Correlation Analysis Of Purchasing Cost And Quality Control For Power Transformer

As one of the main equipment in the substation, power transformer is an important part of the substation equipment investment. The economy and reliability of power system operation are also determined by the purchase cost and quality performance of the transformer. That how to develop effective procurement strategy and quality strategy, purchase the transformer which meets the expectation of the grid with a reasonable price and then make it into the power grid asset life cycle links to guide the quality control in various stages is the problem which is paid attention by the power grid enterprise in recent years.This paper makes power transformer as the object of study and builds the 220 kV transformer purchasing cost estimation model based on fuzzy logic after lots of investigation and site visits. After studying the characteristics, this paper proposes the concept of cost sensitivity and quality sensitivity, and then analyzes the cost and the quality of the transformer used BCG matrix. Finally, the suggestion of differences of quality control strategies is given based on the analysis result. The main research contents and results are as follows:(1) This paper establishes the estimation model of 220 kV transformer main material weight which is based on fuzzy logic. The maximum error is 12% after comparing with the result of capacity growth law and multiple regression analysis verifying by the actual value. The error is below the allowable range. Then the paper establishes the estimation model of 220 kV transformer cost based on the estimation model of transformer main material. After examples validation, the error of the results are respectively +1.9% and +5.5% which proves the accuracy of the model. Meanwhile, it refers that the closer model estimates result to the bidding price, it should be more able to reflect the real purchasing cost of transformer.(2) In order to analyze the characteristics of the cost and quality of the transformer main material and components, the paper makes the percentage of the cost of the components of the transformer accounting for direct cost as cost sensitivity and uses grey correlation analysis to calculate the correlation of the main material and components that the comparison sequences are the test failing rate, defect rate and accident rate. The correlation is taken as the quality sensitivity after sorting. Meanwhile, the resolution coefficient is 0.1357 which determined by particle swarm optimization and the weight of the index series are respectively 0.1970, 0.2974 and 0.5056 which calculated by entropy method.(3) Based on the cost sensitivity, quality sensitivity and BCG matrix, the paper establishes the matrix of the cost and quality control correlation analysis of the transformer. The matrix is divided into four areas which are respectively called key control area, quality-oriented area, strategy optimization area and strategy holding area. Finally, from the perspective of Power Grid Corp, the suggestion of the quality control strategies about the main material and components of transformer is given according to the area which has different characteristics of the cost and quality.The research ideas, proposed research method and the results obtained in this paper have certain reference value to the similar study of other devices on the grid.