Power transmission company Karnataka Power Transmission Corporation Limited (KPTCL), set up in 1999, is mainly responsible for the transmission of power in the renewables-rich state of Karnataka. Over the past few years, the transco has managed to bring its transmission losses to as low as 3.1 per cent, while maintaining a stable system availability at 99.5 per cent. Due to a high share of renewables in the grid, the transco has been investing in a series of initiatives to implement innovative technologies in its network. It is one of the few utilities to have its entire network covered under a state-of-the-art supervisory control and data acquisition (SCADA) system, helping the transco achieve real-time monitoring of all its interface points. The state has also set up a renewable energy management centre (REMC) for monitoring renewable energy generation. Further, towards its plan of moving towards smart grids, KPTCL plans to install phasor measurement units (PMUs) in its network as well. KPTCL is also involved in the implementation of automatic generation control (AGC) pilots in the state, which will help support the system operation during high ramping of renewable energy sources.
Current infrastructure and operational performance
KPTCL’s infrastructure has grown at a steady pace over the past few years. As of March 2020, the line length stood at 38,033.5 ckt. km. The length of overhead lines is 37,652 ckt. km, while that of underground lines is 381.5 ckt. km. The length has increased by 2.25 per cent and 14.47 per cent, respectively, over the past one year. The compound annual growth rate (CAGR) of overhead transmission lines was 2.65 per cent and that of underground transmission lines was 7.35 per cent, over the four years from 2016-17 to 2019-20. The 220 kV underground transmission line length grew at the highest CAGR of 22.12 per cent.
Its 33/11 kV substation base increased from 1,116 in 2016-17 to 1,222 in 2019-20, while the number of transformers have grown from 2,557 to 2,659 over the same period. Transformer capacity has increased by 16.8 per cent from 56,496 MVA in 2016-17 to 65,996 MVA at present.
Of its substation base, six are at the 400 kV level, 108 are at 220 kV, 110 are at 432 kV and 676 are at 66 kV. The total number of substations has grown at a CAGR of 3.07 per cent over the past four years (from 2016-17 to 2019-20), with the highest growth or 400 kV ones at 14.47 per cent. The number of transformers stands at 2,659 (15 of which are 400 kV, 231 are 220 kV, 1,087 are 110 kV and the remaining 1,326 are 66 kV), recording a CAGR of 1.31 per cent over the same period. The highest growth rate has been observed for 400 kV transformers at a CAGR of 7.72 per cent. The transformer capacity has recorded a 5.32 per cent CAGR over the past four years. The company has shown a steady decline in transmission loss. From 2002-03 to 2019-20, transmission losses have decreased by 3.8 percentage points. System availability has remained steady (around 99.5 per cent) over the same period. As of March, 2020, the company has a transmission system availability of 99.5 per cent.
The company’s revenue for financial year 2018-19 stood at Rs 31,272.3 million and profit at Rs 2,142.5 million. Over the same period, the CAGR for income and profit has been 6.89 per cent and 16.88 per cent respectively. Going forward, the company has planned a capex of Rs 3,269.65 billion for financial year 2020-21 and Rs 3,287.78 billion for financial year 2021-22. The planned areas of investment include new transmission lines and substations as well as renovation and modernisation (R&M) and upgradation; IT, SCADA and software, etc.
To overcome right-of-way (RoW) issues, KPTCL has installed extra high voltage cables with 2,000 sq. mm for the 220 kV lines. This has been primarily done to overcome the RoW issue in the Bengaluru area. For 220 kV class substations, cables with 1,200 sq. mm were installed. In the case of 66 kV class of substations, the cables installed were 1,000 sq. mm. Another initiative for the purpose of increasing corridor capacity has been the installation of high temperature low sag (HTLS) conductors at the 66 kV level in Bengaluru. The company has also established monopoles (220 kV double circuit lines) in the city using the road median corridor in congested areas. In various locations, multicircuit multivoltage (MCMV) towers and narrow-based towers have also been installed. The transco is also implementing GIS substations in its network to overcome RoW. In Bengaluru, it has a 400 kV GIS station at Mylasandra and a 220 kV GIS station at Kumbalgod.
Currently, SCADA covers the entire KPTCL grid network, which is being used for real-time monitoring and control of 1,510 stations, which include all generating stations, independent power producers, and energy supply companies stations (ESCOMs). The system has 16 control centres, which include the main control centre, a disaster recovery centre, area load despatch centres for transmission zones and distribution control centres for ESCOMs. The communication mode used is VSAT communication through a satellite. It is a unique feature, wherein all the data from all substations (right up to 66 kV level), all generation sources (including renewable energy) and all polling stations are connected through VSAT communication.
Also, the REMC, which has been set up adjacent to the state load despatch centre (SLDC), will take inputs from forecast service providers, the SCADA system and provide week-ahead and day-ahead schedules at pooling points. The implementing agency for the project has been Power Grid Corporation of India Limited. Another initiative planned is the installation of PMUs. So far, it has installed PMUs in four stations. In Phase II, all 400 kV and 220 kV stations are envisaged to be covered. Another initiative where the transco is involved is the AGC pilots at the Varahi and Sharavathi hydropower plants of Karnataka Power Corporation Limited under the USAID’s GTG-RISE initiative. The existing AGC module in the energy management system (EMS) at the SLDC is planned to configure to generate AGC signals for participating hydro units. Globally, AGC is a tool widely used by system operators for a stable frequency operation and security of the grid.
Going forward, KPTCL also plans to implement 400 kV station/bay kiosks, and an outdoor GIS kiosk of 200 kV at Bengaluru, optical ground wire for all 220 kV and above transmission lines and a digital substation (which is a process bus technology for R&M) at the Subramanyapura station in Bengaluru. All these developments are currently at at the initial stage. The company is also considering changing the existing conductors with a high capacity, that is, high performance conductors. Recently, it has gone for ERP adoption for management. However, the company had been facing some RoW issues with farmers expecting more compensation compared to guidelines. These issues are being resolved, with the help of the district administration. These challenges notwithstanding, overall, KPTCL’s initiatives towards a future smart grid are expected to enable the company to shift to a more efficient, comprehensive and flexible energy system that provides better insight and control.