Experimental validation of an alternative method to estimate the parameters of tail chopped lightning impulses

Summary

The energy transmission in Ultra High Voltage (UHV), with 1200 kV AC and ±1000 kV DC, requires a new laboratory infrastructure for testing and experimental theory research to consider such voltage levels. The current facilities at high voltage equipment suppliers and at research labs, for the most part, are limited to 765 kV AC and ±600 kV DC. The construction of new laboratories to cater to UHV systems requires more studies about standards for equipment, as well as for testing and measurement techniques. Consequently, with the increase in the voltage levels for AC and DC transmission systems, some adaptations and changes to existing standards might become necessary. To evaluate existing overvoltage in an electrical system, it is important that the characteristics of each type of impulse are known. Each type of waveform represents a phenomenon that can occur in high voltage power equipment, which must be tested and certified in high voltage laboratories by standard procedures prior to its commissioning. The IEC 60060-1:2010 standard, with regard to lightning impulse tests, introduced as the main requirement the test voltage function, which involves digitally filtering the original impulse waveform and calculating the amplitude and time parameters from this filtered waveform. This new procedure should be applied to Full Lightning Impulses (LI) and Tail Chopped Lightning Impulses (LIC) waveforms. Currently, after the revision of the International Electrotechnical Commission (IEC) family of standards 60060 in 2010, the analysis of Tail Chopped Lightning Impulse (LIC) waveforms is only possible by applying a reference Full Lightning Impulse (LI), thus creating difficulties for the experimental procedure and posterior analysis and processing of the waveforms. This paper describes the development and validation of an alternative method for treating the LIC waveforms which excludes the need for a LI reference, being based on the fitting of a double exponential to the LIC waveform up to the instant of chopping.

Additional informations

Authors

C.R.H. BARBOSA, M.T. SILVA, L.C. AZEVEDO

Keywords

Lightning Impulses, Tail Chopped, IEC standard