Signal filtering and differential acquisition are classic yet challenging issues in control engineering.The discrete-time optimal control(DTOC)based on classic tracking differentiator(TD)can effectively extract differ...Signal filtering and differential acquisition are classic yet challenging issues in control engineering.The discrete-time optimal control(DTOC)based on classic tracking differentiator(TD)can effectively extract differentiation signals and filter signals,while eliminating the chattering problem that arises during the discretization of the continuous solution.However,under external disturbance,the convergence mode may change,leading to overshoot and noise amplification.In this paper,a dual-switching strategy is proposed,which can alternate between the base double-integral system and its dual system according to the quadrant of the system’s state.And a novel linearized control law is also introduced,deriving a novel dual-switch tracking differentiator.Further analysis of system convergence and time optimality is provided.Simulation results show that the application of this dual-switching strategy notably reduces overshoot in both tracking and differential signals while enhancing noise filtering performance.Moreover,experiments conducted on a permanent magnet synchronous motor(PMSM)platform,where the proposed TD acts as a filter in the speed feedback loop,demonstrate that the standard deviation between the reference speed and the target speed(at a constant speed of 378 r/min)decreased from 5.63 r/min to 4.93 r/min,compared to the moving average algorithm.展开更多
新型电力系统下,大量新能源电源及电力电子设备接入交流电网。发生母线区内故障时,受控制策略影响,故障电流幅值受控,角度受控,谐波含量高,母线比率差动保护的动作性能下降,因此文中提出一种适用于新型电力系统的母线比率差动保护改进...新型电力系统下,大量新能源电源及电力电子设备接入交流电网。发生母线区内故障时,受控制策略影响,故障电流幅值受控,角度受控,谐波含量高,母线比率差动保护的动作性能下降,因此文中提出一种适用于新型电力系统的母线比率差动保护改进算法。首先,介绍传统比率差动算法的基本原理,并分析新型电力系统下该算法存在的问题;然后,提出不受故障电流角差及谐波影响的母线比率差动保护改进算法,将相位存在差异的各支路电流相量映射到同一坐标系下,并进行差流和制动电流计算,分析母线比率差动保护改进算法在母线区内外故障及区外故障电流互感器(current transformer,CT)饱和时的动作性能,提出母线比率差动保护改进逻辑;最后,基于实时数字仿真(real time digital simulation,RTDS),对比传统比率差动保护和改进比率差动保护的动作性能,证明改进比率差动保护能够在不降低保护动作可靠性的前提下提高动作灵敏性。展开更多
【目的】探究农户分化对农业生产性投资的直接影响机制和间接影响机制,为解决中国当前农业生产性投资不足问题、制定农地流转等相关政策提供理论借鉴和参考。【方法】采用2012—2020年中国家庭追踪调查(China family panel studies,CFPS...【目的】探究农户分化对农业生产性投资的直接影响机制和间接影响机制,为解决中国当前农业生产性投资不足问题、制定农地流转等相关政策提供理论借鉴和参考。【方法】采用2012—2020年中国家庭追踪调查(China family panel studies,CFPS)数据,通过建立OLS模型、面板固定效应模型、中介效应模型进行计量分析,并进一步做出稳健性、内生性检验。【结果】农户分化对农业生产性投资有显著负向影响;农地流转在农户分化与农业生产投资间发挥部分中介作用,农户分化通过影响农地流转进而对农业生产性投资产生影响。【结论】要充分关注农户分化给农业生产造成粗放化、副业化甚至撂荒等潜在危害;积极采取措施发挥农地流转对农业生产投资的刺激作用。展开更多
基金Project(QZKFKT2023-012)supported by the State Key Laboratory of Heavy-duty and Express High-power Electric Locomotive,China。
文摘Signal filtering and differential acquisition are classic yet challenging issues in control engineering.The discrete-time optimal control(DTOC)based on classic tracking differentiator(TD)can effectively extract differentiation signals and filter signals,while eliminating the chattering problem that arises during the discretization of the continuous solution.However,under external disturbance,the convergence mode may change,leading to overshoot and noise amplification.In this paper,a dual-switching strategy is proposed,which can alternate between the base double-integral system and its dual system according to the quadrant of the system’s state.And a novel linearized control law is also introduced,deriving a novel dual-switch tracking differentiator.Further analysis of system convergence and time optimality is provided.Simulation results show that the application of this dual-switching strategy notably reduces overshoot in both tracking and differential signals while enhancing noise filtering performance.Moreover,experiments conducted on a permanent magnet synchronous motor(PMSM)platform,where the proposed TD acts as a filter in the speed feedback loop,demonstrate that the standard deviation between the reference speed and the target speed(at a constant speed of 378 r/min)decreased from 5.63 r/min to 4.93 r/min,compared to the moving average algorithm.
文摘新型电力系统下,大量新能源电源及电力电子设备接入交流电网。发生母线区内故障时,受控制策略影响,故障电流幅值受控,角度受控,谐波含量高,母线比率差动保护的动作性能下降,因此文中提出一种适用于新型电力系统的母线比率差动保护改进算法。首先,介绍传统比率差动算法的基本原理,并分析新型电力系统下该算法存在的问题;然后,提出不受故障电流角差及谐波影响的母线比率差动保护改进算法,将相位存在差异的各支路电流相量映射到同一坐标系下,并进行差流和制动电流计算,分析母线比率差动保护改进算法在母线区内外故障及区外故障电流互感器(current transformer,CT)饱和时的动作性能,提出母线比率差动保护改进逻辑;最后,基于实时数字仿真(real time digital simulation,RTDS),对比传统比率差动保护和改进比率差动保护的动作性能,证明改进比率差动保护能够在不降低保护动作可靠性的前提下提高动作灵敏性。
文摘【目的】探究农户分化对农业生产性投资的直接影响机制和间接影响机制,为解决中国当前农业生产性投资不足问题、制定农地流转等相关政策提供理论借鉴和参考。【方法】采用2012—2020年中国家庭追踪调查(China family panel studies,CFPS)数据,通过建立OLS模型、面板固定效应模型、中介效应模型进行计量分析,并进一步做出稳健性、内生性检验。【结果】农户分化对农业生产性投资有显著负向影响;农地流转在农户分化与农业生产投资间发挥部分中介作用,农户分化通过影响农地流转进而对农业生产性投资产生影响。【结论】要充分关注农户分化给农业生产造成粗放化、副业化甚至撂荒等潜在危害;积极采取措施发挥农地流转对农业生产投资的刺激作用。
