Unbalanced power active compensator with unit efficiency control for the improvement of the electric quality in four wire systems with photovoltaic panels in the DC bus

The paper presents a new method for obtaining the reference currents for an unbalanced power active compensator (UPAC), applied in unbalanced systems with linear loads connected to an unbalanced three-phase system and with positive sequence voltage. The reference currents are obtained using the unifying theory of electrical power (UTEP). UTEP is applied to the control of a power converter and this helps optimize the balance of the current supplied by the three-phase generator and improves efficiency. Unit efficiency control (UEC) is used in this application. The developed system uses photovoltaic panels in the DC bus and this enables compensation for power losses in the inverter bridge and control circuits-depending on the level of sunshine. The system efficiently supplies electrical energy to the utility. UEC control of voltage source inverters (VSI) is applied over a single-phase linear load; specifically, over a resistance domestic oven of 2200 W, supplied by a three-phase utility of 220 V from line to neutral point, with a 50 Hz frequency and direct sequence. The digital control is achieved with a digital signal processor (DSP) and the power section consists of a commercial three-phase power inverter bridge and an interface card.