Analysis and Verification of Compound SRFPI-LADRC Strategy for an Off-Grid Single-Phase Inverter

Abstract

Summary. The linear active disturbance rejection control (LADRC) is mainly applied for tracking a step signal, and it is inadequate to realize satisfactory performance in the control of a single-phase inverter whose reference signal is sinusoidal. In this paper, an improved voltage control strategy based on compound synchronous reference frame proportional-integral (SRFPI) control and LADRC is proposed. The SRFPI and LADRC remain relatively independent without complicating the control parameter design. Detailed theoretical analyses on the compound strategy and its performance are presented, indicating that it inherits the advantages of the two controllers. Moreover, contrast experiments are carried out to verify the feasibility and superiority of the proposed control strategy. The results show that the system achieves a small steady-state error, voltage tracking error, fast transient response, and low total harmonic distortion (THD) when feeding a highly nonlinear load.

SRFPI-LADRC Based Control Strategy for Off-Grid Single-Phase Inverter: Design, Analysis, and Verification

“…Table 4 provides a summary of the experimental results for several test cases, including THDu, tracking error and output voltage (RMS value). The measuring results of the SRFPI-LADRC strategy proposed in [22], which has no differential voltage reference for LADRC, are listed as well for comparison. To make the comparison persuasive, the parameters of the overlapping parts of these methods stay consistent intentionally.…”

“…In our earlier work, to combine the advantages of SRFPI and LADRC, a novel singlephase inverter control technique based on cascade connected SRFPI and LADRC [22] is developed, where the first output signal of SRFPI is taken as the voltage reference of LADRC. Prompted by the fact that the SRFPI, which outputs two orthogonal signals, naturally provides a voltage reference and a differential voltage reference, the second output signal of SRFPI is utilized as the differential voltage reference of LADRC to further improve the system performance in [23].…”