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| − | == Ballast or dump load ==
| |
| | | | |
| − | <!--{12766841534926}--><span>A ballast load is mostly an electrical resistance heater. It's sized to handle the
| + | [[Portal:Hydro|► Back to Hydro Portal]] |
| − | </span>full generating capacity of the microhydro turbine. They're placed in air or water. If there is more electricity produced then consumed the charge controller uses this excess energy to generate heat.<br>
| + | |
| | | | |
| − | Other but not common ballast load may be pumping water or ice production.
| + | = Overview = |
| | | | |
| − | == Load factor ==
| + | -> See article [[Micro Hydro Power (MHP) Plants|Micro Hydro Power (MHP) Plants]] |
| | | | |
| − | <span>The load factor is the amount of | + | <br/> |
| − | power used divided by the amount of power that is available if the
| + | |
| − | turbine were
| + | |
| − | to be used continuously. Unlike technologies relying on costly fuel
| + | |
| − | sources,
| + | |
| − | the 'fuel' for hydropower generation is free and therefore the plant
| + | |
| − | becomes
| + | |
| − | more cost effective if run for a high percentage of the time. If the
| + | |
| − | turbine is
| + | |
| − | only used for domestic lighting in the evenings then the plant factor
| + | |
| − | will be
| + | |
| − | very low. If the turbine provides power for rural industry during the
| + | |
| − | day,
| + | |
| − | meets domestic demand during the evening, and maybe pumps water for
| + | |
| − | irrigation
| + | |
| − | in the evening, then the plant factor will be high. </span>
| + | |
| | | | |
| − | <span>It is very important to ensure a | + | = Turbine Types<br/> = |
| − | high plant factor if the scheme is to be cost effective and this should
| + | |
| − | be
| + | |
| − | taken into account during the planning stage. Many schemes use a 'dump'
| + | |
| − | load
| + | |
| − | (in conjunction with an electronic load controller - see below), which
| + | |
| − | is
| + | |
| − | effectively a low priority energy demand that can accept surplus energy
| + | |
| − | when an
| + | |
| − | excess is produced e.g. water heating, storage heaters or storage
| + | |
| − | cookers. </span>
| + | |
| | | | |
| − | == Turbine types ==
| + | A [[Steffturbine - Hydropower Turbine|turbine]] converts the energy in falling water into shaft power. There are various types of turbine which can be categorized in one of several ways. The choice of turbine will depend mainly on the pressure head available and the design flow for the proposed hydropower installation. As shown in table 2 below, turbines are broadly divided into three groups; high, medium and low head, and into two categories: impulse and reaction.<br/> |
| | | | |
| − | <span><!--{127668415349214}-->[[Image:]]</span>
| + | The difference between impulse and reaction can be explained simply by stating that the impulse turbines convert the kinetic energy of a jet of water in air into movement by striking turbine buckets or blades - there is no pressure reduction as the water pressure is atmospheric on both sides of the impeller. The blades of a reaction turbine, on the other hand, are totally immersed in the flow of water, and the angular as well as linear momentum of the water is converted into shaft power - the pressure of water leaving the runner is reduced to atmospheric or lower. |
| | | | |
| − | <span>A turbine converts the energy in
| + | {| align="right" cellpadding="0" border="1" style="width: 100%" |
| − | falling water into shaft power. There are various types of turbine which
| + | |
| − | </span>can be categorized in one of several ways. The choice of turbine will depend mainly on the pressure head available and the design flow for the proposed hydropower installation. As shown in table 2 below, turbines are broadly divided into three groups; high, medium and low head, and into two categories: impulse and reaction.
| + | |
| − | | + | |
| − | {| cellpadding="0" border="1" | + | |
| | |- | | |- |
| − | | valign="top" rowspan="2" | <br> | + | | style="vertical-align: top" rowspan="2" | |
| − | '''<span>Turbine</span> ''' | + | '''<span>Turbine</span>'''<br/> |
| | | | |
| − | '''Runner''' | + | '''Runner''' |
| | | | |
| − | | valign="top" align="center" colspan="3" | | + | | style="text-align: center; vertical-align: top" colspan="3" | |
| − | '''<span>Head</span> ''' | + | '''<span>Head</span>''' |
| | | | |
| − | '''pressure''' | + | '''pressure''' |
| | | | |
| | |- | | |- |
| − | | valign="top" align="center" | | + | | style="text-align: center; vertical-align: top" | |
| − | '''High''' | + | '''High''' |
| | | | |
| − | | valign="top" align="center" | | + | | style="text-align: center; vertical-align: top" | |
| − | '''Medium''' | + | '''Medium''' |
| | | | |
| − | | valign="top" align="center" | | + | | style="text-align: center; vertical-align: top" | |
| − | '''Low'''<br> | + | '''Low'''<br/> |
| | | | |
| | |- | | |- |
| − | | valign="top" | | + | | style="vertical-align: top" | |
| − | Impulse | + | Impulse |
| | | | |
| − | | valign="top" | | + | | style="vertical-align: top" | |
| − | <span>Pelton | + | *<span>Pelton</span><br/> |
| − | </span> | + | *Turgo |
| | + | *Multi-jet Pelton<br/> |
| | | | |
| − | Turgo | + | | style="vertical-align: top" | |
| | + | *<span>Crossflow</span><br/> |
| | + | *Turgo |
| | + | *Multi-jet Pelton<br/> |
| | | | |
| − | Multi-jet Pelton <br>
| + | | style="vertical-align: top" | |
| | + | *Crossflow<br/> |
| | | | |
| − | | valign="top" | | + | |- |
| − | <span>Crossflow
| + | | style="vertical-align: top" | |
| − | </span>
| + | Reaction |
| | | | |
| − | Turgo
| + | | style="vertical-align: top" | |
| | + | *<span>Francis</span><br/> |
| | + | *Pump-as-turbine (PAT)<br/> |
| | | | |
| − | Multi-jet Pelton <br>
| + | | style="vertical-align: top" | |
| | + | *<span>Propeller</span><br/> |
| | + | *Kaplan<br/> |
| | | | |
| − | | valign="top" | | + | | style="vertical-align: top" | |
| − | Crossflow
| + | <br/> |
| | | | |
| − | |- | + | |} |
| − | | valign="top" |
| + | |
| − | Reaction
| + | |
| | | | |
| − | | valign="top" |
| + | <br/> |
| − | <span>Francis
| + | |
| − | </span> | + | |
| | | | |
| − | Pump-as-turbine (PAT) <br>
| + | <br/> |
| | | | |
| − | | valign="top" |
| + | <br/> |
| − | <span>Propeller
| + | |
| − | </span> | + | |
| | | | |
| − | Kaplan <br>
| + | <br/> |
| | + | *For further information, click [[Steffturbine - Hydropower Turbine|here]].<br/> |
| | + | *For information on Pump-as-Turbine, click [[:File:Pump as Turbine (PaT) Manual.doc|here]]. |
| | | | |
| − | | valign="top" |
| + | <br/> |
| − |
| + | |
| | | | |
| − | |} | + | [[Electrical-Mechanical Equipment#toc|►Go to Top]] |
| | + | |
| | + | = Generators = |
| | + | |
| | + | *[[Thermo Electric Generators|Thermo Electric Generators]]<br/> |
| | + | |
| | + | <br/> |
| | + | |
| | + | == Established Producers of Hydro Generators == |
| | + | |
| | + | Marelli |
| | + | |
| | + | == Induction Motor as Generator == |
| | + | |
| | + | = Controller - Function Principles<br/> = |
| | + | |
| | + | [[File:Mhp-scheme.jpg|thumb|center|605px|Elements of a Micro Hydro Power Scheme|alt=Elements of a Micro Hydro Power Scheme]]<br/> |
| | + | |
| | + | A Load- or Flow- controller ensures that the '''power output does not exceed the power demand''' and power output is stable (e.g. 230V, 50 Hz). |
| | + | |
| | + | Water turbines, like petrol or diesel engines, will '''vary in speed as load is applied''' or relieved. Although not such a great problem with machinery which uses direct shaft power, this speed variation will seriously '''affect frequency and voltage''' output from a generator. |
| | + | |
| | + | Traditionally, hydraulic or mechanical speed governors altered flow as the load varied. Nowadays usually electronic load controller (ELC) are used. These prevent speed variations by continuously adding or subtracting an artificial load ('''load controller'''). In that in effect, the turbine is working permanently under full load and the ELC diverts excess energy into a dump load, mostly a heater.</span> The traditional kind of equalizing power in and output by controlling the flow is usually also automatised ('''flow control'''). Thereby the ELC steers a valve which regulates the amount of water inflowing. |
| | + | |
| | + | In case of more power demand than supply the controller cuts off single users (clusters) in order to keep voltage and frequency constant for the others (first and second class connections). Load or flow controller are placed between generator output and the consumer line.<br/> |
| | + | |
| | + | [[Electrical-Mechanical Equipment#toc|►Go to Top]]<br/> |
| | + | |
| | + | == Controller Types == |
| | + | |
| | + | Fluctuating energy demand requires a mechanism which either regulates the water input into the turbine (= flow control) or by diverting excess energy from the consumer connection (= ballast load). |
| | + | |
| | + | For small micro or pico hydropower sites it's sometimes not easy to find the right controller. There is a lower price limit of several 100 USD even for only 1 or 2 kW power. In such cases there may be thought of manual control. |
| | + | |
| | + | [[Electrical-Mechanical Equipment#toc|►Go to Top]] |
| | + | |
| | + | === Load Control === |
| | | | |
| − | ''' '''
| + | The electric load controller (ELC) keeps outgoing Voltage and Frequency stable. Therefore the load on the generator has to be kept stable. The controller adds and subtracts an artificial load (heater) in a way to neutralise the fluctuations on the consumer side. |
| | | | |
| − | <span>The difference between impulse and
| + | [[File:Controler.jpg|thumb|right|734px|Controler|alt=Controler.jpg]] |
| − | reaction can be explained simply by stating that the ''impulse''
| + | |
| − | turbines
| + | |
| − | convert the kinetic energy of a jet of water in air into movement by
| + | |
| − | striking
| + | |
| − | turbine buckets or blades - there is no pressure reduction as the water
| + | |
| − | pressure is atmospheric on both sides of the impeller. The blades of a ''reaction''
| + | |
| − | turbine, on the other hand, are totally immersed in the flow of water,
| + | |
| − | and the
| + | |
| − | angular as well as linear momentum of the water is converted into shaft
| + | |
| − | power -
| + | |
| − | the pressure of water leaving the runner is reduced to atmospheric or
| + | |
| − | lower. </span>
| + | |
| | | | |
| − | == Load control governors ==
| + | <br/> |
| | | | |
| − | <span>Water turbines, like petrol or | + | <br/> |
| − | diesel engines, will vary in speed as load is applied or relieved.
| + | |
| − | Although not
| + | |
| − | such a great problem with machinery which uses direct shaft power, this
| + | |
| − | speed
| + | |
| − | variation will seriously affect both frequency and voltage output from a
| + | |
| − | generator. Traditionally, complex hydraulic or mechanical speed
| + | |
| − | governors
| + | |
| − | altered flow as the load varied, but more recently an electronic load
| + | |
| − | controller (ELC) has been developed which has increased the simplicity
| + | |
| − | and
| + | |
| − | reliability of modern micro-hydro sets. The ELC prevents speed
| + | |
| − | variations by
| + | |
| − | continuously adding or subtracting an artificial load, so that in
| + | |
| − | effect, the
| + | |
| − | turbine is working permanently under full load. A further benefit is
| + | |
| − | that the
| + | |
| − | ELC has no moving parts, is very reliable and virtually maintenance
| + | |
| − | free. The
| + | |
| − | advent of electronic load control has allowed the introduction of simple</span> and efficient, multi-jet turbines, no longer burdened by expensive hydraulic governors.
| + | |
| | | | |
| − | <br>
| + | === Ballast Load === |
| | | | |
| − | == Controller: <br> ==
| + | If energy demand is temporarily low the excess energy is dumped. It's converted into heat by some heat elements either in water or air. To increase an mhp's overall efficiency such excess power could be utilised as well. Therefore some storage technology would be required. Battery charging, freezers, water pumping or heat storage may be options. |
| | | | |
| − | <!--{12766848790530}--><!--{12766848790531}--> <!--{12766848790532}-->
| + | Regarding intelligent load management: [[:File:Operation and Maintenance of Small Hydro.pdf|Operation and Maintenance of Small Hydro]] by Dr Nigel Smith, Dr Philip Taylor and Tim Matthews |
| | | | |
| − | <span style="display: none;" id="1274973221030S"> </span> | + | <br/> |
| | | | |
| − | <!--{12766848790533}--><!--{12766848790534}--><!--{12766848790535}--><span lang="DE" style="font-size: 11pt; font-family: Tahoma; color: black;">Function </span><span lang="DE" style="font-size: 11pt; font-family: Tahoma; color: black;">[[Image:Mhp-scheme.jpg|right|560x386px|Elements of a Micro Hydro Power Scheme]]principles</span><br>
| + | === Flow Control === |
| | | | |
| − | Load- or Flow- controller ensure that the power output does not exceed the power demand (e.g. 230V, 50 Hz). <br> If flow of water in a MHP-station is constant the energy output of a turbine/generator is constant as well. Power demand is usually fluctuating over the time (e.g. day/night). If supply is higher than demand, excess energy must be diverted / dumped. Alternatively the water flow can be reduced which results also in less power output. <br> In case of more power demand than supply the controller cuts of the of single users (clusters) in order to keep voltage and frequency constant. <br> Load controller are placed between generator output and the consumer line.<!--{12766848790536}--> <span lang="DE" style="font-size: 11pt; font-family: Tahoma; color: black;">
| + | regulates the amount of water into the turbine in order to match power output and power demand. Nowadays flow control is done mostly via electronics, which steer a valve |
| − | </span>
| + | |
| | | | |
| − | <br>
| + | [[File:Flow-control.jpg|thumb|center|834px|principle flow control|alt=principle flow control]] |
| | | | |
| − | <br> | + | <u>Manual Flow Control:</u> |
| | | | |
| − | <br>
| + | In very small schemes often all power for lighting and TV is used constantly. Then energy consumption barely alters or does only at certain times. In such cases it can be even practical to train an operator who open / closes a valve manually to stabilise the Voltage. This allows to disclaim a controller, which saves costs and potentially flaws. |
| | | | |
| − | <br> | + | <br/> |
| | | | |
| − | <!--{12766848790537}--><!--{12766848790538}--> <!--{12766848790539}-->
| + | [[Electrical-Mechanical Equipment#toc|►Go to Top]] |
| | | | |
| − | === <span lang="DE" style="font-size: 11pt; font-family: Tahoma; color: black;">Controller Types</span> === | + | = Load Factor = |
| | | | |
| − | ==== Load controller: ====
| + | The load factor is the amount of power used divided by the amount of power that is available if the turbine were to be used continuously. Unlike technologies relying on costly fuel sources, the 'fuel' for hydropower generation is free and therefore the plant becomes more cost effective if run for a high percentage of the time. If the turbine is only used for domestic lighting in the evenings then the plant factor will be very low. If the turbine provides power for rural industry during the day, meets domestic demand during the evening, and maybe pumps water for irrigation in the evening, then the plant factor will be high. |
| | | | |
| − | [[Image:Controler.jpg|right|350x141px|Controler.jpg]]
| + | It is very important to ensure a high plant factor if the scheme is to be cost effective and this should be taken into account during the planning stage. Many schemes use a 'dump' load (in conjunction with an electronic load controller - see below), which is effectively a low priority energy demand that can accept surplus energy when an excess is produced e.g. water heating, storage heaters or storage cookers. |
| | | | |
| − | Electronic circuit, which keeps output power constant in Frequency- and Voltage- parameters.
| + | [[Electrical-Mechanical Equipment#toc|►Go to Top]] |
| | | | |
| − | Fluctuating energy demand requires a mechanism which either regulates the water input into the turbine (= flow control) or by diverting excess energy from the consumer connection (= ballast load).
| + | = Further Information = |
| | | | |
| − | ==== Ballast load ====
| + | *[[Control Equipment - Hydropower|Control Equipment - Hydropower]]<br/> |
| | + | *[[Hydropower - Equipment|Hydropower - Equipment]]<br/> |
| | + | *[[Steffturbine - Hydropower Turbine|Steffturbine - Hydropower Turbine]] |
| | | | |
| − | usually electrical heaters in water or air. If energy demand is temporarily low the excess energy is converted into heat.
| + | <br/> |
| | | | |
| − | ==== Flow control ====
| + | [[Electrical-Mechanical Equipment#toc|►Go to Top]] |
| | | | |
| − | regulates the amount of water into the turbine in order to match power output and power demand.
| + | = References = |
| | | | |
| − | Nowadays flow control is done mostly via electronics (which steer a valve)
| + | *General:[[Micro Hydro Power (MHP) Manuals|Micro hydro Power Manuals]] |
| | + | *[[:File:Good and bad of mini hydro power vol.1.pdf|Good and Bad of Mini Hydro Power]] |
| | + | *[[:File:Hydro scout guide ET may10.pdf|Micro Hydro Power Scout Guide]] |
| | + | *[http://practicalaction.org/micro-hydro-power-2 Micro-Hydro Power: Practical Action] |
| | | | |
| − | [[Image:Flow-control.jpg|left|650x264px|principle flow control]]
| + | <references /><br/> |
| | | | |
| | [[Category:Hydro]] | | [[Category:Hydro]] |
The difference between impulse and reaction can be explained simply by stating that the impulse turbines convert the kinetic energy of a jet of water in air into movement by striking turbine buckets or blades - there is no pressure reduction as the water pressure is atmospheric on both sides of the impeller. The blades of a reaction turbine, on the other hand, are totally immersed in the flow of water, and the angular as well as linear momentum of the water is converted into shaft power - the pressure of water leaving the runner is reduced to atmospheric or lower.
Traditionally, hydraulic or mechanical speed governors altered flow as the load varied. Nowadays usually electronic load controller (ELC) are used. These prevent speed variations by continuously adding or subtracting an artificial load (load controller). In that in effect, the turbine is working permanently under full load and the ELC diverts excess energy into a dump load, mostly a heater.</span> The traditional kind of equalizing power in and output by controlling the flow is usually also automatised (flow control). Thereby the ELC steers a valve which regulates the amount of water inflowing.
In case of more power demand than supply the controller cuts off single users (clusters) in order to keep voltage and frequency constant for the others (first and second class connections). Load or flow controller are placed between generator output and the consumer line.
Fluctuating energy demand requires a mechanism which either regulates the water input into the turbine (= flow control) or by diverting excess energy from the consumer connection (= ballast load).
For small micro or pico hydropower sites it's sometimes not easy to find the right controller. There is a lower price limit of several 100 USD even for only 1 or 2 kW power. In such cases there may be thought of manual control.
The electric load controller (ELC) keeps outgoing Voltage and Frequency stable. Therefore the load on the generator has to be kept stable. The controller adds and subtracts an artificial load (heater) in a way to neutralise the fluctuations on the consumer side.
If energy demand is temporarily low the excess energy is dumped. It's converted into heat by some heat elements either in water or air. To increase an mhp's overall efficiency such excess power could be utilised as well. Therefore some storage technology would be required. Battery charging, freezers, water pumping or heat storage may be options.
regulates the amount of water into the turbine in order to match power output and power demand. Nowadays flow control is done mostly via electronics, which steer a valve
In very small schemes often all power for lighting and TV is used constantly. Then energy consumption barely alters or does only at certain times. In such cases it can be even practical to train an operator who open / closes a valve manually to stabilise the Voltage. This allows to disclaim a controller, which saves costs and potentially flaws.
The load factor is the amount of power used divided by the amount of power that is available if the turbine were to be used continuously. Unlike technologies relying on costly fuel sources, the 'fuel' for hydropower generation is free and therefore the plant becomes more cost effective if run for a high percentage of the time. If the turbine is only used for domestic lighting in the evenings then the plant factor will be very low. If the turbine provides power for rural industry during the day, meets domestic demand during the evening, and maybe pumps water for irrigation in the evening, then the plant factor will be high.
It is very important to ensure a high plant factor if the scheme is to be cost effective and this should be taken into account during the planning stage. Many schemes use a 'dump' load (in conjunction with an electronic load controller - see below), which is effectively a low priority energy demand that can accept surplus energy when an excess is produced e.g. water heating, storage heaters or storage cookers.
