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101.
±660 kV银东直流输电山东侧安全稳定控制策略 总被引:1,自引:0,他引:1
在交直流混联电网中,直流系统的双极闭锁对系统的安全性和稳定性影响较大。银东直流输电系统发生双极闭锁故障时,会引起特高压线路失稳、系统低频的稳定性问题,此时可通过采取切负荷的控制策略,确保系统稳定运行。文中通过研究±660kV银东直流输电系统山东侧安全稳定控制策略,提出了适用于大容量直流输入电网的安全稳定控制系统的策略研究方法、有效的切负荷优化技术及直流极闭锁判据;设计了主站、执行站分层控制模式以及按轮级切负荷的控制原理。该策略在山东电网的实际应用结果证明了其有效性。 相似文献
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基于FPGA的直接数字频率合成任意波发生电路 总被引:1,自引:0,他引:1
介绍了基于FPGA,采用DDS技术实现任意波发生电路的技术方案及关键技术.该任意波发生器电路简单,程控方便,产生的波形具有相噪好、频率步进低、输出电平分辨率小、相位可调等优点,可用在各种场合. 相似文献
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提出利用四个二粒子部分纠缠态作为量子信道,实现四粒子任意纠缠态的概率隐形传输的两种方案.发送者做四次Bell基测量,然后接收者通过引入辅助粒子并做适当的幺正变换,就能以一定的概率完成四粒子纠缠态的隐形传输.由变换算符出发,利用变换算符之间的关系给出两种方案的理论分析. 相似文献
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ABSTRACTA new approach to the solution of what is termed causal output tracking problem for linear time-invariant systems in the presence of both matched and unmatched unmodelled disturbances is presented. The proposed solution is addressed through the design of a dynamic steady state estimator based on the desired system structure and an observer, considering the reference as the system output. The unmatched disturbance is estimated and used in the steady state estimator to achieve invariance, while the matched disturbance robustness is provided via sliding mode control using the super-twisting algorithm. A useful application of the presented techniques is output tracking for non-minimum phase systems; thus, the performed simulation results confirm the effectiveness of the proposed control scheme for this kind of systems. 相似文献
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Firooz A. Sadjadi Cornell S. L. Chun Anders Sullivan Guillermo C. Gaunaurd 《Sensing and Imaging: An International Journal》2006,7(1):23-44
We present a polarimetric approach that can be used to characterize subsurface targets by means of ground-penetrating radar. Several quantities related to the Huynen-fork parameters are basic to the study. These quantities are all expressible in terms of the elements of Sinclair matrix S which in turn, can be determined as functions of frequency by an application of the method-of-moment (MoM)—which is briefly reviewed here—to a mine-like object buried at various depths in a soil of specified dielectric and moisture properties. The quantities in question are the Stokes parameters, the elevation, azimuth, and polarizability angles, as well as the polarization ratios and the scattering eigenvalues which optimize the backscattered power. Some of these quantities are studied here and displayed in various graphs. These frequency dependent graphs exhibit useful symmetry properties. The plots of the polarizability angle (β) vs. frequency seem to remain invariant with target depth, and exhibit resonance features that are later shown to agree well with other standard methods to estimate resonances such as Prony method. A simple analysis of the early-time resonances thus estimated is used to obtain acceptable mine dimensions. The agreement found implies that polarimetric techniques, such as present one, can also be used in the arsenal of techniques yielding target-ID clues. 相似文献
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The output tracking (OT) of arbitrary references in discrete‐time (DT) nonlinear systems is addressed by designing an output‐feedback control. A set of difference‐algebraic equations is proposed as an exact solution of the problem. Using a novel technique of approximating DT functions, the system disturbance and steady states, characterized by tracking error identically zero, for both the system state and the control input, are represented as signals generated by a disturbed dynamic system. Using the mentioned dynamics, the control system is extended. Then, a state observer is proposed to estimate the resulting extended system state. Finally, a DT sliding mode controller is designed to achieve the approximate OT. Simulations show the effectiveness of the proposed control scheme. 相似文献