Asymmetrical Saturation Research Articles

Event‐triggered asymmetrical saturation‐constraint impulsive control of multi‐agent systems

AbstractThe impulsive consensus problem of nonlinear multi‐agent system under energy consumption constraint is considered in the article. For considering the restricted communication channel, asymmetrical input saturation constraint is adopted into impulse control protocol. Then, based on the current national policy of energy conservation and emission reduction, a novel control protocol which combines asymmetrical input saturation constraint impulse protocol with event‐triggered approach is raised and set event decision time at pulse time. Then, the control protocol not only can be able to decrease communication frequency and energy consumption, but also avoid “Zeno behavior”. Furthermore, some theorems and their proofs about the consensus problems with and without leader are provided. Through mathematical derivation, sufficient conditions of problems have been crystallized. In the end, some different simulation instances are presented to verify the research.

Consensus Congestion Control for Ad Hoc Networks: Time-Delay and Saturation

This work focuses on the congestion control design for ad hoc networks affected by time-delay and asymmetrical input saturation. First, an innovative general TCP/AQM model for mobile and wireless ad hoc networks (MANET/WANET) is proposed using graph theory and TCP/AQM system dynamics in a dumbbell topology. Next, a new characteristic condition for sector linearity is developed, which plays the role of a specification to be checked and allows us to assume that the dynamics of the nodes are not saturated. Finally, we propose a new consensus-based congestion control protocol while satisfying the input constraints based on the Lyapunov method, the new sector of linearity condition, the Bessel Legendre-based integral inequality, and the reciprocal convex combination. The proposed results have the advantage of being given as a set of linear matrix inequality (LMI) conditions, which can be solved using convex optimization toolboxes. The merits of the theory are evaluated with the help of various real and challenging scenarios with the use of MATLAB and NS3.

Design of switching state-feedback controllers for linear systems subject to asymmetric saturations*

This paper considers the problem of controlling a linear system affected by asymmetrical input saturation. The proposed solution is based on using a linear matrix inequality (LMI)-based methodology to find the gains of a switching state-feedback controller. The main difference and contribution when compared to existing approaches is that the switching rule is chosen based on the closed-loop performance that each of the non-saturating controller gains can achieve when used with the current value of the state vector. Although the main focus of the paper is on time-invariant systems, the possible extension to linear parameter-varying (LPV) systems is discussed. An illustrative example is used to show the main features of the proposed approach.

A new pilot relaying technique for the STATCOM compensated transmission line

With the inclusion of STATCOM in the transmission line (TL) causes maloperation of both the local end and both ends data-based relaying techniques. In this work, a differential impedance is derived using both ends synchronized phase voltage and current data which is equal to zero during normal conditions and high for internal faults. Moreover, the computation of accurate fault distance is an added superiority of the proposed scheme with due reliable fault classification. To validate the proposed technique, a STATCOM compensated 400 kV, 60 Hz and 9- Bus 230 kV, 50 Hz systems are simulated using PSCAD/EMTDC and MATLAB19a. The simulation results illustrate that the proposed technique successfully discriminates, classifies and locate the faults. Further, this technique is robust against variations in fault resistance, source impedance, fault location, mutual coupling between phases under asymmetrical faults and CT saturation. The comparative results reveal the superiority of the proposed technique against recently proposed schemes. Finally, the results under Indian Real-Time field data of a line having 144 km between Ranchi-Rourkela show the authenticity of the proposed scheme for practical implementation.

Finite-time reliable nonfragile control for fractionalorder nonlinear systems with asymmetrical saturation and structured uncertainties

This paper investigates the finite-time stabilization problem of fractional-order nonlinear differential systems via an asymmetrically saturated reliable control in the sense of Caputo’s fractional derivative. In particular, an asymmetrical saturation control problem is converted to a symmetrical saturation control problem by using a linear matrix inequality framework criterion to achieve the essential results. Specifically, in this paper, we obtain two sets of sufficient conditions under different scenarios of structured uncertainty, namely, norm-bounded parametric uncertainty and linear fractional transformation uncertainty. The uncertainty considered in this paper is a combination of polytopic form and structured form. With the help of control theories of fractional-order system and linear matrix inequality technique, some sufficient criteria to ensure reliable finite-time stability of fractional-order differential systems by using the indirect Lyapunov approach are derived. As a final point, the derived criteria are numerically validated by means of examples based on financial fractional-order differential system and permanent magnet synchronous motor chaotic fractional-order differential system.

Neural network-based adaptive trajectory tracking control of underactuated AUVs with unknown asymmetrical actuator saturation and unknown dynamics

In this paper neural-network (NN) based adaptive trajectory tracking control scheme has been designed for underactuated Autonomous Underwater Vehicles (AUVs) which are subjected to unknown asymmetrical actuator saturation and unknown dynamics. First, some control preliminaries and assumptions along with AUV kinematic & kinetic models and trajectory tracking problems are elaborated. Secondly, the tracking error model and tracking guidance law are derived based on the theory of relative motion and the principle of approach angle respectively. Then the kinematic controller is designed by using the backstepping technique and Lyapunov theory. Similarly, AUV kinetic controller is designed by using the NN compensation and adaptive estimation techniques which is termed as NN-based adaptive controller (NNAC). Pertinently, a novel bounded saturation function has been developed to describe the unknown asymmetrical actuator saturation. The NN is adopted to approximate the complex AUV hydrodynamics and differential of desired tracking velocities. The bound of the generalized disturbance, which is composed of NN approximation error and ocean disturbances, are approximated based on the adaptive estimation technique. To analyze the stability of the developed NNAC, Lyapunov theory and backstepping technique are utilized by considering the control actions on different saturation sections. Finally, effectiveness and superiority of the proposed NNAC are validated through two sets of comparative simulation studies.

Inductance Calculation of Interior Permanent Magnet Machines Considering Asymmetrical Saturation of the Bridge

The bridge of the interior permanent magnet (IPM) machine can reduce the leakage of the machine, which makes the utilization rate of the permanent magnet (PM) improved. However, the asymmetric saturation in the bridges will cause the asymmetry distribution of the magnetic potential on the rotor surface, which will bring challenges to the accurate calculation of inductances. Excited by the armature current at different initial phase angles, the flux distributions in the bridges are analyzed. Meanwhile, the reason why the asymmetric saturation exists in the bridges is revealed theoretically. Based on the above analysis, the rotor magnetic potential (RMP) model for an IPM machine with the bridges is established and used to calculate the armature reaction magnetic field and inductances of the IPM machine. In this paper, the RMP distribution in the bridges is obtained by considering asymmetric saturation, so the RMP model can reflect the rotor surface magnetic potential distribution more accurately, which is evident from the adjacent degree between the calculation results and the finite-element analysis (FEA) ones.

Improved receding horizon H∞ temperature spectrum tracking control for Debye media in microwave heating process

This paper considers the problem of tracking control for the coupled thermal-electromagnetic model with temperature-dependent permittivity in microwave heating process, where the incident electrical field is subject to the asymmetrical saturation. Due to the nonhomogeneous Neumann boundary condition and inherent infinite-dimensional characteristics for microwave heating process, it is difficult for us to readily design and implement tracking controller. With the help of improved spectral Galerkin method, the traditional partial differential equation (PDE) model is transformed into the linear finite-dimensional ordinary differential equation (ODE) model which can be subsequently used for controller design. Then, the receding horizon H∞ control strategy is improved to stabilize the derived uncertain ODE error model with asymmetrical input saturation and bounded external disturbance. The outcome of improved algorithm is formulated as a linear matrix inequalities (LMIs) optimization problem, which can be on-line updated by applying the finite-different time-domain (FDTD) method. Finally, the improved control strategy is successfully applied in one-dimensional cavity model for tracking temperature spectrum.

Adaptive quantised control of switched stochastic strict‐feedback non‐linear systems with asymmetric input saturation

The adaptive quantised tracking problem is addressed for a class of switched stochastic strict-feedback non-linear systems with asymmetrical input saturation in this study. With the aid of a Gaussian error function-based continuous differentiable switching model and some special techniques, the technical difficulties from dealing with the switching asymmetric saturation non-linearities and the sector-bounded quantisation errors are overcome. Then, by combining the common Lyapunov function method, backstepping technique and neural network approximation-based approach, a simple common adaptive tracking control scheme involving one adaptive parameter only is presented for such systems under arbitrary switching. The given quantised control scheme guarantees that all signals of the closed-loop system are semi-globally bounded in probability while the tracking error can converge to a small neighbourhood of the origin. Finally, simulation studies are provided to illustrate the effectiveness and applicability of the proposed control design.

Receding horizon H∞ guaranteed cost tracking control for microwave heating medium with temperature-dependent permittivity

This paper considers the temperature spectrum tracking control of microwave heating model, in the presence of asymmetrical input saturation, nonhomogeneous Neumann boundary condition and temperature-dependent permittivity. The sufficient condition for the existence of receding horizon H∞ guaranteed cost control is proposed based on the derived finite-dimensional ordinary differential equation (ODE) error model. Furthermore, by on-line updating and solving linear matrix inequalities (LMIs) optimization problem, the constrained tracking controller can be obtained in the sense of minimizing H∞ norm and satisfying the quadratic cost performance. The proposed control strategy is implemented on a one-dimensional cavity heating model and its performance is evaluated through the simulation.

Harmonic losses in high-speed PM synchronous machines

PurposeThe purpose of this paper is the development of a new numerical method for the calculation of the air-gap magnetic flux harmonics in synchronous machines with permanent magnet (PM) excitation. The harmonic analysis results are used as input data for the eddy-current loss calculation and for the rotor heating evaluation.Design/methodology/approachThe method is based on the finite element analysis (FEA). The model takes into account toothed stator design, rotor asymmetrical magnetic reluctance and saturation. At first, a series of static DC magnetic (magnetostatic) simulations is run. Each problem corresponds to specific rotor position and the momentary stator winding currents. The Fourier analysis performed for each problem yields the harmonic spectrum variation in time. Then, a series of AC magnetic (time-harmonic) simulations is run. Each problem corresponds to a specific harmonic. The result is the eddy-current losses distribution. After total loss is calculated, the heat transfer analysis is conducted.FindingsThe analysis reveals that 90 per cent of losses are located in the sleeve that holds PMs together. Rotor eccentricity brings even harmonics of low magnitude that have little impact on heating.Originality/valueIn general, the study requires transient electromagnetic analysis with motion. The purposed method allows to simplify the problem. The method is based on static and quasi-static (time-harmonic) problems simulation. It is fast and highly automated. The method allows simultaneous taking into account of tooth-order harmonics, stator winding harmonics and eccentricity for heating calculation.

Stabilization of Systems with Unsymmetrical Saturated Control: An LMI Approach

This paper deals with the regulator problem for linear continuous-time systems with asymmetric saturations on the control. The main contribution of this work is to extend the available results for symmetrical saturations, in term of LMIs, to systems with asymmetric saturations. Hence, LMIs formalism is obtained for the first time for asymmetrical saturation. New less conservative result on saturation is used. An example is presented to illustrate the obtained results.

Experiment and Simulation of Eddy-Current Loss inside Copper Shielding of Transformers under DC Biasing Condition

With the advent of power electronic technology, the excitation conditions applied to transformers, motors, etc. could be very atypical. DC bias excitation is an undesired working condition of AC power transformers, the asymmetrical saturation of the transformer core, the heavy noise, the serious vibration, and the local loss concentration can all potentially occurred in dc-biased transformers. The effect of the exciting current under different dc-biased magnetization on eddy-current loss in copper plate based on a reduced engineering-oriented benchmark model (TEAM Problem 21) is investigated. Experiment scheme for dc biasing is presented and the distribution of the eddy current loss under different dc-biased excitation conditions was studied in detail. The engineering applicability of three dimensional eddy current analysis methods for dc-biased magnetization field computation and the practical loss modeling are examined, which has been demonstrated via the numerical modeling results and the measured data.

Room Temperature Generation of Amplitude Squeezed Light from a Semiconductor Laser with Weak Optical Feedback.

Amplitude-squeezed states are produced from a room-temperature Fabry-P\'erot quantum-well semiconductor laser using a combination of pump suppression and weak, dispersive optical feedback. Up to 0.9 dB of squeezing is measured using a balanced homodyne detector corresponding to 1.5 dB of squeezing at the output facet of the laser. A comparison of the data to theoretical predictions suggests that the excess noise measured under free-running conditions could be a result of incomplete side-mode suppression in combination with asymmetrical cross-mode nonlinear gain saturation.

A Novel Method of Detecting Asymmetrical Transformer Core Saturation Due to Gic

A device based on the sensing of a unique symptom of sustained asymmetrical core saturation of a power transformer, due to geomagnetically induced currents (GIC), and thus indirectly indicating the presence of GIC in an EHV transmission line system, has been developed. The device can be used to achieve any of the following objectives: (1) As an alarm to permit the power system operator to take remedial measures if necessary to prevent further system disturbances during a severe geomagnetic storm. (2) As a control signal for inserting a preventive device designed to eliminate GIC-flow in the system. (3) As a blocking signal for preventing misoperation of existing protection schemes. (4) As an informative alarm signal for a false trip (if any) due to GIC, allowing the system operator to decide on the possibility of fast restoration.

A Novel Method of Detecting Asymmetrical Transformer Core Saturation Due to GIC

A Novel Method of Detecting Asymmetrical Transformer Core Saturation Due to GIC

Incremental Describing Function Analysis of Subharmonic Oscillations in Control Systems with Thyristor Converters

Often subharmonic oscillations of firing angle of thyristor converters with large magnitude in negative feedback control systems are a kind of jump phenomena. For their investigation rectifiers may be modeled by an asymmetrical saturation type nonlinearity in series with a linear block whose factors depend upon the number of pulses of the rectifier and the order of subharmonic in question. Application of the incremental describing function technique results in a set of curves, which is useful for the determination of the critical gain of the system and its design. Results of digital computer simulated systems are in good agreement with the predicted values