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This paper focuses on both voltage transients and short-duration RMS variations, and presents a unique and heterogeneous approach to their assessment by applying AI tools. The database consists of both real (obtained from Lithuanian PQ monitoring campaigns) and synthetic data (obtained from the simulation and literature review). Firstly, this paper investigates the fundamental grid component and its harmonics filtering with an IIR shelving filter. Secondly, in a key part, both SVM and KNN are used to classify PQ events by their primary cause in the voltage–duration plane as well as by the type of short circuit in the three-dimensional voltage space. Thirdly, since it seemed to be difficult to interpret the results in the three-dimensional space, the new method, based on Clarke transformation, is developed to convert it to two-dimensional space. The method shows an outstanding performance by avoiding the loss of important information. In addition, a geometric analysis of the fault voltage in both two-dimensional and three-dimensional spaces revealed certain geometric patterns that are undoubtedly important for PQ classification. Finally, based on the results of a PQ monitoring campaign in the Lithuanian distribution grid, this paper presents a unique discussion regarding PQ assessment gaps that need to be solved in anticipation of a great leap forward and refers them to PQ legislation. [ABSTRACT FROM AUTHOR]

The proposed method, based on three combined criteria—Sn—design capacity of the power line, LF, (line flow)—power flow in an electric transmission line, MVA, and the ratio of LF/Sn—allows for ranking electric transmission lines when calculations are performed in normal/pre-emergency modes. A combined set of criteria used to study critical/post-emergency N-k modes is developed. The simulations were performed on the real Baltic 330 kV electricity transmission system. The results reveal that when the power system operates in different load modes, most of the critical power lines determined by our method fall into the actual set of important/"critical" power transmission lines. This allows us to significantly reduce the number of simulated combinations and shorten the calculation time required for it. During the study of the Baltic electricity system, it was found that the developed method was accurate and efficient and suitable for the assessment of the reliability of real electricity transmission networks when planning operational and perspective work modes. The simulations results revealed the high reliability of the Baltic electricity system. The 330 kV electricity transmission network of the Baltic countries fully meets the N-2 criterion (usually, electricity transmission networks are designed to meet the N-1 criterion). [ABSTRACT FROM AUTHOR]

Featured Application: The results and ideas in this paper have a high practical significance, thus can easily be applied by grid operators and any other interested parties. Firstly, the discovered principles of voltage sags propagation can be used for the planning and implementation of a PQ monitoring system, as has successfully been carried out in Lithuania. Secondly, the created BRELL-based test scheme can be used and expanded in further researches. Thirdly, the proposed methodology, involving both reliability indexes and probabilistic analysis of the primary causes of faults in the PQ field, can be used by grid operators, while the method created for the estimation of functions (distributions) similarity can be used universally. Fourthly, in a wider context, the findings will be useful for grid planning, the framework of national energy strategies and legal documents, also as a PQ database for machine learning in anticipation of AI algorithms. Nowadays, voltage sag continues to remain a critical PQ issue in the industry. Since it is not possible to install a voltage analyzer on every node, optimal monitoring locations must be determined. However, during the PQ monitoring campaign of the Lithuanian DSO grid, the execution of this task was inhibited by the lack of knowledge and literature about the fundamentals of voltage sags propagation. Therefore, the first part of this paper investigates the propagation paths of voltage sags by using a voltage sag matrix method on the created test grid, which for the first time is BRELL-based. This paper is the first to not only investigate voltage sags propagation paths (both downward and upward) in detail, but also to investigate them complexly, encompassing all four types of short-circuits, both voltages (phase-to-phase and phase-to-ground), and interconnections with other PQ events (interruption, transient, unbalance). The result has established a generalization of voltage sags propagation mechanisms by inductive reasoning and laid the foundation for the further development of PQ theory. The second part of this paper focuses on the Lithuanian DSO grid and is one of the first to investigate voltage sags/interruptions through the prism of both relationship with reliability indexes (SAIFI and SAIDI) and primary causes. For this purpose, we created our own scientific methodology, applying known probabilistic and statistical methods along with newly proposed approaches, in particular for ACR success evaluation and estimation of functions similarity. [ABSTRACT FROM AUTHOR]

In the past few years, technical progress has determined traditional electric power system conversion to Smart Grids, and consequently empowered a worldwide renaissance in the forgotten PQ field. Since the installation of PQ monitors is currently associated with high investments and operational costs, it is inappropriate to install a monitor on each grid busbar. Hence, grid operators must establish the best cost–benefit scenario for monitors installation and achieve maximal observability with a limited number of analyzers. Firstly, this paper presents a review of the state-of-the-art of displacement strategies, and discusses them regarding the tendencies of node selection criteria, the test schemes used, and the grid size. Secondly, the relevant fundamental issues which must be solved in the future in order to eliminate restrictions in PQ monitors' allocation planning are presented and discussed. These issues concern the treatment, interpretation, and assessment of PQ events, measurement chain technical features, PQ's role in the grid planning stage, communication technologies, and other remote monitoring aspects, and integration with other Smart Grid applications. The provided insights are based on experience which has been obtained during the PQ measurement campaign in the Lithuanian DSO grid. Finally, a PQ system development strategy—both short-term and long-term perspectives—in the Lithuanian distribution grid is presented, including monitors allocation criteria. [ABSTRACT FROM AUTHOR]

In this study, we applied a mathematical model to explore the mechanism and factors leading to phase separation and the formation of branching structures with nanocolumns extending from larger clusters formed on the substrate of a grown film. The mathematical model simulated the growth of a thin film over time by using partial differential equations, including the processes of adsorption, phase separation, and diffusion due to the curvature of the thin film surface. The modeling results revealed the possible mechanism that could lead to the formation of the described branching structures. That mechanism can be divided into two main steps. The first step is the growth of a relatively large cluster (of a component that makes up the branching phase) on the substrate during the initial growth stages. The second step is the division process of that large cluster into smaller clusters in the later growth stages. The model parameters influencing the growth conditions that lead to the formation mechanism of the branching structures were determined, and their influences on the phase structure were analyzed. [ABSTRACT FROM AUTHOR]

Abstract The processes of phase separation and surface segregation which take place during two-component nanocomposite Metal:Carbon thin film growth are analyzed. The mathematical model is proposed which includes the processes of adsorption, phase separation, surface segregation, surface and bulk diffusion. The process of phase separation is described using Cahn-Hilliard equation and the process of surface segregation is described by Gibbsian segregation model. Diffusion in growing film is allowed to occur in a layer of an arbitrary thickness near the surface. The formations of metal clusters, columns or surface layer in matrixes of carbon are shown by the numerical simulations depending on thin film growth conditions. The influence of film composition and deposition temperature on film morphology is analyzed by the presented simulations. The simulation results are compared with experimental data taken from literature where C:Ni thin films were grown at different contents of Ni and substrate temperatures. The simulation results are in a good agreement with the corresponding experimental data. Graphical abstract Unlabelled Image Highlights • A model for phase separation and surface segregation during film growth is proposed. • Modeling results are consistent with experimental results of the C:Ni thin films. • Depending on conditions, model results exhibit layered, columnar, granular patterns. [ABSTRACT FROM AUTHOR]

Highlights: [•] Thin films structure depends on the ratio of diffusion coefficient over growth rate D/V. [•] At relatively high values of D/V simulated thin films exhibit a columnar structure. [•] At relatively low values of D/V simulated thin films exhibit a granular-like structure. [Copyright &y& Elsevier]

The morphology of aluminum co-doped scandium stabilized zirconia (ScAlSZ) thin films formed by e-beam deposition system was investigated experimentally and theoretically. The dependencies of surface roughness, and the films' structure on deposition temperature and deposition rate were analyzed. It was shown experimentally that the dependence of the surface roughness on deposition temperature and deposition rate was not monotonic. Those dependencies were analyzed by mathematical modeling. The mathematical model includes the processes of phase separation, adsorption and diffusion process due to the film surface curvature. The impacts of substrate temperature, growth rate on surface roughness of thin films and lateral nanoparticle sizes are shown by the modeling results. Modeling showed that the roughness of the surface of grown films became higher in most cases as the substrate's temperature rose, but the higher deposition rate resulted in lower surface roughness in most cases. The results obtained by simulations were compared to the relevant experimental data. The non-linear relationships between surface roughness of grown films and lateral size of nanoparticles were also shown by our modeling results, which suggested that the variation in the surface roughness depending on the substrate temperature and growth rate was related to the lateral size of nanoparticles. [ABSTRACT FROM AUTHOR]

In this work analysis considering Ni:C thin films growth on thermaly oxidized Si substrate by proposed kinetic model is presented. Model is built considering experimental results where microstructure evolution as a function of the substrate temperature and metal content of Ni:C nanocomposite films grown by hyperthermal ion deposition is investigated. The proposed kinetic model is based on the rate equations and includes processes of adsorption, surface segregation, diffusion, chemical reactions of constituents. The experimental depth profile curves were fitted by using proposed model. The obtained results show a good agreement with experiment taking into account concentration dependent diffusion. It is shown by modeling that with the increase of substrate temperature the process of nickel surface segregation becomes most important. [ABSTRACT FROM AUTHOR]

The dependences of the surface roughness and the phase structure of compound thin films on substrate temperature and flux of incoming particles are investigated by a proposed mathematical model. The model, which describes physically deposited thin compound film growth process is based on the Cahn–Hilliard equation and includes processes of phase separation, adsorption, and diffusion. In order to analyze large temperature range and assuming deposition of energetic particles, the diffusion is discriminated into thermal diffusion, radiation-enhanced diffusion, and ion beam mixing. The model is adapted to analyze surface roughness evolution during film growth. The influences of the substrate temperature and incoming flux particles on the surface roughness are determined by a series of numerical experiments. The modelling results showed that the surface roughness increased as the substrate temperature rose. Besides, a similar relationship was discovered between substrate temperature and size of nanoparticles formed in binary films, so the increase in the surface roughness with the substrate temperature was attributed to the increase in size of nanoparticles. [ABSTRACT FROM AUTHOR]

In the present paper, the formation of columnar and layered structure during co-deposition of binary thin films is analyzed by kinetic modeling. The kinetic model is based on phase field theory and involves the main processes taking place during binary film growth: adsorption, phase separation, Gibbsian surface segregation, surface and bulk diffusion. The process of phase separation is defined by the Cahn–Hilliard equation, which describes well the kinetics of formation of nanoparticles in binary system with a limited solubility of components. The formation of columns and layers can occur only if other processes such as diffusion and segregation take place. In this paper, the most attention is paid to the formation of multilayered structures during binary components co-deposition, which is experimentally observed, but whose mechanism of formation is not well understood. In the work presented, the mechanism of formation of layers is shown, and the conditions at which this mechanism starts to work are formulated. It is shown that very important aspects are surface segregation of one of the components and depth dependent diffusion. [ABSTRACT FROM AUTHOR]