Optimization of Fuzzy Logic Controller for Supervisory Power System Stabilizers

This paper presents a powerful supervisory power system stabilizer (PSS) using an adaptive fuzzy logic controller driven by an adaptive fuzzy set (AFS). The system under study consists of two synchronous generators, each fitted with a PSS, which are connected via double transmission lines. Different types of PSS-controller techniques are considered. The proposed genetic adaptive fuzzy logic controller (GAFLC)-PSS, using 25 rules, is compared with a static fuzzy logic controller (SFLC) driven by a fixed fuzzy set (FFS) which has 49 rules. Both fuzzy logic controller (FLC) algorithms utilize the speed error and its rate of change as an input vector. The adaptive FLC algorithm uses a genetic algorithmto tune the parameters of the fuzzy set of each PSS. The FLC’s are simulated and tested when the system is subjected to different disturbances under a wide range of operating points. The proposed GAFLC using AFS reduced the computational time of the FLC, where the number of rules is reduced from 49 to 25 rules. In addition, the proposed adaptive FLC driven by a genetic algorithm also reduced the complexity of the fuzzy model, while achieving a good dynamic response of the system under study

Optimization of Fuzzy Logic Controller for Supervisory Power System Stabilizers

This paper presents a powerful supervisory power system stabilizer (PSS) using an adaptive fuzzy logic controller driven by an adaptive fuzzy set (AFS). The system under study consists of two synchronous generators, each fitted with a PSS, which are connected via double transmission lines. Different types of PSS-controller techniques are considered. The proposed genetic adaptive fuzzy logic controller (GAFLC)-PSS, using 25 rules, is compared with a static fuzzy logic controller (SFLC) driven by a fixed fuzzy set (FFS) which has 49 rules. Both fuzzy logic controller (FLC) algorithms utilize the speed error and its rate of change as an input vector. The adaptive FLC algorithm uses a genetic algorithmto tune the parameters of the fuzzy set of each PSS. The FLC’s are simulated and tested when the system is subjected to different disturbances under a wide range of operating points. The proposed GAFLC using AFS reduced the computational time of the FLC, where the number of rules is reduced from 49 to 25 rules. In addition, the proposed adaptive FLC driven by a genetic algorithm also reduced the complexity of the fuzzy model, while achieving a good dynamic response of the system under study

A New Parallel Genetic Algorithm Model

This paper presents an implementation of three Genetic Algorithm models for solving a reliability optimization problem for a redundancy system with several failure modes, a modification on a parallel a genetic algorithm model and a new parallel genetic algorithm model. These three models are: a sequential model, a modified global parallel genetic algorithm model and a new proposed parallel genetic algorithm model we called the Trigger Model (TM). The reduction of the implementation processing time is the basic motivation of genetic algorithms parallelization. In this work, parallel virtual machine (PVM), which is a portable message-passing programming system, designed to link separate host machines to form a virtual machine which is a single, manageable computing resource, is used in a distributed heterogeneous environment. The best result was reached and The TM model was clearly performing better than the other two models

Alleviating the adverse effects of plant pathogens, drought and salinity stress factors using plant growth promoting bacteria

Climate change is one of the most important threats to agricultural production, therefore, more attention must be paid to study the environmental stresses that affect plant production. Pathogen stress is one of the most important stresses that negatively affect growth and yield, also drought and salinity are very dangerous abiotic factors. Pathogens, drought and salinity stresses led to decrease morphological characters and yield production of plant. However, the application of plant growth promoting bacteria (PGPB) positively affect morphological, physiological, and yield characters such as number of leaves, stem height, chlorophyll concentration, relative water content, antioxidant enzymes and crop yield. PGPB can play a pivotal role in facilitating nutrient uptake, bioactive compounds and scavenging reactive oxygen species (ROS) to control various pathogens and increase plant tolerance to drought and salinity stresses. Finally, the latest studies of these beneficial bacteria have been presented comprehensively under stress conditions to highlight the recent trends with the aim to maximize the crop production.

Effect of Some Polyphenolic Compounds on Biochemical Parameters in Leukemic Patients

ackground :Polyphenolic compounds are groups of naturally occurring compounds in different plants. They are promising product to protect, and prevent leukemia and many types of cancer by different mechanisms. Objectives: The present study designed to study the effect of polyphenolic compounds [Ellagic acid (EA), Tannic acid (TA) and Caffiec acid (CA)] on GOT,GPT activities and total protein TP concentration in all types of leukemia [acute myeloblastic leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myeloblasti leukemia (CML) and chronic lymphoblastic leukemia (CLL)],in addition to compare the potency of these compounds among each other. Patients and Methods: Blood samples were collected from a hundred leukemic patients. In addition fifty healthy subjects age matched were chosen as control group. Transaminases (GOT and GPT) activities and total protein concentration in sera of all studied groups were determined before and after addition of 10 mM (EA, TA and CA) Results: There is a significant increase in serum GOT,GPT activity and TP concentration for all leukemic groups compared to control. The elevated values of GOT, GPT activities and TP concentration in patients were returned to about normal values in most cases after addition of 10 mM (EA, TA and CA). Conclusion: Results showed the effectiveness of polyphenolic compounds (EA, TA and CA) in treatment of leukemia in vitro study , also, results revealed that EA was the most potent compound among the types of polyphenolic compounds studied in affecting the parameters to be close to normal values

Multi-port converter for medium and high voltage applications

This work presents a multi-port converter (MPC) that is well-suited for use as a hybrid hub in complex multi-terminal high-voltage direct current (MTDC) networks. The proposed MPC generates several and controllable DC voltages from a constant or variable input DC voltage or AC grid. Its operating principle is explained and corroborated using simulations and experimentations

New analysis of VSC-based modular multilevel DC-DC converter with low interfacing inductor for hybrid LCC/VSC HVDC network interconnections

The integration of multiterminal hybrid HVDC grids connecting LCC- and VSC-based networks faces several technical challenges such as DC fault isolation, ensuring multi-vendor interoperability, managing high DC voltage levels, and facilitating high-speed power reversal without interruptions. The two-stage DC-DC converter emerges as a key solution to address these challenges. By implementing the modular multilevel converter (MMC) structure, the converter's basic topology includes half-bridge sub-modules on the VSC side and full-bridge sub-modules on the LCC side. However, while this topology has been discussed in the literature, its connection to an LCC-based network with controlled current magnitude lacks detailed analysis regarding operational challenges, control strategies under various scenarios, and design considerations. This paper fills this gap by providing comprehensive mathematical analysis, design insights, and control strategies for the modular DC-DC converter to regulate DC voltage on the LCC-HVDC side. Additionally, the proposed control scheme minimizes the interfacing inductor between the two bridges, ensuring uninterrupted power flow during reversal and effective handling of DC faults. Validation through Control-Hardware-in-the-Loop testing across diverse operational and fault scenarios, along with a comparative analysis of different converters, further strengthens the findings

Quality of Type 2 Diabetes Management in the States of The Co-Operation Council for the Arab States of the Gulf: A Systematic Review

Type 2 diabetes mellitus is a growing, worldwide public health concern. Recent growth has been particularly dramatic in the states of The Co-operation Council for the Arab States of the Gulf (GCC), and these and other developing economies are at particular risk. We aimed to systematically review the quality of control of type 2 diabetes in the GCC, and the nature and efficacy of interventions. We identified 27 published studies for review. Studies were identified by systematic database searches. Medline and Embase were searched separately (via Dialog and Ovid, respectively; 1950 to July 2010 (Medline), and 1947 to July 2010 (Embase)) on 15/07/2009. The search was updated on 08/07/2010. Terms such as diabetes mellitus, non-insulin-dependent, hyperglycemia, hypertension, hyperlipidemia and Gulf States were used. Our search also included scanning reference lists, contacting experts and hand-searching key journals. Studies were judged against pre-determined inclusion/exclusion criteria, and where suitable for inclusion, data extraction/quality assessment was achieved using a specifically-designed tool. All studies wherein glycaemic-, blood pressure- and/or lipid- control were investigated (clinical and/or process outcomes) were eligible for inclusion. No limitations on publication type, publication status, study design or language of publication were imposed. We found the extent of control to be sub-optimal and relatively poor. Assessment of the efficacy of interventions was difficult due to lack of data, but suggestive that more widespread and controlled trial of secondary prevention strategies may have beneficial outcomes. We found no record of audited implementation of primary preventative strategies and anticipate that controlled trial of such strategies would also be useful