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With the growing of cable outlets in distribution network, the ground current increases quickly when single-phase ground fault occurs. Which results show single-phase ground fault protection mode selection becomes difficult. Based on interval analytic hierarchy process (IAHP), the comprehensive evaluation method for single-phase ground fault protection modes in cable network was researched. Indicators...
Due to the small fault current and unstable arc, the fault location problem of low power coal mine phase-to-ground fault has not got thoroughly solved. The existed leakage judging method of coal mine low voltage distribution network has the disadvantages of large error and long action time, so it is unfavorable for safety operation. This paper give a new methods which based on the model parameter...
Due to lack of test data, there is no numerical resistance model of mine communication cable now. Based on the simulation method, this paper uses the BT #0 model, modeling parameters of ordinary twisted-pair communication cables and the physical dimensions of the cables to validate the physically realizable model for the mine communication cables, and studies the resistance characteristics. The results...
Grounding insulation resistance detection is of great importance for the solar inverter. A novel scheme of grounding insulation resistance detection system based on switch-controlled bridge circuit for the solar inverter was proposed in the paper. By controlling the bridge circuit, linear equations in respect of insulation resistances can be established, and the values of insulation resistances can...
Along with the UHV construction scheme, China will form a large number of transmission lines which have the characteristics of the ultra-high voltage, large-capacity, longdistance. Because the UHV power grid transmission line parameters and the structure of the grid and the transformer are different from the other power net, Geomagnetic storms will affect the UHV power grid more, the work have important...
The winding of XLPE cable transformer is XLPE cable. In order to obtain the electrical characteristics of the XLPE cable transformer outer semiconductor layer, two XLPE cable with different length are used. The electrical resistances, capacitance at different frequency are measure. The study shown the resistance of outer semiconductor layer is about 0.095 Ω m and the capacitance of outer semiconductor...
Calculating additional losses of the transformer driven by load harmonics is very significant to economic, safe and efficient operation of transformer. Based on the transditional model of additional losses driven by load harmonics, the simplified model is put forward, as well as the calculation equation. According to the simplified model, a method to monitor the transformer harmonic losses online...
As the foundation of line loss management job, it is necessary to be researched deeply. At this stage, for low voltage distribution network loss calculation, mainly concentration was focused on the accuracy of the theoretical calculation basing the existing system parameters. As the simplicity of equivalent resistance method, it had a wide range of applications. But the influence of the line loss...
This paper describes the reutilization of paper sludge, a kind of industrial solid wastes, for preparation of a coal desulfurizer. Studies include experiments on paper sludge single component and paper sludge-fly ash composite components reusing as a coal desulfurizers. When the paper sludge used as a single component of the calcium-based coal desulfurizer, the desulfurization rate was more than 80%...
In view of on-line insulation detection requirements of ship's engine room automation equipment, which is not be attached attention usually, a kind of on-line insulation detection method based on ladder-shape signal injection is studied. To simplify the hardware configuration, the generator circuitry of injection signal and logical circuitry are designed based on CPLD, and then the insulation detection...
The penetration of distributed generation resources in distribution grids increasing worldwide, it is both a challenge and an opportunity for a variety of technologies and operating scenarios. The need to provide acceptable power quality and reliability will create a very favorable climate for the entry of distributed resources and innovative operating practices. Distributed resources is a term that...
Nonlinear programming is used to optimize the hull form of displacement type deep-vee vessels with bulbous bow in this paper. The total resistance is chosen as target function; the offsets of ship form are the optimizing variables; hull form displacement and variation range of offsets are used as restrictions. The effect of sailing pose was considered to calculate the total resistance, and the wave-making...
This thesis designs a new intelligent insulation measure instrument. Giving hardware and software design of the Power supply, Increased voltage, Multiple voltage, Sampling, Calculate and Display units. Discussing the problems and solutions in the measurement.
As the main transportation equipment for precooling system, water pump exists more energy consumption when operating in the traditional throttling mode. Put forward the variable frequency speed control strategy for energy-saving. The vector control variable frequency speed regulation model of the water pump motor is based on Fuzzy PI speed controller. The simulations experiment results show that the...
With the 500kV substations put into operation one after the other, the capacity and scale of 500kV autotransformer are more and more large. The single-phase short-circuit current at 220 kV buses of 500kV substations is higher than three-phase, the safe operation can't be satisfied. It can be controlled by adding small reactance at 500kV autotransformers from the operation experience of all over the...
The concept of numerical complete similarity ship model is present with the introduction of virtual fluid kinetic viscosity and virtual acceleration of gravity. This concept is verified by the total resistance calculation of the numerical complete similarity model with different length-to-breadth ratio and block coefficient. It is shown that, this complete similarity calculation method has well stability,...
There are different effects on the performance of paper by various drying methods, which determines whether the drying method is suitable to paper. In this thesis, the contrast test of drying rewetting paper was carried out by self-made electromagnetic dryer and electric dryer. The results have shown that there is no obvious effect on the whiteness and bursting strength of paper by electromagnetic...
Based on LabVIEW, the measurement system of I-V characteristics of solar energy is designed with a solar simulator, a Keithley 2400 Source Meter and a GPIB port. The system can quickly describe the I-V characteristic curves and calculate the basic characteristic parameters and focus on the analysis of the series resistance (Rs) and shunt resistance (Rsh). The results of the measurement demonstrate...
In the two-terminal fault location of the power transmission lines, In order to avoid the error of location result due to the impaction of system resistance, transition resistance and TA saturation and improve the accuracy of distance location, a new method of transmission line fault location which only depends on dual-voltage fault components is introduced in this paper. Basing on the linear superposition...
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