This paper proposes a supervisory control framework for a 6-MW wind farm (WF) comprising four 1.5-MW doubly fed induction generator (DFIG)-based wind turbines (WTs) to improve power quality and mitigate electrical and mechanical stresses under grid-pollution conditions. A backstepping control (BC) strategy is implemented at each WT to regulate active and reactive power while enabling active harmonic compensation through the existing power-electronic converters. A proportional allocation algorithm coordinates the compensation effort among the available WTs according to the load-current magnitude, thereby allowing partial or full-WF harmonic compensation depending on the operating condition. MATLAB/Simulink simulations under variable wind speeds, with an average wind speed of approximately 8.2 m/s, demonstrate accurate tracking of the WF-level active and reactive power references, with steady-state errors below 1.4%. Under nonlinear-load conditions, the proposed compensation strategy reduces the grid-current total harmonic distortion (THD) from 43.02% to 1.37% and from 33.16% to 1.33%, corresponding to reductions of approximately 96.8154% and 95.9891%, while improving the power factor from 0.78 lagging to 0.998. In addition, the rotor-circuit current ripple and electromagnetic torque ripple are reduced by 42% and 37%, respectively, indicating reduced electrical and mechanical stress on the DFIG-based WTs. These results demonstrate that the proposed supervisory and BC-based compensation framework can simultaneously achieve effective power regulation, harmonic mitigation, and stress reduction without requiring dedicated additional active-filter converters.
Fixed series capacitors are effective in increasing transmission line capacity in grid-connected Doubly Fed Induction Generator (DFIG)-based wind farms. Sub-Synchronous Resonance (SSR) phenomena occur when the series capacitors are in operation. The Gate-Controlled Series Capacitor (GCSC) model is used to eliminate the SSR effect. However, while the GCSC can control low series capacitance conditions, it is insufficient in high series capacitance conditions. To address this problem, this study aims to enhance a resonance control model for the Rotor-Side Converter (RSC) and Grid-Side Converter (GSC) circuits to reduce the SSR effect and improve the system's efficiency under different operating conditions in the DFIG. By enhancing the resonance control models for the GCSC and converter circuits, comparisons are made on some parameters in the DFIG at different wind speeds and different fixed series compensation ratios. In these comparisons, evaluations were made using the traditional model, the GCSC model, and the enhanced resonance control model in multiple applications in the RSC and RSC-GSC circuits. In addition, eigenvalue analyses were examined in detail in the comparisons. The results showed that the resonance control models enhanced for the GCSC and RSC-GSC circuits stabilized the system in a short time, and the resulting oscillations were quickly damped.
In this study, the high-resolution numerical simulation of the three-dimensional radiative rotating flow of polyalphaolefins (PAOs)-based nanolubricant with synergistic dispersion of molybdenum disulfide (MoS2) and silicon dioxide (SiO2) hybrid nanoparticles over a permeable surface expansion is presented. Motile bioconvection microorganisms are incorporated in the hybrid nanofluid to maximize the convective thermal performance and to stabilize the matrix of the multiphase solutions. The computational fluid dynamics framework considers the multiphysical coupled effects of the Darcy-Forchheimer porous medium, thermal radiation, heat sources and convective Biot boundary conditions with an aligned magnetic angle. The numerical approach, BVP4c is used to solve the transformed nonlinear equations of the boundary layer, and response surface methodology is applied to the surface topologies for the statistical mapping of the interactive limits of the parameters. It is found from the quantitative evaluations that the dominance of the porosity parameter is that it exactly gives a 67.4012% increase in the secondary skin friction as the porosity factor increases from 0.5 to 2.5. Moreover, the effect of an aligned magnetic field improves the energy transfer rate by 77.47%. The results of a rigorous grid independence matrix test show that when the number of discrete grid nodes is increased beyond (N = 320), all boundary layer fluxes are asymptotically stabilized to within six decimal places. Consequently, absolute convergence results show that the absolute error residuals are always kept within a stable micro-band until 10-8, demonstrating the unprecedented numerical accuracy, stability and reliability of the present simulation for advanced microfluidic thermal management systems.
Lithium-ion battery packs integrated with solar photovoltaic (PV) systems are susceptible to state-of-charge (SOC) imbalance among series-connected cells, which can reduce charging efficiency, usable capacity, and battery lifetime. This study proposes an integrated energy management strategy that combines fractional open-circuit voltage (FOCV)-based maximum power point tracking (MPPT) with predictive SOC-based passive cell balancing for a solar-powered lithium-ion battery system. A 185 W PV module is interfaced with a 13-cell battery pack comprising 3.7 V, 2.6 Ah cells through a boost DC–DC converter. The FOCV-based MPPT regulates the PV operating voltage within 70%–80% of the open-circuit voltage, while the predictive balancing algorithm continuously evaluates individual-cell SOC and selectively activates MOSFET-controlled bypass resistors to reduce SOC disparities. The proposed system is modeled and evaluated in the Typhoon-HIL environment and validated in real time using a Typhoon HIL-402 platform. The system extracts a maximum PV power of 183.95 W and achieves an MPPT efficiency of 98.9%, balancing efficiency of 94.6%, energy-utilization efficiency of 99.2%, and balancing power loss of approximately 0.41 W. The proposed approach also reduces SOC equalization time by 35% relative to the reported baseline. These results demonstrate that the integrated strategy can simultaneously enhance solar energy utilization and improve SOC uniformity in lithium-ion battery systems.
Education and R&D are frequently treated as broad capacity inputs to energy transition, but their empirical role is difficult to interpret when composite outcomes overlap with the regressors or when persistence and common shocks are ignored. Using World Bank Environment, Social and Governance (ESG) Data, this study constructs an outcome-only Energy-System Performance Index (ESPI) from electricity access, import security, renewable-electricity output, renewable-energy consumption, and resource protection for 46 World Bank economy aggregates over 1999–2020. Education and R&D expenditure are excluded from the index and modeled separately. The five outcomes are jointly observed for 942 of 1012 potential aggregate-years; incomplete predictor reporting leaves 455 observations across 31 aggregates in the baseline fixed-effects model. Baseline estimates associate education with lower ESPI (−0.1041, p = 0.0272) and R&D with higher ESPI (0.3234, p = 0.0219), while R&D is also associated with lower net energy-import dependence (−0.1478, p = 0.0172). The static ESPI coefficients are specification-sensitive, but all four reported dynamic estimators imply positive ESPI persistence (0.4640–0.9110); the split-panel-jackknife interval includes one, so stationarity is not uniform. Component-equality tests reject common education and R&D slopes (both p < 0.001), showing that the predictor associations are heterogeneous across energy outcomes. Persistence-adjusted confidence intervals include zero, and alternative weighting and leave-one-component-out checks show that composite coefficients depend on index construction. The contribution is therefore a measurement- and identification-disciplined framework for integrated energy-system performance, with the clearest recurring channel linking R&D to lower external energy dependence.
