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DIGITAL FILTERS IMPLEMENTATION IN MICROPROCESSOR-BASED RELAY PROTECTION
- Source :
- Izvestiâ Vysših Učebnyh Zavedenij i Ènergetičeskih ob Edinennij SNG. Ènergetika, Vol 59, Iss 5, Pp 397-417 (2016)
- Publication Year :
- 2016
- Publisher :
- Belarusian National Technical University, 2016.
-
Abstract
- This article presents the implementation of digital filters used in digital relay protection current measuring elements. Mathematical descriptions of the considered digital filters as well as the computer programs for their coefficients calculation are described. It has been shown that in order to reliable estimate the digital filter performance its input signals waveforms must be close to the actual secondary current waveform of the current transformer to which the digital protection with the estimated digital filter is connected. For these purposes in MatLab–Simulink dynamic simulation environment the power system and the current measuring element models were developed. Performed calculations allowed to reveal that the exponentially decaying DC component which in some cases contains in primary fault current drives the current transformer core into saturation even when its nominal parameters are not exceeded. This results in distortion of the current transformer secondary current which in this case contains higher and inter-harmonics. Moreover, such harmonic content is not completely taking into account during coefficients calculation of the considered digital filters what results in signal magnitude estimation inaccuracy. Comparison of the digital filters response to the above-mentioned input signals allowed to find out such digital filter implementations which enable signal magnitude estimation with a minimum error. Ways of filtering quality improvement concerned with the window functions are proposed. Thus, the joint usage of digital filter and Hamming window allows to achieve the zero value of the signal magnitude gain factor in high-frequency range and substantially suppress all spectral components above 100 Hz. The increasing of the signal magnitude settling time in this case can be reduced by choosing the most optimal parameters of the all components of the current measuring element.
- Subjects :
- digital filter
discrete fourier transform
least error squares technique
orthogonal component
hamming window
digital signal processing
current transformer
saturation
digital relay protection
matlab
simulink
Hydraulic engineering
TC1-978
Engineering (General). Civil engineering (General)
TA1-2040
Subjects
Details
- Language :
- Russian
- ISSN :
- 10297448 and 24140341
- Volume :
- 59
- Issue :
- 5
- Database :
- Directory of Open Access Journals
- Journal :
- Izvestiâ Vysših Učebnyh Zavedenij i Ènergetičeskih ob Edinennij SNG. Ènergetika
- Publication Type :
- Academic Journal
- Accession number :
- edsdoj.74276269ddf949c3b17ccdd30027d972
- Document Type :
- article
- Full Text :
- https://doi.org/10.21122/1029-7448-2016-59-5-397-417