61results about How to "Good quickness" patented technology

By utilizing unique high-frequency attenuation oscillation characteristic of a DC line when an MMC-HVDC DC line single-pole grounding fault occurs, through waveform recognition of a single-end current quantity and extraction of an oscillation amplitude and an oscillation period of a current transient quantity, an MMC-HVDC DC line single-pole grounding fault protection method based on current waveform recognition determines that a single-pole grounding fault occurs in a system when the oscillation amplitude and the oscillation period meet a high-frequency attenuation oscillation criteria.

The invention discloses a multi-end pilot protection method for a new energy field station based on cosine similarity, and the method comprises the steps: obtaining a transient current analytic expression of a fault of the new energy field station and a short-circuit current analytic expression of the new energy field station for the new energy field station which achieves the grid connection through a power electronic converter through combining with a commonly used control strategy for inhibiting a negative sequence current; analyzing and obtaining the superposing characteristics of a sine wave with the short-circuit waveform in the non-power-frequency attenuation with a non-power-frequency sine wave of the new energy station field according to the short-circuit current analytic expression of the new energy field station, and thereby constructing a multi-end pilot protection criterion of the new energy field station based on the cosine similarity; and setting a protection fixed valuein the multi-end pilot protection criterion according to an angle error and amplitude error when a system operates normally. The method is not affected by the new energy capacity and an operation mode, is high in reliability and sensitivity, is good in power swing performance, and improves the operation safety and reliability of a large-scale new energy grid connected system.

The invention relates to a fast triggering system of a resonant current limiter thyristor valve and a working method of the fast triggering system. The system mainly comprises a sampling module, a controller, a clock circuit, a triggering unit and an alarm circuit, wherein the sampling module is used for sampling line current and resonance voltage difference signal at high speed; the clock circuit is used for providing an overall clock signal and providing a reference time for the system; and the controller is used for realizing a fault recognition logic matching scheme by adopting a field programmable technology and converting a criteria signal into a thyristor valve triggering signal. A model experiment indicates that the resonance voltage difference recognition method can provide a criteria output signal within 1ms. The fast triggering system disclosed by the invention has the advantages of fast recognizing short-circuit fault and avoiding faults, such as switch reclosing, system disconnection, and the like.

The invention provides a micro-grid current selective tripping protection method applicable to photovoltaic multipoint access. The micro-grid current selective tripping protection method applicable to the photovoltaic multipoint access comprises the following steps of S01 stage of judging whether an onside protection device is started or not; S02 stage of judging whether an on ring main unit adjacent protection device acts or not; S03 stage of judging a protection device on an opposite side of a protection circuit acts or not; S04 stage of executing circuit fault protection; S05 stage judging whether an opposite end protection device acts or not. Compared with a traditional over-current protection and differential protection, the micro-grid current selective tripping protection method applicable to the photovoltaic multipoint access can protect circuits and buses, not need to introduce PT, has no protection dead zones, can cover the full-length of the circuit and meanwhile has good selectivity and power swing.

The invention provides an annular direct current power distribution network fault detection method based on voltage prediction, and belongs to the field of safe operation of a direct current power distribution network. Two ends of the direct current power distribution network are each provided with a protection device which includes a breaker, a sensor, a relay and an electric reactor. The annulardirect current power distribution network fault detection method based on voltage prediction is characterized by: predicting a prediction voltage value at a next moment on a line side according to sampling voltage values of any three sampling time points on the line side, and using the difference between the prediction voltage value and the measured voltage value on the line side at the fault time as an action basis for protection. The annular direct current power distribution network fault detection method based on voltage prediction solves the problems that the protection of a conventionalDC power distribution network is low in quickness, and relies too much on communication and the damping state of the circuit. The annular direct current power distribution network fault detection method based on voltage prediction only relies on the voltage value on the line side, and effectively avoids the influence of relying too much on the damping state of the circuit at the fault time when the operating current, the first derivative and the second derivative of the current, the first derivative of the voltage and other elements set protection.

The invention relates to a region backup protection method capable of being used for setting and simplifying distance II section protection. An existing distance II section protection setting method has large calculating amount and calculating difficulty. By means of the region backup protection method, according to the resistance value of a protected line, the setting value of distance II section protection is calculated only according to sensitivity requirements. Then, starting information of distance protection of an adjacent transformer substation is collected. Afterwards, a region backup protection criterion result is calculated. Finally, a protection action is determined according to the criterion result so as to correctly eliminate faults. The region backup protection method reduces setting difficulty of distance II section protection, reduces workloads, and improves quickness of distance II section protection.

The invention provides a three-area current differential protection method, and belongs to the technical field of current differential protection in a power system. The area which the relative relationship of double-end currents belongs to on an amplitude-phase plane is judged, a fault type is judged, and whether protective actions are carried out or not is decided according to the judgment results. The amplitude and the phase of double-end currents are made full use of, the whole amplitude-phase plane is divided into three areas including a braking area, a fuzzy area and an action area, whether protective actions are carried out or not is determined according to the area where the relative relationship of the double-end currents is located, by means of an external fault CT linear area, high-resistance faults in the area and external fault CT saturation is judged in the fuzzy area, contradiction between sensitivity and safety is eliminated, and meanwhile, by means of the method, an external fault can be converted into a fault in the corresponding area quickly.

The invention relates to a petal-shaped power distribution network trunk line time-limited current quick-break protection acceleration method. The method comprises the following steps of calculating apositive sequence voltage power frequency quantity and a positive sequence current amplitude at a protection position during a fault; obtaining a positive sequence impedance value of a protected line, positive sequence impedance of a lower line in a protection direction and a minimum value of a fault current break variable measured by successive action protection of a petal-shaped power distribution network trunk line; judging a fault type; meanwhile, judging the fault direction; selecting an adaptive time-limited current quick-break protection setting formula and a current break variable setting formula according to a fault type judgment result when a fault direction element judges that a fault occurs in the forward direction; and when the positive sequence current is greater than the time-limited current quick-break protection setting value and less than the quick-break current setting value, and the current break variable is greater than the break variable setting value, judging the protection to be an internal fault. According to the invention, the problem of insufficient quickness of traditional current protection is overcome, and the method has the advantage of adapting to symmetric faults.

The invention relates to the field of high-voltage direct-current power transmission relay protection, in particular to a novel single-ended protection method for a high-voltage direct-current power transmission line. The method specifically comprises the following steps of: establishing an electromagnetic transient simulation model of a bipolar high-voltage direct-current power transmission system, performing internal and external fault simulation of a line area, obtaining transient current of a line boundary protection device, calculating a current break variable amplitude and taking the current break variable amplitude as an electric quantity required by protection starting, and extracting a characteristic frequency band component of the transient current as a characteristic electrical quantity for identifying a fault section and fault pole selection. Whether the direct current system breaks down or not is judged according to whether the transient current break variable amplitude value is greater than a protection starting threshold value or not under the fault condition, a corresponding fault interval is judged according to whether the Shannon entropy value of the extracted transient current characteristic frequency band component is greater than a protection action threshold value or not, and a fault polar line is selected according to the ratio of the transient current characteristic frequency band component amplitude integral detected by the two-pole line boundary protection device. The method still has relatively high sensitivity when a high transition resistance fault occurs.

The invention relates to an MMC (Modular Multilevel Converter) DC transmission line protection method based on voltage correlation, which belongs to the technical field of power system relay protection. When a fault occurs in a DC transmission line, the positive and negative voltages at both ends of the line are collected and a correlation coefficient is obtained. Then, whether the fault is a single-pole grounding fault is judged according to the correlation coefficient. If the fault is judged to be a non-single-pole grounding fault, the inter-pole voltage is calculated, and the change rate ofthe inter-pole voltage is obtained. Finally, whether there is a short circuit between the two poles is judged according to the change rate of the voltage. The method of the invention has strong transition resistance endurance, and the data window is only 3ms. The method is quick in operation, and has a strong application prospect.

The invention discloses a hydropower station monitoring system guide vane opening analog quantity segmented open-loop control and speed regulator PID closed-loop control combined control method and system. The method is based on a water head, active power and guide vane opening corresponding data table, in an opening mode, a monitoring system adopts a mode of looking up the corresponding data table and segmented open-loop control, the guide vane opening analog quantity control signal is output, a PID closed-loop control manner is adopted in a speed adjusting system, a hydraulic servo system control signal is output, the brand-new method for quickly and accurately adjusting the active power of a unit by combining the two aims to solve the problems that a power closed-loop conventional pulseadjusting manner is adopted in an opening manner, the active power adjusting speed is low, the adjusting process is easily influenced by the water hammer reaction and the unit inertia effect, the problems that in a pure open-loop control manner, the water head, active power and guide vane opening corresponding data table has deviation, and consequently static deviation exists in opening control are solved, and meanwhile the serious overshoot phenomenon caused by the excessively-high adjusting speed is restrained.

The invention belongs to the field of high-voltage direct-current line protection, and relates to a high-voltage direct-current line rapid pilot protection method, which comprises the following steps of: polar line voltage and polar line current are measured by using measuring points at the head end and the tail end of a line; preliminary judgment is carried out in the starting unit, and protection starting is carried out when a starting criterion is met; a convolution power sequence is carried out by using the polar line voltage and the polar line current, and an average value of the convolution power sequence is calculated; the measuring point transmits the calculated convolution power average value to the measuring point on the opposite side of the line; the difference between the convolution power average values on the two sides of the line is calculated; in the intra-region fault identification and fault pole selection unit, intra-region faults are identified by using the difference of convolution power average values, and fault pole selection is carried out; and in the protection unit, corresponding protection action is performed according to the processing result of the internal fault identification and fault pole selection unit. According to the method, the defects that an existing pilot protection method is not high in speed and double-end data needs to be strictly synchronized are overcome. The invention further provides a high-voltage direct-current line rapid pilot protection system.

The invention discloses a control method and system combining guide vane opening analog quantity closed-loop and segmented open-loop control. The method is a brand-new method of rapidly and accurately adjusting active power of a unit and outputting a guide vane opening degree analog quantity control signal in an opening degree mode based on data tables corresponding to a water head, the active power and guide vane opening degree by adopting a mode of combining corresponding data table checking, open-loop control and closed-loop control, and aims to solve the problems that a conventional power closed-loop pulse regulation mode is adopted in an opening degree mode, the active power regulation speed is low, the regulation process is easily influenced by water hammer reaction and unit inertia, and static deviation of opening control is caused by deviation of the data tables corresponding to the water head, the active power and the guide vane opening degree in a pure open-loop control mode and the like, rapid, accurate and stable control over the guide vane opening and the active power of the unit is achieved, and the regulation quality is improved.

The invention discloses a power transmission line travelling wave protection method considering travelling wave speed characteristic. The method comprises the steps of acquiring a transient current travelling wave signal at each bus node in a power grid after a fault occurs in a line, and calculating to obtain modulus time difference between initial wavefront which are reached of a zero-mode travelling wave and a line-mode travelling wave of each bus node; taking the bus node with minimum modulus time difference as a key bus node; and determining a fault region according to the key bus node, calculating average modulus ride-through time difference of each circuit in the fault region, determining the circuit with minimum average modulus ride-through time difference as a fault circuit, and performing circuit protection action on the fault circuit. By the travelling wave protection method, two ends of the circuit do not need to be synchronous, the travelling wave protection method is freefrom influence of factors such as a system load, a fault initial phase angle and transition resistance, is high in reliability and accuracy and rapid in action speed and has relatively high economy and relatively high practical value.

The invention discloses a low-pressure single-phase alternating current leakage protector. The leakage protector comprises a power failure trip protecting mechanism, a resonant protection circuit capable of generating resonance immediately and generating instantaneous high impedance when an earth fault happens, a data acquisition processing circuit, and a main controller for controlling the power failure trip protecting mechanism according to a signal detected by the data acquisition processing circuit, which are connected in series in a power supply circuit; the resonant protection circuit is a double-resonance protection circuit consisting of two LC resonant circuits; the two LC resonant circuits comprise a first LC resonant circuit consisting of L1 and C1, and a second LC resonant circuit consisting of L2 and C2, and the L1 and the L2 are two mutual inductors; and the data acquisition processing circuit is connected in parallel at two ends of the capacitor C1 or the capacitor C2. The low-pressure single-phase alternating current leakage protector has reasonable circuit design, high intelligent degree and good using effect, and can effectively solve the practical problems that the prior leakage protector has unreliable motions, is likely to cause personal casualty, influences load normal operations and the like.

The invention discloses a hydropower station monitoring system guide vane opening analog quantity segmented open-loop control and speed regulator PID closed-loop control combined control method and system. The hydropower station monitoring system guide vane opening analog quantity segmented open-loop control and speed regulator PID closed-loop control combined control method is based on a water head, active power and guide vane opening corresponding data table, in an opening mode, a monitoring system adopts a mode of looking up the corresponding data table and segmented open-loop control, a guide vane opening degree analog quantity control signal is output, a speed adjusting system adopts a PID closed-loop control mode, a hydraulic servo system control signal is output, the guide vane opening degree analog quantity control signal and the hydraulic servo system control signal are combined to quickly and accurately adjusting the active power of a unit, the problems that a power closed-loop conventional pulse adjusting mode is adopted in an opening degree mode, the active power adjusting speed is low, the adjusting process is easily influenced by the water hammer reaction and the unitinertia effect, in a pure open-loop control mode, consequently static deviation exists in opening degree control due to the fact that the water head, active power and guide vane opening degree corresponding data table have deviation are solved, and meanwhile, the serious overshoot phenomenon caused by the excessively-high adjusting speed is restrained.

The invention discloses a power distribution network fault detection method and system based on differential analysis and a positioning method. The method comprises the steps: constructing a correction rule of a fault feature value based on the fault current feature analysis of a DC power distribution network; acquiring a first parameter of the DC power distribution network in a normal operation state; constructing a fault identification criterion and a protection starting criterion based on the first parameter and a correction rule of the fault feature value; acquiring a second parameter of the DC power distribution network in the fault state; and based on the fault identification criterion and the protection starting criterion, judging whether the second parameter satisfies the fault identification criterion and the protection starting criterion, and if the second parameter satisfies the fault identification criterion and the protection starting criterion, judging that the fault of the DC power distribution network is the internal fault. The method has the beneficial effects that the fault and the type of the fault can be quickly identified, and the reliability, the quickness and the selectivity of the detection result are good; and the fault current differential value is compensated and corrected by utilizing the correction strategy, and the anti-transition resistance capability and the sensitivity of protection are improved.

The invention relates to an oil flow velocity variation-based oil immersed transformer digital non-electricity protection method. The method comprises steps of first, performing continuous real-time measurement on flow velocity of oil in a connection tube by a digital flow velocity sensor installed at a connection tube of the oil immersed transformer; then determining whether a velocity variationcalculation procedure is started by a digital gas relay by using received oil flow velocity data; if yes, calculating oil flow velocity variation, and comparing measurement value of variation with setting value of variation; and determining whether protection acts according to a comparison result. The method is started effectively when the oil immersed transformer has an internal fault, and protects reliable actions; and prevents the oil immersed transformer from acting wrongly when the oil immersed transformer has an external fault.

An object of the present invention is to provide a method for analyzing a target nucleic acid fragment which can be simply and swiftly carried out by using a small apparatus, a kit for analyzing a target nucleic acid fragment using the method for analysis, and a dry analytical element for quantifying pyrophosphoric acid. The present invention provides a method for analyzing pyrophosphoric acid generated upon polymerase elongation reaction based on certain nucleotide sequence of a target nucleic acid, a kit for analysis for carrying out the above mentioned method for analysis, and a dry analytical element for quantifying pyrophosphoric acid.