多馈入直流系统的协调控制仿真分析

针对多区域互联电网区域间低频振荡阻尼较弱的问题,在分析了直流阻尼调制机理的基础上,考虑到所搭建的典型电网近距离直流多落点的特点,提出了直流阻尼调制的协调控制策略。     

Oscillation criteria for second-order quasi-linear neutral difference equations

In this paper, we obtain some oscillation criteria for the second-order quasi-linear neutral delay difference equation

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, where > 0, τ ≥ 0, and σ ≥ 0 are constants, {a_n}, {p_n}, {q_n} are nonnegative sequences and f ε C(R,R).     

Exploiting natural dynamics for gait generation in undulatory locomotion

ABSTRACT

Robotic vehicles inspired by animal locomotion operate via periodic body movements. The pattern of body oscillation (gait) can be mimicked from animals, but understanding the principles underlying gait generation would allow for broad, flexible applications beyond nature's design. We hypothesise that travelling-wave oscillations observed in undulatory locomotion can be characterised as a natural oscillation of the locomotion dynamics and propose a formal definition of the natural gait for locomotion systems. We identify the essential dynamics and define the mode shape of natural oscillation by the free response of an idealised system. We then use body-environment resonance to define the amplitude and frequency. Explicit formulas for the natural gait are derived to provide insight into the mechanisms underlying undulatory locomotion. Examples of a swimming leech and a fictitious swimmer illustrate how undulatory gaits similar to those observed can be produced as the natural gait and modulated to achieve different swim speeds.     

基于PCC的弹性扭转系统控制器能设计与实现

贝加莱（B＆R）公司将工业中柔性连接驱动加以抽象,设计开发出了一套多质量弹性扭矩装置,其具有强震荡性,依据对象特性,本文采用双微分反馈（DDF）控制方案,征B＆R公司的X20控制器上开发相应模块,用C语言编写了控制程序,实验结果表明该控制方案能使系统往极短的时间内达到预设速度,实现了无超调的控制效果,并具有较高的稳态精度。将双轮负载扩展为三轮负载后,微调控制器参数仍可得到理想的控制效果,体现了控制系统县有良好的鲁棒性,控制器具有优秀的控制性能。     

Development of a Fuzzy Rule-Based Multi-Objective Hybrid Controller for Static Synchronous Compensator

Static synchronous compensator (Statcom) is a powerful new device for power systems, which can be used for various purposes. The multi-objective demands are quite different in nature, e.g. continuous linear control for voltage maintaining, and discrete bang-bang control for oscillation damping. Unfortunately, they often conflict with each other. In this respect, a supplementary damping control together with an independent voltage control is normally used. However, inevitable small disturbance and uncertainties will cause problems in the coordination of the two functions. To overcome such difficulties, a fuzzy rule-based hybrid controller is proposed in this paper, which incorporates conventional linear voltage control along with the fuzzy rule-based supplementary power damping control to form a unified global controller for Statcom. Because only simple fuzzy rules and a few input signals are involved, it is very easy to implement in a practical power system. The simulation performed on a Single- Machine-Infinite-Bus (SMIB) power system and an actual large power system demonstrates the effectiveness of the proposed approach.     

Detection and diagnosis of plant-wide oscillations using GA based factorization

The degradation in the performance of the plant is observed in form of oscillations in time trends of measurements. These disturbances propagate throughout the plant and also affect the performance of healthy loops. Thus, it becomes increasingly important to detect all the loops that lead to plant-wide oscillations. In this paper, spectral decomposition based on Evolutionary Algorithms is proposed for the detection of plant-wide oscillations. The key feature of the proposed technique is that it retains causal basis spectrum like shapes consisting of narrow band peaks by searching the solution space globally. Two industrial case studies are presented to demonstrate the efficiency of GA based Evolutionary Algorithms over existing techniques like independent component analysis (ICA) and non-negative matrix factorization (NMF) in detecting plant-wide oscillations. Results show that the proposed technique outperforms ICA and NMF with respect to reconstruction error.     

Detection and diagnosis of plant-wide oscillations from industrial data using the spectral envelope method

Plant-wide oscillations are common in many processes. Their effects propagate to many units and may impact the overall process performance. It is important to detect and diagnose the cause of such oscillations in order to rectify the situation. This paper proposes a new procedure to detect and diagnose plant-wide oscillations using routine operating data. A technique called spectral envelope is used to detect oscillations. The variables that have common oscillations are identified and categorized accurately by a statistical hypothesis test. A new index called the oscillation contribution index (OCI) is proposed to isolate the key variables as the potential root cause candidates of the common oscillation(s). Two industrial case studies are presented to demonstrate the utility and practicality of the proposed procedure.     

连铸保护渣道动态压力的研究

通过Bikerman公式确定弯月面的形态，计算保护渣道内的压力随结晶器振动、拉坯参数的规律。发现随保护渣粘度、拉坯速度、振动的负滑脱时间的增加以及保护渣道的出口宽度的减小，保护渣道内的最大正压、最大负压均有增加，其中保护渣道内的压力受渣道出口宽度的影响最大。     

Investigation of the optimum oscillation frequency value towards increasing the efficiency of OBIST approach

This paper is mainly focused on the investigation of the optimum value of the oscillation frequency in the Oscillation-based Built-In Self Tests (OBIST). It has been assumed that the proper frequency value might increase the test efficiency in covering hard-detectable short faults in analog integrated circuits (ICs) designed in nanoscale technology. In our research, active analog filters designed in 0.35 μm and 90 nm CMOS technologies were used as circuits under test (CUT). The tested circuits were brought to oscillation at different oscillation frequencies by varying the values of passive devices. The achieved results prove that the efficiency of OBIST approach can be increased in this way.     

高速数字跟踪位置测量系统警觉“振荡”的研究

高速数字跟踪位置测量系统在机床工作台妄动时容易产生振荡、从而使工作台出现抖动而不能正常工作文章中分析了测量系统初态振荡的原因，介绍了初态“低速化”的防振荡措施，即通过限制测量系统跟踪控制器中的速度。