High-voltage engineering
The topics covered in this book include gas discharge, insulating materials, system earthing, overvoltage and insulation coordination, and high-voltage equipment and testing techniques. In two chapters, the principles of design of high-voltage busbars are discussed, together with their insulation and ampacity, whether they are of conventional air-insulated type or the metal-clad GIS types now widely used at the HV and EHV levels. The various types of circuit breakers and cables are discussed including mention of solid-state breakers and superconducting cables. The authors present a treatment of power system grounding, external and internal overvoltages imposed on system insulation, and techniques adopted for insulation coordination. The last three chapters focus on the area of insulation testing, covering the topics of high-voltage generation, measurements, and standard specifications.
 Usefulness of SPICE in high voltage engineering education
The usefulness of the SPICE circuit analysis program is demonstrated in high voltage engineering education, where assembling the actual circuit might be very time-consuming and costly and hand calculation techniques could be very complicated. Two representative high-voltage generating circuits are simulated. One is an impulse generator and the other is a voltage multiplier. The first circuit is analyzed for the dependence of the risetime of the impulse voltage on the values of the wave-front resistor, line inductance, and load capacitance. A three-stage impulse generator is also simulated to determine the effects of wave-front and wave-tail resistors on the voltage waveform. The second circuit is analyzed for the dependence of the output voltage and ripple on the load resistance and output capacitance. SPICE can similarly be used for most high-voltage systems in the laboratory, making use of students’ time much more effective as well as limiting their exposure to very high voltages, ensuring personal safety in the laboratory.
 Properties of Polymer Composites Used in High-Voltage Applications
The present review article represents a comprehensive study on polymer micro/nanocomposites that are used in high-voltage applications. Particular focus is on the structure-property relationship of composite materials used in power engineering, by exploiting fundamental theory as well as numerical/analytical models and the influence of material design on electrical, mechanical and thermal properties. In addition to describing the scientific development of micro/nanocomposites electrical features desired in power engineering, the study is mainly focused on the electrical properties of insulating materials, particularly cross-linked polyethylene (XLPE) and epoxy resins, unfilled and filled with different types of filler. Polymer micro/nanocomposites based on XLPE and epoxy resins are usually used as insulating systems for high-voltage applications, such as: cables, generators, motors, cast resin dry-type transformers, etc. Furthermore, this paper includes ample discussions regarding the advantages and disadvantages resulting in the electrical, mechanical and thermal properties by the addition of micro- and nanofillers into the base polymer.
 Defective Barrier on Voltage Optimization for Small Airgap
Aim: To investigate the effect of defective barrier on the optimum breakdown voltage, using positive and negative needle electrodes in an air medium of 10cm gap distance.
Methodology: The barriers for the tests were placed at 2.5cm from the point electrode for each test. The defective barriers were created by having holes of 6mm, 8mm, 12mm and 20mm diameter at the centre of the barrier. For each barrier position the breakdown test for positive and negative polarity for needle electrodes were carried out. Also, tests were carried out with non defective barrier and with point-plane airgap (without barrier).
Result: From the test without barrier the negative point electrode offered higher breakdown voltage (1.8 times), than the positive point. When with plain barrier the positive point was optimized to 1.6 times, while the negative point was lowered.
The optimum breakdown voltage decreased gradually as the hole diameter increased and at 20mm hole diameter the effect was like the plain barrier.
Conclusion: From the results, optimization is only effective with positive point’s electrode and it endures even with small opening within the ionization zone. It is necessary to check this in practical situations because the specified optimum voltage of an equipment may be lowered.
 Design of Reactive Power and Voltage Controllers for Converter-interfaced ac Microgrids
This paper aims at presenting design of two controllers for the study of a microgrid testbed. The response of the microgrid testbed to different short circuits would be investigated under these two control regimes, namely, reactive power and voltage controls. This paper therefore presents design of active power, reactive power and voltage regulators for a converter-interfaced ac microgrid. The design was performed using Simulink Control Design® in the Department of Electrical and Computer Engineering, Curtin University, Sarawak, Malaysia between May 2015 and December 2015. The microgrid consists of two 5.5kW, 575V wind turbines based on doubly-fed induction generators (DFIGs). The systems designed are pitch control system, active power regulator, reactive power regulator, grid ac voltage regulator, dc bus voltage regulator, grid-side converter current regulator and rotor-side converter current regulator. The time-domain step response analysis for each modeled plant indicated stable performance but poor response.
 Khalifa, M., 1990. High-voltage engineering.
 Suthar, J.L., Laghari, J.R. and Saluzzo, T.J., 1991. Usefulness of SPICE in high voltage engineering education. IEEE transactions on power systems, 6(3), pp.1272-1278.
 Pleşa, I., Noţingher, P.V., Schlögl, S., Sumereder, C. and Muhr, M., 2016. Properties of polymer composites used in high-voltage applications. Polymers, 8(5), p.173.
 Afa, J.T., 2013. Defective Barrier on Voltage Optimization for Small Airgap. Current Journal of Applied Science and Technology, pp.1301-1310.
 Aminu, M.A., 2016. Design of reactive power and voltage controllers for converter-interfaced ac microgrids. Current Journal of Applied Science and Technology, pp.1-14.