SCADA upgrade for Lake Como aqueduct system

Lake Como, in northern Italy, is served by nearly 60 km of aqueducts. The aqueducts draw water directly from the lake and pump it to storage tanks. The water flows from the tanks via more aqueducts serving businesses around the lake, so the reliability of the water system is paramount, because water disruption leads to lost production for manufacturers in Como.

After 30 years of service, the SCADA system was in need of modernisation, and energy costs in the region have risen significantly during the last 30 years. The geography of the lake, set in mountainous terrain, is also particularly challenging to water management, so the modernisation of the SCADA system created the opportunity to not only take advantage of technology advances, but also to review water management concepts and to introduce energy profile management.

Pumping forms the greatest percentage of energy consumed. Energy profile management involves analysing daily consumption and comparing to lake levels, which allows projection of the storage required. The setpoints for the pumps are managed such that the tanks are filled at night when electricity is less expensive. Operating the pumps during the day is possible, but minimised to reduce costs.

The SCADA collects other relevant operational data from the system, including the continuous recording of pressure, level, flow rates and volumetric meter readings.

The telecommunications were evaluated in the early phases of the project, and the decision was made to move to an Ethernet-based network. Existing landlines interconnect the PLCs and the SCADA host, so HDSL was used to provide the Ethernet network over the telecommunication system.

The Ethernet-based network provides multiple advantages over a fieldbus architecture, including the potential for future revenue sources. For example, other Lake Como utilities may lease bandwidth for their own industrial protocols or other applications such as surveillance and telephony may be hosted. The design also made the telecommunications independent of PLC and SCADA technology.

A client-server architecture was chosen for the SCADA system. The simplified design is based on commercially available hardware with a modular open architecture for easier maintainability.

PcVue, from ARC Informatique, was chosen for versatility and ease of maintenance. The graphics provides a very lean display, thanks to modern symbols for visualisation and animation. Using a branching structure, the tags in PcVue minimise the number of screens to be developed. The client station deployment is essentially automatic - clients are enabled by simply sharing the project file, therefore any modification for the project can be made on the server and copied to the clients.

The system has about a thousand alarms, which are divided into priority levels. All of the alarms are stored and are available in both textual forms and with graphic animations. When alarms are raised, the SCADA uses contextual logic to determine the appropriate course of action. For high-priority alarms, SMS text messages are sent to the operator based on the concept that the operator can connect to the network and acknowledge the alarm. If the operator does not respond within a designated time, the system will resend the SMS message until the alarm is acknowledged.

Even the choice of the contractor was strategic. Only qualified system integrators capable of design and implementation of the entire system with full autonomy were considered.

A critical aspect was to bring the new system online with minimal disruption. It was not easy to manually operate the system and only possible for short times during emergencies. To replace the SCADA, a total halt of the waterworks was required, so well organised and coordinated teams worked simultaneously on all sites to keep disruption during installation and commissioning minimised.

The selected system integrator, TSA, provided a careful analysis of the state of the art in existing similar systems. TSA formed a partnership with Borghi, which had previously been responsible for the design and installation of new electrical switchgear and control. The synergy between the two partners (TSA-Borghi) allowed for a competitive proposal with a substantial savings in cost. More importantly, the team had all the necessary areas of expertise to be able to execute all stages from design to commissioning without depending on third-party subcontractors.