A Constant-Pressure Hydraulic PTO System for a Wave Energy Converter Based on a Hydraulic Transformer and Multi-Chamber Cylinder

This paper presents a constant-pressure hydraulic PTO system that can convert stored pressure energy into electrical energy at a stable speed through hydraulic motors and generators. A multi-chamber cylinder can be connected to the main power generation circuit by check valves, and the motor displacement can be controlled by a fuzzy controller to maintain the main power generation circuit under stable pressure. The hydraulic transformer can control the forces applied to the floater. The hydrodynamic parameters of the floater are calculated by AQWA, and the optimal PTO damping of the hydraulic system is analyzed as the target of transformer control. MATLAB/Simulink and AMESim are used to carry out the co-simulation. Three kinds of wave elevation time-series for the specific state are designed for the simulation. In the co-simulation, three approaches are carried out for the simulation including no control strategy, fuzzy control with a fixed transformer ratio, and fuzzy control with a variable transformer ratio. Under the fuzzy control with a fixed transformer ratio, the floater displacement and captured energy do not increase significantly, but the oil pressure fluctuation is very stable, which indicates that the fuzzy controller maintains the stability of the main power circuit. While under fuzzy control with a variable transformer ratio, the power generation is not larger than those under no control strategy or fuzzy control with a fixed transformer ratio, which proves that this hydraulic transformer concept is less efficient.

1 X 1000 kVA Transformer Measurement Analysis using Dyn-11 Vector Group and Off Load Tap Changer

The transmission line of electrical energy generated by the power plant is usually located far from the load center to be distributed to the community. The substation is part of a distribution transmission line that acts as a control center and consists of a collection of extra high voltage equipment. Routine maintenance of the power transformer as the main equipment of the substation must be scheduled so that its performance remains reliable. The proposed method of this research is to analyze the condition of the transformer through testing when it is off, to the calculation of the transformer ratio to determine the condition of the transformer windings using the calculation of the formula and measurement of the Raytech Transformer Turn Ration measuring instrument. In this research, the Raytech Transformer Turn Ratio measurement tool is used to determine the ratio of the winding input voltage of 20,000 volts and the output voltage of 400 volts on the power transformer. At a voltage of 40VAC, from the results of the comparisons that have been made, it can be seen that the test results of the Raytech Transformer Turn Ratio measuring instrument, if it crosses the 0.5% tolerance limit, the measurement results on one of the coils change the ratio. If the transformer is not regularly checked, the impact will result in unbalance of voltage on one of the coils. And one of the coils in phase will expand and cause a loss of voltage.

WAKEFIELD EXCITATION BY A RAMPED ELECTRON BUNCH TRAIN IN A PLASMA-DIELECTRIC WAVEGUIDE

A linear theory of wakefield excitation by a ramped electron bunch train in a cylindrical plasma-dielectric waveguide is presented. It is shown that during an excitation process the drive bunches are in the focusing field due to the radial electric field excitation of the plasma wave. The possibility of both obtaining a high transformer ratio and focusing the drive and witness bunches is demonstrated.

Experimental Characteristics of Mechanical Continuously Variable Transmission with Internal Force Functions

The paper proposes a new type of a mechanical continuously variable transmission with internal force functions to upgrade the energy efficiency of a vehicle equipped with a conventional engine. The prototype of the transmission is a well-known V. F. Maltsev concurrent pulse variator in which freewheel mechanism driven members are supplemented with elastic torsions shafts. It is shown that the variator turns into a continuous transformer – a mechanical continuously variable transmission with internal force functions. There is an internal automaticity and continuity in the entire range of gear ratio changes. The configuration engineering solution is implemented in the engineering prototype. The aim of the research is experimental study of the properties and characteristics of such a mechanical continuously variable transmission. The kinematic configuration and the main structural dimensions of the engineering prototype are given. Special testing facility and measuring-and-recording equipment have been developed. A set of parameters to be recorded has been specified. The accuracy of their measurement is statistically estimated. The results of the experiments are presented in terms of output and input torque dependencies on the speed of the driven shaft. It is shown that the transmission characteristics in their dimensionless form (transformer ratio and efficiency) in the function of internal gear ratio are universal. The possibility of obtaining an infinite kinematic and significant power transmission ranges by independently changing the internal link oscillation range (level of the force function) and the rotation frequency of the drive shaft has been experimentally shown. The transmission has high transforming and energy properties, which are higher than those of hydrodynamic gears.

Electron trapping and acceleration in plasma wake field produced by an evolving hollow electron beam

In this article, the electron trapping and acceleration in the wake field driven by an ultrarelativistic hollow electron beam is studied. When the hollow driver injects into plasma, there is a doughnut-shaped electron bubble formed because of the existence of a special ‘backflow’ beam in the centre of the electron bubble. At the same time, there is a transverse convergence of the hollow driver, which leads to the weakening of the backflow beam. This results in a local electron density transition at the rear of the bubble. During this process, there is an expansion of the longitudinal electron bubble size, and a bunch of background electrons is trapped by the wake field at the rear of the bubble. The tracks for the trapped electrons show that there are two sources: one is from the bubble sheath and the other is from the unique backflow beam. In the particle-in-cell simulation where the driving beam has initial energy of $1.0$ GeV per particle, the trapped beam can be accelerated to energy of more than $1.5$ GeV per particle and the corresponding transformer ratio is $1.5$ . With the increase of driving beam energy up to $40.0$ GeV, a transformer ratio of $1.4$ still can be achieved. By adjusting the hollow beam density, it is possible to control the trapped beam charge value and beam quality, such as its energy spread and transverse emittance.

MAXIMUM TRANSFORMER RATIO AT WAKEFIELD EXCITATION AT BLOWOUT REGIME IN PLASMA BY ELECTRON BUNCH UNDER SEMI-GAUSSIAN CHARGE DISTRIBUTION

Using 2d3v code LCODE, the numerical simulation of nonlinear wakefield excitation in plasma by shaped relativistic electron bunch with charge distribution, which increases according to Gaussian charge distribution up to the maximum value, and then decreases sharply to zero, has been performed. Transformer ratio, as the ratio of the maximum accelerating field to the maximum decelerating field inside the bunch, and accelerating the wakefield have been investigated taking into account nonlinearity of the wakefield. The dependence of the transformer ratio and the maximum accelerating field on the length of the bunch was investigated with a constant charge of the bunch. It was taken into account that the length of the nonlinear wakefield increases with increasing length of the bunch. It is shown that the transformer ratio reaches its maximum value for a certain length of the bunch. The maximum value of the transformer ratio reaches six as due to the profiling of the bunch, and due to the nonlinearity of the wakefield.