Machine Learning for Hybrid Line Stability Ranking Index in Polynomial Load Modeling under Contingency Conditions

In the conventional technique,in the evaluation of the severity index,clustering and loading suffer from more iteration leading to more com-putational delay.Hence this research article identifies,a novel progression for fast predicting the severity of the line and clustering by incorporating machine learning aspects.The polynomial load modelling or ZIP(constant impedances(Z),Constant Current(I)and Constant active power(P))is developed in the IEEE-14 and Indian 118 bus systems considered for analysis of power system security.The process of finding the severity of the line using a Hybrid Line Stability Ranking Index(HLSRI)is used for assisting the concepts of machine learning with J48 algorithm,infers the superior affected lines by adopting the IEEE standards in concern to be compensated in maintaining the power system stability.The simulation is performed in the WEKA environment and deals with the supervisor learning in order based on severity to ensure the safety of power system.The Unified Power Flow Controller(UPFC),facts devices for the purpose of compensating the losses by maintaining the voltage characteristics.The finite element analysis findings are compared with the existing procedures and numerical equations for authentications.

Contingency management strategies of the Nursing Department in centralized rescue of patients with coronavirus disease 2019

Objectives:This article aims to summarize a series of contingency management strategies of the Nursing Department in the centralized treatment of patients with coronavirus disease 2019(COVID-19).Methods:The strategies of the Nursing Department included an early warning for prevention and control,taking functions of vertically commanding and horizontally coordinating,and reasonably allocating nursing workforce,to facilitate centralized treatment work in the in-hospital fever clinic,isolation wards and ICU,and referral and admission of critical patients.Five special groups were established in charge of training and examination,management and supervision,psychological support,logistical support,and reporting and publicity,respectively.Results:It was achieved that no deaths from critical patients and no medical staff,no other patients were infected.Conclusion:Through the implementation of these strategies,safe and efficient centralized treatment was ensured timely,orderly and sustainably.

An Extended Bivariate T-Distribution Type Symmetry Model for Square Contingency Tables

The purpose of this paper is to propose a new model of asymmetry for square contingency tables with ordered categories. The new model may be appropriate for a square contingency table if it is reasonable to assume an underlying bivariate t-distribution with different marginal variances having any degrees of freedom. As the degrees of freedom becomes larger, the proposed model approaches the extended linear diagonals-parameter symmetry model, which may be appropriate for a square table if it is reasonable to assume an underlying bivariate normal distribution. The simulation study based on bivariate t-distribution is given. An example is given.

Sizing of STATCOM to Enhance Voltage Stability of Power Systems for Normal and Contingency Cases

The electric power infrastructure that has served huge loads for so long is rapidly running up against many limitations. Out of many challenges it is to operate the power system in secure manner so that the operation constraints are fulfilled under both normal and contingent conditions. Smart grid technology offers valuable techniques that can be deployed within the very near future or which are already deployed nowadays. Flexible AC Transmission Systems (FACTS) devices have been introduced to solve various power system problems. In literature, most of the methods proposed for sizing the FACTS devices only consider the normal operating conditions of power systems. Consequently, some transmission lines are heavily loaded in contingency case and the system voltage stability becomes a power transfer-limiting factor. This paper presents a technique for determining the proper rating/size of FACTS devices, namely the Static Synchronous Compensator (STATCOM), while considering contingency cases. The paper also verifies that the weakest bus determined by eigenvalue and eigenvectors method is the best location for STATCOM. The rating of STATCOM is specified according to the required reactive power needed to improve voltage stability under normal and contingency cases. Two case system studies are investigated: a simple 5-bus system and the IEEE 14-bus system. The obtained results verify that the rating of STATCOM can be determined according to the worst contingency case, and through proper control it can still be effective for normal and other contingency cases.

Problem-Based Learning of Drug Use and Abuse during COVID-19 Contingency

Introduction: Nursing students’ experiences during the pandemic provoked social isolation, the way to learn and every context increasing their stress and anxiety leading to drug use and abuse, among others. Problem-based learning (PBL) is a pedagogic strategy to strengthen significant learning;then the objective was to establish PBL influence in nursing students’ experiences on drug use and abuse during COVID-19 contingency. Methods: Qualitative, phenomenological and descriptive paradigm, 12 female and male nursing students aged 20 - 24 years old from the 5th and 6th semesters participated. Information collection was through semi-structured interview and a deep one in four cases. A guide of questions about: How the pandemic impacted your life? How did you face it? And what did you learn during this process? Those questions were used. Qualitative data analysis was based on De Souza Minayo, and signed informed consent was obtained from participants. Results: Students’ experiences allowed four categories to emerge, with six sub-categories. Category I. Students’ experiences on drug use and abuse facing the sanitary contingency;Category II. Students’ skills development to identify a problem and design of appropriate solutions;Category III. Developing skills to favor interpersonal relationships;Category IV. Influence of PBL in nursing students’ experiences on drug use and abuse during the COVID-19 contingency. Conclusion: PBL favored analysis and thoughts in nursing students’ experiences on drug use and abuse during the COVID-19 contingency, they worked collaboratively, developed resilience to daily life situations, and implemented stress coping strategies with their significant learning, which diminished their risk behavior.

Marine oil spill contingency planning

According to the practice researching and formulating “The Oil Spill Contingency Plan of South Chinese Sea”, this paper analyses and discusses the structure, functions and main contents of marine oil spill contingency planning, programs the organizing and commanding system and emergency response system, and advances the planning and researching method to coordinate comprehensively and to design practically the detailed emergency response steps until to formulate the ease operating programs for the plan implementation(PPI) and the PPI to apply high techniques supporting emergency administrations and response.

Extended Diagonal Exponent Symmetry Model and Its Orthogonal Decomposition in Square Contingency Tables with Ordered Categories

For square contingency tables with ordered categories, this article proposes new models, which are the extension of Tomizawa’s [1] diagonal exponent symmetry model. Also it gives the decomposition of proposed model, and shows the orthogonality of the test statistics for decomposed models. Examples are given and the simulation studies based on the bivariate normal distribution are also given.

Asymmetry Index on Marginal Homogeneity for Square Contingency Tables with Ordered Categories

For square contingency tables with ordered categories, the present paper considers two kinds of weak marginal homogeneity and gives measures to represent the degree of departure from weak marginal homogeneity. The proposed measures lie between –1 to 1. When the marginal cumulative logistic model or the extended marginal homogeneity model holds, the proposed measures represent the degree of departure from marginal homogeneity. Using these measures, three kinds of unaided distance vision data are analyzed.

A Unified Approach for the Multivariate Analysis of Contingency Tables

We present a unified approach to describing and linking several methods for representing categorical data in a contingency table. These methods include: correspondence analysis, Hellinger distance analysis, the log-ratio alternative, which is appropriate for compositional data, and the non-symmetrical correspondence analysis. We also present two solutions working with cummulative frequencies.

A Multivariate Test for Three-Factor Interaction in 3-Way Contingency Table under the Multiplicative Model

Two test statistics that have been commonly used in analysing interactions in contingency table are the Pearson’s Chi-square statistic, χ2, and likelihood ratio test statistic, G2. Both test statistics, in tables with sufficiently large sample size, have an asymptotic chi-square distribution with degrees of freedom (df) equal to the number of free parameters in the saturated model. For example under the hypothesis of independence of the row and column conditioned on the layer in an I × J × K contingency table, the df is K(I –1)(J– 1). These test statistics, in large sized tables, will have less power since they have large degrees of freedom. This paper proposes a product effect model, which combines the advantages of the multiplicative models over the additive, for analysing the interaction between the row and column of the 3-way table conditioned on the layer. The derived statistics is shown to be asymptotically chi-square with a small degree of freedom, K?– 1, for the I × J × K contingency table. The performance of the developed statistic is compared with the Pearson’s chi-square statistic and the likelihood ratio statistic test using an illustrative example. The results show that the product effect test can detect interaction even when some of the main effects are not significant and can perform better than the other competitors having smaller degree of freedom in large sized tables.

Comparative Analysis of Hybrid Controllers of Done Systems (UPFC) and Interphase Power Regulators Type RPI 30p15 on Contingency Management in Electrical Networks

The aim of this work is to demonstrate that interphase power regulators (IPR) bring new and interesting ultra-solutions that complement those already taken into account by the FACTS (Flexible Alternative Transmission System) in the resolution of the problems related to the power flow in the AC transmission networks. In order to facilitate the understanding of this work, a comparative study of the performances of the two technologies between the UPFC (Unified Power Flow Controller) and RPI was carried out and at the end of which we were able to highlight the preponderance of RPI compared to the UPFC in the bypassing of the short-circuit fault insofar as the latter allows, in particular, an increase in the transformation capacity without an increase in the level of the short-circuit. The decoupled watt-var method has been used to control the UPFC while the RPI is controlled by phase shift. The simulation results are obtained in the Matlab Simulink environment and show the flexibility of the RPI compared to the UPFC in limiting strong contingencies.

A Steady-State Contingency Analysis of the SADC Regional Grid Using the N-1 Criterion

Southern Africa has experienced electric power deficits over the last decade. This has been due in part to the member countries＇ inadequate electrical power supply system, as well as load growth in areas which were not adequately planned for. This has induced the formation of organizations such as SADC （Southern African Development Community） and SAPP （Southern African Power Pool） that have the common goal of achieving development and economic growth in the region which comprises of 15 member countries. This paper presents results from a security analysis of the region＇s electric power supply system using a baseline level of performance. This was carried out by performing a steady-state contingency analysis on a SADC power network model subject to the N-1 criteria which expresses the ability of the power network to experience a contingency without causing an overload or failure in any other part of the network. Simulations were carried out using DigSilent.

A novel collapse prediction index for voltage stability analysis and contingency ranking in power systems

Voltage instability is a serious phenomenon that can occur in a power system because of critical or stressed condi-tions.To prevent voltage collapse caused by such instability,accurate voltage collapse prediction is necessary for power system planning and operation.This paper proposes a novel collapse prediction index(NCPI)to assess the volt-age stability conditions of the power system and the critical conditions of lines.The effectiveness and applicability of the proposed index are investigated on the IEEE 30-bus and IEEE 118-bus systems and compared with the well-known existing indices(Lmn,FVSI,LQP,NLSI,and VSLI)under several power system operations to validate its practicability and versatility.The study also presents the sensitivity assumptions of existing indices and analyzes their impact on voltage collapse prediction.The application results under intensive case studies prove that the proposed index NCPI adapts to several operating power conditions.The results show the superiority of the proposed index in accurately estimating the maximum load-ability and predicting the critical lines,weak buses,and weak areas in medium and large networks during various power load operations and contingencies.A line interruption or generation unit outage in a power system can also lead to voltage collapse,and this is a contingency in the power system.Line and generation unit outage contingencies are examined to identify the lines and generators that significantly impact system stability in the event of an outage.The contingencies are also ranked to identify the most severe outages that significantly cause voltage collapse because of the outage of line or generator.

Hybrid Physics and Data-driven Contingency Filtering for Security Operation of Micro Energy-water Nexus

This paper investigates a novel engineering problem,i.e.,security-constrained multi-period operation of micro energywater nexuses.This problem is computationally challenging because of its high nonlinearity,nonconvexity,and large dimension.We propose a two-stage iterative algorithm employing a hybrid physics and data-driven contingency filtering(CF)method and convexification to solve it.The convexified master problem is solved in the first stage by considering the base case operation and binding contingencies set(BCS).The second stage updates BCS using physics-based data-driven methods,which include dynamic and filtered data sets.This method is faster than existing CF methods because it relies on offline optimization problems and contains a limited number of online optimization problems.We validate effectiveness of the proposed method using two different case studies:the IEEE 13-bus power system with the EPANET 8-node water system and the IEEE 33-bus power system with the Otsfeld 13-node water system.

Contingency Reserve Evaluation for Fast Frequency Response of Multiple Battery Energy Storage Systems in a Large-scale Power Grid

Recently,the fast frequency response(FFR)service by large-scale battery energy storage systems(BESSs)has been successfully proved to arrest the frequency excursion during an unexpected power outage.However,adequate frequency response relies on proper evaluation of the contingency reserve of BESSs.The BESS FFR reserve is commonly managed under fixed contracts,ignoring various response characteristics of different BESSs and their coexisting interactions.This paper proposes a new methodology based on dynamic grid response and various BESS response characteristics to optimise the FFR reserves and prevent the frequency from breaching the under-frequency load shedding(UFLS)thresholds.The superiority of the proposed method is demonstrated to manage three large-scale BESSs operating simultaneously in an Australian power grid under high renewable penetration scenarios.Further,the proposed method can identify remaining battery power and energy reserve to be safely utilised for other grid services(e.g.,energy arbitrage).The results can provide valuable insights for integrating FFR into conventional ancillary services and techno-effective management of multiple BESSs.

A contingency-aware method for N-2 security-constrained transmission expansion planning

In this paper,a novel contingency-aware method for N-2 security-constrained transmission expansion planning is proposed.To ensure that the transmission construction plan satisfies the N-2 security criterion,the proposed method takes advantage of the adjustable robust optimization(ARO)framework and upgrades it.We construct a discrete uncertainty set in which component failures are treated as uncertain events that are handled as binary variables.In addition to the failure of existing lines and generators,we explicitly model the failure of candidate lines.The proposed model comprises a master problem that makes the transmission construction decision,and a series of subproblems that can detect not only the worst contingency,but also the potential contingencies.Computational studies on the IEEE RTS 24-bus and IEEE 118-bus test systems are carried out to validate the effectiveness of the proposed method.Compared with the deterministic method and ARO method in the literature,the proposed method has higher computational efficiency.

Large-scale branch contingency analysis through master/slave parallel computing

Contingency analysis(CA)requires fast execution time for real-time power system operations.Because CA problems can naturally be divided into separate subtasks,parallel computing helps to speed up the computation time.This paper proposes a master/slave parallel computing architecture and studies the computation of CA in a large-scale power system through high performance computing,adopting a message passing interface for implementation.In particular,although the execution time of CA varies,there is a tradeoff between having an imbalanced workload and"paying"a synchronization penalty for parallel computing:either factor blocks the progress of scalability.The proposed layered dynamic scheduling method is effective to tackle the challenge of high synchronization cost and workload imbalance and have the potential to further scale for the N-2 contingency analysis.

Techno-economic Analysis of Contingency Reserve Allocation Scheme for Combined UHV DC and AC Receiving-End Power System

In a UHV DC and AC combined system the UHVDC’s blocking fault becomes the most serious load balance contingency of the receiving end power system due to its large capacity.The amount of contingency reserve thus is largely increased.This paper proposes three distinct schemes for allocating contingency reserve to cover the power shortage caused by UHVDC’s blocking fault,and compares the economic cost of these schemes.An operation simulation method using a unit commitment technique is proposed for evaluating the operation costs associated with increasing contingency reserve.A real case study for a Jiangsu Province power system in China is presented to demonstrate that the best scheme is to share the contingency reserve with neighborhood power systems through the transmission capacity of UHVAC lines.

Development and Social Implementation of Smartphone App Nige-Tore for Improving Tsunami Evacuation Drills: Synergistic Effects Between Commitment and Contingency

This research explored how we can improve tsunami evacuation behavior,which has been a major social issue since the 2011 Great East Japan Earthquake and Tsunami.We introduce Nige-Tore,a smartphone app for supporting tsunami evacuation drills,which was developed within an interdisciplinary research framework.Nige-Tore serves as an effective interface tool that successfully visualizes the dynamic interactions between human actions(evacuation behavior)and natural phenomena(tsunami behavior).Drill participants can check,on their smartphone,the estimated inundation area of the approaching tsunami,along with their own current evacuation trajectory.The results of real-world trials using NigeTore show that the app is more powerful than conventional devices and methods that have been used in tsunami evacuation training,such as hazard maps and traditional drills that do not make use of any apps,because Nige-Tore provides an interface that enables commitment and contingency thinking—which at first glance appear to represent different orientations—to not only coexist but to synergize.‘‘Commitment’’(devotion or involvement)refers to the act of immersing oneself in and viewing as absolute one particular scenario or its potential to be actualized,given conditions in which infinite scenarios may be actualized,depending on the interactions between human systems and natural systems.‘‘Contingency’’thinking(an accidental or incidental state)refers to the act of relativizing and separating oneself from any particular scenario or its potential to be actualized,given the same conditions.The synergistic effect of‘‘commitment’’and‘‘contingency’’thinking also expands people’s capacity to cope with unexpected and unforeseen events.

MODEL SELECTION FOR LOG-LINEAR MODELS OF CONTINGENCY TABLES

In this paper, we propose an information-theoretic-criterion-based modelselection procedure for log-linear model of contingency tables under multinomial sampling, andestablish the strong consistency of the method under some mild conditions. An exponential bound ofmiss detection probability is also obtained. The selection procedure is modified so that it can beused in practice. Simulation shows that the modified method is valid. To avoid selecting the penaltycoefficient in the information criteria, an alternative selection procedure is given.