The increasing influx of renewables, greater variability in load and varied sources of generation have necessitated greater flexibility and automation in grid operations and stepping up the smart grid efforts for dynamic monitoring of grid parameters. A key initiative to make the transmission grid smarter has been the Unified Real Time Dynamic State Measurement (URTDSM) project, which is being implemented by Power Grid Corporation of India Limited (Powergrid). A look at the URTDSM project and other initiatives…
The URTDSM project is one of the largest projects for monitoring and controlling power supply across the country. It aims to facilitate dynamic real-time measurements and visualisation in order to enhance the security of the grid and equip it to take corrective measures whenever required. The project employs wide area measurement system (WAMS) technology for collating concentrated data on an array of parameters, including load angles, oscillations and voltage. WAMS consists of components such as phasor measurement units (PMUs), phasor data concentrators (PDCs), visualisation aids, application and analysis modules, data archiving and storage.
Under the project, Powergrid is installing approximately 1,700 PMUs at all high voltage direct current (HVDC) and 400 kV and above voltage level substations. In addition, analytical tools to analyse the PMU data are being developed in association with IIT Bombay. The WAMS infrastructure has three major elements: PMU, PDC units and wideband communication. PMU measures the electrical waves on an electricity grid using a common time source for synchronisation, which, in turn, enables synchronised real-time measurements of parameters such as the phase angle and amplitude. The PMU network also facilitates the monitoring of grid events such as power flow, voltage and backing down. The output from the PMUs is transmitted through a local area network switch and router to the PDC. The PDC collects data from multiple PMUs and aligns it by a time lag to create a synchronised data set. This data set is then transmitted to the state load despatch centres (SLDCs), which further send it to the super PDC at the regional load despatch centres (RLDCs). The data finally reaches the PDC installed at the National Load Despatch Centre (NLDC) and is backed up. It is then analysed using software, which consists of applications such as vulnerability test on relay characteristics and dynamic/ linear state estimation and online circuit validation test.
Under Phase I of the project, around 1,200 PMUs will be installed along with computer hardware and software at 34 control centres. At present, Powergrid has installed more than 900 PMUs and has developed three of the six analytical tools planned under the project. Moreover, to meet the communication requirements, all substations of Powergrid, central generating stations and important stations in different states are being connected on an optic fibre network.
Besides the URTDSM project, there are several other initiatives being taken to make the grid smarter. To equip power system operators with real-time data on renewable energy generation, Powergrid is taking up the development of renewable energy management centres (REMCs) with advanced forecasting tools and smart despatching solutions. The government plans to set up 11 REMCs across the country, alongside the SLDCs and one REMC at the national level. These REMCs would work in tandem with their SLDC/RLDC to enable smooth grid operations. While scheduling can be done through centralised or decentralised ways through the REMCs, at present a decentralised forecasting/scheduling approach is being followed, wherein every wind farm and solar park of over 10 MW and 5 MW capacity respectively has to submit its schedule individually.
In addition, the installation of compensation devices such as static VAR compensators (SVCs) and static synchronous compensators (STATCOMs) has been proposed in the interstate transmission system grid by Powergrid, which would provide dynamic capabilities to the grid. Powergrid has commissioned SVCs at three locations in the northern region and another one is under implementation in the northern region. STATCOM has also been commissioned at one location in the southern region. Overall, Powergrid is planning to install STATCOMs at 13 locations across the northern, eastern, western and southern regions. As per the Central Electricity Authority, the total investment in compensation devices is estimated at over Rs 28 billion during the period 2017-2022. Moreover, efforts are being made to enable remote operation and monitoring of substations. Currently, 122 substations are being remotely operated from Powergrid’s National Transmission Asset Management Centre at Manesar, Haryana.
As the country moves towards achieving its renewable energy goals, key changes to the conventional grid will be required to maintain system stability. The ongoing efforts to deploy smart grid technologies are certainly steps in the right direction.