scholarly journals Cable Capacity Enhancement by Utilizing Trapezoidal Voltage Waveform

2019 ◽  
pp. 103-107
Author(s):  
Mohamad Ghaffarian Niasar ◽  
W Li ◽  
Peter Vaessen
Keyword(s):  
Field Distribution ◽  
Peak Load ◽  
Homogeneous Field ◽  
Voltage Waveform ◽  
Multilevel Converters ◽  
Cable Insulation ◽  
Capacity Enhancement ◽  
Underground Cable ◽  
Dynamic Voltage ◽  
Continuous Power

To avoid installation of expensive new underground cable connections in locations where peak load exceeds existing cable capacity, it is advantageous to transfer more power through a cable than its nominal power capacity, without endangering its reliability. Dynamic current rating of cables is a typical approach that is used to exceed the nominal cable capacity for a short time period. In this paper a new method for cable capacity enhancement based on dynamic voltage rating is introduced. The method can be applied if multilevel converters are installed at both ends of cable as will become more commonplace in the future when an inverter rich power system is realized. In this study the influence of trapezoidal voltage waveform on the electric field distribution inside cable insulation is investigated. The results shows that by using trapezoidal waveform it is possible to achieve a more homogeneous field distribution inside the cable insulation. This enables better utilization of the insulation system which translates into higher continuous power transfer capacity.

scholarly journals Operation and Control of a Seven-Level V-Clamp Multilevel Converter

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4761
Author(s):  
Yao Xue ◽  
Xiaofeng Yang ◽  
Lutian Yuan ◽  
Trillion Q. Zheng
Keyword(s):  
Power Conversion ◽  
Modulation Method ◽  
Multilevel Converter ◽  
Multilevel Converters ◽  
Output Performance ◽  
Flying Capacitors ◽  
Dynamic Voltage ◽  
Set Up ◽  
And Control ◽  
Laboratory Prototype

Multilevel converters are well suited for high-power and high-quality power conversion. This paper presents a new seven-level V-clamp multilevel converter (VMC) with reduced clamping devices. All phases of the VMC share common DC-link capacitors and realize bidirectional power conversion without flying capacitors. Each branch of the VMC sustains only a single-level voltage of the DC-link capacitors during its commutation process. Hence, the series switches can be controlled as simple as one switch and the dynamic voltage unbalancing issue is avoided. In this paper, the operation principle and the modulation method of the VMC are analyzed in detail. In addition, compensation control for non-ideal factors is designed to improve the output performance. The output fundamental distortion is compensated and the harmonics are reduced. Finally, a laboratory prototype of the seven-level VMC is set up to verify the feasibility of the presented topology and analysis.

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