Reliability and Cost Model of P.M. in A Component of an Electrical Distribution System Considering Ageing Mechanism

Application of Reliability Centered Maintenance (RCM) in a system results in a decrease in component failure rates and as such improvement in the system reliability. One of the major subjects of the RCM is focused on the Online and Offline Preventive Maintenance (OPM and FPM which together will be denoted by OFPM) of the components which repairing the component needs or doesn’t need to stop the mission carrying out by it. The RCM is classified as a preventive maintenance policy and has significant contribution in practical applications. However, little research has been devoted to modeling the online and offline Preventive Maintenance. This research assumes that the component failure rate will be improved if the OFPM is performed for a long period of time as a part of an RCM program. Application of an OFPM program could cause the component set at least to “as bad as old state but cannot reach the “as good as new” state. The emphasis of this research is to model the OFPM for critical components or any equipment with critical failure in a system. The proposed model is based on the concept of PM and improvement factor of reliability in a system with critical components which their failure could cause a failure in the system (first-order cut- sets).DOI:http://dx.doi.org/10.11591/ijece.v4i2.551

Operating health analysis of electric power systems

The required level of operating reserve to be maintained by an electric power system can be determined using both deterministic and probabilistic techniques. Despite the obvious disadvantages of deterministic approaches there is still considerable reluctance to apply probabilistic techniques due to the difficulty of interpreting a single numerical risk index and the lack of sufficient information provided by a single index. A practical way to overcome difficulties is to embed deterministic considerations in the probabilistic indices in order to monitor the system well-being. The system well-being can be designated as healthy, marginal and at risk. The concept of system well-being is examined and extended in this thesis to cover the overall area of operating reserve assessment. Operating reserve evaluation involves the two distinctly different aspects of unit commitment and the dispatch of the committed units. Unit commitment health analysis involves the determination of which unit should be committed to satisfy the operating criteria. The concepts developed for unit commitment health, margin and risk are extended in this thesis to evaluate the response well-being of a generating system. A procedure is presented to determine the optimum dispatch of the committed units to satisfy the response criteria. The impact on the response wellbeing being of variations in the margin time, required regulating margin and load forecast uncertainty are illustrated. The effects on the response well-being of rapid start units, interruptible loads and postponable outages are also illustrated. System well-being is, in general, greatly improved by interconnection with other power systems. The well-being concepts are extended to evaluate the spinning reserve requirements in interconnected systems. The interconnected system unit commitment problem is decomposed into two subproblems in which unit scheduling is performed in each isolated system followed by interconnected system evaluation. A procedure is illustrated to determine the well-being indices of the overall interconnected system. Under normal operating conditions, the system may also be able to carry a limited amount of interruptible load on top of its firm load without violating the operating criterion. An energy based approach is presented to determine the optimum interruptible load carrying capability in both the isolated and interconnected systems. Composite system spinning reserve assessment and composite system well-being are also examined in this research work. The impacts on the composite well-being of operating reserve considerations such as stand-by units, interruptible loads and the physical locations of these resources are illustrated. It is expected that the well-being framework and the concepts developed in this research work will prove extremely useful in the new competitive utility environment

A New Methodology for Allocation of Stabilizers in Uncontrollable poles of multi-machine power systems

One of the main problems in power systems is dynamic stability and damping of Electromechanical  oscillations which for this reason power system stabilizers are being used and the method for determining the location of stabilizer for the purpose of damping critical modes, is using participation factors, in which controllability and observability of modes have influence. The real value or the amplitude of participation factor is usually used as evaluation criterion, while in case that the real values of participation factors are close, the imaginary part of these coefficients are also influential, and if the imaginary part of coefficients are either negative or positive, different results will be obtained. The method introduced in this paper, in modes that the value of participation factors are close to each other, priority for the placement of generator, installation of stabilizer and the optimum value for the stabilizer's gain, is very accurate and appropriate.DOI:http://dx.doi.org/10.11591/ijece.v3i1.183

Implicit Processes in Smoking Interventions

Although explicit attitudes have traditionally been used in predictive models of health behaviour, recent theorizing suggests that implicit attitudes might be more useful in predicting socially undesirable or addictive behaviours. In Studies 1 through 3, smokers’ explicit and implicit attitudes were examined to compare the predictive utility of each. Results confirmed that implicit attitudes are better at predicting impulse-driven behaviours, such as smoking consumption. Consequently, implicit attitudes also predict whether a quit attempt will be successful. In contrast, explicit attitudes are better at predicting deliberative outcomes, such as having intentions to quit, and making planned quit attempts. Extending these findings, in Studies 4 and 5, the effectiveness of a novel affirmation intervention designed to break the association between smoking and stress-reduction is evaluated. Preliminary results demonstrate that an affirmation intervention designed to break the smokers’ reliance on smoking as a means of coping with stress can have beneficial and sustainable effects in cessation outcomes. The impact on smokers’ implicit attitudes as a possible mediating role is discussed. Implications for more effective health interventions are also discussed