ABSTRACT:
This
paper proposed a grid connected solar Photovoltaic (PV) Systems with a new
voltage balancing converter suitable for Neutral-Point-Clamped (NPC) Multilevel
Inverter (MLI). The switched capacitors used in the proposed converter is able
to balance the DC link capacitor voltage effectively by using proper switching
states. The proposed balancing converter can be extended to any higher levels
and it can boost the DC input voltage to a higher voltage levels without using
any magnetic components. This feature allows the converter to operate with the
boosting capability of the input voltage to the desired output voltage while
ensuring the self-balancing. In this paper the proposed converter is used for a
grid connected solar PV system with NPC multilevel inverter, which is
controlled using vector control scheme. The proposed grid connected solar PV
system with associated controllers and maximum power point tracking (MPPT) is implemented
in Matlab/SimPowerSystem and experimentally validated using dSPACE
system and designed converters. The simulation and experimental results show
that the proposed topology can effectively balance the DC link voltage, extract
maximum power from PV module and inject power to the grid under varying solar
irradiances with very good steady state and dynamic performances.
KEYWORDS:
1. Solar
photovoltaics
2. NPC
multilevel inverter
3. Balancing
circuit
4. Dc-link
voltage balancing
5. Grid
connected PV system
SOFTWARE:
MATLAB/SIMULINK
CONCLUSION:
A
new step-up voltage balancing converter for solar photovoltaic system which is
suitable for NPC-MLI has been proposed in this paper. The proposed converter
not only can boost the input PV voltage at the desired output level, but also can
remove the magnetic elements which reduces the weight and cost of the system.
It also requires only one DC source or PV array output to produce multi-level
output, which reduces the number of input voltage sources required in such
systems. Capacitance calculation, voltage ripple of the capacitors, output power
and normalized energy according to the number of output levels are also
analyzed. A deep comparison with other DC-DC topologies has been done and
showed the cost effectiveness of the proposed converter. The proposed converter
is implemented for a grid connected solar PV system with a NPC multilevel
inverter, which is controlled using vector control scheme. The proposed system
with associated controllers is implemented in Matlab/SimPowerSystem and experimentally
validated using dSPACE DSP (digital signal processor) system and designed
converters. The simulation and experimental results confirms that the proposed
topology can effectively balance the DC link voltage, extract maximum power
from PV module and inject power to the grid under varying solar irradiances
with very good steady state and dynamic performances.
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