Transcript Poster_b

Simulink Modelling and Simulation of a Hydrogen Based
Photovoltaic/Wind Energy System
I
R H
Mamadou Lamine Doumbia, Kodjo Agbossou, and Évelyne Granger
Université du Québec à Trois-Rivières
Hydrogen Research Institute
Department of Electrical and Computer Engineering
Université du Québec à Trois-Rivières, C.P. 500
3351 boul. des Forges Trois-Rivières (Québec) Canada G9A 5H7
Institut de recherche sur l’hydrogène
ABSTRACT – This paper presents a dynamic simulation model using Matlab/Simulink software to study the behavior of renewable energy systems with hydrogen storage (RESHS). The
complete system model is developed by integrating individual sub-units of the photovoltaic arrays, wind turbine, batteries, electrolyzer, fuel cell and power conditioning units. The sub-models
are valid for transient and steady state analysis as a function of voltage, current, and temperature. Such a global model is useful for optimal dimensioning and effective control design of the
RESHSs. The state of charge control method was chosen to validate the developed simulation models. The results confirmed previous experimental measurements on the test bench.
IV. BATTERY MODEL
I. INTRODUCTION
For many years, the Hydrogen Research Institute (HRI) has developed a renewable
photovoltaic/wind energy system based on hydrogen storage (Fig. 1). This system
operates using state-of-charge (SOC) control method. The control system verifies
the state of charge of the batteries and sends commands to the electrolyzer or the
fuel cell via DC/DC converters to manage energy production/consumption in the
system. In order to obtain more efficient control of the entire system, and particularly
in order to be able to study how it should be connected to the electrical grid, the
development of a general simulation model was undertaken. The main components
(photovoltaic array, wind turbine, electrolyzer and fuel cell) of the system were each
modelled and simulated, and then integrated into a global simulation model
designed to function like the real system. Matlab/Simulink software was used for this
purpose.
PV Array
Wind Turbine
The battery model presents the relation between voltage, current and the battery
state of charge Q. Two modes of operation are considered:
Discharge mode (I<0):


Md (C  Q)
C Q

V ( t )  Vd  g d
 Rd I  1 

C
C
(
1

C
)

(
C

Q
)
d


Charge mode (I>0):

M cQ 
Q


V ( t )  Vc  g c  1    Rc I  1 

C
CC c  Q 


I= battery current (A); V= battery voltage (V); C= battery capacity (Ah); Q=state of charge; T=
time (h); R= internal resistance (Ω); M, g= coefficients.
Critical Loads
Grid Connected Inverter
In our model, the coefficients g, R, C and M are expressed as a function of the
battery age.
V. ELECTROLYZER MODEL
Most of the commercially available electrolyzers run in current mode, according to a
polarization characteristic. This characteristic can be represented as a sum of linear,
logarithmic and exponential functions
BUS DC, BATTERY BANK & POWER CONVERTERS
V  E0 ( T )  R( T )* I  b( T )* ln( I )  m( T )* exp( n* I )
AC Loads
Eo= reversible potential (V); I= current (A); T= temperature (°C); b,m,R = coefficients that depend
on temperature; n = constant.
For the Stuart Compagny’s electrolyzer at the HRI, the following polarization curve
was found from the experimental data:
Compressor
PEMFC
H2 Tank
Electrolyzer
V  E0  RI  b ln( I )  ( 0.1716 exp( 0.0612T ))* exp( 0.055I )
Fig.1 Renewable energy system with hydrogen storage
E0(T) = 32.5628–0.00677*T; R(T) = 0.0002089*T–0.00955; b(T) = 3.374–0.0194*T
II. PHOTOVOLTAIC ARRAY MODEL
The PV cell are described by the I-V characteristics which equations are :
I  I L  I0 ( e
q( V  IRS )
nkT
 1)
I L  I L( T 1 ) ( 1  K 0 ( T  T1 ))
I L( T 1 ) 
G * I SC ( T 1 )
G nom
; K0 
3
n
T 
I 0  I 0( T1 ) *   * e
 T1 
I SC ( T1 )
I 0( T1 ) 
1 1 
e
III.
qVoc( T1 )  
*  T T1
nkT1





I SC( T 2 )  I SC( T 1 )
I SC( T 1 ) ( T2  T1 )
 qVg  1 1
*  
nk  T T1
1




In the model, the temperature variation was found from the dissipated (heat) power:
IL = photogenerated current (A)
I0 = diode saturation current (A)
q = electronic charge (C)
V = solar cell terminal voltage (V)
RS = cell series resistance ()
n = diode quality factor
k = Boltzmann’s constant (J/K)
T = ambient temperature (K)
dTélec Ptot  PH 2  hA(Télec  Tamb )

dt
MC
VI. FUEL CELL MODEL
This curve can be represented by a sum of linear, logarithmic and exponential functions:
G = cell irradiance W/m²
Gnom= rated cell irradiance (W/m²)
T = solar cell temperature (K)
T1, T2= two reference temperatures (K)
ISC(T1)= short circuit current at temp. T1 (A)
ISC(T2)= short circuit current at temp. T2 (A)
; R   dV  1
S
dIVoc X V
q
X V  I 0( T1 ) *
*e
nkT1
qVoc( T1 )
nkT1
WIND TURBINE MODEL
The wind turbine power can be calculated by the following equation. An algebraic
relation between wind speed and mechanical power extracted is assumed.
Ptot= Total power consumed by the electrolyzer (W)
PH2= Power consumed to produce hydrogen (W)
MC = thermal capacity of the electrolyzer (J/K)
hA= thermal transfer coefficient (W/K)
Télec = electrolyzer temperature (K)
Tamb = ambient temperature (K)
V  E0  b( T )* ln( I )  R( T )* I  m( T )* exp( n * I )
Eo= reversible potential (V); I = current (A); T= temperature (°C); n = constant;
b, R, m = coefficients that depend on the temperature.
In the model, the temperature variation was found from the dissipated (heat) power:
dT pile
dt

0.98Ptot  Pélec  hA(T pile  Tamb )
MC
Ptot= Total power consumed by the fuel cell (W); Pélec= Electric power produced by the fuel cell (W)
MC = thermal capacity of the fuel cell (J/K); hA= thermal transfer coefficient (W/K)
Tpile = fuel cell temperature (K); Tamb = ambient temperature (K)
VII. SIMULATION RESULTS
The complete system’s model is developed and simulated using Matlab/Simulink software.
1
2
3
Pw  R C p  ,  v
2
12000
10000
Pw = power extracted from the wind (W)
 = air density (kg/m3)
R = blades radius (m)
Cp = power (performance) coefficient
 = tip speed ratio
 = pitch angle of the rotor blades (°)
v = wind speed (m/s)
Puissance (W)
8000
6000
4000
2000
Wind speed, temperature and
irradiance
Wind turbine and photovoltaic
array power
State of charge, electrolyzer
power and fuel cell power
Fig.3 Results for January Month
0
0
2
4
6
8
10
12
14
16
18
20
Vitesse du vent (m/s)
Fig.2 Power versus wind speed plot for the Bergey BWC Excel 10 kW wind turbine
This work has been supported by the Natural Sciences and Engineering Research Council of Canada and the LTE Hydro-Québec,
Wind speed, temperature and irradiance
Wind turbine and photovoltaic
array power
Fig. 4 Results for July Month
State of charge, electrolyzer
power and fuel cell power