This
study proposes a single-stage solar photovoltaic energy conversion system
(PV-ECS) integrated to a three phase four-wire (3P4W) distribution grid with
dual-function capabilities, i.e. active power transfer and power quality (PQ) enhancement
at the point of interaction (PoI). The PV-ECS system comprises of a solar
photovoltaic array and a voltage source inverter (VSI), supplying active power
(during daytime) to the distribution grid and connected single-phase and
three-phase loads. Apart from transfer of power, the system also improves the
PQ at the PoI by compensating reactive power and neutral current, attenuating
harmonics, correcting power factor and balancing grid currents. During night,
the VSI acts as a shunt active power filter mitigating PQ issues, thereby
increasing the device utilisation factor. A three-phase magnitude-phase locked
loop (3M-PLL) method is utilised to extract and estimate fundamental term of
load currents and an incremental conductance algorithm is applied for maximum
power point tracking. To demonstrate its effectiveness, the system is modelled
and its performance is simulated on MATLAB and experiments are performed on a
developed prototype in the laboratory.
SOFTWARE: MATLAB/SIMULINK
Fig. 1 System configuration and control scheme
(a) Structure diagram of 3P4W grid-connected
PV-ECS
EXPECTED SIMULATION RESULTS
Fig. 2 Dynamic behaviour of system at
(a),
(b) Unbalanced
load, (c) Step increase in irradiance from 700 to 1000 W/m2
CONCLUSION:
A
dual-function single-stage PV-ECS integrated to the 3P4 distribution grid has
been proposed here. Two modes of operation of PV-ECS are to supply and transfer
active power to the grid and tied loads as well as to improve quality of power
at PoI. An In Cbased approach is
utilised here for tracking MPP of solar PV array and a 3M-PLL-based control
scheme is utilised for extracting fundamental
components of load current. Simulated and test results have demonstrated the
performance of the system under various conditions such as non-linear loading,
unbalanced loading and varying irradiance levels. Test results have shown that
the system has improved the power quality at the PoI by compensating neutral current
and reactive power, correcting power factor and balancing loads on the grid
side. The harmonics are reduced to below 5% on grid side, which is within the
limits of an IEEE-519 standard. Moreover, test results have indicated that the
system has operated suitably during night-time (sunlight unavailability)
thereby increasing the utilisation factor of the VSI by two-fold. The single stage
structure has decreased the losses in the system and increased the total
efficacy of the system.
REFERENCES:
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in tariffs – benefits all consumers’, 30 May 2016. Available at http:// reneweconomy.com.au/2016/rooftop-solar-net-metering-is-a-netbenefit-
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[2] Meza, E.: ‘India implements new 40 GW rooftop, small PV plant
program’, 20 May 2016. Available at http://www.pv-magazine.com/news/details/beitrag/ india-implements-new-40-gw-rooftop--small-pv-plant-program-_100024678/
#axzz4ADc3MIV6
[3] Deo, S., Jain, C., Singh, B.: ‘A PLL-less scheme for
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