ABSTRACT
The
photovoltaic (PV) generation is increasingly popular nowadays, while typical
loads require more high-power quality. Basically, one PV generator supplying to
nonlinear loads is desired to be integrated with a function as an active power
filter (APF). In this paper, a three-phase three-wire system, including a
detailed PV generator, dc/dc boost converter to extract maximum radiation power
using maximum power point tracking, and dc/ac voltage source converter to act
as an APF, is presented. The instantaneous power theory is applied to design
the PV-APF controller, which shows reliable performances. The MATLAB/Simpower Systems
tool has proved that the combined system can simultaneously inject maximum
power from a PV unit and compensate the harmonic current drawn by nonlinear
loads.
KEYWORDS
1. Active
power filter (APF)
2. Instantaneous
power theory
3. Photovoltaic
(PV)
4. Power
quality
5. Renewable
energy
SOFTWARE:
MATLAB/SIMLINK
BLOCK DIAGRAM:
Figure 1. proposed design of PV-APF combination.
CONTROL DIAGRAM:
Figure 2. controller topology of dc/ac VSC in the
PV-APF combination.
EXPECTED SIMULATION
RESULTS:
Figure 3. output power of pv during running time.
Figure 4. duty cycle and vpv changed by mppt. (a)
output
voltage of pv unit. (b) duty cycle of mppt.
Figure 5. utility supplied current waveform.
Figure 6. utility supplied current and pcc voltage
waveform.
Figure 7. thd in four modes of pv system operation
while
utility supplies power. (a) dq-current mode. (b)
pv-apf mode.
(c) apf mode. (d) only utility supplies load.
Figure 8. pv supplied current waveform.
Figure 9. real power from the (a) utility, (b) pv
unit, and (c)
load, while the utility supplies power.
Figure 10. imaginary power from the (a) utility, (b)
pv unit,
and (c) load, while the utility supplies power.
Figure 11. utility received current waveform.
Figure 12. thd in four modes of pv system operation
while
utility receives power. (a) dq-current mode. (b)
pv-apf mode.
(c) apf mode. (d) only utility supplies load.
Figure 13. real power from the (a) utility, (b) pv
unit, and (c)
load, while the utility receives power.
Figure 14. imaginary power from the (a) utility, (b)
pv unit,
and (c) load, while the utility receives power.
CONCLUSION:
Regarding
the multifunctional DG concept, in this paper, a dynamic grid-connected PV unit
is built and the PV-APF combination system with a local controller is proposed.
The controller implements two purposes, which are supplying power from the PV
unit and filtering the harmonics of the local nonlinear load. The new
controller based on instantaneous power balance has been explained accordingly.
The MATLAB/Simpower Systems simulation shows good performances of this
controller. The positive influence of MPPT on maximizing PV power output is
also validated. The switching among three controllers to dc/ac VSC brings
different current waveforms. As a result, the conventional dq-current controller
should not be applied when PV is connected to a local nonlinear load regarding
power-quality viewpoint. Preferably, the PV-APF controller compensates the utility
currents successfully. While a PV unit is deactivated, the APF function can
still operate. It is, therefore, technically feasible for these power
electronics-interfaced DG units to actively regulate the power quality of the
distribution system as an ancillary service, which will certainly make those DG
units more competitive.
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