Abstract
Aiming at the voltage distortion at the microgrid public connection point caused by nonlinear loads, a H∞ state feedback deadbeat repetitive control strategy is proposed to rectify the total harmonic distortion of the output voltage. Firstly, through establishing the state space of the repetitive controller, introducing state feedback, combining the H∞ control theory, and reformulating the system stability problem as a convex optimization problem with a set of linear matrix inequality (LMI) constraints to be solved, high stability control accuracy can be guaranteed and antiharmonic interference strengthened. Secondly, by introducing deadbeat control technology to improve the transient response speed of the system, changes in output voltage caused by load changes can be quickly compensated. Compared with the existing methods, the designed control method has the advantages of good stability, low harmonic content, and fast convergence speed, and the results are easier to verify. Finally, the simulation verifies the effectiveness of the proposed control strategy.
Highlights
In recent years, the microgrid has received wide attention for its unique form of maximizing the flexibility and advantages of distributed generation systems (DG) [1,2,3]
When the microgrid runs in the island mode, affected by the harmonic current generated by the nonlinear loads, the voltage at the Point of Common Coupling is distorted, leading to the degradation of the supply voltage quality and affecting the normal operation of the load and inverter [4,5,6]. erefore, it is of great practical significance to study a control strategy for reducing the total harmonic distortion (THD) of the output voltage in a state of satisfying the demand for nonlinear loads
Inspired by the above literature, in order to reduce the harmonic content of the PCC point voltage of the z-source inverter with nonlinear loads and achieve power sharing, this paper proposes a H∞ state feedback deadbeat repetitive control based on a parameter-optimized droop controller (H∞SFDBRC) strategy
Summary
The microgrid has received wide attention for its unique form of maximizing the flexibility and advantages of distributed generation systems (DG) [1,2,3]. Inspired by the above literature, in order to reduce the harmonic content of the PCC point voltage of the z-source inverter with nonlinear loads and achieve power sharing, this paper proposes a H∞ state feedback deadbeat repetitive control based on a parameter-optimized droop controller (H∞SFDBRC) strategy. Aiming at the disadvantages of traditional repetitive control being insufficient to deal with the time-varying uncertainty caused by load changes, the complexity of the solution process, and the difficulty of verifying conditions, this paper designs an improved repetitive control system that optimizes the design of the repetitive controller, constructs a state space expression formula, and introduces H∞ state feedback control, and the design of the repetitive controller is transformed into a convex optimization problem with a set of LMI constraints according to the Lyapunov functional; due to the inherent delay characteristics of repetitive control, in order to improve the transient performance of the system to obtain better antidisturbance characteristics, a new conceptual topology is proposed, with the deadbeat control technology, to provide fast dynamic response after the start of the system or during the large load step changes.
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