'No single factor responsible for grid failures'

'No single factor responsible for grid failures'
V K Gupta
26 August, 2012
The enquiry commttee report on grid failures has failed to pin-point the exact cause of grid failures. 1 1 0 NO SINGLE factor was responsible for grid disturbances on 30th and 31st July, is the finding of four-member enquiry committee, headed by A S Bakhsi, Chairman Central Electricity Authority.

The committee has identified several factors, which led to the collapse of the power systems on both the days and these include the protection system of transmission lines, depleted transmission network, overdrawals by states, non-compliance of directions of regional load Dispatch Centre and Regulatory commissions.

It has been noted by committee that during the disturbances on 30th and 31st July 2012, tripping was initiated by 400 KV Bina- Gwalior-Agra transmission lines. It also observed that one circuit of 400 kV Bina-Gwalior-Agra section was taken under planned outage by power grid for upgradation to 765 kv level. A number of 400 kv lines were out prior to the incidence on both these days. The outage of 400 kv Bina-Gwalior–Agra for up-gradation work, non-availability of 400 kV Zerda-Kankroli and 400 kv Bhinmal-Kankroli due to insulator problems weakened the northern western system Interface.
Committee recorded that as per record 400 kV Bina-Gwalior line was not thermally overloaded. The line tripped on zone-3 of Main-II protection. It was also noted that on both days, only Main-II protections operated and Main-I protection did not pick up. There were several other concurrent conditions, which ultimately led to collapse of grid. There is no doubt that the tripping of system is attributable to load encroachment.
The committee further noted that states do not take the messages of load dispatch centers seriously. In these cases also messages issued by NRLDC to various SLDCs for reduction of overdrawals by various states to save the system went unheeded. There was hardly any reduction in flow on Bina Gwalior line.
The committee has made various suggestions including upgrading of protection system of transmission lines.
Rajinder Kaul, who was member of CBIP committee on EHV protection said: "Load encroachment has caused the false trip of 400 kv Bina-Gwalior line, and initiated these grid failures." It looks as if it is a copy of some old Grid Disturbance Report. Same type of reasons and same age-old recommendations. Nothing has been learnt from previous Grid disturbances.