45results about How to "High protection sensitivity" patented technology

The invention discloses a relay protection method and device for quickly cutting off the fault of empty charging in the dead zone of a transformer, including the following control process: the circuit breakers on each side of the transformer are in the opening position, and the current on one side changes from no flow to flow and When the circuit breaker on this side is turned from the minute position to the close position, the transformer is in the state of empty charging from this side; the transformer is empty charging, and the dead zone protection is opened for T seconds; the circuit breaker on a non-empty charging side of the transformer is in the opening position; The maximum phase current of the three-phase current on the charging side is greater than the current setting value, or the zero-sequence current is greater than the zero-sequence setting value, or the negative-sequence current is greater than the negative-sequence setting value; when the above conditions are met, the transformer differential protection will be activated after a delay of t1 The tripping action exits the circuit, trips the circuit breakers on each side of the transformer, and quickly removes the fault in the dead zone. The invention avoids the influence of inrush current when the transformer is empty-charging, has nothing to do with the setting value of the backup protection of the transformer, the type of the transformer and the type of the fault, and greatly shortens the removal time of the fault in the dead zone.

The invention discloses transmission line self-adaptive single-end transient protection based on transition resistance and fault angle reductions. When the transmission line is in short circuit, a large amount of high-frequency signals produced by a fault are transmitted to two ends of the transmission line; and owing to affect of earth distributed capacitance of a bus, the high-frequency signals are obviously reduced via the bus, high-frequency component close to the fault side of the bus is invariably higher than that of the fault side of the bus, and the transition resistances and fault angles have a great affect on the high-frequency component produced by the fault. Relative reduction formulas and parameters are selected according to the type of the fault, the transient amount reduction is performed corresponding to the transition resistances and the fault angles, and protective criterion is constructed according to the reduction transient amount. According to the principle, fault feature amount with both directional elements and number comparing functions are constructed on the basis of the transient amount difference of reduction of two sides of the bus to determine a zone the fault occurs in. By the aid of the scheme, the affect to the single-end transient protection by the transition resistances and fault angle is eliminated to a maximum extent. Fault feature differences between the forward direction and reverse direction and inner zone and external zone are obvious, reliability and flexibility are high, the overall length of a line can be protected, protecting areas are twice that of traditional protecting areas, and requirements for the distributed capacitance of the bus are low.

A small current neutral grounding fault location method based on the direction of transient state reactive power is characterized in that change of voltage or current serves as a failure starting condition, and after the starting, the zero sequence voltage is taken as the participating voltage if a detection point can be used for detecting the zero sequence voltage and if not, the following steps are performed: 1, confirming the fault phase as per characteristics of three transient state line voltages, and 2, confirming the transient state line voltage including the fault message as per the type of the fault phase, taking the transient state line voltage as the participating voltage, confirming the characteristic frequency range, and further building a digital filter to filter the participating voltage and the zero sequence current signal, so as to obtain the component within the characteristic frequency range; and then confirming the direction of the reactive power of all the detection points through utilizing the components of participating voltage and the zero sequence current within the characteristic frequency range, so as to further confirm the fault section. According to the invention, the transient voltage and current signals as well as zero sequence voltage and line voltage are utilized at the same time, the positioning reliability is higher, the adaptability is stronger, quick direction protection for ground fault of all the voltage classes is applicable at the same time, and the protection speed and reliability are taken into consideration.