56 results about "Current source converter" patented technology

Provided in the present disclosure are a converter system of a wind turbine generator system, and a wind turbine generator system and an offshore wind farm. The converter system comprises: a voltage source converter and a current source converter; and a converter control apparatus, which is configured to control the operation of the voltage source converter and the current source converter by means of taking into account an internal circulating current of a wind turbine generator system in voltage outer-loop control of the voltage source converter and by means of taking into account the internal circulating current in active and reactive power control stages of the current source converter.

The invention provides a control method, device, circuit and equipment of a current source type converter and a medium, and belongs to the technical field of converters. The method comprises the following steps: detecting a direct-current voltage output by a current source type converter; when the direct-current voltage is greater than the direct-current upper limit threshold value, a plurality of controllable switching devices in the current source type converter are controlled to be switched off, so that a charging loop of a direct-current bus capacitor in the current source type converter is switched off; and when the direct current voltage is smaller than the first direct current lower limit threshold value, determining a driving control signal, and controlling a plurality of controllable switching devices in the current source type converter based on the driving control signal. According to the invention, the plurality of controllable switching devices are controlled to be switched off and stop charging the bus capacitor, and in the process, the bus capacitor charges the load all the time so as to reduce the DC voltage, thereby reducing the possibility of DC overvoltage protection events and load safety threat events, and improving the stability and safety of load operation.

The invention provides a control method, device, circuit and equipment of a current source type converter and a medium, and belongs to the technical field of converters. The method comprises the steps of determining a maximum phase, a minimum phase and an intermediate phase based on current voltages of three phases in a three-phase alternating current; determining a first duty ratio corresponding to the maximum phase based on the current voltage of the maximum phase; determining a second duty ratio corresponding to the intermediate phase based on the current voltage of the intermediate phase; based on the second duty ratio corresponding to the intermediate phase, a third duty ratio corresponding to the minimum phase is determined, and the minimum phase and the intermediate phase complement each other; and based on the current three-phase voltage, the first duty ratio, the second duty ratio and the third duty ratio, controlling a plurality of controllable switching devices in the current source type converter to be switched on or switched off. According to the invention, the voltage stress is reduced, and the EMI performance is improved.

The invention provides an alternating-current parallel hybrid converter type direct-current power transmission system and a control method and device, and relates to the technical field of high-voltage direct-current power transmission. The AC parallel hybrid converter type DC power transmission system includes: a first AC parallel hybrid converter and a second AC parallel hybrid converter, the first AC parallel hybrid converter and the second AC parallel hybrid converter each including: a current source converter including a six-pulse bridge circuit; the voltage source converter and the current source converter are connected in parallel on the alternating current side; one side is connected with the alternating current side of the voltage source converter, and the other side is connected with an alternating current system. According to the alternating-current parallel hybrid converter type direct-current power transmission system, 6k + / -1 harmonic waves are filtered out through a voltage source converter, a six-pulse bridge circuit is directly adopted in the high-voltage direct-current power transmission system, the converter structure of the high-voltage direct-current power transmission system is simplified, operation flexibility is improved, and the capacity of suppressing commutation failure is achieved.

The invention provides an offshore wind power direct current sending-out system structure based on an S7 bridge arm current source converter and a control method of the offshore wind power direct current sending-out system structure. The topological characteristic provided by the invention is that an S7 bridge arm is connected in parallel with the direct current side of the 6-pulse CSC, and the switch of the S7 bridge arm and the switch of each bridge arm of the 6-pulse CSC are distributed, so that multi-active and multi-reactive independent control is realized. The active quantity of the land CSC is controlled by constant direct current voltage, and the reactive quantity of the land CSC is controlled by reactive power. When the collected submarine cable has a fault, the S7CSC reduces the reference value of the AC bus and reduces the current fed by the CSC to a fault point, thereby preventing fault transient overcurrent and realizing fault ride-through. The technical scheme provided by the invention has the advantages that: S7CSC has two control degrees of freedom, can realize independent control of active components and reactive components, stabilizes the offshore AC voltage and frequency, can adapt to the fluctuation of wind power output, effectively inhibits the increase of fault current at the offshore AC collection fault, and realizes fault ride-through.

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.

The invention relates to the technical field of high-voltage direct-current power transmission, discloses a hybrid cascade direct-current fault disturbed coordination system based on a turn-off current source converter, and belongs to the technical field of high-voltage direct-current power transmission. A receiving-end high-end power grid commutation converter is replaced by a turn-off current source converter, and an active energy consumption mechanism of a lightning arrester is combined, so that control cooperation is realized; a main branch of the turn-off current source converter is formed by connecting a thyristor and a full-control device in series, and an auxiliary branch is connected with a metal oxide lightning arrester in parallel. When a fault occurs, the control unit actively turns off the main branch IGBT, the fault current is switched to the auxiliary branch, the lightning arrester is utilized to establish a reverse commutation voltage and rapidly discharge energy, and the direct current and voltage fluctuation of the low-end MMC is inhibited. The method has the advantages that the commutation failure risk is eliminated, the MMC locking probability is reduced, and the energy loss is reduced, the hybrid direct-current power drop during the fault period is reduced, and the method has remarkable engineering application value.

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 present application relates to a method for regulating reactive power of a current source converter with active commutation. When it is detected that the operating states of the DC power transmission system and the AC system connected to the DC power transmission system meet the preset judgment conditions, first control the current source converter with active commutation to be in the target active power mode, then determine the target reactive power to be adjusted when the current source converter with active commutation is in the active power mode, and obtain the target mapping relationship corresponding to the target active power mode. Finally, according to the target reactive power and the target mapping relationship, adjust the tap position of the converter transformer so that the reactive power exchanged between the current source converter with active commutation and the AC system connected to the current source converter with active commutation reaches the target reactive power. The above method can avoid the problem of active power change caused by directly adjusting the trigger angle or turn-off angle of the current source converter with active commutation in the prior art.

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.

The invention provides a fault ride-through energy consumption device which is suitable for a current source converter (CSC) open sea wind power output system. In a CSC-based open-sea wind power output system, when an onshore alternating current system breaks down, direct current voltage on an inverter side is reduced, transmittable power is greatly reduced, direct current voltage on a sea side is basically kept unchanged, a voltage difference is generated in a direct current loop, and transient overcurrent occurs on a direct current line. The energy consumption device provided by the invention can solve the problem, the resistor in the energy consumption device consumes surplus power and limits the increase of direct current overcurrent, and meanwhile, by utilizing the characteristic that the inductor passes through low frequency and resists high frequency, the direct current is converted into high-frequency alternating current through the full-control switch, so that the purpose of limiting the direct current by the inductor is achieved. The energy consumption device provided by the invention can consume the fault surplus power, achieves the suppression of overcurrent, reduces the configuration number of the energy consumption device, and solves the cooling problem.

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 invention discloses a current balance control method for a multi-level current source converter, which belongs to the field of power conversion and comprises the following steps of: decomposing common-mode and differential-mode components of direct-current side current of N units, performing closed-loop control on the differential-mode component of each unit by adjusting the component in the same phase as the alternating-current capacitor voltage in the alternating-current side current reference signal of the converter of each unit, so that the differential-mode component approaches to the total direct current / N; a zero vector for increasing common-mode current and a zero vector for reducing common-mode current are introduced into a switch sequence of each unit according to a voltage sector, and closed-loop control is performed on a common-mode component of each unit by adjusting an action time distribution proportion of the two zero vectors, so that the common-mode component approaches 0; meanwhile, balance of direct-current side differential mode current between the units and balance of upper and lower inductive current in the units are achieved. According to the method, processing of a large number of redundant vectors and a complex sorting algorithm is avoided, the current sharing local failure phenomenon is avoided, the requirement for the real-time performance of the controller is lowered, and the additional increase of the switching frequency is reduced.

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.

The invention provides a power estimation method and system for a turn-off current source converter, and the method comprises the steps: obtaining a forced commutation angle through the derivation of a trigger angle and a natural commutation angle in a commutation process; based on the forced commutation angle, the AC secondary side voltage and the commutation transformer impedance, obtaining the current of each time period in the commutation process; and on the basis of the current value, using an approximate linearization processing method, and adopting Fourier analysis to obtain the power of the current source converter capable of being turned off. According to the method, the direct current voltage and the alternating current are obtained by analyzing different stages of the commutation process, the fundamental frequency active current and the fundamental frequency reactive current are obtained by utilizing an approximate linearization processing method and adopting Fourier analysis, estimation is more accurate, the accuracy of the control process is improved, the reactive supporting capacity of the current converter is accurately quantified, and a theoretical basis is provided for developing BPA software.

A synchronous reverse blocking switch for a soft-switching current source converter (SSCSC), the switch comprising: a first controlled switch; a second controlled switch connected in series to the first controlled switch; and a delay generation circuit configured to control: the second controlled switch to turn on after a delay (t_dON) from the first controlled switch turning on, and the second controlled switch to turn off after a delay (t_dOFF) from the first controlled switch turning off.