Reciprocating Bus in FREEDM System with Solar Farm Integration

Speeding up the transition to clean renewable energy is one of the best ways to curb the dangers of carbon pollution that cause the climate changes. Solar power is one of sustainable and clean energy sources. Abounding type of solar power is photovoltaic PV, so it needs to be integrated into the utility grid to reduce the amount of burning fossil fuel, which causes the pollution problem. Besides, different DC voltage levels, in the medium voltage bus (MVB), are needed to fulfil the customer expectation and to harvest the solar power into Future Renewable Electric Energy Delivery and Management (FREEDM) system. Therefore, this paper discusses the integration of PV power with the main power grid via reciprocating bus based on power electronic transformer (PET), because PET can provide galvanic isolation instead of using the bulky conventional line-frequency transformer. Moreover, it can be controlled. Reciprocating bus is created by changing the connection of PETs in the secondary side to provide different voltage levels 10KV and 20KV in the MVB. 20KV bus is used to integrate the PV power to a main grid; in fact, it can feed the load from the solar power and from the grid at the same time. Rewarding of using PET is small, efficient and cheaper as compared with power transformer. Simulation results validate the effectiveness and superiority of proposed diagram; the results are verified by PSCAD / EMTDC software.