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September 27, 2020
Water power plants in each particular area are built because of two purposes. Local and Nationwide. In case of local, each installation has some different purpose, tying to fill in the gap of specific mechanical or energy problem that occurs in the given area, e.g. water mill,water hammer, funicular, local railway for mine or wood. Alternatively, hydro power plant could help to generate hydrogen or support local power grid because of the current trends in transport transformation to electric and hybrid power hence the higher power demands and green energy limitations. Also it many times seen as a viable option for decentralized generation (DG approach).
On the other hand the nationwide purpose is completely different agenda and it is usually based on the country´s hydrological system. For example, in Slovakia most of the hydro power plants are weir types, because of simple fact that overwhelming majority of the Slovak rivers spring in Slovakia thus their aquosity is either low or extremely volatile on the contrary Taiwanese hydro power plants are combination of predominantly cascade, diversion and large accumulation types because of the annual precipitation rate, typhoons or sudden droughts.
What is more Taiwan is an island country thus it is quiet important to keep the fresh mountain water on surface as long as possible. Therefore hydro power plants have many times multifunctional character e.g. maan hydro power plant on Fig. 1. below which except the electrical energy generation also incorporates retention basins further used for irrigation, drinking and industrial water supply. On the other hand Slovakian water structure Selice has regulation, navigation and electrical energy generation function.
Large and medium types
Accumulation type Using reservoir with dam or surging weir Pumped storage Using two reservoirs Weir type Using river regulation weir
Small, Micro and Pico types
Weir type Using existing weir originally built for water level regulation or newly built surging weir.
Pumped storage Using two reservoirs or lake and water tank with
Derivative or diversion types usually called Run-of-River types ROR.
Using diversion weir or not using weir at all.
1. No pressured derivation Using diversion canal, side canal, adjusted river arm or river bed.
2. Positive pressure derivation Using penstock
3. Negative pressure derivation Using siphon tube
4. Combined derivation (No pressured and positive pressure or No pressure and negative pressure)
Figure 3: Classification of Small, Micro and Pico hydro power plants according to configuration from Table 2.: A-Standard weir type with rubber weir, B-Derivation including accumulation cascade, C-Small PS hydro with upper pond or water tower D-Standard diversion via diversion canal, E- Combination of no pressure with positive and negative pressure configuration. (fig. source: Author 2018).
Table 3: Classification of hydro power plants according to installed capacity.
Large/Very large >100MW / 0,5GW
Medium 25 - 100MW
Small 1 - 25 MW
Mini 100kW - 1 MW
Micro 5 - 100kW
Pico < 5kW
There are any ways how to further set typology of hydro power plants, in this paper we use division based on Table no.2 where hydro power plants are divided according to their capacity and configuration.
Based on the installed capacity listed in Table no.3, hydro power plants could be divided from very tiny private pico, micro and mini systems which capacity usually does not exceeds 1000kWs, then small or medium installations with capacity measured in MWs up to large or very large water works which capacity is set mostly in GWs. For example within Visegrad area we can sort out large installation like Slovak "Vodné dielo Gabčíkovo"(720MW),
"Žilina"(72MW) or "Orava"(21.75MW), but naturally there are even larger installations like Russian "Sayano–Shushenskaya"(6400MW) power plant, Brazilian "Itaipu"(Table no.4) on Paraná River which currently holds the world´s record on annual production or according to the installed capacity the largest installation among all located in Chinese, Hubei on Yangtze River known as "Three Gorges Dam"(Table no.4).
There are no major questions regarding the magnitude of large scale installations accept possible ecological risks, however if it comes to small hydro power plants(SHP), the installed capacity is many times a point for debates as it has not been fixed yet. For instance in Italy it
represents 3MW, in Germany 5 MW, in Poland and Hungary 5MW, in Czech Republic,Slovakia, Austria and Philippines 10MW, however Taiwan has 20MW, India 25MW, USA 30MW and below, China and Canada has both 50MW). For all that the maximum capacity of 10MW is commonly recognized according to ESHA (European Small
Hydropower Association), Small Hydropower World portal developed by ICSHP (International Center on Small Hydro Power) and UNIDO (United Nations Industrial Development Organization) and will be further used in reference to the SHP