Hydroelectric power project gets complete control

ENEL, the national generators and suppliers of electrical power in Italy, chose GE Fanuc's Cimplicity and PLCs to monitor and control the SCADA system for a peak-time hydroelectric power scheme

ENEL, the national generators and suppliers of electrical power in Italy, chose GE Fanuc's Cimplicity and GE Fanuc PLCs to monitor and control the SCADA system for a peak-time hydroelectric power scheme.

Cimplicity HMI Viewer resides on two PCs running under Windows NT in the main control room, while Cimplicity Server in four operation rooms offers local operator access to the whole system.

The power station of Roncovalgrande is totally hidden inside a mountain beside Lake Maggiore which lies in the North-West of Italy close to the Swiss border.

The installation was started in 1971 and completed in 1973.

A 220m long tunnel into the heart of the mountain connects the entrance at the lake-side to the main generator hall together with its ancillary control gear and operations rooms.

The generator hall itself, measuring some 195m long x 18m wide x 58m high, has been carved inside the mountain and houses 8 water turbines which each drive an electrical generator.

The Hydro-Electric Power (HEP) station works like a power accumulator since it uses excess power during the night to store energy ready to satisfy greater electrical demand during the day time.

The electrical energy required to pump water from Lake Maggiore, via 8 multi-stage pumps to an artificial lake, Lake Delio, which is about 700m above the surface of Lake Maggiore, is obtained from over-production from other power stations on the national grid system.

This avoids the need to reduce the firing of solid fuel powered stations during the night.

During daytime, when the demand for electricity is greater, the potential energy of the water stored in Lake Delio is then converted to electrical energy by falling through 700m and driving the Pelton turbines, which in turn drive the electrical generators.

The water is returned to Lake Maggiore.

The artificial lake can store up to 11.2million cubic metres of water.

Each of the 8 generators is capable of producing 125MW over a 17 hour period, thus providing a total of 17M kWh of electrical energy.

This is supplied into the national grid at times of peak demand or when needed as a hot backup when other power stations may experience difficulties.

The electrical energy is fed via transformers to a distribution station on local Mount Bormia.

A dual Viewer system running under Cimplicity HMI on a Windows NT platform provides the overall supervision and control of the plant automation systems.

The 2 PCs continually gather and display all the variables of the system on user-defined Cimplicity Viewer screens in the Control Room.

They also perform data logging and actual and historical trending.

Intranet connection provides remote access via ENEL's internal WAN.

This enables interrogation of the system from a distant location.

When the original infrastructure was built, the SCADA system was operated via electromechanical and discrete electronic components.

During 1999/2000, the Cimplicity controlled network was installed and the automation, control and supervision interfaces were replaced by GE Fanuc 90-30 PLCs, fitted with CPU352s.

Each of the 8 sets of turbine/generator systems has a dedicated 90-30 PLC to control either the pumping of water up to Lake Delio, or the generation of electricity as the water returns to Lake Maggiore.

Each PLC supports around 1000 I/O.

The PLCs are located in pairs in each of the 4 operation rooms.

They are linked via a twisted pair Ethernet to local switches.

These 4 switches are on a fibre-optic Ethernet LAN, linked to a hub in the control room.

The Ethernet works on a TCP/IP protocol.

An operator in each control room also has local access to the supervisory system from a PC running CIMPLICITY Server.

A local printer provides a hard copy of all alarm signals.

Commands can also be given direct to the PLCs via hardwired local and remote push-button controls.

Apart from data acquisition and logic control, a critical task of these PLCs is to provide data to the supervisory PCs for the Sequence of Events (SOE) recorder, providing time stamps with a 10ms resolution.

An additional Series 90-30 PLC is dedicated to SOE recording of other services based in the plant.

According to Mr Tassera, Project Manager at ENEL Engineering in Domodossola, "Since the GE Fanuc system has been installed we have seen greatly reduced downtimes.

The speed at which the PLCs and Continued/....

Cimplicity can capture and store the Sequence of Events for later analysis is proving exceptionally useful.

Another great advantage derived from the use of Cimplicity is that multi-user and remote access has been enabled.".

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