Voltage Fluctuations (Dips and Swells) - Remedy, Solutions [Demo]

The solutions for voltage fluctuations (dips and swells) are as various as their causes.
powerqualityonline shows you possible remedies with their advantages and disadvantages.

The Following Measures Can be Taken:
 
1. Increase of Short-Circuit Power
Advantages Disadvantages
Voltage fluctuation (dips and swells) is reduced if caused by own loads Usually difficult to realize
Usually no detrimental effect on disconnection conditions Cost-intensive and complex
Also useful against harmonics and grid resonances Coordination with owners of upstream grid areas is often required
  No elimination of problem if fluctuation comes from outside
  Metrological support is required to ensure effectiveness and absence of retroactive effects to other loads
  Interruption of operation (downtime) during conversion

 

2. Load Equalization
Advantages Disadvantages
Voltage fluctuation (dips and swells) is reduced if caused by own loads Load is often not convertible
No effect on disconnection conditions Cause of problem eliminated if voltage fluctuation (dips and swells) comes from the own power grid
No coordination with owners of upstream  grid areas is required No interruption of operation of other loads

 

3. Use of Centralized UPSes per Property
Advantages Disadvantages
No intervention in power grid structure Interruption of operation (downtime) during installation
Mains retroactions are eliminated Solution is very expensive when covering the entire power
Easy realization of a local terra neutral separated grid structure (TN-S-structure) when using designs with output transformer Possibilty of more disturbances (high frequency) and resonances, depending on rectifier and EMC-filter topology
Bridging of voltage failures In case of resonances in the downstream low voltage power grid, they may persist (this can however be prevented by good output filtering)
Mains retroaction from outside is decoupled Metrological support is required to ensure effectiveness and absence of retroactive effects to other loads

 


The size of the UPS or UPSes must be chosen sensibly in each case. Only use models with passive rectification.
4. Use of Decentralized UPSes at Affected Loads
Advantages Disadvantages
No intervention in power grid structure Several devices required
Elimination of mains retroaction and external influences Possibility of more resonances, depending on rectifier and EMC-filter topology (but this can be prevented by good tuning)
Bridging of voltage failures No prevention from vagrant currents due to terra neutral combined/separated grid (TN-C-S-grid) problems
More cost effective than a central UPS as the power has to be covered only partially Result should be checked metrologically


The size of the UPS or the UPSes must be chosen sensibly in each case. For critical power grids (e.g. with commutation dips or other deformations of the voltage) only use models with passive rectification.
5. Use of Voltage Stabilizers for Affected Loads
Advantages Disadvantages
No intervention in power grid structure  
Possibly less expensive than a UPS Only suitable for low powers
No generation of high frequency Voltage stabilizers mostly work with magnetic saturation and a 50 Hz oscillating circuit, i.e. there are high losses and high electricity costs
  Unknown performance relating to harmonic loads and possibly already existing grid resonances, therefore measurement is necessary, thus test effort required


 
6.  Connection to Another Supply Point
Advantages Disadvantages
Very good chance of success when the supply point is selected correctly Intervention in power grid structure
UPS operation is omitted, thus also possible disturbing influences coming from it Possibly expensive due to potentially greater distances/cable lengths and possibly earthworks
No problem with surge loads Result should be checked metrologically

If the power grid is converted as described above, bundled conductors should be used instead of single conductors, since single conductors can lead to unbalanced impedances and vagrant currents due to the induction effect (even if the local terra neutral separated grid structure (TN-S-structure) is correct). Please refer to Unbalance.
The price of this option depends on whether long cable runs with possibly required earthworks have to be laid or whether there is the possibility of easy access to another feed-in.

 
7. Use of Other Devices, ECGs, Converters, Power Supply Units etc.
Avantages Disadvantages
No intervention in power grid structure Measurement is required beforehand to find out which devices are specifically affected
No costs for a UPS Often not realizable because of existing infrastructures or lack of spare components/devices
Avoidence of disadvantages of UPS and voltage constants Costly as many individual systems have to be checked
  Result/success should be checked metrologically
 This option is very costly because many individual components have to be replaced and it is practically not realizable at all because of existing infrastructures. I



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