Journal of Electrical & Electronic Systems

Power system stabilizers (PSS) have been widely used to enhance damping due to the electromechanical low frequency oscillations occurrence in power systems. In this paper, a new method is used for the online tuning of parameters of conventional power system stabilizers (CPSS) using fuzzy logic. Fuzzy logic enables mathematical modeling and computation of some nonlinear parameters of the system, which are usually, derived empirically by utilization of expert knowledge rules. Various literatures has shown that fuzzy logic controller is one of the most useful methods for expert knowledge utilization. This type of controller is adaptive in nature and can be used successfully as a power system stabilizer. The design of fuzzy logic controllers is mainly based on fuzzy rules and input/output membership functions. Simple and efficient clustering algorithms allow data classification in distinct groups using distance and/or similarity functions. In the present paper, the optimum generation of fuzzy rules base using Fuzzy C-means (FCM) clustering technique is used. In fact, data are classified and the number of fuzzy rules which depends on convergence radius is determined. Finally, the performance of proposed FCM controller is compared with that of conventional controller. The active power, reactive power and bus voltages used as inputs to the fuzzy logic network based power system stabilizer and the parameters of the optimum stabilizer , i.e. gain factor as well as time constants of the lead/lag compensator, are
the outputs of the proposed system. The design method has been successfully implemented on a single machine power system connected to an infinite bus over various operating conditions.

The sequential circuit designed was Look-Ahead Transformation based LFSR in which a hardware complexity was present and it may limit their employ in many applications. The design of efficient LFSR for BCH encoder using TePLAT (Term Preserving Look-Ahead Transformation) overcame this limitation by opening the employ of minimizing the iteration bound and hardware complexity in wide range of applications. A TePLAT convert LFSR formulation behaves in the same way to achieve much higher throughput than those of a native implementation and a Look-Ahead Transformation-based.

In a VLSI circuit, interconnection plays the dominant role in every part of the circuit nearly 70 percent of the area depends on interconnection, 20 percent of area depends on insulation, and remaining 10 percent to devices. The binary logic is limited due to interconnect which occupies large area on a VLSI chip. In this work, the designs of quaternaryvalued logic circuits have been explored over multi-valued logic due to the following reasoning. An approach to mitigate the impact of interconnections is to use multiple-valued logic (MVL), hence, more information can be carried in each wire, reducing the routing network. Therefore, a single wire carrying a signal with N logic levels can replace log N having base 2 wires carrying binary signals. Reducing the routing leads to a direct reduction of the line capacitance and the overall circuit area. Therefore, this results in increasing the maximum operation frequency and also reducing the power consumption. The most important characteristics of this method is a voltage-mode structure. Voltage mode structure has the advantages like reduced power consumption implemented in a standard CMOS technology. Our new method overcomes conventional techniques with simple and efficient CMOS structures.

The Nigeria 330 KV integrated power network consisting of seventeen (17) generating stations, sixty four (64) transmission lines and fifty two (52) buses is studied, to investigate the time limits of stability before, during and after occurrence of a three phase (3-θ) fault on the largest generating station (Egbin) and to determine also the most affected generating stations and buses in the network.Theswing and torque equations expressed in time domain was used for the study and the network was modeled in ETAP transient analyzer environment. Transient stability time limit of the system was set to operate at maximum value of ten (10) seconds. Before the fault (between 0.000secs-0.0006secs), the system dynamics was not affected and the peak values of terminal current, rotor angle, frequency,mechanical and electrical power obtained were observed to be within stability region. However, as the fault occurred between 0.0006 secs-0.042 secs, the system dynamics changes, thus affecting the quadrature axis. This change in quadrature axis affected the individual generator’s exciter current, exciter voltage, electrical power, mechanical power, frequency, rotor angle and terminal current, though still remain within stability boundary. However, when the fault is cleared within this time, the system returns to its stability region. When the fault lasted beyond 0.042 secs, there is loss of system synchronism. Generating stations that were majorly affected are Omotosho, Sapele, AES and Delta stations. It was observed that the bus voltages connected to these stations deviated from the statutory limit of 313.45 KV-346.5 KV. Their bus voltage values were: Omotosho (361.42KV), Sapele (358.42 KV), AES (350.43 KV) and Delta (364.32 KV). The other buses connected to the other generating stations were however not affected. The province’s population is expected to grow by about 28 percent – or about 3.7 million people – by 2030 and become increasingly urbanized. The structure of the economy will also change as the high-tech and service sectors grow and demand from large industries is expected to grow moderately.

This paper deals with the modeling and control of a wind energy system based on a doubly-fed induction generator. Initially, an MPPT control strategy of the doubly-fed induction generator is presented. Thereafter, the control vectororiented stator flux is performed. Finally, the simulation results of the wind system using a doubly-fed of 3 MW are presented in the Matlab / Simulink environment.

This paper presents the implementation of a different SPACE VECTOR PWM techniques applied to the indirect vector controlled induction motor (IM) drive involves decoupling of the stator current into torque and flux producing components of an induction motor. The drive control generally involves a fixed gain proportional-integral controller. Space vector pulse width modulation technique is widely used in inverter and rectifier controls. Compared to the sinusoidal PWM (SPWM), SVPWM is more suitable for digital implementation and can increase the obtainable maximum output voltage with maximum line voltage approaching 70.7% of the DC link voltage (compared to SPWM’s 61.2%) in the linear modulation range. This paper presents the indirect vector controlled induction motor drive using different Space Vector PWM techniques are implemented in MATLAB-SIMULINK. The corresponding harmonic spectrum is calculated for various PWM techniques and the results are compared.

In this work, the reflected, transmitted, and loss powers due to the interaction of electromagnetic waves with graphene-dielectric structures are analyzed theoretically and numerically. The properties of the graphene material are given in detail and the required equations for its main parameters are defined. The formulations for the transverse electric waves case are provided. A recursive method is used to calculate the overall reflection and transmission coefficients of the structure. The reflected, transmitted, and loss powers are determined using these coefficients. In the numerical results, the mentioned powers are computed as a function of wavelength, angle of incidence, and dielectric thickness when graphene thickness changes.

The RFID technology has been developing fast and implemented likewise over all across the developed countries and developing countries like INDIA as well. Here we are proposing a simple, cost-effective and which can be practically implemented scheme of using the power ports available in Indian trains for some timed intervals of time so that “each and every” passenger in Indian railway bogie (in reservation section only) gets to use the power ports. The power ports available are used for mobile and laptop charging. This system uses rfid cards to detect the particular passenger and allows him to use the power for some specific intervals of time. In this way every passenger is only allowed a certain specific duration to use the power port and hence no passenger can monopolise over the power port.

The Nigeria 330 KV integrated power system currently consist of the existing network, National Independent Power Projects (NIPP), and the Independent Power Producers (IPP). This network consist of Seventeen generating stations, Sixty four Transmission lines and Fifty two buses. Loss reduction and bus Voltage improvement control mechanism is still based on conventional devices (synchronous generators/condensers, tap changers, reactors and inductors) and building more generating stations and transmission lines as an alternative to meet the ever increasing power demand. This work modeled and analyzed the application of Interline Power Flow Controller (IPFC),which is a modern control Flexible Alternating Current Transmission System (FACTS)device on the network using Genetic Algorithm (GA) for its optimal placement and an option for power improvement. The result obtained showed improvement of weak bus voltages and loss reduction with and without IPFC devices on incorporation in the network. It is recommended that FACTS devices be incorporated into the power network for improved efficiency and not necessarily building more stations and transmission lines, as this is the current practice in Nigeria. This should be an integral part of the planning process for both the existing, NIPP and IPP in the country so as to meet the vision 2020 goal.