ABSTRACT:
This paper presents a green energy solution to a microgrid
for a location dependent on a diesel generator (DG) to meet its electricity
requirement. The proposed microgrid is powered by two renewable energy sources
such as wind energy conversion system (WECS) using doubly fed induction generator
(DFIG) and solar photovoltaic (PV) system. The solar PV array is directly
connected to common DC bus of back-back voltage source converters (VSCs), which
are connected in the rotor side of DFIG. Moreover, a battery energy storage
(BES) is connected at the same DC bus through a buck-boost DC-DC converter to
provide path for excess stator power of DFIG. The extraction of maximum power
both from wind and solar is achieved through rotor side converter (RSC) control
and buck-boost DC-DC converter control, respectively. A modified perturb and
observe (P&O) algorithm is presented to extract maximum power from the
solar PV array. Moreover, the control of load side converter (LSC), is designed
to optimize the fuel consumption of DG. A novel generalized concept is proposed
to compute the reference DG power output for optimal fuel consumption. The
microgrid is modelled and simulated using SimPowerSystems tool box of MATLAB,
for various scenarios such as varying wind speeds, varying insolation, effect
of load variation on bidirectional converter and unbalanced nonlinear load
connected at point of common coupling (PCC). The DFIG stator currents and DG currents,
are found balanced and sinusoidal. Finally, an experimental prototype is
developed in the laboratory to validate the proposed scheme.
KEYWORDS:
1.
Wind Turbine
2.
Doubly fed induction generator (DFIG)
3.
Diesel generator
4.
Solar photovoltaic array
5.
Bidirectional buck boost converter
6.
Battery energy storage
7.
Power quality
SOFTWARE:
MATLAB/SIMULINK
CONCLUSION:
The
proposed microgrid based on wind turbine driven DFIG, DG and solar PV array
with BES, has been presented. The solar PV array is directly connected to DC link
of back-back connected VSCs, whereas BES is connected through buck-boost
converter. The system has been simulated for various scenarios such as variable
wind speeds, variable insolation and unbalanced nonlinear load connected at
PCC. Moreover, the performance of buckboost converter at change in load has
been investigated. The simulated results have shown the satisfactory
performance to achieve optimal fuel consumption. The DFIG stator voltages,
currents and DG currents, are found balanced and sinusoidal, as per the IEEE
519 standard. A prototype has been developed in the laboratory to validate the
performance of the microgrid. Test results have shown quite good performance
under variable wind speeds, variable insolation and change in load.
REFERENCES:
[1] J. Knudsen, J. D. Bendtsen, P. Andersen,
K. K. Madsen, and C. H. Sterregaard, “Supervisory control implementation on
diesel-driven generator sets,” IEEE Trans. Ind. Electron., vol. 65, no.
12, pp. 9698- 9705, Dec. 2018.
[2]
J. Jo, H. An, and H. Cha, “Stability improvement of current control by voltage
feedforward considering a large synchronous inductance of a diesel generator,” IEEE
Trans. Ind. Applicat., vol. 54, no. 5, pp. 5134- 5142, Sept.-Oct. 2018.
[3]
Y. Zhang, A. Melin, S. M. Djouadi, M. Olama, and K. Tomsovic, “Provision for
guaranteed inertial response in diesel-wind systems via model reference
control,” IEEE Trans. Power Systems, Early Access.
[4]
N. Nguyen-Hong, H. Nguyen-Duc, and Y. Nakanishi, “Optimal sizing of energy
storage devices in isolated wind-diesel systems considering load growth
uncertainty,” IEEE Trans. Ind. Applicat., vol. 54, no. 3, pp. 1983-1991,
May-June 2018.
[5]
W. Li, P. Chao, X. Liang, J. Ma, D. Xu, and X. Jin, “A practical equivalent
method for DFIG wind farms,” IEEE Trans. Sustain. Energy, vol. 9, no. 2,
pp. 610-620, April 2018.
