Rapid developments in EHV/UHV transmission systems require a deeper understanding of the mechanism of long air gap discharge.Leader propagation is one of the main processes in long gap breakdown.In this paper,the lead...Rapid developments in EHV/UHV transmission systems require a deeper understanding of the mechanism of long air gap discharge.Leader propagation is one of the main processes in long gap breakdown.In this paper,the leader propagation characteristics of real size±800 kV UHVDC transmission tower gaps under positive switching impulse voltages(185/2290μs)are investigated.An integrated observation platform consisting of an impulse voltage divider,a coaxial shunt,a high-speed video camera,and a set of integrated optical electric field sensors(IOES),is established.The waveforms of impulse voltage,discharge current,electric field variation at specific positions,and time-resolved photographs of discharge morphology are recorded.Axial leader velocity and the relationship between leader advancements and injected charge are obtained.The typical value of leader stable propagation velocity is 1.7–2.2 cm/μs,which varies slightly with the gap length and applied voltage amplitude.The leader velocity in the re-illumination process is much higher,and is seen as varying from 5 cm/μs to 30 cm/μs,with an average value around 10 cm/μs.The charge in leader channel per unit length is 20–40μC/m,which illustrates a near-direct proportion relationship between discharge current and leader velocity.The observed parameters are important for further simulation of the tower gap breakdown processes.展开更多
The paper deals with impulse switching function which are used as exciting functions of one- and multidimensional state-space models of power electronic converters. Obviously, these functions are harmonic but using po...The paper deals with impulse switching function which are used as exciting functions of one- and multidimensional state-space models of power electronic converters. Obviously, these functions are harmonic but using power converters they can be strongly non-harmonic, sometimes piecewise constants with zero spaces between them. Then, one deals with power series of time pulses. The impulse switching functions which are orthogonal ones can be derived from these series. The new impulse switching functions are created using Z-transform, inverse Z-transform and numerical series/sequences. The impulse switching functions created this way can be used for both steady- and transient state investigation of converters.展开更多
The increase of voltage level for AC and DC transmission systems requires some changes in the high voltage testing for Ultra High Voltage(UHV) equipment.After a short description of the coordination work in the standa...The increase of voltage level for AC and DC transmission systems requires some changes in the high voltage testing for Ultra High Voltage(UHV) equipment.After a short description of the coordination work in the standardization bodies the requirements for UHV equipment are mentioned.The main points concerning high voltage testing of UHV equipment are the impulse shape of standard lightning impulse voltage,the evaluation of the test voltage for impulses with oscillations or overshoot near the peak and the time parameter of switching impulses.The linearity check of the measuring devices,the proximity effect,the wet tests and the atmospheric correction factors are further points to be discussed concerning testing of UHV equipment.展开更多
This work investigates the input-to-state stability(ISS)problem for impulsive switched singular systems(ISSSs)with mismatched disturbances.In this paper,‘disturbance’is a general concept that includes model uncertai...This work investigates the input-to-state stability(ISS)problem for impulsive switched singular systems(ISSSs)with mismatched disturbances.In this paper,‘disturbance’is a general concept that includes model uncertainty,unknown system dynamic,external disturbance,etc.The modified uncertainty and disturbance estimator(UDE)-based control method is presented for singular systems and ISSSs,a virtual control is introduced to offset the effects of mismatched disturbances.On the basis of a discontinuous multiple Lyapunov functional and admissible edge-dependent average dwell time(AED-ADT)method,several sufficient conditions in terms of linear matrix inequalities(LMIs)are obtained to ensure that the closed-loop systems are regular,impulse-free and ISS.Finally,two examples are given to demonstrate the effectiveness of the proposed results.展开更多
In this paper,an optimal switch-time control problem is solved for a class of impulsive switched autonomous systems.The considered systems jump at the switching times,and the sequence of active subsystems is pre-speci...In this paper,an optimal switch-time control problem is solved for a class of impulsive switched autonomous systems.The considered systems jump at the switching times,and the sequence of active subsystems is pre-specified.The control variables consist of the impulse times and a set of scalars which determine the jump amplitudes.Moreover,the subsystems do not require a refractory period,which can bring more generality.Using the calculus of variation,the partial derivatives of the cost with respect to the control variables are derived,based on which the optimality conditions are given.Meanwhile,the obtained formulas can be used in some gradient descent algorithms to locate the optimal control variables.Finally,the viability of the proposed method is illustrated through two numerical examples.展开更多
This paper is devoted to the investigation of stability for a class of coupled impulsive Markovian jump reaction-diffusion systems on networks(CIMJRDSNs). By using graph theory, a systematic method is provided to cons...This paper is devoted to the investigation of stability for a class of coupled impulsive Markovian jump reaction-diffusion systems on networks(CIMJRDSNs). By using graph theory, a systematic method is provided to construct global Lyapunov functions for the CIMJRDSNs. Based on Lyapunov functions and stochastic analysis method, some novel stability principles associated with the topology property of the networks are established.展开更多
The problem of fault detection for a class of nonlinear impulsive switched systems is investigated in this paper. Fault detection filters are designed such that the augmented systems are stable, and the residual error...The problem of fault detection for a class of nonlinear impulsive switched systems is investigated in this paper. Fault detection filters are designed such that the augmented systems are stable, and the residual error signal generated by the filters guarantees the H∞ performance for disturbances and faults. Sufficient conditions for the design of fault detection(FD) filters are presented by linear matrix inequalities. Moreover, the filter gains are characterized according to a solution of a convex optimization. Finally, an example derived from a pulse-width-modulation-driven boost converter is given to illustrate the effectiveness of the FD design approach.展开更多
基金supported by the National Natural Science Foundation of China under Grant 51325703,51377094Fund of the National Priority Basic Research of China(2011CB209403)。
文摘Rapid developments in EHV/UHV transmission systems require a deeper understanding of the mechanism of long air gap discharge.Leader propagation is one of the main processes in long gap breakdown.In this paper,the leader propagation characteristics of real size±800 kV UHVDC transmission tower gaps under positive switching impulse voltages(185/2290μs)are investigated.An integrated observation platform consisting of an impulse voltage divider,a coaxial shunt,a high-speed video camera,and a set of integrated optical electric field sensors(IOES),is established.The waveforms of impulse voltage,discharge current,electric field variation at specific positions,and time-resolved photographs of discharge morphology are recorded.Axial leader velocity and the relationship between leader advancements and injected charge are obtained.The typical value of leader stable propagation velocity is 1.7–2.2 cm/μs,which varies slightly with the gap length and applied voltage amplitude.The leader velocity in the re-illumination process is much higher,and is seen as varying from 5 cm/μs to 30 cm/μs,with an average value around 10 cm/μs.The charge in leader channel per unit length is 20–40μC/m,which illustrates a near-direct proportion relationship between discharge current and leader velocity.The observed parameters are important for further simulation of the tower gap breakdown processes.
文摘The paper deals with impulse switching function which are used as exciting functions of one- and multidimensional state-space models of power electronic converters. Obviously, these functions are harmonic but using power converters they can be strongly non-harmonic, sometimes piecewise constants with zero spaces between them. Then, one deals with power series of time pulses. The impulse switching functions which are orthogonal ones can be derived from these series. The new impulse switching functions are created using Z-transform, inverse Z-transform and numerical series/sequences. The impulse switching functions created this way can be used for both steady- and transient state investigation of converters.
文摘The increase of voltage level for AC and DC transmission systems requires some changes in the high voltage testing for Ultra High Voltage(UHV) equipment.After a short description of the coordination work in the standardization bodies the requirements for UHV equipment are mentioned.The main points concerning high voltage testing of UHV equipment are the impulse shape of standard lightning impulse voltage,the evaluation of the test voltage for impulses with oscillations or overshoot near the peak and the time parameter of switching impulses.The linearity check of the measuring devices,the proximity effect,the wet tests and the atmospheric correction factors are further points to be discussed concerning testing of UHV equipment.
基金supported by the National Natural Science Foundation of China under Grant No.61977042the Foundation for Innovative Research Groups of National Natural Science Foundation of China under Grant No.61821004。
文摘This work investigates the input-to-state stability(ISS)problem for impulsive switched singular systems(ISSSs)with mismatched disturbances.In this paper,‘disturbance’is a general concept that includes model uncertainty,unknown system dynamic,external disturbance,etc.The modified uncertainty and disturbance estimator(UDE)-based control method is presented for singular systems and ISSSs,a virtual control is introduced to offset the effects of mismatched disturbances.On the basis of a discontinuous multiple Lyapunov functional and admissible edge-dependent average dwell time(AED-ADT)method,several sufficient conditions in terms of linear matrix inequalities(LMIs)are obtained to ensure that the closed-loop systems are regular,impulse-free and ISS.Finally,two examples are given to demonstrate the effectiveness of the proposed results.
基金supported by the National Natural Science Foundation of China under[Grant 61803238 and Grant 61873151].
文摘In this paper,an optimal switch-time control problem is solved for a class of impulsive switched autonomous systems.The considered systems jump at the switching times,and the sequence of active subsystems is pre-specified.The control variables consist of the impulse times and a set of scalars which determine the jump amplitudes.Moreover,the subsystems do not require a refractory period,which can bring more generality.Using the calculus of variation,the partial derivatives of the cost with respect to the control variables are derived,based on which the optimality conditions are given.Meanwhile,the obtained formulas can be used in some gradient descent algorithms to locate the optimal control variables.Finally,the viability of the proposed method is illustrated through two numerical examples.
基金supported by the National Natural Science Foundation of China under Grant Nos.61473097,11301090the State Key Program of Natural Science Foundation of China under Grant No.U1533202+2 种基金Shandong Independent Innovation and Achievements Transformation Fund under Grant No.2014CGZH1101Civil Aviation Administration of China under Grant No.MHRD20150104Guangxi Natural Science Foundation under Grant No.2016JJA110005
文摘This paper is devoted to the investigation of stability for a class of coupled impulsive Markovian jump reaction-diffusion systems on networks(CIMJRDSNs). By using graph theory, a systematic method is provided to construct global Lyapunov functions for the CIMJRDSNs. Based on Lyapunov functions and stochastic analysis method, some novel stability principles associated with the topology property of the networks are established.
基金supported by Northeast Dianli University(Nos.BSJXM09 and BSJXM10)
文摘The problem of fault detection for a class of nonlinear impulsive switched systems is investigated in this paper. Fault detection filters are designed such that the augmented systems are stable, and the residual error signal generated by the filters guarantees the H∞ performance for disturbances and faults. Sufficient conditions for the design of fault detection(FD) filters are presented by linear matrix inequalities. Moreover, the filter gains are characterized according to a solution of a convex optimization. Finally, an example derived from a pulse-width-modulation-driven boost converter is given to illustrate the effectiveness of the FD design approach.