Hamdy A. Ashour

Digital hysteresis current control for grid-connected converters with LCL filter

Current controlled inverter using hysteresis controller is popular due to the simplicity of the algorithm implementation with a robust dynamic response. However, the controller action requires the use of analogue circuitry to maintain its characteristics which lacks the interfacing, maintenance, flexibility, and integration of a digital system. In this paper, a digital hysteresis controller based on sampling the feedback signal and applying control action at a fixed interval is investigated. The controller is applied on three proposed configurations for a single phase grid connected inverter with a designed LCL filter and a primary control loop on the filter inductor current. Parameters affecting the hysteresis controller primary characteristics are investigated and a selection criteria of filter parameters is derived. To eliminate performance issues arising from parameters mismatching and variable switching frequency, adaptive hysteresis band calculation and a secondary control loop is proposed. By means of simulation and experimental implementation, the performance of the configurations is evaluated.

Comparison Analysis of AC Voltage Controllers Based on Experimental and Simulated Application Studies

This paper introduces a detailed comparison between possible connections of AC voltage controllers. For each configuration, the experimental setup is implemented and the corresponding simulation program is presented using Simulink under Matlab. The simulated and experimental instantaneous voltage and current waveforms in case of resistive and inductive loads are matched well, validating the simulation comparison for analysis. The comparison analysis includes the required number of devices and isolated gate signals, which determines the complexity and the size, hence the overall cost. Also harmonic spectrum, total harmonic distortion, effective rms value, dc offset and the control range are compared to specify the performance. The implementation of a fixed-capacitor thyristor controlled reactor (FC-TCR) and three phase induction motor starters (SOFT STARTER) as two application case studies of AC voltage regulators has been discussed. Experimental and simulation results have been obtained and well correlated, showing the effectiveness of such configurations in the fields of control of reactive power flow and in the field of controlling the starting performance of three phase induction motor

Implementation and Analysis of Microcontroller Based Soft Starters for Three Phase Induction Motors

This paper introduces two different microcontroller based three phase induction motor starters, the first using electromechanical star-delta with reactor starting and the second utilizes electronic AC voltage controllers starting technique. For each of the proposed methods, the experimental setup is implemented and the output voltage, current and speed waveforms were demonstrated and analyzed for different selection options and operating conditions. A dynamic model of three phase induction motor has been developed to validate a model of six terminals connection motor for star and delta performance analysis. The model has been utilized for the simulation analysis and comparison of various electromechanical and electronic induction motor starters techniques. Comparison between commercial analog controller based soft starter LH4-N2 and the proposed starter has been introduced as well. Experimental and simulation waveforms obtained are matched validating the proposed starters for practical applications.

Maximum power point tracking for irregular irradiance of a photovoltaic array

This paper investigates different photovoltaic array configurations and there effect on the PV array efficiency, while applying the maximum power point tracking (MPPT) for better utilization of the overall system. There are several MPPT and several arrangements of the PV modules inside the array. Among several studied MPPT algorithms for PV panels, the Perturb and Observe (P&O) method is utilized as the simplest and the easiest to be practically implemented. The PV module has been modeled and the MPPT algorithm has been validated by simulation analysis and experimental implementation using microcontroller and power electronics converter. Different arrangements of the PV array were discussed, and a comparison study between the central inverter configuration and the multi-string configuration is conducted. Results obtained showed that the MPPT within multi-string configuration improves the overall utilization of the PV array more than the central inverter configuration.

Online fault detection of transmission line using artificial neural network

As the voltage and current waveforms are deformed due to transient during faults, their pattern changes according to the type of fault. The artificial neural network (ANN) can then be used for fault detection due to its distinguished behavior in pattern recognition. In order to minimize the structure and timing of the ANN, preprocessing of the voltage and current waveforms was done. The data delivered from a simulated power system using PSCAD (EMTP with cad system) was used for training and testing the ANN. An experimental setup, consists of a 3 phase power supply module and transmission line module, is utilized. A set of signal conditioning circuits is designed and implemented in order to transfer data to a PC which is used as an online relay for fault detection. This is done via a data acquisition card (CIO-DAS1602/12). The Matlab program captures and processes real data for training the ANN. Applying different types of faults for testing the system, right tripping action was taken and the type of fault was correctly identified. The suggested artificial neural network algorithm has been found simple and effective hence could be implemented in practical application.

Automatic transfer switch (ATS) using programmable logic controller (PLC)

In the industrial engineering education curriculum, advanced manufacturing technology is so important to provide the students with effective industrial instructions and enrich their practical skills through the continuous development of laboratory industrial resources. Hence, the author has developed an automatic transfer switch (ATS) based on a programmable logic controller (PLC) in the laboratory of the Arab Academy for Science & Technology (AAST) as an industrial case study for the students through the course of industrial automated systems. General concepts and practical considerations of the ATS have been discussed. Steps of designing and implementing the proposed setup, including system requirements, sensors, actuators, hardware configuration, software programming and experimental tests, are demonstrated. The proposed setup has been found so effective not only in increasing students industrial knowledge and skills but also can be used as a stand-alone system in commercial and industrial practical fields.

Sliding mode speed control of a shifted fully pitched switched reluctance machine

An experimental speed control drive system for the shifted WIN pitched switched reluctance machine, using the C167 embedded controller, is presented. Methods of speed control and acceleration estimation are discussed. System performance is tested for speed step change, speed reversal, speed tracking and load disturbance responses using proportional plus integral (PI) control and sliding mode (SLM) control. A comparison between proportional plus integral and sliding mode speed control, using Slotines approach, is experimentally carried out and the robustness of sliding mode control is shown.

A new electronic step-up/down voltage stabilizer topology based on H-Bridge AC chopper

The rapid development and high controllability advantages of power electronic devices lead to their application in voltage stabilizers and tap-changers as competitive options with commercially available mechanical counterparts. This paper introduces a new electronic voltage stabilizer topology utilizes four AC switches in a form that may be named as AC H-bridge connection, and based on pulse width modulation (PWM) AC chopper combined with a single low power compensating transformer. Such topology eliminates the need of the main input multi-tapping transformer, hence reducing the overall size, weight and cost. Depending on the selected switches and value of the chopping duty cycle, the proposed configuration is capable of stepping up or down the input voltage, hence keeping the output voltage constant with continuous flow of input current and better harmonics restraining in the output load voltage. Mathematical equations describing the function of the proposed topology have been demonstrated and simulation analysis has been presented. Practical verification to confirm the capability of the setup has been illustrated through several experimental results and analysis.

Realization of adaptable PID controller within an industrial automated system

This paper describes and implements an a real control technique using advanced automation technology. PID controller is one of the most controller used in industrial but it need to be adaptable in real situation in order to overcome the parameter variation and system disturbance. An adaptable PID controller based on analogical gate technique is implemented using an industrial Programmable Logic Controller (PLC) to control the temperature of a process by actuating of a three way valve. The valve distributes the hot and cooled air in order to adjust the temperature of a vessel. The system control hardware consists of first; PLC as a field controller with high sampling rates, second; Human Machine Interface (HMI) as a local operating and adjusting station, finally; SCADA software to adjust and supervise the overall system. The process parameter estimation, simulation results and practical results are obtained and compared for system validation. A comparison between conventional and the proposed adaptable one performance is introduced, showing merits and effectiveness of proposed algorithm.

Reduced voltage combined AC motor and drive system for safe electric vehicle

This paper presents the design, analysis and implementation of a proposed combined three phase induction motor and its drive system to meet the demand of low-voltage electrical system for hybrid and electric cars, avoiding the high voltage human risks, expensive and complex requirements of the higher voltage insulation and power electronic devices. The development of electric vehicle technologies has been reviewed. A conventional 220V 3-ph induction motor has been rewound in order to get the required 48V 3-ph motor. A comparison between the old motor and the rewound motor has been theoretically and practically carried out including different characteristics. Design and simulation analysis of different control cards have been carried out using PSpice software while the overall drive system performance has been simulated using Simulink under Matlab package. The proposed setup has been practically implemented using commercial available components. Different practical waveforms have been obtained for different operation modes, showing the effectiveness of the proposed setup as a reduced voltage speed control drive system suitable for safe electric vehicle applications.