Proposal of waveform parameters determination techniques for steady state AC and short-time AC waveforms generated by IEC 61083-4 TDG

IEC 61083-4, which is, to date, still in a draft stage, defines requirements for a software which analyses a.c. and d.c. waveform parameters distilled from digitally measured data. TDG (Test Data Generator) to be attached to the 61083-4 simulates digitally recorded data for typical waveforms observed in daily measurement. Any acceptable software should determine waveform parameters within a given margin specified in the forthcoming standard. Authors could successfully analyse all the a.c. waveforms generated by the TDG using techniques, 1) FFT after an interpolation for steady a.c. and 2) a base curve for short-term a.c. The former can get rid of superposing noise by applying digital low-pass filter and can analyses higher frequency components. The latter involves the least square method for fitting the so-called “base curve” to measurand and a set of non-linear equations to be solved with Levenberg-Marquardt method. The distilled parameters for both waveforms are within the specified margins (0.1% in peak value) proposed in IEC 61083-4. The details of the algorithm are to be clarified in the paper. Also mentioned in the paper is a proposed TDG’s controversial behaviour in which a currentzero instant is shifted due to a discrete sampling interval. A solution to this problem is also proposed in the paper.