Advanced Materials Research Vol. 811

Abstract: The problem of mean square bounded-input-bounded-output (BIBO) stability for the stochastic delay systems with nonlinear perturbations is investigated in this paper. Using the Razumikhin technique combined with comparison principle, several novel BIBO mean square stability criteria are established. A numerical example is given to illustrate the effectiveness of our result.

Abstract: Existing inventory lot-sizing models assume certain demand and sufficient supply, which are not practical for industry. Dynamic inventory models can serve uncertain demand, but supply is assumed to be available. However, in the real world situation, supply is not always offered. So, the method that can deal with both uncertain demand and supply should be developed. Fuzzy logic control is now being the effective methodology in many applications under uncertainty. Therefore, a fuzzy logic approach for solving the problem of inventory control under uncertainty was proposed for a case study factory. In the proposed Fuzzy Inventory System (FIS), both demand and availability of supply are described by linguistic terms. Then, the developed fuzzy rules are used to extract the fuzzy order quantity and the fuzzy reorder point continuously. The order quantity and reorder point are both adjusted according to the FIS system. In this research, the suitable ranges for the inputs of the FIS model are justified for the case study factory. Moreover, the effect of trend demands for both increase and decrease are also analyzed with the proposed range. Inventory costs of the proposed fuzzy inventory system are compared with the existing model based on historical data of the case study factory. It found that the proposed range can obtain lower cost than the previous research FIS lot-sizing model, which is better than conventional approaches.

Abstract: The effect of load model on the analyses of load flow, transient stability, small disturbance stability and voltage stability is analyzed. The importance of the load modeling research is emphasized. The development of component-based method and measurement-based method is reviewed. The advances on the load model research including the select ion of load model structure, model parameters identification, load model with the voltage stability analysis and the sensitivity of load model to the transient stability is summarized.

Abstract: This paper proposes a general overview of distribution network automation technology. With the continuous development of society and economy, the distribution network automation has become the trend and developing direction of electric power system. As the end part of the electric power system, the distribution network is directly connected to the consumers and plays a vital role in improving the quality and reliability of power supply. In order to provide reference for improving the reliability of distribution network and to speed up the development of distribution network automation, this paper analyses the system structure, development status and trend of distribution network automation technology.

Abstract: The dynamic voltage restorer (DVR), as an important electrical installation, can handle the voltage sags and stable the electrical power system. This paper talks about power system operation problems - Voltage dips, then briefly introduces Dynamic Voltage Restorer basic structure and principles, the then mainly complaint about the dynamic voltage restorer research. At last, it will give us a conclusion and the future development trend.

Abstract: Flexible AC transmission technology (FACTS) is a new technology developed in recent years. It use power electronic technology and modern control technology to achieve fast control for AC transmission system parameter and structure [, to achieve the rational allocation of transmission power, reduce the power loss and the cost of power generation, greatly improve the stability and reliability of the system. STATCOM is based on the principle of reactive power compensation, using full-controlled switching devices to compose self-commutated inventer, complemented by small-capacity storage elements constitute reactive power compensation device. Its role in the power system is the compensation of reactive power, maintain the voltage of the connection point, improve system voltage stability, and improve the steady performance and dynamic performance of the system.

Abstract: In order to study on the problem of voltage stability of power system, this paper describes the static bifurcation analysis and the dynamic bifurcation analysis in voltage stabilization analysis of power system and its relationship with the voltage stability,discusses the voltage instability caused by two main bifurcation formal definition, the occurrence of the conditions and the calculation of the bifurcation point, and points out advantages and disadvantages of various algorithms. Finally the paper looks forward to further study of the bifurcation theory in terms of voltage stability.

Abstract: With the development of modern technology, high quality power supply becomes more desirable in everyday life. Among problems related with the power quality, the most urgent is the voltage dip; with the application of power electronics devices, the power system is polluted by harmonics. SMES (Superconducting Magnet Energy Storage) system can not only compensate the voltage dip, but also provide a load-fluctuation compensation and active power filter. In the paper the main structure of SMES system is introduced; the necessity to use SMES are demonstrated by analyzing the problem of power quality. The analysis shows that SMES system is effective in improving the power quality.

Abstract: e. The formalism of wireless power transmission is discussed coupled mode theory can be used to describe the resonance process. According to the changing process of input impedance and input current to describe the demarcate of resonant frequency. also demonstrate that loop circuits have an important effect of the resonant magnetic field distribution.

Abstract: With the wide application of power electronic equipments in power system, more and more harmonic are poured into the power system, which cause power pollution and make the power quality problem increasingly serious. Active power filter (APF) is an important equipment to compensate harmonic and reactive current in power system. One of the key technologies lies in the real-time and accurate control. The fundamental principles of several control strategies of compensate current were presented, and the respective merit and demerit of these control strategies were pointed out with contrast analysis in this paper. Active power filter will achieve a higher performance and a wider application with the continuous development of the control strategy.