221results about How to "Eliminate harmonics" patented technology

The invention provides a compensation method of direct current (DC) voltage fluctuation of a photovoltaic grid-connected inverter, and the method can be used for improving the quality of the grid-connected current through compensating an input DC side secondary pulse voltage by adding a DC voltage pulse compensation module in a DC / AC (direction current / alternating current) high-frequency link, and eliminating a grid-connected current harmonic wave caused by the DC voltage pulse. The control performance of the system can be improved without adding a filter device and adding any extra appliance.

A filter uses a special autotransformer that has a ferromagnetic core with a plurality of legs and flux return bars. A first coil is located on one leg, and a second coil is located on the same leg, but spaced from the first coil. The first coil and at least part of the second coil are connected in series to receive distorted alternating current and at least that part of the second coil is connected to an output terminal. Between the coils and extending at least part of the way from the first leg to an adjacent leg is a magnetic shunt assembly to divert part of the flux generated in the first coil by the alternating current so that that part does not link with the second coil. An air gap is located to link with the second coil to create an inductor in that coil by flux in the second coil, and a capacitor is connected across the second coil to tune it to the fundamental frequency of the alternating current and substantially reduce harmonics in that current.

The linear dynamo used in wave power generation relates to a permanent magnetic linear synchronous motor, which comprises a primary pole and a secondary pole. The primary pole of the permanent magnetic linear synchronous motor comprises two primary iron cores (2), a primary tri-phase winding (3). The primary tri-phase winding (3) is bedded in the wire ducts of the primary iron cores (2). The secondary pole comprises a secondary permanent magnet (1) which is arranged on a buoy (6) by a spring (5). The bottom of the container which contains the linear dynamo is fixed on the seabed. Both the primary pole and the secondary pole of the linear dynamo are in rectangle shape. The secondary permanent magnet (1) is positioned between the two primary iron cores (2). And air gaps (4) are provided between the secondary permanent magnet (1) and the two primary iron cores (2). The invention uses the linear dynamo instead of traditional rotating dynamo, with non-contact driving, reduces the dielectric loss and increases the electricity generation efficiency; sustains the pressure of wave, with strong structure; has the advantages of no poisonous gas released, no extra noise, environment-protection and health, with the cost as low as common electricity generation.

The invention discloses a finite-control-set model predictive current control method of a five-phase permanent-magnet synchronous motor. The finite-control-set model predictive current control method comprises the steps of respectively mapping a voltage, a current and magnetic flux of the five-phase permanent-magnet synchronous motor under a natural coordinate system to two orthogonal rotating coordinate systems of d1-q1 and d3-q3 according to extended Park rotation transform; constructing an input voltage vector control set which is used in an FCS-MPCC (Finite-Control-Set Model Predictive Current Control) algorithm again; solving amplitude of U<'> of the (d1-q1) coordinate system and an acting time allocation proportion of two basic voltage vectors required for forming a virtual vector; constructing a target function in the FCS-MPCC algorithm of the five-phase permanent-magnet synchronous motor; selecting the virtual voltage vector which enables the target function to be minimum as control output quantity; and performing steps of pulse sequence generation and design on the virtual voltage vector. By the finite-control-set model predictive current control method, a low-order harmonic component of a five-phase motor current caused by a harmonic (d3-q3) space is eliminated, the algorithm is enabled not to require excessive calculation quantity, a digital processor is liable to implement, the difficulty of program design is reduced, and the running power consumption of a digital chip is reduced.

A filter uses a special autotransformer that has a ferromagnetic core with a plurality of legs and flux return bars. A first coil is located on one leg, and a second coil is located on the same leg, but spaced from the first coil. The first coil and at least part of the second coil are connected in series to receive distorted alternating current and at least that part of the second coil is connected to an output terminal. Between the coils and extending at least part of the way from the first leg to an adjacent leg is a magnetic shunt assembly to divert part of the flux generated in the first coil by the alternating current so that that part does not link with the second coil. An air gap is located to link with the second coil to create an inductor in that coil by flux in the second coil, and a capacitor is connected across the second coil to tune it to the fundamental frequency of the alternating current and substantially reduce harmonics in that current.

The invention discloses an active filter current self-adaptive control method based on fuzzy PI composite control, and the method not only utilizes the advantage that fuzzy control does not depend on system parameters but also utilizes the capability of self-adaptive control of overcoming the uncertainty of a controlled object as well as the quick and precise tracking performance of the self-adaptive control to compensate for modeling errors and external disturbance on line in real time, so that compensation current quickly and accurately tracks a command current signal while capacitive voltage on a direct current side precisely tracks the set voltage, the purpose of eliminating harmonic wave is achieved, the compensation performance of an active power filter and the robust performance of the system can be greatly improved, the control goals of quickness and high adaptability are achieved, and the quick popularization of the active power filter is facilitated.

The method of determining a speed of rotation of an axially symmetrical vibrating sensor having a vibrating member associated with control electrodes and with detection electrodes for generating vibration presenting an elastic line possessing periodicity of order n and having a position that is variable as a function of the rotation of the sensor, the method comprising the steps of:performing evaluation of the speed of successively for a predetermined number of positions of the vibration relative to the electrodes; the positions being geometrically offset relative to each other and the vibration being moved from one position to another by applying a precession command using a pre-established scale factor;determining a speed of rotation in function of the evaluations.The device for implementing such method.

The invention relates to an adaptive RBF (radial basis function) neural network control technique for three-phase parallel active filters, belonging to an active power filter control technique. The invention provides an adaptive RBF neural network control method for three-phase parallel active power filters, which is used for controlling a compensation current output by a three-phase parallel active power filter through a controller, thereby eliminating harmonic waves and improving the power supply quality of a power grid. According to an adaptive control rule provided by the invention, the boundedness of weights is ensured, and the stability of the controller is proved by using a Lyapunov stability theory; and simulation results show that the control method effectively reduces the distortion factor of harmonic waves and is good in dynamic response, and when parameters change, the controller has good robustness and adaptability.

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.

An apparatus for characterising an analog to digital converter, comprising a signal generator for supplying an input signal having a first sinusoidal component to an analog to digital converter and an acquisition device for receiving and storing a plurality of output values from the analog to digital converter, and a data processor arranged to examine the output values in order to determine discrepancies due to bit weight errors and to calculate estimates of the bit weights or bit weight errors.

The invention discloses a high-frequency distribution transformer, which comprises a three-phase voltage high-frequency modulation circuit, high-frequency phase-shifting transformer, a multi-pulse rectifying circuit, and an inverter output module, wherein each phase of bridge arm of the three-phase voltage high-frequency modulation circuit comprises n serially-connected single-phase rectifying modules and inverter modules of which the number is m times of that of the single-phase rectifying modules. Output voltage of the high-frequency distribution transformer can be adjusted by adjusting the duty cycle of the inverter modules in three-phase voltage high-frequency modulation circuit; the operation of the high-frequency phase-shifting transformer in a high-frequency modulation mode can effectively reduce the volume and weight of the whole distribution transformer; and the distribution transformer can solve the flow equalization problem of the multi-pulse rectifying circuit, allows a power factor on the line side to be close to 1 and substantially eliminates the current harmonics on the line side. The high-frequency distribution transformer is applicable to the prior power frequency power distribution system and multiphase power distribution system as well as high-frequency power distribution system such as 400Hz ship power distribution system.

The invention discloses a control method for high-power reactive and harmonic dynamic hybrid compensation method. The hybrid compensation system comprises an SVG (static var generator), a TSF (thyristor switched filter) group and a controller, and the SVG and TSFs are parallelly connected to a grid. The three-phase current of the grid between the SVG and the TSFs is taken as a detection object, voltage and current values collected by sensors are processed through the controller, switching signals of the TSFs are acquired according to hybrid logic judgment, most of the reactive power of loads is compensated in a graded manner, and specific subharmonic is filtered out; control parameters of the SVG are acquired according to an instantaneous-power theory, and the surplus reactive power and harmonic of the loads are continuously compensated. A cost-effective scheme for rapid continuous compensation of the high-power reactive and harmonic is provided, impact of switching of passive equipment on the grid can be completely avoided, and harmonic current is avoided flowing to the grid, so that the control method is energy saving, emission reducing, green, environment friendly, good in social and economical effectiveness, wide in application range and especially applicable to the field of oil drilling.

The invention discloses a method for controlling an active power filter based on model reference self-adaptive fuzzy control. The method comprises the steps that (1) a dynamic model of the active power filter is established; (2) a reference model is selected and a state space model of the reference model is shown as the formula (14); (3) a generalized state tracking error of the active power filter is defined as that e=xm-x (15); (4) T-S fuzzy approaching output of a non-linear portion of the active power filter is designed; (5) a current self-adaptive controller, composed of a T-S fuzzy control item and a sliding mode control item, of the active power filter is designed; (6) a system is proved to be stable through the stability theory and it is guaranteed that the tracking error e converges at zone; (7) a PI controller is used for controlling voltage across the direct current side of the active power filter. According to the method, the compensation performance and the robustness of the active power filter can be greatly improved, the power quality is effectively improved, and the method is beneficial to rapid popularization of the active power filter.

The invention discloses a filtering antenna capable of restraining high frequency harmonic waves. The filtering antenna comprises a dielectric plate, a stepped-impedance resonator, a stepped-impedance symmetrical oscillator, a low-pass filter and a feed unit; the stepped-impedance resonator and the stepped-impedance symmetrical oscillator are both arranged on the top layer of the dielectric plate; the stepped-impedance resonator is close to the stepped-impedance symmetrical oscillator to form an antenna unit; an upper conductor of the low-pass filter is arranged on the top layer of the dielectric layer, and is connected with a left arm of the stepped-impedance symmetrical oscillator; a lower conductor of the low-pass filter is arranged on the bottom layer of the dielectric plate and connected with a right arm of the stepped-impedance symmetrical oscillator through a via hole; an upper conductor of the feed unit is arranged on the top layer of the dielectric plate and connected with the upper conductor of the low-pass filter; a lower conductor of the feed unit is arranged on the bottom layer of the dielectric plate and connected with the low conductor of the low-pass filter; and the projection of the upper conductor of the feed unit on the bottom layer of the dielectric layer is positioned in the center of the lower conductor. The filtering antenna capable of restraining high frequency harmonic waves has the characteristics of high rectangle degree and capability of effectively restraining harmful harmonic waves.

The invention relates to a wind-power-station power output counterbalance system which comprises a wind speed acquisition and conversion circuit, an actual wind-power-station analog module, a differential amplifying circuit, a comparison circuit, a control circuit, a current transformer and a superconducting magnetic energy storage device, wherein the superconducting magnetic energy storage device comprises a chopper, a wave filter and a feedback circuit. The working method of the wind-power-station power output counterbalance system comprises the following steps: (1) converting a wind signal into an electric signal; (2) producing a signal which has the same output variation law as the actual wind power station; (3) processing by the differential amplifying circuit; (4) performing the circuit comparison with the power signal output by the superconducting energy storage device; (5) and controlling the conduction of a triode in the current transformer, and outputting power of the multiple superconducting energy storage devices. The invention has the advantage of storing the electric energy by utilizing the superconducting magnet, thereby greatly enhancing the energy storage density, reducing the energy consumption and realizing the synchronous inhibition on the power output fluctuation of the wind power station.

The invention relates to the field of ship electric propulsion, in particular to a ship electric propulsion system with harmonic suppressing and regenerative braking functions and a control method. The system is mainly composed of an IGCT control and drive system, a signal acquisition and control system, a composite energy storage system and a two-way inversion rectification system installed between a motor and a ship power grid. A double-three-level diode clamp type topological structure is adopted in the two-way inversion rectification system in the ship electric propulsion system, the SVPWM control technology is selected in the control method, and therefore the harmonic suppressing and regenerative braking functions are achieved. The composite energy storage system in the ship electric propulsion system can be used for absorbing energy generated in the ship braking process, can also be used for leveling fluctuations of the ship power grid and has the ship power grid stabilizing effect. The ship electric propulsion system has the important application value for improving the electric energy quality of the ship power grid and increasing the energy use rate.

The invention discloses an electric power and electric quantity measuring method based on frequency domain analysis and sequence component analysis, relating to the technical field of electric power and electric quantity measurement. The method comprises the following steps: firstly, processing signals of the same path of voltage and current to form analog signals, and carrying out anti-aliasing filtering on the processed voltage signals and the processed current signals to form sampling signals; carrying out analog-to-digital conversion on the sampling signals to form digital signals; computing the digital signals after analog-to-digital conversion by utilizing a discrete Fourier transformation computation method through a processor; carrying out decomposition computation of positive sequence, negative sequence and zero sequence on fundamental wave signals by utilizing a sequence component decomposition method through the processor; and comprehensively computing the digital signals after DFT and sequence component decomposition to form the following parameters: harmonic active power, positive sequence active power, negative sequence active power, zero sequence active power, total active power and electric quantity. The invention has high measuring accuracy and provides an effective method for power consumers and power supply companies to measure power consumption of electric loads comprehensively and accurately.

The invention discloses a phase-locked loop and a phase locking method. The phase-locked loop comprises a Clark transformation module, a QSG module, a PNSC module, a synchronous rotating coordinate system PLL module, an HE module and an AFRC module. The novel PLL can accurately operate under the situations of unbalanced voltage and serious voltage harmonic and frequency variation. The provided QSG and AFRC can accurately detect the positive-sequence power grid voltage sequence, the HE can well eliminate harmonic waves under the condition of serious power grid pollution, the AFRC make the frequency self-adapt quickly and be smooth, and the PLL can be achieved in the case that the power grid voltage has frequency fluctuation, imbalance and harmonic waves at the same time; the digital implementation of the improved digital PLL is performed through a method using a Tustin predeformation and increment algorithm to discretize, and the accuracy of the harmonic broadband of the power grid voltage can be ensured.

The invention provides a specific harmonic wave eliminating system comprising a PWM (Pulse Width Modulation) inverter and a main control unit which controls the PWM inverter to convert direct current into alternating current and supply power to an alternating load; the main control unit comprises a obtaining sub-unit, an establishing sub-unit, a computing sub-unit and a control sub-unit; the obtaining sub-unit is used for obtaining a voltage output waveform of the PWM inverter; the establishing sub-unit is used for establishing a bipolar specific harmonic elimination mathematical model according to the voltage output waveform of the obtaining sub-unit; the computing sub-unit is used for computing out an exact solution of a switching angle by using a homotopy differential method and a Newton iteration method according to the bipolar specific harmonic elimination mathematical model in the establishing sub-unit; and the control sub-unit is used for controlling the on-off time of a switching tube in the PWM inverter according to the exact solution of the switching angle in the computing sub-unit. The system can effectively eliminate the influence of a harmonic wave.

An optical storage microgrid system control method is characterized by utilizing an energy management system of an optical storage microgrid system to detect the harmonic content and the power factors at a point of common coupling of the optical storage microgrid system, adopting a multiple proportion resonant controller under the rotational coordinates to realize the astatic control of a fundamental current and a harmonic current, and optimizing and controlling an energy storage converter of the optical storage microgrid system to realize the reactive current compensation and harmonic current compensation functions of the optical storage microgrid system under a grid connected mode, eliminate the specified harmonic in the optical storage microgrid system and improve the electric energy quality of the optical storage microgrid system.

The invention discloses a power frequency online anti-icing and de-icing method for a power transmission line, which comprises the steps which are as follows: three sets of dynamic reactive power compensation devices are connected with a power transmission line between a left side electric power substation and a right electric power substation which are adjacent; a temperature sensor is arranged on the power transmission line; when the temperature detected by the temperature sensor is lower than 0 DEG C, a controller controls the three sets of dynamic reactive power compensation devices into an anti-icing and de-icing working state; the reactive power compensation device at the left side generates a capacitive reactive current; the dynamic reactive power compensation device at the right side generates a capacitive reactive current; and the dynamic reactive power compensation device in the middle generates an inductive reactive current. The power frequency online anti-icing and de-icing method for the power transmission line can automatically implement anti-icing and de-icing under the conditions that the line is not stopped and the power supply is not influenced, guarantees the line from icing, guarantees the stability and safety of a power supply system under extreme disaster weather conditions such as freezing rain, ice and snow, and improves the running economical efficiency of the power system.

The invention discloses a method for achieving an arc suppression coil function by using a high-voltage cascading type SVG. The method includes the steps of 1) monitoring whether a system runs normally or not, 2) when the system runs normally, starting a reactive compensation mode and a harmonic suppression function mode, controlling a cascading type SVG converter to perform system reactive compensation and harmonic cancellation, meanwhile, monitoring bus voltage, judging whether a neutral point of the bus voltage deviates and generates zero-sequence voltage or not, if the neutral point of the bus voltage deviates and generates the zero-sequence voltage, executing the step 3), and otherwise, keeping the current operation state, 3) starting an arc suppression coil function mode, controlling the cascading type SVG converter to compensate ungrounded phase grounding capacitive current, and meanwhile monitoring the bus voltage, judging whether deviation and the zero-sequence voltage of the neutral point of the bus voltage disappear or not, if deviation and the zero-sequence voltage of the neutral point of the bus voltage disappear, executing the step 2), and otherwise keeping the current operation state. The method has the advantages of being simple to achieve and capable of adjusting automatically, having the dual function modes, and being flexible in mode conversion.

The invention provides a petroleum fracturing direct-current transmission power system. The system comprises a power generation subsystem, a power transmission and distribution subsystem, a power transformation and distribution subsystem, a driving subsystem, an energy storage subsystem and an energy management subsystem; a power generation system and a driving system which are mutually independent in traditional electric fracturing are combined into a whole, and is unified as direct-current voltage in the form of electric energy; the direct current is transmitted to the driving end of each electric device through a bus; a driving device supplies power to the device through an inverter or a switch; and therefore, comprehensive utilization of energy of a whole well site is achieved.

The present invention relates to the field of artificial intelligence, and provides a method, a device and equipment for constructing a speech recognition model and a storage medium. The method comprises the following steps: acquiring a plurality of training speech samples; constructing the speech recognition model by using an independent convolution layer, a convolution residual layer, a full connection layer and an output layer; inputting speech training information to the speech recognition model, updating a weight value of neurons in the speech recognition model with the speech informationand a text label corresponding to the speech information through a natural language processing NLP technology, and then obtaining a target model; evaluating an error of the target model by L(S) = -ln[Pi]<(h(x),z) being an element of a set S> p(z|h(x))= -sigma<(h(x),z) being an element of a set S> ln p(z|h(x)); adjusting the weight value of the neurons in the target model until the error is less than a threshold value; setting the weight value of the neurons with the error less than the threshold value as an ideal weight value; deploying the target model and the ideal weight value on a client.The method of the present invention reduces influence of tone in the speech information on a predicted text and computation burden during recognition process in the speech recognition model.

The invention discloses a detection method and device of low frequency oscillation of an electric power system. The method comprises steps of firstly converting a power frequency signal collected by the electric power system into a power curve; calculating the extreme value of the power curve and determining a wave crest point and a wave trough point; calculating a half period range and a whole period range corresponding to a set frequency range, calculating a cycle of a to be detected low frequency component, after a wave crest / wave trough Bk is detected, determining whether a wave crest / wave trough Bj exists or not within the range of a half period after the Bk, determining whether a wave crest / wave trough BL exists or not within the range of a whole period after the Bk if the wave crest / wave trough Bj exists within the range of the half period after the Bk, and taking a signal determined by the Bk, Bj and BL as a cycle of the to be detected low frequency component if the wave crest / wave trough BL exists within the range of the whole period after the Bk; and finally calculating the frequency and the amplitude of the to be detected low frequency component By the abovementioned processes, the invention achieves objects of reducing the operand and saving the operation time.

The invention discloses a 12-pulse-wave self-coupling phase shift rectifier transformer, wherein a transformer core adopts a three-phase column structure, three phases of windings are connected in a self-coupling and bending manner, any phase of winding of the transformer comprises five windings wound on different iron columns, any phase of winding comprises an input voltage and two output voltages, the phase difference between the two output voltages is 30 degrees, and the input voltage and the output voltage can meet any ratios of transformation. Based on the electromagnetic filter principle, the 12-pulse-wave self-coupling phase shift rectifier transformer can inhibit the distortion of the output voltage of the transformer, eliminates harmonic waves of 3 times, 5 times, 7 times, 17 times and 19 times, and greatly improves the influence of a secondary side harmonic wave on a primary side power grid, and meanwhile, the self-coupling connection method of the windings further effectively reduces the size and the manufacturing cost of the transformer.

A method for detecting damage in a bearing of a wind turbine includes collecting vibration data relating to the bearing. Another step includes storing the vibration data in a memory device. The method also includes identifying a plurality of harmonics in the vibration data that are indicative of bearing damage. Further, the method includes eliminating harmonics within a specified frequency proximity to areas of high energy content representative of normal gearbox operation. Moreover, the method includes determining at least one of increases in energy or a variance of the energy within each of the remaining harmonics and calculating a damage factor of the bearing as a function of a least one of the increases in energy or the variance of the energy within each of the remaining harmonics. Accordingly, the method includes comparing the damage factor to a predetermined damage threshold, wherein a damage factor exceeding the predetermined damage threshold may be indicative of a damaged bearing.

The present invention relates to a converter neutral-point voltage balance control method based on SHEPWM. The method comprises the following steps: 1, building a three-level neutral-point clamped converter specific harmonic wave elimination control method mathematics model, and solving non-linear transcendental equations; 2, performing the vector quantization of the three-level neutral-point clamped converter SHEPWM; and 3, dynamically transforming the switch state of the SHEPWM, and replacing the small vector corresponding to the SHEPWM with another small vector which is paired with the small vector corresponding to the SHEPWM. The converter neutral-point voltage balance control method based on SHEPWM is configured to replace the small vector corresponding to the SHEPWM with another small vector which is paired with the small vector corresponding to the SHEPWM through dynamically transforming the switch state of the SHEPWM while eliminating the special low-order harmonics so as to effectively control the neutral-point voltage balance, improve the quality of the output waveform and decrease the distortion of the total harmonic distortion on the premise without influence of eliminating the line voltage special harmonics.

The invention provides a soft startup device for single-phase motor. Wherein, the motor at least includes a primary winding connected with a startup winding in series, and a running capacitor paralleled with windings. The provided soft startup device comprises: a reactor connected with primary winding in series, and an ac contactor with coil paralleled with the startup winding to work and bypass the reactor when motor rotation speed up to threshold. This invention reduces startup current and time.

The invention provides a unipolar SPWM (Sine Pulse Width Modulation) dead-time-free modulation method of an H-bridge cascade multilevel converter. The method realizes the dead-time-free control of a chopper arm of the H-bridge converter through a digital logical circuit and certain dead time is set for a direction arm of the H-bridge converter only at every half working frequency cycle, so that the problem that the voltage on the direct-current side of the H-bridge cascade multilevel converter and the harmonic content of output current is influenced due to the dead time can be ignored. By introducing a control signal, the direction arm and the chopper arm realize interchange by taking two-divided frequency of working frequency as a cycle, the problem that the action of the switching device of the H-bridge converter is unbalanced under the situation of unipolar SPWM dead-time-free control is effectively solved, the thermal stability is good and the heat dissipation design and the long-term operation of the device are facilitated.