251 results about "Synchronous oscillations" patented technology

The invention discloses an integrated multi-channel synchronous vibration data acquisition, monitoring and analysis diagnosis device. The data acquisition unit comprises a signal conditioning circuit, an anti-aliasing filtering circuit, a multi-channel synchronous sampling chip, a system control logic unit, a pulse-shaping circuit (16), a phaselocking frequency multiplication chip and a microprocessor CPU, wherein the system control logic unit comprises a channel configuration logic unit, a clock generation logic unit, a rotating speed measurement logic unit, a sampling control logic unit and a frequency divider, and the data acquisition unit (1) is directly connected with a plurality of eddy current vibration displacement sensors, ICP type piezoelectric vibration acceleration sensors or magnetoelectric vibration speed sensors, and has an interface of a single-channel direct-connected eddy-current, photoelectric or magnetoelectric key phase/revolution speed sensor and so on. The CPU core board is connected with a computer or a palm computer through a network and a USB or a serial interface and finishes the data acquisition for monitoring and analysis diagnosis.

A data emission/reception device by inductive coupling includes an inductive antenna circuit in which an antenna signal appears, a mechanism configured to for extracting a first periodic signal from the antenna signal, a synchronous oscillator receiving the first periodic signal and supplying a second periodic signal, and an active load modulation circuit configured to apply bursts of the second periodic signal to the antenna circuit. The device is configured to place the oscillator in the synchronous oscillation mode before each application of a burst of the second periodic signal to the antenna circuit, then place the oscillator in the free oscillation mode.

The invention relates to a generating set sub-synchronous oscillation suppression method adopting a full-controlled variable current device. The method uses the variable quantity of a rotating speed signal of a generating set as a control quantity, and performs filter, phase shift, proportional amplification and operation processing on the variable quantity of the rotating speed signal to acquire a control signal for controlling a variable current power unit by using a voltage synchronization signal as standard, then the full-controlled variable current device generates a sub-synchronous model modulation current, and the current affects the rotating speed of the generating set through a power transmission unit so as to achieve the aim of suppressing the sub-synchronous oscillation of the generating set. A controller comprises a plurality of signal processing subunits and a main control subunit, wherein each signal processing subunit comprises a filter module, a phase shift module, a proportional amplification module and an operation module; and the main control subunit accomplishes the control for the full-controlled device. The method can effectively suppress the sub-synchronous oscillation problem of a power grid system, has high response speed and high tracing precision, and can greatly improve the stability and reliability of a power grid.

A power distribution system comprising a point of common connection that receives electric power supplied by a first power generation system and a second generation system, with the second power generation system that comprises a renewable electric power generator; a transmission line operatively connected to the point of common connection for conducting the electric power between the point of common connection and an external AC electric network. The power distribution furthermore comprises a capacitive compensator connected in series with the transmission line to compensate for a reactive power component of the electric power conducted by the transmission line; and a shunt arranged flexible AC transmission system that mitigates a sub-synchronous resonance effect caused at least in part by the capacitive compensator. A flexible AC transmission system controller of the flexible AC transmission system comprises a damping effect on sub-synchronous oscillations included in the sub-synchronous resonance.

The invention discloses a power system sub-synchronous oscillation mode identification method which is characterized in that time complexity of the matching pursuit search process is reduced by aid of a particle swarm optimization, sub-synchronous oscillation signals are subjected to atomic decomposition in an optimized matching pursuit method, and atomic parameters are converted to sub-synchronous oscillation mode parameters after the optimum atom is searched. The power system sub-synchronous oscillation mode identification method can accurately identify power system sub-synchronous oscillation mode parameters, has good time-frequency characteristic, is favorable for deeply analyzing power system sub-synchronous oscillation characteristic, accordingly effectively restrains oscillation, and ensures stable operation of a unit and a power system.

The invention relates to a sub-synchronous oscillation suppression method based on controlled series compensation, which is based on the concept of damping torque, adopts a design method of phase compensation, and carries out proper amplification and phase shift processing on speed signal delta omega to generate an additional control signal to modulate a TCSC (Thyristor Controlled Series Capacitor) trigger angle. Therefore, equivalent reactance of the TCSC is changed, the TCSC can provide positive electrical damping in the entire sub-synchronous frequency range, and the problem of SSR (Sub-Synchronous Resonance) caused by series compensation capacitors can be thoroughly eliminated.

The invention provides on-line detection and filtering methods for a sub-synchronous oscillation part of a power system. The on-line detection method comprises: a power signal of a power grid is obtained and a power frequency component in the power signal of the power grid is filtered to extract a sub-synchronous oscillation component; and a detection analysis is carried out on sub-synchronous oscillation component by Fourier transform to generate a frequency, an amplitude, and a phase of the sub-synchronous oscillation component. According to the on-line detection and filtering methods provided by the embodiment of the invention, the sub-synchronous oscillation part in the power signal can be detected and filtered rapid and accurately.

The invention discloses a method for restraining sub-synchronous oscillation of a power system based on SSSC (Static Synchronous Series Compensator), comprising the following step of: generating an additional control signal, carrying out superposition on the additional control signal and an amplitude control signal, and then carrying pulse width modulation with a phase control signal to obtain a trigger pulse of a voltage source inverter in a static synchronous series compensator so as to control the output voltage of the static synchronous series compensator. The step of generating the additional control signal comprises the following steps of: collecting and filtering rotation speed difference signals of a generator in a power system to obtain all torsional vibration frequency signals of a generator shaft system, amplifying carrying out phase compensation on all the torsional vibration frequency signals and carrying out superposition to obtain additional control signals. With the method, the SSSC can supply positive electric damping near each torsional vibration mode of a generator unit through the control of the output reference voltage amplitude modulation coefficient ma and phase theta of the static synchronous series compensator of a flexible AC transmission device, thereby achieving the purpose of restraining sub-synchronous oscillation.

The invention discloses an injection synchronization narrowband regenerative phase-locked loop (ISNRPLL) circuit. The circuit includes a synchronous oscillation loop composed by the connecting of an injection synchronization narrowband regenerative voltage-controlled oscillator (ISNRVCO) and an exclusive-OR double frequency circuit; a phase-locked loop composed by the connecting of a digital phase detector, a charge pump and a loop filter, and a D type flip-flop for outputting data. The ISNRVCO does not ask much of the syntonic loop, and can be implemented by integrating inductance on a chip. Preferably, it can be integrated completely by using the deep submicron digital CMOS technology, so there are only a few external elements. Simulation shows that the capture range, capture time and phase noise etc. of the INSRPLL are all better than the conventional phase-locked loop circuit and can be used in GHz level high-speed clock recovery integrated circuit.

A control circuit for power system sub-synchronous oscillation dampening is described. The control circuit is configured to provide low impedance at sub-synchronous frequencies and high impedance at the fundamental frequency. The control circuit includes an input configured to receive a direct voltage value and a quadrature voltage value. Both the direct voltage value and the quadrature voltage value are based on a three-phase voltage. At least one controller configured to determine a direct current value and a quadrature current value based at least in part on the direct voltage value and the quadrature voltage value is included. The control circuit also includes an output configured to send the direct current value and the quadrature current value as feed forward signals to a control loop for the three-phase voltage.

The invention discloses a PMU and a method for achieving the on-line identification and alarm of the secondary synchronous oscillation. The PMU comprises an anti-aliasing filter module, an ADC sampling module, a synchronous sampling clock module, a DFT quadrature conversion module, a front-loading filter module, a phasor amplitude analyzing and processing module, and an uploading and processing module. The method comprises the steps of accurately calculating the synchronous phasor; pre-filtering the synchronous phasor; sampling and processing the calculated amplitude of the phasor; analyzing the frequency spectrum of the phasor amplitude; identifying the secondary synchronous oscillation according to the components of the frequency spectrum of the phasor amplitude; uploading the frequency components of the secondary synchronous oscillation and the alarm information to a dispatching master station. According to the technical scheme of the invention, the on-line identification and alarm of the secondary synchronous oscillation of the power system can be completed by the PMU. Through adopting the analysis on the frequency spectrum of measured high-density phasor data, the frequency components of the secondary synchronous oscillation can be accurately calculated. Therefore, the analysis monitoring accuracy and the analysis monitoring adaptability of the secondary synchronous oscillation are improved.

The invention discloses a sub-synchronous oscillation suppression method based on a fully-controlled inverter in the field of stabilization and control of power systems. The method comprises the following steps of: respectively extracting sub-synchronous frequency components from a generator rotating speed deviation signal, from line current d-axis components and from line current q-axis components; acquiring the voltage deviation value of a direct current capacitor of the fully-controlled inverter; and inputting the sub-synchronous frequency components into the fully-controlled inverter, generating corresponding voltage components, and generating current components which are used for suppressing sub-synchronous oscillation and stabilizing the direct current voltage of the fully-controlled inverter. The method is high in response speed, and the sub-synchronous oscillation caused by various reasons can be effectively suppressed.

The invention relates to a method and device for judging the stability of grid-connected sub-synchronous oscillation of a double-fed induction generator. The method comprises the steps of setting positive sequence harmonic voltage and positive sequence harmonic current of a stator of the double-fed induction generator according to stator phase-a voltage, stator phase-a current and rotor phase-a current of the double-fed induction generator; determining an output voltage expression of a current regulation link according to the positive sequence harmonic voltage and the positive sequence harmonic current; establishing a stator-side impedance analytical expression of the double-fed induction generator according to the positive sequence harmonic voltage, the positive sequence harmonic currentand the output voltage expression so as to obtain double-fed induction generator-side impedance characteristics; building a grid-side impedance model so as to obtain grid-side impedance characteristics; establishing a characteristic function equation of the double-fed induction generator-side impedance characteristics and the grid-side impedance characteristics; and solving the characteristic function equation so as to quantitatively judge the oscillation frequency and damping level of the double-fed induction generator. The oscillation frequency and damping level of can be quantitatively judged according to the method and device.

The invention belongs to the power system field and particularly relates to a method for improving the sub-synchronous oscillation (SSO) damping of a thermal power plant in a wind-thermal power series-compensation combined transmission system by utilizing a supplementary controller to modulate the reactive power output of a wind generation set. The method is based on the rotor current active and reactive decoupling control principle of a double-fed wind generation set, and introduces shafting rotational speed difference of a combined-transmission thermal power plant as the characteristic signal for designing a damping controller, and the output of the damping controller is modulation component under the control of rotor reactive power; and through the regulation on the reactive power of the wind generation set, the effect of enhancing the SSO damping of the combined-transmission thermal power plant is achieved. The invention is applicable to large-capacity wind-thermal power combined series capacitance compensation transmission occasions, so the SSO property of the thermal power plant can be improved, the electric power of a new energy resource is ensured to be transmitted safely, continuously and reliably, and the power system is also ensured to operate safely and stably.

The invention provides a method for quickly positioning the oscillating center of an electric system. In application aspects of inhibiting the oscillation of the system, coordinating the disconnection and the like, the accurate position of the oscillating center of the electric system often needs to be known. By the method, only the electric quantity and natural parameters of circuits need to be measured on the spot, the out-of-step oscillating center of the system can be accurately judged at the synchronous oscillation stage of the system, and the out-of-step quick disconnection criterion is realized based on the on-the-spot electric quantity. By the popularization and the application of the method for positioning the oscillating center based on the on-the-spot electric quantity, and the combination of the reliable quick disconnection criterion, the out-of-step disconnection control can be realized quickly, reliably and on the spot, and the method can also be adapted to different operating modes of the system, and realize the coordinating control of a plurality of disconnection devices.

The invention discloses a research method for analyzing subsynchronous oscillation characteristics of a direct-drive fan based on admittance. A direct-drive fan network side converter mainly comprisesa current controller, an outer ring voltage controller and a phase-locked loop controller. The method comprises the following steps of: the step 1, establishing an admittance model of a current controller; the step 2: on the basis of the step 1, establishing an outer loop voltage controller model, and correcting an admittance model; the step 3: based on the steps 1 and 2, establishing a phase-locked loop controller model to obtain a final direct-drive fan admittance model; the step 4: based on the step 3, evaluating the risk of the direct-drive fan generating sub-synchronous oscillation by utilizing the dissipative property of the admittance matrix; the step 5: establishing a power grid side input impedance matrix; and the step 6: based on the steps 3 and 5, predicting the grid connectionstability of the direct-drive fan by utilizing the stability criterion of the impedance matrix infinite-norm.

The present invention discloses a method and system for inhibiting double-feed wind turbine sub-synchronous oscillation. The system comprises a double-feed wind turbine, an active power damping controller and a reactive power damping controller. The active power damping controller and the reactive power damping controller are configured at the active and reactive power outer loop control modules of the rotor side inverter of the double-feed wind turbine. The active power damping controller is used for receiving an active power signal and outputting an active additional damping power signal to the active power outer loop control module after the active power signal is processed by a filtering module, a phase shift module, a gain module and an amplitude limiting module. The reactive power damping controller is used for receiving a reactive power signal and outputting a reactive additional damping power signal to the reactive power outer loop control module after the reactive power signal is processed by the filtering module, the phase shift module, the gain module and the amplitude limiting module. The double-feed wind turbine adjusts electrical damping according to the active additional damping power signal and the reactive additional damping power signal, and the sub-synchronous oscillation is inhibited.

The invention provides an anti-oscillating self-adaptive restraining system of subsynchronous oscillation of a large-size generator set. The anti-oscillating self-adaptive restraining system of the subsynchronous oscillation of the large-size generator set comprises a signal measurement control system and a static var compensator system, wherein the signal measurement control system is used for enabling measured torsional mode components of the large-size generator set to be through the processing of measurement, inverse amplification, lowpass filtering and self-adaptive control parameter generation in sequence to obtain a needed control signal and enabling the control signal to be input into the static var compensator system, the static var compensator system is used for controlling a triggering angle according to the control signal generated by the signal measurement control system so as to adjust equivalent admittance of the static var compensator system, then reactive power output by the static var compensator system is changed in a self-adaptive mode, corresponding damping torque is generated, and accordingly self-adaptive restraining of the subsynchronous oscillation of the large-size generator set is achieved. The anti-oscillating self-adaptive restraining system of the subsynchronous oscillation of the large-size generator set is capable of better restraining the occurrence of the subsynchronous oscillation of the large-size generator set.

The invention provides an analysis method for subsynchronous oscillation generated by grid connection of wind driven generators. The analysis method comprises following steps: establishing a linearized system model formed in such a manner that wind driven generators are connected to an infinite-bus power system via series compensation capacitance; calculating static stable points of the linearized system model; obtaining characteristic roots of a coefficient matrix of the linearized system model and left and right feature vectors thereof; obtaining all oscillation frequencies of the linearized system model according to characteristic roots and obtaining state variables related to the oscillation modes of the all the oscillation frequencies in the linearized system model; and varying parameter values of the state variables in order to acquire states in which all the oscillation frequencies vary with the corresponding state variables.The analysis method for subsynchronous oscillation generated by grid connection of wind driven generators has following beneficial effects: a quantitative analysis on subsynchronous oscillation generated by grid connection of wind driven generators can be made so that subsynchronous oscillation generated by grid connection of wind driven generators can be effectively monitored and addressed.

The invention discloses a risk analysis method of sub-synchronous oscillation generated by connection of a converter and an equivalent grid by considering phase-locked loop influence, and belongs to the technical field of electric power systems and automation thereof. The method includes the steps: building an equivalent grid and grid-connected converter electrical appliance link and control linksmall-disturbance mathematical model, and analyzing influence of detection errors of phase-locked loops under small disturbance on grid-connected converter control variables; correcting the grid-connected converter control link small-disturbance mathematical model according to the influence; determining system input voltage variables and output current variables, and getting a system dynamic impedance transfer function under small disturbance; drawing a system frequency impedance curve, and analyzing system sub-synchronous oscillation risks according to characteristics of the curve. A novel stability analysis method of a joint of VSC converter and a grid is provided, and the stability and the oscillating characteristics of the system can be simply and efficiently judged.

Multiple output power source apparatus enables to optimize efficiency for each output and to perform simultaneous shutdown and synchronous oscillations between the outputs. Power source circuits of various types connected to a power source are provided, and those power source circuits have a function of outputting an abnormality signal to other power source circuits when an abnormality occurs in the own circuit and shutting down the operation of the own circuit by an abnormality signal from other power source circuits and a function of outputting a synchronous oscillation signal synchronized with a switching oscillation frequency used for controlling the own circuit to other power source circuits and conducting synchronous control of the switching frequency used for controlling other power source circuits.

The present invention provides a doubly-fed wind farm sub-synchronous oscillation SVG suppressing method and a device. The method comprises the following steps: acquiring voltage signal(s), current signal(s) and wind farm parameters of the output end(s) of a doubly-fed wind farm, wherein the wind farm parameters comprises a wind speed and a power-transmission line series compensation degree; determining active power signal(s), voltage oscillation amplitude(s) and current oscillation amplitude(s) according to the voltage signal(s) and the current signal(s); determining the working mode of a SVGcontroller; determining module parameter(s) of the SVG controller according to the determined working mode, the voltage oscillation amplitude(s), the current oscillation amplitude(s), oscillation frequencies, the wind farm parameters and a pre-established SVG parameter table, wherein the SVG parameter table is a pre-established corresponding table of the SVG function module parameter(s) and system operation information under different working modes; and performing sub-synchronous oscillation SVG suppressing on the wind farm by using the SVG controller with the determined parameter(s). According to the method, sub-synchronous frequency band signal(s) are filtered from sampling signal(s), and the doubly-fed wind farm is subjected to sub-synchronous oscillation SVG suppressing by using the voltage(s) and the active power(s).

The invention provides a novel subsynchronous oscillation damping controller which adopts the structure that a capacitor is connected with an inverter in series or in parallel, or the controller is only formed by the inverter; according to the preset control policy of the inverter, the subsynchronous oscillation damping controller takes on the characteristics of the preset impedance to absorb, damp or bypass subsynchronous frequency component, thus increasing the electrical damping of the corresponding subsynchronous frequency and finally achieving the aim of inhibiting subsynchronous oscillation (SSO) or subsynchronous resonance (SSR) of an electric power system.

The invention discloses a multi-mode additional sub/super synchronous oscillation control method and control system. The method comprises the following steps: collecting total three phase current ic at a fan side or total three phase current iL at a circuit side; according to the total three phase current ic at the fan side or the total three phase current iL at the circuit side, calculating to obtain multiple mode control signals; performing addition operation on the multiple mode control signals, so as to obtain an additional control signal; performing amplitude limiting processing on the additional control signal, so that the amplitude value of the additional control signal is located in a first preset range. The method can effectively inhibit sub/super synchronous oscillation of a system when a wind power plant is connected.