394 results about "Power oscillation" patented technology

Embodiments of the subject invention pertain to a method and apparatus for contactless power transfer. A specific embodiment relates to an impedance transformation network, a new class of load network for application to a contactless power system. Embodiments of the impedance transformation network enable a contactless power system to operate without encountering the common problems of: 1) over-voltage and / or under-voltage conditions; 2) over-power and / or under-power conditions; 3) power oscillations; and 4) high heat dissipation.

Embodiments of the subject invention pertain to a method and apparatus for contactless power transfer. A specific embodiment relates to an impedance transformation network, a new class of load network for application to a contactless power system. Embodiments of the impedance transformation network enable a contactless power system to operate without encountering the common problems of: 1) over-voltage and / or under-voltage conditions; 2) over-power and / or under-power conditions; 3) power oscillations; and 4) high heat dissipation.

A gas discharge laser crystallization apparatus and method for performing a transformation of a crystal makeup or orientation in a film on a workpiece is disclosed, which may comprise a master oscillator power amplifier MOPA or power oscillator power amplifier configured XeF laser system producing a laser output light pulse beam at a high repetition rate and high power with a pulse to pulse dose control; an optical system producing an elongated thin pulsed working beam from the laser output light pulse beam. The apparatus may further comprise the laser system is configured as a POPA laser system and further comprising: relay optics operative to direct a first output laser light pulse beam from a first laser PO unit into a second laser PA unit; and, a timing and control module timing the creation of a gas discharge in the first and second laser units within plus or minus 3 ns, to produce the a second laser output light pulse beam as an amplification of the first laser output light pulse beam. The system may comprise divergence control in the oscillator laser unit. Divergence control may comprise an unstable resonator arrangement. The system may further comprise a beam pointing control mechanism intermediate the laser and the workpiece and a beam position control mechanism intermediate the laser and the workpiece. Beam parameter metrology may provide active feedback control to the beam pointing mechanism and active feedback control to the beam position control mechanism.

A gas discharge laser crystallization apparatus and method for performing a transformation of a crystal makeup or orientation in a film on a workpiece is disclosed, which may comprise a master oscillator power amplifier MOPA or power oscillator power amplifier configured XeF laser system producing a laser output light pulse beam at a high repetition rate and high power with a pulse to pulse dose control; an optical system producing an elongated thin pulsed working beam from the laser output light pulse beam. The apparatus may further comprise the laser system is configured as a POPA laser system and further comprising: relay optics operative to direct a first output laser light pulse beam from a first laser PO unit into a second laser PA unit; and, a timing and control module timing the creation of a gas discharge in the first and second laser units within plus or minus 3 ns, to produce the a second laser output light pulse beam as an amplification of the first laser output light pulse beam. The system may comprise divergence control in the oscillator laser unit. Divergence control may comprise an unstable resonator arrangement. The system may further comprise a beam pointing control mechanism intermediate the laser and the workpiece and a beam position control mechanism intermediate the laser and the workpiece. Beam parameter metrology may provide active feedback control to the beam pointing mechanism and active feedback control to the beam position control mechanism.

A control method and system for a hybrid electric vehicle powertrain is disclosed. A filtered, profiled battery power modifier is used in calculating a final desired wheel power. Unstable battery power oscillations are avoided when a change in driver power demand is made. The effect of engine torque disturbances also is avoided during steady state operation when desired battery power is between limiting charge or discharge values.

A wind turbine (8) for controlling power oscillations on a grid of a power system (28). The wind turbine (8) comprises rotor blades (12) for turning by the wind, an electric generator (20) rotatably coupled to the rotor blades (12), a power converter (24) responsive to electricity generated by the electric generator (20), the power converter (24) for converting the generated electricity to a frequency and voltage suitable for supply to the power grid (28), and the power converter for regulating voltage on the grid supplemented by modulating real power for damping the power oscillations.

Embodiments of the present invention include control methods employed in multiphase distributed energy storage systems that are located behind utility meters typically located at, but not limited to, medium and large commercial and industrial locations. These distributed energy storage systems can operate semi-autonomously, and can be configured to develop energy control solutions for an electric load location based on various data inputs and communicate these energy control solutions to the distributed energy storage systems. In some embodiments, one or more distributed energy storage systems may be used to absorb and / or deliver power to the electric grid in an effort to provide assistance to or correct for power transmission and distribution problems found on the electric grid outside of an electric load location. In some cases, two or more distributed energy storage systems are used to form a controlled and coordinated response to the problems seen on the electric grid.

Laser systems have a line-narrowed master oscillator and a power oscillator for amplifying the output of the master oscillator. The power oscillator includes optical arrangements for limiting the bandwidth of radiation that can be amplified. The limited amplification bandwidth of the power oscillator is relatively broad compared to that of the output of the master oscillator, but narrower than would be the case without the bandwidth limiting arrangements. The bandwidth narrowing arrangements of the power oscillator function primarily to restrict the bandwidth of amplified spontaneous emission generated by the power oscillator.

The invention belongs to the field of power systems, and in particular to a method which uses an additional damping controller to modulate active and reactive output of a doubly-fed wind generator to increase low-frequency oscillation damping of a grid connection power system of a large-scale wind farm. According to the invention, the method uses auto-disturbance rejection control technology, introduces the theory of data driving control, engineers an additional damping controller of the wind generator, and makes feature signal of the connecting points of a wind farm as input of the additional damping controller which outputs a signal to be added to active and reactive modulation quantity of a machine side current converter. According to the invention, simulation of the method proves that negative damping low frequency oscillation and forced power oscillation are better controlled, and the method has stronger robustness and engineering practicality. The invention provides a novel method for adjusting parameters of a state observer of a second-order non-linear auto-disturbance controller based on broadband concept.

The invention discloses a model prediction current control method based on an NPC topology grid connected inverter under asymmetric voltage, introducing the model prediction current control technology into the NPC grid connected inverter control. The model prediction current control method disclosed by the invention comprises steps of introducing decoupling double synchronization reference coordinate system phase-locked loop (DDSRF-PLL) phase lock technology to perform tracking on a positive sequence voltage phase angle in order to accurately track the positive sequence voltage phase angle under the condition that the power system has the asymmetric fault, on the basis, utilizing the DDSRF-PLL to decouple to obtain fundamental frequency voltage positive and negative sequence components, realizing a model prediction current control with the inhibition of the negative sequence current component, the active power oscillation and the reactive power oscillation as the control goal by combining with a instantaneous power theory, and adding a weight coefficient item into a cost function in order to guarantee the capacitor voltage balance on the DC side of the NPC grid connected inverter in the control process. In the whole control process, the invention reduces the usage of the PI controller, enhances the responding speed of the system, and enables the two sides of the grid connected inverter to have higher electric energy quality and stability.

A clock generation circuit is provided for improving the accuracy of a low power oscillator circuit contained therein. The clock generation circuit includes a crystal-less oscillator having at least two distinct frequency modes, including a low frequency mode and a high frequency mode. In some cases, the crystal-less oscillator may be adapted to generate a first clock frequency with relatively high accuracy and a second clock frequency with relatively low accuracy. A calibration and control circuit is included within the clock generation circuit for increasing the accuracy of the second clock frequency. In particular, the calibration and control circuit increases accuracy by using the first clock frequency to calibrate the second clock frequency generated by the same crystal-less oscillator. A system comprising the clock generation circuit and methods for operating a crystal-less oscillator having at least two distinct frequency modes are also provided herein.

The invention provides a two-region interconnected electric power system alternating current interconnection tie power fluctuation peak calculating method. When the electric power system is in power vacancy, large power vibration can be generated on interconnection tie. The invention is based on the linear second-order system model of two-region electric power system interconnection tie power oscillation and calculates interconnection tie power fluctuation peak after fault by dynamic response of the second-order system. The invention can be applied to simulation analysis of electric power system, grasps the dynamic characteristic of two-region interconnected electric power system, is beneficial to system operation and analysis personnel to timely take effective measures and improves safety steady operation level of electric power system.

The invention discloses a negative-damping low-frequency oscillation and forced power oscillation distinguishing method, relating to scheduling automation of a power system and safety operation of a power grid. The method comprises the following steps of: calculating energy flow direction factors of all generators and load branches based on data acquired by a power grid wide area measuring system (WAMS) when negative-damping low-frequency oscillation or forced power oscillation happens in the power grid; judging whether a definite external disturbance source exists in the power grid; if the definite external disturbance source exists, judging that a low-frequency oscillation mechanism is based on forced power oscillation; and if no external disturbance source exists, judging that the low-frequency oscillation mechanism is based on negative-damping low-frequency oscillation. The negative-damping low-frequency oscillation and forced power oscillation distinguishing method has the advantages that the basis is provided for the power dispatching department to take corresponding measures for rapidly inhibiting oscillation when the power grid has low-frequency oscillation; in addition, the calculating method is simple and feasible, high in calculating speed, capable of meeting the requirement of a real-time oscillation judgment mechanism of the power grid and strong in practicability.

The invention discloses a virtual synchronous generator control method and device for an energy storage converter, which can achieve a purpose that the damping power only acts in the dynamic process of frequency fluctuation, the damping power after a steady state is constant to be zero, the deviation of the steady-state active power cannot be affected due to change of the damping coefficient, and it is guaranteed that the active power tracks the instruction value according to the set droop proportion while power oscillation is restrained. Besides, while the energy storage converter can provide inertia support and grid-connected and off-grid seamless switching, the device has the capability of quickly controlling a voltage and current loop, quickly controls an output current through the current loop, facilitates reduction of current distortion, and improves the electric energy quality of the energy storage converter during grid-connected and island mode operation.

A control method and system for a hybrid electric vehicle powertrain is disclosed. A filtered, profiled battery power modifier is used in calculating a final desired wheel power. Unstable battery power oscillations are avoided when a change in driver power demand is made. The effect of engine torque disturbances also is avoided during steady state operation when desired battery power is between limiting charge or discharge values.

The invention discloses a current compensation based power decoupling method of a virtual synchronous power generator. The power decoupling method comprises the following steps of 1) acquiring a dq component of an output current of a virtual synchronous motor through sampling, acquiring power angle information by a mechanical property simulation part, and further calculating reactive power-power angle decoupling current compensation instruction; 2) acquiring transient state variable quantity of a virtual excitation electromotive force, and calculating active power-voltage decoupling current compensation instruction by combining the dq component, obtained in the step 1), of the output current; and 3) correcting the reactive power-power angle decoupling current compensation instruction obtained in the step 1) and the active power-voltage decoupling current compensation instruction obtained in the step 2) to obtain a new current instruction, and obtaining a switching signal through a current ring to drive a switching network. The invention proposes the power decoupling method applicable to the virtual synchronous motor, and the influence of a power angle on droop control can be eliminated; and compared with the prior art, the power decoupling method has the advantages that dynamic power oscillation and a steady-state error brought by power coupling can be eliminated.

The invention discloses an online analysis and early warning method for low-frequency oscillation of electric power system, relating to the safe operation of electric power system. The method comprises the steps that: oscillation frequency is obtained by carrying out K point median filtering over collected relative power angle in a power grid wide-area measurement system and via Teagar energy operator; and when power oscillation with the oscillation frequency between 0.1-0.2 Hz exists in power grid, the damping ratio dominating oscillation mode can be worked out through a signal energy analysis method based on EMD, thus to realize online analysis and early warning for low-frequency oscillation. The advantages of the invention include that the Teagar energy operator can rapidly work out the frequency of the relative power angle in the power grid; the algorithm of the damping ratio is simplified; large amount of integral operation can be avoided; the calculation is much simpler and morerapid; and the online analysis and early warning for low-frequency oscillation in power grid is realized.

Exemplary embodiments of the present disclosure provide a method and controller for damping multimode electromagnetic oscillations in electric power systems which interconnect a plurality of generators and consumers. The controller for damping such oscillations includes a phasor measurement unit (PMU) and a power oscillation damper (POD) controller. Each oscillating mode signal is damped and then superposed to derive a control signal. A feedback controller is used to feedback the control signal to a power flow control device in the power system.

A power down system and method for an integrated circuit that enables a power down mode to be maintained for a predetermined time is described herein. The power down system comprises an oscillator, a low power oscillator and an oscillator control circuit controlling both the oscillator and the low power oscillator. The oscillator control circuit including at least one real time counter. The oscillator control circuit being so configured that the oscillator is energized when said oscillator control circuit is in a normal mode and that, when a power down signal is received: a) the oscillator control circuit measures an oscillation frequency of the low power oscillator, b) the oscillator control circuit uses the measured oscillation frequency of the low power oscillator to set the real time counter so as to maintain the power down mode for the predetermined time, c) the oscillator control circuit turns off the oscillator and uses the low power oscillator for the duration of the power down.

Disclosed is a method for determining a position of a forced power oscillation disturbance source in a regional interconnected power grid. According to the method, when forced power oscillation occurs in a regional power grid, an algebraic sum of energy flow directional factors in the regions of the regional interconnected power grid is calculated so as to online determine the position of the disturbance source in real-time. Compared with the conventional disturbance source positioning method based on an energy function, the disturbance source positioning method based on calculation of the energy flow directional factors provided by the invention can reduce the impact of a periodic disturbance component and an initial constant on the determination of an aperiodic component of branch potential energy, thus achieving higher accuracy. Moreover, the integration links are reduced and the calculation process is simplified, thus better meeting the requirements for real-time power grid calculation.

The invention provides a nonlinear fractional order auto disturbance rejection damping control method of doubly fed induction generators. The method is characterized by comprising the following steps: establishing a multi-unit system mathematical model comprising the doubly fed induction generators; constructing a mathematical model comprising a fractional order system through diffeomorphism mapping; compensating system parameters and state variables which are included in pre-control variables through design of an extended state observer in an auto disturbance rejection controller; and selecting a fractional order auto disturbance rejection control law and the like. The method provided by the invention effectively improves the damping level of a doubly fed induction generator power grid, effectively estimates model errors and external uncertain disturbance, eliminates errors by use of feedback linearization, effectively enhances the power oscillation inhibition capability of the doubly fed induction generators, reduces investment of additional equipment and improves operation benefits of the power grid, and also has the advantages of scientificalness, rationality, simplicity, effectiveness, quite high robustness, high engineering application value and the like.

The invention relates to a frequency self-recovery control method based on a virtual synchronous generator. When the virtual synchronous generator is put into a microgrid, a small moment of inertia Jis provided to avoid dynamic power oscillation. When small disturbance occurs, the primary frequency modulation method based on virtual synchronous generator is adopted. When the disturbance is large,the frequency offset exceeds a certain value to start the secondary frequency modulation, and the fast charging and discharging characteristics of the energy storage battery are utilized to make it participate in the secondary frequency modulation process, so that the frequency can be quickly restored to the threshold range; after that, the energy storage output is gradually reduced and the secondary frequency modulation is slowly withdrawn, and other frequency modulation devices play a major role in restoring the frequency to the rated value. The invention can effectively restrain the frequency exceeding the limit when the heavy load disturbance occurs, enable the frequency to be recovered quickly, combine the primary and secondary frequency modulation in the whole frequency modulation range, and give full play to the energy storage function.

The invention discloses an online analyzing method for grid forced power oscillation caused by internal disturbance of a power plant and relates to the field of power system operation and control. The method is mainly used for judging whether the grid forced power oscillation is caused by internal periodical disturbance of the power plant. In actual operation of a grid, the forced power oscillation caused by generator disturbance is the most common oscillation mode, but whether grid oscillation is caused by the internal disturbance of the power plant where the grid is connected or by the disturbance at the grid end is difficult to judge directly through the characteristics of oscillation amplitude, frequency and the like. Therefore, the method is provided to identify measured data parameters of the power plant connected into grid nodes based on FFT (fast Fourier transform) and conduct energy flow phase difference analysis to judge whether the grid oscillation is caused by the internal disturbance of the power plant where the grid is connected. By means of the method, judgment can be conducted directly at a measuring terminal, and the method is simple in calculation and high in analyzing speed and has good actual application value.

The invention relates to a method for controlling a three-phase photovoltaic grid-connected inverter when a power grid voltage is unbalanced. The method comprises the steps of establishing a three-phase photovoltaic grid-connected system main circuit and an inverter control system, collecting signals, carrying out clark transform, synchronizing power grids, extracting the phase sequence, calculating a reference current, controlling a current loop, carrying out inverse clark transform, controlling PWM and driving an inverter. The method has the advantages that a photovoltaic power source is efficiently connected to the power grids under the situation that the power grids are normal; the grid-connected current harmonics are effectively eliminated through an LCL filter, and high-power factor grid connection is achieved through a PR current controller; when the power grids break down, the faults can be omitted, and three control targets of voltage supporting, voltage balancing and power vibration eliminating are achieved.

The invention, which belongs to the field of the power system and automation technology thereof, provides a method for locating prime motor disturbance source triggering forced power oscillation. The invention employing the system disturbed trajectory collected by wide area measurement system (WAMS) locates a disturbance source according to the phase relation characteristic between the system response trajectory and the disturbance motivation trajectory, so as to provide a decision support to the electric power system dispatching and operating control. The beneficial effects of the invention lies in that the method, which can solve the problem of distinguishing the response and motivation from the actual measurement system dynamic trajectory, has characteristics of less calculation and simple analysis procedure, so as to provide the intuitive reference for power system operating control and improves the practicability of the WAMS.

A method for damping power oscillation in a power system includes generating synchronized generator speed signals by time stamping a plurality of generator speed signals. The synchronized speed signals are transmitted to a control station for determining power oscillations in the power system. The control station provides damping control signals to a plurality of damping devices based on power oscillations in the power system.

The invention discloses an integrated frequency and damping control method for a double-fed wind power generation unit. When the double-fed wind power generation unit normally operates, a maximum power tracking control policy is adopted; when system frequency is changed, a quick active control instruction is provided for participation in system frequency modulation of the wind power generation unit through a frequency controller, and the inertial frequency response of the wind power generation unit is simulated. The proportional differential control in the conventional frequency control of the wind power generation unit is improved into the proportional differential control with first-order inertia, so that the frequency control of the wind power generation unit is always shown as positive damping characteristics, the wind power generation unit have a frequency modulation control function and a system power oscillation suppression control function, and a foundation is laid for the wide application of the controller. After the frequency of a power grid is changed, the electromagnetic power of the wind power generation unit is quickly regulated by frequency control to participate in frequency modulation of the power grid; if a system is subjected to inter-area low-frequency oscillation, the wind power generation unit can suppress the power oscillation of the system under the control policy.

The invention provides a method for inhibiting the line power oscillation of an interconnected electric power system via an energy storing device. The method adopts the power of the line connected with a bus where the energy storing device is as an input signal, obtains an equivalent conductivity through a measurement amplifying link, a stopping link and a phase shifting link, and then obtains an active power instruction value needing to be output by the energy storing device by multiplying the equivalent conductivity by the square of a terminal voltage. A transducer of the energy storing device generates an appointed active power to the power grid through a given power value so as to inhibit the power oscillation of the line. The invention does not depend on a remote communication; the controller has simple and reliable structure and easily adjusted parameters; and a 300MW energy storing device can inhibit a power oscillation with amplitude about 1400MW.

A detection and protection method for low frequency oscillation of a power system adopts changing track of tie line active power to detect the low frequency oscillation; condition one: the following criterions are satisfied at the same time, namely low frequency oscillation hard platen input, low frequency oscillation soft platen input, a device in starting state with |Pk-Peqv| more than Psetqd; condition two: the following criterions are satisfied at the same time: oscillating period is less than or equal to Tsetmax and more than or equal to Tsetmin, power oscillation range is more than or equal to an alarm threshold, oscillation number is more than or equal to alarm period number; alarm period number: oscillation number threshold fixed value of alarming; condition three: the following criterions are satisfied at the same time: oscillating period is less than or equal to Tsetmax and more than or equal to Tsetmin, power oscillation range is more than or equal to action threshold, oscillation number is more than or equal to action period number. The low frequency oscillation gives an alarm when the condition one and the condition two are satisfied at the same time; and the low frequency oscillation .performs protective action when the condition one and the condition three are satisfied at the same time.