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Analysing the stability of an islandedhydro-electric power
system
The American Modelica Conference 2018
Dietmar Winkler
Kindly presented by Prof. Luigi Vanfretti, ALSETLab
th October
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Contents
Introduction
• Project background• Project objectives
Modelling
• The OpenIPSL library• Transmission system model
Three-generator model
Four-generator model
Simulation
• Results of two different load scenariotypes
Active and reactive load changes
Active load changes only
Conclusions
• Summary• Modelling challenges
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
Contents
Introduction
• Project background• Project objectives
Modelling
• The OpenIPSL library• Transmission system model
Three-generator model
Four-generator model
Simulation
• Results of two different load scenariotypes
Active and reactive load changes
Active load changes only
Conclusions
• Summary• Modelling challenges
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
Contents
Introduction
• Project background• Project objectives
Modelling
• The OpenIPSL library• Transmission system model
Three-generator model
Four-generator model
Simulation
• Results of two different load scenariotypes
Active and reactive load changes
Active load changes only
Conclusions
• Summary• Modelling challenges
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
Contents
Introduction
• Project background• Project objectives
Modelling
• The OpenIPSL library• Transmission system model
Three-generator model
Four-generator model
Simulation
• Results of two different load scenariotypes
Active and reactive load changes
Active load changes only
Conclusions
• Summary• Modelling challenges
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
IntroductionProject background
The Westfjords
• Low reliability of power supplyin this area
• Consumption is larger thanarea’s local production
• If connection to central grid islost loads need to be
reduced
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
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IntroductionProject objectives
Goal
• Determine optimaldisconnection sequence of
loads
• Effect of additional productionof Hvesta power station
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
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IntroductionThe transmission system
• transmission linesOperating at
132kV 66kV 33kV 11kV• load centres
Bíldudalur
Patreksfjörður
Tálknafjörður
• generating unitsMjólká , &
Hvesta
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
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IntroductionThe power stations
Mjólká
• Largest power station in the Westfjords• Total capacity of
13.25MVA• Generating units
Mjólká (Francis turbine, 3.4MVA)Mjólká (Pelton turbine,
8.5MVA)Mjólká (Francis turbine, 1.35MVA)
Hvesta
• Pelton turbine, 1.7MVAFigure: Power house of Mjólká and
Mjólká
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
ModellingThe Open Instance Power System Library
OpenIPSL
• open-source library for modelling of electrical
powersystems
• developed as an continuation of the iTesla project and
ismaintained by the ALSETLab research group
• components are based on and validated against modelsfrom the
existing power system software such as “Power
System Simulator for Engineering (PSS/E)” and “Power
System Analysis Toolbox (PSAT)”
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
ModellingThree-generator model
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
ModellingFour-generator model
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
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SimulationsScenario 1: Active and reactive loads
• Connection to the national grid is lostat 20s
• Loads are partially disconnected if thefrequency drops below a
specified limit
• Loads remain disconnected• Quality requirements:
Frequency
Voltage
Initial loads
Load name Active load Reactive load
[MW] [Mvar]
LoadTAL . .
LoadBIL . .
LoadPAT . .
Total loads . .
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
SimulationsLoad Scenario 1.1: Disconnection of LoadPAT and
LoadTAL
• % of LoadTAL and LoadPAT are disconnected• System stabilises s
after the disconnection from the national grid
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
SimulationsLoad Scenario 1.2: Disconnection of LoadBIL
• % of LoadBIL is disconnected• System stabilises s after the
disconnection from the national grid
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
SimulationsLoad Scenario 1: Additional production,
four-generator model
• The increased production of Hvesta stabilises the system•
System stabilises s after the disconnection from the national
grid
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
SimulationsScenario 2: Active loads
• Connection to the national grid is lostat 20s
• Loads are partially disconnected if thefrequency drops below a
specified limit
• Loads remain disconnected• Quality requirements:
Frequency
Voltage
Initial loads
Load name Active load [MW]
LoadTAL .
LoadBIL .
LoadPAT .
Total loads .
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
SimulationsLoad Scenario 2.1 (3G): Disconnection of LoadPAT and
LoadTAL (Three-generator)
• % of LoadPAT and LoadTAL are disconnected• System stabilises s
after the disconnection from the national grid
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
SimulationsLoad Scenario 2.1 (4G): Disconnection of LoadPAT and
LoadTAL (Four-generator)
• % of LoadPAT is disconnected (LoadTAL stays connected)• System
stabilises s after the disconnection from the national grid
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
SimulationsLoad Scenario 2.2 (3G): Disconnection of LoadBIL
(Three-generator)
• % of LoadBIL is disconnected• System stabilises s after the
disconnection from the national grid
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
SimulationsLoad Scenario 2.2 (4G): Disconnection of LoadBIL
(Four-generator)
• % of LoadBIL is disconnected• System stabilises s after the
disconnection from the national grid
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
Conclusions
LoadBIL
• Disconnection of LoadBIL gives fasteststabilisation for both
scenarios
Additional production from Hvesta
• Grid is not overloaded in scenario• Gives better voltage
stability at all buses• System stabilises slower
Modelling Challenges
• For numerical reasons parameters hadto be adjusted away from
original PSS/E
values
• Reduced load values→ simulatedvoltage levels lower than in
reality
• Sub-optimal turbine governorparameters lead to frequency
offset
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
Conclusions
LoadBIL
• Disconnection of LoadBIL gives fasteststabilisation for both
scenarios
Additional production from Hvesta
• Grid is not overloaded in scenario• Gives better voltage
stability at all buses• System stabilises slower
Modelling Challenges
• For numerical reasons parameters hadto be adjusted away from
original PSS/E
values
• Reduced load values→ simulatedvoltage levels lower than in
reality
• Sub-optimal turbine governorparameters lead to frequency
offset
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
-
Thank you!Acknowledgement and Contact
Acknowledgement
This paper is based on the work executed by Kim Aars
as part of his Master’s Thesis in with the title:
“Simulation of load and fault scenarios in a hydro
power system with island grid” in cooperation with
Verkís Consulting Engineers, Iceland
Contact
[email protected]
Analysing the stability of an islanded hydro-electric power
system – The American Modelica Conference /
mailto:[email protected]
