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Ijumba N, Abungu NO. "Power factor correction and energy cost savings.". In: The 4TH IEEE Africon Conference in Africa ( South African Universities Power Engineering Conference. IEEE Africon Conference in Africa ( South African Universities Power Engineering Conference); 1994. Abstract

In this paper a hybrid numerical technique is presented, suitable for analyzing transmission properties of an arbitrarily shaped slot in a thick conducting plane. The slot is  excited by an electromagnetic source of arbitrary orientation. The analysis of the problem is based on the "generalized network formulation" for aperture problems. The problem is solved using the method of moments(MOM) and the finite element method(FEM) in a hybrid format. The finite element method is applicable to inhomogeneously filled slots of arbitrary shape while the method of moments is used for solving the electromagnetic fields in unbounded regions of the slot. The cavity region has been subdivided into tetrahedral elements resulting in triangular elements on the surfaces of the apertures.  Validation results for rectangular slots are presented. Close agreement between our data and published results is observed.  Thereafter, new data has been generated for cross-shaped, H-shaped and circular apertures.

Ijumba, N; Abungu NO. "Power Factor Correction And Energy Cost Savings.". 1994.
Ijumba N, Gakuru M, Abungu NO. "Applications of electric field calculations in optimization of insulator design.". In: The 4th IEEE International Conference on Properties and Applications of Dielectric Material. The IEEE International Conference on Properties and Applications of Dielectric Materials; 1994. Abstract

When an insulator is placed in an electrode gap, its surface charge field distorts the geometric field, leading to a flashover at a voltage value dependent on the degree of the gap field distortion. This paper reports on studies conducted to determine the relationship between flashover voltages and electric filed distribution along solid insulator surfaces. The surface electric field distribution along different insulator profiles was determined using the Finite-Difference method, and the flashover of the actual profile model measured. The obtained results show that each profile had a peak surface electric field and the higher the peak value, the lower the flashover voltage. The correlation curve for peak electric field and flashover voltage was developed using a curve fitting technique based on the Nelder-Mead simplex algorithm.

Ijumba N, Orero SO, Abungu NO. "Computer applications in voltage monitoring and control (case of the Kenya Power and Lighting Company.". In: The International Workshop on Voltage Collapse & Voltage Regulatio. The International Workshop on Voltage Collapse & Voltage Regulation; 1992. Abstract

When an insulator is placed in an electrode gap, its surface charge field distorts the geometric field, leading to a flashover at a voltage value dependent on the degree of the gap field distortion. This paper reports on studies conducted to determine the relationship between flashover voltages and electric filed distribution along solid insulator surfaces. The surface electric field distribution along different insulator profiles was determined using the Finite-Difference method, and the flashover of the actual profile model measured. The obtained results show that each profile had a peak surface electric field and the higher the peak value, the lower the flashover voltage. The correlation curve for peak electric field and flashover voltage was developed using a curve fitting technique based on the Nelder-Mead simplex algorithm.

Ireri TG, Murage DK, Abungu NO. "Short Term Load Forecasting Using Artificial Neural Networks.". In: Mechanical Engineering Annual Conference. Juja; 2013. Abstractjkuat_conf_paper.pdf

Load forecasting refers to the prediction of future load conditions based on present or historical data. This is important especially for transmission planning and economic dispatch. In this paper, an Artificial Neural Network (ANN) is trained using historical data for a sub-station at Ruiru, Kenya and the corresponding loading conditions for the sub-station are used to test its accuracy in forecasting the electrical load when given other parameters.

Ireri TG, Abungu NO. "An Efficient Method of Load Forecasting for Non-Working Days.". In: Kenya Society of Electrical and Electronics Engineers. Kenya Society of Electrical and Electronics Engineers (KSEEE); 2012. Abstract

Power utility companies are required to supply customers with power within specified voltage limits. Voltage rise in networks with distributed generators therefore poses a challenge. This paper presents a coordinated network controller whose objective is to maintain an optimal voltage profile across the power network. The operations of distributed generators, on-load tap-changing transformers and reactive power sources are controlled. The controller is modelled as an optimisation problem which is solved using Particle Swarm Optimisation. The IEEE 30-bus test network is then used to verify the effectiveness of the controller. The results obtained show that this controller can greatly improve the voltage profile of a power network by varying the parameters of existing generation and voltage control equipment.

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