Sliding-Mode Observer Based Voltage-Sensorless Model Predictive Power Control of PWM Rectifier Under Unbalanced Grid Conditions

Abstract

Sydney. He focused on fundamental research on mechanical vibration, multi-body system dynamics and its applications to complex machines and vehicular systems. He developed advanced models and numerical schemes for simulating gear shift in powertrains with AT, MT and CVTs and for dynamic analysis of vehicles fitted with advanced suspensions.

Frequency Adaptive Current Control Scheme for Grid-connected Inverter without Grid Voltage Sensors Based on Gradient Steepest Descent Method

“…The sensorless control scheme should be able to produce desirable harmonic-free injected currents by adapting to the grid frequency deviation to meet the requirement of robustness against both the distorted grid and frequency variation in the grid-connected inverter. The study in [16] presents a voltage sensorless scheme based on the sliding mode observer to control a three-phase voltage source rectifier under unbalanced grid conditions. Though a good performance is achieved under several adverse test conditions by this approach, the grid frequency that was obtained by the conventional phase-locked loop (PLL) still has long transient time under a sudden frequency step change.…”

Finite Control Set Model Predictive Control for an LCL-Filtered Grid-Tied Inverter with Full Status Estimations under Unbalanced Grid Voltage

“…However, these control schemes are usually designed under the ideal grid voltage condition, and the negative effects caused by the negative sequence component (NSC) are not considered. Therefore, under the unbalanced grid voltage condition, the feasibilities of current sensorless control schemes need be further verified [17].To alleviate the adverse effects of the unbalanced grid voltage, the positive sequence component (PSC) and the NSC of the grid voltages are required to be separated first, and then applied in the control algorithm [18][19][20][21]. In [18], for the distributed generation inverter, a flexible reference generator based on positive and negative active and reactive powers, was proposed to keep feeding the grid and support the grid voltage under the unbalanced grid voltage condition.…”

“…In [20], Suul et al proposed a virtual-flux-based method for the voltage-sensorless grid synchronization under variable grid frequency and unbalanced voltage conditions, integrating the functions of frequency-adaptive bandpass filtering, the virtual flux estimation, and the sequence separation into one operation. In [21], Yang et al proposed a sliding-mode grid voltage observer for the voltage-sensorless operation under an unbalanced network, separating the PSC and NSC inherently. The variables of methods proposed in [18,19] are all based on the full state measurements, while only one kind of sensor is reduced in [20,21].…”

“…In [21], Yang et al proposed a sliding-mode grid voltage observer for the voltage-sensorless operation under an unbalanced network, separating the PSC and NSC inherently. The variables of methods proposed in [18,19] are all based on the full state measurements, while only one kind of sensor is reduced in [20,21]. Note that it is of great challenge for the LCL-filtered grid-tied inverter to further reduce the number of sensors, especially under the unbalanced grid voltage condition.In this paper, a novel FCS-MPC approach for the control of an LCL-filtered grid-tied inverter using merely grid-injected current sensors under the unbalanced grid voltage condition has been presented.…”

“…To alleviate the adverse effects of the unbalanced grid voltage, the positive sequence component (PSC) and the NSC of the grid voltages are required to be separated first, and then applied in the control algorithm [18][19][20][21]. In [18], for the distributed generation inverter, a flexible reference generator based on positive and negative active and reactive powers, was proposed to keep feeding the grid and support the grid voltage under the unbalanced grid voltage condition.…”