7 results about "Current limiting reactor" patented technology

The application relates to the technical field of power distribution networks, and discloses a novel DC power distribution network hybrid current limiter and a polarity self-recovery control method, wherein the hybrid current limiter comprises: hybrid current limiters which are respectively arranged in series between current limiters and DC circuit breakers at two ends of a DC line, and each end hybrid current limiter comprises a current passing branch, a current limiting branch and a commutation branch; the current passing branch is used for providing a current passing path; the current limiting branch is used for limiting the increase of a fault current; and the commutation branch is used for performing current commutation of the current passing branch and the current limiting branch to block the passing of the fault current from the current passing branch; the application not only improves the fault current limiting capacity of the DC power distribution network, but also reduces the breaking stress of the DC circuit breaker and the investment cost of the DC power distribution network system, and realizes fast reclosing.

The application discloses a fault current limiter input method based on a voltage drop criterion and belongs to the technical field of power system fault protection, which comprises the following steps: collecting three-phase voltage instantaneous values of a fault current limiter installation point and calculating zero sequence voltage; synchronously calculating real-time voltage amplitude and voltage change rate; comparing the real-time voltage amplitude and the voltage change rate with preset criteria and combining zero sequence voltage auxiliary criteria to determine a ground fault; quickly opening a switch to input a current limiting reactor when the fault occurs; and closing the switch to exit the current limiting reactor after the fault is eliminated. The application adopts a comprehensive design of double main criteria of voltage amplitude and voltage change rate plus zero sequence voltage auxiliary criteria, can accurately distinguish a ground fault from normal fluctuations of a power grid, avoids misjudgment and missed judgment, has a quick sampling response, realizes quick input of current limiting by cooperating with a quick switch, can be self-adaptively adjusted according to actual power grid parameters and operating conditions, can effectively suppress a fault current peak value, prevents power equipment from being damaged, and practically improves the safe and stable operation level of a power system.

This invention discloses a short-circuit current limiting system and method, relating to the field of short-circuit current limiting, including a fast switch and a current-limiting reactor; the fast switch includes an arc-extinguishing chamber and a fast mechanism, the fast mechanism including an electromagnetic drive component and a trigger circuit; the method comprises: calculating and obtaining the peak value of the first half-wave short-circuit current and the time of the first zero-crossing point; determining whether the fast switch should trip based on the peak value of the first half-wave, thereby reducing the number of system trips; determining the tripping time of the fast switch based on the zero-crossing point, thereby reducing the arc-extinguishing chamber arcing time; calculating and obtaining the peak value of TRV, adjusting the charging voltage of the trigger circuit based on the peak value of TRV, reducing the stress on the fast mechanism, thereby improving the overall lifespan of the system.

The application relates to a built-in current-limiting reactor, which comprises an upper yoke, a coil and a lower yoke arranged in sequence from top to bottom, wherein the upper yoke is provided with an upper yoke frame, the upper side of the upper yoke frame is provided with an upper connecting seat, the inside of the upper yoke frame is provided with upper silicon steel sheets, the upper silicon steel sheets are insulated from the upper yoke frame and connected with the upper connecting seat, the upper connecting seat is connected with a corresponding upper clamp of a transformer, the lower yoke is provided with a lower yoke frame, the lower side of the lower yoke frame is provided with a foot pad, the inside of the lower yoke frame is provided with lower silicon steel sheets, the lower silicon steel sheets are insulated from the lower yoke frame and connected with the corresponding foot pad, the foot pad is connected with a corresponding lower clamp of the transformer, vertical screw rods are arranged between the upper yoke and the lower yoke, the upper ends of the vertical screw rods are fixedly connected with the corresponding upper connecting seats, the lower ends of the vertical screw rods are fixedly connected with the corresponding foot pads, upper lead wire rows and lower lead wire rows are arranged outside the coil, and the upper lead wire rows and the lower lead wire rows are respectively connected with corresponding low-voltage lead wire rows of the transformer. The built-in current-limiting reactor has lower cost, smaller loss, stronger short-circuit resistance, shortened production cycle and reduced installation space.

This invention relates to the field of power system transformer protection technology, and discloses a method and device for suppressing transformer inrush current, comprising the following steps: disconnecting the bypass switch before energizing the transformer, so that the current-limiting reactor is in series; after the main circuit breaker is closed, the transient inrush current is limited by the current-limiting reactor; acquiring the transformer current signal, calculating the proportion of the second harmonic and the fluctuation rate of the fundamental current effective value; when the closing time or the proportion of the second harmonic and the effective value of the fundamental current both meet the preset switching criteria, calculating and outputting a closing command based on the current zero-crossing point and the inherent operating time of the bypass switch, short-circuiting the current-limiting reactor. This invention effectively limits the amplitude and duration of the inrush current at the moment of closing, while having no additional losses or voltage drop during normal operation. It has the advantages of simple principle, reliable operation, good economy and easy modification, and is applicable to various types of transformers.

The application discloses a kind of based on the multi-terminal direct current system relay protection method and device of MMC active current limiting, belong to power grid protection field;By limiting the direct current fault current of MMC at k1 times rated current, thereby effectively eliminating short-time direct current short-circuit fault, control is relatively simple, and reliability is higher.On this basis, a kind of MMC hardware and software combined end direct current system relay protection method is presented, reduces the demand to direct current side current limiting reactor, can realize the accurate control of fault current.In addition, a kind of strategy for coping with permanent fault is also proposed, to ensure that multi-terminal direct current system MMC has excellent fault response capability whether in short-time fault or permanent fault.Finally, the MMC dominant direct current short-circuit fault selective protection strategy is presented, using the injected amplitude droop type ac current signal realizes the three-stage selective protection of short-circuit fault, reduces the cost and design requirement of direct current line protection, and is suitable for the multi-terminal direct current system containing complex branch structure.