A Composite Strategy for Improved Power Quality Using Micro Compensators in Secondary Distribution Systems

This paper introduces a micro compensator which is installed and maintained by an electric utility for improved power quality in low voltage secondary distribution systems. Envisaged as a shunt-connected current-controlled voltage source inverter at 400 V level, a micro compensator performs reactive and harmonic compensation during peak periods. Hence the power factor and the power quality at the point of common coupling are improved. During off-peak periods, a micro compensator provides dynamic reactive current support to compensate for voltage sag or voltage swell. The weighing factors which regulates the contribution of each compensation are quantitatively derived from voltage measurements at the point of common coupling. The proposed method to calculate reactive and harmonic compensation indices is validated in realistic systems. Frequency domain analysis shows that the harmonic compensation can be achieved in both static and dynamic modes. Analytical predictions based on frequency domain analysis are verified with experimental results which shows notable improvement in power quality levels.