Prof. Ibrahim A.
Metwally High Voltage (ELE311), Fall 2024
Mansoura University
Faculty of Engineering
Department of Electrical Engineering
PSCAD/EMTDC Mini Project
I. Introduction
PSCAD/EMTDC represents and solves the differential equations of the entire power system and its
controls in the time domain (both electro-magnetic and electro-mechanical systems). This class of
simulation tool differs from load flow and transient stability tools, which use steady state equations
to represent electrical circuits (i.e. electromagnetics), but solve the differential equations of machine
mechanical dynamics (i.e. rotational inertia..).
PSCAD/EMTDC results are solved as instantaneous values in time, but can be converted to phasor
magnitudes and angles via built-in transducer and measurement functions (like true-rms meters or
FFT spectrum analyzers...), much the way real system measurements are performed. Since load-flow
and stability programs work with steady state equations to represent the power system, they output
fundamental frequency magnitude and phase information only. The PSCAD simulation tool can
therefore duplicate the response of the power system at all frequencies, bounded only by the user-
selected time step, which can be varied, from ns to s.
II. Objectives:
Four PSCAD files will be run and discussed during the High Voltage course, where their objectives
can be summarized in the following Table:
# File Name Objectives
1 SA-Testing.psc Simulation of the impulse testing of surge arrester to draw the I-V
characteristics and to investigate the effect of circuit inductance on the
voltage waveforms.
2 SA-Location.psc To show the distance effect in the application of surge arresters to protect a
power transformer and how the reflection phenomenon affects the current
waveform through the surge arrester.
3 Reflection.psc To show the effect of cable parameters, cable sheath resistance and load on
the traveling wave velocity, transient time and the transmitted wave to the
load.
4 Switching- To demonstrate the effect of the opening time of circuit breaker, the use of
Overvoltages.psc pre-insertion resistance and surge arrester, and the cable parameters on the
transient overvoltages at the sending-end of the cable.
III. Calculation Procedures & Presentation of the Results
1) For SA-Testing.psc file: First, keep the input current constant at 10 kA (adjust it from the
current slider) and change the circuit inductance (L) from 1 H to 0.1 mH (take L = 1, 5, 10, 20,
50 and 100 H) and draw the peak value of the impulse voltage versus the inductance. Second,
keep L = 1 H and change the current from few A to 20 kA and draw the voltage at peak current
versus the peak current using semi-log scale in the x axis. Repeat the aforementioned procedures
by changing the impulse current waveform (follow the sticky note given in the project main page
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Prof. Ibrahim A. Metwally High Voltage (ELE311), Fall 2024
to generate impulse currents of 1.2/50 µs and 300/1000 µs). Comment and explain the trend of
the results by EQUATIONS. Use samples of waveforms for all voltages and currents to explain
their trends, and get the values of and K assuming the current and voltage is given by I = KV.
2) For SA-Location.psc file: First, keep the length of the station bus as 10 m and keep the surge
arrester (SA) connected to position (A) and do not change the input current (keep it constant at
10 kA). Run the program then record and comment on the current through the arrester (Arr
Current) and the incident current (Lightning Current). Also, record both the voltage at the
transformer end (TFR Volts) and the bus voltage (Bus volts). Increase the length of the station
bus from 10 m to 20 m in steps of 2 m and record all the above-mentioned four quantities. Draw
the current through the arrester (Arr Current), the voltage at the transformer end (TFR Volts) and
the bus voltage (Bus volts) versus the length of the station bus. Repeat the aforementioned
procedures by changing the value of the termination resistance of the far-end of the overhead line
for all phases to be 35 and 1 instead of 350 . Comment and explain the trend of the
results by EQUATIONS. Second, move the SA connection to position (B) and repeat all the
above-mentioned steps. Use samples of waveforms for all voltages and currents to explain their
trends.
3) For Reflection.psc file: First, keep the load resistance constant (1 M), and also keep TWO of
the following parameters constants (cable length, cable relative permittivity and cable relative
permeability) and change the third one then draw the voltage (Ea2) and the transit time () versus
the varied third parameters. Vary cable length from 1 km to 5 km in steps of 0.5 km, cable
relative permittivity from 1 to 5 in steps of 0.5, and cable relative permeability from 1 to 10 in
steps of 1. Comment and explain the trend of the results by EQUATIONS. Second, change
the load resistance constant (1 ) and repeat all the above-mentioned steps. Use samples of
waveforms for all voltages and currents to explain their trends.
4) For Switching-Overvoltages.psc file: First, run the circuit without any change (the opening time
of the circuit breaker to open at zero current crossing = 0.213515 s) then change this time to ±
0.005 s (± 5 ms) in steps of ± 0.001 s (± 1 ms). Draw the peak value of the transient voltage at the
opening time (E1) versus the opening time and comment on the results. Second, fix the opening
time at 0.21851 s and use pre-insertion resistance values of 1 , 5 , 10 , 20 , 50 , 100 ,
200 , 500 , 1 k, 5 k, 10 k, 100 k, and 1 M. Draw the peak value of the transient
voltage at the opening time (E1) versus the pre-insertion resistance and explain the trend of the
results by equations. Third, fix the opening time at 0.21851 s and do not use pre-insertion
resistance, connect the surge arrester and vary its voltage rating from 2 kV to 10 kV in steps of 2
kV, then draw the peak value of the transient voltage (E1) versus the arrester voltage rating and
explain the trend of the results. Fourth, fix the opening time at 0.21851 s, don’t use pre-insertion
resistance and disconnect the surge arrester, then vary the cable length from 2 km to 10 km in
steps of 2 km, and then draw the peak value of the transient voltage at the opening time (E1)
versus the cable length. Comment and explain the trend of the results by EQUATIONS. Use
samples of waveforms for all voltages and currents to explain their trends.
IV. Deadline and Evaluation
Submission deadline: Week 14
Evaluation: 15 Marks (12 %)
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