A New Space Vector Pulse Width Modulated Transformer Less Single-Phase Unified Power Quality Conditioner


Emergence of solid-state switching devices, like thyristors, GTO’s, IGBT’s and etc, are widely used for controlling electric power in power electronic equipment for various purpose such as HVDC systems, computers etc. These devices draw disturbance in voltages and currents of both source side and distribution ends due to its non-linearity. This induce harmonics, reactive power, and excess neutral current cause the system to have less efficiency and reduction in power factor. In this paper transformer less single-phase unified power quality conditioner has been implemented to reduce the voltage and current distortions. The operation and control of single-phase transformer less three leg Unified power quality conditioner is investigated with the implementation of a new pulse width modulation method for solving the coupling problem introduced by common leg switches.


  1. TL-UPQC
  2. SVPWM
  3. Harmonics
  4. Total harmonic distortion
  6. DVR



Fig. 1. Block Diagram for Harmonic Reduction Using UPQC.


Fig. 2. DC- link Voltage Waveforms.

Fig. 3. Source Current Waveforms.

Fig. 4. % THD of Source Side Current.

Fig. 5. Switching pulses of Inverter.

Fig. 6. Waveform of Supply side, Load side Voltage and Distorted Voltage at Supply Side.

Fig. 7. % THD of Distorted Voltage Waveform.


The custom power devices such as DVR helps in compensation of voltage unbalances and DTATCOM helps in the elimination of current harmonics that are entering the circuit due to the presence of a non-linear load at the consumer side. By using a unified power quality conditioner both the issues such as compensation of voltage unbalances and elimination of current harmonics can be minimized. The replacement of the series transformer with a series inductance helps to overcome the issues of cost and weight of the system. The working principle and implementation of practical two-level space vector modulation has been shown. The special switching sequence incorporated in space vector modulation technique technique used here minimizes the coupling issues that occur in the common leg operation.


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[2] I. Hunter, Power quality issues-a distribution company perspective, Power Eng. J., 15 (2) (Apr. 2001) 75–80.

[3] B. Singh, K. Al-Haddad, A. Chandra, A review of active filters for power quality improvement, IEEE Trans. Ind. Electron., 46 (5) (Oct. 1999) 960–971.

[4] P. Curtis, The fundamentals of power quality and their associated problems, IEEE Press, Wiley, 2007.

[5] M. El-Habrouk, M.K. Darwish, P. Mehta, Active power filters: a review, IEE Proc., Electr. Power Appl. 147 (5) (2000) 403, https://doi.org/10.1049/ipepa: 20000522.

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