An Adaptive Digital-Control Scheme for Improved Active Power Filtering Under Distorted Grid Conditions

Hogan, Diarmaid J.; González-Espín, Fran; Hayes, John G.; Lightbody, Gordon; Foley, Raymond

doi:10.1109/tie.2017.2726992

Cited by 71 publications

(33 citation statements)

References 30 publications

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“…An input voltage peak detector is used to approximate the value of v P CC,1 to v P CC,1 ≈ V P CC,peak sin(ωt). Different approaches, such as the zero-phase detector circuit in [53] or PLLs can be applied here, the last one being the preferred approach to achieve immunity to input voltage distortion [54], [55], as is included in certain PFC proposals [56], [57]. Hence, (30) is rewritten as…”

Section: Implementation Of the Pqe Controllermentioning

confidence: 99%

Power Quality Enhancement in Residential Smart Grids Through Power Factor Correction Stages

López

Azcondo

Pigazo

2018

IEEE Trans. Ind. Electron.

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The proliferation of non-linear loads and the increasing penetration of Distributed Energy Resources (DER) in Medium-Voltage (MV) and Low-Voltage (LV) distribution grids, make it more difficult to maintain the power quality levels in residential electrical grids, especially in the case of weak grids. Most household appliances contain a conventional Power Factor Corrector (PFC) rectifier, which maximizes the load Power Factor (PF) but does not contribute to the regulation of the voltage Total Harmonic Distortion (T HDV) in residential electrical grids. This manuscript proposes a modification for PFC controllers by adapting the operation mode depending on the measured T HDV. As a result, the PFCs operate either in a low current Total Harmonic Distortion (T HDI) mode or in the conventional resistor emulator mode and contribute to the regulation of the T HDV and the P F at the distribution feeders. To prove the concept, the modification is applied to a current sensorless Non-Linear Controller (NLC) applied to a single-phase Boost rectifier. Experimental results show its performance in a PFC front-end stage operating in Continuous Conduction Mode (CCM) connected to the grid with different T HDV .

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Section: Implementation Of the Pqe Controllermentioning

confidence: 99%

Power Quality Enhancement in Residential Smart Grids Through Power Factor Correction Stages

López

Azcondo

Pigazo

2018

IEEE Trans. Ind. Electron.

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“…• 100 (30) where the V − o rms is the rms values of the negative of the DG output voltage and the V + o rms is the rms values of the positive of the DG output voltage.…”

Section: Voltage Compensationmentioning

confidence: 99%

“…Several studies, such as References [27][28][29][30][31][32] have proposed to use the APFs and UPQC for the cancellation of the voltage and current harmonics in MG. Along this line, Cheng et al [27] proposed a control strategy using distributed APFs to weaken the voltage harmonics of the system.…”

Section: Introductionmentioning

confidence: 99%

“…The results show that the UPQC can compensate for the voltage and current disturbance at the Point of Common Coupling (PCC) during interconnected mode. It is used in [30] as a flexible digital-control design in a three-phase APF, which is used in variable-frequency grid conditions. The design consisted of a grid-frequency flexible resonant current adjuster and an upgraded synchronous-reference-frame phase-locked loop.…”

Section: Introductionmentioning

confidence: 99%

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A Harmonic Compensation Strategy in a Grid-Connected Photovoltaic System Using Zero-Sequence Control

et al. 2018

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Mitigation of harmonics for a grid-connected inverter is an important element to stabilize the control and the quality of current injected into the grid. This paper deals with the control method of a three-phase Grid-Connected Inverter (GCI) Photovoltaic (PV) system, which is based on the zero-sequence current adjuster. The proposed method is capable of removing the harmonic current and voltage without using any active and passive filters and without the knowledge of the microgrid topology and also impedances of distribution bands and loading conditions. This concept is adopted for the control of a Distributed Generator (DG) in the form of grid-connected inverter. The proposed control can be applied to the grid connected inverter of the PV. The fast dynamic response, simple design, stability, and fast transient response are the new main features of the proposed design. This paper also analyzes the circuit configuration effects on the grid connected inverter capability. The proposed control is used to demonstrate the improved stability and performance.

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“…However, to ensure a negligible frequency deviation during the discretization of the PR controller transfer function through the bilinear transformation, this scheme uses the relatively high switching frequency of 20 kHz. To improve the estimation performance of the grid phase and frequency in the presence of voltage harmonics, the study in reference [14] proposed an adaptive digital control scheme for three-phase active power filtering comprising an enhanced SRF phase-locked loop (PLL). This research work demonstrates the improvement in grid phase and frequency estimation as well as in current control performance under adverse grid conditions by means of the online updating of resonance parameters.…”

Section: Introductionmentioning

confidence: 99%

Frequency-Adaptive Current Controller Design Based on LQR State Feedback Control for a Grid-Connected Inverter under Distorted Grid

2018

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This paper proposes a frequency-adaptive current control design for a grid-connected inverter with an inductive–capacitive–inductive (LCL) filter to overcome the issues relating to both the harmonic distortion and frequency variation in the grid voltage. The current control scheme consists of full-state feedback control to stabilize the system and integral control terms to track the reference in the presence of disturbance and uncertainty. In addition, the current controller is augmented with resonant control terms to mitigate the harmonic component. The control scheme is implemented in the synchronous reference frame (SRF) to effectively compensate two harmonic orders at the same time by using only one resonant term. Moreover, to tackle the frequency variation issue in grid voltage, the frequency information which is extracted from the phase-locked loop (PLL) block is processed by a moving average filter (MAF) for the purpose of eliminating the frequency fluctuation caused by the harmonically distorted grid voltage. The filtered frequency information is employed to synthesize the resonant controller, even in the environment of frequency variation. To implement full-state feedback control for a grid-connected inverter with an LCL filter, all the state variables should be available. However, the increase in number of sensing devices leads to the rise of cost and complexity for hardware implementation. To overcome this challenge, a discrete-time full-state current observer is introduced to estimate all the system states. When the grid frequency is subject to variation, the discrete-time implementation of the observer in the SRF requires an online discretization process because the system matrix in the SRF includes frequency information. This results in a heavy computational burden for the controller. To resolve such a difficulty, a discrete-time observer in the stationary reference frame is employed in the proposed scheme. In the stationary frame, the discretization of the system model can be accomplished with a simple offline method even in the presence of frequency variation since the system matrix does not include the frequency. To select desirable gains for the full-state feedback controller and full-state observer, an optimal linear quadratic control approach is applied. To validate the practical effectiveness of the proposed frequency-adaptive control, simulation and experimental results are presented.

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An Adaptive Digital-Control Scheme for Improved Active Power Filtering Under Distorted Grid Conditions

Cited by 71 publications

References 30 publications

Power Quality Enhancement in Residential Smart Grids Through Power Factor Correction Stages

Power Quality Enhancement in Residential Smart Grids Through Power Factor Correction Stages

A Harmonic Compensation Strategy in a Grid-Connected Photovoltaic System Using Zero-Sequence Control

Frequency-Adaptive Current Controller Design Based on LQR State Feedback Control for a Grid-Connected Inverter under Distorted Grid

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