39 results about "Current source converter" patented technology

The invention provides a hybrid direct-current power transmission system, a system control method and a hybrid direct-current power transmission device.The system comprises a sending-end converter and a receiving-end converter which are used for being electrically connected with an alternating-current bus, the sending-end converter comprises a positive-pole converter and a negative-pole converter, the positive-pole converter is used for being electrically connected with a positive pole of a direct-current line, and the negative-pole converter is used for being electrically connected with a negative pole of the direct-current line; the negative current converter is electrically connected with the negative electrode of the direct current line, and the positive current converter comprises a full-control current source current converter; the cathode converter comprises a modularized multi-level converter and / or a controllable commutation current source converter, and the anode converter and the cathode converter both comprise full-control devices; the receiving-end converter is electrically connected with the sending-end converter through a direct-current line, and the receiving-end converter is a converter controlled by direct-current voltage. According to the system, a CCSC and HCC / MMC hybrid high-voltage direct-current power transmission system is adopted at the sending end, and hundred percent new energy sending of an alternating-current bus is achieved.

The invention provides a two-degree-of-freedom fundamental frequency modulation method and device of a multi-level current source converter. And triggering each bridge arm in the multi-level current source converter by adopting a fundamental frequency modulation mode according to a preset first degree of freedom and a preset second degree of freedom under the condition that the terminal voltage of the U-phase filter capacitor has a zero crossing point moment. On the basis of the first degree of freedom and the second degree of freedom, the switching speed of a semiconductor device on a bridge arm in the multi-level current source converter can be reduced by adopting a fundamental frequency modulation mode, and the harmonic quality of the multi-level current source converter is greatly improved, so that the operation loss of the multi-level current source converter is reduced, and the service life of the multi-level current source converter is prolonged. And the sampling cost and the control cost of the sensor are reduced. The multi-level current source converter can realize decoupling of voltage and power, so that the operation of the multi-level current source converter is more flexible and efficient.

The invention belongs to the technical field of power electronics, and provides a multi-degree-of-freedom general carrier modulation method and system for a current source converter, and the method comprises the steps: constructing a modular cascade current source converter; a sine pulse width sequence is output through carrier modulation to analyze direct-current side voltage harmonic distribution in the constructed modular cascade current source type converter; determining the optimal phase shift angle of the modular cascade current source type converter by taking the sine pulse width sequence waveform quality, the switching frequency and the DC voltage performance optimization as optimization targets according to the distribution result of the DC side voltage harmonic waves; and adjusting the three-phase carrier wave of each current source module in the current source type converter based on the determined optimal phase shift angle, and completing multi-degree-of-freedom general carrier wave modulation of the current source type converter.

A control circuit for a current source converter having a current generator comprising an inductance and having two or more half bridges, each half bridge having an upper leg provided with upper switching devices and a lower leg provided with lower switching devices, the upper leg switching devices and the lower leg switching devices being controlled by a controller to provide overlap between upper leg off switching devices and upper leg on switching devices and to provide overlap between lower leg on switching devices and lower leg off switching devices by gate pull-up and pull-down pulse signals input to gate driver buffers of the switching devices, characterized in that the gate driver circuit comprises: - a gate current mirror circuit for each upper leg switching device and each lower leg switching device, the gate current mirror circuit providing a gate pull-down signal on a source branch of the gate driver buffer of the switching device when the switching device is off, the gate pull-down signal being connected to a control line of a gate buffer of a respective other upper leg switching device or other lower leg switching device, - a positive gate command connection path from a positive gate command output of a pre-driver for each upper leg switching device and each lower leg switching device, the positive gate command connection path providing a reset signal for the gate pull-down signal of the respective other upper leg switching device or respective other lower leg switching device.

The utility model provides an alternating-current parallel hybrid converter and a direct-current power transmission system, and relates to the technical field of high-voltage direct-current power transmission. The AC parallel hybrid converter comprises: a current source converter; the alternating current side of the voltage source converter is connected with the alternating current side of the current source converter in parallel; and one end of the reactor is connected with the alternating current side of the current source converter, and the other end is connected with an alternating current system. The AC parallel hybrid converter filters 6k + / -1 harmonic waves by using a voltage source converter, the high-voltage DC power transmission system directly adopts a six-pulse bridge circuit, and a converter transformer is replaced by an electric reactor, so that the converter structure of the high-voltage DC power transmission system is simplified, and the equipment manufacturing cost is reduced.

The application relates to a hybrid bridge arm and a control method thereof, a half-bridge circuit and a current source type converter. The half-bridge circuit of the current source type converter comprises a series connection of an upper bridge arm and a lower bridge arm. At least one of the upper bridge arm and the lower bridge arm is a hybrid bridge arm. The hybrid bridge arm comprises a conduction voltage drop optimization bridge arm and an off current optimization bridge arm in parallel connection. The conduction voltage drop of the conduction voltage drop optimization bridge arm is smaller than the conduction voltage drop of the off current optimization bridge arm. The off current capability of the off current optimization bridge arm is higher than the off current capability of the conduction voltage drop optimization bridge arm. The hybrid bridge arm is formed by connecting the conduction voltage drop optimization bridge arm with low conduction voltage drop and the off current optimization bridge arm with high off current capability in parallel connection. The current source type converter is composed of the hybrid bridge arm. The current source type converter can improve the off current capability while reducing the conduction voltage drop, realizes the simultaneous optimization of the operation efficiency and the operation range of the current source type converter, and improves the upper limit of the working performance constraint of the current source type converter.

An exemplary embodiment of the present disclosure provides a resonant module and sensing circuits for use with a soft-switching current source converter. The resonant module comprises a resonant switch, a resonant inductor, and a resonant capacitor. The resonant inductor is connected in electrical series with the resonant switch. The resonant capacitor is connected in parallel with the serially connected resonant switch and resonant capacitor. The resonant module further comprises first and second sensing circuits. The first sensing circuit is configured to generate a first sensing signal indicative of when the time derivative of a voltage across the resonant capacitor is negative. The second sensing circuit is configured to generate a second sensing signal indicative of when a voltage across the resonant capacitor is less than or equal to a predetermined threshold value.

The application provides a full-control current source converter DC transmission line fault detection method and device, relates to the high-voltage DC transmission technical field, and the method comprises the following steps: acquiring the actual first-end voltage, actual first-end current and actual last-end voltage of the full-control current source converter DC transmission line; taking the acquired actual first-end current and actual last-end voltage as inputs, outputting the predicted first-end voltage of the full-control current source converter DC transmission line through a preset digital twin reference model; determining whether the full-control current source converter DC transmission line is faulty based on correlation analysis on the actual first-end voltage and the predicted first-end voltage; wherein the digital twin reference model is used to represent the mapping relationship between the first-end current, last-end voltage and first-end voltage in the time domain. The application effectively improves the accuracy and efficiency of full-control current source converter DC transmission line fault identification.

Method for modulating an n-phase current source converter, comprising the steps: a) obtaining duty ratio values, which are identified by using the following four sub-steps: i. obtaining initial duty ratio values, which are used to determine required output currents, from the ratio of AC output current reference values and a DC supply current value, ii. determining excess duty ratio values, which are used to compensate a missing duty ratio value, wherein the missing duty ratio value results from the subtraction between 1 and a sum of the initial upper or initial lower duty ratio values, wherein the sum of initial upper duty ratio values equals the sum of initial lower duty ratio values, iii. splitting the missing duty ratio value among converter legs that results in final duty ratio values and iv. obtaining cumulative sums of the initial or final duty ratio values, which are supplied to the comparator array as thresholds, b) comparing multiple thresholds through the comparison of the cumulative sums of the initial duty ratio values or final duty ratio values to a piecewise linear carrier signal, which results in n-1 digital signals obtained from n-1 comparators, wherein the comparing of multiple thresholds is performed by a first multiple threshold modulator for the upper switches and a second multiple threshold modulator for the lower switches, and c) processing of the digital signals from the multiple threshold comparator to obtain gating signals by using a digital combinatorial logic.

This invention discloses an injection pulse modulation method for a multi-level injection current source converter, S1. Based on the main bridge switching frequency f s Determine the main bridge switching cycle T s The period T of the injection circuit switching pulse is determined based on the number of injection levels m. inj S2. Generate a carrier frequency of 6f s The triangular carrier wave; S3. The carrier amplitude A c Divide T into 2(m-1) equal parts; S4. inj Decompose into (m-1) carrier periods; S5. Traverse M1 to M in the positive and negative intervals. (m‑1) S6. Compare the modulated wave with the carrier wave to obtain the injection pulse scheme that satisfies the injection pulse condition; This invention provides an intuitive and easy-to-implement new method, which not only avoids the complexity and error-proneness of traditional counting and assignment methods, but also simplifies and accelerates the conversion process between different injection pulse schemes. In addition, the modulation wave generation technology in this invention provides a new perspective for understanding how different injection pulse schemes affect the harmonic content of the AC and DC side current of the system.

The application discloses a commutation margin hybrid compensation system, method and device and related equipment, and the system comprises at least one 12-pulse converter bridge, at least two converter transformers, a smoothing reactor, a network-side AC bus, at least two commutation margin hybrid compensation devices, the commutation margin hybrid compensation device comprising a valve-side AC bus, a shunt capacitor bank and at least one current source converter; the shunt capacitor bank and the current source converter are both connected in parallel on the valve-side AC bus; the shunt capacitor bank is configured to provide reactive compensation to the 12-pulse converter bridge and filter out high-order harmonics; the current source converter is configured to increase the actual extinction angle of the 12-pulse converter bridge by outputting a preset harmonic current. The scheme effectively increases the commutation margin, reduces the risk of commutation failure, accurately compensates for reactive power and harmonics nearby, saves the traditional AC filter, reduces the occupied area, and reduces the loss and cost.

An exemplary embodiment of the present disclosure provides a current source converter, comprising a transformer, a first circuit, and a second circuit. The transformer can comprise a first winding, a second winding, and a third winding. The first circuit can be electrically coupled to the first and second windings. The first circuit can comprise a battery port and a photovoltaic (PV) port. The battery port can be configured to interface with one or more batteries. The PV port can be configured to interface with one or more PV modules. The second circuit can be electrically coupled to the third winding. The second circuit can comprise an alternating current (AC) port configured to interface with an AC load.

This application provides a method and apparatus for adjusting the firing angle of a turn-off current source converter. The maximum firing angle of the turn-off current source converter can be calculated based on the DC voltage protection value and the sampled values ​​of the three-phase AC phase voltages. An upper limit value for the firing angle of the turn-off current source converter is calculated based on the maximum firing angle. The firing angle of the turn-off current source converter is then adjusted based on this upper limit value. In the event of a three-phase AC fault at the receiving-end converter station, adjusting the firing angle can reduce the reactive power absorbed by the turn-off current source converter. Combined with other reactive power compensation devices, reactive power can be injected into the AC system. After the three-phase AC fault is cleared, it supports the restoration of AC voltage in the AC power grid, thus improving the turn-off current source converter's ability to support transient reactive power in the AC power grid.

The application provides a current source converter, a control method and a system. The current source converter comprises a first bridge arm module and a second bridge arm module, the first bridge arm module comprises a plurality of first bridge arms, the second bridge arm module comprises a plurality of second bridge arms, each output end of a three-phase power supply is connected with one first bridge arm in the first bridge arm module and one second bridge arm in the second bridge arm module respectively, each first bridge arm comprises a plurality of first power devices respectively, and each second bridge arm comprises a plurality of second power devices respectively; at least one first auxiliary module is at least partially connected on the first bridge arm and electrically connected with the first poles of the first power devices to provide commutation voltage compensation for a faulty first bridge arm; and at least one second auxiliary module is at least partially connected on the second bridge arm and electrically connected with the first poles of the second power devices to provide commutation voltage compensation for a faulty second bridge arm, so that the problem of low commutation efficiency of the current source converter is solved.

The application belongs to the technical field of power electronics, and provides a multi-degree-of-freedom universal carrier modulation method and system of a current source converter, comprising: constructing a modular cascaded current source converter; using carrier modulation to output a sine pulse width sequence to analyze the DC side voltage harmonic distribution in the constructed modular cascaded current source converter; according to the distribution result of the DC side voltage harmonic, taking the sine pulse width sequence waveform quality, the switching frequency and the DC voltage performance as the optimization target, determining the optimal phase shift angle of the modular cascaded current source converter; based on the determined optimal phase shift angle, adjusting the three-phase carrier of each current source module in the current source converter, and completing the multi-degree-of-freedom universal carrier modulation of the current source converter.

The application provides a current source type converter admittance simulation reactive power regulation method and system, and belongs to the technical field of current source type converter regulation, and comprises the following steps: establishing a single-phase equivalent circuit of a current source type converter grid-connected system, and collecting capacitor voltage; transforming the collected capacitor voltage to obtain transformed voltage, processing the transformed voltage by using an integrator to obtain a fundamental wave in-phase component, a fundamental wave quadrature component and a non-fundamental wave residual error; constructing a fundamental wave admittance current reference according to an outer ring given active instruction reactive power instruction; low-pass shaping the non-fundamental wave residual error to obtain intermediate output, and further processing the intermediate output to obtain a non-fundamental wave damping current reference; superimposing the fundamental wave admittance current reference and the non-fundamental wave damping current reference to form a current source type converter injected current total reference; and the current source type converter adopts a current source type converter ring to make an actual injected current track the current source type converter injected current total reference, so that expected frequency division admittance simulation is realized at a capacitor node.

The application provides a kind of receiving end converter device and direct current transmission system, the receiving end converter device includes: modular multilevel converter, its direct current side is used to be electrically connected with direct current pole line, its alternating current side is used to be electrically connected with first alternating current network;Current source converter, its direct current side is used to be electrically connected with direct current pole line, its alternating current side is used to be electrically connected with second alternating current network, the voltage of first alternating current network is different from the voltage of second alternating current network;Controller is connected with modular multilevel converter and current source converter respectively, controller is used to control modular multilevel converter and current source converter to run in different working mode.The application solves the problem of poor system stability in the prior art of the access mode of the receiving end converter device.

The application provides a kind of adaptive modal injection type current source converter energy efficiency optimization control method based on PPO algorithm, it is related to power supply system field, it is applied to injection type current source converter, injection type current source converter includes twelve pulse inverter and multiple injection branches cascaded in the DC side of twelve pulse inverter, and the method comprises: collecting real-time meteorological data and real-time power grid state data;Through the reinforcement learning agent based on proximal policy optimization algorithm, based on real-time meteorological data and real-time power grid state data, determine the optimal action, wherein the optimal action at least includes target level number, the number of injection branches that need to be started and the number of injection branches that need to be disabled;According to optimal action, control multiple injection branches run, with the advantage of realizing the optimal operation of injection type current source converter under all operating conditions.

The present disclosure relates to the technical field of converters, and provides a control method, apparatus and circuit for a current source converter, a device, and a medium. The method comprises: measuring a direct current voltage outputted by a current source converter; when the direct current voltage is greater than a direct current upper limit threshold, controlling a plurality of controllable switching devices in the current source converter to be switched off, so as to disconnect a charging circuit of a direct current bus capacitor in the current source converter; and when the direct current voltage is less than a first direct current lower limit threshold, determining a drive control signal, and controlling the plurality of controllable switching devices in the current source converter on the basis of the drive control signal. In the present disclosure, charging of the bus capacitor is stopped by controlling the plurality of controllable switching devices to be switched off, and in this process, the bus capacitor keeps supplying power to a load, so that the direct current voltage is reduced, thereby reducing the possibility of direct current overvoltage protection events and load safety threatening events, and improving the stability and safety of load operation.

This invention provides a current source system and current source control method for green hydrogen production, including a new energy AC power generation system, a new energy DC power generation system, an AC current source converter, a DC current source converter, a three-phase transformer, a single-phase transformer, and an impedance-controlled and stabilizing load. The impedance-controlled and stabilizing load includes a controlled-adjustable variable impedance device and an electrolyzer. The new energy AC power generation system is connected to the AC power source converter via the three-phase transformer. The new energy DC power generation system is connected to the DC current source converter via the single-phase transformer. The impedance-controlled and stabilizing load is connected to both the AC and DC current source converters. The three-phase and single-phase transformers achieve voltage level transformation between the power generation system and the current source converter to meet the control of the current and power of the electrolyzer in the impedance-controlled and stabilizing load. This invention can achieve reliability and safety in hydrogen production from renewable energy sources at the refinery level.

The application relates to a current source converter valve protection system and a current source converter. An AC filter capacitor and a converter transformer are connected to an AC outlet end of the current source converter valve respectively, and a second end of the converter transformer is connected to an AC power grid. Thus, AC-DC conversion can be performed in the process of power transmission. Moreover, a capacitor protection module is connected to the AC filter capacitor. Through the capacitor protection module, overvoltage protection can be performed on the AC filter capacitor in the case of an AC side fault of the current source converter valve, and / or oscillation suppression can be performed on the AC filter capacitor in the case of recovery of the AC side fault. Thus, it can be ensured that the AC filter capacitor will not be overvoltage in the case of the AC side fault of the current source converter valve, and / or the AC filter capacitor can quickly return to a steady state in the case of recovery of the AC side fault, thereby greatly reducing the operation risk of the filter capacitor in the current source converter valve.

The application provides a harmonic current injection control method of a full-controlled current source converter and related devices, and relates to the technical field of harmonic current injection. In the application, a main valve generates a harmonic current, an auxiliary valve generates a reverse harmonic current, and the two cooperate with each other to eliminate the harmonic current injected into an alternating current system. In addition, the auxiliary valve can only generate a voltage, and a difference between an alternating current voltage fundamental reference value and an alternating current voltage actual value is divided by a filter inductance to generate a harmonic current reference signal. Furthermore, by separating a target harmonic component and adaptively injecting a gain of a reverse harmonic, a harmonic injection loop is formed, and independent control and periodic control of specific harmonics are realized by using the harmonic injection loop. The whole implementation process does not need to use a bridge arm reactance, can simplify the structure of the full-controlled current source converter, and saves cost.

This invention discloses an isolated current source converter based on an SP-type pseudohermite coreless transformer, comprising a negative resistor, an SP-type pseudohermite coreless transformer, a full-bridge rectifier, and a load resistor. The negative resistor is connected to the input terminal of the SP-type pseudohermite coreless transformer. The full-bridge rectifier includes a first rectifier arm, a second rectifier arm, an output filter inductor, and an output filter capacitor. The switching nodes of the first and second rectifier arms are connected to the output terminal of the SP-type pseudohermite coreless transformer. The output filter inductor and output filter capacitor are connected in series and then in parallel with the first and second rectifier arms, respectively. The output filter capacitor is connected in parallel with the load resistor. This invention, using an SP-type pseudohermite coreless transformer as its core, realizes a coreless isolated current source converter with constant current output characteristics independent of the load. This invention achieves corelessness, greatly reducing the weight, size, and cost of the isolated current source converter.

The invention discloses a commutation margin hybrid compensation system, method and device and related equipment, and the system comprises at least one 12-pulse converter bridge, at least two converter transformers, a smoothing reactor, a network side AC bus, and at least two commutation margin hybrid compensation devices. The commutation margin hybrid compensation device comprises a valve side alternating current bus, a parallel capacitor bank and at least one current source type converter. The parallel capacitor bank and the current source converter are connected in parallel to the valve side alternating current bus; the parallel capacitor bank is configured to provide reactive compensation for the 12-pulse converter bridge and filter higher harmonics; the current source converter is configured to increase the actual extinction angle of the 12-pulse converter bridge by outputting a preset harmonic current. According to the scheme, through hybrid compensation and cooperative control, the commutation margin is effectively increased, the commutation failure risk is reduced, reactive power and harmonic waves are accurately compensated nearby, a traditional alternating current filter is omitted, the occupied area is reduced, and loss and cost are reduced.

The invention discloses a method for realizing a multi-three-phase balanced output low-ripple current source, which is characterized in that voltage source DCDC converter modules are connected with the output end of an active Boost power factor correction module and are used for converting high-voltage DC voltage into required DC voltage, and the output ends of the three voltage source DCDC converter modules are connected in parallel; the current-sharing bus serves as a feedback signal, balances the output current of each voltage source DCDC converter module by controlling the working states of the voltage source DCDC converter modules, and balances the power of an alternating current input end to realize multi-three-phase balanced output. The current source DCDC converter module is connected with the output end of the voltage source DCDC converter module and used for converting the voltage into constant current to be output, and low-ripple current source output is achieved; through cooperation of the voltage source DCDC converter module and the current source DCDC converter module, low-ripple current source output is realized, output current of each module is balanced through the current-sharing bus, power of an alternating current input side is further balanced, and multi-three-phase balanced output is realized.

The application relates to a current source converter operation method and device and a current source converter. The number of IGCT devices to be turned off to meet the active commutation demand of a single active commutation task of a same bridge arm is acquired. In the case that the current source converter has an active commutation demand, the turned-off IGCT devices are turned off in turns every time the same bridge arm performs an active commutation task. Finally, after a rotation cycle is completed, the number of times of turning off all the IGCT devices in the same bridge arm is consistent. In this way, the commutation function can be realized by turning off a small number of IGCT devices every time the bridge arm of the current source converter performs an active commutation task. Moreover, the turned-off IGCT devices are rotated every time the commutation task is performed, and all the IGCT devices do not need to be turned off every time the commutation is performed, so that the heat of the turned-off IGCT devices can be shared. The number of times of actively turning off the bridge arm of the current source converter is increased, and the ability of the current source converter to resist commutation failure is improved.

The utility model provides a current source converter of a hybrid controllable capacitor bank and a direct current power transmission system. The converter comprises a plurality of converter transformers; a converter bridge circuit; the hybrid controllable capacitor bank comprises a first passive filter and a controllable capacitor bank which are electrically connected, the controllable capacitor bank comprises a plurality of fully-controlled devices and capacitors which are electrically connected, and each phase alternating current end of the converter bridge circuit is electrically connected with the first passive filter; the first ends of the filter reactors are electrically connected with the hybrid controllable capacitor bank and one phase alternating current end of the converter bridge circuit respectively, and the second ends of the filter reactors are electrically connected with the second ends of the corresponding converter transformers. According to the converter, the first passive filter is electrically connected with the controllable capacitor bank, so that the output alternating voltage of the controllable capacitor bank is reduced, and the number of sub-modules of the controllable capacitor bank is directly reduced under the condition that the voltage grade of a single sub-module is not changed, so that the cost and the loss are reduced.

The invention provides a parameter design method for a photovoltaic direct-current module converter based on efficiency optimization, which comprises the following steps of: improving a current source converter, and adopting a voltage doubling rectifying circuit on a secondary side of the current source converter on the basis of the existing current source converter; loss analysis and device optimization are carried out on the converter on the basis of efficiency optimization by establishing a loss analysis model of the converter, and the efficiency and the power density of the converter are comprehensively considered according to optimization results under different switching frequencies; the optimal design result of the photovoltaic direct current module main circuit based on the current source type half-bridge converter is determined, and the efficiency of the photovoltaic direct current module converter is greatly improved.

The invention discloses an over-current control method and system for an alternating-current parallel hybrid converter and the converter, and relates to the technical field of high-voltage direct-current power transmission. The over-current control method comprises the following steps: controlling the voltage source converter to perform first temporary locking under the condition that the bridge arm current of at least one phase of the voltage source converter is detected to be greater than a first current threshold value and lasts for a first time threshold value; and / or under the condition that the bridge arm current of at least one phase of the voltage source converter is detected to be greater than a second current threshold value and lasts for a second time threshold value, controlling the voltage source converter to be secondarily temporarily locked, and controlling the current source converter to switch a bypass pair and / or shift phase. When the bridge arm current of the voltage source converter exceeds the device limit value, the voltage source converter is controlled to be temporarily locked, and meanwhile, the current source converter is controlled to switch the bypass pair and / or the phase shift, so that the current flowing into the voltage source converter from the current source converter is quickly inhibited, and the bridge arm current of the voltage source converter is inhibited from continuously increasing; and the reliability of the converter is improved.

The application provides a hybrid DC power transmission system, a control method of the system and a hybrid DC power transmission device. The system comprises a sending-end converter and a receiving-end converter for electrical connection with an AC bus. The sending-end converter comprises a positive converter and a negative converter. The positive converter is used for electrical connection with a positive pole of a DC line, and the negative converter is used for electrical connection with a negative pole of the DC line. The positive converter comprises a fully-controlled current source converter. The negative converter comprises a modular multi-level converter and / or a controllable commutation current source converter. The positive converter and the negative converter both comprise fully-controlled devices. The receiving-end converter is electrically connected with the sending-end converter through the DC line, and is a converter controlled by a DC voltage. The system is a hybrid HVDC power transmission system adopting a CCSC and an HCC / MMC at the sending end, and realizes 100% new energy sending out of the AC bus.