Mohd Salleh Serwan

Cascading Collapse Assessment Considering Hidden Failure

Hidden failure relay protection is the major cause of cascading failure in power system. Therefore, in this study, a hidden failure model has been developed to study the impact of certain parameter that could cause cascading collapse. The parameters that could lead to major blackout include system loading level, spinning reserve, hidden failure probability and other factors. As the overall load is the key factor that could affect the risk of cascading outages, this study will reveal the impact of it to the system. A test system of IEEE 24 bus RTS is used as a case study. The hidden failure model adopts here is the steady state analysis, which is caused by line tripping. The significant loads at which blackout risk sharply increases are identifiable for cascading collapse. This study can provide guidance for the utility on when and how to mitigate the cascading collapse from spreading to the entire power system. This study also can determine the critical loading in the risk of cascading failure.

Critical System Cascading Collapse Assessment for Determining the Sensitive Transmission Lines and Severity of Total Loading Conditions

This paper presents a computationally accurate technique used to determine the estimated average probability of a system cascading collapse considering the effect of hidden failure on a protection system. This includes an accurate calculation of the probability of hidden failure as it will give significant effect on the results of the estimated average probability of system cascading collapse. The estimated average probability of a system cascading collapse is then used to determine the severe loading condition contributing to a higher risk of a system cascading collapse. This information is important because it will assist the utility to determine the maximum level of increase in the system loading condition before the occurrence of critical power system cascading collapse. Furthermore, the initial tripping of sensitive transmission line contributing to a critical system cascading collapse can also be determined by using the proposed method. Based on the results obtained from this study, it was found that selecting the accurate probability of hidden failure is very important as it will affect the estimated average probability of a system cascading collapse. Comparative study has been done with other techniques to verify the effectiveness of the proposed method used in the determination of sensitive transmission lines.

Risk assessment of dynamic system cascading collapse for determining the sensitive transmission lines and severity of total loading conditions

This paper presents a computationally accurate technique used to determine the estimated average probability of a dynamic system cascading collapse considering the effect of hidden failure on a protection system. This requires an accurate calculation of the probability of hidden failure as it will give significant effect on the results of the estimated average probability of dynamic system cascading collapse. The estimated average probability of a dynamic system cascading collapse is then used to determine the severe loading condition contributing to a higher risk of a system cascading collapse. This information of risk assessment is important to the utility that will assist them to determine the maximum level of increase in the system loading condition before a critical dynamic system cascading collapse is incurred. Furthermore, initial tripping of sensitive transmission line contributing to a dynamic critical system cascading collapse can also be determined by using the proposed risk assessment. Based on the results obtained from this study, it was found that selecting the accurate probability of hidden failure is very important as it will affect the estimated average probability of a dynamic system cascading collapse used for determining the results of sensitive transmission lines and severity of total loading conditions.

An effective approach to determine the sensitive transmission lines due to the effect of hidden failure in a protection system

Protection system hidden failure was identified as one of the main causes of cascading failure. However, in the current practice of power system analysis, protection system is assumed to be perfect and the impact of hidden failures of a protection system is neglected. This paper proposes a systematically accurate technique to evaluate the impact of protection system hidden failures to the probability of system cascading outage. Further analysis is performed by analyzing the results of the probability of a system cascading outage which will then be used to identify the initial tripping of sensitive transmission lines that could contribute to calamitous cascading outage in the system. In accordance with the results that have been obtained, it is important to decide on the accurate value of the hidden failure probability as it will have an effect on the probability of a system cascading outage. This analysis is beneficial not only for the power system operation and planning, but also to the system operator in order to determine the exact locations to improve the protection system.

Improvisation on Standard Limit of the Critical Clearing Time Specified for the Protection Relays Using one Machine Infinite Bus Equivalent

This paper presents a computationally accurate technique used to determine the critical clearing time using the one machine infinite bus equivalent system based on the equal area criterion. The critical clearing time is the maximum time interval by which the fault must be cleared in order to preserve the system stability. The computation of critical clearing time involves an intrinsic mathematical formulation derived from the pre-fault, during fault and post-fault conditions. The value of critical clearing time becomes significantly less when transient instability is induced by a three phase fault occurred at the bus bar closest to the substation connected with a sensitive generator. By setting the protection relay with the obtained value of critical clearing time, it is adequate to sustain the transient stability even though fault happened at the other locations. During the occurrence of fault, a circuit breaker which is operating earlier than the smallest critical clearing time will not agitate to a transient instability. The IEEE Reliability Test System 1979 (RTS-79) is used to verify the robustness of the methodology in a determining the critical clearing time.

Comparison between the System Cascading Collapse Based Hidden Failure and Fault Chain Theory in the Determination of Sensitive Transmission Lines

This paper presents a computationally accurate technique used to determine the estimated average probability of a system cascading collapse in association with the effect of hidden failure on a protection system. This includes an accurate calculation of the probability of hidden failure as it will provide considerable effect on the results of the estimated average probability of system cascading collapse. The estimated average probability of a system cascading collapse is then used to determine the sensitive transmission contributing to a higher risk of a system cascading collapse. This information is important because it will assist the utility to determine the critical transmission lines before the occurrence of critical power system cascading collapse. Comparative study has been done with other techniques to verify the effectiveness of the proposed method used in the determination of sensitive transmission lines.

Implication of transmission line outages and system cascading collapse in the evaluation of TRM and ATC

Available transfer capability (ATC) and transmission reliability margin (TRM) provides imperative information for power marketers and planning sectors in a deregulated power system. The stochastic environment of power system activities, however, made the evaluation of TRM and ATC a intricate and complicated task. A stochastic structure has been established for TRM and ATC calculation with implication of uncertainties in transmission line outages and system cascading collapse. The evaluation of the proposed TRM and ATC calculation is based on bootstrap technique which allows generating random samples of transmission line outages and system cascading collapse at a predefined confidence interval. The IEEE RTS-79 network is used as a case study in order to verify the effectiveness and robustness of the proposed technique. The results elucidate the significant impact of uncertainties on TRM and ATC value.

Identifying severe loading condition during the events of cascading outage considering the effects of protection system hidden failure

Protection system plays an important function in maintaining the stability and reliability of the electric power grid. However, most of the major blackouts happened throughout the world has identified that hidden failure of a protection system is one of the major causes of system cascading failure. This paper proposes a computationally systematic approach to assess the impact of protection system hidden failures to the probability of system cascading collapse. Additional analysis is performed by analyzing the results of the probability of a system cascading collapse which will then be applied tin order to obtain the severe loading condition contributing to greater risk of critical system cascading outages. According to the findings that have been achieved in this analysis, it is essential to choose the accurate value of the hidden failure probability as it will have an impact on the probability of system cascading outages. This information is important to the system utility as it could assist the operator to determine the highest point of increased system loading condition prior to the event of critical system cascading collapse.