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With SVG technology becoming more and more mature, chain SVG is also installed in some power grid substations to solve local power quality problems, and certain effect has been achieved. Compared with other compensators in the substations, for example, capacitor bank, SVQC, SVC etc, actual loss of SVG is above average level, this limits its practicability.This paper puts forward a method that utilizes soft switch technology to reduce IGBT on/off loss in SVG device, gives main circuit topology of the designed soft switch PWM inverter, and the comparative analysis with on/off loss of hard switch, proves effectiveness of this method.

As SVG products get more and more popular, new products keep being developed for the demand of actual operation. Intensive SVG is a new kind of SVG developed on the basis of conventional SVG products. The main characteristic of the so-called “intensive SVG” is the draw-out type power module which is featured by small volume, low loss and strong environmental adaptability. The power unit is the core of SVG and its reliability is the foundation on which the entire system functions. Therefore, the reliability evaluation is of vital importance. In this paper, a method of studying its reliability by setting up a reliability module is introduced, which may help with equipment maintenance in future.

Outdoor SVG is the SVG that is derived from conventional SVG, and can be used on sites of limited space. After repeated technical upgrading, this kind of SVG is functioning more and more stably, and is well received by clients. However, since the internal space of outdoor SVG is greatly compressed, and overheat trip still occurs in “extreme environment”. Because the “extreme environment” is just occasional, increase in number or power of fans will greatly increase equipment cost and failure points, most SVG manufacturers are not willing to adopt this strategy. In this paper, the outdoor SVG “overheat capacity reduction” control strategy based on wireless bluetooth humidity and temperature monitoring system is proposed, which ensures that the equipment can run safely in “extreme environment”, saving labor and materials remarkably.

This paper presents a topic ontology tree based hierarchical HMM (hHMM), and the generation of topic property based life cycle curve is studied. Compared with the traditional methods, this model can describe the hierarchy relations of topics.

The topic tree-based topic structure model is proposed using five-tuple and probability theory of ontology. Vocabularies in the glossary are presented with leaf nodes of the topic tree. The results of simulation experiment on real news corpus eventually show that the topic similarity of sym-KL divergence could construct a topic tree more accurately and dig the potential semantic topic characteristics of time and space more deeply in the text stream compared with other flat topic structure models.

The bearing lubrication system flow distribution design of the transmission was realized with a new system modeling method, targeted at the problem of a certain type of transmission’s bearings’ sintering. The heat-generated model and the flow-required model of the bearings and the gears were set up, and the required lubrication flow was obtained. The simulation model of the system flow distribution was established, the simulation analysis toward the dynamic characteristic of the transmission’s lubrication flow’s distribution was performed, and the results of the simulation analysis and the test were analyzed comparatively. The result showed that the simulation model matched the test result well, proving the effectiveness and correctness of the model of the transmission’s flow distribution.

Before commissioning, SVG first requires a separated excitation process: network voltage charges the capacitor on DC side in each H-bridge power module via the starting resistor (IGBT in all modules shall lock impulse). After charging, SVG has enough power for dynamic var compensation of the system. This paper introduces fundamental functions of the starting resistor in SVG, analyzes the influence of starting resistor selection on safe operation of the device, raises the principle of selection and conducts simulation verification by using of PSCAD.

Chain SVG device is connected to the power grid via the reactor which is also referred to as connection reactor. Compared with other reactors of reactive compensation devices, It’s not like the serial filtering reactor which simply provides a specific quantity of inductive reactive power, or parallel phase control reactor which provides continuously adjustable inductive reactive power. The connection reactor in SVG is related to the impact of SVG on the power grid, the impact of the power grid system on SVG, and in particular, the compensation capacity and effect of SVG. Therefore, during design, requirements of SVG and electrical property of the compensated system should both be considered. In this paper, the impact of the connection reactor on SVG stable operation is analyzed in detail. The design principle that when choosing the reactor parameters, the impact on power unit DC side voltage should be prioritized is proposed, and simulation verification is conducted by using of PSCAD software. A reasonable reactor is selected for a 10kV SVG based on the conclusion. The actual operation result verifies the rationality of design.

power quality problems such as high line loss, low voltage exist commonly in rural power grid of China due to few supply points, long power transmission and distribution line. Huge fund is required to increase the quantity of supply points in rural power grid; installation of var compensators on line nodes could not solve power quality problems on the whole line. At the same time, as distributed power supply, wind power is also restricted by peak regulation, insufficient line output capacity and other factors in large scale centralized grid-connected output, wind curtailment often occurs. In order to solve the above-mentioned two problems simultaneously, electric power of wind farm may be output via nearby rural power grid line, thus not only utilization rate of wind power is increased, but also power quality of rural power grid is improved.This paper takes an example of a district in Fuxin City, summarizes power quality change data of relevant rural power grid before and after the distributed grid connection of wind farm is made, the analysis shows that distributed grid connection of wind power could improve load flow distribution of the power system, reduce system transmission loss in this district obviously, increase economical efficiency of the system operation effectively. At the same time, effectiveness of static var generator in substation to overcome the impact of such grid connection mode on power grid is verified.

SVG is a device parallel on the power grid for dynamic reactive power compensation, is a product of best performance and mature technology in the third generation dynamic reactive compensation technology so far. Thanks to power unit module series structure and PWM technology, compared with multiple SVG, chain SVG has high capacity, low loss, simple maintenance. But more complicated in control, indirect current control technology and direct current control technology are adopted. This paper utilizes PSCAD simulation software to build a chain SVG direct current controller model according to mathematical model of the chain SVG, simulates SVG compensation with inductive load and capacitive load, so as to verify advantages of fast tracking speed and stable control of direct current controller.

Traditional voltage regulating means, for example, change the transformation ratio of on-load tap-changing transformer, switch on/off parallel compensation capacitor etc, could not solve transient voltage drop effectively due to slow response speed and inaccurate control. SVC and SVG adopt power electronic device that may be turned on/off at high speed and instantaneous reactive power theory, could output huge reactive power within very short time smoothly, so they are capable to suppress transient voltage drop.This paper analyzes the principles of SVC and SVG to suppress transient voltage drop theoretically, studies their characteristics in this respect through simulation, puts forward precautions for both devices to further suppress transient voltage drop according to the simulation result.

The dry hollow reactor has the features of good inductance linearity and heat dissipation and is not easy to produce ferromagnetic resonance with capacitive load in the system. Therefore, the phase controlled reactor in TCR-type SVC is usually a dry hollow reactor. According to years’ actual operating condition, the phase controlled reactor in 35kV SVC or SVC at a lower level operates stably while tree discharge or breakdown failure frequently happens to the phase controlled reactor in the 66kV vertical SVC, which seriously affects the stable operation of the equipment. This paper puts forward a method of installing arrester on the phase controlled reactors to relieve the SVC switching overvoltage impulse and protect the phase controlled reactors. Besides, it uses PSCAD to conduct a simulation and verifies the feasibility of this method.

Recently, with the increasing strength of attracting business and investments in Liaoning coastal area or big cities’ suburbs (counties), a large number of industrial and mining enterprises have shifted to rural areas. The rural areas’ power load is growing rapidly, but at the same time, many power sites such as 66kv substation, 10kv transmission line, and low-voltage distribution area have occurred different levels of “low voltage”, which affect the daily life and production of native residents. From 2011, Liaoning Electric Power Co., Ltd. has applied the third generation of dynamic reactive power compensation technology—SVG to control the “low voltage” of rural network, which has fast speed and strong compensation. And as a consequence, there is good social and economic benefit.

In order to solve the problem of low voltage at a terminal rural power grid 66kV substation, a 5000-kilovar SVG is arranged in the substation to elevate and stabilize the 10kV bus voltage. Since put into operation, SVG runs well, solving the problem of low voltage while lowering the loss of the entire line. However, in some cases, people find that while stabilizing the bus voltage, SVG causes voltage drop in adjacent substation, and act of the intelligent capacitor unit in the adjacent substation, thus leading to opposite reactive response of SVG, affecting voltage stabilization of the two substations and adding up to equipment loss. This paper analyzes this phenomenon and has proposed an approach of correction.

In recent years, 66kV vertical TCR-type SVC was put into operation in several transformer substations at home. Compared to the compensation mode of the conventional 35kV SVC which is connected to 66kV busbar through by way of step-down transformer, the vertical compensation mode has the advantages of low loss and small maintenance amount. However, it is found that damage of phase controlled reactor in TCR happens in several scenes, and the technicians and research institutions studied this problem from such aspects as phase controlled reactor manufacturing process, SVC control strategy and natural environment of the transformer substations and obtained their own conclusions. This paper uses PSCAD software to conduct a simulation research on the 66kV vertical SVC system installed on a 220kV transformer substation at home and concluded that the SVC switching overvoltage might be the direct cause leading to damage of phase controlled reactor.

In recent 15 years, the study of complex networks has been gradually becoming an important issue. Community structure is an interesting property of complex networks. Researchers have made much exciting and important progress in community detection methods. The paper introduced the definition and significance of community structure; elaborates on the overview of community discovery algorithms and a proposed taxonomy according to the basic principle that they used. Modularity function was recommended briefly. Finally, described several popular test methods and benchmarks.

This paper examined the critical loading condition of a light sport aircrafts main landing gear during the impact loading condition. The new category airplane was established by the FAA in 2004. The light sport aircraft has great market demand for personnel entertainment purpose and regional transportation. The main object of this research was to establish a static and dynamic loading simulation model for the aluminum alloy landing gear of a light sport aircraft. This work also examined the critical loading parameters of the main landing gear, including the maximum take-off weight and maximum stall speed. The analysis was performed using ANSYS and LS-DYNA to establish the finite element model after simplifying the geometric characteristics and verifying the results by energy conservation, hourglass energy, and sliding energy. The study tested aluminum plates with a thickness from 15~25 mm. The results showed all the samples could sustain the required loading condition, except for the thickness of 15mm that failed under impact loading. The simulation model provides a cost-saving process compared to a real crashworthiness drop test to test the main landing gears compliance with regulations.

The training of the personnel in environmental art engineering design will be complete ultimately relying on the innovative course system of this program, and also the training model and teaching system have to meet the needs of modern social development, science and technology development, and employment market. However, environmental art design program based on science and technology features very strong practicality. In this paper, through analyzing the characteristics of environmental art design program and combining the concept of modern design education, a feasible model of practice teaching and the operation methods of professional project teaching oriented at studio are proposed, for the purpose of creating a practice environment in which design art personnel with subject characteristics can be trained.

For the development research for a new 8 step speed automatic transmission, a simplified dynamic model for this transmission was established. Aimed at four basic shift types, the ideal characteristics of shift clutch and engine control were set up. By using torque estimation method, PI slip control algorithm and engine coordinated control principle, the control model were developed for two main shift phases which are torque phase and inertia phase. The test on the rig and vehicle verified the accuracy and feasibility of this shift control strategy. The development model and algorithm have a high value for engineering application.

Problems such as low voltage and big line loss have long existing in the power grid in rural areas of China. In recent years, some province and cities have improved voltage and reduced line loss by installing SVG at substations in rural power grids, and the effect is remarkable.With great compensation capacity and a good variety of modes of compensation, SVG is sure to replace old reactive compensation devices in rural power grid in future, which requires evaluation and analysis of SVG reliability so as to guarantee safety and stability of the power grid. However, now no research or analysis has been made in China on SVG reliability in rural power grids, which affects wide promotion of SVG in rural power grids.Under the background of Liaoning Power Grid 10kV/±5Mvar Chain SVG, this paper analyzes the reliability of k/n (G) system model of SVG master circuit structure, improving the accuracy of system reliability estimation. The estimation matches the operation outcome, thus providing data basis for the feasibility of SVG’s wide application in rural power grid in future.

In a rural power grid 220kV transformer substation in Liaoning Province, because of the appearance of a lot of new impact loads in the power supply area, the original reactive power repertory can not meet the existing load need. As a result, the output 66kV voltage fluctuation affects the power supply security of the users. After a comprehensive evaluation, it is planned to set up a set of ±100M SVG to increase the reactive power repertory to stabilize the system voltage. The electrical system of 220kV transformer substation is huge and often meets with sudden failure; and the capacity of this set of SVG is large, so it may worsen the situation in case of improper control. This paper discusses several operational modes that SVG should have and designs a scheme that can be flexibly switched in several operational modes, which is specifically executed by an overall coordination module. This method has passed the preliminary field operation verification.

To improve the current non-linear optically coupled isolation amplifier and high power consumption, we designed a low-power, high-speed and high-linearity BiCMOS optically isolation amplifier. There are only two push-pull output stages configuration bipolar transistor (BJT) in the design process, the rest of the circuit is the CMOS device. To improve amplifier gain linearity and stability, we introduce the complementary symmetrical photodiode, in the optically coupled part and every amplifier, negative feedback is introduced. Experimental results indicate that the design of optically isolation amplifier ± 3 dB bandwidth increases 40 kHz than optically isolation amplifier ISO100 bipolar, When the power supply voltage is 4.8 V, the delay - power product of DP is lower than ISO100 37.3 pJ, gain linearity is up to 5.5 × 10-5, which is suitable for high-speed control system.

This paper describes the setup of a complex voltage ratio measurement system for the audio frequency range. A wideband two-channel digitizer and a differential analogue channel switching front-end are used as the heart of the system. The complex error, frequency response characteristics and short term stability of the system are tested in this paper. The errors range from 1×10-7at 50 Hz to 10×10-6at 200 kHz in ratio 1:1 test with 6 V input voltages. And errors are below ±8×10-7and ±0.06 μrad in ratio 1:1 test with a 4V power line (50 Hz) input voltage over 64 hours. The test results and comparisons between with and without channel exchange mode confirm the remarkable improvement regarding the suppression of the static mismatch errors of the digitizer and show the usefulness of the system at 50 Hz too.

The jet pipe electro-hydraulic servo valve is a typical two-stage flow control servo valve, its static and dynamic characteristics are analyzed in this paper. The interaction of the mechatronic and hydraulic system is considered by multidomain simulation tool, the all key parameters are tunable and this provides the optimal possibility to develop a high-performance jet pipe electro-hydraulic servo valve.

Objective To observe the therapeutic effect of attenuated Salmonella carrying siRNA-STAT3 plasmid on transplanted prostate cancer in mice, and investigate the mechanism of siRNA-STAT3 inducing apoptosis of prostate cancer cells in mice. Methods The transplanted prostate cancer models of mice were built, and then the mice were randomly divided into Mock group, pGC-Si-Scramble group and pGC-Si-STAT3 group. The general status of the mice was observed and the changes of tumor volume were recorded. The expression levels of mRNA and protein of STAT3 and its downstream genes such as Bcl-2, c-Myc, HIF-1, cyclinD1 were analyzed with RT-PCR and western blotting, and the apoptosis of tumor cells was detected with flow cytometry. Results Compared with the Mock group, the tumor weight and tumor volume in pGC-Si-STAT3 group were significantly decreased (PPPP

As the representative of 3G dynamic reactive compensation technology, the chain SVG voltage has advantages of high-grade and high compensation capacity which mainly owe to the structure that each phase of conversion chain consists of a plurality of H-bridges in cascade. Although the DC side capacitor is not the core device in H-bridge, it has the job of providing DC voltage source during H-bridge circuit conversion. DC side capacitance affect not only the operation reliability of chain SVG, but also equipment cost and operation loss, so it should be selected reasonably. This paper introduces the role DC side capacitor plays in H-BRIDGE. PSCAD is used for simulated contrast analysis of chain SVG with different capacitances, and raises the criteria for DC side capacitance selection. Finally, the correctness of the criteria is verified based on the actual operation data of the field equipment.