Applied Mechanics and Materials Vols. 494-495

Abstract: Concerning the uneven distribution of energy in Chinas regional power grid, power of big energy base should be transmitted through long distance. Therefore, calculating available transfer capability (ATC) of large interconnected grid is necessary. However, it is difficult to collect the needed data, so ATC of the large interconnected grid cannot be calculated directly. To solve these problems, this paper presents a decomposition calculation method to calculate ATC of the large interconnected grid. The basic principles are: According to the executive partition, the large interconnected grid is divided into several subsystems, of which ATC can be calculated directly and easily. Then, according to series or parallel combination between the subsystems, ATC of the large interconnected grid can be calculated indirectly by the obtained ATC of subsystems. The series and parallel ATC probabilistic calculation models are established, used for synthetizing ATC of the subsystems. Illustrations verify the correctness and feasibility of the calculation method.

Abstract: In this paper, the dynamic characteristics of a 1000kV UHV steel tubular tower with double circuit transmission lines on the same tower are analyzed under seismic loading with 8 degrees fortification intensity. Firstly, the finite element model of the tower and simulation of the earthquake are built in ANSYS finite element software. The dynamic characteristics of steel tube tower under Seismic Loads, such as the time-domain curves of displacement, velocity and force of UHV steel tower under Seismic Loads are obtained. The impact of 1000kV UHV transmission tower under nonlinear vibration of simplified conductor model is studied. The results can help to understand the damage forms of UHV steel tower under earthquake, to improve the capabilities to resist earthquake loads and severe damage of environmental loads under various field conditions for UHV steel tower.

Abstract: In this paper, a novel modelling approach based on characteristic fusion is proposed and used to build a static equivalent model of wind farm. Firstly, the modelling framework based on characteristic fusion is given. Secondly, the basic characteristics of wind farm including characteristic of wind turbine generator (WTG), wind speed spatial distribution and characteristic of wind farm are analyzed according to the framework. Then detailed modelling process is provided utilizing SVR as a fusion tool. This approach combines the advantages of both mechanism and non-mechanism methods with both satisfactory fitting ability and generalization ability. It only requires the maximum and minimum value of wind speed among the wind farm, rather than accurate wake model as mechanism method nor massive measurement data as non-mechanism method. Numerical simulation indicates the effectiveness and robustness of the proposed method. When available data is reduced or includes bad measurement, the proposed method can still keep favorable performance.

Abstract: The variable speed wind turbine generator exhibits serious nonlinearity, uncertainty and difficulty accurate modeling, conventional PID controller can't achieve ideal control effect. In this paper, an adaptive inverse control scheme based on neural network identification technology is proposed to solve the above problem. The scheme firstly uses online identification of one DRNN to obtain the Jacobian information of plant. On this basis, another DRNN identifies the inverse plant model which constitutes adaptive inverse control system as controller. The simulation results verify that the adaptive inverse control scheme has excellent adaptability and robustness, which can make the actual rotational speed of wind turbine rapidly track the set point to maintain the best tip-speed ratio in order to get maximum wind energy capture in the random wind conditions.

Abstract: Doubly-fed induction generator (DFIG) is the leading in wind power technology currently. In this paper, decoupling control of DFIG is studied and a new energy storage device is used in the smooth control of DFIG system’s power and voltage. This new method has a good characteristic on stability of grid-side power and voltage when the wind speed changes rapidly. In this paper, a simulation system based on this method is designed using MATLAB, the experimental results of simulation show that the method is correct and has practical value.

Abstract: In order to increase the performance of the current high voltage grid for pulse shocking, which is imperfection in controlling the intensity of pulse shock in the high voltages, a set of perimeter prevention high-voltage grid system is design with using the programmable logic controller (PLC). In this design, the average filtering algorithm is applied for promoting the accuracy of the intensity. The feasibility of the algorithm is verified through simulation. In this paper, the algorithm and the experimental procedure are mainly discusses, and so get some result about the changeable resistor, which could adjust the intensity of high voltage pulse shock.

Abstract: With the development of smart grid, mass data collected in real time for equipment monitoring requires higher performance of data store. Hence, a storage system based on cloud platform for smart grid equipment monitoring is designed and achieved. Aiming at electric power monitoring data, this paper designs an improved PI revolving door compression algorithm, which improves the performance of data transmission and storage. Related experiments show the effectiveness of the algorithm. The storage system meets the requirements of real-time, mass, high reliability and high performance of data store in smart grid.

Abstract: Integration of large scale renewable energy sources and electric cars into power grid will bring new opportunities and challenges to the operation, control of the power grid and the power market .The microgrid , which integration the distributed generation systems, energy storage element and loads ,has been seen as one effective way to solve the problems. This paper proposed a MEA-based scheduling algorithm, and studied a microgrid that contains 32 nodes and 50 electric cars. Both the MEA algorithm and mixed integer nonlinear programming algorithm (MINLP) can solve the energy resource scheduling problem,but the results of our simulation shows that the total cost of MEA is higher than that of the MINLP,but there is a significant improvement in the efficiency of execution.The results shows that we can use MEA to achieve optimal scheduling,it also verify the effectiveness of the algorithm.

Abstract: This paper presents the efficiency enhancement for a novel photovoltaic/thermal (PVT) air collector in which PV and thermal efficiency is simultaneously enhanced with a reciprocal aid. With the encapsulation of solar cells directly on a fin-type heat sink, the direct conduction mechanism and the convective area for the thermal transportation are effectively increased. Through a two-month experiment measurement, it is found that the thermal efficiency of PVT module is obviously enhanced up to over 50% in sunny days. In addition, the waste heat recovery decreases the operating temperature of solar cells and concurrently improves the PV efficiency. The results demonstrate the concurrent enhancement of the novel PVT module in PV electricity and solar thermal efficiency.

Abstract: Particle Swarm Optimization (PSO) algorithm converges fast but it is easy to fall into local optimum, and bacterial chemotaxis (BC) algorithm prevents premature convergence and prevents falling into local optimum, so a new mixed bacterial chemotaxis (MBC) algorithm is proposed by combining the PSO with BC. The novel algorithm is applied to reactive power optimization on power system. First the PSO is used to find best solution, then BC is used to find the optimal solution among the selected area of previous step, the reserving elite strategy is introduced to enhance the efficiency of the algorithm, and then the optimal solution is obtained. Through the comparison with PSO and BCC in the reactive power optimization of IEEE30-bus system, the results indicate that MBC not only prevents premature convergence to a large extent, but also keeps a more rapid convergence rate than PSO and BCC.