PI controller
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In this paper, an improved voltage control strategy for microgrids (MG) is proposed, using an artificial neural network (ANN)-based adaptive proportional-integral (PI) controller combined with droop control and virtual impedance techniques (VIT). The control strategy is developed to improve voltage control, power sharing and total harmonic distortion (THD) reduction in the MG systems with renewable and distributed generation (DG) sources. The VIT is used to decouple active and reactive power, reduce negative power interactions between DG's and improve the robustness of the system under varying load and generation conditions. Simulation findings under different tests have shown significant improvements in performance and computational simulation. The rise time is reduced by 60%, the overshoot is reduced by 80%, the THD of the voltage is reduced by 75% (from 0.99 to 0.20%), and the THD of the current is reduced by 69% (from 10.73 to 3.36%) compared to the conventional PI controller technique. Furthermore, voltage and current THD values were maintained below the IEEE-519 standard limits of 5% and 8%, respectively, for the power quality enhancement. Fluctuations in voltage and frequency were also maintained at 2% tolerance and 1% tolerance, respectively, across all voltage limits, which is consistent with international norms. Power-sharing errors were reduced by 50% after conducting the robustness tests against the DC supply and load disturbances. In addition, the proposed strategy outperforms the previous control techniques presented at the state of the art in terms of adaptability, stability and, especially, the ability to reduce the THD, which validates its effectiveness for MG systems control and optimization under uncertain conditions.
Load frequency control (LFC) is critical for maintaining stability in interconnected power systems, addressing frequency deviations and tie-line power fluctuations due to system disturbances. Existing methods often face challenges, including limited robustness, poor adaptability to dynamic conditions, and early convergence in optimization. This paper introduces a novel application of the sinh cosh optimizer (SCHO) to design proportional-integral (PI) controllers for a hybrid photovoltaic (PV) and thermal generator-based two-area power system. The SCHO algorithm's balanced exploration and exploitation mechanisms enable effective tuning of PI controllers, overcoming challenges such as local minima entrapment and limited convergence speeds observed in conventional metaheuristics. Comprehensive simulations validate the proposed approach, demonstrating superior performance across various metrics. The SCHO-based PI controller achieves faster settling times (e.g., 1.6231 s and 2.4615 s for frequency deviations in Area 1 and Area 2, respectively) and enhanced robustness under parameter variations and solar radiation fluctuations. Additionally, comparisons with the controllers based on the salp swarm algorithm, whale optimization algorithm, and firefly algorithm confirm its significant advantages, including a 25-50% improvement in integral error indices (IAE, ITAE, ISE, ITSE). These results highlight the SCHO-based PI controller's effectiveness and reliability in modern power systems with hybrid and renewable energy sources.
- Klíčová slova
- Load frequency control, PI controller, Sinh cosh optimizer (SCHO), Two-area system,
- Publikační typ
- časopisecké články MeSH
The imbalance between generated power and load demand often causes unwanted fluctuations in the frequency and tie-line power changes within a power system. To address this issue, a control process known as load frequency control (LFC) is essential. This study aims to optimize the parameters of the LFC controller for a two-area power system that includes a reheat thermal generator and a photovoltaic (PV) power plant. An innovative multi-stage TDn(1 + PI) controller is introduced to reduce the oscillations in frequency and tie-line power changes. This controller combines a tilt-derivative with an N filter (TDn) with a proportional-integral (PI) controller, which improves the system's response by correcting both steady-state errors and the rate of change. This design enhances the stability and speed of dynamic control systems. A new meta-heuristic optimization technique called bio-dynamic grasshopper optimization algorithm (BDGOA) is used for the first time to fine-tune the parameters of the proposed controller and improve its performance. The effectiveness of the controller is evaluated under various load demands, parameter variations, and nonlinearities. Comparisons with other controllers and optimization algorithms show that the BDGOA-TDn(1 + PI) controller significantly reduces overshoot in system frequency and tie-line power changes and achieves faster settling times for these oscillations. Simulation results demonstrate that the BDGOA-TDn(1 + PI) controller significantly outperforms conventional controllers, achieving a reduction in overshoot by 75%, faster settling times by 60%, and a lower integral of time-weighted absolute error by 50% under diverse operating conditions, including parameter variations and nonlinearities such as time delays and governor deadband effects.
Amphoteric azo dyes were used for internal control of pI values in Comparative two-dimensional Fluorescence Gel Electrophoresis (CoFGE) [1]. The 2D-gel images of separated Escherichia coli proteins as well as those of colored amphoteric dyes separated by isoelectric focussing are presented. The latter were used to correct for variation in the first electrophoretic dimension and further improve protein coordinate assignment in 2D-gel electrophoresis. Data tables are supplied to demonstrate pI-value calibration and the effect on the assignment of protein spot coordinates.
- Klíčová slova
- 2D-PAGE, CoFGE, Gel electrophoresis, pI,
- Publikační typ
- časopisecké články MeSH
The microgrid (MG) faces significant security issues due to the two-way power and information flow. Integrating an Energy Management System (EMS) to balance energy supply and demand in Malaysian microgrids, this study designs a Fuzzy Logic Controller (FLC) that considers intermittent renewable sources and fluctuating demand patterns. FLC offers a flexible solution to energy scheduling effectively assessed by MATLAB/Simulink simulations. The microgrid consists of PV, battery, grid, and load. A Maximum Power Point Tracking (MPPT) controller helps to extract the maximum PV output and manages the power storage by providing or absorbing excess power. System analysis is performed by observing the State of Charge (SoC)of the battery and output power for each source. The grid supplies additional power if the battery and PV fail to meet the load demand. Total Harmonic Distortion (THD) analysis compares the performance of the Proportional-Integral Controller (PIC) and FLC. The results show that the PI controller design reduces the THD in the current signal, while FLC does not reduce the THD of the grid current when used in the EMS. However, FLC offers better control over the battery's SOC, effectively preventing overcharging and over-discharging. While PI reduces THD, FLC provides superior SOC control in a system comprising PV, battery, grid, and load. The findings demonstrate that the output current is zero when the SOC is higher than 80% or lower than 20%, signifying that no charging or discharging takes place to avoid overcharging and over-discharging. The third goal was accomplished by comparing and confirming that the grid current's THD for the EMS designed with both the PI Controller and the FLC is maintained below 5%, following the IEEE 519 harmonic standard, using the THD block in MATLAB Simulink. This analysis highlights FLC's potential to address demand-supply mismatches and renewable energy variability, which is crucial for optimizing microgrid performance.
- Klíčová slova
- Energy management system, Fuzzy logic controller, MATLAB simulink, Microgrid,
- Publikační typ
- časopisecké články MeSH
Steam condensers are vital components of thermal power plants, responsible for converting turbine exhaust steam back into water for reuse in the power generation cycle. Effective pressure regulation is crucial to ensure operational efficiency and equipment safety. However, conventional control strategies, such as PI, PI-PDn and FOPID controllers, often struggle to manage the nonlinearities and disturbances inherent in steam condenser systems. This paper introduces a novel multistage controller, TDn(1 + PIDn), optimized using the diligent crow search algorithm (DCSA). The proposed controller is specifically designed to address system nonlinearities, external disturbances, and the complexities of dynamic responses in steam condensers. Key contributions include the development of a flexible multi-stage control framework and its optimization via DCSA to achieve enhanced stability, faster response times, and reduced steady-state errors. Simulation results demonstrate that the TDn(1 + PIDn) controller outperforms conventional control strategies, including those tuned with advanced metaheuristic algorithms, in terms of settling time, overshoot, and integral of time weighted absolute error (ITAE). This study marks a significant advancement in pressure regulation strategies, providing a robust and adaptive solution for nonlinear industrial systems.
Cytokinetic membrane abscission is a spatially and temporally regulated process that requires ESCRT (endosomal sorting complexes required for transport)–dependent control of membrane remodeling at the midbody, a subcellular organelle that defines the cleavage site. Alteration of ESCRT function can lead to cataract, but the underlying mechanism and its relation to cytokinesis are unclear. We found a lens-specific cytokinetic process that required PI3K-C2α (phosphatidylinositol-4-phosphate 3-kinase catalytic subunit type 2α), its lipid product PI(3,4)P2 (phosphatidylinositol 3,4-bisphosphate), and the PI(3,4)P2–binding ESCRT-II subunit VPS36 (vacuolar protein-sorting-associated protein 36). Loss of each of these components led to impaired cytokinesis, triggering premature senescence in the lens of fish, mice, and humans. Thus, an evolutionarily conserved pathway underlies the cell type–specific control of cytokinesis that helps to prevent early onset cataract by protecting from senescence.
- MeSH
- biologická evoluce MeSH
- buněčné linie MeSH
- cytokineze * MeSH
- dánio pruhované MeSH
- endozomální třídící komplexy pro transport metabolismus MeSH
- fosfatidylinositol-3-kinasy genetika metabolismus MeSH
- fosfatidylinositol-4,5-difosfát metabolismus MeSH
- fosfatidylinositoly metabolismus MeSH
- katarakta metabolismus patologie MeSH
- lidé MeSH
- mutace MeSH
- myši MeSH
- oční čočka cytologie růst a vývoj metabolismus MeSH
- předčasné stárnutí MeSH
- proteiny buněčného cyklu metabolismus MeSH
- proteiny dánia pruhovaného genetika metabolismus MeSH
- proteiny vázající vápník metabolismus MeSH
- stárnutí buněk * MeSH
- tubulin metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
- Názvy látek
- CHMP4B protein, human MeSH Prohlížeč
- endozomální třídící komplexy pro transport MeSH
- fosfatidylinositol-4,5-difosfát MeSH
- fosfatidylinositoly MeSH
- PDCD6IP protein, human MeSH Prohlížeč
- phosphoinositide-3,4-bisphosphate MeSH Prohlížeč
- PIK3C2A protein, human MeSH Prohlížeč
- Pik3c2a protein, mouse MeSH Prohlížeč
- proteiny buněčného cyklu MeSH
- proteiny dánia pruhovaného MeSH
- proteiny vázající vápník MeSH
- tubulin MeSH
- VPS36 protein, human MeSH Prohlížeč
Growth factors and hormones activate global and selective protein translation by phosphorylation and therefore activation of p70 S6 kinase through a wortmannin-sensitive phosphoinositide-3 kinase (PI-3K) antiapoptotic pathway and a rapamycin-sensitive signalling pathway of mTOR. Here we demonstrate that the phosphorylation of 40S ribosomal protein S6, a physiological substrate p70 S6 kinase, was highly increased by growth-stimulation of the cytolytic T cells (CTLL2) with interleukin 2 (IL2), which was accompanied with the increased phosphorylation of p70 S6K. The activity of p70 S6K and phosphorylation of the S6 protein was completely blocked by rapamycin and significantly decreased upon treatment of the cells with wortmannin, indicating an involvement of the PI-3K pathway in concert with the signalling pathway of mTOR in IL2-dependent phos-phorylation of ribosomal protein S6. The phosphorylation and activity of PKB/Akt in IL2-stimulated CTLL2 cells were rapamycin-insensitive and reduced upon wortmannin treatment of the cells, confirming a requirement for PI-3K for Akt activity. The data support the hypothesis that Akt may act downstream to PI-3K and upstream to mTOR in an IL2-mediated signal transduction pathway that controls phosphorylation of the regulatory protein S6 in CTLL2 cells.
- MeSH
- androstadieny farmakologie MeSH
- buněčné linie MeSH
- fosfatidylinositol-3-kinasy metabolismus MeSH
- fosforylace * MeSH
- imunoblotting MeSH
- inhibitory enzymů farmakologie MeSH
- interleukin-2 metabolismus MeSH
- lidé MeSH
- myši MeSH
- protein-serin-threoninkinasy fyziologie MeSH
- proteinkinasy metabolismus MeSH
- protoonkogenní proteiny c-akt MeSH
- protoonkogenní proteiny * MeSH
- ribozomální protein S6 chemie metabolismus MeSH
- signální transdukce MeSH
- sirolimus farmakologie MeSH
- TOR serin-threoninkinasy MeSH
- wortmannin MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- AKT1 protein, human MeSH Prohlížeč
- androstadieny MeSH
- inhibitory enzymů MeSH
- interleukin-2 MeSH
- MTOR protein, human MeSH Prohlížeč
- mTOR protein, mouse MeSH Prohlížeč
- protein-serin-threoninkinasy MeSH
- proteinkinasy MeSH
- protoonkogenní proteiny c-akt MeSH
- protoonkogenní proteiny * MeSH
- ribozomální protein S6 MeSH
- sirolimus MeSH
- TOR serin-threoninkinasy MeSH
- wortmannin MeSH
beta-catenin has a dual function; it is implicated in intercellular junctions and transcriptional co-activation. Here we examined the regulation of the expression and localization of beta-catenin in HT29 colorectal adenocarcinoma cells. Our results showed that inhibition of PI-3 kinase with wortmannin was accompanied by a considerably reduced expression of beta-catenin. This effect was overcome by butyrate and occurred at the protein level, not at the level of mRNA. Moreover, NaBT significantly increased the phosphorylation of the ribosomal protein, S6, known to participate in the translational control of gene expression. This was accompanied by the increased phosphorylation of p70 S6K and MAPKs, the effector proteins that are upstream of protein S6 in the distinct signaling pathways. These facts indicate that different signaling pathways may be involved in the regulation of beta-catenin synthesis. Modulation of beta-catenin expression induced by NaBT appeared to occur at the level of protein translation, suggesting that NaBT may act as a translational regulator.
- MeSH
- adenokarcinom metabolismus MeSH
- alkalická fosfatasa metabolismus MeSH
- androstadieny metabolismus MeSH
- beta-katenin genetika metabolismus MeSH
- butyráty metabolismus MeSH
- fosfatidylinositol-3-kinasy metabolismus MeSH
- fosforylace MeSH
- imunohistochemie MeSH
- inhibitory fosfoinositid-3-kinasy MeSH
- kinasy ribozomálního proteinu S6, 70-kDa metabolismus MeSH
- kinasy ribozomálního proteinu S6 metabolismus MeSH
- kolorektální nádory metabolismus MeSH
- lidé MeSH
- mitogenem aktivované proteinkinasy metabolismus MeSH
- nádorové buněčné linie MeSH
- serin metabolismus MeSH
- signální transdukce fyziologie MeSH
- tyrosin metabolismus MeSH
- wortmannin MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- alkalická fosfatasa MeSH
- androstadieny MeSH
- beta-katenin MeSH
- butyráty MeSH
- inhibitory fosfoinositid-3-kinasy MeSH
- kinasy ribozomálního proteinu S6, 70-kDa MeSH
- kinasy ribozomálního proteinu S6 MeSH
- mitogenem aktivované proteinkinasy MeSH
- serin MeSH
- tyrosin MeSH
- wortmannin MeSH
Switched Reluctance Motor (SRM) has a very high potential for adjustable speed drive operation due to their cost-effectiveness, high efficiency, robustness, simplicity, etc. Now a days SRMs are widely used in automotive industries as traction motors in electric vehicles and hybrid electric vehicles, air-conditioning compressors, and for other auxiliary services. In this article, a novel super twisting sliding mode controller (STSMC) is proposed to improve the performance of an SRM for reducing the ripple in speed and torque. Initially, a novel Modified Electric Eel Foraging Optimization (MEEFO) technique is developed by incorporating a quasi-oppositional phase and its performance is compared with the conventional Electric Eel Foraging Optimization (EEFO) technique with four popular benchmark functions. Then, both MEEFO and EEFO techniques are implemented to optimally design PI, SMC and STSMC controllers to effectively control the speed of an SRM. The study is carried in three different scenarios such as during starting, during a torque change and during a speed change. Finally, performance of the SRM in real time is studied with OPAL-RT 4510 simulator. It is observed that MEEFO based STSMC exhibits significant improvements in effectively controlling speed of the SRM, as compared to its other proposed counterparts.
