From security to risk assment and risk
control
E. Ciapessoni
– AFTER coordinator – RSE
D. Cirio - RSE
F
T
ER
UE Project N.
261788
Vulnerability of PS
Vulnerabilities
Physical infrastructure - power
2
2
ENTSO-E requirements
:
• A single incident, e.g.: line, tie-line, DC link, transformer, generator
• A single incident in neighbouring TSO grid, having impact in own grid
• Out of scope:
busbar
(
it happens with low probability: it is a system vulnerability
)
Additional requirements adopted by some TSOs
:
• Busbar fault for 400 kV substations
Vulnerability of PS
Vulnerabilities
Physical infrastructure - power
3
3
Main causes of damages due to natural
events:
1.
Wind storms
2.
Ice storms
Vulnerability of PS-ICT
Logical failures
Monitoring
Control
Protection
Defence
Fiber optics damaged by rodents
e.g. Wrong settings of protections…
Vulnerabilities
Infrastructure damages due to external events
Component
ageing
Natural Threat dependency
earthquakes
landslides
floods
Strong wind
Power system
vegetation
Ground movements
Component damages due to ground acceleration
Overflowing dams
Component damages
e.g. transformer
outages
e.g. OHL pylons damaged
e.g. OHL conductor damages
fires
e.g. transformer damages/explosion
Lateral contacts
Increasing sag
Higher stress
Rain/ice/
snow
Animals
Pollution
e.g. insulator
flashover
Bird drops
e.g. increases salt deposit in marine environments
Solar storms
Component damages
Black out
7
…
Uncertainties
…
Risk of… what
?
Uncontrolled
islanding
Cascading
Voltage
instability
Loss of load
Current
violation
Initiating event(s)
Frequency
instability
Angle
instability
Voltage
violation
€
N-1
security against
a credible set of
contingencies
Vulnerability
to
events of
substantial
risk
FROM
security analysis
TO
vulnerability/risk analysis
Key features
•
Not only N-1:
–
N-2, … ,
N-k
–
including
dependent
contingencies
–
Uncertainties
•
Multiple contingency selection
•
Cascading simulation
•
Operational risk assessment
–
Possible to link the
risk based security assessment
to
real time monitoring
systems
9
The bow tie model
Focus
•
Multiple contingencies (functional and geographic dependencies)
•
ICT dependencies
•
Cascading
Multi-layer perspective of the power & ICT systems
Threat classification
12
ICT THREATS
External
Internal
Natural
e.g. Ice and snow, Heavy
flood,
Fire and high temperature,
Geomagnetic storm
e.g. Operation out of
range, Internal faults,
Ageing
Human related
e.g. Hacker, Sabotage,
Malicious outsider
e.g. Employee errors
Malicious actions by
unfaithful employees, SW
PHYSICAL THREATS
External
Internal
Natural
e.g. lightnings, fires,
ice/snow storms, solar
storms
e.g. Component faults,
strained operating
conditions
Man related
e.g. unintentional damage by
operating a crane; Sabotage,
terrorism
outsider errors
e.g. Employee errors
Malicious actions by
unfaithful employees
AFTER Risk Assessment : work flow
Threat models (T)
Component Vulnerability
models (V)
Impact indices (I)
Risk indices (RI)
Injection
uncertainties
Other
influent
factors
Models of
automatic/manual
actions (SPS,
Operator…)
possibly affected
by ICT failures
Power / ICT component fault
and probability models (F)
Scenario
generator
Threat and
vulnerability
data
Selection
criteria
C
ri
ti
c
a
l
s
c
e
n
a
ri
o
s
e
le
c
ti
o
n
(
C
S
S
)
Power / ICT contingency
and probability models (C)
Post-fault response and
probabilities (R)
Application for control center: risk assessment of a system state
(uncertainty on contingencies)
14
operator
EMS
Power
SCADA
RTU’s, PMU’s
Security level
requirements
Alarms/alerts/
(suggested
control
actions)
On-line alert systems
Control actions
Some
N-2’s
N-1’s
Conventional
security
assessment
S
e
c
u
ri
ty
A
s
s
e
s
s
m
e
n
t
State Estimation / Power flow
Risk based
security
assessment
C
o
n
ti
n
g
e
n
c
y
s
e
le
c
ti
o
n
0
5
10
15
20
25
30
35
40
0
2
4
6
8
x 10
-4
High current Risk Index Cumulative Curve (time interval = 10 minutes)
Contingency
ctg: N-2-Ln-10 -Ln-36 ( cum % risk: 94.3)
ctg: N-1-B15Y211-B24Y221 ( cum % risk: 32.0)
ctg: SB-B24Y221 ( cum % risk: 99.6)
0 20 40 60 80 100 120 140
SB_B03I301_no_signal_to_one_CB SB_B03I301_no_signal_to_one_CB SSB2_B09Q301_BUSFAULT_stuckCB_L_IQ37 SSB2_B09Q301_BUSFAULT_stuckCB_T_B11Q211T1SSB1_B15Y211_PP_BUSFAULT_stuckCB_L_YY210SSB1_B15Y211_PP_BUSFAULT_stuckCB_L_YW28SSB2_B15Y211_PP_BUSFAULT_stuckCB_L_YW29SB_B24Y221_BUSFAULT_stuckCB_T_B24Y224T2SB_B24Y221_stuckCB_FAULT_ON_T_B24Y224T2SSB1_B09Q301_BUSFAULT_stuckCB_L_KQ311SSB1_B09Q301_BUSFAULT_stuckCB_L_IQ36SB_B03I301_BUSFAULT_stuckCB_L_II32 SSB1_B09Q301_BUSFAULT_stuckCB_T_B12Q212T3SSB1_B09Q301_stuckCB_FAULT_ON_T_B12Q212T3SSB2_B09Q301_stuckCB_FAULT_ON_T_B11Q211T1SSB2_B15Y211_PP_stuckCB_FAULT_ON_L_YW29SSB1_B15Y211_PP_stuckCB_FAULT_ON_L_YW28SSB1_B15Y211_PP_stuckCB_FAULT_ON_L_YY210SSB2_B15Y211_PP_BUSFAULT_stuckCB_L_YY27SSB2_B15Y211_PP_stuckCB_FAULT_ON_L_YY27SB_B03I301_BUSFAULT_stuckCB_T_B24Y224T2SB_B03I301_stuckCB_FAULT_ON_T_B24Y224T2SSB1_B09Q301_stuckCB_FAULT_ON_L_KQ311SSB1_B09Q301_stuckCB_FAULT_ON_L_IQ36SSB2_B09Q301_stuckCB_FAULT_ON_L_IQ37SB_B24Y221_BUSFAULT_stuckCB_L_YY210SB_B24Y221_stuckCB_FAULT_ON_L_YY210SSB1_B15Y211_PP_no_signal_to_one_CBSSB1_B15Y211_PP_no_signal_to_one_CBSSB2_B15Y211_PP_no_signal_to_one_CBSSB2_B15Y211_PP_no_signal_to_one_CBSB_B03I301_BUSFAULT_stuckCB_L_IQ36SB_B03I301_stuckCB_FAULT_ON_L_IQ36SB_B03I301_stuckCB_FAULT_ON_L_II32N-3_Ln_10 _Ln_36 _2WND_B24YT2N-2_Ln_10 _2WND_B24YT2N-2_Ln_36 _2WND_B24YT2SB_B24Y221_BDP_OOSSB_B03I301_BDP_OOSN-1_B03I301_B09Q301N-1_B15Y211_B24Y221N-1_B01I301_B03I301N-2_Ln_10 _Ln_36 SSB2_B15Y211_PPSSB1_B15Y211_PPSSB2_B09Q301SSB1_B09Q301SB_B24Y221N-1_B24YT2N-1_B24YT2SB_B03I301
Angle instability Risk (dt = 10 minutes)- TOTAL Risk= 0.02686
Conti ngency ID dB (Level O = 1e-015)
N-2’s
N-1’s
«Risky»
N-k’s
THE MODULES
The AFTER global risk assessment TOOL
Requirements
for contingency selection
Need to consider:
–
Possible dependence among components affected
by one threat
•
Geographical / functional dependences
•
ICT and PS components
–
Interdependencies among different threats
Multiple contingencies definition
•
Geospatial dependence:
–
A threat may impact over a large portion of the grid affecting
several components
•
Need to define geospatial models for threats
•
Functional dependence:
–
Double circuit faults (a line affected by a threat may fall on
the other line of a double circuit)
–
Busbar contingencies (different responses of primary
protection systems)
–
Power plant PP contingencies (faults on PP interconnection
substation)
Contingency selection
- Manual selection
-
All N-1 ctgs
-
N-2 ctgs by operator’s
selection
- Automatic selection
-
multiple N-k
contingencies
-
power plant and busbar
ctgs, considering possible
malfunctioning of
protection systems
-
Multiple branch
contingencies due to
extensive effect of a
common threat (e.g. a
storm)
Definition of multiple
contingencies
Identifying set of critical
components
(
Cumulative sum
screening method
)
Probability of failure of
components
Set of contingencies to be analysed
Complete set
of N-1 ctgs ,
some N-2 ctgs
selected by
operators
PS/ICT response modeling
Two simulation approaches to catch
adequate metrics of the impact of
contingency on the ICT/PS:
–
A
quasi-static cascading engine
(built
upon the PRACTICE tool) which
evaluates the possible cascading
paths triggered by a contingency
using a robust load flow-based
approach
–
Time domain simulators
, in order to
evaluate the dynamic response of the
ICT/PS immediately after the
application of contingencies by
running a fully dynamic power system
model.
19
Evaluating the impact of a
contingency on the integrated
system
•
Significant focus on
cascading
mechanisms
•
Possible
instability
phenomena
occurring during
post contingency transients
Rationale of the algorithm
AFTER impact indicators
•
Aim: quantifying the impact of a contingency on
ICT/PS
•
AFTER approach proposes several indicators:
–
Indices based on immediate
post-fault steady-state
quantities (currents and voltages)
–
Indices based on
cascading outcome (loss of load, cost of
unsupplied energy)
–
Indices to detect
instability
mechanisms (angle and
voltage deviations)
AFTER risk indicators
•
Risk = set of triples {contingency, probability,
impact}
•
Common indicator = expected value of impact
•
Technical Risk indicators (TRI) are :
–
TRI based on post contingency quantities
–
TRI based on cascading outcome
HOW CAN THE AFTER TOOL BE
INTERESTING FOR TSO’S?
The AFTER global risk assessment TOOL
AFTER tool applications
•
Identifying
multiple contingencies with highest probabilities
in
short term,
–
combining component failure probabilities
–
complementing traditional N-1 criterion
•
Identifying
most vulnerable
components in
current
weather/environment conditions
•
Evaluating
sensitivity of specific component parameters on the
probability of failure
of ICT/power components
–
Thanks to probabilistic models of component vulnerability
–
Possible to improve vulnerability with targeted interventions
Future perspective for AFTER tool
•
Linking the
contingency probabilities to real time data
from
monitoring systems
–
storm alert systems in control centers
THREATS, VULNERABILITIES AND
CONTINGENCIES MODELS:
EXAMPLES
The AFTER global risk assessment TOOL
Example 1: storm
Failure probability of lines dependence on
storm intensity (peak wind speed)
Storm affecting North-West of Sicily transmission system (early
2000’s)
Above wind speed
values for line
design!!!
Impact of wind
direction vs line
direction
Example 1: storm
Failure probability of lines dependence on
storm intensity (peak wind speed)
Storm affecting North-West of Sicily transmission system (early
2000’s)
Above wind speed
values for line
design!!!
Impact of wind
direction vs line
direction
27
Useful to drive targeted actions in operational planning
(deloading of some branches, ecc.)
Example 2: pollution
0
50
100
150
200
250
300
180
200
220
240
260
280
300
320
ISBA111
ISBA811
ISBA821
ISBA822
ISBA831
RIZN111
RIZN311
RIZN312
ANPP211
ANPP212
ANPP731
ANPP741
BLLP211
BLLP311
BLLP312
CRCP211
CRCP311
CRCP312
CRCP313
CHGP111
CHGP211
CHGP311
CMRP211
CMRP311
CMRP312
CORP211
CORP311
FAVP211
FAVP311
FAVP312
FULP211
FULP311
MLLP211
MLLP311
MLLP312
MLLP313
MSBP211
MSBP311
MSBP312
PNAP211
PNAP311
PNAP312
PRRP211
PTRP111
PTRP311
PRGP211
PRGP711
PRGP811
RAGP211
RAGP311
SFMP211
SFMP212
SFMP221
SFMP231
SFMP711
SFMP821
SFMP831
SRGP111
SRGP211
SRGP311
SRGP312
TIMP211
TIMP711
TIMP811
km
k
m
75
80
85
90
95
100
105
110
115
120
125
270
275
280
285
290
295
300
BLLP211
BLLP311
BLLP312
CRCP211
CRCP311
CRCP312
CRCP313
CMRP211
CMRP311
CMRP312
PRRP211
TIMP211
TIMP711
TIMP811
km
k
m
X= 106.4013
Y= 280.4013
Level= 0.022769
Stress variable
scalar field
Typical densities for heavily polluted
environments [CIGRE TB sources]
Linking maintenance plans to a maximum
admissible probability of failure?
Example 3: lightnings
GFD (ground flash
density) expressed in
# of flashes/km^2*hour
29
COMPONENTS WITH
HIGHEST PROBABILITY
OF FAILURE
Pf (nr failures/ 10
minutes)
CMRP211 - CRCP211
0.00195
CMRP211 - CRCP211
0.00195
BLLP211 - CRCP211
0.001385
BLLP211 - CRCP211
0.001385
CMRP211 - PRRP211
0.000804
CMRP211 - PRRP211
0.000804
CORP211 - CRCP211
0.000244
CORP211 - CRCP211
0.000244
CRCP211 - TIMP211
8.40E-05
VT at node CMRP31
3.35E-05
From
real time data of
threats
to
failure
probability
of
components!
AN OPERATIONAL RISK ASSESSMENT
APPLICATION
The AFTER global risk assessment TOOL
Threat, vulnerability and component failure models
31
0
10
20
30
40
50
60
70
80
20
40
60
80
100
120
140
160
180
B11Q211
B12Q211
B13U211
B14Y211
B15Y211
B16Y211
B17W211 B18W211
B19X211
B20X221
B21W221
B22W221
B23X221
B24Y221
B01I301
B02K301
B03I301
B04I301
B05I301
B06K301
B07K301
B08K301
B09Q301
B10Q311
km
k
m
Polluting agents
at
nodes 3 and 24
Peak value of pollution
concentration:
13
µ
µ
µ
µ
g/cm
2
Spatial distribution of
stress variable
Selection of critical components
32
CRITICAL COMPONENT
FAILURE PROB.
(next 10
minutes)
B15Y211 - B24Y221
0.25387
B03I301 - B09Q301
0.14409
B01I301 - B03I301
0.086235
Potential Transformer (PT) at
node B24Y221
0.075969
B24Y221 - B03I301
0.075969
PT at node B03I301
0.044622
busbars at node B24Y221
0.038949
Selection of contingency scenarios
33
CTG ID
Prob. of occurrence
(next 10 min)
'N-1_B24YT2'
0.034049623
'N-1_B15Y211_B24Y221'
0.163413657
'N-1_B01I301_B03I301'
0.048204656
'N-1_B03I301_B09Q301'
0.07945655
'N-2_Ln_10
_2WND_B24YT2'
0.013435
'N-2_Ln_32
_2WND_B24YT2'
0.00396313
'N-2_Ln_36
_2WND_B24YT2'
0.006532494
'N-2_Ln_10 _Ln_32 '
0.019020167
'N-2_Ln_10 _Ln_36 '
0.031351264
'N-2_Ln_32 _Ln_36 '
0.009248168
'N-2_Ln_27 _Ln_16 '
0
'N-2_Ln_28 _Ln_10 '
0
'N-2_Ln_21
_2WND_B11QT1'
0
'N-2_Ln_21 _Ln_33 '
0
'N-2_Ln_18 _Ln_21 '
0
'N-2_Ln_15 _Ln_38 '
0
'N-2_Ln_16 _Ln_21 '
0
'N-2_Ln_23 _Ln_38 '
0
'N-2_Ln_11
_2WND_B12QT3'
0
'N-2_Ln_23 _Ln_14 '
0
'N-2_Ln_11 _Ln_16 '
0
'N-2_Ln_32 _Ln_10 '
0
'N-2_Ln_35
_2WND_B11QT4'
0
'N-2_Ln_14 _Ln_21 '
0
'N-3_Ln_10 _Ln_32
_2WND_B24YT2'
0.001563737
'N-3_Ln_10 _Ln_36
_2WND_B24YT2'
0.002577534
'N-3_Ln_32 _Ln_36
_2WND_B24YT2'
0.000760335
'N-3_Ln_10 _Ln_32
_Ln_36 '
0.00364906
'N-4_Ln_10 _Ln_32
_Ln_36 _2WND_B24YT2'
0.000300006
'N-1_B24YT2'
0.022561151
'SB_B24Y221'
0.052238651
'SB_B03I301'
0.028086227
'SSB1_B09Q301'
1.03E-05
Possible to include N-2 ctgs deemed as
“dangerous” by operators
All N-1’s
-> for complete security analyses
No N-1’s
-> complementary to conventional
N-1 security analyses
Only critical N-1’s
Includes all N-k deemed as topologically
“risky” for next 10 min!
ICT/PS response
Impact evaluation (I): post contingency currents
and voltage
34
0
5
10
15
20
25
30
35
40
0
0.05
0.1
0.15
0.2
Current-based Severity Index Cumulative Curve (time interval = 10 minutes)
Contingency
ctg: N-2-Ln-10 -Ln-36 ( cum % risk: 37.7)
ctg: N-2-Ln-25 -Ln-26 ( cum % risk: 75.7)
ctg: N-3-Ln-10 -Ln-36 -2WND-B24YT2 ( cum % risk: 97.9)
0
5
10
15
20
25
30
35
40
0
1
2
3
Low Voltage Severity Index Cumulative Curve (time interval = 10 minutes)
Contingency
ctg: N-2-Ln-10 -Ln-36 ( cum % risk: 43.4)
ctg: N-3-Ln-10 -Ln-36 -2WND-B24YT2 ( cum % risk: 82.5)
ctg: N-2-Ln-36 -2WND-B24YT2 ( cum % risk: 20.1)
High current
impact
Low voltage
impact
Easy to detect the contingencies
with largest contributions!!
Impact evaluation (II): loss of load from quasi
static cascading engine (one path)
35
0
5
10
15
20
25
30
35
40
0
0.1
0.2
0.3
0.4
0.5
LOL Risk Index Cumulative Curve (time interval = 10 minutes)
Contingency
ctg: N-2-Ln-36 -2WND-B24YT2 ( cum % risk: 30.7)
ctg: N-2-Ln-10 -Ln-36 ( cum % risk: 87.1)
ctg: N-3-Ln-10 -Ln-36 -2WND-B24YT2 ( cum % risk: 100.0)
Dynamic response (I)
Possible to analyse different timing sequences
for protection interventions
36
CTG
ID
Description
ICT
failure/stuck
breaker
Action
1
Busbar
fault
with
correct
operation of all CBs and BDP
(bus differential protection)
NO
Intervention of BDP
2a
Busbar fault with malfunction of
one signal to a CB
YES
, miss signal to a CB Intervention of BDP and
breaker
failure device
on one CB
2b
Busbar fault +one stuck breaker
YES
, one CB stuck
Intervention of BDP and back up
protection for one CB
3a
Busbar fault +missing signal to
bus coupler K
YES
, missing signal to K Intervention of BDP for faulty
half-busbar
+
back-up protections
for
components of safe half-busbar
3b
Busbar fault with stuck K
YES
, stuck K
Intervention of BDP for faulty
half-busbar + breaker failure device for
components of safe half-busbar
3c
Busbar fault with BDP out of
service
YES
, BDP out of service Intervention of all backup
protections for all components at
two half-busbars
Possible to analyse different timing sequences
for protection interventions
37
CTG
ID
Description
ICT
failure/stuck
breaker
Action
1
Busbar
fault
with
correct
operation of all CBs and BDP
(bus differential protection)
NO
Intervention of BDP
2a
Busbar fault with malfunction of
one signal to a CB
YES
, miss signal to a CB Intervention of BDP and
breaker
failure device
on one CB
2b
Busbar fault +one stuck breaker
YES
, one CB stuck
Intervention of BDP and back up
protection for one CB
3a
Busbar fault +missing signal to
bus coupler K
YES
, missing signal to K Intervention of BDP for faulty
half-busbar
+
back-up protections
for
components of safe half-busbar
3b
Busbar fault with stuck K
YES
, stuck K
Intervention of BDP for faulty
half-busbar + breaker failure device for
components of safe half-busbar
3c
Busbar fault with BDP out of
service
YES
, BDP out of service Intervention of all backup
protections for all components at
two half-busbars
YES
-> N-k
-j
contingencies
accounting for ICT
failures/misoperation
Impact evaluation (III): angle instability impact
continuous metrics
38
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0.045
SSB1_B15Y211_PP
SB_B03I301_stuckCB_FAULT_ON_L_IQ36
SSB2_B09Q301_stuckCB_FAULT_ON_L_IQ37
SSB1_B09Q301_BUSFAULT_stuckCB_T_B12Q212T3
SSB1_B09Q301_BUSFAULT_MSig_CB_T_B12Q212T3
N-2_Ln_10 _Ln_36
N-2_Ln_18 _Ln_12
SB_B03I301_stuckCB_FAULT_ON_T_B24Y224T2
N-2_Ln_36 _2WND_B24YT2
N-2_Ln_15 _Ln_17
N-1_B15Y211_B16Y211_PP
N-1_B12QT3
SSB1_B15Y211_PP_stuckCB_FAULT_ON_L_YY210
N-1_B11QT1
SSB2_B15Y211_PP_BUSFAULT_stuckCB_L_YY27
N-2_Ln_16 _Ln_33
N-2_Ln_11 _Ln_32
N-2_Ln_11 _Ln_33
N-2_Ln_25 _Ln_26
SSB2_B09Q301_no_signal_to_one_CB
SSB2_B09Q301_no_signal_to_one_CB
SSB1_B15Y211_PP_stuckCB_FAULT_ON_L_YW28
SSB2_B15Y211_PP_stuckCB_FAULT_ON_L_YW29
SSB1_B09Q301_no_signal_to_one_CB
SSB1_B09Q301_no_signal_to_one_CB
SSB1_B09Q301_no_signal_to_one_CB
N-2_Ln_10 _2WND_B24YT2
N-2_Ln_12 _Ln_19
N-2_Ln_24 _Ln_13
SSB2_B15Y211_PP_stuckCB_FAULT_ON_L_YY27
N-2_Ln_13 _Ln_18
SB_B24Y221_no_signal_to_one_CB
SB_B24Y221_no_signal_to_one_CB
SSB1_B09Q301_stuckCB_FAULT_ON_L_KQ311
SSB1_B09Q301_stuckCB_FAULT_ON_L_IQ36
N-2_Ln_34 _2WND_B12QT3
SSB1_B09Q301_stuckCB_FAULT_ON_T_B12Q212T3
SB_B03I301
N-3_Ln_10 _Ln_36 _2WND_B24YT2
SB_B03I301_BDP_OOS
SB_B03I301_no_signal_to_one_CB
SB_B03I301_no_signal_to_one_CB
SB_B03I301_no_signal_to_one_CB
N-2_Ln_16 _Ln_39
N-2_Ln_21 _2WND_B11QT1
N-2_Ln_11 _2WND_B12QT5
N-2_Ln_31 _Ln_39
SSB1_B15Y211_PP_no_signal_to_one_CB
SSB1_B15Y211_PP_no_signal_to_one_CB
SSB2_B15Y211_PP_no_signal_to_one_CB
SSB2_B15Y211_PP_no_signal_to_one_CB
Angle based Instability Impact Index (dt = 10 minutes)
Impact value
C
o
n
ti
n
g
e
n
c
y
I
D
Angle stability problems
concentrated around power
plant
substation at node 15
Risk indicators
Risk evaluation (I): static indicators linked to
post contingency values
39
0
5
10
15
20
25
30
35
40
0
2
4
6
8
x 10
-4
High current Risk Index Cumulative Curve (time interval = 10 minutes)
Contingency
ctg: N-2-Ln-10 -Ln-36 ( cum % risk: 94.3)
ctg: N-1-B15Y211-B24Y221 ( cum % risk: 32.0)
ctg: SB-B24Y221 ( cum % risk: 99.6)
Contingency
0
5
10
15
20
25
30
35
40
0
0.01
0.02
0.03
0.04
Low Voltage Risk Index Cumulative Curve (time interval = 10 minutes)
Contingency
ctg: N-1-B15Y211-B24Y221 ( cum % risk: 75.8)
ctg: N-2-Ln-10 -Ln-36 ( cum % risk: 94.6)
ctg: SB-B24Y221 ( cum % risk: 99.5)
High current risk
Low voltage risk
High contributions from N-1’s
(due to higher prob.) but also by
Risk indicators
Risk evaluation (II): loss of load risk indexes
from one path cascading engine
40
0
5
10
15
20
25
30
35
40
0
0.1
0.2
0.3
0.4
0.5
LOL Risk Index Cumulative Curve (time interval = 10 minutes)
Contingency
ctg: N-2-Ln-36 -2WND-B24YT2 ( cum % risk: 30.7)
ctg: N-2-Ln-10 -Ln-36 ( cum % risk: 87.1)
ctg: N-3-Ln-10 -Ln-36 -2WND-B24YT2 ( cum % risk: 100.0)
Highest contributions from N-k
contingencies!
Dynamic PRA
Risk evaluation (III): angle instability risk
41
0
20
40
60
80
100
120
140
SB_B03I301_no_signal_to_one_CB
SB_B03I301_no_signal_to_one_CB
SSB2_B09Q301_BUSFAULT_stuckCB_L_IQ37
SSB2_B09Q301_BUSFAULT_stuckCB_T_B11Q211T1
SSB1_B15Y211_PP_BUSFAULT_stuckCB_L_YY210
SB_B24Y221_BUSFAULT_stuckCB_T_B24Y224T2
SSB1_B09Q301_BUSFAULT_stuckCB_L_KQ311
SSB1_B15Y211_PP_BUSFAULT_stuckCB_L_YW28
SSB2_B15Y211_PP_BUSFAULT_stuckCB_L_YW29
SSB1_B09Q301_BUSFAULT_stuckCB_L_IQ36
SB_B24Y221_stuckCB_FAULT_ON_T_B24Y224T2
SB_B03I301_BUSFAULT_stuckCB_L_II32
SSB1_B09Q301_BUSFAULT_stuckCB_T_B12Q212T3
SSB1_B15Y211_PP_no_signal_to_one_CB
SSB1_B15Y211_PP_no_signal_to_one_CB
SSB2_B15Y211_PP_no_signal_to_one_CB
SSB2_B15Y211_PP_no_signal_to_one_CB
SB_B03I301_BUSFAULT_stuckCB_L_IQ36
SB_B24Y221_BUSFAULT_stuckCB_L_YY210
SB_B03I301_BUSFAULT_stuckCB_T_B24Y224T2
SSB2_B15Y211_PP_BUSFAULT_stuckCB_L_YY27
SB_B24Y221_stuckCB_FAULT_ON_L_YY210
SB_B24Y221_BDP_OOS
SSB2_B09Q301_stuckCB_FAULT_ON_T_B11Q211T1
SB_B03I301_stuckCB_FAULT_ON_L_II32
SB_B03I301_stuckCB_FAULT_ON_L_IQ36
SSB2_B09Q301_stuckCB_FAULT_ON_L_IQ37
SB_B03I301_stuckCB_FAULT_ON_T_B24Y224T2
SSB1_B15Y211_PP_stuckCB_FAULT_ON_L_YY210
SSB1_B15Y211_PP_stuckCB_FAULT_ON_L_YW28
SSB2_B15Y211_PP_stuckCB_FAULT_ON_L_YW29
SSB2_B15Y211_PP_stuckCB_FAULT_ON_L_YY27
SSB1_B09Q301_stuckCB_FAULT_ON_L_KQ311
SSB1_B09Q301_stuckCB_FAULT_ON_L_IQ36
SSB1_B09Q301_stuckCB_FAULT_ON_T_B12Q212T3
SB_B03I301_BDP_OOS
N-3_Ln_10 _Ln_36 _2WND_B24YT2
N-2_Ln_36 _2WND_B24YT2
N-1_B01I301_B03I301
N-1_B24YT2
N-1_B24YT2
N-2_Ln_10 _2WND_B24YT2
N-2_Ln_10 _Ln_36
N-1_B03I301_B09Q301
N-1_B15Y211_B24Y221
SSB2_B09Q301
SSB1_B09Q301
SB_B24Y221
SSB2_B15Y211_PP
SSB1_B15Y211_PP
SB_B03I301
Angle instability Risk (dt = 10 minutes)- TOTAL Risk= 0.02686
C
o
n
ti
n
g
e
n
c
y
I
D
dB (Level O = 1e-015)
Highest contributions from N-k
busbar contingencies
N-k-j ctgs (with j
ICT failure) with
highest impact
not at top of list
Risk of losing load: effect of hidden failures
42
0
10
20
30
40
50
0
0.5
1
1.5
2
2.5
3
LOL Risk Index Cumulative Curve (time interval = 10 minutes)
Contingency
1% Hidden failures
one path (no hidden failures)
Evaluating the effect of Hidden
Failures on the risk of losing loss at
the end of cascading
HF’s may increase a lot the risk
for specific contingencies
Application for control center:
risk assessment of a system state - uncertainty on contingencies
43
operator
EMS
Power
system
SCADA
RTU’s, PMU’s
Security level
requirements
Alarms/alerts/
(suggested
control
actions)
On-line alert systems
Control actions
Some
N-2’s
N-1’s
Conventional
security
assessment
S
e
c
u
ri
ty
A
s
s
e
s
s
m
e
n
t
State Estimation / Power flow
Risk based
security
assessment
C
o
n
ti
n
g
e
n
c
y
s
e
le
c
ti
o
n
0
5
10
15
20
25
30
35
40
0
2
4
6
8
x 10
-4
High current Risk Index Cumulative Curve (time interval = 10 minutes)
Contingency
ctg: N-2-Ln-10 -Ln-36 ( cum % risk: 94.3)
ctg: N-1-B15Y211-B24Y221 ( cum % risk: 32.0)
ctg: SB-B24Y221 ( cum % risk: 99.6)
0 20 40 60 80 100 120 140
SB_B03I301_no_signal_to_one_CB SB_B03I301_no_signal_to_one_CB SSB2_B09Q301_BUSFAULT_stuckCB_L_IQ37 SSB2_B09Q301_BUSFAULT_stuckCB_T_B11Q211T1SSB1_B15Y211_PP_BUSFAULT_stuckCB_L_YY210SSB1_B15Y211_PP_BUSFAULT_stuckCB_L_YW28SSB2_B15Y211_PP_BUSFAULT_stuckCB_L_YW29SB_B24Y221_BUSFAULT_stuckCB_T_B24Y224T2SB_B24Y221_stuckCB_FAULT_ON_T_B24Y224T2SSB1_B09Q301_BUSFAULT_stuckCB_L_KQ311SSB1_B09Q301_BUSFAULT_stuckCB_L_IQ36SB_B03I301_BUSFAULT_stuckCB_L_II32 SSB1_B09Q301_BUSFAULT_stuckCB_T_B12Q212T3SSB1_B09Q301_stuckCB_FAULT_ON_T_B12Q212T3SSB2_B09Q301_stuckCB_FAULT_ON_T_B11Q211T1SSB2_B15Y211_PP_stuckCB_FAULT_ON_L_YW29SSB1_B15Y211_PP_stuckCB_FAULT_ON_L_YW28SSB1_B15Y211_PP_stuckCB_FAULT_ON_L_YY210SSB2_B15Y211_PP_BUSFAULT_stuckCB_L_YY27SSB2_B15Y211_PP_stuckCB_FAULT_ON_L_YY27SB_B03I301_BUSFAULT_stuckCB_T_B24Y224T2SB_B03I301_stuckCB_FAULT_ON_T_B24Y224T2SSB1_B09Q301_stuckCB_FAULT_ON_L_KQ311SSB1_B09Q301_stuckCB_FAULT_ON_L_IQ36SSB2_B09Q301_stuckCB_FAULT_ON_L_IQ37SB_B24Y221_BUSFAULT_stuckCB_L_YY210SB_B24Y221_stuckCB_FAULT_ON_L_YY210SSB1_B15Y211_PP_no_signal_to_one_CBSSB1_B15Y211_PP_no_signal_to_one_CBSSB2_B15Y211_PP_no_signal_to_one_CBSSB2_B15Y211_PP_no_signal_to_one_CBSB_B03I301_BUSFAULT_stuckCB_L_IQ36SB_B03I301_stuckCB_FAULT_ON_L_IQ36SB_B03I301_stuckCB_FAULT_ON_L_II32N-3_Ln_10 _Ln_36 _2WND_B24YT2N-2_Ln_10 _2WND_B24YT2N-2_Ln_36 _2WND_B24YT2SB_B24Y221_BDP_OOSSB_B03I301_BDP_OOSN-1_B03I301_B09Q301N-1_B15Y211_B24Y221N-1_B01I301_B03I301N-2_Ln_10 _Ln_36 SSB2_B15Y211_PPSSB1_B15Y211_PPSSB2_B09Q301SSB1_B09Q301SB_B24Y221N-1_B24YT2N-1_B24YT2SB_B03I301
Angle instability Risk (dt = 10 minutes)- TOTAL Risk= 0.02686
Conti ngency ID dB (Level O = 1e-015)
N-2’s
N-1’s
«Risky»
N-k’s
AN OPERATIONAL PLANNING
APPLICATION
The AFTER global risk assessment TOOL
Uncertainties on initial ICT/PS conditions
45
t
-
k
hours
tt +
∆
t
time
contingency
k
-hour ahead forecast errors
eP
eP
for stochastic inputs
Short term probability distributions for
∆
P
∆
Initial state
∆
P
e
P
GOAL : how does the
operational risk
of a
PS subjected to a set of contingencies
depend on the
forecast error distributions
of
RES production and load absorptions
GOAL
46
how does the
operational risk
of a PS
subjected to a set of contingencies depend
on the
forecast error distributions
of RES
production and load absorptions available k
hours ahead?
Stress variable spatial
distribution for next
quarter of hour
GOAL
47
how does the
operational risk
of a PS
subjected to a set of contingencies depend
on the
forecast error distributions
of RES
production and load absorptions available k
hours ahead?
K hour ahead forecast
errors for RES and loads
K hour ahead forecast
errors for RES and loads
GOAL
48
how does the
operational risk
of a PS
subjected to a set of contingencies depend
on the
forecast error distributions
of RES
production and load absorptions available k
hours ahead?
Probability
distributions for
security risk
indicators
RESULTS
Characterising the uncertainties …
49
Parameters of RES and load
forecast error models
Characterising the uncertainties …
50
Input data to model correlations
among forecast errors
2
2.5
3
3.5
4
4.5
x 10
-5
0
0.2
0.4
0.6
0.8
1
CTG N-2-Ln-248 -Ln-249 : probability of overcoming the value of risk of high currents on x axis
0
1
2
3
4
x 10
-5
mean
standard deviation
-0.5
0
0.5
1
skewness
kurtosis
CTG N-2-Ln-248 -Ln-249 - skewness and kurtosis of risk of high currents
3.3
3.4
3.5
3.6
3.7
3.8
x 10
-5
0
0.2
0.4
0.6
0.8
1
CTG N-2-Ln-248 -Ln-249 : probability of overcoming the value of risk of low voltages on x axis
0
1
2
3
4
x 10
-5
mean
standard deviation
-0.6
-0.4
-0.2
0
0.2
skewness
kurtosis
CTG N-2-Ln-248 -Ln-249 - skewness and kurtosis of risk of low voltages
Assessing impact of uncertainties
51
0.85
0.9
0.95
1
1.05
1.1
1.15
1.2
1.25
1.3
1.35
x 10
-4
0
0.5
1
Probability of overcoming the value of total risk of high currents on x axis
6.7
6.8
6.9
7
7.1
7.2
7.3
7.4
x 10
-5
0
0.5
1
Probability of overcoming the value of total risk of low voltages on x axis
0
0.5
1
1.5
2
2.5
3
3.5
4
x 10
-3
0
0.5
1
Probability of overcoming the value of total risk of loss of load on x axis
Probability of overcoming a
specific value of …
total risk index
High currents
Low voltage
Loss of load
risk index
for any contingency
2
2.5
3
3.5
4
4.5
x 10
-5
0
0.2
0.4
0.6
0.8
1
CTG N-2-Ln-248 -Ln-249 : probability of overcoming the value of risk of high currents on x axis
0
1
2
3
4
x 10
-5
mean
standard deviation
-0.5
0
0.5
1
skewness
kurtosis
CTG N-2-Ln-248 -Ln-249 - skewness and kurtosis of risk of high currents
3.3
3.4
3.5
3.6
3.7
3.8
x 10
-5
0
0.2
0.4
0.6
0.8
1
CTG N-2-Ln-248 -Ln-249 : probability of overcoming the value of risk of low voltages on x axis
0
1
2
3
4
x 10
-5
mean
standard deviation
-0.6
-0.4
-0.2
0
0.2
skewness
kurtosis
CTG N-2-Ln-248 -Ln-249 - skewness and kurtosis of risk of low voltages
Assessing impact of uncertainties
52
x 10
-5
0
0.5
1
1.5
2
2.5
3
3.5
4
x 10
-3
0
0.5
1
Probability of overcoming the value of total risk of loss of load on x axis
Loss of load
Acceptable loss of load, LOL
Risk*
Cyan Area = Probability that Risk is higher
than LOL R*
Application for operational planning:
Risk assessment of a forecast state - uncertainty on contingencies and initial state
53
Prob(
Risk
>
Acceptable R*
) >
εεεε
?
operator
EMS
Security level
requirements
Driving operational
planning decisions …
k-hour ahead
forecasts for
RES and load
Forecasting critical grid
scenarios (weather
forecasts, monitoring
equipment conditions over
days…)
Allocate resources
to preserve
desired security
levels
global risk assessment
AFTER tool
Conventional
planning
tools
subset of
N-2’s
«Risky»
N-k’s
N-1’s
Risk based
Operational
planning support
tool
Contingency
selection
22.533.544.5 x 10-5 0 0.2 0.4 0.6 0.8 1 CTG N-2-Ln-248 -Ln-249 : probabilit y of overcoming t he value of risk of high currents on x axis0 1 2 3 4 x 10-5
mean standard deviat ion
-0.5 0 0. 5 1 skewnesskurtosis
CTG N-2-Ln-248 -Ln-249 - skewness and ku rtosi s of ris k o f hi gh curre nts 3.33.43. 53.63.73.8 x 10-5 0 0.2 0.4 0.6 0.8 1 CTG N-2-Ln-248 -Ln-249 : probability of overcoming the value of risk of low voltages on x axis
0 1 2 3 4 x 10-5 mean standard deviat ion
-0.6 -0.4-0.2 0 0.2 skewnesskurtosis
CTG N-2-L n-2 48 -L n-2 49 - skewne ss and kurtosis of risk of low voltage s 0.85 0.9 0.95 1 1.05 1.1 1.151.2 1.25 1.3 1.35
x 10-4 0
0.5 1
Pr obability of overcoming the value of total risk of high currents on x axis
6.7 6.8 6.9 7 7.1 7.2 7.3 7.4 x 10-5 0
0.5 1
Probability of overcoming the value of total r isk of low voltages on x axis
0 0.5 1 1.5 2 2.5 3 3.5 4 x 10-3 0
0.5
1 Probability of overcoming the value of total risk of loss of load on x axis
