Harmonics and Stability Analysis of Single-Phase Grid-Connected Inverters in Distributed Power Generation Systems Considering Phase-Locked Loop Impact

Xu, Jinming; Qian, Qiang; Zhang, Binfeng; Xie, Shaojun

doi:10.1109/tste.2019.2893679

Cited by 96 publications

(63 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…1(c) for showing the impact institutively. If other robust AD and current controllers are used, the similar phenomenon may be observed because the PLL dominates the behaviors of the inverter system at the very low frequencies [23], [26].…”

Section: B Instability Of Pll For the High Grid Impedancementioning

confidence: 73%

“…However, such conclusion is not convincing, because the PLL impact is not considered in the low frequency range. In (6), the PLL impact, i.e., term T PLL (s)G close (s), can be eased if I ref reduces, as the study in [26] also tells. Thus, in this study, the rated power situation is especially concerned and the value of I ref is I rated , i.e., 1.414P rated /U g .…”

Section: B Instability Of Pll For the High Grid Impedancementioning

confidence: 99%

“…As studied in [23] and [25], the PLL affects the inverter output impedance at the very low frequencies (i.e., from the fundamental frequency to several hundreds of Hz). Hence, for a wide grid impedance variation, harmonics around the PLL bandwidth (i.e., within several hundreds of Hz) can still be aroused [26]. Although an adaptive feedforward is proposed in [23] for enlarging the phase margin (PM), the improvement (only 20 • at 400 Hz, much higher than PLL bandwidth) is marginal and the online estimation of the grid impedance is required.…”

Section: Introductionmentioning

confidence: 99%

“…As analyzed, harmonics at the very low frequencies may be triggered due to the phase-locked function (even if the robust AD and controller are used), so that it is required to improve the grid synchronizations [26]. In [27], the power synchronization for the three-phase system is proposed for the weak grid application.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Robustness Improvement of Single-Phase Inverters Under Weak Grid Cases by Adding Grid Current Feedforward in Delay-Based Phase-Locked Loop

Bian

Qian

et al. 2020

IEEE Access

Self Cite

View full text Add to dashboard Cite

For inverters, a phase-locked loop (PLL) is usually needed for the grid synchronization. Typically, for the single-phase inverters, the orthogonal-signal-generators based PLLs (e.g., delay-based PLL) can be used. However, if the grid at the point of common coupling (PCC) exhibits a large grid impedance, the inverter may not work well or even be unstable. In order to work satisfactorily in the very weak grid, this study aims to formulate a robust PLL. At first, by modeling the inverter output impedance and considering the frequency coupling effect, the stability of the typical delay-based PLL has been analyzed and the reason for the performance degradation has been explained. Then, based on analyzing the differences of PLL blocks under different PCC conditions, the robust PLL with the grid current feedforward is discussed. Compared with the typical PLL, the improvement of the system behaviors in the weak grid cases is mainly attributed to the extra term on the numerator of output impedance, which is introduced by the current feedforward of the proposed PLL. The selection of control parameters has been emphasized for maintaining the high robustness. At last, selected comparative waveforms have verified that the single-phase inverter can perform well even with the large grid impedance, without the grid impedance estimation.

show abstract

Section: B Instability Of Pll For the High Grid Impedancementioning

confidence: 73%

Section: B Instability Of Pll For the High Grid Impedancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Robustness Improvement of Single-Phase Inverters Under Weak Grid Cases by Adding Grid Current Feedforward in Delay-Based Phase-Locked Loop

Bian

Qian

et al. 2020

IEEE Access

Self Cite

View full text Add to dashboard Cite

show abstract

“…The output impedance can also be increased by the grid voltage full feedforward scheme, but its suppression effect of the current harmonics is weakened by the system delay which is inevitable for the digital control system [4]. In addition, due to its additional negative phase shift, the stability of the inverter system is also reduced [4], [18]− [20].…”

Section: Introductionmentioning

confidence: 99%

Control Scheme and Performance Analysis of Dual-Frequency Single-Phase Grid-Connected Inverter Interfaced With Weak and Distorted Grids

Yang

Zhang

et al. 2020

IEEE Access

View full text Add to dashboard Cite

Grid impedance variation and voltage harmonics may cause instability of the grid-connected inverter system and reduce the grid current quality under weak grid. Switching losses and electromagnetic interference of inverter can be reduced by using lower switching frequency. However, it is a challenging task to achieve stable operation of LCL-type grid-connected inverter using the active damping method at the low switching frequency. In this paper, an improved control strategy is proposed for the dual-frequency inverter, which contains a power inverter and an auxiliary converter. For the proposed control strategy, the ability to suppress the influence of the grid voltage harmonics and the robustness against grid impedance variation are analyzed. In order to reduce the switching losses, the electrical energy is delivered to the power grid through the power inverter at a low switching frequency. By using the switching ripple compensation method and the grid voltage feedforward scheme, the switching current ripple caused by the power inverter and the current harmonics caused by the grid voltage harmonics can be suppressed. Since the filters used in the proposed inverter are all L type filters, the system stability is guaranteed under weak grid. The simulation and experimental results are provided to verify the effectiveness of the proposed gridconnected inverter system under weak grid. INDEX TERMS Dual-frequency inverter, grid-connected inverter, grid impedance, harmonics, stability analysis, weak grid.

show abstract

Compensation of power quality problems throughUPQC‐Susing enhanced complex coefficient filter

Alam

Arya

2021

Int Trans Electr Energ Syst

View full text Add to dashboard Cite

Harmonics and Stability Analysis of Single-Phase Grid-Connected Inverters in Distributed Power Generation Systems Considering Phase-Locked Loop Impact

Cited by 96 publications

References 37 publications

Robustness Improvement of Single-Phase Inverters Under Weak Grid Cases by Adding Grid Current Feedforward in Delay-Based Phase-Locked Loop

Robustness Improvement of Single-Phase Inverters Under Weak Grid Cases by Adding Grid Current Feedforward in Delay-Based Phase-Locked Loop

Control Scheme and Performance Analysis of Dual-Frequency Single-Phase Grid-Connected Inverter Interfaced With Weak and Distorted Grids

Compensation of power quality problems throughUPQC‐Susing enhanced complex coefficient filter

Contact Info

Product

Resources

About