Energy and Power Engineering, 2013, 5, 41-45
doi:10.4236/epe.2013.54B008 Published Online July 2013 (http://www.scirp.org/journal/epe)
Simulation Study of Three Types of Distributed Power
Based on EMTDC
Peng-tao Mu, Dong-mei Zhao
School of Electrical and Electronic Engineering, North China Electric Power University, Beijing, China
Received March, 2013
ABSTRACT
In order to analyze the performances of directly-driven permanent magnet synchronous generator wind turbine (PMSG)
connecting to the grid, photovoltaic array and microtubine, dynamic models of them are established. The validity of the
established models and proposed control strategies are demonstrated by simulation system under the software package
PSCAD/EMTDC.
Keywords: Wind Power; Photovoltaic; Microtubine; Simulation; PSCAD/EMTDC
1. Introduction
Distributed generation refers to making use of a variety
of decentralized energy, including renewable energy and
the local fossil fuel which is easy to g et to generate pow-
er. Flexible, economic, and environmental protection are
the main advantages of distributed generation. But at the
same time some of the renewable energy have inter- mit-
tent and randomness characteristics, this power has some
difficulties to regulate itself alone to meet the load, usu-
ally need other power to coordinate [1]. Currently, more
mature distributed generation technologies have several
forms, such as photovoltaic power, wind power, gas tur-
bine power.
Grid connection of the distributed power has presented
new challenges to the safe operation of the power system.
The diversity of distr ibu ted pow er increases the difficulty
to connect the grid. Grid-connected distributed power
easily affect the quality of the surrounding electricity
users, it is difficult to achieve energy optimizatio n.
About wind power generation system, synchronous
wind turbines which is connected to the grid by uncon-
trollable rectifier and controllable grid-connected inverter
is studied in the literature [2]. A method to decouple the
power of D-PMSG (directly driven wind turbine with
permanent magnet synchronous generators) which is
connected to the grid by uncontrollable rectifier and con-
trollable inverter is reported in literature [3]. A complete
model of the PMSG is given in literature [4]. About
photovoltaic power generation system, a photovoltaic
cell model with a friendly interface is developed using
Matlab/Simulink simulation software in literature [5]. A
simple photovoltaic generation systems is established
using PSCAD/EMTDC electromagnetic transient simula-
tion software in literature [6]. About micro turbine gen-
eration system, a single cycle mathematical model for
dynamic simulation of microturbine is established on the
basis of the analysis of single cycle overloaded microtur-
bine in the literature [7].
2. Model Research of Wind Power
Generation System
2.1. Structure of Wind Power Generation System
A complete distributed generation system is mainly
composed of distributed power, power electronic conv erter,
the various controllers as well as the power grid or load.
These components require modeling and solving in the
electrical and control system.
The modeling of doubly fed induction wind generator
has been a lot of research at home and abroad, relatively
modeling of directly driven wind turbine with permanent
magnet synchronous generator is less. A permanent
magnet synchronous generator is used in this article. The
overall structure of the wind generation system is shown
in Figure 2-1. Many articles have the detailed introduction
about the wind turbine and grid-connected converter, so
these parts are ignored.
2.2. Modeling of Directly—Driven Permanent
Magnet Synchronous Generator
*The National High Technology Research and Development of China
863 Program (2012AA050201). Permanent magnet synchronous generator for wind power

P.-T. MU, D.-M. ZHAO
42
has more pole pairs, so the ge nerator can still work in low
rotor speed, thus permanent magnet sy nchronous generat or
can directly couple to the wind turbine, eliminating the
need for a gear box. A mathematical model of permanent
magnet synchronous generator is established in d-q
synchronous rotating coordinate system:
3[() ]
2
d
dsdqqd
q
qsqdd fq
eqddqf
di
uRiwLiL
dt di
uRiwLiwL
dt
TpiiLL


 
 

(1)
d is the d-axis voltage of generator unit stator; q
is the q-axis voltage of generator unit stator; d is the
d-axis current of generator unit stator; q is the q-axis
current of generator unit stator; d is the d-axis
equivalent inductance of generator unit stator; q is the
q-axis equivalent inductance of generator unit stator;
uu
i
L
i
L
s
R
is stator armature winding resistance;
f

is the per-
manent magnet flux of rotor; e is the electromagnetic
torque; w is the frequency of the stator electrical angle; p
is the number of pole pai rs.
T
2.3. Control Strategy of Grid-Connected
Inverter
The main role of the grid-connected inverter is to
maintain voltage of dc side constant, and to control the
reactive power exchange between the wind driven
generator and the grid according to need of the grid[8].
Shown in Figure 2-2.
Wind Turbine
D D
D D
D
D
200 [m F]
g41
g11 g31
g61
g51
g21
2
22
22
2
5 [ mH]0. 005 [ohm]
5 [ mH]0. 005 [ohm]
5 [ mH]0. 005 [ohm]
16 [uF] 16 [uF] 16 [uF]
Usa 1
Usb 1
Usc1
Ia 1
Ib 1
Ic1
Ed1
Figure 2-1. The overall structure of the wind power generati on
system.
D+
F
-
D+
F
-
I
P
Id 1
Iq 1
I
P
B
+
D+
F
+
B
-
D+
F
+
Ud1
Uq1
*
0.1885
*
0.1885
Usq1
I
P
D+
F
-
I
P
s
1.2
Ed1
Sign1
0.0
Usd1
Figure 2-2. The control of grid-connected inverter.
Active and reactive power output of the grid-
connected inverter:
1111
1111
dd qq
qd dq
Pui ui
Quiui


1
1
(2)
The grid voltage space vector is put on d-axis on the
d-q coordinate system, so 、1.We can get
that 111dd
1dg
uu0
q
u
Pui

、111dd Qui


1q
i
, apparently, you can
achieve decoupling control of active and reactive power
through the control of and .
1d
i
3. Simulation Model of Photovoltaic
Generation System
Grid-connected PV system is made up of the PV array,
DC / DC converter, inverter and other components, and
the most important components are the PV array and
inverter. The photovoltaic generation system is shown in
Figure 3- 1.
4. Simulation Model of Microtubine
Microturbine generation system [9] is mainly composed
of the microturbine of high-speed rotation and permanent
magnet synchronous generator. microturbine is made up
of micro-turbine compressor, combustor, gas turbine.
The mixture of the pressurized air by the compressor and
fuel flame in the combustion chamber, and the high
temperature gas expands in the gas turbine to generate
power, which eventually converted to mechanical energy.
A part of the mechanical energy drive compressor work,
the other part is provided to the generator. The velocity,
temperature, and fuel control the air quantity which is
sent into the combustor to limit the upper temperature of
the combustion chamber in order to obtain maximum
operating efficiency in a safe and reliable state in the
energy conversion process .The microturbine model is
shown in Figure 4-1.
5. Simulation
5.1. Wind Generation System
Wind power generation and transmission system which is
gt1
gt2
gt3
gt4
gt5
gt6
1
EaEc Eb
Idc
35
264
135
264
Ia_motor
dcVltg
80000
5
10000
5
T1
Vp v
Icon
0.01 [ H]
Ip v
D
+
G
T
-
Figure 3-1. The structure of the photovoltaic generation
system.

P.-T. MU, D.-M. ZHAO 43
D+
F
-
I
PD
-
F
+
950.0
G
1 + sTG
1 + sT1
1 + sT2
Min
C
D**
0.77 D+
F
+
0.23
G
1 + sTG 1 + sTe-sT
e-sT
G
1 + sT
1
sT D
+
F
-
Te
Wf
*
-1.0
G
1 + sT1
1 + sT2
Te 2Te2
Tm
B
-
D+
F
+
0.201
*
1.3
*
1.3
w
w
*
700.0
B
-
D+
F
+
935.0
*
55.0
w
1.0
Figure 4-1 The structure of the photovoltaic generation
own in Figure 2-1 is set up in the PSCAD / EMTDC
ample, the start average wind
sp
system.
sh
simulation platform to simulate the changes of power and
voltage under the gust. The wind turbine in the system is
a directly driven wind turbine with permanent magnet
synchronous generator.
In the simulation ex
eed to is 4m / s, after 5 seconds, the speed reduces to
1.98 m / s. The total simulation time is 20s, and the
solution time step is 50
s

. The simulation results are
shown in Figure 5-1, Fige 5-1(a) shows the generator
speed can quickly follow the changes of the wind turbine.
Figure 5-1(b) shows the active power generator issue
can quickly follow the variation of the wind turbine. we
can see that the capacitor voltage of DC side fluctuates
because of changes in the system transmit power from
Figure 5-1 (c). We can get the following conclusions,
this wind power system can operate stable under different
wind conditions. The grid converter of this system uses
PI controllers, which does not require complex mathe-
matical algorithms. The control method is simple and the
dynamic performance of control system is good.
ur
5.2. Photovoltaic Generation System
is based on As shown in Figure 3-1, the system
photovoltaic arrays for power, and the power flow to th e
DC load through buck circuit. The MPPT module real-
time calculates and output voltage of the maximum
power. The voltage is compared with the capacitor
voltage of DC side to generate a PWM control signal.
The signal adjusts the output voltage of the PV array to
make the PV array work in the maximum power point
voltage, so the PV array output power reaches the
maximum. Using incremental conductance method in
MPPT, incremental conductance method achieves
maximum power tracking through instantaneous
conductance and conductance change.
ro t o r s
p
eed
0.0 2.5 5.0 7.5 10.0 12. 5 15.0 17.5 20.0
-2.00
-1.50
-1.00
-0.50
0.00
0.50
1.00
1.50
2.00 w
p.u.
(a)
Pw ind
0.0 2.5 5.0 7.5 10.0 12.5 15.0 17 .5 20.0
0.000
0.010
0.020
0.030
0.040
0.050 Pw ind
MW
(b)
Ed1
0.0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0
-2.00
-1.50
-1.00
-0.50
0.00
0.50
1.00
1.50
2.00 <Untitled>
KV
(c)
Figure 5-1. (a) Generator sp (b) Generator active power;
In the simulation example, the first light intensity of
10
eed;
(c) capacitor voltage of DC side.
00 2 /wm, after 5 seconds, the light intensity reduced
to 4602, the total simulation time is 7s, the solution
time step is 50
/wm
s

.
From the Firegu 5-2, the system will soon enter the
steady state; this is because the photovoltaic array
module does not contain the dynamic links, when the
changes of the light intensity, the system can well adjust
the active power and the photovoltaic outlet voltage.
Because of MPPT control, the output voltage remains
near the maximum power point. When the light intensity
drops from 1,000 2 /wm to 4602 /wm, the output
voltage of the PV array decreases aeginning and
then increases, but the size is almost no change, This is
the PV characteristics curve with the light intensity
changes and changes in the law exactly. The change rule
of Figure5-2 is exactly similar to the rule of P-V
t the b

P.-T. MU, D.-M. ZHAO
44
characteristics curve of the light intensity changing.
5.3. Microturbine Generation System
shown in Microturbine generation system which is
Figure 5-3 is set up in the PSCAD / EMTDC simulation
platform to simulate the operating characteristics of the
microturbine. Microturbine provides power to the load of
40 kw. The total simulation time is 20 s, and the solution
time step is 50
s

. Power characteristic of microturbine
is shown in Figure 5-4.
PV a rra
y
out
p
ut
2.0 3.0 4.0 5.0 6.0 7.0
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
KV
Vpv
0.0000
0.0050
0.0100
0.0150
0.0200
0.0250
0.0300
0.0350
MW
Parray
Figure 5-2. PV array output voltage, PV array output
power.
ACDC
AC DC
V
A
PMSG
Turbine
fuel
Microturbine Generation System
Figure 5-3. microturbine power generation system structure.
mi croturbine1 : G ra
p
hs
0.0 1.0 2.0 3.0 4.0 5.0
0.000
0.010
0.020
0.030
0.040
0.050
0.060
0.070
MW
Pout
Figure 5-4. active power of microturbine.
6. Con
model of directly driven wind turbine
agnet synchronous generator is
are also
re
mover system, high-speed permanent
m
ERENCES
[1] P. Li, “Researulation Methodol-
ogy of Microibuted Energy Re-
iable
Directly Driven
Wind Turbine with
ulink,”
rray and MPPT Controller,”
s Turbines,” Journal of Engineering for
clusions
The grid-connected
with permanent m
established based on PSCAD/EMTDC simulation
platform. The model achieves maximum wind energy
capture and the dynamic performance is good.
Characteristics of the PV array are related to the
parameters of photovoltaic cell module, and
lated to the intensity of solar radiation and ambient
temperature, thus the PV array is actually a highly
nonlinear power with multiple parameters. A
mathematical model based on the physics of the
photovoltaic cell is build in PSCAD, and the result of
simulation shows that the above model can dynamically
track changes of the intensity of solar radiation and other
parameters.
Microturbine power generation system consists of
microturbine
agnet synchronous generator and power electronic
converter. This article briefly describes the microturbine
mover system. Simulation results show that the structure
of the system is able to simulate the steady-state process
of the microturbine. The model can be used as the basis
of the following study.
REF
ch on the Transient Sim
-grid Powered by Distr
sources,” Ph.D. Thesis, Tianjin University, 2010.
[2] S. K. Kim, E. S. Kim and J. Y. Yoon, “PSCAD/EMTDC
Based Dynamic Modeling and Analysis of a Var
Speed Wind Turbine,” IEEE Power Engineering Society
General Meeting, USA, Denver, 2004．
[3] D. Wu and J. W. Zhang, “Control System of Vari-
Able-speed Permanent-magnet Generator
by Wind Turbine,” Large Electric Machine and Hydrau-
lic Turbine, No. 6, 2006, pp. 51-55.
[4] M. Yin, G. Y. Li and J. C. Zhang, et al., “Modeling and
Control Strategies of Directly Driven
Permanent Magnet Synchronous Generator,” Power Sys-
tem Technology, Vol. 31, No.15, 2007, pp. 62-65.
[5] H. L. Tsai, C. S. Tu and Y. J. Su, “Development of Gen-
eralized Photovoltaic Model Using Matlab/Sim
Proceedings of the World Congress on Engineering and
Computer Science, 2008．
[6] Z. Y. Sun, H. Yu and G. G. Yan, “PSCAD Simulation
Models for Photovoltaic A
Power System Protection and Control, Vol. 37, No.19,
2009, pp. 61-64.
[7] W. I. Rowen, “Simplified Mathematical Representations
of Heavy Duty Ga
Power, Vol. 105, No.4, 1983, pp. 865-869．
doi:10.1115/1.3227494
[8] G. G. Yan, J. G. Liu and G. Mu, “Modeling and Control

P.-T. MU, D.-M. ZHAO
45
riven Wind Turbine with Perma-Strategies of Directly D
nent Magnet Synchronous Generator,” Power System
Protection and Control, Vol. 39, No.7, 2011, pp. 68-73.
[9] C. S. Wang, F. Gao and P. Li, “Model Improvement and
Experimental Verification of Microturbine Generation
System,” Journal of Tianjin University, 2011.