Advanced Materials Research Vols. 614-615

Abstract: Smart distribution grid is an open grid, in the process of its deployment must be fully consider its safety problems. Based on the technical system and features of smart distribution grid, the security of smart distribution grid is divided into three levels, smart distribution grid may be the emergence of new safety issues, from data acquisition and processing, information transmission and information applications, this paper expounded on the security technology of the future smart distribution grid.

Abstract: Traditional power flow calculation can only supply the information of the conventional electric parameters, such as node voltage, branch current, power, etc. The transmission of power which is injected into the network by each power source, including power supply paths, power belongs, relationship among the power injected into each nodes, cannot be given. To solve this problem, this paper using the theory of the physical distribution of power network’s energy, proposes a matrix method for describing the power transmission, expresses the value and supply paths of the power from each single source in power network with the analytic method.

Abstract: At present the research of power grid maintenance scheduling is mostly focused on reducing the maintenance costs or improving the reliability, which ignores the potential risk of power grid during repairing to a certain extent. Considering the potential risks of power grid and users fully, a new optimization model is built here. The model’s objective function is the minimum of the comprehensive risk cost caused by maintenance, the constraint conditions are list as synchronous overhaul, mutually exclusive overhaul, security checking and resource requirement and so on. The improved particle swarm algorithm is chosen to achieve a better convergence here. The analysis of the RBTS system example verifys the effectiveness of the model and algorithm.

Abstract: The low voltage DC (LVDC) distribution system is a new concept and a promising technology to be used in the future smart distribution system having high level cost-efficiency and reliability. In this paper, a low-voltage (LV) DC microgrid protection system design is proposed. Usually, an LVDC microgrid must be connected to an ac grid through converters with bidirectional power flow and, therefore, a different protection scheme is needed. This paper describes practical protection solutions for the LVDC network and an LVDC system laboratory prototype is being experimentally tested by MATLAB/SIMULINK. The results show that it is possible to use available devices to protect such a system. But other problems may arise which needs further study.

Abstract: Firstly the current situation and demand of power wireless communication was analyzed, and the technical characteristics of a variety of wireless communication applicated in the area of distribution were summarized, then, Considering strict requirement for QoS, high data rate, mass uplink data, and a large number of users, a solution based on TD-LTE Technology is purposed for 230MHz broadband wireless transmission. Therefore, MIMO, OFDMA and Carrier Aggregation Technology are all improved to realize the broadband wireless transmission of power communication under the condition of discrete, narrowband carrier.

Abstract: This article investigates the characteristics of the Power IoT, and a design scheme for the intelligent community based on Power IoT is proposed. According to the requirement analysis, the intelligent community designed consists of electric energy data acquisition system, distributed energy access monitoring and control system, smart home system, community service management system. Considering multiple communication technology in smart grid, a unified communication platform is built for information interaction among the systems. Finally, the intelligent community would provide a safe, comfort, energy-saving and humanized living environment for the residents.

Abstract: With the development of micro-grid, the protection and control technologies for micro-grid have withdrawn broad attention. By analyzing the interactions between the micro-grid and the main grid, a dual-processor based coordinator is proposed in the paper. This coordinator achieves the functions of protection and control through two processors, utilizing the electrical information from the whole network, realizing the wide area data sharing and sound cooperation of the unit protection and regional control in the micro-grid. The proposed method enables smooth transition between grid-connected and islanded operation, which is adaptive to any operational modes. Implemented in a demonstrative project of the micro-grid in china, this novel method is verified to be efficient.

Abstract: Power scheduling of the Intelligent Community is an important issue, and it is also an important part of the Smart Grid. With the target of saving and rationally distributing energy, this paper studies the power scheduling problem of the Intelligent Community. Firstly it designs a framework of power scheduling system. Then, based on the framework, it proposes a power balanced scheduling model among users of the Intelligent Community, and uses the classical simplex method and the improved table-working method respectively to solve the model. Simulation results show that the proposed model and the designed methods can realize power balanced scheduling and minimize the loss in the power scheduling process, and therefore make the electrical power fully utilized.

Abstract: Transient capability improvement of doubly fed induction generator (DFIG) during low voltage ride-through (LVRT) is important for both generator and grid safety. A theoretical current control method is introduced here to deal with LVRT of wind turbines with DFIG under symmetrical voltage dips. The objective is achieved by balancing the energy that flows in and out the DC-link capacitor. Simulations performed by Matlab software demonstrate the capabilities of the proposed method in enhancing the DFIG’s performance during low voltage ride-through.

Abstract: With constrains imposed by natural conditions, the power generated from wind power, solar power and other intermittent energy system has great randomness and volatility. Thus, the impact from the intermittent energy to the system voltage and power flow is uncertainty. In view of this problem, this paper studies the characteristics of these double random variables and correlation. By using the typical probabilistic load flow and Monte Carlo simulation method, this paper poses the probability load flow adapted to the intermittent distributed generation. Finally, taking IEEE33 distribution system for example, this paper obtains the mutual relationship between the power from the intermittent distributed generation and the probability distribution of the node voltage, current distribution of each branch.