Root Locus-Based Magnetic Levitation System Stabilization: An Undergraduate Control System Design Approach

The subject of control system design has evolved considerably over the years. Although several design techniques and strategies have been adopted to realize control systems that meet a predetermined set of performance criteria, the fundamental problem remains that of developing controllers to adjust the performance characteristics of a dynamic system in order to obtain a desired output behavior. The dynamic behavior of a magnetic levitation system (MLS) of a ferromagnetic ball is compensated in this paper. Consolidating the exposure of undergraduate students to the rudiments of control system design, the paper employs the classical root locus technique to stabilize the system. A combination of analytical and software-based methods is used to design proportional-derivative and phase-lead compensators based on the linearized model of the system. Complete details of the design approach, from modeling and analysis of the plant to computing the values of the controller parameters, are shown. MATLAB scripts for plotting root loci and simulating the system are provided

Auxiliary Winding Switching Circuit for Single-Phase Induction Motors

The most common practice for starting a single-phase induction motor is to connect a starting capacitor, in series, with the auxiliary winding. Here, the possibility of using an electronic switch in parallel with the starting capacitor, is discussed. This work relates particularly to a switching device for electrically connecting and removing the auxiliary winding and starting capacitor from the single-phase induction motor's circuitry. The starting capacitor with the auxiliary winding are disconnected by electronic means as the motor gains speed hence leaving only the main winding in the motor circuit for normal operation

Automatic Electrical Appliances Control Panel Based on Infrared and Wi-Fi: A Framework for Electrical Energy Conservation

-Today, proprietary home automation targets very specific applications which operate mostly on a cable based infrastructure. In contrast to that, our implementation builds on a wireless platform for the automatic control of house hold electrical appliances. The nodes gather sensor readings in a home and transmit them to a central automation server. There, the readings are matched against a list of script statements. When there is a match, a specific action is performed. An important property of the system is that the control of all home appliances is done by means of the ubiquitous Infrared and Wi-Fi wireless technologies. This way, the co-operation between manufacturers is not a necessity in order to connect devices to the home automation network

DEVELOPMENT OF NONLINEAR CONTROL SCHEMES FOR ELECTRIC POWER SYSTEM STABILIZATION

Power system stabilizers and other controllers are employed to damp oscillations in power systems, thereby guaranteeing satisfactory dynamic performance following major network disturbances. However, the parameters of these controllers are often tuned based on the power system linearized model which generally is a function of the system operating point or state. These controllers suffer from poor performance when the system state changes. The aim of the research work reported in this Thesis is to develop nonlinear synchronous generator excitation control schemes with control laws for providing improved transient stability when the system is subjected to wide parameter variations due to network disturbances. The study employed fourth-and third-order models of a single-machine-connected-to-an-infinite-bus system to design two nonlinear sliding mode control laws (CLs) and one finite-time homogeneous control law (CL), which were constructed based on a well-chosen output function of the system. The parameters of the control laws were properly selected and/or tuned to give desirable dynamic characteristics using well established linear control methods. Justifications for the selection of the fourth-and third-order synchronous generator models to design the aforesaid controllers are presented. Dynamic simulations of the system under the action of the control laws were carried out using MATLAB®/SIMULINK. In order to test the performance of the laws, several simulation studies were performed when the voltage magnitude (V) of the infinite bus and the transmission line reactance (XE) of the system changed due to an applied three-phase symmetrical fault at the infinite bus and generator terminals. Results obtained from these studies show that the dynamic characteristics of the system being investigated have improved significantly, in terms of the rotor angle and rotor speed first peak, damping of low-frequency mechanical oscillations in rotor angle following fault clearance, and settling times of key stability indicators (rotor angle and rotor speed). For instance, for application of each of 5-cycle, 7-cycle, and 9-cycle fault at the infinite bus, the system rotor angle settled to its stable steady values within 1 - 2.2s with minimal control effort that varied between -5pu and 5pu before settling at the prefault value of 1.5603pu in 4.32s (CL1), in 1.92s (CL2), and in 3.32s (CL3). Whereas, CL3, which is a contribution to the improvement of the existing general higher-order sliding mode control structure for synchronous excitation control, was able to make the system withstand greater fault duration than CL1, CL2, which has a new positive parameter (called the dilation gain) incorporated into it, furnished the system with the greatest fault-retaining capability. In practice, the implementation of the three control laws can be carried out in a static exciter configuration with a very fast response

The Case for Aluminium Cable Usage in 1-kV Networks in Nigeria with Emphasis on Public Awareness

This paper presents the needed analysis for the use of Aluminium conductors as an alternative to the use of copper in 1-kV armoured and non-armoured cable network applications in Nigeria. The study revealed that over the years, copper cables have dominated the Nigeria cable market, except for bare Aluminium conductors (AOHL) and service cables (NAY and NAYY). The use of Aluminium as a conductor material has reached a great development due to its mechanical and electrical characteristics, in addition to the economic advantage over other metals used as conductors. The specification of its properties is expressed in the same units employed for other materials in order to appreciate its application as compared to other conductors. This paper carried out a rigorous comparison analysis on the price, weight and conductor’s minimum cross section to sustain the permissible current carrying capacity, allowable voltage drop and short circuit current for 4-cores armoured mains cables

An Electronic Protection Unit for Diesel Engine Standby Generators

Today diesel engine-driven standby generators for backup power supply have been adopted for residential, commercial, and industrial use—especially in some developing countries where power from the utility company is highly erratic. Although many of these generators function well in operation, certain engine conditions, such as low oil pressure, high oil and water temperature, abnormally high speed, etc., could lead to malfunction, failure, or complete breakdown of the engine. Therefore, the focus of this work is to present the implementation of a simple, but effective electronic protection unit (EPU) capable of mitigating the adverse effect which may arise as a result of these conditions. It is composed of two major sub-circuits—the main protective sub-circuit and the timing sub-circuit—realized using a combination of passive and active components. Unlike the common electrical relay-based protection system, this unit has an additional advantage of being able to keep the faultindicating system of the generator working even after engine shutdown, thereby facilitating fault tracking. The unit has been tested on a diesel engine-driven generator and found to function satisfactorily. The test results are shown

On The Cost Implications of Technical Energy Losses on Nigerian 330-kV Transmission Grid System

Base on the author’s result of power line losses obtained for low, medium and high current levels as 146.73MW, 322.24MW and 738.28MW respectively, in his bid to evaluate the power line losses using symmetrical component theory of unbalanced fault, the annual energy (MWH) losses for year 2013 was calculated and validated in this study. The annual technical energy losses due to the low, medium and high power losses were respectively found to be 443.45GWH, 976.895GWH and 2231.230GWHbased on Load Factor and Load Loss Factor amounting to N8.4 billion, N18.6 billion and N42.4 billion respectively. The low power loss (steady-state) result of this work was validated by the result of load-flow obtained using the MATLAB and Power Word Simulator (PWS) while the annual MWH for the high power loss level compares favourably well with the normal practice of utility operator’s monthly energy balance thereby closing the gap between the practical information and the theoretical one

On The Cost Implications of Technical Energy Losses on Nigerian 330-kV Transmission Grid System

Base on the author’s result of power line losses obtained for low, medium and high current levels as 146.73MW, 322.24MW and 738.28MW respectively, in his bid to evaluate the power line losses using symmetrical component theory of unbalanced fault, the annual energy (MWH) losses for year 2013 was calculated and validated in this study. The annual technical energy losses due to the low, medium and high power losses were respectively found to be 443.45GWH, 976.895GWH and 2231.230GWHbased on Load Factor and Load Loss Factor amounting to N8.4 billion, N18.6 billion and N42.4 billion respectively. The low power loss (steady-state) result of this work was validated by the result of load-flow obtained using the MATLAB and Power Word Simulator (PWS) while the annual MWH for the high power loss level compares favourably well with the normal practice of utility operator’s monthly energy balance thereby closing the gap between the practical information and the theoretical one

Review of System Collapse Incidences on the 330-kV Nigerian National Grid

A modern electric power system network (PSN) is typically a large and complex engineering system whose healthy existence is crucial to industrial and socio-economic development of Nations. Voltage instability contributes to large extent to the system collapses or blackouts. It is a major concern for today’s electric power system operators. The Nigerian National grid (NNG) experiences on an average of thirty-five (35) system collapses every year over the past ten (10) years. This paper presents a review and classification of system collapses experienced on the Nigerian National Grid (NNG). It also reveals that on the average, the fault induced system collapse is about 88%. This implies that the NNG is highly venerable to voltage instability than other form of disturbances

Nomadic Base Station (NBS): a Software Defined Radio (SDR) based Architecture for Capacity Enhancement in Mobile Communications Networks

In this research work, the problem of congestion that leads to dropped calls at GSM cell sites and drastic reduction in network capacity is addressed. We designed a novel GSM base station architecture named Nomadic Base Station (NBS) which is based on Software Defined Radio (SDR) architecture and simulated the LNA for its receiver front-end. The NBS receiver LNA selects and amplifies GSM signal bursts operating at 900MHz and 1800MHz Radio Frequency Band. The later stages translate the Radio Frequency (RF) signal to Intermediate Frequency (IF) signal. This implements the SDR technology by digitizing the IF signal into bit streams that can be processed on generic Central Processing Unit (CPU) using custom written signal processing software