A variable speed wind turbine employing a rotor (103) connected to a multiplicity of synchronous generators (106 - 112) with wound field or permanent magnet rotors. A passive rectifier (114 - 120) and an inverter (136 - 142) are used for power transfer back to the grid. A Turbine Control Unit (TCU) (132) commands a required generator torque based on rotor speed and power output of the turbine inverters. Torque is controlled by regulating the DC current by control of the inverter. A main-shaft-damping filter is provided by measurement of the DC bus voltage. In high winds the turbine remains at a constant average output power through a constant torque command and a varying pitch command to a rotor pitch servo system (102). A set point is fixed at the inverter output such that output VAR load is minimized running the turbine at very nearly unity power factor. Dynamic VAR and power factor control is provided by a separate VAR apparatus.

Variable speed distributed drive train wind turbine system

An electronic circuit, such as a UPS, interfaces a main ac power source and at least one secondary power source to a load. The secondary power source(s) may include one or more auxiliary generators, a flywheel motor generator or microturbine with high speed motor generator, and/or any of a variety of dc storage devices. The electronic circuit includes a dc bus, a first uncontrolled rectifier in combination with a first filter for coupling the main ac power supply to the dc bus, one or more additional uncontrolled rectifier(s) and filter(s) for coupling the auxiliary generator(s) to the dc bus, and a dc-to-ac inverter (between the dc bus and the load) for providing ac output power to the load. The advantages of reduced parts count, increased compatibility between the generator(s) and the electronic circuit, and a simpler method for paralleling many storage and generation devices with a very high power factor to the sources, regardless of the load power factor, are provided.

Uninterruptible power supply

An electronic interface couples a combination of generation and storage devices with a power grid and/or a load. The interface comprises a DC bus; a DC storage device coupled to the DC bus; a first DC-to-AC inverter (N1) having a DC port operatively coupled to the DC bus, and an AC port; a second DC-to-AC inverter (N2) having a DC port operatively coupled to the DC bus, and an AC port; a switch (S4) for electrically coupling the AC port of the second DC-to-AC inverter to a first generator or an AC storage device; a first rectifier (D1) for coupling an AC output of the first generator to the DC bus; and a second rectifier (D2) for coupling an AC output of the AC storage device to the DC bus. The electronic interface provides an efficient mechanism for integrating a variety of storage and generation devices to produce high quality power and reliability to a load as well as to facilitate interfacing of the storage and generation devices to the power grid for purposes of energy control, load leveling, and peak shaving.

Universal distributed-resource interface

A system and method for providing an uninterrupted supply of power to a critical load includes at least two uninterruptible power supply UPS modules that receive power from separate utility sources. A controller controls the UPS modules so that the output power from one UPS module is substantially in-phase with the output power from the other UPS module. As a result, the output powers from the UPS modules can be combined with one another to provide a sufficient source of uninterruptible power to the critical load regardless of the phase difference in the power provided by the separate utility sources.

System and method for providing an uninterruptible power supply to a critical load

A microturbine engine that includes a compressor that is operable to provide a flow of compressed air. The compressed air flows through a recuperator where it is preheated before delivery to a combustor. The preheated compressed air mixes with a fuel and is combusted within the combustor to provide a flow of products of combustion. The flow of products of combustion pass through one or more turbines to drive the compressor and a synchronous generator. The synchronous generator is able to synchronize to a priority load, to the utility grid or to both depending on the mode of operation. A control system monitors various engine parameters as well as load and grid parameters to determine the desired mode of operation.

Microturbine engine system

An UPS (uninterruptible power system) includes an UPS power conditioning unit that provides conditioned AC power to a critical load. The UPS power conditioning unit includes a variable speed drive that operates in response to AC utility power or to a standby DC input by providing a motor drive signal. The UPS power conditioning unit further includes a motor-generator that operates in response to the motor drive output by providing the conditioned AC power to the critical load. In response to an outage in the utility AC power, standby DC power is provided by a standby DC power source that includes a variable speed drive and a flywheel motor-generator connected to the variable speed drive. Both the UPS power conditioning unit and the standby DC power source are initially operated in response to the utility AC power, the flywheel motor-generator storing kinetic energy in a rotating flywheel. When an outage occurs, the rotating flywheel continues to operate the flywheel motor-generator of the standby DC power source, causing the production of AC power which is rectified and provided as standby DC power to operate the variable speed drive of the UPS power conditioning unit until either the utility AC power outage is over or a standby emergency generator is brought on line.

Uninterruptible power system with a flywheel-driven source of standby power

A power converter for converting shore power voltage, phase, and frequency for shipboard use includes a variable inductance input transformer that can be connected to the shore power. The primary windings of the transformer have a plurality of taps, and a respective computer-controlled switch is connected between adjacent taps to selectively establish a closed circuit or an open circuit between the taps and thereby configure the primary windings as a low or high voltage "delta" or "wye", as appropriate for the shore power voltage. The output of the input transformer is sent to a variable speed drive, then to an output transformer, and thence to the distribution bus of the ship. A voltage regulator regulates the output voltage of the output transformer. If desired, a phase selector can be provided between the shore power and input transformer to establish the phase characteristics (i.e., single, two-, or three-phase) of the power signal that is output by the input transformer, depending upon the phase characteristics of the shore power that is connected to the input transformer.

Richard N. Bowyer

Papers

Uninterruptible power system with a flywheel-driven source of standby power

Power converter for converting AC shore power to shipboard use