Health status evaluation of secondary power equipment using entropy weight method
TAN Jinlong
WANG Kaike
YU Bing
NAN Dongliang
LIU Huanqing
Abstract：[Objective]Conducting a state evaluation of secondary equipment in power systems is crucial for mitigating the operational risks of the power grid and improving grid reliability.To address the logical issues in the analytic hierarchy process(AHP)and the limitations of subjective judgment in the entropy weight method,this study proposed an improved entropy weight method for assessing the health status of secondary equipment.[Methods]Based on the fundamental characteristics of secondary equipment in the power system,both technical and management indicators for the state evaluation were developed.The study utilized forward,reverse,and trapezoidal mapping relationships to standardize the indicator parameters.In addition,a membership function based on normal distribution was adopted.This function retained valid information from high membership intervals,incorporating information from low membership ranges,and avoided misjudgment caused by an overemphasis on the low membership range.The weight principle of AHP was used to establish the judgment matrix of different evaluation indicators,and the coefficient of variation in the entropy weight method was introduced based on the arithmetic mean and standard deviation of each indicator,enabling an objective representation of the evaluation indicator weight.Subsequently,a comprehensive model for the state evaluation of secondary equipment was established.The model was validated using 36 protection devices in a substation.[Results]The verification results demonstrate that the evaluation results aligns with the actual operation status of the protection device.The membership value for"good"is 0.890 1,and for"fair"it is 0.097 9,which allows for the determination that the 220 kV main transformer protection device operates normally and consistents with the actual operational state of the protection device.The range of the membership function for evaluation indices obtained using AHP is 0.321 0,while the entropy weight method yields a range of 0.341 4,which may lead to misjudgments.Longitudinal comparisons of the AHP-entropy weight method and the entropy method's weighting algorithms show that the membership degree ranges are 0.125 0 and 0.184 9,with minimum values of 0.806 5 and 0.708 8,respectively,with no misjudgments.In this method,the difference in the range values of the membership degree is 0.048 1,with maximum and minimum values of 0.900 0 and 0.851 9,resulting in a narrower fluctuation range and higher judgment reliability.[Conclusion]The innovation of this study lies in the combination of AHP and the entropy weight method,which effectively avoids the interference of human factors in subjective weighting.Moreover,by incorporating objective factors into equipment evaluation and introducing an entropy weight calculation method based on the coefficient of variation,the weight calculation accurately reflects the equipment's actual operation status.The actual calculation results show that the proposed method more effectively reflects the actual state of equipment operation and provides crucial support for equipment operation and maintenance.
Keywords：secondary equipmententropy weight methodanalytic hierarchy processstate evaluationcomprehensive indicatorcoefficient of variationoperating statusindicator weight
Publication Date：2025-07-25
Online Publishing Date：2025-09-18(First online date of this platform, not the publication date of the document)
Pages：7( 425-431 )