scholarly journals Control of Reliability of Measurements in Power Systems According to the First Increment and on the Basis of Extrapolating Filters

2018 ◽  
Vol 61 (5) ◽  
pp. 423-431 ◽  
Author(s):  
V. A. Anishchenko ◽  
T. V. Pisaruk
Keyword(s):  
Power Systems ◽  
Power Equipment ◽  
Limit Values ◽  
Logic Control ◽  
Process Control Systems ◽  
Reliability Control ◽  
Incorrect Measurement ◽  
The Difference ◽  
Reliability Of Operation ◽  
Lower Limits

Reliability of operation of power systems is determined by reliability of the power equipment, and reliability of the measuring information characterizing a condition of power equipment and the technological processes of generation, transfer, distribution and consumption of energy proceeding in it. Unreliable information causes errors in the diagnosis of equipment malfunctions, improper operation of process control systems and reduction the operational technical and economic performance of power systems. Along with the methods of hardware control of the reliability of measurements using digital codes, there are methods of software and logic control based on the technological meaning of the measured data, their logical consistency and consistency. Control of reliability of measurements by limit values is often applied when the result of measurement of a variable is compared with its known upper and lower limits of reliable values. The resolution of the control by limit values is sharply decreased with the expansion of the range of reliable values. The article deals with the reliability control based on the analysis of the rate of alteration of the controlled variables. At control in accordance with the first increments, the first increment, i.e. the difference of results of measurements in the current and previous moments of time is compared with the known range of the first increments of reliable results of measurements. Control in accordance with the first increments is most effective in cases where the controlled processes are sufficiently inertial and the rate of alteration of variables is relatively small. The resolution of the control by the first increment can be enhanced through the use of extrapolation filters. In this case, the current measured value of the variable is compared with its extrapolated value at the previous time and the result of the comparison reveals an incorrect measurement result.

scholarly journals Protecting power equipment against magnetohydrodynamic effects (MHD) of electromagnetic pulses (EMP)

2015 ◽  
Vol 12 (3) ◽  
pp. 321-332
Author(s):  
Vladimir Gurevich
Keyword(s):  
Power Systems ◽  
Power System ◽  
Electrical Equipment ◽  
Power Equipment ◽  
Electromagnetic Pulses ◽  
Effective Measure ◽  
Solar Storm ◽  
Induced Currents ◽  
The Difference ◽  
Technical Measures

The article is devoted to the effects of geomagnetic-induced currents (GIC) on electrical equipment of power systems and analyzes technical measures for protection against such effects. It is noted that the difference between highaltitude nuclear detonation and solar storm GICs forces applying different methods of electrical equipment protection. It also illustrates that enhancement of transformer immunity to GICs without saturation prevention is not an effective measure to protect the power system. The article offers a special relay designed for fast disconnection of the transformer under GICs.

scholarly journals The IG- file use to Gauge the Apical Diameter in Endodontics: An In Vitro Study

2018 ◽  
Vol 12 (1) ◽  
pp. 638-646 ◽  
Author(s):  
Massimo Amato ◽  
Alfredo Iandolo ◽  
Giuseppe Pantaleo ◽  
Dina Abtellatif ◽  
Michele Simeone ◽  
...  
Keyword(s):  
Measurement Accuracy ◽  
Reference Value ◽  
In Vitro Study ◽  
Vitro Study ◽  
Root Canals ◽  
New Instrument ◽  
Clinician Experience ◽  
Incorrect Measurement ◽  
The Difference

Aim: The aim of this study was to evaluate the efficacy of the IG-file, a new instrument designed for apical diameter gauging. Materials and Methods: After shaping with F1 Universal Protaper, 60 roots were randomly divided into two groups and assigned to two operators, One Expert in Endodontics (EO) and One Unexpert (UO). In each sample, after canal curvatures have been detected, the apical diameters were measured with the IG-file and the K-NiTi. The results were compared with the reference value obtained by retrograde apical gauging. The data were statistically analyzed. Results: Among 60 samples, 10% of errors were recorded when the IG-files were used; in the K-NiTi group the incorrect measurements were 70%. In both groups (expert and unexpert) the IG-file measurements were more accurate than the K-NiTi (90 vs 33 and 90 vs 26,7). The differences were statistically significant. In curved canals, the difference between measurement rates performed with both instruments was statistically significant (85,7% IG-file vs 28,6% K-NiTi) as well as for the samples without curvatures (92,3% IG file vs 30,8% NiTi file). In root canals without curvatures overestimation errors in K-NiTi file group are more frequent than underestimation errors. This difference was statistically significant. Conclusion: A proper gauging of the apical diameter has a key role in endodontic therapy; an incorrect measurement can lead to clinical failures. This “in vitro” study highlights that IG-file improves measurement accuracy independently from clinician experience. Furthermore, in curved canals, the IG-file is more accurate than K-NiTi.

scholarly journals Comparative Legal Analysis of the Systems of Executive Power in Russia and Japan

2020 ◽  
Vol 15 (9) ◽  
pp. 195-205
Author(s):  
A. A. Vayno
Keyword(s):  
Power Systems ◽  
Legal Aspects ◽  
Executive Power ◽  
Primary Role ◽  
Legal Analysis ◽  
Head Of State ◽  
Significant Difference ◽  
Legal Nature ◽  
Statics And Dynamics ◽  
The Difference

The paper is devoted to the comparative legal aspects of the study of executive power systems in Russia and Japan. These states, despite the significant difference in both the political and legal historical path and modern forms of government and state structure, have a number of common constitutional and legal features. Both countries have chosen a legal strategy aimed at the full-fledged building of a democratic rule of law. Comparison of executive-power systems reveals both serious similarities and significant differences in the statics and dynamics of their daily functioning. If in Russia ministers perform rather an administrative and managerial function and are actually deprived of many of their own political prerogatives, in Japan the top officials of ministries are, as a rule, public politicians. The difference also lies in the procedure for appointing heads of executive departments — in Russia in this process, the primary role is assigned to the personal will of the elected head of state, in Japan — to the collective will of the elite, self-organizing and legitimized through parliamentary elections. At the same time, a number of common features correspond to the governments of these countries, both in terms of their legal nature and in terms of their functions. These circumstances indicate the need to intensify comparative legal research in this direction in order to clarify questions about the further expediency of the mutual reception of norms and institutions related to the corresponding public law orders.

Multifractal Analysis of Daily Global Horizontal Radiation in Complex Topography Island: La Reunion as a Case Study

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Miloud Bessafi ◽  
Vishwamitra Oree ◽  
Abdel Anwar Hossen Khoodaruth ◽  
Guillaume Jumaux ◽  
François Bonnardot ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Power Systems ◽  
Small Island ◽  
Spatial And Temporal Variability ◽  
Reunion Island ◽  
Island States ◽  
Energy Technologies ◽  
Solar Radiation Incident ◽  
Réunion Island ◽  
The Difference

An accurate assessment of the amount solar radiation incident at specific locations is highly complex due to the dependence of available solar radiation on many meteorological and topographic parameters. Reunion Island, a small tropical French territory, intends to deploy solar energy technologies rapidly. In this context, the variability and intermittency of solar irradiance in different regions of the island is of immediate interest if the generated energy will be integrated in the existing energy network. This paper identifies different features of spatial and temporal variability of daily global horizontal irradiance (GHI) observed on Reunion Island. For this purpose, trends in the mean daily as well as seasonal variability of GHI were investigated. Furthermore, the intermittency and multifractal behaviors of the spatial daily GHI change were examined. Analyzing this daily variability is crucial to day-ahead forecasting of solar resource for better managing solar integration in the power grid, particularly in small island states with isolated power systems. Results revealed that the difference in cumulative GHI for two successive days ranges between −10 and 10 kW/m2/day while the highest and lowest variability of daily change occurs during summer and winter, respectively. The decorrelation distance, which gives a measure of the distance over which the variability at distinct geographic locations become independent of one another at a given timescale, was also calculated. It was found that the average decorrelation distance for day-to-day GHI change is about 22 km, a smaller value than that calculated by the previous studies using much sparser radiometric networks. The Hurst exponent, fractal co-dimension, and Lévy parameter, which describe solar radiation intermittency, were also evaluated for Reunion Island.

scholarly journals Stripped-envelope core-collapse supernova 56Ni masses

2020 ◽  
Vol 641 ◽  
pp. A177 ◽  
Author(s):  
N. Meza ◽  
J. P. Anderson
Keyword(s):  
Systematic Errors ◽  
Power Source ◽  
Radioactive Material ◽  
Estimation Methods ◽  
Core Collapse ◽  
Core Collapse Supernova ◽  
Explosion Mechanism ◽  
The Difference ◽  
Uniform Manner ◽  
Lower Limits

Context. The mass of synthesised radioactive material is an important power source for all supernova (SN) types. In addition, the difference of 56Ni yields statistics are relevant to constrain progenitor paths and explosion mechanisms. Aims. Here, we re-estimate the nucleosynthetic yields of 56Ni for a well-observed and well-defined sample of stripped-envelope SNe (SE-SNe) in a uniform manner. This allows us to investigate whether the observed hydrogen-rich–stripped-envelope (SN II–SE SN) 56Ni separation is due to real differences between these SN types or because of systematic errors in the estimation methods. Methods. We compiled a sample of well-observed SE-SNe and measured 56Ni masses through three different methods proposed in the literature: first, the classic “Arnett rule”; second the more recent prescription of Khatami & Kasen (2019, ApJ, 878, 56) and third using the tail luminostiy to provide lower limit 56Ni masses. These SE-SN distributions were then compared to those compiled in this article. Results. Arnett’s rule, as previously shown, gives 56Ni masses for SE-SNe that are considerably higher than SNe II. While for the distributions calculated using both the Khatami & Kasen (2019, ApJ, 878, 56) prescription and Tail 56Ni masses are offset to lower values than “Arnett values”, their 56Ni distributions are still statistically higher than that of SNe II. Our results are strongly driven by a lack of SE-SN with low 56Ni masses, that are, in addition, strictly lower limits. The lowest SE-SN 56Ni mass in our sample is of 0.015 M⊙, below which are more than 25% of SNe II. Conclusions. We conclude that there exist real, intrinsic differences in the mass of synthesised radioactive material between SNe II and SE-SNe (types IIb, Ib, and Ic). Any proposed current or future CC SN progenitor scenario and explosion mechanism must be able to explain why and how such differences arise or outline a bias in current SN samples yet to be fully explored.

Reducing the Impact of Source Information Uncertainty in Intelligent Automated Thermal Process Control Systems in Ensuring Reliable Operation of Power Equipment

Vestnik MEI ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 78-87
Author(s):  
Edik K. Arakelyan ◽  
◽  
Ivan A. Shcherbatov ◽  
Keyword(s):  
Control System ◽  
Process Control ◽  
Control Systems ◽  
Process Control System ◽  
Power Equipment ◽  
Source Information ◽  
Equipment Operation ◽  
Process Control Systems ◽  
Automated Process ◽  
The Impact

The uncertainty of the source information is used to solve key tasks in an intelligent automated thermal process control system affects the calculation of control actions, the implementation of equipment optimal operating modes and, as a result, leads to degraded reliability. As a rule, this type of information can be qualitative (the use of expert knowledge) or quantitative in nature. In this regard, it is extremely important to reduce the impact of uncertainty. The aim of the study is to identify the types and origins of uncertainty in the source information used by an intelligent automated process control system and to develop approaches to reduce its impact on the reliability of power equipment operation. The approaches used to ensure the specified indicators of reliability, efficiency and environmental friendliness in modern intelligent automated process control systems are based on predictive strategies, according to which the technical condition of equipment and specific degradation processes are predicted. This means that various types of uncertainty can have a significant negative impact. To reduce the influence of uncertainty of the initial information that affects the reliability of power equipment operation, the use of artificial neural networks is proposed. Their application opens the possibility to predict the occurrence of equipment defects and failures based on retrospective data for specified forecast time intervals. A method for reducing the impact of anomalies contained in the source information used in an intelligent process control system for energy facilities is demonstrated. Data omissions and outliers are investigated, the elimination of which reduces the impact of uncertainty and improves the quality of solving key problems in intelligent automated process control systems. Experimental studies were carried out that made it possible to identify the mathematical methods for removing omissions and anomalies in the source information in the best way. Methodological aspects of eliminating various types of uncertainty that exist in managing of power facilities by means of intelligent automated process control systems at the key stages of the power equipment life cycle are described.

scholarly journals Limiting Values and Functional and Difference Equations

Mathematics ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 407 ◽  
Author(s):  
N.-L. Wang ◽  
Praveen Agarwal ◽  
S. Kanemitsu
Keyword(s):  
Difference Equations ◽  
Functional Equations ◽  
Boundary Behavior ◽  
Special Functions ◽  
Asymptotic Formulas ◽  
Limit Values ◽  
Summatory Function ◽  
The Difference ◽  
Limiting Values ◽  
Mathematics And Science

Boundary behavior of a given important function or its limit values are essential in the whole spectrum of mathematics and science. We consider some tractable cases of limit values in which either a difference of two ingredients or a difference equation is used coupled with the relevant functional equations to give rise to unexpected results. As main results, this involves the expression for the Laurent coefficients including the residue, the Kronecker limit formulas and higher order coefficients as well as the difference formed to cancel the inaccessible part, typically the Clausen functions. We establish these by the relation between bases of the Kubert space of functions. Then these expressions are equated with other expressions in terms of special functions introduced by some difference equations, giving rise to analogues of the Lerch-Chowla-Selberg formula. We also state Abelian results which not only yield asymptotic formulas for weighted summatory function from that for the original summatory function but assures the existence of the limit expression for Laurent coefficients.

scholarly journals Modeling and Stability Analysis of Parallel Inverters in Island Microgrid

Electronics ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 463 ◽  
Author(s):  
Xiaohuan Wang ◽  
Hongyang Qing ◽  
Peng Huang ◽  
Chunjiang Zhang
Keyword(s):  
Parallel System ◽  
Open Loop ◽  
Power Equipment ◽  
Control Methods ◽  
Impedance Model ◽  
Loop Transfer Function ◽  
Impedance Modeling ◽  
The Difference ◽  
Output Characteristics ◽  
The Stability

The island microgrid is composed of a large number of inverters and various types of power equipment, and the interaction between inverters with different control methods may cause system instability, which will cause the power equipment to malfunction. Therefore, effective methods for analyzing the stability of the microgrid system have become particularly important. Generally, impedance modeling methods are used to analyze the stability of power electronic converter systems. In this paper, the impedance models of a PQ-controlled inverter and droop-controlled inverter are established in d-q frame. In view of the difference of output characteristics between the two control methods, the island microgrid is equivalent to a double closed-loop system. The impedance model of the parallel system is derived and the open loop transfer function of the system is extracted. Based on the generalized Nyquist criterion (GNC), the stability of parallel system working in island microgrid mode is analyzed using this proposed impedance model. The simulation and experiment results are presented to verify the analysis.

scholarly journals A Distributed AGC Method considering Two-Channel Random Delays and Their Difference between Interconnected Power Systems

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Xilin Zhao ◽  
Zhenyu Lin ◽  
Bo Fu ◽  
Yang Yang ◽  
Jimin Ma
Keyword(s):  
Power Systems ◽  
Time Delays ◽  
Frequency Control ◽  
Control Variable ◽  
Automatic Generation ◽  
Control Sequence ◽  
Negative Effects ◽  
Random Load ◽  
Sequence Selection ◽  
The Difference

With the emergence of the concept of smart grid, the networked automatic generation control (AGC) method has been more and more important for secondary frequency control due to its characteristics such as openness and flexibility. However, the networked AGC system also presents some defects such as time delays and packet dropouts. The existence of time delays makes the traditional AGC strategies more challenging. A novel AGC method is proposed in this paper to mitigate the negative effects of time delays. Firstly, a multiarea power system model is built under the consideration of two-channel time delays: from controller to actuator and from sensor to controller. More practically, the difference of delays between areas is also exhibited in the model. Thus, from the predictive characteristics of model predictive control (MPC), a method of selection with optimization is presented to obtain the appropriate control variable when delays exist. Furthermore, three cases, (a) no processing for delay, (b) control sequence selection, (c) control sequence selection with optimization, are analyzed. The frequency and area control error (ACE) performance are evaluated with step load perturbation and random load perturbation. The simulation results indicate that the system controlled by the proposed method has desired dynamic performances. Consequently, the feasibility and effectiveness of the proposed method are verified.

scholarly journals Digital Twins-Assisted Design of Next-Generation Advanced Controllers for Power Systems and Electronics: Wind Turbine as a Case Study

Inventions ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 19 ◽  
Author(s):  
Meisam Jahanshahi Zeitouni ◽  
Ahmad Parvaresh ◽  
Saber Abrazeh ◽  
Saeid-Reza Mohseni ◽  
Meysam Gheisarnejad ◽  
...  
Keyword(s):  
Power Systems ◽  
Wind Turbine ◽  
Dynamic Performance ◽  
Adaptive Controller ◽  
Fitness Evaluation ◽  
Digital Twin ◽  
Speed Error ◽  
Policy Gradient ◽  
The Difference ◽  
Output Behavior

This paper proposes a novel adaptive controller based on digital twin (DT) by integrating software-in-loop (SIL) and hardware-in-loop (HIL). This work aims to reduce the difference between the SIL controller and its physical controller counterpart using the DT concept. To highlight the applicability of the suggested methodology, the regulation control of a horizontal variable speed wind turbine (WT) is considered for the design and assessment purposes. In the presented digital twin framework, the active disturbance rejection controller (ADRC) is implemented for the pitch angle control of the WT plant in both SIL and HIL environments. The design of the ADRC controllers in the DT framework is accomplished by adopting deep deterministic policy gradient (DDPG) in two stages: ( i ) by employing a fitness evaluation of wind speed error, the internal coefficients of HIL controller are adjusted based on DDPG for the regulation of WT plant, and ( ii ) the difference between the rotor speed waveforms in HIL and SIL are reduced by DDPG to obtain a similar output behavior of the system in these environments. Some examinations based on DT are conducted to validate the effectiveness, high dynamic performance, robustness and adaptability of the suggested method in comparison to the prevalent state-of-the-art techniques. The suggested controller is seen to be significantly more efficient especially in the compensation of high aerodynamic variations, unknown uncertainties and also mechanical stresses on the plant drive train.

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