Power Electronics ASVG Power Quality System at Fonterra Hautapu ticks all of the boxes

Vishaal Lad, Electrical Engineer for Fonterra Hautapu identified that several switchboards on site had power factor correction equipment that was either not working, non-existent or not economical to maintain due to age.   

He was acutely aware that low power factor causes many issues including penalty charges, reduced efficiency, reduced capacity and increased heat losses. 

A power quality meter was connected by Power Electronics to three switchboards and the data recorded. 

The Cheese Packing switchboard had no power factor correction due to  failure of the original capacitor based system.

Measurements revealed the true power factor averaging 0.82 with displacement power factor averaging 0.90.

True Power Factor is a combination of displacement pf, by induction motors causing current to lag the voltage, and distortion pf, caused by non-linear load’s harmonics such as VSDs, LEDs and switched mode power supplies.  In order to improve True Power Factor some form of Active Harmonic Filtering was required to mitigate harmonics and thus improve true power factor.

Power Electronics recommendation was to use 300kVAr ASVG (Advanced Static Var Generator) which would mitigate harmonic levels, correct displacement pf and bring true power factor up to > 0.95.  This would also allow for the additional load which was not running at the time of the test.

 Vishaal’s decision to choose the ASVG and the Cheese Packing switchboard was for the following reasons;

• There was no PFC on this board due to a failure in the original capacitor based system
• The ASVG assesses and corrects within 15ms or ¾ of a cycle.  This enables a setpoint of unity pf to be maintained without the concern of under or over correcting. 
• The ASVG is immune to existing system harmonics and eliminates the risk of fire from failing capacitor based PFC systems.
• The plug-in module design allows for simple addition of extra modules.
• Inverter technology eliminates the possibility of resonance.
• Low losses and low maintenance.
• The new inverter technology is a much better solution compared with the traditional capacitor based PFC which are becoming more redundant in today’s harmonic rich environments.
• Total cost of ownership is very similar to a properly designed capacitor based system
• Shorter delivery timeframe due to parts available in NZ

Pictured above, the 300kVAr ASVG unit installed in the Cheese Packing Switch Room

As can be seen from the screenshot above pf has been improved from a low of 0.827 to 0.999. 

TDHi has been reduced from 44-47% to 10%.  Current that the mains cables feeding the Cheese Packing switchboard sees has not only been reduced by 60 amps, it has also been balanced out by the ASVG.  The plant was not operating under full load at the time of the screenshot however there was plenty of capacity left in the ASVG.

The ASVG’s dynamic performance and infinitely variable reactive power compensation makes it an ideal solution for rapidly changing loads, allowing a setpoint of unity achievable.

Vishaal concludes “This has been a successful project and is in keeping with Fonterra’s drive to be an industry leader by utilising the latest technology”.

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