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In the active distribution networks (ADNs), the emerging trend of high penetration of sustainable energy sources such as wind turbines, photovoltaics, and the forthcoming integration of energy storage devices and additional dynamic loads like plug‐in‐electric vehicles (PEVs) influences to change the nature of electric distribution networks. Consequently, it deteriorates power quality and reliability in terms of unacceptable voltage rise‐drop, harmonic distortion, voltage unbalance, and excessive power loss. In this context of transition into the active distribution network, the probabilistic optimal power flow (P‐OPF) in the ADN is considered an important tool that helps the distribution grid operators for defining the optimal settings of the system's control variables. However, the optimal solution of P‐OPF becomes highly complex while considering the multiple variables, time‐varying characteristics and operational uncertainties associated with sustainable resources, consumer behaviour and electricity market prices. This review aims at promoting the research and discussion of P‐OPF studies in the context of ADNs characteristics and challenges. First, we perform a data‐driven and visualized scientometric analysis of 1988 quality documents retrieved from the Scopus during the last ten years using VOSviewer software. Second, an in‐depth investigation of the recent and emerging techniques for solving the P‐OPF problem is presented. Third, a set of recommendations and highlights of future challenges for P‐OPF in ADNs are offered. The review findings showed high interest among the scientific community in sustainable energy source integration, given the recent rise in publications and citations. Also, there is still a lack of innovative optimization techniques that can adequately handle the current issues associated with P‐OPF and objectives with fair computational efficiency and accuracy. Finally, this paper offers a guide for P‐OPF researchers to navigate the recent studies considering the sustainable sources, spot the new research frontiers, and identify the most impactful countries and publishers. [ABSTRACT FROM AUTHOR]

Helical gratings (HGs) have an achievement of flexible mode conversion for fibre‐guided orbital angular momentum (OAM) modes. Sampled reflection HGs can realise the generation and conversion of OAM mode with comb spectra. They can be used to simultaneously filter wavelengths and convert modes, and thus may be applied to the hybrid multiplexing technology with wavelength division multiplexing and mode‐division multiplexing. [ABSTRACT FROM AUTHOR]

A novel miniaturised dual‐band bandpass filter (BPF) using improved split ring λ/4 resonator and stepped impedance resonator (SIR) is proposed. A simple analysis is given for each resonator. By tuning the geometric parameters of the resonators, the two passbands of the BPF can be adjusted separately. Source‐load coupling is adopted to achieve more transmission zeros in the stopband. The new dual‐band BPF, which has a miniature circuit size of 0.18 × 0.18λg, presents narrow and sharp passband characteristics. Good agreement is found between simulated and measured results, which verify the high‐frequency selectivity. [ABSTRACT FROM AUTHOR]

A novel dual‐band Wilkinson power divider (WPD) is designed for the purpose of operating at two arbitrary frequencies. The theory and design procedure of the novel component are presented in detail. For demonstration, a dual‐band WPD with operating frequencies of 1.0 and 2.6 GHz is proposed, fabricated and tested. The good agreement between the measured and simulated results confirmed the design concept. Measurements show that insert losses both at the two central frequencies are less than 3.3 dB. Both return loss and port isolation have good performances, which are more than 21 and 28 dB separately. [ABSTRACT FROM AUTHOR]

A multi‐stage least mean square (MLMS) algorithm based on polynomial fitting in time‐varying systems is proposed. As the name implies, the MLMS algorithm is divided into different stages in sequence. In non‐stationary environments, the optimal weight coefficients of the adaptive filter are variable with time and they are assumed to be approximated by a polynomial. According to the conditions above, the convergence of the MLMS algorithm is verified through theoretical analysis and formula derivation. Similar to the least mean square (LMS) algorithm, the step size μ must be chosen in the specific range to guarantee the feasibility and effectiveness of the MLMS algorithm. Compared with the LMS, LMF and NLMS algorithms, the MLMS algorithm provides the best convergence performance in the simulation experiments. [ABSTRACT FROM AUTHOR]