During the test on transient pressure signal in explosion field,false trigger caused by field interference can lead to test failure.To improve the stability of test system,a signal detection and recognition technology...During the test on transient pressure signal in explosion field,false trigger caused by field interference can lead to test failure.To improve the stability of test system,a signal detection and recognition technology is proposed for transient pressure test system.In the process of signal acquisition,firstly,electrical levels are monitored in real time to find effective abrupt changes and mark them;then the effective data segments are detecdted totected;thus the effective signals can be acquired in turn finally.The experimental results show that the shock wave signal can be collected effectively and the reliability of the test system can be improved after removal of interferences.展开更多
The phase change between periodic signals is regular. Research on the regular phenomenon between periodic signals is helpful to improve the precision of some measurements and develop some new measurement methods. So i...The phase change between periodic signals is regular. Research on the regular phenomenon between periodic signals is helpful to improve the precision of some measurements and develop some new measurement methods. So it is necessary to analyze the characteristics of the greatest common factor frequency and the least common multiple period universally existing in periodic signals. The regulation of the quantitative phase shift resolution between periodic signals is presented.The cause of difference in phase characteristics between periodic signals is explained well. In this paper we propose different application prospects based on the regular phenomenon between periodic signals, with focusing on the methods for high precision frequency measurement and transient stability measurement. The experimental results are satisfactory.展开更多
Estimation of model parameter for transient signal is very important in many aspects. This paper presents a new Markov ARMA model Q-slice estimation algorithm for transient signal based on bispectrum. Simulation resul...Estimation of model parameter for transient signal is very important in many aspects. This paper presents a new Markov ARMA model Q-slice estimation algorithm for transient signal based on bispectrum. Simulation results show that this new method has some special features, such as higher estimation precision, lower amount of calculation, higher fitting effect even in lower signal-to-noise ratio (SNR) situation.展开更多
Many dynamic signals of mining machines are transient, such as load signals when roadheader’s cutting head being cut-in or cut-out and response signals produced by these loads.For these transient signals, the traditi...Many dynamic signals of mining machines are transient, such as load signals when roadheader’s cutting head being cut-in or cut-out and response signals produced by these loads.For these transient signals, the traditional Fourier analysis method is quite inadequate.The limitations of analysis, resolution by using Short-Time Fourier Transform (STFT) on them were discussed in this paper. Because of wavelet transform having the characteristics of flexible window and multiresolution analysis, we try to apply it to analyse these transient signal. In order to give a pratical example,using D18 wavelet and Mallat’s tree algorithm with MATLAB, the discrete wavelet transform was calculated for the simulating response signals of a three-degree-of freedom vibration system when it Was under impulse and random excitations. The results of the wavelet transform made clear its effectiveness and superiority in analysing transient signals of mining machines.展开更多
直流母线电容作为电机驱动变换器中最薄弱的元件之一,其老化会导致系统故障的概率增大,因此对电容老化进行在线监测至关重要。针对现有监测方法存在经济性差、采样频率高、影响系统正常运行等问题,提出一种基于长周期暂态信号分析的电...直流母线电容作为电机驱动变换器中最薄弱的元件之一,其老化会导致系统故障的概率增大,因此对电容老化进行在线监测至关重要。针对现有监测方法存在经济性差、采样频率高、影响系统正常运行等问题,提出一种基于长周期暂态信号分析的电容在线监测方法,用于估计电机驱动变换器直流母线等值串联电容(equivalent series capacitance,ESC)。首先,根据系统负载切换过程建立共节点感-容等值暂态模型,分析长周期暂态信号特点。其次,推导基于长周期暂态信号的在线监测模型,确定监测程序启动判定条件。然后,提出一种基于多项式重构的电容电流基线校准方法,消除传感器零漂影响,提高监测精度。最后,仿真和实验表明所提出方法的监测精度满足电容监测的要求。展开更多
Precise fault location plays an important role in the reliability of modern power systems.With the in-creasing penetration of renewable energy sources,the power system experiences a decrease in system inertia and alte...Precise fault location plays an important role in the reliability of modern power systems.With the in-creasing penetration of renewable energy sources,the power system experiences a decrease in system inertia and alterations in steady-state characteristics following a fault occurrence.Most existing single-ended phasor domain methods assume a certain impedance of the remote-end system or consistent current phases at both ends.These problems present challenges to the applicability of con-ventional phasor-domain location methods.This paper presents a novel single-ended time domain fault location method for single-phase-to-ground faults,one which fully considers the distributed parameters of the line model.The fitting of transient signals in the time domain is real-ized to extract the instantaneous amplitude and phase.Then,to eliminate the error caused by assumptions of lumped series resistance in the Bergeron model,an im-proved numerical derivation is presented for the distrib-uted parameter line model.The instantaneous symmet-rical components are extracted for decoupling and inverse transformation of three-phase recording data.Based on the above,the equation of instantaneous phase constraint is established to effectively identify the fault location.The proposed location method reduces the negative effects of fault resistance and the uncertainty of remote end pa-rameters when relying on one-terminal data for localiza-tion.Additionally,the proposed fault analysis methods have the ability to adapt to transient processes in power systems.Through comparisons with existing methods in three different systems,the fault position is correctly identified within an error of 1%.Also,the results are not affected by sampling rates,data windows,fault inception angles,and load conditions. Index Terms—Fault location,distributed parameter line model,transient signal,renewable energy,instantaneous phase.展开更多
For the shock wave overpressure signal measurement of explosion field, the type and equivalent of the ammunition as well as the distance from test nodes to ground zero have a great influence on the characteristics of ...For the shock wave overpressure signal measurement of explosion field, the type and equivalent of the ammunition as well as the distance from test nodes to ground zero have a great influence on the characteristics of shock wave signal. To ensure that shock wave signal with different characteristic parameters can be collected completely in the test of shooting range, a tran- sient pressure signal storage system with configurable parameters is presented. In order to meet the requirements of different test nodes, the system can set parameters of all test nodes by wireless communication in explosion field. The feasibility and re- liability of the system are fully verified through transient pressure measurement in explosion field.展开更多
基金The 11th Postgraduate Technology Innovation Project of North University of China(No.20141142)
文摘During the test on transient pressure signal in explosion field,false trigger caused by field interference can lead to test failure.To improve the stability of test system,a signal detection and recognition technology is proposed for transient pressure test system.In the process of signal acquisition,firstly,electrical levels are monitored in real time to find effective abrupt changes and mark them;then the effective data segments are detecdted totected;thus the effective signals can be acquired in turn finally.The experimental results show that the shock wave signal can be collected effectively and the reliability of the test system can be improved after removal of interferences.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10978017 and 61201288)
文摘The phase change between periodic signals is regular. Research on the regular phenomenon between periodic signals is helpful to improve the precision of some measurements and develop some new measurement methods. So it is necessary to analyze the characteristics of the greatest common factor frequency and the least common multiple period universally existing in periodic signals. The regulation of the quantitative phase shift resolution between periodic signals is presented.The cause of difference in phase characteristics between periodic signals is explained well. In this paper we propose different application prospects based on the regular phenomenon between periodic signals, with focusing on the methods for high precision frequency measurement and transient stability measurement. The experimental results are satisfactory.
文摘Estimation of model parameter for transient signal is very important in many aspects. This paper presents a new Markov ARMA model Q-slice estimation algorithm for transient signal based on bispectrum. Simulation results show that this new method has some special features, such as higher estimation precision, lower amount of calculation, higher fitting effect even in lower signal-to-noise ratio (SNR) situation.
文摘Many dynamic signals of mining machines are transient, such as load signals when roadheader’s cutting head being cut-in or cut-out and response signals produced by these loads.For these transient signals, the traditional Fourier analysis method is quite inadequate.The limitations of analysis, resolution by using Short-Time Fourier Transform (STFT) on them were discussed in this paper. Because of wavelet transform having the characteristics of flexible window and multiresolution analysis, we try to apply it to analyse these transient signal. In order to give a pratical example,using D18 wavelet and Mallat’s tree algorithm with MATLAB, the discrete wavelet transform was calculated for the simulating response signals of a three-degree-of freedom vibration system when it Was under impulse and random excitations. The results of the wavelet transform made clear its effectiveness and superiority in analysing transient signals of mining machines.
文摘直流母线电容作为电机驱动变换器中最薄弱的元件之一,其老化会导致系统故障的概率增大,因此对电容老化进行在线监测至关重要。针对现有监测方法存在经济性差、采样频率高、影响系统正常运行等问题,提出一种基于长周期暂态信号分析的电容在线监测方法,用于估计电机驱动变换器直流母线等值串联电容(equivalent series capacitance,ESC)。首先,根据系统负载切换过程建立共节点感-容等值暂态模型,分析长周期暂态信号特点。其次,推导基于长周期暂态信号的在线监测模型,确定监测程序启动判定条件。然后,提出一种基于多项式重构的电容电流基线校准方法,消除传感器零漂影响,提高监测精度。最后,仿真和实验表明所提出方法的监测精度满足电容监测的要求。
文摘Precise fault location plays an important role in the reliability of modern power systems.With the in-creasing penetration of renewable energy sources,the power system experiences a decrease in system inertia and alterations in steady-state characteristics following a fault occurrence.Most existing single-ended phasor domain methods assume a certain impedance of the remote-end system or consistent current phases at both ends.These problems present challenges to the applicability of con-ventional phasor-domain location methods.This paper presents a novel single-ended time domain fault location method for single-phase-to-ground faults,one which fully considers the distributed parameters of the line model.The fitting of transient signals in the time domain is real-ized to extract the instantaneous amplitude and phase.Then,to eliminate the error caused by assumptions of lumped series resistance in the Bergeron model,an im-proved numerical derivation is presented for the distrib-uted parameter line model.The instantaneous symmet-rical components are extracted for decoupling and inverse transformation of three-phase recording data.Based on the above,the equation of instantaneous phase constraint is established to effectively identify the fault location.The proposed location method reduces the negative effects of fault resistance and the uncertainty of remote end pa-rameters when relying on one-terminal data for localiza-tion.Additionally,the proposed fault analysis methods have the ability to adapt to transient processes in power systems.Through comparisons with existing methods in three different systems,the fault position is correctly identified within an error of 1%.Also,the results are not affected by sampling rates,data windows,fault inception angles,and load conditions. Index Terms—Fault location,distributed parameter line model,transient signal,renewable energy,instantaneous phase.
基金The 11th Postgraduate Technological Innovation Project of North University of China(No.20141150)
文摘For the shock wave overpressure signal measurement of explosion field, the type and equivalent of the ammunition as well as the distance from test nodes to ground zero have a great influence on the characteristics of shock wave signal. To ensure that shock wave signal with different characteristic parameters can be collected completely in the test of shooting range, a tran- sient pressure signal storage system with configurable parameters is presented. In order to meet the requirements of different test nodes, the system can set parameters of all test nodes by wireless communication in explosion field. The feasibility and re- liability of the system are fully verified through transient pressure measurement in explosion field.
