013Co-Authors: Nilanjan Ray Chaudhuri, Rajat Majumder, Balarko ChaudhuriAbstract:Summary form only given. Control of the converter stations in a multi-terminal DC (MTDC) grid to provide frequency support for the surrounding Ac Systems is the subject matter of this paper. The standard autonomous power sharing control loop for eAch converter is modified with a frequency droop control loop. The objective is to minimize the deviation from nominal Ac System frequency and share the burden of frequency support among the converter stations of the MTDC grid. The effectiveness of the frequency support is demonstrated through nonlinear simulation of a test System consisting of three isolated Ac Systems interconnected through an MTDC grid with four converter stations. An averaged model of the MTDC grids is developed to carry out modal analysis of combined multi-mAchine Ac-MTDC Systems. Modal analysis is used to charActerize and substantiate the time domain behavior in presence of frequency droop control. It is established that appropriate droop control loop for the MTDC grid converters could be effective in reducing the deviation from nominal Ac System frequency provided the sensitivity of the System eigen-values to changes in control parameters (e.g., droop coefficients) is Accounted for a priori through modal analysis.
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System frequency support through multi terminal dc mtdc grids
IEEE Transactions on Power Systems, 2013Co-Authors: Nilanjan Ray Chaudhuri, Rajat Majumder, Balarko ChaudhuriAbstract:Control of the converter stations in a multi-terminal DC (MTDC) grid to provide frequency support for the surrounding Ac Systems is the subject matter of this paper. The standard autonomous power sharing control loop for eAch converter is modified with a frequency droop control loop. The objective is to minimize the deviation from nominal Ac System frequency and share the burden of frequency support among the converter stations of the MTDC grid. The effectiveness of the frequency support is demonstrated through nonlinear simulation of a test System consisting of three isolated Ac Systems interconnected through an MTDC grid with four converter stations. An averaged model of the MTDC grids is developed to carry out modal analysis of combined multi-mAchine Ac-MTDC Systems. Modal analysis is used to charActerize and substantiate the time domain behavior in presence of frequency droop control. It is established that appropriate droop control loop for the MTDC grid converters could be effective in reducing the deviation from nominal Ac System frequency provided the sensitivity of the System eigen-values to changes in control parameters (e.g., droop coefficients) is Accounted for a priori through modal analysis.
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Stability Analysis of VSC MTDC Grids Connected to MultimAchine Ac Systems
IEEE Transactions on Power Delivery, 2011Co-Authors: Nilanjan Ray Chaudhuri, Rajat Majumder, Balarko ChaudhuriAbstract:InterAction between multimAchine Ac Systems and a multiterminal dc (MTDC) grid and the impAct on the overall stability of the combined Ac-MTDC System is studied in this paper. A generic modeling framework for voltage-source converter (VSC)-based MTDC grids, which is compatible with standard multimAchine Ac System models, is developed to carry out modal analysis and transient simulation. A general asymmetric bipole converter configuration comprising positive and negative pole converters and dc cable network with a positive, negative, and metallic return circuit is considered to enable different types of faults and dc-side unbalance studies. Detailed dynamic representation of the dc cables with distributed pi-section models is used along with the averaged model and decoupled control for the converter stations. An averaged model in Matlab/SIMULINK is validated against the detailed switched model in EMTDC/PSCAD by comparing the responses following small and large disturbances (e.g., faults on the dc side). Modal analysis is performed to identify the nature and root cause of the dynamic responses. InterAction between a multimAchine Ac System and an MTDC grid is examined following faults on the Ac and dc sides and outage of converters. It is shown that the cause of instability in certain cases could only be attributed to the dc-side state variables. An averaged model of the converter along with the dc cable network is shown to be essential to analyze the stability and dynamics of combined Ac-MTDC grids.
Lidong Zhang - One of the best experts on this subject based on the ideXlab platform.
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Modeling and control of VSC-HVDC links connected to island Systems
IEEE Transactions on Power Systems, 2011Co-Authors: Lidong Zhang, Lennart Harnefors, Hans-peter NeeAbstract:The recently proposed power-synchronization control for grid-connected voltage-source converters (VSCs) has been shown to be a feasible solution for high-voltage direct-current (HVDC) transmission connected to high-impedance weak Ac Systems. In this paper, power-synchronization control is investigated for VSC-HVDC links connected to another type of weak Ac System, i.e., low-inertia or island Systems. As an example, a linear model of a typical island System feeding by a VSC-HVDC link, including a synchronous generator, an induction motor, and some passive loads, is developed for tuning the control parameters of the VSC-HVDC link. Time simulations in PSCAD/EMTDC demonstrate that VSC-HVDC Systems using power-synchronization control are flexible for various network conditions, such as large-Ac-System connection, island Systems, or passive networks. The time simulations also show that power-synchronization control can seamlessly handle transitions between operation modes, as well as ride through Ac-System faults in all network conditions.
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power synchronization control of grid connected voltage source converters
IEEE Transactions on Power Systems, 2010Co-Authors: Lidong Zhang, Lennart Harnefors, Hans-peter NeeAbstract:In this paper, a novel control method of grid-connected voltage-source converters (VSCs) is proposed. The method can be generally applied for all grid-connected VSCs but may be of most importance in high-voltage dc (HVDC) applications. Different from the previous control methods, the proposed method utilizes the internal synchronization mechanism in Ac Systems, in principle, similar to the operation of a synchronous mAchine. By using this type of power-synchronization control, the VSC avoids the instability caused by a standard phase-locked loop in a weak Ac-System connection. Moreover, a VSC terminal can give the weak Ac System strong voltage support, just like a normal synchronous mAchine does. The control method is verified by both analytical models and time simulations.
Reza Iravani - One of the best experts on this subject based on the ideXlab platform.
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An Enhanced DC Voltage Droop-Control for the VSC--HVDC Grid
IEEE Transactions on Power Systems, 2017Co-Authors: Chongru Liu, Reza IravaniAbstract:This paper introduces an enhanced droop-based dc-voltage control method, including dead-band, for applications to the high-voltage direct-current (HVDC) grid that utilizes the voltage-sourced converter (VSC) technology. The proposed droop-control structure also autonomously imposes energy balance between the HVDC grid and its host Ac System. The droop-control method (1) divides the VSC stations into four groups, (2) Activates the droop-control of eAch group based on a prespecified voltage margin, and (3) introduces an improved power-voltage charActeristic for desirable VSC station dynamic performance. Feasibility and performance of the proposed control method are evaluated based on time-domain simulation studies in the PSCAD platform, using the IEEE-39-Bus System that imbeds a five-terminal VSC–HVDC grid. EAch VSC station is a monopolar modular multilevel converter (MMC). The study results show that the proposed droop-control method enables the HVDC-Ac System to reAch a new steady state after transient events.
Nilanjan Ray Chaudhuri - One of the best experts on this subject based on the ideXlab platform.
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System frequency support through multi terminal dc mtdc grids
Power and Energy Society General Meeting, 2013Co-Authors: Nilanjan Ray Chaudhuri, Rajat Majumder, Balarko ChaudhuriAbstract:Summary form only given. Control of the converter stations in a multi-terminal DC (MTDC) grid to provide frequency support for the surrounding Ac Systems is the subject matter of this paper. The standard autonomous power sharing control loop for eAch converter is modified with a frequency droop control loop. The objective is to minimize the deviation from nominal Ac System frequency and share the burden of frequency support among the converter stations of the MTDC grid. The effectiveness of the frequency support is demonstrated through nonlinear simulation of a test System consisting of three isolated Ac Systems interconnected through an MTDC grid with four converter stations. An averaged model of the MTDC grids is developed to carry out modal analysis of combined multi-mAchine Ac-MTDC Systems. Modal analysis is used to charActerize and substantiate the time domain behavior in presence of frequency droop control. It is established that appropriate droop control loop for the MTDC grid converters could be effective in reducing the deviation from nominal Ac System frequency provided the sensitivity of the System eigen-values to changes in control parameters (e.g., droop coefficients) is Accounted for a priori through modal analysis.
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System frequency support through multi terminal dc mtdc grids
IEEE Transactions on Power Systems, 2013Co-Authors: Nilanjan Ray Chaudhuri, Rajat Majumder, Balarko ChaudhuriAbstract:Control of the converter stations in a multi-terminal DC (MTDC) grid to provide frequency support for the surrounding Ac Systems is the subject matter of this paper. The standard autonomous power sharing control loop for eAch converter is modified with a frequency droop control loop. The objective is to minimize the deviation from nominal Ac System frequency and share the burden of frequency support among the converter stations of the MTDC grid. The effectiveness of the frequency support is demonstrated through nonlinear simulation of a test System consisting of three isolated Ac Systems interconnected through an MTDC grid with four converter stations. An averaged model of the MTDC grids is developed to carry out modal analysis of combined multi-mAchine Ac-MTDC Systems. Modal analysis is used to charActerize and substantiate the time domain behavior in presence of frequency droop control. It is established that appropriate droop control loop for the MTDC grid converters could be effective in reducing the deviation from nominal Ac System frequency provided the sensitivity of the System eigen-values to changes in control parameters (e.g., droop coefficients) is Accounted for a priori through modal analysis.
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Stability Analysis of VSC MTDC Grids Connected to MultimAchine Ac Systems
IEEE Transactions on Power Delivery, 2011Co-Authors: Nilanjan Ray Chaudhuri, Rajat Majumder, Balarko ChaudhuriAbstract:InterAction between multimAchine Ac Systems and a multiterminal dc (MTDC) grid and the impAct on the overall stability of the combined Ac-MTDC System is studied in this paper. A generic modeling framework for voltage-source converter (VSC)-based MTDC grids, which is compatible with standard multimAchine Ac System models, is developed to carry out modal analysis and transient simulation. A general asymmetric bipole converter configuration comprising positive and negative pole converters and dc cable network with a positive, negative, and metallic return circuit is considered to enable different types of faults and dc-side unbalance studies. Detailed dynamic representation of the dc cables with distributed pi-section models is used along with the averaged model and decoupled control for the converter stations. An averaged model in Matlab/SIMULINK is validated against the detailed switched model in EMTDC/PSCAD by comparing the responses following small and large disturbances (e.g., faults on the dc side). Modal analysis is performed to identify the nature and root cause of the dynamic responses. InterAction between a multimAchine Ac System and an MTDC grid is examined following faults on the Ac and dc sides and outage of converters. It is shown that the cause of instability in certain cases could only be attributed to the dc-side state variables. An averaged model of the converter along with the dc cable network is shown to be essential to analyze the stability and dynamics of combined Ac-MTDC grids.
