Independence Polynomials and the Merrifield-Simmons Index of Mono-Layer Cylindrical Grid Graphs

Research on the independence polynomial of graphs has been very active.However,the computational complexity of determining independence polynomials for general graphs remains NP-hard.Letα(G)be the independence number of G and i(G;k)be the number of independent sets of order k in G,then the independence polynomial is defined as I(G;x)=∑_(k=0)^(α(G))i(G;k)x^(k),i(G;0)=1.In this paper,by utilizing the transfer matrix,we obtain an analytical expression for I(CGn;x)of mono-cylindrical grid graphs CGn and present a crucial proof of it.Moreover,we also explore the Merrifield-Simmons index and other properties of CGn.

Enhancing Autonomy Capability in Regional Power Grids:A Strategic Planning Approach with Multiple Autonomous Evaluation Indexes

After the integration of large-scale DistributedGeneration(DG)into the distribution network,the randomness and volatility of its output result in a reduction of spatiotemporal alignment between power generation and demand in the distribution network,exacerbating the phenomenon of wind and solar power wastage.As a novel power system model,the fundamental concept of Regional Autonomous Power Grids(RAPGs)is to achieve localized management and energy autonomy,thereby facilitating the effective consumption of DGs.Therefore,this paper proposes a distributed resource planning strategy that enhances the autonomy capabilities of regional power grids by considering multiple evaluation indexes for autonomy.First,a regional Energy Storage(ES)configuration strategy is proposed.This strategy can select a suitable reference value for the upper limit of ES configuration based on the regional load andDGoutput to maximize the elimination of source load deviations in the region as the upper limit constraint of ES capacity.Then,a control strategy for regional ES is proposed,the charging and discharging reference line of ES is set,and multiple autonomy and economic indexes are used as objective functions to select different proportions of ES to control the distributed resources of the regional power grid and establish evaluation indexes of the internal regional generation and load power ratio,the proportion of power supply matching hours,new energy consumption rate and tie line power imbalance outside the region to evaluate changes in the regional autonomy capabilities.The final simulation results showthat in the real regional grid example,the planning method in the planning year in the region of the overall power supply matching hour ratio and new energy consumption rate increased by 3.9%and 4.8%on average,and the power imbalance of the tie line decreased by 7.8%on average.The proposed planning approach enables the maximization of regional autonomy while effectively smoothing the fluctuation of power exchange between the regional grid and the higher-level grid.This presents a rational and effective planning solution for the regional grid,facilitating the coordinated development between the region and the distribution network.

Index system and methods for comprehensive assessment of cross-border power grid interconnection projects

With the global economy integration and progress in energy transformation,it has become a general trend to surpass national boundaries to achieve wider and optimal energy resource allocations.Consequently,there is a critical n eed to adopt scie ntific approaches in assessi ng cross-border power grid interconnection projects.First,con sidering the promotion of large-scale renewable energy resources and improvements in system adequacy,a comprehensive assessment index system,including costs,socio-economic benefits,environmental benefits,and technical benefits,is established in this study.Second,a synthetic assessment framework is proposed for cross-border power grid interconnection projects based on the index system comprising cost-benefit analysis,with market and network simulations,iterative methods for indicator weight evaluation,and technique for order preferenee by similarity to an ideal solution(TOPSIS)method for the project rankings.Fin ally,by assessi ng and comparing three cross-border projects betwee n Europe and Asia,the proposed index system and assessment framework have been proved to be effective and feasible;the results of this system can thus support investment decision-making related to such projects in the future.

Research on Security Assessment Index System for Operating Reserve in Large Interconnected Power Grid

Optimization and placement of spinning reserve is an important issue in power system planning and operation. Systematic way for security assessment of operating reserve needs to study. A security assessment index system for operating reserve in large interconnected power grids is presented in this paper. Firstly, classification and determination methods of operating reserve at home and abroad are investigated, and operating reserve is divided into transient state operating reserve and quasi-steady state operating reserve from the view of security assessment. Secondly, assessment indexes and optimization methods for transient state operating reserve are studied. Thirdly, optimization model, deterministic and probabilistic optimization methods for quasi-steady state operating reserve are explored. Finally, some principles for determination of operating reserve are suggested, and a security assessment index system is put forward. The proposed index system, considering both transient and quasi-steady state, both deterministic and probabilistic methods, provides a systematic way to assessment and arrangement of operating reserve.

Grid System Analysis of Urban Flora of Bukhara City (Uzbekistan)

This article presents information on the study of the flora of Uzbekistan based on grid system mapping. The urban flora of the city of Bukhara was researched in it. As a result of research, the territory of Bukhara city was divided into 85 indexes based on 1 × 1 km2 grid mapping system. The diversity and density of species in the indexes are determined. The influence of anthropogenic factors on the diversity of species in the indexes is determined.

具有可用性改善的P-Grid覆盖网络

原P-Grid覆盖网络通过大量冗余将低在线率的节点构建成高可用性的系统.考虑分布式环境下节点不一定具有低在线率而呈现周期性,提出一种基于P-Grid的具有可用性改善的节点周期性组织方式.分类节点为长期节点、周期节点和普通节点,将长期节点按原P-Grid方式形成周期性组织下的主体二叉树,设计适当的信息表结构建立节点间的关系,并给出相应的查找、节点加入和数据对象创建的算法.数值分析和模拟实验表明在相同的节点规模及树高度下,周期性组织方式可以达到更高的可用性,同时数值分析也表明不影响维护消耗.

分布式能源接入下虚拟电厂负荷优化调度决策

针对分布式能源接入带来的电网特性变化和优化调度复杂性增加问题,以电动汽车(EV)为研究对象,探讨了其在虚拟电厂负荷优化调度中的潜在作用。基于构建的EV充电行为上、下界,建立了电动汽车聚合体(EVA)的功率容量预测模型,为虚拟电厂负荷优化调度提供了保障。考虑到EV具有不同的功率调节动态响应特性,提出了基于改进后自组织映射(SOM)算法的EV聚类方法,并使用Davies-Bouldin指数来评估聚类效果,以保证不同功率调节特性下EV聚类的准确性。进一步考虑风电接入和电动汽车并网可能带来的不利影响,以及功率平衡等多方面约束,构建了虚拟电厂的负荷优化调度决策模型。仿真结果表明,该虚拟电厂负荷优化调度决策模型保证了合理分配EVA容量情况下电网的安全运行。

VFP中Grid控件使用技巧三则

介绍了 Grid 控件的一些使用技巧，用它可设计出不同的编辑和游览数据的窗口。

暂态稳定视角下电网关键输电断面辨识方法

关键输电断面选定不合理,会导致电网负荷出现异常增大的情况,从而干扰电网的稳定运行。为此,提出了暂态稳定视角下电网关键输电断面辨识方法。根据暂态稳定条件,提取电网特征信息,并联合电量性能指标,求解暂态稳定模型,完成暂态稳定视角下的电网断面电量性能评估。在此基础上,定义关键输电断面,通过计算风险评估指标,确定辨识权重指标的取值范围,完成暂态稳定视角下电网关键输电断面辨识方法的设计。实验结果表明,应用上述辨识方法,可以保证已选定关键输电断面内的电网负荷不超过5.2×10^(11)kW,有效解决关键输电断面选定不合理造成的电网负荷异常增大问题,能够提高电网运行的稳定性。

An Online Fault Detection Model and Strategies Based on SVM-Grid in Clouds

Online fault detection is one of the key technologies to improve the performance of cloud systems. The current data of cloud systems is to be monitored, collected and used to reflect their state. Its use can potentially help cloud managers take some timely measures before fault occurrence in clouds. Because of the complex structure and dynamic change characteristics of the clouds, existing fault detection methods suffer from the problems of low efficiency and low accuracy. In order to solve them, this work proposes an online detection model based on asystematic parameter-search method called SVM-Grid, whose construction is based on a support vector machine(SVM). SVM-Grid is used to optimize parameters in SVM. Proper attributes of a cloud system's running data are selected by using Pearson correlation and principal component analysis for the model. Strategies of predicting cloud faults and updating fault sample databases are proposed to optimize the model and improve its performance.In comparison with some representative existing methods, the proposed model can achieve more efficient and accurate fault detection for cloud systems.

Differentiation degree combination weighting method for investment decision-making risk assessment in power grid construction projects

Power grid construction projects are distinguished by their wide variety,high investment,long payback period,and close relation to national development and human welfare.To improve the investment accuracy in such projects and effectively prevent investment risks,this paper proposes an investment optimization decision-making method for multiple power grid construction projects under a certain investment scale.Firstly,an in-depth analysis of the characteristics and development requirements of China’s power grid projects was performed.Thereafter,the time sequence and holographic method was adopted to conduct multi-dimensional,multi-perspective risk assessment of different parts of power grid projects,and a holographic risk assessment index system was developed.Moreover,an investment decision model considering the comprehensive risk based on combination weighting was developed according to the output and input of power grid construction projects.A new combination weighting optimization method that takes into account the investment willingness of enterprises was designed to improve the current weighting evaluation methods.Finally,the validity and applicability of the proposed evaluation method were verified by case examples.

Application of SVR Models in Stock Index Forecast Based on Different Parameter Search Methods

Stock index forecast is regarded as a challenging task of financial time-series prediction. In this paper, the non-linear support vector regression (SVR) method was optimized for the application in stock index prediction. The parameters (C, σ) of SVR models were selected by three different methods of grid search (GRID), particle swarm optimization (PSO) and genetic algorithm (GA).The optimized parameters were used to predict the opening price of the test samples. The predictive results shown that the SVR model with GRID (GRID-SVR), the SVR model with PSO (PSO-SVR) and the SVR model with GA (GA-SVR) were capable to fully demonstrate the time-dependent trend of stock index and had the significant prediction accuracy. The minimum root mean square error (RMSE) of the GA-SVR model was 15.630, the minimum mean absolute percentage error (MAPE) equaled to 0.39% and the correspondent optimal parameters (C, σ) were identified as (45.422, 0.012). The appreciated modeling results provided theoretical and technical reference for investors to make a better trading strategy.

Cyber Attack Protection and Control of Microgrids

Recently, the smart grid has been considered as a next-generation power system to modernize the traditional grid to improve its security, connectivity, efficiency and sustainability.Unfortunately, the smart grid is susceptible to malicious cyber attacks, which can create serious technical, economical, social and control problems in power network operations. In contrast to the traditional cyber attack minimization techniques, this paper proposes a recursive systematic convolutional(RSC) code and Kalman filter(KF) based method in the context of smart grids.Specifically, the proposed RSC code is used to add redundancy in the microgrid states, and the log maximum a-posterior is used to recover the state information, which is affected by random noises and cyber attacks. Once the estimated states are obtained by KF algorithm, a semidefinite programming based optimal feedback controller is proposed to regulate the system states, so that the power system can operate properly. Test results show that the proposed approach can accurately mitigate the cyber attacks and properly estimate and control the system states.

Multi-level fuzzy comprehensive appraisal on social effects of projects

The application of multi-level fuzzy comprehensive appraisal on social effects of projects has been studied. The principles for setting up an index system have been analyzed and the index system has been set up according to projects of construction. Models for multi-level fuzzy comprehensive appraisal have been offered and relative calculation steps have been given according to project instances.

Multi-stage power source and grid coordination planning method considering grid uniformity

Given the increasing uncertainties in power supply and load,this paper proposes the concept of power source and grid coordination uniformity planning.In this approach,the standard deviation of the transmission line load rate is considered as the uniformity evaluation index for power source and grid planning.A multi-stage and multi-objective optimization model of the power source and grid expansion planning is established to minimize the comprehensive cost of the entire planning cycle.In this study,the improved particle swarm optimization algorithm and genetic algorithm are combined to solve the model,thus improving the efficiency and accuracy of the solution.The analysis of a simple IEEE Garver’s 6-node system shows that the model and solution method are effective and feasible.Moreover,they are suitable for the coordinated planning of the power source and grid under a diversified nature of power supply and load.

Index-Peer:半结构化网格资源发现模型

针对网格环境下的集中式和无结构P2P资源发现机制的不足,提出一个基于半结构化P2P索引技术的资源发现模型。该模型采用三层索引结构,模型充分利用网格环境中的节点性能差异,具有高效的查找功能,且对网络的高度动态性有良好的适应性。

Effects of mesh style and grid convergence on numerical simulation accuracy of centrifugal pump

In order to evaluate the effects of mesh generation techniques and grid convergence on pump performance in centrifugal pump model, three widely used mesh styles including structured hexahedral, unstructured tetrahedral and hybrid prismatic/tetrahedral meshes were generated for a centrifugal pump model. And quantitative grid convergence was assessed based on a grid convergence index(GCI), which accounts for the degree of grid refinement. The structured, unstructured or hybrid meshes are found to have certain difference for velocity distributions in impeller with the change of grid cell number. And the simulation results have errors to different degrees compared with experimental data. The GCI-value for structured meshes calculated is lower than that for the unstructured and hybrid meshes. Meanwhile, the structured meshes are observed to get more vortexes in impeller passage.Nevertheless, the hybrid meshes are found to have larger low-velocity area at outlet and more secondary vortexes at a specified location than structured meshes and unstructured meshes.

Square Grid结构无线传感网数据传输的源路由策略分析

无线传感网中的汇聚传输模式使得靠近汇聚点的节点承担了较多的数据转发业务,导致这些节点能量很快耗尽,造成网络节点负载分布不均衡。针对这种汇聚传输问题,结合规则拓扑结构的对称性和预知性,提出基于Square Grid规则拓扑结构中分析典型源路由策略,设计一种计算路由节点负载分布的转发指数,并依据该转发指数分析各路由策略负载性能的方法。通过Mathematica绘制各路由节点负载分布图并对比各路由策略的转发指数,实验结果验证了Balancing Forwarding路由策略的节点具有较均衡的负载分布。该方法能有效地应用于评价路由策略的优劣。

A novel decomposition and coordination algorithm for complex networks and its application to power grids

To analyze and control complex networks effectively, this paper puts forward a new kind of scheme, which takes control separately in each area and can achieve the network’s coordinated optimality. The proposed algorithm is made up of two parts: the first part decomposes the network into several independent areas based on community structure and decouples the information flow and control power among areas; the second part selects the center nodes from each area with the help of the control centrality index. As long as the status of center nodes is kept on a satisfactory level in each area, the whole system is under effective control. Finally, the algorithm is applied to power grids, and the simulations prove its effectiveness.

Distributed Air-Conditioning Energy Management System within the Smart Grid Context

-Air-conditioning （AC） systems are the major energy consumption units in residential and commercial buildings. In the context of smart grid, optimizing AC operations leads to substantial saving in energy consumption, reducing the consumer＇s bill and contributing to the environment by minimizing carbon emissions from generating stations. This paper presents a distributed AC energy management system for buildings by using networked master-slaves controller architecture. The proposed system was designed, simulated, and experimentally tested by using real AC units in a students＇ residence hall. Based on the students＇ class schedules, several operational scenarios were implemented and tested. The proposed system implementation leads to a 40% to 60% saving of the consumed energy by the tested units. The same energy management scheme can be applied and implemented in other commercial and residential buildings.