Diminishing the Computational Burden when Analyzing Electrical Signals with Long Wavelet Filters
Journal Title: ANALELE UNIVERSITATII DIN CRAIOVA - Seria Inginerie electrica - Year 2017, Vol 41, Issue 41
Abstract
Wavelet analysis is characterized by filters with irrational coefficients and runtimes increasing with filters order. The terminal nodes of Wavelet Packet decomposition trees exhibit good harmonics’ selectivity when implemented with Daubechies wavelet mothers with filters of length 28 and respectively of length 40 (denoted in MATLAB by ‘db14’ and ‘db20’). Therefore they can be used for power quality (PQ) analysis of electric signals. When rounded to 4 decimal places, certain coefficients from these filters become 0. In the “rounded” context, the number of iterations sup-porting the convolution products involved by the Wavelet analysis is restricted. Based on the number of neglected co-efficients and length of wavelet filter, a formula is deduced for the percent runtime savings strictly associated to the wavelet decompositions. Statistical evaluations (considering sets of 20 consecutive programs executions) were performed considering full operational contexts, where all types of studied wavelets were involved in complex operations like evaluating PQ indices and harmonic spectra. The mean runtime savings proved to be 20.4% for ‘db14’ and respec-tively 23.2% for ‘db20’. The impact of rounding over the PQ analysis’s accuracy was evaluated considering three-phase waveforms acquired from a power group. The follow-ing quantities were considered: harmonic spectra and ener-gies of the Wavelet Packet tree’s terminal nodes, instanta-neous values corresponding to the fundamental frequency, vectors of details and approximations yielded by the Dis-crete Wavelet Transform and signals reconstructed from the vectors of details and approximations. Highly acceptable small errors were obtained, recommending the rounding to 4 decimal places of the analyzed wavelet filters as a faster reliable wavelet based analysis method.
Authors and Affiliations
ILeana-Diana Nicolae, Petre-Marian Nicolae, Ionuţ Daniel Smărăndescu
DATA ACQUISITION AND PROCESSING SYSTEM FOR SMART MEASUREMENT OF POWER IN HV GRIDS BY OPTOELECTRONIC MEANS
The present concerns related to the smart use of energy require changes in the way in which the electric energy consumption management should be performed, under the circumstances connected to the assurance of electric e...
OPTIMAL SOLUTION OF WEAK SPOTS PROBLEM IN A GRID SYSTEM BY MEANS OF FACTS DEVICES
Electrical power system functioning is permanently exposed to different disturbances which cause the regime parameters change. Every grid system contains elements whose regime parameters variations influence system...
Diagnosis with Analytic Model of a Rectifier for Faults of the Rectifier Control
The diagnosis of the electric systems is an actual item for the specialists in domain. Due to the variety of the measurements and multiplicity of faults which can be analyzed, the approach is motivating. The model reprod...
Computing of Phase Shift for Coupled Oscillators through a Two-Port Passive Network
Voltage controlled microwave oscillators are used in digital communication systems. Pairs of coupled and synchronized voltage controlled oscillators are used to control the phase in microwave antenna arrays as a...
CPC - Based Reactive Compensation of Linear Loads Supplied with Asymmetrical Nonsinusoidal Voltage
The paper presents a method of calculation of LC parameters of reactive balancing compensators of linear time-invariant (LTI) loads supplied with a nonsinusoidal and asymmetrical voltage. The method is based on the Cur-r...