The Experts below are selected from a list of 1428 Experts worldwide ranked by ideXlab platform

H.k. Verma - One of the best experts on this subject based on the ideXlab platform.

  • effects of line length fault resistance and dc filters on hvdc line protection based on Signum Function of transient energy
    International Review of Electrical Engineering-iree, 2019
    Co-Authors: H.k. Verma
    Abstract:

    Protection schemes and algorithms of high-voltage direct-current (HVDC) lines are known to be affected by the line length, fault resistance values and dc filter type. The authors have conducted a simulation study on a monopolar HVDC line in order to evaluate the effect of the three parameters on a protection algorithm based on Signum Function of transient energy. A simulation study has been carried out using PSCAD/EMTDC. The line length has been varied from 200 km to 2000 km, and the fault resistance from 0 Ω to 2000 Ω. Three types of dc filters are considered. The results are presented and analyzed in the paper. For the effect of line length on the fault classification time, the latter varies with the former both for internal and external faults. Increase in the fault resistance leads to a small increase in the fault classification time for internal faults and a larger increase for external faults. Since protection is not to be initiated on external fault, increased classification time for external faults has no bad consequences. Classification time for all the three type of dc filters for internal faults is the same for all the type of dc filters except for sending end dc fault with triple tuned filter.

  • Incremental Power Improves Relay Selectivity to Transmission Line Faults
    Journal of The Institution of Engineers (India): Series B, 2019
    Co-Authors: Abdul Waheed Kumar, H.k. Verma, Shashank Singh
    Abstract:

    A research work published in 2014 reported a novel relaying principle for protection of transmission lines using Signum Function of instantaneous power flows at the two ends of the line. Subsequently, a detailed study of this relaying principle to evaluate its selectivity (sensitivity to detect all internal faults and stability on external faults and no-fault condition) was carried out and results were reported in another paper. The present paper reports a considerable improvement in the relay selectivity by using Signum Function of incremental powers at the two ends of the line. This principle of fault detection and classification has been tested by simulating a 230 kV, 50 Hz five-bus system in PSCAD/EMTDC. The various parameters of the study include dc offset, line load, location and type of fault and fault resistance. Various fault resistance values ranging from 0.01 ohm (solid fault) to 1000 ohms have been taken for simulation. The study has been carried out on two types of lines: a line between a source bus and a load bus, and a line connected between two source buses, and for two line lengths, namely 100 km and 200 km. Results of this detailed study are presented in the paper. The final outcome of the study is that the relay is able to detect all internal faults with all fault resistance values and all line loads. However, it operates on some external faults near the load bus, that is, has some transient overreach, for the first type of line. This tendency of operating on external faults is also lower than that with the instantaneous power-based relay.

  • improved relay algorithm for detection and classification of transmission line faults using Signum Function of instantaneous power
    2017 3rd International Conference on Condition Assessment Techniques in Electrical Systems (CATCON), 2017
    Co-Authors: Abdul Waheed Kumar, H.k. Verma, Shashank Singh
    Abstract:

    A novel algorithm on fault detection and classification employing instantaneous power using Signum Function was reported in 2014 [6]. However, the performance analysis was not exhaustive and the effect of the line load on the relay behavior was not reported. A detailed investigation has been carried out by the authors of this paper to study the effectiveness of the technique using instantaneous power flows and the relay algorithm has also been improved. The principle of fault detection and classification has been tested by simulating a 230 kV, 50 Hz, five-bus system in PSCAD/EMTDC. The various parameters of the study include dc offset, line load, location of fault and fault resistance. Various fault resistance values ranging from 0.01 ohms to 1000 ohms have been taken for simulation. The study has been carried on two types of lines: a line between a source bus and a load bus and a line connected between two source buses. Results of the study are presented in this paper. The final outcome of the study is that the technique works successfully with low fault resistance values and low line loading but fails to detect fault with high resistance faults occurring on heavily loaded lines.

Zhigang Zeng - One of the best experts on this subject based on the ideXlab platform.

  • A simple no-equilibrium chaotic system with only one Signum Function for generating multidirectional variable hidden attractors and its hardware implementation
    Chaos, 2020
    Co-Authors: Sen Zhang, Xiaoping Wang, Zhigang Zeng
    Abstract:

    This paper proposes a simple no-equilibrium chaotic system with only one Signum Function as compared with the existing no-equilibrium chaotic ones with at least one quadratic or higher nonlinearity. The system has the offset boosting of three variables through adjusting the corresponding controlled constants. The resulting hidden attractors can be distributed in a 1D line, a 2D lattice, a 3D grid, and even in an arbitrary location of the phase space. Particularly, a hidden chaotic bursting oscillation is also observed in this system, which is an uncommon phenomenon. In addition, complex hidden dynamics is investigated via phase portraits, time series, Kaplan–Yorke dimensions, bifurcation diagrams, Lyapunov exponents, and two-parameter bifurcation diagrams. Then, a very simple hardware circuit without any multiplier is fabricated, and the experimental results are presented to demonstrate theoretical analyses and numerical simulations. Furthermore, the randomness test of the chaotic pseudo-random sequence g...

  • a simple no equilibrium chaotic system with only one Signum Function for generating multidirectional variable hidden attractors and its hardware implementation
    Chaos, 2020
    Co-Authors: Sen Zhang, Xiaoping Wang, Zhigang Zeng
    Abstract:

    This paper proposes a simple no-equilibrium chaotic system with only one Signum Function as compared with the existing no-equilibrium chaotic ones with at least one quadratic or higher nonlinearity. The system has the offset boosting of three variables through adjusting the corresponding controlled constants. The resulting hidden attractors can be distributed in a 1D line, a 2D lattice, a 3D grid, and even in an arbitrary location of the phase space. Particularly, a hidden chaotic bursting oscillation is also observed in this system, which is an uncommon phenomenon. In addition, complex hidden dynamics is investigated via phase portraits, time series, Kaplan-Yorke dimensions, bifurcation diagrams, Lyapunov exponents, and two-parameter bifurcation diagrams. Then, a very simple hardware circuit without any multiplier is fabricated, and the experimental results are presented to demonstrate theoretical analyses and numerical simulations. Furthermore, the randomness test of the chaotic pseudo-random sequence generated by the system is tested by the National Institute of Standards and Technology test suite. The tested results show that the proposed system has good randomness, thus being suitable for chaos-based applications such as secure communication and image encryption.

L. C. Fu - One of the best experts on this subject based on the ideXlab platform.

  • Adaptive backstepping PI sliding-mode control for interior permanent magnet synchronous motor drive systems
    Proceedings of the American Control Conference, 2011
    Co-Authors: C. K. Lin, T.-h. Liu, L. C. Fu
    Abstract:

    An adaptive backstepping PI sliding-mode control is proposed for speed control of the drive of an interior permanent magnet synchronous motor (IPMSM) subjected to load disturbances. First, a nonlinear model with uncertainties is derived for the IPMSM, and then an adaptive backstepping sliding-mode controller incorporating a linear load torque estimator is designed. Next, the parametric uncertainties of the model are handled with adaptive laws in the design of the controller. To attenuate the chattering problem without sacrificing the feature of the sliding-mode control, an adaptive PI-saturation Function is used to approximate the Signum Function within the boundary layer. Asymptotic stability of the proposed control method is proven by Lyapunov stability theory and Barbalat's lemma. A digital signal processor, TMS320LF2407, is adopted to implement the proposed control scheme. The experimental results show that the proposed system can effectively reduce the chattering phenomenon and has fast transient response, good load disturbance rejection response, and good tracking response. © 2011 AACC American Automatic Control Council.

Sen Zhang - One of the best experts on this subject based on the ideXlab platform.

  • A simple no-equilibrium chaotic system with only one Signum Function for generating multidirectional variable hidden attractors and its hardware implementation
    Chaos, 2020
    Co-Authors: Sen Zhang, Xiaoping Wang, Zhigang Zeng
    Abstract:

    This paper proposes a simple no-equilibrium chaotic system with only one Signum Function as compared with the existing no-equilibrium chaotic ones with at least one quadratic or higher nonlinearity. The system has the offset boosting of three variables through adjusting the corresponding controlled constants. The resulting hidden attractors can be distributed in a 1D line, a 2D lattice, a 3D grid, and even in an arbitrary location of the phase space. Particularly, a hidden chaotic bursting oscillation is also observed in this system, which is an uncommon phenomenon. In addition, complex hidden dynamics is investigated via phase portraits, time series, Kaplan–Yorke dimensions, bifurcation diagrams, Lyapunov exponents, and two-parameter bifurcation diagrams. Then, a very simple hardware circuit without any multiplier is fabricated, and the experimental results are presented to demonstrate theoretical analyses and numerical simulations. Furthermore, the randomness test of the chaotic pseudo-random sequence g...

  • a simple no equilibrium chaotic system with only one Signum Function for generating multidirectional variable hidden attractors and its hardware implementation
    Chaos, 2020
    Co-Authors: Sen Zhang, Xiaoping Wang, Zhigang Zeng
    Abstract:

    This paper proposes a simple no-equilibrium chaotic system with only one Signum Function as compared with the existing no-equilibrium chaotic ones with at least one quadratic or higher nonlinearity. The system has the offset boosting of three variables through adjusting the corresponding controlled constants. The resulting hidden attractors can be distributed in a 1D line, a 2D lattice, a 3D grid, and even in an arbitrary location of the phase space. Particularly, a hidden chaotic bursting oscillation is also observed in this system, which is an uncommon phenomenon. In addition, complex hidden dynamics is investigated via phase portraits, time series, Kaplan-Yorke dimensions, bifurcation diagrams, Lyapunov exponents, and two-parameter bifurcation diagrams. Then, a very simple hardware circuit without any multiplier is fabricated, and the experimental results are presented to demonstrate theoretical analyses and numerical simulations. Furthermore, the randomness test of the chaotic pseudo-random sequence generated by the system is tested by the National Institute of Standards and Technology test suite. The tested results show that the proposed system has good randomness, thus being suitable for chaos-based applications such as secure communication and image encryption.

Karl Henrik Johansson - One of the best experts on this subject based on the ideXlab platform.

  • Finite-Time Attitude Synchronization With Distributed Discontinuous Protocols
    IEEE Transactions on Automatic Control, 2018
    Co-Authors: Silun Zhang, Antonio Adaldo, Johan Thunberg, Xiaoming Hu, Karl Henrik Johansson
    Abstract:

    The finite-time attitude synchronization problem is considered in this paper, where the rotation of each rigid body is expressed using the axis-angle representation. Two discontinuous and distributed controllers using the vectorized Signum Function are proposed, which guarantee almost global and local convergence, respectively. Filippov solutions and nonsmooth analysis techniques are adopted to handle the discontinuities. Sufficient conditions are provided to guarantee finite-time convergence and boundedness of the solutions. Simulation examples are provided to verify the performances of the control protocols designed in this paper.

  • Finite-time attitude synchronization with a discontinuous protocol
    2017 13th IEEE International Conference on Control & Automation (ICCA), 2017
    Co-Authors: Silun Zhang, Antonio Adaldo, Xiaoming Hu, Karl Henrik Johansson
    Abstract:

    A finite-time attitude synchronization problem is considered in this paper where the rotation of each rigid body is expressed using the axis-angle representation. One simple discontinuous and distributed controller using the vectorized Signum Function is proposed. This controller only involves the sign of the state differences of adjacent neighbors. In order to avoid the singularity introduced by the axis-angular representation, an extra constraint is added to the initial condition. It is proved that for some initial conditions, the control law achieves finite-time attitude synchronization. One simulated example is provided to verify the usage of the control protocol designed in this paper.

  • ICCA - Finite-time attitude synchronization with a discontinuous protocol
    2017 13th IEEE International Conference on Control & Automation (ICCA), 2017
    Co-Authors: Silun Zhang, Antonio Adaldo, Xiaoming Hu, Karl Henrik Johansson
    Abstract:

    A finite-time attitude synchronization problem is considered in this paper where the rotation of each rigid body is expressed using the axis-angle representation. One simple discontinuous and distributed controller using the vectorized Signum Function is proposed. This controller only involves the sign of the state differences of adjacent neighbors. In order to avoid the singularity introduced by the axis-angular representation, an extra constraint is added to the initial condition. It is proved that for some initial conditions, the control law achieves finite-time attitude synchronization. One simulated example is provided to verify the usage of the control protocol designed in this paper.