TY - GEN
T1 - Utility scale interface for renewables and storage using a power electronic transformer with back-to-back MMCs
T2 - 2017 North American Power Symposium, NAPS 2017
AU - Vipin, Vishnu Narayan
AU - Kshirsagar, Abhijith
AU - Opila, Daniel
AU - Mohan, Ned
PY - 2017/11/13
Y1 - 2017/11/13
N2 - The utility-scale renewables, PV and wind, are already approaching grid parity. To further enhance their penetration rapidly requires additional cost reduction and increased efficiency. There are other applications in utility-scale energy storage systems and in substations with power ratings in MW range for rapid charging of multiple electric vehicles. Towards this goal, one approach to interface with grid voltages of up to 34.5 kV is to use Power Electronic Transformers (PETs) consisting of back-to-back MMCs (Modular Multilevel Converters) and a high-frequency transformer. The control in such systems is challenging because of the lack of significant energy storage in the dc link between the two MMCs, unlike those in applications such as HVDC transmission and medium-voltage motor drives. Constraints on the modulation scheme under such conditions are pointed out and a novel control scheme is proposed in this paper that results in a ripple-free voltage dc link voltage, but controllable, between the two MMCs, reduced ripple in the capacitor voltages in each MMC module, and low THD in the ac currents at the terminals of the MMCs. Using this control scheme, the operation at controllable power factor and under unbalanced grid conditions is investigated and the simulation results are presented.
AB - The utility-scale renewables, PV and wind, are already approaching grid parity. To further enhance their penetration rapidly requires additional cost reduction and increased efficiency. There are other applications in utility-scale energy storage systems and in substations with power ratings in MW range for rapid charging of multiple electric vehicles. Towards this goal, one approach to interface with grid voltages of up to 34.5 kV is to use Power Electronic Transformers (PETs) consisting of back-to-back MMCs (Modular Multilevel Converters) and a high-frequency transformer. The control in such systems is challenging because of the lack of significant energy storage in the dc link between the two MMCs, unlike those in applications such as HVDC transmission and medium-voltage motor drives. Constraints on the modulation scheme under such conditions are pointed out and a novel control scheme is proposed in this paper that results in a ripple-free voltage dc link voltage, but controllable, between the two MMCs, reduced ripple in the capacitor voltages in each MMC module, and low THD in the ac currents at the terminals of the MMCs. Using this control scheme, the operation at controllable power factor and under unbalanced grid conditions is investigated and the simulation results are presented.
KW - Back-to-Back MMCs
KW - Grid Integration
KW - Power Electronic Transformer
KW - Virtual DC link
KW - constraints on the modulating signal
KW - modified carrier phase shifts
UR - http://www.scopus.com/inward/record.url?scp=85040621437&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85040621437&partnerID=8YFLogxK
U2 - 10.1109/NAPS.2017.8107334
DO - 10.1109/NAPS.2017.8107334
M3 - Conference contribution
AN - SCOPUS:85040621437
T3 - 2017 North American Power Symposium, NAPS 2017
BT - 2017 North American Power Symposium, NAPS 2017
PB - Institute of Electrical and Electronics Engineers Inc.
Y2 - 17 September 2017 through 19 September 2017
ER -
