August 2020Khosro Kabiri, Ph.D., P.Eng.
PSC North America
Brief Review of EMTP and Emerging Application To Renewable Generation Assessment
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Khosro Kabiri, Ph.D., P.Eng.
Principal ConsultantPSC North America
Presenter Information
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Introduction Historical Development Breakthroughs
Current State of the Art Common Areas of Application EMTP for Renewable Generation Studies Data Requirements
Outline
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Generally known as a tool to study Fast transients in power systems
Lightning, Switching overvoltages, Inrush currents, etc. Power Electronic Devices
Time-Domain Simulation Time is discretized Time constants matter!
How is it different from electromechanical simulation? frequency Network representation
Electromagnetic Transients Simulation
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A Bit of HistoryElectromechanical Stability Simulation
Electromagnetic Transients Simulation
To study rotor angle stability of synchronous machines
To study overvoltages in transmission lines
First program 1956 First program 1963 in Technical University Munich
PSS®E 1972 Dommel’s classic paper 1969:“Digital Computer Solution of Electromagnetic Transients in Single-and Multiphase Networks”IEEE PAS-88 Issue4
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EMTP Development Groups BPA EMTP
Hermann Dommel, Scott Meyer, Tsu-huei Liu ATP is a free version, requires license
UBC EMTP (MicroTran) H. Dommel, J. Marti, L. Marti
DCG/EPRI EMTP Development Coordination Group formed in 1982 EMTP-RV (1997) mainly developed by Jean Mahseredjian
PSCAD – EMTDC First code written by Dennis Woodford in 1975 Manitoba HVDC Research Centre founded in 1981 Commercially available since 1993
NETOMAC (Siemens) Initially developed by B. Kulicke, now embedded in SINCAL
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Connecting synchronous machine differential equations to network equations
Stability simulation covers a limited range of frequencies to about 5 Hz
“Power System Stability and Control”, Prabha Kundur, McGraw-Hill, 1994.
Electromechanical Simulation Breakthrough
�𝑌𝑌 �𝑉𝑉 = ̅𝐼𝐼
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Solving large sets of network differential equations using digital computers
EMTP Breakthrough
�𝑌𝑌 �𝑉𝑉 = ̅𝐼𝐼 Stability𝑅𝑅 𝑉𝑉 = 𝐼𝐼 + 𝐼𝐼ℎ EMTP
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Excerpt from EMTP Theory Book
… engineers who have read one or one too manytextbooks on electric circuits and networks, mayhave been misled to believe that Laplacetransform techniques should be used …. Laplacetransform techniques are only useful for “handsolutions” of rather small networks, and more orless useless for computer solutions of problemsof the size typically analyzed with the EMTP.Since even new textbooks perpetuate the myth ofthe usefulness of Laplace transforms, …
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Bergeron Line Model (also known as Dommel’s line model)
EMTP Breakthrough
Zs ZsIh1 Ih2
+
-
V1
I1+
-
V2
I2
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Extensive library of components Unsymmetrical representation and events A large range of frequencies Advanced tools for visualization and output analysis Graphical User Interface Scripting capability Provisions for modelling large networks
Sparse Matrix Utilization Network splitting
EMTP Today
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E M T PA P P L I C A T I O N S
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Applications – Insulation Coordination
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Lightning Switching Equipment Energization
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Lattice Diagram
RZ1 Z2
𝑒𝑒
𝐿𝐿𝑣𝑣
𝛽𝛽2𝛼𝛼2𝑒𝑒
𝛼𝛼1 𝛼𝛼2
𝛾𝛾1 𝛾𝛾2 𝛽𝛽1 𝛽𝛽2
2𝐿𝐿𝑣𝑣
0
TIM
E
𝐿𝐿
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Challenge of modelling periodic Switching Pulse arriving in the middle of time step Numerical oscillations
HVDC, FACTS Design/Test controllers
Real-Time Digital Simulation
Applications – Power Electronics
3-PhaseAC
DC
+
-
~
T1
T1
D2
T1
T2
D1
T2
D2
T1 D1
T2
T4
T5
T6
T3
T2
D1
D2
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Out of stability simulation zone Frequency scanning
Application - Subsynchronous Interaction
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Renewable Energy Sources
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Converter-based Synchronization with the power system through measuring the voltage at
the point of coupling. Use of Phase-Locked Loop (PLL) This measurement can be erroneous when the system is weak (low short circuit levels)
Synchronous machines are retiring Short Circuit MVA is decreasing Total inertia is decreasing
PLL model in stability studies is simplified Instability can go unnoticed!
Renewable Energy Sources
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Stability simulation can be used for limited interaction studies due to masking of some frequency areas
Usually these interactions become a problem when a large number of renewable farms are connected electrically close to each other
Can happen in frequencies out of stability realm Instability can go unnoticed!
Control Interaction
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Renewable Energy Sources
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3LG Fault at POI 200 MW Battery Connected at 345 kV
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To represent networks in three-phase to include asymmetry Many sources are connected to single-phase distribution level lines
To not be limited to a range of frequencies of 5 Hz band around the synchronous frequency
Renewable sources often have converters (same reason as HVDC)
Why use EMTP for Renewable Studies?
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Modelling very large networks Multicore Simulation Hybrid Simulation
Lack of Data Parametric studies Generic Models
Challenges
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Very successful in bypassing lack of data caused by confidentiality and other issues
Has been adopted in North America and some other parts of the world These models are made for stability type simulations
WECC Generic Models
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As the push for use of EMTP programs is on the rise. There might be a good reason to develop a few generic models for EMTP Decoupled DQ control Phase-locked Loop Plant controller (can be similar to stability models) Detailed power electronics bridge (6-pulse bridge, etc.) with IGBT switches Unit Scaling
WECC Generic Models for EMTP?
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AEMO (Australian Energy Market Operator) Extensive use of proprietary models Australian system is geographically widespread with large distances between load and
generation pockets.
ISO-NE Each developer is asked to submit both PSSE and PSCAD models. PSSE models have to be
generic. PSCAD models are proprietary.
ISO Examples
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E M T PD A T A R E Q U I R E M E N T S
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Transmission line data Transformer data including saturation Lumped component data (inductors, capacitors) Machine data Converter data Surge arrester data Substation Layout CTs, VTs, CVTs Graphical Data Other data
EMTP Data Requirements
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ISOs and Utilities are collecting EMTP models from developers of renewable energy sources. Intention is to use for wide-area simulation Study of Control Interactions
ISOs and Utilities benefit from Common Data Format Common Application Programming (API) Interface between programs
Last Word
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P R O G R A M D E M O
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2 Area System
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Thank You!
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PSC at a Glance
180Subject matter
experts
25+Countries
served
>20Offices in North
America, Europe & Asia Pacific
25Years inbusiness
200+Clients
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