Case study: Evolving SCADA toward energy management
Water has always played an important role in the development of Monroe County, N.Y. The county borders Lake Ontario and contains the city of Rochester, whose port dates back to the 1700s. In the early 1800s, the Erie Canal was routed through downtown Rochester and prosperity continued for Monroe County as the New York Central and other railroads were installed parallel to the canal.
Today, Monroe County’s water resources are protected by Monroe County Pure Waters, consisting of associated collection systems and two wastewater facilities. Monroe County Pure Waters manages 50 pump stations, 12 monitoring sites, and 30 deep tunnel sites that collect storm water. The Frank E. VanLare facility is in the middle of a three-year project to change out its 60 mechanical aerators, replacing them with diffused air, as the Northwest Quadrant facility continues to use mechanical aeration. Both facilities use centrifuges and thickeners before shipping sludge to a landfill.
The supervisory control and data acquisition (SCADA) system represents the heart of Monroe County Pure Waters’ collections and treatment operations. This system has grown from its original mandate and continues to evolve with the needs of these operations.
Monroe County Pure Waters SCADA system evolution
Like many other utilities, Monroe County’s first experience with programmable logic controllers (PLCs) led to the installation of multiple platforms. Its first PLC was a Square D SY/MAX, installed in 1984. Over time, Monroe County realized the benefits of a single programmable automation controller (PAC) platform. In addition to providing a single software architecture, having a single PAC platform can result in a unified network strategy for the future. Therefore, in the mid 1990s, Monroe County began migrating all of its existing PLCs, including 20 at Frank E. VanLare, three at NorthWest Quadrant, 10 at deep tunnel sites, and 18 at pump stations to Schneider Electric’s Modicon Quantum PAC.
“We decided to adopt the Modicon Quantum PAC because the ladder logic programs from the SY/MAX (PLC) could easily be moved to the programming software and would make life easy for us,” said Curt McEntee of VSG Enviromation, a division of Zeller, the county’s selected control systems integrator.
The existing SCADA system was a mainframe-based system that was suspected to have several issues due to year 2000 (Y2K) speculations. Monroe County could not risk a blind implementation of a new SCADA system; therefore, it followed a two-step approach:
In the first step, the county interviewed different SCADA providers about their Y2K readiness and ability to stand by their system. Schneider Electric’s Vijeo Citect SCADA system was able to assure the county of Y2K readiness without any hesitation.
The county was impressed with Vijeo Citect SCADA, but before fully committing to the solution, it wanted to see it perform on a small-scale system. Thus, Monroe County Pure Waters decided to install the solution on a landfill that it was managing at the time. “The landfill system was the perfect test bed for Vijeo Citect SCADA. It consisted of a central location with three remote pump stations. These pump stations were PLC-based and communicated via radio network,” McEntee said. “From a control and automation viewpoint, this was a small-scale model of the countywide collection system.”
Following completion of the SCADA system pilot, the county’s path was set for its collection and plant operations, which at that time were on separate systems. Vijeo Citect SCADA was installed on the collection system in 1998 and the treatment plants in 1999. This new SCADA system provided a common database which enabled both groups to be combined into a single location.
While the SCADA system was being upgraded, the PLC systems were also going through a transformation. When the original PLCs were installed in the 1980s and 1990s, a variety of systems and manufacturers were utilized, many of which were set up as stand-alone processes.
“The original purpose of the system upgrade was to solve the Y2K challenge,” McEntee said. “However, during implementation it became apparent to everyone that we could network these systems together and there was huge benefit. This led to the elimination of functional islands. We have not looked back since.”
Eventually, the SY/MAX PLC reached its end of life and Schneider Electric expanded its PLC offerings when it acquired Modicon. Thus the county began replacing its SY/MAX PLCs with the more advanced Modicon Quantum PACs—still an ongoing program.
Today, Monroe County’s automation system consists of a variety of these PLCs. The Vijeo Citect SCADA software system is currently running on a dozen shared I/O servers and also supports about six stand-alone isolated sites. With 10 dedicated display clients and 30 intranet clients, Monroe County Pure Waters is in the process of implementing Vijeo Historian software—a plant-wide tool that collects, stores, and delivers reporting data from the SCADA system and other databases. Monroe County is also in the process of upgrading everything to Ethernet. Currently the radios and leased lines are Modbus-based, and the fiber optic is Ethernet-based.
The new SCADA system was able to enhance operations for both the treatment and collections teams. Therefore, Monroe County Pure Waters was able to identify that the main plants had sufficient capacity and the collections system was able to respond rapidly to changing conditions. Through this visibility, the county was able to close several small remote plants (1 million gallons per day each) and convert them to pump stations. This eliminated several small stream discharge points that led into the Genesee River.
SCADA empowers power monitoring system
The investment that Monroe County has made in its SCADA and automation systems provided many benefits to the control and operation of the collection and treatment systems at Monroe County Pure Waters. With such success, the county also decided to add power data to the system.
Monroe County Pure Waters now uses a Schneider Electric PowerLogic system to monitor its power usage. The collected data is displayed on the SCADA interface. Monroe County Pure Waters then compares the power usage against process parameters to give an indication of process efficiency. These same systems are now used pervasively across Monroe County facilities.
Today what was originally designed as a wastewater utility’s replacement of a SCADA software from a non-Y2K compliant mainframe system has become much more. The SCADA still monitors and controls the wastewater utility. However, it is also tied into the power monitoring systems of both treatment plants and a combination of 24 collection and tunnel sites. Future plans call for the extension of the SCADA system and power monitoring into each Pure Waters facility managed by the Monroe County Department of Environmental Services.
All of this data is being mapped into the SCADA system, and Vijeo Historian software is being implemented to enhance the data trending and analysis of all of these interconnected facilities. Monroe County is well on its way to reaching the day when it will be able to map and track all power users across the entire Pure Waters network with the ability to identify system-wide energy savings.
– Grant Van Hemert, PE, wastewater applications specialist, and Dick McDonnell, business developer, Schneider Electric Water and Wastewater Competency Center. Edited by Jordan M. Schultz, associate content manager, CFE Media, Control Engineering, email@example.com