Study On The Ampacity Estimation For ACCC Conductor Based On Thermal Circuit Model And Markov Chain

Aluminum Conductor Composite Core(ACCC)is new type of high temperature low sag conductor that has the advantages of light weight,high tensile strength,high temperature resistance,low sag,high conductivity,high carrying capacity and good corrosion resistance when compared with traditional overhead Aluminum Conductor Composite Core(ACSR).Benefited from these characteristics,the problems caused by rapid increase of electrical load and difficulty of new transmission corridor building can be worked out easily.Currently,ACCC conductor is one of the most potential new conductors.However owing to the fact that ACCC conductor is short in development time,the studies on ampacity estimation on method are rare.The ampacity of ACCC conductor lines are always determined by steady thermal rating method,which has limited its transmission capacity severely.In order to explore the potentiality of ACCC conductor ampacity and then improve the economy and safety of ACCC lines,this paper has carried out related research on ampacity estimation method for ACCC conductor.Firstly,the traditional ampacity calculation models for ACSR conductor,such as IEEE model,IEC model and thermal circuit model are studied in this paper.Also,the parameters computation methods of these models are compared to analyze the pros and cons of each other,which has laid a foundation of thermal circuit model building for ACCC conductor.Then,on basis of thermoelectricity analogy,take ACCC conductor as the research object,the thermal circuit model has been built in this paper.And the particle swarm optimization parameter identification method is chosen to solve the unknown parameters.To verify the feasibility of the above methods,a temperature rise experiment platform for current-carrying conductor is used,choosing the domestic ACCC-240/35 as the object.The result shows that,the maximum relative error of AC resistance calculation method is less than 1.2%,when the error of the thermal circuit model is no more than 2.2%.The thermal circuit model built in this paper and its parameter identification method can be effectively used to compute the unknown parameters and the thermal dynamic process of the conductor,which has provided the basis for research on ampacity estimation method.Finally,in order to decrease the influence of ampacity estimation result caused by environmental thermal resistance random disturbance in the natural meteorological conditions,the capacity estimation method based on thermal circuit model and Markov chain was proposed in this paper.Through this method,the environmental thermal resistances are simulated by using Markov chain and then the dynamic capacity can be estimate ampacity in the form of overload probability.The outdoor experiment results show that the estimated value and measured value of ACCC conductor ampacity are basically same.the method can offer basic research for mining ACCC line transmission capacity and thus promote the safety and economic operation of ACCC conductor.