1st Edition

Small Hydroelectric Engineering Practice

By Bryan Leyland Copyright 2014
    254 Pages 90 B/W Illustrations
    by CRC Press

    Small Hydroelectric Engineering Practice is a comprehensive reference book covering all aspects of identifying, building, and operating hydroelectric schemes between 500 kW and 50 MW. In this range of outputs there are many options for all aspects of the scheme and it is very important that the best options are chosen.

    As small hydroelectric schemes are usually built against a limited budget it is extremely important that the concept design is optimum and every component is designed to maximise the benefi t and minimise the cost. As operating costs are often a high proportion of the income it is very important to make sure that everything is designed to be simple, reliable and long lasting.

    The book is based on the experience gained over 45 years on the overall and detailed design, construction and commissioning of more than 30 small hydropower schemes. It includes contributions from experts in the field of intakes, water diversion structures, geology, canals, painting and other aspects of hydropower development. It is intensely practical with many drawings and photographs of schemes designed and commissioned by Leyland Consultants and others. There are also sections on preparing specifi cations, tender assessment and operation and maintenance.

    The book includes a CD with spreadsheet programs for analysing aspects of small hydropower development and many arrangement drawings and detail designs for gates, penstocks, electrical systems and control systems. Typical specifi cations for generating plant are also included. The spreadsheets will be useful during the feasibility stage and the drawings will enable designers to scale the designs as needed for their own projects. Consultants, developers, designers, builders and operators of small hydroelectric schemes will find this book invaluable..

    1 Introduction
    1.1 Key features of small hydro schemes

    2 Scheme identification
    2.1 Preliminary study
    2.1.1 Cost estimates
    2.2 Feasibility study
    2.2.1 Site survey
    2.2.2 Hydrology
    2.2.3 Geology
    2.2.4 Environmental assessment
    2.2.5 Preliminary estimates
    2.2.6 Preliminary report

    3 Refining the design
    3.1 Hydrology
    3.2 Geology
    3.3 Headworks
    3.3.1 Spillway options
    3.3.2 Intakes
    3.3.3 Canal design
    3.4 Penstocks and intakes
    3.4.1 Penstock intakes
    3.4.2 Steel penstocks
    3.4.3 Wood stave penstocks
    3.4.4 Plastic and GRP penstocks
    3.5 Turbine selection
    3.5.1 Low head turbines
    3.5.2 Medium head turbines
    3.5.3 High head turbines
    3.6 Powerhouse arrangement
    3.7 Useful spreadsheets
    3.8 Preliminary financial analysis
    3.9 Outside financing
    3.9.1 “Bankable’’ feasibility study
    3.9.2 Economic and financial analysis

    4 Detailed design of intake works, canals and penstocks
    4.1 Environmental factors
    4.2 Final optimisation
    4.2.1 Technical optimisation
    4.2.2 “Alab’’ computer program
    4.2.3 “Hydrohelp’’ computer program
    4.3 Intakes at low weirs
    4.3.1 Coanda screen
    4.3.2 Streambed intake
    4.3.3 Bypassing
    4.3.4 Settling basin
    4.4 Conventional intakes
    4.4.1 Screen cleaners
    4.4.2 Intake gates
    4.4.3 Penstock filling
    4.4.4 Additional information on intakes
    4.5 Spillways
    4.5.1 Flap (fish belly) gates
    4.5.2 Obermeyer gates
    4.5.3 Radial gates
    4.6 Bypass gates
    4.7 Stoplogs and bulkheads
    4.8 Canal regulating gates
    4.9 Additional information on gates
    4.10 Canals
    4.10.1 Controlling leakage
    4.10.2 Small unlined canals
    4.10.3 Canal linings
    4.10.4 Under drainage
    4.10.5 Further information
    4.11 Penstocks and water hammer
    4.11.1 Water hammer
    4.11.2 Steel penstocks
    4.11.3 Glass reinforced plastic (GRP) penstocks
    4.11.4 HDPE and PVC penstocks
    4.12 Surface treatment and painting of steelwork

    5 Turbine selection
    5.1 Introduction
    5.2 Number of turbines
    5.3 Particulate erosion
    5.4 Kaplan and Francis turbines
    5.4.1 Guide vanes
    5.4.2 Guide vane actuation
    5.4.3 Cavitation
    5.4.4 Hydraulic stability and rough running
    5.5 Low head turbines
    5.5.1 Dimensions of Kaplan turbines
    5.5.2 Vertical Kaplan turbines
    5.5.3 Bulb turbines
    5.5.4 Pit turbines
    5.5.5 Matrix turbines
    5.5.6 Axial Kaplan turbines
    5.5.7 Open flume Kaplan turbines
    5.5.8 Very low head turbines
    5.5.9 Stoplogs and emergency isolation
    5.6 Medium head turbines
    5.6.1 Dimensions of Francis turbines
    5.6.2 Air admission
    5.6.3 Vertical Francis turbines
    5.6.4 Horizontal Francis turbines
    5.6.5 Twin horizontal Francis turbines
    5.6.6 Inlet valves
    5.6.7 Relief valves
    5.6.8 Bypass valves
    5.7 Pelton turbines
    5.7.1 Dimensions of Pelton turbines
    5.7.2 Pelton turbine arrangement
    5.7.3 Pelton turbine runners
    5.7.4 Pelton turbine options
    5.7.5 Turgo turbines
    5.8 Governing systems

    6 Generators
    6.1 Overspeed
    6.2 Synchronous generators
    6.2.1 Stators
    6.2.2 Corona
    6.2.3 Excitation systems
    6.2.4 Neutral earthing
    6.2.5 Lightning protection
    6.2.6 Generator cooling
    6.2.7 Overspeed testing
    6.2.8 Increasing generator inertia
    6.2.9 Bearings
    6.2.10 PTFE bearings
    6.2.11 Bearing cooling and monitoring
    6.2.12 Induction generators

    7 Electrical systems
    7.1 Single line diagram
    7.1.1 Transformers
    7.1.2 Station earthing
    7.1.3 Transmission
    7.2 Control
    7.2.1 Control philosophy
    7.2.2 Communications
    7.2.3 Programmable Logic Controllers
    7.2.4 Programming instructions
    7.3 Protection and instrumentation
    7.4 Synchronising

    8 Auxiliary plant
    8.1 Auxiliary AC power supplies
    8.2 DC power supplies
    8.3 Water piping
    8.4 Sump pumping

    9 Specifications and contracts
    9.1 Conditions of contract
    9.1.1 General Conditions of Contract
    9.2 Specifications for major generating plant
    9.2.1 Turbine specifications
    9.2.2 Governing systems
    9.2.3 Inlet and bypass valves
    9.2.4 Generator specifications
    9.2.5 Tender schedules
    9.2.6 Sample specifications
    9.3 Specifications for other mechanical and electrical plant
    9.4 Surface preparation and painting
    9.4.1 Background
    9.4.2 Specification requirements
    9.5 Assessment of tenders

    10 Powerhouse layout and design

    11 Construction and commissioning
    11.1 Project construction
    11.2 Commissioning

    12 Operation
    12.1 Generating plant
    12.2 Civil works
    12.3 Safety and environmental requirements

    13 Lessons from failures
    13.1 Civil engineering failures
    13.1.1 Ruahihi canal collapse
    13.1.2 Wheao canal and head-pond breach
    13.1.3 Aniwhenua canal leak
    13.1.4 Lessons from civil engineering failures
    13.2 Generating plant failures
    13.2.1 Station in the Pacific, 1990
    13.2.2 Mangahao power station
    13.2.3 Tuai power station
    13.2.4 Duffers power station

    14 Appendix 1: Useful spreadsheets and computer programs
    14.1 Hydro scheme data and cost estimates
    14.2 Intake screen head losses
    14.3 Turbine dimensions
    14.4 Cost estimates for turbines and generators
    14.5 Financial analysis

    15 Appendix 2: Financial and economic considerations
    15.1 Objectives of financial analysis
    15.2 Objectives of economic analysis
    15.3 Approach and methodology
    15.3.1 Financial evaluation
    15.3.2 Levelized Cost of Electricity
    15.3.3 Overview of economic cost benefit analysis

    16 Appendix 3: Environmental issues with two hydropower schemes
    16.1 Aniwhenua
    16.2 Onekaka

    17 Appendix 4: Making the most of hydro specifications
    17.1 Introduction
    17.2 The tenderer/contractor – an interesting species
    17.3 Specifications
    17.3.1 Performance specifications
    17.3.2 Performance specification vs prescriptive specification
    17.3.3 Getting the “A’’ team
    17.3.4 Life cycle cost analysis
    17.3.5 Is the specification tough enough?
    17.3.6 Interfacing with existing equipment
    17.3.7 Warranties
    17.3.8 Drawings
    17.3.9 Innovation vs conservatism
    17.3.10 Contract inspection
    17.3.11 Works acceptance vs Site acceptance
    17.3.12 Project schedule
    17.4 Looking beyond the specification
    17.4.1 Educating our masters
    17.4.2 Legal advice
    17.4.3 Commercial advice and instruction
    17.4.4 General Conditions of Contract
    17.4.5 Special Conditions of Contract
    17.4.6 Instructions to tenderers
    17.4.7 Partnering
    17.4.8 Tender evaluation
    17.5 Conclusion

    Subject index
    Contents of CD


    Bryan Leyland trained in New Zealand and then went overseas for nine years. During this time he worked on power projects all over the world. He returned to New Zealand in 1970 to work for Lloyd Mandeno, an outstanding hydropower engineer. In 1974 Bryan set up his own consulting firm and spent most of the next 25 years working on the overall and detailed design and commissioning of 26 small hydropower schemes totaling 250 MW and the refurbishment of 27 schemes in New Zealand and overseas. Ten of the scheme won awards as "engineering projects of outstanding technical significance". On three occasions he was involved in the repair and recommissioning of schemes that had suffered catastrophic failures. This gave him a valuable insight into the need for high quality geotechnical and civil engineering. He has also acted as a consultant to the World Bank and to the Asian Development Bank on hydropower investigations and on dam safety. He has written many papers on hydropower development, power systems and electricity markets. In 2009 he was listed by Waterpower and Dam Construction as one the 60 most influential people in the hydropower industry worldwide.

    We are a group of individual investors who are trying to tap into the small hydro space. At the moment we are working on two small hydro schemes. None of us are engineers by trade, so our strategy has been to lean heavily on a reputable consultant with experience and know-how. 
    (...) Now that the consultant is entering into the tender drawings phase, We are trying to raise many of the design considerations highlighted in this book to them. As we debate each item, I cannot help but feel extremely relieved to have bought and read this book. At the very least, even though we are led by our consultant on the designs, we are not completely blind and have working knowledge to influence the designs.
    This book has been invaluable to our business. The contents in the book are having a real life impact here in our projects.
    I highly recommend this book to anyone who is about to enter into the small hydro space.
    Alan Jenviphakul

    The book takes you from start to finish through the evolution of a hydro scheme.  From initial site assessment, hydrology, environmental, banking and finance through the many layers of detailed design work  to detailed analysis of the many types and configurations of turbine plant and generators available.
    Small Hydroelectric Engineering Practice is a thoroughly readable and enjoyable book for anyone interested in small hydro.  It is an essential book for anyone working with small hydro whether a first time developer or an experienced hydro engineer.
    Dave MacKay, Inchbonnie Hydro, New Zealand

    A book, based on tradition, full of experience and  presenting recent developments. Supported by many pictures, sketches and tables it is very comfortable to read and to learn in one run. Several pages dedicated to "learning from failures" and operational recommendations should be highlighted. A "must" in the library of a hydropower engineer!
    Prof. Dr  Bernhard Pelikan,  University of Natural Resources and Applied Life Sciences, Vienna, Austria;
    Vice President of the  European Small Hydropower Association

    This is a unique and comprehensive collection of practical engineering advice that should be essential reading for anyone involved in the development of a small to medium sized hydro-electricity resource. It covers all engineering disciplines and is based on a lifetime of involvement in this industry by the author. He should be commended for sharing both ingenious design solutions and the sometimes painful lessons learned, with others who might be fortunate enough to also be involved in harnessing these often overlooked renewable energy resources.
    Ir. W.L. Mandeno, FIPENZ, CPEng, Int.PE.
    Wellington, NZ

    By systematically explaining the different scheme components, Mr Leyland’s book caters to a range of readers and keeps the book highly readable. He explained logically about the important decisions required when developing a scheme and suggests how to avoid repeating past mistakes. This lays the foundation for the subsequent detailed discussions including job specifications, contracts for procurement and installation.
    The book also includes a CD of eight spreadsheets to assist consultants, engineers, owners and development of small hydro electricity schemes. It reads well using clear, conversational language to explain a complex subject without a lot of jargon. As a fellow hydropower enthusiast, I believe this book is an excellent reference.
    Robert Shelton, MIPENZ