Conventional Proportional Controller Research Articles

Optimal control for a photovoltaic integrated grid system using PSO and modified whale optimization to enhance power quality

The paper proposes a modified & optimized controller for PV-integrated grid-connected PV systems. As the solar power output depends on the environmental conditions, i.e., irradiation and atmospheric temperature, the maximum power from the photovoltaic (PV) module is extracted using perturb and observe (P & O) algorithm. With a variety of controllers, such as conventional proportional and integral (PI) controllers, particle swarm optimization (PSO), and the modified Whale optimization algorithm (MWOA) method based on optimum control, the power as compared to extracted from PV panels using MWOA-based controllers. A complete simulation and implementation of a single-phase grid-connected inverter are shown to verify the proposed PV controller. The power flow control and grid synchronization are also presented when the above controllers act as MPPT controllers in the proposed system. The performance of proposed system is evaluated and compared among conventional and optimal controllers under a MATLAB-Simulink environment.

A Feedback Control Strategy for a Fed-Batch Monoclonal Antibody Production Process Utilising Infrequent and Irregular Sampled Measurements

The ability to take non-invasive Raman measurements presents a unique opportunity to use one Raman probe across multiple vessels in parallel, reducing costs but making measurements infrequent. Under these conditions, infrequent and irregular feedback signals can result in poor closed-loop control performance. This study addressed the issue of infrequent and irregular Raman measurements using a linear dynamic model developed from interpolated data to predict more frequent measurements of the controlled variable. The simulated monoclonal antibody production was sampled hourly with white noise added to the simulated glucose concentration to replicate real Raman measurements. The hourly samples were interpolated into 15 min intervals and a linear dynamic model was developed to predict the glucose concentration at 15 min intervals. These predicted values were then used in a feedback control loop by using model predictive control or a conventional proportional and integral controller to control the glucose concentration at 15 min sampling intervals. For setpoint tracking, the model predictive control reduced the integral of absolute errors to 14,600 from 15,900 (with a 1 h sampling time) or 8.2% reduction. With adaptive model predictive control, the integral of absolute errors was reduced from 14,500 (1 h sampling time) to 14,200 for setpoint tracking and from 13,500 (1 h sampling time) to 13,300 for disturbance rejection. A final comparison demonstrated that the proposed method can also cope with random variations in the sampling time.

Application of the ISE Optimized Proportional Control of the Wave Maker in a Towing Tank

This paper presents the improvement of the wave maker control system. The wave maker is a facility widely used in hydromechanics laboratories to generate waves in towing tanks. It is equipped with an electrohydraulic drive and an actuator submerged into water. The waves are generated to model the environmental conditions for physical experiments, performed on reduced-scale models of maritime objects. The physical experiments allow to predict the behaviour of full-scale objects and prove the results of numerical analyses. The overriding goal of the fluid dynamics experiments is to improve the human safety and survivability of constructions. The reported investigation and application works were vital for the improvement of physical model tests. The optimization of the proportional controllers was performed in terms of the Integral of Squared Error (ISE). The final evaluation was performed in terms of the frequency response characteristic. The results of the proportional control optimization were evaluated versus the previously applied control. The experimental research was conducted in the real towing tank located at the Maritime Advanced Research Centre. The investigation has shown the advantage of the ISE optimized conventional proportional control. It has particularly proven the affordability and swiftness of the optimization process. It also proved a more efficient frequency response of the wave maker obtained within a required and reasonable lead time. The performed investigation has greatly contributed to the development of a new method of physical experiments in white noise waves. The results related to this new more efficient method are presented as well.

Fuzzy Control of Traffic Junctions in Oversaturated Urban Networks

The paper describes the design and implementation of a fuzzy controller for traffic network management in urban areas. The controller uses expert knowledge for the derivation of its fuzzy rules. The proposed controller is simulated and compared to a conventional proportional controller by means of the software platform for traffic management AIMSUN. The results show that the fuzzy controller outperforms the proportional controller.

Hybrid Dual-Loop Control for Current Regulation and Low-Frequency Ripple Rejection in Led Drivers

This paper presents a new hybrid dual-loop control system for the DC/DC LLC resonant converter, operating as a downstream DC/DC converter in a two independent stage offline LED driver. The outer loop employs a PI controller to maintain the average LED current regulated at the reference value and reject parametric variation. The inner loop implements an adaptive periodic disturbance rejection (APDR) subsystem, thus conceiving the hybrid PI\&APDR controller. The APDR subsystem is designed to strictly reject the bus voltage ripple and limit its transmission to the LED current. Experimental results show the proposed controller feasibility in achieving good tracking behavior, reduced output current ripple under different bus voltage ripple amplitude and frequency, robustness against parametric variations, and simple implementation and design. For the sake of completeness, the proposed PI&APDR is compared with the conventional proportional resonant controller employing experimental results and extra analysis based on simulations.

Extended Kalman Filter Based Linear Quadratic Regulator Control for Optical Wireless Communication Alignment

High-precision positioning of two underwater mobile robots based on laser beams alignment has been investigated in this work. Usually, the control problem addressed in laser beams aims to maintain the position of the receiver robot aligned with the transmitter robot despite the effects of noise and active disturbances. In this paper, a new state space model is proposed. The latter is more precise than the usual used two state space model [1]. Furthermore, an estimation based control strategy using Extended Kalman Filter Estimator (EKF) and Linear Quadratic Regulator (LQR) is proposed to achieve the control objectives. LQR controller is well known as optimal control design with better tuning flexibility along with intrinsic robustness properties such as noise and output disturbance rejections. The achieved performance of the proposed controller is compared to the conventional proportional (P), Proportional-Integral-Derivative (PID) and Proportional-Integral (PI) controller to analyze the improvements and stability. In addition, an investigation of a sensitivity analysis is conducted to show robustness with different process noise variances of LQR controller.

Using sigma-delta quantizer Based PI for inductive power transfer systems

<p>In this paper, a Sigma-Delta Quantizer (∑∆-Q) based Proportional and Integral control is proposed for a wireless power transfer control system, namely inductive power transfer system. The proposed control topology employs ∑∆-Qs to convert the conventional signals (analog/digital signals) into bitsreatm signals (1-bit per sample time). Considering the oversampling feature of ∑∆-Q, field programmable gate array is utilized in the implementation of the control system. To evaluate the effectiveness of the presented control topology, it is compared with an inductive power transfer control system using the conventional proportional and integral controller. For the sake of simplicity, the comparison is carried out using hardware in Loop. Both control systems exhibit almost identical responses. However, the bitstream feature of the proposed PI controller significantly helps in reducing the hardware resources (logic elements) in field programmable gate array. In addition, less wire routing and computational complexity is achieved due to absence of multipliers.</p>

Energy saving and Fuzzy-PID position control of electro-hydraulic system by leakage compensation through proportional flow control valve

In this article, the focus is on the energy efficiency along with the position control of the linear actuator used in heavy earth moving equipment. It is quite evident that linear actuators are one of the critical machinery components used in the construction and mining activities like in booms of excavation equipment. The proposed work employed two different hydraulic circuits and a contrast has been carried out in terms of the energy efficiency. In one hydraulic circuit, the conventional proportional directional control valve (PDCV) is used for the position control. In another one, an innovative solution of using proportional flow control valve (PFCV) by creating artificial leakage between the two ends of the actuator is evaluated according to its energy efficiency. The extra flow coming from the pump during position control is by-passed by PFCV rather than the pressure relief valve in PDCV. This reduces the energy loss in the form of heat and increases the efficiency of the hydraulic circuit. The simulation of the hydraulic circuit is performed using MATLAB/Simulink and results are compared with the experiments and it is found that hydraulic circuit using PFCV is 8.5% more energy efficient than the conventional circuit using PDCV. The position control of the actuator is done using PID controller tuned by the fuzzy controller.

Model Predictive Control for load frequency stabilizer

This paper deals with the importance of load frequency control (LFC) for single and interconnected power system. It is important to keep the frequency of the system and the inter area tie power stable. The goal of LFC is to maintain the frequency, the desired power output and to control the change in tie line power between control areas in an interconnected power system. Two different techniques have been implemented in this paper which are model predictive controller MPC and conventional proportional plus integral controller PI for LFC of single area power system as well as two area system. To investigate the powerful and robustness of model predictive control (MPC) technique for LFC problems in electric power system, time simulations is performed. The obtained results indicate that the MPC provide better damping to the single area system as well as two-area system in case of load disturbance compared with conventional PI controller. The studied single-area and two-area systems are modelled and simulated using Simulink/Matlab software.

An Efficient Technique Using Modified p–q Theory for Controlling Power Flow in a Single-Stage Single-Phase Grid-Connected PV System

In this paper, an efficient power conditioning unit is presented for a single-phase grid-connected photovoltaic (PV) system incorporating both maximum power-point tracking and current control algorithms in a single-stage. Modified p–q theory is applied to derive the reference signal for a hysteresis band current (HBC) controller so that the active and reactive power sharing between the PV system and the grid can be controlled independently. Enhanced stability during the internal dynamics, caused by the variations in PV generation and load conditions, is the prime aspect of the controller. The performance of the proposed p–q theory correlated HBC controller is evaluated against tracking of maximum PV power and compensation of load reactive power under the changeable atmospheric and load conditions, and also compared with the widely used conventional proportional resonant controller to justify superiority. Simulation and experiment are carried out under variable weather and different load conditions to validate acceptability of the proposed control scheme.

Remote real-time pressure control via a variable speed pump in a specific water distribution system

Pressure management (PM) in a water distribution system (WDS) can be accomplished by setting the pressure to be low and constant at remote consumer locations, through the use of a controller. The controller adjusts the speed of a variable speed pump (VSP) in real time. To study the implementation of these concepts, the installation of a VSP for PM in a real-world WDS in South Africa is investigated with a hydraulic model, to show how this can assist in addressing challenges and to determine the adequacy of various controllers. In this study, a suitable pump is installed which is sized to supply the required set pressure at maximum demand. Previously existing pressure deficiency challenges are solved. PM with recently proposed controllers, which depend on hydraulics theory, is performed for the first time for a WDS which exists in the real world. Since these controllers need to be studied under realistic conditions, stochastic water consumption is used. All controllers, including conventional proportional control, perform well. A consequence of this is that a controller without a tunable parameter can initially be used safely, and a related controller can then be tuned slowly to improve performance. Criteria for selecting an appropriate controller are given.

Modelling and Simulation of a Controlled Solenoid

In this paper a suggested control system for a solenoid coil is proposed. This control model is based on the employment of the electrical part of the solenoid with a conventional proportional, integral, and derivative (PID) controller unit to investigate the performance of the control system. A mathematical model of the system has been derived, and the entire control system simulated via the MATLAB software package. The simulation process included tuning the gain parameters of the controller unit to achieve best behaviour of the system. In the computer simulation, two mathematical models of the electrical part of the solenoid coil were implemented; the first one involved the typical transfer functions of the coil, while the second dealt with an approximate model. The obtained results showed that the control system using the approximate model of the electrical part of the solenoid coil provides a more stable system and can thus be applied with acceptable response.

Fractional PI pinning synchronization of fractional complex dynamical networks

A novel method for synchronization of fractional order complex dynamical networks using a new fractional Proportional–Integral (PI) pinning control scheme is presented in this paper. Stability of this network is proved via the Lyapunov stability theorem, and the synchronizability criterion is obtained. Although one can also design a proportional pinning control scheme to synchronize the whole network, our proposed fractional PI control is more efficient. Numerical simulations on Lorenz oscillator’s interaction over a sample network have shown that the proposed fractional PI controller can provide a faster synchronization with less overshoot to the reference state compared to conventional proportional controller with the same power consumption.

Precise tracking of highly nonlinear phase-shift full-bridge series resonant inverter via iterative learning control

This paper presents iterative learning control of the phase-shift full-bridge series-resonant inverter (PSFB-SRI). It has the merits of high conversion efficiency, medium-to-high power capacity, compact size, and low current–voltage stress on components, but the demerits of highly nonlinear dynamics that varies in a wide range depending on the operating points. The PSFB-SRI also suffers from a grid-voltage disturbance when it operates in grid-connected environment. To overcome these control problems, an iterative learning controller (ILC) supplemented with a proportional controller is developed and applied to the PSFB-SRI. Conventional proportional controller is used to improve the output current tracking performance. The ILC makes use of both previous-cycle and current-cycle learning terms which help the system output to converge to the reference trajectory. It is also simple in structure and easy to implement in practical applications. First-harmonic approximation of the PSFB-SRI model has been conducted and the resulting nonlinear large-signal model was used to construct the developed ILC. A detailed design guideline of the control parameters is provided. Numerical simulations validate the proposed control scheme, and experiments using a 500-W prototype demonstrate its feasibility.

A PIMR-Type Repetitive Control for a Grid-Tied Inverter: Structure, Analysis, and Design

This paper proposes a proportional-integral (inertial) multiresonant (PIMR) type repetitive control (PIMR-type RC) scheme for a grid-tied inverter. The proposed control scheme is composed of a repetitive controller in parallel with a proportional gain for the purpose of replacing lots of parameters of the conventional proportional multiresonant controller, and therefore, only a few parameters need to be designed. The proportional gain not only improves the dynamic response, but also enables repetitive controller (RC) to accommodate a larger RC gain, and hence a faster convergence rate. Theoretical analysis and stability analysis of PIMR-type RC are given, and then a practical step-by-step design tutorial is also provided. The experimental results validate the feasibility and outstanding performance of the proposed control scheme.

Design and Tuning of Robust Fractional Order Controller for Autonomous Microgrid VSC System

A robust controller design for the voltage control of an autonomous three-phase voltage source converter (VSC) is proposed. As compared with the conventional proportional plus integral (PI) controllers, fractional order controllers make the VSC system robust due to their fractional characteristics. The fractional PI $\lambda$ controller has an additional degree of freedom $\lambda$ along with $k_p$ and $k_i$ gains of the conventional PI controller. Detailed modeling of a VSC is used in the controller design process so as it include inner current control and filter dynamics. The outer fractional voltage controller is designed such that the VSC system satisfies a required phase margin, with improved robustness in the system and capability to attenuate the noise. The overall system stability is analyzed using both bode plot and step response, and these responses are compared with a conventional PI controller. Further, the dynamic performance of the fractional controller is evaluated by simulating the nonlinear system. A hardware prototype is also developed to demonstrate the practical realization of the controller.

Efficient fuzzy logic controller for magnetic levitation systems

Magnetic levitation is a system of suspending a body or a complete system against gravity. Suspending a system in air against gravity without using fixed structure for supporting is highly unstable and complex. In the previous research many techniques of stabilizing magnetic levitation systems were discussed. In this paper magnetic levitation controller using fuzzy logic is proposed. The proposed Fuzzy logic controller (FLC) is designed, and developed using triangular membership function with 7×7 rules. The system model was implemented in MATLAB/SIMULINK and the system responses to Fuzzy controller with different input signals were investigated. Using unit step input signal, the proposed controller has a settling time of 0.35 secs, percentage overshoot of 0% and there is no oscillation. The proposed controller is validated with a model of an existing practical conventional proportional plus derivatives (PD) controller. The PD controller has a settling time of 0.45 secs, percentage overshoot of 7% and with oscillation. Similarly, with sinusoidal input, the FLC has a phase shift and peak response of 0^0 and 0.9967 respectively, while PD controller has a phase shift and peak response of 24.48o and 0.9616 respectively. A disturbance signal was applied to the input of the control system. Fuzzy controller succeeded in rejecting the disturbance signal without further turning of the parameters whereby PD controller failed. Keywords : Fuzzy logic, levitation system, phase lead compensator, root locus, PD controller.

Comparison of GA tuned fuzzy logic and NARMA-L2 controllers for motion control in 5-DOF robot

Robots are useful in industries in many ways. In today’s economy, the manufacturing industry needs to be efficient to cope with the competition. Installing robots in the industry is often a step to be more competitive because robots can do certain tasks more efficiently than humans. Some of the manufacturing tasks in which robots perform better are assembling products, polishing, and cutting. In order to accurately perform these industrial operations, an effective controller needs to be implemented instead of conventional Proportional plus Integral (PI) controller. When a fuzzy controller is implemented directly, there will be a problem of computational complexity. Therefore, soft computing-based approach namely, genetic-fuzzy systems are proposed in this paper. Fuzzy systems have been integrated with Genetic Algorithm (GA) to optimize the scaling factors that define the fuzzy systems. GAs inspired by the process of biological evolution, are adaptive search and optimization algorithms. A system to be optimized is represented by a binary string which encodes the parameters of the system. This methodology is highly robust and imprecision tolerant. If a unique optimum exists, the procedure approaches it through gradual improvement of the fitness and if the optimum is not unique, the method will approach one of the optimum solutions. Hence, GA tuned fuzzy system is proposed and compared with NARMA-L2 controller for controlling the motion of a 5DOF robotic manipulator. This analysis has been performed using SOLIDWORKS and MATLAB/SIMULINK environments.

Model-based motion control for multi-axis servohydraulic shaking tables

The shaking table is an essential testing tool in the development of earthquake resistant buildings and infrastructure, so improving its performance is an important contribution to saving lives. Currently the bandwidth and accuracy of shaking tables is such that earthquake motion often cannot be replicated with the desired fidelity. A new model-based motion control method is presented for multi-axis shaking tables. The ability of this method to decouple the control axes is demonstrated. A linear parameter varying modal control approach is used – i.e. the modes of vibration of the system are controlled individually, with the modal decomposition repeated at each time step to account for parameter variations. For each mode, a partial non-linear dynamic inversion is performed in the control loop. Feedback is based on a combination of position and acceleration measurements. A command feedforward method is proposed to increase the tracking bandwidth, thus the controller has a two degree-of-freedom structure. Experimental and simulation results are presented for a large (43t total) six degree-of-freedom shaking table. The simulation results are based on a detailed, validated model of the table. Experimental results show that the controller gives exceptional performance compared a conventional proportional controller: for example the horizontal acceleration bandwidth is six-times higher at over 100Hz, which is also many times higher than the hydraulic resonant frequency. These results will allow a step change in earthquake simulation accuracy.

A complete modeling and simulation of DFIG based wind turbine system using fuzzy logic control

The current paper talks about the variable speed wind turbine generation system (WTGS). So, the WTGS is equipped with a doubly-fed induction generator (DFIG) and two bidirectional converters in the rotor open circuit. A vector control (VC) of the rotor side converter (RSC) offers independent regulation of the stator active and reactive power and the optimal rotational speed tracking in the power maximization operating mode. A VC scheme for the grid-side converter (GSC) allows an independent regulation of the active and reactive power to exchange with the grid and sinusoidal supply currents and keeps the DC-link voltage constant. A fuzzy inference system (FIS) is adopted as an alternative of the conventional proportional and integral (PI) controller to reject some uncertainties or disturbance. The performances have been verified using the Matlab/Simulink software.