Papers by Keyword: Grid

Abstract: Integration of PV systems into the grid is growing rapidly around the world, and PV penetration plays a huge role in minimizing the effect of greenhouse gases in the atmosphere and also contributes to minimizing the impact of load shedding. However, PV systems contribute to grid integration issues such as transients, voltage, and frequency instabilities and reductions in the generator's inertia, respectively; therefore, it is essential to investigate the effect of the PV system on the grid before integrating it. This paper utilized a modified IEEE 9 bus system to investigate the impact of large-scale PV on the power system, and PSCAD software has been used for this study. Four scenarios with different PV penetration levels were considered in this paper. Moreover, for each scenario, the transient stability was assessed based on five parameters, namely: active power, reactive power, rotor angle, rotor speed, and the terminal voltage. Scenario 1 examines the PV systems integrated into a single bus and finds that the optimal PV penetration is 60% of the total power generation. Scenario 2 investigates the effect of integrating PV systems using the optimal PV penetration of 60% distributed into two buses, which was found to be the best for transient stability improvement after a fault condition. Scenario 3 investigates the impact of the power system stabilizer (PSS), using the optimal PV penetration of 60%, and the results reveal that system stability improves when a fault occurs on the bus where the PV system is also connected. Scenario 4 investigates the effectiveness of the fault clearing time on the response of the system with an integrated PV system, using the optimal PV penetration of 60%. The results revealed that a PV system only improves transient stability if the fault-clearing time is below 0.5 seconds; otherwise, the system loses stability. Overall, the study demonstrates that the system’s stability improves up to 60% of the PV penetration level of total generation power.

Abstract: A generalised approach for the modelling of arbitrary shaped deformable structures in the framework of the discrete element method is presented. Minkowski sums of polytopes and spheres are used to describe the geometry of rounded cylinders and particle facets. In the current formulation, these new elements can be deformable. Their deformation is defined by the set of positions and orientations of their nodes. The elements can be connected to form arbitrary structures, such as grids and membranes. The constitutive behaviour of such connections is defined via an elastic perfectly plastic beam model. Contacts between other not connected structures or particles are detected based on three simple primitives: spheres, cylinders and thick rounded facets. The introduction of a virtual sphere at the contact point not only allows for straightforward contact handling but as well for the use of standard contact models based on sphere–sphere interactions. Hence, there is no need for developing new contact models. The approach is implemented into the open-source framework YADE. The capability of the newly developed approach for the modelling of soil–inclusion problems is presented.

Abstract: The average wind power in China increases year by year, obviously wind power output volatility and uncertainty that makes the large-scale wind power grid to bring a lot of problem, such as peaking and frequency modulation, voltage regulator, stability, power quality problems, etc. The power structure in China is given priority with coal-fired thermal power, peaking power is relatively scarce. Lack of wind power on a large scale grid has intensified. The paper briefly analyzes the power grid network frame structure, load and power characteristics in Gansu province. Considering the measured data in 2014 of Gansu power network, intuitive shows Gansu power grid fluctuation characteristics of wind power output in different period of time, discussed the influence of wind power grid peak shaving capability. It improving the large-scale wind power access after the measures of Gansu power grid peak shaving capability.

Abstract: In this paper, the analysis results of the imitative grounding systems consisting of 4 mesh grid with rods are presented by using the Finite Element Method (FEM) and field test. This combined grid with multiple rods configuration was installed by previous researchers [4] and the resistance value is obtained under steady state. The FEM simulations were conducted and the resistance value and electric field profile are obtained. Comparison study in terms of its resistance value is performed between FEM and at steady state, and further analysis of the grounding systems using FEM is presented and discussed in this paper.

Abstract: Multi-scale grid is an essential deformation carrier in optical methods for multi-scale deformation measurement. In this study, several new-type multi-scale grids were designed and fabricated by electron beam lithography. Each pattern includes several periodically distributed dots with the same spacing but different sizes. As a consequence, the grayscale of the whole grid pattern periodically changes. The peak parts of the grayscale generate a secondary grid, i.e., the large-scale grid. The ratio of the large-scale grid pitch to the small-scale grid pitch can be easily adjusted according to the requirement. The natural integration between the small-scale grid and the large-scale grid works well in eliminating the mutual disturbance between the different-scale grids. Besides, this type of grid has a very high success rate in fabrication owing to the small differences in size between the big dots and the small dots. The proposed multi-scale grid pattern is expected to serve as the deformation carrier in moiré methods and geometric phase analysis for multi-scale deformation measurement.

Abstract: Grid dependent tasks rescheduling problem currently are facing triggering frequent. Aiming at this problem, this paper introduces a simple based on Fault Index Based Rescheduling (FIBR). Then it put forward the improved method based on the tax mechanism successful index rescheduling method. Through the method, the grid system can accord the successful index value for task allocation relatively stable resources. At the same time, the method can make the most of the available resources are fully utilized, greatly reducing resource load imbalance situation, effectively improves the utilization of resources in history current stability judgment accuracy. The possibility of rescheduling trigger is reduced.

Abstract: For multilayer mobile sensor network, the issues of improving sensor network coverage by the use of mobile sensors are studied. A coverage-optimized deployment algorithm based on grid-division and bipartite graph matching is proposed. Firstly, the deployment area is divided into many grids and build distribution matrix of sensor nodes. Then construct a bipartite graph G based on the grid-division and solve a matching of maximum cardinality of G. It corresponds to an optimal deployment scheme which maximizes the network coverage and minimizes the total movement cost. Results show that after optimized deployment the network coverage increases, and with the increase in the percentage of mobile nodes it increases accordingly. In the way of distributed calculating the network also can achieve a higher coverage ratio and the movement cost is lower. It is very suitable for deployment of multilayer sensor network.

Abstract: The ability of a mobile robot to plan its path is the key task in the field of robotics, which is to find a shortest, collision free, optimal path in the various scenes. In this paper, different existing path planning methods are presented, and classified as: geometric construction method, artificial intelligent path planning method, grid method, and artificial potential field method. This paper briefly introduces the basic ideas of the four methods and compares them. Some challenging topics are presented based on the reviewed papers.

Abstract: A-distance coloringof is said to be adjacent vertex distinguishing if this coloring satisfy for any pair of adjacent vertices and in, wheredenotes the set of colors that are received by the vertex and all neighbors of with respect to. The minimum number of colors necessary to adjacent vertex distinguishing-distance color, is denoted by. In this paper, we give the exact values of forand, where denotes the-dimensional grid.

Abstract: The finite element modeling is based on the aluminum-silicon alloy piston compression performance test by using both 10-node tetrahedron element and 10-node hexahedron element. After analyzing four grid types, we found that employing both tetrahedron element and hexahedron element can obtain stress-strain nephogram, but with a difference between the four modeling results. In the context of having the same grid size, 10-node hexahedron element reflects a fairly accurate piston stress-strain status than the 10-node tetrahedron element, and among the four schemes, the result calculated by analyzing the locally refined grid that containing both 2mm and 1mm sized 10-node hexahedron grids is the one that matches the experimental value best.