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              Success Story: Electrical Energy

              Energie Ouest Suisse and Grande Dixence S. A. (Switzerland)

              Automation of Europe's Largest Peak Demand Hydro Electric Power Plant (423 MW)

              Success Story: Electrical Energy



              Customer profile:

              Energie Ouest Suisse and Grande Dixence S. A. produces electricity for the largest distribution companies in western Switzerland and transports it via a high voltage transmission network. To satisfy the growing demand for peak energy in Switzerland, Italy and France as well as utilise the huge water reserves in the Swiss Alps,  the company decided to develop a  new facility  as a major extension to an existing hydro electric power plant.



              EOS engineering, a subsidiary of the power plant owner founded for this specific project, completed the configuration and commissioning of the automation.



              Customer objective and constraints:

              The customer wanted to develop a new facility (Cleuson Dixence) and implement a control system that would provide:

              •  the ability to connect a wide variety of different sensors and actuators,
              •  the ability to communicate in an EMC disturbed environment and via long distances,
              •   time tagging of events,
              •   easy configuration and commissioning,
              •  debugging and simulation support,
              •   extensive documentation features.



              Implementation methodology (main phases):

              •  Schneider Electric actively participated in the conception, design and testing of the architecture.
              •  The EOS subsidiary carried out the configuration and commissioning.


              The project was completed in 2000.


              Solution overview (services, products, systems, architectures...):


              After a detailed evaluation phase, Schneider Electric provided a solution based on  Modicon Quantum programmable controllers for the automation part of the project. 90 Quantum PLCs automate the new turbine generator units and the extensive auxiliary installations. The Quantum PLCs have been programmed with Concept, the IEC 1131 programming software of Schneider Automation.


              A key requirement in this project however, was the collection and time tagging of events from the auxiliary installations and their transfer to a remote control centre. For this task the Quantum ERT time tag modules have been used successfully. They are time synchronised via a DCF 77 receiver in this project.


              Communication between, and programming of the PLCs is achieved quickly and efficiently via a Modbus Plus network, in both standard wire and fibre optic. Third party devices for special tasks have been integrated via special bridge Mux modules.


              For structuring reasons the system has been divided into 3 independent identical systems for the turbine units, with 25 PLCs each and a general system with 15 PLCs. The individual parts of the system can be manually controlled at the local level. There is a control room inside the plant with an HMI system for each of the four groups. The PLCs are connected to the HMI systems via the serial high speed network Modbus Plus.


              An Ethernet connection is provided for a supervisory centre in Sion, from where the power plant can be remotely controlled and monitored.

              Modicon TSX Quantum PLCs support the system structuring approach by having Modbus and Modbus Plus integrated into the CPUs. The PLCs are located in control cabinets and communicate with each other via Modbus Plus. Modbus Plus is used for system communication, as well as for distribution of I/O periphery.


              For connection of subsystems over long distances and for communication in EMC disturbed environments, some of the Modbus Plus lines are fibre optic. Bridge Mux modules have been used for integration of the 3rd party modules. A Bridge Mux offers the possibility to connect several devices with Modbus interface in an uncomplicated way to a Modbus Plus network.


              The functions are in detail monitoring and control of:

              •  Generator and turbines
              •  Ball valve
              •  500 MVA transformer for 423 MW
              •  380 KV switching substation in 300 m distance
              •  Auxiliaries for the turbines with remote I/O
              •  Auxiliaries for generator e.g. excitation and braking as well as lubrication of generator bearings.
              •  Auxiliaries for electricity distribution (16 KV and monitoring)
              •  Devices for measurement of voltage, current and power.


              The general system controls the following devices:

              •  Valve at the dam (20 km distant)
              •  Surge shaft in front of the high pressure pipe
              •  Cooling water valve (gate) at the Rhone level
              •  220/16 KV auxiliaries
              •  Cooling water pump (40 m above the plant)
              •  Auxiliaries of distribution (signalling and monitoring)
              •  Higher level control board for manual operation and safety devices.


              Each system contains an HMI station, a time processor for synchronisation and a unit for DCF 77 processing (for time tagging of events), as well as a parallel manual operation for emergency handling.

              Solution overview (services, products, systems, architectures...):



              Customer benefits:

              •   Open and Flexible architecture : the automation can be adapted to plant requirements.
              •  Ability to adapt output power supply from 0 to 1,200 MW in less than 3 minutes.
              •  Concept contains all IEC editors and offers extensive flexibility for programming, commissioning and system documentation.
              •  Time tagging of events was achieved.
              •   Remote plant access capabilities for control and monitoring.

              Schneider Electric differentiating values VS competitors:

              •  The customer was pleased with SE's thorough understanding of customer challenges and pain points.
              •  Provided strong extensive knowledge and technical support throughout the project.



              Other information


              The Cleuson Dixence plant is one of the world's largest high-pressure, hydro electric power plants. It has been built specifically for the satisfaction of peak demands. The normal base load of the electrical distribution networks are covered by nuclear, thermal and traditional hydro electric power plants. With an output of more than 1,200 MW this new peak demand facility produces more energy than the largest Swiss nuclear power plant. Water from the Grand Dixence reservoirs high in the Swiss Alps is used to propel 3 gigantic turbine generator units located in the Rhone valley. Each of the 3 generators produces 423 MW. The reservoir's dam is 284 meters high and stores 400 million m3 of water.


              During its descent, the water passes through 20 km of high pressure tunnels and shafts. After descending 1883 m, 75m3 of water per second hit the Sulzer Hydro turbines at a speed of 690 km/h. The water jets create an impulse of 57 tons/sec at each of the turbine vanes. To control this enormous energy a shut-off ball valve is located in front of each turbine. Additional shut-off valves are located at the dam itself and at the water lock in front of the high pressure pipe.


              As peak demands appear on very short notice, a fast start up of the turbines is imperative. The Cleuson Dixence plant reaches its top performance of 1,200 MW in less than two minutes.


              To satisfy environmental considerations, virtually all of the facility lies underground. From outside only a tunnel entry gives evidence of the installation. 150,000 m2 of soil were removed during the construction of the facility.

              Other information

              Key downloads & links


              Solution breakdown

              •  Process Control: 90 Modicon Quantum PLCs
              •  Programmimg Software:Concept
              •  Network: Modbus Plus
              •  Ethernet Connection