Modeling Simulation Technology Research for Distribution Network Planning

This paper proposes to use the power system simulation software CYME to plan, model and simulate for an actual distribution network for improving the reliability and efficiency, enhancing the efficiency and capacity, simulating the abnormal condition of distribution network, and presenting operation program of safe, reliable and having simulation record statements. The modeling simulation results show that the software module has lots of advantages including high accuracy, ideal reliability, powerful practicality in simulation and analysis of distribution network, it only need to create once model, the model can sufficiently satisfy multifarious types of simulation analysis required for the distribution network planning.

A Novel Simulation Framework for Predicting the Formation Parameters Variation in Unconsolidated Sandstone Reservoir

After long-term waterflooding in unconsolidated sandstone reservoir, the high-permeability channels are easy to evolve, which leads to a significant reduction in water flooding efficiency and a poor oilfield development effect. The current researches on the formation parameters variation are mainly based on the experiment analysis or field statistics, while lacking quantitative research of combining microcosmic and macroscopic mechanism. A network model was built after taking the detachment and entrapment mechanisms of particles in unconsolidated sandstone reservoir into consideration. Then a coupled mathematical model for the formation parameters variation was established based on the network modeling and the model of fluids flowing in porous media. The model was solved by a finite-difference method and the Gauss-Seidel iterative technique. A novel field-scale reservoir numerical simulator was written in Fortran 90 and it can be used to predict 1) the evolvement of high-permeability channels caused by particles release and migration in the long-term water flooding process, and 2) well production performances and remaining oil distribution. In addition, a series of oil field examples with inverted nine-spot pattern was made on the new numerical simulator. The results show that the high-permeability channels are more likely to develop along the main streamlines between the injection and production wells, and the formation parameters variation has an obvious influence on the remaining oil distribution.

Joint optimization scheduling for water conservancy projects incomplex river networks

In this study, we simulated water flow in a water conservancy project consisting of various hydraulic structures, such as sluices, pumping stations, hydropower stations, ship locks, and culverts, and developed a multi-period and multi-variable joint optimization scheduling model for flood control, drainage, and irrigation. In this model, the number of sluice holes, pump units, and hydropower station units to be opened were used as decision variables, and different optimization objectives and constraints were considered. This model was solved with improved genetic algorithms and verified using the Huaian Water Conservancy Project as an example. The results show that the use of the joint optimization scheduling led to a 10% increase in the power generation capacity and a 15% reduction in the total energy consumption. The change in the water level was reduced by 0.25 m upstream of the Yundong Sluice, and by 50% downstream of pumping stations No. 1, No. 2, and No. 4. It is clear that the joint optimization scheduling proposed in this study can effectively improve power generation capacity of the project, minimize operating costs and energy consumption, and enable more stable operation of various hydraulic structures. The results may provide references for the management of water conservancy projects in complex river networks.

Modeling methodology and fault simulation of distribution networks integrated with inverter-based DG

The increasing penetration of inverter-based distributed generations(DGs)significantly affects the fault characteristics of distribution networks.Fault analysis is a keystone for suitable protection scheme design.This paper presents the modelling methodology for distribution networks with inverter-based DGs and performs fault simulation based on the model.Firstly,a single inverter-based DG model based on the cascaded control structure is developed.Secondly,a simulation model of distribution network with two inverter-based DGs is established.Then,different fault simulations are performed based on the Real Time Digital Simulator(RTDS).Theoretical analyses are conducted to justify the simulation results,including the equivalent circuit of distribution networks with inverter-based DGs and the solution method for loop currents.

A universal elliptical disc(UED)model to represent natural rock fractures

Since natural fractures are often non-equidimensional,the circular disc model still has great limitations.By contrast,the elliptical disc model is more applicable to representing natural fractures,especially for slender ones.This paper developed a universal elliptical disc(UED)model by incorporating the center point,size,and azimuth of fractures as variables.Specifically,with respect to the azimuth of elliptical fractures in three-dimensional(3D)space,we proposed a paradigm to construct its probability density function(PDF)by coupling the orientation and rotation angle of long axis based on three coordinate transformations.To illustrate the construction process of the PDF of the fracture azimuth,we took the orientation following the Fisher distribution and the rotation angle following Von Mises distribution as an example.A rock slope is used to show the use of the developed UED model,and the 3D DFNs for the slope rock mass are generated by Monte Carlo simulation.In addition,the DFNs for the rock mass are also generated based on the existing circular disc model and non-universal elliptical disc model.The comparison results from the three models clearly illustrate the superiority of the UED model over the existing circular and non-universal elliptical disc models.

基于组织-任务网络的项目进度风险分析

针对工程项目外部进度风险的传播与控制,构建项目组织-任务网络模型,依据级联失效理论,从风险荷载、节点容量、荷载重分配与失效判别规则四方面确定项目进度风险的传播机制.仿真结果表明,组织和任务间的相互关系会扩大外部风险对项目进度的影响,且随机组织失效造成的影响大于关键组织.通过增加风险投入、加强预警、提高容错率可在一定范围内增强项目风险抵抗能力,同时需要加强非关键组织的风险预警与管控,有效控制外部风险对项目进度造成的影响.

高比能二次锂电池电极材料的储能系统配电网运行建模与仿真研究

对于包含储能系统的配电网运行建模与仿真,传统方法由于缺少对储能系统变量增补约束,导致建模后储能系统的电热转换效率较低。为此,提出高比能二次锂电池电极材料的储能系统配电网运行建模与仿真研究。依据储能系统在配电网中的运行特性,建立储能系统等效电路,并以高比能二次锂电池电极材料的储能系统的经济性指标构建电网运行模型,同时对其加以变量增补约束,以动态描述配电网的运行过程。实例应用结果显示,所提方法能够有效提高储能系统的电热转换效率,建模结果更加可靠。

Kinetic model of vibration screening for granular materials based on biological neural network

The kinetic model is the theoretical basis for optimizing the structure and operation performance of vibration screening devices.In this paper,a biological neurodynamic equation and neural connections were established according to the motion and interaction properties of the material under vibration excitation.The material feeding to the screen and the material passing through apertures were considered as excitatory and inhibitory inputs,respectively,and the generated stable neural activity landscape was used to describe the material distribution on the 2D screen surface.The dynamic process of material vibration screening was simulated using discrete element method(DEM).By comparing the similarity between the material distribution established using biological neural network(BNN)and that obtained using DEM simulation,the optimum coefficients of BNN model under a certain screening parameter were determined,that is,one relationship between the BNN model coefficients and the screening operation parameters was established.Different screening parameters were randomly selected,and the corresponding relationships were established as a database.Then,with straw/grain ratio,aperture diameter,inclination angle,vibration strength in normal and tangential directions as inputs,five independent adaptive neuro-fuzzy inference systems(ANFIS)were established to predict the optimum BNN model coefficients,respectively.The training results indicated that ANFIS models had good stability and accuracy.The flexibility and adaptability of the proposed BNN method was demonstrated by modeling material distribution under complex feeding conditions such as multiple regions and non-uniform rate.

基于特征矩阵分区等值和自适应插值切换的有源配电网多速率并行仿真方法

现代有源配电网呈现复杂多变、多时间尺度的特征,采用单一仿真速率难以同时兼顾计算效率与精度,对此该文提出基于特征矩阵分区等值和自适应插值切换的有源配电网多速率并行仿真方法。首先,构建系统状态空间矩阵,并基于状态矩阵特征值的量级将系统拆分为多个动态特性差异的子系统,通过将系统的状态矩阵进行分块等效,实现子区域在小步长时刻的独立仿真解算与在大步长时刻的等效补偿,在保证仿真精度的基础上大幅降低了系统仿真规模;然后,针对各区域间数据交互不同步问题,通过倍率步长相量法分析线性插值误差产生原理及主要影响因素,并提出基于二阶泰勒展开式的多步自适应插值仿真算法,可以根据系统频率与仿真步长需求调节相关插值参数,显著降低插值误差;最后,采用改进型IEEE 123节点配电网算例,通过分区等值/插值计算与仿真结果的对比,验证了所提多速率并行仿真方法的可行性与有效性。

EMTP-type Program Realization of Krylov Subspace Based Model Reduction Methods for Large-Scale Active Distribution Network

Effective model reduction methods are required to deal with new challenges in active distribution network simulations that are on a large scale and have complicated structures.In the development of advanced electromagnetic transient simulation programs,automated model reduction plays an important role.This paper proposes an automated realization algorithm for the Krylov subspace based model reduction methods of an active distribution network with which the reduced model can be automatically established according to a given threshold of reduction error.The combined state-space nodal analysis framework is employed to apply the automated model reduction algorithm in popular EMTP-type simulation programs.Simulations are performed using PSCAD and a self-developed program to show the feasibility and validity of the proposed methods.

拓扑关系重建下的配网调度防误模拟操作优选排序算法

结构复杂的配网调度中,拓扑关系冗杂,内部线路繁复,排序过程容易陷入局部最优,无法得到全局最优调度方案。对此,设计一种在拓扑关系重建下的配网调度防误模拟操作优选排序算法。为了获取配网拓扑接线图信息,生成拓扑关系重建下的配网接线图,同步分析待重建数据与配网模型。利用Petri网描述配网中调度操作活动,利用动态关联矩阵分析调度防误模拟操作方案。分层计算各方案不同环节下的风险和总体方案的风险,选择风险最小的调度方案完成配网调度防误模拟操作优选排序。测试结果表明,该方法更加接近理论上的优选方案,相对安全,保证了配网调度防误模拟操作过程的完整性和实际应用性。

主动配电网源网荷储一体化协调优化模型研究

常规主动配电网源网荷储一体化协调优化模型采用局部协调的方法,导致协调优化结果能源利用效率不高,因此提出主动配电网源网荷储一体化协调优化模型研究。结合支路电流值分析模型约束条件,构建协调优化模型,分析主动配电网源网荷储的出力情况。实验表明:该模型应用后表现出的功率曲线与配电需求高度一致,能源利用效率较高,满足主动配电网的实际运行需求。

传输距离对芯片供电影响的研究

芯片工作所需的能量供应,是通过传输路径送达其内部的。在传输过程中,存在电压压降、效率损耗与电压动态响应等情况,其在高功率大电流的芯片供电应用中尤为明显。针对此情况,研究了传输距离对芯片供电的影响,并对研究结果进行了分析。报告了芯片供电的传输距离对功耗、电压、电源设计所带来的影响和困难等现状;提出了通过缩短电源传输距离来实现优化芯片供电质量及提高电源有效使用率的设计方案的调查与仿真,通过对调查和仿真结果进行比照分析,验证了所提策略的有效性与可行性。

分布式光伏发电对配电网电压的影响分析

阐述分布式光伏发电的特点,分析其对配电网电压的影响,包括不同时段的电压影响、节点配网架构设定。从设置储能发电系统、阻止越限电压、解析仿真模型方面,探讨电压越限解决措施。

基于行波时差法的配电网故障诊断方法

针对配电网结构复杂故障难以精确诊断的问题,提出了一种基于故障行波时差的配电网故障诊断方法,实现对配电网故障点的精确定位及故障类型的判断。根据线路行波传输特性及故障点距离计算理论,构建配电网线路状态方程,将计算的理论值代入状态方程,输出故障搜索矩阵,利用矩阵变化的特征来诊断线路的故障情况。最后,利用行波到达多端时刻差解决线路中波速变化造成的故障定位不准确问题。该方法经配电网仿真模型验证具有有效性,可以准确诊断出不同阻值接地故障。

基于光纤光栅的配网故障定位仿真模型研究

针对配电网环境复杂,监测的数据容易受到干扰或丢失,从而影响最终的故障定位准确性的问题,文中提出了一种基于光纤光栅技术的配电网故障仿真模型。该模型利用光纤光栅电流传感器来收集电流数据,发挥抗干扰性强、数据不易丢失等优点,通过电流波动来判断故障位置。利用该方法,从源头上提高监测的数据质量,依靠安装在配电网线路上的光纤电流传感器采集电缆中电流,当输电线路上某点发生故障时,计算出故障点相邻的前后两个光纤电流传感器检测到电流波动差值,通过阈值比较来实现故障位置的快速定位。该模型成功应用于某两个供电局,故障判断的准确率达到了98.89%,还考虑了无法确认故障是否真实发生的情况,具备良好的实用性及准确性。

面向新型配电网的地配一体化调度仿真技术研究

新一代配电网呈现配网有源化、主配协同化、源网荷协同等新业态和新模式,主配网专业队伍能力建设需进一步协同加强。原有的仿真培训系统多针对无源配电网格局,无法满足地配调度中心运行人员培训新需求。文章研究并提出了适应有源配电网的地配一体化仿真培训系统若干关键技术并进行了研发应用,围绕地配调中心调度运行人员实际培训业务需求,给出了满足新一代配电网调度培训所需的系统设计思路和关键培训功能,可提升相关专业人员的配网调度运行技能和离线操作能力,提高配网专业人员对新型配电网的调度驾驭能力,具有较好的行业科技推广价值。

考虑配电网络的综合负荷模型

介绍了电力系统稳定计算分析程序中常用的负荷模型,分析了上述负荷模型的结构及其在电力系统计算分析程序中的实现过程,指出了上述负荷模型的不足。根据变电站负荷的实际构成,提出了物理意义明确的综合负荷模型。该模型物理结构合理,可操作性强,可方便地模拟负荷元件和包括配电网络、无功补偿系统和接入低压电网的发电机的供电系统。2004年和2005年东北电网的4次三相短路试验验证了该综合负荷模型的有效性。

直流配电网拓扑结构及控制策略

对直流配电网的环状拓扑结构和两端拓扑结构的可行性进行了探讨,对直流配电网链式结构典型支路的功率方程等进行了推导与求解。对分布式能源和储能装置并入交流配电网和直流电网进行了对比研究,研究结果表明相较于接入交流配电网而言,接入直流配电网能够有效节省DC/AC变换器和滤波装置。采用了混合式直流断路器同时提出了一种直流配电网的协调控制模型。利用PSCAD/EMTDC对环状直流配电网结构的正常工况和故障情况进行仿真,仿真结果表明通过有效的控制和分布式能源的合理调度,能够有效限制短路故障对系统造成危害,缩短短路时间,使整个直流配电网更加有效稳定地运行。

基于信息传播的社交网络拓扑模型

研究社交网络的拓扑结构有利于深刻理解信息在人际网络中的传播过程以及社交网络所具有的拓扑特性。考虑到信息传递具有有向性,通过结合现实生活中信息传播所遵循的规律构造加权有向拓扑模型模拟信息传递的动态性,从而更好地仿真社交网络的拓扑结构。实验结果表明,模型所生成网络的拓扑结构的度、势分布以及度—势相关性具有明显的幂律分布特性;同时,通过分析所生成网络的聚类系数、核数和基尼系数,验证了其具有社交网络的聚集特性、层次性和异质性。