Photovoltaic system maximum power point tracing method

Abstract

The invention provides a photovoltaic system maximum power point tracing method. The method comprises the steps that 1, the power value P of a photovoltaic system is obtained in real time; 2, a limit marking value M is obtained according to the current MPPT disturbance period system power value P(k), the set limit power value PLimit and the limit power dead zone PStep; 3, the disturbance direction DFlag is determined according to the current MPPT disturbance period system power value P(k), the previous MPPT disturbance period system power value P(k-1) and the maximum power tracking dead zone PDead; 4, according to the formula: Vmmpt(k)=Vmppt(k-1)+M*DFlag*VStep, the maximum power disturbance voltage Vmppt (k) is obtained for maximum power tracking. By the adoption of the technical scheme, the photovoltaic system maximum power point tracing method has the advantages that full load and limiting output power of a photovoltaic inverter are smooth; the full-load power and limit power of the photovoltaic system are accurate, and the output power is stable; bus voltage is more stable, and a system loop is more reliable.

Description

technical field [0001] The invention relates to the field of photovoltaic power generation, in particular to a method for tracking the maximum power point of a photovoltaic system. Background technique [0002] attached figure 1 The MPPT algorithm of the traditional grid-connected inverter is generally controlled by the three-loop control operation of MPPT, voltage loop and current loop. When the input power exceeds the operating power of the equipment, it is common practice to add a limiter after the voltage loop. [0003] The specific implementation method of adding a limiter at the rear stage of the voltage loop is that when the power limit occurs, the MPPT loop is in an invalid state, the voltage loop is in a saturated state, and the desaturation rate of the voltage loop is uncontrollable, and the re-execution of MPPT is false tracking. , or re-tracking and other reliability risks; the accuracy of power limit is not high, the power is easy to change suddenly, the full l...

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Problems solved by technology

[0003] The specific implementation method of adding a limiter at the rear stage of the voltage loop is that when the power limit occurs, the MPPT loop is in an invalid state, the voltage loop is in a saturated state, and the desaturation rate of the voltage loop is uncontrollable, and the re-execution of MPPT is false tracking. , or re-tracking and other reliability risks; the accuracy of power limit is not high, the power is easy to change suddenly, the output power at full load, and the stability of power limit is not enough, etc.

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