Advanced Materials Research Vols. 986-987

Abstract: It is well known that mid and long term electric load forecasting has many uncertain factors that influence the forecasting precision greatly, so every forecasting method has its limitation. Considering limitations of basic grey model and conventional improved models, a new practical method called combined optimum grey model for mid and long term load forecasting is introduced. The combined model is composed of partial error optimum grey model (GM) as well as equa-l dimension and new-information grey model. The forecasting algorithm can estimate model parameters, meet the requirements of dynamic power load and overcome random disturbances. Example analysis shows that the forecasting error is below 3 percent. Compared with conventional theoretical methods, the proposed scheme has the characters of simple computation, high forecasting precision and good applicability.

Abstract: Cloud computing is a new emerging paradigm which delivers an infrastructure, platform and software as services in a pay-as-you-go model. However, with the development of cloud computing, the large-scale data centers consume huge amounts of electrical energy resulting in high operational costs and environment problem. Nevertheless, existing energy-saving algorithms based on live migration don’t consider the migration energy consumption, and most of which are designed for homogeneous cloud environment. In this paper, we take the first step to model energy consumption in heterogeneous cloud environment with migration energy consumption. Based on this energy model, we design energy-saving Best fit decreasing (ESBFD) algorithm and energy-saving first fit decreasing (ESFFD) algorithm. We further provide results of several experiments using traces from PlanetLab in CloudSim. The experiments show that the proposed algorithms can effectively reduce the energy consumption of data center in the heterogeneous cloud environment compared to existing algorithms like NEA, DVFS, ST (Single Threshold) and DT (Double Threshold).

Abstract: In post-Kyoto Protocol times, forest carbon-sink has become one of the key path choices to realize clean development for China. Currently, China’s carbon market system has not come into being. So it is necessary to take government-leading model to establish three market systems. They are property relations of coal forest, binding planning for GDP carbon emission intensity and credit trading system of forest carbon-sink. Based on market systems, certified emission reductions (CERs) and voluntary emission reductions (VERs) in mining industry can be developed.

Abstract: This thesis mainly analysed the internal relations between parameters of SiC MOSFET and its dynamic and static characteristics respectively. And furthermore, a new method for modeling of SiC MOSFET based on PSpice was proposed in this paper. By introducing voltage’s controlling for voltage source E, we can compensate and correct the difference between PSpice default value of gate threshold voltage and actual value. At the same time, we can adopt two different junction capacitance models to describe the changes of junction capacitance which were brought about by the difference of the terminal voltage. In the meanwhile, there are newly increased source-drain resistance of MOSFET and gate resistance with the temperature change of variable temperature sub models. New models are able to fully and accurately reflect SiC MOSFET’s static and dynamic characteristics. Moreover, it provides an important foundation for switch process analysis of SC MOSFET, loss calculation and main circuit design. The fact that the experimental testing result is highly coincident with the simulation results verifies the correctness and accuracy of the models.

Abstract: The difference between schedule power flow and online power flow is that the former has no corresponding physical power flow, while the latter is the reappearance of existing physical power flow. Owing to the different premise, the selection of power flow calculation’s known quantities can be different. A schedule power flow schedules physical power flow for power system, so the selection of known quantities has strict requirements, such as active power and reactive power regulation capability. Since the physical power flow exists, the selection of online power flow calculation’s known quantities can be more flexible. For example, we can choose load bus as slack bus or replace PQ bus with PV bus. The example demonstrated that we could locate the stealing electricity buses by choosing load bus as slack bus. Considering that voltage amplitude measurement accuracy is higher than reactive power measurement accuracy, we can replace PQ bus with PV bus and make the power flow calculation results more consistent with the physical power flow. Finally, the examples show that online power flow calculation’s known quantities can be selected flexibly according to the actual situation rather than strictly following the classical power flow calculation requirements.

Abstract: Overhead transmission lines is an important part in the power system and the lifeblood of the transmission system.Important element of the transmission line conductor suspension system namely conductor and insulator, hardware.This paper, by using the fault tree analysis method, establishes the mathematical model of the transmission line conductor suspension system running condition assessment, reliably evaluates the running status of system, find out the weak links and the problems of the various parts, for the evaluation and maintenance of overhead transmission line provide theoretical support.

Abstract: Accelerator has been widely applied to high energy, low energy physics, Medical environmental and military fields, etc. The magnet power supply is one of the most important parts of the accelerator. At the beginning, the state-space model of the magnet power supply has been established by modern control theories. Then, the PSO algorithm has been used for the weight matrices optimization of LQR controller in order to ensure that the magnet power supply can provide a magnetic field quickly which the accelerator required. The experimental results indicate that the method that proposed in the paper can meet the requirements of fast output response of the system and each control index of the LQR controller is obviously superior to that by the traditional method.

Abstract: The non-parametric regression prediction model for dissolved gases in power transformer and its application are studied. As the intervals between two analytic experiments of transformer dissolved gas are unfixed,the data sequence sampled with unequal intervals is converted into the data sequences with equal intervals,which is smoothed to form a new sequence. And then use the historical samples data to establish non-parametric regression model for prediction. Compared with the grey model,the non-parametric regression model has better prediction accuracy. The case verifies the correctness and feasibility of the method.

Abstract: A field-circuit coupled finite element method has been applied on one induction machines for the transient analysis in case of inverter power supply and sinusoidal voltage supply in this paper. The focus is to build the time-stepping finite element method with external circuit coupled to the electromagnetic field equations and achieve voltage supply. The problem of the motion of rotor is solved through moving boundary by interpolation in the moving coordinate system. The induction machine starting transient simulation has been completed using Finite element equations indirect coupled with mechanical equation. The influence of the electromagnetic field and performance has been analyzed compared with sinusoidal condition. This method can be used for dynamic analysis of any power supply taking into account the magnetic nonlinearity of the core material. The established machine overall structure model is closer to the actual. Compared to the traditional analysis method, we can reduce the dependency of experience design. It can also be used for analysis and optimization of the new machine

Abstract: In this paper, we propose a meshless method for solving the mathematical model concerning the leakage problem when the pressure is tested in the gas pipeline. The method of radial basis function (RBF) can be used for solving partial differential equation by writing the solution in the form of linear combination of radius basis functions, that is, when integrating the definite conditions, one can find the combination coefficients and then the numerical solution. The leak problem is a kind of inverse problem that is focused by many engineers or mathematical researchers. The strength of the leak can find easily by the additional conditions and the numerical solutions.