Active Gas Thrust Bearing With Embedded Digital Valves and Backpressure Sensors

A Static Synchronous Compensator (STATCOM) is one of the Flexible AC Transmission System (FACTS) device which plays an vital role in power system network in alleviation of small and large transient disturbances and better voltage regulation. This paper proposed a self tuning Proportional-Integral (PI) controller for STATCOM which provided a voltage support at point of common coupling (PCC). Self tuning of PI controller was achieved by adapting PI controller gains with system parameters by using Bats Echolocation controller which mimics the Bats Echolocation behavior. In the proposed controller, the system voltage (parameter) at point of common coupling compared with reference voltage and then Bats Echolocation Controller updates the PI controller gains according to the variation obtained between them. This paper also proposed a Cascaded Multilevel Inverter (CMLI) instead of conventional Voltage Source Inverter (VSI) for STATCOM to obtain better voltage regulation at point of common coupling. The voltage imbalance between H-bridge cells in CMLI was rectified by prosing Multicarrier Pulse Width Modulation (PWM) techniques, The proposed controller was validated by comparing the simulation results with fixed gain PI controller and Self tuning PI controller using Neural controller and Particle Swarm Optimization.

The main problem of using a Proportional Integral (PI) Controller in Brushless Direct Current (BLDC) motor speed control is tuning the PI’s parameter and its performance cannot adapt to the system behavior changes. Particle Swarm Optimization (PSO) has been chosen to optimize the tuning. Fuzzy Logic Controller (FLC) is used to online tuning PI’s parameters to adapt to system conditions. Optimal adaptive PI, which combines the PSO method and FLC method to tune PI, is proposed. It was successfully implemented in the simulation environment. The test was carried out in three conditions: step responses, set-point changes, and disturbance rejection. The proposed algorithm is superior with no overshoot/undershoot. Whereas in terms of settling time is in between PI and PI-PSO. PI controller has the smallest control effort. However, the other parameter is the worst. PI-PSO is superior in terms of settling time and Integral of Absolute Error (IAE) except for the step response test. The proposed method has lower IAE and higher control effort by 78.73 % and 60 % compared to PI control. On the other hand, it has a higher IAE dan lower control effort by 11.82 % and 33.88 % compared to PI-PSO. Therefore, the optimal adaptive PI control can reduce energy consumption compared to optimal PI with better performance than PI control.

Proportional Integral (PI) controller has attracted researchers in industrial control processes because of its simplicity and robust performance in a wide range of operating conditions. It has been used to provide proportional delay differentiation on web servers in previous work. However, PI controller cannot achieve satisfactory results due to (1) the web server's non-linearity properties, and (2) the difficulty of building an accurate model for the web server. To address these issues, a nonlinear fuzzy PI controller is proposed in this paper, which has the advantage of fuzzy controller while maintaining the simplicity and robustness of PI controller. The proposed controller are self-tuned according to the periodical online performance measurement. The experimental results demonstrate that our fuzzy PI controller outperforms the PI controller in several aspects.

A novel, high-speed, high temperature, oil-free, foil thrust bearing test rig has been developed with a critical element being a double-acting, active magnetic thrust bearing. The magnetic thrust bearing is used to react against loads applied to the foil thrust bearing under test. The magnetic bearing has the capability of reacting against thrust loads of up to 2224 N (500 pounds) at speeds to 80,000 rpm, while the rotor is supported by foil journal bearings. Two issues that are especially challenging for this test rig are magnetic material selection and the electronic control system. The magnetic material selection is critical due to the high centrifugal stresses that occur at 80,000 rpm. The electronic control system must handle the non-linear variation in stiffness and damping that is seen by the magnetic thrust bearing as the foil thrust bearing is loaded, as well as maintain rotor system stability as the foil bearing is purposefully overloaded to the point of failure to discover maximum load and performance capabilities. This paper describes the design of the active magnetic thrust bearing, the material selection process, and the development of a digital signal processor based control system. Typical experimental data obtained during operation of the test rig will also be presented.

Augmenting effectiveness of control loops of a PMSG (permanent magnet synchronous generator) based wind energy conversion system by a virtually adaptive PI (proportional integral) controller

This paper proposes a design of modified Guo Tao based optimized Proportional Integral (PI) controller for the level control system. The performance of a designed system is compared with Fuzzy PI and conventional PI controller. The parameters of PI controller are optimized using Genetic Algorithm (GA) with Elite Preservation Strategy (EPS). Guo Tao proposed a subspace searching GA (GTA) in his research. Limitations of Guo Tao's algorithm (GTA) motivate us to propose a modified GTA using elite preservation strategy. Multi-parent crossover is used with EPS to enhance the performance of controller. A transfer function of a level loop of fabricated experimental setup is obtained by using the step response analysis. The performance of proposed controller is checked and verified by transfer function analysis using Ziegler Nicholas (Z-N) method in MATLAB environment. The proposed controller algorithm possesses an excellent transient response as compare to Fuzzy PI and conventional PI controller.

Traditional centralized power stations face challenges such as high greenhouse gas emissions, reliance on non-renewable resources, and inefficiencies in meeting peak power demand. Additionally, Renewable Energy Sources (RESs) like solar and wind complicate efforts to maintain a consistent power supply and grid stability. This study proposes a Hybrid Renewable Energy System (HRES) that integrates a Photovoltaic (PV) system with a Doubly Fed Induction Generator (DFIG) based Wind Energy Conversion System (WECS) to address these challenges. The PV system incorporates a High Gain Cubic Boost Converter (HG-CBC), regulated by a Raccoon Optimized Algorithm (ROA) based Proportional Integral (PI) controller, to enhance voltage levels. The DFIG based WECS stabilizes power flow through a Pulse Width Modulation (PWM) rectifier and a PI-controlled PWM generator. Moreover, a 3-phase Voltage Source Inverter (3Φ VSI) converts DC power into AC for grid integration. Experimental verification using MATLAB/Simulink demonstrates a high efficiency of 98%, showcasing the model's ability to significantly boost system reliability and suitability for HRES-powered grids.

PurposeThis paper aims to study the influence of cylindrical texture parameters on the lubrication performance of static and dynamic pressure thrust bearings (hereinafter referred to as thrust bearings) and to optimize their lubrication performance using multiobjective optimization.Design/methodology/approachThe influence of texture parameters on the lubrication performance of thrust bearings was studied based on the modified Reynolds equation. The objective functions are predicted through the BP neural network, and the texture parameters were optimized using the improved multiobjective ant lion algorithm (MOALA).FindingsCompared with smooth surface, the introduction of texture can improve the lubrication properties. Under the optimization of the improved algorithm, when the texture diameter, depth, spacing and number are approximately 0.2 mm, 0.5 mm, 5 mm and 34, respectively, the loading capacity is increased by around 27.7% and the temperature is reduced by around 1.55°C.Originality/valueThis paper studies the effect of texture parameters on the lubrication properties of thrust bearings based on the modified Reynolds equation and performs multiobjective optimization through an improved MOALA.

The performance of air foil thrust bearings (AFTBs) is studied for aligned, distorted and misaligned operating conditions on the basis of a very detailed numerical model for the foil sandwich. The exact geometry of the bump foil is modeled by a Reissner–Mindlin-type shell theory. A penalty-type contact formulation including frictional effects is applied for the contact between top foil and bump foil as well as between bump foil and base plate. The minimal film thickness within the thrust bearing is used as a criterion for comparing different air foil thrust bearings with rigid thrust bearings. If the rotor disk and the base plate are perfectly parallel (aligned conditions), AFTBs are proved to have always a lower load capacity than (optimized) rigid thrust bearings due to unequal bump foil deformations and top foil sagging effects. This finding is in contradiction to previous works based on simplified foil models, which claimed AFTBs to be superior to rigid thrust bearings. Furthermore, for both operating conditions—thermally induced distortions of the rotor disk as well as misalignment—an individual pad of an AFTB is found to be unable to effectively compensate for the disturbance in the gap function. Consequently, a tailoring of the stiffness distribution in the AFTB is shown to be of limiting effect. Instead, the overall compliance of the pads in an AFTB is demonstrated to be the essential reason for the superior behavior of AFTBs to rigid thrust bearings under misaligned conditions.

This paper deals withthe comparative study of single phase Power Factor Correction (PFC)based on fixed Pulse Width Modulation (PWM) and variable frequency control techniquesusing Bridgeless Cuk converter. Design equations and state model of the BridglessCuk converter to aid the control loop are derived based on the modes of operation. The control strategy uses an outer Proportional Integral (PI) controller to normalize output voltage and inner PI controller to shape the input current. PI controller parameters are determined using Tyreus-Luben method. Simulation results are presented to validate the two approaches. Advantages of the proposed scheme are simple method of generating reference currents using the multiplier approach, power factor close to unity, low %THD, regulated output voltage for load variations and effective set point tracking.

A comparative analysis of sliding mode control and PI controller for the operation of boost converter is presented in this paper. Proportional (P), Proportional Integral (PI), Proportional Integral Derivative (PID) controllers are the widespread linear control technique which are very ordinary and less costly for adjustment to a particular specification or requirement. Many industries use these controllers. On the other hand there is one non-linear sliding mode control (SMC) technique. It has many advantages like fast dynamical response, ingrained robust features of SMC. In the present paper, the boost converter is modeled and Pulse Width Modulation (PWM) based SMC and PI controllers are designed and simulated using MATLAB/SIMULINK. SMC and PI controller performance areanalyzed and compared and the results are projected.

Sliding Mode – PI controller is recognized as robust controller with a high stability in a wide range of operating conditions, although it suffers from chattering problem. In addition, it cannot be directly applied to multi switches power converters. This paper concerns a sliding controller design with the proportional-integral (PI) control form. First, a theoretical analysis of the considered sliding PI controller is provided. Our analysis reveals that the proportional control term of the sliding PI controller, i.e., sliding proportional controller, can reduce the chattering problem and thus, the robustness can be established. Second, the chattering problem is eliminated by smoothing the control law in a narrow boundary layer, and a pulse width modulator produces the fixed frequency switching law for the inverter. The smoothing procedure is based on limitation of pulse width modulator. Therefore, the chattering problem of the proportional gain is resolved and the valuable robust control property of the sliding integral controller is illustrated again. The simulation model has been developed and tested using MATLAB software.

This paper presents the closed-loop control of high brightness LED lamps using microcontroller. Three types of controllers, proportional-integral (PI) controller, look-up table fuzzy logic controller and real-time calculation fuzzy logic controller are implemented for performance comparison. A photosensitive resistor senses the LED brightness and an 8-bit microcontroller converts brightness signal to numerical value and performs control algorithm. The algorithm is programmed in C language. Selected inputs for fuzzy control algorithm are the brightness error and the change of brightness error. Pulse width modulation (PWM) correction is the only output of the controller and PWM current source is used to drive the LED lamp. Experimental results show that the PI controller needs the least memory and run time, and the real-time calculation fuzzy logic controller requires the most memory and run time, among the designed controllers.

The efficiency of control systems in permanent magnet synchronous motors (PMSM) is crucial, especially for applications in physiotherapy robots. Previous studies have demonstrated that an open-loop field-oriented control (FOC) driver using BTS7960 outperforms the commonly used electronic speed controller (ESC). This research addresses the challenge of further improving efficiency by employing a closed-loop FOC driver with the BTS7960. The research methodology involves two main stages. First, a PSIM software simulation of a closed-loop FOC using a proportional integral (PI) controller is conducted. The aim is to determine the P and I parameters that result in the smallest settling time, steady-state error, and overshoot in controlling the PMSM motor's rotation per minute (RPM). The second stage involves hardware implementation with the BTS7960, where the PMSM motor RPM is compared under various loads ranging from 10-gram to 60 gram. RPM results from both open-loop and closed-loop configurations are compared. The results show that the closed-loop FOC driver has improved system transient response compared to the previous open-loop FOC driver, notably reducing the settling time from 2.24 seconds to 1.45 seconds for a 60 gram load. Therefore, this research concludes that a closed-loop configuration with well-tuned PI parameters can deliver better performance compared to open-loop methods, as clearly demonstrated.

The primary function of microgrid (MG) is to share the power accurately among different distributed generation (DG) units according to the load demands. The droop control methods are normally used for appropriate power sharing. However, these control techniques suffer badly due to the feeder impedances and uncontrollable power coupling issues. Many techniques have been proposed to share power accurately, most of them rely on communication link. In this work a localized/communication free signal generating mechanism is proposed. The mechanism injects the transient reactive power in frequency droop characteristics by observing the changes in microgrid. This injection disturbs the actual active power sharing which is helpful for the computation of reactive power sharing errors. These errors are minimized by utilizing the proportional integral (PI) controller. The PI controller modifies the y-intercept and the slop of Q-E (Reactive Power –Voltage) droop characteristic for the correction of reactive power sharing error. Moreover, the parameters of droop and PI controller of inner control loop are optimized by Particle Swarm Optimization (PSO) to obtain high precision and reliability. The proposed technique has the following salient features:1. Accurately shares the reactive power without the information of feeder line impedances2. This accurate reactive power sharing scheme has been started locally without the need of communication signal from the central controller. Thus, there is no delay in monitoring the notable changes in microgrid caused by DGs. 3. The careful selection of PI & droop controller parameters through PSO makes the system more stable as compared to the conventional methods in terms of transients and steady state responses.