抑制超低频振荡的稳定器控制机理及策略验证

电力系统稳定器(PSS)是解决低频振荡的有效手段,但对于富集水电互联系统出现的超低频振荡,无法提供有效正阻尼。文中基于复转矩系数法对超低频振荡机理进行剖析,理论推导出附加阻尼控制的可行性。利用分频段控制思想,对传统PSS附加低通分支以拓展超低频控制段,构建新型抑制超低频振荡的PSS控制结构,同时提出频段设定和计及系统工况变化的控制参数鲁棒整定算法。通过应用于四川电网某水电外送区域的实例测试,验证了该附加阻尼控制策略对不同工况下产生的超低频振荡均能有效抑制。     

适用于中低压配电网的VSG多机协同鲁棒运行控制方法

虚拟同步发电机(VSG)作为一种新型电网友好型运行控制方法,通常情况下大多以中低压、多节点分散接入配电网,其存在多类不确定因素以及多机协同运行控制问题,给配电网的安全稳定控制带来了一定的挑战。为此,提出了一种面向中低压配电网的VSG多机协同鲁棒运行控制方法,主要针对协同运行控制中的母线电压跟踪、多机功率均分以及中低压配电网中线路阻抗参数不确定造成的功率耦合不确定和系统设备出力不确定等问题进行了讨论。通过建立VSG并网模型,将不确定功率耦合转化为模型不确定问题进行设计;考虑到中低压配电网中可能存在的拓扑未知和模型阶数较高的问题,通过直接扩张母线电压状态和多机功率均分状态,建立多VSG并网协同控制模型;采用鲁棒控制理论设计整体系统的反馈控制器,抑制模型内部的功率不确定耦合和外部设备不确定出力对控制性能的影响。基于MATLAB/Simulink的仿真模型验证了所提方法的有效性。     

基于库存理论考虑局部不确定性的互联微电网分布式鲁棒调度

为实现广域分布式能源系统的高度自治性和鲁棒性,提出了一种用于互联微电网(interconnected microgrids, IMG)的分布式鲁棒经济调度(distributed robust economic dispatch, DRED)。首先,应用多智能体理论搭建IMG的分层分布式调度框架;其次,为了解决分布式鲁棒优化问题,将原问题分解为多层问题,在上两层进行可行性测试和联络线功率优化。在此研究结果的基础上,运用库存理论对可再生能源和负荷的不确定性进行了研究;最后,以一个实际的IMG系统为例,通过对分散和集中式鲁棒方案的比较,验证了该策略的收敛性和可行性。该模型在计算复杂度上也优于传统的DRED模型,利用概率信息实现了某一置信水平下的最优调度。     

基于鲁棒优化的主动配电网分布式电源优化配置方法

为优化配置作为分布式发电的有效管理平台的主动配电网,针对含分布式发电并网的主动配电网优化配置问题,给出一种基于鲁棒优化理论的优化配置模型。首先,以综合配置成本最小为目标函数,计及功率平衡约束、可控微源运行约束、旋转备用约束等必要约束条件,建立主动配电网优化配置模型。针对模型中的不确定性,采用鲁棒优化框架将分布式光伏和风电区间模型中的不确定变量进行消除,再采用线性对偶理论和拉格朗日求导法将其转化为确定性的优化配置模型。仿真算例表明,主动配电网相比于传统配电网具有更高的运行经济性和可靠性。同时,所建立的模型能够计及风光出力不确定性对配置结果的影响,从而适用于主动配电网优化配置方案制定。     

低速巡飞器倾斜转弯鲁棒反演控制律设计

针对低速巡飞器倾斜转弯非线性控制系统存在耦合、不确定项的特点,设计了一种倾斜转弯（BTT）鲁棒反演控制律。将巡飞器的动力学模型写成适用于反演算法的块控模型,假设其由标称模型与不确定项组成,利用微积分学中的Leibniz法则推导不确定项。采用反演算法推导控制律的基本形式,并通过改进的符号函数抵消非匹配不确定项,利用Lyapunov理论重新设计技术补偿匹配不确定项。仿真结果表明,与传统反演法相比,该系统能够快速、准确地跟踪攻角、侧滑角、倾斜角参考指令,具有强鲁棒性。     

Robust optimum design of tuned liquid column damper in seismic vibration control of structures under uncertain bounded system parameters

The optimum design of a tuned liquid column damper (TLCD) considering system parameter uncertainty is usually performed by minimising the performance measure obtained by the total probability theory without any consideration to the variation of its performance due to parameter uncertainty. However, such a design method does not necessarily correspond to an optimum design in terms of maximum response reduction as well as its minimum dispersion. Furthermore, such approach cannot be applied in many real situations when the required detailed information about the uncertain parameters is limited. The robust design optimisation (RDO) of a TLCD system to mitigate seismic vibration effect in which the bounds on the magnitude of the uncertain properties of the structural and ground motion model parameters are only required is attempted in this study. The RDO is formulated as a two-criterion optimisation problem where the weighted sum of the maximum root mean square displacement of the structure and its dispersion is minimised. The conventional interval analysis-based bounded optimum solution is also obtained to demonstrate the effectiveness of the proposed RDO approach. A numerical study elucidates the effect of parameter uncertainty on the RDO of TLCD parameters by comparing the RDO results with the bounded optimum results.     

Data-Driven Temporal Filtering on Teager Energy Time Trajectory for Robust Speech Recognition

Data-driven temporal filtering technique is integrated into the time trajectory of Teager energy operation （TEO） based feature parameter for improving the robustness of speech recognition system against noise. Three kinds of data-driven temporal filters are investigated for the motivation of alleviating the harmful effects that the environmental factors have on the speech. The filters include： principle component analysis （PCA） based filters, linear discriminant analysis （LDA） based filters and minimum classification error （MCE） based filters. Detailed comparative analysis among these temporal filtering approaches applied in Teager energy domain is presented. It is shown that while all of them can improve the recognition performance of the original TEO based feature parameter in adverse environment, MCE based temporal filtering can provide the lowest error rate as SNR decreases than any other algorithms.     

Robust stability analysis and improved design of phase‐locked loops with non‐monotonic nonlinearities: LMI‐based approach

Due to nonlinear nature of several phase detectors, linear approximation method often leads to performance degradation in many phase‐locked loops (PLLs), particularly when the phase errors are sufficiently large. A third or higher order PLL, in spite of the ability to track a wider variety of inputs and having higher operating‐frequency range, requires more design attention in order to ensure stable tracking. In this work, with the nonlinearities inserted into the system's model, suitable criteria that take into account the nonlinearities' non‐monotonicity, sector and slope bounds are employed to establish robust stability conditions. The result is applicable to any PLLs without order and type restrictions. For Type‐1 PLLs, the resulting condition can be used to search for the maximum stable loop gain, which is also linked to the lock‐in range of the system. In the later part of this work, the focus is devoted towards designing PLLs with high lock‐in range, which is performed via mixing the proposed method with H _∞ synthesis. The searches for the parameters in both PLL analysis and design are expressed in terms of convex linear matrix inequalities, which are computationally tractable. To illustrate the improvement introduced via this approach, several numerical examples and simulations are included with comparisons over conventional methods. Copyright © 2017John Wiley & Sons, Ltd.     

非仿射纯反馈不确定系统预设性能鲁棒自适应控制

针对一类结构和参数及控制方向均未知的非仿射纯反馈非线性不确定系统,提出了一种保预设性能鲁棒自适应控制方案。首先引入性能函数和误差转换函数,通过误差转换将原始的输出误差存在性能约束的受限系统转换为等价的非受限系统;其次,基于中值定理将非仿射型系统转化为具有线性结构形式的时变系统,并同时利用自适应投影算法对有界时变参数进行辨识,参数辨识误差和外界干扰采用非线性阻技术项进行补偿;随后综合运用反演技术和Nussbaum函数设计控制器并进行稳定性分析。所设计的控制器不仅能够保证闭环系统所有信号有界且输出误差满足预设的瞬态及稳态性能要求;最后,仿真结果验证了所设计控制方案的可行性与有效性。     

某火炮高平机手轮力6σ稳健优化设计

火炮高平机工作环境的温度存在一个波动范围,无法人为控制,影响到其平衡性能和高平机手轮力。传统的优化设计较少考虑温度等不确定性因素对手轮力的影响。为了提高高平机的稳健性和可靠性,降低高平机手轮力对温度变化的敏感度,基于6σ稳健优化方法,将工作温度作为影响手轮力的不确定因素,对高平机进行稳健优化设计。优化结果表明,在温度变化相同幅度时,手轮力变化值减小,优化结果降低了高平机手轮力对温度变化的敏感度,提高了高平机的稳健性。