Reliability and Power Density Increase in a Novel Four-Pole System for Line-Commutated Converter HVDC Transmission

Abstract

This paper presents a novel four-pole system for line-commutated converter high-voltage direct current transmission with a quad 12-pulse operation. This system aims to eliminate a ground electrode or metallic return and increase the reliability and density of power transmission. The operating principles of this system are presented, followed by a detailed mathematical analysis of a conventional bipolar and the proposed four-pole systems. The mathematical results show that the proposed four-pole system has the following advantages: 1) it has four effective parallel 12-pulse dc circuits instead of only two, similar to a bipolar system; 2) it increases the reliability and density of power transmission; 3) it can avoid using a neutral conductor (metallic return) or the ground electrode that injects dc current into the ground; and 4) it efficiently facilitates power transmission due to relatively low line-to-line dc voltage levels. A complete simulation of the proposed four-pole system and the conventional bipolar system is performed using MATLAB/Simulink. The simulation results show that the proposed four-pole system configuration can eliminate the ground electrode or metallic return, produce four effective parallel dc circuits at low lineto-line dc voltages with quad 12-pulse operations, and increase the reliability of the system. In addition, phase-to-ground ac faults and pole-to-ground dc faults have been efficiently cleared. INDEX TERMS LCC-HVDC transmission, 12-pulse converter, multi-pole HVDC system, HVDC grounding electrode.

Complete Method to Assess the DC Corrosion Impact on Pipeline Systems During the Planning and Approval Stages of HVDC Systems With Earth Current Return

“…This allows for an explicit calculation, merely relating to the expected time of electrode usage at full operational current. It is apparent that the proposed method is redundant when evaluating HVDC system options that do not make use of electrodes (e.g., bipolar systems with dedicated metallic return, four-pole systems [6], etc. ).…”

“…Within (6), ACX refers to the availability of the converter, ATRX to the availability of the transformer, ACRX to the availability of the coupling reactor, ACUX to the availability of the converter unit, ACSX to the availability of the control system and ASWX to the availability of the DC switchyard, at converter station X (i.e. either station 1 or station 2).…”

Upgrading of the Existing Bi-Pole to the New Four-Pole Back-to-Back HVDC Converter for Greater Reliability and Power Quality

“…A novel four-pole HVDC power transmission topology is presented in [15] to increase reliability and power density transmission. The application of the proposed four-pole system in [15] is limited to the Point-to-Point HVDC transmission system without using the ground electrode for carrying its return current. This study introduces a novel topology based on [15] for Back-to-Back HVDC system applications.…”

“…The application of the proposed four-pole system in [15] is limited to the Point-to-Point HVDC transmission system without using the ground electrode for carrying its return current. This study introduces a novel topology based on [15] for Back-to-Back HVDC system applications. This topology is proposed to upgrade an existing 2PBTBS LCC-HVDC with two parallel 12-pulse DC circuits to the 4PBTBS with four parallel 12-pulse DC circuits for increased system reliability.…”

Effect of Temperature on Space Charge Distribution in Two Layers of Transformer Oil and Impregnated Pressboard Under DC Voltage

“…The oil-paper insulation is the main insulation of the converter transformer, which is the core equipment for AC-DC conversion in the HVDC system. The valve side winding of the converter transformer works under AC-DC combined electric field during the operation [1], [2]. The space charge is easy to accumulate in the solid insulators under DC electric field [3].…”