Download VOLTAGE STABILITY

VOLTAGE STABILITY
On-line assessment
Future power system operation
• Power transfers are increased
• Environmental reasons restrict the
expansion of networks
• Better service is required for a
reduced cost
Data pre-processing
Line flows
DATA
Voltage stability problem
• A power system has a limited capability to transmit power especially
reactive power to the loads
• Voltage instability point is needed
to assess in order to quarantee secure operation in normal operation
point and after disturbances
Neural network approach
Voltages
Outage list
Network topology
Unit commitment
NN
PostMargin
Model creation
Data calculation and analysis
Input feature selection/extraction
Estimation of model parameters
Generalization capability testing
•
•
•
•
Neural network generalization test
Target value = x
NN output=o
V
o
l
t
a
g
e
most critical
contingency
normal operation
point
maximum
loading
point
pre-margin
post-margin
Parameter
1.2
1.15
1.1
0
10
20
30
40
50
60
Case number
70
80
90
100
0
10
20
30
40
50
60
Case number
70
80
90
100
Output error
0.02
0.01
0
−0.01
−0.02
15
Histogram
Voltage stability assessment
• The most critical voltage stability
margin describes the available
transfer capacity
– Number of contingencies is
studied
– Collapse points are calculated
Margin
1.25
10
5
0
−0.02
−0.01
0
0.01
0.02
0.03
Output error
Test results and conclusions
• Accurate voltage stability margin
approximation with neural network
(maximum output error is 2%)
• Model creation time is reduced
significantly by input feature
selection and extraction
www.elteknik.chalmers.se
Visiting researcher
Sami Repo
Tampere University of Technology, Finland
Research project is funded by Graduate School
in Electrical Engineering and FINGRID Plc.