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

This is a device to avoid transformer flow upon switch on in idling and the method. The device includes more than one switching sets linked between the power switch and the transformer, each phrase of the alternating current is linked to at least one switching set; a side contactor parrell linked to the switching sets; a control unit; a front end voltage transformer for testing power voltage; a current transformer for testing transformer current; a back end voltage transformer for testing transformer voltage whose signal output is linked to the control unit and calculates the size and phase of the magnetic flux linkage of the internal pre-incharged magnetism of the transformer, and calculates the link time for the premier winding sets to decide the connecting time for the contactor, as well as the link time for other winding sets for contacting of the side switch sets.

A control unit 13 of an electric power supply system causes, responsive to a closing command signal phi B, a switch 2 corresponding to R phase to be thrown at a timing when a stationary magnetic flux and a residual magnetic flux of R phase are coincident with each other and then subsequently causes other switches 3, 4 corresponding to S phase and T phase to be thrown at a timing which is delayed from a zero point of an alternating voltage of R phase by a predetermined phase angle of 0-30 degrees, such that the difference of the stationary magnetic flux and the residual magnetic flux of each of S phase and T phase is minimum. Therefore, an exciting incoming current which flows into a three-phase transformer 8 at a time of throwing a three-phase breaker 1 provided with interpole capacitors 5-7 can be suppressed.

The invention discloses a train-mounted transformer magnetizing inrush current suppression method and a combined circuit breaker system which have a function of suppressing train-mounted transformer magnetizing inrush current. The combined circuit breaker system structurally comprises a control loop and a main circuit, the control loop comprises a controller, a voltage sensor and a current sensor,and the main circuit comprises a solid-state circuit breaker and a mechanical circuit breaker. The invention further provides new circuit breaker system topology. A phase selection making control strategy is adopted to suppress train-mounted transformer magnetizing inrush current, in other words, at the moment of opening the combined circuit breaker, residual magnetism is calculated according toa relation between flux and voltage phase and recorded; at the moment of closing of the next time, circuit breaker closing phase angle is calculated through the residual magnetism and attenuation coefficient thereof, and a calculating principle is enabling stable-state flux at the moment of closing and residual magnetism of a transformer to have no error to achieve the objective of suppressing themagnetizing inrush current. A solid-state circuit breaker module is added into the main circuit, so that response speed is increased while resistance to voltage and current of the circuit breaker system is ensured.

The invention discloses a transformer excitation surge suppression device, which realizes that a current value of a line measured by a current transformer does not change suddenly due to excitation surge caused by no-load input of the transformer when lines in 110kV and above realize longitudinal current differential protection during relay protection of an electric system, and ensures operation correctness of a relay protection device. The excitation surge suppression device is formed by a power supply module, a CPU module, a data storage module, a data display module and an encryption module. The device relates to the technical field of relay protection, electric power system transient stability and power electronic technology and the like. For the problems of maloperation of traditionallongitudinal current differential protection during no-load input of the transformer and loss of accuracy of the relay protection device and the like, by controlling remanent magnetism and no-load input angle of the transformer, three-phase excitation surge is suppressed, and the transformer is allowed to enter steady-state operation smoothly when voltage in the electric system changes suddenly.

The invention discloses a transformer excitation inrush current suppression system based on closing voltage frequency control and a transformer excitation inrush current suppression method thereof. The transformer excitation inrush current suppression method comprises the steps that residual magnetism detection and parameter setting are performed; a control function is generated, and the parameters of the control function are calculated; and a system power supply and the primary side of a transformer are connected through a closing voltage frequency control system, voltage frequency inputted to the transformer is changed according to the control function, and control is ended and the closing voltage frequency control system is disconnected and the power supply and the primary side of the transformer are directly switched on. The beneficial effects of the system and the method are that the size of magnetic flux in the no-load closing process of the transformer can be accurately controlled so that the magnetic flux is enabled not to exceed saturation magnetic flux which can be borne by a transformer iron core, and the objective of excitation inrush current can be achieved; excitation inrush current can be fundamentally suppressed, and the influence of excitation inrush current on the transformer and transformer protection equipment can be more effectively avoided; and selection and setting of the control function are allowed so that flexibility of the control scheme and adaptability to different types of transformers can be ensured.

According to an embodiment, when a transformer that is connected to a first power supply through a first breaker as well as to a second power supply through a second breaker is detected to be disconnected from the power supplies, a specific phase of the three phases of the first breaker is closed to suppress an excitation inrush current, based on calculated residual magnetic fluxes and a voltage of the first power supply, and thereafter, the remaining two phases are closed. Based on the calculated residual magnetic fluxes and a voltage of the second power supply, a specific phase of the three phases of the second breaker is closed to suppress an excitation inrush current, and thereafter, the remaining two phases are closed.

The invention discloses a switch-on voltage amplitude control based excitation surge suppression system and method of a transformer. The method comprises the following steps of detecting residual magnetism; setting a parameter; generating a control function, and calculating the parameter of the control function; and connecting a system power supply and a primary side of the transformer by a switch-on voltage amplitude control system, changing a voltage amplitude input to the transformer according to the control function, completing the control of switching off the switch-on voltage amplitude control system, and directly switching on the power supply and the primary side of the transformer. The method has the advantages that the size of the excitation surge during the no-load switch-on process of the transformer can be accurately controlled and cannot exceed saturated magnetic flux borne by a transformer iron core, so that the purpose of preventing excitation surge is achieved; the excitation surge can be fundamentally suppressed, and the influence of the excitation surge on devices such as the transformer and a transformer protection device can be effectively prevented; and the control function is allowed to be selected and set, and the flexibility of a control scheme and the adaptability to different types of transformers can be ensured.

The invention belongs to the technical field of transformer equipment protection and operation control, and relates to a transformer operation control method with economical operation and automatic switching to suppress excitation inrush current, which can protect the operation of transformers in power transmission systems. The phase angle of the circuit breaker opening and closing voltage in the transportation system realizes the mutual cancellation of the bias magnetism and the residual magnetism, suppresses the no-load excitation inrush current of the transformer and realizes automatic switching, and adopts the feedback mechanism to increase the control accuracy and reliability of the power transportation system, so that the power The transportation system automatically tracks and adapts to the change of opening and closing time of the circuit breaker due to aging or environmental changes; its overall control process is scientific and reasonable, the technical route is simple, the hardware and software technology is mature, the operation is safe, the control performance is reliable, and the investment Less, low operating cost, easy to popularize and use.

The invention discloses a suppression method of an excitation inrush current. The suppression method comprises the steps of S1, sampling a plurality of points of each periodic wave of a simulation value of each circuit breaker, setting preset switch-on time, setting switch-on setting angle to be 90 degrees or 270 degrees, and setting a rated current peak; S2, acquiring actual switch-on time, a switch-on angle and a switch-on current peak when the circuit breaker is switched on, and calculating to obtain switch-on time difference and switch-on angle difference; S3, switching off the circuit breaker; and S4, correcting switch-on time to be used as next switch-on time according to the switch-on angle difference, obtaining a new switch-on angle and a circuit peak, considering excitation inrushcurrent suppression to be success when the switch-on angle approximates to the switch-on setting angle and the current peak approximates to the rated current peak, otherwise, continuing to repeat thestep S3 and the step S4. By a flexible control method, the excitation inrush current is effectively suppressed, and great convenience and flexibility are provided for a relay under various special working conditions.

A magnetizing inrush current suppression device (6) that controls a breaker (2), wherein inter-pole capacitors (22U, 22V, 22W) are connected, and which opens/closes a connection between a transformer (3) and a three-phase alternating-current power supply (1) so as to control magnetizing inrush current. On the basis of the three-phase alternating current voltages (Vtu, Vtv, Vtw) on the transformer side of the breaker (2), the phase for which the absolute value is the largest or the phase for which the absolute value is the smallest, of the direct current components (Zdu, Zdv, Zdw) of the three-phase residual flux, is detected as the phase of interest. In addition, the breaker (2) is closed at the phase of interest when the phase of interest of the three-phase alternating current voltages (Vu, Vv, Vw) on the power supply side is a closing target phase (thetac1) having a wave-height value which is the reverse polarity of the polarity of the direct current component (Zdu, Zdv, Zdw) of the residual flux, and the breaker (2) is closed at the two phases other than the phase of interest when the phase of interest of the three-phase alternating current voltages (Vu, Vv, Vw) on the power supply side is a closing target phase (thetac2) which reaches zero after the closing target phase (thetac1).

A capacitive current transformer structurally comprises a primary winding, a secondary winding and an annular iron core. The secondary winding is composed of one or more groups of capacitive windings,different wiring modes are adopted, high potential generated when the secondary winding is in an open circuit state is added to the two poles of the capacitor, the positive feedback capacitor currentinducted by the secondary winding is close to the same primary load current in the same phase, and therefore the power input current is reduced, and the energy-saving effect is achieved. Meanwhile, higher harmonic current can be suppressed, the power factor of a power grid is improved, and the starting current of the motor and the no-load closing magnetizing inrush current of the transformer arereduced.

The invention relates to the technical field of excitation inrush current suppression, and discloses a method, a system and equipment for evaluating the minimum input time of a closing resistor of a circuit breaker. According to the method, the steady-state magnetic flux of the transformer corresponding to the circuit breaker and the closing angle when the auxiliary contact in the circuit breaker is closed are determined, and then the minimum discontinuity angle of the excitation inrush current is calculated according to the steady-state magnetic flux and the closing angle. And finally, evaluating the minimum input time of a closing resistor of the circuit breaker according to the minimum discontinuity angle and the closing angle. The minimum input time of the closing resistor is determined according to the minimum discontinuity angle of the magnetizing inrush current and the closing angle of the auxiliary contact, and compared with the mode that the minimum input time of the closing resistor is set according to empirical parameters in the prior art, the magnetizing inrush current can be restrained more effectively.

The invention discloses an intelligent operation box with an inrush current suppression function, which comprises a main board, an AC quantity collection module, an input module, an output module anda voltage switching module. A main board comprise a management CPU and a first FPGA, wherein that first FPGA and each module are connected and communicate through a BLVDS bus. The management and control CPU acquires the AC quantity data collected by the AC quantity collection module and the input quantity data collected by the input module through the first FPGA. Then, according to the acquired data, the switching bus PT operation instruction is transmitted to the voltage switching module to switch on and off the corresponding bus PT, and when the inrush current inhibition criterion is operated, the switching operation instruction is transmitted to the opening/closing module to control the corresponding circuit breaker to complete the switching operation by using the preset inrush currentinhibition algorithm. The invention can improve the accuracy of the opening and closing angle control of the circuit breaker, effectively suppress the excitation inrush current generated when the transformer is airdropped, realize the intelligence of the operation box, and have the operation and communication ability.

The invention discloses an inrush current suppression device suitable for testing transformer frequent no-load input. The device is completely serially connected into a power supply loop, the protection and operation method of the original power supply and distribution system will not be changed, so advantages of simple transformation and convenient operation can be realized; and the control circuit is composed of a time relay and a contactor, so advantages of simple structure and no complex digital control can be realized, and the time of the time relay can be adjusted according to actual needs to satisfy the transformer soft starting requirements of different rated capacities and currents, so the device has advantages of broad applicability and wide application range, and play an important support and guarantee in the test of the whole high-power power electronic equipment.