Decision Tree Based Dynamic Security
Assessment for WECC System
Group 9
Jonathan Devadason, Horacio Silva
4.5.2016
Constraints summary
PG4<501.46
PG65_2>994.13
40GW
Load
5-2
Constraints summary
PG6>753.61
42.5GW
Load
5-3
Constraints summary
45GW
PG6<764.39
Load
5-4
Constraints summary
PG4<418.49
PG9<1743.54
47.5GW
Load
5-5
Constraints summary
PG4<336
50GW
Load
5-6
Constraints summary
PG4<329.62
PG9>1728.05
52.5GW
Load
5-7
Constraints summary
PG4<317.83
PG11<1981.40
55GW
Load
5-8
Constraints summary
Slack bus
PG77>3518.83
PG6>760
PG13>1727.04
57.5GW
Load
5-9
Generation adjustment
Slack bus
Two analysis for redistributing
generation to avoid excess of power
in PG77:
•
Approach 1: Gen. Buses 180 & 181
•
Approach 2: Power redistribution
5-10
First adjustment approach
5-11
Case Scenarios (Approach 1)
Case
Load (GW)
Percentage
Change (%)
Generation (GW)
Percentage
Change (%)
1
58
-4.13
59.1
-3.9
2
59.5
-1.65
60.5
-1.62
60.5
0
61.5
0
61.5
1.65
62.6
1.8
3(Base)
4
TSAT Security Assessment (Approach 1)
Case
No. of secure
contingencies
No. of insecure
contingencies
1
325
32
2
325
32
3
324
33
4
319
38
Power Angle and Voltage Response
Insecure cases (61.5 GW)
Generator Rotor Angle (Degrees)
Generator Rotor Angle (Degrees)
1000
160
800
120
600
80
400
40
200
0
0
-40
-200
-80
0
4
8
12
16
0
20 Sec
4
8
12
16
20 S
4
8
12
16
20 S
Bus Voltage (pu)
Bus Voltage (pu)
1.4
1.1
1.3
1.2
1
1.1
0.9
1
0.8
0.9
0.8
0.7
0.7
0.6
0.6
0
Contingency No. 339
4
8
355: 3P @ 113# - 114
12
16
20 Sec
0
Contingency No. 320
330: 3P @ 180# - 81
Decision tree – pruned
Test option – Cross-validation with 20 folds.
Decision tree –pruned
No constrains
in generation
Second adjustment approach
TSAT Security Assessment (Approach 2)
Case
No. of secure
contingencies
No. of insecure
contingencies
1
138
218
2
78
278
3
77
279
4
0
356
Decision tree – pruned (Approach 2)
Test option – Cross-validation with 20 folds.
Decision tree –pruned (Approach 2)
PG13>=1800.18
PG4<=309.95
Final Data collection
Decision tree – pruned (Approach 2)
Test option – Cross-validation with 20 folds.
Decision tree –pruned
PG13>=1800.8
PG4<=309
PG77>=668.2
PG6<=744.18
PG11<=1786.44
PG65_1<=973.2
PG35>=2808.8
PG40<=1363.1
Conclusions
• The constraints depend upon how the power is distributed
among the generators.
• New constraints in addition to the existing ones appear
here where all the cases are considered.
• Finally, above 60GW, the system is highly stressed.
5-24
Thanks!
5-25