Elevation in Meters
220
210
200
Normal max.
H.W.EL.217.00
Flow Access deck El 181.90)
Ordinary min. power.
190 pool Ellected
180
Trashrack
Roadway deck El. 222.8
-Axis of dam
El varies
-Dam
-4 tunnel
-Gate structure
El.153.00
- Extreme min, operating
level El. 158.0°
110
11⁄2"x3.00 grout holes, 3.00 oc and as req'd.
.8.00 dia.
70
A-A
Scale O
50 Meters
1:4000
Figure 2. Profile of power development. However, because of the advantages of a single responsi- bility as against management by multiple agencies, it was decided that the construction of this particular development be undertaken under the sole administration of NPC with NWSA sharing part of the cost of the joint facilities.
Downstream of the project area, the potential area for irrigation is about 30,000 hectares. The comple- tion of this project will permit irriga- tion of about 30,000 hectares during the rainy season and about 21,000 hectares during the dry season.
The staggering increase in popula- tion coupled with the phenomenal industrial development in and around Manila demand a water sup- ply programme for domestic and industrial use. The Angat River project is a part of this programme. It will make available ultimately 500 m.g.d. to NWSA for water supply.
Use of computer
Studies in the power phase of the project including the dam and other joint facilities were handled by the National Power Corporation.
Their
consultants for the project are the associated firms of Harza Engineer- ing Company, of Chicago, and En- gineering and Development Corpora- tion of the Philippines (EDCOP), of Manila, a Filipino-American associa- tion for joint services.
Power studies were based on the operation of the Angat reservoir through the optimum installed capacity that will permit maximum utilization of the energy potential of the Angat River.
In these studies the consultants used a Bendix G-15 electronic digital computer for the large number of trial and error computations requir- ed. As programmed, the reservoir is operated without fore-knowledge of inflows, evaporation and power re- leases. A criterion elevation of maximum reservoir drawdown is first set. Then the stream flow records are run through, assuming a continu- ous constant primary power output.
70
-45°
-Original ground line
Rock surface
-É power tunnel & distributor El. 68.00
8.00 dia.
Concrete lined
power funnel
7.00 dia.
Steel lined
★ Auxiliary Units
Penstock & distri-
butor El.98.00
83.00
- Main Units
-Switchyard
El. 106.00
-Powerstation
Tailrace tunnel
Min.TW EL.68.!~ (1 unit operating)
power funnel & penstocke 170.00
facilities. Note different elevations of main and auxiliary power units
Several trials of assumed constant power output are then made and the primary power output which could be obtained and which fits the criterion maximum reservoir drawdown eleva- tion is chosen. Different criterion elevations are tested.
Installed capacity
The location of the water supply diversion works is a few river kilo- meters downstream of the proposed site, whereas the diversion of the ir- rigation system is several kilometers away. It is therefore necessary to release the water supply flow at about river bed level at the project site while the irrigation and power re- leases can be made several kilometers farther on.
In the evaluation of the optimum installed generating capacity the fol- lowing factors were considered:
a. Market demands during
early and later years of opera- tion.
the
b. Reduction in primary energy
Figure 3. Pano. ramic view of project site showing struc. tures, (1) Dam, (2) Power sta-
tion, (3) Diver-
sion tunnel
outlets, (4) Spillway, (5) Dyke
output as the water supply
requirements increase.
Consideration of these factors in- dicated a two-power plant scheme. One plant, set at an elevation, utilizes the maximum head available and an auxiliary plant uses the water supply leases. Since the water supply re- lease will be fairly constant, the au- xiliary plant will act as a base load plant.
As the water supply requirements increase, additional auxiliary units will be added to absorb the increased flow. Because of the proximity to the load centre and because hydro machinery can accept rapid changes of load smoothly and economically, the main generating units of Angat plant were designed as a peaking plant.
the
Present market demands for power and energy results in an annual load factor of about 50 to 60 per cent. As time goes on, and more steam generation is available for base loads, the output of Angat can be used for peaking at lower load factors, say 25
Far East Architect & Builder June, 1965