Seven-parameter photovoltaic cell output characteristic modeling method based on STFT (Short Time Fourier Transform) operator

Abstract

The invention discloses a seven-parameter photovoltaic cell output characteristic modeling method based on an STFT (Short Time Fourier Transform) operator. The method comprises the steps of establishing an equivalent circuit initial model of photovoltaic cell output characteristics; defining the STFT operator to obtain a decoupling explicit equation parameter model of a photovoltaic cell; establishing a nonlinear equation set by using standard working condition basic data provided by a photovoltaic cell manufacturer, and calculating unknown parameters by using a solution algorithm; calculating unknown parameter values of the decoupling explicit equation parameter model under given working conditions; bringing the unknown parameter values under the given working conditions in the decoupling explicit equation parameter model of the photovoltaic cell to obtain a final photovoltaic cell model which comprehensively reflects photovoltaic cell output characteristics under the given working conditions. The method has the beneficial effects that the STFT operator adopted for model decoupling is not limited by a domain of definition, the expected STFT decoupling operator calculation accuracy can be set according to the needs, and the application is more flexible.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic power generation, and in particular relates to a method for modeling the output characteristics of a seven-parameter photovoltaic cell based on an STFT operator. Background technique [0002] With the continuous development of social economy, the shortage of fossil energy and the increasingly serious environmental pollution, people put forward higher and higher requirements for energy. Finding new energy has become an urgent task for human beings, and the development and utilization of renewable energy is imminent. Among them, solar energy, as one of the clean renewable energy sources with large-scale development prospects, is widely used in household small-scale solar power generation systems, large-scale photovoltaic grid-connected power stations, building-integrated photovoltaic glass curtain walls, solar street lights, and wind-solar complementary power supply systems. It has received ext...

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Problems solved by technology

Among them, the fixed ideal factor method assumes that under the condition of constant ideal factor, numerical calculation methods such as iterative method are used to solve the remaining four parameters, but one parameter is fixed, which will affect the accuracy of the overall modeling of the model

[0008] For the function optimization method, it is usually based on the open circuit condition, short circuit condition, maximum power point condition and maximum power point gradient condition of the photovoltaic cell equivalent circuit model at present. Factor a, equivalent series resistance R s and the equivalent parallel resistance R p etc. to optimize the solution for the target variable, and the a, R obtained through optimization s and R p Solve the reverse saturation current I of the diode under standard conditions by using the open circuit condition 0 , and it is assumed that the photogenerated current under standard conditions is approximately the short-circuit current under standard conditions, which to some extent loses the calculation accuracy of the model

In addition, the operating point of the photovoltaic cell array is usually the maximum power point under different operating conditions in order to effectively utilize the output energy efficiency of the photovoltaic cell array. Therefore, the constructed photovoltaic cell output characteristic model and its optimized parameters are also expected to be able to It has better model accuracy, such as matching the maximum power temperature coefficient parameters provided by the manufacturer and the correction of the short-circuit current temperature coefficient and open-circuit voltage temperature coefficient at the maximum power point. However, the current photovoltaic cell output characteristic modeling and parameter solution are both Failure to take into account the impact of the above factors

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