52 research outputs found

    Study of Reactive Power Compensation for High Speed Railway Design

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    AbstractThe peculiarity of the high speed railway power supply and distribution system is introduced. With comparison of conventional reactive power compensation approach, an adjustable and feasible compensation scheme is proposed. In order to regulate the reactive power of the high speed railway flexibly, we compensate the reactive power of the feeder substation and the power through line respectively. The compensation scheme of the power through line relies mainly on setting fixed reactors distributed on it with adjustable reactors concentrated in the substation as subsidiary, and increasing the power factor of the end line of the feeder substation

    Risk-Based Probabilistic Voltage Stability Assessment in Uncertain Power System

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    The risk-based assessment is a new approach to the voltage stability assessment in power systems. Under several uncertainties, the security risk of static voltage stability with the consideration of wind power can be evaluated. In this paper, we first build a probabilistic forecast model for wind power generation based on real historical data. Furthermore, we propose a new probability voltage stability approach based on Conditional Value-at-Risk (CVaR) and Quasi-Monte Carlo (QMC) simulation. The QMC simulation is used to speed up Monte Carlo (MC) simulation by improving the sampling technique. Our CVaR-based model reveals critical characteristics of static voltage stability. The distribution of the local voltage stability margin, which considers the security risk at a forecast operating time interval, is estimated to evaluate the probability voltage stability. Tested on the modified IEEE New England 39-bus system and the IEEE 118-bus system, results from the proposal are compared against the result of the conventional proposal. The effectiveness and advantages of the proposed method are demonstrated by the test results

    A False Rejection Oriented Threat Model for the Design of Biometric Authentication Systems

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    For applications like Terrorist Watch Lists and Smart Guns, a false rejection is more critical than a false acceptance. In this paper a new threat model focusing on false rejections is presented, and the standard architecture of a biometric system is extended by adding components like crypto, audit logging, power, and environment to increase the analytic power of the threat model. Our threat model gives new insight into false rejection attacks, emphasizing the role of an external attacker. The threat model is intended to be used during the design of a system

    Chance-Constrained Real-Time Dispatch with Renewable Uncertainty Based on Dynamic Load Flow

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    In this paper, a comprehensive real-time dispatch model considering renewable uncertainty based on dynamic load flow (DLF) is proposed. Through DLF, the primary and secondary frequency regulation amount caused by the variation of renewable energy as well as the line flow when primary and secondary regulation are deployed can be obtained easily. Not only the frequency constraints, but also the regular constraints like generator production limits and line flow limits are respected under both primary and secondary frequency regulation. To solve the dispatch problem with renewable uncertainty, chance-constrained programming based on cumulants and Cornish-fisher expansions (CCP-CMCF) is adopted to get the probability of holding the chance constraints and then the real-time dispatch model can be transformed into a quadratic programming. The simulation results show that the dispatch model proposed in this paper can deal with both primary and secondary regulation well and has a fast computation speed
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