A New Signal Processing based Method for Reactive Power Measurements

Abstract

<p class="MsoNormal" style="text-align: left; margin: 0cm 0cm 0pt; layout-grid-mode: char;" align="left"><span class="text"><span style="font-family: ";Arial";,";sans-serif";; font-size: 9pt;">A new modified Walsh function (WF) based method for the measurement of reactive power (RP) under both sinusoidal and non-sinusoidal conditions is proposed and investigated. Proposed method simplifies the multiplication procedure to evaluate the reactive components from instantaneous power signal using peculiar properties of the WF. One of the advantages of proposed measurement approach is that in contrast to the known existing methods which involve phase shift operation of the input signal, the proposed technique does not require the time delay of the current signal to the 2 / π with respect to the voltage signal. Another advantage is related to the computational saving properties of the proposed approach coming from use of the Walsh Transform (WT) based signal processing method. Proposed method eliminates an influence of the prevalent third order current harmonic to and reduces the effect of the highest order current harmonics on the RP measurement results. The examples are used to illustrate validity and effectiveness of the suggested method for evaluation of the RP. A new method has been tested by use of a simulation tools developed on the base of “Matlab”.</span></span><span style="font-family: ";Arial";,";sans-serif";; font-size: 9pt;"></span></p&gt

Measurement of Reactive Power in Three-Phase Electric Power Systems by Use of Walsh Functions

“…To obtain the algorithm for measuring the reactive power in phase a, we multiply both sides of Eq. A9 (See Appendix) by the third order WF [23], ) . 3 ( t Wal and integrate over the period T of power system frequency:…”

“…In previous research works [19]- [23] the WF based RP measurement method and some aspects of its realization [19], a modified WF based method for the measurement of reactive power in sinusoidal as well as in noise conditions with the immunity to the distortion power [20], a new algorithm for evaluation the reactive components from instantaneous power signal and its realization on the electronic elements [21], the effect of the harmonics on the WF based RP measurement algorithm and problems related to the estimation and correction of the error introduced by harmonics [22], the signal processing based frequency insensitive RP measurement algorithms involving peculiar properties of the WF [23] have been investigated and proposed.…”

“…The attraction of WF based approach to RP evaluation in three-phase systems comes from the key advantages such as following [23]:…”

“…Considering the solution of the right side integral (See[23] for details)of this Eq. we have [ of this equation for the b phase RP,…”