Brief Review of EMTP and Emerging Application To Renewable

August 2020Khosro Kabiri, Ph.D., P.Eng.

PSC North America

Brief Review of EMTP and Emerging Application To Renewable Generation Assessment

Proprietary and ConfidentialProprietary and Confidential

Khosro Kabiri, Ph.D., P.Eng.

Principal ConsultantPSC North America

[email protected]

Presenter Information

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mailto:[email protected]

http://www.pscconsulting.com/


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


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!


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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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3LG Fault at POI 200 MW Battery Connected at 345 kV


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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Documents

Brief Review of EMTP and Emerging Application To Renewable