44results about How to "Suppresses inrush current" patented technology

The invention discloses a phase selection control method aimed at a zero-load transformer comprising a primary side employing star ungrounded connection and calculating the influence of residual magnetism of the zero-load transformer. A vacuum breaker, a current zero crossing detection circuit, a voltage zero crossing detection circuit and a control circuit are included. The method is characterized in that (a) when the breaker is opened, a phase B of the breaker is firstly disconnected when a current of the phase B crosses zero, then currents flowing through a phase A winding and a phase C winding of the transformer are of the same size and opposite directions, and when the two currents cross zero, a phase A and a phase C of the breaker are disconnected simultaneously, and phase angles of voltages of the two phases at the moment of disconnection are recorded; and (b) when the breaker is closed, the phase A and the phase C of the breaker are closed at the same time if the voltage phase angles of the two phases equal the voltage phase angles of last breaker opening, and the phase B of the breaker is closed when the voltage of the phase B reaches a peak value. The method can effectively inhibit inrush current of a closing moment of the zero-load transformer.

The invention discloses a commutation transformer phase-selective closing excitation inrush current suppression method based on bias magnet simulation. The method includes: 1. Estimating the three-phase residual magnetism values ​​of Y-bridge and D-bridge converter transformers; 2. Extracting and considering the circuit breaker series connection The influence of the gate resistor on the closing bias amplitude and phase is used to construct the bias function; 3. Compare the residual magnet estimated when the converter transformer is opened with the bias function to obtain the appropriate closing time of the converter transformer. . The present invention can utilize the residual magnetism when the converter transformer opens and the bias magnetism when it closes to offset each other, effectively improves the excitation inrush current suppression effect of the converter transformer, and helps to suppress commutation problems during maintenance of high-voltage direct current transmission projects and changes in operating modes. The excitation inrush current caused by the transformer closing and charging can improve the commutation failure problem caused by the excitation inrush current of the commutation transformer.

The invention provides a phase-selection switching control method of a non-contact regulating voltage stabilizing device, including the following: designing the structure of a non-contact compensation type AC voltage stabilizing device; according to the structure of the non-contact compensation type AC voltage stabilizing device, analyzing its Working principle, the relationship between the output voltage and the input voltage of the non-contact compensation type AC voltage stabilizing device is obtained; the circuit model of the three-phase voltage regulating transformer is simplified, and the main magnetic flux of the three-phase voltage regulating transformer is obtained by calculation; the analysis of the three-phase voltage transformer For the main magnetic flux of the voltage regulator, a phase selection switching strategy based on load characteristics is designed, and then the switching mode of the thyristor assembly is changed, and the excitation inrush current existing in the switching process of the non-contact compensation AC voltage stabilizing device is suppressed. The beneficial effects provided by the invention are: maximally restraining the excitation inrush current during the phase selection and switching process of the non-contact regulating and stabilizing device, and ensuring the stability and reliability during the switching process of the device.

According to one embodiment, a magnetizing inrush current suppressing device includes, a first closing unit closes the circuit-breaker at the notable phase by the first phase determined by the first-phase determination unit, a second-phase determination unit determines a second phase at which the notable phase detected by the notable phase detection unit from the three-phase AC voltage measured by the power-supply-side voltage measurement unit becomes a zero point after the first phase determined by the first-phase determination unit, and a second closing unit closes the circuit-breaker at two phases other than the notable phase by the second phase determined by the second-phase determination unit.

The invention relates to a device and a method for inhibiting inrush current upon switching on an idling transformer. The device includes more than one thyristor set linked between an AC power switch and the transformer, each phrase of the AC current is linked to at least one thyristor set; a side contactor parallely linked to the thyristor sets; a resistance-capacitance circuit parallely linked to two ends of a thyristor power module which forms the thyristor set. A front end voltage transformer in the system tests the power voltage; a current transformer tests the phase current of the transformer; a back end voltage transformer tests transformer voltage whose signal output terminals are respectively linked to the corresponding input terminals of a control unit. The control unit firstly calculates the size and phase of the pre-magnetizing flux linkage in the transformer, and calculates the link time for the premier winding sets to determine the connecting time for the thyristor set, as well as the link time for other winding sets, finally short-circuits the thyristor through the side switch sets. The invention can inhibit the excitation inrush current upon switching on the idling transformer to a great extent.

According to one embodiment, in the case where the transformer is connected to the first power source through the first circuit breaker and the second power source is connected through the second circuit breaker, if it is detected that the transformer is disconnected from the power source, then according to the calculated The residual magnetic flux and voltage of the first power supply are used to close a specific phase of the three phases of the first circuit breaker to suppress the inrush current, and then the remaining two phases of the first circuit breaker are closed. According to the calculated residual magnetic flux and voltage of the second power supply, one specific phase of the three phases of the second circuit breaker is closed to suppress the inrush current, and then the remaining two phases of the second circuit breaker are closed .