• 1.0             BACKGROUND
    Tehri PSP comprising of four reversible pump turbine units of 250 MW each, involves construction of an Underground Machine Hall on the left bank of river Bhagirathi.  The main feature of the Project is the large variation of about 90 m between the maximum and minimum head, under which the reversible units shall operate. The operation of Tehri PSP is based on the concept of recycling of water discharged between upper reservoir to lower reservoir. The Tehri Dam reservoir shall function as the upper reservoir and Koteshwar reservoir as the lower balancing reservoir. On completion, additional generating capacity of 1000 MW, peaking power, will be added to the Northern Region (annual generation of 1268 million units).   
    For pumping operation of reversible units during off-peak hours, the energy requirement will be of the order of 1712 MU limited to maximum of 1000 MW during off-peak hours. With the construction of Tehri PSP, Tehri Hydro power Complex shall function as a major peaking station having an installed capacity of 2400 MW.
    2.0             PROJECT APPROVAL
    Govt. of India approved the execution of Pumped Storage Plant (4X250 MW) in July-2006, at a cost of Rs.1657.60 cr. including IDC of Rs. 81.64 cr. at Dec.’05 price level with debt equity ratio of 70:30.
    3.0            REVISED COST ESTIMATE
    CCEA has approved Revised Cost Estimate (RCE) of the Project amounting to Rs 2978.86 Cr including IDC of Rs. 405.04 Cr at Apr-10 PL in Nov’11 with scheduled completion of the Project by Feb, 2016.
    i.         Upstream Reservoir           : Tehri Dam Reservoir (Already commissioned)
    ii.        Downstream Reservoir      :  Koteshwar Dam Reservoir (Already commissioned)
    iii        Head Water Levels
                   Maximum               :  830 m
                   Minimum               :  740 m
    iv.       Head Race Tunnels            :  Two nos concrete lined HRTs (HRT-3 & HRT-4)
                                                         Dia 8.5 M, Length HRT-3: 932m, HRT–4 :1060m already constructed 
    v.       Upstream Surge Shaft
         Location                            :   End of HRT
         Number                             :   2 composed of two horizontal galleries, linked with a vertical shaft.
         Width of galleries            :    approx. 8 m
         Height of galleries           :    approx. 8 m
         Length of galleries           :    approx. 105 m
         Vertical shaft diameter    :    approx. 10 m
        Penstock Bifurcation           :    at the base of surge shaft with gates
    vi.  Penstocks
         Number                              :           04
         Dia                                     :           6.0 m
         Type                                   :           Steel lined
    vii   Power House
    Type                                       :          Underground
    Size of Machine hall               :          max. width   :25.4 m + lining
             :          Height           :57.3 m
             :          Length          :201 m
    Location                                  :          Left Bank
    Rated unit capacity                 :           250 MW
    Installed capacity                    :           1000 MW
    Number of units                      :           04 nos.
    Type of Machine                      :           Variable speed vertical
                                                               Francis type reversible Turbine.
    Turbine Net Head Range          :           120.4m to 219.4 m
    Pump delivery Head Range      :           130.5m to 229.5 m
    Design Head                             :           188 m
    Rotational Speed                      :           Variable speed
    Distributor axis                        :           approx. EL 568 M
    Submergence                           :            approx. 38 m
    -Nominal value                         :           278 MVA
    -Maximum capacity                  :           306 MVA
    Rated electrical power output  :           250 M W
    at about 188m WC of rated net Head
    viii)  Downstream Surge Shaft
    Nos.                                          :          02
    Dia                                           :          approx. 18 m
    Height                                      :          approx. 101 m
    ix)   Tail Race Tunnels
    Nos                                           :           02
    Dia                                            :           9.0 m
    Length                                      :
    TRT-3                                        :         1081 m
              TRT-4                                        :         1176 m
    x)  Tail Water Levels
              Maximum                                  :          612.5 m
              Minimum (in pump mode)         :          606    m
              Minimum (in turbine mode)      :          603    m
              Average                                      :         609.5  m

Updated on : 18/02/2018