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Hanoi, January 27th 2015
Enrico WeberDEIB – Politecnico di Milano
IMRR ProjectINTEGRATED AND SUSTAINABLE WATER MANAGEMENT OF
RED-THAI BINH RIVER SYSTEM
IN A CHANGING CLIMATE
4. Reservoirs and power plants models
Main reservoirs in the Red River Basin
Strategic reservoirs:• Son La• Hoa Binh• Tuyen Quang (Na
Hang)• Thac Ba
Medium reservoirs (on Da river basin):• Lai Chau• Ban Chat, • Huoi Quang
Not
considered
Essential condition
The model simulation must be extremely fast:
1 year in few milliseconds
We got 3 10-3 sec
Features of reservoirs
• the active (or live) storage
• The stage-discharge curve of the spillways and bottom gates, the intake tower, the penstock curve
By the management point of view a reservoir is characterized by: TuyenQuang
Causal network
tS
1tE1te
1ts 1t
a 1tr t
u
1th
ts
r depends on a and e
st = storage volume at time t
at+1 = inflow volume in [t ,t+1)
et+1 = specific evaporation in [t ,t+1)
rt+1 = effective release volume in [t , t+1)
Mechanistic model
surface
Dung tích hồ [m3]
Diệ
n tíc
h m
ặt n
ướ
c hồ
[km
2 ]TuyenQuang
Mechanistic model
ttt sSeE 11 evaporation
tt sSS surface
storage
Mechanistic model
ttt sSeE 11 evaporation
tt sSS surface
1111 ttttt rEass storage
tt shh level
111 ,,, tttttt EausRrreleaseTuyenQuang
Mechanistic model
evaporation
tt sSS surface
1111 ttttt rEass storage
level
111 ,,, tttttt EausRrrelease
11111 ,,, tttttttttt eausRsSeass
Instantaneous storage-discharge relationships
• s* : storage corresponding to the spillway position
s*
spillway
s(t)
( )r t
TuyenQuang
minimum release
Instantaneous storage-discharge relationships
s*
spillway
open gates
minimum release
s(t)
( )r t
TuyenQuang
Instantaneous storage-discharge relationships
• s min , s max : bounds of the regulation range
s min s max s*
spillway
open gates
maximum release
minimum release
s(t)
( )r t
From this information the function
R t (s t
,u t ,a t+1 ,e t+1 )
is obtained.
Legal constraintsMinumum and maximum (unconstrained) release
legal constrains
Jun 15th - Jun 25th, early flood-period
Before June 25th, if Hoa Binh reservoir level is at 107 m and the Hoa Binh inflow is predicted to be higher than 4,000 m3/s, Son La reservoir is allowed to use the storage between 200 m and 205 m to prevent Hoa Binh reservoir level from exceeding 107 m.
WHAT TO DO?
Son La
st+1 = st +at+1 - Et+1 - rt+1
at+1 = inflow volume [t ,t+1)
Inflow calculation
t t +1
at+1
we assume it uniformly distributed
st = storage volume at time t
Et+1 = evaporation volume in [t , t+1)
a
rt+1 = volume actually released in [t , t+1)
at+1 = st+1 - st + Et+1 + rt+1
st+1 = st +at+1 - Et+1 - rt+1
at+1 = inflow volume [t ,t+1)
Inflow calculation
t t +1
at+1
we assume it uniformly distributed
st = storage volume at time t
Et+1 = evaporation volume in [t , t+1)
a
rt+1 = volume actually released in [t , t+1)
at+1 = st+1 - st + Et+1 + rt+1
from energy measures
st+1 = st +at+1 - Et+1 - rt+1
at+1 = inflow volume [t ,t+1)
Inflow calculation
t t +1
at+1
we assume it uniformly distributed
st = storage volume at time t
Et+1 = evaporation volume in [t , t+1)
a
rt+1 = volume actually released in [t , t+1)
at+1 = st+1 - st + Et+1 + rt+1
from level measures
st+1 = st +at+1 - Et+1 - rt+1
at+1 = inflow volume [t ,t+1)
Inflow estimation
t t +1
at+1
we assume it uniformly distributed
st = storage volume at time t
Et+1 = evaporation volume in [t , t+1)
a
rt+1 = volume actually released in [t , t+1)
at+1 = st+1 - st + Et+1 + rt+1
?
An example: HoaBinh
st+1 = st +at+1 - Et+1 - rt+1
Historical reservoir storageEstimated reservoir storage
EVN estimates
An example: HoaBinh
Historical reservoir storageEstimated reservoir storage
x 4.53
st+1 = st +at+1 - Et+1 - rt+1
An example: HoaBinh
x 4.53
st+1 = st +at+1 - αEt+1 - rt+1
Historical reservoir storageEstimated reservoir storage
Hydropower plant
Hydropower plant model
Hazen-Williams formula [Gardner Stewart.W [1920]
for each turbine for the whole plant
net head
Tuyen Quang
The stage function can be more complex: SonLa
Influence of Hoa Binh reservoir level
Historical Son La downstream level
Historical Hoa Binh reservoir levelEstimated Son La downstream level
1/1/2011 - 31/07/2012
Hydropower plant model
turbine efficiency η η = (q,H) orη = (p,H)
Characteristic curve of a turbine of Tuyen Quang power station
Sources:EVN
for each turbine for the whole plant
Tuyen Quang
Optimal turbines allocation
the efficiency of the two turbines must be equal
If all the turbines are identical, it follows that they must all be fed with the same flow.
the total flow Q has to be equally split among m turbines, where m is the number of turbines that maximizes the total generated power P, given the net head H
Optimal hours allocation
Ej energy production generated by splitting the volume R in j hours
For a given H
1 hour
2 hours
3 hours
Tuyen Quang
The distribution in time has nothing conceptually different from the distribution among the turbines.
Optimality condition: the efficiency must be the same for every turbine and every instant of times
If the net head H were know
Optimal hours allocation
Solve the system numerically for any j and (R,hr)
However, the net head H is not known in advance: it depends upon the volume R (which influences the downstream level hd) and the flow q through the turbines (which, due to the optimality condition, must be the same in each hour and each turbine).
hr = 95
hr = 105
Tuyen Quang
From mechanic to electrical energy
http://www.snowyhydro.com.au
Tuyen Quang
Error = -
maximum (electrical) energy that can be generated if:
the released volume Rt in day t is
know since the start of the day
the reservoir level hr remains stationary for the whole day
efficiency of the generator
Tuyen Quang
Error = -
Final tuning
http://www.snowyhydro.com.au
maximum (electrical) energy that can be generated if:
the released volume Rt in day t is
know since the start of the day
the reservoir level hr remains stationary for the whole day
efficiency of the generator
depends on the diameter and the type of material of the penstock Estimate θ
maximum (electrical) energy that can be generated if:
the released volume Rt in day t is
know since the start of the day
the reservoir level hr remains stationary for the whole day
Tuyen Quang
Error = -
Final identification
http://www.snowyhydro.com.au
Tuyen Quang
HoaBinh
Www.wikimapia.org
Hoa Binh validationError = - 3 year moving windows
efficiency
Hoa Binh validationError = - 3 year moving windows
prior the year 2009
efficiency
Son La validation
Togliere verde
Son La validation
1
2
3
4
5
turbines
Son La validation
1
2
3
4
5
turbines
wikipedia.org
TuyenQuang
Reservoir: release function (1)
before July 2012
Reservoir: release function (1)
Historical downstream levelEstimated downstream level
2002-2012
Historical data
Chiem Hoa reservoir
Reservoir: release function (1)
before July 2012
declared to be valid after July 2012
Reservoir: release function (1)
before July 2012
declared to be valid after July 2012
proposed
Van Coc diversion
Scheme of RTBR system
Van Coc diversion
Van Coc rules
• Opening
When
hHNt > 12.8 m and (hHN
t+1 > 13.4 or hHNt+2 > 13.4)
• Closing
When
hHNt < 13.4 m and (hHN
t+1 < 13.4 and hHNt+2 < 13.4)
The detention basin dynamics is assumed to be negligeable
^ ^
^ ^
Thanks for your attention
XIN CẢM ƠN
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