Control Strategy for Three-Phase Grid-Connected Converters under Unbalanced and Distorted Grid Voltages Using Composite Observers

Abstract

This paper proposes a novel scheme for the current controller for the grid-side converter (GSC) of permanent-magnet synchronous generator (PMSG) wind turbines to eliminate the high-order harmonics in the grid currents under grid voltage disturbances. The voltage unbalance and harmonics in three-phase systems cause grid current distortions. In order to mitigate the input current distortions, multi-loop current controllers are applied, where the positive-sequence component is regulated by proportional-integral (PI) controllers, and the negative-sequence and high-order harmonic components are regulated by proportional-resonance (PR) controllers. For extracting the positive/negative-sequence and harmonic components of the grid voltages and currents without a phase delay or magnitude reduction, composite observers are applied, which give faster and more precise estimation results. In addition, an active damping method using PR controllers to damp the grid current component of the resonant frequency is employed to improve the operating stability of VSCs with inductor-capacitor-inductor (LCL) filters. The validity of the proposed method is verified by simulation and experimental results.

Harmonic compensation capability‐based coordinated control for hybrid wind farms under distorted grid voltage conditions

“…However, due to the large number of applications of power electronic devices and non‐linear loads, the grid voltage usually contains harmonic components [4, 5]. Under this conditions, the output current of the hybrid wind farms will be seriously distorted, and the instantaneous powers and electromagnetic torque may oscillate, which could severely affect the operation of the hybrid wind farms [6, 7]. Consequently, the operation principles and coordination strategy of the hybrid wind farms should be further analysed and investigated under distorted grid voltage conditions.…”

IDA-PBC controller design for grid connected Front End Converters under non-ideal grid conditions

“…For the case in which grid voltage includes unbalance and distortion, Nguyen et al [15], tries to solve this problem using a multi-loop current controller that regulates positive-sequence currents, negative-sequence currents and fifth and seventh harmonic, separately, using PI and resonant controllers. A combination of PI and a bank of resonant controllers is also proposed in Trinh and Lee [16].…”

Pattern Recognition of Monitored Waveforms from Power Supplies Feeding High-Speed Rail Systems

“…Mishra et al [9] presented an S-Transform based probabilistic neural network (PNN) classifier for the recognition of PQ disturbances, which can reduce the features of the disturbance signal and needs less memory space and PNN learning time. To eliminate the high-order harmonics in the grid currents under grid voltage disturbances, Nguyen et al [10] proposed a novel scheme for the current controller of the grid-side converter of a permanent-magnet synchronous generator. Huang et al [11] proposed a chaos synchronization (CS)-based detector for PQ disturbance classification, and realized a CS-based detector to track the dynamic errors from the fundamental and distorted signals.…”

“…The few research studies on the PQ problems of HSR mainly concentrate on the upgrading and transformation of the related technical and PQ issues it caused [5][6][7]; while the research on PQ disturbances is relatively mature [9][10][11][12][13]. Mishra et al [9] presented an S-Transform based probabilistic neural network (PNN) classifier for the recognition of PQ disturbances, which can reduce the features of the disturbance signal and needs less memory space and PNN learning time.…”