Load Flow Analysis simulation using Power World
simulator
BAGUMA KEVIN – MEE231025
Faculty of Electrical Engineering
Universiti Teknologi Malaysia
Johor Bahru, Malaysia
bagumakvn20@gmail.com
Abstract—This document describes the IEEE fourteen bus
power system setup with connected loads, synchronous
condensers, transmission lines, generators and capacitor
banks. Power World simulator is used to perform the load flow
analysis and the per unit bus voltages, real and reactive power
flows are determined for the simulated system.
Keywords—Load flow analysis, power system, Power World
Simulator.
I. INTRODUCTION
Load Flow Analysis (LFA) is a study that is aimed at
determining the power flows, currents and voltages in a
power system (PS) under steady state. Every power system
consists of at least synchronous generators, transformers,
transmission lines and various types of connected loads. A
power system is connected to ensure that it supplies reliable
power that is within the acceptable voltage and frequency
limits to the customer in real time. During normal operation,
there is need to determine the steady state system voltages,
currents and the real and reactive power flows for the
connected system. Unlike traditional circuit analysis, power
flow studies use simplified notations such as single-line
diagrams and the per unit system, and focuses on the various
forms of AC power i.e., real, reactive and apparent rather
than voltage and current. The most important use of load
flow studies is in the planning for the future expansion of
power systems as well as in determining the best operation
for the existing systems [1]. This work is based on
simulations using the Power World simulator which provides
the results of the system parameters under study.
II. THEORY
In a network, the transmission lines, transformers and
reactances are modelled by their linear equivalent circuits
but for generation and load demands at the buses, non-linear
electrical characteristics are present.
For digital simulations, a number of algorithms have been
developed for digital power flow solutions and with these,
different methods for LFA have been developed and
distinguished from each other by the speed and time of
computation, storage requirement and the rate of
convergence.
The common power flow methods used are Gauss-Seidel
method, Newton-Raphson method and the Fast Decoupled
method [1].
The main points of concern in a LFA are:
• Determining the voltage magnitude and phase
angle at each bus.
• Determining the active and reactive power flows in
each line.
At each bus, there are always two variables that are defined
and the other two are always unknown and need to be
determined. The variables are: voltage magnitude, voltage
phase angle, real power injection and reactive power
injection.
In a power flow analysis, three types of network buses are
encountered that is [2];
• Slack or swing bus – the voltage magnitude and
phase angle are known; real and reactive power
injections are unknown.
• Generator or voltage-controlled bus – this is also
called the PV bus where the real power injection
and voltage magnitude are known; voltage phase
angle and reactive power injection are to be
determined.
• Load or PQ bus – the real and reactive power
injections are known; voltage magnitude and phase
angle are unknown.
This document therefore presents details of the IEEE 14 bus
one-line diagram setup with connected loads, generators,
synchronous condensers, transmission lines and capacitor
banks. Power world simulator was used the LFA task as
described.
III. SIMULATION SETUP
In the Power World simulator, the components of the IEEE
14 bus network system were set all set to the initial values.
Generator buses were modelled and initialized with their
real power injections and voltage phase on a system base
apparent power of 100MW. The selected system nominal
voltage was 138kV for which the per unit (P.U) voltages at
the buses were determined.
Table 1: Initial P.U bus voltages and bus loads
Table 1 above indicates the initial P.U bus voltages and the
different loads that were connected to the load buses.
BAGUMA KEVIN – MEE231025
The buses were clearly distinguished from one another by
the initial settings. This created the slack bus, PV and PQ
buses for the network as shown.
Table 4: Transmission line parameters
Table 2: Bus types
All that information was used to design the IEEE 14 bus
system in Power World simulator software as illustrated.
For each of the buses, the P.U voltage limit was set so as to
help in monitoring the stage when iterations are made with
the simulation software. A deviation of ±6% was used to set
the limits within 0.94 and 1.06 P.U. Any values within that
range are acceptable and the system operation is normal for
this scenario. The following table indicates the set limits.
Table 3: P.U bus voltage limits
Interconnections between the different system equipment
was done with transmission lines. The transmission lines
were modelled with per unit values of reactances, resistances
and line charging. For interconnections where a transmission
was introduced, the transformers were well initialised with
tap ratios indicated as below.
Figure 1: IEEE 14 bus simulation setup
BAGUMA KEVIN – MEE231025
IV. RESULTS AND DISCUSSIONS
In the run mode of the simulation software, the base case
power flow was run. Upon completion, bus bar per unit
voltages were determined. Also, the real and reactive power
flows in the transmission lines were determined as
indicated.
With use of the limit monitoring option, it was discovered
that all the per unit bus voltages on the system nominal
voltage were within the acceptable range for proper system
operation. The limits are indicated in the table below.
Table 6: P.U bus voltage limit monitoring
The real and reactive power flows after running the base case
scenario are extracted and shown below.
Table 7: Real and reactive power flows
Figure 2: P.U bus voltages and line flows
The following table clearly indicates the per unit bus
voltages after running the base case scenario.
Table 5: P.U bus voltages
The real and reactive power line flows were extracted into an
excel sheet and the required per unit values computed as
shown in the table below.
BAGUMA KEVIN – MEE231025
Table 8: P.U real and reactive power computations
Real and reactive line flows
From
Name
Bus 1
To
Name
Bus 2
MW
From
158.7
Mvar
From
-24.1
PU MW
flow
1.587
PU Mvar
flow
-0.241
Bus 1
Bus 5
75.6
5.3
0.756
0.053
Bus 2
Bus 3
74.4
-1.5
0.744
-0.015
Bus 2
Bus 4
56.1
1.1
0.561
0.011
Bus 2
Bus 5
41.5
3.7
0.415
0.037
Bus 3
Bus 4
-22.4
12.4
-0.224
0.124
Bus 4
Bus 5
-60.3
14.3
-0.603
0.143
Bus 4
Bus 7
27.8
-2.9
0.278
-0.029
Bus 4
Bus 9
16.0
1.8
0.160
0.018
Bus 5
Bus 6
44.6
12.9
0.446
0.129
Bus 6
Bus 11
7.6
4.9
0.076
0.049
Bus 6
Bus 12
7.9
2.7
0.079
0.027
Bus 6
Bus 13
17.9
8.0
0.179
0.080
Bus 7
Bus 8
0.0
-9.4
0.000
-0.094
Bus 7
Bus 9
27.8
4.8
0.278
0.048
Bus 9
Bus 10
5.0
3.0
0.050
0.030
Bus 9
Bus 14
9.2
2.8
0.092
0.028
Bus 10
Bus 11
-4.0
-2.9
-0.040
-0.029
Bus 12
Bus 13
1.7
0.9
0.017
0.009
Bus 13
Bus 14
5.9
2.6
0.059
0.026
V. CONCLUSION
The simulated IEEE 14 Bus system above was operating
with the busbar voltages within the acceptable ranges and
thus the system was stable.
VI. REFERENCES
[1] M. W. Mustafa, Power System Analysis, Esktop
Publisher, 2023.
[2] Corry B., Weedy B.M., Electric Power System, 5th
Edition, John Wiley & Sons Ltd, 2012.
BAGUMA KEVIN – MEE231025