汽轮机运行调节方式优化策略探析

分析了汽轮机的喷嘴调节、节流调节、旁通调节、定压调节和滑压调节等几种基本调节方式的特点,指出现役燃煤火电机组多因调节方式单一而普遍存在着调峰能力不足、负荷响应迟缓以及因长期偏离设计工况致使运行安全经济性下降等诸多问题,提出了通过调节方式的优化组合,采用(节流)定压-滑压-(喷嘴)定压-旁通调节的复合调节方式,以实现煤电机组安全、经济、灵活、快速地参与电网的深度调峰,破解具有强随机波动性的新能源电量规模化并网的困境。     

多约束下距离加权最优滑模末制导律

为解决多约束下制导炮弹的精确制导问题,采用带有相对距离权函数的最优滑模末制导律,将权函数引入到最优制导律中,通过改变制导炮弹的运动轨迹、运动时间,进而增强制导精度。针对单权函数难以同时满足制导精度与导引头视线角、过载等约束的问题,采用不同权函数的分段加权方法解决加权最优末制导引起的制导问题。结合滑模变结构控制理论,设计分段加权最优滑模末制导律,增强制导系统的抗干扰能力。仿真验证结果表明,该末制导律既能解决过载、导引头视线角、落角等多约束情况下的精确制导问题,同时又具有一定的鲁棒性。     

A robust locating multi-optima approach for damage identification of plate-like structures

This paper proposes a robust optimization approach for multiple damage identification of plate-like structures. Different from traditional particle swarm optimizations (PSOs), a combined PSO and niche technique (NPSO) is proposed to solve multimodal optimization problems, with the full consideration of subswarm creation, merging and absorbing mechanism. As a hypersensitive parameter to damage, the curvature mode shape is adopted to construct the objective function. Case studies are conducted to investigate the effectiveness and robustness of the algorithm on multi-damage identification. Simulation results show that the proposed algorithm exhibits robust search performance on identifying damage locations accurately with good convergence behavior. It is hoped that this study can provide guidance on robust damage detection, especially when the structure is subject to multiple damages and external disturbances.     

When is it reasonable to implement the discontinuous sliding‐mode controllers instead of the continuous ones? Frequency domain criteria

Professor Utkin proposed an example showing that the amplitude of chattering caused by the presence of parasitic dynamics (stable actuators) in some systems governed by the First‐Order Sliding‐Mode Controller is lower than that produced by the Super‐Twisting Algorithm. This example served to motivate this paper reconsidering the problem of comparison of chattering in systems with stable actuators, and driven by Discontinuous Sliding‐Mode Controllers (DSMCs) and Continuous Sliding‐Mode Controllers (CSMCs). Comparison of chattering produced by DSMC and CSMC taking into account their amplitudes, frequencies, and average power (AP) needed to maintain the system into real‐sliding modes, allowing to conclude the following: (i) for systems with slow actuators, the amplitude of oscillations and AP produced by DSMC be smaller than those caused by CSMC; (ii) for bounded disturbances with fixed Lipschitz constant, there exist sufficiently fast actuators for which the amplitude of oscillations and AP produced by CSMC be smaller than those caused by DSMC.     

A globally exponentially stable speed observer for a class of mechanical systems: experimental and simulation comparison with high-gain and sliding mode designs

It is shown in the paper that the problem of speed observation for mechanical systems that are partially linearisable via coordinate changes admits a very simple and robust (exponentially stable) solution with a Luenberger-like observer. This result should be contrasted with the very complicated observers based on immersion and invariance reported in the literature. A second contribution of the paper is to compare, via realistic simulations and highly detailed experiments, the performance of the proposed observer with well-known high-gain and sliding mode observers. In particular, to show that – due to their high sensitivity to noise, that is unavoidable in mechanical systems applications – the performance of the two latter designs is well below par.     

Attitude control of spacecraft simulator without angular velocity measurement

In this paper the attitude control of a spacecraft simulator using Reaction Wheels (RW) as the actuators is investigated. The main goal of the current study is to bring the RWs to the rest at the end of the maneuver without angular velocity measurement. A modified feedback linearization controller is applied by considering the Euler angles of the simulator as the output and the RWs angular momentums as the internal state variables. The stability of the proposed controller and the internal dynamics is analyzed using Lyapunov theory. Two modified sliding mode observers are designed to estimate the angular velocities of the spacecraft attitude control subsystem simulator. The proposed observers do not use the control input and the detailed knowledge of the model and thus it can be implemented easily. The global stability of the system is proved. The proposed controller and observers are finally evaluated numerically and experimentally on an attitude spacecraft simulator.     

基于滑模的二阶多智能体快速抗扰一致性

针对带有外部未知扰动的二阶多智能体系统的领导—跟随有限时间一致性问题，本文设计出一种带有时变增益的有限时间干扰观测器，用以实现对每个跟随智能体中未知扰动的快速估计，在此基础上，本文结合超螺旋积分滑模控制方法并利用邻居智能体的位置和速度信息设计一种快速抗扰一致性协议，该协议能够保证存在非线性动态的多智能体系统有限时间一致性控制并能抑制抖振现象.同时，利用李亚普诺夫函数进行了稳定性的证明.最后，通过Matlab数值仿真进一步验证了所提出协议的可行性.     

Self-consistent kinetic theory with nonlinear wave-particle resonances

We have developed, based on the oscillating-center transformation, a general theoretical approach for self-consistent plasma dynamics including, explicitly, effects of nonlinear(higherorder) wave-particle resonances. A specific example is then given for low-frequency responses of trapped particles in axisymmetric tokamaks. Possible applications to transport as well as nonlinear wave growth/damping are also briefly discussed.     

Intelligent Power Compensation System Based on Adaptive Sliding Mode Control Using Soft Computing and Automation

The approach power compensator system (APCS) plays a role in the automatic carrier landing system (ACLS), and the performance of the APCS is affected by the carrier air-wake in the final-approach . In this paper, the importance of the APCS is verified through the analysis of the signal flow chart of the ACLS. Hence, it is necessary to suppress the carrier air-wake in order to improve the anti-interference ability. The adaptive sliding mode control (ASMC) not only has better dynamic tracking performance compared to the nonlinear mode, but also can efficiently resist the disturbance caused by the carrier air-wake. The design of the longitudinal control law of the ACLS is based on the carrier-based aircraft nonlinear model and the carrier air-wake model. It comprises the longitudinal guidance rate, autopilot (CAS) and the APCS. The ASMC is used to design the APCS to suppress the carrier air-wake. A comparison of the simulation results indicates that the design based on the ASMC has better anti-interference ability and can keep the velocity constant on the timely.     

Application of full order sliding mode control based on different areas power system with load frequency control

In the traditional sliding mode control method, there always exist the singularity due to the reduced order of the control method. In order to eliminate the singularity, I propose a new full order sliding mode control method in this article, which has been firstly applied to load frequency control. The full order sliding mode control method includes the terminal sliding mode control (TSM) and the linear sliding mode control (LSM). TSM has the good characteristic of eliminating the singularity due to the avoidance of derivative of terms with fractional power factors. While the LSM is easy to design and has fast time convergence comparing to TSM. The model is based on the system with different kinds of turbine or the same kind of turbine, which contains the nonlinearities. The control purpose is to adjust the frequency deviation to zero. Through the simulation results, it is shown that the frequency deviation can be kept to zero in the condition of different load disturbances by the two approaches, which approves the robustness of the proposed methods. In addition, we compare the two methods with the traditional sliding mode control (SMC), which proves the superiority of the two methods in terms of chattering and response time.