259 results about "Dc capacitor" patented technology

The invention discloses a fault ride-through test method for an offshore wind power flexible direct output system, and the method comprises the steps: building a fault equivalent circuit of the offshore wind power flexible direct output system, analyzing the operation characteristics of an AC power grid side under a low-voltage fault, and determining the incidence relation between the DC side excess energy and the power grid voltage drop; establishing a model representing each component in the fault equivalent circuit, wherein the components at least comprise a machine-side converter, a grid-side converter, a direct-current capacitor and an unloading resistor; when a low-voltage fault of an alternating-current power grid side is detected, executing the following cooperative control based on the model: synchronously starting unloading resistance control and reactive power support control, wherein an unloading resistor dissipates excess energy of a direct-current side through a direct-current chopper; the grid-side converter injects a capacitive reactive current which is deeply matched with the voltage drop of the power grid so as to improve the voltage of a grid-connected point; and if the direct-current voltage continuously exceeds the preset threshold value, starting power prompt drop control, and reducing the output power of the unit according to a gradient until the system recovers to be stable.

The invention relates to the technical field of power system control, in particular to a direct-current capacitor self-synchronizing grid-connected control strategy method, system, equipment and medium, a direct-current capacitor energy dynamic model is established based on an actual energy balance relation, a direct-current voltage signal is acquired in real time, and a synchronous compensation signal is calculated based on the acquired direct-current voltage signal; performing phase compensation and gain adjustment on the synchronous compensation signal through a correction link based on the calculated synchronous compensation signal, adjusting the internal frequency of the inverter based on the synchronous compensation signal after phase compensation and gain adjustment, controlling the DC voltage through the internal frequency of the inverter, and establishing a self-synchronization control model; and based on the self-synchronization control model, establishing an adaptive control algorithm, generating a damping coefficient and a virtual inertia coefficient through the adaptive control algorithm, and dynamically adjusting control parameters according to the damping coefficient and the virtual inertia coefficient.

The invention discloses a two-stage multi-mode bidirectional inverter circuit, which comprises a direct-current power supply DC, an alternating-current power supply AC, a DC / DC circuit, a direct-current voltage-dividing capacitor Cb1, a direct-current voltage-dividing capacitor Cb2, a DC / AC circuit and a controller, and is characterized in that a negative electrode of a second port of the DC / DC circuit is connected with a negative electrode of the direct-current voltage-dividing capacitor Cb1 and a negative electrode of a direct-current port of the DC / AC circuit; a middle point of a second port of the DC / DC circuit is connected with a negative electrode of a direct-current voltage-dividing capacitor Cb1 and a positive electrode of a direct-current voltage-dividing capacitor Cb2, and is connected to an alternating-current neutral line N; the AC port of the DC / AC circuit is connected with an AC live wire L1 and an AC live wire L2. The controller stably outputs voltage or current by controlling the DC / DC circuit and the DC / AC circuit, and bidirectional electric energy conversion is achieved. According to the invention, direct-current capacitance and additional circuits do not need to be increased, the size of the device is reduced, the system cost is reduced, the conversion efficiency is improved, and the device can be widely applied to new energy power generation and energy storage and other industrial and civil bidirectional power conversion systems so as to meet the global power supply and consumption requirements.

The invention discloses an energy storage type SOP black-start method, system and device based on improved VSG network construction control and a medium, and relates to the field of power grid black-start, and the method comprises the steps: an energy storage type converter MMC carries out the active and reactive control based on an improved VSG network construction control strategy; a non-fault side MMC is controlled to firstly close an isolation circuit breaker and slowly charge a direct-current capacitor, and when the voltage reaches a set threshold value, a current-limiting resistor is quitted; the fault side MMC is started by the same step as the non-fault side MMC; after synchronization is completed, AC circuit breakers between the non-fault side MMC and the feeder load and between the fault side MMC and the feeder load are closed respectively; based on the collected power grid power data, MMC output parameters are adjusted to meet the power grid connection condition, the control mode is switched according to the grid connection state, and the black start process is ended. And by arranging the black start resistor for current-limiting charging and sub-module voltage balance control, the phenomena of overcurrent and voltage unbalance in the black start process are avoided.

A kind of power device parallel type power module and capacitor charging and discharging method, power module includes two or more than pressure type power device, the two or more than pressure type power device adopts the physical form of half bridge group string upper and lower parallel;The half bridge group string of the pressure type power device is connected in parallel by silicon pile composite busbar;Each power module is provided with pneumatic short-circuit switch, in the case of multiple power module series connection, the pneumatic short-circuit switch is connected in series with all DC capacitors, and charging and discharging is carried out through the ground loop of flexible AC transmission equipment AC, DC valve side;The pneumatic short-circuit switch is connected with gas driving pipeline, and the gas driving pipeline is connected with valve-based gas pressurizing device.The power module can effectively improve the capacity of flexible AC transmission equipment, so that it has short-time frequency modulation capacity output, provides technical scheme support for new power system construction, and guarantees system safety and stability;The provided capacitor charging and discharging method can improve maintenance efficiency and enhance product reliability.

The invention provides a resistance voltage division control redundancy power supply circuit for a multi-level converter power sub-module, and relates to the technical field of power supply of the multi-level converter power sub-module. The resistor voltage division control redundancy power supply circuit comprises n voltage division resistors which are connected in series and are connected with a high-voltage direct-current capacitor in parallel; one end of the first through-current unit is connected with a connection point of the (k-1) th divider resistor and the kth divider resistor; one end of the second through-flow unit is connected with a connection point of the (j-1) th divider resistor and the jth divider resistor, and the other end of the second through-flow unit is connected with an energy storage capacitor of the bypass switch; one end of the resistance voltage division control branch is connected with one end of the first through-current unit, and the other end is connected with the negative electrode of the high-voltage direct-current capacitor; and two ends of the redundant power supply and energy taking module are respectively connected with the other end of the first through-current unit and the negative electrode of the high-voltage direct-current capacitor. In the low-voltage pre-charging stage of the multi-level converter power sub-module, starting of redundant power supply is achieved, black module faults are avoided, and the system reliability is improved.

The invention provides a direct-current capacitance determination method for a flexible interconnection device of a three-port intensive low-voltage power distribution network, the flexible interconnection device comprises three alternating-current ports and a direct-current port, each alternating-current port is connected with a power grid through an alternating-current feeder line, and the direct-current port comprises a plurality of direct-current capacitors; the method comprises the following steps: respectively determining active power and reactive power of three alternating-current feeder lines, and respectively determining current and modulation voltage of three alternating-current ports according to the active power and the reactive power of the three alternating-current feeder lines; according to the current and the modulation voltage of the three alternating current ports, determining a current instantaneous value of a direct current capacitor without a current direct current component in a fundamental wave period; determining the capacitance value of the direct current capacitor according to the capacitor voltage ripple limit value and the current instantaneous value of the direct current capacitor; the scene of multiple alternating current ports is considered, and the adjusting effect of the power flow is improved.

The invention discloses a model predictive control-based virtual inertia adjustment method and system for power electronic equipment. The method comprises the following steps of: respectively calculating an output power reference value and an output power adjustment amount of each power emitting node in a power grid before and after load power change; obtaining an output power prediction sequence in a certain time range in the future by taking minimization of a power loss function and a direct current loss function of the power electronic equipment in an adjustment process as a target through model prediction control; taking an output power predicted value obtained by calculation at the first moment as optimal control at the current moment, and mapping the optimal control back to a PWM control signal; and adjusting the output power of the power electronic equipment to a corresponding power reference value by cyclically repeating model predictive control and mapping PWM control signals. According to the method, the loss in the power adjustment process is effectively reduced while the power electronic equipment is ensured to provide the required virtual inertia, the stability of the direct-current capacitor voltage is maintained, and the dynamic stability and the energy utilization efficiency of a power grid system are improved.

The invention relates to a network construction type STATCOM (static synchronous compensator) analysis model based on DC capacitance dynamics, and belongs to the technical field of power distribution networks. The invention aims to realize the simulation of the synchronization characteristic of a synchronous machine by utilizing the similarity between the dynamic state of the direct current capacitor and the dynamic state of a generator rotor, namely a grid-building STATCOM analysis model based on the dynamic state of the direct current capacitor for the self-synchronous control of the direct current capacitor. The control structure of the internal frequency of the STATCOM on the direct current voltage is adjusted, a voltage equation under a synchronous coordinate system is deduced according to the superposition theorem and a topological graph, and the equivalent synchronous machine is obtained according to the equivalent principle, so that an equivalent rotor motion equation of the equivalent synchronous machine is obtained. According to the control mode, the internal frequency of the equipment can be adjusted to realize synchronization with the power grid, and stable operation of the direct-current side is ensured by controlling the direct-current voltage.

The invention discloses a magnetic flux coupling regulation type hybrid transformer and a control method thereof, and relates to the technical field of power distribution network voltage regulation equipment. The magnetic flux coupling regulation and control type hybrid transformer is composed of three three-column four-winding transformers and a voltage source type back-to-back converter. The three three-column four-winding transformers are the same in structure, and four windings are respectively an input winding, an output winding, an energy taking winding and a voltage regulating winding. The back-to-back converter is composed of a rectification unit, an inversion unit and a direct current capacitor. The rectification unit realizes stable control of DC voltage through controlling port current, and carries out reactive power and harmonic compensation on an input port of the hybrid transformer. And the inversion unit realizes flexible adjustment of the voltage of the output winding port of the hybrid transformer by controlling the output voltage of the inversion side. The method has the characteristic that the line fault current does not directly flow through the converter, and can reduce the voltage and current resistance level of a converter power device and the equipment protection difficulty, thereby reducing the cost of the hybrid transformer.

The invention specifically discloses an optical storage system dynamic damping control method based on direct current capacitor energy, and relates to the technical field of new energy. The method comprises the following steps: firstly, acquiring a direct-current bus voltage value, photovoltaic output voltage and current, energy storage battery voltage and current, LC filter inductive current and grid-connected point voltage and current in the current optical storage system; then, the photovoltaic system and the energy storage system are adjusted to operate cooperatively, the photovoltaic system achieves maximum power point tracking through a disturbance observation method, and the energy storage system stabilizes the direct-current bus voltage through a voltage-current double closed loop; secondly, based on a dynamic damping control strategy of direct-current capacitor energy, introducing a difference value between actual direct-current capacitor energy and a reference value into a network construction control active control loop through a direct-current damping coefficient; and finally, performing network construction control by combining an inverter virtual synchronous generator control technology. According to the method, existing hardware resources are effectively utilized, a complex algorithm is not needed, the dynamic performance of the system is remarkably improved, and the method has high adaptability and wide application prospects.

The invention provides a transformer DC capacitor state monitoring device and method based on an FPGA, and relates to the technical field of capacitor state monitoring. The device comprises a voltage acquisition module used for synchronously acquiring voltage analog signals at two ends of a DC capacitor in a plurality of MMC modules and performing analog-to-digital conversion; the current acquisition module is used for synchronously acquiring bridge arm current analog signals of a plurality of MMC modules and performing analog-to-digital conversion; the master control FPGA module is respectively connected with the voltage acquisition module and the current acquisition module, and is used for receiving and caching the digitized voltage signal and current signal, respectively calculating a real-time capacitance value of a direct-current capacitor in each MMC module based on a parallel sliding window and a hardware acceleration real-time capacitance value tracking algorithm, and outputting the real-time capacitance value of the direct-current capacitor in each MMC module; the degradation state of each direct-current capacitor is evaluated according to the real-time capacitance value; and the communication module is connected with the master control FPGA module and is used for uploading the degradation state data to an upper computer. According to the method, the real-time performance of monitoring can be remarkably improved while the calculation precision is ensured.

The invention discloses a power module. The power module comprises a direct current busbar, a radiator, an IGBT module I and an IGBT module II, the IGBT module I and the IGBT module II are respectively arranged on a mounting surface I and a mounting surface II of the radiator; the direct-current busbar comprises a direct-current busbar I, a direct-current busbar II, a direct-current busbar III and a direct-current busbar IV; the two ends of a fourth direct-current busbar are connected with the first IGBT module and the second IGBT module respectively, and the middle of the fourth direct-current busbar is connected with the middle of a third direct-current busbar. The two ends of the direct current busbar III are respectively connected with the direct current busbar I and the direct current busbar II; the direct current busbar I and the mounting surface I as well as the direct current busbar II and the mounting surface II are oppositely arranged and parallel to each other; the first direct current capacitor assembly is connected with the first direct current busbar, and the second direct current capacitor assembly is connected with the second direct current busbar. The influence of stray inductance is reduced by optimizing a current path, and the voltage spike at the switching moment is reduced due to the reduction of the stray inductance, so that the switching loss is reduced.

The present invention relates to the technical field of pumped-storage units, and particularly to a starting control method for a full-power variable-speed pumped-storage unit converter, including: when the unit starts, keeping the grid-side circuit breaker and the machine-side circuit breaker in the off state; controlling the excitation device to generate an initial excitation current; controlling the guide vane opening through the governor to control the speed increase of the motor, and judging the currently required operating state. If it is the power generation state, the machine-side converter enters the power control mode to complete the start; if it is the pumping state, closing the guide vane, the machine-side converter enters the braking and decelerating state. After the motor speed drops to 0, it drives the pump-turbine to increase speed in the reverse direction and enters the pumping working condition mode to complete the start. Through this control method, the additional DC capacitor charging circuit of the traditional full-power converter can be omitted, reducing the unit cost.

The invention relates to an expandable distributed voltage controller, and relates to the technical field of power grid electric energy management, the expandable distributed voltage controller comprises a series-parallel module comprising a parallel converter, a first series converter, a first DC capacitor and an isolation transformer, the DC side of the parallel converter is connected with the DC side of the first series converter through the first DC capacitor, and the DC side of the first series converter is connected with the isolation transformer through the isolation transformer; the alternating current side of the series converter is connected in series to the power grid side through the isolation transformer; and the series connection module comprises a second series connection converter, a second direct current capacitor and an isolation transformer, the second direct current capacitor is arranged on the direct current side of the second series connection converter, and the second series connection converter is connected to the load and / or the grid connection position in series through the isolation transformer. A plurality of problems can be solved while the power quality problem of the power grid is governed, so that the application range is wider.

The invention discloses a cooperative control method for suppressing transient overvoltage of a hybrid wind power plant, and the method comprises the steps: judging whether a fault occurs or not through monitoring a grid-connected bus voltage effective value and a DC capacitor voltage in real time; when the fault signal meets the synchronous trigger logic, switching the GFM-PMSG of the network-forming type fan to constant voltage control; and when the fault signal meets the low-voltage logic of the grid-connected point, the grid-following type fan GFL-PMSG is switched from steady-state control to low-voltage ride-through control, and meanwhile, a grid-connected bus reactive power compensator is cut off, and advanced reactive power cut-off control is carried out. According to the method, the problem of transient overvoltage caused by sudden change of voltage amplitude and phase of the GFM-PMSG of the grid-forming fan during a fault period, control lag of the GFM-PMSG and incapability of realizing instantaneous adjustment by reactive compensation equipment can be solved.

The present invention belongs to the technical field of power electronic converters and discloses a medium-voltage distribution network flexible interconnection switch topology and control method. The medium-voltage distribution network flexible interconnection switch topology provided by the present invention includes three connected reactors L1, three connected reactors L3, two chain-type STATCOMs, two three-phase isolation transformers, two three-phase LC filters, two three-phase inverter circuits, and a DC port. Back-to-back three-phase converters are introduced at the ends of the chain-type STATCOMs of two feeders. Through the back-to-back three-phase converters, active power flow mutualization between the two medium-voltage chain-type STATCOMs, that is, between two different feeders, can be achieved. The present invention can achieve DC capacitor voltage balancing of the chain-type STATCOM submodules of the two feeders. Compared with the BTB-VSC commonly used in existing medium-voltage distribution network flexible interconnection demonstration projects, this solution has lower cost, simpler topology, easier control, and does not need to consider the active and reactive power decoupling issues between interconnected feeders, making it easy to promote and apply on a large scale.

The invention relates to the technical field of power systems, and particularly discloses a high-voltage cascade valve hall type energy storage direct current side double-frequency current suppression method, which comprises the following steps of S1, acquiring the current of a branch where a battery cluster is located and / or the current of a battery stack direct current bus; s2, performing second harmonic extraction on the current of the branch and / or the current of the direct current bus to obtain a second harmonic generation harmonic current component; s3, performing difference calculation on the reference value of the double-frequency harmonic current component and the double-frequency harmonic current component to obtain a modulation signal; s4, inputting the modulation signal into a full-current controller, adjusting the output target voltage of the battery pack, and acting on a loop of a direct-current capacitor of a half-bridge sub-module and / or a full-bridge sub-module to realize suppression of a double-frequency harmonic current component; according to the invention, the extracted double-frequency harmonic current component is compared with the preset reference value to generate the modulation signal, and the battery pack is adjusted by using the modulation signal to output the target voltage, so that suppression of the double-frequency harmonic current component is realized.

The invention relates to the technical field of all-condition equivalent testing of flexible direct current capacitors, and discloses an all-condition equivalent testing method and system for a flexible direct current capacitor. The preset working condition voltage is adjusted according to the waveform consistency judgment result of the sample so as to equivalently simulate the alternating-current and direct-current superposed voltage and pulse power characteristics in actual operation; and collecting the surface temperature and leakage current of the sample, and finally generating an electric heating performance parameter curve through comparison and judgment with a preset threshold value. By dynamically adjusting the working condition voltage and strictly monitoring the waveform consistency, the pulse power intensity of large-current charging and discharging of the capacitor in each working period in actual operation is effectively reproduced, and the performance change under the real operation working condition is comprehensively reflected by combining environmental parameter simulation and real-time monitoring of temperature and current. The technical problems that in the prior art, the pulse power intensity of the capacitor in the continuous charging and discharging process along with large current in each work period during operation is difficult to reflect, and the real operation condition cannot be comprehensively reflected are solved.

The invention discloses a sequential active frequency support method for an offshore wind power flexible direct current sending-out system, and the method comprises the steps: constructing a dynamic coupling relation between the frequency of an onshore alternating current system and the direct current voltage at a receiving end converter station through a direct current voltage synchronous control technology; the grid-connected power of a receiving end converter station is adjusted in real time according to the frequency change of an onshore alternating-current power grid by setting a proper direct-current voltage and frequency coupling coefficient. In a sending end converter station, additional control based on direct current voltage-frequency is added. And according to the fluctuation of the direct-current voltage, the frequency given value of the offshore alternating-current collection system is adjusted in real time, so that the stored energy of the sub-module capacitor of the sending-end converter station is released, and short-time frequency support is realized. In addition, the control strategy of the offshore wind turbine generator is improved, and fan virtual inertia control and primary frequency modulation control are introduced; and the frequency modulation function is realized by fully releasing the DC capacitor of the wind turbine generator and the stored energy of the rotor. The frequency change of the alternating current system can be quickly responded, and the stability is enhanced.

The invention relates to the technical field of power grid control, in particular to a control parameter design method and device for a multi-scene active support type networking SVG (Static Var Generator), and the method comprises the steps: determining the target power grid strength and an active support demand based on a short-circuit ratio and an inertia ratio; determining a parameter steady-state reference value and a boundary of the network-forming static var compensator; the short-circuit ratio and the inertia ratio are dynamically mapped to the virtual impedance, the voltage regulation coefficient and the frequency modulation coefficient of the network-forming type static var compensator; and based on the parameter steady-state reference value, the boundary, the virtual impedance, the voltage regulation coefficient and the frequency modulation coefficient, comprehensively determining a direct-current system value according to a direct-current capacitance value and a system inertia demand, and generating control parameters of the multi-scene active support network-forming static var compensator. Therefore, the problems of inertia deficiency, poor frequency stability and the like of a power grid system due to the fact that network construction SVG control mainly adopts fixed parameters or a parameter adjustment principle is determined from a short circuit ratio single dimension in related technologies are solved.

The invention provides a grid-connected frequency modulation control strategy based on photovoltaic power prediction so as to solve the problems of stability and safety of a power system under high-proportion photovoltaic grid connection. According to the strategy, new parameters representing characteristics of a traditional synchronous generator set and a photovoltaic system are introduced, and a control strategy of a power grid side inverter is improved based on actual grid-connected working conditions. Meanwhile, a frequency dynamic response model considering the photovoltaic penetration influence is established, and the inertia response of the synchronous generator set is accurately simulated by introducing the dynamic characteristics of a power grid side direct current capacitor. And by adjusting the virtual inertia and the adjustment factor, the anti-disturbance capability of the photovoltaic system is enhanced. In combination with historical photovoltaic power generation data, the photovoltaic power is predicted by adopting data normalization, feature selection, SOM clustering analysis, singular spectrum analysis and a full-connection network model, and the prediction accuracy is improved. And the control strategy is combined with the power prediction result to realize efficient and stable frequency modulation control of the grid-connected photovoltaic system.

A motor driving device and a home appliance according to one embodiment disclosed herein comprises: a converter for converting input alternating current power into direct current power to output the direct current power; a direct current terminal capacitor for storing the direct current power; an inverter which includes a plurality of upper arm switching elements and lower arm switching elements connected in series, and converts the direct current power from the direct current terminal capacitor into alternating current power to drive a motor; a current detection unit disposed between the direct current terminal capacitor and the inverter; gate drivers for driving the switching elements included in the inverter; bootstrap capacitors which are charged in response to the lower arm switching elements being turned on and supply a driving voltage to the gate drivers of the upper arm switching elements; and a control unit for controlling the inverter on the basis of the current detected by the current detection unit, wherein the control unit first turns some of the plurality of lower arm switching elements on and off and then turns the other lower arm switching elements on and off before driving the motor.

The present invention discloses an expanded T-type three-phase three-level converter and a modulation method thereof. The first end of a three-phase input filter module in the expanded T-type three-phase three-level converter is electrically connected to an AC power supply module, the first end of a three-phase expansion module is electrically connected to a second end of the three-phase input filter module, and the second end is connected to a first DC capacitor and a second DC capacitor in a delta-connected DC capacitor module, connected to points P, O, and N. The first end of the delta-connected DC capacitor module is electrically connected to the second end of the three-phase expansion module, the first end of a T-type three-phase three-level three-phase inverter module and the second end of the delta-connected DC capacitor module are electrically connected to points P, O, and N, and the first end of a three-phase output filter module is electrically connected to the second end of the T-type three-phase three-level three-phase inverter module. The present application has the advantages of continuously adjustable output voltage, excellent input and output power quality, and low switching loss.

The invention relates to a power module and a direct-current power transmission system, the power module is formed by constructing an upper power switch device, a lower power switch device, a direct-current capacitor, a discharge resistor and a multi-level driving circuit, and an upper tube and a lower tube of the power module are arranged in a differentiated manner, namely, the upper power switch device is configured to comprise a universal power switch device. The lower tube comprises a diode enhanced power switch device, and proper driving resistors are respectively configured for the upper tube and the lower tube through a multi-level driving circuit, so that the consistency of dynamic parameters of the upper tube and the lower tube is ensured, and the influence of direct current bias and the like caused by inconsistent device specifications is eliminated as far as possible; therefore, the upper tube and the lower tube can be reliably conducted in turn during normal operation, namely, the power conversion function is realized. According to the scheme, under extreme working conditions of short circuit and the like, surge current can pass through the diode of the diode enhanced power switch device, namely, autonomous shunt protection is realized, and excessive additional devices do not need to be arranged.

The application provides a pre-charging method and system of a motor train unit traction auxiliary converter, the method comprising: closing an output contactor in the traction auxiliary converter according to a received contactor closing instruction; if no pre-charging instruction is received, judging whether to perform a pre-charging process on a direct current capacitor in the traction auxiliary converter according to a voltage of the direct current capacitor and a preset rated voltage; if yes, obtaining three-phase alternating current voltages and three-phase alternating current of an alternating current port of an auxiliary inverter in the traction auxiliary converter, determining active current feedback values and reactive current feedback values, and generating a pulse signal, and sending the pulse signal to the auxiliary inverter, so that an output voltage of a direct current port of the auxiliary inverter reaches the rated voltage. The application realizes the pre-charging function of the converter without increasing the hardware of the converter, reduces the cost, improves the availability of the converter, reduces the current impact of the switching device and the action frequency, helps to improve the service life and reduce the failure rate.

A distributed ice melting device topological structure suitable for an ultra-high voltage power transmission line comprises a plurality of ice melting sub-modules arranged in a distributed mode, and each ice melting sub-module comprises a single-turn coupling transformer, a metal oxide voltage limiter, a bypass switch, a filter, an H-bridge current converter and a direct-current capacitor. A primary winding of the single-turn coupling transformer is directly formed by split sub-conductors of the ultra-high voltage power transmission line, and a secondary winding of the single-turn coupling transformer is electrically connected with other parts of the ice melting sub-modules, so that the ice melting sub-modules are connected in series on the split sub-conductors of the power transmission line in a distributed manner; the H-bridge current converter is electrically connected with the direct-current capacitor, and the direct-current capacitor provides smooth direct-current voltage for the H-bridge current converter; the filter is connected in series with the H-bridge current converter, the bypass switch is connected in parallel with the H-bridge current converter, and the metal oxide voltage limiter is connected in parallel with the line side output end of the ice melting sub-module; and the ice melting sub-modules adjust the current of the corresponding split sub-conductors by changing the equivalent impedance of the ice melting sub-modules, so that accurate ice melting of the ice-coated split sub-conductors is realized, and the overall current and the transmission power of the power transmission line are kept unchanged. The technical problem to be solved by the invention is to provide the distributed ice melting device topological structure suitable for the ultra-high voltage power transmission line, and the technical problem that the existing ice melting technology cannot realize accurate ice melting and non-power-cut operation on an ice coating section on the ultra-high voltage power transmission line is solved. And normal transmission of the line is affected due to overlarge capacity demand, line overcurrent or incapability of three-phase synchronous ice melting.

The invention discloses a monitoring circuit of a turning thyristor and a monitoring method thereof, and belongs to the technical field of power device control. The monitoring circuit of the turning thyristor is provided with a first driving unit, a second driving unit, a voltage detection unit, a control unit, a first leakage current detection unit and / or a second leakage current detection unit; and detecting the capacitor voltage of the direct current capacitor in real time, identifying a first breakdown result of the first leakage current detection unit and / or a second breakdown result of the second leakage current detection unit, and judging whether the turning thyristor is abnormal breakdown or not by combining the capacitor voltage, the first breakdown result and / or the second breakdown result. Therefore, on-line monitoring of the working state of the turning thyristor is realized, a certain reference significance is provided for analysis of failure reasons of the turning thyristor and improvement of the operation reliability of the modular multilevel converter in high altitude and other scenes, the protection action of the power module is further triggered, the fault range is prevented from being expanded, and reliable operation of direct current transmission is guaranteed.

The embodiment of the invention relates to the technical field of direct-current power transmission, and discloses a flexible chopping type direct-current energy consumption device and an online energy taking power supply, method and system thereof, and the online energy taking power supply comprises an input end, a starting circuit, a PWM controller, a switching tube Q, a transformer T and a photoelectric coupler OC; the first end of the input end is connected to a direct current capacitor C of the power module; the second end of the input end is connected to the input end of the starting circuit; the output end of the starting circuit is connected to the first input end of the PWM controller; the output end of the PWM controller is connected to the first pole of the switching tube Q; the second pole of the switching tube Q is connected to the primary side of the transformer T; the secondary side of the transformer T is connected to the input end of the photoelectric coupler OC; and the output end of the photoelectric coupler OC is connected to the second input end of the PWM controller. According to the embodiment of the invention, the energy required by the control circuit can be conveniently obtained, and an industrial frequency transformer is not needed.

The application discloses a power assembly and a liquid-cooled converter, the power assembly comprising a capacitor module, a power module and a radiator; the capacitor module comprises DC capacitor banks and a capacitor busbar connected with each other; the power module comprises an input busbar, an output busbar and three single-phase switch tube groups, each single-phase switch tube group comprising a plurality of switch modules and being connected to the input busbar and the output busbar; the input busbar is connected to the connecting part; the output busbar is used for outputting electric energy; and all single-phase switch tube groups in the power module are mounted on the radiator, and the arrangement direction of each switch module in each single-phase switch tube group is parallel to the connecting part. The power assembly can solve the problem of large volume of the existing power assembly.