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.
Reasoning the Major power disturbancein India - 30th, 31st July 2012Siva Prasad Katrusivakatru@gmail.com
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
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 2600Census 2001 - 44% of householdsdo not have access to electricity.Mission 2012: Power for All
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 effectedMajor power blackout• The outage must not be planned by the service provider.• There must be at least 1,000,000 person- hours of disruption.
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.
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
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 1314MWNR constituents were instructed by NRLDC Agra GorakhpurWRLDC 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
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 faultPrior to disturbance conditions • This phenomenon is called “Load encroachment”. 29884MW NR 1014 MW 33945MW NER 1226MWNR constituents were instructed by NRLDC Agra GorakhpurWRLDC 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
References1) http://www.powermin.nic.in/pdf/GRID_ENQ_REP_16_8_12.pdf2) http://en.wikipedia.org/wiki/Electricity_sector_in_India3) http://www.bbc.co.uk/news/world-asia-india-190602794) 100 million Indonesians affected by power outage. AP5) "The Darkest Night". Archived from the original on 2009-05-13. Retrieved 2010-10-08.6) The great 2003 North America blackout. CBC7) Italys blackout raises questions. The Guardian8) The Great Northeastern Blackout of 1965. CBC