Micro Hydro System by. Andrian L

8/12/2019 Micro Hydro System by. Andrian L

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MICRO HYDRO POWERSYSTEMS

Lecture presented as part of the

module: Energy Systems 414

Adriaan Lombard21February 2013

Lecture Overview

Micro Hydro Power Systems 2

1. Hydro Power Introduction

2. Hydro Power Characteristics

2.1. Types of Hydro Power Systems

2.2. Identifying Hydro Power Resource

3. Micro Hydro Power System Design

3.1 Mec hanical Design

- Inlet

- Pipeline

- Turbines

3.2 El ectrical Design

4. Case Study Waterval Micro Hydro Power System

Introduction


Hydro Power size classification

Capacity Classification SAs Share

> 10MW Large Hydro Power

System

95%

1 1 0MW Small Hydro PowerSystem

3.7%

100 1 ,000kW Min i Hyd ro Power

System

1.2%

< 100kW Micro Hydro PowerSystem

0.1%

Hydro power systems

Very significant source of electrical energy

Represents 19% of annual global electrical energy production

Current global installed capacity: 1,010GW

South African installed capacity: 690MW

Micro Hydro Power capacity to be exploited in SA: 65MW


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Introduction


Micro Hydro Power Systems

Disadvantages

High Capital investment is usually required

Advantages

No large complicated and expensive civil works

Low Operating and Maintenance cost

Depending on technology spare parts could be easily available

Base load can be supplied continuously

Reliable systems with long life spans

Capacity factor can be >90%, compared to wind where capacity factor of 20 - 40% usually

achieved

Recent increases in electricity tariffs and those planned for future

Micro Hydro Power Systems becomes more feasible

Hydro Power Characteristics


Types of Hydro Power Systems

1. Reservoir Systems

GariepHydro Power Station 360MW

4 x 90MW Units



Types of Hydro Power Systems

1. Reservoir Systems

2. Run of River Systems

Waterval Micro Hydro Power System

1 x 9kW Unit


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Identifying Hydro Power Resources

Primary factors determining the hydro power capacity of a site:

Available gross head Difference in height between inlet and outlet

Availability of flow

P = gQHN

where:

P: Electrical Power (W)

: Combined Turbine and Generator efficiency (%)

: Density of water, usually 1,000 (kg/m3)

g: Gravitational acceleration, usually 9.81 (m /s2)

Q: Flow rate (m3/s)

HN: Net head (m)




Electrical Energy from a Hydro Power System

E = CF(P)t

where:

E: Electrical Energy for a given period (Wh)

CF: Capacity Factor of the system (%)

t: Period over which energy is generated (h)




Measuring Gross Head

1. Dumpy Level and staff

2. Global Positioning System (GPS)


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Measuring Flow

Most essential parameter in the design of a Micro Hydro Power System

Measurement period depend on flow characteristics of river

0

2

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6

8

10

12

14

1 2 3 4 5 6 7 8 9 1 0 11 12

Flow(m3/s)

Month

N.B!!! Remember the environmental reserve, i.e. minimum flow that need to remain in theriver after water is diverted from the river

- Perennial flow requires once off measurement

- Non perennial flow requires regular measurements taken at least over a full year

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1 2 3 4 5 6 7 8 9 10 1 1 1 2

Flow(m3/s)

Month




Measuring Flow Bucket and Stopwatch Method

Simple method for measuring flow in a pipe

Q = V/t

where:

V: Volume (m3)

t: Time (s)




Measuring Flow - Weir Method

Very accurate method for measuring flows in a river course

Different notch shapes, for example: Rectangular, Triangular, etc.

Requirements:

- Notch need to have a very sharp edge

- Slow moving pool of water upstream from the weir, to avoid turbulence

Q = 1.8(W -0.2h)h3/2

where:

W: Width of the notch (m)

h: Height of water above the notch (m)


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Micro Hydro Power System Design


Mechanical Design

Intake

Structure where water enters the pipeline

Prevent silt from entering the pipeline

- Pipe entrance must not be at the bottom of the weir

- Flush pipe at the bottom of the weir

Prevent vortices

- Adequate submergence

- Ensure symmetrical approaching flow conditions

Prevent floating debris from entering the pipeline

- Install trash rack



Mechanical Design

Pipeline

Dynamics of fluid in a pipeline induces pipeline losses

Head available at bottom of pipeline is less than the measured head

HN= HG-H

where:

HG: Gross measured head (m)

H: Pipeline head loss (m)

Pipeline losses determined by:

Length of pipeline

Diameter of pipeline

Material type

Flow rate

Valves, Bends, etc.



Mechanical Design

Pipeline

Larger pipe High costs Less losses More power available

Pipeline is often most-expensive part of Micro Hydro Power System

Economic analysis required to optimally size the pipeline for the design flow

120 140 160 180 200 220 2400

0.5

1

1.5

2

2.5

3x 10

5

Diameter of the pipe [mm]

Cost(ZAR)

Pipeline costCost of lost energyTotalcost

Optimum pipeline

diameter


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Mechanical Design

Pipeline

Comparison of common pipe materials

PVC Pipe Polyethylene Pipe Steel Pipe

Cost Cheapest Cheaper than steel Very Expensive

Corrosion No Corrosion No Corrosion Does Corrode

Sunlight Needs protectionagainst sunlight

Needs protectionagainst sunlight

Susceptible tosunlight

Friction Low Resistance Low Resistance Higher resistanceand increases with

corrosion

Jointing Slide into oneanother

Need to be weldedon site

Weldedor bolted onsite

Handling Easy, light and

available in fixed

lengths

Easy, light and

available in fixed

lengths or long rolls

Difficult, heavy and

available in fixed

lengths



Mechanical Design

Pipeline

Polyethylene and PVC pipes are mostly used for Micro Hydro Power Systems

Several methods exist to determine friction losses in a pipeline

Friction losses diagrams available for different types of pipes

Diagrams does not include minor losses, i.e. bend losses, valve losses, etc.



Mechanical Design

Pipeline

Determining the optimum flow for a pipe with a given diameter

Friction losses is a pipeline: H = kQ2

Power delivered by a pipeline: P = gQHN

P = gQ(HG

-H)

P = gQ(HG Q2) = gQHGgQ

3

Maximum Power:

= 0 = gHG 3gQ

2 = HG- 3H

H = 1/3HG


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Mechanical Design

Turbine

Reaction Turbines

Lowhead (0 100m);Highflow

Fully immersedin water

Torque created by pressure

difference of moving massof waterthroughthe runner

ImpulseTurbines

High head(100m +); Lowflow

Runner notimmersed in water

Torque created by force of jets

of water squirting onto bucketslocated around the

circumference of a wheel

Kaplan Turbine

Francis Turbine

TurgoWheel PeltonW heel



Mechanical Design

Turbine

Advantages

Low cost due to mass production

Easy construction and maintenance

Spare parts are widely available

Disadvantages

Lowerpeak efficiency

Lit tle turbine mode performance data is

available; pump mode performance dataneedto beusedto select a suitable pump

Alternative Option Pump as Turbine

Some standard sizes do exist, but are usually custom designed for specific application

Can operate at varying flow conditions

Designed for peak efficiency (70 90 %) at available Qand HN

Very expensive



Mechanical Design

Turbine

To determine nozzle diameter for a Pelton Wheel

Use kinetic energy equation: HN= v2/2g v =

Q = vA=

d =

where:

d: Nozzle diameter (m)

n: Number of nozzles


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Electrical Design


Stand-alone system

- With or without battery storage

- Depending on available flow, batterystorage required can be much lessthan for weather-dependent PV

systems

- Designed to meet the average dailydemand

- Other forms of regulators, such asflow control valves



Electrical Design


Stand-alone system

Grid-connected systems

- Grid used as virtual storage device

- Synchronous generators with grid

interfaces requires precise speedcontrol (very expensive)

- Asynchronous generators requires

operation beyond synchronous speed

(relative cheap option as very littleelectrical interfaces are required)



Case Study Waterval Micro Hydro Power System

Measured Gross Head with GPS: 79m

Minimum Flow: 0.03m3/s

Rectangular Weir plate design

Suggested water height above the notch: 0.05m

W =

W =

W = 1.5m

Determine maximum flow to be measured:

Consider constraint of W > 3h; h = 0.5m

Q =

Q =

Q = 0.89m3/s


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Pipeline losses

Consider:

PVC Pipeline with length of 470m and diameter of 100mm

Flow of 0.02m3/s

Conversion factors:

1foot = 0.3048m

448.8gpm = 0.02832m3/s 0.02m3/s = 317gpm

Friction loss:

4.2ft of head for every 100ft of pipe

1.28m of head for every 30.48m of pipe

H= 470m x 1.28m/30.48m

H= 19.74m




Generated Power and Energy

Net Head available:

HN = HGH

HN = 79 19.74

HN = 59.3m

Generated Power:

Assume a combined generator and turbine efficiency of 60%

P = gQHN

P = (0.6)(1000)(9.81)(0.02)(60.2)

P = 6.98kW

Generated Energy over 31 days (1 month):

Assume a Capacity Factor of 95%

E = CF(P)t

E = (0.95)(8.5)(31)(24)E = 4933kWh




Maximum power from a given pipe diameter

Consider:

PVC Pipeline with length of 470m and diameter of 100mm

Gross head of 79m

5.6ft of head for every 100ft of pipe

Optimum flow rate: 365gpm = 0.023m3/s

Maximum Head loss: H = 1/3HG = 26.3m

Net Head: 52.7m

Generated power: 7.13kW

Generated energy over a month: 5039kWh


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Peltonwheel Nozzle Diameter

Consider:

Peltonwheel having 4 Nozzles

d =

d =

d = 13.5mm




Pipeline losses

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90

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Netheadattheendofthemainpipeline(m)

Flow (l/s)

Measured Results

Calculated Results




Power generated by the Micro Hydro Power System

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GeneratedPower

(kW)

Date

Generated active power Rated capacity of the generator

Systemdowntime

Maintenance


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Energy generated by the Micro Hydro Power System

8.14

3.22 3.624.93

22.10822

9.04263

13.20834 13.06559

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5

10

15

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25

Power(kW)andEnergy(MWh)

Average Power Generated (kW) Total Energy Generated (MWh)

Generated by the

hydro system

Consumed from the

Hydro system

Consumed from

the grid

Delivered to the

grid

12 March 2009 01 October 2009




Micro Hydro Power System Capital Expenditure R135,610

Annual Operation and Maintenance Cost R350




-150

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-50

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NPVoftheMHPS(ThousandZAR)

MHPS Life Cycle (Years)

Payback Period 4.3 Years

Net Present Value R396,166

Cost of electricity 10.2c/kWh


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Thanks

[email protected]

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Micro Hydro System by. Andrian L