Investigation of a Hybrid HVDC System with DC Fault Ride-Through and Commutation Failure Mitigation Capability

Abstract

A hybrid HVDC system that is composed of line commutated converter (LCC) at the rectifier side and voltage source converter (VSC) in series with LCC at the inverter side is studied in this paper. The start-up strategy, DC fault ride-through capability, and fault recovery strategy for the hybrid HVDC system are proposed. The steady state and dynamic performances under start-up, AC fault, and DC fault scenarios are analyzed based on a bipolar hybrid HVDC system. Furthermore, the immunity of the LCC inverter in hybrid HVDC to commutation failure is investigated. The simulation results in PSCAD/EMTDC show that the hybrid HVDC system exhibits favorable steady state and dynamic performances, in particular, low susceptibility to commutation failure, excellent DC fault ride-through, and fast fault recovery capability. Results also indicate that the hybrid HVDC system can be a good alternative for large-capacity power transmission over a long distance by overhead line.

Offshore Wind farm HVDC Transmission System Protection against AC and DC Faults

“…Moreover, fault direction cannot be provided by overcurrent protection. Therefore, overcurrent is usually used as a backup protection if the main protection fails to trip out the fault in the corresponding zone [7][8][9][10]. The main issue associated with the smart grid is to implement communication-based protection techniques.…”

“…The main issue associated with the smart grid is to implement communication-based protection techniques. However, these techniques require backup protection scheme to manage communication link failures [7]. The differential protection techniques are based on measured AC signals from both ends of the lines.…”

Power Equalization Control Strategy for MMCs in Hybrid-Cascaded UHVDC System

“…The rectifier station still has LCC, while the inverter station has LCC at the high end and three MMCs in parallel at the low end. The hybrid-cascade UHVDC system meets the requirements for a large transmission capacity, commutation failure mitigation, and flexible control at the same time [8][9][10][11]. However, the operating principle and control strategies of the two types of converters are essentially different.…”