multiwave: passive solutions for harmonics

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The load on industrial networks is more and more dominated by a high number of smaller and larger converters. They are used when purchasing new machines or when modifying present machines in order to increase energy effiency.

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Hereby, two effects can be observed. Firstly, the demand for inductive reactive power of fundamental harmonics decreases due to the reduction of motors operated directly on the mains. Secondly, the reactive power which is generated by the converters’ harmonic currents increases.

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The harmonic currents are removed from the power network by network impedances. Here, the power transformer’s impedance is a key factor, as this is where the major part of the harmonic voltages is generated, which in turn is responsible for faults at other consumer loads. Often, the limit value norm for harmonics is already violated in the main distribution board. This results in an unreliable operation of machines with increased faults in control technology.

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KBR’s harmonic filters of the multiwave product group are the solution. Here, the passive version as a tuned filter circuit system is completely new. multiwave passive was developed especially for mains which show a high proportion of 5th and 7th harmonics, typical harmonic systems of industrial networks. The system is introduced centrally in the low-voltage main distribution board and covers a part of the harmonic current. The construction of the passive filter determines the extent of suction (network cleaning).

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This results in a considerable improvement of the voltage’s total harmonic distortion (THD-V), in addition to a minor thermal load of the transformer.

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Controlling and monitoring multiwave passive is effected by the known compensation controller multicomp D6, which is provided with a specially developed program for filter circuit systems. multicomp D6 controls and examines contactors and fans, it monitors the system for overcurrent and excess temperature. Diverse measuring functions are implemented, as well as an error memory, which can be shown on the plain text display. Furthermore, it is possible to operate several systems in a master-slave-network.

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The compensation power of multiwave passive is remarkable. For example, a filter with 250 kvar of reactive power of fundamental harmonics is able to withdraw up to 650 A of harmonic current from the network. Thereby, the filter effect is very broadband and includes the following degrees of compensation:

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5th harmonic 85%

7th harmonic 43%

11th harmonic 32%

13th harmonic 30%

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In order to guarantee this level of filter performance on a long-term basis, components of highest load capacity need to be inserted. Again, the components from our own production were most convincing. The high performance reactors were specially developed for this type of system by KBR. The known UHPC premium capacitors, offering an overload capacity of up to twice of the nominal current, complete the package.

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Altogether, a consistent concept for a distinct improvement of your voltage quality at an unbeatable value for money.