Mini & Micro Hydro Power Generation EBARA Hatakeyama Memorial Fund Tokyo, Japan
Definitions Large Scale hydro power generation : Capacity 100(MW) Most of them involve major construction of dams. Small Scale hydro power generation : Capacity 5(MW) per site Commonly do not involve major construction of dams. Most of them are Run-of-river type. less environment impact Micro Scale Hydro : Capacity 100(kW) per site
Advantages of Mini/Micro Hydro Schemes 1. Renewable and sustainable source of electricity Hydro energy is a free and a continuously renewable electrical energy source. Hydropower is a completely national resources, without importing any other fuel. 2. Little or no environmental impact No water pollution or greenhouse gas emissions 3. Technology is proven and reliable 60~80(%) efficiency for conversion to electricity Low operating and maintenance costs Full time staff are not required for serving. The system can be integrated with water supply for irrigation and potable systems The working life of the machine is much longer than for diesel generator
Advantages of Mini/Micro Hydro Schemes (continued) 4. Long life equipment Existing plants have been in operation for more than half a century and are still providing continuous power as long as water resources are sufficient. 5. Create job opportunities locally In remote areas, small hydro may have a positive impact on the development of local communities where young people may leave the farms because of low income from farming. The possibility of supplementary income from local electricity production with possibility to start small industry could be the goal for small hydro development in remote areas of developed countries as well as for developing countries. Hence, reduce population migration from remote rural area to urban
Disadvantages of Mini/Micro Hydro Plants 1. Seasonal Water Flow Fluctuation Flows often vary throughout the year, affecting the availability of water in a certain seasons. 2. Location is everything Locations where power can be economically exploited are limited. The best sites have a reliable water supply year-round and a large vertical drop in a short distance. 3. Long construction period and higher initial investment The problem is that the new investors place primary importance on short payback time( Fast Money ), where the long life of system is not reflected in the economic analysis of small hydro projects.
Flowchart of Mini Hydro Project Planning Potential Site Site Reconnaissance Demand Side Identification of System Layout Confirmation of Design Discharge Selection of the Civil Structures Location Confirmation of the Head B Selection of the Generating System A Selection of Power Demand Facilities C
B A Examination of Demand and Supply Balance C Rough Estimation of the Project Cost Project Implementation Stage (Source)Manual for Micro-Hydropower Development/DOE & JICA
Classification of Hydro Plant Reservoir type Power Station Conduit type Power Station(Run-of-River type)
Intake Canal Route Parallel to river system A system taking water from the up-stream, providing a canal along the river and feeding water to turbine by steep penstock Short cut system A system providing a short cut canal at the bend of a river, and feeding water by steep penstock.
Micro Hydro Unit beside Irrigation Weir Irrigation Weir A B C G E F A B C E F G Intake Lateral By-pass Canal HeadTank GeneratingUnit Tailrace Transmission/Distribution Line - whenever a weir imposes an excess head relatively to the downstream delivery flow, a micro unit can be envisaged in order to replace a dissipation structure. - along an irrigation canal system, significant difference topographic level can be used and diversion scheme can be implemented out of irrigation period.
Run of River type Micro Hydro Generation System A Intake B A B C Lateral By-pass Canal Head Tank C D E Penstock Pipe Generating Unit G Transmission/Distribution Line D G E In order to take the advantage of a local significant difference topographic level created by a weir or a small dam, only a part of stream flow is used to generate power.
Up Stream Rubber type Weir (Inflatable Weir) Stream Flow type Power Station (Rubber Weir) Trash Rack Down Stream Head Race Spillway Intake Screen Stop Log Penstock Tail Race Head Tank Power House Distribution Line
Inflatable Rubber type Weir
Application of Rubber Weir Plant type : Run-of-River type Max. Flow : 4.6(m 3 /s) Max. Head : 42.0(m) Max. Output : 1,500(kW) Commissioning : 1991 Intake Facility(Rubber Weir) (Dimensions : 27.4m L x 2.0m H )
Application of Rubber Weir Plant type : Run-of-River type Max. Flow : 1.8(m 3 /s) Max. Head : 79.9(m) Max. Output : 1,200(kW) Commissioning : 1997 Intake Facility(Rubber Weir) (Dimensions : 22.0m L x 2.0m H )
Water Intake Facility for Micro Hydro Turbine
Points necessary for Mini Hydro Exploitation The following items shall be taken into the consideration for Mini Hydro Exploitation. A high rainfall catching area A river or water source with a suitable head of water A easiness of water intake placing in a stream A easiness of transporting the water to the turbine (Easiness of installation of conduit pipe or channel) A easiness of electrical distribution line/grid connection A easiness of returning its water to the main stream Topography, Rainfall data, Availability of funds
Assessing Hydro Plant Capacity The amount of energy at a given site can be assessed as ; P=9.8 Q H e, e=ηt ηg ηgr where, P : Plant capacity (kw) H : Turbine net head (m) Q : Water flow to turbine (m 3 /s) e : Turbine generator combined efficiency Mini Hydro : approx. 75~85% Micro Hydro : approx. 65~75% ηt : Turbine efficiency(=75~90%) ηg : Generator efficiency(=85~96%) ηgr : Speed increaser efficiency(=97~97.5%) For assessing the power potential, Q and H shall be measured at site.
Classification of Hydro Turbine Impulse Turbine Pelton Turbine Cross Flow Turbine Turgo Impulse Turbine Reaction Turbine Francis Turbine Propeller Turbine Kaplan Tubular Bulb Centrifugal pump as turbine
Specific Speed vs Applicable Turbine Type Ns= N P 0.5 H 1.25 where, N : Turbine Speed (min -1 ) P : Turbine Output (kw) H : Net Head (m)
Pelton Turbine Bulb Turbine Turbine Types Francis Turbine S type Tubular Cross Flow Turbine Straflo Turbine
Mini Hydro Turbine Selection Chart 1000 Pelton ペルトン 水 車 有 Net 効 落 Head 差 ( m) (m) 100 10 Mixed Flow DL 逆 type 転 水 車 Pump as Turbine クロスフロー 水 車 Cross Flow Centrifugal ポンプ 逆 転 Pump 水 車 as Turbine 100kW 300kW 50kW フランシス 水 車 5000kW 1000kW 3000kW プロペラ 水 車 1 0.01 0.1 1 10 100 流 Flow 量 ( m3/sec) (m 3 /s) Francis Tubular Siphon Propeller
Selection Chart for Low Head Turbine Semi Kaplan Bulb Turbine Siphon Propeller S Type Tubular
Comparison of Turbine Performances
Flow Duration Curve Flow Hydrograph : A period of 20~25 years records is required for planning the Run-of River type Plant. The most suitable design flow for run-of-river type power station is around 95 day flow. 95day The area below the curve shows the energy of hydro potential in the river Flow Duration Curve : A curve of flow versus the percentage of time. This curve is usually the most convenient form for turbine size selection.
An Example of Flow Duration Curves Flow (m 3 /s) Days
Design Flow for Conventional Turbine too small design flow (Run-of of-river type Mini Hydro Plant) too large design flow 365days operation available operating duration shorter Bypass flow from turbine increased (cannot operate in dry season) Bypass flow decreased Annual Energy Output(kWh) = 365(days) x 24(hrs) x Pg(kW) Unit Electricity Cost( /kwh) = Total Construction Cost Annual Energy Output
Flow Duration Curve vs Unit Efficiency ηmax In case of maximum efficiency (ηmax) being selected on extreme partial flow point, the runner cavitation at maximum flow shall be carefully studied.
The cost of the Mini Hydro Plant is site specific and may vary widely from scheme to scheme The cost of the Mini Hydro Plant is site specific and varies greatly depending on the remoteness of the site and physical features of its major components, namely, civil works (including waterways), generating equipment(turbine, generator, control, protection) and electrical transmission/distribution lines. While the cost of generating equipment in the powerhouse is almost a linear function of kw/h 0.5, the cost of civil works further depend upon the gradient of the waterway(intake to powerhouse). Similarly, the cost of electrical line further depends upon the energy density of the load centers. Therefore, the coat of Mini Hydro Plant installations can vary widely from scheme to scheme. The share of initial civil works component cost may vary from a mere 20% for a relatively high gradient waterway profile and low cost construction to 60% for a relatively low gradient and expensive construction. Therefore, the percentage share of one component on the total initial investment cost would depend upon its own as well as other component s construction feature.
Budget for Turbine, Generator and Associated Equipment (Source) Engineering Manual for Mini Hydro Generation System (NEF, Japan)
Economic Evaluation of H.E.P. Construction Cost/kW Construction Cost/kWh Construction Cost/kWh Construction Cost/kW The most economical Turbine Design Flow Turbine Design Flow(m 3 /s)
Sizing of Micro Hydro Unit Utilization of the same two or more units Minimum Flow The most of Micro Hydro Unit is not provided the flow control device like conventional hydro turbine. Select the Micro Hydro Unit from Maker Selection Chart by using available minimum flow. The provision of the same two or more units can produce more electric power in plenty of water flow season. Combination of different units The power generation will be increased by applying the additional different Micro Hydro Unit, if the surplus flow is smaller than the minimum flow. Minimum Flow
Intake Screen 250mm mmφ Mixed Flow type Micro Hydro Generating Unit Siphon Breaker DC Motor Vacuum Pump Net Head (m) 7.0~11.8 Micro Hydro Generating Unit Flow (m 3 /s) 0.17~0.22 Speed (rpm) 1,000 Generator Output(kW) 7.3~15.8 HWL Siphon Intake Pipe 4.0~8.8 0.13~0.19 750 3.2~9.7 Gross Head : 5~8m Bypass Valve 250Dia. SZ Pump as Turbine Generator Generator Control Panel Features: -The pump for low lift & agriculture usage are applied as turbine. -The generator for diesel engine can be connected to this turbine. -No need to provide the large hole on reservoir side wall. TWL
Micro Hydro Selection Chart
Features Suitable for High Head & Small Flow Good partial flow efficiency Pelton Turbine Height between Nozzle center & Tailwater cannot use as Net Head Net Head of Pelton Turbine Construction of Horizontal shaft, Single Jet Pelton
Turbine Runner
Head Tank h 1 H=H G -h 1 -h H H st H : Net Head 2 Jets Operation 2 Jets Operation H G H st : Static Head H G : Gross Head h l : Head Losses between penstock inlet and Tail Race h turbine inlet h : Distance between jets center and tailrace Gross, Static & Net Head for Pelton Turbine
Turbine Efficiency Comparison Relative Turbine Efficiency (%) Pelton 2 Jets Operation Pelton 1 Jet Operation Francis Turbine Turbine Flow Ratio (%) Turbine Design Flow
Pelton Turbine Ratings : Net Head : 788(m) Speed : 3,575(min -1 ) Flow : 0.0917(m 3 /s) Output : 619(kW)
Cross Flow Turbine Features Suitable for Medium Head & Small Flow Good partial flow efficiency compared with Francis Turbine Height between Runner & Tailwater cannot use as Net Head Light duty equipment Capacity : 50~around 1,000kW Head : 5~100m Flow : 0.1~10(m 3 /s)
Cross Flow Turbine Construction Flow Water Flow in the Casing 1: Runner 2,3: Guide Vane 4: Casing 5: Baffle Plate 6: Inlet Pipe 7: Cover 8: Draft Tube 9: Runner Shaft 10: Bearing Box 11: Shaft Seal 12: Air Valve 13: Silencer 14, 15: Guide Vane Arm 16: Handhole Under Guide vanes fully closed
Net Head for Cross Flow Turbine Head Tank h 1 H=H G -h 1 -h H : Net Head H st : Static Head H G : Gross Head H Hst H G h l : Head Losses between penstock inlet and turbine inlet h : Distance between jets center and tailrace Tail Race h
Outview of Cross Flow Turbine Turbine Runner
Cross Flow Turbine Efficiency Comparison Relative Turbine Efficiency (%) Maximum efficiency is less than Francis but efficiency at low flow is better. Guide vane opening Francis Turbine Guide vane opening Full Guide vane opening Turbine Flow Ratio (%)
Francis Turbine Features Widely used for large, medium and small-scale hydro plant Wide Applicable Head Range : 15~300(m) Flow : 0.4~20(m 3 /s) for Horizontal shaft Capacity : 200~10,000kW for Horizontal shaft Robust Construction Long Life Equipment
Net Head for Reaction Turbines Head Tank v 2 2 H=H G -h 1-2g -h h 1 H : Net Head H st : Static Head H G : Gross Head h l : Head Losses between penstock inlet and turbine inlet h : Distance between draft tube outlet and tailrace level V 2 : Outlet velocity of draft tube H V 2 2 2g Tailrace Hst H 0 h
Francis Turbine Efficiency Comparison Relative Turbine Efficiency (%) (Note)Relative Turbine Efficiency 100(%) means the peak efficiency of Ns=around 175m-kW where the highest maximum efficiency is obtained in all Francis turbines Turbine Flow Ratio (%) Turbine Design Flow
Outview of Mini Hydro Francis Turbine
1,050kW Francis Turbine Generator Max. Output : 1,050(kW) Features Net Head : 65.8(m) Oil-less, Water-less and Brush-less type Turbine Generator Max. Flow : 2.0(m 3 /s) Air-cooled type Turbine Generator Rated Speed : 1,000(min -1 ) Electric motor driven GV actuator
450KVA Francis Turbine Generator Net Head : 24.6m Flow : 2.23m 3 /s Speed : 600min -1 Turbine Output : 460kW Features : Oil-less, Water-less & Brush-less equipment Power upped by Scrap & Built
Large scale Francis Turbine Vertical shaft Francis Type of turbine : Vertical shaft, Single flow, Francis Net head : 108.2~135.7(m) Maximum flow : 250(m 3 /s) Maximum output : 121(MW) Rated speed : 250(min -1 ) Suction head : -8.2(m)
Propeller Turbine Features Suitable for Low Head : 2~20m for Mini/Micro Hydro Turbine 6~60m for Medium & Large Hydro Turbine Good partial flow efficiency for Kaplan type turbine
Kaplan Turbine Runner Guide vane apparatus Vertical shaft Kaplan Turbine Turbine Runner
Propeller Turbine Efficiency Comparison Fixed Runner, Fixed Guide vanes Relative Turbine Efficiency (%) Full Kaplan Variable Runner Blades,Fixed Guide vanes Fixed Runner Blades, Variable Guide vanes Turbine Flow Ratio (%) Turbine Design Flow
Turbine Applicable Operating Range Turbine type Flow Range(Q) Head Range(H) Pelton (0.1~0.2) x Q d Q Q d (0.85~0.9) x Hmax H Hmax Francis (0.3~0.4) x Q d Q Q d 0.6 x Hmax H Hmax Cross Flow (0.2~0.4) x Q d Q Q d 0.7 x Hmax H Hmax Kaplan & Propeller Turbines :
S type Tubular (Horizontal shaft propeller) Capacity : 50~3,000kW Head : 3~18m Flow : 1.5~20m 3 /s Suitable for low head and large discharge plant
Outview of S type Tubular Turbine
Large Scale Kaplan Turbine Kaplan Turbine Type of turbine: Vertical shaft, semi spiral, Kaplan Net Head : 12.3~14.5(m) Maximum Flow : 270.0(m 3 /s) Maximum Output : 34(MW) Rated Speed : 90(min -1 )
Bulb Turbine 2,400kW Bulb Turbine Casing
Generator for Mini/Micro Hydro Plant Generator type Advantages Disadvantages Synchronous Generator Induction Generator available of isolated operation adjustable of voltage,frequency & power factor simple construction simple control system need for complex control and insulated rotor winding to be get excitation from the grid parallel operation only Items to be considered at Generator Selection : In case of isolated operation, Synchronous generator shall be applied. Rotor & bearing shall be designed to withstand the overspeed at load rejection Estimated Overspeed : Pelton & Francis : approx. 1.8~2.0 times of rated speed Propeller : approx. 2.5~3.0 times of rated speed
Construction of Synchronous & Induction Generator Synchronous Generator Induction Generator
Function Governor to regulate the speed at unit start-up and stop to keep the frequency(speed) of generator under unit isolated operation to control the unit output under unit parallel operation with grid Mechanical Governor for Mini Hydro Plant
Governor for Micro Hydro Plant (Electronic Load Control Governor) to be applied for Micro Hydro Turbine without Flow Control Device Advantages Low cost, No water hammer, Simplified turbine
An Example of Mini Hydro Power Plant in Japan
Mini Hydro Power Station -Utilizing Utilizing Compensation Flow to the River General Arrangement (Sectional View)
Mini Hydro Power Station -Utilizing Compensation Flow to the River General Arrangement (Plan View)
Submersible type Turbine Generator General Arrangement
Submersible Turbine Generator Net Head : 8.06~9.12(m) Generator Output : 236(kW) Design Flow : 3.73(m 3 /s) Voltage : 440(V) Sectional View of Submersible Turbine Generator
Mini Hydro Power Station -Utilizing Compensation Flow to the River 464kW Semi-Kaplan Turbine Max. Output : 464(kW) Net Head : 7.91~9.32(m) Max. Flow : 7.63(m 3 /s) Min. Flow : 3.73(m 3 /s)
Comparison between Turbine & Pump Performance Turbine Performance Pump Performance Semi Kaplan type Turbine Submersible Pump/Turbine
S type Full Kaplan Turbine Generator (All Actuators are operated by Electric Motor) Turbine Type : S type Tubular Turbine with Speed Increaser Turbine Speed Increaser Net Head : 5.45(m) Turbine Flow : 15.0(m 3 /s) Turbine Output : 694(kW) Generator Turbine Speed : 200(rpm) Electric Motor Driven Actuator for Runner Blades Generator Type : Synchronous Generator with AVR Capacity : 670(KVA) Speed : 900(rpm)
540kW Mini Hydro Power Station provided in Irrigation Facilities Bird Eye View of Power Station Intake Facility Sectional View Plane View
135kW Turbine Generator Inlet Valve Turbine Generator Side View of Unit Turbine : Type : Fixed Blades & Guide vanes, Propeller Turbine Ratings : 7.36m x 2.6m 3 /s x 429(min -1 ) x 165kW Generator : Type : Horizontal shaft, Induction Generator Ratings : 170kW x 420V x 429(min -1 ) Unit No. : 4 View from Draft Tube
Turbine Generator Construction
Siphon type Propeller Turbine Generator Specification: Siphon Detector Head race Max WL Siphon Intake Min. WL Generator Runner Blade Controller Tubular Turbine Draft Tube Tailrace Turbine : Type : Vertical Shaft, Tubular type Semi Kaplan Turbine Net Head : 3.7~1.3(m) Max. Flow : 3.7(m 3 /s) Max. Output : 112(kW) Generator : Type : Permanent Magnet type Synchronous Generator Capacity : 110(KVA) Voltage : 400(V) Speed : variable
Sectional View of Hydro Power Station Sectional View Intake Gate Generator Intake Gate (Emergency Closing Gate) Machine Hatch Water Head Tank for Cooling Water Stop Log Control Panels Cooling System for Bearing Water Channel Water Intake Screen Casing Draft Tube Tailrace River Intake Screen Discharge Valves Turbine Generator Drainage Pit Existing Headrace New Headrace Power Station Tailrace
Ratings Turbine Type Kaplan type Tubular Turbine(Bulb type) Max. Output 2,520kW Rated Speed 138(min -1 ) Design Flow 13.09~43.0(m 3 /s) Net Head 5.46~7.0(m) Generator Type 3 Phase Synchronous Generator Capacity 2,520(KVA) Commissioning March, 2003 Features: - Guide Vanes & Runner Blades are operated by Electric Motor Driven Actuators. No Oil Hydraulic Pressure System is provided. - Closed circuit water cooling system is applied for bearing oil cooling system.
Construction of Turbine Generator 1 Draft Tube 6 Generator Stator 11 Guide Vanes 16 Turbine Bearing 2 Machine Hatch 7 Generator Rotor 12 Discharge Ring 17 Shaft Mechanical Seal 3 Outer Casing 8 Exciter 13 Runner Blades 18 Guide vane Servomotor 4 Inner Casing 9 Generator Bearing 14 Runner Boss 19 Generator Pedestal 5 Stay Vanes 10 Runner Servomotor 15 Runner Cone 20 Water-Water Cooler for Bearing
Gate Ring Electric Motor driven Guide Vane Servomotors
Electric Motor Driven Servomotor (Guide vane Servomotor) Construction of Electric Motor Driven Servomotor Schematic Diagram of Electric Motor Driven Servomotor/Governor
Electric Motor Driven Blade Actuator(1/2) On running ; Actuator Speed n=generator Speed N At Runner Blade opening changing; - Actuator Speed n>generator Speed N : Runner Opening Increased - Actuator Speed n<generator Speed N : Runner Opening Decreased
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