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90 results about "Proportionality factor" patented technology

Factor of proportionality, constant of proportionality(noun) the constant value of the ratio of two proportional quantities x and y; usually written y = kx, where k is the factor of proportionality.

Single phase ground fault section locating method in small current grounding system

The invention provides a single phase ground fault section locating method in a small current grounding system, which includes the following steps: step 1, recording the zero mode voltage and the zero mode current of the previous period and the next period of the single phase ground fault time when the single phase ground fault occurs to the small current grounding system; step 2, selecting the highest frequency intrinsic mode function component after decomposing the transient zero mode power pure fault component of the single phase ground fault time through empirical mode decomposition; step 3, obtaining the approximate entropy proportionality factor of the highest frequency intrinsic mode function component of each detecting section through the approximate entropy value of the high frequency intrinsic mode function component of each detecting section; and step 4, comparing the approximate entropy proportionality factor of the highest frequency intrinsic mode function component of each detecting section with the preset first threshold in the main station, so as to find out the section with the single phase ground fault. The single phase ground fault section locating method has the characteristics of high detecting precision and universality, and can be widely applied to the power system.
Owner:HENAN POLYTECHNIC UNIV

Low-voltage traversing control method for double-fed wind power generation system

The invention relates to a low-voltage traversing control method for a double-fed wind power generation system, which belongs to the technical field of wind power generation. The method comprises the following steps: firstly, the stator flux and the rotor flux of a double-fed generator are calculated according to the stator current and the rotor current of the double-fed generator which are measured by a current sensor; secondly, the stator flux is multiplied by a corresponding proportionality factor to serve as the set value of the rotor flux of the double-fed generator, so as to control therotor flux; and thirdly, the rotor flux is controlled in the way that as feedforward compensation decoupling is performed, closed-loop control is conducted to the decoupled system, and a rotor-side converter is controlled after pulse-width modulation is conducted to the obtained voltage control quantity of a rotor-side converter, so as to achieve low-voltage traversing control during failures. The low-voltage traversing control method provided by the invention has fast response, and very good traversing effect when symmetrical and asymmetrical drop failures of the network voltage occur, meanwhile, and oscillation of output electromagnetic torque of the double-fed generator can be effectively inhibited. The control method is simple and suitable for engineering application.
Owner:TSINGHUA UNIV

Sea surface wind measurement method based on X-band marine radar

ActiveCN102681033AImproved wind direction measurement accuracyImproved wind speed accuracyIndication of weather conditions using multiple variablesIndication/recording movementNormalized radar cross sectionSea temperature
The invention discloses a sea surface wind measurement method based on an X-band marine radar and belongs to the technical field of marine dynamic environment remote sensing. The measurement method comprises three parts of radar image preprocessing, wind direction measurement and wind speed measurement. In the wind direction measurement indexes, image gradient, gray level and smoothing item are organically combined, the proportion of the image gradient, the gray level and the smoothing item is adjusted through proportionality factor and a model suitable for the sea surface wind characteristic is established, compared with the prior art, the wind direction measurement precision is improved by 68.4 percent. In the wind speed measurement indexes, when the radar is used for measuring individually, normalized radar cross section (NRCS), the actually measured wind direction and signal to noise ratio (SNR) serve as back propagation (BP) network input, compared with the traditional algorithm, the wind speed measurement precision is improved by over 84 percent. In the wind speed measurement indexes, sea boundary layer parameters serve as addition input of the BP network, so that the wind speed measurement precision of the marine radar can be further improved, and the measurement precision is improved by over 48 percent by taking air-sea temperature difference, salinity, sea level and atmospheric pressure into consideration.
Owner:哈尔滨哈船导航技术有限公司

Method for controlling wind turbine to participate in power grid frequency modulation based on virtual inertia and pitch angle

The invention discloses a method for controlling a wind turbine to participate in power grid frequency modulation based on virtual inertia and a pitch angle. The method comprises the following steps:when a frequency deviation exists between the rated power of a system power grid and the current frequency, calculating a proportionality factor of a tracking curve of the sub-optimal rotating speed-active power of the wind turbine under the control of the virtual inertia; calculating a reference power of an inverter at a rotor side under the control of the virtual inertia; calculating an introduced electromagnetic power at the rotor side inverter according to the frequency change rate, and accumulating the introduced electromagnetic power and the reference power to obtain a total electromagnetic power of the rotor side inverter; calculating the rotating speed deviation of the wind turbine, and adopting the rotating speed deviation of the wind turbine to calculate the electromagnetic powervariation of the rotor side inverter; obtaining an active power of a pitch angle mechanism according to the total electromagnetic power and the electromagnetic power variation, and calculating the pitch angle of the pitch angle mechanism by adopting the active power of the pitch angle mechanism; and controlling the wind turbine to increase captured wind energy and inject the active power into thepower grid according to the pitch angle.
Owner:SOUTHWEST JIAOTONG UNIV

Split-phase differential protection method based on scalar product brake criterion normalization

The invention belongs to the field of relay protection of a power system, and relates to a split-phase differential protection method based on scalar product brake criterion normalization. The method comprises the following steps of: acquiring the currents on the two sides of a transmission line by utilizing current transformers (CTs) on the two sides of the transmission line; calculating the amplitude values, the phase angles and the phase angle difference between the currents on the two sides by utilizing a full-wave Fourier algorithm; if the phase angle difference between the currents on the two sides is less than 120 degrees, determining that an internal fault exists, performing the protection action of tripping; and if the phase angle difference between the currents on the two sides is more than 120 degrees, turning to the amplitude value judgment below: first, judging whether the amplitude values of the currents on the two sides are both greater than three times the rated current of the primary side of the CT, wherein if the amplitude values are both greater than three times the rated current of the primary side of the CT, the proportionality factor K=2, and if the amplitude values are not greater than three times the rated current of the primary side of the CT, the proportionality factor K=0.8; and then calculating the ratio of the smaller amplitude value to the greater amplitude value of the currents on the two sides, wherein if the ratio is less than the K, determining that an internal fault exists, and performing the protection action of tripping. According to the split-phase current differential protection method of the transmission line provided by the invention, the sensitivity of the internal fault and the selectivity of an external fault are taken into consideration.
Owner:TIANJIN UNIV

Even pace fan-shaped scan running device of type-B ultrasonic

The invention relates to a scanning device, in particular to a type-B ultrasonic constant sector scanning moving device which includes a dial on an X-Y plane driven by a motor, a balance arranged on the dial and a slide block which is driven by the balance and can move flatly along the directions of an X shaft and a Z shaft. A swing body provided with a type-B ultrasonic probe is connected with the slide block through a rotary shaft. The swing body can swing along the Y-shaft direction on the X-Z plane; wherein, the slide block is provided with a plane cam swing slot driven by the balance and a contour line of the plane cam swing slot meets an equations set; wherein, d relates to a projection of the distance between the balance and the center of the slide block on the X shaft; R relates to a rotary radius of the balance; a relates to the included angle between the rotary radius of the balance on the dial and the Y shaft; r relates to the distance from a swing shaft to a rotary shaft of the swing body; b relates to the included angle between the swing radius of the swing body and the Z shaft; k relates to a proportionality factor. The invention is also provided with a position sensor sensing the swing position of the slide block. The invention switches the constant rotation of the motor into the constant swing of the sector scanning probe, which is simple in structure and is stable and reliable.
Owner:TIANJIN SUOWEI ELECTRONICS TECH

Method for calculating composite stress of non-equal structure superposed valve plates of vehicle shock absorber

The invention relates to a method for calculating the composite stress of non-equal structure superposed valve plates of a vehicle shock absorber and belongs to the technical field of the shock absorber. The method is characterized in that according to the inner radius, outer radius, thickness and number of the non-equal structure superposed valve plates, the outer radius unequal rate factor, the equivalent thickness, the equal thickness, and the thickness proportionality factor of each superposed valve plate are determined; according to structure parameters and material characteristic parameters, the composite stress factor of the non-equal structure superposed valve plates is calculated, so that the composite stress of each non-equal structure superposed valve plate at any radius under uniform pressure is calculated. Comparison with an ANSYS simulation verification result shows that the calculating method is correct, a reliable composite stress calculating method is provided to the detaching design and strength verification of the non-equal structure superposed valve plates of the vehicle shock absorber, the design level, the quality and the performance of the shock absorber can be improved, on the premise that characteristic design requirements are met, the design requirement on the stress strength of the valve plates is met, and the design and experiment cost and the production cost are reduced.
Owner:SHANDONG UNIV OF TECH

Interference type optical fiber vibration sensing demodulation system and method based on photoelectric oscillator

The invention provides an interference type optical fiber vibration sensing demodulation system and method based on a photoelectric oscillator, and the system mainly comprises a light source, an electro-optic modulator, an interference type vibration sensing unit, a polarization controller, a polarizer, a photodetector, a microwave amplifier, a power divider and a frequency monitoring unit. In theinvention, the electro-optic modulator is used to generate phase-dependent polarization orthogonal carrier waves of different frequency components and a first-order single-sideband, polarization characteristics are adopted to separate the carrier waves and first-order single-sideband such that the carrier waves and first-order single-sideband are transmitted along two interference arms in the interference type vibration sensing unit, and the phase difference containing the vibration signal to be measured is converted into a change in the microwave oscillation frequency of the photoelectric oscillator with a high Q value. Therefore, the vibration signal to be measured can be demodulated by monitoring the frequency change of the microwave signal output by the photoelectric oscillator. Thisamount of frequency change is proportional to the vibration signal to be measured, and the proportionality factor is determined by the frequency of the optical carrier, so that vibration detection anddemodulation with high sensitivity, high accuracy and fast response can be achieved.
Owner:BEIJING JIAOTONG UNIV

Method and device for adjusting writing bandwidths of solid-state disks

The invention discloses a method for adjusting writing bandwidths of solid-state disks. The method includes acquiring the numbers of current remaining available physical blocks in the solid-state disks according to preset sampling periods; adjusting proportionality factors in real time according to the numbers of the available physical blocks; smoothing errors of the proportionality factors by the aid of PID (proportion, integration and differentiation) controllers according to proportionality factor difference values of a previous sampling period. The proportionality factors are ratios of GC (garbage collection) writing bandwidths to total bandwidths. The invention further discloses a device for adjusting the writing bandwidths of the solid-state disks. The method and the device have the advantages that the proportionality factors between the GC writing bandwidths and the total bandwidths are adjusted by the aid of the numbers of the real-time available physical blocks, and accordingly the accuracy of the proportionality factors can be guaranteed; the errors of the proportionality factors are controlled by the aid of the PID controllers and proportionality factors of the previous sampling period, fluctuation of the proportionality factors can be reduced, and accordingly the stability of writing bandwidths can be improved for users.
Owner:SUZHOU LANGCHAO INTELLIGENT TECH CO LTD
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