Double closed-loop control method for photovoltaic energy storage system in grid-connected mode

Abstract

The invention relates to a double-closed-loop control method of a photovoltaic energy storage system in a grid-connection mode, and belongs to the technical field of photovoltaic energy storage. The photovoltaic energy storage system is composed of a photovoltaic module, a lithium ion battery, a public power grid, a local load and power converters, wherein the power converters comprise the photovoltaic-side Boost converter, the battery-side Buck-Boost converter and the load-side full bridge inverter. The three converters are all connected to a public direct-current bus in a bridging mode, so that a direct-current microgrid is constituted. Double-closed-loop control is adopted for the load-side full bridge inverter in the grid-connection mode. By the adoption of an inner inverter filter inductance current loop and an outer direct-current bus voltage loop, the double-closed-loop control method has the advantages that the dynamic performance of the system is improved, and the output power of the photovoltaic module or the charging power of the lithium ion battery is controlled to be equal to the grid-side power by controlling a direct-current bus voltage to be constant; the technical problem that the output power of the photovoltaic module and flowing of the charging power of the lithium ion battery cannot be well controlled in the prior art is solved.

Description

technical field [0001] The invention relates to the technical field of photovoltaic energy storage, in particular to a double closed-loop control method, and more specifically to a double closed-loop control method in a grid-connected mode of a photovoltaic energy storage system. Background technique [0002] The entire photovoltaic energy storage system is composed of photovoltaic modules, lithium batteries, single-phase power grid, loads and power converters. The photovoltaic modules form a public DC bus through Boost converters, and the lithium batteries are connected to the public DC bus through Buck-Boost converters. Above, the DC bus is connected to the single-phase grid through the full-bridge inverter or independently converted into AC voltage to supply power to the load. All three converters are connected across the common DC bus to form a DC microgrid. [0003] In the grid-connected mode, the grid-connected control strategy of the full-bridge inverter is particula...

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Problems solved by technology

[0004] In view of the deficiencies in the literature in related technical fields and the above existing technologies, on the basis of a large number of existing literature research and long-term research and development practices in related fields, the present invention proposes "Double closed-loop full-bridge inverter in the grid-connected mode of photovoltaic energy storage system Closed-loop control strategy" overcomes the technical problems in the prior art such as "the output power of photovoltaic modules and the flow of lithium battery charging power cannot be well controlled", and the "inner loop inverter filters the inductor current loop and the outer loop DC bus voltage loop". ", to achieve the beneficial effect of "improving the dynamic performance of the system, and controlling the output power of photovoltaic modules or the charging power of lithium batteries to be the same as the grid-side power by controlling the DC bus voltage to be constant"

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