Challenge Expiration Date: January 31, 2018
Abstract
Enel Green Power is looking for economic, commercial solutions that can be used to dissipate energy in case of grid failures, thus granting the respect of the level of the discharge drain in hydro power plants.
Because of their smaller size and power capacity, run-of river hydro power plants are considered as intermittent renewable energy source therefore their control strategy must be designed to get the best possible tracking of the available river flow. In some cases, based on the plant design and on the license constraints, a power plant must grant a continuous water release from turbines, even when it’s not producing energy.
Description
BACKGROUND
In some plants, there are also constraints related to ensure continuous release of water from turbines respecting river in case of electrical grid failures.
In case of grid failure and GU outages for external causes, it is necessary to ensure total dissipation, to keep water level constant in discharge drain (level before outage = level after outage).
The dissipation system (resistor) must ensure compliance with these essential requirements:
- short switching times (ms),
- continuous operation at previous load before outage of the GU
- modular load, constantly aligned with the grid one before outage of the GU,
- rapid constructability (lower than 4 months) and installation times(1 month),
- Dimension compatible with annex 1 (layout of the actual installation site of rheostats), installation must be done on site due to the limited space of the access.
- Maximum admissible base load 1500 daN/m2,
- Automation system of the rheostat must be connected with the existing automation system of the GU,
- Maximum three-phase power load 25 MW and minimum 10 MW in any conditions at 10 kV.
In the event that fictitious loads are used, consisting of water tanks with fixed electrodes inside, it is also necessary to ensure full operation of the solution, even with significant variations in the water resistivity value of the river, typically 1000 ohm/cm (clean water) at 5000 ohm/cm (dirty water in case of full river).
The technology currently under review by local O&M is resistor, a rheostat, that acts as a variable resistance. Most rheostats are intended for use in high-power circuits with power ratings from several watts to several tens of watts.
There are many different types of variable resistors. The simplest are wirewound resistors with some of the wire exposed so that a movable electrode can be attached. The most common are adjusted with a rotary shaft as shown. The element provides a fixed resistance between terminals 1 and 3. The wiper moves to contact the element at different positions, changing the resistance between either end of the element and terminal 2.
Therefore, Enel GP is looking for economic (much lower than 1700€/MW), commercial and effective solutions to dissipate energy.
The maximum power that the system has to grant is 25 MW, the minimum 10 MW.
This is a Challenge that requires only a written proposal to be submitted. The Challenge award will be contingent upon evaluation of the proposal by Enel GP.
THE CHALLENGE
Enel GP is looking for economic, commercial and effective solutions to dissipate energy.
Any proposed solution should address the following Solution Requirements:
- must be able to dissipate energy (maximum 25 MW, minimum 10 MW), granting short switching times (a few milliseconds), continuous operation for at maximum 24hours at the maximum load (worst case conditions) and modular load constantly aligned with the grid.
- must be economical (much lower than 1700 €/MW, including capital, and installation costs)
- must be easy to install (installation time lower than 5 months) and require low maintenance cost
- must use no toxic chemicals or have any negative impact on the environment
- must have a long lifetime, ideally of 30+ years
- the proposed system should offer the Seeker “freedom to practice” or be available for purchasing. There should be no third party patent art preventing the use of specific equipment and materials for their application
Project Deliverables:
The solution may combine existing components, commercially available components and must be proposed as a unique solution.
The submitted proposal should include the following:
- Detailed description of the proposed solution that can meet the above Solution Requirements.
- Rationale as to why the Applicant believes that the proposed solution will work. This rationale should address each of the Solution Requirements and the Essential Requirements described in the Detailed Description and Background should be supported with relevant examples.
- Data, drawings, case studies, references or any additional documents that supports the proposed solution.
The submission should not include any information the Solvers may consider as their Intellectual Property they do not want to share.
