Abstract
In this paper, a robust DC-link voltage control scheme is proposed to improve the tolerance of photovoltaic (PV) grid-connected inverter to disturbances. The sensitive characteristic of the DC-link voltage complicates the dynamics of the inverter control system and limits its overall performance, especially when uncertain disturbances are considered. To cope with this issue, a voltage controller based on the linear active disturbance rejection control (LADRC) is designed. By exploring the principle of deviation regulation, an improved linear extended state observer (LESO) is established to ensure that the total disturbance can be estimated in a relatively timely manner. The linear state error feedback (LSEF) control law is generated to compensate for the total disturbance, which reduces the plant to approximate the canonical cascaded double integrator. The stability and disturbance rejection capability of the improved LADRC are further analyzed in frequency domain. Finally, theoretical analysis and experimental results confirm the feasibility of the proposed control scheme.
Highlights
In recent years, with the increasing depletion of traditional energy sources, renewable energy power generation has become the mainstream of industrial applications
A DC-link voltage control strategy based on improved linear active disturbance rejection control (LADRC) was proposed for grid-connected inverter in this paper
By describing the stability problem and power relationship of the DC-link, the voltage outer loop is modeled. Both theoretical analysis and experimental results prove that the proposed voltage control scheme achieves better control performance, either during the start-up process or operating conditions variation
Summary
With the increasing depletion of traditional energy sources, renewable energy power generation has become the mainstream of industrial applications. Zhou et al.: DC-Link Voltage Research of PV Grid-Connected Inverter Using Improved ADRC scheme is proposed in [12] to improve the robustness of the DC-link voltage This strategy, needs to provide the parameter of the load resistance, which is undesirable from the practicality. In [26], a robust active damping method based on LADRC was proposed to improve the performance of an inverter connected to the grid through an inductor-capacitorinductance (LCL) filter. An improved LADRC-based DC-link voltage controller is proposed for the PV grid-connected system, which is dedicated to enhancing the robustness when disturbed. The rear stage, whose primary objective is to achieve the active power balance and grid connection, comprises a three-phase voltage source inverter, a low-pass filter, and the grid [7]. Strong robustness against unknown disturbances must be a key attribute in DC-link voltage control to guarantee the regular operation of the system
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