Applied Mechanics and Materials Vols. 291-294

Abstract: A control model of PV cell operating in grid-connected state is researched in this paper. Based on the equivalent circuit of PV (Photovoltaics) cell and its mathematical model, a general engineering control model of photovoltaic array is established. The MPPT (Maximum Power Point Tracing) algorithm is realized by controlling the duty cycle of BOOST circuit to tracing the maximum power, and the control strategy of double closed-loop control of voltage and current guarantees stable DC output and rapid dynamic responses of current. The simulation model can provide guidelines for practice engineering design.

Abstract: Analyses the demand to information flow control technology in smart distribution grid, points out that IEC 61968 based information exchange bus has defects in information flow control, and proposes a framework that consists of flow direction control, information content control and flow runtime control. Based on principle of active and collaborative control, this paper proposes also detailed designs of flow direction arrangement, adapter identification, flow direction analysis, syntax validation, semantic validation and runtime control which consist of start-stop control, traffic control and priority control. The framework and its control functions provide a flexible, uniform and stable solution to information flow control in smart distribution grid.

Abstract: Smart grid is recognized as the development direction of future grid. The text described the current development of smart grid in China from four aspects of the basic features of smart grid, and analysis some technology researches in smart grid, and also put out the current technological bottleneck exists. Meanwhile direct for China's future development of smart grid.

Abstract: Smart grid makes new request for the representation and application of power grid knowledge. To solve the problem of “information isolated island” caused by the continuous development of power grid and the ineffectively use of massive domain knowledge, ontology technology is introduced into the smart grid field. Each link of smart grid is analyzed and new request for knowledge it makes is introduced. Then a simple introduction of ontology and ontology modeling is made. Referring to the defects of existing ontology modeling methods and considering the specific reality of smart grid, an ontology modeling method suitable for the smart grid field is presented, which is aiming at providing guidance on ontology modeling of smart grid. Finally a modeling example is given which proves the feasibility and efficiency of the method.

Abstract: This study proposes combining fuzzy inference system and support vector machine based voltage relays for voltage disturbance detection in micro-distribution systems (MDSs). Moreover, the coordination characteristic curves of the trigger time versus dynamic errors are proposed for under-voltage and over-voltage protection. Modified coordination characteristic curves use a critical trigger time to isolate the faults. An support vector machine (SVM) is a multi-layer decision-making model, which detects voltage disturbances, such as voltage swell, voltage sag, voltage unbalance, and faults. Computer simulations are conducted, using an IEEE 30-bus power system and micro-distribution systems, to show the effectiveness of the proposed voltage relays.

Abstract: With more and more attention are paid on energy security and environment, smart grid has become an important direction of future energy industry development all over the world. In order to fully exploit the role of government on the development of smart grid, this paper first discusses the insufficiency of government function execution during the construction of smart grid in China at present from the respects of smart grid planning, laws making, supervising, electric structure reform, and management function execution. Then this paper presents some suggestions on the fulfillment of government function on the construction of smart grid. Many measures should be taken from both macro and micro field to fulfill the government function on the construction of smart grid to realize healthy development of smart grid.

Abstract: Currently, the electricity infrastructure has remained for a long time, while the demand of electricity is increasing. Smart systems could be employed to improve the performance of electric power grid and reduce the . Especially, the communication technology and optimization technology of smart systems are able to enhance the reliability, stabilization and efficiency of the grid. In this paper, several different communication and optimization technologies are compared and analysed. Finally, the summary is obtained of the utilization of smart systems in order to improve the electric power grid.

Abstract: Jiangsu is one of the most prosperous provinces in China with the highest population density but a shortage of fossil fuel. However, wind energy is recognized as a sustainable resource which is abundant in Jiangsu Province. Even so, the fluctuation of wind power, offshore and non-grid-connected wind power systems are required to manage this fluctuation. In addition, hydrogen production using wind power is a new idea to increase the contribution of wind power. According to the current situation of Jiangsu Province and wind power technology in China, there are both advantages and disadvantages to the method of hydrogen production in using non-grid-connected offshore wind power.

Abstract: The requirement is that the protection relay provides early warning for the protected device in order to guarantee the system reliability and high system security after fault is cleared. The development of new protection functions for smart grid is introduced in this paper. The principles and techniques of integrated state monitoring and main protection techniques for transformers are presented. The principles and techniques of transmission cross section protection which has developed from the line overload protection technique is also presented to show its application to avoid cascading overload tripping. Finally an islanding control system is presented. In the control system the islanding center is responsible for the co-ordination, and optimization and out-of-step relays are responsible for complimentary action. The aim of islanding control is that load-generation imbalance in each island is minimized and generators in each island are not out of step any more.

Abstract: Optimal configuration of distributed generations (DGs) is an important topic in the developing of intelligent power grid. In this paper, to finding out the optimal sitting and sizing Of DGs in distribution network without considering the newly increased load nodes, an economical model is built that regards the annual minimum operating cost as the objective function. Meanwhile, in order to avoid the particles trapping in local optimum, the chaos particle swarm optimization algorithm (CPSO) is adopted. Through testing on the IEEE 33-bus radial distribution system, the analysis results showed that the algorithm is effective.