ABSTRACT
PV often has to be operated in conjunction with conventional generating units as diesel generators. AC output is often required due to lack of DC consumer equipment. In many locations a connection to the public electrical grid exists, but supply is unstable. Therefore the power conditioning unit should be able to synchronize to the grid when it is working and switch immediately to an autonomous operation mode (supplied by a battery), as soon as supply is getting unstable or is lacking. The purpose of this work is to combine different units (MPPT, advanced charge controller using charge balance, an energy flow monitor with a data logger and a single phase DC-AC converter which works under stand-alone and in combination with other generating sets) to one system. MPPT and charge control are already built and tested, the integrated inverter is in the stage of development. To adapt the unit to different conditions and applications, a computer control for MPPT, charge controlling, energy balance monitoring and data logging was chosen. The computer also is also serving as a direct control of the power electronic devices. The design is relatively simple to ensure low costs and high reliability, but also features high efficiency. The 300 Hz PWM switching is carried out by a single IGBT device. The voltage of the DC bus at the output of the MPPT is controlling the energy flow into and from the battery. A fuzzy control strategy is compared to conventional approaches.
