Al-Rafidain Engineering Journal (AREJ)

The power quality (PQ) is a major issue for both electrical utilities and their customers. The nonlinear loads cause PQ problems like current harmonics, voltage harmonics, frequency deviation, voltage sag and voltage swell. A unified power quality conditioner (UPQC) is utilized in this research to minimize these PQ problems. The UPQC is made up of two active power filters (APFs), one of which is connected to the line in series and the other in parallel. The Unit Vector Template Generation (UVTG) approach is used to control the series APF, whereas the Synchronous Reference Frame (SRF) technique is used to control the shunt APF. The compensating properties of a series-shunt APFs when the loads become imbalanced have been explored. The system performance has been tested under conditions current harmonics, voltage harmonics, voltage sag, and voltage swell. The voltage harmonics are identified and reparation in a series APF using the UVTG technique, whereas the harmonics and unbalanced currents are identified and reparation in a shunt APF using the SRF method. An IEEE-519-compliant THD (Total Harmonic Distortion) of less than 5% is achieved by UPQC in simulations with unbalanced loads. The findings indicate that harmonic currents and supply voltage fluctuations were lessened by UPQC.

Power generation is normally produced at constant frequencies of 50 Hz or 60 Hz and the generators E.M.F can be considered practically sinusoidal. However, when a source of sinusoidal voltage is applied to a nonlinear device or load, the resulting current is not perfectly sinusoidal. Due to non-linear loads, distortions are produced in the sinusoidal waveform so filters are used to minimize these distortions. This paper aims to build a simulation model of a nine-bus ring system to evaluate characteristics of harmonics in different cases of study using electrical transient and analysis program (ETAP), which is considered one of the best tools to study harmonics in the power system, thus, the harmonic distortion is analyzed in ETAP. To generate harmonic distortion in the power network, a general load is modeled as a source of harmonics. A harmonic load flow analysis was carried out in order to determine the impact of harmonic current on a power network, and the THD% of all types of harmonic models on all the buses was checked and the typical IEEE model that has the highest THD% was chosen and compared with the model that contains low THD indices (one of the best models of IEEE manufacturer).