Positive Sequence Research Articles

P-2231. The Impact of Cell-free DNA Sequencing in the Evaluation and Management of Infections

Abstract Background Cell-free DNA Sequencing is a novel diagnostic test that utilizes next generation sequencing to detect pathogens directly from plasma. Microbial cell-free DNA (mcfDNA) can be detected for a large number of pathogens with high analytic sensitivity and specificity; however, testing may be cost prohibitive and the direct impact on clinical care decisions is unclear. Methods A retrospective review was performed at a large inner-city tertiary care medical center from 9/2021 to 3/2024 to assess the results of mcfDNA sequencing (using the Karius Test®) on committee approved patients for whom infection was suspected, and without a definitive diagnosis on traditional microbiologic testing or in patients not improving on current antimicrobial therapy. Clinical, microbiologic, and outcome data were collected, and the impact of a positive or negative test on clinical care decisions was abstracted. Test results were defined as impactful if they led to change in the antimicrobials (e.g. additional agents, dosing adjustment, or discontinuation of antimicrobials). Results Testing was completed on 25 patients, ranging from 5 months to 63 years (mean age 17 years), 16 (64%) female, 12 (48%) immunocompromised. The average result reporting time was 2.6 days. 23 (92%) patients received antibiotics prior to testing with an average duration of 30.8 days. A total of 13 (52%) of tests were positive by mcfDNA (with a mean of 1.6 organisms (SD=0.65) detected), and 7 (53.8%) polymicrobial results. The positive vs negative did not vary by suspected site, though sample size was small (Fig1). A total of 15 (60%) patients were positive by traditional microbiology tests with an organism correlation of 5 (20%). The mcfDNA results were impactful in 9 (36%) of the patients. A positive test was more likely to be impactful than a negative test (p=0.01). Ninety-day mortality was noted in 10 (40%) of patients and the average duration of hospitalization was 75.5 days – with no difference among patients with a positive mcfDNA (Table 1). Conclusion A positive mcfDNA sequencing result was noted to be clinically impactful in 36% of cases. Our data suggests that testing would be most beneficial for patients that lack a definitive infectious diagnosis or those not responding to appropriate therapy. Disclosures All Authors: No reported disclosures

P-2164. Diagnostic Utility of Plasma Microbial Cell-free DNA Sequencing in Suspected Infective Endocarditis and the Impact on Treatment Decisions

Abstract Background Plasma microbial cell-free DNA (mcfDNA) sequencing, commercially available from Karius® (Redwood City, CA), has been increasingly utilized in diagnosing endovascular infections. The 2023 updated Duke criteria incorporated detection of pathogen via metagenomic sequencing in its microbiologic criteria. We analyzed the clinical impact of mcfDNA sequencing in the diagnosis and treatment of suspected infective endocarditis (IE) cases. Methods We performed retrospective review of patients with suspected IE who underwent Karius® test at Mayo Clinic, MN, between 2017 to 2023. Results We preformed preliminary analysis of 25 patients. Analysis of baseline characteristics (table 1) revealed that these patients had significant predisposing factors for IE. Before accounting for mcfDNA sequencing, 3 (12%) met criteria for definite IE, 10 (40%) met criteria for possible IE, and 12 (48%) were rejected per 2023 Duke criteria. After incorporating mcfDNA sequencing result, 1 patient who was classified as possible IE was escalated to definite IE. This patient had previous infection of implantable cardioverter-defibrillator (ICD) with Streptococcus dysgalactiae. ICD was removed. She had development of endophthalmitis and stroke, 1 week and 2 weeks after the completion of IV antibiotics, respectively, with echocardiogram showing new tricuspid valve vegetation. Routine work-up was negative despite that she was not on any systemic antibiotics at the time of blood culture collection. mcfDNA sequencing detected Streptococcus dysgalactiae, making definite diagnosis of IE, leading to the physician’s decision to extend the IV antibiotic treatment (treatment escalation). Overall, after mcfDNA sequencing result, treatment decision was not impacted in 14 (56%), ongoing treatment was escalated in 4 (16%), de-escalated in 5 (20%), and antimicrobials was newly initiated in 2 (8%) (figure 1). Positive mcfDNA sequencing result often led to treatment escalation or initiation; negative result often led to treatment de-escalation (figure 2). Conclusion In challenging cases of suspected IE, mcfDNA sequencing led to alteration of antimicrobial treatment in 44% of cases. Further data collection and final analysis will include larger number of patients. Disclosures All Authors: No reported disclosures

Identification of fine antigenic epitopes of Tamdy virus glycoprotein Gn fragment and establishment of ELISA detection method

BackgroundTamdy virus (TAMV) was first isolated in Uzbekistan and Turkmenistan. In 2018, it was found in China, marking its entry into the molecular research era. TAMV is linked to febrile diseases, but its epidemiology and spillover risks are poorly understood, necessitating urgent molecular research and detection method development.MethodsThe secondary structure of TAMV glycoprotein Gn was predicted, and the results showed that it had rich antigenic epitopes. According to the predicted results, glycoprotein Gn was divided into 46 truncated 16-peptides by modified synthetic peptide method, and the antigenicity of 46 truncated 16-peptides was verified by western blotting analysis.ResultsThe results showed that P8, P9, P24, P25, P28, P29, and P39 had antigenicity. Subsequently, the seven positive 16-peptide sequences with antigenicity were truncated to form 8-peptide sequences with an overlap of seven amino acids. After analysis with the same method, eight fine antigenic epitopes E1 (58VINSTLDH65), E2 (65HVGSWGMP72), E3 (68SWGMPVTT75), E4 (187IRNQPFKS194), E5 (195FNVEVQ200), E6 (226AVVEHH231), E7 (228VEHHGNKA235), and E8 (310RGGRR314) were identified, all of which were located on the three-dimensional surface of glycoprotein Gn and were highly conserved in different TAMV strains.ConclusionsEight precise epitopes were identified, and an indirect ELISA method based on fusion multiepitope peptide (r-Gn-MEPX2) was developed and implemented, featuring high sensitivity, accuracy, and specificity.Graphical

New Oscillation Criteria for H‐Difference Equation With Oscillatory Periodic Coefficients

ABSTRACTIn this manuscript, new oscillation criteria are given for solutions of h‐order delay difference equation in the equation (1.1). There, four cases of are considered: for , as oscillatory periodic sequences with periods and and a quickly oscillating sequence such that . It is well‐known that coefficient functions have a very important role in the behavior of the solutions of an equation. The coefficient sequence has been considered as positive sequences in all oscillation criteria so far. But it is considered as oscillatory periodic sequences and quickly oscillatory sequences for the first time in this study. We use a new technique to prove our results. Also, some examples are provided to demonstrate the effectiveness of the main results.

Multi-Fault-Tolerant Operation of Grid-Interfaced Photovoltaic Inverters Using Twin Delayed Deep Deterministic Policy Gradient Agent

The elevated penetration of renewable energy has seen a significant increase in the integration of inverter-based resources (IBRs) into the electricity network. According to various industrial standards on interconnection and interoperability, IBRs should be able to withstand variability in grid conditions. Positive sequence voltage-oriented control (PSVOC) with a feed-forward decoupling approach is often adopted to ensure closed-loop control of inverters. However, the dynamic response of this control scheme deteriorates during fluctuations in the grid voltage due to the sensitivity of proportional–integral controllers, the presence of the direct- and quadrature-axis voltage terms in the cross-coupling, and predefined saturation limits. As such, a twin delayed deep deterministic policy gradient-based voltage-oriented control (TD3VOC) is formulated and trained to provide effective current control of inverter-based resources under various dynamic conditions of the grid through transfer learning. The actor–critic-based reinforcement learning agent is designed and trained using the model-free Markov decision process through interaction with a grid-connected photovoltaic inverter environment developed in MATLAB/Simulink® 2023b. Using the standard PSVOC method results in inverter input voltage overshoots of up to 2.50 p.u., with post-fault current restoration times of as high as 0.55 s during asymmetrical faults. The designed TD3VOC technique confines the DC link voltage overshoot to 1.05 p.u. and achieves a low current recovery duration of 0.01 s after fault clearance. In the event of a severe symmetric fault, the conventional control method is unable to restore the inverter operation, leading to integral-time absolute errors of 0.60 and 0.32 for the currents of the d and q axes, respectively. The newly proposed agent-based control strategy restricts cumulative errors to 0.03 and 0.09 for the d and q axes, respectively, thus improving inverter regulation. The results indicate the superior performance of the proposed control scheme in maintaining the stability of the inverter DC link bus voltage, reducing post-fault system recovery time, and limiting negative sequence currents during severe asymmetrical and symmetrical grid faults compared with the conventional PSVOC approach.

Matrix Transforms into a Set of α-absolutely Aλ-summable Sequences

Suppose A is a matrix having real or complex entries and λ- a monotonically increasing strictly positive sequence, i.e., the speed. In this paper, the notions of λ-reversibility of A, $$Α^λ$$-boundedness, and $$Α^λ$$-summability of sequences are recalled, and the notion of α-absolute $$Α^λ$$-summability of sequences is introduced. Also, there are characterized matrix transforms from the set of all $$Α^λ$$ -bounded, or the set of all α-summable, or the set of all 1- absolute $$Α^λ$$-summable sequences into the set of all α-absolutely (α>1) $$Β^μ$$-summable sequences for a normal or λ-reversible matrix A and a matrix $$Β=(b_{nk})$$ with $$b_{nk}=0$$, k>n, and for another speed μ.

MCHelper automatically curates transposable element libraries across eukaryotic species.

The number of species with high-quality genome sequences continues to increase, in part due to the scaling up of multiple large-scale biodiversity sequencing projects. While the need to annotate genic sequences in these genomes is widely acknowledged, the parallel need to annotate transposable element (TE) sequences that have been shown to alter genome architecture, rewire gene regulatory networks, and contribute to the evolution of host traits is becoming ever more evident. However, accurate genome-wide annotation of TE sequences is still technically challenging. Several de novo TE identification tools are now available, but manual curation of the libraries produced by these tools is needed to generate high-quality genome annotations. Manual curation is time-consuming, and thus impractical for large-scale genomic studies, and lacks reproducibility. In this work, we present the Manual Curator Helper tool MCHelper, which automates the TE library curation process. By leveraging MCHelper's fully automated mode with the outputs from three de novo TE identification tools, RepeatModeler2, EDTA, and REPET, in the fruit fly, rice, hooded crow, zebrafish, maize, and human, we show a substantial improvement in the quality of the TE libraries and genome annotations. MCHelper libraries are less redundant, with up to 65% reduction in the number of consensus sequences, have up to 11.4% fewer false positive sequences, and up to ∼48% fewer "unclassified/unknown" TE consensus sequences. Genome-wide TE annotations are also improved, including larger unfragmented insertions. Moreover, MCHelper is an easy-to-install and easy-to-use tool.

Positive and negative sequence impedance measurement method based on inductance switching for converters

Abstract Nowadays, the impedance-based method is a common method to study the small-signal stability of converters. Impedance measurement is the key to using this method. Common impedance measurement methods usually inject disturbances on the primary side and calculate the converter’s impedance by measuring the response excited by the disturbance. The high price and troublesome operation are the drawbacks of this method. In this paper, an impedance measurement method of the grid-tied converters by switching the grid-side inductance is proposed. By changing the grid-side inductance and injecting the same disturbance into the control system before and after the alteration, the positive and negative sequence impedance of the converters can be measured. This paper explains the measurement principle and elaborates the measurement steps. In the end, the effectiveness of the method is verified by simulations.

A low voltage ride-through approach for virtual synchronous machines under asymmetric fault conditions

Abstract With the advancement of renewable energy generation technologies, virtual synchronous machine (VSG) technology has garnered significant attention for enhancing power system stability. However, under asymmetric grid faults, the operational stability of VSMs under low voltage conditions remains a challenge. To address this, this paper presents a low-voltage ride-through strategy that utilizes dual-loop control for managing both positive and negative sequence components, aiming to improve the dynamic response of VSG during asymmetric faults. By thoroughly analyzing the VSM topology and mathematical model, an improved control scheme is developed. The effectiveness and practicality of the proposed strategy are ultimately validated through simulations under complex fault conditions.

Power quality enhancement of three-phase solar photovoltaic system-based generalized integrator controlled UPQC

Abstract As distributed generation becomes increasingly prevalent, providing reliable and stable electrical energy to the grid is of paramount importance. Therefore, precise monitoring of grid voltage is necessary in order to synchronize compensating current and voltage with the grid. The Dual Second-Order Generalized Integrator (DSOGI) can extract the fundamental positive sequence component from three-phase grid signals, enabling accurate determination of grid phase and current signals for rapid and precise grid compensation. This paper presents a control algorithm for extracting and compensating UPQC reference signals based on the Second-Order Generalized Integrator (SOGI). The improved photovoltaic-fed Unified Power Quality Conditioner System (PV-UPQC) is verified and analyzed under conditions of unbalanced grid voltage, current harmonics, as well as voltage sags and swells. It can be demonstrated that the enhanced system exhibits superior adaptability to the grid.

LOSSES OF ELECTRICAL ENERGY DUE TO ITS LOW QUALITY AT PUMPING STATIONS OF HEATING NETWORK ENTERPRISES

The issue of increasing the reliability of the facilities in the energy system of Ukraine is considered. It is noted that Ukraine lacks sources of electric energy as a result of hostile actions. In addition, the level of electric energy losses is very noticeable. Even according to pre-war statistics, the level of losses exceeded 10 % of all energy produced. And this was a consequence of the wear and tear of both electrical equipment and insufficient quality of electric energy. And as a result of hostile actions, the destruction of energy equipment led to an even worse decrease in the parameters of the quality of electricity. The priority is to maintain the operability of the energy system, while quality indicators are relegated to the second place. For most electricity-consuming equipment, deterioration in the quality of electricity can have a multiplier effect. Manifesting itself as a sharp increase in losses. For enterprises whose work provides for the vital needs of the population, the quality of electric energy is not a criterion. The main goal is to maintain operability. Such enterprises also include enterprises of heating networks. Almost all devices and equipment of heating companies operate on electricity. Forced movement of the coolant in the network is created only by electric pumps receiving torque from asynchronous electric motors. Such motors are characterized by increased losses of electrical energy if its quality is poor. Measurements of the quality of electrical energy were made at two different heat supply enterprises. The article presents the results of the measurements. Despite the fact that the heat supply enterprises are very different (the first serves more than 30 thousand residents, the second – more than 8 thousand residents), the results of the measurements show the affinity of problems with the quality of electrical energy. The overwhelming majority of electrical energy quality indicators do not meet the requirements for the quality of electrical energy. The most critical deviations are in the values of average voltage and average positive sequence voltage, which may not meet the standard in 100 measurements out of 100. The deviation of the voltage asymmetry coefficient for zero sequence also exceeds the standard values. The authors draw attention to the presence of a deviation of the average coefficient of the n-th harmonic component of voltage in all phases. The specificity of the operation of heat supply enterprises' equipment is that their operating modes are continuous throughout the entire heating season. And losses in the network can accumulate. In addition, one of the consequences of using low-quality electricity is a reduction in the service life of electrical equipment. The authors propose general methods for correcting the situation and emphasize the need to conduct a study of electrical equipment of heat supply enterprises in order to develop measures to improve their operation and reduce energy losses.

Evaluating synchrophasor-enabled angle-based differential protection in distribution networks

The inclusion of Distributed Energy Resources (DERs) affects the protection requirements and the functional constraints of the modern distribution networks (MDNs). With continued research on the primary protection of MDNs, this paper evaluates an angle-based differential protection scheme utilizing synchrophasors from distribution-level phasor measurement units (D-PMUs). The suggested scheme is based on computing the Absolute Superimposed Differential Angle (ASDA) of positive sequence current between two ends of a distribution line. The ASDA concept is explained by considering internal and external fault conditions. The initial investigations are performed on a modified real-distribution network in the Dubai utility, assuming rotating or non-rotating DER. Thereafter, the scheme is thoroughly examined in a seven-node MDN modelled in Real-Time Simulator, exploring various scenarios such as different fault types, fault resistance and line length variations, switching transients, varying DER penetration levels and types, and different network operation modes. Additionally, the analysis of CT saturation effect, measurement noise and response time of the proposed scheme has been carried out. A real-time laboratory testbed is also developed utilizing physical PMUs and a real-time simulator to verify the performance of suggested scheme in a practical environment. Furthermore, a quantitative and qualitative evaluation of the proposed strategy is presented to demonstrate the strategy’s reliability and efficacy. Our findings demonstrate that the suggested approach reliably detects short-circuit faults in a broad spectrum of network conditions.

Power Quality Enhancement in Grid-Connected Solar PV Systems Using Adaptive Control and Multilevel Inverter Topologies Under Dynamic Grid Conditions

This paper introduces a control strategy that uses an integrator-based positive sequence estimator to improve the power quality of a grid-connected double-stage solar PV system. The control extracts positive sequence components from distorted and unbalanced grid voltages to calculate unit templates and grid reference currents during grid anomalies like distortion, unbalance, sag/swell, and DC offset. A feedforward term is introduced to the photovoltaic array to ensure rapid transient response, and the DC-link voltage is adaptively regulated to reduce the voltage source converter (VSC) losses during weak grid conditions. The paper compares the performance of two-level and three-level inverters in this system configuration, highlighting the differences in power quality improvement, harmonic reduction, and system efficiency under various grid disturbances and intermittent solar conditions. Simulation results, performed in MATLAB, validate the superior performance of the three-level inverter in terms of lower total harmonic distortion (THD) in grid currents, in compliance with IEEE standard 519, while demonstrating the satisfactory response of both inverter types during challenging grid conditions like intermittent solar irradiation, DC offset, voltage distortions, unbalance, and voltage sag/swell.

A Modified Control Strategy for Three-Phase Four-Switch Active Power Filters Based on Fundamental Positive Sequence Extraction

Three-phase four-switch active power filters (APFs) have attracted attention due to their low amount of semiconductors and low cost. The traditional control strategy of three-phase four-switch APFs usually includes phase-locked loops (PLLs) and rotating coordinate transformation for harmonic detection, resulting in complicated calculations and increased computation. In this paper, a modified control strategy for three-phase four-switch APFs based on fundamental positive sequence extraction is proposed, eliminating PLLs and rotating coordinate transformation with trigonometric calculations. Harmonic extraction is based on the fundamental positive sequence extraction method, while non-locked phase loop coordinate transformation is proposed to eliminate trigonometric calculations. Quasi-PR control is adopted for current tracking, and DC voltage control is designed to suppress voltage imbalance between the two split capacitors on the DC side. The space vector pulse width modulation (SVPWM) method is modified for a reduced-switch APF topology. The proposed control strategy guarantees excellent harmonic compensation: harmonic currents are significantly suppressed when the APFs are working, the THD of the source current decreases to 3.86%, the bus voltage fluctuation on the DC side is small, the voltage remains stable, and the computational complexity is reduced. Finally, a simulation and an experimental hardware platform are established to validate the feasibility and performance of the proposed control strategy. The experimental results show that it has good performance in suppressing harmonics and improving power quality.

Research on Radial Vibration Model and Low-Frequency Vibration Suppression Method in PMSM by Injecting Multiple Symmetric Harmonic Currents

Driven by frequency conversion, the windings of a three-phase permanent magnet synchronous motor (PMSM) contain both odd and even harmonic currents. Due to the motor’s pole–slot conductance modulation, the interaction between the magnetic fields generated by these harmonic currents and the permanent magnet field results in harmonic radial vibrations of the motor. This paper analyzes the three-phase currents of the prototype and derives the radial magnetomotive force (MMF) spatiotemporal models for symmetric harmonic currents. By integrating Maxwell’s magnetic force formula and vibration response formula, the radial vibration models for symmetric harmonic currents are developed. The characteristics of vibrations caused by odd and even harmonic currents, as well as positive sequence and negative sequence harmonic currents, are analyzed separately. A cyclic sequence, low-frequency vibration suppression control method incorporating multiple harmonic current injections was designed. Experimental results of this method are compared with those obtained using an ideal sinusoidal current. Except for the second harmonic vibration, all other vibrations are significantly suppressed, with a maximum suppression rate of 92.28%. The total vibration level is reduced by 12.7619 dB, and the average torque is reduced by 0.67% with the total harmonic distortion of the current at 2.89%. The experimental results show that the vibration method in this paper has little influence on the average torque of the motor, the current distortion rate is small, and the vibration suppression effect is good.

Enhancing power quality in distributed generation systems using three-phase shunt active power filter

The current paper presents a new reference current generation algorithm for shunt active power filter (SAPF) combined with distributed generation systems using the instantaneous power theory (IPT) which is organized in two main blocks. The first is the synchronization technique; we propose a new quasi open loop technique that combines a Decoupled double self-tuning filter (DDSTF) and a single-phase frequency locked loop (FLL). The DDSTF is a new technique that extracts and separates the positive and negative sequence voltage under highly unbalanced and distorted conditions with no need to the symmetrical component and/or signals delay. The FLL achieve the grid frequency adaptation. Unlike the existing frequency estimators, this technique is motivated by its simplicity and the immunity to the voltage signal amplitude and phase variation or disturbance, which is a great advantage. The second is an ADALINE in power space to separate the fundamental harmonic from the distortion harmonics of the measured currents. The effectiveness of the proposed OLS technique in their application to the SAPF is validated by simulation.

Influence of wind farm fault current control strategies on distance protection during unsymmetrical faults

Abstract This paper evaluates the performance of distance protection near a wind farm with type IV wind turbines with various basic fault current control strategies implemented in the power converters. The considered fault control strategies include control of purely positive sequence currents or combined positive and negative sequence currents for reactive power support of various magnitudes. A multi-variable study is performed in PSCAD to show performance of a basic algorithm of distance protection at a 420 kV line in a vicinity of the wind farm. The results show that the majority of relay failures occur for phase-phase-ground faults, that reactive current control has less influence in strong grid than in weak grid, and that standard wind turbine fault control procedure of providing balanced current might result in fault currents much smaller than maximum allowed (usually 1.2 pu).

Research of the distribution symmetrical components in an electrical system with a diesel generator at an unsymmetrical load

Purpose. Investigation symmetrical components of current and voltage in microgrid elements with an autonomous synchronous generator of limited power, which works in parallel with a network transformer under the condition of non-metric load. Methodology. During the research, visual programming methods were used in the Simulink/Matlab package, methods of electrical engineering theory in terms of determining symmetrical component currents and voltages in observation branches, methods of synthesizing schemes for replacing elements of electric power systems for symmetrical component currents, methods of data processing and construction diagrams using specialized software tools.. Findings. As a result the analysis known studies, it was established that under the condition of researching low-power generating systems in conditions of asymmetry, insufficient attention is paid to the nature of the asymmetric load. Using the well-known structure of a microgrid, which includes a synchronous generator, a machine load, and an external network transformer, its model was built, in which, by introducing asymmetric loads of various types, a series of experiments was implemented with the registration of voltages and currents of forward, reverse, and zero sequences in the branches of the network. The analysis of the results obtained during the research established that the positive sequence voltage in the case of a change in the active load does not change its level, under the same circumstances, in the case of an active-capacitive and active-inductive load, the voltage change has the opposite character. In the case of increasing asymmetry of an active-inductive nature, the positive sequence voltage decreases, and in the case of an active-capacitive one, it increases. The specified changes in some cases exceed 3%. Positive sequence currents in the case of active load imbalance differ slightly. In the case of a positive sequence current of the transformer, its continuous growth is observed, which in the case of active-capacitive and active-inductive loads exceeds the active one by an average of 1.5 times. Negative sequence currents in the studied model, which are formed by an asymmetrical load, are completely closed to the transformer, causing zero-sequence voltages, and the nature asymmetrical load significantly affects the value of these currents, a 61% increase was noted. Originality. It was established that in a microgrid, which includes a synchronous generator, a machine load, a symmetrical active load of comparable power to the generator, an external network transformer, in addition to the fact of asymmetry caused by an asymmetrical load, the character of an asymmetrical load (active, active-inductive or active-capacitive). Practical value. In the case of using in microgrids devices that provide an increase in the quality of electrical energy, for example, symmetrical devices, it is necessary, in addition to the asymmetry factor, to take into account the natural load that causes the latter.

Separation of yttrium from ion-adsorbed-rare-earth deposit leachates using N,N-di(2-ethylhexyl)-diglycolamic acid (HDEHDGA): Preliminary experimental and molecular dynamics simulation studies

The separation of yttrium (Y) from heavy rare-earth elements (HREEs) is a major issue for ion-adsorbed rare-earth deposits. This study describes a new extraction system to develop efficient separation of Y from HREEs in a chloride medium using diglycolamic acid as the extractant. The extraction performance of N,N-di(2-ethylhexyl)-diglycolamic acid (HDEHDGA) for mixed REEs of an ion-adsorbed rare-earth deposit was investigated. The extraction order of the REEs in the HDEHDGA system followed a positive sequence, and the extraction behavior of Y resembled that of the middle REEs. Compared with naphthenic acid (NA) and sec-octylphenoxy acetic acid (CA12), HDEHDGA exhibited better separation performance for HREEs (Ho-Lu) and Y. The separation factors of Ho/Y, Er/Y, Tm/Y, Yb/Y, and Lu/Y in the Y-enriched solution were 4.41, 4.29, 3.77, 3.26, and 3.11, respectively. Combined slope analysis and electrospray ionization–high-resolution mass spectroscopy (ESI-HRMS) results identified cation exchange as the extraction mechanism of RE3+. Furthermore, the molecular dynamics simulation results provided new insights into the dynamic behaviors of Y3+ and Yb3+ extraction and revealed that the interaction of HDEHDGA with Yb3+ was stronger than that with Y3+. In addition, the loading capacity and recyclability of HDEHDGA were evaluated. This study highlights the potential of the HDEHDGA system for the separation of Y from HREEs.

Photovoltaic Power Intermittency Mitigating with Battery Storage Using Improved WEEC Generic Models

The growing integration of renewable energy sources, such as photovoltaic and wind systems, into energy grids has underscored the need for reliable control mechanisms to mitigate the inherent intermittency of these sources. According to the Brazilian grid operator (ONS), there have been cascading disconnections in renewable energy distributed systems (REDs) in recent years, highlighting the need for robust control models. This article addresses this issue by presenting the validation of an active power ramp rate control (PRRC) function for a PV plant coupled with a Battery Energy Storage System (BESS) using WECC generic models. The proposed model underwent rigorous validation over an extended analysis period, demonstrating good accuracy using the Root Mean Squared Error (RMSE) and an R-squared (R2) metrics for the active power injected at the Point of Connection (POI), PV active power, and BESS State of Charge (SOC), providing valuable insights for medium and long-term analyses. The ramp rate control module was implemented within the plant power controller (PPC), leveraging second-generation Renewable Energy Systems (RES) models developed by the Western Electricity Coordination Council (WECC) as a foundational framework. We conducted simulations using the Anatem software, comparing the results with real-world data collected at 100 ms to 1000 ms intervals from a PV plant equipped with a BESS in Brazil. The proposed model underwent rigorous validation over an extended analysis period, with the presented results based on two days of measurements. The positive sequence model used to represent this control demonstrated good accuracy, as confirmed by metrics such as the Root Mean Squared Error (RMSE) and R-squared (R2). Furthermore, the article underscores the critical role of accurately accounting for the power sampling rate when calculating the ramp rate.