Grid Segment Research Articles

Modification of the reputation and trust model in the tasks of information security of grid systems for resistance to the threat of "malicious host groups"

In Grid-systems, the key idea is the joint use of resources, therefore there is a need for mutual trust between users and resource providers. In small grid systems, all participants are in a relationship of complete trust. For example, in the Ukrainian Academic Grid segment, all participants belong to the National Academy of Sciences of Ukraine, and on this basis there is complete trust. But in larger Grid-systems, participants may often not be directly connected to each other, and there is a risk that one of the participants will turn out to be unscrupulous and malicious. Trust mechanisms are designed to reduce these risks. The main purpose of security mechanisms is to provide protection against malicious users and groups of persons. Traditional security methods usually protect resources from malicious influences by restricting access to authorized users. However, in most cases there is a need to protect the system and its components from those who provide resources and services within heterogeneous computing systems. Thus, there are a large number of problems in the field of security that cannot be solved within the framework of traditional approaches. Information providers can, for example, commit fraud by providing false and unreliable information, and traditional security mechanisms are unable to protect against this type of threat. On the other hand, systems of reputation and trust can provide protection against these risks. The distinction between these two approaches to information security was first described by Rasmussen and Jansson (1996), who used the term hard security to refer to traditional mechanisms such as authentication and access control, and the term soft security to refer to what they called public control mechanisms. in general, exemplified by reputation and trust systems.

Optimization of SPIDER Grounded Grid Segment Design

Source for the production of ions of deuterium extracted from a radio frequency plasma (SPIDER) is a full-size negative ion source and a multibeamlet 100-kV accelerator, operational since 2018. It serves as the test bed for the full development of the heating neutral beam system for megavolt ITER injector and concept advancement (ITER). In 2020, the third grounded grid segment broke at the electrodeposited copper layer near one of the four feeders causing leakage. This article reports the redesign development of the SPIDER GG segment. In the first part of the article, several design configurations are proposed and compared to each other. The comparison serves to identify a suitable redesign configuration. A set of coupled analyses, including computational fluid dynamic (CFD) and finite-element method (FEM) analyses, is then performed to finally evaluate the redesigned component in accordance with the ITER structural design criteria for in-vessel components (ITER SDC-IC) criteria.

Electromagnetic coupling modeling and accuracy verification of non-parallel cable structure

<sec>Owing to the random bundling of the cable bundle, the different conductors within the cable present non-parallel distribution structural features. Such a structural feature leads to different cross-sectional structures at different positions along the line. The variations of spacing between different conductors and the height from the ground can lead the distribution parameters to change. This requires that when solving the electromagnetic coupling of the cable bundle, the cable bundle should be divided into multiple grid segments along the line, and the distribution parameters should be calculated according to the cross-sectional geometry information at different grid segment positions.</sec><sec>On the basis of the integration of the transmission line model and the distributed parameter model, the distribution parameters of different mesh segments are calculated according to the cross-sectional structure of different mesh segments of the cable in this paper. When the parameters are brought into the transmission line model, an electromagnetic coupling model suitable for non-parallel cable structures is established. In order to verify the accuracy of the model, a unit cable structure from real cable with non-parallel distribution characteristics is designed. The calculation results from the proposed model are compared with the calculation results from the full-wave algorithm and the experimental results, showing they are in good agreement with each other.</sec><sec>In order to understand the influence of the cable non-parallel structure characteristics on the response of electromagnetic coupling to cable, the comparison of electromagnetic coupling response results between the parallel cable and non-parallel cable structures are made and analyzed, showing that the non-parallel structure characteristics of the cable have a significant effect on the electromagnetic coupling. It is confirmed that the influence of the non-parallel cable structure characteristics must be considered in the electromagnetic coupling simulation of the real cable.</sec>

The Proposal of a New Tool for Condition Assessment of Medium Voltage Power Cable Lines

A medium voltage (MV) cable network is a substantial component of the distribution network. Present management of this grid segment is mainly based on the failure rate analysis, i.e., a rise in the number and kind of faults on the actual line means that its technical condition is getting worse. The efficiency of the power system is low and additional costs of repair works, supply interruption, difficulties in the investment planning and operation and maintenance works are necessary. The aim of the R&D works done in the realised project is to implement the management of the MV cable network based on the estimated condition of the individual cable line, obtained from diagnostic measurements. The diagnostic investigations of the cable lines are the reference. Many years of research work have led to the development of the Health Index based on diagnostic, technical and service data.

Effective energy storage power control to extend the acceptable range of generator frequency in distributed generation

Gas-turbine and gas-piston generator sets (GS) are widely used at distributed generation (DG) facilities. International GS manufacturers configure relay protections (RP) in a way that narrows the acceptable range (AR) and causes properly functioning RPs to effect unnecessary disconnections. It has been shown that the worst disturbances are observed when a microgrid that carries a DG facility is islanded, and power imbalance occurs; when motors start in groups; when the GS’s shed 95% of their output; and when a 3-phase short-circuit occurs in an islanded grid segment. Energy storage units (ESU) are the most recent and highly successful solution to many problems of power engineering. The authors hereof have developed a method that controls active and reactive power of an ESU independently to avoid unnecessary GS disconnections that would otherwise be caused by a short-term deviation in frequency; this will help reliably deliver electricity to the users of an islanded microgrid. Simulation results show that the use of ESUs helps to effectively extend the acceptable range for generator sets. There are recommendations on drawing technical requirements to ES. An important advantage of the proposed ESU power control method is that it does not need to adjust ES-received control actions (CA) online for frequency deviation.

Forecasting of daily power consumption dynamics

The purpose of the study is to simulate the time series of power consumption in a power grid segment. It gives us be able to forecast the future state from values of the series according to current and past estimates. We want to test two different approaches: Box-Jenkins method and recurrent neural networks, for detect which of them give more accuracy and speed of prediction calculation. This article discusses the using Box-Jenkins method.

Barriers to entrepreneurship in public enterprises: boards contributing to inertia

ABSTRACT This article adopts a qualitative comparative causal mapping approach to extend knowledge of the interrelated barriers to public entrepreneurship and the outcomes of such entrepreneurship. The results highlight marked differences between the sales segment and the distribution grid segment of German public enterprises that should prompt a refined perspective on public entrepreneurship. Notably, besides intra-organizational barriers and those interfering from the external environment, results also show that a public enterprise’s supervisory board can hinder its progress. This study thus contributes to recent discussion on governance and entrepreneurship by revealing a feature that could distinguish public from private enterprises.

A Method for Noninvasive Remote Monitoring of Energy Meter Error Using Power Consumption Profile

In this article, a noninvasive remote monitoring method of error of electricity energy meter (EM) is introduced and its achievable precision is investigated. The aim of the method is to determine remotely the smart EM active power relative measurement error using the reference EM connected at the input of a low-voltage distribution grid segment. The meter error estimation is carried out despite other customers’ electrical load changes observable by the reference meter and power fluctuations in the distribution network. The method is based on the real-time analysis of natural customer power consumption profiles without any additional load injection for error-monitoring needs. A power step in the customer power consumption profile is detected by the meter under test and then the step magnitude is delivered for the comparison with the power step magnitude estimated synchronously by the reference meter. The analysis of the method error is conducted by applying simulation of the benchmark distribution grid which includes 26 EMs and utilizing the open data power consumption profiles. It is shown that after two to three days of averaging (including approximately 170 power steps) of the meter error estimates, it becomes possible to achieve an uncertainty of meter error estimation approximately 0.63%. The feasibility of the method implementation scenarios with the state-of-the-art EM data collection protocols in advanced measurement infrastructure (AMI) by means of occupancy index modeling is performed.

Design and analysis of TWIN source extraction system grids with indigenous manufacturing feasibility assessment

Abstract A 3 grid extractor and accelerator system is to be coupled to the two driver RF negative ion source test bed to extract and accelerate H- ion beams up to 50 keV. One of the aims of the TWIN test bed is to characterize and benchmark the optics design of such an accelerator system (1:4 scale) which has been modelled for the 8 driver diagnostic neutral beam negative ion source. A cooling scheme based on analysis and indigenous manufacturing assessment has been selected. In order to enable indigenous manufacturing of embedded cooling channel of such an accelerator a route of vacuum brazing has been considered to close the water cooling channels of the 3 grid segments as against the conventional route of 1 mm thick electrodeposited layer of copper. It will be an attempt to replace copper electro-deposition which has limited availability across the globe. The optimal geometrical requirements for establishing brazing to close the water cooling channels has been successfully realized and validated experimentally by subjecting the developed prototype braze coupon under high heat flux facility at IPR. The selected cooling scheme choice has then been utilized on a strip model (Grid segment) to perform thermo-mechanical analysis under operating load conditions to study thermal profile, stresses, out of plane deformations and aperture displacements (misalignment).

Segmentation of Human Eye Pupil with Novel Grid Based Localization Computing

This paper discuss about grid computing which increase the performance of vision image segmentation. The segmentation process with grid computing identifies the challenging in computation task. Novel grid based method supports image processing technique to circle eye pupil in normal and defective eyes. The procedure of the proposed system use real eye images as data collection for input to grid computing. Image corner and line edge detection is replaced with grid based technique to achieve good segmentation result. Grid with different sizes classified to reach neighbors to form grid segment. Adjacency graph merge the regions of highlighted eye pupil. This grid location points of eye image is noted to identify the eye center localization. The experimental task proves the efficiency of automate segmentation compared with other algorithms.

Повышение надежности сетей 6–35 кВ путем применения метода STA/LTA

Quick and accurate detection of single phase to earth faults (SPEF) in electric grids is a relevant problem. However, the existing methods and tools are not always capable of ensuring sufficient quality of such detection, which is why developing SPEF detection tools and methods is an ongoing effort. This paper proposes an STA/LTA-based SPEF detection method; the STA/LTA method is widely used for detecting seismic activity. The paper describes this method and presents an algorithm of using it to detect SPEF in distribution grids. An SPEF-detection VBA application has been developed based on this algorithm. To test the method, a cable-grid computer model was made in PSCAD, matching a real-world urban grid segment. The model-generated SPEF voltage and current oscillograms were processed by the developed application. Simulation and computation results analysis can identify STA/LTA trigger thresholds for reliable SPEF detection. Trigger boundaries are defined in relative units, making the method adaptive to changes in grid topology. Therefore, testing the STA/LTA method by means of a PSCAD model proves its efficiency and great potential for SPEF detection.

Techno-economic evaluation of load activation quotas as a concept for flexible load management

Flexible load management concepts are increasingly relevant due to a rising share of flexibilities at distribution grid level, e.g. power-to-heat systems, electric vehicles or home battery storages. In a market oriented load management, uniform price signals can lead to higher load simultaneity factors and grid congestions. Therefore, load management concepts have to consider the prevention of grid congestions, e.g. by load activation quotas. The quota represents the maximum share of flexible loads per grid segment for each point in time that can be activated without causing grid congestions. Grid expansion measures increase the possible activation quota and lead to higher flexibility in operation. For an aggregator of flexible loads, grid expansion increases the potential for procurement cost reduction. On the other side, it causes capital costs for the distribution system operator. This study introduces a methodology for the techno-economic evaluation of LAQ as a concept for flexible load management in future distribution grids, which is applied to an exemplary medium-voltage grid in Southern Germany. The analysis considers both the investment costs for grid expansion by the grid operator and operational savings in procurement due to an increased flexibility for an aggregator. The cost-efficient trade-off from a micro-economic perspective is determined.

Manufacturing technology development for an ‘angled’ accelerator grid segment for DNB Beam Source

The accelerator for the Diagnostics Neutral Beam (DNB) beam source is composed of a multi-aperture grid system with three water cooled grids made from Oxygen free Copper. To achieve the focusing requirements at the distance of >20m, the grid segments are designed with two stage angles (0.222° and 0.665°) from the centerline in the horizontal direction. The configuration of this kind of ‘angled segment’ includes the water cooling channels milled in the angular form, subsequently closed by copper electrodeposition, providing the angles on front and back surface and then drilling of apertures on the angular plane. The long beam path and low energy beam demands the tight tolerances on each of these mechanical features and therefore demands the high degree of manufacturing controls on each of the processes.To unveil the challenges those could appear during the production of such grid, a 1:1 prototype of the most complex type of grid has been manufactured. This paper shall present the technical data generated out of manufacturing of this prototype, summarizing the recommendations for real grid production on: optimization of the sequence of manufacturing, effect of each of the operations, post-manufacturing handling and identifying the measurement techniques. The experience gathered here provides a recipe for the best manufacturing practices for the accelerators of NB system for ITER and upcoming devices.

Resistor-Based Shape Sensor for a Spatial Flexible Manifold

In robotics, knowing a mechanism’s configuration is essential. Commonly, potentiometers or encoders are used in order to obtain the mechanism’s configuration. Nevertheless, such sensors are useless for applications where a surface’s spatial-shape is to be attained. For that end, we introduce a novel sensor mesh. We use an electrical-resistors grid as the shape sensor. The resistance in each grid segment changes with accordance to its length. So, by attaching the sensor mesh to an elastic grid, bending results with resistance change in the associated segments. For practical reasons, only the peripheral nodes are wired. We introduce an algorithm to extract the resistance of each of the segments. We then formulate the forward kinematics of elastic grid mechanisms which later on, we apply, in order to obtain an estimate for the surface shape. We exemplify our algorithm on a 40 resistors grid.

CFD ANALYSIS OF THE SPACER GRIDS AND MIXING VANES EFFECT ON THE FLOW IN THE CHOSEN PART OF THE TVSA-T FUEL ASSEMBLY

<p>CFD is a promising and widely spread tool for a flow simulation in nuclear reactor fuel assemblies. One of the limiting factors is the complicated geometry of a spacer grid. It leads to the computational mesh with high number of cells and with possibility of decreasing quality. Therefore an approach to simulate the flow as precisely as possible and simultaneously in a reasonable computational expense has to be chosen. The goal of the following CFD analysis is to obtain the detailed velocity field in a precise geometry of <br /> a chosen part of the TVSA-T fuel assembly. This kind of simulation provides data for comparison that can be applied in many situations, for instance, for comparison with simulations when a porous media boundary condition is applied as a replacement of the spacer grid.</p><p>TVSA-T fuel assembly is equipped with combined spacer grids. Combined spacer grid has two functions - support of the fuel pins as a part of assembly skeleton and mixing vanes which ensures coolant mixing. The support part is geometrically very complicated and it is impossible to prepare a good quality computational mesh there. It is also difficult to create a mesh in the support part and the mixing part joint area because of inaccurate connection between these two parts.</p><p>A representative part of the TVSA-T fuel assembly with a combined spacer grid segment was chosen to perform the CFD simulation. Some inevitable geometry simplifications of the spacer grid geometry were performed. These simplifications were as insignificant as possible to preserve the flow character and to make it possible to prepare <br /> a quality mesh at the same time.</p><p>Steady state CFD simulation was performed with k-ε realizable turbulence model. Heat transfer was not simulated and only velocity field was investigated. Detailed flow characterization which was obtained from this calculation shown, that mixing vanes already affect the flow in the support part of the grid thanks to suction effect. Vortex structures disappear approximately 50 mm behind the mixing vanes but the basic spiral character of the flow is preserved in the whole area between two following spacer grids.</p>

Service-oriented infrastructure for flood mapping using optical and SAR satellite data

In this paper, we present the service-oriented infrastructure within the Wide Area Grid project that was carried out within the Working Group on Information Systems and Services of the Committee on Earth Observation Satellites. The developed infrastructure integrates services and computational resources of several regional and national Grid systems: Ukrainian Academician Grid (with satellite data processing Grid segment, UASpaceGrid) and Grid system at the Center on Earth Observation and Digital Earth of Chinese Academy of Sciences. The study focuses on integrating geo-information services on flood mapping provided by Ukrainian and Chinese entities to benefit from information acquired from multiple sources. We also describe services for workflow automation and management in Grid environment and provide an example of workflow automation for generating flood maps from optical and synthetic-aperture radar satellite imagery. We also discuss issues of enabling trust for the infrastructure using certificates and reputation-based model. Applications of utilizing the developed infrastructure for operational flood mapping in Ukraine and China are given as well.

Broker hybrid algorithm for NordugridARC 2.0 for Ukrainian grid segment

With the development of science one can observe an increase in the volume of experimental data to be analyzed to obtain new knowledge. The current volume of such computations often exceeds the capacity of a single cluster to compute in a satisfactory amount of time. Therefore, there is a necessity in a distributed computation of such amounts of data using the GRID-systems. For the load balancing in such systems one uses special mechanisms – brokers, which implement a certain policy, under which such system distributes tasks among computing resources according to utilization of computational resources in the system or according to the properties of the task. To implement the algorithm of balancing a broker should take into account enough number of factors to find the most appropriate task that can perform it with the lowest possible load or in minimum amount of time. One can use regular information sources of software that maintain the GRID-system, as well as additional ones that are not included in the standard package of this software. The article is dedicated to the problems of a broker construction using heterogeneous information sources. The proposed method is implemented on the basis of the Ukrainian segment GRID using the software package NordugridARC 2.0. Also, this technique can be implemented on other similar software packages for the GRID.

The Wide Area Grid Testbed for Flood Monitoring Using Earth Observation Data

In this paper we present the results of the Wide Area Grid (WAG) project that was carried out within the Working Group on Information Systems and Services (WGISS) of the Committee on Earth Observation Satellites (CEOS). We describe the InterGrid infrastructure that integrates several regional and national Grid systems: Ukrainian Academician Grid (with satellite data processing Grid segment, UASpaceGrid) and Grid system at the Center on Earth Observation and Digital Earth of Chinese Academy of Sciences (CEODE-CAS). The study also focuses on workflow automation and management in Grid environment, and provides an example of workflow automation for generating flood maps from satellite imagery. Examples of utilizing the developed infrastructure for operational flood mapping are given as well.

Optimization of the cooling circuit and thermo-mechanical analysis for the extraction grid of ELISE

The NNBI test facility ELISE (“Extraction from a Large Ion Source Experiment”), presently under construction at IPP, will have an extraction area with the same width and half the height of the ITER source, acceleration up to 60 kV, for 10 s, every 180 s, and plasma generation up to 1 h. Electrons are co-extracted from the ion source. Suppression magnets in the extraction grid deflect the electrons onto the extraction grid surface. For 30 mA/cm 2 extracted electron current density and 10 kV extraction voltage, localized power density is in the order of 39 MW/m 2 near the grid apertures and a total heat load of 150 kW is deposited onto each extraction grid segment. Heat removal is provided by a water circuit inside the grid. For ELISE, a new cooling circuit has been developed to provide a more reliable operation. The optimization of the cooling circuit and the thermo-mechanical analysis of the extraction grid of ELISE, considering maximum grid temperature, mechanical stresses and grid deformation, has been performed using the codes KOBRA3, TrajAn, the ANSYS finite element package and the fluid dynamics code CFX.

Development of an Algorithm of Dynamic Gridding for Multiphase Flow Calculation in Wells

Summary Because more and more wells have been put in operation, an accurate modelling of wellbore flow plays a significant role in reservoir simulation. One requirement of a wellbore model is its ability to trace various flow boundaries in the tubing, such as those created by phase or flow regime changing. An algorithm of dynamic gridding is applied to the wellbore flow model coupled with Stanford?s general purpose research simulator (GPRS), which has the capability to simulate the isothermal black oil reservoir model to obtain detailed information that explains such important quantities as flow pattern and mixture velocity in any specific location of wellbore. A significant problem in this case is how to calculate fluid and velocity properties with a fine grid (segment) on the boundaries of different flow regimes in the wellbore. Local dynamical segment refinement in the well can accurately and effectively handle this problem. This wellbore model includes mass conservation equations for each component and a general pressure drop relationship. The multiphase wellbore flow is represented using a drift-flux model, which includes slip between three fluid phases. The model determines the pressure, mixture flow velocity, and phase holdups as functions of time and the axial position along the well or alleviation depth. In addition, this model is capable of generating automatically adaptive segment meshes. We apply the black oil model to the simulation of several cases of isothermal dynamical local mesh refinement, and compare the results with fixed coarse and fine meshes. The experiments show that using local segment refinement can yield accurate results with acceptable computational time.