A Novel Hybrid Integrated
Adel M. Sharaf Mohamed A. H.
Centre of Energy Studies
University of Trinidad and Tobago
Point Lisas Campus, Esperanza Road, Brechin Castle, Couva elsmah@hotmail.cm
I.INTRODUCTION
In remote isolated areas and arid communities such as small islands, diesel generator sets and micro gas turbines are usually the main source of power supply. Fossil fuel for electricity generation has several drawbacks: it is costly due to transportation to the remote areas and it causes global warming pollution and green house gases. The need to provide an economical, viable and environmental safe alternative renewable green energy source is very important. As green renewable energy resources such as wind and Photovoltaic (PV) have gained great acceptance as a substitute for conventional costly and scare fossil fuel energy resources.
The equivalent

A k T c 
I p h + I 0 
I c 


V c = 

ln 


R s I C 
e 
I 0 






Where,
e: electron charge (1.602 Ã—
k: Boltzmann constant (1.38 Ã—
Iph: photocurrent, function of irradiation level and junction temperature (5 A).
I0: reverse saturation current of diode (0.0002 A). Rs: series resistance of cell (0.001 ).
Tc: reference cell operating temperature (20 Â°C). Vc: cell output voltage (V).
A: a curve fitting constant(100).
The output DC voltage, current and power of any photovoltaic PV array vary as a function of the solar Insolation/Irradiation level (Sx), junction temperature (Tc), ambient temperature (Ta), and varying electric DC load demand. As a result, the effect of all these varying ambient parameters should be considered while designing any efficient PV power tracking controller, it should be mentioned that the maximum power generated by the PV cell and PV arrays is also function of the solar irradiation level and operating junction/ambient temperature, and should be tracked for better operational performance and maximum energy utilization [4, 5].
The current research deals with the efficient utilization and low impact of PV panels as well as novel control concepts of power matching and decoupled interfacing topologies. Thereby, the interaction of PV source with power system and converters
1244 
Authorized licensed use limited to: Felix Raja S V. Downloaded on October 11, 2009 at 07:56 from IEEE Xplore. Restrictions apply.
feeding motors, choppers and dynamic controllers are crucial
PMDC generators are usually preferable due to their reliability, durability, low cost, low voltage characteristics, positive coefficient of conversion between electrical and mechanical parts, sizing and design flexibility. A permanent magnet direct current (PMDC) generator converts mechanical energy provided by wind kinetic energy to electrical power provided by a spinning rotor by means of magnetic coupling. The parameters and symbols which were used in simulating the system are given in Appendix of the paper. The armature coil of the DC generator is represented by an inductance (Lm) in series with resistance (Rm) in series with an induced voltage (Em). A differential equation for the equivalent circuit is derived by using Kirchhoffâ€™s voltage law around the electrical loop.
E=Ke.Ï‰ 
(2) 
(3) 
PMDC generator Load Equations can be expressed by:
TT = PT / Ï‰ 
(4) 
TG=KTI 
(5) 
(6) 
Where Ï‰ is the generator angular velocity, TG is the generator torque, TT is the wind turbine torque, KT is the torque constant and J, B are the generator inertia and friction coefficients.
An effective approach is to ensure renewable energy diversity and effective utilization by combining these different renewable energy sources to form a coordinated and hybrid integrated energy system. Hybrid green energy system is a valid alternative solution for small scale
II LAYOUT OF THE STUDIED GREEN ENERGY
SYSTEM
The paper presents a hybrid dual wind/PV system for supplying an isolated community with electrical energy. In order to obtain electricity from the hybrid green system at an economical price, its topology and control design must be optimized in terms of coordinated operation and layout configuration. Many topologies are currently available for hybrid green system configurations, depending on the use of interface converters based on common DC/common AC bus interface architecture.
Solar panels can be connected in parallel or in series to obtain required photovoltaic power rating power rating. The power obtained by this way is DC in nature and it should be converted to AC for some AC type loads. Therefore, DC to AC converters are required for such load types. Electrical energy is not only required during day time, but also at night. This key requirement puts forwards the possible use of other renewable green energy sources, such as wind energy, tidal/wave and fuel cells in hybrid micro
The wind energy scheme with PMDC generator could be directly connected to the common DC bus through
Fig.(1) Hybrid Integrated
Energy Scheme for Village Electricity
scheme with common DC/ common AC collection bus interface. The scheme uses a primary common DC bus collection with an added secondary common AC bus for feeding any AC loads. The proposed hybrid green energy scheme is digitally simulated for different operation conditions
1245
Authorized licensed use limited to: Felix Raja S V. Downloaded on October 11, 2009 at 07:56 from IEEE Xplore. Restrictions apply.
and load excursions. The proposed control scheme comprises novel
III COORDINATED ERROR DRIVEN
CONTROLLER
Figure (2) shows the general four regulator coordinated control structure. The hybrid system was digitally simulated and validated using MATLAB/Simulink
Fig. (2) Structure of Coordinated error driven
The main controller comprises the following four regulators:
(1)
(2)
(3)MPFC regulator for ripple minimization of


1 


Vr 






1 
Gain 1 
1 




Vdc 

10 



1 







Transfer Fcn 2 




Gain 3 


1 



1 




2 

Transfer Fcn 3 








Gain 5 



















Idc 


























1 








0.5 



Gain 4 






















10 












Transfer Fcn 1 




Gain 2 

















































































































































PI 






Signal(s)Pulses 

1 
























Out 1 

Saturation 








Discrete 








PWM Generator 1 

PI Controller
Transport
Delay 1
Fig.
The


1 



Vr 



1 
Gain 1 








Wwnd 







1 



1 
Gain 3 








10 




Transfer Fcn 2 


2 









Iwnd 

1 



Gain 4 









Transfer Fcn 1 
Gain 2 









PI 
Signal(s)Pulses 








Discrete 
Saturation 



PI Controller 
PWM Generator 1 


Transport 









Delay 1 


(4)



1 



Out 1 
Figure (3 
Fig. 




1246
Authorized licensed use limited to: Felix Raja S V. Downloaded on October 11, 2009 at 07:56 from IEEE Xplore. Restrictions apply.




1 




Out1 


RMS 




RMS 

2 






1 


Out 2 





1 





.5 



Vac 




Transfer Fcn 2 










Gain 2 









Gain 4 




Transport 




Delay 1 





.5 




Gain 3 





PI 
Signal(s)Pulses 

1 

Discrete 
Saturation 

u 
PWM Generator 1 






PI Controller 



10 




Transfer Fcn 3 
Abs 










Scope 1 

Fig.




1 




Out1 


RMS 




RMS 

2 






1 


Out 2 





1 





.5 



Vac 




Transfer Fcn 2 










Gain 2 









Gain 4 




Transport 




Delay 1 





.5 




Gain 3 





PI 
Signal(s)Pulses 

1 

Discrete 
Saturation 

u 
PWM Generator 1 






PI Controller 







Transfer Fcn 3 
Abs 










Scope 1 

Fig.
IV. DIGITAL SIMULATION RESULTS
The unified
electronic interface converters, namely
Figures (4 6) show the digital simulation of the unified system dynamic responses of
V CONCLUSIONS
The paper presents a novel coordinated hybrid Wind/PV green energy utilization scheme for Village/Island
REFERENCES
[1]I. Altas, A. Sharaf, â€œNovel maximum power fuzzy logic controller for photovoltaic solar energy systemsâ€, Renewable Energy, vol. 33, pp 388 399, 2008.
1247
Authorized licensed use limited to: Felix Raja S V. Downloaded on October 11, 2009 at 07:56 from IEEE Xplore. Restrictions apply.
[2]A. Sharaf, R. Chhetri, â€œA novel dynamic capacitor compensator/green plug scheme for
[3]H. Fargali, F. Fahmy, M. A.
[4]A. M. sharaf, G. Wang, â€œVoltage stabilization of standalone wind energy conversion system using active power compensatorâ€, International journal of global energy issues, vol.26 No.
[5]Wind power in power systems, edited by T. Ackermann, John Wiley &Sons, 2005
[6]E. Muljadi and C.P. Butterfield, â€œDynamic Model for Wind Farm Power Systems,â€ Global Wind Power Conference, Chicago, Illinois, March/April 2004.
[7]I. H. Altas, A. M. Sharaf, â€œ A
[8]Naik, R.; Mohan, N.; Rogers, M.; Bulawka, A.; A novel grid interface, optimized for
systems 

Power Delivery, IEEE Transactions on Volume 10, 
Issue 4, Oct. 1995 
Page(s):1920 â€“ 1926. 

[9]J.J. Brey, A. Castro, E. Moreno and C. Garcia, "Integration of Renewable Energy Sources as an Optimized Solution for Distributed Generation," 28th Annual Conference of the Industrial Electronics Society 2002, vol. 4,
[10]Adel M. Sharaf, Mohamed A. H.
[11]A.M. Sharaf, Mohamed S.
Appendix for Simulated System Parameters
PV Array:
Vpv = 200 V DC
Ppv= 10 kW
PMDC wind driven generator parameters:
Ra = resistance of armature winding=0.1
La = inductance of armature winding=5 mH
Km=voltage constant= 1.273 V/rad
Kt =torque constant = 1.273 Nm/A
Jm =moment of inertia=0.75 kgm2
Bm=Viscous constant=0.14 Vs/rad
Va=nominal armature voltage=240 V
Static
DC Heating Load = 10 kW
DC Lighting Load =5 kW
Static
AC load 
= 10 kW 
Modulated Filter at AC Bus:
C1=C2 = 85 Âµf
Rf= 0.05
Lf= 0.1 H
PI controller parameters:
PV and Wind
Inverter and Modulated Power Filter Compensator : Kp =4.5 and KI =1.25
Fig.(4) Common DC bus voltage dynamic Response under varying DC loading and Wind Conditions (increased static load by 33.3% at t=6 s, decrease wind speed by 50% at t=10 s for 2 s)
1248
Authorized licensed use limited to: Felix Raja S V. Downloaded on October 11, 2009 at 07:56 from IEEE Xplore. Restrictions apply.
Fig.(5) Speed Dynamic Response of Wind Driven PMDC Generator under varying
Fig. (7) Dynamic Response of the PV array voltage under varying
Fig (6) Common AC bus voltage Dynamic Response at Inverter Interface using interface inverter
Fig. (8) Dynamic Response of the PV array Generated Current under varying
1249
Authorized licensed use limited to: Felix Raja S V. Downloaded on October 11, 2009 at 07:56 from IEEE Xplore. Restrictions apply.