Advanced Materials Research Vols. 614-615

Abstract: When vibration signal analysis method is used to monitor the transformer, the core vibration signal is often obtained as the transformer runs under no-load condition. In this paper, a method extracting core vibration signal without operating transformer under no-load condition was introduced. The transformer vibration accelerative signals at different on-load current and no-load condition were measured. From the fitted curve of on-load current versus fundamental frequency component of vibration accelerated signal, the value of fundamental frequency component was obtained when the on-load current was zero, which was almost equivalent to the fundamental frequency component of vibration accelerative signal measured under no-load condition, thus the fundamental frequency component of core vibration can be obtained by using on-load current method. The core with fault was finally monitored by using the on-load current method compared with wavelet package transform method. From the result of experiment, it can be seen this method is very useful to estimate the condition of the transformer core.

Abstract: A systematic procedure to synthesize dynamic equivalent impedance matching method (EIM) based on the quasi-sliding mode control (QSMC) is presented. Aiming at the existing maximum power point tracking (MPPT) methods’ limitation on the dynamic response, control accuracy and robustness, in this paper, with a boost converter used, QSMC is introduced on the basis of EIM and the synthesis (EIM&QSMC) which not only improves the tracking speed and accuracy, but also further enhances the robustness. The simulation results show that compared with EIM, on the condition of load impedance and illumination change, the synthesis improves the MPPT system on the ability to adapt the circuit parameter variation, which has better control effect and practical significance. The design and the models are validated by Matlab / Simulink simulations.

Abstract: A circuit model of nonlinear inductor with magnetic core based on duality theory is presented in this paper. The presented circuit model of the nonlinear inductor can reflect the magnetic circuit topological structure of the magnetic core very well. The circuit model of the nonlinear inductor based on duality theory was implemented in the PSCAD software for verification. The transient temporal simulation was made at 50 Hz and 500 Hz. The validation of the circuit model based on duality theory has been verified by comparing the simulation results obtained by PSCAD software and ANSOFT software.

Abstract: As the corroded metal grounding usually has a high resistance, the paper presents a new kind of effective graphite grounding conductor to solve the related problems during the reform or construction process. By discussing the ratio of raw material, the structure designs, the principle of reducing resistance and the installation methods in detail, it proves the effectiveness of this grounding conductor. The formula made up with graphite, high-grade cement, small stones and sands, the graphite grounding conductor can show the characteristics of stable performance, excellent corrosion resistance, non-toxic and pollution-free. In addition, the structure of corrugation or cavity can effectively reduce the ground resistance, and it is quite significant for the safe and reliable operation of the power grid.

Abstract: Photovoltaics systems effectively used in buildings will contribute to reduce electrical energy consumption and carbon emissions significantly. Main characteristics and recent development of BIPVs and BAPVs and is analyzed firstly. The system structure and major equipment for an experimental BIPVs/BAPVs system is presented. And a multi-performance comprehensive monitoring and control system integrated both BIPVs and BAPVs is designed as well. It established an important system platform for further analysis of the interaction mechanism among the electrical performance, component reliability, and environmental adaptability of BIPVs particularly.

Abstract: Manchester code is a linear code of the data communication,Because of its good self-synchronization capability and robustness ,it is often used in data synchronization.The design of high-speed stability Manchester codec directly affect the efficiency of data transmission.The programmable logic device has brought a lot of flexibility for the design of digital systems.This paper introduces the application of programmable logic device design Manchester encoder and decoder.And giving the corresponding simulation waveforms while debugging successful with CYCLONE chip of ALTERA.

Abstract: Reactive power optimization is an effective method for improving the electricity quality and reducing the power loss in power system, and it is a mixed nonlinear optimization problem, so the optimization process becomes very complicated. Genetic algorithm is a kind of adaptive global optimization search algorithm based on simulating biological genetic in the natural environment and evolutionary processes, can be used to solve complex optimization problems such as reactive power optimization. Genetic algorithm is used to solve reactive power optimization problem in this study, improved the basic genetic algorithm, included the select, crossover and mutation strategy, and proposed a individual fitness function with penalty factor. The proposed algorithm is applied to the IEEE9-bus system to calculate reactive power. The results show the superiority of the proposed model and algorithm.

Abstract: To improve the tracking accuracy of the maximum power point of photovoltaic cells can improve the operational efficiency of photovoltaic power generation system and reduce the cost of photovoltaic electricity. Because the common perturbation and observation (P&O) runs at a low speed, this paper proposes a new dual-mode control MPPT algorithm based on improved genetic algorithm and perturbation & observation method. Then this method was used in the experiment. From the experimental results can be seen, the algorithm overcomes the shortcomings of the traditional perturbation and observation method can quickly and accurately tracking the maximum power point of photovoltaic cells output, you can improve system output power.

Abstract: The traditional methods to adjust voltage in distribution network reactive power optimization is discretization，and it is difficult to realize the continuous voltage adjustment. A reactive power optimization model and algorithm in distribution network with wind farm is proposed. The network loss，deviation of voltage and stability of voltage are taken into account in the multi-objective reactive power optimization model. The quantum particle swarm optimization（QPSO）algorithm has been used to solve the reactive power optimization problem. The algorithm described particle state by wave function, not only increase the diversity of population，but also avoid premature convergence. The comparison of the simulation result between QPSO and PSO on the modified IEEE 33-bus system demonstrated the effectiveness and advantage of quantum particle swarm optimization.

Abstract: Face to the questions in the traditional video monitoring system, this paper proposed the intelligent video surveillance system based on the 3G technology, developed by the embedded system. The system can realize the information transmitted through the 3G network. And the system has the function of remote real-time audio monitoring, remote viewing and download the video data acquisition, and message security alarm.