Sunday, April 19, 2009

Teleprocessing through GSM and broadband - Express Computer

Its a Tech dream..without adequate and reliable water supply, whats the use of having this system...we should get our priorities right...

Teleprocessing through GSM and broadband - Express Computer
Teleprocessing through GSM and broadband

Water distribution networks can achieve great benefits with the adoption of GSM and broadband technologies for teleprocessing. By Varun Aggarwal

Utilities invest considerable sums of money in their water and wastewater networks—so it is probably worth spending a little more to ensure that they operate efficiently. As the vital importance of water conservation grows ever more apparent, large amounts (of water and money) can be saved simply through the rapid detection of leaks and other untoward events on a water network’s pipelines. The water industry has been slow to take advantage of information technology, but it is catching up quickly. In many parts of the world, water managers now depend entirely on real-time data to manage their water supply and wastewater services.

Automation has become a core enabler of operations. Water loss due to leakages is a bigger problem than people may think. With regard to water leakage in India, this is of major concern and of significant importance to those companies involved in the transportation of water any leakage can have significant financial consequences. In India, there is great opportunity and benefit to manage leakage considering the scarcity and cost of drinking water in the region coupled with unreliable weather prediction and truant monsoons. It is gradually being accepted that water networks need to be managed and maintained around the clock and, as a result, the concept of infrastructure asset management has emerged.

Conventional methods of leak detection rely primarily on the expertise of operators to identify leaks within the system based on pressure losses at various locations. Pressure management and DMAs (district metered areas) are used to prevent leaks and detection is typically done by using acoustic listening devices, leak noise correlators and tethered hydrophone systems.

Although this method works in the case of large leaks in which there is a considerable loss of pressure in the pipeline, it is more difficult to identify smaller leaks which, over time, cause the majority of the water losses. Leaks that are not visible in the water distribution system can go undetected for months and even years. Typically, water leaks do not happen quickly—they appear over a period of time.

The challenge is not only to detect, but even avoid a water leak in the first place. Data acquisition software allows a utility to collect data from all control systems and instrumentation, which is the key to water leakage prevention and detection. Without the data, a utility can only guess at the amount of leakage and would not be able to detect long run leaks that are not visible. Utilities need to be able to collect and analyze data before any optimization or leakage reduction can be accomplished and measured. Based on the constant stream of data collected from water meters, the system can conduct real-time water balances to alert operators of possible leaks or anomalies in the entire water distribution network. It can reconcile the entire water distribution system in real-time.

A typical water distribution system is spread over large geographical area and requires teleprocessing of data from remote area. Accurate and reliable data acquisition over telemetry needs reliable and affordable carrier (media) for data like flow, level, pressure, pump status etc. Media for teleprocessing should be easily available and simple in maintenance. Communication should be understood by semi- skilled staff operating at remote places without supervision.

Teleprocessing of data in the early 1990s was achieved often through licensed band radio or via satellite. With the continuous development of automation hardware and software, by the early 2000s European and American water industries started using RTUs based on GPRS/GSM/Broadband teleprocessing with small application logic built in. The technology now available for the Indian market is even more advanced, reliable, relevant and optimized.

GSM technologies

Niraj Desai is a Surat based System Integrator who runs a company called Nish Automation. His company has deployed many telemetry solutions in India for the automation of water distribution systems. According to Desai, “As the bulk of data logging occurs at remote places, this data is transferred using GSM channels to centralized control room through periodic data polling or data file transfer over data call generated by a predefined schedule. GSM-based systems also have an advantage of sending SMS periodically to various numbers, which can be logged. Data sent by this method is time stamped. This fulfills data acquisition needs of the system with accuracy and at a low cost. In the event of alarm conditions, it is sent out of turn with an exception report. The provision for sending SMS to mobile helps executives stay in touch directly with the system parameters.”

“However, SMS-based solutions have many limitations. SMS can be sent only in a predefined structure for the system to understand it. Moreover, in case of a bulk of data is required to be sent, it needs to be sent in multiple messages as SMS has a limitation of 160 characters. Another big issue is of reliability. SMS often do not reach the destination on time due to congestion in the operator network etc. Therefore, time stamping also becomes difficult with the use of SMS and real time processing is out of question here,” Desai added.

GPRS is the new way for telemetry. However, GPRS technology now available in India is better than the conventional way of using it in other countries. The conventional use of GPRS is through connecting to the Internet using a GPRS SIM. However, this mode of communication suffers with huge amounts of data loss due to call drops and is often rendered unreliable. Many telecom operators in India now offer data services through which one gets a dedicated GPRS connection through a GSM modem. This mode of communication does not suffer call drops as is the case of a regular GPRS connection and are more reliable. GSM data calls are also a more cost-effective mechanism for telemetry as compared to radio signals or VSAT connectivity. Nish Automation has already deployed this solution in water distribution projects in Hyderabad and Bangalore. Apart from water distribution, the technology is also viable for other purposes like gas and power distribution.
Essentials for a typical RTU or PLC based system

* Communication should be understood by semi-skilled staff who operate at remote places without supervision
* Local data storage capacity with time stamping capability
* Battery backup in the event of power failure
* In built GSM modem or facility to hook up external GSM modem
* Web-based navigation for programming and monitoring
* Ethernet Port for Broad band connectivity with relevant features like SNMP, DHCP and Port configuration
* Serial port for fetching data from the slave PLC
* HMI (Human Machine Interface) software with schedule dialup to the OPC server in case of GSM based system
* HMI software with routing and firewall for the broadband based system
* HMI software with remote connectivity for the MIS system

Broadband for higher reliability

One of the biggest inhibitors to the GSM data call is that not all operators offer this service. In metro or urban areas, where broadband is easily available, broadband and Internet-based data acquisition bring everything online in real-time. This is the best form of data acquisition combining accuracy and high speed. Broadband also offers better connectivity as there is no signal loss or network congestion in the case of broadband as compared to GSM technologies. Moreover, with dedicated leased line connectivity, higher security can be achieved on a broadband connection.

“When implemented with Google Earth features, geographic positions of pumping station or distribution station can also be embedded for easy viewing of operators. With this, a Supervisory Control And Data Acquisition system (SCADA) can offer a three dimensional representation of pipelines, leakages, visualization of flow and direction of the water etc. HTML-based configuration and programming make it programmable from anywhere without any geographical limitations. Each RTU becomes a Web server on its own, e-mailing reports directly to whosoever needs to read them,” opined Desai.

Both broadband and GSM technologies can help water distribution companies to get a faster, more reliable, and a lower cost solution for telemetry. Depending on the availability in the area, any of the two technologies can be implemented as in rural areas broadband may not be available and in urban areas, there can be issues like network congestion.


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