Modified Seven-Level Pack U-Cell Inverter for Photovoltaic Applications

ABSTRACT:

This paper proposes a modified configuration of single-phase Pack U-Cell (PUC) multilevel inverter in which the output voltage has higher amplitude than the maximum DC link value used in the topology as a boost operation. The introduced inverter generates seven-level AC voltage at the output using two DC links and six semiconductor switches. Comparing to cascaded H-bridge and neutral point clamp multilevel inverters, the introduced multilevel inverter produces more voltage levels using less components. The proposed inverter is used in PV system where the green power comes from two separate PV panels connected to the DC links through DC-DC converters to draw the maximum power. Due to boost operation of this inverter, two different PV panels can combine and send their powers to the grid. Simulations and experimental tests are conducted to investigate the good dynamic performance of the inverter in grid-connected PV system.

KEYWORDS:

1.      PV Inverter

2.      Pack U-Cell

3.      Modified Pack U-Cell

4.      PUC5

5.      MPUC5

6.      Power Quality

7.      Renewable Energy Conversion

SOFTWARE: MATLAB/SIMULINK

CONCLUSION:

 In this paper a modified multilevel inverter topology has been presented. The proposed MPUC inverter can generate 7-level voltage waveform at the output with low harmonic contents. Unlike the reported PUC topology, the 7-level MPUC inverter is capable to produce voltage levels more than the DC sources used in the structure. It can sum up the DC buses amplitudes to deliver more power to the output. The associated switching algorithm has been designed and implemented on the introduced MPUC topology with reduced switching frequency aspect. Moreover, photovoltaic application has been targeted for this inverter to deliver power from PV panels with different voltage/current rating to grid. In this regard, results have been shown to validate the acceptable voltage regulation and current controlling of the grid-connected inverter as well as the implemented P&O MPPT algorithm.

REFERENCES:

[1] B. Singh, A. Chandra, and K. Al-Haddad, Power Quality: Problems and Mitigation Techniques: John Wiley & Sons, 2014.

[2] I. Gowaid, G. Adam, A. Massoud, S. Ahmed, and B. Williams, "Hybrid and Modular Multilevel Converter Designs for Isolated HVDC-DC Converters," IEEE Journal Emerg. and Select. Topics in Power Electron., vol. PP, no. 99, p. 1, 2017.

[3] H. Vahedi, K. Al-Haddad, Y. Ounejjar, and K. Addoweesh, "Crossover Switches Cell (CSC): A New Multilevel Inverter Topology with Maximum Voltage Levels and Minimum DC Sources," in IECON 2013-39th Annual Conference on IEEE Industrial Electronics Society, Austria, 2013, pp. 54-59.

[4] P. W. Hammond, "A new approach to enhance power quality for medium voltage drives," in Petroleum and Chemical Industry Conference, 1995. Record of Conference Papers., Industry Applications Society 42nd Annual, 1995, pp. 231-235.

[5] A. Nabae, I. Takahashi, and H. Akagi, "A new neutral-point-clamped PWM inverter," IEEE Trans. Ind. Applications, no. 5, pp. 518-523, 1981.