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Power Quality Harmonics Analysis and Real Measurements Data Part 11

Tham khảo tài liệu 'power quality harmonics analysis and real measurements data part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Characterization of Harmonic Resonances in the Presence of the Steinmetz Circuit in Power Systems 189 The resonant behavior of the Steinmetz circuit with power system reactors occurs in a range of relatively large harmonics. The resonances are located in the low-order harmonics only if the displacement power factor of the single-phase load impedance is close to the unity value i.e. Ằl 1 and this impedance is small in comparison with the supply system reactances i.e. small rL ratios . The former condition is common but considering that rL Ằl SS SL Sainz et al. 2009a the latter only occurs in weak power systems where the short-circuit power at the PCC bus SS is low compared to the apparent power of the single-phase load SL. The resonances are shifted to high-order harmonics if the T1 ratio of the Steinmetz circuit inductor is far from the zero value i.e. its displacement power factor Ằ1 is far from the unity value. It is also true if the Steinmetz circuit capacitor degrades i.e. the Steinmetz circuit suffers capacitor loss and de is also far from the unity value. 6. Examples For the sake of illustration two different implementations of the kr a expression 22 are developed. In the first the analytical study in Section 4 is validated from laboratory measurements. Several experimental tests were made to check the usefulness of the kr a expression in locating the parallel and series resonance. In the second this expression is applied to locate the harmonic resonance of several power systems with a Steinmetz circuit in the literature. 6.1 Experimental measurements of power system harmonic response To validate the analytical study measurements were made in two downscaled laboratory systems corresponding to the networks of Fig. 4 parallel resonance and Fig. 6 series resonance . The frequency response measurements were made with a 4.5 kVA AC ELGAR Smartwave Switching Amplifier as the power source which can generate sinusoidal waveforms of arbitrary frequencies between 40 Hz