A novel three-level optical storage machine based on grid frequency control

Due to the fluctuation of PV power, it is difficult to keep the active power of the PV grid-connected inverter constant. To address the above problems, this paper proposed a new three-level integrated photovoltaic storage machine consisting of a T-type three-level DC/AC converter, a three-level Boost converter and a three-level bi-directional DC/DC converter and related control strategies. The three-level structure allowed for lower switching losses resulting in higher system efficiency and wider voltage range adaptability. In terms of control, frequency differentiation and deviation control were introduced in the control of the energy storage DC/DC converter to achieve frequency regulation of the transient/static support of the active power of the parallel network. The simulation and experiment show that when the frequency fluctuation range is 50.02~49.97 Hz (meeting the national standard), the new optical storage all-in-one machine proposed in this paper can operate stably and be easily realized.