Active damping of LCL resonance with minimum sensor effort by means of a digital infinite impulse response filter

Dick, Christian; Richter, Sebastian A.; Rosekeit, Martin; Rolink, J Jérôme; Doncker, Rik W. De

doi:10.1109/epe.2007.4417362

Cited by 43 publications

(25 citation statements)

References 5 publications

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“…According to (9), only two parameter a 1 and a 2 associated with angular notch frequency ω n and the stop bandwidth Ω have to be designed. Since the magnitude and phase contribution of the LCL filter resonance will become small at the crossover frequency, the LCL filter response will be dominated by the series inductance [3].…”

Section: Current Controller Designmentioning

confidence: 99%

“…However, this method using a differentiator that may amplify high frequency noise. Nevertheless, a leadlag network or an Infinity Impulse Response (IIR) digital filter that behaves as a differentiator can be adopted in the case of a virtual resistor based active damping [7]- [9]. Moreover, a new control strategy by feeding back the weighted average value of currents flowing through the split filtering capacitors to the current controller is proposed in [10], and in [11] the feedback term is instead the grid or the inverter current.…”

Section: Introductionmentioning

confidence: 99%

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Digital notch filter based active damping for LCL filters

Yao

Yang

Zhang

et al. 2015

2015 IEEE Applied Power Electronics Conference and Exposition (APEC)

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-LCL filters are widely used in Pulse Width Modulation (PWM) inverters. However, it also introduces a pair of unstable resonant poles that may challenge the controller stability. The passive damping is a convenient possibility to tackle the resonance problem at the cost of system overall efficiency. In contrast, the active damping does not require any dissipation elements, and thus has become of increasing interest. As a result, a vast of active damping solutions have been reported, among which multi-loop control systems and additional sensors are necessary, leading to increased cost and complexity. In this paper, a notch filter based active damping without the requirement of additional sensors is proposed, where the inverter current is employed as the feedback variable. Firstly, a design method of the notch filter for active damping is presented. The entire system stability has then been investigated, which has revealed that negative variations of the resonant frequency can seriously affect the system stability. In order to make the controller more robust against grid impedance variations, the notch filter frequency is thus designed smaller than the LCL filter resonant frequency, which is done in the z-domain. Simulations and experiments are carried out to verify the proposed active damping method. Both results have confirmed that the notch filter based active damping can ensure the entire system stability in the case of resonances with a good system performance.

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Section: Current Controller Designmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Digital notch filter based active damping for LCL filters

Yao

Yang

Zhang

et al. 2015

2015 IEEE Applied Power Electronics Conference and Exposition (APEC)

View full text Add to dashboard Cite

show abstract

“…For i L2 , assuming H(s) = ks 2 , the peak can be damped [38][39][40][41], but the high-order derivative is hard to implement with high reliability in practice. Thus, a novel AD based on i L2 feedback is proposed in [39], by using a modified HPF with an optimized parameter design.…”

Section: Ad Subject To Different Options Of Single Statementioning

confidence: 99%

“…Filter-based AD improves stability by adding a digital filter next to the current controller [11][12][13][14][15][16]. For feedbackbased AD, the state used for feedback can be the capacitor current [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32], the capacitor voltage [33][34][35][36], the inverterside current [37], the grid current [38][39][40][41] or a combination of multiple states [42][43][44][45][46][47][48][49][50]. Among the feedback-based AD methods, proportional feedback of capacitor current is widely studied during last decade due to its simple implementation.…”

Section: Introductionmentioning

confidence: 99%

LCL-resonance damping strategies for grid-connected inverters with LCL filters: a comprehensive review

Xie

2017

J. Mod. Power Syst. Clean Energy

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Grid-connected LCL-filtered inverters are commonly used for distributed power generators. The LCL resonance should be treated properly. Recently, many strategies have been used to damp the resonance, but the relationships between different damping strategies have not been thoroughly investigated. Thus, this study analyses the essential mechanisms of LCL-resonance damping and reviews state-of-the-art resonance damping strategies. Existing resonance damping strategies are classified into those with single-state and multi-state feedback. Singlestate feedback strategies damp the LCL resonance using feedback of a voltage or current state at the resonance frequency. Multi-state feedback strategies are summarized as zero-placement and pole-placement strategies, where the zero-placement strategy configures the zeros of a novel state combined by multi-state feedback, while the poleplacement strategy aims to assign the closed-loop poles freely. Based on these mechanisms, an investigation of single-state and multi-state feedback is presented, including detailed comparisons of the existing strategies. Finally, some future research directions that can improve LCL-filtered inverter performance and minimize their implementation costs are summarized.

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“…However, the additional resistor will result in power loss and decrease the attenuation of the LCL filter [9]. In order to overcome these drawbacks, the concept of virtual resistor was proposed, which is called AD method [10], [11]. And an interesting control strategy based on the feedback of the splitting capacitor current was proposed in [12].…”

Section: Introductionmentioning

confidence: 99%

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.

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Active damping of LCL resonance with minimum sensor effort by means of a digital infinite impulse response filter

Cited by 43 publications

References 5 publications

Digital notch filter based active damping for LCL filters

Digital notch filter based active damping for LCL filters

LCL-resonance damping strategies for grid-connected inverters with LCL filters: a comprehensive review

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

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