Ηydroelectric installation studies encompass various phases, the extent, and depth of which significantly depend on the nature and size of the installation.
To complete a hydroelectric project, three types of studies are required.
Firstly, a feasibility study is conducted to determine if the examined location warrants further investigation. This study includes:
Determining the height of the drop and the initial selection of the water intake position, as well as the location of the power station.
Plotting the flow duration curve of the location to estimate annual energy production and calculate the project’s annual revenues.
Estimation of construction cost based on the area’s morphology, the length of the penstock, the type of electromechanical equipment, and the distance of connection to the Hellenic Electricity Distribution Network (DEDDIE).
Estimating the construction cost of the project based on the area’s morphology, length of the penstock, type of electromechanical equipment, and distance of connection to the power distribution network.
In case the result of the Feasibility Study In the event of a positive outcome from the feasibility study, and if the interested party wishes to proceed with the project, the pre-feasibility study is then carried out. Its aim is to shape and dimension the project, as derived from examining and analyzing various alternative solutions. The analysis level of the pre-feasibility study is adequate for obtaining the various permits required for the project’s construction.
The Design Based on the results of the feasibility study, the design phase includes:
Selection of turbines and determination of their hydraulic characteristics.
Selection of generators with their respective characteristics and all related electrical equipment.
Definition of the automation system characteristics and operation of the installation.
Determining the water intake system at the station, meaning the water abstraction, the intake pipeline (open or closed), the loading tank, and the rest of the auxiliary facilities.
Building infrastructure for the installation of the mechanical equipment (ensuring the arrangement of the turbines and generators allows easy access and maintenance without interrupting the operation of the remaining units), automation systems, all auxiliary equipment, the substation, and connection to the grid.
Although the result of the pre-installation study is positive, the final installation study is then conductedwhich involves compiling all plans, calculations, results from economic analysis, specifications of necessary equipment, as well as the environmental impact assessment. Upon completion of the installation study, the construction of the project begins.
For the elaboration of a hydroelectric plant study, the following steps are followed:
Identification of the area. It includes the initial arrangement and location of the project, recording local conditions, difficulties, infrastructure, other competitive water uses, studying geological conditions, and determining the demand for electricity in the area.
Collection and evaluation of existing hydrological data and plotting the duration curve of the flow.
Market research and availability. The cost of the turbine, generator, generator controller, and installation pipes is examined since these will be the most expensive components.
Calculation of generated power. Depending on possible combinations of hydraulic elevations and flows achievable, the generated electrical power of the installation is calculated and assessed for sufficiency or insufficiency for the operation of a hydroelectric plant.
The power of the installation is calculated by the following formula:
P = nxρxgxQxH
Where:
P: the generated operational electrical power (kW).
n: the overall efficiency score of the installation.
ρ: water density (≈1000 kg/m3).
g: acceleration due to gravity (≈9.81 m/s2).
Q: flow passing through the turbine (m3/s).
H: available head (m).
The calculation using the above formula is approximate. That is, an overall efficiency score for the installation is considered (a value within the range of 55-75% is fairly close to reality), and then, with known flow and head values, the generated electrical power is calculated.
The total efficiency score of the installation depends on the efficiency scores of the individual components comprising it, calculated as follows:”
n = nHydro turbinex nγεννήτριας x nμετασχηματιστή
Oβαθμός απόδοσης του υδροστροβίλου, αποτελείται και αυτός από επιμέρους βαθμούς απόδοσης και προκύπτει από την εξής σχέση:
nHydro turbine = nEngineer x nHydraulicx nVolumetric
The data usually available during calculations are the nominal performance degree of the hydro turbine and the nominal performance of the generator and transformer. Therefore, the overall nominal performance degree of the installation can be calculated.
Calculation of installation requirements. At this stage, the minimum electrical power that must be generated by the installation’s generator is calculated to ensure that all devices designed to be connected and powered by it operate at the desired level.
Calculation of the generator size based on the installation’s requirements and expected cost.
Preliminary economic sustainability check. Depending on the estimated generated power and the installation’s requirements, the optimal design is chosen, and the annual income is compared with the investment capital cost.
Selection of the suitable combination (or combinations) of flow rates and hydraulic head to produce the required power from the hydro turbine-generator system, along with estimates for the installation’s performance degree.
Selection of the final output power value. The final size of the generator to be used is estimated based on accurate data of the hydraulic potential and the installation’s flow that were calculated.
Installation design. Plans and maps of the installation are constructed, including all elements of the installation, their dimensions, and layout.
Check if any alternative solutions in the installation design could lead to lower costs or more favorable operation.
Detailed cost calculation. The cost of each element of the hydroelectric installation is calculated, and subsequently, the total initial cost is determined.
Economic sustainability check based on the new estimated cost of the installation. If the investment remains economically unviable, elements of the installation that caused additional economic burden should be replaced with newer, cheaper ones.
Ordering of materials and all necessary equipment for the project, according to the calculations made, and their installation according to the installation design.
Training of personnel who will oversee maintenance and the overall operation of the unit.
Commissioning after ensuring the correct placement and connection of all individual components.
