1. Hanoi, January 27 th 2015 Enrico Weber DEIB – Politecnico di Milano IMRR Project INTEGRATED AND SUSTAINABLE WATER MANAGEMENT OF RED-THAI BINH RIVER SYSTEM IN A CHANGING CLIMATE 4. Reservoirs and power plants models

2. 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

3. Essential condition The model simulation must be extremely fast: 1 year in few milliseconds We got 3 10 -3 sec

4. 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

5. Causal network r depends on a and e s t = storage volume at time t a t+1 = inflow volume in [t,t+1) e t+1 = specific evaporation in [t,t+1) r t+1 = effective release volume in [t, t+1)

6. Mechanistic model surface Dung tích hồ [m 3 ] Diện tích mặt nước hồ [km 2 ] TuyenQuang

7. Mechanistic model evaporation surface storage

8. Mechanistic model evaporation surface storage level release TuyenQuang

9. Mechanistic model evaporation surface storage level release

10. Instantaneous storage-discharge relationships s* : storage corresponding to the spillway position s* spillway s(t)s(t) TuyenQuang minimum release

11. Instantaneous storage-discharge relationships s* spillway open gates minimum release s(t)s(t) TuyenQuang

12. 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)s(t) From this information the function R t (s t,u t,a t+1,e t+1 ) is obtained.

13. Legal constraints Minumum 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

14. s t+1 = s t +a t+1 - E t+1 - r t+1 a t+1 = inflow volume [t,t+1) Inflow calculation t t +1 a t+1 we assume it uniformly distributed s t = storage volume at time t E t+1 = evaporation volume in [t, t+1) r t+1 = volume actually released in [t, t+1) a t+1 = s t+1 - s t + E t+1 + r t+1

15. s t+1 = s t +a t+1 - E t+1 - r t+1 a t+1 = inflow volume [t,t+1) Inflow calculation t t +1 a t+1 we assume it uniformly distributed s t = storage volume at time t E t+1 = evaporation volume in [t, t+1) r t+1 = volume actually released in [t, t+1) a t+1 = s t+1 - s t + E t+1 + r t+1 from energy measures

16. s t+1 = s t +a t+1 - E t+1 - r t+1 a t+1 = inflow volume [t,t+1) Inflow calculation t t +1 a t+1 we assume it uniformly distributed s t = storage volume at time t E t+1 = evaporation volume in [t, t+1) r t+1 = volume actually released in [t, t+1) a t+1 = s t+1 - s t + E t+1 + r t+1 from level measures

17. s t+1 = s t +a t+1 - E t+1 - r t+1 a t+1 = inflow volume [t,t+1) Inflow estimation t t +1 a t+1 we assume it uniformly distributed s t = storage volume at time t E t+1 = evaporation volume in [t, t+1) r t+1 = volume actually released in [t, t+1) a t+1 = s t+1 - s t + E t+1 + r t+1 ?

18. An example: HoaBinh s t+1 = s t +a t+1 - E t+1 - r t+1 Historical reservoir storage Estimated reservoir storage EVN estimates

19. An example: HoaBinh Historical reservoir storage Estimated reservoir storage x 4.53 s t+1 = s t +a t+1 - E t+1 - r t+1

20. An example: HoaBinh x 4.53 s t+1 = s t +a t+1 - αE t+1 - r t+1 Historical reservoir storage Estimated reservoir storage

21. Hydropower plant

22. Hydropower plant model Hazen-Williams formula [Gardner Stewart.W [1920] for each turbine for the whole plant net head Tuyen Quang

23. The stage function can be more complex: SonLa Influence of Hoa Binh reservoir level Historical Son La downstream level Historical Hoa Binh reservoir level Estimated Son La downstream level 1/1/2011 - 31/07/2012

24. Hydropower plant model turbine efficiency η η = (q,H) or η = (p,H) Characteristic curve of a turbine of Tuyen Quang power station Sources:EVN for each turbine for the whole plant

25. 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

26. Optimal hours allocation E j 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

27. Optimal hours allocation Solve the system numerically for any j and ( R,h r ) However, the net head H is not known in advance: it depends upon the volume R (which influences the downstream level h d ) and the flow q through the turbines (which, due to the optimality condition, must be the same in each hour and each turbine). h r = 95 h r = 105 Tuyen Quang

28. From mechanic to electrical energy http://www.snowyhydro.com.au Tuyen Quang Error = - maximum (electrical) energy that can be generated if:  the released volume R t in day t is know since the start of the day  the reservoir level h r remains stationary for the whole day efficiency of the generator

29. Tuyen Quang Error = - Final tuning http://www.snowyhydro.com.au maximum (electrical) energy that can be generated if:  the released volume R t in day t is know since the start of the day  the reservoir level h r remains stationary for the whole day efficiency of the generator depends on the diameter and the type of material of the penstock Estimate θ

30. maximum (electrical) energy that can be generated if:  the released volume R t in day t is know since the start of the day  the reservoir level h r remains stationary for the whole day Tuyen Quang Error = - Final identification http://www.snowyhydro.com.au Tuyen Quang

31. HoaBinh Www.wikimapia.org

32. Hoa Binh validation after the year 2009 Error = - 3 year moving windows efficiency

33. Hoa Binh validation after the year 2009 Error = - 3 year moving windows prior the year 2009 efficiency

34. SonLa ‪www.vietnamonline.com

35. Son La validation Togliere verde

36. Son La validation 1 2 3 4 5 turbines

37. Son La validation 1 2 3 4 5 turbines

38. wikipedia.org TuyenQuang

39. Reservoir: release function (1) before July 2012

40. Reservoir: release function (1) Historical downstream level Estimated downstream level 2002-2012 Historical data

41. Chiem Hoa reservoir

42. Reservoir: release function (1) before July 2012 declared to be valid after July 2012

43. Reservoir: release function (1) before July 2012 declared to be valid after July 2012 proposed

44. Van Coc diversion

45. Scheme of RTBR system Van Coc diversion

47. Van Coc rules Opening When h HN t > 12.8 m and (h HN t+1 > 13.4 or h HN t+2 > 13.4) Closing When h HN t < 13.4 m and (h HN t+1 < 13.4 and h HN t+2 < 13.4) The detention basin dynamics is assumed to be negligeable ^ ^ ^ ^

48. Thanks for your attention XIN CẢM ƠN