Comparison of digital analysis procedures for high-voltage impulses according to revised IEC and IEEE standards on high-voltage test techniques

摘要

There have been recent developments in digital analysis methods for the evaluation of parameters ofhigh-voltage impulses used for testing major power system assets. The recently published internationalstandards IEC 60060-1:2010, IEC 60060-3:2010, and IEEE Std 4-2013 have adopted these methods tofurther enhance the reliability of high-voltage impulse testing. One of the significant improvements,now written into these new standards, is on the analysis of full lightning-impulse (FLI) voltages andtailed chopped lightning impulse (TCLI) voltages. Compared to the previous editions of the standards(IEC 60060-1:1989 and IEEE Std 4-1995), the methods in these newly revised standards havesignificantly improved the accuracy of the analysis results, especially for cases where superimposedovershoot or oscillation is present in the test impulses. This improvement is especially important fortesting large equipment at UHV levels where overshoot and oscillation is inherent to the large testcircuits due to the physical size of test objects.Some changes have also been made in the revised international standards regarding the measurementprocedures for switching impulse voltages, to address the difficulties in evaluating the time parametersof this type of impulses. The switching impulse voltage test is one of the most important tests forhigh-voltage equipment with system voltages at the transmission levels.Although the new evaluation methods, now written in these relevant standards, follow the sameprinciples that had been studied by the high-voltage research communities, the test results may stilldiffer when different procedures stipulated in the standards for the same test are used. This paper seeksto evaluate the differences in the results obtained by different analysis procedures described in thesenewly published standards. In particular, we evaluate1. two procedures, one specified in IEC 60060-1:2010 and one in IEEE Std 4-2013, fordetermining full lightning impulse voltage parameters;2. three procedures, one specified in IEC 60060-1:2010 and two in IEEE Std 4-2013, fordetermining tail chopped lightning impulse voltage parameters, are evaluated; and3. five procedures, two described in IEC 60060-1:2010, one in IEEE Std 4-2013, one in IEC60060-3:2006 and a newly proposed by previous researchers, for determining switchingimpulse voltage parameters, are evaluated.The evaluations are performed using the same recorded impulse waveforms and waveforms generatedby the Test Data Generator of IEC 60183-2:2013 for each type of impulses. Regarding the procedurefor full lighting impulses and tail chopped impulses, the comparisons show that the differences in theprocedures are insignificant for the purposes of equipment testing. However, they may becomesignificant for the purposes of calibration of impulse measurement systems. This indicates that acalibration may need to be defined for a particular procedure depending on the required accuracy ofthe calibration. For switching impulses, the comparisons show that differences in the procedures aresignificant even for equipment testing purposes. Hence further improvements or harmonisation of therelevant standards are necessary in the case of switching impulse evaluation, in order to furtherenhance testing consistency and efficiency across the industry.