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精品文档---下载后可任意编辑 HARMONIC DISTORTION AND REACTIVE POWER COMPENSATION IN SINGLE PHASE POWER SYSTEMS USING ORTHOGONAL TRANSATION TECHNIQUE W. Hosny(1)and B. Dobrucky(2) (1) University of East London, England (2) University of Zilina, Slovak Republic ABSTRACT This paper reports a novel strategy for analysing a single phase power system feeding a non-linear load. This strategy is based on a new theory to trans the traditional single phase power system into an equivalent two-axis orthogonal system. This system is based on complementing the single phase system with a fictitious second phase so that both of the two phases generate an orthogonal power system. This would yield a power system which is analogous to the three phase power system but with the phase shift between successive phases equal to л/2 instead of 2л/3. Application of this novel approach makes it possible to use the complex or Gauss domain analytical in a similar way to the well known of instantaneous reactive power for three phase power system instigated by Akagi et al in 1983. Thus, for the fictitious two-axis phase power system, the concept of instantaneous active and reactive power could be instigated. Moreover, the concept of instantaneous power factor could be defined. The novel strategy of power system analysis outlined in this paper is applied to a single phase power system feeding a non-linear load in conjunction with an active power filter. The latter serves the purpose of compensating for either of the instantaneous reactive power or the harmonic current distortion in the single phase power system under investigation or for compensating of both. Experimental results demonstrated the effectiveness of the novel single phase power system analysis reported in this paper. Keywords: single phase power systems, orthogonal transation technique, harmonic distortion and reactive power compensation 1 INTRODUCTION In this section the orthogonal transation technique applied to a single phase power system instigated by Akagi et al, reference [1], is described. By adopting this technique expressions for the reference currents used in an active power filter for the compensation of harmonic distortion or reactive power or both, are derived. Consider a single phase power system which is defined by its voltage and current as follows: vRe(t) = V Cos ωt (1) iRe(t) = I Cos (ωt – Ф) Where V and I respectively are the peak values of the voltage and current, ω is the angular frequency of the power supply and Ф is the phase shift between voltage and current. The power system described by Eq.(1) is termed as the real part in a complex power system and is complemented by a fictitious/imaginary phase defined as follows: Vim(t) = V Sin ωt