Non-sinusoidal System Research Articles

Optimal Design of C-Type Filter in Harmonics Polluted Distribution Systems

This paper aims to find the optimal size of parameters of a C-type filter in a non-sinusoidal system using a new optimization method called the Archimedes optimization algorithm (AOA). The inductance and capacitance values of the filter are acquired in which the power loss in the Thevenin resistor and the power loss characteristics of the load bus are minimized based on a new proposed objective function. Subject to technical and practical limitations of the IEEE 519 standard, an optimization problem is defined to achieve an optimal filter design that can increase the system power quality. The effectiveness of the proposed method is proved by comparison with the recent previously published methods. The results show the effectiveness of the proposed approach using the AOA in finding the minimum power losses and the harmonic content of frequency-dependent components. Eventually, the current study confirmed that the suggested objective function minimizes power losses of fundamental and harmonic order harmonics in non-sinusoidal systems.

Passive-component-based reactive power compensation in a non-sinusoidal multi-line system

In this paper, a generalized compensation method of reactive power applicable to a multi-line system under non-sinusoidal conditions is studied. The compensation is confined to parallel compensation with passive components, i.e., inductors and capacitors. If the required reactive currents containing harmonics are given, an L–C network, composed of passive components and generating the required reactive currents, is synthesized. The proposed L–C network is composed of a star-connected part and a circular connected part. It is shown that the proposed method is comprehensive, easy, and systematic to apply.

Nonlinear Compound Control for Nonsinusoidal Vibration of the Mold Driven by Servo Motor with Variable Speed

In this paper, a fuzzy PI control method based on nonlinear feedforward compensation is proposed for the nonsinusoidal vibration system of mold driven by servo motor, rotated in single direction with variable speed. During controller design, there are mainly two issues to consider: (i) nonlinear relationship (approximate periodic function) between mold displacement and servo motor speed and (ii) uncertainties caused by backlash due to motor variable speed. So, firstly, the relationship between mold displacement and motor rotation speed is built directly based on the rotation vector method. Then, an observer is designed to estimate the uncertainties and feedforward compensation. Secondly, as the motor rotates in single direction with variable speed, a fuzzy control with bidirectional parameter adjustment is adopted to improve rapidity and stability based on the traditional PI method. Finally, some simulation results show the effectiveness of the proposed control method.

Mold Oscillating System with Optimized Non-Sinusoidal Oscillation Profile

A mold oscillating system for continuous casting machines has been developed based on a nonsinusoidal oscillation profile with an online oscillation control capability. A new type of the mold oscillating system is proposed comprising two servomotor-driven eccentric shafts. The principle of operation of a non-sinusoidal oscillation system is described. Based on the analysis of the non-sinusoidal oscillation waveform expressed as a piecewise linear function, the angular speed of a servomotor necessary to realize such oscillations was determined. A procedure for calculating process parameters was developed. The model of synchronized control of the casting speed and oscillation frequency was optimized and process parameters were calculated for the deviation factor of 20% and amplitude equal to 4 mm. The mold oscillating systems of sinusoidal and non-sinusoidal type were compared. The advantages of the non-sinusoidal type of oscillating system were shown, which include a decrease in depth of the oscillation marks on the surface of continuous-cast billet, an improvement in the mold-ingot lubrication conditions, and higher quality of continuous-cast billets.

Application of mixed integer distributed ant colony optimization to the design of undamped single-tuned passive filters based harmonics mitigation

Abstract The purpose of this study is to find the optimum sizing parameters of the undamped single tuned filter in the nonsinusoidal system by using a new method called Mixed Integer Distributed Ant Colony Optimization. The inductance and capacitance values of the filter are obtained for each criterion where the power factor is maximized, the losses power in Thevenin's resistor is minimized or the transmission efficiency is maximized complying with the technical and practical constraints based on IEEE Std. 519-2014 and IEEE Std. 18-2012. A detailed study has been performed and discussed where global minimum and maximum are achieved after considering the loads being nonlinear, the value of the filter that would introduce resonance, voltage total harmonic distortion, the consequence of the Thevenin's impedance on the load voltage and the practical values of the capacitor. The obtained optimum value of a single tuned filter is used to explain the system performance by evaluating other functions. The effectiveness of the proposed method is proved by comparison with previous publication and other evolutionary computation techniques which are genetic algorithm and particle swarm optimization.

Compensation of Harmonics in Residential Distribution System Using Virtual Impedance

this paper presents the modeling of nonlinear load used in domestic and small scale industrial distribution system. Proportional integral controller is used for the current control, fuzzy based MPPT is used for the variation of power from PV due to the change in atmospheric condition. Harmonics are compensated by the virtual impedance implementation. However due to increasing implementation of multiple distributed generation in residential areas, DG grid interfaced converters are used to improve the power quality. Harmonic analysis of the distribution system is used to study the behavior of equipment connected in the non-sinusoidal system environment for designing and optimal location of filters. THD is used as harmonics index to study the effect of these nonlinear loads at utility. In depth analysis and comparison of different compensation schemes based on the virtual harmonic damping impedance concept are carried out. The effect of harmonics and the compensations are verified by the analysis and simulation by MATLAB/Simuink.

A simple algorithm for amplitude estimation of distorted power system signal

Abstract This paper presents development and implementation of a novel digital signal processing algorithm for on-line estimation of peak value of the fundamental component of a non-sinusoidal power system signal. The algorithm relies on stable band-pass first and second degree digital integrator based rigorous mathematical deduction and recombines itself with zero-crossing avoiding technique. Compared with the well-established technique such as the enhanced phase-locked-loop (EPLL) based system, the proposed algorithm provides higher degree of immunity and insensitivity to harmonics and noise, and faster response. Based on simulation studies, performances of the proposed algorithm at different operating conditions have been presented and its accuracy and response time have been compared with the EPLL systems. Moreover, a simple laboratory setup implemented by MATLAB and dedicated hardware is built to verify the performance of the proposed algorithm in real time applications. The framework of laboratory prototype has been given out and the necessary modification in proposed algorithm for on-line implementation has been discussed.

Harmonic assessment‐based adjusted current total harmonic distortion

Power systems suffer from harmonic distortion and extra ohmic losses associated with them. Moreover, all harmonic frequencies are mostly assumed to have the same effect on the system losses. However, the frequency-dependency of the resistances should be taken into account, so that the apparent power and the power factor have to considerably reflect power losses under non-sinusoidal conditions. In this study, the difference between unweighted and weighted non-sinusoidal losses is addressed. A new harmonic-adjusted total harmonic distortion (THD) definition is proposed for both voltage and current. Besides, a new formula that relates the proposed harmonic-adjusted THD and a generalised harmonic derating factor definition of the frequency-dependent losses of the power transmission and distribution equipment is derived. An optimal C -type passive filter design for harmonic mitigation and power factor correction based on the minimisation of the proposed harmonic-adjusted THD for a balanced non-sinusoidal system is introduced. A comparative study of the proposed filter design based on the new harmonic-adjusted definition, and a conventional filter design based on standard THD definition, is presented.

Properties of the generalised power theory: universality and partitioning/augmentation properties

The power theory, which can be applied to a power system with transmission/distribution lines with unequal resistances, has useful properties of universality and partitioning/augmentation. Its definitions for apparent power and power factor are consistent from a sinusoidal single-phase system to a non-sinusoidal multi-line system. This study shows that a power system can be partitioned into sub-power systems if some conditions are satisfied and further, it is shown that the sub-power systems can be combined into a large power system. The application area of the concept of apparent power and power factor can be extended with consistency from a single system to a large combined system. The usefulness of the properties in analysing and designing combined power systems is illustrated using examples.

REACTIVE POWER COMPENSATOR WITH SMOOTH CONTROL

Reactive power compensation devices are widely used: thyristor-control reactors (TCR) and thyristor-switched capacitors (TSC). The TCR disadvantages are discussed. The TSC disadvantages are: influence of higher harmonics on nonsinusoidal voltage power system, the inability to ensure the smooth regulation. The proposed reactive power compensator consists of series with active filter and capacitors with step switch. Reactive power compensator’s control system is proposed. Hysteretic control of the inverter with current feedback is applied. DC-voltage regulator provides balance of active power. The control system allows overcompensation or undercompensation of reactive power modes. Reactive power distribution regulator performs the redistribution of power between switching capacitors and active filter. Minimization condition of this regulator is active filter’s power. Adjustment properties of reactive power compensator are analyzed. The choice of relations between the capacitors TSC steps to minimize the installed capacity of the active filter and the number of stages in TSC is considered. The approach that makes possible to «isolate» capacitors from harmonic currents and provide smooth control of reactive power is proposed

Research on the Influence of Load Disturbance on the Crystallizer PID Control System

Based on the simulation model of hydraulic servo non-sinusoidal vibration control system by MATLAB/Simulink,the paper analyzed the degree of the best performance under different types of load disturbance on the crystallizer PID control System, and discussed the influence the amplitude and frequency of load disturbance on the control system. It has certain theoretical guiding significance for practical production.

Recursive Pyramid Algorithm-Based Discrete Wavelet Transform for Reactive Power Measurement in Smart Meters

Measurement of the active, reactive, and apparent power is one of the most fundamental tasks of smart meters in energy systems. Recently, a number of studies have employed the discrete wavelet transform (DWT) for power measurement in smart meters. The most common way to implement DWT is the pyramid algorithm; however, this is not feasible for practical DWT computation because it requires either a log N cascaded filter or O (N) word size memory storage for an input signal of the N-point. Both solutions are too expensive for practical applications of smart meters. It is proposed that the recursive pyramid algorithm is more suitable for smart meter implementation because it requires only word size storage of L × Log (N-L), where L is the length of filter. We also investigated the effect of varying different system parameters, such as the sampling rate, dc offset, phase offset, linearity error in current and voltage sensors, analog to digital converter resolution, and number of harmonics in a non-sinusoidal system, on the reactive energy measurement using DWT. The error analysis is depicted in the form of the absolute difference between the measured and the true value of the reactive energy.

The Research on Non-Sinusoidal Vibration Control System of Continuous Casting

This paper studies the math functions about non-sinusoidal vibration waveform of the continuous caster, simulates the continuous caster non-sinusoidal vibration waveforms displacement and velocity curve ,and creates a model of the mold oscillation control system. Besides, we use MATLAB to judge the stability of the control system and system simulation and verify the feasibility of the control system through the field's test.

Simulation and Study on Non-Sinusoidal Oscillation Control System of Continuous Casting Mold

The paper describes the composition and working principle of the mold oscillation control system. The mathematical model of hydraulic servo control system is established. The total system transfer function is established by MATLAB program. By using the SIMULINK module, we determined various components’ parameter values. We got different simulation curves and Bode plots by inputting non- sinusoidal function and carrying out the dynamic simulation to the mold oscillation mathematical model, we also analyzed stability of the whole system to verify the accuracy of system design.

The Model and Simulation of Hydraulic Non-Sinusoidal Vibration System on Billet Caster Crystallizer

Study focusing on the dynamics of the crystallizer hydraulic non-sinusoidal vibration system in the bullet caster crystallizer, which is employed in an electric furnace factory, is introduced. With respect to construct a mathematical model of continuous casting crystallizer hydraulic vibration system, a power band graph method is applied. With the utilization of this method, a process of modeling and evaluating the performance of the hydraulic cylinder, electric-hydraulic servo and sensor system is conducted. The system is also analyzed and simulated by MATLAB/SIMULINK. In our experiment, the performance of the crystallizer non-sinusoidal vibration system with the change of main parameters is studied. Furthermore, an experiment is also conducted aims at investigating the quality requirements for the servo system, including stability, rapidity, and accuracy. Furthermore, an experiment is also conducted aims at investigating the quality requirements for the servo system, including stability, rapidity, and accuracy. The results demonstrate that crystallizer hydraulic servo non-sinusoidal vibration system can satisfy high frequency steel ball requirements and small amplitude design requirements. In addition, it can effectively improve the surface quality of casting blank.

Research on the Elastic Vibration Response of New Non-sinusoidal Oscillation System for the Mold

A new type of non-sinusoidal oscillation system for the mold made up of anti-parallel equal-crank four-bar linkage and the cascaded whole-leaf spring oscillation mechanism.Elastic dynamic model coupled by torsional and linear vibration is set up with lumped parameter method and equations of motion is also built.Elastic vibration response is solved in time domain,which shows motion law of mold becomes distortion in some working frequency.In frequency domain,it is given that resonance is the cause of distortion motion of mold by FFT,and harmonic increases with bigger amplitudes in these frequencies.Furthermore,effects on the motion law of excitations are analyzed,which proves that the inner excitations with multi-frequency determine the resonance frequency of the system and external excitation only influence resonance peak value.So the study can provide theoretical basis for application of the system and research on the kinematic stability of the non-sinusoidal oscillation system.

An extension to definition of apparent power for multiphase systems in non-sinusoidal conditions

The generalized definition of apparent power for multiphase systems in non-sinusoidal conditions is extended in this paper. The meaning of apparent power is still a matter of discussion. The apparent power definition for unbalanced three-phase systems is in two schools of thought. The first school is based on a pure theoretical approach and the second is related to the IEEE 1459–2000 standard, which is based on practical concept. Both approaches define the apparent power as the maximum active power that can be delivered to the load for unchanged load equivalent voltages and currents. This paper at first, reviews the theoretical approach of apparent power definition for three-phase unbalanced systems. Then this definition is extended using a vector space for multiphase power systems. This extension of the generalized definition considers a system which not only could be unbalanced but also could include non-sinusoidal voltage and current waveforms. It also considers unequal line resistances. An example is presented which compares the results obtained using this method with the results of the IEEE approach. A three-phase unbalanced non-sinusoidal system in which a rectifying diode is employed in one of the phases is also used to further evaluate performance of different power definitions under study. By using an exact model to define the apparent power, the proposed extended definition provides accurate results. Copyright © 2010 John Wiley & Sons, Ltd.

A New Fuzzy-Based Representative Quality Power Factor for Unbalanced Three-Phase Systems With Nonsinusoidal Situations

Under ideal sinusoidal operating conditions, the definition of power factor for single-phase and balanced three-phase systems is unique and meaningful. However, in nonsinusoidal situations and/or unbalanced three-phase system operation, different power factors have been proposed to deal with these situations. In this paper, a new fuzzy-based representative quality power factor (RQPF) is introduced to represent three recommended power factors: 1) fundamental positive-sequence power factor (FPSPF); 2) transmission efficiency power factor (TEPF); and 3) oscillation power factor (OSCPF). In addition, the problem of defining power factor for the three-phase system is formulated and the RQPF module is explained. In order to test the validity of the proposed fuzzy-based module, the RQPF is applied to different cases: balanced, unbalanced, linear, nonlinear, sinusoidal, and nonsinusoidal. The results obtained reveal that the new RQPF is meaningful and accurately represents the existing power factors in all cases and in all situations. Taking into consideration the advantages of fuzzy systems, this factor is useful for power quality evaluation, cost-effective analysis of PQ mitigation techniques, as well as billing purposes in these situations.

Low-frequency Resonance of Mold Driven by Oval Gears

In production practice,some continuous casters suffer from severe resonance during their starting although the vibration frequency of mold is much lower than the natural frequency of the vibration system.The resonance can cause shake of liquid steel level and,more seriously,even industrial accident such as breakout.In view of this phenomenon,the torsional vibration model of non-sinusoidal oscillation system driven by oval gears is built up.And the dynamics equations are deduced.Low-frequency resonance is discussed.Factors which influence the resonance frequency are considered.A solid foundation for solving the running smooth problem of the mold and for better application of the oscillation device is laid.

Maximum power throughput in the multiphase brushless DC generator

An advanced control technique for maximum power throughput of the multiphase brushless DC (BLDC) generator is presented. In a generator of given rating the weight and size of the system affect the fuel consumption of the generation system directly, especially in vehicle applications. Therefore maximum power density is one of the most important issues in a stand-alone power generation system. A BLDC generator itself has high power density from the machine point of view and additional increases by special control means can be expected. Conventional rectification methods cannot achieve the maximum power possible because of nonoptimal current waveforms. An optimal control scheme to maximise power density and minimise machine size and weight in a multiphase, nonsinusoidal power supply system is proposed, incorporated into a control system, and verified by simulation and experimental work.