Feasibility Study Report. India Muerta Small Hydro Power Plant. In Uruguay

Transcription

1 Feasibility Study Report of India Muerta Small Hydro Power Plant In Uruguay Prepared by International Center on Small Hydro Power (ICSHP) for United Nations Industrial Development Organization (UNIDO) January, 2013

2 TABLE OF CONTENTS Chapter 1 Executive Summary... 1 Chapter 2 Basic Information General Description of Uruguay Brief Introduction of India Muerta Reservoir Project Project Owner and Background Local Social and Economic Conditions of the Project Transportation and Communication Grid and Power Supply Electricity Tariff and Water Price Prices of Main Marterials... 5 Chapter 3 Hydrology General Information of the Drainage Area Climate Precipitation Runoff Flood Sediment Chapter 4 Engineering Geology Chapter 5 Project Tasks and Installation Scale Project Tasks Installation Scale Determination of Characteristic Water Level Runoff Regulation and Determination of Generating Flow Determination of Installation Capacity I

3 5.2.4 Calculation of Multi-year Mean Output Chapter 6 Project Layout and Main Civil Works Project Layout Layout and Situation of the Dam Layout of the Hydropower Station System Design of Main Civil Works Diversion System Structures Powerhouse Draft Tube and Tailrace Channel Step-up Switchyard Irrigation Bypass Valve System Chapter 7 Hydraulic Machinery, Electrical Equipment & Metal Structures Hydraulic Machinery Selection of Hydraulic Turbines Selection of Generators Basic Parameters of Units Selection of Regulating Device Excitation System Selection of Lifting Device in Powerhouse Water Supply and Drainage System Irrigation Water Supply System Electrical Engineering Primary Electrics Secondary Electrics DC System II

4 7.2.4 Lighting System Dispatch and Communication System Metal Structure Trash Rack and Intake Gate Penstock Irrigation Bypass Valve and Bypass Pipe Chapter 8 Construction Organization and Design Construction Condition Project Condition Construction of the Main Structures Diversion System Powerhouse and Tailrace Transportation for Construction External Transportation Field Transportation Construction Facilities Mixing System Machinery Factory Comprehensive Processing Factory Electricity, Water and Wind Supply for Construction Construction Layout Field Layout Scheme Waste Slag Scheme Estimation of Main Temporary Construction Quantity and Construction Occupation Total Construction Schedule Preparation Period of Project III

5 8.6.2 Construction Period of Main Structures Completion Period of Project Chapter 9 Engineering Management Management Institution Establishment of Management Institution Authorization of Management Staff Management Range Engineering Management and Operation Operation of Reservoir Engineering Management Facilities Chapter 10 Investment Estimation Budget Preparation Project Description Main References References for Budget Quota Unit Rates Prices of Equipment To consider the difference in project budget between China and Uruguay, the following costs are not included into the budget estimation of the project Compensation Fee for Construction Land Tenure: Budget list General Budget List Project Cost List Chapter 11 Economic Evaluation Costs Calculation (Only the actual expenses directly spent on project construction included) IV

6 Project investment Annual Running Expense Income Calculation Financial Evaluation Conclusion Annex Quote of Mechanical and electric equipment V

7 Chapter 1 Executive Summary Entrusted by UNIDO, ICSHP experts paid a preliminary on-site visit to the India Muerta Reservoir Project which the local government intends to renovate it into a small hydropower station in Uruguay. And after the consultation trip the Proposal of the India Muerta Hydro Power Project in Uruguay has been submitted. In April 2012 UNIDO entrusted ICSHP to conduct the survey and design for the India Muerta Reservoir Project, Uruguay. Three SHP experts were dispatched by ICSHP to pay the second visit to the site to make a field survey for the project from July The tasks included topographic survey on dam site and powerhouse area, general geographic investigation, survey on flood discharge at reservoir area, survey on irrigation area, average annual rainfall data collection, irrigation data collection, owner s background investigation, main materials rates, traffic situation and highroads investigation,grid and tariff investigation. To acquire the above data and information is essentially required for engineering design of the project. It is much appreciated that during the stay in Uruguay, the ICSHP technical experts got strong support and active cooperation from Mr. Alberto, general manager and Mr. Rodrigo, engineer, of the project owner company Comisaco s.a., as well as the considerate concerns from the officials of UNIDO Uruguay Office and Ministry of Industry, Energy and Mines of Uruguay. 1

8 Chapter 2 Basic Information 2.1 General Description of Uruguay The Oriental Republic of Uruguay (República Oriental del Uruguay) is a country in the southeastern part of South America. It lies on the east bank of the La Plata River and the Uruguay River, neighboring Brazil in north, Argentina in west and the Atlantic Ocean in southeast. It has a land area of 176,215 square kilometers. An approximately 90% of the population is of European descent and 8% is other races. Catholicism is the main religion of the country, and Spanish is the official language. The capital city is Montevideo. It declared independence on 25 August The country has a flat landform in most of the area with highly developed agriculture and animal husbandry. Uruguay's climate is relatively mild. It has natural scenes and stable social environment. 2.2 Brief Introduction of India Muerta Reservoir Project The India Muerta Reservoir, which is located on the India Muerta River, Rocha Province, Uruguay, is to serve the local agriculture irrigation, with annual irrigation capacity of 8000 hectares. The reservoir area, dam and irrigation area are showed in Figure 1- layout. Figure 1 The India Muerta Reservoir Area The dam of India Muerta Reservoir has 12 m of height, 52.2m of altitude of dike top and 3221m length of axe of dam and 65,700 hectares of catchment area. The India Muerta Reservoir has 47m of normal storage level, 3530 hectares of corresponding water area and million m 3 of effective storage capacity. The dam type and characteristics of the reservoir are showed in Figure

9 Figure 2 Characteristic Curve of the India Muerta Reservoir Figure 3 Layout of the India Muerta Reservoir Dam Figure 4 Cross Section of the India Muerta Reservoir Dam The irrigation system contains the east canal and the west canal (fronting the downstream, the left is the east and the right is the west). The east canal has 68km of length, with 10.5 m 3 /s of design flow discharge, and it is 40.2m in altitude of top and 37.2m in altitude of bottom; the west canal has 45km of length, with 10.5m 3 /s of design flow discharge, with 39m in altitude of top and 36m in altitude of bottom. Please see the canal data from Table 1. 3

10 Table 1 Irrigation Canal Data Length(km) Discharge(m 3 /s) Main canal (the east canal) Main canal (the west canal) Secondary canal (east-1) Secondary canal (Los Ajos) Secondary canal (Laguna de los Ajos) Secondary canal (Alferez) Secondary canal (Talita) Irrigation canal (India Muerta) Irrigation canal (Talita) Secondary canal (el Sauce) Secondary canal (Lascano) Auxiliary canal 436 variable Generally speaking, the India Muerta Reservoir reaches its normal high level every August, then continuously discharging the water within 200 days for irrigation until March of next year, with probably water releasing in every September to October. 2.3 Project Owner and Background The owner of the India Muerta Reservoir Project is Comisaco s. a.. This is a private company located in Lascano City, 35km away from the Reservoir. It is invested by two of the biggest grain processing enterprises in Uruguay. The grains procured in the area irrigated by the India Muerta Reservoir are all purchased by the two grain processing companies who invest in Comisaco s. a.. The Comisaco s. a. s profit through irrigation equals 1000kg grains of each hectare of the land. This will be paid by the processing companies when purchasing the grains. 2.4 Local Social and Economic Conditions of the Project The India Muerta Reservoir Project is surrounded with pastures with highly developed animal husbandry. The farmers have an annual per capita income of USD. The Lascano City, the nearest city to the Reservoir has 7000 residents. The city has good infrastructures and civil facilities, convenient transportation, prosperous economy. The distance to the capital city Montevideo is 250km. 2.5 Transportation and Communication The distance from the capital city Montevideo to Lascano City is 250km with four- 4

11 lane highroad. It is 35km between Lascano city to the India Muerta Reservoir, with 30km long double-lane (8m in width) highroad with asphalt pavement and 5km double-lane highroad (6m in width) with sand and gravel pavement. This provides a better traffic condition and good transport network. The country has a developed communication network. Strong phones signals are covered in the India Muerta Reservoir area. This provides a better communication condition. 2.6 Grid and Power Supply The national grid in Uruguay belongs to the state electric power corporation UTE. The investigation along the way tells that Uruguay has a good electric power supply grid with high level facilities and technology. The grid has a voltage of 15/0.4(0.2) kv, and supplied with both three-phase and single phase currents. The 15kV grid extends to the place 500m far away from the India Muerta Reservoir 2.7 Electricity Tariff and Water Price In Uruguay the electricity tariff is decided in a wide range. It is learnt that the household electricity tariff is 0.3 USD/kWh. The irrigation water is provided by the India Muerta Reservoir at a rate of 1000kg/ton grains, equivalent to 240 USD. 2.8 Prices of Main Marterials Cement: USD/ton Steel: 2300 USD/ton Timber: 32 UDS/m 3 Sand: 35 UDS/m 3 Rock: 45 UDS/m 3 5

12 Chapter 3 Hydrology 3.1 General Information of the Drainage Area The India Muera River rises in the northwest of Rocha Province, Uruguay, 60km away from the coast of the Atlantic Ocean. The river is oriented from an area of hilly grassland, flowing through the gently sloping grassland in middle stream and reaching the flat grassland in downstream. The whole drainage area has well-grown vegetation and mostly are grazing land with a low density of herds. 3.2 Climate Uruguay has a subtropical humid climate in the Southern Hemisphere. The winter temperature is 2-14 from April to September while the summer temperature is from October to March. Although it is influenced by the dry west wind from the Andes, owing to its location near the ocean, warm ocean current also flows through it, the country has a plenty of rainfall. The annual precipitation increases from 950mm in the south up to the 1250mm in the north. 3.3 Precipitation The project owner company Comisa s. a. provides us with the monthly rainfall data of 28 years from (see Table 2). The maximum year precipitation is 1567mm (in 2003) and the minimum is 852mm (in 2008). The average annual precipitation is m. According to the analysis on the long-term precipitation data, this area has a plenty of rainfall which ranges evenly among the years but unevenly among the months in one year. For example: in the high flow year as 2002 it ranges 671mm in the highest flow month to the 45mm in the lowest flow month; in the normal flow year as 1993 it ranges from 180mm in the highest month to the 13mm in the lowest month; in the low flow year as 2008 it is from 160mm to the 2mm. In irrigation period of the Reservoir from October to March (summer) the average annual precipitation is 602.4mm and the average monthly precipitation is 100.4mm. In the storage period of the Reservoir from April to September (winter) the average annual precipitation is 608.7mm and the average monthly precipitation is 101.5mm. Thus it proves that the rainfall in this drainage area distribute half in the irrigation period and the other half in the storage period of the Reservoir. 6

13 Due to a lack of discharge data, the average annual precipitation in this drainage area can be calculated through frequency analysis so as to achieve a basis evaluation on the flow variation of the Reservoir. The calculation results are listed in Table 3 and Figure 5. Table 2 Monthly Precipitation of the India Muerta Reservoir from Table 3 Distribution of Annual Precipitation in the Example Years (mm) Month Total High Flow Year (P=25%) (example year 2010) Normal Flow Year (P=50%) (example year 2005) Low Flow Year (P=75%) (example year 1987) Runoff There is no hydrological station in the India Muerta drainage area so the related hydrological data was not obtained. In an experience-oriented view, the runoff amount at the cross section of the dam site can be calculated according to the runoff coefficient determined by the annual precipitation data in this drainage area. However, the India Muerta Dan has been put into operation for 30 years, and the operation schedule of the Reservoir that the irrigation is adjusted according to the growth period 7

14 requirement of the grains in this irrigation area could not be changed. Therefore the calculation of the runoff amount at the cross section of the dam site is not necessary. On the other hand, a document of Daily Records of the Irrigation Level & Flow of the India Muerta Reservoir from January 2008 to June 2012 (See part of Table 4) provided by the project owner company Comisaco s.a. is very helpful for the calculation of the average annual electricity output. Figure 5 Precipitation Frequency Curve from Table 4 Irrigation Level & Flow, Sluice Gate Position and Overflow Amount DAN OF INDIA MUERTA Level at Sluice Gate and Position of Gate Month Jan. Year 2008 Q 1 +Q 2 Sluice Gate Position m 3 /s Date Water Level of GATES (CMS.) Spillway Volume Overflow Discharge Irrigation Amount Irrigation Discharge Reservoir Left Right ,089,747 1,085,820 1,082,866 1,254,073 1,248,

15 ,242,493 1,236,662 1,231,978 1,227,276 1,094,014 1,089,774 1,085,517 1,081,243 1,076,952 1,071,565 1,066,150 1,060,708 1,055,237 1,049,738 1,045,318 1,040,880 1,158,197 1,151,939 1,145,648 1,139,322 1,162,763 1,156,197 1,177,988 1,248,146 1,242,314 1,236,

16 3.5 Flood There is in the absence of actual peak flow or flood calculation data in the basin. As the terrain in the basin is flat and vegetation coverage is good, therefore, the formation of flood peak is slow and the waveform variation rate of flood peak is small. Thorough the regulation by India Muerta Reservoir, the flood peak value is decreased greatly when the flood peak flows out of the spillway of reservoir. According to spillway flow log of year (see irrigation water level and flow logs of India Muerta reservoir) provided by the owner, we can see that the maximum flood during these 4 years happened on 9 th, February, 2010 with peak flow of m 3 /s. According to owner s introduction, the flood disaster also happened at the downstream of reservoir. Led by Mr. Alberto, we investigated the downstream submerged area. Because the terrain of submerged area is also flat, it still looks like an extension of swamp. The India Muerta Reservoir has operated for 30 years. The powerhouse of station is planned to be equipped between the stilling pool (at the exit of irrigation pipe) and diversion section of the east and west trunk canals. It is about 3 km away from the spillway of dam and will not be influenced by the flood discharge. 3.6 Sediment There is in the absence of sediment data. According to our on-site investigation, the vegetation coverage of reservoir area is good, the gradient of river is small, and the water quality of reservoir is clear with a small amount of sand silting on the reservoir bank. Therefore, we can reach the conclusion that the India Muerta River has a small amount of sediment content, including a small amount of suspended load but basically without any bed load. 10

17 Chapter 4 Engineering Geology There is in the absence of relevant data. According to our preliminary on-site investigation, the soil around the dam site is sandy and the rocks under the grassland on the left side are exposed to the air. According to the visual inspection, these rocks are basalts. According to owner s introduction, the dam foundation has been excavated to the bed rocks. The thickness of the overburden layer is 3-8 meters without fracture. 11

18 Chapter 5 Project Tasks and Installation Scale 5.1 Project Tasks The main task of India Muerta Reservoir is to provide water for agricultural irrigation. According to owner s introduction, at primary stage of construction, it planned to install one turbine-generator unit and construct a surge tank at the exit of the irrigation pipe for power generation. However, because of technical problems, this plan was not accomplished. The project tasks: On the premise that the irrigation function of India Muerta Reservoir should be ensured, it plans to generate electricity through utilizing the drop between reservoir normal water level and water level at the exit of irrigation pipe, and potential water power in irrigation flow. It plans to install one turbine-generator unit on proper place at the exit of each of two irrigation pipes. The tail water of turbinegenerator unit will connect to diversion section of east and west trunk canals, which ensures that the tail water will flow into east and west trunk canals respectively according to irrigation design requirements. The distribution of discharge will be controlled by the throttle valve nearby the diversion section of east and west trunk canals. 5.2 Installation Scale Determination of Characteristic Water Level 1.The normal high level of reservoir (Z j ) is 47 meters. According to design and operation situation, when the normal water level is higher than 47 m, it begins to overflow the right bank of the spillway. Therefore, the normal water level of reservoir will be determined as 47 m. 2. The highest operating water level of reservoir (Z g ) is 48 meters. According to the Operation Log of Reservoir, the overflow discharge of reservoir reached the maximum record m 3 /s on 9 th Feb. 2010, meanwhile the corresponding water level of reservoir was m. Therefore, the highest operating water level of reservoir should be 48 m. 3.The generation dead water level of reservoir is 42.5 meters. As the bottom elevation of irrigation pipes is m and the pipe diameter is 1.75 m, the top elevation of irrigation pipes will be =40.76 m. As the submerged depth will be considered as 0.5 m, the generation dead level will be =41.76 m. To be 12

19 considered good for operation, a generation dead level of 42.5 m has been determined. 4.The design tail water level of downstream (Z w ) is 40.0 meters. The turbinegenerator unit will be equipped near the stilling pool at the exit of irrigation pipes. The crest and bottom elevation of tailrace canal correspond respectively to the crest elevation (40.2 m) and bottom elevation (37.2 m) of the east trunk canal. Therefore, the design tail water level of downstream (Z w ) will be determined as 40.0 m, taking into account 0.2 m of super elevation. As the bottom elevation of tailrace canal is determined, the design tail water level will be relied on cross section design of tailrace canal. 5.The lowest tail water level of downstream (Z d ) is 39.5 meters. 1) As with small pressure fluctuation of tail water pipe, the operation stability of unit will raise, therefore, the fluctuating depth of downstream tail water level should be small. 2) The minimum requirement of submerged depth at exit of tail water pipe should be considered. Therefore, this characteristic value is also controlled by cross section design of tailrace canal Runoff Regulation and Determination of Generating Flow 1.Runoff Regulation: India Muerta Reservoir has a total storage capacity of 127 million m 3, which is classified as large scale reservoir. According to catchment area of 670 km 2, data of multi-year rainfall and runoff coefficient determined by the vegetation condition in the basin, the storage capacity coefficient of India Muerta reservoir is calculated more than 15%, so it has annual regulation capacity. However, because of following reasons: 1) the adequate of runoff data; 2) the water supply for irrigation wholly follows growth period of crops in irrigation area; 3) limit of pipe diameter, the runoff regulation calculation and the change of operation method are both impossible. Therefore, the function of runoff is only to regulate its operation method during overflow period based on original operation method, in order to achieve the aim that the flood within 21 m3/s can be utilized to generate electricity. 2.Determination of Generating Flow(Q): According to operation log of India Muerta Reservoir, the reservoir has 4 operation modes: 1) discharge of irrigation water (Q g )> 0, and discharge of overflow (Q y ) = 0; 2) discharge of irrigation water (Q g )>0, and discharge of overflow (Q y ) > 0; 3) discharge of irrigation water (Q g ) = 0, and discharge of overflow (Q y ) > 0; 4) discharge of irrigation water (Q g ) = 0, and discharge of overflow (Q y ) = 0. In our design, the discharge of irrigation water (Q g ) and discharge of overflow (Q y ) will both be utilized to generate electricity, so Q = Q g + Q y. As the maximum design flow of irrigation pipe is 21 m 3 /s, therefore, Q 21 13

20 m 3 /s. When Q g + Q y >21 m 3 /s, the redundant flow will be discharged through spillway. As installation of turbine-generator units should meet the requirement of maximum irrigation flow, therefore, the design generating flow is determined as 21 m 3 /s (Q j = 21 m 3 /s) Determination of Installation Capacity 1. Output Calculation of Station: As the diameter of irrigation pipe is fixed, and the generation should meet the requirements of irrigation. Therefore, the rule mentioned above the discharge of irrigation water (Q g ) and discharge of overflow (Q y ) will both be utilized to generate electricity, so Q = Q g + Q y, and Q 21 m 3 /s should be adopted to calculate the output of station. According to irrigation log of reservoir ( ) and output formula: N = 9.81 H Q η In this formula: N Output, kw; H Water Head, m; H = Drop between upstream water level and downstream water level. For convenience of calculation, we adopt design tail water level (Z w = 40.0 m) as the downstream water level. η Comprehensive Efficiency of Turbine-Generator Unit. We set it as 0.8 m. Therefore, the results of output calculation are as follows: Daily Output Hydrograph of Year Output(kW) Days 14

21 Figure 6 Daily Output Hydrograph of Year 2008 (N-T) Daily Output Hydrograph of Year Output(kW) Days Figure 7 Daily Output Hydrograph of Year 2009 (N-T) Daily Output Hydrograph of Year Output(kW) Days Figure 8 Daily Output Hydrograph of Year 2010 (N-T) 15

22 Daily Output Hydrograph of Year Output(kW) Days Figure 9 Daily Output Hydrograph of Year 2011 (N-T) The maximum output N max = 1250 kw, which happened on 9 th, February, Determination of Installed Capacity: 1) Water Head of Station: Maximum water head H max = = 8.5 m; Minimum water head H min = = 2.5 m; Arithmetical average water head H P =( )/ 2 = 5.5 m; Taking into account characteristics of reservoir storage capacity and operation, we set design water head H j = 6.5 m. 2) Design flow Q j : taking into account requirement of maximum irrigation flow, we set Q j = 21 m 3 /s. 3) Design output of station N j = (kw). 4) Determination of installed capacity of station: taking into account requirements of maximum irrigation flow and operation condition at high water level during overflow period, we set installation coefficient as 1.2, therefore the installed capacity of station N zj = 1.2 N j = (kw). Taking into account the standardization of unit capacity, the installed capacity of station is determined as 1260 kw, which agrees with the maximum output mentioned in above calculation. 3. Selection of Unit Number and Type 16

23 As taking into account following points: 1) to match the number of water supply pipes; 2) the reliability and flexibility of operation and 3) changes of operating conditions, we recommend equipping 2 turbine-generator units with rated output of 630 kw each for this station. The Kaplan turbine and Shaft Extension Tubular turbine can both be used for this station. Compared from the application scope of spectrum and operation experience of similar stations, we recommend the Shaft Extension Tubular turbine to be equipped for this station. The advantages of Shaft Extension Tubular turbine: 1) less hydraulic loss and high efficiency; 2) convenience for installation and maintenance; and 3) less excavation of powerhouse Calculation of Multi-year Mean Output 1. Calculation of Annual Output of Year : based on above calculation of daily output, we can use formula E = N T (T = 24 hours) (kwh) to calculate out the daily energy output and obtain the annual output by accumulating all the daily energy output. The results of calculation are as follows: Daily Output Cumulative Hydrograph of Year Cumulative Output(kWh) Days Figure 10 Daily Output Cumulative Hydrograph of Year

24 Daily Output Cumulative Hydrograph of Year Cumulative Output(kWh) Days Figure 11 Daily Output Cumulative Hydrograph of Year Daily Output Cumulative Hydrograph of Year 2010 Cultive Output(kWh) Days Figure 12 Daily Output Cumulative Hydrograph of Year

25 Daily Output Cumulative Hydrograph of Cumulative Output(kWh) Days Figure 13 Daily Output Cumulative Hydrograph of Year Calculation of Multi-year Mean Output: according to calculation results of annual output of year , we can reach the conclusion that the annual output is basically proportional to annual rainfall of this project. According to this conclusion, we can calculate out the multi-year mean output form year 1988 to year 2011: : mean rainfall of mm, and mean output of kwh : mean rainfall of mm, and mean output of kwh. 3. Annual Utilization Hours of the Station: T n = / (h). 19

26 Chapter 6 Project Layout and Main Civil Works 6.1 Project Layout Layout and Situation of the Dam The India Muerta Reservoir dam consists of a Main dam, dam abutment, auxiliary dam, spillway, intake, pipeline, stilling basin, distributary point, the heads of the east and west canal, the east and west throttle valve, etc. The dam body and the right dam abutment are arranged in a straight line, while the left dam abutment is at a folded angle inwards of 30 to the dam axis. The auxiliary dam is located at the right dam abutment at a folded angle inwards of 50 to the dam axis. The tower structure at intake is on the left side of the dam, and the water supply pipeline is located inside the dam and connected to the stilling basin downstream. The stilling basin is connected to the apron and extends 20 m to the distributary point and then separates into the east and west canal. The spillway, at a width of 200 m, is built in another small valley approximately 1.5 km far away from the auxiliary dam (Figure 3) Layout of the Hydropower Station System The powerhouse is arranged at the existing stilling base and apron, with two 630 kw shaft-extension type tubular turbines installed inside. The tail channel is connected to the distributary point, and the throttle valves of the east and west canal need to be shifted about 10 m down river. The switchyard is in the left side of the powerhouse, with two 800 kwa step-up transformers installed. At the upstream side of the powerhouse, a Φ1000mm hole is opened on outside for each penstock before both are extended into the powerhouse. Also the gate valves are fixed to connect the by-pass tube for the reason that when the hydraulic turbine and generator units are under maintenance, irrigation water could be supplied through the by-pass tube to ensure a constant irrigation system. 6.2 Design of Main Civil Works With reference to China s national Classification and Design Standards for Water Resources and Hydroelectric Projects" (SL217-87), the India Muerta Reservoir Project is classified as a Grade-3 project of middle size, the main hydraulic structures as Grade-3 buildings, other minor buildings as Grade-4 buildings, whilst temporary 20

27 structures such as the construction cofferdam are classified as Grade-5 buildings. The structures for the generating system of this project are built behind the dam instead of being located... due to the area s more stable geology. As a consequence, according to the regulation SL the buildings can be regarded as "minor" buildings (meaning of secondary importance) compared to the dam. They are therefore designed following up requirements as Grade 4 buildings Diversion System Structures 1. Intake. The intake of the irrigation pipelines is in the dam slope on the upstream side of the dam body, connected to the highroad on the top of the dam through a working bridge. A vertical trashrack is put at intake to connect the two intakes. The two intakes are both equipped with two screw driven sluice gates, of which one is a working gate and the other an alternate one. Required by the owner, the intake will not be changed and only a steal trashrack is added. 2. Existing Penstocks (water supply pipeline). Two concrete pipelines are set after intake, each with an internal diameter of 1.75 m, a wall thickness of 0.3 m, elevation in the centre of 40m and a total length of 80 m. (See figure 14). The two pipelines join up into one at the stilling base behind the dam, before going through the tower surge tank and turning off at outtake(see Figure 15). The outtake is 2.5m in diameter of and at an elevation in the centre of m (See Figure 16). Figure 14 Vertical and horizontal cross section of the Water supply pipeline (penstocks) 21

28 Figure15 Plan of the two water supply pipelines (penstocks) joining in one, Tower surge tank, and outtake Figure16 Partial cross section of the water supply pipeline (penstocks) from the outtake to the stilling base 22

29 The extension and rehabilitation of the penstock: At the point which the existing pipelines joins in one (see Figure 15), remove the rear section and construct an anchorage block to support the pipelines. The pipeline extends along the flow and makes a horizontal 30 turn outward. When the central line of the pipe reaches the point of 6 m away from the units, it goes forward and makes a horizontal 30 turn inward. Thus the two pipelines are both parallel to the flow, with 6 m distance between each other. It is required to construct the anchorage blocks to support the turns of the pipes. The sizes of the anchorage blocks are decided through stability calculation Powerhouse It is proposed to equip this plant with two shaft-extension type tubular turbines of model GD008-WZ-140, with total installed capacity of 1260 kw. According to the parameters and size of the units provided by the manufacturers and with reference to the plants of a similar scale and equipped with the units of the same type, the size of the main powerhouse (length width height) is designed as m (the height of the powerhouse refers to the elevation difference between ceiling and floor). The installation room, 6.0 m in length and at the same height as the highroad approaching the powerhouse, is built on the left side of the powerhouse to store the two units. The two units are installed 6.0 m apart without a division line. The units are installed at an elevation of m on level with the centre of the existing outtake. The elevation at the bottom of generators is m, and the floor of installation room is 41.0 m. For easy installation and maintenance, a 15 ton electrical singlegirder overhead travelling crane is equipped, having a span of 11.5 m and an elevation of m on its track top. The auxiliary powerhouse is located down the left side of the main one and links to the installation room via the gate. It contains the panels and boards of the protection, control and direct current systems for the units in addition to duty desks for the operators. The auxiliary powerhouse has the following dimensions: m - length width height), and the ground elevation is 41.0 m, while the ceiling elevation is 46.5m. The powerhouse is constructed in a framed structure, with the roof assembled with a prefabricated light steelwork Draft Tube and Tailrace Channel Draft tube is supplied together with the units by the equipment manufacturer. It 23

30 consists of a bend, straight, expansion and rectangular level section. The concrete lining around the draft tube requires a minimum thickness of 0.7 m. The draft tube is connected to an adverse slope of 1:3 (height width) at the end of the level section, and before going through a 6.12 m transition section and finally connects to the tailrace channel. The tailrace channel is at an elevation of m from the bottom, with the cross section of rectangle, which has 12.0 m of width and 43 m. The channel dike is built with sandy soil and concrete lined with a minimum thickness of 0.25 m. The tailrace channel is about 68 m in length from the transition section to the sluice gate distributing the flow to the east and west canal Step-up Switchyard The step-up switchyard is located on the left side of the powerhouse and in close proximity to the outer wall of the auxiliary powerhouse, which size should be m (length width) and 41.0m of the bottom. Two S11-800KVA/15/0.4kv transformers and one 15kV transmission line are installed in the switchyard whilst an iron fence at a height of 1.7 m is built around it Irrigation Bypass Valve System As it is essential that irrigation is guaranteed during the unit maintenance period, aφ 1500 orifice is opened on the each of the two anchorage blocks of the water supply pipeline (penstocks) before they enter the powerhouse (2 Φ1500). A valve of Φ 1500 is fixed to connect aφ1500 bypass pipe and then to the tailrace channel. Under normal conditions, the valve is closed; and if the units are under maintenance during the irrigation period, the bypass valve will be opened to draw the water through the bypass pipe for irrigation use. 24

31 Chapter 7 Hydraulic Machinery, Electrical Equipment & Metal Structures 7.1 Hydraulic Machinery Selection of Hydraulic Turbines Selection of Turbines. Having made careful comparison and reference to the similar cases, we recommend the shaft-extension type tubular turbines for this plant. Only two models of the shaft-extension type tubular turbines, namely the Model GD008- WZ-140 and the Model GD006-WZ-160 could satisfy the operating conditions as attributed by the head and flow. Parameters of the above two models are listed in Table 5. Each model has its advantages and disadvantages. The Model GD008-WZ-140 is smaller in size, has a lower price and relatively less civil works would be involved. In addition it has a high rated output with a certain overload capacity but lower turbine efficiency. The Model GD006-WZ-160 is more efficient due to its larger size, consequently its price is higher and the amount of civil works would increase. Furthermore, the second model has a lower rated output and a limited overload capacity. After comparison of the above two models, the former model (GD006-WZ- 140) is considered the most appropriate. Table 5 Comparison of Turbine Parameters Turbine Model GD008-WZ-140 GD006-WZ-160 Rated Output KW Runner Diameter cm Max. Head m Min. Head m Rated Head m Rated Discharge Q 3 /S Rated Rotational Speed r/min Rated Efficiency η% Optimum Efficiency η% Suction Height m 0.5 (2.3- /900) Selection of Generators The three-phase synchronous AC generator, Model SF-J550-20/1430, utilized in the plant is directly connected to the hydraulic turbine. The generator adopts an open 25

32 structure for ventilation and cooling. It works at a synchronous rotating speed of 300 r / min, with machine base number of 1430 mm and a power factor of Basic Parameters of Units 1. Turbine Type: GD008-WZ-140 Max. Head: 8.0m Design Head: 6.5m Min. Head: 2.5m Rated Discharge: 10.5m3/s Rated Output: 589KW Rated Rotational Speed: 300r/min Runner Diameter: 140cm Number of Turbines Installed: 2 Turbines 2. Generator Type: SF-J550-20/1430 Rated Capacity: 550KW Rated Voltage: 400V Rated Rotating Speed: 300r/min Rated Efficiency: 50Hz Power Factor: 0.8 Excitation System: Silicon controlled Static Excitation Cooling Method: Open structure for ventilation and cooling Selection of Regulating Device To realize the automatic control, YWT Step Programmable Computer-based Governor is adopted. The governor works at a capacity of 1000kg.m and with Operating Oil Pressure of 4.0Mpa. The main regulating parameters are: Proportion Coefficient KP 0~20 Integral Coefficient KI 0~10(1/s) Differential Coefficient KD 0~5(s) Permanent Speed Droop bp 0~10% man-made frequency dead-band f 0~±1% Given Frequency Range f G 0~50Hz Given Power Range P G 0~100% 26

33 Power AC~220V±10% 500w Excitation System Since faults are generally more likely to be found in generator excitation systems, an excitation system of high-level redundancy with PLC double computer, full-bridge and in double DC side switching mode, is selected. The excitation model is SWJL Selection of Lifting Device in Powerhouse For easy installation and maintenance, an electrical single-girder overhead travelling crane is fixed in the powerhouse. According to the maximum weight of the object as well as the dimension of the main powerhouse, it is decided to choose a span of 11.5m for the crane with a weight limit of 15t Water Supply and Drainage System 1. Technical water supply system: The water is flowing by itself through the penstock. A pressurization pump is added before the main valve of the water supply, in case the water pressure is insufficient when the units operates at the lowest water level. In a situation, where the water pressure is lower than the required technical water supply pressure, the pump will start and add pressure to realize a normal water supply. 2. Seepage Water Drainage System in Powerhouse: As the normal level of the tailrace 40m is higher than the bottom elevation of the generator, a seepage pumping shaft for leakage water is set in the right corner of the main powerhouse, in an elevation of 36.5m of the shaft bottom and dimension of m (length width). Also two centrifugal seepage water pumps, Model 2BA-6B are installed over the seepage pumping shaft (in the same elevation of the bottom of the generator). The main parameters of the centrifugal pump are: Type 2BA-6B Discharge 25m 3 /s(6.9l/s) Total Lift 16.3m Rotating Speed 2900r/min Shaft Power 1.73KW Electrical Motor Y90L-2 2.2KW Efficiency 94% Allowed Suction Head(HS) 6.6m 27

34 Runner Diameter Weight (Pump and bed) 132mm 42/28Kg 3. Maintenance Water Drainage System in Powerhouse: For the shaft-extension type tubular turbines, less inspection and maintenance inside the draft tube is required, therefore, it is not necessary to apply a fixed maintenance water drainage system. The drainage measures could be taken temporarily when the draft tube needs to be drained. 4. Drainage System in Powerhouse Site: The station is built after the dam, having its tail water directly flowing into the irrigation channel. It is far away from the flood discharge river, and the elevation of the powerhouse is on the same level of the normal tailrace at downstream, so the powerhouse has remote possibility to be submerged or flooded by back flow. Therefore, no fixed drainage system will be set in the powerhouse Irrigation Water Supply System 1. Irrigation water supply system under normal operating condition of the units: The rated discharge of the two units is decided in accordance to the maximum water quantity supplied for irrigation. Under normal operating condition of the units, the tail water of the station goes through the tailrace channel to the east and west canal, with sufficient water quantity to satisfy the irrigation demands. 2. Irrigation water supply system when the water head is lower than the maximum head of the unit: If the water level of the reservoir is too low to reach the maximum head of the unit, the turbine & generator units must be stopped. On such occasions, the by-pass tube system will be used to transfer the water for irrigation. There are two options for the by-pass valve: Z941-6,DN=1000. They are both manually operated. 3. Irrigation water supply system during repair period of the unit: When one unit breaks down and requires examination, but the other unit works as normal, only one by-pass valve for the broken unit is needed to make up for the lost water supply. Table 6 Main Devices of Hydraulic Machinery No. Name Model Unit Number 1 Turbine GD008-WZ-140 set 2 N=589KW 2 Generator SF-J550-20/1430 set 2 N=550KW 0.4KV 3 Governor YWT-1000 set 2 28

35 A=1000kg.m PG=4.0Mpa 4 Excitation System SWJL-65 set 2 5 Overhead Travelling CXTS-10 set 1 Crane G=15t 6 Seepage Water 2BA-6B set 2 Drainage System H=16.3m Q=25m3/h 7 By-pass Valve Z941-6 DN=1000 set Electrical Engineering Primary Electrics 1.The Connection of Power Station and Electrical System According to distribution grid standard of Usinas y Trasmisiones Electricas (UTE), the power station will be accessed by the electrical system with a voltage line of 15 kv. The access point is at the end of distribution grid, which is in the village 500 m far away from the power station. The generator voltage of the power station is 0.4 kv, which will be boosted to 15 kv by a step-up transformer and transmitted to the access point through a 15kV one-circuit overhead transmission line. The type of transmission line is a LGJ Main Electrical Connection According to the requirements of design principle, two connection schemes are proposed for comparison. One of them will be recommended for current stage design. Scheme 1: The two units will connect with the main transformer. The enlarged unit connection is adopted at the generator voltage side (0.4 kv). The air circuit breaker and isolation switch will be equipped at the generator outlet whilst the main transformer low voltage side will be equipped with an isolation switch only. The main transformer line unit connection is adopted at the transformer high voltage side (15 kv), which will be equipped with one outdoor high voltage vacuum circuit breaker and one group of outdoor isolation switches. Scheme 2: Each unit will connect to main transformer. The single bus sectional connection is adopted at the generator voltage side (0.4 kv). The air circuit breaker and isolation switch will be equipped at the generator outlet, and the main transformer low voltage side will be equipped with an isolation switch only. The single bus connection is adopted at the main transformer high voltage side (15 kv), which will then be equipped with an outdoor high voltage vacuum circuit breaker and a group of outdoor isolation switches. The line side will not be equipped with a circuit breaker 29

36 and isolation switch. Comparison of the two schemes: Scheme 1 has a simpler connection and represents a lower level of investment, however it lacks operational flexibility and reliability. If the main transformer were to break down, the operation of both units would be stopped. This will influence not only the benefits from power generation, but also the water supply for normal irrigation. Scheme 2 has a more complicated connection and thus a higher investment and as a result it has more operational flexibility and reliability. Scheme 2 includes the following operational modes: 1) At normal conditions, the isolation switches of the bus at the generator voltage side will open, so that the No. 1 and 2 generators will connect to the No. 1 and 2 main transformers respectively to form two generator-transformer units for generation; 2) If one of the main transformers breaks down, the operation of fault generator-transformer unit will stop leaving the other non-faulty generator-transformer unit operating; 3) If one of the main transformers of one generator-transformer unit and one generator of another generator-transformer unit breaks down, both generator-transformer units will stop. After closing isolation switches of the bus at the generator voltage side, the non-faulty generator will connect the non-fault main transformer to form a new generatortransformer unit for generation. According to the features of the power station, irrigation will combine generation, but irrigation is more important than generation, and therefore scheme 2 is recommended for current stage design. 3.Selection of Main Electrical Equipment 1) Selection of Main Transformer The selection will be in accordance with rated output and voltage. The type of main transformer is S11-M-800/15 with the following parameters: Type S11-M-800/15 Rated Output 800KVA Voltage 16.5±2 2.5%/0.4kv Connection Group Ynyn0 No-load Loss P 0 980W Load Loss P F 7500W No-load Current I% 0.8 Weight of Oil 500Kg Weight of Equipment 1640Kg Total Weight 2750Kg Dimension (Length Width Height) ) Selection of Outdoor Vacuum Circuit Breaker 30

37 The selection will be in accordance with rated voltage and current, and be checked by rated short-circuit breaking current. The type of circuit breaker is ZW 32-15/630 with the following parameters: Type ZW 32-15/630 Rated Voltage 15KV Rated Current 630A Rated Frequency 50Hz Rated Short-circuit Breaking Current 20KA Rated Peak Withstand Current 50KA Life times Operational Voltage AC220V or DC220V 110V 3) Selection of Outdoor High Voltage Isolation Switch The selection will be in accordance with rated voltage and current. The type of isolation switch is GW 4-15/200 with the following parameters: Type GW 4-15/200 Rated Voltage 15KV Rated Current 200A Rated Frequency 50Hz Maximum Peak Current 15KA 5s Thermal Stable Current 5KA Number of Poles 3 Life times 4) Selection of 0.4 kv Air Circuit Breaker (Equipped in Control Panel of Generator) The selection will be in accordance with rated voltage and current. The type of circuit breaker is TDKW (tripolar drawer type, microprocessor) with the following parameters: Type TDKW Rated Voltage 0.4KV Rated Current 1250A Rated Short-circuit Breaking Current 80KA 5) Selection of Low Voltage Distribution Panel: The selection will be in accordance with the features of the panel or cabinet. The control panel at the generator outlet will select GGD type and the distribution panel for station power supply will select GCK or GCS type. 6) Selection of Power Cable from Generator Outlet to Control Panel: According to voltage, laying mode, current-carrying capacity, the low voltage power cable of VV- 1KV type will be selected. 7) Selection of Power Cable from Control Panel to main transformer: According to 31