Research And Application Of High-voltage Cable Insulation Aging Evaluation System

Cross-linked polyethylene cables(XLPE cables for short)are widely used in high-voltage power transmission lines of power systems and are an important part of power systems.Ensuring its safe operation is vital to grid security.However,many XLPE cables in operation have been running for many years,and some have reached the end of their service life.These XLPE cables are no longer suitable for continued operation.We need to accurately evaluate the use of high-voltage XLPE cables to determine whether the cables continue to run or exit the power system.This can avoid power outages that affect power system operation due to cable failures.Studies have shown that high-voltage cables undergo insulation aging under the synergistic effects of electricity,heat,machinery,moisture and other factors.When the cables undergo insulation aging,some characteristic parameters of the cables will change.By studying the changes of these characteristic parameters before and after aging,Law,so we can judge the aging status of the cable.In this thesis,firstly,through the tensile test,thermogravimetric analysis test,FTIR spectrum test,differential scanning calorimetry,AC breakdown test and other experiments to obtain the characteristic quantity indicators reflecting the aging state of the cable,and then study the differences in moisture and laying methods to these characteristics This will provide some guidance for future cable installation.Because there are many factors reflecting cable aging,many factors have strong correlations.In order to reduce the redundancy of the data,we obtain the five characteristic quantities that are most relevant to cable insulation aging,namely the elongation at break,through correlation analysis,Melting temperature,breakdown field strength,carbonyl index,thermal decomposition temperature.By studying the above five characteristics and the change law of the cable insulation aging,we can get the status indicators of the cable.According to the aging status of the cable,we can choose whether the cable should be replaced or continued to be used.In order to evaluate the aging status of the cable,we choose an improved fuzzy analytic hierarchy process,which calculates the weight of each evaluation factor from the fuzzy judgment matrix.The process of solving the weights can be expressed by a mathematical problem,and then through the iterative optimization of the improved whale optimization algorithm to find the optimal solution.According to the obtained optimal solution weights,we bring them into the empirical formula reflecting the aging of electrical equipment,so that the aging state of the cable can be obtained.In order to reflect the aging status of the cable intuitively,we have developed a high-voltage cable insulation aging status evaluation software system based on the theory.This system implements the evaluation of the cable aging status based on an improved fuzzy analytic method.The system has a user login.Fill in the fuzzy judgment matrix,cable parameters,the remaining life of the cable and the results of each evaluation index.In this system,the importance of each evaluation index can be filled in reasonably by experts to evaluate the aging status of the cable more accurately,and the interface of this system is simple to fill in,and the evaluation of the aging status of the cable can be completed without complicated operations.By evaluating multiple cables,the system proves that the system has practical value.