Reliable and Cost-efficient Pipeline Monitoring Now a Reality
Crude oil and natural gas reserves are generally located in remote areas such as deserts or offshore, which is why pipelines are used for transporting the oil and gas from the original drilling sites to refineries and other facilities for further processing and export. Leaks or sabotage along the pipeline can be costly and extremely dangerous.
Pipeline monitoring for water, wastewater, oil, and gas share a few features: The monitoring stations are spread over a vast area and they are substantially different from traditional factory automation monitoring systems, which are located in confined areas and normally employ industrial serial-based fieldbuses to connect all the PLCs and remote I/O devices.
For traditional systems, a serial-based data polling system is often sufficient , since the distance between the I/O points and numbers of I/O points is limited. On the other hand, due to the vast area it covers, pipeline monitoring requires a highly enhanced and reliable communications link to transmit the I/O events back to the remote central site.
The Drawbacks of Traditional DAQ Pipeline Systems
Proprietary protocol incompatibility
Until recently, DNP3.0 was the only alternative to using system-integrator-created proprietary protocols, which usually cause integration havoc due to system incompatibility. DNP3.0 is a standard industrial protocol that features active report and anti-avalanche. The downside is that DNP requires high performance systems to run, and DNP supported devices, such as PLCs, are expensive, and the cost of integration overhead is high. Taken together, these reasons make DNP economically unfeasible for many applications.
To reduce costs, many people choose the popular option of using PLCs that do not support DNP, and then require system integrators to create proprietary protocols that support active reporting. In the short run this may appear to be a great solution because it is both cheaper and easier, but in the long run, this strategy will cause serious and costly compatibility problems. The main reason is that proprietary protocols that are built specifically for a particular SCADA system usually cannot co-exist with subsequent new systems created by other system integrators.
Wireless instability
Wireless communications is not stable enough for traditional passive polling. A loss of communication can result in permanent data loss, which can prove to be disastrous. To work around this problem, many system designers will install a data logger in the field to prevent data loss. The data logger works together with the PLC and the cellular/wireless modem to perform data transmissions and logging. The maintenance of these three devices can be rather complicated and demanding.
DAQ system failures
Externally connected modems are another link that causes data acquisition (DAQ) system failures. These modems connect to PLCs through a serial connection, and if the serial port is not properly protected, it will be extremely vulnerable to electric surges. The unavailability of a wireless modem can also cause DAQ system failures. In practice, engineers will pre-program the PLC to reboot the modem once a day to ensure that communications are continuously active. However, doing so makes it difficult to achieve real-time DAQ.
Modern Pipeline Monitoring System Requirements
Due to their nature and the harsh conditions they must endure, pipeline monitoring systems require a reliable network to provide non-stop round-the-clock monitoring of pipeline pressure and flow conditions and to ensure effective communications with the central SCADA system.
Pipeline monitoring systems require an extensive network for connecting field devices over a fiber optic cable that runs parallel to the pipeline to monitor corrosion and third party damage in real-time, as well as to locate potential leaks and thermal anomalies. The following requirements are a must:
- Real-time data acquisition over wide areas
- Wireless communications
- High bandwidth for real-time video and data monitoring over vast distances
- Industrial-grade devices that meet safety standards and have a wide operating temperature range to construct a rock solid monitoring network for use in hazardous environments.
The Challenges of Modern Pipeline Monitoring Systems
A modern pipeline monitoring system should be highly reliable and able to facilitate secure interconnections between the process control and SCADA systems. Two major obstacles are:
Limited wireless bandwidth
At first glance, wireless communication seems to be the perfect solution for monitoring distributed systems spread out over a wide area. However, wireless communications usually employs the traditional passive polling method, which can pose a serious challenge as it takes up too much bandwidth.
System incompatibly caused by many proprietary protocols
To meet the demands for active/real-time status reporting, many system integrators create their own proprietary protocols, which are usually the root cause of system incompatibility and make integration extremely difficult if not impossible.
Choose Moxa for Reliable and Cost-efficient Pipeline Monitoring Solutions
With a history of success and extensive experience in reliable value-added Ethernet automation solutions, Moxa is an industry leader in OPC-based remote data acquisition solutions. These solutions not only reduce management costs, but also achieve complete network automation.
In pipeline monitoring, SCADA is often used to provide real-time video surveillance, automatic monitoring and control capabilities, and remote monitoring applications are enhanced with visual management. Traditional OPC has been around for years to provide interoperability between Ethernet data acquisition devices and SCADA systems; however, there are several limiting factors that deter many system integrators. Thankfully, new Active OPC Servers, with their "push" architecture, have made OPC technology a more viable solution for Ethernet data acquisition and SCADA applications.
Basically, OPC is middleware that operates between SCADA software and hardware devices. OPC is an open standard, which means lower costs for manufacturers and more options for end-users. Hardware manufacturers do not need to support different SCADA standards, and end-users can choose any OPC client software they want, creating a win-win solution for bridging hardware and software.
What Moxa Offers:
Moxa offers Active OPC Server, which is freeware that comes with ioLogik products. Unlike the traditional polling architecture, Moxa's Active OPC Server is an event-based or time-based alarm system that shoots back events or alarms actively. Active OPC Server is simple to integrate and works in a very similar manner as DNP3.0. The auto tag generation function, for example, requires no cumbersome tag settings or configuration. With Active OPC Server, no programming is required, and a few clicks is all it takes to create tags that will be pushed back to the central monitoring station.
Unlike DNP3.0, Active OPC Server can work with private and dynamic IP addresses. Even if your field devices are equipped with private or dynamic IP addresses, Active OPC Server will allow you to receive or set the remote station I/O status from the SCADA system.
Another distinct advantage is Moxa's 3-in-1 pipeline monitoring solution, the ioLogik W5300 series cellular RTU, which integrates a data logger, a cellular router, and a PLC into a single device. This solution not only saves money and space, but also makes maintenance and troubleshooting effortless and uncomplicated.
The demand for solutions that are more reliable and cost-efficient never stops; neither do we. Moxa never tires in providing innovative, value-added automation solutions that are cost-efficient, time saving, and simple to deploy.
For more information visit the remote automation theme site at:
http://www.moxa.com/event/net/2009/iologik_w5312/index.htm
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