Risk Assessment of Power System Transmission Network Based on Cascading Failure Chains

2018 ◽  
Vol 19 (1) ◽  
Author(s):  
Qiming Sun ◽  
Libao Shi ◽  
Yixin Ni ◽  
Dajun Si
Keyword(s):  
Risk Assessment ◽  
Risk Evaluation ◽  
Transient Stability ◽  
Search Strategy ◽  
Control Measures ◽  
Cascading Failure ◽  
System Control ◽  
Transmission Network ◽  
Failure Model ◽  
Subsequent Failure

AbstractThis paper aims to conduct the risk assessment of transmission network based on the search of cascading failure chains. Regarding the generalized cascading failure model with transient stability constraints, some significant improvements including the subsequent failure search strategy and the system control measures are proposed during analysis. Besides, the risk evaluation indices pertinent to the failure chains combined with the actual engineering requirements, and the failure level classification are elaborately derived and discussed. Finally, case studies are performed on a real-sized Chinese power grid to illustrate the validity of the proposed strategies and methods.

scholarly journals Occurrence and Toxicological Risk Evaluation of Organochlorine Pesticides from Suburban Soils of Kenya

2019 ◽  
Vol 16 (16) ◽  
pp. 2937 ◽  
Author(s):  
Teresiah M. Mungai ◽  
Jun Wang
Keyword(s):  
Risk Assessment ◽  
Gas Chromatography ◽  
Organochlorine Pesticides ◽  
Risk Evaluation ◽  
Control Measures ◽  
Cancer Risk Assessment ◽  
Risk Level ◽  
Toxicological Risk ◽  
And Control ◽  
Control Insect

The use of organic chemicals in agriculture and manufacturing has raised concerns about the dangers of organochlorine pesticides (OCPs) in the environment. By examining OCPs occurrence in the suburban soils from Kenya, this study revealed the distribution, concentrations, and the threat posed to the environment and human health. A gas chromatography electron capture detector was used to test the pesticides. The hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT) studied in soils of Kapsabet, Voi, and Nyeri towns showed concentrations ranging from 0.03–52.7, 0.06–22.3, and 0.24–24.3 ng/g respectively. The highest concentration of HCHs was in Kapsabet (0.03–48.1 ng/g), whereas the highest DDTs concentration was in Voi (n.d.–15.5 ng/g). Source identification revealed OCPs pollution originated from recent usage of DDT pesticides to control insect-borne diseases and from the use of lindane in agriculture. Correlation test revealed that total organic carbon influenced the presence of pesticides in the soils. The enantiomeric ratios of α-HCH/γ-HCH were <3 indicating the use of lindane while the ratios of DDE/DDT were <1 suggesting recent input of DDT. The cancer risk assessment showed values close to the set risk level of 10−6, suggesting the likelihood of exposure to cancer was not low enough, and control measures need to be established.

Power System Transient Stability Assessment Based on Critical Cutset Transient Stability Available Capacity

2014 ◽  
Vol 615 ◽  
pp. 80-83
Author(s):  
Ke Wang ◽  
Da Hai You ◽  
Ceng Long ◽  
Peng Xu ◽  
Ling Ling Pan ◽  
...  
Keyword(s):  
Power System ◽  
Transient Stability ◽  
Stability Margin ◽  
Control Measures ◽  
System Control ◽  
Prevention Measures ◽  
Power System Control ◽  
Transient Energy Function ◽  
Transient Energy ◽  
Fault Clearance

Aiming at the disadvantages of converting traditional transient stability margin into power system control measures, this paper proposes a new transient stability margin characterization method based on critical cutset transient stability available capacity (TATC). Compared with traditional transient stability margin based on fault clearance time or transient energy function, TATC can directly reflects power system transient stability margin form the view of power which is more conducive for power system planning and operation personnel to grasp system transient stability state, at the same time, is also advantageous for prevention measures and emergency control measures to be developed directly according TATC. Simulation results based on IEEE50 machine 145 bus system show that the proposed TATC can effectively characterize power system transient stability margin.

scholarly journals Risk Evaluation Model of Highway Tunnel Portal Construction Based on BP Fuzzy Neural Network

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Xianghui Deng ◽  
Tian Xu ◽  
Rui Wang
Keyword(s):  
Neural Network ◽  
Numerical Simulation ◽  
Risk Assessment ◽  
Risk Evaluation ◽  
Risk Measures ◽  
Evaluation Model ◽  
Control Measures ◽  
Slope Instability ◽  
Tunnel Portal ◽  
Risk Evaluation Model

Risk assessment for tunnel portals in the construction stage has been widely recognized as one of the most critical phases in tunnel construction as it easily causes accident than the overall length of a tunnel. However, the risk in tunnel portal construction is complicated and uncertain which has made such a neural network very attractive to the construction projects. This paper presents a risk evaluation model, which is obtained from historical data of 50 tunnels, by combining the fuzzy method and BP neural network. The proposed model is used for the risk assessment of the Tiefodian tunnel. The results show that the risk evaluation level is IV, slope instability is the greatest impact index among four risk events, and the major risk factors are confirmed. According to the evaluation results, corresponding risk control measures are suggested and implemented. Finally, numerical simulation is carried out before and after the implementation of risk measures, respectively. The rationality of the proposed risk evaluation model is proved by comparing the numerical simulation results.

Risk Assessment of Power System Cascading Failure Considering Hidden Failures and Violation of Temperature

2011 ◽  
Vol 354-355 ◽  
pp. 1083-1087 ◽  
Author(s):  
Long Yue Zhang ◽  
Li Jie Ding ◽  
Xian Yong Xiao ◽  
Chao Ma ◽  
Jing Feng
Keyword(s):  
Risk Assessment ◽  
Probability Model ◽  
Initial Period ◽  
Cascading Failure ◽  
Failure Model ◽  
Prediction And Prevention ◽  
Hidden Failure ◽  
Line Contacts ◽  
Conductor Temperature ◽  
Hidden Failures

A method was proposed to throw light on the initial period of cascading failure that would be the best time to implement prediction and prevention. A more accurate hidden failure model which considers fault locations and protection schemes was created, as well as a conductor temperature-outage probability model depicting tree-to-line contacts happened in the blackout frequently. It reveals the physical process of cascading failure more clearly and demonstrates that differently located fault which may trigger different PEFD of hidden failures and different ambient situations can both result in different outage sequence.

Grid risk assessment based on cascading failure model

2015 ◽  
Author(s):  
Rui Chen ◽  
Yinguo Yang ◽  
Lei Feng ◽  
Ping Liu ◽  
Lin Zhu
Keyword(s):  
Risk Assessment ◽  
Cascading Failure ◽  
Failure Model

Liquidity Gap Report for Stress Testing Structural Liquidity Risk

GIS Business ◽  
2017 ◽  
Vol 12 (6) ◽  
pp. 43-53
Author(s):  
Eugenia Schmitt
Keyword(s):  
Risk Assessment ◽  
Risk Evaluation ◽  
Stress Testing ◽  
Gap Analysis ◽  
Liquidity Risk ◽  
Methodological Basis ◽  
Qualitative Risk Assessment ◽  
The Future ◽  
Liquidity Gap

The need to focus on banks funding structure and stress testing in an explicit way arose as a consequence of the crisis of past decades. Liquidity risks usually occur as a consequence of other kinds of risks, hence analysing scenarios in a prospective manner is essential for the assessment if the bank can fulfill its obligations as they come due and if its funding costs are appropriate. The structural liquidity risk and the degree of the liquidity mismatch can be measured based on the liquidity gap analysis, where expected cash-in- and outflows, divided in different time-buckets are depicted. The liquidity gap report (LGR) shows if a liquidity shortcoming appears in the future and how high is the amount a bank would have to pay, if any hedging were not possible. This paper shows how to build a comprehensive LGR which is the base for both, liquidity and wealth risk evaluation. To improve the accuracy of the forecast, the counterbalancing capacity will be incorporated into the LGR. This tool is a methodological basis for quantitative and qualitative risk assessment and stress testing.

Risk Assessment of Dental Unit Waterline Contamination

2003 ◽  
Vol os10 (1) ◽  
pp. 5-10 ◽  
Author(s):  
Caroline L Pankhurst
Keyword(s):  
Risk Assessment ◽  
Respiratory Health ◽  
Health And Safety ◽  
Control Measures ◽  
Respiratory Pathogens ◽  
Infection Control Measures ◽  
Colony Forming Units ◽  
Assessment Approach ◽  
Dental Unit Waterlines ◽  
Mycobacterium Spp

Biofilms form rapidly on dental unit waterlines. The majority of the organisms in the biofilm are harmless environmental species, but some dental units may harbour opportunistic respiratory pathogens. This paper describes a risk assessment approach to analysing the hazard from biofilm organisms contaminating dental unit waterlines on the respiratory health of both the dental team and patients. The health risk from the respiratory pathogens Legionella spp, Mycobacterium spp and Pseudomonads was found to be low. Nevertheless, in order to satisfy water regulations and comply with health and safety legislation dentists should institute infection-control measures to maintain the dental unit water at the standard of less than 200 colony-forming units per ml of aerobic bacteria.

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