Yantan Hydropower Station

1.Brief Description 

  Yantan hydropower station is located on the middle reaches of the Hongshui river, in Dahua county. It is the fifth stage in the Hongshui river cascade development. It is 83 km away from the county and 234 km from Nanning, the capital city of Guangxi. Its geographic coordinate is at 107.50E and 24.10N.

  The catchment area at the dam site is 106580km2.The annual mean rainfall is 1508mm,annual mean temperature 20.4,and annual mean discharge at the dam site 1770m3/s.The project is of grade one.The main structures are also of grade one.The 1000-year design flood discharge is 30500m3/s,the 5000-year check flood discharge 34800m3/s,The annual mean sediment transport 5080×104 tand the annual mean sediment content 0.98kg/m3.

  The reservoir normal water level is 223m, the corresponding reservoir capacity is 26.1×106m3.The limiting water level during flood season is 219 m. When individual operation during early stage, the dead reservoir water level is 204m, the regulating reservoir capacity 15.72×108 m3, the firm output 242MW, the installed capacity 1210MW, and the annual mean energy production 56.6×108kwh,with the utilization hour for the installed capacity 4678h, Besides power generation, in Yantan Hydropower Station, with the impounding reservoir capacity, the 153km of canalized waterway, 107.5km2 of reservoir water surface area and the beautiful landscape in the reservoir area, its irrigation, navigation, fishery and tourism potentials can be fully developed.


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The penstocks in construction

The pestocks in construction   Upon joint operation when upstream cascade project completed, the dead water level can be increased to 219m, firm output 622MW, annual energy production 82.68×108kwh and annual utilizing hour 6833h.When construction of the upstream cascade station completed, Yantan Station will be able to fully expand its good effect in frequency and peak regulation, and solve the energy loss problem caused by waste water due to maintenance, overhaul or major overhaul. After completion of the upstream cascade station, phase 2 project will be constructed and the capacity will be increased by 450MW.

  The project is composed of the main dam , the power house, the switch station and the ship lift. The main dam is of a concrete gravity type, consisting of the right bank dam section, power house dam section, spillway dam section, ship lift dam section and left bank dam section. It is divided into 28 blocks .The total dam crest length is 525m and the maximum dam height 110m.The flood discharge structure is located in the middle of

the river bed.There are 7 surface overflow bays,1 flooddischarge bottom outlet and 2 sluicing bottom outlet. The maximum discharge capacity is 33400m3/s. The spillway weir surface has WES standard profile,15m width for each bay, weir crest elevation 202m.The flaring gate pier equipbed with bucket for energy dissipation is used. By each bay, one radial sarvice gate is provided; by upstream side of the gate, there is a service gate slot, with 7 bays sharing one service gate.


The construction of R.C.C
  The water intake system consists of the intake, the gradual section and the penstock. Each unit has one penstock. The total length of the intake system is 93.88m.The penstocks are inclined buried in dam body. The penstock has a diameter of 10.8m, with a maximum intaking flow 567 m3/s.Trash rack, a service gate and a quick lowering emergency gate are set on the intake. The service gate is hoisted by 2×2500kN gantry cranes arranged on the dam crest. The quick lowering emergency gate is operated by a 800kN/6000kN hydraulic cylinder press.
  
  The power house is arranged behind the dam on the right bank, it consists of the main power house, erection bay, upstream auxiliary power house, downstream auxiliary power house and entrance building. The length of the power house along the unit center line is 200m,width 60m and height 72.58m.There are four Francis turbine generator units. The generator is of   Model SF302.5-80/17000 of a vertical shaft, semi-umbrella type, with rated power 302.5MW; The turbine is of  Model   HLA286-LJ-800,Max head 85m,Min head 37m,rated head 59.4m,and rated flow 580m3/s, rated power 307.1MW.In the power house, there are 2 sets of 2×300t overhead bridge cranes. Four main transformers are arranged on the platform of elevation 174m,between the dam and the power house. 

  The 500kV switch station is located on the dam slope by the right bank between the dam and the power house, for which,the construction area is 2530.5m2/s.The switch station is of in-door type, in two levels.The fully-enclosed GIS is set on the elevation of


Mounting rotator

181m,out-getting line bushings and surge arresters are arranged on elevation of 194m.2 circuits of 500KV out-going lines go through the power house to lead to the downstream transmission lines.

  The vertical ship lift is of 250t class (the upper navigation waterway, middle navigating channel in 500t class), set by left bank spillway dam section. The full length of navigation centerline is 905m.

2. Construction of the Project and the Engineering characteristics

  Yantan Hydropower Station was included in the state key project list in 1984.On march 1985,construction of the main structures was started. The river closure was done on November,1987. On March 1992, the gates were closed to start reservoir impounding and on September in that year, first unit was put into commissioning.By Jane 1995, all four units were completed and put into commissioning. The project was completed.

  The owner of Yantan Hydropower Station is GuangXi ElectricpowerBureau. The designer is GuangXi Electricpower Investigation and Design Institute. GuangXI Yantan Hydropower Project Construction Corporation was responsible


Overlook of beautiful powerhouse

for the projects construction as well as its management. The project owner responsibility system was adopted for the construction of the project. Bidding system was carried out for contract award and engineer supervision system was used to control the construction duration, the quality and the investment.


Central control room

  
  Rely on scientific advancement, by using new technologies and new processes and means, the design was optimized and the site management was strengthened, which brought about project efficiency and abundant achievements.

--during river closure ,the gap with a maximum flow rate of 6.6m/s, flow 1900m3/s,was closed in only 9hours.the river closure was done one year ahead of schedule. In 1992,the first unit was put into commissioning, which was 9 months ahead of the reasonable schedule approved by the State Planing Committee.

 —
  
--a serious of new techniques and processes have been sprung up ,they are :RCC construction technique, construction technique of large diameter penstock, press-stress anchorage cable technique, energy dissipation technique by using flaring gate pier combined with bucket, as well as technique of dismantling RCC coffer dam ,among which ,88 items were won national and provincial scientific advance awards.

  --with effective management and new techniques ,the project has made a better achievement with less investment. The projects construction cost per KW is 3389.68yuan.


Overlook of Yantan Power Station

3. The projects Beneficial Results and its Operation Management.

  The installed capacity of Yantan Hydropower Station accounts for 14.6% of the total installed capacity for the GuangXi Electric power grid, with annual power generation accounting for 32.43% of that of the grid.Yantan Hydropower Station is the first frequency/peak regulating power station in the grid.

  Since the station starts its energy production. the station instantly organized a young,shrewed and capable and high quality staff and workers ,among which, young staff below an age of 35 account for 72%,and staff with various profession title and technical specialists account for 57%. Since establishing the station, it has been operating smoothly,safely and efficiently.In1996,it was attested by the state as a super large enterprise and in 1997,for the month of June and July ,it was awarded by the State Electric Power Corporation as the civilized and standardize enterprise for safe and efficient operation and production ,which form a solid base for the station to become a first class enterprise.

  From September 1992 when the first unit starting commissioning till the end of 1999,Yantan Hydropower Station has been generating a 315×108kwh, creating a 2463.24×108 yuan of social output value ,which makes an important contribution to the GuangXI industrial and agricultural production and national economic development.

Geographic location of Yantan power station

 

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General layout of yantan project

 

Overview from downstream

 

The dam cross section along unit center line

 

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Main Characteristics of Yantan Hydropower Station

  Location   Da Hua
County,Guangxi

Spillway dam

Overflow type×number   Surface bay×7 bottom
  outlet
×1
  River   Hongshui  River Weir crest elevation   202m/176m

Hydrologic characteristics

Catchment area   106580km2 Spillway length 159.35m
Annul mean rainfall   1508mm Unit discharge 300m3/m.s
Rechecked
  Annual mean flow   1770m3/s Encrgy dissipation Flaring gate+bucket basin
  Annual mean run off   559m3/s

Gate type
(w
×h)

  Radial steel gate

  15×22.49/5×8(m)
  Design folld   p=0.1%,30500m3/s
  Check flood    p=0.02%,3480m3/s Hoist type,capacity Fixed hoist2×2800KN/2×1600KN
100-year flood    p=1%,24300m3/s

Power house

  Power house type Behind-the-dam power house

Reservoir characteristics

  Regulation   incomplete  annual regulation   Dimension of the main power house L200W60
H72.56m
  Check flood level   (0.02%)
  229.71m  rechecked
  Penstock layout Shallow buried inside the dam body
  Design flood level   (0.1%)227.37m     rechecked   Dimension of penstock section Φ10.8 
  Normal water level   223.0m   Dimension of WxH8.2x14.1m
  Dead water level   204.0m   Dimension of tailrace gate   WxH7.5x10.48(m)
  Total reservoir capacity   34.3亿m3   Intake hoist   8000/6000KN Hydraulic cylinder press
  Reservoir capacity of normal impounding   26.12亿m3   Tailrace gate hoist   1x1250KN   Hoist
  Regulating reservoir capacity   15.72亿m3

  Turbine

  Model   HLA286a-LJ-800
  Dead reservoir capacity   10.4亿m3   unitsxrated power   4台x307100KW
  Waater utilization coefficient   71.2%   Runner diameter   8m

Dam

  Type of dam   Concrete gravity dam   Rated r.p.m   75r/min
  Dam crest elevation   233m   Rated heat   59.4m
  Max. Dam height   110m   Rated discharge   580m3/s
  Dam length   525m   Working head   Max. 68.5m
  Dam width   23.5m   Min. 37m
  Spillway dam22.5m   Turbine installed elevation   154.5m

Generator

  Model   SF302.5-80/17000

Major losses by inundation

  Inundating farmlandI   (p=505) 59498
  Setsxrated capacity   4台x302.5MW/345.7MVA     paddy field

  cultivated land

  26965
  Rated votage/power coefficient   15.75KV/0.875   32533

Transtformer

   Model   SFP7-360000/500   population of resettlement   43176
  Sets/Rated capacity   4台/360MVA   Project permanent occupied land   2547
   Rated voltage   525x2x2.5%/15.75KV Material consumption   Steel  reinforcement   11.29万吨
Switch station   Switches   closure indoor SF6 switch         gears   4.31万吨
Outgoing circuit   500KV3   circuits    Wood   3.71m3
  200KV2   circuits   Cement   60.9t
  Navigation facility   Model   Vertical ship lift   Construction progress   Generation date   19853
  Max. Design navigable vessel   Barge 250t   River closure date   198711
  Navigable water level   upstream   223/212(m)     Generation date   unit 1
                               
                                 unit2
                               
                                 unit3
                               
                                 unit4  
                                    
                                
  1992916
  Max ./Min   downstream 162.6/154.5(m)   19938
  Design yearly cargo shipping   180x104t   19946
  Distance ship reception chamber travel
Max.
Min.
  68.5m   19956
  60.4m   Main structure completion date   19956
Proiect efficiency Installed capacity   1210MW

Total cost

  41.015亿元
  Firm output   242MW

Owner

  Guangxi Electric Power  Bureau
   Annual mean generation   56.6亿kwh

Desiger

   Guangxi Electric Power Investigating Aan Design Institute
  Annual utilization hour   4678h

Owner's representative

  Guangxi Yantan Hydropower Project Construction Corporation
  Improving   166km

  Supervision

  Guangxi Water Conservency/Eletric Power  Construction  Supervision corporation
Construction features of main structures   Open cut earth work   98.13m3
  Open cut rock work   427.59 m3

Main construction units

  Guangxi Hydropower Constructin Bureau
  Earth/Rock filling   76.49m3 Ge Zhouba Hydropower Construction Bureau
  Concrete   283.94m3 Ge Zhouba Hydropower Construction Bureau
  Steel reinforcement   38137t

Turbine manufacturer

  Harbin Eourth Bureau of China Water Conservency/Hydropower Construction
  Metal structure   22598t

Transformer manufacturer

Xian Transformer Factory
  Curtain grouting   5.17m     
  consolidating grouting   9.09m    

 

     

 

"20%" height="2">    consolidating grouting   9.09m