d-q axis decoupling parameter identification strategy for the grid-connected inverter of photovoltaic generation system

This paper presents a parameter identification strategy based on the d-q axis decoupling for a typical PV inverter, which contains double loop control model. This strategy can reduce the order of the model and improve the accuracy of the identification. Firstly, a typical PV grid-connected system model is built up, in which the inverter controller is based on the d-q axis decoupling current control. It´s a double loop control including the outer voltage loop and the inner current loop, and the maximum power point tracking (MPPT). Secondly, we take the system as a research object, deduce the decoupling characteristics of the d-q axis parameters of the inverter controller through theoretical calculation, and reduce the order of the inverter model. Lastly, we get disturbance data through the simulation of control target reference step, and identify the parameters with the nonlinear damped least square method. The experimental results show that: the error is less than 5% in the dominant parameters of the inverter model, which proves the correctness and validity of the identification strategy.