Asea Brown Boveri Jumet S.A. FD 1/30 ASEA BROWN BOVERI Harmonic Problem ? Are Tuned Filters THE Solution ?

Asea Brown Boveri Jumet S.A. FD 2/30 ASEA BROWN BOVERI Typical Industrial Plant Drive 600 kVA cos  =.7 Load 150 kW cos  =.85 High voltage network 200 MVA 6 kV Transformer 1300 kVA 7.8% Low voltage bus bar 400 V 50 Hz System of reactive power compensation

Asea Brown Boveri Jumet S.A. FD 3/30 ASEA BROWN BOVERI Equivalent Circuit Acts as a Source of Harmonic Currents Drive Load Compensation Transformer HV Net IhIhIhIh

Asea Brown Boveri Jumet S.A. FD 4/30 ASEA BROWN BOVERI Initial Problem : PF Correction cos  = 0.74 Q C (cos  = 0.92) = 279 kvar Q C (cos  = 1.00) = 521 kvar Harman51 Installation of 300 kvar Harmonic analysis needed

Asea Brown Boveri Jumet S.A. FD 5/30 ASEA BROWN BOVERI Before Compensation LV-THD = 8.2% HV-THD = 0.68%

Asea Brown Boveri Jumet S.A. FD 6/30 ASEA BROWN BOVERI Capacitors Only (300 kvar) LV-THD = 18.4% HV-THD = 1.48% (8.2%)(0.68%)

Asea Brown Boveri Jumet S.A. FD 7/30 ASEA BROWN BOVERI Capacitors Only I7I7I7I7 U7U7U7U7 Parallel resonance between net and capacitor High current inside capacitors Destruction of capacitors (and maybe the transformer too !)

Asea Brown Boveri Jumet S.A. FD 8/30 ASEA BROWN BOVERI Capacitors Only : Impedances Parallel resonance on H 7 Very high impedance (dangerous because current source !)

Asea Brown Boveri Jumet S.A. FD 9/30 ASEA BROWN BOVERI 7% Reactor Bank (300 kvar) LV-THD = 5.9% HV-THD = 0.48% (8.2% %)(0.68% %)

Asea Brown Boveri Jumet S.A. FD 10/30 ASEA BROWN BOVERI 7% Reactor Bank : Impedances The parallel resonance has moved to non significant harmonic level (if no H 3 ).

Asea Brown Boveri Jumet S.A. FD 11/30 ASEA BROWN BOVERI H 5 and H 7 Tuned Filters (200 kvar on H 5 and 100 kvar on H 7 ) LV-THD = 3.4% HV-THD = 0.28% (8.2% % - 5.9%)(0.68% % %)

Asea Brown Boveri Jumet S.A. FD 12/30 ASEA BROWN BOVERI H 5 and H 7 Filters : Impedances

Asea Brown Boveri Jumet S.A. FD 13/30 ASEA BROWN BOVERI Conclusion (THD Point of View) l H 5 and H 7 tuned filters give the lowest THD l 7% reactor bank conducts to acceptable results l Capacitors alone are dangerous when harmonics (risk of parallel resonance)

Asea Brown Boveri Jumet S.A. FD 14/30 ASEA BROWN BOVERI Currents (*) With 10 % fundamental overload 19% 71% 8% 6% 3% 56% 112% 131% 125% I RMS (*) I5I5I5I5 I7I7I7I7 7% H5H7H5H7H5H7H5H7 47%109%166%C 476 A 318 A 159 A I1I1I1I1 476 A No more security margin (already >30 % overload for capacitors)

Asea Brown Boveri Jumet S.A. FD 15/30 ASEA BROWN BOVERI Conclusion (I C Point of View) Harmonic currents inside the filters are important (I h  60-70% I 1, I RMS  130%) Care in design Harmonic currents inside the filters are important (I h  60-70% I 1, I RMS  130%) Care in design Harmonic currents inside the reactor bank are quite low (I h  20% I 1, I RMS  112%) Harmonic currents inside the reactor bank are quite low (I h  20% I 1, I RMS  112%)

Asea Brown Boveri Jumet S.A. FD 16/30 ASEA BROWN BOVERI Polluted High Voltage Net Acts as an Harmonic Voltage Source UhUhUhUh Assume U HT 5 = 3% U HT 7 = 2% Below VDE & G5/3 norms

Asea Brown Boveri Jumet S.A. FD 17/30 ASEA BROWN BOVERI H 5 and H 7 Tuned Filters LV-THD = 3.6% (3.4% with clean HT)

Asea Brown Boveri Jumet S.A. FD 18/30 ASEA BROWN BOVERI 7% Reactor Bank LV-THD = 7.6% (5.9 % clean HT)

Asea Brown Boveri Jumet S.A. FD 19/30 ASEA BROWN BOVERI Polluted HV Net : Currents 31% (19%) 112% (71%) 5% (8%) 10% (6%) 13% (3%) 91% (56%) 115 % (112%) 157% (131%) 146% (125%) I RMS I5I5I5I5 I7I7I7I7 7% H5H7H5H7H5H7H5H7 Drastic increase of filter current due to (small) HV pollution Burning of the filters

Asea Brown Boveri Jumet S.A. FD 20/30 ASEA BROWN BOVERI Conclusion l Tuned filters give much better THD than reactor bank BUT... l Tuned filters are extremely sensible to net pollution (with impossibility to foresee it). Design problems l Reactor banks can support net pollution without any damage

Asea Brown Boveri Jumet S.A. FD 21/30 ASEA BROWN BOVERI LV Network Extension No pollution of HV network Everything goes right with tuned filters Modification of LV net : + (small) new drive Drive I 600 kVA Load 150 kW Drive II 250 kVA

Asea Brown Boveri Jumet S.A. FD 22/30 ASEA BROWN BOVERI LV Network Extension : Currents Drastic increase of filter current due to (small) LV net modification Burning of the filters 28% (19%) 100% (71%) 11% (8%) 9% (6%) 4% (3%) 74% (56%) 114 % (112%) 150% (131%) 138% (125%) I RMS I5I5I5I5 I7I7I7I7 7% H5H7H5H7H5H7H5H7

Asea Brown Boveri Jumet S.A. FD 23/30 ASEA BROWN BOVERI Design Requirements Higher voltage on the capacitors Higher reactor losses, weight & cost Filters { 7% Reactor bank Filter I rms (A) I lin (A) Losses (W) Weight (kg) Volume (dm 3 ) Cost U rms (V) U peak (V) C L H5H5H5H5 H7H7H7H7

Asea Brown Boveri Jumet S.A. FD 24/30 ASEA BROWN BOVERI Parallel Filters SWITCHING ON SWITCHING OFF

Asea Brown Boveri Jumet S.A. FD 25/30 ASEA BROWN BOVERI Parallel Filters Always parallel resonance on missing filter

Asea Brown Boveri Jumet S.A. FD 26/30 ASEA BROWN BOVERI Multiple Steps of Same Tuned Frequency Tolerances C : ± 5% L : ± 2% ± 7 % on tuned frequency ± 7 % on tuned frequency due to component variations f0f0f0f0 f 0 ± 7% Very low impedance at f 0 Small differences on Z can lead to very high currents !

Asea Brown Boveri Jumet S.A. FD 27/30 ASEA BROWN BOVERI Multiple Steps Solution Parallelconnections Difficult to realize

Asea Brown Boveri Jumet S.A. FD 28/30 ASEA BROWN BOVERI Conclusions for Tuned Filters l Low flexibility l No control of harmonic current l Overload danger l Risk of over compensation l High currents when polluted HV net l High losses l High operational cost

Asea Brown Boveri Jumet S.A. FD 29/30 ASEA BROWN BOVERI Conclusions for Reactor Banks l Reactor preserving capacitors l Gratis filtrering properties Filteredharmonics Harmonics Q C / S T

Asea Brown Boveri Jumet S.A. FD 30/30 ASEA BROWN BOVERI Final Conclusion Always prefer a reactor bank a reactor bank in place of a tuned filter ! (*) (*) If possible !