Penstock works - British Hydropower Association

Report
The Replanting of Lochaber Hydro Power Station
by Andrew Thick
1
Topics to be covered today
• Scheme modelling;
• Operating capability of Lochaber;
• Turbine selection;
• Penstock works.
2
Schematic of the Lochaber Scheme
Spill
Spill
Gravity
Inflows
Gravity
Inflows
Surge
Chamber
Spill
tunnel
tunnel
tunnel
Penstocks
Spey
reservoir
Loch
Laggan &
reservoir
Loch
Treig
Powerhouse
Tailrace
Loch
Linnhe
3
Schematic of the Lochaber Scheme
Spill
Spill
Gravity
Inflows
Gravity
Inflows
Surge
Chamber
Spill
tunnel
tunnel
tunnel
Penstocks
Spey
reservoir
Loch
Laggan &
reservoir
Loch
Treig
Powerhouse
Tailrace
Loch
Linnhe
4
Spey Dam
5
Schematic of the Lochaber Scheme
Spill
Spill
Gravity
Inflows
Gravity
Inflows
Surge
Chamber
Spill
tunnel
tunnel
tunnel
Penstocks
Spey
reservoir
Loch
Laggan &
reservoir
Loch
Treig
Powerhouse
Tailrace
Loch
Linnhe
6
Schematic of the Lochaber Scheme
Spill
Spill
Gravity
Inflows
Gravity
Inflows
Surge
Chamber
Spill
tunnel
tunnel
tunnel
Penstocks
Spey
reservoir
Loch
Laggan &
reservoir
Loch
Treig
Powerhouse
Tailrace
Loch
Linnhe
7
Laggan Dam
8
Schematic of the Lochaber Scheme
Spill
Spill
Gravity
Inflows
Gravity
Inflows
Surge
Chamber
Spill
tunnel
tunnel
tunnel
Penstocks
Spey
reservoir
Loch
Laggan &
reservoir
Loch
Treig
Powerhouse
Tailrace
Loch
Linnhe
9
Schematic of the Lochaber Scheme
Spill
Spill
Gravity
Inflows
Gravity
Inflows
Surge
Chamber
Spill
tunnel
tunnel
tunnel
Penstocks
Spey
reservoir
Loch
Laggan &
reservoir
Loch
Treig
Powerhouse
Tailrace
Loch
Linnhe
10
Schematic of the Lochaber Scheme
Spill
Spill
Gravity
Inflows
Gravity
Inflows
Surge
Chamber
Spill
tunnel
tunnel
tunnel
Penstocks
Spey
reservoir
Loch
Laggan &
reservoir
Loch
Treig
Powerhouse
Tailrace
Loch
Linnhe
11
Loch Treig and Dam
12
Schematic of the Lochaber Scheme
Spill
Spill
Gravity
Inflows
Gravity
Inflows
Surge
Chamber
Spill
tunnel
tunnel
tunnel
Penstocks
Spey
reservoir
Loch
Laggan &
reservoir
Loch
Treig
Powerhouse
Tailrace
Loch
Linnhe
13
Schematic of the Lochaber Scheme
Spill
Spill
Gravity
Inflows
Gravity
Inflows
Surge
Chamber
Spill
tunnel
tunnel
tunnel
Penstocks
Spey
reservoir
Loch
Laggan &
reservoir
Loch
Treig
Powerhouse
Tailrace
Loch
Linnhe
14
Schematic of the Lochaber Scheme
Spill
Spill
Gravity
Inflows
Gravity
Inflows
Surge
Chamber
Spill
tunnel
tunnel
tunnel
Penstocks
Spey
reservoir
Loch
Laggan &
reservoir
Loch
Treig
Powerhouse
Tailrace
Loch
Linnhe
15
Penstocks, Powerhouse and Smelter
16
Simplified Lochaber Scheme Model
Gravity Intake Flows are combined with
Reservoir Inflows
Qintakes
QLin
QLspill
QTin
QLin
QLin
Qintakes
QTspill
QTunnel
QP/H
QTin
Laggan
Treig
17
Energy Modelling Results
Trial
1
2
3
4
5
6
7
Installed Cap. (MW)
65
80
60
70
80
90
100
Overall Efficiency (%)
75
87
87
87
87
87
87
Headloss Coeff. (k)
Operating rule
0.021
0.0172 0.0172 0.0172 0.0172 0.0172 0.0172
Ext
Ext
Max E
Max E
Max E
Max E
Max E
2,034
1,794
4,160
1,709
1,227
1,074
801
Treig Spill (mcm)
154
121
857
201
54
10
7
Ave. Energy (GWh/yr)
467
569
523
574
581
583
580
Laggan Spill (mcm)
18
Scheme Operating Capability Diagram
Average Operation
90.7 % Q
9.3 % Q
No Gravity Inflows
100 % Q
0%Q
Max. Gravity Inflows
0%Q
100 % Q
19
Operating Capability in terms of Loch Treig Level
Note:
90.7% of water from Loch Treig
9.3% of water from gravity intakes
20
Scheme Operating Capability Diagram
Average Operation
90.7 % Q
9.3 % Q
No Gravity Inflows
100 % Q
0%Q
Max. Gravity Inflows
0%Q
100 % Q
21
Operating Capability in terms of Surge Shaft Water Level
Note:
90.7% of water from Loch Treig
9.3% of water from gravity intakes
Penstock Limitation
22
Scheme Operating Capability Diagram
Average Operation
90.7 % Q
9.3 % Q
No Gravity Inflows
100 % Q
0%Q
Max. Gravity Inflows
0%Q
100 % Q
23
Operating Capability in terms of Surge Shaft Water Level
Note:
All water from Loch Treig
24
Scheme Operating Capability Diagram
Average Operation
90.7 % Q
9.3 % Q
No Gravity Inflows
100 % Q
0%Q
Max. Gravity Inflows
0%Q
100 % Q
25
Operating Capability in terms of Surge Shaft Water Level
Note:
All water from gravity intakes
26
Scheme Operating Capability Diagram
Average Operation
90.7 % Q
9.3 % Q
No Gravity Inflows
100 % Q
0%Q
Max. Gravity Inflows
0%Q
100 % Q
27
Example Operation exceeding Penstock Pressure Rise Limit
28
Turbine Selection
The steps towards to turbine selection were:
• Analysis of historical data of scheme
operation
• The number of generating units was
selected – 5
• Analysis of operating data from scheme
model
• Performance data from tendering suppliers
was fed into the scheme model
29
Scheme Operation
Frequency Plot
30
Turbine Selection
The steps towards to turbine selection were:
• Analysis of historical data of scheme
operation
• The number of generating units was
selected – 5
• Analysis of operating data from scheme
model
• Performance data from tendering suppliers
was fed into the scheme model
31
32
Turbine Selection
The steps towards to turbine selection were:
• Analysis of historical data of scheme
operation
• The number of generating units was
selected – 5
• Analysis of operating data from scheme
model
• Performance data from tendering suppliers
was fed into the scheme model
33
34
Turbine Selection
The steps towards to turbine selection were:
• Analysis of historical data of scheme
operation
• The number of generating units was
selected – 5
• Analysis of operating data from scheme
model
• Performance data from tendering suppliers
was fed into the scheme model
35
36
Penstock works
Key aspects of the penstock works were:
• Need to undertake the works minimising shutdown
of generation.
• Existing penstock system was very complex.
• In order to maintain double isolation, the penstocks
needed to be dewatered sequentially.
• The works were complex with poor access.
• Decision with RTA to laser scan the penstock
system and create a 3-D model.
37
Multiple buspipes
Numerous Valves
Bifurcations
38
Penstock Area – difficult terrain!
39
Penstock works
Key aspects of the penstock works were:
• Need to undertake the works minimising shutdown
of generation.
• Existing penstock system was very complex.
• In order to maintain double isolation for the
penstocks needed to be dewatered sequentially.
• The works were complex with poor access.
• Decision with RTA to laser scan the penstock
system and create a 3-D model.
40
Survey Point Cloud Data
41
AutoCAD 3-D Model
42
Project Summary
• The generating plant has been replaced to give 25+ years life
extension.
• The water to wire efficiency has been improved from 75% to
90+%.
• Energy production increased from 460 GWh/yr to 600+
GWh/yr.
• The scheme’s capability is better understood and limitations
identified.
• The scheme was completed ahead of schedule and is
operating successfully with minimal disruption to Smelter
operations during construction
43
Thank you for your kind attention
Contact Details
Andrew Thick BEng CEng MIMechE
URS Infrastructure and Environment UK Limited
International House, Dover Place
Ashford
Kent TN23 1HU
United Kingdom
Tel: +44 (0) 1233 658200
[email protected]

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