Performance of Control Dynamics of Wind Turbine Based on Doubly Fed Induction Generator under Different Modes of Speed Operation

There are many solar power and wind stations installed in the power system for environmental and economic reasons. In fact, wind energy is inexpensive and the safest among all sources of renewable energy, it has been recognized that variable speed wind turbine based on the doubly fed induction generator is the most effective with less cost and high power yield. Therefore, this paper has chosen doubly fed induction generator for a comprehensive study of modeling, analyzing, and control. DFIG in wind turbine has to operate below and above the synchronous speed, which requires smooth transition mode change for reliable operation, specially, close to synchronous speed where the DFIGWT instability starts to appear. Furthermore, its output electric power has to be controlled to provide stability for the power system; hence its performance depends on the generator itself and the converter operation and control system. This paper presents completed mathematical model of DFIG with its AC/DC/AC converter driven by DC machine. A new vector control technique is designed and modeled, which allows to evaluate the dynamic performance of the controller under (below, above, and through synchronous speed). The simulation results demonstrate the accuracy and high performance of the new control system of DFIG for wind turbine, which provides smooth transition mode without using any extra circuit.

Three-Year Performance Evaluation of Single Junction Amorphous Solar Cells Grid-Connected Power Station in Libya

Photovoltaic (PV) conservation of solar energy is one of the most promising sources of future energy. Grid-connected PV systems are widely used in many countries, but in Libya it is just started. A PV grid-connected of 24 KWP PV system has been installed as a pilot project to deliver AC energy to the Tripoli University electric grid; the system is of single junction amorphous solar cells which were erected in Sep. 2009; it consists of 240 Mitsubishi thin film amorphous PV Modules of MA100T2 type capable of supplying 100 Watts of DC power each, five inverters of type SMA Sunny Mini Central, and the system is equipped with a data logger to record all important parameters. In this paper the evaluation of the PV system performance was carried out according to the European guidelines of the PV system operation. The results of the measured parameters, namely, the performance ratio, AC energy yearly yield, the temperature dependent, and the system efficiency, showed that the system is performing better than the deigned parameters.

Controlling Nonlinear Behavior in Current Mode Controlled Boost Converter Based on the Monodromy Matrix

Recently it has been observed that power electronic converters working under current mode control exhibit codimensional-2 bifurcations through the interaction of their slow-scale and fast-scale dynamics. In this paper, the authors further probe this phenomenon with the use of the saltation matrix instead of the Poincaré map. Using this method, the authors are able to study and analyze more exotic bifurcation phenomena that occur in cascade current mode controlled boost converter. Finally, we propose two control strategies that guarantee the stable period-one operation. Numerical and analytical results validate our analysis.

Speech Recognition of Arabic Spoken Digits

With the widespread growth in the use of digital computers, there has been an increasing need to be able to communicate with machines in a simple manner. One of the main tasks that simplify the communication with machines is the speech recognition. Speech recognition is the translation of spoken words into text. However, speech recognition is a very complex problem. This paper is related to the recognition of spoken Arabic digits. Two recognition techniques have been implemented and tested: Pitch Detection Algorithm (PDA) and Cepstrum Correlation Algorithm (CCA). In order to analyze the recognition accuracy of the selected techniques, a database of spoken Arabic digits has been created. The performance of the two techniques has been analyzed based on the created database.

The Development of Body-Powered Prosthetic Hand Controlled by EMG Signals Using DSP Processor with Virtual Prosthesis Implementation

The state of the art in the technology of prosthetic hands is moving rapidly forward. However, there are only two types of prosthetic hands available in Libya: the Passive Hand and the Mechanical Hand. It is very important, therefore, to develop the prosthesis existing in Libya so that the use of the prosthesis is as practical as possible. Considering the case of amputation below the elbow, with two movements: opening and closing the hand, this work discusses two stages: developing the operation of the body-powered prosthetic hand by controlling it via the surface electromyography signal (sEMG) through dsPIC30f4013 processor and a servo motor and a software based on fuzzy logic concept to detect and process the EMG signal of the patient as well as using it to train the patient how to control the movements without having to fit the prosthetic arm. The proposed system has been practically implemented, tested, and gave satisfied results, especially that the used processor provides fast processing with high performance compared to other types of microcontrollers.

Interfacing PMDC Motor to Data Port of Personal Computer

Procedures and techniques of hardware interfacing to personal computer system through parallel data port to control permanent magnet DC (PMDC) motor and create LabVIEW integrated-development-environments (IDEs) based Virtual Instrument (VI) software are discussed. To test the designed VI software diagram, authors constructed interface hardware without taking support of any commercially available DAQ boards. Hardware resource utilization and performance optimization by creating VI are discussed. Testing the design (Hardware and VI) by varying the set point speed of the motor is concluded. It is observed that the motor speed gradually approaches and locks to the desired or set speed.

Microcontroller Based Less Switches Topology and Digital Gating Technique for Single-Phase Five-Level Inverter

The multilevel inverter is the idea of connecting such distributed DC energy sources (solar and fuel cells in addition to rectified output of wind turbines) to a power grid. Multilevel pulse width modulation (PWM) inverters have gained importance in high performance power applications without requiring high ratings on individual devices. The elementary concept of a multilevel converter to achieve higher power is to use a series of power semiconductor switches with several lower voltage DC sources to perform the power conversion by synthesizing a staircase voltage waveform. In the present paper we introduce a power circuit for single-phase five-level inverter which contains a very lower number of switches and the technique for the generation of required signals to control the operation of the inverter switches. The presented technique is implemented via microcontroller ATmega16. The simulation and practical results are presented.

Prevention of Cascaded Events of Distance Relay Zone Three Using Logic Controls

This paper presents a new method to prevent cascaded events caused by zone 3 elements of distance relays due to transmission line overload by using logic controls. A proposed adaptive distance relay algorithm provides a new concept to distinguish between actual faults and flow transfers and secures time to perform remedial controls by a defense system during cascaded events. Maloperation of distance relay is a very critical situation, leading to more operation of other distance relays and finally partial or total blackout. Logic controls are used to insure the operating decision through observing the system parameters and compare it with a setting already being input to the system. When distance relay is activated and the logic controls find that the system is healthy (unfaulted) and that the activation resulted from transmission line overload not real fault, the operation signal will be blocked to protect the system from maloperation.

Performance Assessment of Fuzzy Logic Power System Stabilizer on North Benghazi Power Plant

Fuzzy logic design has been implemented online to tune the power system stabilizer gain (KPSS). To assess the performance of the proposed technique, Benghazi North Power Plant (BNPP), at eastern Libyan network, has been utilized as a power system stabilizer (PSS) benchmark. The design considers different operating conditions and large disturbance. A selection of fuzzy rules is derived by means of system output power to tune KPSS, whereas Particle Swarm Optimization technique (PSO) is exploited to calculate the PSS parameters offline according to real-time measurements of the considered plant. Several simulation scenarios have been conducted to show the effectiveness of the proposed PSS in damping of local and interarea modes of oscillation of one-machine infinite-bus system. The study also contains comparison between the proposed technique and conventional PSS (CPSS).