A single-phase photovoltaic grid-connected power generation detection system and its nonlinear current control method

Abstract

The invention relates to the field of photovoltaic power generation systems, in particular to a single-phase grid-connected photovoltaic power generation detection system and a nonlinear current control method thereof. The system at least comprises a photovoltaic array, a filter capacitor, a grid-connected inverter, an AC distribution network and a grid-connected line. The grid-connected line comprises a maximum power point tracking module, a phase-locked loop module, a pulse modulation module, a linear control module and a partial-feedback linear control module. The nonlinear current control method includes: converting the nonlinear dynamic process of the system by linear and partial-feedback linear control, allowing the system to more quickly respond to external environmental changes, acquiring voltage and current signals which the photovoltaic array outputs to the grid side and which a grid-connected photovoltaic power generation system inputs to the grid side, and by means of nonlinear current control with functions such as maximum power point tracking and phase-locked loop, adjusting the inverter to allow the grid-connected photovoltaic power generation system to run efficiently and stably.

Description

technical field [0001] The invention relates to the field of photovoltaic power generation systems, in particular to a single-phase photovoltaic grid-connected power generation detection system and a nonlinear current control method thereof. Background technique [0002] Due to the intermittence of light and the nonlinear functional relationship of the power conversion device, the photovoltaic grid-connected system shows strong nonlinear characteristics. As the interface unit connecting the photovoltaic grid-connected power generation system and the grid, the photovoltaic grid-connected inverter is widely used It is of great research and application value to develop a high-performance current control method that is compatible with the grid-connected inverter hardware and is applied in a photovoltaic grid-connected power generation system. [0003] At present, the main control methods to improve the static and dynamic performance of the inverter include various PI control, de...

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Problems solved by technology

[0003] At present, the main control methods to improve the static and dynamic performance of the inverter include various PI control, deadbeat control, sliding mode control and various intelligent control methods; The output characteristics of the power supply change from time to time, load changes, sudden failures and other problems. The above control methods all show certain limitations: the dynamic response of PI control is not fast enough under the rapidly changing light irradiance and ambient temperature, and the amount of calculation and Complexity is difficult to achieve optimization; deadbeat control responds quickly, but requires an accurate system model, and it is difficult to overcome the mismatch and instability problems caused by changes in the external environment; sliding mode control requires high switching frequency control and is practical It is difficult to determine the ideal sliding mode surface; when intelligent control methods such as neural network and genetic algorithm are practical, it is difficult to accurately capture and fine-tune the dynamic characteristics of the system. It can be seen from the above analysis that it is necessary to fully increase the output power of the inverter Quality and optimization of the control process require further research and design of new control methods

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