The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform

Francky Catthoor - One of the best experts on this subject based on the ideXlab platform.

  • hierarchical memory size estimation for Loop fusion and Loop shifting in data dominated applications
    Asia and South Pacific Design Automation Conference, 2006
    Co-Authors: Qubo Hu, Martin Palkovic, Per Gunnar Kjeldsberg, Arnout Vandecappelle, Eric Brockmeyer, Francky Catthoor
    Abstract:

    Loop fusion and Loop shifting are important transformations for improving data locality to reduce the number of costly accesses to off-chip memories. Since exploring the exact platform mapping for all the Loop transformation alternatives is a time consuming process, heuristics steered by improved data locality are generally used. However, pure locality estimates do not sufficiently take into account the hierarchy of the memory platform. This paper presents a fast, incremental technique for hierarchical memory size requirement estimation for Loop fusion and Loop shifting at the early Loop transformations design stage. As the exact memory platform is often not yet defined at this stage, we propose a platform-independent approach which reports the Pareto-optimal trade-off points for scratch-pad memory size and off-chip memory accesses. The estimation comes very close to the actual platform mapping. Experiments on realistic test-vehicles confirm that. It helps the designer or a tool to find the interesting Loop transformations that should then be investigated in more depth afterward.

  • ASP-DAC - Hierarchical memory size estimation for Loop fusion and Loop shifting in data-dominated applications
    Proceedings of the 2006 conference on Asia South Pacific design automation - ASP-DAC '06, 2006
    Co-Authors: Qubo Hu, Martin Palkovic, Per Gunnar Kjeldsberg, Arnout Vandecappelle, Eric Brockmeyer, Francky Catthoor
    Abstract:

    Loop fusion and Loop shifting are important transformations for improving data locality to reduce the number of costly accesses to off-chip memories. Since exploring the exact platform mapping for all the Loop transformation alternatives is a time consuming process, heuristics steered by improved data locality are generally used. However, pure locality estimates do not sufficiently take into account the hierarchy of the memory platform. This paper presents a fast, incremental technique for hierarchical memory size requirement estimation for Loop fusion and Loop shifting at the early Loop transformations design stage. As the exact memory platform is often not yet defined at this stage, we propose a platform-independent approach which reports the Pareto-optimal trade-off points for scratch-pad memory size and off-chip memory accesses. The estimation comes very close to the actual platform mapping. Experiments on realistic test-vehicles confirm that. It helps the designer or a tool to find the interesting Loop transformations that should then be investigated in more depth afterward.

Wei Tian - One of the best experts on this subject based on the ideXlab platform.

  • three phase distribution power flow calculation for Loop based microgrids
    IEEE Transactions on Power Systems, 2018
    Co-Authors: Xu Wang, Mohammad Shahidehpour, Wei Tian, Chuanwen Jiang, Zhiyi Li
    Abstract:

    This paper introduces an efficient method for calculating the three-phase power flow in a Loop-based microgrid. The proposed method incorporates the conventional Newton–Raphson (NR) iterative approach in a backward/forward sweep (BFS) algorithm for power distribution network analyses. Conventional compensation-based approaches are commonly used to account for Loop breakpoints (LBPs) and PV nodes. However, the efficiency and the convergence of traditional solutions deteriorate as the number of Loops and PV nodes increases. In this paper, we convert microgrid Loops into radial structures by breaking up LBPs, when PV nodes connected to distributed generators (DGs) are regulated with scheduled constant voltage magnitudes. Then, we apply a three-phase BFS-based power flow method with an acceptable convergence for radial distribution networks. Next, we use the NR method for power mismatch corrections at LBPs and PV nodes. Finally, the proposed method is extended to islanded microgrids by introducing the system frequency as a variable. We label the proposed Loop-based method an NR-BFS power flow calculation scheme, which combines NR and BFS methods for microgrid solutions. The solution of the proposed algorithm, which signifies the application of the improved BFS method, is applicable to active distribution systems with several Loops and DGs. The simulation results demonstrate the efficiency of the proposed method in the Loop-based microgrid applications.

  • Protection Scheme for Loop-Based Microgrids
    IEEE Transactions on Smart Grid, 2017
    Co-Authors: Mohammad Shahidehpour, Zuyi Li, Wei Tian
    Abstract:

    This paper presents a protection scheme for Loop-based microgrids, which is divided into four levels, including load-way, Loop-way, feeder, and microgrid. The scheme applies a dual protection strategy at the load-way level and a single protection strategy at the other three levels, which are designed to handle various types of faults in grid-connected and island modes of microgrids. The microgrid primary and back-up protections are taken into consideration at each level for grid-connected and island modes. The plug and play characteristics, time constraints of low voltage ride through, and unbalanced faults are considered for distributed generations. This paper demonstrates that the microgrid reliability is improved by coordinating the logics in the four proposed protection levels. The Illinois Tech microgrid is used as a design testbed to verify the effectiveness of the proposed protection scheme.

Zhiyi Li - One of the best experts on this subject based on the ideXlab platform.

  • three phase distribution power flow calculation for Loop based microgrids
    IEEE Transactions on Power Systems, 2018
    Co-Authors: Xu Wang, Mohammad Shahidehpour, Wei Tian, Chuanwen Jiang, Zhiyi Li
    Abstract:

    This paper introduces an efficient method for calculating the three-phase power flow in a Loop-based microgrid. The proposed method incorporates the conventional Newton–Raphson (NR) iterative approach in a backward/forward sweep (BFS) algorithm for power distribution network analyses. Conventional compensation-based approaches are commonly used to account for Loop breakpoints (LBPs) and PV nodes. However, the efficiency and the convergence of traditional solutions deteriorate as the number of Loops and PV nodes increases. In this paper, we convert microgrid Loops into radial structures by breaking up LBPs, when PV nodes connected to distributed generators (DGs) are regulated with scheduled constant voltage magnitudes. Then, we apply a three-phase BFS-based power flow method with an acceptable convergence for radial distribution networks. Next, we use the NR method for power mismatch corrections at LBPs and PV nodes. Finally, the proposed method is extended to islanded microgrids by introducing the system frequency as a variable. We label the proposed Loop-based method an NR-BFS power flow calculation scheme, which combines NR and BFS methods for microgrid solutions. The solution of the proposed algorithm, which signifies the application of the improved BFS method, is applicable to active distribution systems with several Loops and DGs. The simulation results demonstrate the efficiency of the proposed method in the Loop-based microgrid applications.

Mohammad Shahidehpour - One of the best experts on this subject based on the ideXlab platform.

  • three phase distribution power flow calculation for Loop based microgrids
    IEEE Transactions on Power Systems, 2018
    Co-Authors: Xu Wang, Mohammad Shahidehpour, Wei Tian, Chuanwen Jiang, Zhiyi Li
    Abstract:

    This paper introduces an efficient method for calculating the three-phase power flow in a Loop-based microgrid. The proposed method incorporates the conventional Newton–Raphson (NR) iterative approach in a backward/forward sweep (BFS) algorithm for power distribution network analyses. Conventional compensation-based approaches are commonly used to account for Loop breakpoints (LBPs) and PV nodes. However, the efficiency and the convergence of traditional solutions deteriorate as the number of Loops and PV nodes increases. In this paper, we convert microgrid Loops into radial structures by breaking up LBPs, when PV nodes connected to distributed generators (DGs) are regulated with scheduled constant voltage magnitudes. Then, we apply a three-phase BFS-based power flow method with an acceptable convergence for radial distribution networks. Next, we use the NR method for power mismatch corrections at LBPs and PV nodes. Finally, the proposed method is extended to islanded microgrids by introducing the system frequency as a variable. We label the proposed Loop-based method an NR-BFS power flow calculation scheme, which combines NR and BFS methods for microgrid solutions. The solution of the proposed algorithm, which signifies the application of the improved BFS method, is applicable to active distribution systems with several Loops and DGs. The simulation results demonstrate the efficiency of the proposed method in the Loop-based microgrid applications.

  • Protection Scheme for Loop-Based Microgrids
    IEEE Transactions on Smart Grid, 2017
    Co-Authors: Mohammad Shahidehpour, Zuyi Li, Wei Tian
    Abstract:

    This paper presents a protection scheme for Loop-based microgrids, which is divided into four levels, including load-way, Loop-way, feeder, and microgrid. The scheme applies a dual protection strategy at the load-way level and a single protection strategy at the other three levels, which are designed to handle various types of faults in grid-connected and island modes of microgrids. The microgrid primary and back-up protections are taken into consideration at each level for grid-connected and island modes. The plug and play characteristics, time constraints of low voltage ride through, and unbalanced faults are considered for distributed generations. This paper demonstrates that the microgrid reliability is improved by coordinating the logics in the four proposed protection levels. The Illinois Tech microgrid is used as a design testbed to verify the effectiveness of the proposed protection scheme.

P. Sannuti - One of the best experts on this subject based on the ideXlab platform.

  • Observer design for Loop transfer recovery and for uncertain dynamical systems
    IEEE Transactions on Automatic Control, 1990
    Co-Authors: A. Saberi, P. Sannuti
    Abstract:

    A theory of observer design for exact and approximate Loop-transfer recovery (LTR) and for uncertain dynamical systems is given. The method decomposes a given multivariable nominal system into several single-input, single-output subsystems, each of which can be designed separately. Both full-order and reduced-order observer designs can be derived. The design addresses the case when uncertainties are modeled as blocks exterior to the given plant and the case when uncertainties are prescribed structurally in terms of a state-space description. When the uncertainties in a given plant are modeled external to it, the observer design corresponds to a traditional LTR design, When uncertainties are given in terms of a state-space description, observer design can take into account uncertain elements of both linear and nonlinear type. This analysis can be viewed as a contribution to the development of a separation principle under which control system design for an uncertain dynamic system can be decomposed into designing a state feedback law and an observer for implementing the state feedback design.