Dynamic Study on the 400 kV 60 km Kyndbyværket – Asnæsværket Line

Until recently, the use of HVAC underground cable systems has been mainly limited to densely populated area. As such, HVAC underground cable systems are limited both in length and numbers to date. This tendency has been changing over the past ten years as the service experience of HVAC, cable systems have shown to be satisfactory. The applications of HVAC cable systems are proposed more often for transmission projects, and recently proposed HVAC underground cable systems are longer compared to existing cable systems. Due to this historical background, HVAC underground cable systems have been studied and tested primarily with short cable lengths. Some knowledge from short cable lines can be directly applied to long cable lines, but there are several phenomena which are peculiar to long cable lines.

The main objectives of the PhD project are to shed light on the phenomena peculiar to long cable lines. The PhD project focuses on the 400 kV 60 km Kyndbyværket – Asnæsværket line, which will feed power to Copenhagen, the Danish capital. The PhD project addresses major problems and potential countermeasures related to the installation and operation of a long cable line, through:
(1) Insulation coordination study
(2) Derivation of theoretical formulas of sequence currents
(3) Identification of dominant frequency components contained in the overvoltage
(4) Analysis on the statistical distribution of energization overvoltages
(5) Protection study