Abstract: Methods, systems, and apparatus, including computer programs stored on a computer-readable storage medium, for obtaining, from an electric field sensor, measurements of a net electric field resulting from a combination of respective electric fields from two or more electrical power conductors that are proximate to the electric field sensor. The apparatus detects a change in successive measurements of the net electric field. The apparatus determines, based on the change, that an electrical fault has occurred in one of the two or more electric power conductors. The apparatus sends to a server system, data indicating that the electrical fault has occurred in one of the two or more electric power conductors.

Abstract: Methods, systems, and apparatus, including computer programs stored on a computer-readable storage medium, for obtaining a reference phase signal that is synchronized with an alternating current (AC) phase of a multi-phase electrical power distribution system. The apparatus obtains output signals from sensors, each output signal representative of an electromagnetic emission detected by a respective sensor. The apparatus identifies, based on comparing respective phases of the output signals to the reference phase signal, a particular AC phase of the multi-phase electrical power distribution system associated with a source of the emissions. The apparatus provides an indication of the particular AC phase to a user.

Abstract: Methods, systems, and apparatus, including computer programs stored on a computer-readable storage medium, for obtaining, from an electric field sensor, measurements of a net electric field resulting from a combination of respective electric fields from two or more electrical power conductors that are proximate to the electric field sensor. The apparatus detects a change in successive measurements of the net electric field. The apparatus determines, based on the change, that an electrical fault has occurred in one of the two or more electric power conductors. The apparatus sends to a server system, data indicating that the electrical fault has occurred in one of the two or more electric power conductors.

Abstract: Methods, systems, and apparatus for an infrared and visible imaging system. In some implementations, Image data from a visible-light camera is obtained. A position of a device is determined based at least in part on the image data from the visible-light camera. An infrared camera is positioned so that the device is in a field of view of the infrared camera, with the field of view of the infrared camera being narrower than the field of view of the visible-light camera. Infrared image data from the infrared camera that includes regions representing the device is obtained. Infrared image data from the infrared camera that represents the device is recorded. Position data is also recorded that indicates the location and pose of the infrared camera when the infrared image data is acquired by the infrared camera.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for performing vegetation management processes. The processes can include obtaining first data identifying vegetation growth proximate to utility lines. The processes can include identifying a set of trees as being likely to interfere with a respective utility line near the tree. The processes can include determining, for each tree in the set of trees, an impact score that indicates a severity of a power outage that would be caused by interference of the tree with a power line. The processes can include selecting, based on the impact scores, individual trees to be trimmed. The processes can include generating trimming data that includes the location of the tree on a graphical map, and providing the trimming data for display on the one or more computing devices.

Abstract: Methods, systems, and apparatus, including computer programs stored on a computer-readable storage medium, for obtaining a reference phase signal that is synchronized with an alternating current (AC) phase of a multi-phase electrical power distribution system. The apparatus obtains output signals from sensors, each output signal representative of an electromagnetic emission detected by a respective sensor. The apparatus identifies, based on comparing respective phases of the output signals to the reference phase signal, a particular AC phase of the multi-phase electrical power distribution system associated with a source of the emissions. The apparatus provides an indication of the particular AC phase to a user.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for generating a representation of an electric power grid. One of the methods includes obtaining respective datasets, identifying one or more predictive models for each of the respective datasets that are each configured to processes a category of data to generate an output that specifies a partial representation of the electric power grid; and aggregating the respective outputs in accordance with a set of predetermined rules to generate a final representation of the electric power grid.

Abstract: Methods, systems, and apparatus for an infrared and visible imaging system. In some implementations, Image data from a visible-light camera is obtained. A position of a device is determined based at least in part on the image data from the visible-light camera. An infrared camera is positioned so that the device is in a field of view of the infrared camera, with the field of view of the infrared camera being narrower than the field of view of the visible-light camera. Infrared image data from the infrared camera that includes regions representing the device is obtained. Infrared image data from the infrared camera that represents the device is recorded. Position data is also recorded that indicates the location and pose of the infrared camera when the infrared image data is acquired by the infrared camera.

Abstract: Methods, systems, and apparatus, including computer programs stored on a computer-readable storage medium, for obtaining a reference phase signal that is synchronized with an alternating current (AC) phase of a multi-phase electrical power distribution system. The apparatus obtains output signals from sensors, each output signal representative of an electromagnetic emission detected by a respective sensor. The apparatus identifies, based on comparing respective phases of the output signals to the reference phase signal, a particular AC phase of the multi-phase electrical power distribution system associated with a source of the emissions. The apparatus provides an indication of the particular AC phase to a user.

Abstract: A compound motor-generator system including a first motor-generator and a second motor-generator. The first motor generator includes a stator having a set of three-phase field windings and a first rotor disposed inside and coaxial with the stator and configured to rotate relative to the stator. The second motor-generator includes a rotational stator and a second rotor coupled to a common shaft with the rotor of the first motor-generator and disposed inside and coaxial to the rotational stator. The rotational stator is configured to rotate relative to the second rotor and at a higher rotational speed than the second rotor.

Abstract: Methods, systems, and apparatus for an infrared and visible imaging system. In some implementations, Image data from a visible-light camera is obtained. A position of a device is determined based at least in part on the image data from the visible-light camera. An infrared camera is positioned so that the device is in a field of view of the infrared camera, with the field of view of the infrared camera being narrower than the field of view of the visible-light camera. Infrared image data from the infrared camera that includes regions representing the device is obtained. Infrared image data from the infrared camera that represents the device is recorded. Position data is also recorded that indicates the location and pose of the infrared camera when the infrared image data is acquired by the infrared camera.

Abstract: Methods, systems, and apparatus, including computer programs stored on a computer-readable storage medium, for obtaining, from an electric field sensor, measurements of a net electric field resulting from a combination of respective electric fields from two or more electrical power conductors that are proximate to the electric field sensor. The apparatus detects a change in successive measurements of the net electric field. The apparatus determines, based on the change, that an electrical fault has occurred in one of the two or more electric power conductors. The apparatus sends to a server system, data indicating that the electrical fault has occurred in one of the two or more electric power conductors.

Abstract: While motors or generators stacked in series may allow for higher operating voltages, such motors or generators may also exhibit instability. To minimize instability, the motors or generators may be controlled to have an approximately equal current. An example motor system may include motor stacks connected in series, each motor stack exhibiting a respective stack voltage and a respective differential power (based on a difference in power between motors in the motor stack). A control system may average the stack voltages to generate an average stack voltage and generate a nominal stack power corresponding to each stack voltage. The control system may receive the differential powers, combine each differential power and nominal stack power for the respective motor stack to generate first and a second motor powers, and control each motor stack using the first and second motor powers.

Abstract: A power distribution system includes at least a ground power unit, an aerial vehicle, and a power station. The ground power unit is configured to convert an input AC power into DC power output, wherein the ground power unit includes at least a first bus, second bus, and a third bus, wherein the first bus is configured to operate at a first voltage level referenced to the third bus, and wherein the second bus is configured to operate at a second voltage level referenced to the third bus that is different from the first voltage level. The aerial vehicle may include a plurality of motor-generators coupled to a respective plurality of turbines, wherein the plurality of motor-generators may be configured to be energized by power received from a tether.

Abstract: A power distribution system includes a bidirectional power converter, a battery, and a controller. The bidirectional power converter is operable to (i) convert AC power received at AC terminals to DC power at DC terminals and (ii) convert DC power received at the DC terminals to AC power at the AC terminals. The bidirectional power converter is disposed within a converter stack formed by a plurality of power converters having DC terminals that are coupled to each other in series. The battery is arranged to be selectively couplable to the DC terminals of the bidirectional power converter. The controller is configured to (i) determine that the DC voltage across the DC terminals of the bidirectional power converter is below a threshold voltage and (ii) couple the battery to the DC terminals of the bidirectional power converter based on the determination that the DC voltage is below the threshold voltage.

Abstract: A photo-voltaic (PV) power generating system and a control system for PV array string-level control and PV modules serially-connected into strings of PV modules. The system includes plural parallel strings of serially-connected powergenerating photovoltaic modules that form a PV array, DC/DC micro-converters that are coupled to a DC voltage buss and to the output of a corresponding photovoltaic module or to the output of a string of photovoltaic modules; a gating or central inverter; and a control system. The micro-converters are structured and arranged to include at least one of: an active clamp device, a ground fault detection device, and a fractional power converter that injects power in series or in parallel with voltage or current from the power-generating portion onto the DC buss.

Abstract: While motors or generators stacked in series may allow for higher operating voltages, such motors or generators may also exhibit instability. To minimize instability, the motors or generators may be controlled to have an approximately equal current. An example motor system may include motor stacks connected in series, each motor stack exhibiting a respective stack voltage and a respective differential power (based on a difference in power between motors in the motor stack). A control system may average the stack voltages to generate an average stack voltage and generate a nominal stack power corresponding to each stack voltage. The control system may receive the differential powers, combine each differential power and nominal stack power for the respective motor stack to generate first and a second motor powers, and control each motor stack using the first and second motor powers.

Abstract: Disclosed are systems and rotor/stator assemblies with improved electrical isolation. An example rotor/stator assembly may include a rotor, a rotor housing, a rotor insulator, a stator, a stator plate, and a stator insulator. The rotor may be electrically isolated from the rotor housing by the rotor insulator, and the stator may be electrically isolated from the stator plate by the stator insulator. The stator may be disposed coaxial to the rotor. The rotor/stator assembly may function as a motor, and the stator may be configured to cause the rotor to rotate about the stator in response to an input of electrical energy to the stator. Alternatively or additionally, the rotor/stator may function as an electrical generator. The rotor may be configured to rotate about the stator, and the stator may be configured to produce electrical energy in response to rotation of the rotor relative to the stator.

Abstract: While motors or generators stacked in series may allow for higher operating voltages, such motors or generators may also exhibit instability. To minimize instability, the motors or generators may be controlled to have an approximately equal current. An example motor system may include motor stacks connected in series, each motor stack exhibiting a respective stack voltage and a respective differential power (based on a difference in power between motors in the motor stack). A control system may average the stack voltages to generate an average stack voltage and generate a nominal stack power corresponding to each stack voltage. The control system may receive the differential powers, combine each differential power and nominal stack power for the respective motor stack to generate first and a second motor powers, and control each motor stack using the first and second motor powers.

Abstract: While motors or generators stacked in series may allow for higher operating voltages, such motors or generators may also exhibit instability. To minimize instability, the motors or generators may be controlled to have an approximately equal current. An example motor system may include motor stacks connected in series, each motor stack exhibiting a respective stack voltage and a respective differential power (based on a difference in power between motors in the motor stack). A control system may average the stack voltages to generate an average stack voltage and generate a nominal stack power corresponding to each stack voltage. The control system may receive the differential powers, combine each differential power and nominal stack power for the respective motor stack to generate first and a second motor powers, and control each motor stack using the first and second motor powers.