O.I. Okoro

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• B.ENG, M.ENG, Ph.D
• Professor at Michael Okpara University of Agriculture

Flux-switching wound field machines (FSWFMs) offer high torque density and independence from rare-earth materials, making them promising candidates for sustainable electric vehicles and industrial applications. However, their adoption is limited by challenges such as high torque ripple, efficiency variations, and sensitivity to manufacturing tolera...

Flux-Switching Wound Field Machines (FSWFMs), renowned for their high torque density and independence from rare-earth materials, hold significant promise for sustainable electric vehicles and industrial applications. However, their widespread adoption is limited by challenges such as high torque ripple, efficiency variations, and sensitivity to man...

In this study, we investigate the potential of wind power and subsequently determine the Weibull parameters of a rural community (Okorobo-Ile town, in Andoni local government area of Rivers State, Nigeria) using four years of real-time measured data (2020, 2021, 2022, and 2023). The Weibull shape and scale factors are crucial parameters in modeling...

This work utilizes the particle swarm optimization (PSO) for optimal sizing of a solar–wind–battery hybrid renewable energy system (HRES) for a rural community in Rivers State, Nigeria (Okorobo-Ile Town). The objective is to minimize the total economic cost (TEC), the total annual system cost (TAC) and the levelized cost of energy (LCOE). A two-ste...

This work utilizes the particle swarm optimization (PSO) for the optimal sizing of a solar – wind – battery hybrid renewable energy system (HRES) for a rural community in Rivers State, Nigeria (Okorobo-Ile Town). The objective is to minimize the total economic cost (TEC), the total annual system cost (TAC) and the levelized cost of energy (LCOE). A...

The increasing demand for electrical energy, driven by technological advancements in underdeveloped and developing nations, has led to a growing reliance on renewable energy sources. Inductive loads requiring high starting currents can significantly affect power sources. Therefore, it is imperative to investigate the impacts of inductive loads on p...

Speed control of a squirrel cage induction motor (SCIM) using a novel control algorithm with proportional integral derivative (PID), fuzzy logic (FL) controller, hybrid controller (FL-PID), and optimized hybrid controller (FL-PID-PSO) was designed, simulated, and analyzed in this paper. 2.5kW three-phase SCIM was considered, and decoupling of the f...

This study proposes and utilizes a modified multi-objective particle swarm optimization (M-MOPSO) algorithm for the optimal sizing of a solar-wind-battery hybrid renewable energy system for a rural community in Rivers State, Nigeria. Unlike previous studies that primarily focused on minimizing total economic cost (TEC) and total annual cost (TAC),...

This work investigates the technical, economic and environmental feasibility of four solar – wind off grid hybrid renewable energy system (HRES) models to provide electrification for Okorobo-Ile town in Andoni Local Government Area of River State, Nigeria using the Hybrid Optimization of Multiple Electric Renewables (HOMER) software. In particular,...

High Impedance Fault (HIF) occurs when an energized conductor comes in direct or indirect contact with a quasiinsulator. If not detected and eradicated, it would lead to fire outbreak, pose a risk to human lives, and negate the existing environmental friendliness. The transmission lines data of the 330 kV, south east Nigeria network were obtained a...

The idea in this paper is the reconfiguration of the windings of a three-phase induction motor. This is done by obtaining a sample machine with known parameters and modeling the same machine in Ansys Maxwell finite element analysis (FEA). The sample machine has a single-layer winding but is later reconfigured to have double-layer windings under the...

Stressed electric networks, either due to increased loading because of system expansion or due to extreme contingencies, often result in voltage limit violations and overload of lines, leading to extreme degradation in the system's damping torque, metamorphosing into fluctuations, and dynamic instability. This paper employs two series Flexible Alte...

Flexible alternating current transmission system (FACTS) devices have provided proficient answers to power system instabilities faced in system operations today with very little infrastructural investment. This paper investigates the effects of the combination of two kinds of FACTS controllers: static VAR compensators (SVC) and thyristor-controlled...

With the ever-increasing complexity of power systems, there is a need to provide stable, secure, controlled, and high-quality power, especially in the deregulated power industry as it exists in Nigeria. One of the major disadvantages of network enlargement is the deterioration in the damping torque of the whole system, which mitigates against the s...

Interest in wound-field flux switching machines (WF-FSMs) in the scientific community has increased due to their high reliability, low cost, and absence of magnets. In the context of global sustainability, it is required that WF-FSMs fulfill physical, technological, and environmental requirements through design and optimization studies. This study...

The impact of structural dimensions and rotor pole numbers on the load and no-load torques of a dual-stator permanent magnet machine is investigated and presented in this work. Finite element analysis (FEA) is adopted in the prediction since it exhibits higher computation accuracy compared to other methods such as analytical modeling, techniques, e...

This paper presents the dynamic analysis and computer simulation of interior permanent magnet synchronous motor (IPMSM) with intermittent loading. This objective was realized with the aid of the MATLAB m.file function program, which is based on an explicit Runge-Kutta fourth-order numerical method to solve a set of first-order differential systems...

With the ongoing expansions and growth of the electric utility industry, including deregulation in Nigeria, numerous changes characterized by additional generating stations, an increase in transmission lines, and increased loads are experienced, thereby pushing the transmission systems closer to their stability and thermal limits and, hence, causin...

This paper presents the effect of saliency and core losses on the dynamic behavior of a permanent magnet synchronous motor. This objective was realized with the aid of Matlab and Simulink. The two motors (Interior and Surface-Mounted Permanent Magnet Synchronous Motor) used in this work are of specifications 3-phase, 2 KW, 50 Hz, 4 poles, 240 V eac...

In this study, the analytical design and electromagnetic performance comparison of a squirrel-cage induction motor (SCIM) and a wound-field flux switching motor (WFFSM) for high-speed brushless industrial motor drives is undertaken for the first time. The study uses analytical sizing techniques and finite element analysis (FEA) to model and predict...

We are currently serving as Guest Editors for the Special Issue “Mathematical and Numerical Analysis in Electrical Engineering, 2nd Edition” to be published in the journal Mathematics MDPI (ISSN 2227-7390, IF 2.592). Mathematics and electrical engineering have always existed mutually. Mathematics is the science of studying numbers, quantities, geom...

Over the years, the Nigerian power system is beset with lingering problems, which include severe power losses, as well as very low transfer capability of the transmission network to evacuate power from generating stations to the load at the distribution level. Presently, the Nigerian power industry is undergoing restructuring, especially in the gen...

The impact of structural dimensions and rotor pole numbers on the load and no-load torques of dual stator permanent magnet machine is investigated and presented in this work. Finite element analysis (FEA) is adopted in the prediction, since it exhibits higher computation accuracy compared to other methods such as analytical modelling and techniques...

The aim of this paper is to develop a generalized MATLAB program to study the dynamic behavior of a three-phase induction motor. The d-q axis transformation theory is applied in rotor reference frame to study the motor dynamics. A general-purpose MATLAB program is developed and used for the dynamic simulation of a 5HP, 460V, 60Hz, 4-poles induction...

Flux switching machines play a crucial role in emerging sectors such as renewable energy, electric vehicles, and the aerospace industry. Recent advancements have underscored their potential for achieving high torque density, effective heat management, and flux-weakening capabilities. This paper provides a comprehensive review of the design optimiza...

Over the years, the Nigerian power system has been beset with lingering problems, which include severe power losses as well as the very low transfer capability of the transmission network to evacuate power from generating stations to the load at the distribution level. Presently, the Nigerian power industry is undergoing restructuring, especially i...

In this paper, a thorough framework for multiobjective design optimization of switched reluctance motor (SRM) is proposed. Selection of stator and rotor pole embrace coefficients is an essential step in the SRM design process since it influences torque output and torque ripple in SRM. The problem of determining optimal pole embrace is formulated as...

Losses such as rotor iron and stator iron losses, magnet eddy current loss, as well as efficiency of a double stator permanent magnet machine having varying rotor pole numbers is estimated and presented in this study. This current investigation would be vital for electrical machine designers in quantifying the amount of losses in the various sectio...

The impact of structural dimensions and rotor pole numbers on the load and no-load torques of dual stator permanent magnet machine is investigated and presented in this work. Finite element analysis (FEA) is adopted in the prediction, since it exhibits higher computation accuracy compared to other methods such as analytical modelling and techniques...

In the power system operation, efficient energy utilization is vital. However, with the advent of voltage unbalance, the system is faced with reduced efficiency in the process of energy conversion. This phenomenon occurs due to the asymmetrical behavior of the operating voltage phasor displacement and magnitudes. This occurrence has been attributed...

This paper presents DC machine dynamic responses when certain variables are varied. This involves producing Simulink block diagram of a DC separately excited motor from where the system responses are generated. Thereafter, studying the output current and speed transient duration at each parameter variation using the block diagram. This is done unde...

This paper presents the dynamic analysis and computer simulation of interior permanent magnet synchronous motor (IPMSM) with intermittent loading. This objective was realized with the aid of MATLAB m.file function program, which is based on an explicit Runge-Kutta fourth order numerical method to solve a set of first order differential system of eq...

South Africa is currently facing shortage of electricity, as the national utility is forced to implement routine load shedding stages. To tackle this problem, the country has planned to boost its electricity infrastructure through the systematic development of renewable energy independent power projects to provide additional capacity for the nation...

The essence of this research work is to develop a thermal model for an induction machine that will enable the prediction of temperature in different parts of the machine. This is very important first to the manufacturer or designer of an induction machine because with these predictions one can decide on the insulation class limits the machine belon...

This paper presents DC machines dynamic responses when certain variables are varied. This involves producing a Simulink block diagram of a DC separately excited motor from where the system responses are generated. Thereafter, study the output current and speed transient duration at each parameter variation using the block diagram. This is done unde...

The switched reluctance motor (SRM) is among the special purpose electric machine family. It is simple in construction and avoids use of magnet so it is cheap to manufacture. The magnetic characteristics and simulation of three phase 12/8 switched reluctance motor (SRM) for enhanced starting torque is presented. The motor was analyzed using finite...

Flexible alternating current transmission system (FACTS) devices have provided proficient answers to power system instabilities faced in the systems operations today with very little infrastructural investment fund. This paper investigates the effects of the installation of the combination of two kinds of FACTS controllers; static VAR compensator (...

This paper is on predicting the stability behaviour of three horsepower induction motor using eigenvalue method. MATLAB software is used for the study of the torque-slip characteristics of the machine at various slip ranges under steady-state condition. The stability study involves the simulation of the linearized machine's electrical and mechanica...

This paper is on predicting the stability behavior of a three-horsepower induction motor using the eigenvalue method. MATLAB software is used for the study of the torque-slip characteristics of the machine at various slip ranges under steady-state conditions. The stability study involves the simulation of the linearized machine's electrical and mec...

Stressed electric network, either due to increased loading because of system expansion, or due to extreme contingencies, often result in voltage limit violations and overload of lines leading to extreme degradation in the system's damping torque, metamorphosing into fluctuations and dynamic instability. This paper employs two series, Flexible Alter...

In this paper, the dynamic model of a six-phase induction motor is presented. The machine is simulated in a finite element modelling (FEM) environment and no-load experiment is performed on the prototype three-phase motor in the laboratory for comparison and validation. The stator of the three-phase motor is reconfigured into six-phase, using the d...

This paper presents the effect of saliency and core losses on the dynamic behavior of permanent magnet synchronous motor. This objective was realized with the aid of Matlab/Simulink. The two motors (Interior and Surface-Mounted Permanent Magnet Synchronous Motor) used in this work are of specifications 3-phase, 2 KW, 50 Hz, 4 poles, 240 V each. The...

Energy, which is required to run space satellites, is as old as space technology itself. The location of these satellites has made it more applicable for unconventional means of energy generation to run them. The Sun being the universal and greatest source of all forms of energy, as well as the closest energy source to space satellites, has been so...

The paper herein presents the dynamic modelling of a linear quadratic regulator based optimal direct current (DC) motor controller for improved performance. This study investigates the optimal use of a controller in the control of DC motor speed. This work also carried out a comparison of time response specification of the Linear Quadratic Regulato...

In this paper, the fault-tolerant capability in terms of inductance profile of a dual-stator permanent magnet brushless AC machine is presented. Similarly, its power-speed and torque-speed characteristics are also predicted. Special reference is made to the impact of different rotor pole numbers. A 2D-finite element analysis (FEA) procedure is adop...

This paper is used to present the application of flexible alternating current transmission system (FACTS) in the Nigerian 48-bus power system network for transient stability enhancement. Here, static VAR compensator (SVC) and static synchronous compensator (STATCOM) are separately employed to investigate the system responses when a three-phase faul...

With the ongoing expansions and growth of the electric utility industry, including deregulation in Nigeria, numerous changes characterized by additional generating stations, increase in transmission lines and loads are experienced thereby pushing the transmission systems closer to their stability and thermal limits and hence, causing the transfer o...

Induction motors are the most indispensable and widely used electric motors in industry. During start-up, loading and unloading operations, the asynchronous motor draws large currents, produce voltage dips and oscillatory torques. It is therefore important to model and study the asynchronous machine in order to predict these phenomena. Lots of work...

With the ever increasing complexity in power systems , there is the need to provide stable, secure, controlled and high quality power most especially in the deregulated power industry as obtains in Nigeria. One of the major disadvantages of network enlargement is the deterioration in the damping torque of the whole system which mitigates against th...

With the ever increasing complexity in power systems , there is the need to provide stable, secure, controlled and high quality power most especially in the deregulated power industry as obtains in Nigeria. One of the major disadvantages of network enlargement is the deterioration in the damping torque of the whole system which mitigates against th...

The analysis of cogging torque, torque ripple and total harmonic distortion of a permanent magnet (PM) flux-switching machine having separate excitation stators is presented in this study. Further, the effect of unbalanced magnetic force (UMF) on the rotor of this machine is also investigated. A comparison of the analysed machine having different r...

Comparison of the electromagnetic performance of a flux-switching permanent magnet (PM) machine having two separate stators as well as different winding topologies is investigated in this paper. Different stator and rotor pole combinations of these machines are also considered. The analysis includes the open-circuit and on-load characteristics of t...

The energy system worldwide is undergoing transition to renew-able energy (RE) due to concerns over depletion and environmen-tal impacts of fossil-fuel sources, energy security, as well as the volatile nature of crude oil prices. In Nigeria, the need to support this transition is underpinned by the deplorable state of Nigeria’s electricity sector w...

In this paper, the electromagnetic performance of double-stator switched flux permanent magnet (DS-SFPM) machine (i.e., DS-SFPM 6/13), conventional single-stator switched flux permanent magnet (SFPM) machines having C-core and E-core stator configurations (i.e., C-core SFPM 6/13 and E-core SFPM 6/11), and partitioned-stator switched flux permanent...

The effect of torque ripple, total harmonic distortion (THD), cogging torque and unbalanced magnetic force (UMF) on a developed double-stator flux-switching permanent magnet (DS-FSPM) machine having different rotor poles is studied in this article. Moreover, the impact of their varying structural geometries is also considered. It is observed that t...

The torque profile of a double-stator permanent magnet (PM) synchronous machine of 90 mm stator diameter having different rotor pole numbers as well as dual excitation is investigated in this paper. The analysis includes a comparative study of the machine’s torque and power-speed curves, static torque and inductance characteristics, losses and unba...

This paper is concerned with the unabated epileptic power (electric) delivery which is seen to be periodic with a struggling generation capacity and losses-prone inefficient transmission network in Nigeria. Ordinarily, it should mean that only an average Nigerian suffers directly, and only, the burden of this inefficiency, whereby electricity suppl...

Data for investment into renewable energy resources in Nigeria is mainly unavailable due to over reliance on conventional resources for energy generation. However, recent developments in the energy sector have portrayed gradual attention to investments in renewable energy resources. This paper reviews the Renewable Energy Master Plan (REMP) which i...

Electricity is the basic tool that drives industrialization, technological advancement, engineering transformation and economic growth all over the world. The situation of Nigeria's electricity power sector is one that has defied virtually every effort made to resurrect it from its state of dilapidation. A major concern is “can there ever be stable...

In this paper, the core loss and permanent magnet (PM) eddy current loss on different parts of double-stator switched flux PM machine are presented. Furthermore, the efficiency of the analysed machine is also given. The calculation includes the losses at a different load current, at a different rotor speed and at varying rotor position. The analyse...