1. An array-based study of increased system lifetime probability
Carsten Nesgaard
Technical University of Denmark
in collaboration with

2. Outline Power system description
Traditional redundancy vs. proposed redundancy concept
Advantages and disadvantages
Statistical representation of system survivability

3. Power system specifications
Unidirectional power flow
N + 2 redundancy
The power path of a converter is comprised of 5 blocks
Each converter uses a front switch

4. Redundancy in reliable power supplies

5. Alternative redundancy scheme

6. Configuration of converter 1

7. Efficiency enhancement

8. Advantages and disadvantages
Compared to a static system the ability to reconfigure itself increases the reliability of any system
The overall reliability of the proposed power system approaches that of a static N + 3 redundant system
Increased reliability with minimal increase in parameters such as volume and mass
Worst case reliability scenario equals that of the traditional static power system
Cost price increases considerably due to the large number of switches
Individual block failure rates increase

9. Nial: Nested interactive array language
System configuration
Nial: Nested interactive array language

10. NIAL NIAL - Nested Interactive Array Language
Designed to allow easy construction and manipulation of data structures, thus enabling the user to create ultra fast – loop free – algorithms for control purposes.
NIAL is developed by professor Mike Jenkins at Queen’s University in Canada.

11. Successive path finding
Step 1
Step 2
Step 3
Traditional logic require multiple loops to find a feasible path.

12. Solution array
Having calculated all switch positions the following array is established:
|ooooo|ooooo|ooooo|olooo| |loooo|olooo|olooo|ooooo| |ooloo|ooloo|ooloo|ooloo| |ooolo|ooolo|ooolo|ooolo| |ooool|ooool|ooool|ooool|
Resulting matrix
Switch configuration

13. Array theoretical implementation of step 1
|lo|oo|oo|ol| |ol|ll|ll|lo| |ll|ll|ll|ll| |ll|ll|ll|ll| |ll|ll|ll|ll|
Q:=((0 pick (cols AA) eachleft = ll) link o)
oolllo
Y:=Q sublist (reverse Res_1)
|oo1oo|ooolo|ooool|
index gets each first (Y eachleft sublist tell (first shape AA))
2 3 4
Y (cart index 0) placeall AA
AA:
All 4 lines of code can be combined and form a very fast algorithm for step 1.
|lo |oo|oo|ol| |ol |ll|ll|lo| |ooloo|ll|ll|ll| |ooolo|ll|ll|ll| |ooool|ll|ll|ll|
Modified AA:

14. Block failure rates Static power system failure rate:
l Total = l Block
Proposed power system failure rate:
l Total = l Switch + l Block

15. Statistical assessment
Power system survival probability:
Proposed configuration
Static configuration
Minimizing individual converter failure rate does NOT imply maximum system survivability.

16. Survivability comparison
Comparing the survival probability of the two configurations it can be seen that the proposed configuration is worse at total converter failure rates lower than:
However, the total failure rate in a real world implementation will most often exceed the above boundary failure rate.

17. Mechanical analogy of the redundancy control

18. Mechanical analogy of the redundancy control

19. Conclusion
An alternative approach in the design of reliable power systems has been presented.
A redundancy control scheme using the array-based logic has been established and its capabilities in ensuring a maximum number of operational paths through the power system has been shown. The drawback of the proposed system configuration is the large number of switches.
Finally, a statistical assessment of the increase in system survivability has been presented and compared to that of a traditional redundant power system.