Small-Signal Modelling and Stability Assessment of Phase-Locked Loops in Weak Grids

Burgos-Mellado, Claudio; Costabeber, Alessandro; Sumner, Mark; Cárdenas, Roberto; Sáez, Doris

doi:10.3390/en12071227

Cited by 17 publications

(8 citation statements)

References 43 publications

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“…The voltage (V ac,i ), current (i ac,i ), frequency (ω i ) and phase angle (θ i ) are measurable/estimable variables at the filter capacitor. Additionally, a reduced-order observer, based on [23], is used to estimate the voltage V L ac,i , at the adjacent measurement node downstream of L i , whereas ωL i and θL i are computed by a phase-locked loop (PLL) [24]. The proposed secondary control is, therefore, a multiple input-multiple output DMPC controller.…”

Section: A Dmpc For Ac Sub-microgridmentioning

confidence: 99%

Distributed Model-Based Predictive Secondary Control for Hybrid AC/DC Microgrids

Rute-Luengo

Navas-Fonseca

Gomez

et al. 2023

IEEE J. Emerg. Sel. Topics Power Electron.

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This paper presents a novel scheme based on distributed model-based predictive control for the secondary level control of hybrid AC/DC microgrids. Prediction models based on droop control and power transfer equations are proposed to characterize the generators in both the AC and DC sub-microgrids, whereas power balance constraints are used to predict the behavior of interlinking converters. The operational constraints (such as powers and control action limits) are included in all the formulations. Experimental results validate the proposed scheme for the following cases: (i) load changes, working within operating constraints, (ii) managing frequency regulation in the AC sub-microgrid, voltage regulation in the DC sub-microgrid and global power consensus in the whole hybrid microgrid, and (iii) maintaining the microgrid performance in the presence of communication malfunction while ensuring that plug-and-play capability is preserved.

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Section: A Dmpc For Ac Sub-microgridmentioning

confidence: 99%

Distributed Model-Based Predictive Secondary Control for Hybrid AC/DC Microgrids

Rute-Luengo

Navas-Fonseca

Gomez

et al. 2023

IEEE J. Emerg. Sel. Topics Power Electron.

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“…To achieve a desired performance, several DSCs have to be connected in cascaded. For instance, five DSCs with different value of n (n = 2, 4, 8,16,32) were arranged at the pre-filtering stage in [37]. The typical block diagram of the control strategy is shown in Figure 4.…”

Section: Modified Delay Signal Cancellation Operatormentioning

confidence: 99%

“…For a three phase power system, synchronous reference frame PLL (SRF-PLL) is an effective and typical method under ideal conditions [13,14]. However, with more utilization of renewable energy sources, a power system turns "weak" [15][16][17][18]. The grid voltages usually contain fundamental frequency negative sequence components (FFNSs) and other harmonic components.…”

Section: Introductionmentioning

confidence: 99%

A Modified DSC-Based Grid Synchronization Method for a High Renewable Penetrated Power System Under Distorted Voltage Conditions

Yang

et al. 2019

Energies

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With the increasing penetration of renewable energy, a weak grid with declining inertia and distorted voltage conditions becomes a significant problem for wind and solar energy integration. Grid frequency is prone to deviate from its nominal value. Grid voltages become more easily polluted by unbalanced and harmonic components. Grid synchronization technique, as a significant method used in wind and solar energy grid-connected converters, can easily become ineffective. As probably the most widespread grid synchronization technique, phase-locked loop (PLL) is required to detect the grid frequency and phase rapidly and precisely even under such undesired conditions. While the amount of filtering techniques can remove disturbances, they also deteriorate the dynamic performance of PLL, which may not meet the standard requirements of grid codes. The objective of this paper is to propose an effective PLL to tackle this challenge. The proposed PLL is based on quasi-type-1 PLL (QT1-PLL), which provides a good filtering capability by using a moving average filter (MAF). To accelerate the transient behavior when disturbance occurs, a modified delay signal cancellation (DSC) operator is proposed and incorporated into the filtering stage of QT1-PLL. By using modified DSCs and MAFs in a cascaded way, the settling time of the proposed method is reduced to around one cycle of grid fundamental frequency without degrading any disturbance rejection capability. To verify the performance, several test cases, which usually happen in high renewable penetrated power systems, are carried out to demonstrate the effectiveness of the proposed PLL. China [7,8], and caused many wind turbines to be tripped off. This highly impacted the operation of power distribution and renewable energy utilization. The grid frequency is prone to deviate from its nominal value since the inertia of the grid decreases. Grid voltages contain an amount of undesired components, such as fundamental frequency negative sequences (FFNSs) and harmonic components, which results in unbalanced and distorted grid conditions. It is an essential requirement for a renewable energy power converter to maintain stable operation with high performance under such conditions. To achieve this goal, a proper grid synchronization method is needed for all grid-connected applications. It is a big challenge for a grid synchronization method to extract grid frequency and phase information under such adverse conditions.

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“…The weakness of a grid is evaluated by the short‐circuit ratio (SCR), which is defined in terms of line‐to‐line RMS grid voltage

V_{g}

, grid impedance

Z_{g}

and nominal inverter power

P_{n}

as in (1). A grid is typically considered weak when the SCR is less than three [2]

SCR = \frac{V_{g}^{2}}{Z_{g} P_{n}}

Weak grids are generally observed in remote or rural areas powered through long feeder lines. When the generation systems are located in remote areas, overextended medium‐voltage transmission resulting in large inductive grid impedances.…”

Section: Introductionmentioning

confidence: 99%

Adaptive controller based on grid impedance estimation for stable operation of grid‐connected inverters under weak grid conditions

Temiz¹,

Keysan²,

Demirok

2020

IET power electron.

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Small-Signal Modelling and Stability Assessment of Phase-Locked Loops in Weak Grids

Cited by 17 publications

References 43 publications

Distributed Model-Based Predictive Secondary Control for Hybrid AC/DC Microgrids

Distributed Model-Based Predictive Secondary Control for Hybrid AC/DC Microgrids

A Modified DSC-Based Grid Synchronization Method for a High Renewable Penetrated Power System Under Distorted Voltage Conditions

Adaptive controller based on grid impedance estimation for stable operation of grid‐connected inverters under weak grid conditions

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