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Title: A Modular Multilevel Converter with Power Mismatch Control for Grid-Connected Photovoltaic Systems

A modular multilevel power converter configuration for grid connected photovoltaic (PV) systems is proposed. The converter configuration replaces the conventional bulky line frequency transformer with several high frequency transformers, potentially reducing the balance of systems cost of PV systems. The front-end converter for each port is a neutral-point diode clamped (NPC) multi-level dc-dc dual-active bridge (ML-DAB) which allows maximum power point tracking (MPPT). The integrated high frequency transformer provides the galvanic isolation between the PV and grid side and also steps up the low dc voltage from PV source. Following the ML-DAB stage, in each port, is a NPC inverter. N number of NPC inverters’ outputs are cascaded to attain the per-phase line-to-neutral voltage to connect directly to the distribution grid (i.e., 13.8 kV). The cascaded NPC (CNPC) inverters have the inherent advantage of using lower rated devices, smaller filters and low total harmonic distortion required for PV grid interconnection. The proposed converter system is modular, scalable, and serviceable with zero downtime with lower foot print and lower overall cost. A novel voltage balance control at each module based on power mismatch among N-ports, have been presented and verified in simulation. Analysis and simulation results are presented for the N-portmore » converter. The converter performance has also been verified on a hardware prototype.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Univ. of Texas, San Antonio, TX (United States). Dept. of Electrical and Computer Engineering
Publication Date:
Grant/Contract Number:
EE0006323
Type:
Accepted Manuscript
Journal Name:
Energies (Basel)
Additional Journal Information:
Journal Name: Energies (Basel); Journal Volume: 10; Journal Issue: 5; Journal ID: ISSN 1996-1073
Publisher:
MDPI AG
Research Org:
Univ. of Texas, San Antonio, TX (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
24 POWER TRANSMISSION AND DISTRIBUTION; 14 SOLAR ENERGY; dual active bridge; maximum power point tracking (MPPT); multilevel; neutral-point clamped; utility scale photovoltaic (PV) system
OSTI Identifier:
1393537

Duman, Turgay, Marti, Shilpa, Moonem, M. A., Kader, Azas Ahmed Rifath Abdul, and Krishnaswami, Hariharan. A Modular Multilevel Converter with Power Mismatch Control for Grid-Connected Photovoltaic Systems. United States: N. p., Web. doi:10.3390/en10050698.
Duman, Turgay, Marti, Shilpa, Moonem, M. A., Kader, Azas Ahmed Rifath Abdul, & Krishnaswami, Hariharan. A Modular Multilevel Converter with Power Mismatch Control for Grid-Connected Photovoltaic Systems. United States. doi:10.3390/en10050698.
Duman, Turgay, Marti, Shilpa, Moonem, M. A., Kader, Azas Ahmed Rifath Abdul, and Krishnaswami, Hariharan. 2017. "A Modular Multilevel Converter with Power Mismatch Control for Grid-Connected Photovoltaic Systems". United States. doi:10.3390/en10050698. https://www.osti.gov/servlets/purl/1393537.
@article{osti_1393537,
title = {A Modular Multilevel Converter with Power Mismatch Control for Grid-Connected Photovoltaic Systems},
author = {Duman, Turgay and Marti, Shilpa and Moonem, M. A. and Kader, Azas Ahmed Rifath Abdul and Krishnaswami, Hariharan},
abstractNote = {A modular multilevel power converter configuration for grid connected photovoltaic (PV) systems is proposed. The converter configuration replaces the conventional bulky line frequency transformer with several high frequency transformers, potentially reducing the balance of systems cost of PV systems. The front-end converter for each port is a neutral-point diode clamped (NPC) multi-level dc-dc dual-active bridge (ML-DAB) which allows maximum power point tracking (MPPT). The integrated high frequency transformer provides the galvanic isolation between the PV and grid side and also steps up the low dc voltage from PV source. Following the ML-DAB stage, in each port, is a NPC inverter. N number of NPC inverters’ outputs are cascaded to attain the per-phase line-to-neutral voltage to connect directly to the distribution grid (i.e., 13.8 kV). The cascaded NPC (CNPC) inverters have the inherent advantage of using lower rated devices, smaller filters and low total harmonic distortion required for PV grid interconnection. The proposed converter system is modular, scalable, and serviceable with zero downtime with lower foot print and lower overall cost. A novel voltage balance control at each module based on power mismatch among N-ports, have been presented and verified in simulation. Analysis and simulation results are presented for the N-port converter. The converter performance has also been verified on a hardware prototype.},
doi = {10.3390/en10050698},
journal = {Energies (Basel)},
number = 5,
volume = 10,
place = {United States},
year = {2017},
month = {5}
}

Works referenced in this record:

A Review of Single-Phase Grid-Connected Inverters for Photovoltaic Modules
journal, September 2005
  • Kjaer, S. B.; Pedersen, J. K.; Blaabjerg, F.
  • IEEE Transactions on Industry Applications, Vol. 41, Issue 5, p. 1292-1306
  • DOI: 10.1109/TIA.2005.853371