ABSTRACT:
In this paper,
a novel algorithm, based on dc link voltage, is proposed for effective energy
management of a standalone permanent magnet synchronous generator (PMSG)-based variable
speed wind energy conversion system consisting of battery, fuel cell, and dump
load (i.e., electrolyzer). Moreover, by maintaining the dc link voltage at its
reference value, the output ac voltage of the inverter can be kept constant
irrespective of variations in the wind speed and load. An effective control
technique for the inverter, based on the pulse width modulation (PWM) scheme,
has been developed to make the line voltages at the point of common coupling
(PCC) balanced when the load is unbalanced. Similarly, a proper control of
battery current through dc–dc converter has been carried out to reduce the
electrical torque pulsation of the PMSG under an unbalanced load scenario.
Based on extensive simulation results using MATLAB/SIMULINK, it has been
established that the performance of the controllers both in transient as well
as in steady state is quite satisfactory and it can also maintain maximum power
point tracking.
KEYWORDS:
1. DC-side active filter
2. Permanent magnet synchronous generator (PMSG)
3. Unbalanced load compensation
4. Variable speed wind turbine
5. Voltage control
SOFTWARE: MATLAB/SIMULINK
CIRCUIT DIAGRAM:
Fig.
1. PMSG-based standalone wind turbine with energy storage and dump load.
EXPERIMENTAL RESULTS:
Fig.
2. Response of mechanical torque for change in wind velocity.
Fig.
3. (a) Load current; (b) wind speed.
Fig.
4. DC link voltage.
Fig.
5. RMS output voltage (PCC voltage).
Fig.
6. Instantaneous output voltage at s.
Fig.
7. Instantaneous output line current.
Fig.
8. Powers.
Fig.
9. Powers.
Fig. 10. DC link voltage.
Fig.
11. Powers.
Fig.
12. DC link voltage.
Fig. 13. Response of controllers.
Fig.
14. Three phase currents for unbalanced load.
Fig.
15. Electrical torque of PMSG with and without dc–dc converter controller.
Fig.
16. Instantaneous line voltages at PCC for unbalanced load.
Fig. 17. (a) RMS value of line voltages at
PCC after compensation; (b) modulation
indexes.
Fig.
18. Instantaneous line voltages at PCC after compensation.
CONCLUSION:
Control strategies to regulate voltage
of a standalone variable speed wind turbine with a PMSG, battery, fuel cell,
and electrolyzer (acts as dump load) are presented in this paper. By maintaining
dc link voltage at its reference value and controlling modulation indices of the
PWM inverter, the voltage of inverter output is maintained constant at their
rated values. From the simulation results, it is seen that the controller can
maintain the load voltage quite well in spite of variations in wind speed and
load. An algorithm is developed to achieve intelligent energy management among
the wind generator, battery, fuel cell, and electrolyzer. The effect of
unbalanced load on the generator is analyzed and the dc–dc converter control
scheme is proposed to reduce its effect on the electrical torque of the
generator. The dc–dc converter controller not only helps in maintaining the dc
voltage constant but also acts as a dc-side active filter and reduces the oscillations
in the generator torque which occur due to unbalanced Load. PWM inverter control
is incorporated to make the line voltage at PCC balanced under an unbalanced
load scenario. Inverter control also helps in reducing PCC voltage excursion arising
due to slow dynamics of aqua elctrolyzer when power goes to it. The total
harmonic distortion (THD) in voltages at PCC is about 5% which depicts the good
quality of voltage generated at the customer end. The simulation results demonstrate
that the performance of the controllers is satisfactory under steady state as
well as dynamic conditions and under balanced as well as unbalanced load
conditions.
REFERENCES:
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