Aatmnirbhar Bharat in Global Positioning System
Published on : Saturday 05-09-2020
Praveen Kumar Agarwal elaborates upon the need to deploy NavIC receivers for all navigational and timing signals requirements in India.
The Global Positioning System (GPS) is a global navigation satellite system (GNSS) that provides geolocation and time information to a receiver anywhere on or near Earth. It is owned by United States government and operated by United States Space force. The GPS provides critical positioning capabilities to military, civil, and commercial users around the world. The United States government created the system, maintains it, and makes it freely accessible to anyone.
Several other countries have also developed or are setting up their own global or regional satellite navigation systems. The Russian have Global Navigation Satellite System (GLONASS), China's BeiDou Navigational Satellite System began global services in 2018, and now finished its full deployment. There is also the European Union Galileo positioning system. Japan's Quasi-Zenith Satellite System (QZSS) is a GPS satellite-based augmentation system to enhance GPS's accuracy.
In India, GPS system is used by wide variety of users and equipment ranging from consumers to the industries and from personal uses to commercial uses. Most common use of GPS is in smartphone wherein GPS is mostly used for location information and for providing precise time. GPS is also used for health and fitness though smartwatch, wearable fitness tracker for calculating the distance run and maintaining the time records. In commercial use, GPS is used for fleet tracking from the central control room, by taxi services to find the route and to calculate the travel charges.
The aviation industry in India and other countries are using GPS for flight navigation and positioning which helps them to find the assigned route, the moment of entry in the foreign country’s airs-pace and seeking permission, landing and taking off, etc. Similarly, ships use GPS for locating their exact positions and to remain in touch with the world – in the absence of GPS they will find themselves isolated from the world and lost in the vastness of the sea.
Now, the power sector is getting dependent on precise timing signals and time synchronising their controller sensors spread all over the geographical area of the electric grid. Until now, synchronising time of different sensors were not important. Time was used only locally by the sensor for time stamping the sequence of events for post event analysis only. Data
acquired in conventional power system SCADA from different geographically spread locations was not so important is sub-seconds domain on the pretext that there is not much significant change in analog parameters of the grid like voltage, frequency, line loadings within sub-seconds duration.
With the commoditisation of electricity and need of loading the grid to its brim is compelling grid engineers to acquire data in sub-second range also. To have true time synchronised data at the central control room, sources of data must be synchronised with a standard time source. GPS is being used for providing timing information to these sources. Furthermore, the increasing need to control the grid from the central control room with use of AI/ ML technique is instigating power engineers to use GPS to synchronise each of its sensors and data acquisition device deployed.
Phasor Measurement Unit (PMU) is a sensor device which acquires sub-seconds data by sampling input power system signals at high sample rate. For this, PMUs require precise timing signals reference. Hence, each PMU is equipped with a GPS receiver for precise timing signal. The network of PMUs is known as Wide Are Measurement System (WAMS). In WAMS, a Phasor Data Concentrator (PDC) at central control room receive and merges the time stamped data from hundreds of time synchronised PMUs.
PDC send the merged data to other power system applications for taking required control or protection action as per system conditions. The electricity grid powers thousands of interconnected rotating machines, which remain in synchronism to each other bind to their rotating speed. The central grid control room needs precise time synchronised data to maintain the synchronism of these machines. Any mismatch in timing may lead to wrong control or wrong protection action leading to failure of synchronism and thus failure of the power grid.
In the view of above, availability, accuracy and security of GPS signals are highly important to any nation and also to India. Since GPS is a voluntary service, USA does not have any obligation to continue and maintain the GPS service. Further, signals transmitted by GPS are open and unsecure, hence are vulnerable to spoofing attack. In such a scenario, a little tweaking of source time signal of GPS may create large-scale disturbance in the Indian power system. There are many published papers on the vulnerabilities of GPS to spoof and risk of malicious tripping in the power system.
The United States government can also selectively deny access to the system, as happened to the Indian military in 1999 during the Kargil War. As per newspaper reports, “When Pakistani troops took positions in Kargil in 1999, one of the first things Indian military sought was GPS data for the region. The space-based navigation system maintained by the US government would have provided vital information, but the US denied it to India.”
Hence, to be Aatmnirbhar (self-reliant), India needs its own geolocation and navigational satellite system (GNSS). Fortunately, India has developed and deployed an indigenous GNSS which is more secure and more accurate than the GPS. This system is called Indian Regional Navigation Satellite System (IRNSS), with an operational name of NavIC (acronym for Navigation with Indian Constellation). NavIC is an autonomous regional signal satellite navigation system that provides accurate real-time positioning and timing services.
NavIC covers India and a region extending 1,500 km around it, with plans for further extension. NavIC is developed, controlled and maintained by Indian Space Research Organization (ISRO) through its Indian Regional Navigation Satellite System (IRNSS). The signal receiver chips developed by ISRO have several variants. They are providing a dedicated time signal for strategic applications like Defence services which are encrypted and more secure. As per ISRO, NavIC receivers with dual frequency bands i.e. L-1 & L-5 are robust and likelihood of spoofing also is extremely low as compared to GPS receivers.
NavIC system has the following distinct advantages over GPS: i. NavIC is an indigenous, reliable solution for the critical sector like Power Sector; ii. It provides better timing accuracy as compared to GPS, particularly in the event of high ionospheric activities; iii. Dual frequency NavIC is highly robust against spoofing as compared to the standard GPS based time receiver system, which is single frequency based; and iv. Can be implemented in Indian Power Sector is phased manner without affecting the critical power system operations.
NavIC provides two levels of service, the ‘Standard Positioning Service’, which will be open for civilian use, and a ‘Restricted Service’ (an encrypted one) for certain category of users (including the military).
This writer, during his tenure in Power System Operation Corporation Ltd, under the Ministry of Power’s program ‘Use of Space Technology in Power Sector’ initiated the use of NavIC receivers in Phasor Measurement Units in collaboration with ISRO. ISRO provided NavIC receivers, which were deployed on a pilot basis at some locations in the live grid in parallel to GPS receivers. The data received from both the receivers were analysed and compared and found accurate. PMUs vendors also welcomed the initiative and expressed their willingness to integrate NavIC receives in their PMUs.
The NavIC receivers need to be brought to the consumer level by mass manufacturing and bringing down its cost to compete with GPS receivers. There is need of mandate from the Government of India to deploy NavIC receivers for all navigational and timing signals requirements in India. To start with, receivers capable to receive signals from both NavIC as well as GPS may be mandated initially, which in later stages may be shifted to only NavIC based systems. As per latest information, Government of India is making efforts to mandate the use of NavIC receivers in all time and positioning signals requirements of India under its Make in India and Use of Space Technology programs.
References
1. Global Positioning System – Wikipedia – https://en.wikipedia.org/wiki/ Global_Positioning_System, retrieved 11-Aug-2020.
2. Indian Regional Navigation Satellite System - Wikipedia https:// en.wikipedia.org/wiki/Indian_Regional_Navigation_Satellite_System, retrieved 11-Aug-2020.
3. NavIC: Two decades after US spurned India in Kargil, Country replies with desi GPS, https://economictimes.indiatimes.com/news/politics-and-nation/navic-two-decadesafter-us- spurned-india-in-kargil-country-replies-with-desi-gps/articleshow/64643986.cms?from=mdr, retrieved 13-Aug-2020.
4. Credit to Dr Nilesh Desai, SAC, ISRO, Ahmedabad for his wholehearted support for application of NavIC in Power Sector.
Praveen Kumar Agarwal Former Director & CISO, POSOCO Ltd has 39 years of experience in diverse areas of power sector, of which 24 years in electricity market design and operations, systems automation, WAMS & SCADA system integration and cyber security with active involvement in project execution and management of Supervisory Control and Data Acquisition (SCADA) system, and Integrated National Control Centre’s SCADA with regional control centres and with control centres of countries like Bhutan and Bangladesh. Agarwal pioneered synchrophasors technology (WAMS) in Indian power system in the year 2009. Among other achievements Agarwal played a key role in designing the Unified Real Time Dynamic State Measurement Scheme and setting up of Renewable Energy Management Centres in India. He has written and published over 50 technical papers and articles, and has contributed chapters in power system books published by international publishers. He has also delivered talks in many International and National conferences, chaired panel sessions, etc.
