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IEEE Chapter Symposium. Nima Farkhondeh Jahromi Zongyu Liu. Possible Applications of PMUs for Detecting Angle Instability in Power Systems. Outline. Problem Formulation Angle Stability Classification First Proposed PMU-Based Algorithm Second Proposed PMU-Based Algorithm - PowerPoint PPT Presentation
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April 21, 2023
1
IEEE Chapter Symposium
Possible Applications of PMUs for Detecting Angle Instability in Power
Systems
Nima Farkhondeh Jahromi Zongyu Liu
April 21, 2023 2
Outline
• Problem Formulation• Angle Stability Classification• First Proposed PMU-Based Algorithm• Second Proposed PMU-Based Algorithm• Conclusion and Remarks
April 21, 2023 3
Problem Formulation• Centralized Power plants
Small number of large scale gen. units • Traditional generator design/const. Not so high efficiency
• Popularity of renewable energy
Large number of small scale gen. units
• Newer Technology in generator design Higher efficiency
Power networks (due to power transfer capacity) get closer to their stability margin
Less tolerance
• Regulated electricity market • Deregulated electricity market
Various power flow directions
More congestions
Contradictory combination
Stability control (instability detection) is (will be) the key challenge
April 21, 2023 4
Angle Stability Classification
[Real-time] Angle Stability Assessment in future Power Systems
Axis 1[Real-time] large disturbance angle stability (transient stability) assessment
Axis 2:[Real-time] small disturbance
angle stability assessment
April 21, 2023 5
1st Proposed PMU-based Algorithm
Detection of transient instability based on the real-time COA
• Concept of Centre Of Angles (COA)
1
1
:
: .
N
i ii
COA N
ii
i
i
H
H
Internal machine rotor angle
H Inertia time cte
Difficult to directly measure
Difficult to access in real time. Number of units being dispatched can vary
April 21, 2023 6
1st Proposed PMU-based Algorithm (1)
• Substitution of the internal angle with the phase angle of the high side bus voltage
• Substitution of the inertia time constant with the high side active power injection
GTU U
Phase Measurement Unit (PMU)
high side injection massP MApproximation! (could be a source of
error)
April 21, 2023 7
1st Proposed PMU-based Algorithm (2)
• Illustration of substitution of the inertia time constant with the high side active power injection
April 21, 2023 8
1st Proposed PMU-based Algorithm (3)
• Real-time Centre of Inertia for area i
• Real-time Centre of Inertia for the whole system
1
1
( )
Ni ij j
jic iN
ij
j
P
g tP
1
1
( )
Ni ic
ic sysN
i
j
Pg t
P
April 21, 2023 9
1st Proposed PMU-based Algorithm (4)
Taking the appropriate remedial action(s) based on the value of
• If > “pre-specified benchmark” (continuously)
1) Area i (in a detailed analysis each gen. can be an area) is speeding up2) Suitable remedial action is to trip some generators
• If < “pre-specified benchmark” (continuously)
1) Area i (in a detailed analysis each gen. can be an area) is slowing down2) Suitable remedial action is load shedding
ic
ic
ic
April 21, 2023 10
1st Proposed PMU-based Algorithm (5)
Alarm mode based on comparing the real-time signals
• A real-time signal for area i
• A signal to be used as a reference: Critically-stable response
( ) ( ) ( )ic c i sys ig t g t f t
( ) ( ) ( )ic crt stab c crt stab i crt stab sys crt stab i crt stabg t g t f t
April 21, 2023 11
1st Proposed PMU-based Algorithm (6)
• Rescue-time definition
Permanent decline
April 21, 2023 12
1st Proposed PMU-based Algorithm (7)
• The method (the reference signal) is fault-location (and also fault-type) dependent.
• The method is dependent on the inertia time constant of the generators (Perhaps in future; lighter machines have higher output)
April 21, 2023 13
2nd Proposed PMU-based Algorithm • Principal idea is to have a real-time energy function (by means of PMUs) for a system divided into two clusters.
• The main question: Based on the real-time energy function, will the system split to more clusters or not?
Area 1M1ω1
Area 2M2ω2
New [temporary] steady-state
2 21 2
1 21 2
1 2
, 1 2
( )1 1( )
2 2
,
( , ) ( ) ( )
K eff eff eff
eff eff
K line line steady state
dE M M
dtM M
MM M
V E P P d
April 21, 2023 14
2nd Proposed PMU-based Algorithm (2)
April 21, 2023 15
Conclusion and Remarks
• It might be possible to perform an on-line transient instability detection and mitigation for a multi-area power systems
• By improving (generalizing) the proposed algorithm, it might be possible to avoid some blackouts happen due to islanding
• Designing the appropriate remedial action, is very much dependent on the system capabilities and is difficult to be generalized
April 21, 2023 16
Discussions
Suggestions
Questions
Criticisms
Ideas
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