Study On The Current-Temperature State Space Model Of Aluminum Conductor Composite Core

Aluminum conductor composite core is a new type of double capacity conductor. Compared with traditional overhead conductors aluminum cable steel reinforced, the conductor has a series of advantages, such as light weight, high tensile strength, large current-carrying capacity, high-temperature and low-sag, high conductivity, low power loss, good heat resistance, low coefficient of linear expansion, good corrosion resistance and no easily icing. However, ACCC is still under development, the studies on current-temperature calculation model are rare, so the corresponding standard for line safe operation is not formed, which hinders application of conductor. Therefor, this paper establishes current-temperature state space model for ACCC based on ACSR current-temperature state space model, which can accurately calculate dynamic process of conductor temperature rise including the axial temperature distribution. It can provide the necessary basis for ACCC conductor safe operation, which has an important theoretic significance and practical values.First of all, the traditional Current-Temperature model is studied in this paper, which includes IEEE model, IEC model, the numerical simulation model, thermal circuit model, and state space model. Then analyzing the calculation methods of the parameters of models, comparing the advantages and disadvantages of each model, and provide a theoretical basis for the study of ACCC current-temperature state space model.Then, current-temperature state space model parameter identification method is improved based on genetic algorithm, which overcomes the problem on difficult selection of initial value for interior point parameter identification method. The effectiveness of proposed parameter identification method is validated based on temperature rise experimental data of ACCC-240/35, and the results showed that genetic algorithm can effectively solve the problem about improper selection of initial value when based on interior point parameter identification method, which can lead to results do not converge or decrease the identification accuracy.Current-temperature state space model for ACCC is established with the kernel ideas of state space model. The current-temperature experiment platform is designed with the ACCC-240/35 conductor as object. The equivalent heat capacity and thermal resistance parameters of conductor model are identified by the proposed parameter identification method, and the change regularity of model parameters with the increasing current is discussed. The results show that with the increase of current, equivalent environment thermal resistance and thermal-conduction resistance of ACCC-240/35 conductor are obviously decreasing, but the excursion of equivalent heat capacity is less, remain stable. Contrast with the same cross section of ACSR conductor, some differences are found. When under the same operating current conditions, equivalent heat capacity of ACCC-240/35 conductor is bigger than ACSR conductor, but equivalent environment thermal resistance and thermal-conduction resistance is smaller. This shows that ACCC conductor is more conducive than ACSR conductor to enhance heat loss through convection with environment, and produce axial temperature difference. After the model of above change regularity of parameters built, the maximum relative error of calculation result on ACCC current-temperature state space model is about 4.8%, and the evaluating relative error is less than 2.2%, so model can accurately calculate dynamic process of conductor temperature rise including the axial temperature distribution.