Digital Advantage

Powergrid’s technology roadmap for transmission system strengthening

A stable grid is vital for the overall health of the power sector in the country. Hence, in the transmission segment, ensuring grid stability is the key driver for the adoption of  information technology (IT) and operational technology (OT) solutions. Technology solutions can help in maintaining optimal energy flow and easing transmission network congestion, which are the key challenges facing the transmission segment in the country. Further, with large-scale integration of renewable energy sources, monitoring energy flow into the grid has become essential for maintaining stability. The use of IT and OT solutions in transmission provides a technological edge and helps in the automation of grid operations.

IT and OT solutions can help utilities in optimising the performance of transmission systems and creating new models for efficiency. Technologies such as asset management, data analytics, IoT, smart sensors and process bus architecture also aid in streamlining grid operations. In addition, IT and OT solutions can help in meeting regulatory challenges and associated environmental regulations. The deployment of such technologies is not an easy task. In order to transition from traditional technologies to advanced IT and OT technologies, transcos need to prepare a technology roadmap with clearly defined short-term and long-term targets. Power Grid Corporation of India Limited (Powergrid) is the pioneer in implementing technology solutions in the transmission space. As of March 31, 2019, Powergrid owned and operated 1,235 lines and 245 extra high voltage substations, including 15 high voltage direct current substations up to ± 800 kV level, 726 transformers, 11  STATCOMs, 5 static  var compensators (SVCs) as well as series reactors and thyristor controlled series compensators/fixed series compensators at various places. The reliable operation of such a vast transmission network requires maintenance of assets in the best possible condition and the transco achieves this by adopting the best IT and OT solutions for maintaining and monitoring the transmission system.

As part of its focus on technology, Powergrid has formulated a digitalisation roadmap for the period 2012 to 2023 which outlines various initiatives taken up or planned by the company. As per the roadmap, the utility began the integration of online sensors at the equipment level in 2012 and commissioned the National Transmission Asset Monitoring Centre (NTAMC) at Manesar in Haryana in 2014. The NTAMC has been established for remote operation of the system and monitoring of various parameters at the national level and 10 regional transmission asset management centres (RTAMCs) at the regional level. During 2018-19, 38 substations have been integrated with the NTAMC for remote operations. With this, a total of 210 substations have now been integrated under the NTAMC for remote operation from control centres. These are manned by experts on a 24×7 basis to provide expert handling of the systems. Powergrid took up geographic information system (GIS) mapping and tablet-based patrolling of lines as well partial substation digitalisation during 2017-18, followed by the implementation of the automated fault analysis system (AFAS) during 2018-19. Smart Utilities presents an overview of Powergrid’s digital journey so far and future targets…

Short-term targets

The short-term targets in Powergrid’s digitalisation roadmap include the implementation of  GIS mapping, patrolling, process bus – partial automation, and AFAS.

GIS mapping helps in disaster preparedness (for example, during natural calamities such as the recent Vayu and Fani cyclones), vulnerability analysis, corridor mapping of critical lines, post-tripping analysis and the study of changes in river course. Powergrid started implementing GIS mapping in 2017, and updated the pan-Indian data by December 2018, including data from the southern region-2 (comprising Karnataka, Kerala and Tamil Nadu) and the north-eastern region. It has also undertaken the integration of the BHUVAN server in 2019 and expects to complete the implementation of GIS mapping by end 2019.

Patrolling is done to monitor towers in order to check faults and ensure proper maintenance. By March 2019, Powergrid, through its Patrosoft software, had started patrolling close to 0.28 million towers. The software dashboard displayed scheduled patrolling and patrolled line towers as well as highlighted critical towers and emergency actions needed, if any.

Powergrid is implementing process bus in substations which provides equipment-level automation, advanced diagnosis, reduced environmental footprint and enhanced safety. It achieved single bay digitalisation at the Bhiwadi substation by January 2015, followed by partial digitalisation at the Neemrana substation in October 2015. Powergrid set up the first digital substation in Chandigarh in August 2019 and undertook retrofitment of the Malerkotla substation in September 2019, thereby completing the digitalisation process. One of the key benefits of digital substations based on process bus is a reduction in the use of control cables through the deployment of fibre optic network.

Further, Powergrid is implementing AFAS, which helps in auto analysis of tripping based on reports generated at the equipment, bay, station and system levels. AFAS monitors cumulative fault current, the pole open discrepancy of circuit breakers (CBs), capacitor voltage transformer errors and current transformer saturation. AFAS identifies frequent demand response triggers in particular relay due to carrier fail, start alarm, auxiliary contact bouncing of CBs, etc. It updates the communication status of relays with remedial action system to identify any physical- or protocol- level disconnection.

Medium-term targets

The medium-term targets in Powergrid’s digitalisation roadmap include the implementation of solutions such as asset health indexing (AHI) and transmission line analytics. AHI deploys IoT and big data to move towards reliability-centred maintenance. It uses real-time values with online sensor data and enterprise resource planning (ERP) data to arrive at the asset health score.

Powergrid started developing AHI solutions in-house by integrating online sensors in 2013 followed by real-time data logging at the NTAMC in 2014. The integration of legacy data with ERP was completed in 2015 and AHI specifications were developed in 2018. In 2019, the company began the development of an initial AHI module for transformers, and plans to fully implement AHI by 2020. Under AHI, online equipment data can be combined with historical offline data to provide an informative and intuitive parameter called asset condition index.

Transmission line analytics through the use of data acquisition tools is also being implemented by Powergrid. The data acquired from various sources including aerial patrolling (such as high resolution tower images), drone-based tower top patrolling, ground patrolling and GIS mapping of lines will be integrated during 2019-20. Thereafter, data analysis models will be developed for implementing transmission line analytics by 2020-21.

Long-term targets

The long-term targets in Powergrid’s digitalisation roadmap are complete automation of substations using process bus architecture and the implementation of a robust cybersecurity framework.

The key benefits of complete digitalisation using process bus include minimised outage time, increased security, improved inter-changeability of equipment, increased reliability, optimised maintenance, and remote commissioning and testing. Powergrid aims to gain experience from operating digital substations during 2019-21, so that it can devise an action plan for the development of all new substations from 2021-22 onwards.

In the long run, a robust cybersecurity framework will be needed to combat transmission vulnerabilities. The transmission vulnerabilities include distributed denial-of-service and man-in-the-middle attacks on transmission grids, malicious data injection, and attacks on SCADA and remote terminal units. Powergrid has already taken cybersecurity measures such as the establishment of a dedicated fibre network, and a security event and information management system during 2017-18. The utility obtained the ISO 27001 certification, a specification for an information security management system, in 2018. It also established a cybersecurity lab at Manesar in 2019. In the years to come, Powergrid plans to start data link authentication, set up a security operation centre, and draft a cybersecurity framework for all substations by 2023. n

Based on a presentation by R.K. Tyagi, Chief General Manager, Power Grid Corporation of India, at a recent Smart Utilities conference

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