This project involves developing an accurate dynamic model of a micro-grid in MATLAB/Simulink. The micro-grid model includes multiple energy sources like a diesel generator and photovoltaic array, various loads, faults, and a connection to the main electrical grid. Students created models of grid-tied inverters, synchronous machines, and developed a human interface device to interact with the simulation. The completed micro-grid simulation provides an educational platform to study different generation scenarios and observe associated power flow phenomena.

1. Project Title
Modelling and simulation of an electrical micro-grid using the MATLAB/Simulink platform
Project Team Members
Aodhgan Gleeson, Ben Hudson
Executive Summary
The structure of the electrical grid has traditionally been based on large centralised power stations
generating electrical power for; transmission over long distances at voltages of the order of 100's of
kV, distribution at voltages of 10's of kV, before ultimately being supplied to the consumer in the
familiar form of 400 V/230 V three-phase and neutral. With the advent of small-scale renewable
energy sources and the increased capability of power electronic converters and associated controls,
the possibility for operating small-scale, isolated electrical grids, independently of this centralised
national grid structure, has become a reality. The design and development of these micro-grids
requires careful consideration and hence the use of simulation tools to gain an insight into detailed
system operation is essential.
The purpose of this project is to develop an accurate, dynamic model of a micro-grid comprising
several different energy sources, various loads, faults and circuit breakers as well as a connection to
the main electrical grid. An appropriate grounding in the relevant theory of three-phase power and
its control was essential. This demanded a comprehensive understanding of dq0 Reference Frame
Theory, synchronous machine theory, electrical power systems and small signal modelling. The
micro-grid model was developed using the MATLAB/Simulink platform in conjunction with the
SimPowerSystems toolbox. This additional toolbox provides component libraries and analysis tools
for modelling and simulating electrical power systems.
Work commenced on creating the micro-grid after studying the relevant literature. Initially, a model
was created that familiarised the students with the dq0 Reference Frame Theory. An adaptation of
this model led to the creation of the main electrical grid model.
The SimPowerSystems toolbox in Simulink allowed for precise models of complex electromagnetic
machines to be implemented into the micro-grid model. Several simulations and calculations were
performed to ensure the students fully understood the workings of both the Permanent Magnet
Synchronous Machine and the Synchronous Machine models.
A model of a three-phase inverter with an LCL filter was adopted from Figueres et al. [1]. This was
developed using small signal modelling techniques. This model acted as a constant voltage source
and was subsequently put forward as a model of a fully charged battery bank. Further adaptations to
this inverter model allowed the students to incorporate any renewable electricity resource that
could be modelled as a current source. 1
A Human Interface Device that enabled the user to interact with the micro-grid model was designed
and constructed. The HID allowed dynamic changes to be made to the micro-grid. Significant work
1
G. G. J. S. F. G.-E. a. J. C. R. Emilio Figueres, “Sensitivity Study of the Dynamics of Three-Phase Photovoltaic
Inverters with an LCL Filter,” IEEE Transactions on Industrial Electronics, vol. 56, no. 3, p. 706, March 2009.

2. was required for both the construction of the physical device and the infrastructure that allowed the
controlled adjustments in the Simulink environment.
The final micro-grid included a diesel generator, a Photovoltaic array, a battery bank, fixed loads,
variable dynamic load and a connection to the national grid. Simulations were carried out on an
instantaneous solver basis, the implication of which is that transients and their associated effects
can be observed and quantified. The interactive, dynamic micro-grid model created in this project
allows the user to simulate any number of generation scenarios and observe the associated power
flow phenomena. Results from sample scenarios are presented in this report but it is important to
note the versatility of the micro-grid model. The interface device, combined with the simulation
model provides an invaluable platform for educational and demonstrative purposes.
Figure 1 Completed HID Device
Figure 2 Renewable Resource Simulink Schematic
2
Idset
1
Vi_abc_SP
dq0
sin_cos
abc
abc
sin_cos
dq0
In1 Out1
Vdc Limited PI
In1 Out1
Iq Limited PI
In1 Out1
Id Limited PI
[dq]
Goto3
[dd]
[I_invq]
[I_invd]
2
Gain4
1
Gain3
1
Gain2
-K-
-K-
Gain
[dq]
[dd]
[I_invq][I_invd]
[I_invd]
From1
[I_invq]
From
5
Iq set
4
Vdc
3
Vdc*
2
sin cos
1
I Inv

3. Figure 3 Simulink Model of Micro Grid
Inverter 2 PQ
Dynamic Load
9.47821
vf
abc
sin_cos
dq0
abc
sin_cos
dq0
abc to dq0
Constant Power
v+
-
v+
-
400
-2.901e-013
-1.313e-013
Vdq0_Grid
607.8
Vdc
Uref
A
B
C
+
-
Uref
A
B
C
+
-
Time
To Workspace1
com
A
B
C
A
B
C
Three-Phase Fault
com
A
B
C
a
b
c
com
A
B
C
a
b
c
com
A
B
C
a
b
c
com
A
B
C
a
b
c
com
A
B
C
a
b
c
Vabc
Iabc
A
B
C
a
b
c
Vabc
Iabc
A
B
C
a
b
c
Vabc
Iabc
A
B
C
a
b
c
Vabc
Iabc
A
B
C
a
b
c
Vabc
Iabc
A
B
C
a
b
c
Vabc
Iabc
A
B
C
a
b
c
A
B
C
PQ
m
A
B
C
Amplitude
Phase
Frequency
SinCosOut
Vabc_grid
Va1
Vb1
Vc1
Three Phase Source
Terminator2
Terminator1
Vabc
Iabc
PQ
Synchronous Machine Power
Vf _
m
A
B
C
Pm
Synchronous Machine
Switch
In1Out1
Scope
2.704e+004
SM Power In
SM Power
SM Load Angle
signalrms
signalrms
signalrms
230.9
230.9
230.9
RMS Voltage Inv 2
231.8
231.8
231.8
RMS Voltage Inv 1
230.9
230.9
230.9
RMS Voltage Grid
Vabc
Iabc
PQ
Power to Grid1
Power to Grid
Real Power
Reactiv e Power
Id
Iq
0.4182
Power angle
PQ
Angle
Power Factor
Power Factor Angle Measurement
1
Power Factor
s
-
+
PhotoVoltaic Array
PV Power
Memory1
Memory
0
0
Load Bank
Vcap_abc
Vga
Vgb
Vgc
Via
Vib
Vic
LCL Filter2
Vcap_abc
Vga
Vgb
Vgc
Via
Vib
Vic
LCL Filter
SM Power
Cloud Cov er
Dy namic Load P
Dy namic load Q
Axis 5
Axis 6
Axis 7
Axis 8
Inv erter 1 P
Inv erter 1 Q
Inv erter 2 P
Inv erter 2 Q
Circ On/Of f 1
Circ On/Of f 2
Circ On/Of f 3
Circ On/Of f 4
Circ On/Of f 5
Circ On/Of f 6
ToggOn/Of f 1
ToggOn/Of f 2
ToggOn/Of f 3
ToggOn/Of f 4
ToggOn/Of f 5
Togg On/Of f 6
Mom. On/Of f 1
Mom. On/Of f 2
Mom. On/Of f 3
Mom. On/Of f 4
Joystick
0
0
0
0
0
0
0
Iq_set
0
Io_set
0
Inverter 2 Q Setpoint
3e+004
Inverter 2 P Setpoint
59.98
-0.4378
4.102e-015
Idq0_Grid
Idc Photovoltaic
19.92
Idc
[V_abc_r_out]
[Idq0_set]
Goto8
[V_inv]
Goto7
[Vdc_renew_star]
Goto5
-T-
Goto48-T-
Goto47-T-
Goto46-T-
Goto45-T-
Goto44-T-
Goto43-T-
Goto42-T-
Goto41-T-
Goto40
[V_grid]
-T-
Goto39-T-
Goto38-T-
Goto37-T-
Goto36-T-
Goto35-T-
Goto34-T-
Goto33-T-
Goto32-T-
Goto31-T-
Goto30
[gate]
Goto3
-T-
Goto29-T-
Goto28-T-
Goto27-T-
Goto26-T-
Goto25-T-
Goto24-T-
Goto23-T-
Goto22-T-
Goto21
[I_inv]
Goto2
[I_abc_1_out]
[V_abc_1_out]
[I_abc_1]
[I_grid_out]
[V_grid_out]
[Ism]
Goto13
[Vsm]
Goto12
[vsc1]
Goto11
[I_abc_r_out]
[sin_cos]
-K-
Gain
[Vdc_renew_star]
From9
[I_abc_1_out]
From8
[V_abc_1_out]
From7
[I_abc_1]
From6
[V_grid]
[sin_cos]
[Circ_4]
[Circ_3
[Circ_
[Circ_2]
[Inverter1
[Inverter1
[Togg_5]
From32
[Togg_4]
From31
[SM_Power]
[sin_cos]
From3
[Circ_2]
[Circ_1]
[Togg_3]
From27
[Togg_2]
From26
[Togg_1]
From25
[Mom_1]
[Circ_4]
[Circ_3]
[Circ_2]
[Circ_1]
[I_inv]
From2
[vsc1]
[Dynamic_Load_Q]
[Dynamic_Load_P]
[I_grid_out]
From16
[Ism]
From15
[Vsm]
From14
[V_grid_out]
From13
[sin_cos]
From12
[sin_cos]
From11
[Cloud_Cover]
[gate]
From1
[I_grid_out]
From
20kWon/off
10kWon/off1
10kWon/off
-10kVAron/off
1kW+5kVAron/off
PowerofLoad
PhaseA
PhaseB
PhaseC
Fixed Load Bank
1
3.904e+004
1.978e+004
Dynamic P and Q
i +
-
I Inv
sin cos
Id set
Iq set
Vgrid
Vi_abc_SP
Vi_dd_dq
Control Loops1
I Inv
sin cos
Vdc*
Vdc
Iq set
Vi_abc_SP
Vi_dd_dq
Idset
Control Loops
50
0
Vg_phase_max
Vdc_sp
Constant
Clock
600
Battery Bank Voltage
Battery Bank Power
Vabc
Iabc
PQ
Vabc
Iabc
PQ
<Load angle delta (deg)>
<Output reactiv e power Qeo (W)>
<Output activ e power Peo (W)>
<Rotor speed wm (rad/s)>