When the line impedance is considered in the microgrid, the accuracy of load sharing will decrease. In this paper, the impact of line impedance on the accuracy of load sharing is analyzed. A robust droop control for a...
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When the line impedance is considered in the microgrid, the accuracy of load sharing will decrease. In this paper, the impact of line impedance on the accuracy of load sharing is analyzed. A robust droop control for a highvoltage microgrid is proposed based on the signal detection on the high-voltage side of the coupling transformer. For a high-voltage microgrid, the equivalent impedance of coupling transformer connecting distributed generator with the grid is usually the dominate factor. Compared with the conventional droop control strategy, the proposed control method in this paper detects the feedback signal from the high-voltage side of the coupling transformer. The impact of line impedance on the load sharing accuracy can be mitigated significantly. The proposed droop control only changes the detection point of the feedback signal, thus it is easy to be implemented. The PSCAD/EMTDC simulation results show the effectiveness of the proposed robust droop control concept in load sharing and voltage regulation with highly accuracy.
Nowadays, robots become a companion in everyday life. To be well-accepted by humans, robots should efficiently understand meanings of their partners’ motions and body language, and respond accordingly. Learning conce...
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Silicon photonics holds the promise of the miniaturization of quantum communication devices. Recently, silicon chip optical transmitters for quantum key distribution (QKD) have been built and demonstrated experimental...
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Silicon photonics holds the promise of the miniaturization of quantum communication devices. Recently, silicon chip optical transmitters for quantum key distribution (QKD) have been built and demonstrated experimentally. Nonetheless, these silicon chips suffer substantial phase- and polarization-dependent loss (PDL) which, if unchecked, could compromise the security of QKD systems due to overestimation of the secret key rate. Here, first, we restore the security by regarding single photons without phase and polarization dependence as untagged and secure qubits. Next, by using a postselection technique, we implement a secure QKD protocol that provides a high key generation rate even in the presence of severe phase- and polarization-dependent loss. Our solution is simple to realize in a practical experiment, as it does not require any hardware modification.
Quantum key distribution is a way to distribute secret keys to distant users with information theoretic security and key rates suitable for real-world applications. Its rate-distance figure, however, is limited by the...
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Currently, wind farms typically rely on greedy control, in which the individual turbine's structural loading and power are optimized. However, this often appears suboptimal for the whole wind farm. A promising sol...
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ISBN:
(纸本)9781509045839
Currently, wind farms typically rely on greedy control, in which the individual turbine's structural loading and power are optimized. However, this often appears suboptimal for the whole wind farm. A promising solution is closed-loop wind farm control using state feedback algorithms employing a dynamic model of the flow. This control method is a novelty in wind farms, and has potential to provide a temporally optimal control policy accounting for time-varying inflow conditions and unmodeled dynamics, both often neglected in current methods. An essential building block for state feedback control is a state estimator (observer) that reconstructs the system states for the dynamic model using a small number of measurements. As computational efficiency is critical in real-time control, lower-fidelity models are proposed to be used. In this work, WindFarmObserver (WFObs) is introduced, which is a state estimator relying on the WindFarmSimulator (WFSim) model and an Ensemble Kalman Filter (EnKF). The states of WFSim form the two-dimensional flow field in a wind farm at hub height. WFObs is tested in a two-turbine setup using a high-fidelity simulation model. With a realistic sensor setup where only 1.1% of the to-be-estimated states are measured, WFObs reduces the RMS error by 21% compared to open-loop simulation of WFSim, at a low computational cost of 0.76 s per timestep, a factor 10~2 faster than the common Extended Kalman Filter.
Distributed coordination algorithms (DCA) carry out information processing processes among a group of networked agents without centralized information fusion. Though it is well known that DCA characterized by an SIA (...
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Despite substantial declines since 2000, lower respiratory infections (LRIs), diarrhoeal diseases, and malaria remain among the leading causes of nonfatal and fatal disease burden for children under 5 years of age (un...
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An improved nonlinear adaptive switching control method is presented to relax the assumption on the higher order nonlinear terms of a class of discrete-time non-affine nonlinear systems. The proposed control strategy ...
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An improved nonlinear adaptive switching control method is presented to relax the assumption on the higher order nonlinear terms of a class of discrete-time non-affine nonlinear systems. The proposed control strategy is composed of a linear adaptive controller, a neural network(NN) based nonlinear adaptive controller and a switching mechanism. An incremental model is derived to represent the considered system and an improved robust adaptive law is chosen to update the parameters of the linear adaptive controller. A new performance criterion of the switching mechanism is designed to select the proper controller. Using this control scheme, all the signals in the system are proved to be bounded. Numerical examples verify the effectiveness of the proposed algorithm.
Reactive power compensation is an important challenge in current and future smart power systems. However, in the context of reactive power compensation, most existing studies assume that customers can assess their com...
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