HVDC (high voltage direct current) technology is an important component of India’s power transmission grid, offering distinct advantages over conventional AC technology, in specific conditions. Hitachi Energy India commissioned India’s pioneering HVDC line, way back in 1989, and has since then been associated with marquee HVDC lines in the subcontinent. In this interaction, we have Saji S, Senior Vice President — HVDC, Hitachi Energy India Ltd, delving into the technicalities of HVDC power transmission. Saji explains that with the rapidly-changing dynamics the in power landscape, HVDC technology can be a cost-effective and low-carbon solution. An interview by Venugopal Pillai.
Let us start by understanding why HVDC technology can be an effective solution for power transmission, particularly in the Indian context.
Lower losses are equivalent to less carbon emissions, so HVDC transmission of electricity is an important piece of the puzzle in meeting global emission reduction targets. Due to its geographical expanse and fast expanding per capita demand, India has massive potential for grid expansion consisting of HVDC transmission and renewable energy integration. HVDC is a key enabler for a carbon-neutral energy system. It is highly efficient for transmitting large quantum of electricity over long distances, penetrating large city centers to meet demand with least footprint, integration of renewables and interconnecting grids.
“HVDC transmission systems hold a unique capability of stabilizing the grid during dynamic conditions.”
Compared to conventional AC transmission (even considering EHV and UHV levels), what are the technological challenges or complexities associated with HVDC transmission?
The transmission networks and power generation systems keep expanding. HVDC transmission systems hold a unique capability of stabilizing the grid during dynamic conditions. This also triggers the need of designing the transmission system that are future-ready and get updated against changing grid dynamics.
HVDC system offers significant flexibility to grid operator to control the power flow and direction in the complex grid environment. The inherent complexity also demands developing expertise and sustaining over long life span of HVDC stations. Technology changes and new challenges like cyber security puts constant monitoring requirements in upgrading systems.
“Hitachi Energy has an impressive record of HVDC accomplishments in India.”
Please give us a brief overview of Hitachi Energy India’s projects in the country.
Raigarh-Pugalur (RP800) is Hitachi Energy’s sixth HVDC project in India and the second UHVDC (Ultra High Voltage Direct Current) installation, following the multi-terminal North-East Agra link (NEA800). Over half of the HVDC links in India are by Hitachi Energy and it is a run rate we would like to build on.
In 2014, we developed complete system solution for 1,100kV ultrahigh voltage direct current (UHVDC) technology and enhancing power transfer capacity to over 10,000 mw and extending distance to over 3,000 km.
We were also awarded the project to set up HVDC in-feed link in Mumbai to supply up to 1,000 MW of electricity, increasing power from outside of the city by almost 50 per cent. This is a city center in-feed link built in combination of underground cables and overhead lines.
“HVDC Classic is the economical and efficient way to transmit bulk power over long distances.”
What are Hitachi Energy’s key offerings in the HVDC solutions space?
HVDC Light®, based on VSC (Voltage Sourced Converter) technology is designed to transmit power underground and underwater, within constrained RoW in city limits and station footprint requirements. It offers numerous environmental benefits, including “invisible” power lines, neutral electromagnetic fields, oil-free cables and compact converter stations.
HVDC Classic is the economical and efficient way to transmit bulk power over long distances for stronger network and around three times more power in a right-of-way than overhead HVAC. HVDC Light on the other hand is compact, quick to install and adaptive in complex grid environment, very useful in efficiently integrating remote renewables, while enhancing the grid stability and overall efficiency.
“The Mumbai HVDC link will help to meet increasing power demand which is expected to be more than 5,000 MW by 2024-25,”
The Mumbai HVDC link that Adani Electricity Mumbai Ltd (AEML) has mandated on Hitachi Energy India is truly a big achievement, as we perceive. Please take us through the project.
We are working with Adani Electricity Mumbai Infra Ltd (AEMIL) for setting up HVDC link for transmission of 1,000 MW reliable and secured power from Kudus to Mumbai city center. This HVDC link will help to meet increasing power demand which is expected to be more than 5,000 MW by 2024-25, enhancing overall transmission capacity, grid stability by power flow control, reactive power support and black start feature to restore the grid in the event of black out.
By utilizing Hitachi Energy’s compact HVDC system and 50 km of underground cables rather than overhead lines, almost 2.3 sqkm of land will be saved – the equivalent of more than 320 soccer pitches!
“HVDC Light technology has features like independent active and reactive power control, black start and grid stability support functions.”
Do you foresee the Mumbai HVDC link setting a precedent for similar transmission systems for other urban centers?
Energy demand in major cities is increasing rapidly due to increasing population, per capita power consumption, industry and data centers power consumption, and increasing requirements for metro and e-mobility. Also, major cities are targeting to reduce carbon footprint by integrating more and more renewable energy, in their quest to make cities environmentally sustainable.
Mumbai city in-feed is the right example, utilizing compact HVDC Light technology with cable transmission, able to provide solution to transmit 1,000 MW power into city center by utilizing less RoW.
Other important features of HVDC Light technology like independent active and reactive power control, black start and grid stability support functions will enable grid operators to integrate efficiently more and more green power, and reduce CO2 emissions.
Hitachi Energy is continuously working on solutions for such applications adapting innovative and compact HVDC Light technology solutions for mainly integrating more and more green power in to city centers by reducing foot print with lower energy loss, enabling the meeting of carbon emission targets.
“HVDC can quickly compensate for fluctuations in power levels, making it the ideal technology for stabilizing irregular power flows, such as those generated by wind farms.”
Do you see HVDC technology getting a boost in India as the currently fledgling offshore wind industry matures with time?
HVDC Light technology is already being used in Europe, US and other part of the world for evacuation and integration of offshore wind with the main grid, interconnecting the complimentary renewable resources for balancing demand-supply gap.
The main attraction of going offshore is the enormous wind resource available. Average wind speeds can be 20 per cent higher, and the resulting energy yield up to 70 per cent greater than on land. The lack of obstacles such as hills, and the smooth surface of the sea, also makes the wind more reliable.
Specific to offshore, India has a huge advantage of its vast coastline with large potential for offshore wind with yield expected to be much better compared to onshore. The trend is likely to continue during the assessment period, owing to significant investment in renewable energy sources, particularly in Asia.
