Showing papers on "Proportional control published in 2021"

Novel metaheuristic-based tuning of PID controllers for seismic structures and verification of robustness

Abstract: In the present study, an active structural control using metaheuristic tuned Proportional-Integral-Derivative (PID) type controllers is presented. The aim of the study is to propose a feasible active control application considering time delay and a feasible control force. In the optimum control methodology, near-fault directivity pulse was considered for ground motion. Three different metaheuristic algorithms are separately employed in the optimum tuning of PID parameters such as proportional gain, integral time and derivative time. The employed algorithms are Flower Pollination Algorithm, Teaching Learning Based Optimization and Jaya algorithm. The maximum control force limit is considered as a design constraint. The methodology contains the time delay consideration and a process to avoid the stability problem on the trial results during the optimization process. The method is explained in three stages as The Pre-Optimization Stage, The Dynamic Analysis Stage and The Optimization Stage. The optimum PID parameters of different algorithms are very different, but the performance of active control is similar since a similar control signal can be generated by different proportion of controller gains such as proportion, integral and derivative processes. As the conclusion of the study, the amount of control force must be chosen carefully since big control forces may resulted with stability problems if the control system has long delay.

Fuzzy Linear Active Disturbance Rejection Control of Injection Hybrid Active Power Filter for Medium and High Voltage Distribution Network

Abstract: In order to reduce the capacity of the active power filter (APF), improve its dynamic tracking speed and anti-disturbance ability of harmonic currents, so as to better solve the problem of harmonic pollution in the medium and high voltage distribution network, this article is suitable for medium and high voltage distribution networks. The three-phase three-wire injection hybrid active power filter (IHAPF) of high voltage distribution network is the research object, and a fuzzy linear active disturbance rejection controller (Fuzzy-LADRC) suitable for IHAPF voltage outer loop control is proposed. The controller is composed of a fuzzy proportional controller, a linear extended state observer (LESO), and a total disturbance compensation link. The introduction of fuzzy logic control solves the difficult problem of controller parameter tuning, and uses Lyapunov stability definition to prove the stability of the system. Finally, the control performance of IHAPF under the control of Fuzzy-LADRC is simulated and verified by MATLAB&SIMULINK simulation platform, and compared with the traditional PI controller. The results show that the Fuzzy-LADRC controller is better than the traditional PI controller and has good tracking and anti-disturbance capabilities.

PI Control Loop–Based Frequency Smoothing of a Doubly-Fed Induction Generator

Abstract: This paper proposes a frequency-smoothing scheme of a doubly-fed induction generator (DFIG) that can significantly eliminate the frequency fluctuations caused by continuously fluctuating wind speeds. To achieve this, a proportional-integral (PI) control loop depending on the frequency deviation instead of a proportional control loop used in conventional schemes is added to the maximum power point tracking loop. The P control loop in the proposed frequency-smoothing scheme eliminates the alternating component in the frequency deviation, whereas the I control loop eliminates the slowly-varying component. The gains for the P control loop and I control loop are suggested for effectively using the rotating masses of a DFIG while avoiding over-deceleration of the rotor speed. The simulation results evidently demonstrate that the proposed scheme nearly removes the frequency deviation under various wind conditions, by using the proposed PI control loop, especially in high penetration levels of wind.

Performance of Optimum Tuned PID Controller with Different Feedback Strategies on Active-Controlled Structures

Abstract: In this study, multi-story structures with different combinations (on each floor and only the first floor) of active tendon control systems driven by a proportional–integral–derivative (PID) controller were actively controlled. The PID parameters, Kp (proportional gain), Td (derivative gain), and Ti (integral gain) for each structure, were optimally tuned by using both the harmony search algorithm (HS) and flower pollination algorithm (FPA), which are metaheuristic algorithms. In two different active-controlled structures, which are formed according to the position of the PID, the structural responses under near-fault records defined in FEMA P-695 are examined to determine the appropriate feedback which was applied for displacement, velocity, acceleration, and total acceleration. The performance of the different feedback strategies on these two active-controlled structures is evaluated. As a result, the acceleration feedback is suitable for all combinations of the active control system with a PID controller. The HS algorithm outperforms the optimum results found according to the FPA.

Development and Application of Fuzzy Proportional-Integral Control Scheme in Pitch Angle Compensation Loop for Wind Turbines

Abstract: Wind energy is regarded as one of the oldest energy sources and has played a significant role. As the nature of wind changes continuously, the generated power varies accordingly. Generation of the pitch angle of a wind turbine’s blades is controlled to prevent damage during high wind speed. This paper presents the development and application of a fuzzy proportional integral control scheme combined with traditional proportional control in the dynamic behavior of pitch angle-regulated wind turbine blades. The combined control regulates rotor speed and output power, allowing control of the power while maintaining the desired rotor speed and avoiding equipment overloads. The studied model is a large-scale wind farm of 120 MW in the Gulf El-Zayt region, Red Sea, Egypt. The control system validity is substantiated by studying different cases of wind speed function: ramp, step, random, and extreme wind speed. The results are compared with the traditional combined control. The model is simulated using MATLAB/SIMULINK software. The simulation results proved the effectiveness of fuzzy tuned PI against traditional PI control.

Control Performance, Stability Conditions, and Bifurcation Analysis of the Twelve-Pole Active Magnetic Bearings System

Abstract: The active magnetic bearings system plays a vital role in high-speed rotors technology, where many research articles have discussed the nonlinear dynamics of different categories of this system such as the four-pole, six-pole, eight-pole, and sixteen-pole systems. Although the twelve-pole system has many advantages over the eight-pole one (such as a negligible cross-coupling effect, low power consumption, better suspension behaviors, and high dynamic stiffness), the twelve-pole system oscillatory behaviors have not been studied before. Therefore, this article is assigned to explore the effect of the magneto-electro-mechanical nonlinearities on the oscillatory motion of the twelve-pole system controlled via a proportional derivative controller for the first time. The normalized equations of motion that govern the system vibrations are established by means of classical mechanics. Then, the averaging equations are extracted utilizing the asymptotic analysis. The influence of all system parameters on the steady-state oscillation amplitudes is explored. Stability charts in a two-dimensional space are constructed. The stable margin of both the system and control parameters is determined. The obtained investigations reveal that proportional gain plays a dominant role in reshaping the dynamics and motion bifurcation of the twelve-pole systems. In addition, it is found that stability charts of the system can be controlled by simply utilizing both the proportional and derivative gains. Moreover, the numerical simulations showed that the twelve-poles system can exhibit both quasiperiodic and chaotic oscillations besides the periodic motion depending on the control parameters’ magnitude.

Enhanced tuning of Smith predictor based series cascaded control structure for integrating processes.

Abstract: This work combines the benefits of cascaded control, Smith predictor, moment matching, and outer-loop decomposition to design an enhanced series cascaded control approach with Smith Predictor for some industrial integrating plants. The inner-loop controller is assumed as a PI/PID type. If the outer-loop process model is of second-order, it is split into first-order models and an individual control-loop is established for each model. This technique is called ‘outer-loop decomposition’. PI controller is employed in the loop having a first-order lag whereas proportional control is used if the loop contains an integrator. Controller parameters are obtained by moment matching i.e. equating the Maclaurin series of expected and real closed-loop system functions. Suitable equations and procedures are given to tune adjustable parameters to attain an expected maximum sensitivity. This makes the proposed method more beneficial than the contemporary schemes that require a hit and trial search within a given range of values. It is seen that the suggested scheme yields noteworthy enhancement in closed-loop response compared to some recent strategies even in the presence of perturbed process dynamics.

Symmetrical Pole Placement Method-Based Unity Proportional Gain Resonant and Gain Scheduled Proportional (PR-P) Controller With Harmonic Compensator for Single Phase Grid-Connected PV Inverters

Abstract: In this paper, a symmetrical pole placement Method-based Unity Proportional Gain Resonant and Gain Scheduled Proportional (PR-P) Controller is presented. The proposed PR-P controller resolved the issues that are tracking repeating control input signal with zero steady-state and mitigating of 3rd order harmonic component injected into the grid associated with the use of PI controller for single-phase PV systems. Additionally, the PR-P controller has overcome the drawbacks of frequency detuning in the grid and increase in the magnitude of odd number harmonics in the system that constitute the common concerns in the implementation of conventional PR controller developed as an alternative to PI controller. Moreover, the application of an unprecedented design process based on changing notch filter dynamics with symmetrical pole placement around resonant frequency overcomes the limitations that are essentially complexity and dependency on the precisely modelled system associated with the use of various controllers such as Adaptive, Predictive and Hysteresis in grid connected PV power generation systems. The proposed PR-P controller was validated employing Photovoltaic emulator (PVE) consisting of a DC-DC Buck power converter, a maximum power point tracking (MPPT) algorithm and a full-bridge grid connected inverter designed using MATLAB/Simulink system platform. Details of the proposed controller, Photovoltaic emulator (PVE) simulations, analysis and test results were presented in the paper.

A Hybrid Control Strategy Based on Lagging Reactive Power Compensation for Vienna-Type Rectifier

Abstract: The Vienna-type rectifier is widely used in many applications due to the merits of controllable dc-link voltage, realizable three-level operation, and compact size. However, the input currents near the zero-crossing point are distorted inevitably due to its special topology. Based on the analysis of the causes of current distortion, a lagging reactive power compensation method is proposed. The $d$ – $q$ -axis current models are developed, and two finite-time current controllers are designed to enhance the interference suppression performance. The asymptotic convergence of the $d$ – $q$ -axis current systems is proved, respectively. In addition, neutral point potential balancing is achieved by employing a proportional controller without increasing the cost of the system. The validity of the proposed hybrid control strategy has been verified by simulation and experimental results. Compared with the conventional strategy, this new hybrid control strategy can help to achieve excellent performance and stronger disturbance rejection.

Research on the performance of a novel electro-hydraulic proportional directional valve with position-feedback groove:

Abstract: Accurate posture control of hydraulic roof supports, which use pressurized water as their fluid power source, is an important part and research direction of intelligent fully mechanized mining face...

Active vibration control of thin-walled milling based on ANFIS parameter optimization

Abstract: In view of the time-varying dynamic characteristics of thin-walled milling, an optimization method of thin-walled milling control parameters based on the ANFIS system is proposed. Firstly, the control system strategy design and equipment selection construction were carried out, and the fuzzy inference model was built based on matlab platform; Subsequently, the fuzzy inference model of the thin-walled workpiece milling process was obtained by collecting fuzzy inference training data set of and the ANFIS system training. The proportional control coefficient of the controller was optimized based on the input and output relation of the model. Finally, the dynamic response and surface roughness of the controlled thin-walled panel milling process before and after optimization were obtained through cutting experiments, and the effectiveness of the ANFIS method to optimize the control parameters and the reliability of the fuzzy reasoning model were verified through analysis of the reasoning results. The results show that the ANFIS system can predict the vibration response performance of the target by setting the input and output reasonably, and optimize the related variable parameters according to the predicted results, so as to make the thin-wall milling system more stable.

On the oscillatory behaviours and rub-impact forces of a horizontally supported asymmetric rotor system under position-velocity feedback controller

Abstract: This work is meant to investigate and control the nonlinear dynamical behaviours of a nonlinear asymmetric rotating shaft system. The studied system is modeled as a nonlinear dynamical system having both quadratic and cubic nonlinearities and excited at the primary resonance. A linear proportional-derivative controller is introduced to eliminate the nonlinear behaviours and to suppress the lateral vibrations of the rotating shaft. The influences of different control parameters on the oscillatory behaviours of the considered system are explored. The main obtained analytical results showed that the uncontrolled shaft may respond with forward and backward whirling motion. However, the proposed controller illustrated its feasibility in eliminating the nonlinear behaviours of the studied system and forcing it to behave like the linear systems. Moreover, the obtained results confirmed that the proportional control gain plays a dominant role in destabilizing the studied rotor system. Finally, the safe operation of the studied system with avoiding the rub-impact force occurrence is discussed.

Proportional control moment gyroscope for two-wheeled self-balancing robot:

Abstract: A two-wheeled self-balancing robot is considered for investigating the responses of a control moment gyroscope powered by a proportional controller to prevent the robot rollover against the constan...

NewtonianVAE: Proportional Control and Goal Identification from Pixels via Physical Latent Spaces

Abstract: Learning low-dimensional latent state space dynamics models has proven powerful for enabling vision-based planning and learning for control. We introduce a latent dynamics learning framework that is uniquely designed to induce proportional controlability in the latent space, thus enabling the use of simple and well-known PID controllers. We show that our learned dynamics model enables proportional control from pixels, dramatically simplifies and accelerates behavioural cloning of vision-based controllers, and provides interpretable goal discovery when applied to imitation learning of switching controllers from demonstration. Notably, such proportional controlability also allows for robust path following from visual demonstrations using Dynamic Movement Primitives in the learned latent space.

Unity Proportional Gain Resonant and Gain Scheduled Proportional (PR-P) Controller-Based Variable Perturbation Size Real-Time Adaptive Perturb and Observe (P&O) MPPT Algorithm for PV Systems

Abstract: In this paper, Proportional Gain Resonant and Gain Scheduled Proportional (PR-P) Controller based variable perturbation size real-time adaptive perturb and observe (P&O) maximum power point tracking (MPPT) algorithm is presented. The proposed control scheme resolved the drawbacks of conventional P&O MPPT method associated with the use of constant perturbation size that leads to poor transient response and high continuous steady-state oscillations. The prime objective of using the PR-P controller is to utilize inherited properties of the signal produced by the controller’s resonant path and integrate it to update best estimated perturbation that represents the working principle of extremum seeking control (ESC) to use in P&O algorithm that characterizes the overall system learning-based real time adaptive (RTA). Additionally, utilization of internal dynamics of the PR-P controller overcome the challenges namely, complexity, computational burden, implantation cost and slow tracking performance in association with commonly used soft computing intelligent systems and adaptive control strategies. The proposed control scheme is verified using MATLAB/Simulink by applying comparative analysis with PI controlled conventional P&O MPPT algorithm. Moreover, performance of the proposed control scheme is validated experimentally with the implementation of MATLAB/Simulink/Stateflow on dSPACE Real-time-interface (RTI) 1007 processor board, DS2004 A/D and CP4002 Digital I/O boards. The experimental results and analysis reveal that the proposed control strategy enhanced the tracking speed five times with reduced steady-state oscillations around maximum power point (MPP) and more than 99% energy extracting efficiency.

Control Strategy Based on Arm-Level Control for Output and Circulating Current of MMC in Stationary Reference Frame

Abstract: This paper proposed a control method for output and circulating currents of modular multilevel converter (MMC). The output and circulating current are controlled with the help of arm currents, which contain DC, fundamental frequency, and double frequency components. The arm current is transformed into a stationary reference frame (SRF) to isolate the DC and AC components. The AC component is controlled with a conventional proportional resonant (PR) controller, while the DC component is controlled by a proportional controller. The effective control of the upper arm and lower arm ultimately controls the output current so that it delivers the required power to the grid and circulating current in such a way that the second harmonic component is completely vanished leaving behind only the DC component. Comparative results of leg-level control based on PR controller are included in the paper to show the effectiveness of the proposed control scheme. A three-phase, five-level MMC is developed in MATLAB/Simulink to verify the effectiveness of the proposed control method.

Adaptive control designs for control-based continuation of periodic orbits in a class of uncertain linear systems

Abstract: This paper proposes two novel adaptive control designs for the feedback signals used in the control-based continuation paradigm to track families of periodic orbits of periodically excited dynamical systems, including black box simulation models and physical experiments. The proposed control designs rely on modifications to the classical model reference adaptive control framework and the more recent $${\mathscr {L}}_1$$ adaptive control architecture, in which an additional low-pass filter is used to ensure guaranteed transient performance and robustness to time delays in the control input even in the limit of arbitrarily large adaptive gains. In contrast to the proportional control formulations that have been used in the literature on control-based continuation, the proposed control designs achieve stable performance with a minimum of parameter tuning. In the context of a class of linear systems with matched uncertainties, the paper demonstrates the successful integration of adaptive control feedback in control-based continuation. Specifically, the control designs are shown to ensure that the control input stabilizes the sought periodic orbits of the uncontrolled system and vanishes along these orbits, provided that an a priori unknown reference input is chosen appropriately. Numerical results obtained using the coco software package demonstrate how the combination of a nonlinear solver (Newton’s method) with the pseudo-arclength parameter continuation scheme can be used to trace the correct choice for the reference input under variations in an excitation parameter.

Transient Modeling of Phase-Locked Loop and its Applications in a Multi-VSCs Grid-connected System

Abstract: Phase-locked loops (PLLs) play an important role in voltage source converters (VSCs) adopting grid-following control. In this paper, a novel transient model in time-domain is derived for PLL based on the multi-scale method in nonlinear dynamics. The transient stability criterion in singular converter system is further obtained via the analytical solution. Moreover, the applications of the transient stability criterion in multi-VSCs systems and the interactions are further explored by changing control parameters, the active power and the line impedance. Simulation and experimental results show that with the decrease of proportional gain, the increase of internal gain, the active power and the line impedance, the criterion value decreases and can be seen as a reference for the stability judgement. In addition, the degrees of interaction in multi-VSCs systems vary under different operating conditions.

Active Disturbance Rejection Control of Doubly-Fed Induction Generators Driven by Wind Turbines

Abstract: This paper proposes a robust active disturbance rejection control (ADRC) scheme to improve the low voltage ride through (LVRT) of a doubly-fed induction generator (DFIG) for wind turbine applications. There are two main parts of the DFIG control system: controlling the rotor side converter (RSC) and controlling the grid side converter (GSC). This digest replaces the proportional-integral (PI) controllers conventionally used in DFIG control with ADRC-based robust controllers. Each ADRC contains an extended state observer (ESO) for disturbance estimation, a simple proportional controller, and a proportional compensator which compensates the output of the proportional controller with the ESO-estimated disturbance to generate the final output of the ADRC scheme. The RSC inner current loop PI controllers are replaced with ADRCs in this paper. The simulations are conducted on a PSCAD/EMTDC switching level model of a 3.6 MW DFIG wind turbine connected to a power grid to verify the LVRT enhancement using the proposed ADRC method.

Vibration Control Using Pole Placement with Proportional Gain of a Flexible Manipulator Incorporating Payload

Abstract: Unpredictable and difficult to solve the problems in control of a one-link flexible manipulator and it becomes more efforts with increasing payload at the tip end of link. The model of one-link flexible manipulator was derived using a finite element method. This study presents comparison control schemes for vibration control of a one-link flexible manipulator. The control schemes, namely pole placement (PPC), linear matrix inequality (LMI) and linear quadratic regulator (LQR) controllers. The controller schemes are through proportional gain. Comparison performances of control schemes are profiled in the aspects of the capability of input tracking for the hub angle position and deflection responses of one-link flexible manipulator. A laboratory-scaled experiment of one-link flexible manipulator were conducted to validate the simulation works. The responses of the system are delivered in the time and frequency domains. Furthermore, the effects of payload on the responses with comparison control schemes are presented with PPC controller performs better than LMI and LQR. The PPC controller provides zero overshoot and faster settling time compared to two others. With only one gain of PPC can cover the vibration profiles for various payload condition with the performances smoother contrasted to two others. A close agreement between simulation and experimental works on the results shows the proposed controller performs an applicable accuracy of the controller scheme.

Power Smoothing of a Variable-speed Wind Turbine Generator

Abstract: This paper presents a power-smoothing scheme of a variable-speed wind turbine generator (VSWTG) that employs separate control gains for the over-frequency section (OFS) and under-frequency section (UFS). In the proposed scheme, an additional proportional control loop based on the system frequency deviation operating in conjunction with maximum power point tracking operation is used. In the OFS, to improve the energy-storing capability, the scheme suggests the gain of the frequency deviation control loop, which is set to be monotonously decreasing with the rotor speed while being significantly larger than that in the UFS. In the UFS, to improve the energy-releasing capability while preventing over-deceleration, the gain of the frequency deviation control loop is set to be a linear function of the rotor speed. The simulation results under continuously varying wind speeds with different wind patterns and wind speeds clearly demonstrate that the proposed scheme significantly mitigates the output power fluctuations of a VSWTG. The proposed scheme keeps the frequency within a narrow range, thereby reducing the required primary frequency control reserve for regulating the frequency under normal operations.

Improving reciprocating traveling WEDM performance by a new adaptive servo feedrate control system

Abstract: With variations in gap discharge state or workpiece height, the servo feedrate of wire electrical discharge machining (WEDM) often fluctuates, and the machining process easily becomes unstable, thereby resulting in a decrease in material removal rate or an increase in risk of unexpected wire breakage. With developments of ISO-pulse discharge pulse power supplies and reciprocating traveling WEDM, a precise discharge state monitoring system for the servo federate control system is required. In this paper, with each single discharge pulse being precisely classified and counted, more accurate feedback information can be provided to the servo feedrate control system. Then a new adaptive servo feedrate control system with a self-tuning regulator and a variable gain linear proportional controller has been proposed to improve the material removal rate and control performance. The scheme of an adaptive servo feedrate control system is analyzed. It is found that the new adaptive servo feedrate control system by using a variable gain linear proportional component has a better control performance. By adjusting servo parameters, the discharge ratios are regulated, and the servo feedrate control system can keep the gap discharge state stable. Experimental results show that the material removal rate can be improved significantly by up to 19% with the new adaptive servo feedrate control system, without sacrificing the surface quality.

Parameter tuning process for a closed-loop pneumatic actuator

Abstract: Pneumatic drives are light weight, small-sizes, simple to install and to maintain. Pneumatic drives have a robust design and operation. They are clean and cheap, have no temperature limitation, and so, they are preferred in many branches of manufacturing and process industry. The well-known pneumatic actuators are widely used in closed-loop positioning systems because of their dynamic performance and mechanical flexibility in different electro-mechanical systems arrangements. The goal of the paper is to find the parameters of a closed-loop pneumatic actuator so that a good dynamic behaviour of the system is obtained. The parametric tuning process is developed by using numerical simulation technique. So, it was seen that using a proportional controller, the pneumatic actuator has an asymptotic stability for different values of the proportional gain Kp. Starting with Kp = 8 the system remains stable, but oscillations of low amplitude appears.

Modeling and Application of Controllers for a Photovoltaic Inverter for Operation in a Microgrid

Abstract: The penetration of renewable energies in the context of distributed generation represents challenges such as maintaining the reliability and stability of the system and considering the random behavior proper of generation and consumption. In this context, microgrids make it possible to manage effectively the generation and consumption of this energy, incorporating, electronic power converters, energy storage systems, and hierarchical control schemes. This paper presents the modeling, design, and application of controllers for a photovoltaic inverter operating in island mode. For this application, the photovoltaic inverter regulates the inverter output voltage via two control configurations implemented to follow the voltage reference imposed by the scheme droop. The first control scheme is configured with a two-degrees-of-freedom controller plus a repetitive controller. In this configuration, the repetitive controller is implemented in the direct loop. The second scheme is configured with an integral proportional controller—proportional controller plus a resonant controller. This configuration is formed by an integral proportional control in the direct loop plus a resonant controller and a proportional controller in the feedback loop. Both control configurations are implemented to improve the inverter disturbance rejection capability when it feeds both linear and non-linear local loads. In addition, these configurations allow the parallel connection of inverters with good performance, using a droop scheme that allows the parallel connection of converters. The tests are carried out by means of simulations using PSIMTM, which shows that, with the implemented controllers, the total harmonic distortion of the inverter output is below 5%, as recommended by the IEEE 519-1992 standard.

Pneumatic Actuator Controlled by Proportional Valve. Experimental results

Abstract: In nowadays the pneumatic controlled systems are widely used in industrial applications where valves must be operated, where there is a fire ignition risk, or in different automation systems where a positioning action is desired. The paper presents the experimental results of a pneumatic actuator controlled by a proportional control valve. The goal of the paper is to compare the experimental results with the numerical simulation results and to improve the mathematical model associated with the experiment.

Implementation of Online Self-Tuning Fuzzy-PI (STFPI) Controller for Conical Tank System

Abstract: In the chemical process industries, the control of liquid level of a conical tank system is a difficult task due to variation present in cross-sectional area with respect to height. In the proposed research, the conical tank is categorized into three operating regions such as lower, middle, and higher regions. The tuning of PI controller parameters using conventional method is complicated, due to the presence of the inherent nonlinearities in the plant dynamics and various uncertainties, measurement noise. In this research work, the conventional ZNT method has been utilized to tune the PI controller parameters to maintain the liquid level of conical tank system. A model free controller is required and it automatically tunes the PI controller parameters such as proportional gain Kp and integral time Ti, respectively. Hence, a self-tuning fuzzy-PI (STFPI) controller has been proposed. The property of STFPI controller has greater flexible than the conventional controllers and it is also growing very fast because of its simplicity and versatility. In servo operation, the performance of the PI controller is tested in terms of performance indices values such as IAE and ISE.