Optimal guidance strategy for flexible load based on hybrid direct load control and time of use

The time-of-use(TOU)strategy can effectively improve the energy consumption mode of customers,reduce the peak-valley difference of load curve,and optimize the allocation of energy resources.This study presents an Optimal guidance mechanism of the flexible load based on strategies of direct load control and time-of-use.First,this study proposes a period partitioning model,which is based on a moving boundary technique with constraint factors,and the Dunn Validity Index(DVI)is used as the objective to solve the period partitioning.Second,a control strategy for the curtailable flexible load is investigated,and a TOU strategy is utilized for further modifying load curve.Third,a price demand response strategy for adjusting transferable load is proposed in this paper.Finally,through the case study analysis of typical daily flexible load curve,the efficiency and correctness of the proposed method and model are validated and proved.

Direct loading of atoms from a macroscopic quadrupole magnetic trap into a microchip trap

We demonstrate the direct loading of cold atoms into a microchip 2-mm Z-trap, where the evaporative cooling can be performed efficiently, from a macroscopic quadrupole magnetic trap with a high loading efficiency. The macroscopic quadrupole magnetic trap potential is designed to be moveable by controlling the currents of the two pairs of anti-Helrnholtz coils. The cold atoms are initially prepared in a standard six-beam magneto-optical trap and loaded into the macroscopic quadrupole magnetic trap, and then transported to the atom chip surface by moving the macroscopic trap potential. By means of a three-dimensional absorption imaging system, we are able to optimize the position alignment of the atom cloud in the macroscopic trap and the microchip Z-shaped wire. Consequently, with a proper magnetic transfer scheme, we load the cold atoms into the microchip Z-trap directly and efficiently. The loading efficiency is measured to be about 50%. This approach can be used to generate appropriate ultracold atoms sources, for example, for a magnetically guided atom interferometer based on atom chip.

Fault Location Method for Overhead Feeders with Distributed Generation Units Based on Direct Load Flow Approach

This paper proposes a novel fault location method for overhead feeders,which is based on the direct load flow approach.The method is developed in the phase domain to effectively deal with unbalanced network conditions,while it can also handle any type of distributed generation(DG)units without requiring equivalent models.By utilizing the line series parameters and synchronized or unsynchronized voltage and current phasor measurements taken from the sources,the method reliably identifies the most probable faulty sections.With the aid of an index,the exact faulty section among the multiple candidates is determined.Extensive simulation studies for the IEEE 123-bus test feeder demonstrate that the proposed method accu-rately estimates the fault position under numerous short-circuit conditions with varying prefault system loading conditions,fault resistances,and measurement errors.The proposed method is promising for practical applications due to the limited number of required measurement devices as well as the short computation time.

Direct load control by distributed imperialist competitive algorithm

Demand side management techniques have drawn significant attentions along with the development of smart grid.This paper proposes a new direct load control(DLC)model for scheduling interruptible air conditioner loads.The model is coordinated with the unit commitment and economic dispatch to minimize the total operation cost over the whole dispatch horizon.The network constraints are also considered in the model.To ensure the thermal comfort of the occupants,we are among the first to incorporate the advanced two-parameter thermal inertia dynamical model of customer houses into the DLC model to calculate the indoor temperature variation.This paper also proposes a distributed imperialist competitive algorithm to effectively solve the model.The simulation studies prove the efficiency of the proposed methodology.

Numerical study of AE and DRA methods in sandstone and granite in orthogonal loading directions

The directional dependency of the acoustic emission （AE） and deformation rate analysis （DRA） methods was analyzed, based on the contact bond model in the two-dimensional particle flow code （PFC2D） in two types of rocks, the coarse-grained sandstone and Aue granite. Each type of rocks had two shapes, the Brazilian disk and a square shape. The mechanical behaviors of the numerical model had already been verified to be in agreement with those of the physical specimens in previous research. Three loading protocols with different loading cycles in two orthogonal directions were specially designed in the numerical tests. The results show that no memory effect is observed in the second loading in the orthogonal direction. However, both the cumulative crack number of the second loading and the differential strain value at the inflection point are influenced by the first loading in the orthogonal direction.

Application of bi-directional static loading test to deep foundations

Bi-directional static loading test adopting load cells is widely used around the world at present, with increase in diameter and length of deep foundations. In this paper, a new simple conversion method to predict the equivalent pile head load-settlement curve considering elastic shortening of deep foundation was put forward according to the load transfer mechanism. The proposed conversion method was applied to root caisson foundation in a bridge and to large diameter pipe piles in a sea wind power plant. Some new load cells, test procedure, and construction technology were adopted based on the applications to different deep foundations, which could enlarge the application scopes of bi-directional loading test. A new type of bi-directional loading test for pipe pile was conducted, in which the load cell was installed and loaded after the pipe pile with special connector has been set up. Unlike the conventional bi-directional loading test, the load cell can be reused and shows an evident economic benefit.

Development of a dynamic load direct shear apparatus for the study of permafrost

The dynamic parameters of permafrost are crucial to and directly affect the accuracy of engineering design and numerical simulation. This paper describes a new dynamic load direct shear apparatus that was developed to measure these parameters. The power systems and measurement and control systems of the device are described, as is a successful validation experiment. The results show that this dynamic load direct shearing device can accurately derive dynamic shear parameters within a certain range of frequencies and ampli- tudes of shear load.

Oblique and Multi-Directional Random Wave Loads on Vertical Breakwaters

Extensive 3-D model tests have been performed to study the effects of wave obliquity and multi-directionality on the wave loads acting on vertical breakwaters. The variation of horizontal and uplift forces acting on an unit length of a breakwater with wave direction, the longitudinal distribution of wave forces, as well as the longitudinal load reduction are analyzed. Some empirical formulae of the longitudinal distribution coefficient and the longitudinal load reduction factor are presented for practical use.

DIRECT DIGITAL DESIGN AND SIMULATION OF MESHING IN WORM-GEAR DRIVE

A direct digital design method （DDDM） of worm-gear drive is proposed. It is directly based on the simulation of manufacturing process and completely different from the conventional modeling method. The loaded tooth contact analysis （LTCA） method is analyzed, in which the advanced surface to surface searching technique is included. The influence of misalignment errors and contact deformations on contact zone and transmission error （TE） is discussed. Combined modification approach on worm tooth surface is presented. By means of DDDM and LTCA, it is very conven- ient to verify the effect of worm-gear drive＇s modification approach. The analysis results show that, the modification in profile direction reduces the sensitivity of worm-gear drive to misalignment errors and the modification in longitudinal direction decreases the TE. Thus the optimization design of worm-gear drive can be achieved prior to the actual manufacturing process.

Electric Loading Simulation System for Missile Wings and Rudders

The design and the realization of missile wings and rudders loading simulation system based on digital signal processor (DSP) TMS320LF2407 and direct torque control (DTC) servo driver ACS600 are discussed. The structure and opration principle for the system are presented. Speediness and elimination of superabundant torque are two key difficulties for electric loading simulation system. The method which can eliminate the superabundant torque is researched. Test results show the airflow resistance when missile wings and rudders are spreading can be rapidly simulated with high accuracy.

Three-Dimensional Analysis of Buried Steel Pipes under Moving Loads

The three-dimensional response of buried steel pipes under vehicle loads is investigated using the finite element analysis. The analysis is conducted using the finite element program ABAQUS. The effects of the vehicle parameters, pipeline parameters and soil parameters on the response of the buried pipeline were discussed. The results indicate that the maximum principal stresses in a buried pipe under vehicle loads are significant for burial depths of less than 1 m. The maximum principal stresses of the buried pipeline decrease as the burial depth, vehicle velocity and surrounding soil’s elasticity modulus increase. For small burial depths, the stresses in buried pipes caused by vehicle motion in the direction normal to the pipe axis are more critical. However, the effects of motion direction are insignificant when the burial depth and the surrounding soil’s elasticity modulus increase. As the diameter of a buried pipe decreases, the maximum principal stresses increase.

出踩与面宽方向柱头科斗栱抗震性能对比试验及数值分析

为研究加载方向对斗栱抗震性能的影响,文章基于地震作用的随机性和斗栱出踩与面宽方向的构造差异,对2个足尺柱头科斗栱分别沿出踩和面宽方向进行拟静力试验,得到斗栱的破坏模式、承载力、刚度与强度退化、耗能和变形能力。结果表明:斗栱在出踩和面宽方向分别加载时,大斗均相对平板枋滑移,馒头榫挤压剪断。出踩方向受力时单昂与桃尖梁相对滑移,面宽方向受力时整体明显转动。相比面宽方向受力的斗栱,出踩方向受力的斗栱具有更高的承载力、初始刚度和耗能能力,而变形能力较差。文章开展柱头科斗栱的数值分析,模拟结果与试验结果吻合较好,研究出踩和面宽不同加载方向、轴压荷载、木构件之间摩擦系数和木材弹性模量对其抗震性能的影响。结果表明:面宽方向是柱头科斗栱的最不利受力方向,其正负向承载力比出踩方向分别低19.21%和17.03%;轴压荷载和木构件之间摩擦系数越大,斗栱承载力越大,而木材顺纹弹性模量和横纹径向弹性模量对斗栱的初始刚度和承载力影响较小。

Dynamic Performance of On-off Operation for a Small Scale Direct Fired Absorption Chiller

A part load operation by turning the burner on and off intermittently is effective for a small scale direct fired absorption chiller. The dynamic performance of the system has been investigated. The relationship between pressure, temperature and concentration of the lithium bromide solution have been analyzed. The result obtained indicates that the pressure of the high pressure generator and the temperature of the exhausted smoke are the most sensitive parameters. It is also found that the transition time from a full load to a part load condition is quite long, and part load relative cooling capacity is almost near the intermittent running time ratio and oil consumption ratio.

偏差电量考核机制下聚合温控负荷群控制策略

为降低售电公司在电力交易中的偏差考核电量和惩罚成本,以在用户负荷中占比较高的温控负荷为控制对象,建立配电网监测控制系统,收集电力市场和居民负荷数据,再根据这些数据设计基于聚合温控负荷群双层优化调度模型的直接负荷控制策略。仿真结果表明,该策略能降低配电网功率不平衡性,有效增加温控负荷的可调度容量,减少温控负荷的调度次数,降低售电公司的偏差考核电量,提高售电公司利润。

Weightlifting Motion Generation for a Stance Robot with Repeatedly Direct Kinematics

This research focuses on how to control the robot easily and how to generate the better trajectories of the robot with multiple joints to implement weightlifting motion. The purpose of this research is to develop a multijoint robot can stand up successfully with an object. This research requires the operations with two items. First, when the object is lifted up slowly, the robot could stand up as easily as possible and does not tumble down. Second, the load applied on each joint should be as small as possible. In this article, a motion control method is proposed to evaluate the variations of the load torque and rotated angle of each joint with the geometrical constraints in the procedure and find the best algorithm to generate the trajectory of a weightlifting motion by a stance robot with repeatedly direct kinematics.

含减载控制和虚拟惯量控制的直驱风电场等值建模方法

为建立准确的具有主动支撑能力的直驱风电场等值模型,提出一种含减载控制和虚拟惯量控制的直驱风电场等值建模方法。首先,建立包含减载控制和虚拟惯量控制的直驱风机并网系统模型;其次,依据适应性分析选取转速、减载系数、惯性系数和阻尼系数作为分群指标;然后,基于分群指标利用改进K-means算法对直驱风电场中的机组进行聚类分群,得到直驱风电场的等值模型;最后,利用实际算例在不同场景下进行仿真和计算,对等值建模方法的准确性进行验证。

基于高斯过程回归的主动配电网负荷控制优化方法

以需求响应为核心进行配电网负荷控制优化时,节能百分比较低。因此,提出基于高斯过程回归的主动配电网负荷控制优化方法。依托于随机森林算法,判断所有输入变量的重要性,明确主动配电网负荷影响变量。运用高斯过程回归原理,应用负荷预测算法,准确得出主动配电网需求侧未来一段时间内的负荷要求。在此基础上,以直接负荷控制为核心,建立负荷控制协调优化模型,再应用遗传算法求解最优负荷控制优化方案。算例分析结果表明:所提优化方法的节能百分比达到6.23%,说明该方法达到了节能的目的。

冷弯薄壁卷边C形不锈钢梁的力学性能试验

为了研究冷弯壁薄卷边C形钢受弯构件的力学性能,以冷弯薄壁不锈钢梁为研究对象,重点研究加载条件、跨度对构件屈曲模式和受弯承载力的影响。结果发现:试件的加载条件和跨度对冷弯薄壁卷边C形钢受弯构件屈曲模式和极限承载力的影响显著,纯弯加载下的短梁极限承载力高达169.1 kN,破坏模式为畸变屈曲,其余试件破坏模式也为畸变屈曲;腹板V型加劲能够有效抑制腹板鼓曲的产生,提高试件的极限承载力。利用现有直接强度法修正公式的计算结果与试验结果进行对比,以验证公式的准确性。

基于集群辨识和卷积神经网络-双向长短期记忆-时序模式注意力机制的区域级短期负荷预测

为了解决区域级短期电力负荷预测时输入特征过多和负荷时序性较强的问题,提出一种基于集群辨识和卷积神经网络(convolutional neural networks,CNN)-双向长短期记忆网络(bi-directional long short-term memory,BiLSTM)-时序模式注意力机制(temporal pattern attention,TPA)的预测方法。首先,将用电模式和天气作为影响因素,基于二阶聚类算法对区域内的负荷节点进行集群辨识,再从每个集群中挑选代表特征作为深度学习模型的输入,这样既能减少输入特征维度,降低计算复杂度,又能综合考虑预测区域的整体特征,提升预测精度。然后,针对区域电力负荷时序性的特点,用CNN-BiLSTM-TPA模型完成训练和预测,该模型能提取输入数据的双向信息生成隐状态矩阵,并对隐状态矩阵的重要特征加权,从多时间步上捕获双向时序信息用于预测。最后,在美国加利福尼亚州实例上分析验证了所提方法的有效性。