3475 results about "Alternating current" patented technology

The invention relates to the technical field of hybrid inverters, and discloses a hybrid inverter supporting reactive compensation and a control method thereof, and the hybrid inverter comprises a DC input unit, a three-phase full-bridge inversion unit, a grid-connected switching unit, a signal acquisition unit and a digital control unit. The direct current input unit comprises a photovoltaic interface, a battery interface and a direct current bus and is used for converging photovoltaic and energy storage electric energy; the three-phase full-bridge inversion unit is composed of a power device and an LCL filter and converts direct current into alternating current. The grid-connected switching unit comprises a static switch and an isolation transformer and is used for controlling power grid connection; the signal acquisition unit detects voltage and current signals; and the digital control unit judges a grid-connected mode or an off-grid mode according to the signal, calculates a reactive current reference value and generates a PWM (Pulse Width Modulation) control signal so as to realize reactive compensation control in the grid-connected mode and the off-grid mode. According to the invention, reactive power compensation capability is provided in both grid-connected and off-grid operation modes, and stable operation of the inverter in various working conditions is ensured.

The invention discloses a high-voltage circuit for an electric flame stove. The high-voltage circuit comprises a PFC circuit, a high-frequency conversion circuit, a boosting transformer, an energy coupling circuit and a voltage doubling circuit which are electrically connected in sequence. According to the EMI filter circuit, common-mode interference and differential-mode interference are filtered out, and pure alternating current input is provided for a back-end PFC circuit; two chips are adopted in the PFC circuit, so that the PFC circuit 300 finally realizes the consistency of the current waveform and the voltage phase; in the other embodiment of the invention, double chips are adopted, so that'fault linkage protection 'is realized; stable discharging of multiple groups of positive and negative electrodes is achieved through multiple groups of single energy coupling capacitors and independent voltage doubling rectifier bridges which are connected in parallel.

The invention relates to a simple and reliable touch control switch. The simple and reliable touch control switch consists of a 12-V direct-current power supply, a one-way silicon controlled rectifier 1 (SCR1) trigger circuit, a one-way silicon controlled rectifier 2 (SCR2) trigger circuit, a relay control circuit and a load RL circuit. A conventional mechanical self-locking rocker switch or a toggle switch has the defects that actions are mechanical, operating actions are different because of persons, a contact is easy to jitter, a contact is easy to ablate, abrade and the like. The touch control switch is realized by only using a small number of common components and two touch metal pieces, namely an on-load circuit is switched on by touching a touch electrode once, and an off-load circuit is switched off by touching the touch electrode once. The overall touch control switch is made of discrete components, and strong electricity can be effectively isolated from weak electricity through a relay, so that the power supply of a load can use alternating current and also can use direct current. Therefore, the touch control switch has a certain function in the field of household appliances, industrial automation, and optical, mechanical and electrical integration.

The invention provides a tumor electric field treatment system, an electrode slice temperature detection method and an electrode slice anomaly detection method, the system comprises an alternating current signal generator, an electrode slice and a controller, the electrode slice comprises a plurality of electrode units and a plurality of temperature detection units, the plurality of temperature detection units are divided into a plurality of row groups and a plurality of column groups, and the plurality of electrode units are connected with the controller. The grounding ends of the temperature detection units in each row group are jointly connected to the same grounding wire, and the signal ends of the temperature detection units in each column group are connected to the same dual-purpose signal wire after being in short circuit with the corresponding electrode units; when the dual-purpose signal line is connected to the temperature sampling point, the grounding wires are sequentially conducted, so that temperature detection signals detected by the temperature detection units are sampled based on the temperature sampling point; when the dual-purpose signal line is connected to the alternating power line, alternating electric signals are transmitted to the electrode units. Therefore, the temperature of the electrode plate can be detected by using fewer conductive traces, and whether the electrode plate is abnormal or not can be judged through temperature detection.

The invention relates to the technical field of charging pile management, in particular to a new energy charging pile management method and system. The method comprises the following steps: obtaining a charging log of a charging module through a control terminal of the new energy charging pile, and carrying out the abnormal analysis of the AC voltage fluctuation, and obtaining the AC voltage abnormal fluctuation data. On the basis, analyzing the thermal stability imbalance of the power device, and further quantifying the power conversion performance loss stage number; thirdly, giving an over-limit voltage stage risk level according to the power conversion performance loss level, and constructing a charging risk prediction model according to the risk level; and finally, the charging risk prediction model is sent to a control terminal for management and optimization of the new energy charging pile. According to the invention, the charging pile management technology is optimized, so that the charging pile management technology is more perfect.

The invention discloses an output voltage detection method and system based on an aviation power supply, and relates to the technical field of aviation power supply voltage detection. A differential voltage sensor is connected to the output end of an aviation power supply, a high-frequency suppression capacitor is connected in parallel, the sampling rate of 20-50 times of the working frequency is set according to the type of the power supply, and the signals are collected and converted into analog voltage signals; the analog signal is subjected to two-stage filtering, is amplified to 0-5V through an instrument amplifier, and is converted into a digital voltage sequence through a 16-bit ADC (Analog to Digital Converter); calculating AC power supply effective value, peak value and other parameters, DC power supply average value, ripple coefficient and other parameters; comparing the characteristic parameters with a preset threshold value, determining that the characteristic parameters exceed the threshold value and recording related information; and a detection result is transmitted to a monitoring terminal through an RS485, data is locally stored, and a switching value is output to an alarm device when the data is abnormal. The method adapts to aviation power supply load fluctuation and environment temperature change, detection precision is high, data transmission and storage are safe, abnormity is accurately identified and early warning is carried out in advance, and aviation power supply operation and maintenance reliability and efficiency are improved.

The invention relates to the field of power grid simulation, and particularly discloses a control method of an alternating-current power grid broadband oscillation simulation device based on a component physical model, which realizes broadband domain oscillation simulation of an alternating-current power grid based on the component physical model and a notch filter. Specifically, according to the control method of the alternating-current power grid broadband oscillation simulation device based on the element physical model, an adjustable element physical model type and a corresponding impedance parameter serve as input conditions, and a dynamic voltage compensation component excited by power grid impedance is calculated in combination with an adjustable notch filter; and a power grid simulation reference signal is constructed in real time through superposition of an original input reference voltage value and a dynamic voltage compensation component excited by power grid impedance, so that oscillation simulation in a wide frequency domain of the alternating-current power grid is realized.

In an example, an electrochemical monitoring system for determining one or more parameters of interest of an electrochemical cell can include measurement circuitry, which can be configured to obtain, for a plurality of specified alternating current (AC) frequencies: (1) a first AC voltage measurement across nodes which can be coupleable to the electrochemical cell, and (2) a second AC voltage measurement across a sensing impedance which can be elicited in response to the AC stimulus. The sensing impedance can be coupled in series with the electrochemical cell. The electrochemical monitoring system can also include a controller circuit, which can be configured to jointly estimate model parameters corresponding to an equivalent circuit model (ECM) of a combination of the electrochemical cell and the sensing impedance, such as using the first and second AC voltage measurements for the plurality of specified AC frequencies.

An electrophotographic member, comprising: a support member having a conductive outer surface; and a conductive layer disposed on an outer surface of the support member, wherein the conductive layer comprises a matrix comprising a first rubber, and a plurality of domains dispersed in the matrix, volume resistivity of the matrix is 1.00×1012 Ω·cm or less, the plurality of domains comprise at least one domain A, and the domain A satisfies specific conditions, in a case where impedance of the electrophotographic member is measured by applying specific AC voltage while changing frequency in a range of 1.0×10−2 to 1.0×107 Hz and the specific plotting is done, a slope at a specific frequency is −0.80 to −0.30, and the impedance in a specific frequency is 1.00×103 to 1.00×107Ω.

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 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 device for ascertaining a property of a fluid, having: an electric conductor assembly which is designed to be at least partly brought into contact with the fluid and which is designed as a voltage divider with two elements, wherein the first element is a first conductor which, at least in a current-conducting state, has a resistance value that differs from that of the second element; a measuring bridge with two voltage dividers connected in parallel, one of said voltage dividers being formed by the electric conductor assembly; an actuation unit for applying an AC voltage to the measuring bridge; a voltage detection unit for detecting a bridge voltage; and an analysis unit which is configured to ascertain a thermal conductivity as the property of the fluid by analyzing the bridge voltage using the 3-omega method.

The invention discloses a novel photovoltaic optimizer based on PLC communication, which comprises a hardware module, a control module, a communication module and a service module, and is characterized in that the hardware module is used for constructing a system material basis and realizing electric energy calling, signal coupling and equipment protection, and the control module is used for realizing intelligent power regulation and communication control; the power generation efficiency is improved and the communication stability is guaranteed through a multi-modal algorithm, and the communication module is used for constructing a power line carrier communication system. A special PLC framework for a direct-current low-voltage environment is adopted, a communication frequency band and an impedance matching scheme can be designed according to photovoltaic direct-current side characteristics, technical field differentiation is formed from alternating-current power grid PLC patents, through dual-mode MPPT dynamic switching, the limitation of a single algorithm in a dynamic environment can be broken through through combination of local gradient prediction and a distributed collaborative algorithm, and the real-time performance of a photovoltaic power grid is improved. In cooperation with a passive impedance compensation technology, adaptive adjustment can be performed through the magnetic ring filter and the capacitor array, an additional power supply module is not needed, and the hardware complexity is reduced.

The invention discloses a hybrid direct current transmission power coordination control device and a control method and equipment thereof, and relates to the technical field of offshore power generation, and the hybrid direct current transmission power coordination control device comprises a diode rectifier unit and a first modular multilevel converter which are connected with an offshore wind plant, the sending-end converter station is used for converting alternating current generated by an offshore wind plant into direct current and outputting the direct current; the second modularized multi-level current converter is connected with the diode rectifier unit and the land power grid and is used for restoring the direct current into the alternating current and transmitting the alternating current to the land power grid; and the control module is connected with the first modular multilevel converter and is used for controlling the DC voltage of the first modular multilevel converter based on the fluctuation power according to the transfer relation between the active power and the DC voltage of the sending end converter station, so that the higher requirement of the rated capacity of the MMC in the related technology is met, and the reliability of the MMC is improved. And the engineering construction cost is increased.

The invention relates to the technical field of power electronics, and discloses a dielectric barrier discharge high-voltage series resonance system and a control method thereof. The system comprises a high-voltage series resonance circuit, an upper computer and a hardware circuit. The upper computer is electrically connected with the hardware circuit, and the hardware circuit is electrically connected with the high-voltage series resonance circuit; wherein the high-voltage series resonance circuit comprises a PFC circuit, a Buck circuit, an LC series resonance circuit, a high-voltage pulse transformer and a dielectric barrier discharge load which are connected in sequence, the high-voltage series resonance circuit converts alternating current into high-frequency high-voltage pulse voltage and provides the high-frequency high-voltage pulse voltage for the dielectric barrier discharge load, and stable dielectric barrier discharge is generated; the upper computer is used for setting parameters, the hardware circuit controls the on-off state of the Buck circuit and the LC series resonance circuit according to the parameters set by the upper computer, accurate generation and control of high-voltage pulse voltage in the dielectric barrier discharge process are achieved, and the response speed and the control precision of the system are also improved.

A power conditioning subsystem (PCS) includes an inverter circuit configured to mutually covert direct current (DC) power of a storage battery and alternating current (AC) power, a command value acquiring portion configured to acquire a command value from a higher-level apparatus to charge or discharge the storage battery, a DC voltage acquiring portion configured to acquire a DC voltage on the storage battery side, and a limiter processing portion configured to perform a process of setting to limit each of an upper limit and a lower limit of the command value acquired by the command value acquiring portion on the basis of the DC voltage acquired by the DC voltage acquiring portion.

The invention discloses a control method for a photovoltaic hybrid inverter, and the method comprises the steps: controlling an inversion unit to apply an AC voltage test signal with a preset frequency and / or a preset voltage value to the output end of the inversion unit under a no-load condition, and maintaining a maximum power point tracking module to work, so as to provide electric energy for a DC bus; judging whether the photovoltaic hybrid inverter is in a weak light state or not based on the first voltage of the direct current bus and a preset voltage threshold value; when the photovoltaic hybrid inverter is in a weak light state, the alternating current side relay is kept disconnected; and after a preset delay time, applying the AC voltage test signal to the output end of the inversion unit again, and maintaining the maximum power point tracking module to work so as to re-judge whether the photovoltaic hybrid inverter is in the weak light state or not until the photovoltaic hybrid inverter is not in the weak light state. And issuing a pull-in instruction to the alternating current side relay to control the inverter unit to operate in a grid-connected manner. And the relay is prevented from being frequently triggered to be closed when the illumination is insufficient.

The utility model relates to a rear-phase-cut single-live-wire type wall light modulator, which comprises an MOS (Metal Oxide Semiconductor) tube switch loop unit, a singlechip control unit and a direct-current power supply unit, the MOS tube switch loop unit comprises a wiring terminal J2 connected with an MOS tube Q1, a grid electrode of the MOS tube Q1 is connected with four resistors in series in sequence and then is connected with an MOS tube Q2, a drain electrode of the MOS tube Q2 is connected with a diode D2, the diode D2 is connected with a diode D1, a fixed end contact of a single-pole double-throw switch is connected with the MOS tube Q2, and two movable end contacts of the single-pole double-throw switch are connected with the wiring terminal J1 and the wiring terminal J3 respectively; the direct-current power supply unit comprises an alternating-current voltage waveform acquisition circuit, a direct-current voltage drop circuit, an overcurrent protection circuit and a filtering voltage stabilizing circuit; according to the single-chip microcomputer control unit, a linear sliding potentiometer is connected with the PC2 end of a single-chip microcomputer after being connected with a resistor in series, the linear sliding potentiometer and a rotary potentiometer are sequentially connected between the output end of the direct-current power supply unit and the ground in series, a triode Q6 is connected with a triode Q5 and then connected with the collector electrode of a triode Q7, and the base electrode of the triode Q7 is connected with the PA6 end of the single-chip microcomputer after being connected with a resistor in series.

The utility model relates to the technical field of magnet power supplies, and discloses an external superconducting magnet power supply, which comprises a plurality of power supply modules connected in parallel, the input end of each power supply module is electrically connected with a power grid, the output end of each power supply module is electrically connected with an external superconducting magnet, and the plurality of power supply modules connected in parallel are used for jointly supplying power to the external superconducting magnet; wherein the power supply module comprises a switching power supply sub-module which is electrically connected with a power grid and is used for converting alternating current of a first voltage level input by the power grid into high-frequency alternating current of a third voltage level; and the linear adjusting tube is electrically connected with the switching power supply sub-module and the outer superconducting magnet, and is used for converting the direct current of the third voltage level into direct current of a fourth voltage level and inputting the direct current of the fourth voltage level into the outer superconducting magnet. According to the utility model, through the switching power supply sub-module and the linear adjusting tube, the power factor and the energy utilization rate can be improved, the harmonic wave is small, the power grid is not polluted, and the stability of the output voltage is ensured.

The invention provides a high-low voltage valve group heterogeneous flexible direct current power transmission system and a direct current fault clearing method, and belongs to the field of power transmission and distribution of electric power systems, and the system comprises an alternating current collection network which is used for collecting alternating current electric energy of a new energy base; each of the sending end converter station and the receiving end converter station comprises a negative-voltage type modular multilevel converter and a half-bridge type modular multilevel converter; the direct-current overhead line is electrically connected between the sending-end converter station and the receiving-end converter station, and direct-current quick switches are arranged on the two sides of the direct-current overhead line respectively; the sending end converter station adopts cooperative network construction control and is used for maintaining the voltage stability of the alternating current collection network; and the receiving end converter station adopts direct-current voltage control and is used for maintaining the voltage stability of the direct-current electric energy of the direct-current overhead line. According to the invention, large-scale long-distance new energy supply is realized, and the construction cost and the operation loss are reduced.

The invention discloses a three-phase uninterruptible power supply device and a control method thereof. The control method comprises the following steps: acquiring an input current of a three-phase alternating current power supply and a load voltage and a load current of an output end of an inverter circuit; carrying out harmonic separation on the collected input current, and determining a total harmonic distortion rate; when the total harmonic distortion rate is greater than a preset total harmonic distortion rate threshold value, generating a harmonic compensation signal; calculating load variation and voltage deviation based on load voltage and load current, dynamically adjusting proportional gain and integral time in real time, and generating a fundamental voltage control signal; superposing the fundamental wave voltage control signal and the harmonic compensation signal to generate a preliminary modulation wave; dynamically adjusting the dead zone time of the PWM wave, and combining the dead zone time with the preliminary modulation wave to generate the PWM wave; according to the control method, the three-phase alternating current is converted into the alternating current meeting the load requirement through the PWM waves, the response capacity to voltage sag, voltage fluctuation and harmonic disturbance is improved, and the output electric energy quality is improved.

A modular and scalable AC / DC substation transforms AC voltage to DC voltage for driving a high-voltage and high-current load, such as a heavy work machine. Sized to fit within a standard high-cube ISO shipping container, the substation includes a main transformer attached at a center of a rectangular base with a pair of controlled rectifiers positioned on the base downstream from the main transformer, aligned parallel to a lateral axis of the base, and substantially symmetrical to a longitudinal axis of the base. The arrangement of these components on the base, together with lowpass filters and switchgear, achieves high power density for the substation, provides balanced mass for stability during shipment and placement, and helps protect personnel from accidental electrical arcing.

The invention discloses a distributed light storage and charging integrated system, which comprises a photovoltaic power generation unit, an energy storage unit, a charging unit, a power grid interface unit, an energy management controller and a direct current bus, the photovoltaic power generation unit comprises a DC / DC converter, and the photovoltaic power generation unit is connected with the DC bus through the DC / DC converter; the energy storage unit comprises a lithium ion battery pack, a flywheel energy storage device, a bidirectional DC converter and a flywheel controller. The lithium ion battery pack and the flywheel energy storage device are connected to the DC bus through the bidirectional DC converter and the flywheel controller respectively. The charging unit comprises at least one direct-current quick charging pile, at least one alternating-current slow charging pile and a DC / AC inverter, the direct-current quick charging pile is directly connected with the direct-current bus, and the alternating-current slow charging pile is connected with the direct-current bus through the DC / AC inverter; the power grid interface unit comprises an AC / DC converter and is connected with the DC bus through the AC / DC converter. According to the invention, through collaborative design of a modular hardware architecture and an intelligent time-sharing strategy, comprehensive improvement of economy, reliability and functionality of the system is realized.

An onboard charging system for an electric vehicle includes a charging port configured to receive a single-phase AC power, a power outlet configured to provide the single-phase AC power to one or more external devices, a single-phase inverter connected to the power outlet and configured to provide power splitting functionality, a DC battery selectively coupled to the charging port, a bidirectional inverter configured to convert AC power to DC power and to convert DC power to AC power, the bidirectional inverter is selectively coupled to the battery, an electric motor coupled to the bidirectional inverter and selectively coupled to the charging port, a DC-AC converter selectively coupled to the electric motor and selectively coupled to the power outlet, and a DC-DC converter coupled to the DC-AC converter and selectively coupled to the battery.

The invention relates to the technical field of power system optimization dispatching, in particular to a frequency constraint unit commitment optimization method, device and equipment based on linear alternating current power flow and a medium. According to the method, second-order cone convex relaxation processing is conducted on a non-convex alternating current power flow equation, and a unit commitment model is constructed; frequency safety constraints are introduced into the unit commitment model, the frequency safety constraints comprise frequency safety margin constraints and system equivalent inertia constraints, and a frequency constraint unit commitment model is formed; a two-stage progressive optimization strategy is adopted for solving the frequency constraint unit combination model, in the first stage, the unit start-stop state and an initial power generation plan are determined through the unit combination model, in the second stage, the multi-period alternating current optimal power flow model is solved in the fixed start-stop state to correct the result, and a final power generation plan is obtained; according to the method, the solving efficiency and the frequency safety are both considered, and the safety and economy of power grid operation are remarkably improved.

The invention relates to a new energy scene collaborative energy compensation system based on multi-energy complementation and a control method. The system comprises a power supply input and conversion module, an energy storage system, a power distribution and energy distribution module, a charging and battery replacement facility and a control system. The power input and conversion module is connected to an alternating current bus through a box-type substation, a photovoltaic panel and a photovoltaic inverter; the energy storage system is connected with an AC-DC bus through a power conversion system and a DC conversion module by utilizing an energy storage battery pack and a mobile power transmission vehicle; the power distribution and energy distribution module transmits electric energy through an AC-DC bus. The charging and battery replacing facility takes power from the AC / DC bus; the control system collects data and dispatches energy through a communication protocol, and cooperates with the power electronic transformer and the virtual synchronous machine control module to realize power grid frequency compensation and voltage stability control. According to the invention, by integrating photovoltaic, energy storage and charging facilities and power grid interaction capability, an intelligent scheduling mechanism is constructed, and multi-energy cooperative control and intelligent scheduling are realized.

The invention discloses a moving-coil direct-drive gravity energy storage device and a control method thereof, and belongs to the technical field of gravity energy storage. The moving-coil direct-drive gravity energy storage device comprises a direct-drive conveying system, an energy storage unit and an upper computer; the direct-drive conveying system comprises an alternating-current power grid, an energy storage converter, a direct-drive motor unit and a plurality of primary rotor carriers, one end of the energy storage converter is electrically connected with the alternating-current power grid, and the other end of the energy storage converter is electrically connected with the direct-drive motor unit through a direct-current bus. According to the device, electric energy and potential energy are efficiently and bidirectionally converted through the direct-drive conveying system and the energy storage unit, simultaneous movement of the multiple rotors is achieved, and the space efficiency ratio of gravity energy storage is increased; and compared with a traditional energy storage mode, redundant movement intermediate mechanisms are removed, unnecessary parts and connection are reduced, the installation space is effectively saved, the maintenance difficulty and cost are reduced, and the energy storage device can be applied to wider field conditions.

An automotive power system integrates a power factor correction circuit, an H-bridge power module, an externally excited synchronous machine, a traction inverter, and a traction battery. The system operates in two modes: driving and charging. In driving mode, power flows from the traction battery through the H-bridge power module and the traction inverter to the externally excited synchronous machine, enabling vehicle propulsion. In charging mode, power from an AC source is routed sequentially through the power factor correction circuit, the H-bridge power module, the synchronous machine, and the traction inverter.

The invention relates to an electrical traction network (1) for a motor vehicle, comprising a separately excited synchronous machine (2), a pulse-controlled inverter (3), a high-voltage battery (4), a DC / DC converter (6) and a charger (5), wherein the charger (5) has a mains connection (9) for an external AC voltage network, wherein the charger (5) is connected to AC voltage outputs of the pulse-controlled inverter (3) via first switching elements (S1), wherein the AC voltage outputs of the pulse-controlled inverter (3) are connected to the phases of the synchronous machine (2) via second switching elements (S2), wherein the DC voltage connections (HV+_PWR, HV-_PWR) of the pulse-controlled inverter (3) and an output of the DC / DC converter (6) are connected to the high-voltage battery (4) via third switching elements (S3), wherein the inputs of the DC / DC converter (6) are connected to the DC voltage connections (HV+_PWR, HV-_PWR) of the pulse inverter (3),wherein fourth switching elements (S4) are arranged between the output of the DC / DC converter (6) and two half-bridges of the DC / DC converter (6), wherein the DC / DC converter (6) is connected to a rotor winding of the synchronous machine (2) via fifth switching elements (S5), and a method for operating such an electrical traction network.

The invention relates to the technical field of low-voltage power supply and distribution systems, and discloses a dual-power-supply quick switching circuit for a low-voltage power supply system, which comprises a main power supply, a standby power supply, a circuit breaker QF1, a circuit breaker QF2, a relay KA1, a relay KA2, an alternating current contactor KM1, an alternating current contactor KM2 and a load, the main power supply is connected with the circuit breaker QF1, one path of the QF1 is connected with the KM1, and the KM1 is connected with the load; the other path is connected with the KA1 from the QF1, the KA1 is connected with the KM2, the KM2 is connected with a coil of the KM1 and then connected with the zero line N, and the 1B phase line and the 1C phase line of the main power supply are further connected with the two ends of the coil of the KA1; the standby power supply is connected with the circuit breaker QF2, one path of the QF2 is connected with the KM2, the KM2 is connected with the load, the other path of the QF2 is connected with the KA2 from the QF2, the KA2 is connected with the KM1, the KM1 is connected with a coil of the KM2 and then connected with the null line N, and the 2A phase line and the 2B phase line of the standby power supply are further connected with the two ends of the coil of the KA2. When the main power supply is abnormal, the standby power supply can be quickly switched to avoid shutdown of the lower-level equipment, the standby power supply can be automatically switched after the lower-level short circuit fault is isolated, and the power supply reliability of the low-voltage power supply and distribution system is greatly improved.