Synchronous Generator Excitation Chatter-Free Sliding Mode Controller

A chatter-free sliding mode controller (SMC) for synchronous generator excitation is presented in this paper. A linearized model of a single machine connected to an infinite bus is employed to design a variable-structure controller which not only stabilizes the system, but also ensures that this is maintained in the face of system parameter variations. Validating the robustness feature of an SMC, simulation results that show the dynamic performance of the system under both constant excitation and SMC-controlled excitation are presented

Development of a software solution for solar-PV power systems sizing and monitoring

Power systems sizing and monitoring are very important design components in determining the overall performance of solar-photovoltaic (PV) systems. These design components represent the pre-installation and post-installation stages of solar-PV systems planning respectively, and paying adequate attention to them can go a long way to increasing the working life of solar-PV system installations. The SolarHelper developed in this work is a small software solution package that monitors and records vital system variables that will give the state and performance of an existing solar-PV installation at any given time; and it is able to accurately provide a simulated output of the required battery storage capacity, and PV array size based on load demands

Analysis and Simulation of a Single Generator-Infinite Bus Power System under Linear Quadratic Regulator Control

The thrust of this article is to develop elaborate educational material on linear quadratic regulator (LQR)-based power system control for electrical engineering students, especially senior undergraduate and fresh graduate students. The paper considers a comprehensive description of a power system, which is represented by a network of a single generator connected to an infinite bus, highlighting modeling, analysis, and simulation of the system. Graphical outputs for various combinations of system state and input weighting matrices are presente

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

Contingency Analysis for Assessing Line Losses in Nigeria 330-kV Power lines

Line losses ill transmission lilies constitute one of the llllljor problt!llls affecting power generation and distribution systems. Losses luwe beelt foulld to affect the overall ejJidency of a system. Therefore, to illcretUe the efficiency of any system, losses must be minimized, This paper carried out a comprehensive study alld analym of line losses associated with Nigeritz 330-kV power transmission lines. The work includes the power-flow analysis carrid out on the existilfg Mtwork using both the Newton-Rapltson (N-R)wrltten in code-btlsed MATLAB a1ld the model-based N-R ill Power World Simulator (PWS) environment. The power-flow analysis HillS further subjected to contingency analysis and silllukdion using the N-R in PWS. Two 101111-flows were performed to reveal voltage violated buses.The resulb showed that the bus voltages outsith the statutory limit of 0.95- 1.05p.u(i.e 313.5 - 346.5kV) occurred at buses2-Bimi1JKebbi (0.9183pu), bus 9 Akangba (0.937pu), bus 18-0nitslul (0.935pu), bus 20-New-Htn~e~~ (0.920pu), bus 25- Kaduna (0.9233pu), bus 26-Kano (0.776pu), bus 22-Jos (0.8192pu) and bus 28-Gombe (0. 7247pu) under normal uncompensated conditio11. CfiiHICitive shunt compensation was applkd on these buses and the results recorded appreciable loss rethlction (about 111.35%). The result of the 11ingk line contiiJgency analyllis for uncompeMated and compen~~ated indicates a total of 335 alld 25 voltage bus violl.ltions respectivel

A microcontroller-based Active Solar Water Heating System for Domestic Applications

A potential solution to adequate and sustainable electricity supply problems in most developing countries is dependent on proper harnessing of solar (radiant) energy. Owing to tbe over dependence on fossil-fuel based energy, tbere is an exponential rise in carbon dioxide (C02) emissions into tbe atmosphere, thereby causing severe environmental degradation and ozone layer depletion. This paper seeks to apply tbe readily available radiant energy source to solar water heating, and establish possible economic benefits to its use in domestic applications for residents of Covenant University campus. The microcontroller-based active solar water heating system (ASWHS) is designed to effectively absorb radiant energy using solar collectors, and store it as hot water in a water tank via a direct current (DC) circulation pump powered by a stand-alone photovoltaic (PV) system. The design also incorporates an auxiliary electric heater which is put to use ou!y when tbere is insufficient radiant energy. A case study is reported to show tbe importance of tbe ASWHS for domestic water heating. The maximum design efficiency and tbe expected energy output of tbe solar collector throughout its working life is 79.94% and 498,225kWh respectively. A reduced dependence on grid supply and/or fossil-fuel based generator sets during hot water demand periods is recorded using tbe ASWHS witb a high payback period of 15 years; and a lower unit cost (US$0.01/kWh) oftbe ASWHS makes it more economically viable as compared to tbe unit cost (US$0.18/kWh) oftbe grid supply fortbe same amount of energy consume

Connecting Wind Turbine Generator to Distribution Power Grid—A Preload Flow Calculation Stage

A distribution grid is generally characterized by a high R/X (resistance/reactance) ratio and it is radial in nature. By design, a distribution grid system is not an active network, and it is normally designed in such a way that power flows from transmission system via distribution system to consumers. But in a situation when wind turbines are connected to the distribution grid, the power source will change from one source to two sources, in this case, network is said to be active. This may probably have an impact on the distribution grid to whenever the wind turbine is connected. The best way to know the impact of wind turbine on the distribution grid in question is by carrying out load flow analysis on that system with and without the connection of wind turbines. Two major fundamental calculations: the steady-state voltage variation at the PCC (point of common coupling) and the calculation of short-circuit power of the grid system at the POC (point of connection) are necessary before carrying out the load flow study on the distribution grid. This paper, therefore, considers these pre-load flow calculations that are necessary before carrying out load flow study on the test distribution grid. These calculations are carried out on a test distribution system

Development of a Prototype Robot Manipulator for Industrial Pick-and-Place Operations

In the industry today, continuous attempts to realize optimal efficiency and increased productivity have spawned much progress in the use of intelligent automated devices and machines to perform various operations and tasks. The thrust of this work is to present the development of a three-degree-of-freedom revolute robot manipulator amenable to pick-and-place operations in the industry. Appropriate kinematic equations of the manipulator are obtained, and then used to develop algorithms for locating predetermined positions of a small object in a customized workspace. An Arduino-based controller circuit is built to implement the algorithms, and servomotors are used to carry out independent joint control of the manipulator. The positions of the object are identified with the aid of light-dependent resistors (LDR). Besides, in order to aid easy fabrication of links and overall system assembly, a 3D model of the manipulator is designed. The results of the work, showing effective and satisfactory operation of the manipulator, are presented

(R1523) Abundant Natural Resources, Ethnic Diversity and Inclusive Growth in Sub-Saharan Africa: A Mathematical Approach

The sub-Saharan African region is blessed with abundant natural resources and diverse ethnic groups, yet the region is dominated by the largest number of poor people worldwide due to inequitable distribution of national income. Existing statistics forecast decay in the quality of lives over the years compared to the continent of Asia that shares similar history with the region. In this paper, a-five dimensional first-order nonlinear ordinary differential equations was formulated to give insight into various factors that shaped dynamics of inclusive growth in sub-Saharan Africa. The validity test was performed based on ample mathematical theorems and the model was found to be valid. The model was then studied qualitatively and quantitatively via stability theory of nonlinear differential equations which depended on the policy success ratio and classical fourth-order Runge-Kutta scheme implemented in maple respectively. The results from the analysis showed that inclusive growth from abundant natural resources and ethnic diversity in sub-Saharan Africa was a function of policy reform whereby an increase in both equitable distribution of national income and accessibility of common man to the goods and services provided by the state to narrow inequality gap was accompanied with a low level of nepotism

Development of a Light Emitting Diode Lighting System with Power Factor Correction for Domestic Applications

The incandescent and fluorescent lighting systems which have been the most prominent electrical lighting choice for over 150 years are gradually being replaced in most homes with Light Emitting Diode (LED) Lighting Systems. This is due to their relatively low power consumption and good luminous intensity. LED lighting systems have revolutionized energy – efficient lighting. The significant feature of LEDs is that the light is directional with very low lagging power factor (0.2 – 0.6) as opposed to incandescent bulbs which spread the light more spherically with high power factor almost approaching unity. New LED designs address the directional limitation by using diffuser lenses and reflectors to disperse the light more. Since LED lighting represents a green technology, the issue of high power factor becomes very important. Power factor, defined as the ratio of real power consumed by a load (expressed in Watts) to apparent power (expressed in Volt-amperes), is a figure that ranges from zero to unity, it indicates the degree of distortion and phase shift in the current waveform. The work reported here proposes LED lighting system equipped with power factor correction driving circuit fed with dc – dc converter circuit. The power factor correction function is achieved by using switching converters circuit that operate directly from a full-wave rectified DC bus on a passive valley fill (PVF) circuit operating in Discontinuous Inductor Current Mode (DICM) for Power Factor Correction (PFC). This converter is simple to control, easy to construct and attractive for low cost application for domestic lighting. The results obtained have shown a LED lighting system with a lagging power factor of 0.85 that is energy – efficient compared to its conventional counterpart in domestic lighting applications