S. M. Bashi

Design of a Prototype D-Statcom using DSP Controller for Voltage Sag Mitigation

This paper presents the design of a prototype distribution static compensator (D-STATCOM) for load compensation in an unbalanced distribution system. The D-STATCOM is intended to replace the widely used static var compensator (SVC). The compensation scheme of the D-STATCOM is derived using the symmetrical component method. In this work, the 12-pulse D-STATCOM configuration with IGBT has been designed and the graphic based models of the D-STATCOM have been developed using the PSCAD/EMTDC electromagnetic transient simulation program. Accordingly, simulation is first carried out to illustrate the use of D-STATCOM in mitigating voltage sag in a distribution system. The D-STATCOM has been developed using DSP controller to achieve excellent overall performance. Simulation results prove that the D-STATCOM is capable of mitigating voltage sag by controlling PWM of the system using DSP board

Cathodic protection system

Cathodic protection system (CPS) is used to reduce corrosion by minimizing the difference in potential between anode and cathode. This can be achieved by applying a current to the structure to be protected from electrical source. When enough current is applied, the whole structure will be at one potential, thus anode and cathode sites will not exists. CPS is commonly used on many types of structures such as pipelines, underground storage tanks, locks and ship hulls. The main objective of this work is to discuss and compares the two methods of applying cathodic protections by using an impressed current system and sacrificial anode. The physical models were also developed for the two methods. The importance of controlling the protective current in the system is presented and discussed. Calculated and measurement results for the two methods have been presented in this paper. Measurement of output current were taken each week showed that there is a decrease in the required current according to time due to reduced of anode surface during the life of the system.

Quantitative Feedback Theory control design using particle swarm optimization method

In this paper, a particle swarm optimization (PSO) method is proposed to design Quantitative Feedback Theory (QFT) control. This method minimizes a proposed cost function subject to appropriate robust stability and performance QFT constraints. The PSO algorithm is simple and easy to implement, and can be used to automate the loop shaping procedures of the standard QFT. The proposed method is applied to the high uncertainty pneumatic servo actuator system as an example to illustrate the design procedure of the proposed algorithm. The proposed method is compared with the standard QFT control. The results show that the superiority of the proposed method in that it can achieve the same robustness requirements of standard QFT control with simple structure and low order controller.

The three phase rectifier with harmonic injection current

This paper demonstrates new circuit and concepts for three phase rectifier using harmonic current injection method. The proposed circuit is using active harmonic current injection method with a capacitor bank which is simple and low cost compared to conventional circuit that using a harmonic current injection method with star-delta transformer. This proposed circuit will reduce the total harmonic distortion which is drawn from input current supply. This will produce the waveform for the input current near to sinusoidal wave. A prototype of the proposed circuit had been developed. The comparison of simulation result and measurement result of the prototype shows good agreement between them. In addition, the THD versus output power of the proposed circuit also had been evaluated and compared with other the conventional circuit that using a harmonic current injection method with star-delta transformer. Finally, this paper will give an overview about a new harmonic current injection method that produce a very low THD of input current.

Speed drive of single-phase induction motor

In this work, the performance of a closed-loop adjustable speed drive for single-phase induction motor using voltage amplitude control. A microcontroller M68HC11E-9 has been used to implement such techniques. The microcontroller senses the speeds feedback signal and consequently provides the pulse width variation signal that sets the gate voltage of the chopper, which in turn provides the required voltage for the desired speed. A buck type chopper has been used to control the input voltage of a fully controlled single phase isolated gate bipolar transistor (IGBT) bridge inverter. PWM technique has been employed In this inverter to supply the motor with ac voltage. The simulation and laboratory results proved that the drive system can be used for the speed control of a single-phase induction motor with wide speed range.

PSO-based robust H∞ controller design using cascade compensation network

This paper proposes a method for robust controller design using cascade compensation network. The method uses particle swarm optimization (PSO) to tune the controller and performance weighting function parameters by minimizing a cost function subject to H∞-norm specifications. Levys curve fitting method is used to accurately express the multiplicative uncertainty function. The proposed method is applied to pneumatic servo actuator with system uncertainty and wide range of load variations as an example to illustrate the design procedure of the proposed controller. It is shown that the proposed controller presents robustness over a wide range of parameters change. A comparison with conventional H∞ controller is presented.

Production of hydrogen using photovoltaic electrolysis

Fossil fuels had been used for centuries and the usage of those fuels had made their supplies limited. Solar energy is one of the most promising solutions, which offer an actual clean, environmental friendly, renewable and alternative energy option. The main objective of this project is to store the energy from the sun in another form of energy. Hydrogen storage is chosen for its potential to make a clean energy option and low cost in construction. The development for hydrogen-fuel economy which had rapid increase in industrial application had also influent the decision of this project. In this work, the solar energy applications in Malaysia have been investigated and converted to an electric energy by using the photovoltaic cells. Electrolysis, which is the simplest process to generate hydrogen, is powered by the DC voltage from the photovoltaic cell instead of using the battery as power supply.

Simulation and analysis of power converter harmonics

The applications of large power electronic converter results in generation of low (LF) and high (HF) frequencies harmonics in the power system. The adverse effects of harmonics are widespread. In this paper, harmonic analysis was carried out on 3-phase fully controlled thyristor bridge. Methods of harmonic reduction have been used. It has been found that, the 12-pulse method is suitable in reduction of lower order harmonic and a high pass filter can be used to reduce the higher order harmonics. Operating the bridges at lower value of a triggered angle and using a star-delta connection of the power transformer leads to reduction of the generated harmonics. PSPICE software has been used for simulation and a good agreement between the simulated and experiment results has been obtained.

Three-phase diode rectifier with a low input current distortion and regulated output voltage

This paper describes the operation of an AC-DC converter employing sixth-order harmonic injected PWM. The boost converter operating on the rectified output uses a constant switching frequency PWM and discontinuous current mode to reduce the total harmonic distortion in the input current. The implementation and the characteristics of the converter are presented.