Why Reactive Compensators Do Not Improve the Efficiency Correctly in Unbalanced Circuits

− This paper shows utility of phasor total unbalance power as a tool to explain working of unbalanced power systems. Conditions under shunt capacitors used to compensate reactive power can deteriorate the efficiency in three-phase four-wire unbalanced at loads power systems are described. Reactive phenomenon is studied using Emanuel ́s positive-sequence fundamental-frequency reactive power, included in the IEEE Standard 1459-2000. Unbalance phenomenon is analyzed using the phasor total unbalance power. This quantity measures unbalance power due to the active loads by separating of those caused by the reactive loads. Results of this analysis show that reactive phenomenon in three-phase power systems can be compensated by single or three-phase capacitor banks, but undesirable effects on the system efficiency are consequence of the unbalance phenomenon and they can be increased by an inadequate reactive-compensator topology. It can have unbalance power due to the reactive loads even thought the reactive power has been compensated.