Instantaneous Power Theory with Fourier and Optimal Predictive Controller Design for Shunt Active Power Filter

This paper presents a novel harmonic identification algorithm of shunt active power filter for balanced and unbalanced three-phase systems based on the instantaneous power theory called instantaneous power theory with Fourier. Moreover, the optimal design of predictive current controller using an artificial intelligence technique called adaptive Tabu search is also proposed in the paper. These enhancements of the identification and current control parts are the aim of the good performance for shunt active power filter. The good results for harmonic mitigation using the proposed ideas in the paper are confirmed by the intensive simulation using SPS in SIMULINK. The simulation results show that the enhanced shunt active power filter can provide the minimum %THD (Total Harmonic Distortion) of source currents and unity power factor after compensation. In addition, the %THD also follows the IEEE Std.519-1992

The Implementation of Active Power Filter using Proportional plus Resonant Controller

This paper presents the harmonic elimination using an active power filter (APF) for three-phase system. The design and performance comparison study of the compensating current controllers are explained. The performance of the PI controller and the proportional plus resonant (P+RES) controller are compared in the paper. Moreover, the hardware implementation of the considered system is also presented in this paper. For the experimental results, the P+RES controller can provide a good performance to control the compensating current compared with using the PI controller

Adaptive stabilization of uncontrolled rectifier based AC-DC power systems feeding constant power loads

It is known that, when tightly regulated, actively controlled power converters behave as constant power loads (CPLs). These loads can significantly degrade the stability of their feeder system. The loop-cancelation technique has been established as an appropriate methodology to mitigate this issue within dc–dc converters that feed CPLs. However, this has not yet been applied to uncontrolled rectifier based ac–dc converters. This paper therefore details a new methodology that allows the loop-cancelation technique to be applied to uncontrolled rectifier based ac–dc converters in order to mitigate instability when supplying CPLs. This technique could be used in both new applications and easily retrofitted into existing applications. Furthermore, the key contribution of this paper is a novel adaptive stabilization technique, which eliminates the destabilizing effect of CPLs for the studied ac–dc power system. An equation, derived from the average system model, is introduced and utilized to calculate the adaptable gain required by the loop-cancelation technique. As a result, the uncontrolled rectifier based ac–dc feeder system is always stable for any level of CPL. The effectiveness of the proposed adaptive mitigation has been verified by small-signal and large-signal stability analysis, simulation, and experimental results

Characterization of Acetonitrile-Tolerant Marine Bacterium Exiguobacterium sp SBH81 and Its Tolerance Mechanism

A Gram-positive marine bacterium, Exiguobacterium sp. SBH81, was isolated as a hydrophilic organic-solvent tolerant bacterium, and exhibited high tolerance to various types of toxic hydrophilic organic solvents, including acetonitrile, at relatively high concentrations (up to 6% [v/v]) under the growing conditions. Investigation of its tolerance mechanisms illustrated that it does not rely on solvent inactivation processes or modification of cell surface characteristics, but rather, increase of the cell size lowers solvent partitioning into cells and the extrusion of solvents through the efflux system. A test using efflux pump inhibitors suggested that secondary transporters, i.e. resistance nodulation cell division (RND) and the multidrug and toxic compound extrusion (MATE) family, are involved in acetonitrile tolerance in this strain. In addition, its acetonitrile tolerance ability could be stably and significantly enhanced by repetitive growth in the presence of toxic acetonitrile. The marked acetonitrile tolerance of Exiguobacterium sp. SBH81 indicates its potential use as a host for biotechnological fermentation processes as well as bioremediation

Adaptive Stabilization of a Permanent Magnet Synchronous Generator-Based DC Electrical Power System in More Electric Aircraft

Most loads of electrical power systems on a more electric aircraft (MEA) are regulated power converters. These loads behave as constant power loads (CPLs) that can significantly affect system stability. The system will become unstable and will be unable to operate at the rated power. In this article, a novel adaptive stabilization of a permanent magnet synchronous generator-based dc electrical power system in MEA is presented using a nonlinear feedback approach via loop-cancellation technique with a simple equation of feedback gain, which can be calculated from the power level of the CPL. The equation can be derived from a polynomial curve fitting based on the proposed mathematical model derived using the dq method. The adaptive stabilization results are validated by a small-signal stability analysis using the linearization technique, a large-signal stability analysis using the phase plane analysis, an intensive time-domain simulation using MATLAB, and experimentation. The results indicate that the proposed adaptive stabilization technique can provide the considered aircraft power system always stable for all operating conditions within the rated power, and the dc bus voltage can adhere to the MIL-STD-704F standard

Bacterial imprinting at Pickering emulsion interfaces

We demonstrate that the tendency of bacteria to assemble at oil-water interface can be utilized to create microbial recognition sites on the surface of polymer beads. In this work, two different groups of bacteria were first treated with acryloyl-functionalized chitosan, and then used to stabilize an oil-in-water emulsion composed of crosslinking monomer dispersed in aqueous buffer. Polymerization of the oil phase followed by removal of the bacterial template resulted in well-defined polymer beads bearing bacterial imprints. Chemical passivation of chitosan and cell displacement assays indicate that the bacterial recognition on the polymer beads was dependent on the nature of the pre-polymer and the target bacteria. The functional materials for microbial recognition show great potential for constructing cell-cell communication networks, biosensors, and new platforms for testing antibiotic drugs

Optimal Speed Controller Design of Commercial BLDC Motor by Adaptive Tabu Search Algorithm

Brushless direct current motors are widely used in many industries because of their high efficiency and long-life. This paper presents the application of the adaptive Tabu Search algorithm for system identification and PID speed controller design to provide the best speed output performance compared with those designed using the well-known tuning method, the Ziegler–Nichols approach. The proposed design technique shows that the adaptive Tabu Search algorithm includes the control signal consideration in the design process. As a result, the resulting controller parameters can be implemented without the limitations of the real devices, while the Ziegler–Nichols method cannot provide as good a response as expected. The results are validated by simulation and experiment in which the output responses from the proposed design method are evidently better than those from the conventional method. Moreover, other artificial intelligence techniques such as the genetic algorithm, particle swarm optimization etc. can also be applied for the optimal design process following the concept in this paper in which the characteristics of the control signal are considered for real devices