The run-of-river Patrind Hydropower Project is being constructed on river Kunhar. With a capacity of 147MW (Net), the Project shall generate, on average, 632 GWh of electricity annually. Since the Project is being developed by SHPL as an IPP, the SHPL has entered into a 30 year Power Purchase Agreement with National Transmission and Dispatch Company (NTDC), Pakistan's grid system operator, for the sale of electricity generated from the Project.
The Project is located on the boundary of Azad Jammu & Kashmir (AJ&K) and District Abbottabad of Pakistan, near the city of Muzaffarabad. The majority of the Project structures, including the powerhouse, are located in the territory of AJ&K. However, the diversion tunnel, flushing tunnel and a part of the weir are located within territorial limits of District Abbottabad.
The weir side of the Project can be reached through Boi Road on right side of river Kunhar at a distance of approximately 12.3 km from Garhi Habibullah, a small town in District Mansehra. The powerhouse side of the Project is accessible from lower Chattar, Muzaffarabad where a new class 70 bridge has been constructed across river Jhelum as part of the Project.
Technical Details and Information
The plan of the Project is to divert the waters of river Kunhar through a weir, located near village Patrind, and a left bank conveyance system of headrace tunnel to the right bank of river Jhelum, near the city of Muzaffarabad, where a powerhouse is being built. The natural difference of elevation between river Kunhar and river Jhelum, along with a 43.5 meter high weir provides a gross head of 112.96 meters to set up a 147MW power project.
Major Project components envisaged under the proposed scheme include a weir structure, an upstream cofferdam and a flushing tunnel for sediments flushing, an intake structure slightly upstream of the weir leading to the headrace tunnel. The headrace tunnel passes through Lohar Gali ridge towards river Jhelum. It connects to an underground surge shaft via link tunnel and further opens into vertical pressure shaft, which connects with a horizontal pressure tunnel. The penstock divides into three manifolds conveying design discharge to a surface type powerhouse located on the right bank of the river Jhelum.
The crest elevation is 769.0 masl which is approximately 43.5m high from the river bed. There will be two radial type overflow gates (12.0m wide x 10.4m high) with flap type gates installed on them for accommodating flood water & floating debris etc. and two radial type underflow gates (7.0m wide X 11.6m high) for carrying out flushing of the rearranged sandtrap (OHDS). The weir will also accommodate a bridge having deck at elevation 769.0 masl, which will provide easy access to the local community and by providing a connection between AJ&K and Khyber Pakhtunkhwa.
The box culvert type power intake is located on the left bank of river Kunhar just upstream of the weir. One intake gate is provided having dimensions of 12.0m wide x 9.0m high. The facility is also equipped with five sets of trashracks having size of 7.0m wide x 12.0m high.
Optimal Hybrid Desander System (OHDS)/ Rearranged Sandtrap
Optimal Hybrid Desander System (OHDS)/ Rearranged Sandtrap is adopted for the project replacing the surface sandtrap. OHDS is composed of a by-pass tunnel and a modified pool. By-pass tunnel of horse shoe type having width of 7.5m and length 175.5m is provided at upstream of the upstream cofferdam to flush out the suspended sediments when the inflow is more than 200mᶟ/sec. The pond between upstream cofferdam and the weir will be used as the sandtrap for settling down particles that will crossover the cofferdam with size ranging between 0.20 to 0.50mm. This modified pond will be 80.0m wide, 20.0m high and 311.0m long. The settled particles shall be flushed out using under-sluice radial gates.
From intake section at Weir site, a circular type headrace tunnel having 7.0 m internal diameter and a length of 2,193.86m, will lead to the vertical shaft along with connection to the surge shaft via link tunnel.
Surge Shaft and Penstock
Orifice type surge tank with surge chamber is proposed at the start of vertical pressure tunnel connected via link tunnel to control the water hammering and speed rise phenomena. Surge shaft is a vertical tunnel having 12 meter diameter with height of 39 meters within the mountain. Surge Chamber is of horse shoe shape with width of 15.0m, height of 10.0m. A horizontal pressure shaft of 62.321m length and 8.5 m diameter connecting to the vertical pressure shaft of diameter 8.5m is proposed in hill mass on the right bank of river Jhelum. Horizontal pressure shaft further connects to the steel lined portion having diameter of 5.5m and length of 102.53m. The steel penstock trifurcates into branches, each having diameter of 3.2 m and length 73.24m.
A surface type powerhouse to accommodate three vertical Francis turbine units, each of 50 MW capacity, is proposed on the right bank of river Jhelum. The powerhouse site is about 8.52 km upstream of the Kunhar – Jhelum confluence. In order to counter the effect of sediments, water exposed parts are provided with HVOF coating for longer life and sustained efficiency.
A Gas Insulated Switchgear (GIS) system is proposed to be constructed on the right bank of river Jhelum. The power from the project will be evacuated through 132 kV double circuit transmission line.