1Didden, M BE Session 2 – Block 3

Barcelona 12-15 May 2003

Considerations to choose the appropriate voltage sag mitigation device

M. Didden, K.U.Leuven - Energy Institute

marcel.didden@mech.kuleuven.ac.be

2Didden, M BE Session 2 – Block 3

Barcelona 12-15 May 2003

Introduction- If process modifications are not possible, mitigation equipment between process and grid can be considered- General guideline before comparing different options:

Cinv initial investment per kVA,

f annual outages due to sags, pprev percentage of outages being prevented,

f·pprev annual mitigated outages,

Csag outage cost per sag per kVA,

pmnt annual maintenance costs per kVA as a percentage of Cinv,

i discount factor, n project time (a).

1)i1(

p)pi()i1(x

C

Cpf

nmntmnt

n

sag

invprev

3Didden, M BE Session 2 – Block 3

Barcelona 12-15 May 2003

Considerations (1/2)

Mitigation concept1) Full protection: during a sag, the load is completely fed by an external energy source2) Relative protection: the voltage is raised by a certain percentage, implying that the immunity of the equipment is enhanced by the same percentage3) Absolute protection: the process will be protected against sags of a certain depth.!!! It should be taken into account that the amount of reduced process outages using this protection highly depends on the initial immunity of the process

4Didden, M BE Session 2 – Block 3

Barcelona 12-15 May 2003

Considerations (2/2)

Price- Initial purchase price- Standby cost- Maintenance (moving parts, batteries)

Other PQ-problemsSome applications are able to solve problems such as voltage harmonics, current harmonics, flicker and controlling reactive power.

5Didden, M BE Session 2 – Block 3

Barcelona 12-15 May 2003

ConclusionsThe techno-economic best solution:

- Flywheel /- On-line UPS if all sags have to be mitigated for- DVR with energy reserve /- DVR without energy reserve if no DC-bus- Statcom /- Shunt connected SM no DC-bus + other PQ issues- Boost Converter if DC-bus, no other PQ-issues- Active Front End if DC-bus, other PQ-issues- Transformerless series injector no DC-bus, no other PQ-issues