A) FULL CYCLE EFFICIENCY
The design of the Mont-Negre hydro system with a maximum water flow speed of 3.00 m/s in both directions and the short length of the pipelines optimise the efficiency of the operational cycle of the plant as proven by the ratio between energy supplied to the network and the energy consumed by the plant. Annex I – “Water concession project” include the annual values of the energy supplied and consumed. These values are in Annex 6 – “Production analysis” of the mentioned Annex I andare shown below:
| annual energy supplied through turbine: | 5,808,000 MWh/year. |
| annual energy consumed through pumping: | 7,464,154 MWh/year. |
Therefore, system efficiency is:
B) HIGH ANNUAL AVAILABILITY, FLEXIBLE PROGRAMMED MAINTENANCE
The plant is designed with 12 independent reversible units with sufficient slack time between hours of operation (at nights and during peak hours during weekdays), leave more than sufficient margin for proper maintenance and conservation of the equipment. Utilisation of the power plant will not be affected.
C) POWER GENERATION RAMP-UP AND RAMP-DOWN. DEPTH OF DISCHARGE
The 118 Hm3 capacity of the upper water reservoir provides a wide margin so as to be able to operate the power plant to demand, i.e. operating the Mont-Negre reversible pumped storage in accordance to the specific instantaneous needs and requirements of the system.
The maximum power ramp-up/down is::
| Per turbine: | 55 MW/min. |
| Per power plant: | 660 MW/min. |
Depth of discharge is the percentage that the upper reservoir could be discharged before pumping starts, it is set to 100%.
D) RELATIONSHIP BETWEEN STORAGE CAPACITY AND POWER.
The basic guidelines for the project require that the plant has a minimum installed capacity of 225 MW a a minimum annual power generation capability of 250 GWh/year. In this context, the installed capacity and power generation capability of the Mont-Negre plant are:
| Total installed power: | 3,300 | MWh. |
| Energy production for the network: | 5,808 | GWh/year. |
From these values it can be established:
- – the relationship between the two:
The implicit hours of operation of the Mont-Negre plant (1,760 h) are greater than the hours stated in the guidelines (1,111 h).
- – In summary, the basic parameters of the Mont-Negre plant exceed the minimum requirements set by the guidelines:
In respect to power 3,300 MW versus 225 MW
In respect to storage 5,808 GWh versus 250 GWh.