Busbar differential relaying method based on combined amplitude and phase information of high frequency transient currents is put forward in this paper for the speed and reliability problems of busbar protection based...Busbar differential relaying method based on combined amplitude and phase information of high frequency transient currents is put forward in this paper for the speed and reliability problems of busbar protection based on fundamental frequency. Under the analysis of features of bus high frequency differential currents, complex wavelet analysis is used to extract the amplitude and phase features of 1/4 period high frequency differential currents, and amplitude and phase information are used to form the polar coordinates. Bus fault is identified intuitively and precisely according to polar locus differences. This polar coordinates represented busbar differential protection scheme based on high frequency transient signals can not only avoid TA saturation, realizing quick protection, lots of PSCAD/EMTDC simulations also show that this busbar differential protection scheme works well under different fault conditions.展开更多
在电力高压站高压隔离开关动作时,产生的特快速暂态过电压(very fast transient overvoltage,VFTO)耦合到二次电缆传输信号中,会造成测量的不准确和设备的误动作。以提高继电保护抗干扰能力为目的,建立并分析“接地网-二次电缆-智能组...在电力高压站高压隔离开关动作时,产生的特快速暂态过电压(very fast transient overvoltage,VFTO)耦合到二次电缆传输信号中,会造成测量的不准确和设备的误动作。以提高继电保护抗干扰能力为目的,建立并分析“接地网-二次电缆-智能组件”的耦合路径,根据电力系统理想采样点的信号特征,提出应对接地网电位差干扰的算法,采用启动元件和判定元件快速判断采样值是否为干扰信号,根据高压隔离开关动作引起的接地网电位差干扰信号幅值高、上升时间短和频带范围宽的暂态特性,采用小波变换作为滤波算法。仿真实验结果表明,此滤波算法能够有效地滤除隔离开关动作引起的接地网电位差干扰信号,均方根误差减少91.6%,信噪比提高138.5%,保证了继电保护数据测量的准确性,提高了电力系统继电保护的可靠性。展开更多
In view of the fact that the wavelet packet transform(WPT) can only weakly detect the occurrence of fault, this paper applies a fault diagnosis algorithm including wavelet packet transform and principal component anal...In view of the fact that the wavelet packet transform(WPT) can only weakly detect the occurrence of fault, this paper applies a fault diagnosis algorithm including wavelet packet transform and principal component analysis(PCA) to the inverter-side fault diagnosis of multi-terminal hybrid highvoltage direct current(HVDC) network, which can significantly improve the speed and accuracy of fault diagnosis. Firstly, current amplitude and current slope are used to sample the data,and the WPT is used to extract the energy spectrum of the signal. Secondly, an energy matrix is constructed, and the PCA method is used to calculate whether the squared prediction error(SPE) statistics of various signals that can reflect the degree of deviation of the measured value from the principal component model at a certain time exceed the limit to judge the occurrence of the fault. Further, its maximum value is compared to determine the fault types. Finally, based on a large number of MATLAB/Simulink simulation results, it is shown that the PCA method using the current slope as the sampled data can detect the occurrence of a ground fault with small transition resistance within 2 ms, and identify the fault types within 10 ms,without being affected by the sampling frequency.展开更多
文摘Busbar differential relaying method based on combined amplitude and phase information of high frequency transient currents is put forward in this paper for the speed and reliability problems of busbar protection based on fundamental frequency. Under the analysis of features of bus high frequency differential currents, complex wavelet analysis is used to extract the amplitude and phase features of 1/4 period high frequency differential currents, and amplitude and phase information are used to form the polar coordinates. Bus fault is identified intuitively and precisely according to polar locus differences. This polar coordinates represented busbar differential protection scheme based on high frequency transient signals can not only avoid TA saturation, realizing quick protection, lots of PSCAD/EMTDC simulations also show that this busbar differential protection scheme works well under different fault conditions.
文摘在电力高压站高压隔离开关动作时,产生的特快速暂态过电压(very fast transient overvoltage,VFTO)耦合到二次电缆传输信号中,会造成测量的不准确和设备的误动作。以提高继电保护抗干扰能力为目的,建立并分析“接地网-二次电缆-智能组件”的耦合路径,根据电力系统理想采样点的信号特征,提出应对接地网电位差干扰的算法,采用启动元件和判定元件快速判断采样值是否为干扰信号,根据高压隔离开关动作引起的接地网电位差干扰信号幅值高、上升时间短和频带范围宽的暂态特性,采用小波变换作为滤波算法。仿真实验结果表明,此滤波算法能够有效地滤除隔离开关动作引起的接地网电位差干扰信号,均方根误差减少91.6%,信噪比提高138.5%,保证了继电保护数据测量的准确性,提高了电力系统继电保护的可靠性。
基金supported by the National Natural Science Foundation of China-State Grid Joint Fund for Smart Grid (No. U2066210)。
文摘In view of the fact that the wavelet packet transform(WPT) can only weakly detect the occurrence of fault, this paper applies a fault diagnosis algorithm including wavelet packet transform and principal component analysis(PCA) to the inverter-side fault diagnosis of multi-terminal hybrid highvoltage direct current(HVDC) network, which can significantly improve the speed and accuracy of fault diagnosis. Firstly, current amplitude and current slope are used to sample the data,and the WPT is used to extract the energy spectrum of the signal. Secondly, an energy matrix is constructed, and the PCA method is used to calculate whether the squared prediction error(SPE) statistics of various signals that can reflect the degree of deviation of the measured value from the principal component model at a certain time exceed the limit to judge the occurrence of the fault. Further, its maximum value is compared to determine the fault types. Finally, based on a large number of MATLAB/Simulink simulation results, it is shown that the PCA method using the current slope as the sampled data can detect the occurrence of a ground fault with small transition resistance within 2 ms, and identify the fault types within 10 ms,without being affected by the sampling frequency.
