381results about How to "Small current" patented technology

The invention discloses a braille point display device. According to the Braille point display, the shape memory alloy material is used as the lifting structure, and the lifting structure is controlled to deform under the power-on condition, so that the point display part is driven to extend or retract relative to the mounting main body. Compared with piezoelectric driving and electromagnetic driving equipment, the shape memory alloy material can adjust the deformation quantity through the power-on state, large deformation quantity can be generated through a small structural material, the size of a lifting structure does not need to be increased, the driving structure of the braille convex points is effectively simplified, the size of the equipment is reduced, and the production cost of the equipment is reduced. And meanwhile, the locking mechanism is arranged, so that the telescopic state of the point display part is kept, the situation that the lifting structure is always kept in a power-on state is avoided, and the power consumption of equipment is reduced.

The invention relates to the technical field of size detection, in particular to a size detection device and method special for a perfume bottle cap, and the device comprises a detection part which comprises a detection box body. Light emitted by the LED light source is refracted by the convex lens and then is flatly emitted to the projection curtain through the light cylinder and the open openings of the plurality of light barriers in parallel, and a part of the light is shielded by the bottle cap, so that a shadow is formed in the middle of the projection curtain; the camera shoots the front-back width and height of the shadow part on the projection curtain and compares the front-back width and height with the scale marks on the projection curtain, the width and height size of the bottle cap can be measured, multiple times of measurement are not needed, the detection efficiency is improved, the servo clamping jaw is driven to rotate through the output shaft of the angle adjusting motor, and the detection precision is improved. In the rotating process of the bottle cap, the two cameras carry out shooting continuously, the multi-dimensional angle of the bottle cap is measured, and the flexibility of size detection of the bottle cap is improved.

The invention belongs to the technical field of transcranial magnetic stimulation medical treatment. The problems that in an existing transcranial magnetic stimulation technology, the focusing performance of a deep specific brain area is not high, positioning is not accurate, and full-path superficial layer tissue is strongly stimulated are solved. According to the deep transcranial magnetic stimulation positioning navigation system based on time interference, based on the time interference principle, stimulation currents with different frequencies are applied to two sets of transmitting coils, low-frequency envelope waves are overlaid in the skull, and therefore the current magnitude is reduced, and the focusing degree is improved. Data support is provided for accurate positioning of the head posture of a patient based on a depth camera, and a multi-degree-of-freedom coil capable of generating an omni-directional magnetic field in space is provided. By reasonably adjusting the amplitude of the current introduced into the coil, the magnetic field can automatically move to the stimulation point of the head of the patient for treatment, the stimulation target is changed by adjusting the electrical parameters, and the low-frequency envelope magnetic field is obtained by modulation at the stimulation target, so that the target neurons are magnetically stimulated.

The invention discloses soft tissue high-frequency welding equipment, and belongs to the technical field of surgical operating instruments, the soft tissue high-frequency welding equipment comprises an electrocoagulation pen main body, the electrocoagulation pen main body is connected with an insulating rod, the insulating rod is further provided with a conduction pipeline parallel to a cutter head part, and a temperature sensing unit comprises a hinting structure and a telescopic action structure. The electric resection temperature of the knife head part can be sensed in real time through the action structure in the temperature sensing unit, and when the knife head part is overheated, the action structure can be converted into an extension state from an initial retraction state and triggers the indicating structure to protrude out of the surface of the electrocoagulation pen main body, so that a doctor is reminded to cool the knife head part in time; therefore, in the electric resection operation process of the hypertrophy tonsil and adenoid body of the child, the situation that the scalpel head part is overheated in the long-time continuous state of the operation and burns the tissue of the affected part of the child is effectively avoided, the safety of the soft tissue resection operation of the child is improved, and postoperative recovery and healing of the operative part of the child are facilitated.

The current collector comprises a foil and a conductive layer, the conductive layer and the foil are stacked, the conductive layer comprises a first area and a second area, the first area is closer to the edge of the foil than the second area, the conductivity of the first area in the first direction is A, the conductivity of the second area in the first direction is B, and A is smaller than B. By arranging the foil and the conductive layer, the conductivity A of the first region and the conductivity B of the second region meet the condition that A is less than B, the conductivity of the edge of the current collector can be inhibited, and the current of the current collector can be reduced, so that the temperature rise of the edge region is reduced, the temperature difference between the edge of the current collector and the middle of the current collector can be reduced, lithium precipitation is reduced, and the service life of the battery cell is prolonged.

The invention discloses a nonlinear time-delay regulation and control device, which solves the problem that an electric appliance is unstable when the electric appliance is connected into a circuit when the current in the circuit is nonlinear and has large fluctuation, and comprises a box body, a control panel is arranged on the front surface of the box body, and wiring terminals are symmetrically arranged on the two sides of the box body. A power connection adjusting assembly is installed in the box body and used for controlling and adjusting, a top adjusting and controlling assembly is installed at the top end of the box body and used for adjusting non-linear current, the power connection adjusting assembly comprises a transverse plate movably installed in the box body, and end contacts are symmetrically installed at the two ends of the transverse plate. A normal power connection unit is installed on the transverse plate and used for power connection adjustment. In the working process, when the arranged transverse plate is located on the lower portion, a circuit can be normally connected into an electric appliance, after the transverse plate moves upwards, the circuit can be connected into regulation and control equipment, and the circuit can be conveniently regulated and controlled.

The invention belongs to the technical field of generators, and particularly relates to a hybrid nano generator and a power management circuit thereof, comprising a shell, and an electromagnetic power generation unit, a friction power generation unit and a piezoelectric power generation unit which are located in the shell; and a corresponding power management circuit. The interior of the shell is connected with the top end and the bottom end in a penetrating mode through a glass fiber connecting shaft. A friction power generation unit, an electromagnetic power generation unit and a piezoelectric power generation unit are sequentially mounted at the bottom end, opposite to the shell, of the glass fiber connecting shaft; the piezoelectric power generation unit comprises at least four cantilevers and a disc, one end of each cantilever is fixed on the disc, and a mass block is placed on the upper surface of the other end; the center of the disc is connected with a glass fiber connecting shaft, and the inner sides of the upper surfaces of the four cantilevers are covered with PZT materials. According to the hybrid nano generator, vibration energy in the environment can be converted into electric energy, and energy is supplied to wireless sensor network nodes.

The invention relates to an outdoor communication cabinet which comprises a cabinet body and further comprises a bearing box, a gas storage part, a gas spraying pipe and a driving part. An air storage part is installed above the bearing box, an opening in the right end of the bearing box communicates with the cabinet, and a dustproof net is fixed in the bearing box; the air storage part comprises a shell and a piston plate, an elastic cylinder is connected between the piston plate and a rear side plate of the shell, an air inlet valve is arranged on the rear side plate of the shell, a first sliding hole is formed in the top plate, on the right side of the dustproof net, of the bearing box, and the upper end of the air spraying pipe penetrates through the first sliding hole and extends into the piston plate. The elastic cylinder is communicated with the upper end of the gas ejector pipe through a one-way gas outlet valve arranged on the piston plate; the driving part comprises a connecting box and a rotating shaft, the interior of the connecting box is divided into an upper cavity and a lower cavity through a partition plate, the rotating shaft is rotationally arranged in the upper cavity, the upper portion of the rotating shaft is connected with a pull rope, and the other end of the pull rope backwards penetrates through the shell to be connected with the piston plate. According to the invention, the problem that the dustproof net of the outdoor communication cabinet for isolating dust is easily blocked by dust is solved.

According to the ultra-low power consumption Doppler radar chip capable of reducing the duty ratio and improving the impedance and the method thereof, the chip comprises a register, a control circuit, an analog delay circuit, an impedance control switch, a differential amplifier and the like, and the charge leakage amount of a sampling capacitor during the non-working period of a radio frequency circuit is reduced by improving the turn-off impedance of a frequency mixer; and the input impedance of the amplifier is improved to reduce PWM ripples on an intermediate frequency signal, so that the detection performance of a radar chip during intermittent working of a radio frequency circuit under the control of a PWM power-saving pulse is maintained as much as possible, a conventional power-saving mode is changed into an ultra-low power consumption mode, and the working current of a radar module is reduced from several milliamperes to dozens of microamperes. The method can be used for any motion induction radar sensor chip and module with power-saving control, especially a battery-powered access control system and a low-cost bulb lamp in a capacitor voltage reduction mode of high-voltage partial-voltage power supply.

The invention provides a method for prolonging the service life of an electrode during resistance spot welding of an aluminum-zinc plated steel plate, which relates to the technical field of welding and comprises the following steps: machining the aluminum-zinc plated steel plate into a preset workpiece; performing pretreatment; setting welding process parameters; welding; the welding spot quality evaluation is used for obtaining the nugget diameter of the welding spot on one hand and comparing the nugget diameter of the welding spot with a preset nugget diameter index on the other hand, and when it is judged that the nugget diameter of the welding spot meets the requirement, shearing force value judgment is executed, and therefore an evaluation result is output; and electrode quality evaluation: on one hand, acquiring the working surface diameter of the electrode, and on the other hand, comparing the working surface diameter change of the electrode with the preset working surface diameter change so as to evaluate the wear condition of the electrode. By optimizing the resistance spot welding process, the current is reduced, so that the instantaneous welding temperature is reduced, the generation of Cu-Zn alloy with poor electrical conductivity and thermal conductivity and the adhesion on the electrode are reduced, the temperature rise of the electrode is delayed, and the service life of the electrode is prolonged.

The invention relates to the technical field of photovoltaic panels, in particular to an automatic cleaning device for a solar photovoltaic panel. According to the technical scheme, the electromagnetic attraction assembly comprises a protective shell, an iron column, a coil, a hydraulic assembly, a magnetic metal block, an annular magnet and a hydraulic telescopic rod, the protective shell is fixedly installed on the side of an upper expansion plate, the iron column is fixedly installed in the protective shell, and the coil electrically connected with a solar panel is wound around the cambered surface of the iron column; a hydraulic assembly is fixedly installed in the protective shell and located at the end of the iron column, and an annular magnet is fixedly installed at the end of the hydraulic assembly. After the surface of the solar panel is covered with dust, the power generation efficiency of the solar panel is reduced, and the current flowing in the coil is reduced, so that the hydraulic telescopic rod extends out to enable the cleaning piece to move on the surface of the solar panel, the dust on the surface of the solar panel is scraped, and the influence of dust covering on power generation of the solar panel is avoided.

The invention discloses a method for protecting a transistor, a protection circuit and a control circuit. The protection circuit comprises a first protection circuit; one end of the first protection circuit is connected with the driving signal output end of the driving circuit, and the other end is connected with the driving end of the to-be-driven transistor; the first protection circuit is used for sharing the charging voltage of the driving end capacitor of the transistor to be driven when the driving voltage provided by the driving circuit enables the first voltage of the first protection circuit not to reach the first working voltage; when the driving voltage provided by the driving circuit enables the first voltage to reach the first working voltage, entering a first conduction state, and controlling the conduction or turn-off of the to-be-driven transistor according to the driving voltage in the first conduction state; and under the condition that the transistor to be driven is conducted, when the driving voltage provided by the driving circuit enables the second voltage of the first protection circuit to reach the second working voltage, the first protection circuit enters a first turn-off state, and the transistor to be driven is controlled to be turned off or conducted after entering the first turn-off state.

The utility model provides an intelligent damper based on laminated MRE and a damping base. The intelligent damper based on the laminated MRE comprises an outer sleeve and an inner sleeve which can move relatively, the outer sleeve comprises a first sleeve body and a second sleeve body, the inner sleeve comprises a third sleeve body, the end of the third sleeve body is inserted into an annular cavity formed by the first sleeve body and the second sleeve body, and the head of the second sleeve body is connected with the bottom wall of the third sleeve body through an elastic piece. A first annular cavity is formed between the first sleeve and the third sleeve, a second annular cavity is formed between the third sleeve and the second sleeve, a plurality of laminated MRE units are arranged in the circumferential direction of the first annular cavity and the circumferential direction of the second annular cavity at intervals, and each laminated MRE unit is correspondingly sleeved with an enameled coil. According to the intelligent damper, the coil is directly wound around the MRE, and under the same MRE effect, the current needing to be connected can be reduced, so that the calorific value is reduced, and the intelligent damper is safer and more suitable for continuous power-on work.

The invention relates to an input voltage power failure locking and startup and shutdown instruction control circuit and a working method thereof. The circuit comprises a short circuit protection unit, a surge suppression unit, an EMI filtering unit, a DC / DC conversion unit, an output filtering unit and a control circuit unit. The control circuit unit comprises an input bus power failure locking unit, a shutdown control instruction unit, a startup control instruction unit and a startup and shutdown state locking unit. The method is suitable for a power supply and distribution system in aerospace electronic equipment, and can be widely applied to other various power supply and distribution systems which work reliably for a long time. According to the method, the reliability of pulse instruction control on and off of the power supply and distribution system in the electronic equipment for space navigation can be guaranteed, when the primary input bus voltage breaks down or returns to normal, the power supply can be effectively in the off state, the effective on and off instruction can be retransmitted through the platform, and it is guaranteed that the system is reliably restarted and operated.

The utility model relates to the technical field of power transmission line fittings, and discloses a wire strain clamp capable of effectively inhibiting heating of a drainage plate, which comprises a steel anchor (1), a strain clamp body (2), a drainage clamp (3), a bolt assembly (4) and a bypass flexible jumper wire (5), a steel core part of a wire is crimped in the steel anchor, an aluminum stranded wire part is crimped in an aluminum pipe of the clamp body, and the bypass flexible jumper wire (5) is crimped in the strain clamp body. The jumper wire is crimped in the main drainage aluminum tube of the drainage wire clamp; one end of the bypass flexible jumper wire is crimped in the auxiliary drainage aluminum tube of the drainage wire clamp, and the other end of the bypass flexible jumper wire is crimped in the drainage aluminum tube of the strain clamp body; the strain clamp body drainage main plate is connected with the main drainage connecting plate through a bolt assembly. According to the utility model, by arranging the bypass flexible jumper wire, the current flowing through the strain clamp is shared; the main drainage plate and the main drainage connecting plate of the wire clamp body are sawtooth-shaped, the contact area is increased, the contact resistance is reduced, and the bolt assembly for connecting the main drainage plate and the main drainage connecting plate is provided with the anti-loosening hoop, so that loosening is avoided, and heating of the drainage plate is effectively inhibited.

The invention provides a method for improving the hardenability of a gear steel bar and the gear steel bar, and belongs to the technical field of continuous casting process.The method comprises the steps that molten steel with qualified components is cast through a continuous casting machine; in the solidification stage, a reduction process is adopted; after solidification, the hot-state casting blank is rolled; in the continuous casting process, the superheat degree of a tundish is 40-45 DEG C, and the electromagnetic stirring current of a crystallizer is 50-150A; according to the reduction process, the reduction amount is controlled through the change of the center solid fraction of a casting blank, the center solid fraction of a reduction area is 0.05-1.0, and the reduction amount is not smaller than 1 mm and not larger than 3 mm in a continuous casting reduction area corresponding to the center solid fraction smaller than 0.3. And the rolling section compression ratio is not less than 90%. By controlling the degree of superheat, electromagnetic stirring of a crystallizer, a pressing process and a rolling process, an equiaxed crystal area of a casting blank and a bar is reduced, meanwhile, formation of semi-macroscopic point segregation of the equiaxed crystal area is restrained, and an as-cast structure of a bar hardenability detection area is converted into columnar crystals from equiaxed crystals; and the section solute range and standard deviation and dendritic structure solute distribution uniformity are further improved, the A and B surface difference values of J9 and J15 are both smaller than or equal to 1.5 HRC, the hardenability index is qualified, the subsequent gear heat treatment non-uniform distortion is reduced, and the product homogeneity is improved.

This application provides a perovskite light-emitting module and its fabrication method, belonging to the field of semiconductor optoelectronic device manufacturing technology. The perovskite light-emitting module includes: a substrate, and multiple perovskite light-emitting units located on the substrate; wherein, along the direction away from the substrate, each perovskite light-emitting unit sequentially includes an anode, a hole transport layer, a perovskite layer, an electron transport layer, and a cathode; the multiple perovskite light-emitting units are arranged in series, and in two adjacent perovskite light-emitting units, the cathode of the preceding perovskite light-emitting unit is electrically connected in series with the anode of the following perovskite light-emitting unit.

The application relates to a direct current power distribution system with a direct current bus architecture reconstruction capability, comprising a plurality of alternating current power sources, a plurality of corresponding AC / DC energy routers, a plurality of corresponding direct current bus switching switches, positive / zero / negative direct current buses, a power frequency isolation transformer and a plurality of DC / DC charging modules constituting a direct current load. The working state of the system can be transformed among two unipolar direct current bus architectures and a true bipolar bus architecture. Compared with the prior art, the application has the advantages of flexibly meeting the needs according to the changes of load access and the like.

The present invention discloses a plasma cutting device for producing marine cold storage, which belongs to the field of plasma cutting technology, and comprises: a base; a driving mechanism, the driving mechanism comprises a fixed frame, a mobile frame and a mounting plate, the mobile frame is fixedly mounted with a mobile plate on the top, the front side of the fixed frame is fixedly mounted with a first driving motor, and the output shaft of the first driving motor is fixedly connected with a first screw rod; a self-adjusting mechanism, the self-adjusting mechanism comprises a connecting plate, an adjusting plate and two balls, and the connecting plate is fixedly mounted on the bottom of the mounting plate; a plasma cutting gun, the plasma cutting gun comprises a plasma emitter and a cutting gun body arranged at the bottom of the plasma emitter. The present invention can automatically adjust the moving speed and working power of the plasma cutting gun when cutting workpieces of different thicknesses through the self-adjusting mechanism to meet the needs, thereby being able to adapt to the cutting work of complex components in marine cold storage.

The present invention relates to the field of motors or electric vehicles, and specifically to a slow-start permanent magnet motor, which is provided with a position detection disk, a time-controlled conduction switch and an inertial feedback device. The time-controlled conduction switch is driven by the inertial feedback device to change the position detected by the inertial feedback device, thereby realizing the control of the on-off time of the time-controlled conduction switch by the conduction hole of the position detection disk, thereby achieving the purpose of controlling the output momentum. The present invention can effectively reduce the acceleration at startup, ensure driving safety, and effectively reduce the current at startup, thereby extending the service life of the motor.

The utility model discloses a hoist electromagnet of permanent magnet and electromagnetic combination, including excitation coil, magnetic pole one, magnetic pole two, iron core and non -magnetic protection board, its characterized in that still is equipped with permanent magnet block group, the permanent magnet block group horizontal setting is between magnetic pole one and magnetic pole two, and is located the top of non -magnetic protection board. The utility model discloses hoist electromagnet increased permanent magnet block group, through the common effect of permanent magnet magnetic potential and electromagnetic magnetic potential and suck up the attracted object, can reduce excitation coil current when hoisting and transporting material, reduce the energy consumption that excitation coil generates, strengthen the magnetic force intensity regulation simultaneously, realize the various operations of attracting material and discharging.

The utility model provides a power conversion system. The power conversion system comprises power equipment, a converter and a power supply device, the power equipment comprises a plug and a controller, the plug is provided with a first conductive part, and the first conductive part is electrically connected with the controller; the converter is configured to be electrically connected with the power supply device and the plug, and a second conductive part is arranged on the converter; the controller is used for receiving a level signal generated by the contact of the first conductive part and the second conductive part, and the level signal is used for controlling the power equipment to enter a current limiting mode. The utility model aims to solve the technical problem that how to ensure that the current passing through the panel does not exceed the rated current of the panel is the problem that needs to be solved urgently at present.

The utility model discloses a power amplifier protection circuit and electronic equipment, and the power amplifier protection circuit comprises an audio input end, an audio output end, a power amplifier circuit, a first resistor, a second resistor, a third resistor, a current sampling circuit, and a threshold comparison circuit. The first resistor is connected between the negative input end of the power amplifier circuit and the grounding end of the power amplifier protection circuit, the second resistor is connected between the output end of the power amplifier circuit and the audio output end, and the third resistor is connected between the negative input end of the power amplifier circuit and the output end of the power amplifier circuit; the first end of the current sampling circuit is connected with the first end of the second resistor, the second end of the current sampling circuit is connected with the second end of the second resistor, the third end of the current sampling circuit is connected with the first end of the threshold comparison circuit, and the second end of the threshold comparison circuit is connected with the negative input end of the power amplifier circuit.

The utility model relates to a TTL and RS232 intelligent automatic switching circuit comprising a change-over switch, a first movable contact of which is used for connecting a sending pin of a communication interface, a second movable contact of which is used for connecting a receiving pin of the communication interface, and a first static contact and a second static contact of which are respectively connected to a receiving end and a sending end of a TTL signal transmit-receive circuit, the third static contact and the fourth static contact are respectively connected to the receiving end and the transmitting end of the RS232 signal transceiving circuit; the control switch is connected in series between the coil of the change-over switch and the voltage source, and the controlled end of the control switch is connected to the output end of the signal acquisition circuit for controlling the action of the change-over switch; and the input end of the signal acquisition circuit is used for being connected with a sending pin of the communication interface and is used for continuously outputting a high-level signal to the controlled end of the control switch when receiving a level signal smaller than a preset voltage so as to control the control switch to be in a turn-off state. The circuit provided by the utility model can avoid the problem that the plug of the communication interface is plugged in a wrong position in the production link of electronic equipment.

The invention discloses a high-linearity low-noise amplifier based on a post-distortion technology. The high-linearity low-noise amplifier comprises a cascode structure circuit, an input matching circuit, an output matching circuit, an auxiliary amplifying circuit and a neutralizing inductor, the cascode structure circuit comprises a first cascode tube and a second cascode tube; the auxiliary amplifying circuit comprises a first common-gate tube; a grid electrode and a source electrode of the first common source tube are connected with the input matching circuit; the drain electrode of the first common-source tube is connected with the output end of the neutralization inductor and the source electrode of the first common-gate tube; the source electrode of the second common-gate tube is connected with the input end of the neutralization inductor; the drain electrode and the grid electrode of the second common-gate tube are connected with the output matching circuit; and the source electrode and the grid electrode of the first common-gate tube are connected with the auxiliary amplifying circuit. According to the invention, the balance of multiple indexes such as linearity, power consumption, gain and matching can be realized. The invention can be widely applied to the technical field of radio frequency integrated circuits.

The invention relates to a transformer closing excitation inrush current suppression device of a power supply and distribution circuit system. Wherein the branch switch is arranged on a branch led out of a low-voltage side bus of a power grid system and serves as a main switch of the branch. The boosting transformer and the branch switch are located on the same branch, and the high-voltage winding side of the boosting transformer is connected to the wire outlet side of the branch switch. The closing inrush current suppression device and the branch switch are located on the same branch, and the outgoing line side of the closing inrush current suppression device is connected to the low-voltage winding side of the boosting transformer. Through the branch circuit formed by the branch switch, the boosting transformer, the closing inrush current suppression device and the power generation equipment, the original direct closing of the main transformer and the generation of the excitation inrush current are converted into the excitation inrush current generated when the branch circuit completes the closing and opening operation. Therefore, the magnitude of the impulse current formed on the low-voltage winding side of the main transformer depends on the maximum allowable working condition of the power generation equipment side, and the rated current of the power generation equipment is far smaller than the rated current of the low-voltage winding side of the main transformer, so that the peak value of the excitation surge current is clamped.

The application provides a display panel and a display device; the display panel comprises a test terminal, a first electric connecting piece, a switching part and a second electric connecting piece; the first electric connecting piece comprises electrically connected first and second transmission parts; one end of the second transmission part away from the first transmission part is electrically connected with the test terminal; the switching part is electrically connected with one end of the first transmission part away from the second transmission part; the second electric connecting piece is electrically connected with one end of the switching part away from the first electric connecting piece; the second electric connecting piece and the first electric connecting piece are arranged in different layers; the surface impedance of the first transmission part is greater than that of the second transmission part, which is equivalent to increasing the impedance of the first transmission part, reducing the current when transmitted to the position of the via hole, and avoiding the technical problem of wire breakage caused by explosion of the wires in the switching area.

The application provides a thyristor-based multi-port hybrid DC circuit breaker and a control method, comprising: a plurality of main branches and a shared branch; all the main branches are connected to the shared branch; the shared branch comprises a first thyristor branch, a power supply side circuit breaker unit and a fault side circuit breaker unit, the thyristor branch is used for bearing fault current in the process of breaking of a fast mechanical switch in the main branch; the fault side circuit breaker unit is composed of a first capacitor, a first discharge resistor and a first lightning arrester element in parallel connection; the power supply side circuit breaker unit is composed of a second thyristor branch, a current limiting resistor, a second capacitor, a second discharge resistor and a second lightning arrester, wherein the second capacitor, the second discharge resistor and the second lightning arrester are connected in parallel to form a second branch, the thyristor branch and the current limiting resistor are connected in series to form a first branch, and the first branch is connected in series to the second branch.

The invention belongs to the field of short-circuit protection of micro-grids, and particularly relates to a short-circuit protection method and system of an alternating-current and direct-current hybrid micro-grid. The method comprises the following protection steps: when direct current in a direct current bus reaches a blocking action threshold value, on the basis of controlling a converter between a power supply corresponding to the direct current bus and the direct current bus to work in a voltage stabilization mode, blocking connection between the power supply corresponding to the direct current bus and the direct current bus; when the duration for blocking the connection is greater than a set time threshold value and the direct current in the direct current bus is smaller than a blocking action threshold value, the connection is switched on on the basis of controlling the converter to be maintained in a voltage stabilization mode; the blocking action threshold value is smaller than a current value used for triggering short-circuit protection of a device connected with a direct-current bus in the alternating-current and direct-current hybrid micro-grid and larger than the upper limit of the normal current value range of the device in the alternating-current and direct-current hybrid micro-grid, the fault rate of the alternating-current and direct-current hybrid micro-grid system can be effectively reduced, and then the operation reliability of the system is improved.

The invention relates to an LCC-MMC extra-high-voltage direct-current transmission line fault restarting method and an extra-high-voltage direct-current transmission system, and belongs to the technical field of extra-high-voltage direct-current transmission. When a line fault is detected, the LCC converter station controls the fault current to a direct current reference value; the MMC converter station controls the sub-module voltage to a rated value, the outer loop control output is switched to the sub-module voltage controller output, the direct current bias part of the direct current voltage reference value is switched to the direct current controller output, and the direct current reference value is the direct current reference value; after the deionization time is over, the DC bias part of the MMC converter station rises to a reference value, and the constant current control is quitted at the same time; when the current converter port voltage is detected to be greater than the starting value, the sub-module voltage control is quitted, and the outer loop control output is switched to the direct current voltage controller output; and the LCC converter keeps a current control mode, and when the DC voltage is detected to be greater than a completion value, the LCC converter station switches the current reference value to a real-time current reference value, and the line fault restart is completed.