The Experts below are selected from a list of 1674 Experts worldwide ranked by ideXlab platform

Joon Han - One of the best experts on this subject based on the ideXlab platform.

  • mitigation of voltage unbalance by using static load transfer switch in bipolar low voltage dc distribution system
    International Journal of Electrical Power & Energy Systems, 2017
    Co-Authors: Gihyeon Gwon, Chulhwan Kim, Chulho Noh, Tackhyun Jung, Joon Han
    Abstract:

    Abstract In this paper, a method is proposed to mitigate voltage unbalance and to reduce power loss due to neutral current in a bipolar Low-Voltage DC (LVDC) distribution system by using a static load transfer switch (SLTS). Furthermore, an algorithm to determine the proper position of loads by using the SLTS is presented; this algorithm is developed by considering the neutral current at each load point. The underlying strategy of the SLTS method is that a Local Substation generates switching signals by using the proposed algorithm on the basis of data measured by a DC/DC converter; thereafter, SLTSs, which are placed in the DC/DC converter, are operated to reconfigure the structure of loads. To evaluate the performance of the proposed method, the conventional method for calculating the percent voltage unbalance for an AC system is modified and made applicable for a DC system. The modeling of a 1500 V bipolar LVDC distribution system carried out using the ElectroMagnetic Transients Program (EMTP) is also presented herein. Finally, a simulation carried out by employing the SLTS method under various load conditions is presented; the results show a decrease in power loss and mitigation of voltage unbalance.

Yuan Liao - One of the best experts on this subject based on the ideXlab platform.

  • Generalized fault-location methods for overhead electric distribution systems
    IEEE Transactions on Power Delivery, 2011
    Co-Authors: Yuan Liao
    Abstract:

    Various methods have been proposed in the past for locating faults on distribution systems, which generally entail iterative procedures. This paper presents novel fault-location algorithms for overhead distribution systems that provide a unified solution that eliminates or reduces iterative procedures applicable to all types of faults. Two types of methods, respectively, for nonradial systems and radial systems have been proposed by utilizing voltage and current measurements at the Local Substation. The proposed methods are based on the bus impedance matrix, through which the Substation voltage and current quantities can be expressed as a function of the fault location and fault resistance, a solution to which yields the fault location. The methods are developed in phase domain and, consequently, are naturally applicable to unbalanced systems. The assumptions made are that the distribution network parameters and topology are known so that the bus impedance matrix can be developed. Simulation studies have demonstrated that both types of methods are accurate and quite robust to load variations and measurement errors.

Gihyeon Gwon - One of the best experts on this subject based on the ideXlab platform.

  • mitigation of voltage unbalance by using static load transfer switch in bipolar low voltage dc distribution system
    International Journal of Electrical Power & Energy Systems, 2017
    Co-Authors: Gihyeon Gwon, Chulhwan Kim, Chulho Noh, Tackhyun Jung, Joon Han
    Abstract:

    Abstract In this paper, a method is proposed to mitigate voltage unbalance and to reduce power loss due to neutral current in a bipolar Low-Voltage DC (LVDC) distribution system by using a static load transfer switch (SLTS). Furthermore, an algorithm to determine the proper position of loads by using the SLTS is presented; this algorithm is developed by considering the neutral current at each load point. The underlying strategy of the SLTS method is that a Local Substation generates switching signals by using the proposed algorithm on the basis of data measured by a DC/DC converter; thereafter, SLTSs, which are placed in the DC/DC converter, are operated to reconfigure the structure of loads. To evaluate the performance of the proposed method, the conventional method for calculating the percent voltage unbalance for an AC system is modified and made applicable for a DC system. The modeling of a 1500 V bipolar LVDC distribution system carried out using the ElectroMagnetic Transients Program (EMTP) is also presented herein. Finally, a simulation carried out by employing the SLTS method under various load conditions is presented; the results show a decrease in power loss and mitigation of voltage unbalance.

Backer Abujaradeh - One of the best experts on this subject based on the ideXlab platform.

  • hierarchical two level voltage controller for large power systems
    IEEE Transactions on Power Systems, 2016
    Co-Authors: V Venkatasubramanian, Javier Guerrero, Hong Chun, Xun Zhang, Farrokh Habibiashrafi, Armando Salazar, Backer Abujaradeh
    Abstract:

    This paper proposes a two-level voltage controller for large-scale power systems. The aim of the controller is to maintain a near-optimal voltage profile in the transmission network by coordinating discrete reactive power (var) control devices in the system. The controller is targeted for implementation in electric power transmission utility companies where most of the voltage controls are coordinated by switching of discrete var devices such as shunt capacitor and reactor banks and transformer banks load tap changers (LTCs). By effectively dividing the controller responsibilities between Local Substation controls and a central coordinator at control center level, the design is aimed at voltage control of large-scale power systems. At Local level, the Substation controllers maintain their respective Substation bus voltages by Local power-flow-like computations using mostly Local PMU measurements. The central coordinator computes and provides the voltage set-points to the Substation controllers and also coordinates by enabling or disabling the Local controllers as needed. The controller is being designed towards prototype implementation in Southern California Edison (SCE), starting with Local controllers at specific Substations in the first stage. It is tested on real-time dynamic models and large-scale power-flow simulations of SCE transmission network.

Honggeng Yang - One of the best experts on this subject based on the ideXlab platform.

  • fault location for distribution networks based on node voltage equation
    IEEE PES Asia-Pacific Power and Energy Engineering Conference, 2012
    Co-Authors: Dan Tan, Honggeng Yang
    Abstract:

    This paper proposed a method to estimate short-circuit fault location in electrical distribution networks using voltage sags data and current measured at the Local Substation. With the knowledge of bus impedance matrix, the bus voltage during the fault can be obtained for any fault in the network. Based on the non-liner profile characteristic of voltage sag measured at the bus, the paper proposed a new method. Firstly, voltage quantity for each section is expressed as a function of fault location and resistance base on the bus impedance matrix. The possible fault is estimated by incorporating the real and imaginary part of voltage sags into the node-voltage equation. Then, the method applies rank reasoning analysis to prioritize the possible fault locations due to the same electrical distance. In this method, the uncertainty of fault resistance is also considered. Through simulating for an 11kv typical test distribution network, the method's validity and accuracy are proved.