Photovoltaic grid-connected inverter and control method thereof

Abstract

The invention discloses a photovoltaic grid-connected inverter and a control method of the photovoltaic grid-connected inverter. The photovoltaic grid-connected inverter comprises a maximum power point tracking module, a power switch tube object, an equivalent filter, a phase-locked loop, an electric grid disturbance measurement module, a current transducer, a voltage transducer and a BP (Back Propagation) nerve network control module, wherein the output end of the voltage transducer is connected to the input end of the phase-locked loop; the BP nerve network control module is respectively connected with the output end of the maximum power point tracking module and the phase-locked loop, the output end of the electric grid disturbance measurement module and the output end of the current transducer, which are used as three input ends of the BP nerve network control module; the output end of the BP nerve network control module is connected with the input end of the power switch tube object; and the output end of the power switch tube object is connected with the input end of the equivalent filter. The photovoltaic grid-connected inverter is higher in intelligent and output precision and is capable of adapting various electric grid environments and improving the stability and the reliability of a photovoltaic grid-connected power generation system.

Description

technical field [0001] The invention relates to the field of nonlinear intelligent control of power electronics, in particular to a photovoltaic grid-connected inverter based on a BP neural network and a control method thereof. Background technique [0002] Photovoltaic grid-connected power generation is the mainstream technology of solar power generation. This technology involves the integration of new semiconductor materials, new power electronics technologies, and modern control theory. It is one of the hot research technologies for new energy utilization in the world today. Photovoltaic grid-connected inverter is a circuit device (DC-AC) that converts direct current output from solar cells into alternating current, and is a strongly nonlinear system. For a strong nonlinear system such as DC-AC switching power inverter, the conventional linear control algorithm cannot achieve satisfactory results, and the linearization model is difficult to reveal the various dynamic char...

AI Technical Summary

Problems solved by technology

These linear control methods are widely used in the synchronous control of photovoltaic grid-connected inverters because of their simple algorithms, but their defects in practical applications are obvious: the disadvantage of PI control is that there is a principle error in the amplitude and phase, and the error There is a contradiction between the improvement of the system and the stability of the system; the hysteresis control is not fixed due to the switching frequency, the voltage stress on the switch tube is relatively large, and the actual design is difficult; the deadbeat control requires accurate load and system models, It is limited in specific applications; these shortcomings of the linear control method greatly affect the reliability and output accuracy of the photovoltaic grid-connected inverter

[0004] In addition, the load of the photovoltaic grid-connected inverter is the grid, and the grid is a complex nonlinear system with various uncertain factors and nonlinear characteristics that are difficult to describe exactly. Self-organization, self-learning, self-adaptive ability and strong fault-tolerant ability, the traditional linear control method can no longer meet such requirements

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