Ageing infrastructure and the increasing thrust on renewables has necessitated amendments to the current grid. In response to this, several utilities across the country have been employing the latest technologies to enhance grid stability and modernise their networks. A case in point is Rajasthan Rajya Vidyut Prasaran Nigam (RVPN). A number of smart grid initiatives targeted at enhancing the digital ecosystem are being implemented by the transco.
The state’s transmission network spans 24,995 ckt. km. This includes 425 ckt. km of 765 kV transmission lines, 4,171 ckt. km of 400 kV lines, 14,107 ckt. km of 220 kV lines and 16,292 ckt. km of 132 kV lines. The total transformer capacity in the state is close to 69,666 MVA, of which the majority is at the 132 kV level (27,891 MVA), followed by the 220 kV network (26,965 MVA). At the 765 kV level, the state has two 765 kV substations, which have a combined capacity of 6,000 MVA.
Drivers for modernisation
One of the key drivers for the modernisation of the state’s grid is its ambitious renewable energy targets. At present, Rajasthan has a wind power capacity of 4,007 MW and a solar capacity of 1,295 MW. By 2021-22, the state plans to add 23,000 MW of capacity. For the evacuation of power from the upcoming capacity as well as to manage the voltage variation with greater injection of renewables, a stronger grid is mandatory.
Further, grid modernisation is expected to help the utility manage the relatively complex power structure envisaged in the future, where production levels will have to be altered in accordance with demand. Overall, the utility is aiming at a wide range of benefits through grid modernisation, encompassing outage management, intelligent metering, load management, asset mapping, etc. A modernised grid is expected to play a key role in enhancing power system analysis, ensuring power quality and enabling stability control.
RVPN has drafted a comprehensive roadmap for the implementation of several smart initiatives.One of the key steps being taken by the utility is the implementation of a Smart Transmission Network and Asset Management System (STNAMS). STNAMS is expected to enhance the visualisation and situational awareness of its transmission grid. Apart from this, such a system would offer other benefits such as enabling remote operations of substations, wide area monitoring and protection, data accuracy and developing a decision support system.
STNAMS is being implemented under four distinct packages covering different aspects of the infrastructure. Under the supervisory control and data acquisition/energy management system package, remote terminal units (RTUs) would be installed to monitor and control nearly 429 substations of the transco. Further, data concentrator units, remote access systems and fault analysis systems would be installed at all locations. Along with this, 25 phasor measurement units, one power distribution centre and the related visualisation software and storage systems would be installed.
The information and communication technology package would include the setting up of a data centre (with a network management system, unified computing systems, a virtual management system and cybersecurity), routers and switches for connecting to all substations/offices and control centres along with the auxiliary power supply system. The tender for the implementation of this phase was awarded in June 2017 and the project is currently under execution.
The reactive power compensation package consists of equipment such as one switchable 400 kV bus reactor, 13 switchable bus reactors at the 220 kV level and two ±300 MVAR static synchronous compensators (STATCOM) in Rajasthan’s grid.
The fourth package is the optical ground wire (OPGW) package, under which OPGW has been proposed to be laid, spanning 13,770.8 km at 538 locations. This package was awarded in September 2017.
Another project in the pipeline is the Smart Transmission Operation Management System (STOMS). This will be utilised for availability-based tariff and other load despatch operations, energy accounting and billing, optimal scheduling and despatch operations, deviation settlement and monitoring grid compliance, among other things. STOMS is expected to improve operational efficiency and ensure timely service to all beneficiaries. It is expected to serve as a tool to perform various business and operational functions.
A major initiative undertaken by RVPN has been the implementation of the SAP enterprise resource planning (ERP) solution to achieve end-to-end integration of various business processes. Currently, SAP-ERP has been implemented at the corporate, zonal, circle, division and sub-division levels, including all grid substation (GSS) locations. This has enabled effective monitoring and control of GSS parameters such as voltage, tripping and power factor. It has also resulted in an improvement in operational working efficiencies of extra high voltage (EHV) GSSs by increasing system availability and minimising breakdowns and timely maintenance.
The system ensures close monitoring and control of maintenance activities at all substations through breakdown analysis and defective equipment’s analysis, thereby translating into improved system availability. Additionally, various dashboards have been developed for monitoring the operational parameters of substations at the circle level as well as in its entirety. In order to monitor the health of transformer oil, oil testing parameters have also been made available. Moreover, the system facilitates proper monitoring of GSS peak load and transformer peak load on a routine basis.
Apart from several initiatives that are currently under way, the utility has been focusing on various new measures such as the setting up of compact substations. The utility is also deploying geographic information system technology to enhance visual assessment and mapping of assets. Moreover, renovation and modernisation of systems is being undertaken. Obsolete protection relays will be retrofitted with IEC-61850-compliant numerical relays. For 220 kV and above voltage levels, numerical busbar protection relays would be installed. In addition to this, EHV cables would be used for 220 kV and above levels. Also, the use of tubular monopole transmission towers is being considered for up to the 220 kV level. In addition to this, high temperature low sag conductors would be installed for doubling the line capacity.
Despite having developed an organised blueprint for making the grid smarter, the utility continues to face challenges. The foremost challenge remains in the skilling domain. The manpower needs to be trained to operate these increasingly complex systems else the entire exercise proves futile. Another major impediment is identifying the appropriate technology and its effective use. To ensure that the right technology is chosen, a detailed study must be conducted, backed by a cost-benefit analysis, to narrow down the relevant options. Further, steps need to be taken to manage the interoperability/interfacing of various layers for data exchange among various parties. In addition to this, the investment required for retrofitting/renovating old systems is a cause for concern. Lastly, with greater integration of renewable energy into the grid, variability continues to be a major hindrance in achieving grid stability.
RVPN’s continued efforts aimed at transforming the grid reflect its commitment to ensure provision of quality power to consumers. The utility has been making concerted efforts to empower the system technologically and thereby improve efficiency. These initiatives are likely to bring about the much-needed turnaround in the conventional grid.
Based on a presentation by Manish Athaiya, Executive Engineer, and Vishwas Kale, Executive Engineer, RVPN