Tutorial
Harmonic Analysis
CYME 7.0 Power Engineering Software
This tutorial provides a guideline on how to perform a harmonic analysis on a network file provided with this tutorial.


Getting Started
1.
Launch the program.
2.
Open the file by clicking on the
Icon of the Main toolbar
and select the self contained study file provided with the
Harmonic Analysis tutorial, Harmonic.sxst.
Network Description
This is a 13-bus system representative of a medium-sized network operating at 13.8 kV and fed from a utility
supply at 69 kV. The system is composed of multiple transformers, cables, in-plant generator, variable
frequency drive (VFD) generating harmonic currents and a power factor correction capacitor.
© CYME International, October 2013

Variable Frequency Drive
1.
Go to Equipment > Harmonic > Frequency Source. The variable frequency drive is represented by a
multi-frequency current source rated at 3.2 MVA, connected on all three phases and has a Y-g
configuration.
2.
The harmonic
spectrum
generated by this
drive, and as
measured on site,
are as per the
details on the table
to the right.
CYME 7.0 Tutorial – Harmonic Analysis
Page 2

Harmonic Analysis
The objective of a Harmonic Analysis program is to analyze the effect of the harmonic currents and limit their
effect on the network to within acceptable limits as specified in the IEEE 519-1992 standard.
1.
Select Harmonic Analysis from the
list of available analyses in the
Simulation toolbar. You can also
launch it from Analysis >
Harmonic.
2.
Click on the Run Simulation icon
in the Simulation toolbar.
3.
The Harmonic Analysis dialog box
is comprised of four tabs as follows:

Global Settings to select
analysis type, line, cable, load
models, overwrite individual
harmonic settings of equipment
with global settings and whether
to include or not the skin effects
of the synchronous machines in
the analysis.

Impedance Calculation at any
bus or node and plot the
impedance as a function of
frequency to check for possible
resonance conditions.

Voltage and Current distortion
analysis, distortion limits and
report options setting.

Capacitor Rating to check
which capacitors in the system
are experiencing overloads due
to the presence of harmonic
currents in the network.
CYME 7.0 Tutorial – Harmonic Analysis
Page 3

Voltage and Current Distortion Analysis
1.
Select the Buses that are to be monitored and the
results to be displayed on the one line diagram.
Select bus PRI_69kV, B3, B8 (VFD Bus) and the
SEC_13.8kV bus.
2.
Click on the Distortion Limits button.
3.
Select the IEEE 519-1992 standard defaults for
Individual (IHD) and Total Harmonic Distortion
(THD) for the voltage range specified.
4.
Click on the Report Options button.
5.
Set the Voltage Report Options as shown in the
illustration to the right. Normal Condition Tags will
be applied to buses within the Harmonic Distortion
Limits specified and Abnormal Condition Tag is for
buses that exceed the limit.
6.
You can click on the
button to run the
Voltage Distortion Analysis or you can set the
Frequency Scan parameters and run both analysis
at the same time and plot the desired charts.
Notes
 You can also select any branch to monitor the current distortions and display the results on the One
Line Diagram of the network.
 For the purpose of this tutorial we will run a voltage distortion analysis simultaneously with a frequency
scan analysis.
CYME 7.0 Tutorial – Harmonic Analysis
Page 4

Frequency Scan Analysis
1.
Select the Bus that is to be included in the Impedance Calculation
analysis: the SEC_13.8kV bus which is also the location of the
6MVAR Capacitor.
2.
Set the range of the Frequency Scan “From” the lowest
frequency which corresponds to our 60 Hz fundamental up “To” a
frequency that includes the highest 37th harmonic frequency
generated by the VFD drive.
3.
Select steps of 5 Hz to generate a smooth plot of the impedance
plots.
4.
Select the Phase impedances for the plots.
5.
Click on the Global Settings tab to set the parameters for the
relevant network components such as.
6.

Use the Series R-L Model for cables since they are relatively
short.

Model Loads as Parallel R-L.

Ignore the Skin Effect of the synchronous machines.
Click on the
button to run both analysis Voltage Distortion and Frequency Scan.
Note: The Program will first run a power flow to obtain the Fundamental Frequency Voltage and Current
profile of the Network. This is a necessary step in order to obtain meaningful harmonic distortion
results.
CYME 7.0 Tutorial – Harmonic Analysis
Page 5

Plotting and Interpretation of Results
1.
Once the analysis is completed the CYMVIEW
chart selector dialog box will be displayed on
screen.
2.
Plot the Impedance Scan and Voltage Waveform
at Bus SEC_13.8kV.
3.
The Impedance Plot indicates possible resonance
condition around the 7th harmonic.
4.
The voltage waveform has considerable distortion
which suggests a Total Harmonic Distortion (THD)
level that exceeds the maximum allowable at the
bus which is set at 5%.
5. You can view the results of the Harmonic Analysis on the one line diagram that will now have result labels
for the monitored buses as specified in the voltage distortion analysis.
CYME 7.0 Tutorial – Harmonic Analysis
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
6.
As can be
noticed, the
results
indicate that
the
SEC_13.8kV
bus has a
THD of 5.37%
which is
beyond the
acceptable
limit.
7.
To solve this
problem, a
filter that can
tune out those
harmonics to
within
acceptable
limits can be
installed.
Single Tuned Filter at Capacitor Location
1.
Go to Equipment > Harmonic > Single Tuned Filter and create a new equipment ID “STF”.
2.
The objective is to tune the existing capacitor and therefore you need to enter its rating of 6 MVAR at 13.8
KV L-L.
3.
Although the resonance is at the 7th harmonic
installing a filter tuned to that frequency does not
improve the situation since it will create a peak
close to the 5th which has a higher harmonic
current content. (Refer to VFD Drive Harmonic
Content Table).
4.
The tuned frequency of the filter will be set at the
5th harmonic and the configuration of the filter
will be Y-g to match the configuration of the
capacitor.
5.
To compute the corresponding R, L and C values
of the filter click on the
button.
6.
The dialog box that will be displayed will have all
the information as entered in the General tab
except for the filter quality factor. Select a high
quality filter like 999; which effect is to neglect
the resistance R of the filter.
7.
Click on the
button and the R, L
and C fields of the General tab will be updated
with the computed values.
8.
Click on OK in the Single Tuned Filter dialog box
to close it.
CYME 7.0 Tutorial – Harmonic Analysis
Page 7
9.
From the Harmonic group of the Symbol bar tab of the Explorer bar,
select the single tuned filter in the Harmonic Analysis symbol bar, drag
and connect to the SEC_13.8kV bus.
10. Once the left hand mouse button is released the STF dialog will be
displayed on screen.
11. Select the single tuned filter ID “STF” from the equipment database.
12. Make sure that you switch “OFF” the 6 MVAR-CAP.

Voltage Distortion and Frequency Scan with the STF Installed
1.
Run the Voltage Distortion and the Frequency
Scan Analysis with the STF connected to the
SEC_13.8kV bus.
2.
Plot the Impedance Scan and Voltage Waveform
at bus SEC_13.8kV.
3.
The Impedance Plot Indicates that the
installation of the filter tuned out the 5th
harmonic at the bus and at the same time
provided an attenuation of the impedance at the
7th harmonic.
4.
The Voltage Waveform does not have any
noticeable distortion level which suggests a Total
Harmonic Distortion (THD) level that is within the
Maximum allowable 5%.
CYME 7.0 Tutorial – Harmonic Analysis
Page 8
5.

The results labels on the
one line diagram confirm
that the THD on the
SEC_13.8kV bus is now
at 0.84 %.
Analysis Reports
1.
If the Voltages and Distortion Report Options have been checked
in the Voltage and Current tab of
the Harmonic Analysis dialog box, then the reports will automatically be displayed on screen once the
analysis is complete.
2.
These reports include information such as:
 Individual Harmonic Distortion (IHD) in % for every harmonic frequency present in the system at
each monitored bus.
 Total Harmonic Distortion (THD) in % at each monitored bus.

KVT Product (KVT) for each bus, which expresses the inductive influence as the square root of the
sum of squares of the weighted RMS values of all the sine-wave voltages (in KV), including the
fundamental. The weighting factor Wh applied to voltage is called the “1960 TIF Weighting Value”.
Refer to IEEE Standard 519.

Telephone Influence Factor (TIF) which is a dimensionless quantity defined as the ratio of the
square root of the sum of the squares of the weighted RMS values of all the sine-wave components
including the fundamental to the un-weighted RMS value of the entire wave.
using voltages in kV.
3.
Sample Harmonic Analysis Report
CYME 7.0 Tutorial – Harmonic Analysis
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