Current Issue : October - December Volume : 2019 Issue Number : 4 Articles : 5 Articles
Conventional Energy Resources (CER) are being rapidly replaced by Renewable Energy\nResources (RER) due to their abundant, environmentally friendly, clean, and inexhaustible nature.\nIn recent years, Solar Photovoltaic (SPV) energy installation is booming at a rapid rate among\nvarious RER. Grid-Connected PVS required advance DC-link controllers to overcome second\nharmonic ripple and current controllers to feed-in high-quality current to the grid. This paper\nsuccessfully presents the design of a Fuzzy-Logic Based PI (F-PI) and Fuzzy-Logic based Sliding\nMode Controller (F-SMC) for the DC-link voltage controller and Proportional Resonant (PR) with\nResonant Harmonic Compensator (RHC) as a current controller for a Single-Phase Two-Stages Gridconnected\nTransformerless (STGT) Photovoltaic (PV) Inverter. The current controller is designed\nwith and without a feedforward PV power loop to improve dynamics and control. A Second Order\nGeneral Integral (SOGI)-based Phase Lock Loop (PLL) is also designed that has a fast-dynamic\nresponse, fast-tracking accuracy, and harmonic immunity. A 3 kW STGT-PV system is used for\nsimulation in Matlab/Simulink. A comparative assessment of designed controllers is carried out\nwith a conventionally well-tuned PI controller. The designed controllers improve the steady-state\nand dynamic performance of the grid-connected PV system. In addition, the results, performance\nmeasure analysis, and harmonics contents authenticate the robustness, fastness, and effectiveness\nof the designed controllers, related to former works....
Coloring of fuzzy graphs has many real life applications in combinatorial optimization problems like traffic light system, exam\nscheduling, register allocation, etc. In this paper, the concept of fuzzy chromatic polynomial of fuzzy graph is introduced and\ndefined based on alpha -cuts of fuzzy graph. Two different types of fuzziness to fuzzy graph are considered in the paper. The first type\nwas fuzzy graph with crisp vertex set and fuzzy edge set and the second type was fuzzy graph with fuzzy vertex set and fuzzy edge\nset. Depending on this, the fuzzy chromatic polynomials for some fuzzy graphs are discussed. Some interesting remarks on fuzzy\nchromatic polynomial of fuzzy graphs have been derived. Further, some results related to the concept are proved. Lastly, fuzzy\nchromatic polynomials for complete fuzzy graphs and fuzzy cycles are studied and some results are obtained....
Consider the problem of memoryless state feedback controller for time-delay system, which cannot consider both the memoryless\nand the memory items in the system. Therefore, the memoryless state feedback controller has certain limitations and is more\nconservative.This paper addresses the memory state feedback control for the time-varying delay switched fuzzy systems based on\nT-S fuzzy model to overcome the problem discussed above. The state vector and input of the time-varying delay systems contain\nunknown time-varying delay with known bounds. The designed controller whose parameters are solvable can introduce past\nstate information and reduce the system conservativeness. The more general Lyapunov-Krasovskii functional is selected and the\nswitching law is designed in order to analyze the open-loop system stability, and the memory state feedback controller is designed\nfor the closed-loop system and the criterion for its asymptotic stability. Discuss the solvability of the above two criteria. Finally, a\nnumerical example is given. The simulation results show that the proposed method is more feasible and effective....
The route evaluation is an important basis for airlines to make route decisions.\nIn order to solve the fuzzy multiple attribute route decision problem,\nroute attribute weight was completely unknown, and the route evaluation\nfuzzy language information was given, the fuzzy language and preference information\nwere converted into trapezoidal fuzzy numbers. A programming\nmodel was constructed by minimizing the total deviation between trapezoidal\nfuzzy numbers to determining the weight of each attribute in the route decision,\nBy weighting the average of the route attribute value and the weights\nvalue, compared the expected value of fuzzy comprehensive evaluation for\neach route, and ranking alternatives by using the expected value operator of\nfuzzy variable. Finally, a numerical example was used to illustrate the proposed\nmethod. The results show that the method can be used by airlines to\nsolve multiple attribute route decision problems with unknown weights, and\nthe method is scientific and effective....
In order to handle heavy chattering and negative robustness caused by time-varying system parameters and external load\ndisturbance of the speed control system, thereby having high-precision control over surface permanent magnetic synchronous\nmachine (PMSM), this paper combines the advantages of sliding mode variable structure control (SMVSC) and fuzzy control.\nFirstly, a fuzzy sliding mode variable structure control (FUZZY-SMVSC) method is proposed, based on the vector control\nfoundation framework of surface PMSM (SPMSM). It effectively reduces chattering while keeping sliding mode, according to the\nfuzzy rules formulated based on fuzzy control principle. Secondly, integral sliding mode surface is used and integration element is\nintroduced into fuzzy control input, thereby reducing the static error of the conventional fuzzy control. Simulation and experimental\nresults show that the proposed fuzzy sliding mode variable structure control reduces chattering by fuzzy reasoning and softening.\nAlso, it still can maintain the strong robustness of sliding mode variable structure and ensures the fine dynamics of the system,\nagainst time-varying system parameters and external load disturbance....
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