Active power conditioners to mitigate power quality problems in industrial facilities

Abstract

[Excerpt] Introduction: Non-linear loads are commonly present in industrial facilities, service facilities, office build‐ings, and even in our homes. They are the source of several Power Quality problems such asharmonics, reactive power, flicker and resonance [1-3]. Therefore, it can be observed an in‐creasing deterioration of the electrical power grid voltage and current waveforms, mainlydue to the contamination of the system currents with harmonics of various orders, includinginter-harmonics. Harmonic currents circulating through the line impedance produces distor‐tion in the system voltages (see Figure 1). Moreover, since many of the loads connected tothe electrical systems are single-phase ones, voltage unbalance is also very common in three-phase power systems [2]. The distortion and unbalance of the system voltages causes severalpower quality problems, including the incorrect operation of some sensitive loads [4,5]. Fig‐ure 1 presents a power system with sinusoidal source voltage (vS) operating with a linearand a non-linear load. The current of the non-linear load (iL1) contains harmonics. The har‐monics in the line-current (iS) produce a non-linear voltage drop (∆v) in the line impedance,which distorts the load voltage (vL). Since the load voltage is distorted, even the current atthe linear load (iL2) becomes non-sinusoidal. [...]