ABSTRACT:
A quasi-Z-source inverter (qZSI) could achieve buck/boost
conversion as well as dc to ac inversion in a single-stage topology, which
reduces the structure cost when compared to a traditional two-stage inverter.
Specifically, the buck/boost conversion was accomplished via shoot-through
state which took place across all phase legs of the inverter. In this paper,
instead of using traditional dual-loop-based proportional integral (PI)-P
controller, a type 2 based closed-loop voltage controller with novel dc-link
voltage reference algorithm was proposed to fulfill the dc-link voltage tracking
control of a single-phase qZSI regardless of any loading conditions, without
the need of inner inductor current loop. A dc–ac boost inverter with similar
circuit parameters as a Qzsi was used to verify the flexibility of the proposed
controller. The dynamic and transient performances of the proposed controller were
investigated to evaluate its superiority against the aforementioned conventional
controller. The integrated proposed controller and qZSI topology was then
employed in static synchronous compensator application to perform reactive
power compensation at the point of common coupling. The effectiveness of the
proposed approach was verified through both simulation and experimental studies.
KEYWORDS:
1. Control system analysis
2. Flexible ac transmission systems
3. Quasi-Z-source inverter (qZSI)
4. Reactive power control
5. Static volt-ampere reactive (VAR) compensators.
SOFTWARE:
MATLAB/SIMULINK
CONCLUSION:
A
voltage controller based on type 2 compensator incorporating a novel dc-link
voltage reference algorithm was proposed for single-phase dc–ac boost inverter
and qZSI topologies. When compared with the traditional dual-loop-based PI-P
controller, the proposed controller showed simpler design procedures to attain its
control parameters without using trial and error method. In addition, the
proposed controller demonstrated stability and excellent dynamic and transient
performances even though Qzsi was operating in discontinuous conduction mode.
Furthermore, constant qZSI dc-link voltage was achieved by the proposed dc-link
voltage reference algorithm regardless of any loading conditions. The proposed
qZSI was employed in STATCOM application to perform reactive power compensation
at the PCC, where all the aforementioned advantages were realized in both the
simulation and experimental works.
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