Abstract: Methods and systems for a synchronverter power control during unbalanced grid conditions is disclosed. The system includes a synchronverter coupled with a power supply grid, a power reference generator, configured to receive a terminal voltage measurement vector vt and a current measurement vector i from the synchronverter, and generate an active power Pf and a reactive power Qf, a synchronverter control unit connected to the power reference generator and configured to process the active power Pf and the reactive power Qf and generate an electromotive force (EMF) vector e, and an active and reactive power control unit, connected between the synchronverter control unit and the synchronverter, configured to receive the electromotive force (EMF) vector e and the terminal voltage measurement vector vt, and regulate the current measurement vector i to eliminate power oscillations and current harmonics in the synchronverter during unbalanced grid conditions.

Abstract: A method for correct operation of the current-angle-based phase-selection method (PSM) is based on a proper dual current controller (DCC) for inverter interfaced sources during unbalanced fault conditions. The fault type is determined in the inverter using voltage-angle-based PSM. Accordingly, fault-type zones' bisectors of the current-angle-based are determined. Consequently, an initial negative-sequence current angle reference is determined to force the relative angle between the negative- and zero-sequence currents in the center of its correct fault-type zone. The initial positive-sequence current angle is determined according to reactive current requirements by grid codes. These initial angles are updated for accurate operation of the PSM and appropriate reactive current injection. Negative- and positive-sequence current references are determined in the stationary frame to comply with the reference angles and inverter's thermal limits. These references are regulated by a proportional-resonance controller.

Abstract: A sensor detects tilt and/or accelerations simultaneously and in a plurality of directions. The exemplary sensor comprises a magnet which is allowed to move in multiple directions within a space about which a plurality of Hall-effect sensors are arrayed. The magnet is mounted by a plurality of springs which limit the displacement of the magnet to the space within the circle of sensors. Continuous signals from the sensors change in response to a changing position of the magnet. These signals are evaluated by an artificial neural network (ANN) taught using validated tilt sensors. Angle and acceleration values are cleaned from vibration values using a Kalman filter.

Abstract: A system for ultrasonic cleaning of a solar panel includes a plurality of microelectromechanical systems (MEMS) ultrasonic transducers arranged on a side wall of the solar panel and/or under transparent glass on a surface of the solar panel; a hydraulic sun tracking mechanism configured to move the solar panel into a plurality of positions; a valve connected to a water source; and a controller which controls the plurality MEMS ultrasonic transducers, the sun tracking mechanism, and the valve, wherein the controller is configured to activate a cleaning protocol comprising the steps of moving the solar panel into a substantially horizontal position; opening the valve to allow a water flow over the surface of the solar panel; activating the plurality of MEMS ultrasonic transducers to apply ultrasonic waves to the water on the surface of the solar panel, wherein signal interference from different transducers are controlled to generate a rotating focused ultrasound signal over the surface of the solar panel; and m

Abstract: A method for correct operation of the current-angle-based phase-selection method (PSM) is based on a proper dual current controller (DCC) for inverter interfaced sources during unbalanced fault conditions. The fault type is determined in the inverter using voltage-angle-based PSM. Accordingly, fault-type zones' bisectors of the current-angle-based are determined. Consequently, an initial negative-sequence current angle reference is determined to force the relative angle between the negative- and zero-sequence currents in the center of its correct fault-type zone. The initial positive-sequence current angle is determined according to reactive current requirements by grid codes. These initial angles are updated for accurate operation of the PSM and appropriate reactive current injection. Negative- and positive-sequence current references are determined in the stationary frame to comply with the reference angles and inverter's thermal limits. These references are regulated by a proportional-resonance controller.