Traveling wave fault location on HVDC lines

Abstract

In order to transmit massive amounts of power generated by remotely located power plants, especially offshore wind farms, and to balance the intermittent nature of renewable energy sources, the need for a reliable high voltage transmission grid is anticipated. Due to power transfer limitations by AC transmission lines and its cost, the most attractive choice for such a power transfer is a high voltage DC (HVDC) lines [1]. The need to detect the fault location in the transmission line as quickly and accurately as possible has increasingly been demanded by utilities, and the use of traveling wave-based fault location technology has been implemented in order to improve the efficiency and to minimize the electrical system downtime and thus to avoid or minimize penalties [2]. The location method consists from measuring accurate time, when the traveling waves (generated by wave fronts caused by transients during line fault) pass through known measurement points, usually substations located at the ends of the transmission line. Different from fault locators using impedance methods, the location methods using traveling waves can achieve much higher accuracy regardless of fault type and line characteristics. The Travelling Wave Fault Locators (TWFL) currently available on the market rely on measurements from inductive CTs and inductive/capacitive VTs, which are not applicable to DC systems. This paper presents a means to acquire the readings of traveling waves in a HVDC transmission system. In addition, results of the field deployment of a TWFL system on a HVDC transmission line are presented. The described system was implemented on the longest in the world IE Madeira HVDC overhead line over a distance of 2375 kilometers, connecting Porto Velho to Araraquara II substations from Northwest to Southeast of Brazil and tested for stage faults during commissioning.