Abstract
Compared with traditional single L-type filters, LCL filters for three-phase grid-connected inverters can suppress the switching voltage and current ripple better, thus reducing harmonic pollution to the power grid. However, the increase in system order also makes it difficult to control the system. To solve the problems of complex model and severe coupling of LCL filter in the d-q coordinate system, the decoupling control of current inner loop by the linear extended state observer (LESO) was proposed based on the analysis of mathematical model of grid-connected inverter with an LCL filter. Moreover, given the relatively low speed of system response in traditional active disturbance rejection control (ADRC), the tracking differentiator (TD) was removed, and the nonlinear control law was replaced with the PI controller. Compared with the conventional feedforward decoupling method, the reasonably designed LESO used in this work can not only realize decoupling control of the original system to improve its performance, but also save the cost of sensor and achieve a better decoupling effect. The effectiveness of the proposed current control strategy was verified by experimental results.
Highlights
Recent years, energy consumption and environmental issues promote the rapid development of renewable energy power generation technologies
Once these harmonics are injected into the grid, they will increase the extra loss of the system, result in protection device malfunction in the power system by causing electromagnetic interference, The associate editor coordinating the review of this manuscript and approving it for publication was Zhixiang Zou
Combining the advantages of traditional control and active disturbance rejection control (ADRC), this paper proposes a novel decoupling control method of current loop by the PI controller together with linear extended state observer (LESO) based on the analysis of mathematical model of grid-connected inverter with an LCL filter
Summary
Energy consumption and environmental issues promote the rapid development of renewable energy power generation technologies. Based on the feedback linearization theory, the decoupling scheme designed by Khajehoddin et al [10] and Bao et al [11] could effectively improve the quality of gridside current. He et al [12] proposed a reduced order method to solve the problem of grid-side current control in LCL filter. Combining the advantages of traditional control and ADRC, this paper proposes a novel decoupling control method of current loop by the PI controller together with linear extended state observer (LESO) based on the analysis of mathematical model of grid-connected inverter with an LCL filter. According to KVL and KCL, the mathematical model of LCL filter in the d-q coordinate system can be obtained: di1d
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