ISLAMABAD:
The nation’s energy watchdog has held the Nationwide Transmission Dispatch Firm (NTDC) chargeable for the partial blackout that occurred within the nation in October final yr.
Sindh, Balochistan and a few components of Punjab have been left with out energy on October 13, 2022 after a grid failure shut down numerous energy stations one after the other in a surprising vogue. The breakdown took out about 8,000 megawatts from the nationwide grid, and it took greater than 12 hours to revive.
It was Pakistan’s third large energy outage in as a few years, displaying extreme issues within the energy distribution system of the nation.
The Nationwide Electrical Energy Regulatory Authority (Nepra) took discover of the incident and shaped an inquiry committee to analyze the matter which on Thursday unveiled its report.
The report stated the receiving of a false DTT sign on the 500kV Gatti G/Station from the Ghazi Barotha finish initiated the tripping of the 500kV Gatti Ghazi Barotha Circuit-11.
“The blackout was brought on by the failure to finish the devoted transmission line for the evacuation of energy from the K2 and K3 energy vegetation.”
The facility regulator stated tripping of the 500kV K2/K3-NKI T/Line and the 500kV K2/K3-Jamshoro T/Line was because of mechanical failure of the {hardware}/conductor.
This was a results of improper interim preparations with non-standard/non-specific {hardware} materials and an absence of periodic upkeep of transmission strains as per commonplace working procedures (SOP).
The report stated the preliminary reason behind the tripping was overheating and subsequent harm of T-clamps and conductor on the non permanent diversion between location quantity 26A and 27 of the 500KV K2/K3-NKI circuit for the evacuation of energy from the K2/K3 vegetation.
Because the building of the devoted transmission line for the evacuation of energy from K2/K3 couldn’t be accomplished by the NTDC, an interim association was made, which continues to be in place indefinitely because the devoted transmission line stays incomplete.
This interim association includes numerous joints with various kinds of clamps, comparable to T-clamps and L-clamps, primarily based on availability on the time of execution.
Learn extra: Nation incurs Rs100b loss because of energy breakdown
The conductor of the transmission strains getting used for the interim association is roughly 26 years outdated and put in in a closely coastal polluted space, leading to deterioration.
Initially, a fault developed on the 500kV NKI-K2/K3 circuit because of overheating and breakage of T-clamps of the jumper, which resulted in tripping from each ends.
This triggered a shift within the load, roughly 2,700 MW of CPHCL and K2/K3, to the remaining two circuits between K2/K3 and Jamshoro, because the CPHGCL-Jamshoro circuit was already beneath scheduled outage since 08:48 hrs.
The extra load affected the 500kV K2/K3-Jamshoro circuit, which is an older circuit, the place a sub-conductor of the purple part heated up on the dead-end physique at location quantity 26A and consequently indifferent and fell to the bottom.
The tripping ought to have occurred instantaneously by the tele-protection scheme as a substitute of zone-2. The relay indications and fault recorder knowledge on the Jamshoro finish present that the tele-protection sign (permissive) was not acquired at Jamshoro from the K2/K3 finish.
“This must be checked and addressed. Relating to the failure of {hardware} inside three years of commissioning, it’s because of the improper interim association with non-standard, non-specified {hardware} materials and an absence of periodic upkeep of transmission strains as per SOP.
“The tripping of circuit breakers on the 500kV HUBCO-K2/K3 circuit at K2/K3 upon receipt of the DIT sign, which remoted CPHGCL, was because of a false sign, as verified by the telecom log throughout a go to to HUBCO, the place no sign was transmitted.
“This false telecom sign must be checked and addressed,” it stated.
The Fortunate Energy Plant tripped because of “Over Excitation Safety” brought on by over-frequency. Nonetheless, its energy system stabilizer (PSS) is but to be introduced into service to stabilize the system. Within the South area, the system couldn’t maintain because of inadequate era in comparison with the load demand.
Some load was shed routinely by under-frequency schemes.
Nonetheless, the area was subsequently restored by the Ok-Electrical energy vegetation and NTDC provide, and the NTDC-KE system synchronized at 17:25 hrs.
Though the system was restored inside an affordable time, the restoration of the Ok-Electrical system was barely delayed as about 60% of their restored community tripped by cross-trip schemes.
This might have been minimized if Ok-Electrical, which was nicely conscious of the scenario, had blocked the cross-trip scheme earlier than initiating the restoration course of.
In the course of the go to to the breakdown/interim association website, the Inquiry Committee noticed that even after rehabilitation, the situation continues to be dangerous, particularly that of the conductor, which has bulged at some factors. It must be addressed as quickly as potential to keep away from any unexpected occasions.
The standing of earlier inquiry report findings and suggestions relating to the entire energy collapse on January 09, 2021, and the NTDC Inquiry Report dated October 13, 2022, relating to the partial shutdown, are nonetheless beneath implementation.
Nepra burdened that the prevailing interim association ought to be instantly bolstered with commonplace {hardware}. The ageing issue of the conductor and the standard of fabric and correct workmanship throughout the execution of the interim association should be ensured.
“Periodic upkeep and monitoring actions, particularly for the interim association designed for K2/K3 circuits, should be ensured as per the SOP. The pending work on devoted transmission strains for the evacuation of energy from K2 and K3 vegetation ought to be accomplished with high precedence.
“A completely practical SCADA facility for the entire system associated to NTDC, GENCOS, lPPs, and DISCOs is important for the system operator to make sure on-line monitoring of system parameters, safety, stability, and evaluation of occasions by GPS-synchronized time occasion recorders.
“Set up of recent know-how gadgets comparable to Huge Space Administration (WAM)—together with Phasor Administration Models (PMU)—to detect oscillation instability, which could be mitigated by the Remedial Motion Scheme (RAS).
“Availability of required professionals and workers as per permitted yardstick, together with required instruments and tools, together with thermo-vision cameras, particularly within the southern area, should be organized urgently to make sure well timed upkeep of the prevailing community for system stability, reliability, and safety.”
Nepra emphasised that each one permitted transmission line initiatives should be accomplished on schedule. Work on delayed initiatives ought to be accelerated on a precedence foundation to make sure secure evacuation of energy era.
The deficiencies within the Community and Telecommunications Operations Middle (NTOC) should be addressed to make sure correct communication of inter-grid indicators and keep away from the transmission of false indicators.
“Protocols and SOPs ought to be developed to streamline operational coordination between Ok-Electrical and Nationwide Energy Building Company (NPCC).”
It stated the quantum of load to be shed by under-frequency and Price of Change of Frequency (ROCOF) schemes within the South area must be elevated to make sure the survival of the area throughout under-frequency conditions.
“The apply of switching off transmission strains to manage overvoltage on the system, which isn’t prudent or beneficial, ought to be studied to put in extra Shunt Reactors at applicable areas, comparable to Grid Station Busbar,” it added.