• Filters on the 690V / 400V / 230V busbars

Except in the situation where only one filter is located at the node 4 or 5 (230V), every other filters combination allows to meet the harmonic voltage specifications. The table 7 and Figure 7 illustrate the main results for the new configuration. Nevertheless, it can be noted that the filtering power can vary greatly in a ratio from 1 to 4 according to the selected connection point. Then the maximum power level near to 51kVA is achieved with a filter connected to the node 1 or 2 while the minimum value of 14.5kVA is obtained with a filtering applied to the nodes 4 and 6.

The proper working of the optimisation process can be then appreciated: the implemented procedure allows to assess a suitable filtering power in compliance with the specified limits set to 3.5% for the fifth harmonic while minimising the total power involved. This also highlights the interest to search for the optimal number and placement of harmonic filters to connect to the grid. In the proposed example, the placement of two filters at the nodes 4 and 6 allows to solve the matter whereas a single filter connected to the node 4 cannot meet the voltage requirements for a similar filtering power near to 14 kVA.
