The major constituents of a city gas distribution (CGD) network are compressed natural gas (CNG) stations, city gas stations, a pipeline network, regulating stations and metering stations.
In the past, CGD entities deployed information technology (IT) and operational technology (OT) solutions as two separate domains. However, the convergence of IT and OT has helped CGD players reduce costs and risks as well as enhance performance. IT refers to the physical infrastructure which is used to transfer gas consumption data from the field (CNG stations, residential complexes, commercial buildings, etc.) to the gas operator. It includes computers (servers and workstations), networking devices (GSM modems), storage and other devices, remote terminal units (RTUs) and field instruments. OT refers to different tools or solutions deployed for data interpretation (graphics, reports, key point applications). It incorporates several types of control systems and associated solutions such as supervisory control and data acquisition (SCADA), distributed control systems and other smaller control system configurations.
RTU
An RTU is an electronic device installed at a remote location that collects data, codes it into a format and transmits this data to a central station. Some of the exceptions-based protocols that RTU supports are IEC 870 101/104, DNP3, Modbus TCP/IP, OPC, etc. In particular, IEC 104 and DNP3 have been specifically designed to cater to the issues of frequent communication failures, low bandwidth and poor signal strength. The advantages of deploying RTUs are compatibility with wide area network communications, buffer storage and data retrieval facility to avoid loss of data due to communication failures, etc.
SCADA
One of the most important OT solutions for CGD networks is SCADA. The system can be customised to have both simple and complex configurations. In a basic SCADA system, information from sensors or manual inputs is sent to the programmable logic controllers or RTUs, which then transmit the information to computers. The SCADA system analyses and displays the data on a central computer. The data is used by the CGD operator to improve its operational efficiency. The design of the SCADA software should be such that it is able to handle any kind of communication being used in CGD networks. The cybersecurity components of SCADA are security global settings, IP white listing for database connections, a password policy, application users and user groups, security logs and digital signed applications.
Another important feature of SCADA is the ability to merge with Google Maps. In this, various gas stations are marked with different colours and all the adjacent geographies are also marked to provide a detailed picture of the geographical area.
A SCADA system can be deployed at CNG stations, city gas stations and industrial units. It can be used for online reconciliation of gas billed and actual consumption, monitoring losses at CNG stations, the centralised monitoring of trends in load and performance parameters, monitoring the upstream pressure for each CNG compressor, continuous monitoring of gas flow parameters, and the identification of any major pockets of pressure loss across the grid, among others.
Some of the technologies that SCADA supports are MS Windows Server 2016, MS Windows 10 LTSB, MS Visual Studio 2015, MS SQL-Server 2014 (64-bit only) and MS Office 2016 (32-bit and 64-bit). Among the various web services offered by SCADA, the O-Data protocol version 4.0 is likely to gain importance in the years to come as it allows the creation and consumption of queryable web services in a simple and standard way. The benefits offered by O-Data are authentication, real-time accessing, maintenance of historical data, etc.
The SCADA system offers several advantages. Chief among these are real-time monitoring of gas consumption, reduction in data errors, automation of processes, etc.
Conclusion
SCADA systems built with the latest RTU technologies can deliver the optimal reliability, efficiency and cost-effectiveness that today’s complex infrastructure and industrial processes require. Despite the importance being given to the installation of SCADA systems, there are various operational challenges that need to be addressed. Inconsistent communication and signal strength, integration of older CNG stations with SCADA, and obsolete metering infrastructure are some of the operational challenges that require urgent attention by all stakeholders.
Based on a presentation by N. Srinivas, Engineering Head, Industrial Automation (Oil, Gas and Chemicals), ABB Limited, at a recent India Infrastructure conference
