BY

G.SRI KEERTHI

09241A02A6

POWER GRID FAILURE

INTRODUCTION

• India is divided into five electrical regions.

INDIAN POWER GRID

EASTERN

WESTERN

NORTH-EASTERN

SOUTHERNNORTHER

N

NEW GRID

• Very complex power transmission network

• Its functioning, from power generation to power distribution is more or less the same across all regional zones.

STABLE GRID

• The stability of a grid is determined by keeping a check on the demand and supply.

• Power frequency reflects the balance between load and power generation in the grid at a given instant.

• Permissible frequency band specified by the Indian Electricity Grid Code (IEGC) of the Central Electricity Regulatory Commission, effective May 3, 2010, is 49.5 to 50.2 Hz.

• Stability of the grid depends on a delicate equilibrium of demand-supply chain.

LOAD DEMAND CURVE

CAUSES FOR GRID FAILURE• Natural causes:

( lightening, rain, snow, ice, wind, dust, floods, storms )

• Brown out:

( drop in electric power supply )

• Black out:

( complete loss of power to a geographic area )

• Power surges:

( leads to rapid overheating and loss of critical and expensive equipment )

• Electrical treeing:

( effects high power installations )

BLACKOUT IN INDIA 2012• According to the data available from the Power System

Operation Corporation Ltd. (PSOC), the grid frequency was in between the specified limits.

0 2 4 6 8 10 12 1449.4

49.5

49.6

49.7

49.8

49.9

50

50.1

50.2

July 30,2012

Time

Fre

qu

en

cy

Factors that led to the initiation of the Grid Disturbance on 30th

July, 2012• Weak Inter-regional Corridors due to multiple outages:

oSystem was weakened by multiple outages of transmission lines in the WR-NR interface.

o400 kV Bina-Gwalior-Agra (one circuit) was the only main AC circuit available between WR-NR interface prior to the grid disturbance.

• High Loading on 400 kV Bina-Gwalior-Agra link:

oOverdrawal by some of the NR utilities contributed to high loading on this tie line.

• Inadequate response by SLDCs to the instructions of RLDCs to reduce overdrawal by the NR utilities and underdrawal/excess generation by the WR utilities.

• Loss of 400 kV Bina-Gwalior link:

oDue to load encroachment (high loading of line resulting in high line current and low bus voltage).

Factors that led to the initiation of the Grid Disturbance on 31st July,

2012• Weak Inter-regional Corridors due to multiple outages:

oSystem was weakened by multiple outages of transmission lines in the NR-WR interface and the ER network near the ER-WR interface.

oOn this day also, effectively 400 kV Bina-Gwalior-Agra (one circuit) was the only main circuit available between WR-NR.

• High Loading on 400 kV Bina-Gwalior-Agra link:

oAlthough real power flow in this line was relatively lower than on 30th July, 2012, the reactive power flow in the line was higher, resulting in lower voltage at Bina end.

• Inadequate Response by SLDCs to RLDCs’ instructions on this day also to reduce overdrawl by the NR utilities and underdrawal by the WR utilities.

• Loss of 400 kV Bina-Gwalior link:

oTripping of 400 kV Bina-Gwalior line on zone-3 protection of distance relay, due to load encroachment, caused the NR system to separate from the WR system.

•A similar near-miss situation occurred on November 28, 2009, when the same circuit carrying around 1000 MW tripped on one of its phases.

• led to subsequent cascade tripping of other parallel lines in the corridor.

• the system survived because of support from generators and quick operator action.

CASCADING EFFECT• A cascading failure is a failure in a system of interconnected

parts in which the failure of a part can trigger the failure of successive parts.

• It may happen in many types of systems, including power transmission, computer networking, finance and bridges.

• common in power grids when one of the elements fails (completely or partially) and shifts its load to nearby elements in the system.

• nearby elements are then pushed beyond their capacity so they become overloaded and shift their load onto other elements.

• The primary problems with preventing electrical grid failures is that the speed of the control signal is no faster than the speed of the propagating power overload.

• They are overcome by using superconducting magnetic energy storage units at critical junctions can store or release power for a few seconds to allow control systems to catch up and actuate isolating procedures.

IMPACT OF THE FAILURE

• It led to 14,000 MW generation losses.

• 684 million people from 21 states & UTs were affected.

• Power supply to the Indian rail network was also hit which lead to over 300 trains coming to a standstill. More than 100 Delhi Metros stalled.

• Traffic signals went on the blink.

• The water distribution system, major water treatment plants across the states came to a halt.

PREVENTIVE MEASURES

• At a hospital or other piece of vital public infrastructure, make sure the back-up generators are maintained at optimum levels at all times.

• Businesses need to keep track of their transformers, insuring that they’re serviced, tested, and cleaned.

• Making sure that plant technicians are aware of all requisite safety information.

• Power plant operators must consistently follow the strictures and operating procedures presented to them by the individual plant manufacturer.

CHANGES TO BE ADOPTED IN THE POWER SYSTEM

• CREATING REDUNDANT LINES:The combination of power lines provides excess capacity. Circuit breakers disconnect a power line when monitors detect an overload. Power is redistributed across the remaining lines.

•UPGRADATION OF TRANSMISSION LINES:Upgrading the existing lines to higher value can also help in prevention of frequent tripping of the lines.

• SMART GRID APPLICATION.

•DEVELOPMENT OF RENEWABLE ENERGY TO MEET PEAK DEMAND.

•GOVERNMENT SHOULD TRY TO ENFORCE THE LAWS VERY STRICTLY LIKE IN USA AND UK.

•UNEVEN REGULATION SHOULD BE PREVENTED.

CONCLUSION• In July 2012, for two consecutive days millions of

people in India suffered from a crippling power crisis after power grids failed in many parts of the country.

• India is not the only country that suffers from grid issues.

• But India seems to have suffered arguably the worst crisis in terms of the population that got affected.

• A variety of urgent measures are needed to overcome the various challenges that are spreading like a wildfire.

THANK YOU

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