Multi-power-supply complementary power supply device and control method thereof

Abstract

The invention provides a multi-power-supply complementary power supply device and a control method thereof. The multi-power-supply complementary power supply device comprises a photovoltaic power supply branch, a mains supply input branch, an inverter and a system controller; the photovoltaic power supply branch comprises a solar controller, an energy storage unit and a photovoltaic voltage adjusting circuit which are sequentially arranged from photovoltaic input; the mains supply input branch comprises a mains supply conversion circuit connected with the mains supply; the output end of the photovoltaic voltage adjusting circuit and the output end of a first voltage boosting / reducing DC-DC unit are connected in parallel to a DC bus of the inverter; a first acquisition circuit is arranged between the system controller and the photovoltaic power supply branch; a second acquisition circuit is arranged between the system controller and the mains supply input branch; and the control outputend of the system controller is connected with the mains supply conversion circuit and the photovoltaic voltage adjusting circuit. Compared with the prior art, seamless switching between photovoltaicand mains supply is realized, short-time interruption of load power supply is avoided, and huge economic loss is avoided.

Description

technical field [0001] The invention belongs to the technical field of electric power generation systems, and in particular relates to a multi-power supply complementary power supply device and a control method thereof. Background technique [0002] In the application of off-grid photovoltaic power generation system, due to the instability of photovoltaic power supply, it needs to be used as a complement to the mains power supply. The two power sources need to be switched and controlled. There are mainly two existing methods: [0003] The first such as figure 1 Shown: The mains is connected to the energy storage unit through AC-DC. When it is judged that the photovoltaic energy does not meet the load demand, the photovoltaic charging is turned off, the mains path is opened, and the mains charges the energy storage unit. After DC-DC, DC- After AC conversion, power is supplied to the load. [0004] The second such as figure 2 Shown: The AC power output by photovoltaic powe...

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Problems solved by technology

[0005] The above two methods have the following problems. First, the utility power directly charges the energy storage unit through AC-DC. Although the seamless switching between photovoltaic and utility power can be realized, the AC-DC needs to be isolated, and there are multi-level circuits afterwards. The cost of the solution is high, and the overall power supply efficiency is very low; second, the photovoltaic and mains are switched by switches. Although the efficiency is high, there is a short power supply interruption at the moment of switching, and the risk is high. For some important applications, it is not allowed to happen. Temporary power interruption, otherwise huge losses will be caused

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