SCADA System Monitors Lift Stations Around The Clock

DIK LEDOUX

When the decision was made in Jefferson Parish, La., to replace the front end of its existing SCADA (supervisory control and data acquisition) system for the parishwide wastewater system, Integrated Controls chose a Windows PC-based system with Lookout industrial automation software from National Instruments as the MMI (Hu-Man Machine Interface) package.

Jefferson Parish is approximately 15 miles wide and lies just west of New Orleans. It is crossed by the Mississippi River and much of the district is below river level. Throughout the parish, sewer lift stations, drainage pumping stations, and water and wastewater treatment plants are tied to a central Emergency Operation Center (EOC) that monitors conditions throughout the area. Rain gauges at about half the sites provide continuous information regarding drainage conditions and their impact on the sewerage system. The previous SCADA system proved inadequate. An extensive search for a replacement resulted in the selection of Lookout. The integration team conducted on-site performance testing prior to the final decision.

Lookout is now the heart and soul of the EOC. The SCADA system achieves control at each of the 150 stations by a combination of stand-alone RTUs and manned operations. Typical data monitored at these sites includes pump status (current draw/speed), canal and wet-well levels, rainfall rates, radio signal level, and flow rates. Other monitoring stations are scattered throughout the area at parish offices, dispatching facilities, and major drainage pumping stations. These stations are tied to the primary/secondary PCs through the parish-wide Ethernet and by radio link as well. Response time is critical because weather conditions change across the parish, affecting drainage pumping stations downstream. SCADA nodes at these pumping stations provide information to users on a nearly real-time basis.

Jefferson Parish, La., needed to upgrade its SCADA system for a large, complex sewerage system to improve performance and reliability. Lookout software was used to integrate data from some 9,000 data points at 150 sites coupled by Ethernet and radio links.

Click here to enlarge image

The computer specialists chose Lookout as the MMI software because of its ease of configuration and the speed with which it could poll the number of sites required. The parish plans to expand the SCADA system to as many as 500 sites. Currently, the system includes 9,000+ data points. The system scan time across three separate radio frequencies at 9,600 bps is approximately 12 seconds.

The primary goal was a SCADA system that could gather the amount of information required and display it simultaneously to as many as 40 users (separate Lookout nodes) around the parish at any given time. The sheer size of the application was a primary challenge in the project. In addition, the complexity of the system was increased by special requirements for collecting and relaying information, as follows:

Radio links from the remote sites to the primary PC running Lookout - the primary PC polls all 150 of the field sites via three separate radio frequencies.
Ethernet distribution of the information around the entire parish - the primary PC also functions as the server for all of the Lookout nodes around the parish. Some of the sites are connected to the parish-wide Ethernet via a radio-LAN link. The sections of the parish on opposite sides of the Mississippi are connected via a fiber-optic LAN bridge.
Radio links back to the major drainage stations for rainfall and canal level information on the remote SCADA nodes at each of these stations.
Dial-in access for the drainage stations in the event of radio loss.
Dial-out to wastewater treatment plants not connected by radio links.

Another system requirement was a "hot" backup of the primary PC. Jefferson Parish is known for heavy rainfall from thunderstorms and hurricanes - flooding occurs with regularity. The parish required that the primary PC be reliably backed up with a secondary PC in case the primary fails.

System Development

Jefferson Parish contracted with Integrated Controls, Inc. (ICON) to put the system together. In addition to replacing the existing MMI with Lookout, the group assisted with converting the programs in the field RTUs to use the Modbus protocol because of the reduced overhead and inherent simplicity. They replaced the existing MicroVAX computers with two Pentium PCs with 32 MB RAM operating as redundant primary/secondary machines. Only a few corrections to the configuration were necessary during the extensive point-to-point checkout. They used Excel to generate comprehensive rainfall reports from data logged with Lookout spreadsheet objects.

They implemented the Lookout redundancy function, which was developed specifically for this project. The team generated a network version of the final process file and copied it to SCADA nodes distributed around the parish on the Ethernet. These remote Lookout stations are continually updated by the primary PC at the EOC. The secondary PC at the EOC acts like any other network machine, except that it monitors the primary PC for a failure. Automatic switch-over from primary to secondary is quick and reliable. The other PCs around the network simply note the loss of the primary PC and redirect their requests to the secondary until the primary comes back on line.

Initially, six of the 150 sites were installed for purposes of testing and review by parish personnel. Response time for the system at this point was predictably fast. When they completed the final installation, there was no appreciable difference in response time despite the fact that the I/O count grew by a factor of 80. ICON attributes this fact to the event-driven engine in Lookout. A single employee at ICON configured the overall interface. A team of people was not needed.

The overall response from the parish was very favorable. Paula Napolitano, manager of the Jefferson Parish SCADA Department, worked closely with the team during the project. She commented, "Lookout is much easier to use and maintain than the old system."