An Equivalent Modeling Method for Photovoltaic Power Generation System

Abstract

Disclosed is an equivalent modeling method of a photovoltaic power generation system. A function module, a controlled voltage source, a filtering circuit, an isolation transformer and a power grid are connected in sequence to form a simplified model of a photovoltaic power source, and the function module works out a steady-state output current of the system according to the illumination intensity and temperature when no fault occurs. When a short-circuit fault occurs, two types of steady-state output currents before and after the short-circuit fault are worked out firstly, then an output current variation curve of the whole transient process is obtained according to time-domain characteristics after reduction of the model and is achieved through fitting, the function module works out an output voltage deserved by the controlled voltage source according to the relationship between the voltage and current, and the controlled voltage source is controlled according to the calculation result. On the premise of achieving the control function of the detailed model and not affecting grid-connection external characteristics, the equivalent modeling method of the photovoltaic power generation system largely shortens simulation calculation time, improves simulation efficiency, and is simple in circuit and easy to achieve.

Description

technical field [0001] The invention relates to a modeling method of a photovoltaic power generation system based on external characteristics, and belongs to the technical field of power generation. Background technique [0002] In today's world, people are increasingly dependent on fossil energy such as coal, oil and natural gas, and the reserves of these fossil energy have a certain limit and are increasingly depleted. Photovoltaic power generation has been highly valued worldwide due to its advantages of energy cleanliness, resource adequacy and potential economy. With the decreasing cost of photovoltaic power generation system, its application is becoming more and more extensive. [0003] figure 1 It is a schematic diagram of the composition of the photovoltaic power generation system. Three-phase grid-connected photovoltaic power generation system consists of photovoltaic array, maximum power tracking (MPPT), inverter system, filter circuit, isolation transformer and...

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Problems solved by technology

[0006] At present, the research on the model of photovoltaic grid-connected system is mainly based on the control strategy of photovoltaic array, maximum power tracking (MPPT) and inverter. Multiple iterations are required, the model is too complicated, and it is not suitable for engineering calculations of a large number of distributed photovoltaic power sources connected to the distribution network, and a simplified and practical equivalent circuit model of photovoltaic power sources is urgently needed

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