考虑时序特性的分布式电源对配电网的影响

针对分布式电源出力时序特性与负荷时序特性,研究了风力发电和光伏发电在不同的渗透率组合情况下对系统网损的影响及网损最小时的电压变化规律。运用前推回代法潮流计算程序对其接入辐射状配电网前后有功损耗和电压进行精确计算,并采用系统总网损、电压改善程度来评价分布式电源对系统网损和电压的影响程度。通过IEEE13节点系统的仿真试验,总结了风力发电和光伏发电在不同的渗透率组合情况下对配电网功率损耗的影响,并找出了使网损最小的风力发电与光伏发电最优安装容量的比例。     

分布式光伏最大准入容量计算方法研究

随着分布式光伏越来越多地接入配电网,配电网对其消纳能力越来越受到人们的重视。介绍了分布式光伏的发电原理和出力模型,建立了分布式光伏最大准入容量计算模型,采用粒子群算法对模型进行求解,IEEE 33节点的算例仿真验证了模型的合理性和算法的有效性。     

基于风光储双层母线微电网的分布式模型预测控制

针对风光储互补的双层母线直流微电网系统,提出一种基于多端口变换器直流微电网分布式模型预测控制策略。首先,建立各个子微网系统中风电系统、光伏系统和储能系统的数学模型,其次,依据风电系统、光伏系统工作在经济最优,发电功率最大,储能系统作为补充的原则,采用分布式模型预测控制算法优化风电系统、光伏系统输出功率,保证高低压侧母线负荷跟踪性能和经济性能。最后,通过微网间DC/DC变换器进行PI控制,实现高低压母线间能量平衡,维持母线电压稳定。通过仿真、实验验证,所提控制策略能够实现各个微电网发电单元经济最优的同时,维持高低压侧母线的功率平衡和母线电压稳定,提高了系统的运行可靠性。     

全桥直流变换器在MPPT中的应用

由于光伏硅电池的独特输出特性,为能够将光伏阵列转换的能量以最大功率输出,就需要对光伏阵列的输出电流、电压进行实时控制,以实现最大功率点跟踪;另外,随着具有MPPT功能的DC/DC变换器的引入,对光伏发电系统的效率也产生了很大的影响.为提高光伏发电系统的效率,采用了移相全桥ZVS DC/DC 变换器作为光伏发电系统 MPPT 变换电路,并对应该具备 MPPT 功能的 DC/DC 变换器进行了设计.最后,采用了1 kW实验样机进行了一系列的实验.实验结果验证了该理论分析和设计的正确性.     

基于自抗扰控制的潮流发电系统最大功率跟踪控制

为了使潮流发电系统在各种工况下均能输出最大的功率，提出一种针对永磁同步电机的以线性自抗扰控制为核心的控制方法。潮流发电系统的输出功率与其获能机构的转速呈非线性关系，在其处于最优叶尖速比状态时可输出最大功率，依据叶尖速比与功率关系作为优化目标，一种新的基于线性自抗扰控制的发电机转速控制策略能够使整个潮流发电系统能够快速达到输出功率峰值。使用MATLAB/Simulink平台对潮流发电系统建立了仿真模型，以可控输入信号模拟不同工况，通过相应的输出验证控制策略的效果。仿真结果能够实现在多种工况下发电机转速快速跟踪峰值功率的预期，并给出各最优解的参数设置。     

农村配电网光伏与负荷相关性概率潮流计算

由于农村配电网的光伏出力与负荷存在较强的相关关系,针对其概率潮流计算处理随机变量相关系数矩阵非正定的不足,提出一种基于特征值分解法的Nataf变换处理光伏出力与负荷之间的相关性,并且结合CSMCMCS-L算法进行概率潮流计算,不仅具有较高的计算效率,而且相较于其他处理非正定性的方法计算更为简单,精度更高.采取光伏出力的综合建模方法,以准确反映不同情况下光伏出力特性.在IEEE33节点配电系统进行仿真验证了所提方法的有效性和准确性.     

并网光伏发电系统的建模与仿真

基于光伏电池的物理特性,建立了光伏阵列的PSCAD仿真模型。考虑到太阳能的波动性和随机性,开发了基于Boost电路的最大功率点跟踪(maximum power point tracking,MPPT)控制器模块,保证了光伏阵列始终保持最大功率输出;然后,采用合理的逆变器控制策略,将光伏阵列接入电网,建立完整的并网光伏发电系统。仿真结果表明,搭建的仿真模型能够准确地反映光伏电池和MPPT控制器的物理特性和准确性,以及在不同光照条件下光伏发电系统的运行特性,对于并网光伏发电系统的研究具有重要意义。     

分布式光伏发电并网对配电网继电保护的影响研究

大量分布式光伏发电系统并入电网,对传统单电源辐射状配电网继电保护配置带来诸多挑战。现介绍了分布式光伏发电系统并网方式,详细分析了分布式光伏发电系统并网后对配电网潮流分布、节点电压、继电保护整定配置等造成的影响,并提出了基于方向元件的配电网保护改进策略。     

基于区域配电网的0.4 kV分布式光伏实时发电功率预测

光伏并网发电对电网的稳定性有较大影响,特别是配电网0.4kV分布式光伏,其发电电量与实时发电功率对台区以及线路的稳定性将产生极大挑战。现对影响光伏发电的关键因素以及光伏实时发电功率预测方法进行了全面分析,并提出基于区域配电网的0.4kV分布式光伏实时发电功率预测算法,以实时预测区域0.4kV光伏发电功率,为管控0.4kV分布式光伏提供宝贵经验。     

基于蓄电池储能的主动配电网优化配置模型研究

主动配电网中分布式能源的合理配置是电网系统得以经济、可靠运行的重要因素。现建立了日前多时段优化模型,考虑了微型燃气轮机、光伏发电、风力发电等间歇性分布式发电及蓄电池储能在主动配电网中有功—无功功率的出力特性。由于优化配置模型涉及非线性潮流模型以及蓄电池状态切换的整数变量,所以难以快速准确地求解该优化配置问题。据此采用二阶锥优化算法松弛原模型,调和求解精度和计算速度的矛盾。在修改的西门子Benchmark低压配电网中验证了所提模型,结果表明,所提模型准确度高,适应性好,符合工程实际应用需求,二阶锥优化算法能有效快速地求解问题。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

Robust Impedance Control of Robots Using an Adaptive Interaction Force Observer

For robot interaction control,the interaction force between the robot and the manipulated object or environment should be monitored.Impedance control is a type ...     

Research on key techniques of expendable conductivity temperature depth measuring system

This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.     

CHARACTERISTCS OF FLUID FILM IN OPTIMIZED SPIRAL GROOVE MECHANICAL SEAL

In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relationship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.