Mechanism and elimination of harmonic current injection from single‐phase grid‐connected PWM converters

Abstract

The mechanism of harmonic current injection from single-phase grid-connected converters is comprehensively investigated. The measurable impacts from grid voltage, converter commutation, power factor, PWM modulation and control strategy are demonstrated on the harmonic current injection. According to the mechanism, a tailor-made control solution which employs a low pass voltage-loop filter and internal model principle-based hybrid current controller, is proposed to eliminate the harmonic current injection from the single-phase grid-connected converters. Experiments are performed to verify the validity of the mechanism and the proposed control method. It not only presents an effective tailor-made solution to the elimination of harmonic current injection from grid-connected power converters, but also provides a mechanism-based benchmark tool to further develop rational grid requirements on the harmonic injection levels in the grid integration of distributed generation units.

Frequency adaptive repetitive control of grid-connected inverters

“…The dynamics of the VSI with linear resistive load in Fig. 3 are given as [14][15] The objective of this controller for the inverter is to achieve power factor ≈ 1, low harmonic distortion sinusoidal feeding current and constant ripple free dc bus voltage . The corresponding sampled-data model of the Eq.…”

Selective harmonic control for power converters

“…m n e k e e mne (3) where km is the control gain for the corresponding SHC module Gnm(s); To has been defined previously; Tc is the phase-lead compensation time; n and m are integers with n > m ≥ 0. Moreover, since (4) in which h = 1, 2, … and m = 0, 1, 2, …, n-1.…”

“…Power converters demand optimal control strategies for harmonics compensation, which should achieve high control accuracy, fast transient response, good robustness, and easy implementation [1]. In practical applications, harmonics usually concentrate on some particular frequencies [3]. For example, in the n-pulse converter systems, nk±1-order (k = 1, 2, 3, …) harmonics dominate the Total Harmonic Distortion (THD).…”

Feedforward Harmonic Mitigation Strategy for Single-Phase Voltage Source Converter

“…One solution is to remove harmonic ripples in the voltage-loop and strengthen the antiharmonic disturbance capacity of current loop. Since harmonic ripples in the voltage-loop can be easily removed by employing low pass voltage filter [12] or notch filter [11], most studies focus on how to improve the performance of current-loop controller. Proportional Resonant (PR) controller [13,14], which has the advantages of simplicity and zero steady-state error for tracking a sinusoidal signal, is widely used for selective harmonic elimination.…”

“…RC presented a much slower dynamic response than PR and MRCs. To achieve a minimum steady-state error while maintaining a fast-transient 2 Journal of Electrical and Computer Engineering response, a hybrid controller by combining PR and RC has been proposed in [12,18]. However, the designation controller parameters were very complex to ensure the effectiveness of the control strategy and the stability of system.…”