This study investigated the feasibility of distance protection in extra-high voltage(EHV) networks. In long-distance transmission lines, the distributed parameter characteristic of the EHV network is obvious. When a f...This study investigated the feasibility of distance protection in extra-high voltage(EHV) networks. In long-distance transmission lines, the distributed parameter characteristic of the EHV network is obvious. When a fault occurs far away from the measurement site, the measured impedance might not be directly proportional to the fault distance, and the protection domain of distance protection will be decreased. The detailed theory inferred and proven in this paper reveals that this phenomenon is widespread in EHV transmission lines. The results indicate that the protection domain error is greatly reduced by the application of the shunt reactor. Overall, simulation results show that the proposed method is effective for impedance relay, considering different characteristics, different lengths of lines, and compensation degrees.展开更多
In order to fully understand the noise characteristics, calculation and control of high-voltage shunt reactors, the noise generation mechanism, acoustic force and pressure characteristics, corrosion and interference p...In order to fully understand the noise characteristics, calculation and control of high-voltage shunt reactors, the noise generation mechanism, acoustic force and pressure characteristics, corrosion and interference process of high-voltage shunt reactors are studied through theoretical analysis, modeling calculation and field measurement, and the control methods and measures are discussed. The results show that the resistance is mainly due to the electromagnetic force between the steel blocks, and the acoustic wave level increases with the increase of nominal capacity. The acoustic energy is mainly concentrated in one third of the central frequency of 100 MHz;The sound pressure distribution of the reactor is very complicated, with slow speed and obvious sound interference. Its scale increases as the business voltage increases, but is not related to the workload. Voice interference should be considered when calculating the noise of electrical equipment, and the accuracy of calculation should be improved. The noise is mainly regulated by the sound insulation cover with a maximum volume of 20db. This research can provide important support for the planning, design, control and management of high-voltage power stations.展开更多
The high frequency transient recovery voltage caused by usually switching operation of the circuit breakers, used on shunt reactor switching, have become a noticeable problem recently. For extension the service life t...The high frequency transient recovery voltage caused by usually switching operation of the circuit breakers, used on shunt reactor switching, have become a noticeable problem recently. For extension the service life time and normal operation of the circuit breakers, a well modified maintenance strategy is proposed. The field testing and experimental measurement showed the maintenance strategy proposed had been proved effectively and adopted in Taiwan Power Company.展开更多
This paper analyzes the fundamental frequency impedance presents a novel transmission line pilot protection scheme characteristic of a thyristor controlled series capacitor （TCSC） and based on fault component integr...This paper analyzes the fundamental frequency impedance presents a novel transmission line pilot protection scheme characteristic of a thyristor controlled series capacitor （TCSC） and based on fault component integrated impedance （FCII） calculated for a transmission line with TCSC and controllable shunt reactor （CSR）. The FCII is defined as the ratio of the sum of the fault component voltage phasors of a transmission line with TCSC and CSR to the sum of the fault component current phasors where all the phasors are determined at both line＇s terminals. It can be used to distinguish internal faults occurring on the line from external ones. If the fault is an external one the FCII reflects the line＇s capacitive impedance and has large value. If the fault is an internal one on the line the FCII reflects the impedance of the equivalent system and the line and is relatively small. The new pilot protection scheme can be easily set and has the fault phase selection ability and also it is not affected by the capacitive current and the fault transition resistance. It is not sensitive to compensation level and dynamics of TCSC and CSR. The effectiveness of the new scheme is validated against data obtained in ATP simulations and Northwest China 750 kV Project.展开更多
The integration of a high proportion of renewable energy introduces significant challenges for the adaptability of traditional fault nature identification methods.To address these challenges,this paper presents a nove...The integration of a high proportion of renewable energy introduces significant challenges for the adaptability of traditional fault nature identification methods.To address these challenges,this paper presents a novel fault nature identification method for renewable energy grid-connected interconnection lines,leveraging wavelet packet decomposition and voltage waveform time-frequency morphology comparison algorithms.First,the paper investigates the harmonic injection mechanism during non-full-phase operation following fault isolation in photovoltaic renewable energy systems,and examines the voltage characteristics of faulted phases in renewable energy scenarios.The analysis reveals that substantial differences exist in both the time and frequency domains of phase voltages before and after the extinction of transient faults,whereas permanent faults do not exhibit such variations.Building on this observation,the paper proposes a voltage time-frequency feature extraction method based on wavelet packet decomposition,wherein low-frequency waveform components are selected to characterize fault features.Subsequently,a fault nature identification method is introduced,based on a voltage waveform time-frequency morphology comparison.By employing a windowing technique to quantify waveform differences before and after arc extinction,this method effectively distinguishes between permanent and transient faults and accurately determines the arc extinction time.Finally,a 220 kV renewable energy grid connection line model is developed using PSCAD for verification.The results demonstrate that the proposed method is highly adaptable across various fault locations,transition resistances,and renewable energy control strategies,and can reliably identify fault nature in renewable energy grid connection scenarios.展开更多
并联电抗器(以下简称电抗器)是在高压长距离输电工程中无功补偿的关键设备,电抗器故障对电网的安全稳定运行构成威胁。文中研究了浙江某特高压变电站1000 k V线路的电抗器故障现象,通过在线油中溶解气体分析发现电抗器发生电弧放电故障...并联电抗器(以下简称电抗器)是在高压长距离输电工程中无功补偿的关键设备,电抗器故障对电网的安全稳定运行构成威胁。文中研究了浙江某特高压变电站1000 k V线路的电抗器故障现象,通过在线油中溶解气体分析发现电抗器发生电弧放电故障,然后通过局部放电在线监测和超声波局放检测等方法再次确认故障并定位到放电位置在电抗器A、X两柱,最后通过解体检查确认故障在电抗铁心柱表面地屏出出现放电。为了进一步追溯绝缘击穿的原因,文中对油中溶解气体突变、局部放电最大放电量与电网事件进行了相关性分析,发现电抗器中乙炔的突然增加与局部放电的发生时间有明显的相关性,延迟约2~3天,这个时间延迟反映了乙炔在油中的扩散过程。并联电抗器油中乙炔的突然增加与线路切换操作和电压突变存在时序关系,线路切换和电压突变导致电抗器绝缘击穿进而引发放电,是乙炔异常生长的根本原因。文中可为其他特高压变电站电抗器故障溯源提供思路。展开更多
电磁型设备为基础的柔性交流输配电技术(electromagnetic equipment based flexible AC transmission&distribution technology,EME-FTDT)以常规电力设备为基础,利用机械开关、电力电子开关作为执行机构,结合控制技术,使其功能特性...电磁型设备为基础的柔性交流输配电技术(electromagnetic equipment based flexible AC transmission&distribution technology,EME-FTDT)以常规电力设备为基础,利用机械开关、电力电子开关作为执行机构,结合控制技术,使其功能特性更灵活,以适应系统状态变化,提升交流输配电系统的安全性和经济性。中国电力科学研究院近二十多年来在EME-FTDT方面开展了大量研发工作,主导研制成功多项EME-FTDT装置。该文阐述了变压器柔性调控技术、断路器柔性控制技术、可控电抗器、可控避雷器、可控中性点接地装置、混合式可控移相器和配电网电磁型柔性互联装置等各类EME-FTDT装置的工作原理,系统总结了中国电力科学研究院在EME-FTDT领域的技术研发与工程应用进展。展开更多
文摘This study investigated the feasibility of distance protection in extra-high voltage(EHV) networks. In long-distance transmission lines, the distributed parameter characteristic of the EHV network is obvious. When a fault occurs far away from the measurement site, the measured impedance might not be directly proportional to the fault distance, and the protection domain of distance protection will be decreased. The detailed theory inferred and proven in this paper reveals that this phenomenon is widespread in EHV transmission lines. The results indicate that the protection domain error is greatly reduced by the application of the shunt reactor. Overall, simulation results show that the proposed method is effective for impedance relay, considering different characteristics, different lengths of lines, and compensation degrees.
文摘In order to fully understand the noise characteristics, calculation and control of high-voltage shunt reactors, the noise generation mechanism, acoustic force and pressure characteristics, corrosion and interference process of high-voltage shunt reactors are studied through theoretical analysis, modeling calculation and field measurement, and the control methods and measures are discussed. The results show that the resistance is mainly due to the electromagnetic force between the steel blocks, and the acoustic wave level increases with the increase of nominal capacity. The acoustic energy is mainly concentrated in one third of the central frequency of 100 MHz;The sound pressure distribution of the reactor is very complicated, with slow speed and obvious sound interference. Its scale increases as the business voltage increases, but is not related to the workload. Voice interference should be considered when calculating the noise of electrical equipment, and the accuracy of calculation should be improved. The noise is mainly regulated by the sound insulation cover with a maximum volume of 20db. This research can provide important support for the planning, design, control and management of high-voltage power stations.
文摘The high frequency transient recovery voltage caused by usually switching operation of the circuit breakers, used on shunt reactor switching, have become a noticeable problem recently. For extension the service life time and normal operation of the circuit breakers, a well modified maintenance strategy is proposed. The field testing and experimental measurement showed the maintenance strategy proposed had been proved effectively and adopted in Taiwan Power Company.
基金supported by the National Natural Science Foundation of China (Grant Nos.50877061 and 51037005)
文摘This paper analyzes the fundamental frequency impedance presents a novel transmission line pilot protection scheme characteristic of a thyristor controlled series capacitor （TCSC） and based on fault component integrated impedance （FCII） calculated for a transmission line with TCSC and controllable shunt reactor （CSR）. The FCII is defined as the ratio of the sum of the fault component voltage phasors of a transmission line with TCSC and CSR to the sum of the fault component current phasors where all the phasors are determined at both line＇s terminals. It can be used to distinguish internal faults occurring on the line from external ones. If the fault is an external one the FCII reflects the line＇s capacitive impedance and has large value. If the fault is an internal one on the line the FCII reflects the impedance of the equivalent system and the line and is relatively small. The new pilot protection scheme can be easily set and has the fault phase selection ability and also it is not affected by the capacitive current and the fault transition resistance. It is not sensitive to compensation level and dynamics of TCSC and CSR. The effectiveness of the new scheme is validated against data obtained in ATP simulations and Northwest China 750 kV Project.
基金supported by State Grid Sichuan Electric Power Company science and technology project“Research on Key Technologies for Reclosing of High-Ratio New Energy Grid Connection Lines.”(Program No:52199723002Q).
文摘The integration of a high proportion of renewable energy introduces significant challenges for the adaptability of traditional fault nature identification methods.To address these challenges,this paper presents a novel fault nature identification method for renewable energy grid-connected interconnection lines,leveraging wavelet packet decomposition and voltage waveform time-frequency morphology comparison algorithms.First,the paper investigates the harmonic injection mechanism during non-full-phase operation following fault isolation in photovoltaic renewable energy systems,and examines the voltage characteristics of faulted phases in renewable energy scenarios.The analysis reveals that substantial differences exist in both the time and frequency domains of phase voltages before and after the extinction of transient faults,whereas permanent faults do not exhibit such variations.Building on this observation,the paper proposes a voltage time-frequency feature extraction method based on wavelet packet decomposition,wherein low-frequency waveform components are selected to characterize fault features.Subsequently,a fault nature identification method is introduced,based on a voltage waveform time-frequency morphology comparison.By employing a windowing technique to quantify waveform differences before and after arc extinction,this method effectively distinguishes between permanent and transient faults and accurately determines the arc extinction time.Finally,a 220 kV renewable energy grid connection line model is developed using PSCAD for verification.The results demonstrate that the proposed method is highly adaptable across various fault locations,transition resistances,and renewable energy control strategies,and can reliably identify fault nature in renewable energy grid connection scenarios.
文摘并联电抗器(以下简称电抗器)是在高压长距离输电工程中无功补偿的关键设备,电抗器故障对电网的安全稳定运行构成威胁。文中研究了浙江某特高压变电站1000 k V线路的电抗器故障现象,通过在线油中溶解气体分析发现电抗器发生电弧放电故障,然后通过局部放电在线监测和超声波局放检测等方法再次确认故障并定位到放电位置在电抗器A、X两柱,最后通过解体检查确认故障在电抗铁心柱表面地屏出出现放电。为了进一步追溯绝缘击穿的原因,文中对油中溶解气体突变、局部放电最大放电量与电网事件进行了相关性分析,发现电抗器中乙炔的突然增加与局部放电的发生时间有明显的相关性,延迟约2~3天,这个时间延迟反映了乙炔在油中的扩散过程。并联电抗器油中乙炔的突然增加与线路切换操作和电压突变存在时序关系,线路切换和电压突变导致电抗器绝缘击穿进而引发放电,是乙炔异常生长的根本原因。文中可为其他特高压变电站电抗器故障溯源提供思路。
文摘电磁型设备为基础的柔性交流输配电技术(electromagnetic equipment based flexible AC transmission&distribution technology,EME-FTDT)以常规电力设备为基础,利用机械开关、电力电子开关作为执行机构,结合控制技术,使其功能特性更灵活,以适应系统状态变化,提升交流输配电系统的安全性和经济性。中国电力科学研究院近二十多年来在EME-FTDT方面开展了大量研发工作,主导研制成功多项EME-FTDT装置。该文阐述了变压器柔性调控技术、断路器柔性控制技术、可控电抗器、可控避雷器、可控中性点接地装置、混合式可控移相器和配电网电磁型柔性互联装置等各类EME-FTDT装置的工作原理,系统总结了中国电力科学研究院在EME-FTDT领域的技术研发与工程应用进展。
