scholarly journals Research on the Voltage Interaction of Multi-Infeed HVDC System and Interaction Factor

2015 ◽  
Vol 03 (04) ◽  
pp. 41-48
Author(s):  
Shengjun Zhou ◽  
Guangyao Qiao ◽  
Chuan He ◽  
Wenhui Wang ◽  
Tianqi Liu
Keyword(s):  
Hvdc System ◽  
Interaction Factor

scholarly journals A Method of Demarcating Critical Failure Impedance Boundary of Multi-Infeed HVDC Systems Based on Minimum Extinction Angle

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Song Zhang ◽  
Guoqing Li ◽  
Shuguang Li ◽  
Xintong Liu
Keyword(s):  
Impedance Boundary ◽  
Hvdc System ◽  
High Voltage Direct Current ◽  
Extinction Angle ◽  
Double Phase ◽  
Interaction Factor ◽  
Three Phase ◽  
Calculation Results ◽  
Nodal Voltage ◽  
Bus System

A method of rapidly demarcating the critical commutation failure (CF) region of a multi-infeed high-voltage direct-current (HVDC) system is proposed. Based on the nodal impedance matrix and nodal voltage interaction factor, for different AC fault conditions—both balanced and unbalanced—a method of calculating the extinction angles of converters in multi-infeed HVDC systems is deduced in detail. First, the extinction angles of convertor stations under single-phase, double-phase, and three-phase ground faults and line-to-line faults occurring at any bus in an AC system are calculated. The minimum extinction angle serves as a CF criterion. If the calculated extinction angle for a certain bus is smaller than the minimum extinction angle, then a fault at that bus will cause CF of the HVDC system and put that bus into a failed bus set. The critical failure impedance boundaries of the topology diagram can therefore be demarcated by examining every bus in the AC system. The validity and accuracy of the proposed index and the method were verified by calculation results based on the three-infeed HVDC system model of the IEEE 39-bus system. Finally, the critical failure impedance boundary was demarcated in the IEEE 118-bus system to demonstrate the application in a wider range of systems.

Anticoagulants of primary haemostasis

2009 ◽  
Vol 29 (03) ◽  
pp. 274-278 ◽  
Author(s):  
U. Steigerwald ◽  
U. Walter ◽  
J. Kössler
Keyword(s):  
Experimental Studies ◽  
Antiplatelet Agents ◽  
Bleeding Risk ◽  
Factor Xii ◽  
Receptor Antagonists ◽  
Thromboxane Receptor ◽  
Adenosine Uptake ◽  
Interaction Factor ◽  
Favorable Clinical Outcome ◽  
Adp Receptor Antagonists

SummaryInhibition of platelet function plays an important role in the treatment and secondary prevention of cardiovascular or cerebrovascular ischemic diseases. Established antiplatelet agents use different pharmacological targets for this role. Acetylic salicylic acid achieves a reduction of thromboxane A2 formation by inhibition of COX-1. Ticlopidin or clopidogrel are ADP-P2Y12 receptor antagonists. Tirofiban, abciximab or eptifibatid are used for the inhibition of the glycoprotein IIb/IIIa receptor which is activated at the surface of platelets preceding the final step of their aggregation. The mechanism of dipyridamole is based on the inhibition of adenosine uptake and of phosphodiesterase-5.Efforts are made to improve antiplatetelet therapy with the aim to find agents with favorable clinical outcome and lower bleeding risk. Current clinical studies focus on a new generation of ADP receptor antagonists (prasugrel, cangrelor and ticagrelor) as successors of ticlopidin and clopidogrel after coronary arterial interventions. Developments using platelet targets different from established drugs are thrombin receptor antagonists (like SCH530348) or thromboxane receptor antagonists (like S18886/terutroban) in patients with cerebrovascular events. Results from recent experimental studies could lead to new strategies for antiplatetelet therapy (like inhibition of GP Ib receptor, GP VI receptor, platelet-leukocyte interaction, factor XII and others) in the future.

scholarly journals A Control Parameter Design Method for Hybrid Multi-Terminal HVDC System

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 18669-18680 ◽  
Author(s):  
Bingkun Li ◽  
Yuansheng Liang ◽  
Gang Wang ◽  
Haifeng Li ◽  
Xinquan Chen
Keyword(s):  
Control Parameter ◽  
Design Method ◽  
Parameter Design ◽  
Hvdc System

scholarly journals A Novel Adaptive Control Approach Based on Available Headroom of the VSC-HVDC for Enhancement of the AC Voltage Stability

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3222
Author(s):  
Duc Nguyen Huu
Keyword(s):  
Adaptive Control ◽  
Voltage Stability ◽  
Reactive Power ◽  
Control Method ◽  
Offshore Wind ◽  
Voltage Source ◽  
Long Distance ◽  
Control Approach ◽  
Hvdc System ◽  
Voltage Support

Increasing offshore wind farms are rapidly installed and planned. However, this will pose a bottle neck challenge for long-distance transmission as well as inherent variation of their generating power outputs to the existing AC grid. VSC-HVDC links could be an effective and flexible method for this issue. With the growing use of voltage source converter high-voltage direct current (VSC-HVDC) technology, the hybrid VSC-HVDC and AC system will be a next-generation transmission network. This paper analyzes the contribution of the multi VSC-HVDC system on the AC voltage stability of the hybrid system. A key contribution of this research is proposing a novel adaptive control approach of the VSC-HVDC as a so-called dynamic reactive power booster to enhance the voltage stability of the AC system. The core idea is that the novel control system is automatically providing a reactive current based on dynamic frequency of the AC system to maximal AC voltage support. Based on the analysis, an adaptive control method applied to the multi VSC-HVDC system is proposed to realize maximum capacity of VSC for reactive power according to the change of the system frequency during severe faults of the AC grid. A representative hybrid AC-DC network based on Germany is developed. Detailed modeling of the hybrid AC-DC network and its proposed control is derived in PSCAD software. PSCAD simulation results and analysis verify the effective performance of this novel adaptive control of VSC-HVDC for voltage support. Thanks to this control scheme, the hybrid AC-DC network can avoid circumstances that lead to voltage instability.

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