Improving performance of single-phase SOGI-FLL under DC-offset voltage condition

Ngo, Tuan; Nguyen, Quan; Santoso, Surya

doi:10.1109/iecon.2014.7048706

Cited by 28 publications

(11 citation statements)

References 6 publications

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“…The structure of the SOGI-FLL is shown in Figure 1, where v is the input grid voltage, ω is the center frequency of the SOGI filter, v and v are its in-phase and quadrature-phase outputs, and ω is the FLL estimated grid frequency acting as the center frequency of the SOGI filter. The SOGI has band-pass filter (BPF) behavior for v d and low-pass filter (LPF) behavior for v q , with their transfer functions defined as [6]…”

Section: Sogi-fll Response To Voltage Sagsmentioning

confidence: 99%

“…There are several methods reported in the literature [2][3][4] for obtaining the grid voltage parameters. Among them, the Second-Order Generalized Integrator-Frequency-Locked Loop (SOGI-FLL) is popular due to its simplicity of implementation and low computational requirements [5,6]. The SOGI-FLL behaves well under grid normal conditions and even with some amount of harmonic distortion.…”

Section: Introductionmentioning

confidence: 99%

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New SOGI-FLL Grid Frequency Monitoring with a Finite State Machine Approach for Better Response in the Face of Voltage Sag and Swell Faults

et al. 2020

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The SOGI-FLL (Second-Order Generalized Integrator–Frequency-Locked Loop) is a well-known and simple adaptive filter that allows for estimating the parameters of grid voltage with a small computational burden. However, the SOGI-FLL has been shown to be especially sensitive to voltage sags and voltage swells, which deeply distort the estimated parameters, especially the frequency. This problem can be alleviated by simply using a saturation block at the Frequency-Locked Loop (FLL) output to limit the impact of distortion on the estimated frequency. Improving upon this straightforward approach, in this paper we propose the use of a finite state machine (FSM) for the definition of the different states of the SOGI-FLL frequency response during a voltage sag or swell fault. The FSM approach allows for applying different gains during the fault, enhancing the SOGI-FLL transient response. The performance of the FSM-based SOGI-FLL is evaluated by using simulation results, which show a better and faster response to these kinds of faults.

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Section: Sogi-fll Response To Voltage Sagsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

New SOGI-FLL Grid Frequency Monitoring with a Finite State Machine Approach for Better Response in the Face of Voltage Sag and Swell Faults

et al. 2020

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“…Finally, frequency estimation can be achieved either by Phase Locked Loops (PLL)s [22], [24], [25] or Frequency Locked Loops (FLL)s [16], [26], [27], [28]. In the presence of DC-offsets, the classic frequency adaption is not possible anymore, so in [23] (see above), multiple PLL-designs are discussed.…”

Section: Motivation and Literature Reviewmentioning

confidence: 99%

A unified method for signal parameter estimation of arbitrarily distorted single-phase grids with DC-offset

Hackl¹

2020

Preprint

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A unified method is presented which allows to estimate all harmonic components, DC-offset and fundamen- tal frequency in arbitrarily distorted single-phase grids us- ing a frequency-adaptive observer (FAO) consisting of modi- fied Second-Order Generalized Integrators (mSOGIs), a DC- Integrator (DCI) and a modified Frequency Locked Loop (mFLL). DCI and mSOGIs are tuned by pole placement which allows for an arbitrarily fast detection of DC-offset and harmonic components if the fundamental frequency is known. If the fundamental frequency must be estimated as well, a mFLL with Gain Normalization (GN), Rate Limitation (RL), Anti-Windup (AW) strategy and low-pass filters (LPF) must be employed. The effectiveness of the proposed FAO is validated by experimental results and its enhanced performance is shown by comparisons to existing estimation methods.

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“…Frequency detection can be achieved by a Frequency Locked Loop (FLL) [6,7,9] or a Phase Locked Loop (PLL) [2,10]. DC-offset estimation was reported in [4,11], whereas detection of higher-order harmonics was introduced in [12,13]. However, only in [13] was (local) stability proven.…”

Section: Motivation and Literature Reviewmentioning

confidence: 99%

A Unified Method for Online Detection of Phase Variables and Symmetrical Components of Unbalanced Three-Phase Systems with Harmonic Distortion

Hackl

Landerer

2019

Energies

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This paper presents a method for online detection of symmetrical components of arbitrarily distorted and biased three-phase input signals. This method is based on Second-Order Generalized Integrators (SOGIs), for which a new tuning based on a gradient search is presented to achieve the fastest possible estimation. Frequency estimation is achieved by a Frequency Locked Loop (FLL) with Gain Normalization (GN) for which an Output Saturation (OS) is applied; this OS guarantees stability of the overall system. Offset detection is implemented by a combination of High-Pass Filter (HPF) and HPF-Amplitude Phase Correction (APC); the HPF filters out any offset, where the APC reconstructs the original offset-free signal. An identical method (APC) can be used for the implemented Low-Pass Filter (LPF) used for noise filtering. The resulting estimates are then used for Harmonic Sequence Detection (HSD) of each harmonic. For the overall system, stability is proven. The estimation performances of the proposed overall system are verified by simulation results. The improvements in tuning and offset detection are compared to standard approaches.

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Improving performance of single-phase SOGI-FLL under DC-offset voltage condition

Cited by 28 publications

References 6 publications

New SOGI-FLL Grid Frequency Monitoring with a Finite State Machine Approach for Better Response in the Face of Voltage Sag and Swell Faults

New SOGI-FLL Grid Frequency Monitoring with a Finite State Machine Approach for Better Response in the Face of Voltage Sag and Swell Faults

A unified method for signal parameter estimation of arbitrarily distorted single-phase grids with DC-offset

A Unified Method for Online Detection of Phase Variables and Symmetrical Components of Unbalanced Three-Phase Systems with Harmonic Distortion

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