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Reducing Harmonic Distortion in Three-phase Parallel UPS Configuration with Nonlinear Load Using Disturbance Observer

Valizade Alavi, Shahab | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50018 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Tahami, Farzad
  7. Abstract:
  8. Three-phase inverters as a UPS are very common in industry and non-linear loads such as rectifiers are growing in industry. Three phase inverter with non-linear load can lead to highly distorted output voltage which can make problem for sensitive loads such as servers etc. Parallel configuration of three-phase inverters, also have the same problem with non-linear loads. Droop control and Master/slave control methods are two major methods which investigated in this thesis. This paper proposes a method for reducing voltage THD in three phase inverters with non-linear load. The proposed method considers the load current as a disturbance and provide a control strategy to reject it using the disturbance observer method. This method doesn’t need any additional sensors or hardware and is implemented digitally in controller. Simulation results show that the presented method will reduce the total harmonic distortion of the output voltage. Also this method is investigated in parallel configuration of inverters. For droop control method, disturbance rejection should implement on each paralleled inverter but for Master/slave method, disturbance rejection should be implemented only for the master inverter. Simulation results show that disturbance rejection method based on Disturbance observer works well and reduce output voltage THD. Also the proposed method is investigated on a 1KW three-pase inverter which implemented experimentally and results show that the disturbance rejection method based on disturbance observer, reduces output voltage THD in non-linear loads
  9. Keywords:
  10. Total Harmonic Distortion ; Nonlinear Load ; Power Supply ; Three Phase Inverter ; Disturbance Observer

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