1504 results about "Dc current" patented technology

The present invention discloses a transformer fault diagnosis technology based on knowledge mapping, which relates to the field of fault diagnosis technology and includes the following steps: S1, obtaining transformer multimodal data and performing data preprocessing; S2, establishing a memory-enhanced early warning model to predict transformer operation data; S3, transformer fault diagnosis. The present invention comprehensively considers online monitoring data or offline test data such as transformer oil dissolved gas data, oil temperature, partial discharge signal, core or clamp grounding current, DC current, infrared spectrum, winding deformation curve, ambient temperature and humidity, etc., performs fault diagnosis on the predicted multimodal data, and predicts possible future transformer faults.

A system includes: an alternating current (AC) to direct current (DC) converter (AC-DC converter), the AC-DC converter connectable to a line voltage; and a DC to DC converter (DC-DC converter) connected to the AC-DC converter, the DC-DC converter including: a high voltage buck-boost converter having a secondary side connectable to a high voltage battery; a low voltage buck-boost converter having a secondary side connectable to a low voltage battery; and one or more transformers having a primary side connected to the AC-DC converter, a secondary side connected to a primary side of the high voltage buck-boost converter, and a tertiary side connected to a primary side of the low voltage buck-boost converter.

The invention provides a mutual inductor loop resistance dynamic compensation correction method and device, and relates to the technical field of circuit testing, and the method comprises the steps: constructing a structural feature tensor and an environmental interference tensor according to the structural parameter information and environmental parameters of a primary winding and a secondary winding; training a dynamic compensation model based on the structural feature tensor, the environmental interference tensor and historical loop resistance test data; injecting a set direct current into the primary winding, obtaining an initial voltage signal sequence at two ends of the primary winding, and constructing a test state tensor in combination with the current loop current and the real-time environment parameters; inputting the test state tensor into the dynamic compensation model, and outputting a non-target resistance compensation value at the current moment; and based on the non-target resistance compensation value, correcting an initial loop resistance value obtained by calculating the initial voltage signal sequence to obtain a compensation resistance value of the target mutual inductor loop. According to the invention, the accuracy of mutual inductance loop resistance testing can be improved.

A bidirectional on-board charger includes a direct current bus, two bus capacitors, a power factor correction circuit, and a controller. The power factor correction circuit includes: a first bridge arm; and three second bridge arms, separately connected in series between the positive electrode and the negative electrode of the direct current bus. The controller is configured to: control the first switch (K1) to be turned off, and control at least one of the second bridge arms to output a direct current to charge a power battery; or control the first switch (K1) to be turned on, and control a midpoint of at least one of the second bridge arms to output an alternating current to supply power to an alternating current load. A Vehicle power system and an electric vehicle are further disclosed. The charger reduces circuit costs.

The invention discloses a fault processing method for an offshore wind power direct current parallel sending-out system through a DRU-MMC. The fault processing method comprises the steps that direct current energy consumption devices are arranged at direct current outlets of respective land MMC converter stations of a DRU-HVDC system and an MMC-HVDC system; when the alternating current power grid at the receiving end has an alternating current fault, the direct current energy consumption device is controlled to adopt a direct current voltage suppression strategy; when the DRU-HVDC system and the MMC-HVDC system respectively have direct current faults, different locking and circuit breaker disconnection time sequence control strategies are adopted, and in the direct current fault ride-through period, a direct current suppression strategy and a direct current voltage suppression strategy are controlled to be adopted by a direct current energy consumption device of the DRU-HVDC system. Therefore, the fault ride-through capability of the DRU-MMC direct current parallel sending-out system of the offshore wind power can be effectively improved, and stable operation of the system is ensured.

The invention relates to the technical field of high-voltage direct-current transmission, and discloses a reactive power support control method and system for a CLCC converter under an alternating-current fault, in order to fully explore the power support potential of the CLCC, the method comprises the following steps: firstly, starting from the forced commutation process of the CLCC during the fault period, analyzing that the trigger angle and the power have the multi-quadrant regulation and control capability; secondly, a direct current operable range and a trigger angle regulation and control range are determined; a power operation domain in the range is established; then, determining a trigger angle compensation amount and a control mode by taking no influence on active power transmitted to a receiving end alternating current system as a target; according to the method provided by the invention, the direct-current voltage and the direct-current transmission power of the inverter side during the alternating-current fault period can be kept unchanged, the voltage drop of the converter bus during the alternating-current fault period can be reduced, and the quick and stable recovery of the alternating-current voltage is facilitated.

A multi-level direct current converter, a voltage control method for a flying capacitor, and a control apparatus are provided. The multi-level direct current converter includes a controller, a flying capacitor, two switching transistor groups, and an inductor. The method for controlling a flying capacitor includes: in response to that an absolute value of a difference between a sampling voltage and a reference voltage of the flying capacitor is greater than a first threshold, adjusting a duty cycle difference between first switching transistors in two switching transistor groups or a phase difference between carriers of first switching transistors in two switching transistor groups based on a magnitude of an inductor current. According to this application, a voltage of the flying capacitor can be controlled, to improve operation stability of the multi-level direct current converter.

The invention relates to a method for passive arc suppression in an electrical treatment of plants, comprising the step: (S400) Applying a pulse-width modulated direct electrical current (I) to the plants.

An electronic device includes a wireless charging receive coil configured to transduce, into an alternating current (AC) power signal, a magnetic field generated by a wireless charging transmit coil of an external device; an active rectifier configured to convert the AC signal received at an AC side of the active rectifier into a direct current (DC) power signal output at a DC side of the active rectifier, the active rectifier comprising a plurality of switches; a first modulation capacitor connected to an upper rail of the AC side; a second modulation capacitor connected to a lower rail of the AC side; and a controller configured to adjust an impedance of the computing device to communicate with the external device by at least controlling the plurality of switches to cause the first modulation capacitor and the second modulation capacitor to charge during separate time periods.

The invention discloses an alternating-current and direct-current fault protection method of a hybrid commutation converter valve and related equipment thereof, and relates to the technical field of high-voltage direct-current power transmission. The method comprises the steps of obtaining an AC voltage of an AC side, a target trigger angle of a hybrid commutation converter valve and a DC current of a DC side, and determining an extinction angle margin risk factor and a volt-second area margin risk factor according to at least one of the above, the extinction angle margin risk factor being used for representing a commutation success margin, and the volt-second area margin risk factor being used for representing a target trigger angle of the hybrid commutation converter valve; the volt-second area margin risk factor is used for representing the commutation driving capability; determining a commutation failure risk index based on the extinction angle margin risk factor, the volt-second area margin risk factor and the prediction confidence factor; and when the commutation failure risk index is abnormal, controlling and triggering the hybrid commutation converter valve to enter a corresponding commutation enhancement mode or an active turn-off mode based on the commutation failure risk index. According to the embodiment of the invention, active intervention can be carried out before the commutation failure is caused by the AC / DC fault, so that the commutation failure can be fully resisted.

The invention discloses a method and a device for tracing a commutation failure fault of a high-voltage direct-current power transmission system, and the method comprises the steps: taking three electrical quantity signals, namely an alternating-current voltage, a direct-current current and a direct-current voltage, of an inversion side of the high-voltage direct-current power transmission system as source data when the commutation failure occurs; extracting an optimal fault feature of the source data by adopting a fault feature extraction model and a feature screening algorithm based on feature density; and finally, in combination with a commutation fault detection model and the optimal fault characteristics, obtaining a fault type causing commutation failure of the high-voltage direct-current power transmission system. Through the above design, fault tracing of the commutation failure can be realized, and in the tracing process, the optimal fault features are extracted by using the machine learning model and the feature screening algorithm based on the feature density, so that interference of human subjective experience on feature extraction can be reduced, and the effectiveness of fault tracing is improved; therefore, the method is very suitable for large-scale application and popularization.

A marine AC generator system includes a marine generator driven by an internal combustion engine and configured to generate an AC current and a rectifier configured to rectify the AC current to provide a DC current. At least one battery is configured to receive and be charged by the DC current. A battery powered inverter is configured to be powered by the at least one battery and to generate a variable current output frequency such that an AC electrical power is provided to a load when the marine generator is not running.

An electrical system includes a battery, temperature sensor, and battery charging station connectable to the battery and to an alternating current (AC) power supply. The charging station includes connected battery charging and heating circuits. The charging circuit includes a first plurality of power switches configured to rectify an AC input voltage from the power supply into a direct current (DC) voltage for charging the battery during a battery charging mode. The heating circuit includes a voltage bus, transformer, series switch, and a second plurality of power switches downstream of the transformer. The heating circuit generates an AC battery current from the DC voltage and injects the same into the battery during a battery heating mode. An electronic controller controls the power switches and the series switch to perform the charging and heating modes, doing so via a corresponding method.

The invention relates to the technical field of electrical performance testing, in particular to a method and system for measuring loss of an inductance winding, and the method comprises the following steps: applying a direct current to a measured inductance winding, synchronously monitoring the temperature, and multiplying a pre-measured direct current resistance value by a direct current value to obtain a direct current loss power value. The direct current is applied to the inductance winding, the temperature is monitored synchronously, the direct-current loss power is obtained by combining the direct-current resistance value and the current value, the temperature curve in the initial stage is extracted, the temperature rise rate is calculated, and therefore the winding heat capacity parameter is obtained, loss measurement can be closely associated with thermal response, and the measurement accuracy is improved. Introduction of a heat capacity factor is added in loss calculation, dynamic characteristics of a winding material on a thermodynamic level can be reflected, instantaneous current with load step change is applied after an inductor is cooled, an instantaneous loss power curve is generated by collecting a voltage sequence and a current sequence at the same time, and loss calculation is not limited to average value or steady state measurement any more.

The invention belongs to the technical field of direct current monitoring, and discloses a TMR-based open-close type direct current leakage current detection device, which comprises a magnetic core, one or more pairs of TMR sensors, a secondary side feedback coil and a main control circuit, and is characterized in that the magnetic core is provided with air gaps which are oppositely arranged; the TMR sensors are symmetrically arranged in the air gap; the secondary side feedback coil is wound on the surface of the magnetic core and forms closed-loop control with the main control circuit; the main control circuit comprises an acquisition feedback circuit, a secondary side detection circuit and a main control chip, the acquisition feedback circuit acquires signals of the TMR sensor under the control of the main control chip, generates feedback current and inputs the feedback current to the secondary side feedback coil, and the secondary side detection circuit is connected between the secondary side feedback coil and the main control chip. And the main control chip collects the secondary side voltage of the secondary side detection circuit and calculates to obtain the direct current leakage current. According to the invention, direct current leakage current detection with high sensitivity, low drift and strong anti-interference capability is realized under the open-close structure, and the requirements of a modern electric power system on continuity, safety and maintainability are met.

The invention relates to an HVDC commutation failure risk prediction method considering an optimal CFPREV, belongs to the technical field of commutation failure defense of a high-voltage direct-current transmission system, and aims to predict the commutation failure risk of an LCC-HVDC system under the control of the optimal CFPREV and judge whether the system can suppress the commutation failure only by changing the size of a trigger angle after a fault occurs. And a support is provided for the investment of an off-station commutation failure defense device. In the implementation process, an inverter station trigger angle under the CFPREV limit effect is calculated through real-time measurement data in the operation process of the high-voltage direct-current power transmission system, then the commutation failure risk under the optimal CFPREV control is predicted based on the commutation area theory, and the change of direct current under the CFPREV effect is considered in the calculation process, so that the prediction accuracy is improved. And the reliability of prediction results is ensured.

The invention discloses an adjustable oil damping electromagnetic release applied to a circuit breaker, and belongs to the technical field of release. Comprising an oil cup, an oil cup iron core capable of moving in the axial direction, a pole shoe arranged at the end of the oil cup and a first coil wound around the outer wall of the oil cup, and when the first coil is powered on, first electromagnetic force driving the oil cup iron core to move towards the pole shoe is generated; and the intelligent control module is arranged at the end part of the oil cup and is used for outputting controllable direct current to generate second electromagnetic force in the same direction or opposite direction as the first electromagnetic force, and the release has a rated current adjusting function and an overload protection adjusting function by adjusting the magnitude and the direction of the second electromagnetic force. The controllable second electromagnetic force is introduced into a traditional oil damping electromagnetic release, the rated current specification can be adjusted, the release action time can be adjusted, the advantage that the temperature stability of the oil damping release is good is reserved, and meanwhile the defect that the protection characteristic of the oil damping release cannot be adjusted is overcome.

Methods and systems of powering a radio that can be mounted on a tower of a wireless communication system are provided in which a direct current (“DC”) voltage is provided to the radio over a power cable from a power supply configured to change the direct current (DC) output from the power supply based on a measured current level. The power supply is configured to change the DC voltage from a first voltage level to a second voltage level in response to the measured current being greater than or equal to a first threshold value.

A device includes a plurality of digital-to-analog converters (DACs), a multiplexer, a plurality of electrodes including a first electrode, and a plurality of direct current (DC) offset circuits including a first DC offset circuit. At least one of the plurality of electrodes is located along a lane for movement of an ion. The multiplexer has multiple inputs coupled to the plurality of DACs and multiple outputs including a first output. The first output is configured to provide a first voltage. The first DC offset circuit is coupled between the first output and the first electrode. The first DC offset circuit is configured to add a first DC offset voltage to either the first voltage or the first voltage amplified by a first gain. The first DC offset voltage is configurable.

The invention relates to a direct current fault ride-through method, a direct current fault ride-through device, direct current fault ride-through equipment and a medium. The method comprises the following steps: switching a control mode of network-forming type energy storage into an alternating-current voltage control mode or a direct-current control strategy, carrying out coordinated control on devices in a multi-terminal direct-current collecting and sending-out system, clearing fault current, and clearing the fault current by utilizing an active step-down control strategy or the direct-current control strategy at the same time. According to the method, measures such as additional direct current circuit breakers are not needed, control is flexible and easy to achieve, the multi-terminal direct current collecting and sending-out system after fault clearing is controlled to be recovered by judging the operation state of the multi-terminal direct current collecting and sending-out system, and safe and stable operation of the multi-terminal direct current collecting and sending-out system is facilitated.

The invention relates to an MMC-CLCC novel DC power transmission system coordination control method, and belongs to the technical field of hybrid DC power transmission. The method comprises the following steps: establishing an MMC-CLCC hybrid DC power transmission system topology architecture, determining an optimal proportion of full-bridge and half-bridge sub-modules according to requirements of system DC voltage and the like, and determining a control strategy during steady-state operation; analyzing the dynamic process of the system under the alternating current fault of the receiving end, and clarifying the power operation characteristics of the CLCC; designing a calculation process of direct current, active power and reactive power operation limits of the inverter station under multi-condition constraints, and constructing a safe operation domain of the inverter station; and proposing a CLCC turn-off angle adjustment strategy based on reactive sensitivity constraint and an MMC coordination strategy based on maximum power transmission. The method can provide support for the receiving-end AC system during the fault period of the receiving-end power grid, guarantees the DC power transmission capability to the greatest extent, and is suitable for a large-scale new energy cross-regional power transmission scene.

A modular multilevel power converter includes: a capacitor voltage adjuster that calculates an active current component command to make an average voltage of capacitors match a command value; an active power detector that receives an AC current signal and an AC voltage signal and calculates an active power; an active power adjuster that calculates a DC current command value to make the active power match a command value; a first active power command suppressor that suppresses an absolute value of an active power command value; and a second active power command suppressor that adjusts an absolute value of an active power command value.

A high-power charging system and a method for charging electric vehicles EVs and / or plug-in hybrid vehicles PHEVs are described that allow for versatile charging one or more vehicles, subsequently or at the same time, with a simplified logistics, eventually in a modular way, and minimum set up work and while operating off-grid, i.e. without being connected to an AC electrical network. The system is an off-grid, integrated and prefabricated apparatus comprising plugs or connectors for vehicles, and means for connecting with sources of electricity from renewable energy, like photovoltaic panels and wind turbines organized in isles. The system also comprises a storage unit, provided with batteries and / or capacitors, a DC power unit supplying direct current DC to the plugs or connectors. The DC power unit is provided with one or more DC-DC converters that serve to adjust the voltage provided at said plugs or connectors. An internal distribution grid directly connects the sources of electricity from renewables to a charging controller that itself supplies the storage unit and the DC power unit. The storage unit instantly supplies the power necessary to meet the demand when the sources of electricity from renewables are insufficient. The system can support DC power charging levels two, three and four.

The invention discloses a miniaturized sensor for detecting alternating current and direct current, and belongs to the technical field of current sensors. The device comprises a conductor, the conductor is respectively connected with a zero-sequence coil and a magnetic-core-free Hall element, the zero-sequence coil is connected with an electric leakage detection module and an electric leakage simulation module, the magnetic-core-free Hall element is connected with a current detection module, and the elements and the modules are respectively and electrically connected with an intelligent control system. The problem that in the prior art, a mutual inductor can only measure alternating current and does not have the function of measuring direct current is solved, a magnetic field generated by current is detected through the magnetic-core-free Hall element and converted into an electric signal, the current magnitude is obtained through analysis of the current detection module, and over-current protection is achieved; residual current in the circuit is detected through the zero-sequence coil, and the electric leakage detection module is used for analysis and comparison to realize electric leakage protection; the whole electric leakage system is regularly tested through the simulation electric leakage module, so that the use performance and reliability of the miniaturized sensor are ensured.

The invention belongs to the technical field of microwave plasmas, and particularly relates to a magnetized atmospheric pressure pulse microwave plasma jet discharger. The discharger is reasonable in design, microwave energy is fed into the discharge chamber through the SMA interface, high electric field intensity is formed at the tip of the hollow needle electrode, and fed working gas is disrupted and discharged; a magnet exciting coil outside the quartz tube generates an axial magnetic field inside the quartz tube through direct current, electrons do spiral cycloid motion in an electromagnetic field, and electron cyclotron resonance can be achieved under the field. Through magnetic field constraint, high-energy electrons are constrained in a core area, a motion path is prolonged, effective collision times are increased, gas dissociation efficiency and ionization degree are improved, and collision loss of the electrons and a wall surface is reduced; the plasma jet performance is improved; the device works in an atmospheric pressure environment, does not need a vacuum system, reduces equipment cost and maintenance difficulty, reduces electrode sputtering and cavity corrosion, and prolongs the service life of core components.

The invention provides a leakage current testing method and system based on a low-frequency EIS and a transverse current pulse, and relates to the technical field of leakage current testing. The method comprises the following steps: firstly, determining use information and low-frequency EIS test parameters of a target battery to be tested, then testing the battery by using electrochemical working equipment according to the parameters, obtaining impedance data under different frequencies, and further obtaining first dynamic capacitance information. And controlling the power supply equipment to apply a preset transverse pulse current to the battery, determining a voltage variation cut-off condition, continuously monitoring the voltage variation, and recording the test time variation when the cut-off condition is reached. And finally, the leakage current value of the battery is determined by integrating the first dynamic capacitance information, the transverse current pulse current, the test time variation and the voltage variation. Compared with a traditional method, the leakage current value can be obtained only by applying the direct current once after the low-frequency EIS test without changing the magnitude and the duration time of the current for many times, the test process is simplified, the test efficiency is improved, and the leakage current value can be determined more accurately.

A ripple voltage detector circuit comprises a pulse generator, a direct current-to-direct current (DC-DC) converter coupled to the pulse generator, and a first control loop coupled to the pulse generator and the DC-DC converter. The first control loop is configured to measure an output voltage of the DC-DC converter, determine an output ripple voltage of the output voltage, determine a ripple coefficient based on the output ripple voltage, determine a reference peak inductor current based on the ripple coefficient, and determine a peak value of an inductor current during a switching cycle, and transition a switching state of the DC-DC converter based on the reference peak inductor current and the peak value of the inductor current.

A system powers a resistive load with switched direct current (DC) power. The high-speed switching of the resistive load heats up the resistive load with a pseudo-DC current. The resistive load can be a water heater element. The water heater can also have another heating element, which allows the pseudo-DC signal to pre-heat the water heater with local solar power, reducing the need for outside energy to power the other heating element.

The present invention discloses a method for self-clearing DC faults in a new energy island power grid transmission system. The sending end adopts a constant AC voltage and frequency control strategy, and there is only one receiving end that adopts a constant DC voltage control strategy, while the remaining receiving ends adopt a constant active power control strategy. At the same time, each pole of the flexible DC converter station at the sending end real-time detects the DC current flowing out of this pole, and each pole of the flexible DC converter station at the receiving end real-time detects the DC current flowing into this pole. After detecting the occurrence of a DC fault, the DC fault is automatically cleared according to their respective control strategies, and the energy balance of the sending end island is achieved in cooperation with the AC energy consumption at the sending end. It solves the technical problems of coordinated control between flexible DC and new energy, power surplus, and self-clearing of DC faults on the DC side, and improves the power regulation ability and system stability of the new energy island power grid transmission system.

The invention discloses a composite voltage generation device and a cable insulation performance evaluation system and method, and relates to the technical field of high-voltage insulation testing. The composite voltage generating device comprises a synchronous controller, a direct current source, an impact source, an IGBT active protection unit and a magnetic isolation coupler, and by means of the excellent characteristics of the IGBT and the magnetic isolation coupler, the superposition time sequence accuracy of direct current and impact voltage is improved, and waveform distortion is reduced. The IGBT active protection unit comprises a first IGBT and a second IGBT, and direct-current voltage polarity switching can be realized through selective conduction of the IGBTs; the RC circuit is connected in parallel between the collector electrode of the first IGBT and the emitter electrode of the second IGBT, reverse current flowing back to the direct current source direction can be discharged through the RC circuit, the risk of energy flowing back is reduced, meanwhile, the magnetic isolation coupler can completely block direct current, and an impact source is protected against the influence of direct current voltage; according to the invention, the authenticity and reliability of cable insulation performance evaluation can be effectively improved.