Active Harmonic Filters Increase Productivity in the Paper Industry

The paper industry is known for its high availability targets and
multiple variable frequency drive applications. Enclosed is a case study
from Schaffner showing the advantages of applying an active harmonic
filter solution to reduce the grid harmonics. As the active filters are
in parallel there is no risk of stopping the machine if the filter fails.

Active Harmonic Filter Application in Ba Na Hills, Vietnam

Here is a great showcase of the effects of applying active harmonic filters on a cable car installation made by Power More in Vietnam. Ba Na Hills Mountain Resort are holders of three Guiness Records – Longest single rope cable car system, Longest distance between stations and Heaviest cable roll. For Ba Na Hills, power quality is a question of safety and service quality. With total harmonic distortion 5 times higher than the national regulated level, Ba Na Hills were facing several problems.

  • Station to station communcation was interrupted
  • Power factor penalties
  • Damaged PFC capacitor units
  • Inerference with PFC controller
  • Reduced motor effeciency in generator mode to 50%

Applying ADF Power Tuning active filters from Comsys to battle both power factor correction and harmonic filtering resulted in:

  • Eliminated risk of PFC failures
  • Eliminated power factor penalties
  • Increased motor efficiency to 100%
  • Improved cable speed

Active Filtering Just Got Simpler

Active Filtering just got simpler with Sensorless Control

Comsys has released a new solution for controlling the Active Harmonic
Filter. The sensorless active filter control reduces the cost and
complexity of the system as it does not require any current transformer

In this case study they describe the retrofit on a small diesel
electric powered oil tanker, Fox Luna. The sensorless active filtering
approach is well equipped for protecting sensitive loads from dirty grids.

Sensorless Control Case Study

Schaffner use Active Harmonic Filters to Clean up Conference Center

In this case study of the Luzern Conference Center in Switzerland, Schaffner demonstrate the full utility of the active harmonic filter application. The active filters are distributed throughout the building to compensate not only harmonics but also power factor correction as well as load balancing.

Leave it to the Swiss to adapt to multifunctional tools.


Vacon Launches NXC Low Harmonic Drive Based on Active Harmonic Filter Technology

Vacon Low Harmonic NXCVacon joins Danfoss as the second tier 1 drives manufacturer to integrate an active harmonic filter with a drive to lower harmonics. Vacons stand-alone NXC range previously offered 12 pulse as well as active front end drive solutions.

The Low Harmonic NXC was recently shown at a large exhibition in Sweden and is reportedly offered on a project by project basis but will become a standard offering in the near future. The system shown, verifies the smaller foot print and weight of the Active Filter drive system compared to the more common Active Front End drives. The active filter NXC also has a lower power loss, which is becoming more important as the EN 50598-2 standard is introduced.

Low Voltage Active Filter as a Medium Voltage STATCOM for Windpower

Fortum Kville Power station

Kville power station compenstated by Comsys STATCOM design.

When the 32 MW Kville wind power station was being built in Sweden, the local grid owner Fortum was looking for alternatives for inductive compensation.  The long underground cable length cause a dynamic capacitive reactive power problem that normally is compensated using a large MV inductor. The inductor is very large and costly device at these sizes and Fortum wished to investigate other alternatives.

Comsys used its extensive knowledge from MV applications in applying its liquid cooled low voltage Active Filter with a step up transformer to create a 2,5 MVA STATCOM solution to solve the problem. If applied correctly, an active technology is very compact and flexible enabling high availability. Comsys liquid cooled modular design offers a high degree of redundancy and availability as the modules can be operated individually.

A further complication was the requirement to measure at the PCC on the 130 kV level so the Low Voltage ADF STATCOM worked through two step-up transformers. After extensive simulations by Comsys, the system was designed and supplied through the turn key integrator Siemens.

Comsys modular design AHF

Comsys P700 modular STATCOM solution

The active filters where installed in an existing building and the step-up transformer was installed outside, saving valuable indoor space and requiring no additional transformer cooling.

The solution dynamically compensates the capacitive reactive power and keeps it in line with the utility’s requirement. Due to the STATCOM following the load dynamically and observing both voltage and current, optimal grid conditions are ensured during all operating conditions.

The investment cost was reported to be lower than using the customized inductor solution proving the competitiveness of small active STATCOM versus passive options.

The ADF P700 STATCOM is a perfect solution in a dynamic environment such as wind farms. It is as cost effective and compact as a passive solution but with superior performance.

AHF Compensates Thruster and Refrigeration Compressor

Danfoss used an Active Harmonic Filter to compensate the THD of their installed 960 kW of VFDs for thruster and refrigeration compressor on the fishing vessel Gitte Henning #8. The AHF ensured to keep the installation within class requirements. Read more at:

Danfoss VFDs on Gitte Henning #8