Power flow control in DC transmission grids using mechanical and semiconductor based DC/DC devices

• Published in: 10th IET International Conference on AC and DC Power Transmission (ACDC 2012) p. B43
• Main Authors: Jovcic, D, Hajian, M, Zhang, H, Asplund, G
• Format: Conference Proceeding
• Language: English
• Published: Stevenage, UK IET 2012; The Institution of Engineering & Technology
• Subjects: Control of electric power systems; Current control; d.c. transmission; Power cables; Power convertors and power supplies to apparatus; Power system control; Switchgear; power transmission lines; choppers (circuits); power system simulation; large meshed DC grid; electric current control; transmission line-cable; mechanical based DC-DC converter; semiconductor based DC-DC converter; mechanical based DC circuit breaker; half bridge bidirectional DC chopper; DC line-cable; PSCAD simulation; power cables; circuit breakers; resistor; power grids; voltage 370 kV; semiconductor based DC circuit breaker; AC-DC converter; DC power flow control; DC-DC power convertors; electric potential; DC transmission networks; power transmission control; DC transmission grid; load flow control; voltage drop; current drop
• ISBN: 1849197008; 9781849197007
• DOI: 10.1049/cp.2012.1972

DC power flow can be controlled though N-1 different DC lines/cables in a DC grid having N individual AC/DC converters. A large meshed DC grid can have more DC lines, and since we can not control power in all lines/cables, an overload may result. In this paper, two methods are proposed for DC power flow control through DC lines/cables. The first method involves using extra resistors embedded in series with DC lines/cables and switched by mechanical or semiconductor based DC circuit breakers. The other method includes installing DC/DC converter at one of the DC line/cable ends with the purpose of DC power flow control. It is shown that the first approach suits better for a short transmission line/cable, while the second one is proposed for a long transmission line/cable with high rated current and higher voltage drop. PSCAD simulation results are presented for a half bridge bidirectional DC chopper employed for DC power flow control between two large 370kV DC grids. (6 pages)