Shunt active power compensator/photovoltaic generator for delta loads using the symmetrical components transformation

The paper describes a new method to obtain the reference currents for a three-phase shunt active power compensator-generator (SAPC/G). Simulated and experimental results as generator and in dual mode (generator/compensator) are presented, obtained with a low scale prototype. The use of photovoltaic panels, fuel cells and/or batteries, connected to the DC bus of the three-phase VSI inverter, supplies to the system the energy necessary for generation. Depending the voltage of the DC sources, the connection to the VSI inverter is done directly or via a DC/DC converter. In this paper SAPC/G is applied to compensate inefficiencies in unbalanced systems with delta linear loads connected to three-phase system at the same time that is generating active power. SAPC/G reference currents are obtained from the sensed voltages and currents in the point of common connection (pcc) with the load. The current and voltage symmetrical components are obtained applying Stokvis-Fortescue transformation. The new method of the SAPC/G reference currents uses the current symmetrical components in the load and a generating current term that depends on the maximum power point of photovoltaic panels. A MPPT algorithm indicates the energy available from the photovoltaic panels that can be transformed in useful electrical energy as an AC three-phase balanced current. The system improves the efficiency of the electrical system and can be used to prevent faults in the distribution lines. All the control systems are done with the digital processor TMS320LF2407. A tolerant band current control is used to control the SAPC/G output currents.