Excessively high temperatures inside a power transformer can accelerate the ageing rate and even cause unplanned outages.Accurately estimating the hot-spot temperature(HST)of a power transformer is important for regul...Excessively high temperatures inside a power transformer can accelerate the ageing rate and even cause unplanned outages.Accurately estimating the hot-spot temperature(HST)of a power transformer is important for regulating the load and ensuring long-term operation.In this study,a closed-loop model of a 110-kV product transformer with an oil natural/air forced(ONAF)cooling mode is built to predict HST,in which the compression ratio of windings,equivalent heat source and radiator geometry are considered.According to the flow field of the winding,the‘dead oil zone’and reverse oil flow are observed in the horizontal oil channels.The accuracy of the proposed model is experimentally validated by temperature-rise tests.The results show that the absolute errors between the measured results and simulation are below 5°C,and the average error is~2°C.Furthermore,the arrangements of windings and radiators are studied to enhance the oil circulation.By adding 5 washers to the high-voltage winding,the average temperature can be decreased by 6°C compared with the case without a washer.Elevating the radiator can also mitigate the characteristic temperatures,and the optimal height difference between the radiator and winding centre is suggested to be 0.66 m.展开更多
A saturable reactor is one of the important components of converter valves in high-voltage direct current transmission systems.With the ever-increasing capacities of converter valves,the heat losses generated by satur...A saturable reactor is one of the important components of converter valves in high-voltage direct current transmission systems.With the ever-increasing capacities of converter valves,the heat losses generated by saturable reactors are also increasing.Thus,a thermal-fluid mechanics coupled heat dissipation model for saturable reactors is proposed.In order to study the factors affecting the thermal dissipation in the saturable reactor,the epoxy resin insulating layers with different thermal conductivity were considered in this work.The simulation results showed that the hot spots in the saturable reactor are on the iron core and close to the pipe inlet that most of the generated heat can be extracted by a cooling pipe and that the effect of heat dissipation can be improved by raising the thermal conductivity of the epoxy resin.The thermal conductivities of the epoxy resin used in the two reactors were 0.8 and 1.2 W/mK,respectively.The time dependence of the iron core temperature was in accordance with the simulation results and the maximum temperatures of the saturable reactor were also consistent with the simulation results.By increasing the thermal conductivity of the epoxy insulation layer,the temperature of the iron core could be significantly reduced.展开更多
基金Science and Technology Project of State Grid Corporation of China,Grant/Award Number:5226SX21001C。
文摘Excessively high temperatures inside a power transformer can accelerate the ageing rate and even cause unplanned outages.Accurately estimating the hot-spot temperature(HST)of a power transformer is important for regulating the load and ensuring long-term operation.In this study,a closed-loop model of a 110-kV product transformer with an oil natural/air forced(ONAF)cooling mode is built to predict HST,in which the compression ratio of windings,equivalent heat source and radiator geometry are considered.According to the flow field of the winding,the‘dead oil zone’and reverse oil flow are observed in the horizontal oil channels.The accuracy of the proposed model is experimentally validated by temperature-rise tests.The results show that the absolute errors between the measured results and simulation are below 5°C,and the average error is~2°C.Furthermore,the arrangements of windings and radiators are studied to enhance the oil circulation.By adding 5 washers to the high-voltage winding,the average temperature can be decreased by 6°C compared with the case without a washer.Elevating the radiator can also mitigate the characteristic temperatures,and the optimal height difference between the radiator and winding centre is suggested to be 0.66 m.
基金supported by the Science and Technology Program of the State Grid Corporation of China(No.5455 DW160007).
文摘A saturable reactor is one of the important components of converter valves in high-voltage direct current transmission systems.With the ever-increasing capacities of converter valves,the heat losses generated by saturable reactors are also increasing.Thus,a thermal-fluid mechanics coupled heat dissipation model for saturable reactors is proposed.In order to study the factors affecting the thermal dissipation in the saturable reactor,the epoxy resin insulating layers with different thermal conductivity were considered in this work.The simulation results showed that the hot spots in the saturable reactor are on the iron core and close to the pipe inlet that most of the generated heat can be extracted by a cooling pipe and that the effect of heat dissipation can be improved by raising the thermal conductivity of the epoxy resin.The thermal conductivities of the epoxy resin used in the two reactors were 0.8 and 1.2 W/mK,respectively.The time dependence of the iron core temperature was in accordance with the simulation results and the maximum temperatures of the saturable reactor were also consistent with the simulation results.By increasing the thermal conductivity of the epoxy insulation layer,the temperature of the iron core could be significantly reduced.
