In recent years,more than 6 million room temperature vulcanized(RTV)silicone rubber coated cap and pin insulators with high mechanical ratings were used in ultra-high voltage transmission lines in China to improve pol...In recent years,more than 6 million room temperature vulcanized(RTV)silicone rubber coated cap and pin insulators with high mechanical ratings were used in ultra-high voltage transmission lines in China to improve pollution performance.However,the unexpected puncture phenomena of RTV coated insulators were exposed during steep-front impulse voltage tests;for instance,the steep-front impulse voltage test pass rate decreased to less than 50% for 550 kN glass insulators with RTV coatings.The steep-front impulse voltage test is the most effective method used to check the insulation quality of cap and pin insulators・This unexpected phenomenon once caused serious concerns to power utilities.In this paper,several possible factors that affect the puncture of insulators were analyzed.Then,the extent of the decline in the breakdown of the 550 kN glass cap and pin insulators with and without RTV coatings were studied.The initial puncture location was then found,and the developmental process of the arc on the insulator surface in steep-front impulse voltage tests was observed with an ultra-high-speed intensified charge coupled device camera.Lastly,a breakdown mechanism is proposed.The puncture phenomena of a RTV coated insulator in a steep-front impulse voltage test is essentially an electrical breakdown of the internal insulation・The RTV coating induces the close adherence of the arc to the surface of the insulator.Such closeness changes the arc development path on the insulator surface and facilitates easy breakdown in the shed weak part.All these factors result in a significant increase in the breakdown probability of RTV coated insulators in steepfront impulse voltage tests.展开更多
During on-site withstand voltage tests of gas-insulated switchgears(GIS),once a breakdown occurs,it is hard to locate the breakdown position due to the intricate branch structures and minimal breakdown energy.The exis...During on-site withstand voltage tests of gas-insulated switchgears(GIS),once a breakdown occurs,it is hard to locate the breakdown position due to the intricate branch structures and minimal breakdown energy.The existing methods may require the placement of a large number of sensors with unsatisfactory accuracy,which adversely affects the process of inspecting and repairing,as well as the subsequent tests.To address this issue,this paper introduces a novel GIS breakdown location method.This method is predicated on the natural frequency of the transient voltage caused by the breakdown.The relationship between the breakdown position and the natural frequency is first derived,which is referred to as the location equation.Then,the natural frequency characteristics are discussed from both mathematical and energy perspectives.Based on these characteristics,the location method is proposed that utilises the location equation and the frequencies at two measurement points.The results of the laboratory experiments demonstrate the accuracy of the method and certain advantages over the ultrasonic method.Further,the effectiveness of the method in GIS and gas-insulated transmission lines(GIL)with complex structures and high voltage levels is also confirmed by simu-lation cases and field experimental data.展开更多
Excitation transformer is an important component of the power plant transformer group equipment. Its reliable operation is an important factor to ensure the stable safety of the unit. In recent years, due to the failu...Excitation transformer is an important component of the power plant transformer group equipment. Its reliable operation is an important factor to ensure the stable safety of the unit. In recent years, due to the failure of excitation transformer, some power plants have not stop, which has a great impact on the safety of equipment and power supply stability. Combined with the several failures of excitation transformer in a power generation enterprise in recent years, this paper sorts out the problems of excitation transformer in power plant caused by failure one by one, analyzes the causes in depth, and puts forward countermeasures.展开更多
With the surge of demand for instant high power in miniaturized electronic and mechanical systems,supercapacitors(SCs)are considered as one of the viable candidates to fulfill the requirements.Thus,long-term resilienc...With the surge of demand for instant high power in miniaturized electronic and mechanical systems,supercapacitors(SCs)are considered as one of the viable candidates to fulfill the requirements.Thus,long-term resilience and superior energy density associated with self-discharge in SCs are obviously critical,but securing electrode materials,which can meet both benefits of SCs and persist charged potential for a comparatively prolonged duration,are still elusive.Herein,hierarchically refined nickel-sulfide heterostructure(CuO-NS)on CuO(CO)scaffold is achieved through optimized film formation,exhibiting a threefold improvement in the essential electrochemical characteristics and outstanding capacitance retention(∼5%loss).Self-discharge behavior and its mechanism are systematically investigated via morphological control and nanostructural evolution.Furthermore,significant mitigation of self-discharge owing to an increase in surface area and refined nanostructure is displayed.Remarkably,CuO-NS2(20 cycle overcoating)based SC can retain over 60%of the charged potential for a complete voltage holding and a self-discharge test for 16 h.An appealing demonstration of wireless power transmission in burst mode is demonstrated for secure digital(SD)card data writing,powered by SCs,which substantiates that it can be readily leveraged in power management systems.This enables us to realize one of the envisioned applications soon.展开更多
After examination of the designed high voltage power supply system of the BESⅢ drift chamber in the beam test of the full length prototype of drift chamber, a full system covering all the channels of high voltage was...After examination of the designed high voltage power supply system of the BESⅢ drift chamber in the beam test of the full length prototype of drift chamber, a full system covering all the channels of high voltage was installed. The system＇s training and the high voltage value adjustment were carried out in the cosmic ray test of the BESⅢ drift chamber. The cosmic ray test for the full system and its final installation on the BESⅢ drift chamber were reported. The full system of high voltage power supply works stably and reliably.展开更多
基金supported by the National Natural Science Foundation of China(51577099).
文摘In recent years,more than 6 million room temperature vulcanized(RTV)silicone rubber coated cap and pin insulators with high mechanical ratings were used in ultra-high voltage transmission lines in China to improve pollution performance.However,the unexpected puncture phenomena of RTV coated insulators were exposed during steep-front impulse voltage tests;for instance,the steep-front impulse voltage test pass rate decreased to less than 50% for 550 kN glass insulators with RTV coatings.The steep-front impulse voltage test is the most effective method used to check the insulation quality of cap and pin insulators・This unexpected phenomenon once caused serious concerns to power utilities.In this paper,several possible factors that affect the puncture of insulators were analyzed.Then,the extent of the decline in the breakdown of the 550 kN glass cap and pin insulators with and without RTV coatings were studied.The initial puncture location was then found,and the developmental process of the arc on the insulator surface in steep-front impulse voltage tests was observed with an ultra-high-speed intensified charge coupled device camera.Lastly,a breakdown mechanism is proposed.The puncture phenomena of a RTV coated insulator in a steep-front impulse voltage test is essentially an electrical breakdown of the internal insulation・The RTV coating induces the close adherence of the arc to the surface of the insulator.Such closeness changes the arc development path on the insulator surface and facilitates easy breakdown in the shed weak part.All these factors result in a significant increase in the breakdown probability of RTV coated insulators in steepfront impulse voltage tests.
基金National Key R&D Program of China,Grant/Award Numbers:2022YFB2403700,2022YFB2403705。
文摘During on-site withstand voltage tests of gas-insulated switchgears(GIS),once a breakdown occurs,it is hard to locate the breakdown position due to the intricate branch structures and minimal breakdown energy.The existing methods may require the placement of a large number of sensors with unsatisfactory accuracy,which adversely affects the process of inspecting and repairing,as well as the subsequent tests.To address this issue,this paper introduces a novel GIS breakdown location method.This method is predicated on the natural frequency of the transient voltage caused by the breakdown.The relationship between the breakdown position and the natural frequency is first derived,which is referred to as the location equation.Then,the natural frequency characteristics are discussed from both mathematical and energy perspectives.Based on these characteristics,the location method is proposed that utilises the location equation and the frequencies at two measurement points.The results of the laboratory experiments demonstrate the accuracy of the method and certain advantages over the ultrasonic method.Further,the effectiveness of the method in GIS and gas-insulated transmission lines(GIL)with complex structures and high voltage levels is also confirmed by simu-lation cases and field experimental data.
文摘Excitation transformer is an important component of the power plant transformer group equipment. Its reliable operation is an important factor to ensure the stable safety of the unit. In recent years, due to the failure of excitation transformer, some power plants have not stop, which has a great impact on the safety of equipment and power supply stability. Combined with the several failures of excitation transformer in a power generation enterprise in recent years, this paper sorts out the problems of excitation transformer in power plant caused by failure one by one, analyzes the causes in depth, and puts forward countermeasures.
基金supported by the Incheon National University Research Grant in 2022,Incheon,Republic of Korea.
文摘With the surge of demand for instant high power in miniaturized electronic and mechanical systems,supercapacitors(SCs)are considered as one of the viable candidates to fulfill the requirements.Thus,long-term resilience and superior energy density associated with self-discharge in SCs are obviously critical,but securing electrode materials,which can meet both benefits of SCs and persist charged potential for a comparatively prolonged duration,are still elusive.Herein,hierarchically refined nickel-sulfide heterostructure(CuO-NS)on CuO(CO)scaffold is achieved through optimized film formation,exhibiting a threefold improvement in the essential electrochemical characteristics and outstanding capacitance retention(∼5%loss).Self-discharge behavior and its mechanism are systematically investigated via morphological control and nanostructural evolution.Furthermore,significant mitigation of self-discharge owing to an increase in surface area and refined nanostructure is displayed.Remarkably,CuO-NS2(20 cycle overcoating)based SC can retain over 60%of the charged potential for a complete voltage holding and a self-discharge test for 16 h.An appealing demonstration of wireless power transmission in burst mode is demonstrated for secure digital(SD)card data writing,powered by SCs,which substantiates that it can be readily leveraged in power management systems.This enables us to realize one of the envisioned applications soon.
文摘After examination of the designed high voltage power supply system of the BESⅢ drift chamber in the beam test of the full length prototype of drift chamber, a full system covering all the channels of high voltage was installed. The system＇s training and the high voltage value adjustment were carried out in the cosmic ray test of the BESⅢ drift chamber. The cosmic ray test for the full system and its final installation on the BESⅢ drift chamber were reported. The full system of high voltage power supply works stably and reliably.
