Abstract: A quantized voltage feed-forward (QVFF) circuit and integrated circuits using this technique. The QVFF circuit includes a plurality of comparators in combination with a logic control circuit. The comparators are structured and arranged to establish various voltage threshold levels, each providing a digital state signal representative of the sensed input voltage level. The logic control circuit is structured and arranged to use the digital input signals from the comparators to output a voltage feed-forward factor (KVFF) signal that is representative of the V2rms voltage. Output from the logic control circuit is provided to an analog signal multiplier and used to shape an input current reference (IMO) waveform. This allows detection of changes in the rms level of the input voltage on the half-cycle of the AC line voltage, resulting in a rapid response to line voltage changes. Because the KVFF factor signal contains no AC ripple component, it does not contribute to THD of the input current reference, IMO.

Abstract: Disclosed is a PFC (power factor correction) device for shaping an input current of a power converter. The device includes means for receiving a rectified input voltage derived from an AC input voltage; load determining means for determining a load value L which represents the power drawn by a load supplied by the power converter; current shaping means for shaping the input current of the power converter to follow a reference waveform; and control means for controlling the current shaping means to operate over a conduction interval ? during each positive and negative half cycle of the AC input voltage. The duration of the conduction interval is controlled in accordance with the load value L. The current shaping means may shape the input current to follow the reference waveform which crosses zero at phase angles which substantially correspond to the start and end of the conduction interval.

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: A power conversion controller having a novel power factor correction mechanism, including: a normalization unit, used to generate a normalized signal according to a line voltage by multiplying the line voltage with a normalizing gain, wherein the normalizing gain is proportional to the reciprocal of the amplitude of the line voltage; a reference current generation unit, coupled to the normalization unit to generate a reference current signal by performing an arithmetic operation, wherein the arithmetic operation involves the normalized signal; and a gate drive signal generation unit, used to generate a gate drive signal, wherein the duty of the gate drive signal is determined by a voltage comparison of the reference current signal and a current sensing signal.

Abstract: A power factor controller is disclosed, in which error feedback is provided my means of a parallel combination of at least two error feedback channels. By providing at least two error feedback channels, the stability associated with, for instance, a continuously integrated feedback loop with relatively long time constant, may be combined with a fast transient response associated with, for instance, a sample-and-hold error feedback. A method of operating such a power factor controller is also disclosed.

Abstract: A switching power supply circuit has a control circuit for current-mode on-off control of a primary switch connected to an inductor in a voltage boost topology for operation in boundary-conduction mode. The time at which the primary switch is opened is determined by magnitude of current flowing through the primary switch together with the instantaneous voltage present on an AC input to the power supply circuit. The time at which the primary switch is closed is determined by demagnetization of the inductor. An improvement to the foregoing switching power supply circuit comprises a maximum-on-time enforcement circuit to limit the maximum possible primary switch on-time to a predetermined maximum period of time. The enforcement circuit provides a signal to the control circuit to cause termination of the primary switch on-state if and only if the primary switch has been turned on for more than the predetermined maximum period of time.

Abstract: At the time of charging a power storage device from a commercial power supply, electric power from the commercial power supply is applied to a neutral point of each of first and second motor generators. A rotation preventing control unit (222) determines one phase to be subjected to switching control in the first inverter, based on a rotation angle (?1) of the first motor generator. Further, rotation preventing control unit (222) calculates torque generated in the first motor generator, generates a torque control value for canceling out the torque, and outputs the value to a phase voltage operating unit (214) for motor control.

Abstract: According to one embodiment, a power supply circuit includes an input terminal, a rectifier circuit, a power factor improvement circuit, a DC/DC converter, and a control module. The DC/DC converter converts the level of a DC voltage output from the power factor improvement circuit. The control module determines on the basis of the output voltage of the rectifier circuit whether an input power supply supplied to the input terminal is AC or DC. The control module generates a DC power supply by use of the power factor improvement circuit and DC/DC converter when the input power supply is AC and generates a DC power supply by controlling the operation of the power factor improvement circuit and DC/DC converter according to the voltage of input DC power supply when the input power supply is DC.

Abstract: A power factor correction (PFC) controller includes a first integrator coupled to integrate an input current of a PFC converter. A first signal is generated in response to the first integrator to end an on time of a power switch of the PFC converter. A second integrator is coupled to integrate a difference between a constant voltage and an input voltage of the PFC converter. A second signal is generated in response to the second integrator to end an off time of the power switch of the PFC converter. A driver circuit is coupled to vary the switching frequency of the power switch of the PFC converter in response to the first and the second signals and to output a third signal to switch the power switch of the PFC converter to control the input current to be substantially proportional to the input voltage.

Abstract: An electrical power generation system, such as a solar power inverter, can provide dynamic real-time power compensation, so as to mitigate the effects of voltage sags and swells (e.g., on a utility grid) and thereby provide voltage support functionality to a local grid. The electrical power generation system can do so by receiving first synchrophasor measurements that are taken at a point on the utility grid and transmitted to the electrical power generation system and by taking second synchrophasor measurements. The first and second synchrophasors indicate voltage magnitude and frequency of the alternating current (AC) at their respective measurement points. The electrical power generation system can compare the first synchrophasors with the second synchrophasors and based upon the comparison, vary the power factor of the power the electrical power generation system generates (e.g., by either supplying or absorbing reactive power).

Abstract: A control device for controlling a reactive power compensator connected to an electric power network and arranged to provide reactive power to the electric power network. The control device includes a voltage regulator outputting a control signal to the reactive power compensator for controlling its supply of susceptance to the electric power network. The control device includes a gain-adjusting device arranged to adjust the gain of the voltage regulator relative to the point of operation of the reactive power compensator.

Abstract: Automated power factor correction analysis methods based on an automatically determined hierarchy representing how IEDs and transformers are linked together in an electrical system for reducing a utility bill, releasing capacity to the electrical system, reducing losses, and/or improving voltages. The automatically determined hierarchy places the system elements in spatial context and is exploited by the power factor correction analysis methods to identify power factor correction opportunities. Recommendations are made as to sizing and location of capacitors within the hierarchy where power factor improvements can be achieved. Harmonic distortion levels can be checked first to determine whether safe levels exist for capacitor banks. Recommendations are also checked to avoid leading power factors anywhere in the system due to the addition of capacitor banks. Capacitor bank location is tailored to the end-user's goal for power factor correction.

Abstract: Embodiments of the invention relate to devices and methods and systems for controlling a reactive power contribution to reactive power flowing in an electricity distribution network, so as to optimise this reactive power flow. Conventional methods of controlling reactive power flow focus on minimising a reactive power contribution by power provision and power consumption devices connected to the electricity distribution network, in accordance with, for example, regulations governing a maximum allowed power factor and/or under the control of a central controlling entity. However, such methods are slow to react to changing network conditions, and do not take account of local variations in reactive power. In an embodiment of the present invention, there is provided a reactive power control device for use with a power consumption and/or provision device.

Abstract: An approach is provided for a power factor compensating method to compensate other electronic devices that use a common power source in order to improve power factor from the perspective of a power company. The other electronic device is a type of a non-linear load, and the method enables a compensator to receive a supply voltage from the power source commonly connected to the traditional electronic devices and disables a load of the compensator for a period. The period corresponds to a range that makes an overall supply current more proportional to the supply voltage.

Abstract: The invention relates to a method to control power output of a doubly-fed induction machine to a grid including the steps of measuring grid voltage and grid current in a three phase coordinate system, transforming grid voltage and grid current into a stator frame coordinate system, decomposing the grid voltage and grid current in the stator frame coordinate system in a positive sequence system and in a negative sequence system, calculating active and reactive power in the positive and negative sequence system, and controlling active and reactive power in the positive and negative sequence system.

Abstract: Device and method for high efficiency (low heat loss) control of AC power to reactive load while maintaining a high power factor.

Abstract: A method is provided in one example embodiment and includes receiving a message associated with a detection of reactive power in an energy system and inducing a first quantity of reactive power at a power level specified in the message. The first quantity of reactive power is induced in order to mitigate a second quantity of reactive power that is detected on a specific segment of the energy system. The first quantity of reactive power is induced at a local level on which a source associated with the second quantity of reactive power operates. In more specific embodiments, the message is sent in response to a sensor detecting the second quantity of reactive power, where the first quantity and the second quantity of reactive power are the same. In other embodiments, the method can include receiving a second message to stop mitigating the first quantity of reactive power.

Abstract: An apparatus for rapidly tracking fundamental frequency information in the signal of an electric grid is a cross-coupled phase-lock loop filter (CCPLL) that includes the use of a phase-lock-loop (PLL) apparatus having a plurality individual filters, wherein an input for a first filter in the plurality of individual filters comprises the signal of the electric grid and an output signal from at least a second filter in the plurality of individual filters. A method for using the CCPLL includes applying a signal to the CCPLL and monitoring the output of the CCPLL. Use of the CCPLL may be accomplished or modeled via computer instructions stored on machine readable media.

Abstract: A system for providing reactive power compensation to a utility power network includes a switch coupled to the utility power network, and a capacitor coupled with the switch for providing a controlled amount of reactive current based on conditions of the utility power network. The system also includes a switchable power dissipation device coupled in series to the capacitor and configured to provide a preselected amount of impedance to the reactive current for a predetermined duration when a line voltage on the utility power network drops below a threshold.

Abstract: Certain embodiments of the invention may include systems and methods for regulating power in renewable energy sources. According to an exemplary embodiment of the invention, a method is provided for regulating active power produced by the renewable energy source towards an apparent power setpoint. The method may include selectively regulating voltage based on power factor foldback or voltage foldback associated with the renewable energy source. When power factor foldback is selected, the method may include regulating the power factor associated with the renewable energy source based at least in part on a power factor angle magnitude setpoint, and reducing the power factor angle magnitude setpoint towards zero when apparent power produced by the renewable energy source approaches or exceeds the apparent power setpoint.

Abstract: A power supply includes a PFC stage 6 and an SMPS stage 8. The power supply can operate in a normal mode in which the PFC stage supplies a voltage to the SMPS stage. In a standby mode, the PFC stage is operated in bursts to supply a lower voltage to the SMPS stage that is high enough that the SMPS stage can rapidly respond when it needs to supply a load.

Abstract: A power factor correction controller is utilized for a power factor correction circuit in a critical conduction mode of an electric power converter. The power factor correction controller generates a control voltage according to an output voltage outputted from the electric power converter, and utilizes a first threshold value to detect the control voltage. The power factor correction controller can control the power factor correction circuit to operate in different modes according to various levels of a load. Therefore, an objective according to the present invention for reducing electric power consumption of the electric power converter in a light load or a no-load mode and improving energy transmission efficiency can be attained.

Abstract: A driver includes a sensor sensing a driving current and a driving voltage for an external device including a capacitor, a PWM, a PFC, and a controller. The PFC includes a phase angle estimation unit estimating a phase angle variation of an input voltage to the PFC based on a parameter regarding the driving current, a voltage compensator compensating an error of the driving voltage, a first current estimation unit estimating a variation of a charge of the capacitor based on the charge current and the phase angle variation estimated by the phase angle estimation unit, a second current estimation unit estimating a driving current variation, and a calculator calculating a duty ratio for the PWM based on the variation of the charge current estimated by the first current estimation unit and the driving current variation estimated by the second current estimation unit.

Abstract: A cost effective solution for power factor correction in power devices operating at two widely separated input voltages comprises two unequal power rails. One power rail is optimized for operation at high line voltage only, while the other power rail is designed only for low line voltage. When operating at high line voltage, the second rail is disabled. At low line, both power rails are enabled but by virtue of unequal boost inductors, the high line power rail handles only about 30% of the power while the low line power rail handles the remaining power. Hence, the efficiency at high line voltage is maximized. As the inductance used in the high line power rail is much higher in value, it stays in continuous conduction mode for all load conditions and hence the power factor is significantly improved.

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: A method employing a lead-unity-lag adjustment on a power generation system is disclosed. The method may include calculating a unity power factor point and adjusting system parameters to shift a power factor angle to substantially match an operating power angle creating a new unity power factor point. The method may then define operation parameters for a high reactance permanent magnet machine based on the adjusted power level.

Abstract: A power factor correction (PFC) system includes a comparison module, an adjustment module, a compensation module, and a duty cycle control module. The comparison module measures N currents having different phases, and generates (N?1) comparisons based on the N measured currents, wherein N is an integer greater than one. The adjustment module determines (N?1) time advance adjustments based on the (N?1) comparisons, respectively. The compensation module generates N compensated versions of an input alternating current (AC) line signal based on the input AC line signal, a sinusoidal reference signal, and the (N?1) time advance adjustments, wherein the sinusoidal reference signal is synchronized to the input AC line signal in phase and frequency. The duty cycle control module controls PFC switching based on the N compensated versions of the input AC line signal.

Abstract: A power factor correction (PFC) system includes a period determination module, a frequency generation module, an angle generation module, a signal generation module, and an angle correction module. The period determination module determines a period of an input alternating current (AC) line signal based on a time between rising edges of the input AC line signal. The frequency generation module generates a frequency based on the period. The angle generation module generates an angle based on the frequency. The signal generation module generates a sinusoidal reference signal based on the frequency and an adjusted angle. The angle correction module generates the adjusted angle based on the angle and based on a comparison of a falling edge of the sinusoidal reference signal, the period, and a rising edge of the input AC line signal.

Abstract: Provided are a novel distribution automation system and its voltage control method, which can supply a stable voltage to a user by properly adjusting the settings of a control device so as to compensate for reactive power at each load terminal.

Abstract: A power factor correction (PFC) system includes a direct current (DC) module, an error control module, an offset module, and a duty cycle control module. The DC module determines an average current value based on a plurality of current values over at least one cycle of an input alternating current (AC) line signal of the PFC system. The error control module generates an error signal based on the average current value. The offset module offsets a desired instantaneous current based on the error signal. The duty cycle control module controls at least one duty cycle of switches of the PFC system based on the offset desired instantaneous current.

Abstract: A power factor correction (PFC) system includes an adjustment module, a compensation module, and a duty cycle control module. The adjustment module generates N time advances based on N predetermined time advances and (N?1) time advance adjustments, wherein N is an integer greater than zero. The compensation module generates N compensated versions of an input alternating current (AC) line signal by predicting ahead of the input AC line signal using a gradient of a sinusoidal reference signal and the N time advances, respectively, wherein the sinusoidal reference signal is synchronized with the input AC line signal in phase and frequency. The duty cycle control module generates PFC duty cycles based on the N compensated versions of the input AC line signal.

Abstract: In order to provide a method for regulating a reactive power compensator, which is connected to an alternating current line having multiple phases, wherein for each phase an actual voltage V12, V23 and V31 present thereon is detected and from the actual voltages V12, V23 and V31 a counter system actual fraction is calculated. A control circuit suppresses the counter system actual fraction. A feedback loop determines the level of suppression of the counter system actual fraction with the help of controlled parameters. The method enables an adjustment of the counter system that is largely independent from operating staff. Accordingly, a comparator unit compares the counter system actual fraction to the counter system target fraction and defines the controlled parameters as a function of the comparison.

Abstract: During single operation of a distributed power supply system that has been disconnected from a commercial electric power system, a frequency increase monitoring circuit is operated and an instruction to output a larger amount of a constant reactive current is given to a reactive current controlling unit. After the output frequency of the distributed power supply exceeds a frequency increase level, the level of an active current is limited in accordance with the level of the outputted reactive current.

Abstract: A voltage control circuit is disclosed. A power factor corrector may utilize the control circuit to provide power factor correction for an AC induction motor. An AC induction motor system may combine the power factor correct with an AC induction motor.

Abstract: The present invention discloses a bridgeless active power factor corrector with a logic control comprising a high frequency switch controller, a boost inductor, an output filtering capacitor, two boost transistor modules, two boost diodes, two AC input voltage polarity detectors, and two low frequency switch drivers. With a coupling signal, the two AC input voltage polarity detectors respectively control the two low frequency switch drivers in conjunction with the high frequency switch controller to drive the two boost transistor modules with a logic control so that the inductor current releasing electric energy from the boost inductor can flow through the channels of the two boost transistor modules to effectively reduce the body diode conduction loss.

Abstract: Systems and methods for reducing harmonic distortion in a power system resulting from non-linear loading on the power system. The power at an interface with a power source is measured, and then distortion in the waveforms of the supplied power is identified. Cancellation signals which cancel all or part of the distortion are then generated and injected at the interface. In one embodiment, the power is sampled to determine the waveform, and then a Fast Fourier Transform is performed on the waveform to convert it to the frequency domain. Harmonics of the fundamental frequency can then be identified, and conjugates of the harmonics generated. An inverse Fast Fourier Transform is performed on the conjugates to generate a signal which is amplified to produce the cancellation signal.

Abstract: A battery charger may be capable of receiving power from a power distribution circuit including a fuse and may be configured to reduce reactive power through the fuse caused by at least one load, other than the charger, electrically connected with the power distribution circuit.

Abstract: The configurations of a single-phase dual buck-boost/buck power factor correction (PFC) circuit and a controlling method thereof are provided in the present invention. The proposed circuit includes a single-phase three-level buck-boost PFC circuit receiving an input voltage and having a first output terminal, a neutral-point and a second output terminal for outputting a first and a second output voltages, a single-phase three-level buck PFC circuit receiving the input voltage and coupled to the first output terminal, the neutral-point and the second output terminal, a first output capacitor coupled to the first output terminal and the neutral-point, a second output capacitor coupled to the neutral-point and the second output terminal, and a neutral line coupled to the neutral-point.

Abstract: A method for controlling a power generation plant may be provided. First, an equivalent grid voltage may be estimated based on electric magnitudes measured at a connection point of the power generation plant and an equivalent model of a power grid to which the power generation plant is connected. Then, on the basis of said estimated equivalent voltage, a command indicative of reactive power to be produced by the power generation plant may be generated.

Abstract: A control apparatus of a DC-DC converter includes a reactor and a switching element, repeats an accumulation and a discharge of energy of the reactor by a switching operation of the switching element, and converts a direct-current input voltage to acquire a direct-current output voltage. The control apparatus includes: a current value acquiring unit that acquires current values of the reactor in a current rising section and a current descending section of a current waveform of the reactor at a time interval of a half of a switching period of the switching element; and a center value estimating unit that estimates a center value of a current of the reactor based on the current values acquired in the current rising section and the current descending section.

Abstract: A control method and a control device for controlling a supply unit, which enable supply of the maximum power that can be delivered by a power source, the method includes the presence of an absolute maximum on the curve of the power as a function of the voltage at the connection terminals; the supply system set between the power source and the load is preferably a DC/DC switching converter. The control circuit identifies the optimal operating point, using the relation existing between the harmonic components of the power and the harmonic components of the voltage at the terminals of the source. Starting from any value of the voltage at the connection terminals, the control circuit increments the value of the voltage if, for a given value of the frequency, the power and the voltage at the connection terminals are in phase, whilst it decrements the value of the voltage if the power and the voltage are in phase opposition.

Abstract: A system and method of controlling a TCSC disposed on a high voltage line of an electrical transmission network. The system comprises: (a) a voltage measuring module; (b) a current measuring module; (c) a regulator, working in accordance with a non-linear control law to receive on its input the output signals from the two modules for measuring voltage and current, and a reference voltage corresponding to the fundamental of the voltage which is to obtained across the TCSC; (d) a module for extracting the control angle in accordance with an extraction algorithm; and (e) a module for controlling the thyristors (T1, T2) of the TCSC, and for receiving a zero current reference delivered by a phase-locked loop which gives the position of the current.

Abstract: A method of performing loadflow calculations for controlling voltages and power flow in a power network by reading on-line data of given/specified/scheduled/set network variables/parameters and using control means, so that no component of the power network is overloaded as well as there is no over/under voltage at any nodes in the network following a small or large disturbances.

Abstract: This invention relates to a method of determining stability of unstable equilibrium point (UEP) computed by using BCU method, comprising selecting UEP computed by using BCU method, obtaining a test vector Xtest for the selected UEP, say XUEP using the following equation: Xtest=Xspost+0.99(XUEP?Xspost) where Xspost is the SEP, and checking boundary condition of XUEP by simulating system trajectory of post-fault original system starting from Xtest.

Abstract: An electricity generating installation is connected to an electricity distribution network and feeds electrical power into the network via a converter. After detecting a network fault, a stabilization regulator in the installation is activated. The stabilization regulator regulates the voltage of the electrical power as a function of a fed-back voltage signal and has a step-function response that rises over time. After a predetermined time period has elapsed since the activation of the stabilization regulator, the reactive current feed is increased beyond a limit which is provided for normal operation if the network has not stabilized. Accordingly, a converter-fed electricity generating installation, such as a wind energy installation, can help stabilize an electricity distribution network after a network fault.

Abstract: A system and method of controlling a TCSC disposed on a high voltage line of an electrical transmission network. The system comprises: (a) a voltage measuring module; (b) a current measuring module; (c) a regulator, working in accordance with a non-linear control law to receive on its input the output signals from the two modules for measuring voltage and current, and a reference voltage corresponding to the fundamental of the voltage which is to obtained across the TCSC; (d) a module for extracting the control angle in accordance with an extraction algorithm; and (e) a module for controlling the thyristors (T1, T2) of the TCSC, and for receiving a zero current reference delivered by a phase-locked loop which gives the position of the current.

Abstract: The present invention relates to a power factor correction circuit and a method of driving the power factor correction circuit. The power factor correction circuit according to the present invention includes a power transfer element configured to receive an input voltage, an input current corresponding to the input voltage flowing through the power transfer element, and a switch connected to the power transfer element and configured to control an output voltage generated by the current flowing through the power transfer element.

Abstract: A method and apparatus for controlling a power converter. In one aspect, a controller for use in a power converter includes a first calculator coupled to determine an end of an on time of a power switch of the power converter by integrating an input current to output an on time signal representative of the end of the on time of the power switch. The controller also includes a second calculator coupled to determine an end of an off time of the power switch by integrating a difference between an input voltage and an output voltage to output an off time signal representative of the end of the off time of the power switch.

Abstract: A system and method for operating a Unified Power Flow Controller (UPFC) connected to a SCADA (Supervisory Control and Data Acquisition) are disclosed. The UPFC automatic operation system receives power system data from the SCADA system, automatically determines UPFC's optimum operation conditions according to power system states. The system includes: a UPFC acting as a serial/parallel FACTS to control variables of a power system; a SCADA for periodically acquiring line data of the power system and state data of the UPFC; and an upper controller for analyzing data received from the SCADA, and determining an UPFC's optimum operation mode for each power system condition and UPFC's optimum set-point control commands.

Abstract: Power compensation is provided from a power compensation device to a utility power network carrying a nominal voltage. The power compensation device has a steady-state power delivery characteristic. The power compensation is providing by detecting a change of a predetermined magnitude in the nominal voltage on the utility power network and controlling the power compensation device to deliver, for a first period of time and in response to the detected change in the nominal voltage, reactive power to the utility power network. The power compensation device is controlled to deliver, for a second period of time following the first period of time, reactive power to the utility power network at a level that is a factor N(N>1) greater than the steady-state power delivery characteristic of the power compensation device.