Vibration Performance, Stability and Energy Transfer of Wind Turbine Tower via Pd Controller

In this paper,we studied the vibration performance,energy transfer and stability of the offshore wind turbine tower system under mixed excitations.The method of multiple scales is utilized to calculate the approximate solutions of wind turbine system.The proportional-derivative controller was applied for reducing the oscillations of the controlled system.Adding the controller to single degree of freedom system equation is responsible for energy transfers in offshore wind turbine tower system.The steady state solution of stability at worst resonance cases is studied and examined.The offshore wind turbine system behavior was studied numerically at its different parameters values.Furthermore,the response and numerical results were obtained and discussed.The stability is also analyzed using technique of phase plane and equations of frequency response.In addition,the numerical results and comparison between analytical and numerical solutions were obtained with MAPLE and MATLAB algorithms.

A brand new green coating technology for realizing the regulation of spherical propellant energy release process

To achieve the controllable release of energy of nitrocellulose-based propellants,this paper combines the cellulose-based nanocomposites aqueous coating(Surelease®-NC)with fluidized bed coating equipment to successfully prepare the coated spherical propellant for the first time.The effects of fluidized bed coating temperature,air velocity,flow speed and atomization pressure on the adhesion rate,coating integrity and coating uniformity of the coated spherical propellant were investigated,and the preparation of coated spherical propellant with homogeneous size and structural integrity was achieved for the first time.The microscopic morphology,chemical structure,water vapor adsorption behavior,combustion performance,and ageing resistance property of the coated spherical propellant were systematically investigated by,Fourier transforms infrared spectroscopy(FTIR),Micro confocal raman spectrometer,field scanning electron microscopy(SEM),dynamic vapor adsorption techniques,and closed bomb test,confirming the surface core-shell structure and the tightly bonded interfacial structure of coated spherical propellant.Meanwhile,the coated spherical propellant has good hygroscopic,excellent progressive burning and long storage stability.

Study on creep deformation and energy development of underground surrounding rock under four‐dimensional support

There is an urgent need to develop optimal solutions for deformation control of deep high‐stress roadways,one of the critical problems in underground engineering.The previously proposed four‐dimensional support(hereinafter 4D support),as a new support technology,can set the roadway surrounding rock under three‐dimensional pressure in the new balanced structure,and prevent instability of surrounding rock in underground engineering.However,the influence of roadway depth and creep deformation on the surrounding rock supported by 4D support is still unknown.This study investigated the influence of roadway depth and creep deformation time on the instability of surrounding rock by analyzing the energy development.The elastic strain energy was analyzed using the program redeveloped in FLAC3D.The numerical simulation results indicate that the combined support mode of 4D roof supports and conventional side supports is highly applicable to the stability control of surrounding rock with a roadway depth exceeding 520 m.With the increase of roadway depth,4D support can effectively restrain the area and depth of plastic deformation in the surrounding rock.Further,4D support limits the accumulation range and rate of elastic strain energy as the creep deformation time increases.4D support can effectively reduce the plastic deformation of roadway surrounding rock and maintain the stability for a long deformation period of 6 months.As confirmed by in situ monitoring results,4D support is more effective for the long‐term stability control of surrounding rock than conventional support.

基于ESC的电动汽车再生制动策略及能量回收

为了提高电动汽车制动过程的节能效果,构建了可以对电机回馈制动以及液压制动过程进行协调控制的方案,能够满足对车轮轮缸的协调控制效果。通过仿真测试发现,随着制动强度的变化,可实现电机回馈制动力与液压制动力间的良好协调,以此满足制动过程的控制要求,实现制动能量的高效回收。以电子稳定控制器(Electronic Stability Control⁃ler,ESC)实现的制动能量回收方案效率更高,并且随着制动减速度的降低变得更加显著。当车辆减速度为5m/s2时,液压与电机制动力同时发挥作用,实现协调控制的效果,且轮缸压力的调节功能,避免车轮发生抱死的情况。本方案可以达到更优的车辆控制性能,实现车辆制动能量的高效回收。可以使NDEC工况下的续驶里程提升9.35%,WLTP工况下上升37.2%,ECE工况下上升15.2%。

Energy Optimization of the Fin/Rudder Roll Stabilization System Based on the Multi-objective Genetic Algorithm （MOGA）

Energy optimization is one of the key problems for ship roll reduction systems in the last decade. According to the nonlinear characteristics of ship motion, the four degrees of freedom nonlinear model of Fin/Rudder roll stabilization can be established. This paper analyzes energy consumption caused by overcoming the resistance and the yaw, which is added to the fin/rudder roll stabilization system as new performance index. In order to achieve the purpose of the roll reduction, ship course keeping and energy optimization, the self-tuning PID controller based on the multi-objective genetic algorithm （MOGA） method is used to optimize performance index. In addition, random weight coefficient is adopted to build a multi-objective genetic algorithm optimization model. The objective function is improved so that the objective function can be normalized to a constant level. Simulation results showed that the control method based on MOGA, compared with the traditional control method, not only improves the efficiency of roll stabilization and yaw control precision, but also optimizes the energy of the system. The proposed methodology can get a better performance at different sea states.

Control and Stability of Large-scale Power System with Highly Distributed Renewable Energy Generation:Viewpoints from Six Aspects

Power systems are moving toward a low-carbon or carbon-neutral future where high penetration of renewables is expected.With conventional fossil-fueled synchronous generators in the transmission network being replaced by renewable energy generation which is highly distributed across the entire grid,new challenges are emerging to the control and stability of large-scale power systems.New analysis and control methods are needed for power systems to cope with the ongoing transformation.In the CSEE JPES forum,six leading experts were invited to deliver keynote speeches,and the participating researchers and professionals had extensive exchanges and discussions on the control and stability of power systems.Specifically,potential changes and challenges of power systems with high penetration of renewable energy generation were introduced and explained,and advanced control methods were proposed and analyzed for the transient stability enhancement of power grids.

Transient Stability Analysis during an Improved Coupling Procedure for an Induction Generator Based Wind Generation System to the Grid

For fixed speed wind turbines, the connection of its squirrel cage induction generator (SCIG) to the grid leads to inrush current which can reach an average of 2 p.u. up to 2.5 p.u. in higher wind speed even by using a soft starter. We propose in this paper a new soft starting of squirrel cage induction generator based wind turbine connected to the grid. Our strategy overcomes such transient instability problems and pinpoints rapidly synchronous speed regardless the wind speed acting on pitch angle. The proposed strategy ensures at least 50% reduction of inrush current and 18% gain of WTG starting time. A state model of the system is given including the wind turbine model and the SCIG model in the synchronous reference frame. Simulation results are analysed and compared to the classic coupling procedure.

Stability Analysis of DC-DC Converters with Energy Balance Control

With variation of parameters,DC-DC converters may change from a stable state to an unstable state,which severely degrades the performances of the converter system.In this article,by establishing the state-space average model,the stability and bifurcation of a boost and a buck-boost converter with energy balance control(EBC)is studied,respectively.Then the stability boundary and stable parameter domains are accurately predicted.The obtained stability region provides a parameter regulating range for converter design.Furthermore,compared with the one-cycle control(OCC)method,the EBC possesses an extended stable parameter domain,while avoiding unstable behaviors such as Hopf bifurcation,Quasi-periodic Oscillation even chaos,etc.The theoretic analysis is well validated through simulation and experiment.

含高比例新能源的电力系统频率稳定研究综述

作为“双碳”战略目标的关键载体,含高比例新能源的电力系统具有惯量水平低、调频能力差、抗扰性能弱等特征,对频率稳定带来了全新挑战,迫切需要深入认识能源转型背景下的频率稳定形态。该文按照“建模分析—稳定评估—调频控制”的路线,归纳近年来国内外关于频率稳定的研究及其应用进展。首先,梳理现有频率稳定定义的特点,将其引申为考虑暂态频率安全的广义频率稳定概念,分析含高比例新能源电力系统的频率响应过程;按照系统全局频率和网络节点频率两个视角分析现有特性建模与分析方法,分别总结频率稳定性、频率安全性的评估方法与评估指标,初步建立考虑频率时空分布特性的节点频率安全性指标;列举并归类源网荷储多主体参与系统调频的控制策略,分析相关频率调控措施的特点;最后,结合现有研究进展,对含高比例新能源的电力系统在频率响应特性建模、频率稳定机理评估以及频率稳定协调控制方面的未来发展方向和研究趋势进行展望。

汽车ESC系统干预转向不足性能测评与研究

为探索能有效激发出车辆在危险工况或极限工况下转向不足趋势的试验方法,并制定合理的指标以评价电子稳定性控制系统(ESC)转向不足控制性能,弥补国内外在该领域的不足,在分析ESC工作原理及基本要求的基础之上,利用多体动力学仿真软件ADAMS进行整车模型搭建,并用MATLAB/Simulink联合仿真,结合实车试验验证,提出了一种针对车辆ESC控制转向不足性能的测评方法,能有效地测试、评价在危险工况下ESC对于车辆转向不足的控制性能,完善了ESC测试评价体系。

基于TCN的跟网/构网混合型新能源场站并网系统小干扰稳定性快速评估

为支撑跟网/构网混合型新能源场站中机组控制方式快速切换,实现可适应电网强度变化的新能源场站安全稳定运行,提出基于时间卷积神经网络(temporal convolutional network,TCN)的跟网/构网混合型新能源场站并网系统小干扰稳定性快速评估方法。首先,构建跟网/构网混合型新能源场站聚合阻抗模型,通过特征值计算得到并网系统小干扰稳定裕度。然后,以并网系统短路比和新能源场站跟网/构网控制方式信息作为输入特征,以并网系统小干扰稳定裕度和阻尼比作为输出特征,训练TCN得到混合型新能源场站并网系统小干扰稳定性快速评估模型。经过训练的模型可根据短路比和跟网/构网混合型新能源场站中各机组的控制方式快速输出对应的小干扰稳定裕度和阻尼比。最后,以一个含10台风电机组的新能源场站为对象进行算例分析。结果表明:所提TCN方法相比于长短期记忆神经网络方法,在小干扰稳定裕度和阻尼比预测上的平均绝对百分比误差分别降低16.76%、14.75%;所提方法的计算耗时相对于特征值计算方法降低98.54%,从而验证所提小干扰稳定性快速评估方法的准确性与时效性。

区域新能源并网暂态功角稳定分析与紧急控制策略优化

随着新型电力系统发展和新能源机组不断投产,南方区域将形成多区域新能源与邻近常规电源联合集中接入系统的场景。新能源集中接入常与常规电源共用输电通道,将影响区域系统暂态稳定特性及输送通道的传输能力,使南方区域系统的安全稳定运行和风险防控面临了前所未有的挑战。为深入研究区域新能源送出的稳定特性建立了区域新能源交流集中送出的等值系统模型,分析了新能源并入对区域系统对暂态稳定特性影响的主要机理。基于等面积法则对区域送出系统暂态过程的加、减速面积进行了定量分析,提出了紧急控制切机策略的协调优化方法,实现区域送出传统机组与新能源机组紧急控制切机量及控制代价的最小化的切机策略配置。最终,基于广东区域海风火电打捆送出系统为例,对分析结果的正确性进行了验证。

基于时序卷积残差网络和鹈鹕优化算法的新能源电网安全稳定控制方法

随着“双碳”目标的推进,随机波动的新能源接入电网的规模和容量日益提升,严重影响电网的安全稳定运行。针对大干扰故障电压稳定控制问题,文章提出了一种基于时序卷积残差网络和鹈鹕优化算法的新能源电网电压安全稳定控制策略。首先,利用时序卷积信息损失少、感受野宽以及残差网络深层特征提取能力强的优势,构建基于时序卷积残差网络的电压稳定预测模型,映射出敏感节点电压时序特征和电压稳定之间的关系;其次,构建电压稳定控制模型,利用鹈鹕优化算法收敛速度快、搜索能力强的优势求解控制模型,得出最佳切机和切负荷动作措施;最后,进行了仿真验证。验证结果表明,所提方法提高了新能源电网电压安全稳定预测的准确性,通过最佳的电压稳定控制策略提高了电网故障后的安全稳定运行水平。

高比例分布式可再生能源交直流混合配电网运行调控:科学问题与技术框架

随着分布式可再生能源发电与中低压直流组网技术的快速发展,未来配电网必然向复杂的交直流混合形态演进,其运行调控技术面临许多新的挑战。在高比例分布式可再生能源交直流混合配电网(HR-HDN)运行调控技术发展需求分析的基础上,提炼出HR-HDN运行调控技术的3个科学问题,并以多类型可控设备协同、源-网-荷-储高度互动化和市场化需求为研究主线,从稳定控制、故障主动防御与恢复、电力市场机制辅助调控以及“平台+数据”数字化集成调控4个方面,提出了HR-HDN的运行调控技术框架。最后,对HR-HDN运行调控关键技术的未来发展进行了展望。

计及高比例新能源多种控制方式及运行约束的连续潮流

高比例新能源电网的电压稳定问题突出,连续潮流是电压稳定分析的重要工具。现有含电压源换流器(VSC)电源电网的连续潮流未充分考虑VSC的多种控制方式以及运行约束,导致电压稳定裕度计算的准确性不足。文中提出同时计及新能源并网VSC的输出电流约束和内电势约束,以及考虑构网型新能源恒电压控制、无功功率-电压下垂控制和跟网型新能源恒无功控制的连续潮流模型和计算方法,给出了由约束导致的控制方式切换逻辑和分岔点类型识别方法。通过改造的IEEE 39节点系统算例结果表明,所提模型与算法提升了传统连续潮流方法对高比例新能源电网静态电压稳定分析的适用性。

超导磁储能装置提高柔性直流配电系统稳定性的研究

柔性直流配电系统中定功率控制的换流器具有恒功率负载特性,会降低系统阻尼,对系统的稳定性产生不利影响。针对该问题,在直流配电系统中加入超导磁储能SMES(superconducting magnetic energy storage)装置来提高系统的稳定性。推导了柔性直流配电系统的反馈控制模型,采用频域分析法研究了换流器恒功率负载特性对系统稳定性的影响,并结合数学模型和频域分析,指出SMES装置能够为电网提供正阻尼,增大了系统开环传递函数在剪切频率处的相位裕度,从而改善了系统稳定性。为防止超导磁体两端电压过高,SMES装置与直流配电网连接的DC/DC换流器需具备一定的电压调节性能,因此研究了采用模块化多电平DC/DC换流器DC-MMC(modular multilevel DC/DC converter)的SMES装置,通过调节子模块个数灵活设置换流器电压变比,在实现换流器能量双向流动的同时控制超导磁体两端电压,以保护储能装置。最后通过时域仿真波形验证了采用DC-MMC的SMES装置在提高柔性直流配电系统稳定性方面的可行性和有效性。

交直流电力系统电压稳定性控制方法

交直流电力系统电压稳定性控制方法主要集中在单一的调节手段上进行定功率控制,导致电压区域不稳定,发生大规模波动,为此研究交直流电力系统电压稳定性控制方法。首先,通过对交直流电力系统的电压进行分区,揭示系统电压分布的特点和规律。电压分区后,构建储能单元的数学模型,针对直流配电网的惯性特性进行详细分析,确定电压稳定负荷裕度的计算方法,以评估系统的稳定性水平,最后,结合电压暂态稳定性控制输出,实现交直流电力系统电压稳定性控制。实验结果显示,与无功补偿方法和有功潮流优化方法相比,研究的交直流电力系统电压稳定性控制方法的交流子网的电压区域稳定,未发生大规模波动,具有实际的应用价值。

水电高占比下风电接入对系统稳定性影响

随着绿色清洁高效能源基地的构建,以水电为主体的水风互补成为我国西南能源开发的重要特征。为研究在典型水电系统中接入风电对系统稳定性带来的影响,首先,针对水风互补系统以转矩分析法分析了风电接入对系统频率和功角稳定性的影响,并通过算例和Prony分析验证了风速与风电渗透率对系统稳定性的影响。结果表明,风电的接入在一定程度上可以削弱传统水电系统的超低频振荡,而风电接入互联送端系统会导致区域等值惯量的下降,进而使系统区域间低频振荡风险加剧。其次,考虑风电的接入会诱发区域间低频振荡,在风电系统中引入风电的附加综合虚拟惯性与阻尼控制。算例与Prony分析验证了该控制策略能有效提高系统稳定性。最后,在区域间大规模风电接入场景下,利用改进的鲸鱼算法对风电的附加控制器参数进行了优化;结果表明,参数的整定有效提高了系统的频率以及功角稳定性。

基于虚拟母线电压控制的构网型储能变流器稳定性优化研究

构网型储能变流器作为高比例新能源接入电网的关键设备在强电网下存在稳定性问题。针对此问题,本工作提出一种基于虚拟母线电压控制的构网型储能变流器稳定性优化方法。首先,建立构网型储能变流器状态空间小信号模型,利用特征根分析法得出构网型储能变流器强电网下稳定性变差甚至振荡失稳的结论。然后,提出基于虚拟母线电压控制的稳定性优化方法,通过改变有功功率环跟踪电网电压相位的位置等效提高电网阻抗,从而提高强电网下构网型储能变流器系统并网的稳定性。接着,分析不同工况下加入虚拟母线电压控制前后系统的特征根变化趋势和稳定性提升效果,同时也分析了虚拟母线电压控制参数中补偿系数k和时间常数t对稳定性的影响并给出一般参数设计范围。最后,在MATLAB/Simulink中搭建构网型储能变流器并网模型进行时域验证,进一步搭建硬件在环实验平台进行半实物验证,验证结果表明基于虚拟母线电压控制的构网型储能变流器在强电网下的稳定性明显提高。

电化学储能参与电网暂态功角稳定控制研究

针对电网传统紧急控制资源的日益匮乏,利用电化学储能功率控制的快速性与双向控制能力,研究将其应用于电网暂态功角稳定控制。首先推导了计及电化学储能的双机等值模型,基于扩展等面积定则分析了储能改善电网暂态稳定裕度的原理。其次,提出了一种考虑设备保护与系统保护动作时序差异的储能电站有效工作时长计算方法,改善了紧急控制储能的工作效率。提出了计及储能的基于性能代价比多类措施协调控制策略制定方法,兼顾紧急控制的安全性与经济性,为电网暂态紧急控制提供在线辅助决策支撑。进一步提出了储能电站全景监控系统架构,为实现储能电站与电网紧急控制系统的交互提供了技术实践思路。最后西北电网实际算例验证了所提方法的有效性与合理性。研究结论可为规模化储能与高比例新能源电网第二道防线的扩展与建设提供理论参考。