Abstract: A common-core power factor correction resonant converter includes an energy-transforming circuit. The energy-transforming circuit receives an input line voltage and generates an output power. The energy-transforming circuit includes a coupling inductor and a charge-storage capacitor. The coupling inductor and the charge-storage capacitor are charged by the input line voltage in response to a control signal, so as to generate a charge-storage capacitor voltage. When the charge-storage capacitor voltage is charged to a preset voltage level, the coupling inductor and the charge-storage capacitor are discharged according to the control signal. Then, the energy in the coupling inductor and the charge-storage capacitor is transformed to the output load and provide the output voltage or current regulation.

Abstract: Methods and apparatus for providing a bus interface are disclosed. An example bus interface includes a first power supply bus configured to distribute a first power supply voltage to first circuitry during a normal operating mode of the bus interface and power off during a low power operating mode of the bus interface. The example bus interface also includes a second power supply bus configured to distribute the first power supply voltage to second circuitry during the normal operating mode and distribute a second power supply voltage to the second circuitry during the low power operating mode. The example bus interface further includes a selection device coupled with the first power supply bus and the second power supply bus, where the selection device is configured to transition the bus interface between the normal operating mode and the low power operating mode in response to a received signal.

Abstract: The present invention proposes a liquid crystal display device and a transforming circuit thereof. One terminal of a first coil connects to input voltage. One terminal of a energy-storage unit connects to the other terminal of the first coil. One terminal of a second coil connects to the other terminal of the energy-storage unit, and the other terminal of the second coil connects to the light source. An input terminal of a unidirectional unit connects to the one terminal of the first coil which is connected to the input voltage, and the output terminal connected to the one terminal of the second coil which is connected to the light source. A driving signal is fed into a controlling terminal of a switch unit. A first terminal of the switch unit is grounded, and the second terminal of the switch unit is connected a medial point between the first coil and the energy-storage unit.

Abstract: The present disclosure provides a power factor correction circuit. The power factor correction circuit includes an AC power, a first bridge arm, a second bridge arm and at least one auxiliary capacitor. The AC power has first and second ends. The first bridge arm includes first and second switches connected in series with each other. A second terminal of the first switch is connected to a first terminal of the second switch, and is coupled to the first end of the AC power via a first inductor. The second bridge arm is connected in parallel with the first bridge arm, and includes third and fourth switches connected in series with each other. A second terminal of the third switch is connected to a first terminal of the fourth switch and the second end of the AC power. The auxiliary capacitor is connected to the third or fourth switch in parallel.

Abstract: A one-phase static var compensator apparatus includes a compensator string consisting of a first static var compensator connected serially to a thyristor valve. The compensator string is arranged to be connected on its first end to one phase of a transmission grid of a rated voltage exceeding 69 kV. Moreover, the thyristor valve includes a plurality of thyristors connected serially and the compensator string is arranged to be directly connected to the transmission grid. A corresponding three phase apparatus is also presented.

Abstract: A PFC converter that prevents and reduces switching losses by controlling ripple of inductor current and enables application for high power usage, includes a switching device that is turned off when an inductor current flowing through an inductor reaches a first threshold value, and turned on when the inductor current reaches a second threshold value. A switching control circuit sets a reference value of the inductor current using results from an input voltage detection circuit and an output voltage detection circuit. The first threshold value is produced by adding a predetermined value to the reference value, and the second threshold value is produced by subtracting the predetermined value from the reference value.

Abstract: A resonant converter with power factor correction includes a power-obtaining circuit, an energy-storage element and an energy-transferred circuit. The power-obtaining circuit is used for receiving an input line voltage. The energy-storage element is coupled between the power-obtaining circuit and the energy-transferred circuit. The energy-transferred circuit is used for generating an output power. In a first time period, based on a first control signal, the energy-storage element and the power-obtaining circuit operate a soft switching so that the energy-storage element is charged to obtain the input line power and generate an energy-storage voltage. In a second time period, based on a second control signal, the energy-storage element and the energy-transferred circuit operate a soft switching so that the energy-storage element is discharged to make the energy-storage voltage converted into the output power.

Abstract: An apparatus for compensating a power system transmission line (46). The apparatus comprises an autotransformer (40) disposed in series with the transmission line (46). An autotransformer series winding (40A) extends from an input terminal (46) to a neutral terminal (44) and a common winding (40B) extends from an output terminal (54) to the neutral terminal (44). A compensating device (42) is connected between the neutral terminal (44) and ground. Although connected in shunt with the transmission line (46), the compensating device (42) operates as a series-connected compensating device relative to the transmission line (46). The autotransformer (40) can be connected in a buck or a boost configuration with a fixed or moveable winding tap (88). Also, two autotransformers (110, 114) can be connected in a back-to-back configuration with the compensating device (42) connected to either autotransformer (110, 114).

Abstract: There are provided a power factor correction circuit capable of transferring extra power to a ground before performing switching for a power factor correction to thereby reduce a switching loss generated in switching for a power factor correction, and a power supply device and a motor driving device having the same. The power factor correction circuit includes: a main switch switching input power to adjust a phase difference between a current and a voltage of the input power; and an auxiliary switch switched on before the main switch is switched on, to thereby form a transmission path for extra power of the main switch.

Abstract: A one-phase static var compensator apparatus includes a compensator string consisting of a first static var compensator connected serially to a thyristor valve. The compensator string is arranged to be connected on its first end to one phase of a transmission grid of a rated voltage exceeding 69 kV. Moreover, the thyristor valve includes a plurality of thyristors connected serially and the compensator string is arranged to be directly connected to the transmission grid. A corresponding three phase apparatus is also presented.

Abstract: The invention describes an electrical device having at least one interference suppression capacitor (6, 60) that is actively discharged when there is an interruption to the mains voltage (7) by connecting an electrical load (69) in parallel. For this purpose, the device has means for monitoring the mains voltage (7) and means for connecting (68) the electrical load.

Abstract: A voltage regulating circuit converts a first voltage and provides the converted first voltage to a first voltage pin of a north bridge chip after receiving a control signal from a south bridge chip. A second voltage pin of the north bridge chip is connected to a voltage converting circuit for receiving a second voltage. The logic control circuit receives a control signal from the super I/O chip and outputs a first control signal to turn on the switch to connect the first and the second voltage pins together. The logic control circuit also outputs a second control signal to the voltage regulating circuit to control the voltage regulating circuit to stop providing the converted first voltage to the first voltage pin of the north bridge chip. The voltage converting circuit provides the second voltage to the first voltage pin of the north bridge chip via the switch.

Abstract: A device for improving efficiency of an induction motor that soft-starts the motor by applying a voltage to the motor that is substantially less than the rated voltage then gradually increasing the voltage while monitoring changes in current drawn by the motor, thereby detecting when maximum efficiency is found. Once maximum efficiency is found, the nominal motor current is found and operating ranges are set. Now, the voltage to the motor is increased/decreased by measuring the phase angle between the voltage and the current to the motor and increasing the voltage when the phase angle is less than a minimum phase angle (determined during soft-start) and decreasing the voltage when the phase angle is greater than or equal to the minimum phase angle as long as the voltage does not fall below a minimum voltage determined during soft-start.

Abstract: A one-phase static var compensator apparatus includes a compensator string consisting of a first static var compensator connected serially to a thyristor valve. The compensator string is arranged to be connected on its first end to one phase of a transmission grid of a rated voltage exceeding 69 kV. Moreover, the thyristor valve includes a plurality of thyristors connected serially and the compensator string is arranged to be directly connected to the transmission grid. A corresponding three phase apparatus is also presented.

Abstract: An arrangement and a method for reactive power compensation in connection with a power transmission line. The arrangement includes at least one transformer and at least one reactive power compensator connected to the low-voltage side of the transformer and at least one adapter reactor, the adapter reactor being connected in series with the transformer so that the reactive power compensator is connected to the power transmission line via the transformer and the adapter reactor.

Abstract: The present invention discloses a power factor correction circuit, a control circuit therefor and a method for driving a power factor correction circuit. The power factor correction circuit receives rectified power obtained by rectifying AC power, and corrects the power factor thereof. The power factor correction circuit includes an inductor, and it generates a reference signal as a limit for the inductor current. The reference signal is proportional to Comp/Vin, wherein Comp is a signal relating to a feedback signal, and Vin is a voltage signal relating to the AC power or the rectified power.

Abstract: The invention relates to a poly-phase reactive power compensator 1 comprising for each phase a, b, c a reactive power means 3a, 3b, 3c; 2a, 2b, 2c. The poly-phase reactive power compensator 1 further comprises means 21, 22, 23; 31, 32, 33 for transferring susceptance between the phases a, b, c. The invention also provides a control device for controlling the poly-phase reactive power compensator 1.

Abstract: A three-phase boost-buck PFC converter including three independent single-phase boost-buck PFC circuits respectively is provided, which are capable of performing PFC on each phase of the three-phase power. The single-phase boost-buck PFC circuit is composed of two single-phase boost-buck converters independently working in a positive and a negative half cycle of an input voltage, and the two single-phase boost-buck converters are connected in parallel at an input side, and are connected in series at an output side, and each of the single-phase boost-buck converters is composed of a front-end boost circuit and a back-end buck circuit connected in cascade. Compared to the existing technique, regardless of a boost mode or a buck mode, the conduction loss is effectively reduced, and the whole system efficiency is effectively improved.

Abstract: A power factor correction converter includes a diode bridge that rectifies an alternating-current voltage input from an alternating-current input power supply Vac, a series circuit including an inductor and a switching element, a rectifying smoothing circuit connected in parallel with the switching element and including a diode and a smoothing capacitor, and a digital signal processing circuit that controls turning on and off of the switching element such that the input current input from the alternating-current input power supply Vac comes to have a similar shape to the alternating-current voltage. The current flowing through the inductor in the off period of the switching element is detected by using a current detection resistor, the operation mode is determined on the basis of the inductor current IL at a predetermined timing and the switching element is optimally controlled in accordance with the operation mode.

Abstract: A method of operating a power factor correction (PFC) circuit and a corresponding power factor correction circuit include determining an adaptive switching frequency of the PFC circuit related to a current of the boost inductor of the PFC circuit, and operating the PFC circuit at a light load based on the adaptive switching frequency.

Abstract: An integrated electric meter with VAR capability is disclosed. In one aspect, an electric meter determines a plurality of power related parameters for an AC network, and a VAR generation unit integrated with the electric meter uses the plurality of power related parameters to inject a desired amount of reactive power in the AC network and correct power factor.

Abstract: Described are improvements in power factor control and systems embodying said improved power factor control. Improvements lie in a method of zero voltage switching in which a capacitor is placed in parallel with a switching device, and the switching device is operated responsive to a change in the polarity of the current through the capacitor. Switching therefore occurs at zero or close to zero voltage across the switching device in both on and off modes resulting in very low switching losses and electromagnetic interference. Systems employing the method include a power factor controller, LED light source, boost converter and a power source comprising one or more photovoltaic cells.

Abstract: A method of controlling a static VAR compensator includes providing a static VAR compensator having a capacitive component and a thyristor for switching the capacitive component into and out of a power distribution network; monitoring an electrical characteristic associated with the capacitive component; and controlling operation of the thyristor at least in part on the basis of the electrical characteristic associated with the capacitive component.

Abstract: A first SVC is connected to a first bus. A first SVC control unit controls the first SVC. A first fluctuation-component-voltage generating unit includes a voltage reference circuit that outputs a voltage reference value. A second SVC is connected to a second bus. A second SVC control unit controls the second SVC. A second fluctuation-component-voltage generating unit includes a first-order-lag control block with limiter that generates a comparative voltage that follows a bus voltage of the second bus with a predetermined time lag characteristic and is limited within a predetermined range. An impedance value XS1 of slope reactance of the first SVC is set smaller than impedance value XS2 of slope reactance of the second SVC.

Abstract: A method and circuit for correcting a power factor in an alternating current/direct current power transformer. The circuit has an inductance fed by a rectified AC voltage, and a switch by which the inductance can be charged and discharged by closing and opening the switch, and further has a diode by which the discharge current of the inductance is fed to the output of the circuit. During the discharge phase, a voltage Vmon corresponding to the output voltage VBUS is measured, and the measured values are stored. It is further determined when the discharge current reaches or crosses the zero line at the end of a discharge phase. Switch-on and switch-off signals for actuating the switch are generated by analyzing the information determined. The switch should not be switched on again until a particular minimum switch-off time has been reached.

Abstract: A power compensation system 108 for compensating for the reactive power requirements in an electricity system 100 is provided. The reactive power compensation system 108 includes a static synchronous compensation unit 202, a harmonic current elimination unit 204 and a compensation control unit 206. The static synchronous compensation unit 202 comprises a plurality of static synchronous compensation modules 302 for compensating for the reactive power in the electricity system 100. The harmonic current elimination unit 204 includes a plurality of active filtration modules 502 for eliminating the harmonic current generated in the electricity system 100. The compensation control unit 206 implements a sequential control mechanism for regulating the operation of the static synchronous compensation modules 302 and the active filtration modules 502.

Abstract: A distributed capacitor bank controller for power factor correction of a power system may include a first distributed meter, a second distributed meter, a programmable logic controller and a communications pathway. The first and second meters may be operable to provide a power factor value, a current value, a voltage value, and a load value. The first and second meters may be coupled to the programmable logic controller via the communications pathway. The programmable logic controller may be operable to receive the power factor value, the current value, the voltage value and the load value from the first and second distributed meters, determine an average power factor value and a current unbalance value, and automatically add or remove a capacitor step of a capacitor bank to the power system based at least in part on the average power factor value, the current unbalance value, the voltage value and the load value.

Abstract: A static compensator system for providing reactive and/or active power to a power network. The system includes a static compensator, which has a DC capacitor Ud and a voltage source converter. The static compensator is connected to an energy storage device. The system further includes a booster converter device connected in series with the energy storage device and in parallel with the DC capacitor Ud of the static compensator. The booster converter device and the energy storage device are further connected in parallel with the voltage source converter of the static compensator.

Abstract: According to the method for regulating the supply voltage of an electronic circuit a regulating element with variable resistivity and the outer supply voltage being applied to an input terminal of said regulating element is controlled by an amplified difference between a reference voltage and a part of a regulated supply voltage whereat at first an instant, on which the regulating circuit and the electronic circuit start operating, is detected, and then such value of the reference voltage is set on said instant that the regulated supply voltage will equal a maximum allowable supply voltage of the electronic circuit and the supplied electronic circuit puts itself in a state of a maximum current consumption. Then an operating voltage drop across said regulating element is measured at regular time intervals and the reference voltage is then each time reduced by one degree until said operating voltage drop is below or equals a chosen most appropriate value of said operating voltage drop.

Abstract: The invention relates to a poly-phase reactive power compensator 1 comprising for each phase a, b, c a reactive power means 3a, 3b, 3c; 2a, 2b, 2c. The poly-phase reactive power compensator 1 further comprises means 21, 22, 23; 31, 32, 33 for transferring susceptance between the phases a, b, c. The invention also provides a control device for controlling the poly-phase reactive power compensator 1.

Abstract: A wind power plant and a method of start up at least a part of a wind power plant connected to an external grid substantially without any energy delivered from the external grid for the start up is provided. The wind power plant having a plurality of wind turbines and at least one power source connected to at least one of the wind turbines in order to start the wind turbine while isolated from the remaining wind turbines. The started wind turbine may then supply power in order to start further wind turbines. Power may be delivered to the grid from the started wind turbines.

Abstract: A one-phase static var compensator apparatus includes a compensator string consisting of a first static var compensator connected serially to a thyristor valve. The compensator string is arranged to be connected on its first end to one phase of a transmission grid of a rated voltage exceeding 69 kV. Moreover, the thyristor valve includes a plurality of thyristors connected serially and the compensator string is arranged to be directly connected to the transmission grid. A corresponding three phase apparatus is also presented.

Abstract: Systems and/or methods that facilitate controlling a rate of voltage change across an inductively loaded thyristor when switched are presented. Based on a received control signal indicating a thyristor is to be switched, a control component controls the rate of voltage change across a thyristor associated with an inductive load when the thyristor is switched from a first state to another state to facilitate controlling noise emissions during switching based in part on a predefined noise criteria, without using a filter. A capacitor component is connected to the inductive load and thyristor. The control component employs a voltage-controlled current sink comprising a transistor to facilitate discharging voltage from the capacitor component until the capacitor component is discharged to a predefined voltage level, where at or near such point a gate component can send a signal to the thyristor gate to switch the thyristor to the desired state.

Abstract: A multiplier multiplies a current signal of an Iy generator and a voltage signal from a Vx generator corresponding to a divided voltage value of an output voltage of a full-wave rectifier. The result of the multiplication is output as a current reference signal to the non-inversion input terminal of a current error amplifier. A current peak waveform generator circuit generates an envelope waveform of peak values of an inductor current. An Iz generator, when the envelope waveform exceeds a first threshold value smaller than a third threshold value set in an overcurrent protection circuit, curbs the inductor current by adjusting the size of a current signal output to the multiplier, and reducing the current reference signal.

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 circuit to improve the power factor of a power supply at light load, the circuit including a rectifier bridge, a filter positioned before or after the rectifier bridge, a logic control and power drive circuit, a switching transistor, a light load detecting circuit configured to output a control signal to the logic control and power drive circuit which controls the switching transistor to conduct when a heavy load is experienced and to cut off when a light load is experienced, in order to control the working status of the filter capacitor, and a power factor correction circuit.

Abstract: In a system stabilizing control system of controlling reactive power by a reactive power compensating device according to a voltage variation of an electric power system in which a capacitor is connected to a bus through a breaker, when the bus voltage drops, the capacitor is closed through the breaker to suppress a leading compensation reactive power amount caused by the reactive power compensating device, and when the bus voltage rises, the capacitor is disconnected through the breaker to suppress a lagging compensation reactive power amount caused by the reactive power compensating device.

Abstract: The present invention relates to a static compensator and a method for controlling thereof, more particularly, to a static compensator including a transformer connected with a bus of a power system; an inverter operating according to a control signal and connected to the transformer in series; a tap changer changing turn ratio of the transformer; and a controller generating the control signal to operate the inverter and generating a tap up or a tap down signal to provide to the tap changer and a method for controlling thereof.

Abstract: An AC-DC power converter controls an external upstream switching device, which supplies it power to be converted. Power conversion is initiated when an external signal requests power be converted or when a program within the AC-DC power converter detects the need for power conversion. When this occurs, the AC-DC power converter signals the external switching device, which is upstream of the AC-DC power converter to turn on, thereby supplying the power to be converted to the AC-DC power converter.

Abstract: According to one example embodiment, a bridgeless boost power factor correction (PFC) system includes a first input for connection to a first line of an alternating current (AC) source and a second input for connection to a second line of the AC source. The PFC system includes an output for delivering an output of the bridgeless boost PFC system, a first boost choke coupled to the first input and a second boost choke coupled to the second input. A common mode choke is coupled between the first and second input and the first and second boost choke. A first X capacitor is coupled between the first input and the output and a second X capacitor coupled between the second input and the output.

Abstract: The present invention relates to a power factor correction circuit and a power factor correction method. The present invention receives information on an output voltage of output power and information on an inductor voltage to control a switching operation of a power switch, and estimates the input voltage according to duty of the power switch.

Abstract: A device for providing power factor correction of a low voltage subnet that includes a low voltage feeder line that is connected to one or more low voltage power supply lines that supply power to one or more customer premises is provided. In one embodiment, the device includes a power factor measurement module configured to measure power parameters for determining a power factor of the power traversing the low voltage subnet; a power factor correction assembly configured to vary a capacitance connected to the low voltage feeder of the low voltage subnet; a controller in communication with the power factor measurement assembly and the power factor correction assembly. The controller may be configured to cause the power factor correction assembly to change the capacitance based on the determined power factor. The controller may form part of a power line communication device configured to provide communications to the one or more customer premises.

Abstract: An apparatus for reactive power compensation in an ac medium voltage power network. The apparatus includes a common connection; a first branch including a first switch, and a first capacitor; and a second branch including a second switch and a second capacitor.

Abstract: A SVC control section detects a bus voltage from an instrument transformer, and adjusts reactive power generated by a SVC according to the detected bus voltage. A cooperative control section generates a control command for controlling the interconnection and parallel-off of a phase lead capacitor and a phase lag reactor on the basis of the amount of reactive power generated by the SVC and the bus voltage detected by the instrument transformer and a voltage sensor. A voltage comparator compares the bus voltage with a predetermined threshold voltage set to a voltage lower than a lower limit value of a steady state fluctuation range of the bus voltage and outputs the comparison result to a circuit breaker control section. When the bus voltage is lower than the threshold voltage, the circuit breaker control section locks the control command from the cooperative control section.

Abstract: A Thyristor Switched Capacitor (TSC) system connected to three sets of diodes and thyristors connected in parallel with the diodes being in an anti-parallel configuration, three capacitors connected in series with the diodes and thyristors, and three surge current controlling reactors that control the transient time to improve power quality in the grid.

Abstract: A power switching control apparatus for acquiring pieces of making operation time information of individual phase switches more precisely according to loads and making instants. Making operation time information detecting means outputs the making operation time information of at least one of individual phase switches on the basis of the motion of the movable contact of the phase switch, and outputs the making operation time information of at least another of the individual phase switches on the basis of the phase current of the phase switch. Moreover, the making operation time information detecting means outputs the making operation time information ITA, ITB and ITC of an A-phase switch, a B-phase switch and a C-phase switch individually on the basis of either the detected output of a contact operation sensor and the detected output of a phase current sensor.

Abstract: A reactive power control apparatus for an AC power system includes a reactive power compensation device, a compensation capacitor device and a compensation capacitor control device. The compensation capacitor control device includes a detection voltage output circuit which outputs a bus detection voltage after the clearing of a voltage drop abnormality, corresponding to the AC voltage of a system bus after the voltage drop abnormality that occurred in the AC power system has been cleared, and a compensation capacitor control circuit which controls the connection status of a compensation capacitor with respect to the system bus. The compensation capacitor control circuit controls the connection status of the compensation capacitor with respect to the system bus, on the basis of the voltage level of the bus detection voltage after the clearing of the voltage drop abnormality.

Abstract: In a conventional reactive-power compensator using a static reactive-power compensator (SVC), there are many cases in which the SVC is operating in a state in which it generates an amount of reactive power equivalent to a large part of its capacity. When an unforeseen large voltage fluctuation occurs in this state, the SVC can not sufficiently generate the amount of reactive power required to mitigate the voltage fluctuation. In some cases, such a voltage fluctuation can not be brought under control. To address this situation, a reactive-power compensator utilizes a reactive-power control apparatus that includes a comparison voltage generator for generating, for a control target voltage and to mitigate voltage fluctuation, a comparison voltage restricted within predetermined limits and obeying a predetermined time-lag characteristic. A differential voltage generator generates a differential voltage that is the difference between the comparison voltage and the control target voltage.

Abstract: An active phase angle correction circuit which corrects the phase angle between voltage and current in an AC supply varies the capacitive loading of the AC mains to reduce the phase angle to near zero by detecting the phase angle, reactively and resistively loading the AC mains in steps until the phase angle is at a desired level close to zero, and then maintaining or incrementally adjusting the loading. The applied loading may be continuously switched in and out at a rate much greater than the mains supply frequency.

Abstract: A reactive power compensator includes a control block with a limiter and a primary delay-control block with a limiter that set, based on an output of a voltage sensor, reactive power produced by an SVC to a predetermined value. A reactive power controller sets the reactive power produced by the SVC to the predetermined value controls a voltage of a second bus to fall within a predetermined range. This is performed by adjusting an initial value of the reactive power that is output by the SVC, when a bus voltage of the second bus laid at a position apart from a first bus that is laid at a position near the SVC is deviated from a predetermined fixed range.