| The world's energy demand is increasing quickly. As photovoltaic system is one of the most promising alternative energy sources in DG. The power electronics converters based PCS in the PV system now becomes the key point in cost reduction.;The main tasks for inverter are draw the power out and injected a sinusoidal current to the grid. To competitive with other power sources, the most effective way is to develop inexpensive and reliable inverters. The aim of this thesis is therefore to develop new topologies and control strategies for PV system.;This thesis presented a new power conditioning system based on Z-Source inverter for renewable energy sources. The PV system performance depends not only on temperatures and irradiations, but also on maximum power tracking function of PV inverter. So it is important to verify the inverter system too. To help verifying the inverter system, a dc-dc converter based PV simulator was proposed and implemented. Also, both the stand-alone split-phase PV system and grid-connected three-phase PV system were proposed and analyzed. The simulation and experiment results were shown to verify the proposed system.;With unique X shape network, the Z-Source inverter can realize buck and boost function without additional dc-dc converter. For grid-connect action, the proposed harmonic injected unity power factor current control which also employed modified P&O MPPT method are suitable for PV power applications. By utilizing the Z-Source inverter, the volume, the cost, and the switching device count are minimized. Because of the single stage operation, the efficiency of the system can be greatly improved. The reliability can be enhanced greatly due to the shoot through states. With all these advanced features, the Z-Source inverter based PCS is very promising for renewable energy applications. |
