Advanced Materials Research Vols. 960-961

Abstract: The high-voltage DC power supply for electron beam furnace belongs to Special Power Supplies. It has the characteristics of high voltage and high power. At present, the high voltage DC power supplies for electron beam furnace are mostly controlled by the silicon controlled rectifier operated by power frequency, which not only has the disadvantages of large volume but also doesn't has the characteristics of anti-short circuit capacity、 rapid protection and restart. This characteristic affects the service life of the electron gun and the quality of the smelting. To solve the above problems, a high frequency resonant converter has been used in high voltage power supply, reduced the volume of power supply and the switching loss, and achieved rapid protection and restart. Simulation and experimental research show that the power supply can meet the requirement of smelting.

Abstract: This paper discusses effect of phase sequence layout on electric field under overhead lines. Charge simulation method is used. Examples of two circuit overhead lines and four circuit overhead lines show that phase arrangment of lowest height conductors has major influence and phase arrangment of middle height conductors has lesser influence on electric field under overhead lines. Interlacing placed lowest height conductors with different phase and phase arrangement of middle height conductors different from that of lowest height conductors help to reduce electric field.

Abstract: A 60kV/6kW high voltage power supply for electronic beam welder (EBW) based on LC series resonance is designed. It adopts pulse frequency modulation (PFM) way to adjust the output voltage, and it has over-current and over-voltage protection. The test proves that high voltage power supply has reached zero current switching (ZCS) on and ZCS off, and satisfied the actual requirements of welding technology.

Abstract: Over-voltage in the power system can be caused by a lot of reasons , including higher frequency ferromagnetic resonance overvoltage which occurs in normal operation and causes great harm. Overvoltage events often result in damages to electrical equipment or even power outages . In this paper,ferromagnetic resonance is analyzed to study harm , causes, conditions , and phenomena and to handle resonance and develop practical preventive measures. The related analysis is important to work for the future operation of the power grid to prevent and limit the ferromagnetic resonance over voltage which provides some help to further ensure the safety and stable operation of the power grid .

Abstract: With the interconnection density and doubling the number of layers in VLSI, Interconnect line width,pitch,and the thickness of the dielectric layer will changed within the same chip caused by the process variation. and the interconnect parasitics changes ultimately affect circuit performance and yield.IC designers need an accurate BEoL corner model to help circuit design. Standard Interconnect Performance Parameters (SIPPs) is standard method to measure ultra-large scale integrated circuit BEOL performance. Designed parallel plate, layer-skipping parallel plate, comb meander, comb meander for via resistance test structures to extract SIPPs according to their sensitivity differences to different test structures, and realized them in CIF format file with High-level Perl language automatically. Then change to GDSII format file that wafer used widely by Cadence layout software, and pass electrical rule checks. Greatly improved the efficiency of test structure’s design and realized. Lay the foundations for formulation of Design for Manufacturability physical design rules and further research interconnection statistical models under nanometer technology with more unique physical phenomena.

Abstract: Network reconfiguration is of theoretical and practical significance to guarantee safe and economical operation of distribution system. In this paper, based on all spanning trees of undirected graph, a novel genetic algorithm for electric distribution network reconfiguration is proposed. Above all, all spanning trees of simplified graph of distribution network are found. Tie branches are obtained with spanning tree subtracted from simplified graph. There is one and only one switch open on each tie branch. Decimal identity number of open switch on each tie branch is taken as the optimization variable. Therefore, length of chromosome is very short. Each spanning tree corresponds to one subpopulation. Gene operations of each subpopulation are implemented with parallel computing method. Individuals of offspring after gene operation automatically meet with radial and connected constraints for distribution network operation. Disadvantages of conventional genetic algorithm for network reconfiguration that a large amount of unfeasible solutions are created after crossover and mutation, which result in very low searching efficiency, are completely overcome. High calculation speed and superior capability of the proposed method are validated by two test cases.

Abstract: This paper proposes a methodology for the aggregation of distribution network, induction motors and static loads. This methodology can aggregate induction motors and static loads model into one composite load model with distribution network considered. The absence of simplifications, the proper aggregation of distribution network and the adequate handing to motor mechanical load allow this methodology shows pretty good accuracy. A simple simulation test is also taken to validate the proposed methodology.

Abstract: A method is proposed to design a wide-area damping controller (WADC) based on fuzzy control to dampen the low-frequency oscillations of interconnected power systems. First, the inputs and expected outputs of a fuzzy logic controller are analyzed. Then, a universe of fuzzy sets, membership functions and fuzzy rules are determined based on the relationship between inputs and outputs, and the fuzzy logic controller is constituted. The WADC consists of a fuzzy logic controller and a gain. The gain is obtained using particle swarm optimization. A four-machine two-area power system is simulated using the Matlab/Simulink software to test the performance of the fuzzy-based WADC. The simulation results indicate that the designed controller can compensate for communication delay and improve interconnected power system damping.

Abstract: In view of faults which the traditional genetic algorithm (GA) have such as slow convergence speed and easy to fall into the local optimum. This paper put forward a genetic algorithm which is based on the multi-island group strategy, and applied it to the distribution network planning. The paper has established a planning model which takes the yearly comprehensive cost as objective function and discusses the repair methods of islands, solitary chain and closed-loop to meet with the requirements of grid radial. Finally, the proposed method is planning on a 54-node grid to prove the effectiveness of the algorithm and model.

Abstract: It is common practice to use 2^nd order polynomial load model for steady-state power flow calculation. The paper describes the experiment for obtaining static load characteristics and the technique for identifying coefficients of the load model based on remote metering system data.