Wapda relied on trial-and-error methods: Delay in power restoration
By Our Staff Reporter
LAHORE, Sept 29: The Water and Power Development Authority (Wapda) did not have standard operating procedures for restating the generation system after a major breakdown, which delayed restoration of system last Sunday.
Chairman Tariq Hamid stated this on Friday after sharing inquiry committee report with the media. In the absence of such procedures, restarting the generation system was more of a trial-and-error affair for engineers.
Had these procedures been in place, the engineers would not have taken so much time in restoring the system, he said and added: “The authority would now be developing standard operating procedures within two weeks. It does not take a genius to develop the procedures, they are available on the net.”
Referring to the causes of original tripping at the Rawat-Gatti line, he said that members of the inquiry committee would now be zeroing-in on it to see what had actually happened there. The preliminary report talked about technical fault and its ramifications on the system but it still did not point out what caused the fault in the first place, he said.
According to Inquiry Committee report, “as per NPCC record, one 500-KV line between Rawat and Brotha tripped at 13:44 hours on Sept 24 on three phase fault indication from distance relay and as a result, the second 500-KV line Gatti and Brotha also tripped.”
“Subsequently, at 13:45 two 500/220-KV transformers at Rewat and two 220-KV lines between Rewat and Burhan (via Sangjani) tripped on overload. As a result of these trippings, the NTDC (National Transmission and Dispatch Company) system spilt into independent operating systems: one Northern, which grossly overloaded and other Southern with lack of power supply. The Northern system tripped because of high frequency and southern due to low/under frequency. These systems should have continued operating as independent system, but they collapsed.”
“Before start of tripping of Gatti-Brotha 500-KV lines, 220-KV circuit between Gatti and Jaranwala tripped at 13:43:09. Unit six of GTPS at 13:43:57, 220-KV circuit No2 between Bund Road and New Kot Lakhpat (Lahore) at 13:44:06 and Unit 5 of Mangla tripped at 13:44:08.
“The flow of power on 500-KV Brotha-Gatti circuit-1 increased from 1,123MW to 1,607MW and on Gatti-Brotha circuit II, the flow increased from 1,103MW to 1,587MW. Since this flow exceeded the stated limit of Brotha-Gatti 500-KV line, the system started tripping.”
The report concluded that N-1 line outage criteria had been violated and no hydroelectric power station had been assigned duty for automatic control frequency.
The report called for setting up a reliability council to regulate security of operations of the NTDC power system network. The operating criteria for the NTDC network be recognised and respected at the highest technical and political level. Suitably qualified staff be posted at NPCC.
Well-documented standard operating procedures for normal operations and to handle emergencies after the collapse should be prepared and provided to all NPCC staff.
There should be a continued system of providing practical training and higher education to NPCC staff and the staff should be given attractive salaries to minimise the exodus of staff there, it concluded.
