The Experts below are selected from a list of 42810 Experts worldwide ranked by ideXlab platform
Xiangyu Zhang - One of the best experts on this subject based on the ideXlab platform.
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integrated wind turbine controller with virtual inertia and primary frequency responses for grid dynamic frequency support
Iet Renewable Power Generation, 2017Co-Authors: Yi Wang, Xiangyu ZhangAbstract:An integrated controller of wind turbines with both inertial response and primary frequency regulation (PFR) to provide complete dynamic frequency support for the grid with high wind power penetration is investigated. The wind turbine control governor contains two cross-coupled controllers: pitch controller and maximum power point tracking (MPPT) controller. First, as a precondition for the PFR, a de-Loading pitch control scheme is proposed to reserve capacity required for frequency regulation. Then, by optimizing the MPPT scheme, the rapid virtual inertia response is achieved even under de-Loading Operation condition. Based on the analysis of the steady-state characteristics of wind turbines with frequency droop control, the primary frequency control strategy, which enables the adjustment of frequency droop coefficient, is further proposed through pitch angle changes. Thus, the PFR and inertial response can be both achieved by the proposed de-Loading pitch controller and optimized MPPT controller. A three-machine prototype system containing two synchronous generators and a Doubly Fed Induction Generator (DFIG)-based wind turbine with 30% of wind penetration is implemented to validate the proposed integrated control strategies on providing inertial response and subsequent load sharing in the event of frequency change.
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active participation of variable speed wind turbine in inertial and primary frequency regulations
Electric Power Systems Research, 2017Co-Authors: Xiangyu Zhang, Yang Hei, Hui WangAbstract:Abstract Power systems have increasingly exhibited a need for a potential frequency governor with virtual inertial control (VIC) and primary frequency regulation (PFR) functions in recent years, due to the increased penetration of wind turbines that almost have no frequency response. In this paper, a novel integrated frequency governor applied to a wind turbine is proposed to provide fast active power support and scheduled power allocation for both temporary inertial response and continued PFR. Below rated wind speed, an initial pitch angle is calculated firstly to preset a proper de-Loading level for PFR in response to frequency drops, according to the presented relations of C P - λ - β . Under the de-Loading Operation conditions, the de-Loading power tracking curve is replaced by the defined VIC curves, and the inertial response is then obtained by rapidly shifting the VIC curves. Based on analysis of the mechanical characteristics of wind turbines with frequency droop, a primary frequency control strategy facilitated by the regulation of pitch angles is additionally proposed. A preset β / f droop curve is added to the de-Loading pitch controller to regulate the mechanical power for scheduled power allocation, and thus satisfying the P / f droop demand of system PFR. Finally, the experiments and simulation results demonstrate that by using the proposed frequency governor a doubly fed induction generator (DFIG) based wind turbine can provide both temporary virtual inertia and continued load sharing to improve the dynamic frequency stability of the power grid with high wind power penetration.
Kap Hwan Kim - One of the best experts on this subject based on the ideXlab platform.
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load scheduling for multiple quay cranes in port container terminals
Journal of Intelligent Manufacturing, 2006Co-Authors: Sung Ho Jung, Kap Hwan KimAbstract:This paper proposes a method to schedule Loading Operations when multiple yard cranes are operating in the same block. The Loading scheduling methods in this paper are based on a genetic algorithm and a simulated annealing method, which consider interferences between adjacent yard cranes. It attempts to minimize the make-span of the yard crane Operation. We consider the container handling time, the yard crane travel time, and the waiting time of each yard crane, when evaluating the makespan of the Loading Operation by yard cranes. An encoding method considering the special properties of the optimal solution of the problem is suggested. Numerical experiment was conducted to compare performances of the algorithms suggested in this study.
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an optimal routing algorithm for a transfer crane in port container terminals
Transportation Science, 1999Co-Authors: Kap Hwan Kim, Ki Young KimAbstract:This paper focuses on how to optimally route transfer cranes in a container yard during Loading Operations of export containers at port terminals. Decision variables are the number of containers that a transfer crane picks up at each yard-bay and the sequence of yard-bays that atransfer crane visits during a Loading Operation. This routing problem is formulated as a mixed integer program. The objective function of the formulation is to minimize the total container handling time of a transfer crane, which includes setup time at each yard-bay and travel time between yard-bays. Based on the mixed integer program, an optimizing algorithm is developed.
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Re-marshaling export containers in port container terminals
Computers & Industrial Engineering, 1998Co-Authors: Kap Hwan Kim, Jong Wook BaeAbstract:In order to speed up the Loading Operation of export containers onto a ship, the re-marshaling Operation is an usual practice in port container terminals. It is assumed that the current yard map for containers is available and a desirable bay layout is provided. A methodology is proposed to convert the current bay layout into the desirable layout by moving the fewest possible number of containers and in the shortest possible travel distance. The problem is decomposed into three sub-problems such as the bay matching, the move planning, and the task sequencing. The bay matching is to match a specific current bay with a bay configuration in the target layout. In the move planning stage, the number of containers to be moved from a specific bay to another is determined. The completion time of the re-marshaling Operation is minimized by sequencing the moving tasks in the final stage. A mathematical model is suggested for each sub-problem. A numerical example is provided to illustrate the solution procedure.
Yi Wang - One of the best experts on this subject based on the ideXlab platform.
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integrated wind turbine controller with virtual inertia and primary frequency responses for grid dynamic frequency support
Iet Renewable Power Generation, 2017Co-Authors: Yi Wang, Xiangyu ZhangAbstract:An integrated controller of wind turbines with both inertial response and primary frequency regulation (PFR) to provide complete dynamic frequency support for the grid with high wind power penetration is investigated. The wind turbine control governor contains two cross-coupled controllers: pitch controller and maximum power point tracking (MPPT) controller. First, as a precondition for the PFR, a de-Loading pitch control scheme is proposed to reserve capacity required for frequency regulation. Then, by optimizing the MPPT scheme, the rapid virtual inertia response is achieved even under de-Loading Operation condition. Based on the analysis of the steady-state characteristics of wind turbines with frequency droop control, the primary frequency control strategy, which enables the adjustment of frequency droop coefficient, is further proposed through pitch angle changes. Thus, the PFR and inertial response can be both achieved by the proposed de-Loading pitch controller and optimized MPPT controller. A three-machine prototype system containing two synchronous generators and a Doubly Fed Induction Generator (DFIG)-based wind turbine with 30% of wind penetration is implemented to validate the proposed integrated control strategies on providing inertial response and subsequent load sharing in the event of frequency change.
Ki Young Kim - One of the best experts on this subject based on the ideXlab platform.
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an optimal routing algorithm for a transfer crane in port container terminals
Transportation Science, 1999Co-Authors: Kap Hwan Kim, Ki Young KimAbstract:This paper focuses on how to optimally route transfer cranes in a container yard during Loading Operations of export containers at port terminals. Decision variables are the number of containers that a transfer crane picks up at each yard-bay and the sequence of yard-bays that atransfer crane visits during a Loading Operation. This routing problem is formulated as a mixed integer program. The objective function of the formulation is to minimize the total container handling time of a transfer crane, which includes setup time at each yard-bay and travel time between yard-bays. Based on the mixed integer program, an optimizing algorithm is developed.
Kwangryul Ryu - One of the best experts on this subject based on the ideXlab platform.
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deriving decision rules to locate export containers in container yards
European Journal of Operational Research, 2000Co-Authors: Young Man Park, Kwangryul RyuAbstract:Abstract A methodology is proposed to determine the storage location of an arriving export container considering its weight. We consider the configuration of the container stack and the weight distribution of containers in the yard-bay. A dynamic programming model is formulated to determine the storage location to minimize the number of relocation movements expected for the Loading Operation. We also develop a decision tree from the set of the optimal solutions to support real time decisions. The performance of the decision tree is evaluated by the number of decisions that are different from the optimal solutions of the slower dynamic programming solution method.