There are approximately 153,000 public drinking water systems in the country and almost 16,000 wastewater treatment plants. These water systems can be complex, with multiple pumps, tanks, valves and miles of pipelines. To keep these vast and intricate operations running smoothly and reduce the risks of unplanned downtime requires sophisticated technologies that allow equipment to communicate with each other.
Network Challenges
While water utilities have utilized supervisory control and data acquisition (SCADA) systems for years to improve operational efficiencies, most tend to have a wide range of installed SCADA equipment/networks that can vary considerably in terms of age, feature-set, connectivity and vendor support. In addition, systems often have been built piecemeal over the years by a wide variety of contractors, vendors and consultants, each with their own programming approach. The result: many water utilities now find themselves with complex, varied and comingled systems that are often difficult to manage in terms of operations, maintenance and overall system robustness.1
In an era of tight municipal budgets–even with grants from the American Infrastructure Act–the efficiency of the water and wastewater network must be maintained for costs to remain in check. One way to do this is to turn to Open Platform Communications (OPC). With OPC, access to machines, devices and other systems is standardized and enables similar manufacturer-independent data exchange. The goals of these solutions are to minimize friction points and increase efficiency. By treating devices as generic objects, the system can incorporate new components with minimal disruption. This technology has now gotten even more robust, more agnostic and more secure.
OPC-UA: Seamless Interoperability
Agnostic Connectivity, Powerful Information Modeling and Built-in Security
A challenge with water utilities’ varied networks is the secure, standardized exchange of data and information between devices, equipment and services, which is where Open Platform Communications Unified Architecture (OPC-UA) comes in. OPC-UA is an extensible, platform-independent standard that enables the secure exchange of information in industrial systems. It is compatible with Windows, macOS, Android and Linux and works on PCs, cloud-based infrastructures, programmable logic controllers (PLCs), micro-controllers and cyber physical systems.
It does not stop there though; OPC-UA is also designed to structure and share data to information technology networks and to the cloud beyond. It is the comprehensive information modeling framework provided by OPC-UA that allows it to relay context for information and go beyond simple data transmission, context that is critical for the data to be interpreted and used correctly by external systems. A process variable coming from a sensor value can be modeled with engineering units to allow proper interpretation, operational limits to validate modifications and adjust display and servicing information to provide an approximation of accuracy.
The security of cloud-based platforms has been a growing concern over the last decade. As OPC-UA is a communication layer for machine-to-machine and machine-to-cloud communication, it operates with two security layers. The first layer sets up an encrypted channel connection between the client and server. This layer provides confidentiality, integrity (through message signing) and certificate-based authentication. The application layer then manages user authentication and user authorization.2
Importance of Pumps and Lifts in Water Utilities
Key elements of every pump station include wet wells, pumps, piping with associated valves and strainers, motors, power supply system, equipment control and alarm system, odor control system and ventilation system. This is a lot of critical equipment to keep the operation up and running. SCADA systems monitor information, such as kilowatt (kW) consumption, tank levels, pump activity, gallons per minute or chlorine usage with full historic trends.
Both pump and lift stations contain a number of sensor and instrument field devices to gather operations data. An individual sensor may indicate whether a motor is on or off, a valve is open or closed, if a process variable reaches a limit value or other simple discrete conditions. Instruments provide more complex measurements of analog variables, such as flow, temperature, pressure and level.
Typically, a city will have these assets spread throughout a large geographic area, requiring remote terminal units (RTUs) to relay data from a site, such as a lift station to the SCADA system. The RTUs are likely from different manufacturers and may use distinctive radio technologies to transmit information. With OPC-UA, any device using the standard can be integrated into the platform without coding. After plugging in the device, it will automatically configure the capabilities of the system and structure the data collected.
OPC-UA allows for OPC to be used as a client or a server; it will provide data to various devices and applications to control equipment functions. OPC-UA server applications allow data exchange for machine-to-machine and PC-to-machine communication. OPC server uses include RTUs in field service applications. Another benefit of OPC-UA is that assets can be upgraded to this as they are repaired by deployed edge gateway devices as municipalities’ budgets allow.
Remote Alarm Notification Software
A key theme of OPC-UA is increasing connectivity between devices, networks and physical assets and the cloud. Increasing connectivity allows for greater process transparency and the added potential for predictive analytics and sentinel alarm conditions.
Better connected water utilities will allow potential problems to be addressed before they become problems, but only by extending that connectivity to the final hop–to the people who operate and optimize assets. Connecting devices to people and getting the right information (with increased sophistication of modeling) to the right people at the right time is the strength of remote alarm notification software.
Smart technology and OPC-UA are reshaping the deployment of remote alarm notification software solutions and their connectivity. As assets and processes become more populated with smarter sensors and are increasingly modeled at lower operational levels, the ability of remote alarm notification software solutions to connect both to SCADA and non-SCADA information sources is increasingly important. Advanced notification workflows will call for the synthesis of information from multiple OPC-UA servers in response to unfolding alarm events in SCADA. It isnice to know that a pressure sensor is registering a low alarm; it is better to know that information in the context of the status of the valves and pumps associated with that pressure, the maintenance information for that asset and the downstream impact of the low pressure.
Increased connectivity and information modeling will empower decision-makers, enable faster response times and drive increased productivity. Smart technology ready alarm notification software solutions connect to both the leading SCADA packages and to OPC-UA servers and provide for such advanced notification workflows.
References
https://www.grahamnasby.com/files_publications/NasbyG-PhillipsM_2011_SCADA-Standardization_ISA-W-WW-Symposium2011_jun2012_paper.pdf (accessed December 1, 2022).
https://www.machinemetrics.com/connectivity/protocols/opc-ua (accessed December 12, 2022).
