ABSTRACT:
A new topology
of a hybrid distributed generator based on photovoltaic and wind-driven
permanent magnet synchronous generator is proposed. In this generator, the
sources are connected together to the grid with the help of only a single boost
converter followed by an inverter. Thus, compared to earlier schemes, the proposed
scheme has fewer power converters. A model of the proposed scheme in the d −
q-axis reference frame is developed. Two low-cost controllers are also
proposed for the new hybrid scheme to separately trigger the dc–dc converter
and the inverter for tracking the maximum power from both sources. The integrated
operations of both proposed controllers for different conditions are
demonstrated through simulation and experimentation. The steady-state performance
of the system and the transient response of the controllers are also presented
to demonstrate the successful operation of the new hybrid system. Comparisons of
experimental and simulation results are given to validate the simulation model.
KEYWORDS:
1. Grid-connected hybrid system
2. Hybrid distributed generators (DGs)
3. Smart grid
4. Wind-driven PMSG–PV
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig. 1. Proposed DG system based on PMSG–PV
sources.
EXPECTED SIMULATION RESULTS:
Fig. 2. DC link
steady-state waveforms. (a) Experimental (voltage—50 V/div, current—10 A/div,
and time—500 ms/div). (b) Simulated (voltage—20 V/div, current—5 A/div, and
time—500 ms/div.
Fig. 3. Steady-state grid voltage and current
waveforms. (a) Experimental (voltage—50 V/div, current—10 A/div, and time—20
ms/div). (b) Simulated (voltage—50 V/div, current—5 A/div, and time— 20
ms/div).
Fig.4. Transient response for a step change
in PMSG shaft speed. (a) Changes in rectifier output voltage and duty cycle of
the boost converter. (b) Changes in dc-link voltage and current. (c) Changes in
grid current.
CONCLUSION:
A new reliable hybrid DG system based on
PV and wind driven PMSG as sources, with only a boost converter followed by an
inverter stage, has been successfully implemented. The mathematical model developed
for the proposed DG scheme has been used to study the system performance in
MATLAB. The investigations carried out in a laboratory prototype for different
irradiations and PMSG shaft speeds amply confirm the utility of the proposed
hybrid generator in zero-net-energy buildings. In addition, it has been established
through experimentation and simulation that the two controllers, digital MPPT controller
and hysteresis current controller, which are designed specifically for the
proposed system, have exactly tracked the maximum powers from both sources. Maintenance-free
operation, reliability, and low cost are the features required for the DG employed
in secondary distribution systems. It is for this reason that the developed
controllers employ very low cost microcontrollers and analog circuitry.
Furthermore, the results of the experimental investigations are found to be
matching closely with the simulation results, thereby validating the developed
model. The steady state waveforms captured at the grid side show that the power
generated by the DG system is fed to the grid at unity power factor. The
voltage THD and the current THD of the generator meet the required power quality
norms recommended by IEEE. The proposed scheme easily finds application for
erection at domestic consumer sites in a smart grid scenario.
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