UNITS COMMITMENTS

1. Electrical Power Systems Economics

2. Units commitment

3.  Example
Units commitment

4. solve
Units commitment

5. Units commitment

6. Units commitment

7.  One approach to this solution Simple approach to the
solution is a simple priority list scheme.
 Illustrative Example for the simple priority list scheme
(shut-down rule)
Return to above example, use the simple shut-down rule for
3-units to supply a range of loads from 1200 to 500 MW in
steps of 50 MW. The cost functions for the units are:
𝑭𝟏 𝑷𝟏 = 𝟓𝟔𝟏 + 𝟕. 𝟗𝟐𝑷𝟏 + 𝟏. 𝟓𝟔 ∗ 𝟏𝟎−𝟑𝑷𝟏
𝟐
𝟏𝟓𝟎 𝑴𝑾 ≤ 𝑷𝟏 ≤ 𝟔𝟎𝟎 𝑴𝑾
𝑭𝟐 𝑷𝟐 = 𝟑𝟏𝟎 + 𝟕. 𝟖𝟓𝑷𝟐 + 𝟏. 𝟗𝟒 ∗ 𝟏𝟎−𝟑
𝑷𝟐
𝟐
𝟏𝟎𝟎 𝑴𝑾 ≤ 𝑷𝟐 ≤ 𝟒𝟎𝟎 𝑴𝑾
𝑭𝟑 𝑷𝟑 = 𝟗𝟑. 𝟔 + 𝟗. 𝟓𝟔𝑷𝟑 + 𝟓. 𝟕𝟖 ∗ 𝟏𝟎−𝟑𝑷𝟑
𝟐
𝟓𝟎 𝑴𝑾 ≤ 𝑷𝟑 ≤ 𝟐𝟎𝟎 𝑴𝑾
Units commitment

8. solve
Units commitment

9. Units commitment

10.  The essential constraint in units commitment : Enough
units are committed to supply the load.
Spinning reserve
Units commitment

11. Units commitment

12. Example
Units commitment

13. solve
Units commitment

14. Units commitment
 Eastern Region:
− Assume we lost the largest unit which is (1040 MW)
− Local spinning reserve = 450 MW
− Spinning reserve from western region : 860 – 160 = 700 MW
− Tie line capacity = 550 MW
− Total : 450 + 550 = 1000 MW
The system is not secure, commit 40MW of new generation
within the eastern region
 Western Region:
− Assume we lost the largest unit which is (900 MW)
− Local spinning reserve = 760 MW
− Spinning reserve from Eastern region = 450 MW
− Tie line capacity = 390 MW
− Total : 760 + 390 = 1150 MW

15. Units commitment
Thermal unit constraints

16. Units commitment

17. Units commitment

18. Economic dispatch using dynamic
programming
H.W (2)
 For a power system consisting of two regions which are
connected together by a tie lines. Sex units in the two regions are
committed to supply 3450 MW loading, if the tie lines capacity is
500 MW in the two directions :
1) fill the following table.
2) Verify the allocation of spinning reserves in the system. If there
any problems with the reservation then give a solution.

19. Economic dispatch using dynamic
programming

20. Good Luck
Eng: Mohammed Abdalla Meadni
E-mail: Mo7.m3dani@gmail.com
Tel:00249124642929