A switch assembly including a switch and a high impedance element used for energy harvesting purposes that are connected to a power line at one end and assembly electronics at an opposite end, where in one non-limiting embodiment the switch assembly has particular application for use in connection with a vacuum interrupter. The high impedance element has higher impedance than the switch so that current flows through the switch from the power line when the switch is closed and through the high impedance element from the power line when the switch is open, where power from the high impedance element can power a switch closing device, such as a solenoid actuator. The high impedance element can be a resistive element, a capacitive element or a combination of a resistive and capacitive element.

A hydraulic fracturing system includes a turbine generator for producing electricity at a well site, the turbine generator producing electrical energy at a voltage. The system also includes an electric pump electrically coupled to the turbine generator and receiving operative power from the turbine generator. The system further includes switch gear arranged between the electric pump and the turbine generator, the switch gear distributing electrical energy from the turbine generator to the electric pump, wherein the voltage remains substantially constant from the turbine generator to the electric pump.

Provided is a method of supplying at least one component of a wind turbine with energy. The energy during operation of the wind turbine is taken from energy generated using a generator of the wind turbine and provided for supply to the at least one component of the wind turbine. Provided is an energy supply device for performing the method and a wind turbine having the energy supply device.

Provided is a method of supplying at least one component of a wind turbine with energy. The energy during operation of the wind turbine is taken from energy generated using a generator of the wind turbine and provided for supply to the at least one component of the wind turbine. Provided is an energy supply device for performing the method and a wind turbine having the energy supply device.

A hydraulic fracturing system includes a turbine generator for producing electricity at a well site, the turbine generator producing electrical energy at a voltage. The system also includes an electric pump electrically coupled to the turbine generator and receiving operative power from the turbine generator. The system further includes switch gear arranged between the electric pump and the turbine generator, the switch gear distributing electrical energy from the turbine generator to the electric pump, wherein the voltage remains substantially constant from the turbine generator to the electric pump.

A network of collection, charging and distribution machines collect, charge and distribute portable electrical energy storage devices. To charge, the machines employ electrical current from an external source. As demand at individual collection, charging and distribution machines increases or decreases relative to other collection, charging and distribution machines, a distribution management system initiates redistribution of portable electrical energy storage devices from one collection, charging and distribution machine to another collection, charging and distribution machine in an expeditious manner. Also, redeemable incentives are offered to users to return or exchange their portable electrical energy storage devices at selected collection, charging and distribution machines within the network to effect the redistribution.

A network of collection, charging and distribution machines collect, charge and distribute portable electrical energy storage devices. To charge, the machines employ electrical current from an external source. As demand at individual collection, charging and distribution machines increases or decreases relative to other collection, charging and distribution machines, a distribution management system initiates redistribution of portable electrical energy storage devices from one collection, charging and distribution machine to another collection, charging and distribution machine in an expeditious manner. Also, redeemable incentives are offered to users to return or exchange their portable electrical energy storage devices at selected collection, charging and distribution machines within the network to effect the redistribution.

A system includes a prime mover configured to rotate a shaft. The system also includes a wound rotor induction generator (WRIG). The WRIG includes a rotor coupled to the shaft of the prime mover and configured to rotate when the shaft rotates, where the rotor includes a rotor winding. The WRIG also includes a stator winding electrically connected to a utility source and a load. When the stator winding receives first power from the utility source, the WRIG is configured to transform at least one of a voltage and a frequency of the first power before outputting at least a portion of the first power to the load. When the stator winding does not receive the first power from the utility source, the WRIG is configured to generate second power due to kinetic energy of the rotor and output at least a portion of the second power to the load.

Disclosed is an apparatus including: a photovoltaic panel; a CPG controller configured to receive a limit output power value of a photovoltaic panel, a photovoltaic panel terminal voltage, and a photovoltaic panel output current and output a photovoltaic panel terminal voltage reference; a direct current (DC)-voltage controller configured to receive the photovoltaic panel terminal voltage reference and the photovoltaic panel terminal voltage and output a duty ratio to cause an error between these values to become zero; a pulse width modulation (PWM) control signal generator configured to receive the duty ratio and output a PWM signal to control a DC/DC converter connected to the photovoltaic panel; the DC/DC converter configured to receive the PWM signals and perform CPG control; and a DC/AC inverter connected to the DC/DC converter and configured to convert DC power into AC power and output the AC power to an electrical grid.

Disclosed is an apparatus including: a photovoltaic panel; a CPG controller configured to receive a limit output power value of a photovoltaic panel, a photovoltaic panel terminal voltage, and a photovoltaic panel output current and output a photovoltaic panel terminal voltage reference; a direct current (DC)-voltage controller configured to receive the photovoltaic panel terminal voltage reference and the photovoltaic panel terminal voltage and output a duty ratio to cause an error between these values to become zero; a pulse width modulation (PWM) control signal generator configured to receive the duty ratio and output a PWM signal to control a DC/DC converter connected to the photovoltaic panel; the DC/DC converter configured to receive the PWM signals and perform CPG control; and a DC/AC inverter connected to the DC/DC converter and configured to convert DC power into AC power and output the AC power to an electrical grid.