Multifunctional inverter based energy system integration and its application in PV system

Photovoltaic system is easily affected by weather and has the characteristics of typical intermittency and uncertainty, resulting in a low utilization rate of only about 20%. On the other hand, large number of power electronic devices are applied in photovoltaic system and frequent switching brings various disturbances to the distribution network and worsen the power quality. This paper optimizes the traditional photovoltaic grid-connected inverter into an integrated energy system with active power filter (APF) function without increasing any costs. In the daytime, the multifunctional integrated system can realize both the photovoltaic grid-connection and harmonic suppression in the case of capacity surplus. More importantly, continued work with APF function can also be performed at low light intensity or at night. On this basis, the unified control scheme of multifunctional integrated system is put forward and the key compound current loop controller consisting of PI control and repetitive control is designed. Finally, a multifunctional integrated prototyping system is established and experiments have verified the feasibility and effectiveness.