Jin Hui - Academia.edu (original) (raw)
Papers by Jin Hui
2010 Asia-Pacific Power and Energy Engineering Conference, 2010
ABSTRACT Classification for short duration power quality disturbance (SDPQD) is the premise for e... more ABSTRACT Classification for short duration power quality disturbance (SDPQD) is the premise for electric power quality improvement. A new classification method for SDPQDs is proposed in this paper. It is based on partial similarity and scale zooming of the module time-frequency matrix (MTFM) by Stransform. All types of disturbances with different durations are standardized by time-frequency scale zooming. For templates, one certain part of the MTFM is extracted as the standard template which can represent the disturbance characters to the greatest extent. By comparing the corresponding part of the zoomed MTFM of the test signal with the standard templates, the disturbance type can be well classified according to the principle of maximum similarity. In this paper, six types of single power disturbances and two types of complex power disturbances are discussed and well classified, there is no need to use other complicated classifiers in the whole classification process. The simulation and field test results show that the proposed method is effective to classify disturbance signals in power system.
2012 IEEE 15th International Conference on Harmonics and Quality of Power, 2012
ABSTRACT The interharmonic group concept adopted by the IEC 61000-4-7 is very useful for addressi... more ABSTRACT The interharmonic group concept adopted by the IEC 61000-4-7 is very useful for addressing the need to monitor interharmonics in power systems. This paper shows that grouping spectral bins into interharmonics and harmonic components of 5Hz resolution could yield misleading information for cases where an interharmonic component's frequency is very close to a harmonic frequency. Since interharmonics in such cases can cause more severe waveform modulation, the interharmonic grouping scheme needs to be improved. A signal processing method that can separate interharmonic and harmonic components in close proximity is, therefore, proposed in this paper to address this need. Field data analysis showed that the proposed method was able to extract interharmonic and harmonic components correctly.
International Journal of Bifurcation and Chaos, 2004
In many models of pest control, increases in pest population due to birth are assumed to be conti... more In many models of pest control, increases in pest population due to birth are assumed to be continuous, but in fact, pest population reproduces only during a single period; at the same time, pesticides are often applied during the period. So in this paper we propose a ratio-dependent predator–prey model with birth pulse and pesticide pulse. Using the discrete dynamical system determined by the stroboscopic map, we obtain an exact periodic solution of systems which have Ricker functions or Beverton–Holt functions, and obtain the threshold conditions for their stability. Above the threshold, there is a characteristic sequence of bifurcations, leading to chaotic dynamics, which implies that the dynamical behaviors of the ratio-dependent predator–prey model with birth pulse and pesticide pulse are very complex, including small-amplitude oscillations, large-amplitude cycles and chaos. This suggests that birth pulse and pesticide pulse, in effect, provide a natural period or cyclicity tha...
IEEE Transactions on Power Delivery, 2010
This paper presents a new method to calculate the utility harmonic impedance and the harmonic vol... more This paper presents a new method to calculate the utility harmonic impedance and the harmonic voltage emission level at the point of common coupling (PCC). Since harmonic current at the PCC commonly exhibits negligible dependence on the utility side background harmonic, the variable item of the background harmonic in the deviation formulation can be eliminated by using the covariance characteristic of random vectors. And then, the utility harmonic impedance, the customer harmonic voltage emission level, and the background harmonic can be calculated in real time. Based on the analysis results of the simulation and the field test case, it shows that the proposed method is effective to reduce the calculation errors caused by the fluctuation of background harmonic, and satisfactory results can be achieved.
IEEE Transactions on Power Delivery, 2012
Determination of the utility harmonic impedance based on measurements is a significant task for u... more Determination of the utility harmonic impedance based on measurements is a significant task for utility powerquality improvement and management. Compared to those well-established, accurate invasive methods, the noninvasive methods are more desirable since they work with natural variations of the loads connected to the point of common coupling (PCC), so that no intentional disturbance is needed. However, the accuracy of these methods has to be improved. In this context, this paper first points out that the critical problem of the noninvasive methods is how to select the measurements that can be used with confidence for utility harmonic impedance calculation. Then, this paper presents a new measurement technique which is based on the complex data-based least-square regression, combined with two techniques of data selection. Simulation and field test results show that the proposed noninvasive method is practical and robust so that it can be used with confidence to determine the utility harmonic impedances. Index Terms-Harmonic impedance, noninvasive method, power quality (PQ). I. INTRODUCTION U TILITY harmonic impedance is a key factor for assessing harmonic emission levels in electrical power systems, since it can be successfully used to separate utility and customer harmonic contributions, so that responsibilities for network pollution can be identified. It is also used to check resonance situations for harmonic filter and reactive power compensation design. Due to this importance, utility harmonic impedance calculation has become a concern in the PQ area, so that, recently, several methods of determining harmonic contributions at the point of common coupling (PCC) are based on this parameter [1]-[6]. There are basically two types of methods used to determine the utility impedance [7]: invasive and noninvasive methods. The first methods are usually applied for islanding detection of renewables, control of active rectifiers, and other applications Manuscript
IEEE Transactions on Power Delivery, 2012
Interharmonic components can often be seen from the discrete Fourier transform (DFT) results of m... more Interharmonic components can often be seen from the discrete Fourier transform (DFT) results of measured voltage or current waveforms. These components may be caused by various factors, such as transient waveform distortions or noises. They are not necessarily related to the real interharmonics. This letter presents a simple method to verify the existence of a genuine interharmonic component contained in the DFT results. The method can also reveal the characteristics of the component. The method has been demonstrated on various field measurement data that contain genuine and false interharmonic components.
IEEE Transactions on Power Delivery, 2012
The interharmonic group concept adopted by the IEC 61000-4-7 is very useful for addressing the ne... more The interharmonic group concept adopted by the IEC 61000-4-7 is very useful for addressing the need to monitor interharmonics in power systems. This paper shows that grouping spectral bins into interharmonics and harmonic components of 5 Hz resolution could yield misleading information for cases where an interharmonic component's frequency is very close to a harmonic frequency. Since interharmonics in such cases can cause more severe waveform modulation, the interharmonic grouping scheme needs to be improved. A signal-processing method that can separate interharmonic and harmonic components in close proximity is, therefore, proposed in this paper to address this need. The method is based on the estimation of leakage values caused by interharmonics, at harmonic frequencies. Simulation studies and field data analysis showed that the proposed method was able to extract interharmonic and harmonic components correctly. Moreover, this paper also discusses how to apply the method to enhance the spectral grouping scheme of the IEC 610004-7.
Chaos, Solitons & Fractals, 2008
In this paper, we introduce and study a model of a Monod–Haldene type food chain chemostat with p... more In this paper, we introduce and study a model of a Monod–Haldene type food chain chemostat with periodically varying substrate. We investigate the subsystem with substrate and prey and study the stability of the periodic solutions, which are the boundary periodic solutions of the system. The stability analysis of the boundary periodic solution yields an invasion threshold. By use of
Acta Mathematicae Applicatae Sinica, English Series, 2005
Abstract In most models of population dynamics, diffusion between patches is assumed to be cont... more Abstract In most models of population dynamics, diffusion between patches is assumed to be continuous or discrete, but in practice many species diffuse only during a single period. In this paper we propose a single species model with impulsive diffusion between two patches, which provides a more natural description of population dynamics. By using the discrete dynamical system generated by a monotone, concave map for the population, we prove that the map always has a globally stable positive fixed point. This means that a single species system with impulsive diffusion always has a globally stable positive periodic solution. This result is further substantiated by numerical simulation. Under impulsive diffusion the single species survives in the two patches.
Acta Mathematica Sinica, English Series, 2004
The general system of differential equations describing predator-prey dynamics with impulsive eff... more The general system of differential equations describing predator-prey dynamics with impulsive effects is modified by the assumption that the coefficients are periodic functions of time. By use of standard techniques of bifurcation theory, it is known that this system has a positive periodic solution provided the time average of the predator's net uninhibited death rate is in a suitable range.The bifurcation is from the periodic solution of the time-dependent logistic equation for the prey (which results in the absence of predator).
2010 Asia-Pacific Power and Energy Engineering Conference, 2010
ABSTRACT Classification for short duration power quality disturbance (SDPQD) is the premise for e... more ABSTRACT Classification for short duration power quality disturbance (SDPQD) is the premise for electric power quality improvement. A new classification method for SDPQDs is proposed in this paper. It is based on partial similarity and scale zooming of the module time-frequency matrix (MTFM) by Stransform. All types of disturbances with different durations are standardized by time-frequency scale zooming. For templates, one certain part of the MTFM is extracted as the standard template which can represent the disturbance characters to the greatest extent. By comparing the corresponding part of the zoomed MTFM of the test signal with the standard templates, the disturbance type can be well classified according to the principle of maximum similarity. In this paper, six types of single power disturbances and two types of complex power disturbances are discussed and well classified, there is no need to use other complicated classifiers in the whole classification process. The simulation and field test results show that the proposed method is effective to classify disturbance signals in power system.
2012 IEEE 15th International Conference on Harmonics and Quality of Power, 2012
ABSTRACT The interharmonic group concept adopted by the IEC 61000-4-7 is very useful for addressi... more ABSTRACT The interharmonic group concept adopted by the IEC 61000-4-7 is very useful for addressing the need to monitor interharmonics in power systems. This paper shows that grouping spectral bins into interharmonics and harmonic components of 5Hz resolution could yield misleading information for cases where an interharmonic component's frequency is very close to a harmonic frequency. Since interharmonics in such cases can cause more severe waveform modulation, the interharmonic grouping scheme needs to be improved. A signal processing method that can separate interharmonic and harmonic components in close proximity is, therefore, proposed in this paper to address this need. Field data analysis showed that the proposed method was able to extract interharmonic and harmonic components correctly.
International Journal of Bifurcation and Chaos, 2004
In many models of pest control, increases in pest population due to birth are assumed to be conti... more In many models of pest control, increases in pest population due to birth are assumed to be continuous, but in fact, pest population reproduces only during a single period; at the same time, pesticides are often applied during the period. So in this paper we propose a ratio-dependent predator–prey model with birth pulse and pesticide pulse. Using the discrete dynamical system determined by the stroboscopic map, we obtain an exact periodic solution of systems which have Ricker functions or Beverton–Holt functions, and obtain the threshold conditions for their stability. Above the threshold, there is a characteristic sequence of bifurcations, leading to chaotic dynamics, which implies that the dynamical behaviors of the ratio-dependent predator–prey model with birth pulse and pesticide pulse are very complex, including small-amplitude oscillations, large-amplitude cycles and chaos. This suggests that birth pulse and pesticide pulse, in effect, provide a natural period or cyclicity tha...
IEEE Transactions on Power Delivery, 2010
This paper presents a new method to calculate the utility harmonic impedance and the harmonic vol... more This paper presents a new method to calculate the utility harmonic impedance and the harmonic voltage emission level at the point of common coupling (PCC). Since harmonic current at the PCC commonly exhibits negligible dependence on the utility side background harmonic, the variable item of the background harmonic in the deviation formulation can be eliminated by using the covariance characteristic of random vectors. And then, the utility harmonic impedance, the customer harmonic voltage emission level, and the background harmonic can be calculated in real time. Based on the analysis results of the simulation and the field test case, it shows that the proposed method is effective to reduce the calculation errors caused by the fluctuation of background harmonic, and satisfactory results can be achieved.
IEEE Transactions on Power Delivery, 2012
Determination of the utility harmonic impedance based on measurements is a significant task for u... more Determination of the utility harmonic impedance based on measurements is a significant task for utility powerquality improvement and management. Compared to those well-established, accurate invasive methods, the noninvasive methods are more desirable since they work with natural variations of the loads connected to the point of common coupling (PCC), so that no intentional disturbance is needed. However, the accuracy of these methods has to be improved. In this context, this paper first points out that the critical problem of the noninvasive methods is how to select the measurements that can be used with confidence for utility harmonic impedance calculation. Then, this paper presents a new measurement technique which is based on the complex data-based least-square regression, combined with two techniques of data selection. Simulation and field test results show that the proposed noninvasive method is practical and robust so that it can be used with confidence to determine the utility harmonic impedances. Index Terms-Harmonic impedance, noninvasive method, power quality (PQ). I. INTRODUCTION U TILITY harmonic impedance is a key factor for assessing harmonic emission levels in electrical power systems, since it can be successfully used to separate utility and customer harmonic contributions, so that responsibilities for network pollution can be identified. It is also used to check resonance situations for harmonic filter and reactive power compensation design. Due to this importance, utility harmonic impedance calculation has become a concern in the PQ area, so that, recently, several methods of determining harmonic contributions at the point of common coupling (PCC) are based on this parameter [1]-[6]. There are basically two types of methods used to determine the utility impedance [7]: invasive and noninvasive methods. The first methods are usually applied for islanding detection of renewables, control of active rectifiers, and other applications Manuscript
IEEE Transactions on Power Delivery, 2012
Interharmonic components can often be seen from the discrete Fourier transform (DFT) results of m... more Interharmonic components can often be seen from the discrete Fourier transform (DFT) results of measured voltage or current waveforms. These components may be caused by various factors, such as transient waveform distortions or noises. They are not necessarily related to the real interharmonics. This letter presents a simple method to verify the existence of a genuine interharmonic component contained in the DFT results. The method can also reveal the characteristics of the component. The method has been demonstrated on various field measurement data that contain genuine and false interharmonic components.
IEEE Transactions on Power Delivery, 2012
The interharmonic group concept adopted by the IEC 61000-4-7 is very useful for addressing the ne... more The interharmonic group concept adopted by the IEC 61000-4-7 is very useful for addressing the need to monitor interharmonics in power systems. This paper shows that grouping spectral bins into interharmonics and harmonic components of 5 Hz resolution could yield misleading information for cases where an interharmonic component's frequency is very close to a harmonic frequency. Since interharmonics in such cases can cause more severe waveform modulation, the interharmonic grouping scheme needs to be improved. A signal-processing method that can separate interharmonic and harmonic components in close proximity is, therefore, proposed in this paper to address this need. The method is based on the estimation of leakage values caused by interharmonics, at harmonic frequencies. Simulation studies and field data analysis showed that the proposed method was able to extract interharmonic and harmonic components correctly. Moreover, this paper also discusses how to apply the method to enhance the spectral grouping scheme of the IEC 610004-7.
Chaos, Solitons & Fractals, 2008
In this paper, we introduce and study a model of a Monod–Haldene type food chain chemostat with p... more In this paper, we introduce and study a model of a Monod–Haldene type food chain chemostat with periodically varying substrate. We investigate the subsystem with substrate and prey and study the stability of the periodic solutions, which are the boundary periodic solutions of the system. The stability analysis of the boundary periodic solution yields an invasion threshold. By use of
Acta Mathematicae Applicatae Sinica, English Series, 2005
Abstract In most models of population dynamics, diffusion between patches is assumed to be cont... more Abstract In most models of population dynamics, diffusion between patches is assumed to be continuous or discrete, but in practice many species diffuse only during a single period. In this paper we propose a single species model with impulsive diffusion between two patches, which provides a more natural description of population dynamics. By using the discrete dynamical system generated by a monotone, concave map for the population, we prove that the map always has a globally stable positive fixed point. This means that a single species system with impulsive diffusion always has a globally stable positive periodic solution. This result is further substantiated by numerical simulation. Under impulsive diffusion the single species survives in the two patches.
Acta Mathematica Sinica, English Series, 2004
The general system of differential equations describing predator-prey dynamics with impulsive eff... more The general system of differential equations describing predator-prey dynamics with impulsive effects is modified by the assumption that the coefficients are periodic functions of time. By use of standard techniques of bifurcation theory, it is known that this system has a positive periodic solution provided the time average of the predator's net uninhibited death rate is in a suitable range.The bifurcation is from the periodic solution of the time-dependent logistic equation for the prey (which results in the absence of predator).