Abstract: A method and apparatus provide an improved way to monitor a circuit for deterioration and obtain an advance warning of the deterioration so that action can be taken before the circuit breaker may trip for the circuit. The method establishes a baseline for the circuit, including monitoring the zero crossing point for the voltage and current for the circuit. In operation, the circuit is monitored using the zero crossing point and this information is compared to the baseline to determine if a change has occurred. The baseline information establishes thresholds that signify that the circuit is deteriorating so that the appropriate signal can be provided so that an appropriate action can be taken, interrupt the circuit, take remedial action, etc.

Abstract: A system for testing a transformer includes a voltage source configured to apply an input voltage to a secondary winding of the transformer, the input voltage is configured to induce a voltage in a primary winding of the transformer. A primary voltmeter is configured to measure the induced voltage in the primary winding, a plurality of secondary voltmeters configured to measure voltage in a plurality of secondary windings of the transformer, and one or more phase angle meters to simultaneously measure a plurality of phase angles between the primary voltage and each of the plurality of secondary voltages. A controller is connected to the voltage source, the primary voltmeter, the plurality of secondary voltmeters, and the one or more phase angle meters, the controller is configured to calculate a plurality of winding ratios based on the voltage and phase angle measurements, the controller is also configured to identify all secondary taps.

Abstract: A voltage regulation device includes: an input node configured to receive electrical power from an electrical power source; a primary winding electrically connected to the input node; an output node configured to provide electrical power to a load; a shunt winding electrically connected to the output node; a converter configured to provide a compensation current to the shunt winding; and a control system configured to: determine a harmonic compensation signal based on harmonic frequency data; determine a reactive power compensation signal based on a reactive power set point; and control the converter based on the determined harmonic compensation signal and the determined reactive power compensation signal to produce the output compensation signal. The output compensation signal is configured to reduce the one or more harmonic frequency components in a current that flows in the output node and to control an amount of reactive power at the output node.

Abstract: An intelligent impedance injection module is for use with transmission lines in a power grid. The intelligent impedance injection module has a plurality of transformer-less impedance injector units and a controller. The controller changes injector gain of the impedance injector units to compensate for current swings in a transmission line.

Abstract: A longitudinal voltage regulator includes: a voltage source for generating an additional voltage; and a transformer for coupling the additional voltage into an input voltage. The transformer both generates the additional voltage and couples the additional voltage into the input voltage. In an embodiment, the transformer has an input winding and an output winding.

Abstract: A multi-phase transformer. The multi-phase transformer includes a single rectifier; and a plurality of groups of windings connected to the single rectifier. Each one of the plurality of groups of windings comprises: a corresponding plurality of primary windings having a first output voltage; a corresponding plurality of secondary windings having a second output voltage; and a corresponding plurality of tertiary windings having a third output voltage that is higher than the second output voltage.

Abstract: A device includes a three phase supply input including a first phase input, a second phase input, and a third phase input. The device further includes a three phase supply output including a first phase output, a second phase output, and a third phase output. The device further includes a three-phase wye-connected auto-transformer having windings including a first winding, a second winding, and a third winding. At least one of the windings is rated for at least a maximum line to line voltage of the three phase supply input. The other two windings are rated for at least a maximum line to neutral voltage of the three phase supply input. One or more of the windings of the three-phase wye-connected auto-transformer are configured to be tapped to generate a voltage sag output as the three phase supply output.

Abstract: A resonant wireless power reception apparatus includes a wireless near field communication (NFC) antenna for performing an NFC function through an NFC frequency band, a resonator for receiving resonant wireless power using a resonance frequency different from the NFC frequency band, the resonator being installed adjacent to the NFC antenna, and a high impedance circuit for filtering a signal having the NFC frequency band provided from the NFC antenna, the high impedance circuit being connected to the resonator.

Abstract: Converting a single phase power supply source into a three phase power supply source is carried out by using the single phase power supply source as a first output of the three phase power supply source. The second and third outputs of the three phase power supply source are created utilizing part of the single phase power supply source combined with a phase shifting inverting circuit.

Abstract: It is provided a mechanical bypass switch device arranged to bypass a converter cell in a power converter. The mechanical bypass switch device includes: a mechanical switch; a mechanical switch actuator arranged to make the mechanical switch conduct when supplied with an electric signal; a first control input; and a second control input. The mechanical bypass switch device is arranged such that a control signal, provided on either one of the first control input and the second control input or on both of the first control input and the second control input, causes the mechanical switch to conduct. A corresponding converter arm and bypass converter are also presented.

Abstract: A power converter that interfaces a motor requiring variable voltage/frequency to a supply network providing a nominally fixed voltage/frequency includes a first rectifier/inverter connected to a stator and a second rectifier/inverter. Both rectifier/inverters are interconnected by a dc link and include switching devices. A filter is connected between the second rectifier/inverter and the network. A first controller for the first rectifier/inverter uses a dc link voltage demand signal indicative of a desired dc link voltage to control the switching devices of the first rectifier/inverter. A second controller for the second rectifier/inverter uses a power demand signal indicative of the level of power to be transferred to the dc link from the network through the second rectifier/inverter, and a voltage demand signal indicative of the voltage to be achieved at network terminals of the filter to control the switching devices of the second rectifier/inverter.

Abstract: The present invention provides methods and apparatus for converting a single phase power supply source into a three phase power supply source. The single phase power supply source is utilised as a first output of the three phase power supply source, whilst the second and third outputs of the three phase power supply source are created utilising part of the single phase power supply source combined with a phase shifting inverting circuit.

Abstract: A sequence of series-connected transformers for transmitting power to high voltages incorporates an applied voltage distribution to maintain each transformer in the sequence below its withstanding voltage.

Abstract: An apparatus (14/18) for controlling a voltage on a transmission line (10). The apparatus (14/18) comprises a first voltage sourced converter controller (18) connected to a first node (22) of the transmission line (10); a second voltage sourced converter controller (14) connected to a second node (20) of the transmission line (10), the second node (20) spaced apart from the first node (22) wherein the first voltage sourced converter controller (18) supplies capacitive reactive current and the second voltage sourced converter controller (14) absorbs inductive reactive current to control the voltage.

Abstract: A method, system, and computer program product for selecting a transformer size for an industrial or commercial facility. A plurality of end-use connected load data for the facility is entered via a user interface into a memory of a computing system for determining facility load diversities. A base homogeneity is determined for the end-use connected load data. An initial facility diversity is determined based on the end-use connected loads and initial end-use diversities. A total facility diversity is determined based on the initial facility diversity, the base homogeneity, and a total connected load. An expected energy demand is determined based on the total facility diversity and a total connected load. The end-use diversity is adjusted for at least one end-use and a change in expected energy demand for the facility is allocated to each end-use. The transformer size is determined for a total expected energy demand and a total hours use for each connected load.

Abstract: A phase-controlled power supply is disclosed. The power supply includes a power conditioner with an input configured to connect to an external source of electrical power, the power conditioner being configured to provide conditioned power on its output. The power supply also includes a transformer having a primary winding and a secondary winding, and a switching module coupled between the output of the power conditioner and to the primary winding of the transformer. The switching module has two modes of operation and a control signal input configured to accept a first control signal. The switching module includes a switching element configured to connect the power conditioner output to the primary winding of the transformer. The switching module operates in the first mode when the first control signal is in a first state, switching the first switching element at a first frequency and first duty cycle.

Abstract: A power control method using AC power, the method being capable of performing: low power control that passes only two portions of positive direction waves of each one-cycle sine wave of the AC power and only two portions of negative direction waves of each one-cycle sine wave of the AC power, which have voltage levels lower than a set reference voltage level, through a system; and high power control that does not pass only two portions of positive direction waves of each one-cycle sine wave of the AC power and only two portions of negative direction waves of each one-cycle sine wave of the AC power, which have voltage levels lower than a set reference voltage level, through the system.

Abstract: Which permits the application of methods for increasing the performance of a communications system on a medium made up of N conductors (51-5N) and a reference plane (6) by means of injecting voltage signals (41-4N) in up to N combinations of the conductors, including injection in common mode, such that said injected signals can be made to be orthogonal to each other.

Abstract: Apparatus for controlling the voltage supplied to a load, comprising: a multi-phase transformer having a primary and a secondary winding for each phase, each secondary being connected in series between an input line and an output directed to the load; and the primary is configurable by switches such that the phase of the voltage of the secondary is different from the line to which it is connected by a phase different from 0 and 180 degrees.

Abstract: A method for controlling the power flow in an ac transmission line including prompt handling of voltage recovery and only thereafter thermal constraints.

Abstract: A multi-transformer unit is operative for converting an input AC voltage at a first voltage level to a net output AC voltage at a second voltage level. The multi-transformer unit can be used in place of a conventional transformer or an AC machine and is designed to suppress the transfer of harmonics between the input and output AC voltages. The unit comprises at least two phase-shifting transformers, each transformer being operative to provide a phase shift relative to the first voltage level. On the primary side of the unit the transformers are arranged for independent connection to the first voltage level, whereas on the secondary side of the unit the transformers are linked such that voltage vectors on the secondary side of the unit are added together to at least partially cancel the harmonic pollution and give the net output AC voltage.

Abstract: A power subsystem including a mechanism for satisfying a predetermined power limit in a computer system. The power subsystem may include a split power supply and a voltage regulator. The split power supply may include at least a first voltage supply line and a second voltage supply line. The voltage supply lines may be closely matched voltage sources, each configured to provide relatively the same voltage amount. The voltage regulator may step-down a voltage provided by each of the first and second voltage supply lines to generate a desired voltage for a load. The first voltage supply line may be isolated from the second voltage supply line to limit power provided through either the first or the second voltage supply line from exceeding a predetermined power limit. The predetermined power limit may be a power limit set by U.L. standard #60950, i.e., 250 Watts.

Abstract: A ring balancer comprising a plurality of balancing transformers facilitates current sharing in a multi-lamp backlight system. The balancing transformers have respective primary windings separately coupled in series with designated lamps and have respective secondary windings coupled together in a closed loop. The secondary windings conduct a common current and the respective primary windings conduct proportional currents to balance currents among the lamps. The ring balancer facilitates automatic lamp striking and the lamps can be advantageously driven by a common voltage source.

Abstract: A phacoemulsification system includes a phacoemulsification handpiece including a cutting tip ultrasonically vibrated by an ultrasonic transducer. A power supply is provided for driving the ultrasonic transducer at a resonant frequency of the transducer and cutting tip and varying power to the transducer, in response to loading of the cutting tip, by phase shifting drive signals to the resonant converter which supplies power to the transducer.

Abstract: A system and method for an autotransformer configuration including a plurality of windings which can be used to provide a substantial reduction in harmonics. The autotransformer includes a series of wye windings configured to provide a constant length voltage vector for any given input voltage, and a series of delta windings having a variable length voltage vector based upon turns ratio. The delta winding circuit is electrically coupled with the wye winding circuit to allow circulation of triplen harmonics, thereby reducing the effect on input current waveform such that total harmonic distortion (THD) is reduced, and producing an equivalent kVA rating that is lower than prior art applications, which results in savings in size, weight and cost.

Abstract: A diode system and a generator, uses Zener diodes. The diode system has AC voltage terminals and DC voltage terminals, in which the Zener diodes are operable in the forward direction to rectify an AC voltage present at the AC voltage terminals, in which a lower limit is provided for the Zener voltage of the Zener diodes, and in which the lower limit of the Zener voltage is provided so that it is lower than a preset lower DC voltage.

Abstract: A power adjustment apparatus includes a phase shifter including a stator having a stator winding and a rotor having a rotor winding, a winding terminal of one of the stator winding and the rotor winding being connected to a power-system bus, and a winding terminal of the other being connected to the power-system bus via an impedance load, a driver axially coupled to the rotor to drive the rotor, and a controller which gives the driver a command value to adjust the phase difference between the stator and the rotor to a desired value.

Abstract: A method of controlling connection of a transformer of an electric vehicle, such as a train locomotive, to an alternating voltage supply carried by a trolley wire, the object being to reduce the transformer inrush current on connection of the transformer to the supply. Movement of a pantograph of the vehicle is judiciously controlled from its lowered position to a raised position so that as the pantograph approaches the trolley wire an arc bridges the air gap between them to consistently connect the electrical transformer of the vehicle to the trolley wire when the voltage present on the wire is at or near its peak.

Abstract: An electrical AC-DC power conversion system featuring 18-pulse rectification and utilizing a low weight wye-connected phase shifting autotransformer (500) supplied from a 3-phase AC source (40) through a 3-phase line reactor (41). The current harmonic distortion is less that 5% and can be further reduced to 3% level by the use of additional suppression devices (eg., chokes) which are often required in aerospace applications. The transformer (500) includes three sections (501) each spaced 120° electrically apart, wherein each section (501) includes a main winding (510) and a pair of phase shift windings (540). The main winding (510) has a neutral end connected to a floating neutral point (502) and a source end (514) is connected to one phase (1, 2, 3) of the three-phase power source (40). The pair of phase shift windings (540) each include a second winding (520) and a third winding (530) connected in series and arranged to generate phase outputs (4-9) of the autotransformer (500).

Abstract: A power flow transformer implements power flow control in a transmission line of an n-phase power transmission system, where each phase of the power transmission system has a transmission voltage. The transformer has n secondary windings, where each secondary winding is on a core. The transformer also has n primary windings on the core of each secondary winding for a total of n2 primary windings, where one primary winding from each core is assigned to each phase. For each phase, the primary windings assigned to the phase are coupled in series, and the in-series primary windings receive the transmission voltage of the respective phase of the power transmission system. For each core, each primary winding thereon induces a voltage in the secondary thereon. The induced voltages are summed by the secondary to result in a summed induced voltage. Such summed induced voltage is a compensating voltage for a respective phase.

Abstract: In a power feeding apparatus having pickup coils L1 and L2, a rectifier circuit 4 and output terminals U and V, the relays R1 and R2 are connected between the output side terminals of the rectifier circuit 4 and the output terminals U and V Whereas a protective circuit (switching control circuit) 6, which is connected to the pickup coils L1 and L2 and the relay coils r1 and r2 to obtain the electric power from the output side terminals of the rectifier circuit 4 in order to carry out ON/OFF control of the relays R1 and R2 corresponding to the voltage at the both ends of the pickup coils L1 and L2, is provide. The power feeding apparatus enables to prevent an overcurrent from flowing through a load, to prevent the circuit elements from being destroyed or burnt out due to an overcurrent generated in the pickup coils or an overvoltage generated in a resonance capacitor, to indicate an occurrence of an abnormality and to control the electric power supply by means of a remote control.

Abstract: In a DC/DC converter including a half-wave rectifying circuit of a diode and a capacitor for rectifying a voltage occurring on a secondary side of an insulated transformer, an ON period of one of switch elements has a fixed duration, permitting control of an ON period of the other switch element in order to achieve a constant DC output voltage. Since the switching frequency varies only during the ON period of the controlled switch element, an increase in switching frequency is restrained during a period in which the circuit carries light loads.

Abstract: The invention relates to a circuit for transforming, switching, adjusting or controlling electric power, comprising an electric source 1, a load 2, and a device 3 for transforming, switching, adjusting or controlling the electric power resulting on the load 2. To reduce the losses, it is provided that the device 3 is formed by at least one transformer 10, 10′, whose secondary side overlays the source 1 and whose primary side is connected with a control device 11, whereby at certain points of time and for certain periods of time, a voltage or a current can be produced at the primary side of the transformer 10, 10′, which voltage or current induces a voltage or a current, respectively, at the secondary side of the transformer 10, 10′, which voltage or current, respectively, is equal to the voltage or current, respectively, of the source 1 at this point of time and for that period of time.

Abstract: A drive circuit arrangement for a gas discharge lamp includes a) a self resonating inverting for providing a drive voltage across a load impedance, the inverter having a pair of field effect transistors which operate in anti-phase, b) a tank circuit for canceling the reactive component of the load impedance coupled to the inverter, c) a voltage division circuit which provides a given fraction of the drive voltage to the gates of the field effect transistors, and d) a phase shifting means comprising an inductance in series with the tank circuit for shifting the phase of the given fraction of the drive voltage. The voltage division circuit is provided with a voltage limiter which in operation provides a further phase shift to the given fraction of the drive voltage when the drive voltage exceeds a given threshold value, increasing the resonant frequency of the inverter and limiting the peak drive voltage.

Abstract: Autotransformer design which is capable of modifying the active power flow in autotransformers connecting two different voltage systems in an electrical substation. The bus-tie autotransformers presented change the active power flow by modifying the phase-angle between the primary and secondary voltages of the autotransformer. In accordance with the two tap changers are employed allowing for independent changes in both the voltage ratio and the phase-angle values.

Abstract: The present invention discloses a method for providing balanced power to a single-phase ac load from a three-phase ac power source. The method includes imposing an isolation power transformer between the ac power source and the load wherein the isolation transformer has a three-phase primary winding and a six-phase "wye" connected secondary winding, at least one of the three legs of the secondary having a center tap and being connected to the load such that the center tap provides a reference potential for the load and the reactive load currents are equal and inversely-phased with respect to the reference potential.

Abstract: In an interconnection system (100) for transferring power between a first grid (22) operating at a first electrical frequency and voltage and a second grid (24) operating at a second electrical frequency and voltage, compensation circuits including a shunt compensation circuit (40) and a series compensation circuit (50) are provided for use in conjunction with a rotary transformer (102). The shunt compensation circuit (40) regulates voltage by adjusting reactive current injected in shunt, and is preferably connected between the first grid (22) and the rotary transformer (102). The series compensation circuit (50), which regulates e.g., reactive power flow through the rotary transformer (102), is preferably connected to a transformer (30) which interfaces the first grid (22) to the rotary transformer (102).

Abstract: A neutral conductor filter having three transformers. A first transformer has a primary winding connected to a first power conductor and the neutral conductor. A second transformer has a primary winding connected to a second power conductor and the neutral conductor. A third transformer has a primary winding connected to a third power conductor and the neutral conductor. The secondary windings of the transformers are connected in series with each other and a capacitor is connected in parallel with the series connected secondary windings. The capacitor is tuned with the leakage reactance of the transformers so that the impedance to zero-sequence third harmonic current is minimized.

Abstract: A power flow controller seeks to inject a voltage V.sub.ser on a transmission path between a first electrical area and a second electrical area, in order to cause a desired power flow into the second electrical area. The power flow controller (20) includes a series transformer (40), a regulating transformer (44), a rotary phase shifting transformer network (44), and a control system (46). The rotary phase shifting transformer network (44) includes a first rotary phase shifting transformer (102.sub.1) and a second rotary phase shifting transformer (102.sub.2). The first rotary phase shifting transformer and the second rotary phase shifting transformer have first terminals (windings of one of either rotors or stators) connected in parallel to a regulating winding 62) of the regulation transformer. Second terminals (windings of the other of rotors or stators) are connected in series with an excited winding (52) of the series transformer.

Abstract: A method and apparatus for controlling power transferred and regulating voltage in a multi-phase transmission line includes generating a first plurality of voltages, a second plurality of voltages displaced in phase from the first plurality of voltages, and a third plurality of voltages displaced in phase from the first and second plurality of voltages. The first, second and third plurality of voltages are selectively connected in series in each line of the multi-phase transmission line.

Abstract: A method and apparatus for receiving, monitoring and characterizing network power information in real time through the use of a specialized display system. A processor receives three phase current and voltage information from a network power relay, converts and scales that data into a two-dimensional vector having coordinates that are represented by, and displayed as, a single pixel on a display screen. The repeated monitoring provides a Feature Map (FM) of the network system that can be easily read and understood by operating personnel.

Abstract: A compact power circuit configured for circuit breaker applications includes, in one embodiment, a plurality of current transformers, each current transformer being coupled to a respective one of the phase lines of a power line to generate a current proportional to the current in the respective one of the phase lines. The circuit also includes a plurality of operational amplifiers, each of the operational amplifiers being coupled to a respective one of the current transformers. The operational amplifiers generate the phase signals v.sub.a, v.sub.b and v.sub.c respectively. A neutral phase signal Vn is generated by a current transformer coupled to the neutral phase line of the power line. A ground fault signal is generated from the vector sum of signals v.sub.a, v.sub.b, v.sub.c and V.sub.n.

Abstract: An apparatus and method are disclosed for controlling the power flow in an electric transmission system including at least two transmission lines, each transmission line having two ends and carrying alternating current at a selected transmission line voltage and fundamental frequency between the ends. At least two alternating voltages at the fundamental frequency of the alternating currents flowing in the transmission lines, with variable magnitude and controllable phase angle relative to the transmission line current, are generated and coupled in series with the transmission lines. The magnitude and phase of each generated voltage are controlled selectively and individually to adjust the effective reactive and real impedance of each transmission line, to control the real power transmitted between the two ends of the transmission line and, concurrently, to control the amount of real power individually transferred between the transmission lines.

Abstract: A dynamic mechanically-switched damping (DMSD) system is described which utilizes one or more mechanical switches and appropriate controls to switch series or shunt reactive impedances in order to provide power oscillation damping in power systems. The DMSD system provides a controller which can be configured based on the number of mechanical switches in the DMSD system, the type of reactive impedances interfaced to the power system by each switch and the magnitude of each of the reactive impedance. The DMSD system monitors parameters of the power system and the controller generates a modulation signal based on the monitored parameters. The modulation signal is processed to identify a reactive impedance of the available DMSD system reactive impedances required to damp power oscillations. Appropriate switches are selected for supplying the required reactive impedance.

Abstract: A phase-shifting interconnection apparatus for interconnecting respective phase lines of first and second synchronous polyphase AC networks, includes for each pair of respective phase lines subjected to an interconnection a pair of circuit branches in parallel, having first and second common branch points provided with connecting means for connecting respectively the branch points to the respective phase lines, the circuit branches including respectively inductive and capacitive susceptances; and series transformer for phase-shifting a voltage applied to at least one of said susceptances, the series transformer including at least one primary winding having at least a portion connected in series with the at least one of the susceptances, and at least one secondary winding having at least a portion adapted to receive an excitation voltage derived from the AC networks, the excitation voltage having a phase angle with respect to a phase voltage provided by one of the respective phase lines, whereby, in operation,

Abstract: An improved apparatus and method reduce the harmonic content of AC line and neutral line currents in polyphase AC source distribution networks. The apparatus and method employ a polyphase Zig-Zag transformer connected between the AC source distribution network and a load. The apparatus and method also employs a mechanism for increasing the source neutral impedance of the AC source distribution network. This mechanism can consist of a choke installed in the neutral line between the AC source and the Zig-Zag transformer.

Abstract: A method and apparatus for providing a source of alternating current electrical power to a plurality of loads in an office environment, including a plurality of non-linear loads which draw power for only a portion of the alternating current cycle, includes an input source of electrical power to a primary side of a power transforming device which provides an output at its secondary side which comprises at least two phases and a shared neutral. The plurality of loads are evenly distributed between each phase of the output power source and the shared neutral so as to reduce by current cancellation the current which would otherwise flow in the shared neutral conductor due to the presence of the non-linear loads. In one embodiment, each of six output phase is separated from the other by 120 electrical degrees, and the fourth, fifth and sixth phases are separated from the first, second and third phases, respectively, by 180 electrical degrees.

Abstract: A bias voltage vectorially added to the controllable voltage injected in series with the line voltage of a transmission line reduces the required MVA rating for a unified power flow controller (UPFC) in applications where the power in the transmission line only flows in a single direction, or where the range of the transmission angle is otherwise unequal about zero.

Abstract: A dynamic phase angle regulator for enhancing the transient stability of a three phase AC power system includes a controller, a switching assembly of thyristor switches, and a single transformer coupled to a power line. The transformer includes a balanced three phase configuration of exciting windings coupled to nodes at each phase of a three phase transmission system. Each phase of the transformer further includes a pair of regulating windings electrically coupled to the node and magnetically coupled to a corresponding exciting winding. Each exciting winding induces a voltage on the corresponding pair of regulating windings. To provide a selected phase shift, the controller actuates the switching assembly in response to a transient event to add a voltage induced on the regulating windings to the line voltage. A method is also provided for regulating the phase angle in a polyphase power transmission system.

Abstract: A faster, more controllable phase-shifting transformer system is provided, along with a method of retrofitting and upgrading a preexisting system for faster operation, and a method of applying a desired phase shift to the voltage on a polyphase transmission line. A phase-shifting transformer set has series and regulating transformers coupled together by a switching network, An optional modulator modulates the phase shift voltage about a nominal level established by the switching network. The modulator may be a variable susceptance switched inductor or a switched capacitor, or a variable source device, such as a voltage source inverter device or a synchronous condenser. A thyristor augmented switching network may have a pair of thyristor valves augmenting a reversing switch, or a thyristor augmented load tap changer for varying the phase shift discreet step magnitude.