Multi-factor principle for electrolyte additive molecule design for facilitating the development of electrolyte chemistry

When I read the paper“Electrolytes enriched by potassium perfluorinated sulfonates for lithium metal batteries”from Prof.Jianmin Ma’s group,which was published in Science Bulletin(doi.org/10.1016/j.scib.2020.09.018),I felt excited as presented a multi-factor principle for applying potassium perfluorinated sulfonates to suppress the dendrite growth and protect the cathode from the viewpoint of electrolyte additives.The effects of these additives are revealed through experimental results,molecular dynamics simulations and first-principle calculations.Specifically,it involves the influence of additives on Li^(+)solvation structure,solid electrolyte interphase(SEI),Li growth and nucleation.Following the guidance of the multi-factor principle,every part of the additive molecule should be utilized to regulate electrolytes.This multifactor principle for electrolyte additive molecule design(EAMD)offers a unique insight on understanding the electrochemical behavior of iontype electrolyte additives on both the Li metal anode and high-voltage cathode.In these regards,I would be delighted to write a highlight for this innovative work and,hopefully,it may raise more interest in the areas of electrolyte additives.

Action Origin of the Cosmos

In physical information theory elementary objects are represented as correlation structures with oscillator properties and characterized by action. The procedure makes it possible to describe the photons of positive and negative charges by positive and negative real action;gravitons are represented in equal amounts by positive and negative real, i.e., virtual action, and the components of the vacuum are characterized by deactivated virtual action. An analysis of the currents in the correlation structures of photons of static Maxwell fields with wave and particle properties, of the Maxwell vacuum and of the gravitons leads to a uniform three-dimensional representation of the structure of the action. Based on these results, a basic structure consisting of a system of oscillators is proposed, which describe the properties of charges and masses and interact with the photons of static Maxwell fields and with gravitons. All properties of the elemental components of nature can thus be traced back to a basic structure of action. It follows that nature can be derived from a uniform structure and this structure of action must therefore also be the basis of the origin of the cosmos.

Chatter Suppression with Ultrasonic Elliptical Vibration Based on Energy Principle

A new method is proposed to suppress chatter, in which the ultrasonic elliptical vibration is added on the cutting tool edge. It results in the fact that the rake face of tool is separated from the chip and the direction of the frictional force between the rake face and the chip is reversed in each cycle of elliptical vibration cutting. The experimental investigations show that the chatter can be suppressed effectively by adding ultrasonic elliptical vibration on the cutting tool edge. In order to make clear the reason of chatter suppression, the mechanism of chatter suppression is analyzed theoretically from the viewpoint of energy.

Limit cycle oscillation suppression of 2-DOF airfoil using nonlinear energy sink

This paper presents a novel mechanical attachment, i.e., nonlinear energy sink （NES）, for suppressing the limit cycle oscillation （LCO） of an airfoil. The dynamic responses of a two-degree-of-freedom （2-DOF） airfoil coupled with an NES are studied with the harmonic balance method. Different structure parameters of the NES, i.e., mass ratio between the NES and airfoil, NES offset, NES damping, and nonlinear stiffness in the NES, are chosen for studying the effect of the LCO suppression on an aeroelastic system with a supercritical Hopf bifurcation or subcritical Hopf bifurcation, respectively. The results show that the structural parameters of the NES have different influence on the supercritical Hopf bifurcation system and the subcritical Hopf bifurcation system.

Exploration on Hail Suppression Work of Tobacco in Yuxian County

Climatic characteristics of hail,principle of hail suppression and implementation situation of local hail suppression work in Yuxian County were introduced. Moreover,the problems existed in hail suppression work of tobacco in Yuxian County were analyzed,and corresponding measures and suggestions were proposed to improve planting benefit of local tobacco.

Improvement of circuit oscillation generated by underwater high voltage pulse discharges based on pulse power thyristor

High voltage fracturing technology was widely used in the field of reservoir reconstruction due to its advantages of being clean, pollution-free, and high-efficiency. However, high-frequency circuit oscillation occurs during the underwater high voltage pulse discharge process, which brings security risks to the stability of the pulse fracturing system. In order to solve this problem, an underwater pulse power discharge system was established, the circuit oscillation generation conditions were analyzed and the circuit oscillation suppression method was proposed. Firstly, the system structure was introduced and the charging model of the energy storage capacitor was established by the state space average method. Next, the electrode high-voltage breakdown model was established through COMSOL software, the electrode breakdown process was analyzed according to the electron density distribution image, and the plasma channel impedance was estimated based on the conductivity simulation results. Then the underwater pulse power discharge process and the circuit oscillation generation condition were analyzed, and the circuit oscillation suppression strategy of using the thyristor to replace the gas spark switch was proposed. Finally, laboratory experiments were carried out to verify the precision of the theoretical model and the suppression effect of circuit oscillation. The experimental results show that the voltage variation of the energy storage capacitor, the impedance change of the pulse power discharge process, and the equivalent circuit in each discharge stage were consistent with the theoretical model. The proposed oscillation suppression strategy cannot only prevent the damage caused by circuit oscillation but also reduce the damping oscillation time by77.1%, which can greatly improve the stability of the system. This research has potential application value in the field of underwater pulse power discharge for reservoir reconstruction.

基于功率微分项的双VSG有功功率振荡抑制策略

针对虚拟同步发电机(VSG)双机并联运行时产生的有功功率振荡问题,通过建立双VSG系统的小信号模型,分析了有功功率振荡产生的机理,提出一种基于改进虚拟阻抗的瞬态功率均分策略和一种基于功率微分项的自适应惯量和阻尼的功率振荡抑制策略,将有功功率微分项与角加速度结合起来实现惯量的自适应调节,同时将有功功率微分项引入阻尼控制环节以替代传统的阻尼项,实现阻尼的自适应调节。所提出的策略可以使动态时VSG之间的角频率差更快速地趋近于零,从而减小有功功率振荡的超调,改善频率动态响应性能。搭建了VSG并联的仿真模型,仿真结果表明:所提改进控制策略可以使瞬态时实现有功均分,使动态时的有功功率振荡超调减小41%,振荡过程减小了1秒。

含静止无功发生器的直驱风电并网系统稳定性分析及振荡抑制策略

风电并网系统稳定性分析及振荡抑制策略大多集中于风电场本身,针对含静止无功发生器(SVG)的直驱风电并网系统研究较少。基于特征值灵敏度筛选出对含SVG的直驱风电并网系统稳定性较显著的控制通道,然后基于独立通道分析设计理论将并网系统由多输入多输出耦合系统等效拆分为多个单输入单输出控制通道,在定性分析并网系统稳定性的同时定量评估不同控制通道间的交互作用程度。为抑制控制通道间的交互作用,提出了基于H∞鲁棒控制的次同步振荡抑制策略。通过电磁暂态仿真,验证了基于独立通道分析设计理论分析并网系统稳定性的正确性以及基于H∞鲁棒控制的次同步振荡抑制策略的有效性。

配电网低频非线性振荡引发PT保险熔断的机理及抑制措施

电缆的接入使配电网中性点不接地系统对地电容电流增大,产生由单相接地故障引发的低频非线性振荡,导致电磁式电压互感器(potential transformer,PT)保险熔断,严重影响系统安全运行。首先,分析了低频非线性振荡导致PT保险熔断的原理,并基于ATP⁃EMTP平台对10 kV中性点不接地系统进行了仿真计算,计算表明,低频非线性振荡最大过电压小于2.0 p.u.,故障0.1 s后电流接近熔断器熔断电流,系统对地电容增大、零序电阻减小,保险熔断风险增大;然后,仿真验证了4PT接线和PT高压侧中性点串接压敏电阻抑制措施的有效性,并计算了零序电压测量误差;最后,建立10 kV系统的低频非线性振荡试验平台,验证仿真的有效性,对提高配电网PT运行安全性具有参考价值。

虚拟同步耦合下储能的频率支撑与功率振荡多目标协调控制

准确评估系统惯量、阻尼和一次调频需求,弱化虚拟同步机阻尼支撑和一次调频间的耦合性,是实现储能并网发电系统多目标协调控制的关键。基于同步机的功率响应方程,建立虚拟调速器系统,弱化虚拟同步机单位调节功率和阻尼的耦合性。根据同调发电系统的频率稳定约束,量化评估储能的单位调节功率和惯量需求,以保障系统频率安全。根据阻尼比约束设计储能阻尼,以保障同调发电系统的振荡抑制能力,并结合频率安全需求提出含虚拟调速系统的虚拟同步多目标协调主动支撑控制策略,充分发挥储能的惯量、一次调频及阻尼支撑潜力。搭建风储高渗透率并网仿真系统,验证所提控制策略可显著改善储能支撑系统频率稳定和抑制功率振荡的能力。

基于功角轨迹灵敏度的交直流电网振荡抑制优化

高压直流线路稳态功率影响交直流互联系统功角稳定性。为抑制同步发电机功角振荡,基于功角轨迹灵敏度,提出对故障前直流功率的优化方法。建立交直流系统轨迹灵敏度解析表达,引入中间变量确定功角和稳态直流功率关系。推导潮流解对稳态直流功率的灵敏度,计算轨迹灵敏度初值。基于时域仿真中网络约束方程,推导含直流变量的不平衡项。以功角差最小为目标,提出稳态直流功率优化模型,采用内点法求解。仿真结果验证了所提算法对功角振荡的抑制效果。

基于偏转角抑制的改进人工势场法路径规划

针对传统人工势场法在实际应用中存在的局部最极小值、目标不可达以及路径震荡等问题,文种提出了一种基于偏转角抑制的改进人工势场法。该方法以传统人工势场法为基础,采用改进斥力势场函数保证目标点为全局势能最低点。在路径解算中引入偏转角抑制因子来抑制无人车行驶过程中过大的偏转角,在无人车陷入局部极小值点后每一步的路径解算中都添加新的虚拟目标点,直至无人车累积一定的偏转角摆脱障碍物群。仿真实验结果表明,该算法可以在不影响无人车避障的情况下减少规划路径的震荡性,并能够使无人车逃脱复杂障碍物群顺利到达目标点,规划出一条有效、简短以及震荡较少的路径。

新能源并网系统引发的复杂振荡问题及其对策研究

受电力电子变流器的交互作用等因素影响,新能源并网系统存在复杂的振荡问题,因此分析了新能源并网系统引发的复杂振荡问题,并进行对策研究。结合振荡机制,分析了新能源并网系统引发的振荡问题主要表现形式,结合分析结果,将保持新能源并网系统稳定的前提——具有稳定的流形作为核心,构建合理的阻尼控制器,实现对振荡的抑制。在测试结果中,设计抑制对策下对应的有功功率振荡幅度最小,发生振荡的次数也最少,与对照组相比具有明显优势。

基于能量函数和改进虚拟同步控制的低频振荡抑制策略

随着可再生能源发电的普及和电力电子设备装机规模的扩大,电网稳定性显著降低,虚拟同步发电机(VSG)技术近年来备受关注。然而,VSG与同步发电机并网受到扰动时,VSG虚拟转子转速会发生突变,从而引起系统输出大幅度波动。为了抑制这些波动,本文提出一种基于超前滞后控制环的附加功率和惯量的VSG控制方法。通过引入能量函数的概念,得到一种新的控制策略。利用能量函数,分析VSG参数对系统低频振荡的影响,并通过调节VSG参数实现对VSG输出能量的控制,减少VSG与系统之间的能量流动,进而更好地抑制可再生能源发电系统的低频振荡。通过Matlab/Simulink和远宽半实物仿真平台证明了所提策略对可再生能源发电系统低频振荡具有良好的抑制效果。

沥青抑烟净味剂功能性验证研究

该研究旨在探究物理吸附材料和化学抑制材料对沥青烟气中颗粒物和苯类有机物释放的影响,以减少沥青烟气对施工人员健康和环境造成的危害。在实验室内模拟了沥青实际使用情况,采用聚四氟乙烯滤膜和环己烷吸收液对沥青烟气进行收集,通过重量法和气相色谱质谱联用试验研究了活性炭和净味剂B的抑制效果,并进一步考虑了二者对沥青路用性能的影响。通过中心复合模型得到了复合抑烟净味剂的最佳配方,即活性炭掺量为3.28%,净味剂B掺量为3‰。通过红外光谱试验和核磁共振氢谱试验得到了抑烟净味剂对沥青微观结构的影响,结果表明净味剂B主要由酯类化合物组成,复合抑烟净味剂的主要原理是通过使支链碳链变长,提高沥青沸点,从而达到了抑烟净味的效果。

基于驯服钟控技术的时间频率源设计

标准时间频率信号是系统高效工作的基石,越来越高的时间频率测量精度对时频信号的产生提出了高稳定高准确度的要求。介绍了时间频率源的基本概念,阐述了一种基于驯服钟控技术的高稳定度高准确度时间频率源的基本工作原理及其设计,其输出的频率信号短期稳定度可达1.46×10-13/s。该设计方案已经成功应用于多个车载测控通信系统。

直驱风电场经MMC-HVDC并网送端系统稳定性分析及振荡抑制

基于模块化多电平换流器MMC(modular multilevel converter)的高压直流输电HVDC(high voltage direct current transmission)因具有无源网络支撑等优势而被广泛应用于大容量新能源外送消纳。受电力电子设备交互作用等因素影响,送端系统易发生振荡失稳现象。首先,建立了直驱风电场经MMC-HVDC并网送端系统的小扰动线性化模型,分析了风场有功输出对系统稳定性的影响。然后,建立了MMC及风机并网变流器交流侧dq阻抗模型,从阻抗角度揭示了送端系统振荡失稳机理。进一步,提出了基于MMC交流电压控制外环q轴附加阻尼的振荡抑制策略,可满足系统满功率范围内的运行稳定性要求。最后,基于全比例模型的仿真结果验证了所提振荡抑制策略的有效性。

基于改进虚拟同步发电机控制的功率交互振荡抑制策略

在指令功率发生扰动时,虚拟同步发电机控制环路易产生功率交互振荡,威胁系统的安全稳定运行。为此,提出一种基于改进虚拟同步发电机控制的功率交互振荡抑制策略。基于相对增益矩阵原理研究不同系统参数变化时虚拟同步发电机输出功率间交互作用的变化规律;采用转速阻尼功率高通反馈改进虚拟同步发电机有功功率-频率控制环路,并通过绘制Bode图对比传统虚拟同步发电机控制策略与改进虚拟同步发电机控制策略的暂态和稳态性能;利用相对增益矩阵原理分析改进虚拟同步发电机控制策略的有功功率环路交互作用情况。仿真及实验结果表明,所提策略可有效实现虚拟同步发电机交互振荡的抑制。

THE THREE-POINT FIFTH-ORDER ACCURATE GENERALIZED COMPACT SCHEME AND ITS APPLICATIONS

A three-point fifth-order accurate generalized compact scheme (GC scheme) with a spectral-like resolution is constructed in a general way. The scheme satisfies the principle of stability and the principle about suppression of the oscillations, therefore numerical errors can decay automatically and no spurious oscillations are generated around shocks. The third-order TVD type Runge-Kutta method is employed for the time integration, thus making the GC scheme best suited for unsteady problems. Numerical results show that the GC scheme is shock-capturing. The time-dependent boundary conditions proposed by Thompson are well employed when the algorithm is applied to the Euler equations of gas dynamics.

新能源基地经LCC-HVDC送出系统振荡机理分析与抑制策略(三):振荡抑制策略

针对新能源基地经电网换相换流器型高压直流(line commutated converter-based high voltage direct current,LCC-HVDC)送出系统次/超同步振荡问题,现有研究主要通过新能源侧阻抗重塑设计实现振荡抑制,考虑到实际系统并网台数多、机型繁杂、故障穿越性能等因素制约,其设计裕度受到限制。该文通过LCC-HVDC阻抗重塑实现系统次/超同步振荡抑制。首先,提出送端换流站定触发角控制、受端换流站定直流电流控制的LCC-HVDC阻抗重塑控制策略,建立计及阻抗重塑的LCC-HVDC阻抗解析模型,并验证阻抗模型的准确性。然后,对比分析重塑前后阻抗特性变化,阐述阻抗重塑控制策略的作用机理,消除原有送端换流站直流电流环与功率电路重叠效应所产生的负阻尼。进一步,基于LCC-HVDC阻抗重塑,优化新能源并网点系统阻抗特性,提升直驱风机(permanent magnet synchronous generator,PMSG)、双馈风机(doubly-fed induction generator,DFIG)以及光伏(photovoltaic,PV)不同类型新能源基地经LCC-HVDC送出系统稳定裕度,消除系统次/超同步振荡风险。最后,不同类型新能源基地经LCC-HVDC送出系统仿真结果验证了该文提出的基于LCC-HVDC阻抗重塑振荡抑制策略的有效性。