On Compensation Strategies For Active Filtering In Power Networks

The filtering of disturbances in electrical power networks 1s at present carrled out almost entlrely by the use of passlve filters. These are also entrusted wlth the task of produclng the necessary reactive power. The dlfficultles assoclated wlth the use of these components can be overcome by employlng actlve filters. Present-day technology makes it possible to construct active compensatlon systems. By inJectlng currents of the requlred waveform into the network, these systems carry out simultaneously power factor correctlon, fllterlng and load balancing operatlons. Compensation strategles may assume many forms. Amongst these, unlty PF compensation and sinusoidal compensation are of particular interest in practice. The article examines these two strategles from the point of vlew of current and voltage distortion, losses in the power network and of the current interchanged by the compensation system. The study demonstrates that the two strategles quoted are equivalent when the disturbances origlnate In the load only. It is also shown that, generally speaking, there is no single solution in all the sltuations encountered.