Patents
Literature
Patsnap Copilot is an intelligent assistant for R&D personnel, combined with Patent DNA, to facilitate innovative research.
Patsnap Copilot

490 results about "Initial current" patented technology

Overvoltage protection device, overvoltage protection method and electrolytic-capacitor-free motor driving system

ActiveCN104934943AAvoid damageTo achieve the purpose of overvoltage protectionAC motor controlEmergency protective circuit arrangementsCapacitanceOvervoltage
The invention relates to the field of motor control, and discloses an overvoltage protection device, an overvoltage protection method and an electrolytic-capacitor-free motor driving system. The overvoltage protection device comprises a voltage detection module for detecting direct-current bus voltage Vdc in real time, a current compensation dosage calculation module which is connected with the voltage detection module and is used for calculating a current compensation value according to the detected direct-current bus voltage Vdc and a preset safety voltage Vdc_max, and a current control module which is connected with the current compensation dosage calculation module and is used for generating a final current instruction value according to the calculated current compensation value and an initial current instruction value and adjusting three-phase current input into a motor by an inverter according to the final current instruction value in order to avoid overvoltage damage of the electrolytic-capacitor-free motor driving system. Through adoption of the voltage protection device and method and the electrolytic-capacitor-free motor driving system, the three-phase current of the motor can be adjusted according to the direct-current bus voltage detected in real time and the preset safety voltage, so that over high direct-current bus voltage is lowered, and the aim of overvoltage protection is fulfilled.
Owner:GD MIDEA AIR-CONDITIONING EQUIP CO LTD +1

Dual-closed-loop control-based active voltage arc extinction method and apparatus for power distribution network in fault

InactiveCN106655144ABest injection currentRealize fault arc suppressionEmergency protective arrangements for limiting excess voltage/currentClosed loopThree-phase
The invention discloses a dual-closed-loop control-based active voltage arc extinction method and apparatus for a power distribution network in fault. The arc extinction method comprises the following steps of collecting a three-phase voltage and a neutral point voltage of the power distribution network, and judging whether the power distribution network suffers from a single phase grounding fault or not; if the power distribution network suffers from the single phase grounding fault, determining a fault phase according to the value of the three-phase voltage; injecting an initial current to the power distribution network to obtain a phase voltage and a neutral point voltage of the fault phase, and determining an optimal injection current through a dual-closed-loop control method; and injecting the optimal injection current to the power distribution network to realize arc extinction on an instantaneous single phase grounding fault. According to the method and the apparatus disclosed by the embodiments, based on the dual-closed-loop control method, a current is injected to the neutral point of the active arc extinction apparatus when the power distribution network suffers from the single phase grounding fault; and the fault phase voltage is controlled to be zero, and the reactive current component, the active current component and the harmonic component of the fault phase are compensated, so as to realize rapid and high-precision complete arc extinction on the instantaneous single phase grounding fault.
Owner:YUNNAN POWER GRID CO LTD ELECTRIC POWER RES INST

Differential privacy protection method for online social network based on stratified random graph

The invention discloses a differential privacy protection method for an online social network based on a stratified random graph. The differential privacy protection method comprises the following steps: inputting a network; constructing a tree structure of the network based on a stratified random graph model; sampling in the network through a Markov chain Monte Carlo method according to a preset privacy budget so as to obtain a sampled tree; taking the root node of the sampled tree as an initial current node; calculating an associated probability value of the current node according to the preset privacy budget; finding out a set of node pairs by taking the current node as the nearest father node in the network, and setting an edge among the set of node pairs according to the associated probability value; judging whether traversal of the sampled tree is completed or not, and if not, continuously traversing the next node in the sampled tree; and otherwise, outputting a purified network composed of edges arranged among all the sets of nodes and nodes thereof. According to the invention, the privacy protection problem of sensitive structural data information in the social network can be solved; differential privacy protection requirements can be satisfied; and simultaneously, the good data availability is kept.
Owner:NAT UNIV OF DEFENSE TECH

Distribution line single-phase grounding traveling wave protection method

ActiveCN102780211AOvercome insensitivityOvercomer's failureEmergency protective circuit arrangementsFault locationElectrical polarityEngineering
The invention provides a distribution line single-phase grounding traveling wave protection method. The method includes: step 102, respectively acquiring fault zero modal initial current traveling wave within a frequency range of 0-100KHz and fault zero modal initial voltage traveling wave within a frequency range of 0-100KHz, comparing wavefront polarity of the fault zero modal initial current traveling wave with that of the fault zero modal initial voltage traveling wave, and enabling a first criterion to be established when the polarity of the fault zero modal initial current traveling wave and the polarity of the fault zero modal initial voltage traveling wave are opposite; step 104, acquiring three-phase current magnitude and zero-sequence voltage magnitude under the condition that the first criterion is established, and enabling a second criterion to be established if the zero-sequence voltage magnitude is larger than a first setting value and the three-phase current magnitude is smaller than a second setting value; and step 106, judging to determine that a single-phase grounding fault occurs and giving out a trip signal or an alarm signal when the first criterion and the second criterion are both established. By the technical scheme, when the single-phase grounding fault occurs in a distribution line neutral point ineffective grounding system, the fault can be detected quickly and accurately, and reliable protection actions can be taken.
Owner:TSINGHUA UNIV
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Try Eureka
PatSnap group products