A 4m 2kA HTS Power Cable System

A high temperature superconductor （HTS） cable system of both a length of 4 metre and a normal current of 2 KA with terminations and a cooling system has been built up and tested. The cable conductor was made of Bi-2223 tape. A space maintained vacuum between two corrugated stainless steel tubes functions as the cryostat surrounding the superconductor. A series of tests were carried out to verify the functions of the system. The important data obtained can be used to make longer HTS cable systems.

HTS Power Cable Developed

With the support of the National Center for R&D on Superconductivity, a 6m high T_c superconducting (HTS) power cable has cartied a current of 1473 A successfully at the Institute of Electrical Engineering (IEE), CAS. In 1998, a one-meter-long, 1000A HTS power cable prototype was developed successfully by

Aging Characteristics of XLPE Insulation of 110 kV Cables in the Initial Stage of Operation

The aging characteristics of the XLPE insulation of 110 kV power cables in the initial stage of operation are studied in this paper.The XLPE insulation from cables with different running time was tested by using electrical and physicochemical methods,from which the degradation state of XLPE under multiple stresses during operation was derived.The broadband dielectric spectrum test taken from 10–1 to 10^(6) Hz showed that the dielectric constant and dielectric loss of the XLPE insulation first decrease and then increase with the increase of cable running time,which show obvious variation until 10 years of operation.The AC breakdown strengths of the XLPE insulation of operated cables with the service year no longer than 10 years were higher than that of new cables.The mechanical properties of the XLPE insulation showed no dependence with the cable running time.The crystallinity and perfection of the crystallization area were found to be enhanced during operation and the polar functional groups inside the XLPE insulation were found to be determined not only by the cross-linking by-products but also by the oxidation process during cable operation.The experimental results in this paper are important for improving the operation reliability and reducing the maintenance costs of the cables.

傅里叶变换用于地下电缆故障检测(英文)

An analysis of underground power cables is performed using Fourier analysis with the objective of detecting fault and average life of the cables.Three types of cables are used in this experiment:a normal cable,a shorted cable, and a cable with holes.The impedance in each case is computed and Fourier transformation is applied so that the resulting impedance magnitude and impedance phase can be examined in the frequency domain.Various windowing techniques are applied to the experimental data to eliminate any interference.Fourier analysis is then applied to the impedance data calculated from both the sending end voltage and differential voltage.This analysis reveals differences in the frequency response of the three different types of a cable and can eventually be used as a measure for fault detection. Preliminary results reveal the differences in the frequency response.Accordingly,Fourier type methods can be effectively used as low cost and viable solutions to identify and detect faults in underground cables.

挤包高压直流电缆的质量控制:采用低频耐压试验检测电缆的关键缺陷(英文)

The main purpose of the work presented here is to evaluate different methods for quality control of polymeric insulated HVDC cables.The insight gained can be used to evaluate proposed test methods for quality assurance of long lengths of polymer insulated power cables.Laboratory experiments were performed using both Rogowski shaped test objects and model cables,insulated with XLPE containing imbedded spherically shaped particles.Tests were performed by stressing the test object with AC(50 Hz),VLF(0.1 Hz) and DC voltages and measuring time to breakdown at the different voltages.The slope of the voltage-time curve for 0.1 and 50 Hz were found to be parallel showing higher breakdown strength for 0.1 Hz than 50 Hz.The number of periods to breakdown is somewhat higher for 0.1 Hz than for 50 Hz.The breakdown strength for DC was much higher than for both AC 50 Hz and 0.1 Hz.The results indicate that the VLF test voltage needs to be 2 to 3 times higher than at 50 Hz power frequency in order to eliminate the same defects within a comparable time.

Prediction and Measurement Techniques for Radiated EMI of Power Converters with Cables

Recently,radiated electromagnetic interference(EMI)has become a research hotspot in power electronics systems,as the switching frequencies of power electronics systems have increased significantly with the adoption of wide-bandgap devices.In this article,a generalized radiated EMI model for power electronics converters with power cables is first reviewed.The radiated EMI model is then developed for a flyback power converter with critical ground impedance included.Based on the developed model,accurate high-frequency parameter extraction techniques and a radiated EMI prediction technique are developed and experimentally validated.Finally,essential measurement techniques are identified and developed to accurately extract parameters for accurate EMI prediction.The effects of the resolution bandwidth of the spectrum analyzer and critical PCB ground impedance on the radiated EMI are experimentally validated.PCB’s impact on the common-mode(CM)choke’s impedance and the radiated EMI is further validated.Techniques for minimizing the undesired near-field couplings in parameter extraction are discussed.The predicted EMI properly agreed with the measured EMI in the range of 30-230 MHz based on the EN550323 m class B standard.

Installation and operational effects of a HVDC submarine cable in a continental shelf setting: Bass Strait, Australia

Despite the many submarine telecommunications and power cables laid world-wide there are fewer than ten published studies of their environmental effects in the refereed literature.This paper describes an investigation into the effects of laying and operating the Basslink High Voltage Direct Current(HVDC)cable and its associated metallic return cable across Bass Strait in South East Australia.Over more than 95%of its length the cable was directly laid into a wet jetted trench given the predominantly soft sediments encountered.Underwater remote video investigations found that within two years all visible evidence of the cable and trench was gone at over a third of the transects at six deep water sites(32-72 m deep).At other deep water transects the residual trench trapped drift material providing habitat for the generally sparsely distributed benthic community.Diver surveys at both of the near shore sites(<15 m deep)on the northern side of the Strait also found the cable route was undetectable after a year.On the southern side,where the cable traversed hard basalt rock near shore,it was encased in a protective cast iron half shell.Ecological studies by divers over 3.5 years demonstrated the colonization of the hard shell by similar species occupying hard substrates elsewhere on the basalt reef.Magnetic field strengths associated with the operating cable were found to be within 0.8%of those predicted from theory with strength dropping rapidly with distance from the cable.Beyond 20 m the field was indistinguishable from background.