Over the years, there has been an increase in the size and complexity of city gas distribution (CGD) systems, This has given rise to safety and security concerns, calling for more advanced centralised monitoring of pipelines and CGD networks. At present, the majority of the gas transportation and distribution infrastructure in India, including trunk and regional pipelines, steel pipelines, spur lines, city gate stations, compressed natural gas stations, distribution pressure regulating stations and gas meters, has separate supervisory control and data acquisition (SCADA) and gas management systems (GMSs) installed at various locations. These systems are operated and maintained by multiple operators and companies, which makes monitoring more complicated and cumbersome.
A central gas management system (CGMS) accomplishes the task of monitoring and controlling natural gas trading, transportation and transmission, pipeline parameters and delivery conditions at all major customer terminals by supplying data to a centralised system. It is a reliable, safe and secure system that comprises national GMS (NGMS) servers, which facilitate network management functions such as fault displays, configuration management, performance management and security management.
Implementation process
A CGMS can use both online and offline models. It can be used offline as a business management tool, and online by connecting it to the SCADA system of various operators. It can either be operated and maintained by pipeline transmission companies or by an association of operators/players. In both cases, stringent rules and regulations pertaining to data sharing have to be framed for the safety of operator data.
Global best practices
Some CGD operators in the UK, France and Italy have successfully installed CGMS technology and are using it extensively for their gas operations. The system provides accurate and real-time information, enabling gas distribution companies to monitor and control product movement accurately. It also allows for safe operations of a pipeline system.
National Grid plc, UK: National Grid plc manages the UK’s gas distribution network. The operator has developed a control centre and an online SCADA system supported by satellite communication for real-time data monitoring.
Gaz de France (GDF), France: GDF has developed a web-based interface for managing daily nominations/renominations against weekly forecasts, operational optimisation, predictive model and leak detection. It has also deployed a master control system with an additional emergency control room, GMS and a complete real-time management system.
Snam Rete Gas, Italy: Snam Rete Gas has installed CGMS technology for monitoring gas volumes and quality at entry and exit points. The CGMS controls gas pipelines, 10 compressors, seven entry points and seven silos. Besides, a dedicated SCADA system has been installed in the control room for data collection on a real-time basis. The data can be telemetered through respective remote terminal units to the SCADA control centre via satellite link.
Key issues in the Indian scenario
The Indian CGD industry has limited experience and capability for execution, operations and maintenance of the CGMS. Further, there are issues pertaining to compatibility and connectivity because of different SCADA and GMS systems at different locations. In some pipeline networks, there is no SCADA, making them non-compatible. The unavailability of a highly reliable bandwidth link often poses a challenge in providing online connectivity to all CGMSs and NGMSs. Sharing of sensitive data is another major concern.
Resolving issues
In order to develop a centralised CGMS, a dedicated gas management system has to be built for each pipeline. At the company level, there is a need for developing a central control system (CCS) that can be integrated with the NGMS. The CGMS will provide a comprehensive picture of the overall gas demand and supply management in the country. The NGMS should be managed by pipeline operators by creating a control room with stand-alone terminals at the Petroleum and Natural Gas Regulatory Board office for resolving disputes. Further, national gas management centres (NGMCs) and regional gas management centres (RGMCs) should be installed to monitor and control the quantity and quality, and operational and safety aspects of pipelines as well as the day-to-day operations on a real-time basis.
Conclusion
CGMSs are essential for centralised monitoring of the rapidly growing gas transportation and distribution infrastructure across the country. These should be supported by well-established NGMSs, NGMCs and RGMCs at the national level, and SCADA and gas monitoring systems at the city level. Going forward, with efforts channelised towards the effective monitoring of all gas transportation and distribution networks, CGMSs are expected to enhance the safety and efficiency of CGD networks.