Practical Applications of
the Electromagnetic Transient
Simulation Program XTAP

https://www.xtap.org/© 2022 Central Research Institute of Electric Power Industry

Central Research Institute ofElectric Power Industry

XTAP (eXpandable Transient Analysis Program)

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Central Research Institute ofElectric Power Industry

XTAP (eXpandable Transient Analysis Program)

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Central Research Institute ofElectric Power Industry

Power System Simulation Methods
Simulation by voltages and currents
Simulation by phasors

EMT Simulation
Three-phase, waveform-level
solution

EMT: Electro-MagneticTransient

1 μs

1 ms

Phasor
Simulations

Steady-State
Simulations

Positive-sequence,phasor solution

Positive-sequence,phasor solution

Transient stability andfrequency stabilitysimulations.

1s

10 s
Time Scale

Power flow, fault, voltage
stability and small-signal
stability simulations.

Steadystate4

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Types of EMT Simulations
Lightning overvoltages, Very-fasttransients (VFTs), EMC

Abnormal oscillations, Transformer inrush
currents, Temporary overvoltages (TOVs)

Switching overvoltages, Fault overvoltages,
Transient recovery voltages (TRVs)
Controller design, protective relay settings
System interconnection, Power quality

μsms
Time scales5

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Applications XTAP can be used not only for traditional EMT simulations but also

for new simulation needs.
 Abnormal Overvoltages, Currents and Oscillations: Lightning, switching and black-start overvoltages.
 Transformer and induction motor/generator inrush currents.
 Ferroresonance and subsynchronous resonance.

 Power Quality Assessments:
 Harmonics, flicker and voltage interruptions/drops/swells.

 Performance Studies of Power Electronics Converters:
 HVDC systems, FACTS devices, power electronics converters used in renewableenergy (PV and wind) generation systems and battery storage (EV) systems.
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Simulation Project # 1 − Large Power System Simulation
Including an HVDC Transmission (Shikoku Electric Power)
Entire Shikoku system with a250-kV HVDC transmission
system has been modeledin XTAP for various
simulation purposes.

Simulation: Power-flow inversion

DC voltage and current

HVDC converter station models in XTAP.

control signals

Source: Kawakami et al., IEEJ Power & Energy Society Meeting, 227, 2012.

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Simulation Project # 2 − Design of an MMC HVDC
Transmission System (Hokkaido Electric Power)
A new HVDC interconnection between Hokkaido and Honshu (mainisland) is now under operation. It uses the Modular Multi-level Converter(MMC) technology for the first time in Japan. The entire HVDC
transmission system has been modeled in XTAP for its design studies.

Source: Kikuma et al., IEEJ Trans. on Power & Energy, Vol. 133, No. 5, pp. 449-456, 2013.

AC Fault Simulation

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Simulation Project # 3 − Calculation of Zero-Sequence
Circulating Currents in Cables (Kansai Electric Power)

Multiple-voltage, multiple-circuitunderground cable systems havebeen modeled in XTAP in detail so
as to accurately calculate zerosequence circulating currents. The
study has solved a problem of aprotective-relay malfunction.

Duct Arrangement
Source: Koine, R&D News Kansai, Vol. 468, pp. 2-3, May 2012.

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Simulation Project # 4 − Calculation of Zero-Sequence
Circulating Currents in Cables (Tohoku Electric Power)
Substation A
154 kV

Gen. station B
154 kV

Trench section
Ckt #1
Ckt #2

Substation A
66 kV

Cable arrangement inthe trench section

154-kV TL A-B

66-kV TL A-C

Two busses are
disconnected.
Substation C

Ckt #1
Ckt #2

Substation D

Comparison between field tests and simulations
Case1
2
3
4
5

Magnitude of I0thfield testsimulation

Phase angle of I0thfield test
simulationoooooooooo

Cable arrangement in
the duct section

Two underground cable lines,
one is 154 kV and the other is66 kV, share the same routein a trench. For relay settings
related to zero-sequencecurrents, circulating zerosequence currents I0th due toelectromagnetic couplings
and impedance imbalancemust be assessed precisely.
For this purpose, XTAP is used,
and the simulation results
agree well with corresponding
field-tests results.

Source: Misawa et al., Tohoku Branch Meeting of Electric-Related Academic Societies, 2A13, 2017.

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3φ 200 V

voltage [V]Simulation Project # 5 Transformer Inrush Currents(Kyushu, Tohoku and Shikoku Electric Power)
Circuit breakers

200100
0-100-200

abc
0.04

Transformer
current [A]CCΦ [Wb]

R1

L1

Proposed model

L2

0.055

0.06

0.065

abc-0.1
0.04

0.045

0.05time [sec]

0.055

0.06

0.065

10.5

abc

0-0.5
-1

R2

0.05
time [sec]0-0.2

C0.045

0.2
0.1

0.04

0.045

0.05
time [sec]

0.055

0.06

0.065

Ring-down transient example
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measured
calculated

Secondary winding

current [A]30

Primary winding

25
20
15
105
00

12

34

5678

910

11

12

13

1415

energization timing [ms]Inrush current simulation results

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The three electric
power companies andCRIEPI developed amagnetizing circuit
model for transformer
inrush current
simulations. Thismodel is able toreproduce not only
inrush transients but
also ring-down ones,
and the model
parameters can easily
by obtained by utilityengineers.

Source: Yonezawa et al., IEEJ Trans. on Power & Energy, Vol. 134, No. 9, pp. 749-758, 2014.

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Simulation Project # 6 Multiphase Flashover of Transmission
Lines (Hokuriku, Chugoku, Kyushu and Okinawa Electric Power)
1st circuit

2nd circuit

a: flashover phases obtained by field recording
b: flashover phases predicted by the conventional method.
c: ac voltages at the instance of the flashover.

The four electric power companies andCRIEPI developed a method to predict
multiple flashover phases of atransmission line using the statisticalsimulation function of XTAP. It takes
into account the statistical characteristics of flashover. The developed method, in a statistical sense, predicts
multiple flashover phases which cannot be predicted by the conventional deterministic method.
Source: Itamoto et al., IEEJ Annual Meeting, 7-060, 2018.

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Simulation Project # 7 Studies for the High-Power
Testing Laboratory (CRIEPI)Central ResearchInstitute of ElectricPower Industry(CRIEPI) performs
various tests at theHigh-Power Testing
Laboratory inYokosuka. XTAP isused for its studies.

Comparison of short-circuit currents.

Comparison of a transient recovery voltage (TRV).

Source: Ohtaka et al., IEEJ Power & Energy Society Meeting, 361, 2012.

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Simulation Project # 8 Protection Relay Settings atDistribution Substations (Hokuriku Electric Power)
Faulted feeder

Zero-seq. voltage
Sound feeders
Example of Sensitivity Prediction
Formula for Sensitivity Prediction

For details, see the paper below.

Source: Aoki et al., IEEJ Annual Meeting, 6-309, 2018.

Zero-seq. current

Hokuriku Electric Power carried out studies of protective relay
settings at distribution substations using XTAP and the Smart
Grid Simulator of CRIEPI in Yokosuka. As a result, a formula topredict the sensitivity of the line-to-ground fault relay used
was derived and rationalized the necessary procedures.
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Simulation Project 9 − Lightning Protection ofDistribution Lines (Chubu Electric Power)
Experimental Setup

Simulation ModelField Test

Simulation

Traditionally, communication wires installed below phase wires are not considered in lightning-protection
design of distribution lines. Since the communication wires are equipped with a metallic messenger wire,
it also carries part of a lightning current and thus reduces lightning overvoltages. This study first madeclear the role of communication wires in the lightning-protection design.
Source: Ishimoto et al., IEEJ Trans. on Power & Energy, Vol. 131, No. 7, pp. 591-601, 2011.

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Simulation Project 10 − Interference of an SVR anda PV System (Tohoku Electric Power)time

It was reported that an SVR (step voltage regulator) which is operable under reverse power flow interferedwith a large PV generation system and failed to detect the substation direction. The cause has been identified
by XTAP, and an improved control system of the SVR has been validated using XTAP before installation.
Source: Nagashima et al., IEEJ Trans. on Power & Energy, Vol. 137, No. 2, pp. 154-155, 2017.

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Web Site - www.xtap.org

XTAP is available to everyone for free of charge andcan be downloaded from this site.
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XTAP
https://www.xtap.org/© 2022 Central Research Institute of Electric Power Industry