Photovoltaic inverter service life evaluation method considering photovoltaic module configuration and power tracking limit value influence

Abstract

The invention discloses a photovoltaic inverter service life evaluation method considering photovoltaic module configuration and power tracking control, and belongs to the technical field of power electronic application. The photovoltaic inverter service life evaluation method comprises the following steps: S1, establishing a mathematical model of a photovoltaic system and extracting a task profile; s2, changing photovoltaic array configuration and a power tracking limit value; s3, calculating power loss considering photovoltaic array configuration and a power tracking limit value; s4, calculating the junction temperature of the IGBT and the capacitor; s5, extracting a junction temperature profile; s6, calculating the service life of the IGBT and the capacitor after the photovoltaic array configuration and the power tracking limit value change; s7, comparing the service life calculation values of the IGBT and the capacitor in the photovoltaic inverter, and taking the smaller service life value as the service life of the photovoltaic inverter; and S8, calculating the service life value of the photovoltaic inverter under different photovoltaic array configurations and power tracking limit values. According to the method, the accuracy of photovoltaic inverter service life evaluation is improved, and the method has engineering practical value.

Description

technical field [0001] The invention belongs to the technical field of power electronics applications, and in particular relates to a photovoltaic inverter life evaluation method considering the influence of photovoltaic module configuration and power tracking limit value. Background technique [0002] Photovoltaic systems have accounted for the largest share of all renewable energy investment for nearly a decade, and as PV module and installation costs fall, a greater proportion will be connected. Photovoltaic inverter is a key component of photovoltaic system. In order to reduce the cost of photovoltaic power generation and improve the competitiveness of solar power generation, higher requirements are put forward for the reliability of photovoltaic inverter. However, as an indicator for evaluating the cost of a photovoltaic system, the two goals of maximum power generation and the actual life of the inverter are mutually restrictive. In this case, special consideration nee...

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Problems solved by technology

However, with the continuous growth of photovoltaic grid-connected systems, the power grid is facing many challenges. Even if the MPPT mode is maintained within the rated power range, system overvoltage, serious degradation of switching devices, high light rejection rate and load fluctuations will occur. Therefore, the traditional MPPT can no longer meet the requirements. For this reason, a variable power point tracking (Variable Power Point Tracking, VPPT) control method with variable tracking direction of the photovoltaic operating point is proposed. By adopting variable power tracking limit The value method solves the problem of over-design or under-design of the inverter and improves the reliability of the inverter

[0005] The above research found that in the photovoltaic system, the configuration of photovoltaic modules and the limit value of power tracking are not strictly in accordance with the 1:1 configuration, but will be changed according to the actual operating conditions, and the current life evaluation method of photovoltaic inverters does not take Taking these changes into consideration, there will be large errors if the evaluation is still carried out according to the original method. Therefore, the present invention proposes a photovoltaic inverter life evaluation method that considers the influence of photovoltaic module configuration and limited power tracking limit, which can be more accurate Lifetime assessment of photovoltaic inverters

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