10results about How to "Reduce harmonic interference" patented technology

The invention relates to the technical field of electric power operation and maintenance, and particularly discloses a middle and low voltage distribution network fault online detection method based on cross wavelet coherence analysis, which comprises the following steps: carrying out cross wavelet coherence analysis on zero-sequence current of all lines, finding out a common high-energy frequency band, and selecting the line current with the highest energy as a detection object; monitoring the selected current sequence by using a sliding window method, and dividing the current sequence into small time periods for detection; analyzing the current waveform in each time window through a fractal theory, calculating the fractal dimension of the current waveform, and constructing a multi-scale fractal dimension feature vector; and using a Dirichlet process Gaussian mixture model to perform clustering analysis on the feature vectors so as to accurately identify faults. According to the medium and low voltage power distribution network fault online detection method based on cross wavelet coherence analysis, the optimal frequency band / scale can be determined in a self-adaptive mode, rapid fault detection is achieved in a short time window, and therefore the efficiency and accuracy of fault detection are remarkably improved.

The utility model discloses a direct-drive electro-magnetic annular synchronous motor, and belongs to the technical field of large-scale synchronous motors. The motor comprises a split stator which is formed by splicing and fixing a plurality of stator petals along the circumferential direction; the block magnetic poles form a motor rotor, a plurality of independently-formed magnetic pole units are arranged at intervals in the circumferential direction, and each magnetic pole unit is directly and fixedly installed on the outer wall of the load rotating cylinder; the supporting and sealing structure is arranged at the axial end part between the split stator and the block magnetic pole and is used for sealing a gap between the split stator and the block magnetic pole; and the collector ring and brush carrier system is arranged at one axial end of the motor, and the output end of the collector ring and brush carrier system is electrically connected with the excitation windings of the block magnetic poles. According to the utility model, the split stator and the block magnetic pole structure are adopted, so that the transportation and field installation of the ultra-large motor are facilitated; the rotor is directly mounted on the outer wall of the milling cylinder to realize direct drive, a gear transmission link is omitted, the transmission efficiency is high, and operation is stable; a multi-layer sealing structure adapts to a high-dust environment, and the reliability is high; the speed regulation performance is good and the maintenance is convenient.

This invention provides an output impedance calculation device, which includes: a control unit, an adjustment unit, a LORA transmitting unit, a first impedance calculation unit, a second impedance calculation unit, a matching unit, and a transmitting antenna. The control unit is used to transmit wireless signals; the LORA transmitting unit is used to convert wireless signals into LORA signals; the first impedance calculation unit is used to calculate the input impedance based on the LORA signals; the second impedance calculation unit is used to calculate the output impedance based on the LORA signals; the control unit is used to calculate the reflection coefficient based on the input and output impedances, and to calculate the standing wave ratio based on the transmission coefficient; the adjustment unit is used to adjust the impedance in the circuit based on the standing wave ratio and the reflection coefficient, thereby achieving impedance matching and balance between the input and output terminals of the line, improving the output quality of radio signals, reducing the overall output power consumption, and reducing harmonic interference.

The invention relates to the field of three-phase power supply phase calculation methods, and discloses an ATSE three-phase power supply phase calculation method based on a Goertzel algorithm, which comprises the following steps of: setting an initial frequency of frequency detection, a period number k = 1 and a sampling number N of each period; common variables of the Goertzel algorithm are calculated; carrying out resampling operation on the AD data according to a set frequency; sequentially carrying out convolution operation on the AD data after resampling; after N sampling points of one period of data are calculated, second-step operation is carried out to obtain Yn containing amplitude-frequency information under the target frequency; and calculating phase information of the Yn according to the real part and the imaginary part of the Yn. By collecting AD data of three-phase voltage of the power supply, phase information of three phases is calculated in sequence, phase information of the three-phase power supply is obtained, and then the phase information of the three-phase power supply is obtained through data integration, so that comprehensive mastering of the overall phase state of the three-phase power supply is achieved, and accurate phase information is provided for ATSE control logic.

The utility model provides a manual lifting frequency conversion control system applied to an ocean platform, which belongs to the field of manual lifting frequency conversion control and comprises a cabinet body, a control loop, a plurality of mounting beams and a plurality of copper bars are arranged in the cabinet body, and an incoming line busbar clamp, an outgoing line busbar clamp, a circuit breaker, a reactor, a frequency converter module and a filter are mounted on each mounting beam. The wire inlet end of the circuit breaker is connected with the wire inlet busbar clamp through a copper bar, the wire outlet end of the circuit breaker is connected with the fast-acting fuse through a copper bar, meanwhile, the fast-acting fuse is installed at the wire inlet end of the electric reactor, and the wire outlet end of the electric reactor is connected with the wire inlet end of the frequency converter module through a copper bar. The wire outlet end of the frequency converter module is connected with the wire inlet end of the filter through a copper bar, and the wire outlet end of the filter is connected with the wire outlet busbar clamp through a copper bar. The device is convenient to maintain, facilitates on-site adjustment and maintenance of a control loop, and can design a harmonic processing scheme in a customized manner according to the characteristics of serious harmonic waves and large harmonic interference of a platform power grid under the working condition of a long cable.

The invention relates to the technical field of switching power supplies, and discloses a two-stage active power factor correction circuit and a switching power supply in order to solve the problems of low power factor and high harmonic pollution caused by the fact that the input of the switching power supply is alternating current. The circuit comprises an electromagnetic interference filter, a rectifier bridge, a PFC booster circuit, an LLC half-bridge resonance compensation circuit and a controller which are connected in sequence. The PFC booster circuit is used for boosting the voltage output by the rectifier bridge to the high-voltage direct-current bus voltage; the LLC half-bridge resonance compensation circuit is used for converting the high-voltage direct-current bus voltage output by the PFC booster circuit into stable low-voltage direct current required by a load by adjusting the switching frequency of the LLC half-bridge resonance compensation circuit; the controller is used for controlling the working mode of the PFC booster circuit according to the magnitude of the output current of the LLC half-bridge resonance compensation circuit; meanwhile, the output voltage of the LLC half-bridge resonance compensation circuit is sampled, and the switching frequency of the LLC half-bridge resonance compensation circuit is adjusted according to feedback of the output voltage. By adopting the circuit, the power utilization efficiency of power equipment is improved, and harmonic interference is reduced.

The utility model relates to the technical field of photovoltaic power generation, and discloses a high-capacity photovoltaic boost transformer station, which comprises a low-voltage cabinet, a transformer chamber and a medium-voltage chamber, a power distribution area, a confluence area and a detection area are arranged in the low-voltage cabinet, so that all low-voltage elements can be integrally arranged according to functions, and an external cabinet body of the medium-voltage chamber is provided with a data acquisition module and a heat dissipation module; the medium-voltage chamber comprises a medium-voltage incoming and outgoing line cabinet, a medium-voltage circuit breaker switch cabinet and four medium-voltage PT cabinets. The medium-voltage PT cabinets comprise an incoming line cabinet, an internal connection transformer switch cabinet, an outgoing line cabinet and a metering protection PT cabinet used for metering protection. According to the high-capacity photovoltaic boosting transformer substation, the low-voltage cabinet adopts a partition design, so that the wiring distance is shortened, the integration level is improved, meanwhile, the data acquisition module is externally arranged, so that electromagnetic interference is reduced, high-precision measurement and accurate forwarding of signals are ensured, and precise metering protection of the medium-voltage cabinet is realized through the PT cabinet for metering protection.

The utility model relates to a communication anti-electromagnetic interference technology of numerical control equipment, in particular to an anti-electromagnetic interference device of USBCNC (Universal Serial Bus Computerized Numerical Control) numerical control equipment, which is formed by matching a USB isolation chip ADUM4160 with a power supply filter EMI (Electro-Magnetic Interference) module, the power supply filter EMI module provides a working power supply for the equipment, meanwhile, the power supply filter EMI module is connected with a DC5V switching power supply module, and the DC5V switching power supply module is connected with the USB isolation chip ADUM4160. The DC5V switching power supply module is electrically connected with the main control board which is formed by taking an ADUM4160 chip as a core, and provides a DC5V power supply required by the USB isolation main control board; the USB isolation chip ADUM4160 chip circuit main control board is provided with two USB communication ports, and a USB input interface of the ADUM4160 main control board is connected with a USB interface of a computer; and the USB output interface of the ADUM4160 main control board is connected with the input USB port of the USBCNC shaft motion controller. According to the utility model, electromagnetic interference except for useful signals in the machining process of the numerical control equipment can be effectively filtered, the anti-electromagnetic interference effect of the numerical control equipment of the USBCNC control system is improved, and the operation stability and safety of the equipment are further improved.

The utility model provides a kind of double-frequency wave trap ultra-wideband antenna based on double C-shaped structure, including dielectric substrate, C-shaped radiating patch unit, microstrip transmission line and two coplanar waveguide ground planes.C-shaped radiating patch unit is printed in the upper surface middle part of dielectric substrate, including first C-shaped radiating patch and second C-shaped radiating patch;Microstrip transmission line is printed on the upper surface of dielectric substrate, and microstrip transmission line is guided to C-shaped radiating patch unit from the edge of dielectric substrate and is connected therewith;Two coplanar waveguide ground planes are printed on the upper surface of dielectric substrate, and are symmetrically arranged on the both sides of microstrip transmission line and are provided with first gap between microstrip transmission line.