I have prepared this presentation based on the report submitted by committee setup by Power ministry of India. This presentation talks about the reasons behind the power blackout that happened on 30th & 31st July 2012.

1. Reasoning the Major power disturbance
in India - 30th, 31st July 2012
Siva Prasad Katru
sivakatru@gmail.com

2. Contents
• Indian power sector at a glance
• What happened on 30th, 31st July 2012
• Background - Power Swings, Distance relays
• Analysis of Grid Disturbance on 30th July
• Analysis of Grid Disturbance on 31st July
• Role of distance relay
• Conclusion

3. Indian power sector at a glance
Grid MW
Northern 56058
Western 66757
Eastern 26838
North 2454.94
Eastern Agra
Southern 54898.1
Gwalior
Total 2,07,006.04
Bina
per capita annual avg. kWh
consumption
India 778
European Union 6200
Worldwide 2600
Census 2001 - 44% of households
do not have access to electricity.
Mission 2012: Power for All

4. What happened on 30th & 31st July 2012
• On 30th July 2012, there was a grid
disturbance in the NEW grid at 02:33:11 IST
• NR grid collapsed
• load of about 36,000 MW effected
• Another major disturbance took place on
31st July 2012 in the NEW grid at 13:00:13
IST
• NR, ER and NER grids collapsed
• load of about 48,000 MW effected
Major power blackout
• The outage must not be planned by the
service provider.
• There must be at least 1,000,000 person-
hours of disruption.

5. Power swings
• The rotors of synchronous machines inter-connected by AC lines
tend to run at the same electrical speed in steady state due to the
underlying physics of this system.
• When this system experiences small disturbances, restorative
torques bring back the machines to synchronism (i.e., the same
electrical speed).
• This response is an oscillatory behavior = a spring-mass system. The
oscillations are called “swings” and are seen in practically all
parameters including line power flows.
• For large disturbances (e.g faults, loss of critical transmission links),
the behavior is non-linear and the electrical torques may be unable
to bring all the generators to the same electrical speed. If this
happens the angular difference between the generators goes on
increasing (Transient Instability or Angular Separation). This
causes large variations in voltage and power flow in lines.

6. Role of distance relay
• The impedance per mile is fairly constant
• These relays sees the impedance from the
relay location to fault location
• Observes the values of voltage and current
• Used to identify the fault location

7. Analysis of Grid Disturbance on 30th July, 2012
Committee analyzed the output of DRs, ELs, PMUs, WAFMS, SCADA data
and reports submitted by various SLDCs , RLDCs, POWERGRID and
generation utilities to arrive at the sequence of events
Prior to disturbance conditions
32636 MW
NR 1367 MW
38322MW NER
1314MW
NR constituents were instructed by NRLDC
Agra Gorakhpur
WRLDC also issued for reduction in generation.
Zerda-Bhinmal Patna – Balia
369MW 1055MW
x x
x
x Muzaffarpur
33024 MW Bina Gwalior x
WR 1450MW
Balia – Biharsharif 12452 MW
ER
28053MW
12213MW

8. Analysis of Grid Disturbance on 31st July, 2012
In the both cases, at the time of tripping of
Internal power swings, under
distance relay:
frequency and overvoltage at
• Because of Overload, voltage to current ratio
different places lead to
seen by the relay is low
collapse of NR-ER-NER
• Although there is no fault, treated it as a fault
Prior to disturbance conditions • This phenomenon is called “Load
encroachment”.
29884MW
NR 1014 MW
33945MW NER 1226MW
NR constituents were instructed by NRLDC
Agra Gorakhpur
WRLDC also issued for reduction in generation.
Patna – Balia
x
x
x Muzaffarpur
32612 MW Bina Gwalior
WR
Balia – Biharsharif 13524 MW
ER
Sipat xRanchi
-
Rajgarh xRourkela
-
28053MW
13179MW

9. References
1) http://www.powermin.nic.in/pdf/GRID_ENQ_REP_16_8_12.pdf
2) http://en.wikipedia.org/wiki/Electricity_sector_in_India
3) http://www.bbc.co.uk/news/world-asia-india-19060279
4) 100 million Indonesians affected by power outage. AP
5) "The Darkest Night". Archived from the original on 2009-05-13.
Retrieved 2010-10-08.
6) The great 2003 North America blackout. CBC
7) Italy's blackout raises questions. The Guardian
8) The 'Great Northeastern Blackout' of 1965. CBC