43results about How to "Protection action fast" patented technology

The invention provides a generator rotor de-excitation and overvoltage protection device which relates to an overvoltage protection device of a silicon controlled rectifier excitation system. The generator rotor de-excitation and overvoltage protection device comprises a de-excitation switch, a peak overvoltage absorber, a non-linear resistor, a silicon controlled rectifier trigger, a silicon controlled rectifier, a diode, a current transformer and linear resistors. One end of the de-excitation switch is connected with one end of the peak overvoltage absorber and then is connected with a rectification power supply, and the other end of the de-excitation switch is connected with one end of each linear resistor and one end of the non-linear resistor. The other end of one linear resistor is connected with the other end of the non-linear resistor in parallel and then is connected with one end of the diode and one end of the silicon controlled rectifier. The other end of the other linear resistor is connected with the silicon controlled rectifier trigger. The silicon controlled rectifier trigger is further connected with the other end of the silicon controlled rectifier, the other end of the diode and one end of the current transformer. The other end of the current transformer is connected with the other end of the peak overvoltage absorber and then is connected with a rotor winding. According to the invention, the de-excitation capability is strong, the de-excitation speed is high, the overvoltage protection action speed is high, an open circuit of the rotor winding is avoided, and the insulation breakdown accidents of the rotor winding are effectively prevented.

The invention discloses a voltage-dead-zone-free fault direction determining system and method. The voltage-dead-zone-free fault direction determining system comprises a fault component extracting unit, a back-side impedance calculating unit and a determining and order issuing unit, wherein the fault component extracting unit, the back-side impedance calculating unit and the determining and order issuing unit are sequentially connected. The voltage-dead-zone-free fault direction determining method includes the steps that firstly, the fault component extracting unit extracts a voltage-and-current fault component at the protection installation position; secondly, the back-side impedance calculating unit calculates through the voltage-and-current fault component to obtain protected back-side impedance used for determining the direction of a fault; finally, the direction of the fault is determined through the determining and order issuing unit, if the back-side impedance is positive, the fault is determined to be the fault in the positive direction, and if the back-side impedance is negative, the fault is determined to be the fault in the negative direction, and a locking order is issued. Testing results show that according to the fault direction determining system based on back-side impedance calculation, the direction of the fault can be accurately determined, voltage dead zones do not exist, and influences of connection of a distributed power source and a transition resistor are avoided.

The invention provides an overcurrent protection method and device for a line between / inside a transformer station in a ring network power supply system. The overcurrent protection method includes thefollowing steps: after optical fiber differential protection of the ring network power supply system fails, when an incoming line overcurrent protection device detects that a current of a corresponding line is greater than a corresponding protection current, if a corresponding outgoing line overcurrent protection device detects that the current of the corresponding line is not greater than the corresponding protection current, the incoming line protection device executes an overcurrent protection action; and when the outgoing line overcurrent protection device detects that the current of thecorresponding line is not greater than the corresponding protection current, if the corresponding incoming line overcurrent protection device detects that the current of the corresponding line is greater than the corresponding protection current, the outgoing line protection device executes the overcurrent protection action. According to the technical scheme provided by the method and the device,the judging method is simple, is fast in protection action, is not restricted by protection areas, and can solve the problem that failure is poor when a backup protection system performs incoming lineovercurrent protection on the line between transformer substation in the prior art.

The invention discloses a layered domain-partitioned anti-islanding protection method for large-scale wind power generation. The method includes the steps of: monitoring all breaker tripping signals in a wind power generation system; judging when cluster main station outgoing tie lines and a main transformer are all disconnected according to the breaker tripping signal of the cluster main station, and protecting an island formed due to disconnection of all the cluster main station outgoing tie lines and the main transformer; judging whether an island is formed due to a wind power plant collection bus fault according to the breaker tripping signal of the wind power plant collection bus, and protecting the island formed by the wind power plant collection bus fault; and judging whether an island is formed due to a wind power plant current collection feeder line fault according to the breaker tripping signal of a blower fan feeder line, and protecting the island formed by the wind power plant current collection feeder line fault. The layered domain-partitioned anti-islanding protection method for large-scale wind power generation realizes the advantages of being rapid, accurate, efficient, safe and stable.

The invention discloses an island detection method for large-scale wind power with a function of preventing tripping without fault. The island detection method comprises the steps of initializing a node type table and a node connection table; monitoring circuit breaker tripping signals in a power grid, updating the node connection table according to the monitored circuit breaker tripping signals, and pushing the nodes corresponding to the circuit breaker tripping signals into the a queue; and performing logical judgment according to the updated node connection table and the queue so as to judge whether an island is formed by the nodes corresponding to the circuit breaker tripping signals or not. The island detection method is targeted to the large-scale wind power system for performing the island detection and anti-islanding protection on the power supply side high-voltage main grid, and the island detection method has the advantages of being rapid, accurate, efficient, safe and stable; and meanwhile, the circuit weight is not taken into consideration by the technical scheme of the island detection method, so that the anti-islanding protection actions can be performed more rapidly.

The invention discloses an islanding state detection method for large-scale wind power. The islanding state detection method comprises the steps of initializing a node type table and a node connecting table; monitoring a circuit breaker tripping signal in a power grid, and updating the node connecting table according to the monitored circuit breaker tripping signal, and judging whether an islanding state is formed or not according to the updated node connecting table. The islanding detection and the anti-islanding protection are performed in the power supply side high-voltage main grid for a large-scale wind power generation system; and the islanding state detection method has the advantages of rapidness, accuracy, effectiveness, safety and stability; and meanwhile, the circuit weight is not taken into consideration by the technical scheme of the islanding state detection method, so that the anti-islanding protection action can be performed more rapidly.

The invention relates to the technical field of electrical equipment protection, in particular to a three-phase load phase failure protection circuit. The three-phase load phase failure protection circuit comprises a transformer, a Y-shaped sampling circuit, a first partial pressure circuit, a short-time cutoff circuit, a second partial pressure circuit, a comparison circuit and a control circuit; the secondary side of the transformer is connected with the Y-shaped sampling circuit, the neutral point of the Y-shaped sampling circuit is grounded via the first partial pressure circuit, the low-voltage outlet end of the first partial pressure circuit is connected to positive input end of the comparison circuit, the low-voltage output end of the second partial pressure circuit is connected to the negative input end of the comparison circuit, and the output end of the comparison circuit is connected to the control end of the control circuit. The three-phase load phase failure protection circuit reasonable in design, simple in structure and safe and reliable; when a certain one or two phases are in phase loss during operation of three-phase load, a supply circuit of the three-phase load can be cut off timely to enable the load to be separated from a three-phase power supply to stop running, and load equipment is protected.

The embodiment of the present invention relates to the field of circuit technology, and discloses a real-time monitoring and protection circuit for a radio frequency power amplifier. The circuit includes: a voltage / current detection device for obtaining the working voltage and working current of the power amplifier according to the voltage and current input by an external power supply; Determine whether the working voltage of the power amplifier exceeds the limit, and output a voltage overrun alarm level indication signal at the first output terminal of the voltage / current detection device; determine whether the working current of the power amplifier exceeds the limit, and output the current at the second output terminal of the voltage / current detection device Overrun alarm level indication signal; the AND gate chip outputs a control signal according to the two indication signals to control the power supply of the RF power amplifier on and off through the fast power-off protection device. This method does not need to be processed and judged by the main control device, and directly controls the opening and closing of the power supply of the RF power amplifier. It has the advantages of rapid protection action, strong real-time performance, compact circuit area, and low power consumption.

The invention relates to an over-current quick-protection circuit for a power analyzer, and belongs to the technical field of detection. The technical scheme is that: an electromagnet (3) is a coreless electromagnet; a reed switch penetrates through a coil of the electromagnet; a normally open contact (4) of the reed switch is connected with a coil (5) of a relay; a normally open contact (9) of the relay is bridged at the input end of a channel plate of the measurement instrument; the input end (2) of a panel of the measurement instrument is connected with the electromagnet; and whether the current input end of the measurement instrument has over-current or not is monitored by the coreless electromagnet and the reed switch which penetrates through the coil of the electromagnet. Whether the current input end of the measurement instrument has the over-current or not is monitored by the coreless electromagnet and the reed switch which penetrates through the coil of the electromagnet, so that the over-current quick-protection circuit has the advantages of no influence on the input impedance of the measurement instrument and no undesirable impact on the measurement accuracy of the measurement instrument, can be used for quick protection over alternating over-current or direct over-current, is wide in application range, quick in protection and high in current conveyance capability, and can effectively prevent the damage of instantaneous high current to a channel circuit of the measurement instrument.