188 results about "Dc transformers" patented technology

The invention relates to the technical field of direct-current transformers, in particular to a direct-current transformer for a power distribution network, which comprises an iron core, a coil and insulating oil, an insulating assembly is arranged between the coil and the iron core, and the insulating assembly comprises an insulating paperboard, an insulating cushion block, an insulating contour semi-ring and a semi-ring groove, the insulating paper board is of a structure with a round inner wall and an octagonal outer wall. Through the unique design of the insulating paperboards, the insulating partition strips and the insulating partition blocks, the longitudinal oil ducts and the transverse oil ducts are effectively reserved, the oil flow path of the transformer is optimized, the cooling efficiency is improved, and stable operation of the transformer is ensured; through the bisection splicing structure of the insulating cardboard and the overturning action of the insulating parting strip, the quick clamping assembly of the insulating cardboard and the iron core is realized, the time for adapting the winding on site is saved, the tightness and uniformity of the winding are improved, and the reliability and safety of the transformer are enhanced.

The invention discloses a design method and system for a frequency conversion range of a CLLC direct-current transformer based on a neural network, and the method comprises the steps: carrying out the sampling in a preset variable range, and constructing a sampling database covering all working conditions; performing simulation verification on the sampled data to generate a physical constraint data set containing forward and reverse gains; inputting the processed simulation data into a neural network model for training, and establishing a precise mapping relation between parameter variables and electrical performance; and finally, optimizing model output by integrating an optimization algorithm (such as gradient descent and genetic algorithm), and realizing global optimal solution of resonant cavity parameters under the rigid constraints that the gain matching degree error is less than 2.1% and the frequency fluctuates. According to the method, a simulation verification-model training-parameter optimization closed-loop system is innovatively constructed, through a sampling mechanism and a cross-platform data interface, the three-day optimization period needed by traditional manual trial and error is compressed, and the design is more convenient and reasonable.

The invention belongs to the technical field of power distribution, and discloses a direct current transformer soft switch and a control method.The direct current transformer soft switch comprises a medium-voltage direct current bus and low-voltage direct current buses, the medium-voltage direct current bus is electrically connected with a modular multi-level multi-port direct current converter, and the modular multi-level multi-port direct current converter is electrically connected with a plurality of low-voltage direct current converters; the plurality of low-voltage direct-current converters are electrically connected with a low-voltage direct-current bus and are used for realizing bidirectional power transmission from medium-voltage direct current to low-voltage direct current; according to the method, the medium-voltage side inductance value is reduced, the medium-voltage side current ripple is enabled to pass zero, the M3DC operates in an approximate critical conduction mode, a constant valley current control strategy is adopted, the minimum value of the medium-voltage side inductance current is controlled to be constant under different working conditions, and then zero-voltage switching-on of a switching device in a wide operation range and zero-current switching-off of an anti-parallel diode are achieved.

The invention, which relates to the technical field of direct-current power transmission, discloses a co-offshore medium-high-frequency alternating-current offshore wind power full-direct-current collection system comprising: an offshore wind turbine module, which is used for obtaining offshore medium-voltage direct-current electric energy; the multi-port direct-current voltage transformation module is used for converting the offshore medium-voltage direct-current electric energy into offshore high-voltage direct-current electric energy; the direct-current submarine cable module is used for gathering the offshore high-voltage direct-current electric energy, acquiring the gathered offshore high-voltage direct-current electric energy and transmitting the gathered offshore high-voltage direct-current electric energy to the shore converter station module; the shore converter station module is used for acquiring shore high-voltage alternating-current electric energy according to the collected offshore high-voltage direct-current electric energy; the onshore alternating current module is used for receiving the onshore high-voltage alternating current electric energy and achieving full-direct-current collection of offshore wind power. By improving the medium voltage-high voltage direct current transformer topological structure and the control method, efficient and economical electric energy transmission is realized, the construction economy and the engineering application value of an open-sea wind power collection system are improved, and the average price and low price requirements of marketization development are met.

The invention discloses a direct-current transformer control method, which relates to the technical field of power electronic control and comprises the following steps of: acquiring operating parameters of a direct-current transformer in real time; the operation parameters at least comprise input side voltage, output side voltage and load current; inputting the operation parameters into a model prediction controller; in the model prediction controller, on the basis of the operation parameters and a preset system model, calculating to obtain a switching device control signal which enables a control target in a future preset time domain to be optimal; a switching device control signal is applied to a switching device of the DC transformer to regulate its output voltage or power. The method has the advantages that the dynamic response speed is increased, the system robustness is enhanced, and multi-target optimization control is realized.

The invention relates to a T-connection direct current transformer control method, device and system, a computer readable storage medium and a computer program product. The T-connection direct-current transformer comprises n-phase direct-current conversion modules, and n is larger than or equal to 4. Each phase of DC conversion module comprises a bridge arm formed by connecting a plurality of energy conversion sub-module cascade structures and an electric reactor in series, and two groups of switches, and a common connection end of the two groups of switches connected in series is connected with a first end of the bridge arm; the external connection end of the DC conversion module is used for connecting the high-voltage end, the low-voltage end and the grounding end, and comprises a first end, a second end, a common connection end and a second end of the bridge arm after the two groups of switches are connected in series. The method comprises the following steps: receiving a commutation instruction; in the commutation period, the conduction state of the switch is switched, so that at least an i-phase direct current conversion module is conducted with the low-voltage end at the same moment; 2 < = i < = n-2. By adopting the method, the magnitude of the current which needs to be tolerated by each device can be reduced, so that the T-connection type direct-current transformer meets the requirement of high-capacity application.

The invention provides a multi-bridge-arm integrated valve tower structure, a high-voltage direct-current transformer and a power system. The multi-bridge-arm integrated valve tower structure comprises a high-voltage bridge arm branch, a multiplexing bridge arm branch, a low-voltage bridge arm branch, a high-voltage port and a low-voltage port. One end of the high-voltage bridge arm branch, one end of the low-voltage bridge arm branch and one end of the multiplexing bridge arm branch are connected; the high-voltage bridge arm branch comprises a plurality of first half-bridge sub-modules which are connected in series; the multiplexing bridge arm branch comprises a plurality of second half-bridge sub-modules which are connected in series; the low-voltage bridge arm branch comprises a plurality of full-bridge sub-modules which are connected in series; the number of the first half-bridge sub-modules, the number of the second half-bridge sub-modules and the number of the full-bridge sub-modules are in direct proportion to the voltage withstand level of the valve tower structure. According to the structure, the high-voltage bridge arm branch, the multiplexing bridge arm branch and the low-voltage bridge arm branch are connected in a T-shaped mode, the number of the first half-bridge sub-modules, the number of the second half-bridge sub-modules and the number of the full-bridge sub-modules are determined according to the voltage withstand level needed by the valve tower, and the structure can be suitable for voltages of different levels.

The invention relates to the technical field of direct-current transformer high-voltage side fault identification and ride-through, and discloses a direct-current transformer high-voltage side fault identification and ride-through method and system, and the method comprises the steps: obtaining a first parameter of a high-voltage side of a target direct-current boosting transformer; acquiring a first fault feature according to the first parameter; the first fault feature is used for identifying a direct-current boosting transformer high-voltage side fault type; and presetting a fault ride-through strategy, and if the first fault feature of any fault type is obtained, starting the fault ride-through strategy. According to the invention, reliable identification and fault ride-through of the DC fault of the collection system can be realized by using the local measurement information of the DC transformer, the method is not influenced by photovoltaic output, the accuracy and efficiency of fault identification are improved, a new idea and method are provided for fault diagnosis of the DC boosting transformer, and the fault diagnosis efficiency of the DC boosting transformer is improved through a control and protection cooperation mode. The accuracy and efficiency of fault recognition are improved, and a new thought and method are provided for fault diagnosis of the direct-current boosting transformer.

The invention discloses an overvoltage suppression method of a resonant direct-current transformer and the resonant direct-current transformer, and relates to the technical field of power electronics. The overvoltage suppression method of the resonant direct-current transformer comprises the following steps: detecting a direct-current output voltage provided by a direct-current output port, and comparing the direct-current output voltage with an output voltage target value of the resonant direct-current transformer; and under the condition that the direct current output voltage is greater than the output voltage target value, dynamically adjusting the internal phase shift delay between the control signals of the first half bridge and the second half bridge so as to adjust the direct current output voltage to be less than or equal to the output voltage target value. According to the embodiment of the invention, the suppression cost of the light-load overvoltage of the resonant direct-current transformer can be reduced, and the reliability of the resonant direct-current transformer is improved.

A modular multi-level direct-current transformer topology applicable to a multi-voltage-class direct-current power grid, and a control method therefor. The topology comprises a bridge arm inductor, an upper bridge arm, a lower bridge arm and a filter inductor, wherein one end of the bridge arm inductor is connected to a positive electrode of a high-voltage side, and the other end thereof is connected to one end of the upper bridge arm; the other end of the upper bridge arm is connected to one end of the lower bridge arm and one end of the filter inductor; the other end of the lower bridge arm is separately connected to a negative electrode of the high-voltage side and a negative electrode of a low-voltage side; the other end of the filter inductor is connected to a positive electrode of the low-voltage side; and the upper bridge arm and the lower bridge arm each comprise a sub-module string, the sub-module string comprising several sub-modules, which are sequentially connected in series, and the upper bridge arm and the lower bridge arm regulate respective bridge arm voltages by means of controlling the number of inserted sub-modules, so as to realize direct-current voltage conversion between different voltage classes. In the present application, the use of upper and lower sets of chained sub-modules reduces the use of complex assemblies, thereby reducing the cost and the control difficulty, and also improving the safety, reliability and efficiency of a system.

The invention relates to a charging system and a control method thereof. The charging system comprises a DC source; the direct-current bus is used for transmitting direct current obtained by converting electric energy of the alternating-current power grid or transmitting direct current output by the direct-current source; the charging host is used for outputting charging current to external equipment; the direct-current transformer is used for transforming the direct current transmitted by the direct-current bus and / or the direct current output by the direct-current source; the switching device has a first switching state and a second switching state; in the first switching state, the direct current source is electrically connected with the direct current bus through the switching device so as to realize electric energy transmission between the direct current bus and the direct current source; and in the second switching state, the direct current source is electrically connected with the charging host through the switching device so as to realize electric energy transmission between the direct current source and the charging host. According to the charging system and the control method thereof, electric energy transmission between the direct-current bus and the direct-current source or between the direct-current source and the charging host can be realized through the switching device, so that the energy conversion efficiency is improved.

The invention relates to a fault ride-through method of a direct current transformer and a fault ride-through system of the direct current transformer. Working modes of low-voltage bridge arm direct-current voltage component adjustment, low-voltage port direct-current voltage control and high-voltage bridge arm alternating-current voltage control are switched, and direct current of a low-voltage port is adjusted through a first fault ride-through mode, a constant direct-current power mode and a bridge arm energy balance control mode; during the fault ride-through period, the low-voltage port is controlled to output negative voltage, current opposite to fault current is generated, the direct-current transformer quickly blocks the fault current, voltage balance of the bridge arm sub-module is maintained during the fault period, and stable fault ride-through is achieved.

The present application relates to the technical field of anti-DC current transformer, and discloses an anti-DC current transformer and method based on temperature compensation, which comprises a shell, an iron core is installed on the inner side of the shell, and a transformer coil is wound on the outer side of the iron core, and further comprises a negative temperature resistance compensation system connected in series with the transformer coil, the negative temperature resistance compensation system comprises a NTC negative temperature thermistor R1 and a parallel resistance system composed of a common resistance R3 and a common resistance R2 connected in parallel, and a parallel loop connected in series with the transformer coil, and the equivalent resistance value of the negative temperature resistance compensation system decreases with the increase of ambient temperature.The present application solves the problem of large phase difference / bias difference variation of traditional single-iron-core anti-DC transformer caused by changes in working environment temperature, reduces the phase difference variation caused by temperature from about 15% of the traditional value to 1-2%, and reduces the bias difference variation to within 0.1%, greatly reducing the temperature drift error and improving the transformer precision.

The present disclosure relates to a kind of direct current transformer, direct current transformer includes: transformer circuit, inverter circuit, rectifier circuit and resonance circuit;The direct current side of inverter circuit is connected with direct current input port, the alternating current side of inverter circuit is connected with the primary side of transformer circuit;The alternating current side of rectifier circuit is connected with the secondary side of transformer circuit, the direct current side of rectifier circuit is connected with direct current output port;Resonance circuit includes multiple resonance modules, the alternating current side of inverter circuit is connected with the alternating current side of rectifier circuit through multiple resonance modules and transformer circuit;Resonance module includes first capacitor, resonance module is used to control the input or cut-out of first capacitor.The present disclosure can simulate the voltage outputted when direct current transformer adopts different capacitance resonant capacitor, so as to ensure that direct current transformer does not need to set resonant capacitor, can satisfy the realization condition of resonant soft switching in different working condition scene, and then make the switching device in inverter circuit and rectifier circuit can realize soft switching.

The present invention discloses a DC transformer control system and control method. The DC transformer control system includes: a central controller and several module controllers connected by optical fibers; the module controllers correspond one-to-one with the power modules; the central controller obtains the operating data of the several power modules and obtains the corresponding modulation waves of the power modules; the central controller sends control instructions to the several module controllers according to a preset period, the control instructions including the modulation wave, the power module number, and the power module status information; the module controllers obtain a triangular carrier based on the power module number and the power module status information, and compare and calculate the triangular carrier with the modulation wave to obtain the control command of the power module. By adopting a two-layer controller architecture, the communication frequency is greatly reduced while ensuring control accuracy, reducing the computing power requirements of the main controller and the workload of the DC transformer main controller, thereby improving the operating efficiency of the DC transformer main controller.

The invention discloses a flexible direct-current transformer valve side partition plate system supporting strip fixing structure, and relates to the technical field of flexible direct-current transformer equipment, the flexible direct-current transformer valve side partition plate system supporting strip fixing structure comprises a partition plate system main body, the partition plate system main body is arranged in an ascending flanged base, and the partition plate system main body comprises an abutting part; the fixing assembly comprises a supporting strip and a locking assembly, the supporting strip is arranged between the partition plate system body and the ascending flanged base, the supporting strip is fixedly connected with the ascending flanged base through the locking assembly, the supporting strip comprises a wedge part, and the wedge part is matched with the abutting part in a friction abutting mode; according to the flexible direct current transformer valve side partition plate system supporting strip fixing structure, the supporting strip is arranged between the partition plate system body and the ascending flanged base, and the wedge part of the supporting strip abuts against the abutting part of the partition plate system body, so that tight supporting installation of the partition plate system body relative to the ascending flanged base is achieved, and the vibration influence generated in the transportation process is overcome.

The invention discloses a trapezoidal wave control method of a double-active-bridge direct-current transformer and related equipment, and relates to the technical field of direct-current transformers. In the double-active-bridge direct-current transformer, the first side of a first active bridge is electrically connected with a first direct-current port, the first end of the second side of the first active bridge is electrically connected with the first end of an auxiliary inductor, and the second end of the auxiliary inductor is electrically connected with the first end of a primary winding of an isolation transformer. The second side of the first active bridge is electrically connected with the second end of the primary winding of the isolation transformer; a secondary winding of the isolation transformer is electrically connected with a first side of a second active bridge, and a second side of the second active bridge is electrically connected with a second direct current port; the method comprises the following steps: controlling an inner phase shift angle of a first active bridge to be a first main phase shift angle, and controlling an inner phase shift angle of a second active bridge to be a second main phase shift angle; the difference value between the second main phase shift angle and the first main phase shift angle is a preset auxiliary phase shift angle. According to the embodiment of the invention, the operation reliability and efficiency of the double-active-bridge direct-current transformer can be improved.

The invention discloses a full-direct-current offshore wind power system zero-voltage ride-through method, equipment and a medium, and relates to the field of full-direct-current offshore wind power. The objective of the invention is to solve the problem that a receiving-end converter station cannot transmit power when a land AC power grid breaks down. When the high-voltage direct-current voltage of the offshore direct-current transformer exceeds the first preset threshold value, the medium-voltage direct-current voltage control of the offshore direct-current transformer is switched to the high-voltage direct-current voltage control, so that the offshore direct-current transformer absorbs power from a high-voltage direct-current link; when the medium-voltage direct-current voltage of the fan direct-current transformer exceeds a second preset threshold value, the fan direct-current transformer is switched from low-voltage direct-current voltage control to medium-voltage direct-current voltage control, so that the fan direct-current transformer can absorb power from the low-voltage direct-current voltage side through a fan grid-side direct-current transformer; and when the low-voltage direct-current voltage of the offshore direct-current transformer exceeds a third preset threshold value, the brake resistor is activated to dissipate surplus power until the low-voltage direct-current voltage is lower than a fourth preset threshold value.

The invention provides a multi-scale controllable asphalt pavement snow melting device and method based on a nanometer hot rod, and relates to the technical field of multi-scale controllable asphalt pavement snow melting of the nanometer hot rod, the multi-scale controllable asphalt pavement snow melting device comprises a roadbed, an asphalt concrete pavement, a computer module and a mounting device, the asphalt concrete pavement is located on the upper surface of the roadbed, and the computer module is located on the lower surface of the roadbed; a storage battery module is arranged on one side of the computer module, a wind power generation module and a photovoltaic power generation module are arranged on one side of the storage battery module, a direct-current transformer module is installed on one side of the computer module, and a meteorological data acquisition module is installed on one side of the direct-current transformer module. A wire is arranged on one side of the direct-current transformer module, and a snow melting and deicing device is arranged on the side, close to the roadbed, of the asphalt concrete pavement. The problem that in the prior art, under the extremely low temperature condition, the snow melting efficiency and the system reliability cannot meet the road safety requirement easily is solved.

The utility model relates to an off-grid inverter, which belongs to the technical field of inversion devices and comprises a casing and a main board arranged on the bottom wall of the casing, the main board is sequentially provided with a PV module, an inversion module, a DC-DC module and a battery module along the transverse direction, the front side of the PV module is provided with an AC module, the main board is provided with a copper bar jumper wire and a copper sheet, and the DC-DC module is connected with the battery module. The mainboard is connected with the PV module and the AC module through copper bar jumper wires, and the mainboard is connected with the battery module through a copper sheet. Wherein the PV module is a photovoltaic input module, the DC-DC module is a DC transformation module, and the AC module is an AC output module. According to the utility model, the PV module, the inversion module, the DC-DC module and the battery module are sequentially arranged along the transverse direction of the mainboard, the mainboard is connected with the PV module and the AC module through the copper bar jumper wire and is connected with the battery module through the copper sheet, and the inverter adopts a wireless design, has the advantages of compact structure, simplicity, order and convenience in wiring, and can improve the production efficiency.

The utility model discloses a compact direct-current transformer container, which belongs to the technical field of direct-current transformers and is characterized in that a low-voltage cabinet is arranged on the left side in the container, a high-voltage cabinet is arranged on the right side in the container, a direct-current transformer valve group I is arranged on one side close to the low-voltage cabinet in the container, and a direct-current transformer valve group III is arranged on one side close to the high-voltage cabinet in the container; a direct-current transformer valve group II is arranged between the direct-current transformer valve group I and the direct-current transformer valve group III; a first cabinet door is arranged at the left end of the outer surface of one side of the container, a third cabinet door is arranged at the right end of the outer surface of one side of the container, the first cabinet door corresponds to a low-voltage cabinet in the container, the third cabinet door corresponds to a high-voltage cabinet in the container, and a plurality of second cabinet doors are arranged between the first cabinet door and the third cabinet door at intervals and correspond to direct-current transformer valve groups respectively. According to the utility model, the cabinet doors correspond to the positions of the devices, the devices are convenient to disassemble and assemble, the devices are convenient to maintain by personnel, the high-voltage cabinet and the direct-current transformer valve group are arranged in the container to realize integral assembly and disassembly, and the occupied space is reduced.

The invention discloses a direct current transformer soft start method and related equipment, and relates to the technical field of direct current transformers. The direct-current transformer comprises a full-bridge inverter circuit composed of a first half-bridge and a second half-bridge. The soft start method of the direct-current transformer comprises the following steps: in a soft start stage of the direct-current transformer, in response to a full-bridge inverter circuit in a target switching period, controlling a sign symbol of an inner phase shift angle between a first half bridge and a second half bridge as a first symbol; in response to the full-bridge inverter circuit being in the next switching period of the target switching period, adjusting the sign symbol of the internal phase shift angle between the first half-bridge and the second half-bridge as a second symbol; wherein the positive and negative of the first symbol and the positive and negative of the second symbol are opposite, and the target switching period is any switching period in the soft start stage. According to the embodiment of the invention, the turn-off stress of the device can be effectively balanced, and the improvement of the reliability of the device of the direct-current transformer and the improvement of the starting speed of the system are facilitated.

The invention discloses an electrical circuit hidden danger inspection device, and relates to the technical field of circuit hidden danger inspection. Comprising a bottom plate, two supporting plates are symmetrically and fixedly connected to the side wall of the bottom end of the bottom plate, two first grooves are symmetrically formed in the side wall of the top end of the bottom plate, and first sliding rails are fixedly connected to the inner walls of the first grooves. According to the invention, when line hidden troubles of the direct current transformer need to be detected, the position and angle of the insertion block can be adjusted according to the position and angle of the conducting strip in the insertion port of the direct current transformer, so that the insertion block can be in insertion connection with the conducting strips at different positions; meanwhile, the position and the angle of the cleaning shell can be changed according to the position and the angle of the conducting strip, so that the cleaning shell can cover the corresponding conducting strip, then dust on the surface of the conducting strip is cleaned through the cleaning brush, and it is avoided that dust on the surface of the conducting strip influences accurate judgment of parameters such as the transformation ratio and the voltage regulation rate of the transformer.

This invention discloses an active damping control structure and method for a DC transformer and a DC distribution network, belonging to the field of DC transformer control technology. In the control structure: a summation module sums the input voltages of M sub-modules to obtain voltage v. bus The filter module filters out voltage v bus The AC component in the equation yields the DC voltage v. DC The averaging module calculates the voltage v respectively. bus and DC voltage v DC Divide by M to obtain the reference value v avg and reference value v DCref The input voltage equalization controller realizes the input voltage v of each submodule j. in_j Compared with reference value v avg Zero steady-state error regulation, output power p ivs_j The input voltage regulator controller implements the input voltage v of each submodule j. in_j Compared with reference value v DCref Zero steady-state error regulation, output power p ivr_j The output voltage regulator achieves the output voltage V. o Compared with reference value V oref Zero steady-state error regulation, output power regulation p ove The actual power calculator calculates the actual power of each submodule j using the instruction p. pu_j The control structure and method of this invention ensure stable operation of the transformer.

This invention discloses an onshore wind power transmission system to solve the problems of harmonic resonance and reactive power transmission in existing related technologies. The onshore wind power transmission system includes a wind power sending-end unit and a wind power receiving-end unit. The sending-end unit includes a DC transformer and two or more wind turbines. Each wind turbine has an internal turbine-side converter and a corresponding low-voltage circuit breaker. Each pole of the DC transformer has a DC circuit breaker installed. For each wind turbine, the generated electricity is rectified into a first DC current by the turbine-side converter and then connected in parallel to the DC transformer via the low-voltage circuit breaker to be stepped up to a second DC current. This second DC current is then sent to the wind power receiving-end unit via the bipolar DC circuit breaker of the DC transformer. The receiving-end unit includes a receiving-end converter station, a connecting transformer, and a starting circuit. After the second DC current is rectified at the receiving-end converter station, it is stepped up again by the connecting transformer and then connected to the AC power grid via the starting circuit.

The present application relates to the technical field of butt welding machine, especially to a non-light direct current butt welding machine, comprising: a welding mechanism, comprising a first butt welding assembly, a second butt welding assembly and a direct current transformer; a linkage mechanism, comprising a left moving plate, a right moving plate, a left eccentric shaft and a right eccentric shaft; a driving mechanism, comprising a plurality of servo motors and a top forging oil cylinder; a detection mechanism; a control mechanism, used to weld workpieces by controlling the current value of direct current during welding, used to press workpieces by controlling the rotation angle of the eccentric shaft, used to top forge workpieces by controlling the relative movement of the left moving plate approaching the right moving plate driven by the top forging oil cylinder, used to adjust the height of the left moving plate and the right moving plate respectively by controlling the servo motor to drive the linkage mechanism, and used to adjust the holding time of the top forging pressure according to the total energy of the welded workpiece, and used to correct the top forging displacement target value according to the change rate of the top forging pressure. The present application realizes the improvement of welding efficiency and welding precision.

The application relates to a direct-current transformer valve hall arrangement structure which adopts the technical scheme that: a direct-current transformer valve hall arrangement structure is characterized in that the valve hall is internally arranged with positive and negative electrode valves of a direct-current transformer; one side of the valve hall is a low-voltage direct-current incoming line end; the other side is a high-voltage direct-current incoming line end and a common incoming line end; and each incoming line end is connected with an external device through a wall or floor sleeve at different positions of the valve hall. The positive and negative electrode valves of the direct-current transformer are arranged in the valve hall, the arrangement is reasonable and compact, the space utilization rate is high, and the valve hall space is saved.

The invention relates to the technical field of direct-current converter transformers, in particular to an oil-immersed direct-current transformer which comprises an oil-immersed transformer body, a cooling oil filter fixedly mounted on the oil-immersed transformer body, a mounting base fixedly connected to the oil-immersed transformer body and a lifting frame. A temperature sensor is fixedly installed on the outer wall of the oil-immersed transformer body, a conveying pump is fixedly installed on the outer wall of the oil-immersed transformer body, and the output end of the conveying pump communicates with a cooling oil filter. When the lifting frame drives the insulating cleaning brush to move upwards and reset, the insulating cleaning brush is not in contact with the surface of the oil-immersed transformer main body; and dust remaining on the surface of the oil-immersed transformer main body is prevented from being pushed to the top of the transformer when the insulating cleaning brush moves upwards.

The invention provides a load flow calculation method, system and device and a medium, and the method comprises the steps: obtaining a topology network state and operation parameters of a flexible DC power transmission system; by means of the Newton-Raphson method, the topology network state and the operation parameters are substituted into an alternating-current and direct-current power grid load flow calculation equation set for calculation, and node power and line power of the flexible direct-current power transmission system are obtained; the alternating-current and direct-current power grid load flow calculation equation set comprises a load flow calculation model of a direct-current power flow controller in the flexible direct-current power transmission system and a load flow calculation model of a direct-current transformer. According to the method, the calculation speed and the calculation efficiency of load flow calculation can be ensured while the load flow calculation precision is ensured.

The invention discloses a control method, system and device for misoperation locking of a high-voltage direct-current power transmission system, and relates to the technical field of high-voltage direct-current power transmission, and the control method comprises the steps: reading a direct-current voltage value, measured by a control protection device, of the high-voltage direct-current power transmission system; if the direct-current voltage value is smaller than the starting voltage value of the low-voltage current-limiting protection, whether starting of the low-voltage current-limiting protection is caused by abnormal measurement after short-time voltage loss of a low-voltage arm of the direct-current transformer is judged; if the judgment result is that the starting of the low-voltage current-limiting protection is caused by the abnormal measurement after the short-time voltage loss of the low-voltage arm of the direct-current transformer, executing the regulation control of the low-voltage current-limiting protection; or if the judgment result is that the starting of the low-voltage current-limiting protection is not caused by the abnormal measurement after the short-time voltage loss of the low-voltage arm of the direct-current transformer, shielding the regulation control of the low-voltage current-limiting protection. The problem that short-time voltage loss of a low-voltage arm of a direct-current voltage divider of the high-voltage direct-current power transmission system is caused by lightning stroke disturbance, and then direct-current misoperation locking of the high-voltage direct-current power transmission system is caused is solved.