Journal Volume 16 Issue 1

Power Quality Measurements - the Importance of Traceable Calibration

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Helko E. van den Brom, Dennis Hoogenboom

Standardization has contributed significantly to comparable analysis methods for power quality parameters. However, in order to have undisputable results, the measurement values themselves should also be comparable. This can only be achieved by traceability to international measurement standards. For this reason, at VSL, the Dutch national metrology institute, a fully traceable reference setup was developed for calibration of power quality analyzers. In this paper, we show the calibration results of the critical components of the reference setup, we demonstrate its applicability by test measurements on the public low-voltage supply system for specific parameters, and show its ability to simulate and generate events that can be detected and analyzed by both the equipment under test and the reference setup.

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Last Updated on Monday, 04 August 2014 13:42

Circuit for Balancing Harmonic-Polluted Three-Phase Networks

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Mohamed M. Saied

This paper presents a new circuit capable of balancing harmonics-polluted three-phase power networks supplying single-phase loads. It takes into account the negative and positive sequences exhibited by the fifth and seventh harmonics, respectively. The concept extends the relations of the Steinmetz circuit, which are based exclusively on fundamental frequency considerations. The Steinmetz circuit does not, therefore, guarantee the balancing of the different harmonics in the line currents. Furthermore, it can lead to resonances between the capacitive and inductive elements in the two added balancing branches. A procedure for identifying the topology and the circuit parameters of the proposed connection is given. The results of a detailed case study are presented in order to demonstrate the superiority of the proposed circuit over the conventional Steinmetz connection.

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Last Updated on Monday, 04 August 2014 13:43

New Control Algorithms for Three-Phase Four-Wire Unified Power Quality Conditioner — a simulation study

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Yash Pal, A. Swarup, Bhim Singh

In this paper, some new control algorithms are proposed for three-phase four-wire Unified Power Quality Conditioner. These control algorithms are based on the combination of Unit Vector Template Generation (UVTG) with Power Balance Theory (PBT), single phase d-q theory, Synchronous Current Detection (CSD) technique, and I CosΦ theory. The performance of each control algorithm of UPQC is evaluated in terms of power factor correction, load balancing and source neutral current mitigation, and voltage and current harmonic mitigation. The performance of proposed control algorithms are compared with synchronous reference frame (SRF) based control algorithm. In each proposed control scheme of the three-phase four-wire UPQC, the current/voltage control is applied over the fundamental supply currents/ load voltages instead of fast changing APFs currents/voltages, thereby reducing the effects of computational delay. Moreover, the load neutral or shuntAPF neutral currents are not sensed hence the required current sensors are reduced.

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Last Updated on Monday, 04 August 2014 13:48

On Some Properties of Instantaneous Active and Reactive Powers

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Leszek S. Czarnecki

Some features of the instantaneous active and reactive powers p and q , not reported earlier, are discussed in this paper. It is shown that oscillating components and of these powers may not depend on the order of the load current harmonic. It was shown, moreover, that a load supplied with a nonsinusoidal voltage may not be distinguished in terms of p and q powers from a harmonics generating load (HGL) supplied with a sinusoidal voltage. This observation is important for compensator control. Also it was shown that the instantaneous reactive power q cannot be interpreted as a measure of amount of energy exchanged between supply lines of a load or as amount of energy rotating around such lines, as it was suggested in some publications on the IRP p-q Theory. A phenomenon of energy rotation or exchange between lines does not exist.

 

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Last Updated on Monday, 04 August 2014 13:47