Fault Ride-Through Control of Medium-Voltage Converters With LCL Filter in Distributed Generation Systems

Meyer, Robert K.; Zlotnik, Alexander; Mertens, Axel

doi:10.1109/tia.2014.2304589

Cited by 34 publications

(14 citation statements)

References 18 publications

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“…Under the assumption that the active filter or the power compensator injects instantaneously the compensation reference of each harmonic n (ideal subtraction, with no delay), then (22) and (23) can be substituted into (21), and the resulting phase a signal after compensating with the corresponding reference of the harmonic n is…”

Section: Reference Generator Scheme With One Lpfmentioning

confidence: 99%

Generation of new harmonics caused by the processing of DQ transformation in power quality compensators

González

Cárdenas

Álvarez-Salas

2018

Int Trans Electr Energ Syst

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Summary An event appearing when executing the DQ transformation to get the compensation references in power quality compensators is presented in this work, where new harmonics that had not existed initially are generated and inserted to the electric system. Although the new harmonics have low magnitude, they exist, and correct processing of control techniques should be guaranteed to avoid amplifying their magnitudes. The new harmonics are produced by the filtering act in the dq frame, since filter is not ideal. The appearance of the new harmonics occurs only if the d component is filtered to isolate the dc term in the dq reference frame. But, if both d and q signals are filtered, no new harmonics are generated. This phenomenon is studied for general unbalanced systems; detailed analyses, proofs, simulation, and experimental tests are presented to validate the existence of the generation of new harmonics.

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Section: Reference Generator Scheme With One Lpfmentioning

confidence: 99%

Generation of new harmonics caused by the processing of DQ transformation in power quality compensators

González

Cárdenas

Álvarez-Salas

2018

Int Trans Electr Energ Syst

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“…The requirements are different regarding a fault duration and the injection quantity of the reactive power depending on the voltage drop ratio. This requirement ensures that the system connected to the grid operates properly when the grid voltage drops [12][13][14][15][16][17][18]. The LVRT requirement contributes to the recovery of the grid voltage by supplying the reactive current in the designated voltage range.…”

Section: Introductionmentioning

confidence: 99%

Low-Voltage Ride-Through Control Strategy for a Grid-Connected Energy Storage System

Bak

Lee

2018

Applied Sciences

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This paper presents a low-voltage ride-through (LVRT) control strategy for grid-connected energy storage systems (ESSs). In the past, researchers have investigated the LVRT control strategies to apply them to wind power generation (WPG) and solar energy generation (SEG) systems. Regardless of the energy source, the main purpose of the LVRT control strategies is to inject reactive power into the grid depending on the grid-code regulations using the grid-side inverter; the proposed LVRT control strategy for grid-connected ESSs also has the same purpose. However, unlike the WPG and SEG systems having unidirectional power flow, grid-connected ESSs have a bidirectional power flow. Therefore, the charging condition of the grid-connected ESSs should be considered for the LVRT control strategy. The proposed LVRT control strategy for grid-connected ESSs determines the injection quantity of the active and reactive currents, and the strategy depends on the voltage drop ratio of the three-phase grid. Additionally, in this paper, we analyzed the variations of the point of common coupling (PCC) voltage depending on the phase of the reactive current during the charging and discharging conditions. The validity of the proposed LVRT control strategy is verified and the variations of the PCC voltage of the grid-connected ESS are analyzed by simulation and experimental results.

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“…The main drawback of the CCF scheme is that, even if the controlled converter currents are achieved sinusoidal, the line currents are distorted by the LCL's capacitor currents. Hence, the GCF [5][6][7][8] emerged to solve the distortion problem of the CCF. It is usually implemented using a proportional resonant (PR) control with enough bandwidth and number of resonances to ensure the rejection of the grid current harmonics, resulting in line currents with low THD factor.…”

Section: Introductionmentioning

confidence: 99%

Capacitive Emulation Using Predictive Current Control in LCL-Filtered Grid-Connected Converters to Mitigate Grid Current Distortion

Espı́

Castelló

2018

Energies

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This paper presents an improvement of the capacitive emulation (CE) method to reduce the line current distortion caused by grid-tied LCL-filtered converters. In these cases, the grid voltage is applied to the LCL's capacitor, which generates a distorted capacitor current that pollutes the line. The CE method consists in controlling the converter currents instead of the grid currents, while the converter generates a copy of the distorted capacitor current, so that both the copy and the distorted currents cancel each other in the grid. Therefore, we can say that the converter emulates a negative capacitance connected to the grid, while at the same time delivers its active and reactive powers at the fundamental frequency. The CE method is achieved by adding an estimation of the distorted capacitor current to the converter current reference. However, an effective capacitive emulation requires a current control capable of accurately tracking all harmonics added to the current reference. In this sense, this paper proposes the use of a new integral predictive current control (IPCC), a dead-beat type of control that ensures a constant closed-loop group delay in a wide bandwidth. Unlike a PI control where the closed-loop delay varies with the frequency of the tracked harmonic, the constant control delay of the IPCC can be effectively compensated with a buffer-based advanced current reference. The effectiveness of the proposed CE method with IPCC control to reduce the total harmonic distortion (THD) of the line currents has been proved experimentally on a 10 kVA transformerless grid-connected three-phase inverter.

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Fault Ride-Through Control of Medium-Voltage Converters With LCL Filter in Distributed Generation Systems

Cited by 34 publications

References 18 publications

Generation of new harmonics caused by the processing of DQ transformation in power quality compensators

Generation of new harmonics caused by the processing of DQ transformation in power quality compensators

Low-Voltage Ride-Through Control Strategy for a Grid-Connected Energy Storage System

Capacitive Emulation Using Predictive Current Control in LCL-Filtered Grid-Connected Converters to Mitigate Grid Current Distortion

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