WATERFALL MAINTENANCE OF THE UPPER KOTMALE EHYDROPOWER PROJECT A dissertation submitted to the Department of Electrical Engineering, University of Moratuwa in partial fulfillment of the requirement for the degree of Master of Engineering by RANAWAKA ACHCHIGE LALITH RANAWAKA. Supervised by: Dr. Lanka Udawatta Department of Electrical Engineering 2006 87262 Abstract Sri Lanka's electricity requirement has been growing at an average rate of 8-9% annually, and this trend is expected to continue in the foreseeable future [1]. To meet the high growth rate of demand tor the electricity, more power generating stations should be added to the national grid. Sri Lanka has no fossil fuel resources and therefore implementation of the Upper Kotamale Hydropower Project (UKHP) which uses our indigenous resources is more economical and important for the nation. After several social, environmental and political debates and delays, the construction works of UKHP has now been initiated and the power station will be commissioned in year 2010 [2]. At the implementation of the UKHP the river water of Kotmale Oya win be diverted at Talawakelle intake dam, into the headrace tunnel of length 12.5 km and then to the power house, which is located about 2 km upstream of existing Kotmale reservoir. The significant impact of the project is that the reduction of water flow over the Saint Clair waterfall affecting the natural beauty of the waterfall. Democratic Socialist Republic of Sri Lanka has published a gazette extraordinary making the release of water from the reservoir, to maintain the waterfall compulsory. At the construction phase of the Talawakelle reservoir, a special valve has been proposed to install near bottom outlet of the dam for the purpose of releasing water to maintain the Saint Claire water fall: The objective of this project is to develop an automated system for the optimum water release from the reservoir while meeting the conditions specified in the gazette. Special computer program has been developed to automate the operation of the valve which release water to maintain the waterfall. A graphical user interface was also developed to facilitate the communication between the operator and the controlling system. DECLARATION The work submitted in tllls dissertation is the result of my own investigation, except where otherwise stated. It has not already been accepted for any degree cyld is also not being concurrently submitted for any other degree. -~~~ R. A. L. Ranawaka .. ,. " I endorse the declaration by the candidate ' y . ·~ · .... _ v /~ Dr. Lanka Udawatta Declaration Abstract Acknowledgement List of Figures List of Tables CONTENTS List of Principal Symbols I Acronyms 1. Introduction j 1.1 Requirement of hydropower and its importance to Sri Lanka 1.2 1.3 1.4 1.5 1.6 Need of Upper Kotmale Hydropower Project Environmental studies of waterfall [mpacts on Saint Clair waterfall by UKHP The findings of the waterfall study Evaluation and mitigation in terms oflandscape 2. Requirement of a Controller 2.1 Water releasing gates from hydropower dams --~ 2.2 The structure of the valve maintaining" the waterfall 2.3 Problems to be faced in manual operations 2.4 V a1ue of water in monetary terms 2.5 Need of automatic operation of the valve 2.6 Development of the program 2.7 Key features of the software program 3. Operating Philosophy 3.1 3.2 Methodology of approach Annual discharge patterns at Talawakelle area .-.. .... v i I v VI VJJ JX X 1 4 7 8 10 ll 17 19 19 20 .... - 21 .1~ 26 ~ ,r 31 32 11 4. Controlling Philosophy 4.1 4.2 4.3 collection of data Calculations Flow chart for valve opening mode 5. Operational Modes 5.1 5.2 Modes of operations Operation of radial gates 6. Future Expansions of the Project 6.1 6.2 Forecasting water level of the reservoir Modes of operations in joint control 7. Graphical User Interface (GUI) and Results 7.1 Pages hierarchy 7.2 Main menu 7.3 Man machine interface (MMl) 7.4 Results with increasing water level j A~ "' 7.5 Results of discharge pattern with radial gates opening 7.6 Spilling of the reservoir during daytime 7. 7 Discharge of water at a dry day with low inflow 8. Conclusion References .... v 35 36 39 40 41 43 44 48 50 51 52 56 ~. 58 59 ~ 61 64 ,r"' Ill Appendix A software program Appendix B Intake dam general plan Appendix C Daily discharge record ofTalawakelle 95/96 & 96/97 Appendix D Gazette Extraordinary of Democratic Socialist Republic of Sri Lanka lOth April 2003-Mitigatory measures to be implemented by the project proponent I .. ~ " ,. ..... v , ; '. ~ · ~ / IV Acknowledgement Thanks are due first to my supervisor, Dr. Lanka Udawatta for his great support in duecting me to achieve this goaL I must appreciate his guidance, sense of humor and instructions given to me by allocating time for me in his busy time schedule. I also must thank Professor Ranjith Perera for giving me this opportunity and encouraging me to finalize the project successfully. My sincere thanks go to Professor G. T. F. Sliva for his great support extended towards me in studying Matlab programming. I extend my sincere gratitude to Project Director, Upper Kotama1e Hydropower Project, Ceylon Electricity Board and his staff for the valuable /upport given to me in coJlecting data to make my effort realistic and valuable for the nation of Sri Lanka. Lastly, 1 must thank many individuals, friends and colleagues of mine who have not been mentioned here personally in making this learning process a success. You alJ were always behind me whenever f needed to find out the solutions for the problems that r came across. "~ " ,. ...... ..; , ; ' ~ ,.~ Vl List of Figures Figure Page 1.1 Change in daily load curve over the day 2 L2 Electricity demand forecasted by CEB in year 2006 5 1.3 Water diversion to the power station 9 1.4 Discharge flow patterns for the waterfall 15 1.5 Saint Claire waterfall as seen from main road 16 1.6 Closer view of Saint Clair waterfall I 16 2. 1 Structure of radial gates 18 2.2 Man machine interface 23 2.3 Inputs and outputs of the controller 24 2.4 Water level sensor with connecting wires 24 2.5 physical layout of the system 25 2.6 Use of available data for the calculation of valve opening 27 3 1 Average monthly discharge ofTaJawakelle 95/96 32 .... ? .J.~ Average monthly discharge ofTaJawakelle 96/97 32 .... ..., Average monthJy discharge ofTalawakeHe 97/98 ..,.., .)_.) .).) 3.4 Daily discharge of April/ 1998 at Talawakelle 34 3.5 Daily discharge of August/1998 at Talawakelle.~ 34 .. 4. 1 Discharge valve characteristics 35 4.2 Flow chart of selecting normal and warning operation 39 7.1 Main Menu 50 , ....-. 7.2 Man Machine Interface (MMJ) 51 7.3 Increasing water level of a particular day 52 ..._ .... 7.4 Change in generator loading with time 53-.~ / .; 7.5 Volwne of water discharge at 10 time intervals 53 7.6 Discharge pattern for the waterfall 54 7.7 Comparison of average discharge with natura] discharge during day time 55 7.8 Increasing reservoir level with 5 hours spilling 56 7.9 Generator loading at spi lling conditions 57 Vll 7.10 Discharge rate with radial gates opening 7.11 Increasing water level with radial gates closed during day time 1.12 minimum discharge rate after radial gates are closed 7.13 Discharge volume with time at a low inflow day 7.14 Discharge rate at a low inflow day 8.1 Average daiJy discharge of a month in rainy season before and after construction ofUKHP 8.2 Average daily discharge of a month in dry season before and after construction of UK.HP .. ~ " 57 58 59 59 60 61 62 j :. .... "' , ; '. ·~ ,.~ VUl List of Tables Table Hydropower generation in Sri Lanka Load forecast as of2006 for the next 20 years 1.1 1.2 2.1 Unit value of water compared with thennaJ power plants .. ,. " j .... _ v page 4 6 22 , ; '. ·~ ,.~ lX List of Principle Symbols/ Acronyms FSL Level R mmsl n Lf MOL MWmin MWmax MWset Topoo T close UKHP Vol in Vol turbine Vol wf Vol RG Volin_night Volin hour Vol saved Vol wf min SSP X ref -Full Supply Level - Reservoir water level - Meters from mean sea level - Gate operating interval -Future reservoir water JeveJ - Minimwn Operating Level - Minimwn possible loading of the generator - Maximum possible loading of the generato} - Set value of loading of the generator -Opening time of the valve - Closing time of the valve -Upper Kotrnale Hydropower Project -Volume of water inflow to the reservoir - Volume of water outflow for power generation - Volume of water outflow for water fall -Volume of water outflow through radial gates -Volume of water inflow during the night time period -Volume of water inflow to the reservoir in hourly intervals -Volume of water saved in the previous hours - Minjmum volume of water requi~for the waterf3.ll - Safety Set Point - Valve Opening Set Point .... v , .,. ... ..._ ,r"' X