Optimized Combined System of Shunt Active Power Filters and Capacitor Banks

In larges electrical system used in industries, office builidings, or hotels, capacitor banks are usually utilized to compensate the required VAR absorbed by the loads. As the nonliniear loads are increasing rapidly, the risk of resonance phenomenon occured is becoming higher as its terminal voltages are not anymore sinusoidal. On the other hand, many customers have become aware to the problems caused by the harmonics due to the nonlinear loads. In this case, the active power filters (APFs) offer many interesting properties i.e. the elimination of harmonics, phase balancing feature and the power factor correction. The power factor correction feature suggests that the APFs are also able to compensate the VAR which means that the APFs are able to replace completely the capacitor banks. However, the higher reactive power occured in APFs is responsible to the higher current flowing in the switches, thus the higher rating of switches are required which leads to more expensive system. In this paper, an optimized combined system between APF and capacitor bank is proposed. It is not necessary to dump the installed capacitor bank. In contrary, the capacitor bank will help the APF to compensate the VAR as the APF will concentrate mostly to eliminate the harmonics.