【作者】 孙超；

【导师】 董恩源；

【作者基本信息】 大连理工大学 ， 电气工程， 2020， 硕士

【摘要】 随着我国经济的腾飞,企业、家庭用电量不断攀升,电力行业飞速发展。由于电量需求量的增加,电网负荷不断加大,而故障产生时的短路电流会对整个输电网络产生很大影响乃至不可逆损害。电流转移是利用并联支路间的电压竞争,使故障电流从主通流支路转移至与之并联的功能支路,主要应用在故障限流和直流转移开断等领域。为满足电流转移快速性要求,实现阻抗快速变化,本文提出了一种用于电流转移的压控变阻装置。通过控制压控材料压力的变化,进而控制其电阻变化。由电流转移原理可知,压控变阻装置应具备:稳态接入支路时通态电阻小、通流能力强、通流散热性能好;需要故障切除时能够迅速动作增大支路阻抗。本文对压控变阻机构的出力、分闸速度等特性影响因素进行研究分析;同时为确保压控材料长期压紧通流时的稳定状态,对压控材料温升分布及散热进行了仿真分析;并研究了容器不同材料、不同外加散热方式等因素对温升情况的影响。本文设计了压控变阻装置,对其变阻机构进行设计,并进行了基于此变阻机构的操动特性研究,使其具备体积小、出力大、分闸时间短、激磁驱动电流小等特点。变阻机构设计合闸保持力达到12000 N以上;利用Ansoft进行了有限元仿真,定量分析其特性影响因素,完成了压缩大刚度弹簧合闸。实现压控材料阻值在5 ms时间内由毫欧级变化至欧姆级。依据仿真和试验结果,本文压控变阻机构具有较好的出力特性及操动水平。本文依据热力学定律,利用Ansys对压控材料接入转移支路的稳态、瞬态发热情况进行了有限元仿真,稳态通过电流大于500 A。对压控材料通流容器不同材料热导率、不同结构的散热特性、绝缘特性进行了仿真对比,并对不同散热片结构、位置以及不同散热方式的实效性进行了仿真与试验对比,验证了散热方案的可行性。在仿真分析的基础上,设计装配了压控变阻装置样机整机,对整机操动特性下的压控材料动态电阻特性进行了测定与分析,并进行了电流转移动态试验与温升散热试验。样机试验与仿真对比分析表明,本文压控变阻装置能够通过电阻快速变化实现电流快速转移,具有控制灵活、恢复时间短、易于合闸操作、体积小、成本低等优点,其良好的支路电阻变化操动特性及稳定性,为提升电流转移效率提供了更多可能性。更多还原

【Abstract】 As China’s economy gains momentum,power industry enjoys fast development with the electricity consumption by corporate and household soaring.High demand of electricity is bound to bring more pressure to the grid.Then the fault current caused by malfunction may have serious or even the irreversible impact on the entire electricity supply network.Current transfer utilizes voltage competition between parallel branches.The fault current is transferred from the main current branch to the functional branch parallel to it.Mainly used in fault current limiting and DC transfer breaking.In order to meet the requirements of rapid current transfer,this paper studies a device whose resistance is changed by pressure.Through controlling the change of pressure of the pressure-controlled material,we can control the resistance change.According to the principle of current transfer,we can note that the pressure-controlled variable resistance device need a steady access to the current loop with small on-state resistance,a strong electric current flow capability,and a good heat dissipation ability.Furthermore,it also should be able to swiftly increase branch impedance when a current fault occurs.This paper studies pressure-controlled rheostat,including its pressure output,separation speed and other characteristics affecting factors.At the same time to ensure that it is in the long-term stable state under pressure,we conducted a simulation study of the current.The influence of different materials and different heat dissipation methods on temperature changes is analyzed.In this paper,I design the pressure-controlled variable resistance device,and I also devise its operating mechanism and examine its operating characteristics based on this mechanism so that it can possess features like small volume,large pressure output,short opening time,small control current.The closing pressure of the variable resistance mechanism is designed to reach more than 12000 N.Ansoft was used to carry out finite element simulation and quantitative analysis of factors which affect its characteristics.Realize pressure control material resistance changes from milliohm level to ohm level within 5 ms.In line with the results from simulation and experiment,the pressure-controlled variable resistance device is blessed with a better pressure output and operation capability.Based on the laws of thermodynamics,Pressure-controlled material is connected to the circuit,the purpose is to analyze their steady state and transient state of fever through Ansys,which steady state passing current is greater than 500 A.Besides,the simulation comparison of the different materials,different thermal properties and insulation capacity was also launched and this paper also look into the effectiveness and feasibility of the various heat sink structures and cooling methods.On the basis of simulation analysis,the prototype machine of pressure-controlled variable resistance device is designed and assembled,and the resistance change characteristics of pressure controlled materials under the operating characteristics of the whole machine are measured and analyzed,and the current transfer dynamic test and through-current temperature rise test are carried out.The test and simulation results show that the pressure-controlled rheostat device has good operating characteristics and stability of branch resistance variation.It has the advantages of flexible control,short recovery time,easy closing operation,small volume and relatively low cost.It can quickly achieve current transfer through changes in resistance,improved current transfer efficiency.更多还原