Presence Of Nonlinear Elements Research Articles

Digital Frequency Response-Based Optically Isolated Wire-Wound Hall Current Sensor Scheme for Sinusoidal Current Waveform Measurement

The increasing requirement for reliable power demands robust protection with excellent waveform sensors. The presence of nonlinear elements in the modern-day loads brings challenges in sensing the current waveform, which is different from the conventional sinusoids. This research article proposes a novel current waveform sensing philosophy with the help of five numbers of series-connected wire-wound Hall current sensors. Signal conditioning circuits and their mathematical expressions are also discussed here to estimate the current waveform with 9.6% ± 2.4% linearity and 2.1%/A ± 1.3%/A sensitivity. The sensing technology senses the current waveform with a root mean square error (RMSE) value of 0.2. Apart from sensing the typical sinusoidal current waveform, the proposed sensing philosophy also senses the impulse and switching current waveforms with RMSE values 2.7 and 0.65, respectively. These results have a broad scope of improvement by implementing more wire-wound Hall current sensors in series. Digital output features and the optical link between the sensor and receiver offer necessary isolation to the microcontroller against harmful transients and other waveform distortions. The experimental verification and required data analytics confirm the applicability of the sensor with substantial accuracy, sensitivity, and linearity.

Maiden Application of a Modified HBA-Optimized Cascaded (2DOF + FOPIDN)-PD Controller for Load Frequency Control of Diverse Source Power System

Electricity has become one of the most essential components of establishing a quality standard of living in any country. Consequently, considerable work has been focused on designing a sophisticated load frequency control (LFC) system. However, in light of limited resources and real-world challenges, computationally based control algorithms that are more effective and less expensive remain critically needed. Thus, this paper employs a modified honey badger algorithm (HBA) in conjunction with the concepts of Lévy flight and inertia weight to optimize the parameters of a new cascaded two-degree-of-freedom fractional-PID structure coupled with a proportional derivative (2DOF + FOPIDN)-PD controller to solve LFC problems in an interconnected power system (IPS) comprising conventional and renewable energy sources (RES). The proposed control technique is applied to a two-area IPS under diverse load conditions and in the presence of nonlinear elements and electronic devices. The proposed method is evaluated with respect to a range of performance metrics, such as settling time, undershoots, and error criteria values. The collective performance of the established control scheme indicated that the suggested control approach provides excellent reliability under various load condition scenarios, sensitivity tests, and perturbations, proving the system’s efficacy and dependability.

A Mathematical Description of Dynamic Modes of Operation of the Autonomous Power Supply System in the Presence of Nonlinear Elements in Its Composition

Methodological provisions for studying transient processes in the systems of autonomous power supply with a chemical current source are considered in the presence of nonlinear elements in the voltage control system. The method of statistical linearization has been used to study the dynamics of this system. The equivalent circuit of the system and the mathematical apparatus that allows one to determine the statistical amplification coefficients have been suggested. The stationary random process to change power consumption from the power supply is represented as a mathematical expectation and a decreasing correlation function, and the electrochemical cell in the transition mode at the section a slow change in the output coordinate is considered as an aperiodic link of the first order. Two methods to solve the obtained system of equations, which describes a change in the voltage at output of an electrochemical cell, have been suggested: the method of successive approximations and the graphical method. An example of calculation of the transient process of an autonomous power supply system with an electrochemical cell has been considered.

EM Fields Generated by a Scale Model Helical Antenna and Its Use in Validating a Code for Lightning-Induced Voltage Calculation

This paper aims at validating a code for the evaluation of lightning-induced overvoltages developed in the PSCAD-EMTDC environment using experimental results obtained on an experimental facility deployed at the University of Sao Paulo, Brazil that emulates the return stroke channel with a helical antenna. For this reason, suitable expressions for the helix electromagnetic fields are presented and conditions under which they can be approximated with the ones produced by the classical lightning channel model (i.e., a vertical antenna) are derived. Moreover, the analysis of the deviations between measurements and calculations is used as a tool to propose a channel vertical coordinate dependent function for the speed that guarantees the best fitting. The validation is done considering different line configurations, from a single line to a complex layout with one main feeder and many laterals and in the presence of non-linear elements, such as surge arresters.

Structural identifiability and sensitivity.

Ordinary differential equation models often contain a large number of parameters that must be determined from measurements by estimation procedure. For an estimation to be successful there must be a unique set of parameters that can have produced the measured data. This is not the case if a model is not structurally identifiable with the given set of inputs and outputs. The local identifiability of linear and nonlinear models was investigated by an approach based on the rank of the sensitivity matrix of model output with respect to parameters. Associated with multiple random drawn of parameters used as nominal values, the approach reinforces conclusions regarding the local identifiability of models. The numerical implementation for obtaining the sensitivity matrix without any approximation, the extension of the approach to multi-output context and the detection of unidentifiable parameters were also discussed. Based on elementary examples, we showed that (1°) addition of nonlinear elements switches an unidentifiable model to identifiable; (2°) in the presence of nonlinear elements in the model, structural and parametric identifiability are connected issues; and (3°) addition of outputs or/and new inputs improve identifiability conditions. Since the model is the basic tool to obtain information from a set of measurements, its identifiability must be systematically checked.

Resource Efficient Proportional-Integrated Controller

Proportional-integral (PI) controllers are used for continuous control of technological processes' parameters. Algorithms of Pi-controllers have not undergone fundamental changes over the past decade. Manufacturers do not propose controllers that exceed the standard Pi-controller on several key technical characteristics, which include expense of energy and resources, accuracy of control and stability margin. Therefore, this article offers resource-efficient Pi-controller. Its use allows to achieve the following objectives: to save energy and resources, to improve automatic control accuracy and to increase the stability margin. A universal energy- efficient PI-controller is put as a basis of this design. Manufacturing tolerances are used to improve its technical characteristics. Situational approach is applied in solving the problem. Computational experiments were carried out for the seven known models of objects of control with the transport delay to assess the effectiveness. In the linear case the superiority of resource-efficient PI-controller compared with energy- efficient PI-controller is characterized by the following results: - the summary changing of the output of controller (modulo) decreases on average 1,75 times. This helps to save energy and resources of actuator; - the error of maximum control is reduced by an average of 1,2 times, thereby increasing the quality of products; - an average operation time of the actuator is decreased by an average of 1,3 times. This ensures resources savings of the actuator. The following fact indicates the increase of stability margin: if the coefficients of transmission of control objects increased to values when the automatic control system with PI-controller is at the limit of stability, then continuous oscillations are observed in the automatic control system with PI-controller. Herewith an acceptable quality of control is realized in the automatic control system with a resource-efficient PI-controller, since the maximum control error is less in 5 times. The benefits of resource-efficient PI-controller are preserved in a variety of operating conditions - in the presence of nonlinear elements and the various controller setting. The presented results confirm the high efficiency of resource-efficient PI-controller compared with both PI-controller and energy- efficient PI-controller. Comprehensive solution of improvement problem of the basic technical characteristics of the PI-controller determines the practical value of the work. Companies of chemical and related industries are interested in the use of controllers to enhance the effectiveness of automatic control systems.

Влияние нелинейных эффектов на спектральную эффективность многовходовых антенных систем

The analysis technique and design algorithm are proposed for multiinput antenna systems, based on the mathematical model developed. The technique and algorithm described allow the analysis of a wide class of multiinput systems, in particular, MIMO systems, reconfigurable multiantenna systems, multiinput systems with nonlinear components and devices. The paper presents numerical analysis results of the intermodulation interference effect on the spectral efficiency of a multiinput system with nonlinear elements in receiving antennas, obtained using the methods, algorithms and software products developed. It is shown that in the nonlinear system intermodulation interferences appear, and the spectral efficiency of the data transmission system decays near the operating frequency due to the appearance of additional combinational components in the frequency response of the system. This effect depends on the degree of nonlinearity, radiated power, the level of interfering signals. Based on the results obtained, it was concluded that the presence of nonlinear elements and devices must be taken into account in the design and analysis processes of multiinput multiantenna systems, considering the specific types of those nonlinearities.

Fuzzy Logic based Fault Classification of Impulse Test Records

A fuzzy logic approach is proposed for identification and classification of faults based on records obtained during impulse tests on transformers. The outputs of three filters form the basis of identification. Experiments are performed on a physical lumped parameter model of a winding to identify breakdown, partial discharge and the presence of non-linear element within the winding. The location of breakdown can also be estimated.

Efficient transient simulation of embedded subnetworks characterized by S-parameters in the presence of nonlinear elements

This paper presents an efficient technique for transient simulation of linear subnetworks characterized by S-parameters in the presence of nonlinear components. The proposed method is based on the recently developed model-reduction technique, complex frequency hopping. A new algorithm for computing the moments of S-parameter-based subnetworks is presented. The proposed method is suitable for simulating large number of S-parameter-based subnetworks in a general circuit environment consisting of lumped/distributed elements and nonlinear devices.