Active Damping Scheme for Leakage Current Reduction in Transformerless Three-Phase Grid-Connected PV Inverters

Giacomini, Julian C.; Michels, Leandro; Pinheiro, Humberto; Rech, Cassiano

doi:10.1109/tpel.2017.2711785

Cited by 55 publications

(37 citation statements)

References 34 publications

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“…However, the CM current circuiting path within the inverter is a LC circuit, in which a LC resonance frequency f r exists. The CM current resonance suppression methods for inverter using the ILCL filter are proposed in [13,14] to reduce the leakage current injected to gird. In [14], the authors use a PI controller to control the CM current to be zero by real-time adjusting zero-sequence duty ratio in space vector modulation (SVM) technique.…”

Section: Introductionmentioning

confidence: 99%

“…In [14], the authors use a PI controller to control the CM current to be zero by real-time adjusting zero-sequence duty ratio in space vector modulation (SVM) technique. In [13], the CM voltage which is injected into DM voltage to extend the inverter modulation index is controlled to suppression CM current resonance. Both the methods are useful and effective, and are based on a pair of small voltage vectors to adjust the CM voltage.…”

Section: Introductionmentioning

confidence: 99%

“…One of its characteristics is that there is no a pair of small voltage vectors, only one of the two small voltage vectors is used to compose the reference voltage vector. Since the CM AD methods in [13,14] are based on a pair of small voltage vectors to adjust the CM voltage, they cannot be used directly in DPWM application.…”

Section: Introductionmentioning

confidence: 99%

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A Virtual Negative Resistor Based Common Mode Current Resonance Suppression Method for Three-Level Grid-Tied Inverter with Discontinuous PWM

Zhou

Zhang

et al. 2020

Energies

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The output LC filter of a photovoltaic (PV) string three-level grid-tied inverter that connects the filter capacitor neutral point to dc-link capacitor neutral point can reduce the common-mode (CM) current injected to the grid by letting the CM current circulate within the inverter. However, the internal CM current may resonate because of the existence of the resonant frequency of the internal CM LC circuit. Compared with the traditional continuous pulse-width modulation (CPWM), the resonance can be worse if discontinuous pulse-width modulation (DPWM) is applied, for the zero sequence quantity of DPWM contains more harmonics than that of CPWM. In this paper, a virtual negative resistor based common mode current resonance suppression method for a three-level grid-tied inverter is proposed to overcome the CM current resonance problem in DPWM application. Different positions of the virtual negative resistor in the equivalent CM circuit with different feedback variables are analyzed theoretically. The virtual negative resistor connected in series with the inductor in the equivalent CM circuit is selected to damp the CM current resonance for simplification and damping performance. Different from the implementation in CPWM where a pair of small voltage vectors exist and are used to adjust the CM voltage directly, the proposed method for DPWM application is implemented indirectly by adding the CM adjustment quantity to differential-mode (DM) control quantity with appropriate coefficients. Depending on the sector of DM control quantity in the α β reference frame, the coefficients are calculated using one of three specific voltage vectors. Experimental results are given to demonstrate the effectiveness of theoretical analyses and the proposed method.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Virtual Negative Resistor Based Common Mode Current Resonance Suppression Method for Three-Level Grid-Tied Inverter with Discontinuous PWM

Zhou

Zhang

et al. 2020

Energies

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“…Although this technique is simple and reliable it can lead to additional power losses which are undesirable especially in high power applications. Alternatively, active damping techniques which integrated into the control function are adopted as they do not cause additional power dissipation and meanwhile provide flexible resonance frequency suppression [10][11][12]. However, active methods are sensitive to parameter uncertainties and their controllability is limited by the sampling frequency of the adopted controller [13].…”

Section: Introductionmentioning

confidence: 99%

Resonance Frequency Detection Technique in Gridconnected Inverter Systems Based on Double-order Digitalized Filter

Khalfalla¹,

Ethni

Kadandani³

et al. 2019

2019 10th International Renewable Energy Congress (IREC)

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Voltage source inverters (VSI) employed in distribution generation systems are usually interfaced to the grid via a low-pass LCL filter. This filter has a resonance frequency peak which can vary with respect to grid impedance, leading to instability issues if not properly suppressed. This paper proposes a resonance detection method based on a double-order digital band-pass filter. The digital filter extracts only the harmonic components around the resonance frequency from the injected grid current waveform while attenuating other frequencies outside its passband. The range of resonance frequencies has been determined by a grid impedance estimation technique. The detection method has been implemented in an experimental singlephase grid-connected inverter system and the practical results validate the effectiveness of the proposed method.

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“…The robustness of control system is improved. This is avail to inhibit the resonance produced by LCL filter [15,16].…”

Section: Introductionmentioning

confidence: 99%

The undamped control for PWM rectifier based on LCL filter

Fan¹,

Liang²,

Song³

et al. 2018

J. vibroeng.

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LCL filter is applied in PWM rectifier with the better filtering effect. Its inductor also plays a role in inhibiting the current impact, which not only has a good dynamic performance, but also reduces the system cost. However, LCL filter can cause resonance in certain frequency that affects system performance, as well as the parameters of LCL filter are hard to design. With analysis on the theory and characters of the fixed switching frequency control strategy, an undamped control strategy of three-phase voltage PWM rectifier based on LCL filtering is proposed for the resonance of LCL filter. The delay of system and the fixed switching frequency are used to control the damp. PI regulator's sampling time is adjusted to achieve the system stability. The structure of system is optimized by the design of simplified capacitance sensor. The simulation results show that this method has better dynamic performance, the current harmonic of grid side has reduced sharply, and the resonance of LCL filter has been inhibited effectively.

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Active Damping Scheme for Leakage Current Reduction in Transformerless Three-Phase Grid-Connected PV Inverters

Cited by 55 publications

References 34 publications

A Virtual Negative Resistor Based Common Mode Current Resonance Suppression Method for Three-Level Grid-Tied Inverter with Discontinuous PWM

A Virtual Negative Resistor Based Common Mode Current Resonance Suppression Method for Three-Level Grid-Tied Inverter with Discontinuous PWM

Resonance Frequency Detection Technique in Gridconnected Inverter Systems Based on Double-order Digitalized Filter

The undamped control for PWM rectifier based on LCL filter

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