Distributed photovoltaic power optimizers and control method

Abstract

The invention relates to distributed photovoltaic power optimizers and a control method. When series connection and parallel connection of photovoltaic modules are mismatched due to factors such as partial or intermittent shielding or aging of photovoltaic arrays, the control method is more obvious in effect. The control method is characterized in that after directly attached to photovoltaic modules, the power optimizers are connected through a series connection framework, and the power optimizers in the series connection framework firstly obtain voltage signals and current signals of the photovoltaic modules connected with the power optimizers and directly perform maximum power tracking on the single module, so that the photovoltaic modules output maximum power, and results are transmitted to a central controller. The central controller receives the maximum power calculated by each optimizer, voltage and current conditions of the shielded modules are monitored, and the voltage and current output by all the modules are coordinated through calculation. The control method not only can ensure that each photovoltaic module works at an optimal working point, but also can enable setting of bus voltage to be more flexible and stable, and the system can serve as a direct-current power supply and also be used for an independent or grid-connection photovoltaic system.

Description

technical field [0001] The invention relates to the technical field of photovoltaic applications, in particular to a distributed photovoltaic power optimizer and a control method. Background technique [0002] Solar photovoltaic power generation system, referred to as photovoltaic, is a power generation system that uses the photovoltaic effect of solar cell semiconductor materials to directly convert solar radiation energy into electrical energy. In order to obtain higher voltage or current output, the photovoltaic system is composed of multiple photovoltaic modules. (Modules) connected in series or in parallel. The actual large-area laying of photovoltaic module arrays has uneven lighting conditions, and often faces harsh phenomena, such as shadows, debris, dirt and other environmental conditions. The unbalanced output of photovoltaic modules will cause mismatch problems when they are connected in series or in parallel. , and the direct consequence of the mismatch problem ...

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Problems solved by technology

However, each power optimizer tracks independently, which cannot realize the coordinated control of the parallel branches of the photovoltaic system, and cannot ensure that the DC bus voltage of each string of photovoltaic modules is equal and stable. The branches with lower voltages cannot output current, and may even flow a reverse Direct current, in order to avoid the generation of parallel branch circulation, must connect the diode (101) in series in each branch, the output current will produce an additional loss on the diode

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