10th IET International Conference on AC and DC Power Transmission (ACDC 2012), 2012
ABSTRACT It will be important for the operation of future multi-terminal HVDC systems that each c... more ABSTRACT It will be important for the operation of future multi-terminal HVDC systems that each converter unit is capable of limiting the influence of nearby AC faults on the DC grid. Thus, the local control systems at each terminal should be able to prevent double frequency active power oscillations caused by unbalanced AC faults from propagating to the DC-side of the converter. A simple approach for achieving this objective, while ensuring that the converter currents are limited to safe values, is therefore presented in this paper. The proposed method is based on estimation of Positive and Negative Sequence Virtual Flux components at the terminals of the converter. Double frequency oscillations in the active power flow through the converter can therefore be eliminated during unbalanced conditions, without considering the influence of the filter inductors. By preventing power oscillations in the DC system, while keeping the currents within the available rating, the proposed control system will prevent converter tripping and unwanted interruption of system operation.
2012 IEEE Energy Conversion Congress and Exposition (ECCE), 2012
ABSTRACT This study presents a solution for reducing the frequency oscillations in multi-area int... more ABSTRACT This study presents a solution for reducing the frequency oscillations in multi-area interconnected power system by means of using an VSC-HVDC interconnection transmission line. The upcoming power-electronics based HVDC transmission system offers new features that can be advantageous for improving the frequency control and thus for enhancing the stability in transmission networks. This paper is structured in two main parts; the first one is be devoted to introduce the basic elements of HVDC links and the second part will be focused on the effects of the HVDC links in the frequency control of interconnected power systems. In order to show the positive effects of HVDC links under random load disturbance, a model with parallel AC-DC interconnected power system, including a new power modulation controller of bi-directional VSC-HVDC link, is proposed and simulated. Comparisons between HVAC and HVDC transmissions are presented and its performance is evaluated using Matlab/Simulink.
2011 IEEE Energy Conversion Congress and Exposition, 2011
The operation of distributed power generation systems under grid fault conditions is a key issue ... more The operation of distributed power generation systems under grid fault conditions is a key issue for the massive integration of renewable energy systems. Several studies have been conducted to improve the response of such distributed generation systems under voltage dips. In spite of being less severe, unbalanced fault cause a great number of disconnections, as it may produce the injection
10th IET International Conference on AC and DC Power Transmission (ACDC 2012), 2012
ABSTRACT It will be important for the operation of future multi-terminal HVDC systems that each c... more ABSTRACT It will be important for the operation of future multi-terminal HVDC systems that each converter unit is capable of limiting the influence of nearby AC faults on the DC grid. Thus, the local control systems at each terminal should be able to prevent double frequency active power oscillations caused by unbalanced AC faults from propagating to the DC-side of the converter. A simple approach for achieving this objective, while ensuring that the converter currents are limited to safe values, is therefore presented in this paper. The proposed method is based on estimation of Positive and Negative Sequence Virtual Flux components at the terminals of the converter. Double frequency oscillations in the active power flow through the converter can therefore be eliminated during unbalanced conditions, without considering the influence of the filter inductors. By preventing power oscillations in the DC system, while keeping the currents within the available rating, the proposed control system will prevent converter tripping and unwanted interruption of system operation.
2012 IEEE Energy Conversion Congress and Exposition (ECCE), 2012
ABSTRACT This study presents a solution for reducing the frequency oscillations in multi-area int... more ABSTRACT This study presents a solution for reducing the frequency oscillations in multi-area interconnected power system by means of using an VSC-HVDC interconnection transmission line. The upcoming power-electronics based HVDC transmission system offers new features that can be advantageous for improving the frequency control and thus for enhancing the stability in transmission networks. This paper is structured in two main parts; the first one is be devoted to introduce the basic elements of HVDC links and the second part will be focused on the effects of the HVDC links in the frequency control of interconnected power systems. In order to show the positive effects of HVDC links under random load disturbance, a model with parallel AC-DC interconnected power system, including a new power modulation controller of bi-directional VSC-HVDC link, is proposed and simulated. Comparisons between HVAC and HVDC transmissions are presented and its performance is evaluated using Matlab/Simulink.
2011 IEEE Energy Conversion Congress and Exposition, 2011
The operation of distributed power generation systems under grid fault conditions is a key issue ... more The operation of distributed power generation systems under grid fault conditions is a key issue for the massive integration of renewable energy systems. Several studies have been conducted to improve the response of such distributed generation systems under voltage dips. In spite of being less severe, unbalanced fault cause a great number of disconnections, as it may produce the injection
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Papers by Alvaro Luna