This study provides a comprehensive literature review of techniques for harmonic related power quality improvement of electrical generation systems. Increasing interest in these aspects is due to ever more stringent power quality requirements, deriving from new grid codes and compliance standards, aimed at limiting waveform harmonic distortion at all points of the distribution network. Although a wealth of literature is available for such techniques, it has never been compiled into a handbook incorporating all the solutions aimed at both electrical machine and power system engineers.

Transcontinental grid interconnection and clean energy development for sustainability are the prime objectives to address through global energy interconnection (GEI) platform. Key issues can be solved through GEI such as environmental pollution, climate change, resources scarcity and unbalanced development. The growing concern of fossil fuel depletion leads to the exploitation of renewable energy which is mostly located on Arctic and Equator zones. This study addresses about the importance, current projects and research directions of clean energy, smart grid, ultra-high voltage transmission, grid interconnection trends around the world in order to globally interconnect the future grid. The review results provide comprehensive background knowledge to all the researchers in order to investigate further into the field.

The existing research on furfural analysis mainly focuses on the relationship between the furfural content in oil and the degree of polymerization (DP) of the paper, which are always obtained by accelerated thermal aging at high temperatures. However, the operating temperature of a winding is relatively low, approximately 60°C to 90°C. Thus, the relationship established at high temperature may be not suitable for the operating temperatures. In this research, aging tests of oil-paper systems at different temperatures ( from 100°C to 130°C) were carried out, with the DP, furfural content in oil and furfural content in paper being measured regularly to analyze the effect of temperature variation on the production and diffusion behavior of furfural in oil–paper insulation. The results show that temperature influences the production of furfural, i.e., there is no obvious difference in the amount of furfural produced by paper in the initial aging periods; however, a higher temperature results in more furfural being produced when the DP decreases to values below 600. An obvious diffusion process occurs after furfural is produced in paper in accelerated aging experiments, resulting in most of the furfural content remaining in the cellulose paper in the initial aging period.

This study describes the use of entropy model for some systems used in the dielectric technique. In this manner, the changes considered in the breakdown voltage are similar to those described by the probability entropy formula. This is particularly the case due to the radius ratios of spherical and cylindrical electrode systems modelled in the high-voltage technique. The breakdown voltage variations in the spherical and cylindrical electrode systems are consistent with the Shannon formulation of Information. These information curves demonstrate how the system should be operated under optimal conditions and these curves exhibit entropy changes due to voltage and field strength.

For its high coefficient of performance and zero local emissions, the heat pump (HP) has recently become popular in North Europe and China, which shows potential in absorbing local photovoltaic (PV) generation. In this study, the authors describe a distributionally robust optimisation (DRO)-based HP day-ahead operational schedule model (HP-DOSM) to match the PV power generation, which can well capture the uncertainties of weather, PV, and load prediction errors. Moreover, this DRO-based HP-DOSM can be transformed into a tractable deterministic model. The DRO method they proposed is suitable for linear expectation constrained optimisation whose ambiguity set is constructed using Kullback–Leibler divergence, which could be further transformed into deterministic conic/linear constraints. Compared with robust optimisation (RO) models, the authors’ model is less conservative since more statistical information on the uncertainties is utilised. Numerical tests were conducted to demonstrate its performance, compared with the RO model via Monte Carlo simulations.