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Abstract
In order to efficiently choose poor health status networks from many low-voltage distribution networks to optimize and improve them, this paper proposes an evaluation method of health status of low-voltage distribution network based on order relation-entropy method. Firstly, evaluation index system from 6 status indexes is established. Secondly the indexes are processed consistently, and the indexes dimensionless is processed with extreme value. Then order relation analysis combining expertise is utilized to obtain index subjective weight, meanwhile entropy method is utilized to obtain index objective weight. Finally the optimal Lagrange multiplier method is used to obtain comprehensive index weight, then evaluation function is got, and health status of low-voltage distribution networks is assessed by the function. The feasibility and efficiency of the evaluation method are verified by analyzing several low voltage distribution networks in a certain area. © 2017, Power System Protection and Control Press. All right reserved.
... Exploiting the value of these electric power big data has become important research content for current researchers. At present, the general research idea of using data to analyze power system operation in power system stability analysis is to establish indicators of power grid operation state from different perspectives, respectively, and then to evaluate the system comprehensively by fuzzy comprehensive evaluation method [12], analytic hierarchy process (AHP) [13], entropy theory [14] and so on. For example, in [15], the authors first constructed the operational indicators of the distribution network from three aspects: system operational risk, PV generation uncertainty and network topology robustness; they then used the improved analytic hierarchy process (IAHP) to calculate the weights of different indicators; finally, they summed up to obtain the operational safety indicators of the distribution network. ...
Bulk power grid interconnection and the access of various smart devices make the current grid highly complex. Timely and accurately identifying the power grid operation state is crucial for monitoring the operation stability of the power grid. For this purpose, an evaluation method of the power grid operation state based on random matrix theory and qualitative trend analysis is proposed. This method constructs two evaluation indicators based on the operation data of the power grid, which cannot only find out whether the current state of the power grid is stable but can also find out whether there is a bad operation trend in the current power grid. Compared with the traditional method, this method analyzes the power grid’s operation state from the big data perspective. It does not need to consider the complex network structure and operation mechanism of the actual power grid. Finally, the effectiveness and feasibility of the method are verified by the simulations of the IEEE 118-bus system.
... Chen T et al. [19] proposed an index system of food safety supervision information transparency and used the fuzzy-ANP comprehensive evaluation model to evaluate the food safety supervision information transparency in China. Ji M A and Liu X [20] put forward an evaluation method of health status of low-voltage distribution network, where the optimal Lagrange multiplier method is used to obtain comprehensive index weight based on order relation-entropy method. Wang X et al. [21] constructed an evaluation index system through the qualitative and quantitative analysis of external and internal factors affecting the efficiency of water usage and put forward a matter-element model based on game theory weight to evaluate the effects of the implementation of efficiency control measures for regional water usage. ...
As an important implementing body of the national energy strategy, grid enterprises bear the important responsibility of optimizing the allocation of energy resources and serving the economic and social development, and their levels of sustainable development have a direct impact on the national economy and social life. In this paper, the model of fuzzy group ideal point method and combination weighting method with improved group order relation method and entropy weight method is proposed to evaluate the sustainable development of power grid enterprises. Firstly, on the basis of consulting a large amount of literature, the important criteria of the comprehensive evaluation of the sustainable development of power grid enterprises are preliminarily selected. The opinions of the industry experts are consulted and fed back for many rounds through the Delphi method and the evaluation criteria system for sustainable development of power grid enterprises is determined, then doing the consistent and non dimensional processing of the evaluation criteria. After that, based on the basic order relation method, the weights of each expert judgment matrix are synthesized to construct the compound matter elements. By using matter element analysis, the subjective weights of the criteria are obtained. And entropy weight method is used to determine the objective weights of the preprocessed criteria. Then, combining the subjective and objective information with the combination weighting method based on the subjective and objective weighted attribute value consistency, a more comprehensive, reasonable and accurate combination weight is calculated. Finally, based on the traditional TOPSIS method, the triangular fuzzy numbers are introduced to better realize the scientific processing of the data information which is difficult to quantify, and the queuing indication value of each object and the ranking result are obtained. A numerical example is taken to prove that the model of fuzzy group ideal point method and combination weighting method with improved group order relation method and entropy weight method is feasible and effective for evaluating the sustainable development of power grid enterprises.
... The EWM has been used to determine the weight based on the objective information provided by each evaluation indicator (Ouyang et al. 2013;Ma and Liu 2017). It can not only reflect the importance of a certain indicator in decision-making, but also highlight the changes of each indicator with aging time. ...
Compared with a single chemical indicator, the use of multivariate chemical indicators in aging status assessment of transformer cellulose paper insulation can improve the reliability of the evaluation. In this study, a non-destructive method based on multivariate chemical indicators was proposed to evaluate the remaining life of cellulosic paper insulation. The selected chemical indicators closely related to the aging of the insulating paper were analyzed. Additionally, by applying the subjective and objective weighting method, the evaluation information of each indicator was fully extracted to obtain reasonable comprehensive evaluation weights. Besides, the comprehensive evaluation index of multivariate chemical indicators was obtained by using the technique for order preference by similarity to ideal solution method, which is consistent with the deterioration law of paper insulation. Then, the correlation lifespan model between the comprehensive evaluation index of multivariate chemical indicators and the degree of polymerization of insulating paper under different aging stages was established. The effectiveness of the proposed model was verified by experiments. This promising model can increase the accuracy of the condition assessment for the transformer cellulosic paper insulation.
... Order relations method is an intuitive and effective method to determine subjective weights. It makes full use of experts' experience and obtains the importance ranking of all indices [24]. The following steps constitute the order relations method: Step 1: Determine Order Relations ...
Interconnection of transnational power grids plays an important role in realizing the optimal allocation of energy resources. It can also deepen regional economic cooperation, achieve energy conservation and emission reduction, and improve people’s livelihood. This paper constructs a comprehensive benefit evaluation index system for transnational power networking projects which is suitable for the four stakeholders of investors, international lending institutions, sending-oriented states, and receiving-oriented states. Therefore, on the basis of this index system, this paper adopted the weight determination method based on the order relation method and Gini coefficient method to synthesize subjective and objective information. Then the comprehensive benefit evaluation of such projects was carried out by matter-element extension model with grey relational projection value. Therefore, the problem with the Euclid approach degree leading to a low discrimination of many samples to be evaluated was effectively solved. The final empirical analysis results showed that the focus and evaluation results of the comprehensive benefits of such projects from the perspective of different stakeholders were quite different. The results of comprehensive benefit evaluation will improve the accuracy of decision-making and the objectivity of evaluation, so as to provide decision-making references for different stakeholders.
The existing electric vehicles use charging piles for charging, which is inefficient and inconvenient, so wireless charging technology has become the research focus. Compared with the traditional charging mode, electric vehicle wireless charging does not need wiring, more convenient, safe and efficient. This paper presents a three-coil compensation optimization scheme. Based on the research of square-square coupling coil, while determining the optimal winding mode of the coil, the magnetic cores of transmitting and receiving coils were selected to analyze the coupling situation according to the magnetic field distribution cloud map, and use the Simplorer Maxwell and ANSYS software simulation, analysis, contrast system coupling way, the purpose is to meet the needs of dynamic charging, solve the problem of the current electric vehicle charging limited.
By analyzing the blocking event of DC converter station of the State Grid Corporation in recently ten years, it can be concluded that the sampling system failure, secondary circuit fault, board fault, host fault, etc. of the protection system caused more than 10% of the DC system blockings, which have seriously threatened the normal operation of DC system. Towards this end, this paper makes a statistical analysis of the operation defects of high-voltage direct current (HVDC) transmission protection in Hubei Company in the past five years. A mixed Weibull distribution model method based on entropy weight method is proposed. By using this method, the reliability curve and average defect interval time ( MTBF ) of the DC protection system are obtained. Combined with the actual situation of the converter station, the DC protection system of the converter station is evaluated, which provides an important guiding basis for the subsequent maintenance, system transformation, and replacement of the converter station.
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