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605 results about "Phase selection" patented technology

Symbol timing synchronizing apparatus for complete digital receiver

A complete digital receiver symbol timing synchronizing apparatus of the digital communication technique domain, includes an interpolator, a sampling clock frequency error estimation module, a loop filter, an interpolation controller, a sampling clock phase error calculation module and a sampling phase selection controller, wherein, the sample value of the system over-sampling is taken as the input of the interpolator; the sample value result after the regulation of the interpolator output is taken as the input of the sampling clock frequency error estimation module, for finding the correct sampling point position; the sampling phase selection controller sends out commands to control a lower sampling device, thereby making the lower sampling device complete sampling in the optimum time; the output result of the lower sampling device is taken as the input of the sampling clock frequency error estimation module, for calculating the sampling clock frequency bias; the interpolation controller controls the work process of the interpolator according to the sampling clock frequency bias fed in from the loop filter, for implementing the exactness correction to the sampling values. The loop circuit structure of the invention is quite simple, and is realized by hardware in the digital domain.
Owner:SHANGHAI JIAO TONG UNIV

Low-voltage intelligent circuit breaker with plastic shell

The invention relates to a low-voltage intelligent circuit breaker with a plastic shell. The low-voltage intelligent circuit breaker comprises a switch base and a switch cover, wherein the switch base is provided with four longitudinal through grooves and a transverse through groove penetrating through the longitudinal through grooves, a vacuum electromagnetic switch, a current transformer and a storage capacitor are sequentially installed in three longitudinal through grooves; another vacuum electromagnetic switch and another storage capacitor are sequentially installed in the other longitudinal through grooves, and a zero sequence transformer is installed in the transverse through groove; and a control circuit board is fixed at the upper middle of the switch base, a power module, a charging module, a phasing voltage transformer, three voltage transformer for phase selection, two main processors and two auxiliary processors, wherein the display circuit board is located in the upper middle of the control circuit board and embedded in the switch cover and provided with a display screen, a red indication lamp, a green indication lamp, a switching-in operation button, a switching-off operation button and the like. The invention has the advantages of small volume, compact structure, convenience for use and installation and capability of truly realizing comprehensive intelligence of digital protection, automatic control and communication function.
Owner:胡俊兵

Method for initially positioning and starting switched reluctance motor without position sensor

The invention discloses a method for initially positioning and starting a switched reluctance motor without a position sensor, and belongs to the technical field of control of the switched reluctance motor. The method comprises the following steps of: setting an inductance bottom threshold value LLow and an inductance top threshold value LHigh based on the basic characteristic that the inductance of the switched reluctance motor periodically changes with the position of a rotor; injecting short pulses into each phase winding and calculating inductance values according to a phase voltage equation; judging phases which can be currently switched on according to the relation among each phase inductance calculated value and LLow and LHigh and selecting estimated phases of an initial position angle at the same time; and establishing a phase inductance mathematical model to obtain angle information in the selected phases by using the relation between the inductance mathematical model and the inductance calculated values. Though the method, an initial switch-on phase selection signal can be accurately acquired and the initial position angle of the rotor can be calculated at the same time, so the switched reluctance motor can be started and initially positioned without the position sensor, an algorithm is simple and generality is high.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS

Fault positioning method for common-tower double-circuit line

A fault positioning method for a common-tower double-circuit line comprises the following steps: firstly, carrying out six-sequence decomposition for electrical quantity at two ends of the double-circuit line; next, calculating the fault distance by a long line equation of a transmission line of a same positive-sequence fault component of the six-sequence components, and obtaining six-sequence current of a fault point according to the electrical quantity at two ends of the double-circuit line, the fault distance and the long line equation; then converting the six-sequence current into six-phase current; and finally, judging a fault phase according to the amplitude value characteristic of the phase current of the fault point. According to the method provided by the invention, when fault phase-selection of the double-circuit line is carried out, the fault distance detection can be performed at the same time, and the advantages of clear principle, high distance detection accuracy, simple and reliable phase-selection logic and the like are provided. The method provided by the invention is free of the influence of fault point transitional resistance, circuit distributed capacitor current and load current, can automatically adapt to and regulate a definite value of the phase-selection criterion with the change of a system operation manner, and can provide effective phase-selection logic for distance protection of the common-tower double-circuit line.
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING)

A comprehensive phase selection method for double-circuit lines paralleled on the same tower

The invention relates to the technical field of relay protection, and relates to a comprehensive phase selection method for double-circuit lines paralleled on the same tower: using the six-sequence component method to eliminate the mutual inductance current between the phases; according to the transformed six-sequence component, First distinguish the ground fault and non-ground fault, and then select the fault phase according to the following steps: According to the current amplitude characteristics of the single circuit fault, the non-identical phase cross-line fault and the same name phase cross-line fault, distinguish the non-identical phase span line fault, single circuit fault and phase line fault with the same name; for a single circuit fault, the phase angle of the positive and negative zero-sequence components in the same direction is 0° or 180° from the two The fault line is selected from three lines, and then the phase selection is carried out according to the negative sequence and zero sequence current phase selection principles; for the cross-line faults of the same name phase and non-same name phase, the fault type is judged respectively. The invention can make up for the disadvantages of incomplete phase selection function and even wrong phase selection of other phase selection methods currently used on double-circuit lines.
Owner:TIANJIN UNIV

Three-phase load imbalance automatic adjusting method of power distribution network

The invention provides a three-phase load imbalance automatic adjusting method of a power distribution network. A phase change switch module and a central control region module are arranged. The central control region module comprises a control module and a carrier wave module. The phase change switch module comprises an electric power electronic switch unit and a phase selection switch controller unit. The three-phase load imbalance automatic adjusting process comprises steps of acquiring three-phase current data into the central control region module; calculating imbalance degree; adopting the genetic algorithm during over-limit; coding a vector gene for a three-phase switch switching state corresponding to each load branch; obtaining an optimal phase change control instruction according to corresponding target function of the phase change module; transmitting the optimal phase change instruction to a phase selection switch controller unit of a phase change switch module on each load branch through the carrier wave module; and controlling the electric power electronic switch unit to finish the phase change operation. According to the invention, the method is used for supporting automatic detection during operation of an electric power system, so large quantity of manpower and materials are saved, device safety is improved and power supply reliability is improved.
Owner:WUHAN UNIV

Fault phase selection method for double-fed wind power plant tie line

ActiveCN105375532ASolve the problem of incorrect phase selectionMeet the needs of phase selectionContigency dealing ac circuit arrangementsSingle network parallel feeding arrangementsStable statePower grid
The invention discloses a fault phase selection method for a double-fed wind power plant tie line. The fault phase selection method comprises the following steps: (1) obtaining the voltage of each phase, the break variable of voltage of each phase, the break variable of voltage of each line and a zero sequence voltage at the position where a line protector is mounted; (2) obtaining a fault phase selection coefficient according to the proportion of the break variable of voltage of single voltage to the difference between two phases in the break variable of voltage; (3) judging whether a power grid has an earth fault or not according to the value of the zero sequence voltage and a rated voltage; (4) according to the proportion of the maximum value to the intermediate value of the fault phase selection coefficient, determining the type of the earth fault of the power grid; (5) according to the proportion of the minimum value to the intermediate value of the fault phase selection coefficient, determining the type of the interphase fault of the power grid; and (6) according to the maximum stable-state value of a three-phase voltage and the rated voltage, judging whether the power grid has a three-phase symmetry fault. Based on the characteristic that the break variable of voltage of a fault phase and the break variable of interphase voltage related to a fault have high sensitivity to the fault, the fault phase selection method can be used for accurately judging a fault type and a fault phase.
Owner:HUAZHONG UNIV OF SCI & TECH

Clock signal recovery circuit used in receiver of universal serial bus and method of recovering clock signal

A clock signal recovery circuit that is implemented in a receiver of a universal serial bus (USB) and a method for recovering a clock signal. The clock signal recovery circuit comprises a phase detector, a bidirectional shift register, a multiphase clock signal generator, and a phase selector. The phase detector detects a difference in phases between received data and a predetermined recovery clock signal and generates a first control signal indicative of the detected phase difference. The shift register is shifted in response to the detected signal and outputs a second control signal. The multiphase clock signal generator receives a receiver clock signal having the same frequency as that of a clock signal used in a USB transmitter (from which the data is transmitted) and generates a plurality of phase clock signals, preferably, first through N-th phase clock signals having the same frequencies as that of the receiver clock signal and having differences of about (360 / N)*I degree (°) (where N is an integer, and I is an integer equal to or greater than 0 and equal to or less than N−1) from a phase of the receiver clock signal, respectively. The phase selector selects one of the first through N-th phase clock signals in response to the second control signal and outputs the selected phase clock signal as the recovery clock signal. Preferably, N is an integer equal to or greater than 2 and equal to or less than 8.
Owner:SAMSUNG ELECTRONICS CO LTD

Active voltage arc-extinction method applicable to single-phase earth fault of medium voltage distribution network

The invention discloses an active voltage arc-extinction method applicable to a single-phase earth fault of a medium voltage distribution network, and relates to the technical field of fault self-recovery of a medium voltage distribution network. The active voltage arc-extinction includes the following steps: a. continuously measuring bus three-phase voltage, zero sequence voltage and each outlet three-phase current, and when a single-phase earth fault is detected, conducting fault phase selection; b. designating a threshold Ires.g of a fault phase current magnitude and a threshold Ures.g of a fault phase voltage magnitude of a fault feeder; c. measuring the voltage and current of the fault phase, comparing the fault phase current magnitude of the fault feeder with Ires.g. According to the invention, the method can effectively increase the arc extinction of a low-resistance earth fault, and compensate current at a fault point as much as possible while excess voltage is effectively controlled, and ensures that arc at the fault point can be reliably extinct. According to the invention, for non-linear resistance earth, the method is also effective simply by changing program codes in current active compensating apparatuses, and has higher values when applied to engineering.
Owner:STATE GRID SHANDONG ELECTRIC POWER +1

AC high voltage vacuum breaker

The invention relates to an alternating current high-voltage vacuum circuit breaker, which is characterized in that the invention comprises a case body, a vacuum arc extinguish chamber is seated and connected to the case body, an electromagnetic repulsive force mechanism is disposed in the case body, the mechanism comprises an open coil and a close coil which form a fixed gap, a repulsion disk arranged in the gap, a repulsion rod which is fixedly penetrated by the equipped repulsion disk, a retention capacity rod of a composite disc spring retention force structure connected with the lower end of the repulsion rod, a catch spring fixed on the retention force rod and at least two pieces of disc springs top-arranged on the catch spring. The upper end of the electromagnetic repulsive force is connected with a closing buffer gear which comprises a spring frame structure and a hydraulic cylinder, further, the closing buffer gear comprises an intelligent pulse generator. Because the invention employs the electromagnetic repulsive force mechanism, employs bi-stable composite disc springs to retain, employs the closing hydraulic pressure buffer gear to inhibit closing bouncing, and employs a photoelectric sensor to realize position returning, thereby belonging to the advanced design at home and abroad, therefore, the invention can be widely applied to the field of fault current limiters, phase selection switches, solid change-over switches and the like.
Owner:CHINA ELECTRIC POWER RES INST +1
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