Transcript Current focuses on deregulated system

Voltage Security Margin
Assessment
By Drs. G. Huang and A. Abur
Students: N. Nair, L. Zhao
H. Zhang( not paid through pserc)
Task 1: Modeling of control
devices, loads and transactions
for stability evaluations.
• Modeling FACTS devices 70% Finished
• Modeling Tap-changing transformers for its
reactive power drawing capability 70% Finished
• Modeling exciters 70% Finished
• Modeling loads 70% Finished
• Modeling transactions 40% Finished
Highlights:
• Insight on Dynamic Reserve vs Static Reserve
( dynamic reserve paper)
• Margin based on Static Analysis is 10% too
optimistic for most cases
• TCUL has major impacts on dynamic margin 30%
or more
• Voltage regulating exciters cannot be replaced by
static var reserve.
Task 2 :Use of Stability Margin
and Stability Index Calculations
• Develop a program according to the new models
to simulate the dynamic responses 70% Finished
• Analysis of Modeling Impacts 40% Finished
• Use of stability indices as a transaction scheduler
• Use of utilization indices as basis for auxiliary
service charges
• Develop equipment investment indicators
• Tests and documentation
Highlights
• Weakness of PV curves are found. For some loads, the lower part of
the PV curve do not indicate instability.
 Indicator L gives an information as regards to the stability margin from
the steady state voltage collapse point.
• It has been observed that L calculated on the simulated dynamic data at
the instance of the largest dip in the voltage at the load bus following a
disturbance can give information as regards to the voltage stability
margin.
• An OPF based algorithm to evaluate load curtailment incorporating
voltage stability margin has been formulated based on the proposed
index L.
Task 3: Transaction based
stability margin and utilization
factors calculation
• Formulate the transaction based power flow analysis
problem 70% finished
• Develop software for transaction based power flow
analysis for decompositions 50% finished
• Develop software to calculate utilization factor for control
equipments
• Develop software for finding decomposed utiliziation
factors and stability margins for individual transactions.
• Test case and documentation
Highlights
 A transaction based power flow (TBPF) analysis and prototype
program has been developed.
 The utilization of MW flows, Mvar flows, MVA flows, transmission
losses and reactive power losses of bilateral transactions is part of the
TBPF solution.
• Potentials for the deregulated power market, such as loss allocation,
parallel flow evaluation, congestion management and settlement,
reactive power pricing, Flowgate and ATC assessment etc
• High computation efficiency
 With appropriate logic modification, common power flow programs
embedded in EMS function can be readily extended for TBPF purpose.
Task No:
1.1
1.2
1.3
1.4
1.5
2.1
2.2
2.3
2.4
2.5
2.6
3.1
3.2
3.3
3.4
3.5
3 mo
3 mo
70%
70%
70%
40%
40%
70%
80%
P
P
N
N
70%
50%
30%
P
N
Schedule of Tasks
3 mo
3 mo
3 mo
CR
CR
CR
DCR
DCR
CR
C
R
B
B
P
B
P
D&C
B
C
R
P
P
P: Preparing some information and theory background
N: Not begin to work yet;
R: Report is needed;
C: Need to do some Correctness checking;
D: Develop the program
B: Begin to work
3 mo
B
B
3 mo
3 mo
Desired Input from Industry:
 Real measurement data that records voltage
stability scenarios for us to check if our L
index will correctly predict the problem.
 Real measurement data that indicate PV
curve monitoring do not work for lighting
or resistance loads. But we will demonstrate
that our L indicator will work.