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The presence of high power single-phase loads produces certain disturbances in low voltage distribution networks: supplementary negative and zero sequence currents will cause excessive heating of electrical machines, saturation of transformers, ripple in rectifiers, protection and interference problems etc.Load compensation at the load bus is an effective method to eliminate those undesired sequence currents. The Steinmetz circuitry, consisting of a reactor, a capacitor and the receiver, suitable connected with each other, is widely used for this purpose. Unfortunately, as usually the load characteristics fluctuate, the parameters of the supplementary reactive elements should also vary.The paper deals with the implementation of fuzzy controlled reactive elements in the Steinmetz scheme in order to compensate the load variation.

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.