Applied Mechanics and Materials Vols. 672-674

Abstract: Microgrids are attracting a great deal of attention as integrated renewable energy resource can benefit both the utility and the customers. The droop-control method is popular for the microgrid stable operation as it avoids circulating currents among the converters without using any critical communication between them. The distributed generators should have high speed to follow the reference given by the droop controller, otherwise the system will fluctuate and even black out. Renewable energy powered Distributed Generators (DGs) are mostly inverter-interfaced and controlled by PI controllers. The Particle Swarm Optimization (PSO) was used to optimize the PI parameters with the objective of high tracking speed of the Inverter-interfaced DGs. Simulation studies in Matlab demonstrate the effectiveness of the optimized control parameters.

Abstract: To deal with the super short-time energy management of microgrid, a mixed-integer programming optimization algorithm combined with genetic algorithm is proposed. Firstly, this paper introduced the short-time economic dispatch mathematical model of microgrid. Secondly, a two-layer optimize algorithm is been developed. The lower layer takes no account of power flow constrains, convert the model into a mixed-integer programming problem through linearization techniques. The lower layer gets the generation schedule, and then passes the data to the upper layer. The upper layer takes the power flow constrains into account, optimize the unit output based on genetic algorithm. The simulation result shows that the proposed algorithm achieves a better complementary of the two kinds of optimization algorithm. At the same time, the optimization result also shows the effectiveness of the algorithm.

Abstract: With new technology, Wisdom City makes the various functions of the city in coordination with each other. It provides high quality development space for enterprises and high quality of living for citizens. As an important part of Wisdom City, Smart Grid can ensure the safety of electricity consumption, improve the urban communication network and promote the city green development and industrial development, etc. This paper analyzes the supporting role of Smart Grid in Wisdom City top design, data mining, communication resources, policy system, business model and evaluation index, etc.

Abstract: There is a need to build power grid on RTDS in order to testing performance of security and stability equipment (SASE). The paper divide a large-scale province power grid into four region grid with present RTDS hardware capacity in a view to include all stations installing SASE in a single region grid and disconnect lines as few as possible between adjacent region grids. The paper gives method of manually calculating and modeling node’s power balance, keys of building region grid and matters needing attention transforming parameter format from BPA to RTDS, and then simulating results show that steady state error of some variables are less than one percent, all less than 10 percent and transient characteristics help SASE to start-up to some extent.

Abstract: The wind-solar-storage and other distributed generation (DG) accessing to the distribution grid and user’s interaction with the grid change the business’s forms of the traditional distribute and utilize system, and while the supplier and demander of electric power also set higher requirements on business’s functions of the smart distribution and utilization system. Based on business requirement of smart distribution and utilization, the major content and function of distribution and utilization link are discussed, including intelligent planning, intelligent dispatching, self-healing control, demand side management, two-way interaction and so on. It makes the architectures of business and the objectives of construction more clear and promotes the construction of the business system in the smart distribution and utilization system.

Abstract: Accessing electric vehicle (EV) into micro-grid (MG) by battery-swapping station (BSS) will not only reduce the negative impact brought by EVs which are directly accessed into MG, but also improve the capacity of MG to absorb more renewable energy. That BSS is regarded as schedulable load is guided to avoid peak and fill valley according to TOU. As a result, the gap between peak and valley of MG is decreased and the operation efficiency of MG is elevated. A specific MG is taken as the studying object and the minimum operating cost is regarded as the optimizing goal, then the genetic algorithm is used to optimize the outputting of each micro-source and the charging power of BSS so that the optimal operation is realized.

Abstract: Smart Distribution Grid and Utilization are the important support for the development of Smart City and Smart Grid, meanwhile, the effective data communication and information exchange are the key points to implement them. First, analyze the unified communication method of Smart Distribution Grid and Utilization for each specific business. Then, respectively, from the current reality and future trends, propose two typical implementation:the interface adapter pattern and the integrated pattern, and establish specific implementation patterns, deployment patterns, and pattern evaluations, so as to provide the design of pattern level for the development of Smart Distribution Grid and Utilization.

Abstract: Present icing monitoring system mainly depends on detecting the meteorological parameters and dynamic characteristics of the structure of the overhead icing line. However, all these systems need additional equipments for data collection. This paper provides a new method based on voltage and current of both ends of the line and discriminates the icing region and its severity via the change of active power and reactive power. It requires the voltage and current serving as signal source which is provided by the data collecting device on the both ends of lines. In this way it can accomplish the Monitoring task of icing transmission.

Abstract: The comprehensive impacts of series resonance type fault current limiter (FCL) on power system need further investigation and verification. With regard to switching on 500kV EHV no-load transmission line, the instantaneous peak value, the free component oscillation frequency, the fundamental component amplitude and free component amplitude of terminal overvoltage waveform are simulated with and without installation of FCL considering different switching times. The relationship curves of free component oscillation period, the fundamental component amplitude and free component amplitude are gotten respectively by simulation results. The law of the influence of different fault current limiting reactance on terminal voltage of switching on no-load line is also summarized. The analysis results show that the installation of FCL is benefit for switching on no-load line.

Abstract: In this article, in order to provide a reference for determining the location of fiber optic temperature probe in saving distribution transformers,we analyze the internal transformer by the basic heat transfer theory and simulate via ANSYS simulation software, determining the location of the highest temperature separately of the high and low voltage winding and iron core. The simulation results will be as a reference value for the experimental results. Therefore, it is very significant for analyzing the hottest point distribution of distribution transformers and improving thermal design of dry type transformers and temperature monitoring that the numerical simulation of dry-type distribution transformers of temperature field.