A high-efficiency, stable and multi-functional single-stage photovoltaic single-phase grid-connected control method

Abstract

The invention discloses a high-efficiency stable multifunctional single-stage photovoltaic single-phase grid-connected control method, and belongs to the technical field of photovoltaic power generation control. The method is characterized in that: the method adopts a high-speed digital signal processor and applies a C language dynamic fixed-point algorithm to form a high-performance control algorithm of a whole grid-connected control system; the method adopts a single-stage grid-connected control structure and a quick smooth maximum power point tracking method to directly transmit the maximum energy sent by a photovoltaic array to a local urban power grid through first-stage DC / AC transformation; the harmonic and idle work produced by a local load can be compensated by adopting an FBD method, so the method is favorable for improving the electrical energy quality of the local power grid; and a proportional resonant converter is used to implement precise closed-loop control for the grid-connected current so that the photovoltaic grid-connected current and the commercial single-phase voltage are totally synchronous while implementing maximum power point tracking of the photovoltaic array. The power factor is high, the system efficiency is high, the operation of the whole system is safe and reliable, and the aberration rate of the grid-connected current harmonic is lower than 3 percent.

Description

technical field [0001] The invention relates to a high-efficiency, stable and multi-functional single-stage photovoltaic single-phase grid-connected control method, which belongs to the application field of photovoltaic power generation system control technology. Background technique [0002] The development and utilization of abundant and vast solar energy without and less pollution to the environment is not only an urgently needed supplementary energy in the near future, but also the basis of the future energy structure. At present, the use of this clean energy is rapidly entering the commercial growth stage. Under such a premise, the development and application of solar photovoltaic power generation technology has become the focus of worldwide attention. The advantages of solar power generation are: no risk of depletion, absolutely clean, not limited by the geographical distribution of resources, can generate electricity nearby where the power is used, high energy qualit...

AI Technical Summary

Problems solved by technology

[0006] At present, most of the single-phase photovoltaic grid-connected systems on the market adopt a bipolar structure. The energy of photovoltaic cells needs to undergo DC / DC and DC / AC two-stage conversion. The intermediate conversion link uses batteries. Although the control method is relatively simple, the cost is relatively high. High, and the overall efficiency of the system is difficult to improve;

[0007] The grid-connected current of single-phase photovoltaic grid-connected control system has open-loop control mode and closed-loop control mode. The open-loop control mode is not accurate and unstable; the closed-loop control mode generally adopts traditional proportional plus integral control (PI regulator). Although the method is stable, the PI regulator is suitable for linear control systems, but not suitable for nonlinear control of single-phase sine wave current, especially in the initial stage of grid connection, it is difficult to meet the strict international and domestic standards.

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