The increased penetration of renewable energy sources (RES) and electric vehicles (EVs) is resulting in significant challenges to the stability, reliability, and resiliency of the electrical grid due to the intermittency nature of RES and uncertainty of charging demands of EVs. There is a potential for significant economic returns to use vehicle-to-grid (V2G) technology for peak load reduction and frequency control. To verify the effectiveness of the V2G-based frequency control in a microgrid, modeling and simulations of single- and multi-vehicle-based primary and secondary frequency controls were conducted to utilize the integrated components at the Canadian Centre for Housing Technology (CCHT)-V2G testing facility by using MATLAB/Simulink. A single-vehicle-based model was validated by comparing empirical testing and simulations of primary and secondary frequency controls. The validated conceptual model was then applied for dynamic phasor simulations of multi-vehicle-based frequency control with a proposed coordinated control algorithm for improving frequency stability and facilitating renewables integration with V2G-capable EVs in a microgrid. This proposed model includes a decentralized coordinated control of the state of charge (SOC) and charging schedule for five aggregated EVs with different departure times and SOC management profiles preferred by EV drivers. The simulation results showed that the fleet of 5 EVs in V2B/V2G could effectively reduce frequency deviation in a microgrid.

Earthing systems play an essential role in electrical systems in terms of safety for people in the vicinity against the hazard of electric shocks as well as protection and proper operation of equipment during the incidence of faults. Both are achieved by providing a low-impedance path that can dissipate fault currents to the conductive mass of Earth. One of the first steps in the design of an earthing system is estimating the total resistance to earth and determining the proper size and basic layout of the earth electrode required. Engineers must design adequate earthing systems that comply with international standards and national regulations, which in fact incorporate a variety of earthing methods and various formulae to obtain the design parameters, especially the earthing resistance. The effects of using the varied formulae for each earthing technique are ambiguous and entail considerable risks, and thus require comprehensive compilations and critical examinations. This paper reviews many of the earthing design formulae available in widely used international standards and published scientific papers for a comparative analysis of their differences. The results of a rigorous survey for each earthing type, based on respective electrical resistances’ calculations evaluated for a specified range of resistivities, are presented in line graphs to show precise trends. A recommended list of the most conservative formulae from a safety perspective, based on the results obtained, is outlined as a basis for computing the earthing resistance for designing effective earthing systems. This provides a beneficial compact reference to facilitate the revision and provision of international earthing standards agreement. Copyright © 2021 The Authors - Published by Praise Worthy Prize under the CC BY-NC-ND license.

Earthing system plays an essential role in electrical systems in terms of safety for people in the vicinity against the hazard of electric shocks as well as protection and proper operation of equipment during the incidence of electric faults by providing a low-impedance path that can dissipate fault currents to the conductive mass of earth. Engineers are faced with the design of adequate earthing systems that comply with national standards and regulations which apparently incorporate a variety of earthing methods and various formulae to obtain the design parameters such as the earthing resistance and conductor size. Manual calculation of such parameter makes the design quite laborious, tedious, and time-consuming but could conceivably be performed much quicker by a computer software. This paper presents a proposed step-by-step approach for the design of a reliable and effective earthing system for low-voltage installations. The main objective of this work is to develop a computer-aided and easy-to-use template which could be useful for industry practitioners in Malaysia who are responsible with earthing system design. A simple auto calculation software template was developed using Microsoft Excel spreadsheet. The template was tested by a consulting company in order to meet their industry needs. The developed template provides a technically acceptable computer simulation and yet a low-cost solution to the complex issue of effective design of earthing systems for low-voltage installations.