Abstract: A method for protecting a power system having inverter-interfaced renewable energy sources is provided. The power system includes an inverter and a control system. The control system includes a current controller including a saturation limiter and a proportional and integral (PI) controller, a phase-locked system, and a low-voltage ride-through (LVRT)control unit. The method includes: by using a Park transformation matrix, determining an output voltage of the inverter; determining a modulated voltage of the output voltage; upon detecting a grid fault, obtaining current references by the LVRT control unit; determining a fault current in a first stage of a transient phase of the grid fault; determining a fault current in a second stage of the transient phase; determining a fault current in a third stage of the transient phase; and switching the control system to a fault control mode by tracking the fault currents in the first, second and third stages, to the current references.

Abstract: A method and application of flash imaging lidar to measure the attenuation coefficient of water bodies are provided. In this novel method, the real time remote measurements are achieved on the attenuation coefficient of fresh water using flash imaging lidar based on the adjacent frame difference (AFD) method and water body backscattering model. The method solves the problems of low accuracy and high error of data obtained from real-time remote sensing measurement of attenuation coefficients of water bodies in the prior art; the slow speed of measurement data obtained when measuring water bodies, and the poor feasibility and reliability effect of the remotely measured attenuation coefficients of water bodies obtained. The experimental and theoretical analyses fully illustrate the feasibility of real-time remote sensing measurement of the attenuation coefficient of water bodies using the AFD method, which has a strong practical value.

Abstract: A pointer is rotational relative to the screen. A driver unit rotates the pointer. An imaging device detects an image of the pointer sends a signal of the image. A controller receives the signal of the image from the imaging device. The screen indicates a graphic. The controller modifies the graphic according to the signal of the image.

Abstract: A pointer is rotational relative to a screen. A driver unit is equipped with the pointer and configured to rotate the pointer. A controller sends an output signal to the driver unit to rotate the pointer at a rotational position in a rotational range. The controller is configured to modify the rotational range. The controller is configured to modify the graphic according to the rotational range, which is modified.

Abstract: A pointer is rotational relative to a screen. A driver unit is equipped with the pointer and configured to rotate the pointer. A controller sends an output signal to the driver unit to rotate the pointer at a rotational position in a rotational range. The controller is configured to modify the rotational range. The controller is configured to modify the graphic according to the rotational range, which is modified.

Abstract: A pointer is rotational relative to the screen. A driver unit rotates the pointer. An imaging device detects an image of the pointer sends a signal of the image. A controller receives the signal of the image from the imaging device. The screen indicates a graphic. The controller modifies the graphic according to the signal of the image.