Analysis of the Steinmetz compensation circuit with distorted waveforms through symmetrical component-based indicators

Abstract

This paper deals with the use of a set of indicators defined within a symmetrical component-based framework to study the characteristics of the Steinmetz compensation circuit in the presence of waveform distortion. The Steinmetz circuit is applied to obtain balanced currents in a three-phase system supplying a single-phase load. The circuit is analyzed without and with harmonic distortion of the supply voltages. The compensation effect is represented by the classical unbalance factor and by the Total Phase Unbalance (TPU) indicator defined in the symmetrical component-based framework. Comparing the two indicators, it is shown that the classical unbalance factor is insufficient to represent the effect of voltage distortion and fails to detect the lack of total unbalance compensation occurring with distorted waveforms. Correct information is provided by calculating the TPU indicator.

Characterization of Harmonic Resonances in the Presence of the Steinmetz Circuit in Power Systems

“…Harmonics are not considered in the literature in Steinmetz circuit design and the reactances are determined from the fundamental waveform component with the previous expressions. Nevertheless, Steinmetz circuit performance in the presence of waveform distortion is analyzed in (Arendse & Atkinson-Hope, 2010;Chicco et al, 2009). Several indicators defined in the framework of the symmetrical components are proposed to explain the properties of the Steinmetz circuit under waveform distortion.…”

“…However, this can be solved by the introduction of thyristor-controlled reactive elements due to the development of power electronics in the last few years and the use of step variable capacitor banks, (Barnes & Wong, 1991;Chindris et al, 2002). Steinmetz circuit design must consider circuit performance and behavior under nonsinusoidal conditions because of the growing presence of non-linear devices in electric power systems in the last few decades, (Arendse & Atkinson-Hope, 2010;Chicco et al, 2009;Czarnecki, 1989Czarnecki, , 1992. Harmonic currents injected by non-linear devices can cause voltage distortions, which may damage power quality.…”

“…1c, external balancing equipment consists in the delta connection of reactances (usually an inductor Z 1 and a capacitor Z 2 ) with the single-phase load representing the railroad substation in order to load the network with balanced currents. This circuit, which is known as Steinmetz circuit (ABB Power Transmission, n.d.; Barnes & Wong, 1991;Mayer & Kropik, 2005), is not the most common balancing method in traction systems but it is also used in industrial high-power single-phase loads and electrothermal appliances (Chicco et al, 2009;Mayer & Kropik, 2005). …”

Power quality improvements through power electronic interfaced distributed generation

“…Thereupon, these indices can be weighted and can thus take into account the amount of power transferred by each phase. Another point of view to quantify unbalance is recently given in [9]- [11]. In these papers, the unbalance factor and the distortion factor are considered together.…”

“…As described in [11], the TPU indicator provides the correct information also when the classical unbalance indicator is unable to detect unbalance due to the effects of waveform distortion. Therefore, indicators (14) and (15), will be used to analyse the influence of inverter-connected DG units in the low-voltage grid.…”