Influence of Delay on System Stability and Delay Optimization of Grid-Connected Inverters With LCL Filter

Zou, Changyue; Liu, Bangyin; Duan, Shanxu; Li, Rui

doi:10.1109/tii.2014.2324492

Cited by 226 publications

(147 citation statements)

References 20 publications

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“…3, the grid current is conventionally used as a feedback variable of the current controller to regulate the current injected into the grid. An amplitude peak exists at the resonant frequency of the LCL filter, which would limit the design procedure of the current control-loop [6], [29]. The direct way to damp the LCL filter resonance is to insert a passive resistor in the inductor or capacitor of the LCL filter.…”

Section: B Passive Damping Under Grid Current Feedbackmentioning

confidence: 99%

“…Hence, there is a one-to-one correspondence between positive half of Nyquist plot and the open-loop bode plot, and the N+ and N-are two times the numbers of positive (from lower to upper) and negative (from upper to lower) crossings of (2k+1)π (k is an integer) in the open-loop bode plot in the frequency range with gains above 0 dB. For minimum phase system, i.e., P=0, the system is stable if N+=N- [29], [30].…”

Section: Virtual Resistance Based Active Damping (Ad) Strategymentioning

confidence: 99%

“…In order to mitigate the effect of the grid voltage on the quality of LCL-filter currents, a feed-forward loop of the grid voltage and the multiple resonant regulators at the harmonic frequencies of grid voltages are applied in the current loop. According to (15), setting 1-GN(s)G1(s) to zero and adopting approximate full compensation approach, the feed-forward function is derived as (19) Considering that derivative functions are difficult to be implemented and mainly for middle-and higher-frequency harmonics, and the noise amplification problems would reduce the stability margin, hence (19) is approximated by a first order low pass filter, and the higher order differential terms are neglected to avoid high frequency instabilities [29], [33]. As shown in Fig.…”

Section: And W(s)=g1(s)g2(s)mentioning

confidence: 99%

See 2 more Smart Citations

Stationary Frame Current Control Evaluations for Three-Phase Grid-Connected Inverters with PVR-based Active Damped LCL Filters

Han¹,

Shen²,

Guerrero³

2016

Journal of Power Electronics

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Grid-connected inverters (GCIs) with LCL output filter have the ability of attenuating high-frequency (HF) switching ripples. However, by using only grid-current control, the system is prone to resonances if it is not properly damped, and the current distortion would be amplified significantly under highly distorted grid conditions. In this paper, a synchronous reference frame equivalent proportional-integral (SRF-EPI) controller in αβ stationary frame using the parallel virtual resistance-based active damping (PVR -AD) strategy for grid-interfaced distributed generation (DG) systems to suppress the LCL resonance is proposed. Although both proportional-resonant (PR) controller in αβ stationary frame and PI controller in dq synchronous frame achieve zero steady-state error, the amplitude-and phase-frequency characteristics differ greatly from each other except for the reference tracking at fundamental frequency. Therefore, an accurate SRF-EPI controller in αβ stationary frame is established to achieve precise tracking accuracy. Moreover, the robustness, harmonic rejection capabilities, and influence of control delay are investigated by the Nyquist stability criterion when the PVR-based AD method is adopted. Furthermore, the grid voltage feed-forward and multiple PR controllers are integrated in the current loop to mitigate the current distortion introduced by the grid background distortion. Besides, the parameters design guidelines are presented to show the feasibility and effectiveness of the proposed strategy. Finally, simulation and experimental results are provided to validate the feasibility of the proposed control approach.

show abstract

Section: B Passive Damping Under Grid Current Feedbackmentioning

confidence: 99%

Section: Virtual Resistance Based Active Damping (Ad) Strategymentioning

confidence: 99%

Section: And W(s)=g1(s)g2(s)mentioning

confidence: 99%

See 1 more Smart Citation

Stationary Frame Current Control Evaluations for Three-Phase Grid-Connected Inverters with PVR-based Active Damped LCL Filters

Han¹,

Shen²,

Guerrero³

2016

Journal of Power Electronics

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show abstract

“…Instability will be led to by a time delay of the calculation and the PWM loop [31], [32]. In addition, the first-order delay is on behalf of the ZOH of the VSC current.…”

Section: A Model and Control Of The Systemmentioning

confidence: 99%

An Inductance Voltage Vector Control Strategy and Stability Study Based on Proportional Resonant Regulators under the Stationary αβ Frame for PWM Converters

Sun¹,

Wei²,

Gao³

et al. 2016

Journal of Power Electronics

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The mathematical model of a three phase PWM converter under the stationary αβ reference frame is deduced and constructed based on a Proportional-Resonant (PR) regulator, which can replace trigonometric function calculation, Park transformation, real-time detection of a Phase Locked Loop and feed-forward decoupling with the proposed accurate calculation of the inductance voltage vector. To avoid the parallel resonance of the LCL topology, the active damping method of the proportional capacitor-current feedback is employed. As to current vector error elimination, an optimized PR controller of the inner current loop is proposed with the zero-pole matching (ZPM) and cancellation method to configure the regulator. The impacts on system's characteristics and stability margin caused by the PR controller and control parameter variations in the inner-current loop are analyzed, and the correlations among active damping feedback coefficient, sampling and transport delay, and system robustness have been established. An equivalent model of the inner current loop is studied via the pole-zero locus along with the pole placement method and frequency response characteristics. Then, the parameter values of the control system are chosen according to their decisive roles and performance indicators. Finally, simulation and experimental results obtained while adopting the proposed method illustrated its feasibility and effectiveness, and the inner current loop achieved zero static error tracking with a good dynamic response and steady-state performance.

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“…The value of the delay also influences the stability and robustness of the system. Paper [25] investigates it in detail.…”

Section: Active Damping Without Additional Sensorsmentioning

confidence: 99%

The overview of damping methods for three-phase grid-tied inverter with LLCL-filter

Huang

Blaabjerg

Loh

2014

2014 16th European Conference on Power Electronics and Applications

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Influence of Delay on System Stability and Delay Optimization of Grid-Connected Inverters With LCL Filter

Cited by 226 publications

References 20 publications

Stationary Frame Current Control Evaluations for Three-Phase Grid-Connected Inverters with PVR-based Active Damped LCL Filters

Stationary Frame Current Control Evaluations for Three-Phase Grid-Connected Inverters with PVR-based Active Damped LCL Filters

An Inductance Voltage Vector Control Strategy and Stability Study Based on Proportional Resonant Regulators under the Stationary αβ Frame for PWM Converters

The overview of damping methods for three-phase grid-tied inverter with LLCL-filter

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