CN111521946A - Cascaded converter submodule working condition simulation system and current control method thereof - Google Patents

Cascaded converter submodule working condition simulation system and current control method thereof Download PDF

Info

Publication number
CN111521946A
CN111521946A CN202010337959.XA CN202010337959A CN111521946A CN 111521946 A CN111521946 A CN 111521946A CN 202010337959 A CN202010337959 A CN 202010337959A CN 111521946 A CN111521946 A CN 111521946A
Authority
CN
China
Prior art keywords
voltage
current
controller
signal
bridge arm
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
CN202010337959.XA
Other languages
Chinese (zh)
Inventor
马柯
李恩溢
蔡旭
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shanghai Jiaotong University
Original Assignee
Shanghai Jiaotong University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shanghai Jiaotong University filed Critical Shanghai Jiaotong University
Priority to CN202010337959.XA priority Critical patent/CN111521946A/en
Publication of CN111521946A publication Critical patent/CN111521946A/en
Priority to CN202010942352.4A priority patent/CN111965468B/en
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B11/00—Automatic controllers
    • G05B11/01—Automatic controllers electric
    • G05B11/36—Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential
    • G05B11/42—Automatic controllers electric with provision for obtaining particular characteristics, e.g. proportional, integral, differential for obtaining a characteristic which is both proportional and time-dependent, e.g. P.I., P.I.D.
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B13/00—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion
    • G05B13/02—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric
    • G05B13/04—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators
    • G05B13/042—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators in which a parameter or coefficient is automatically adjusted to optimise the performance
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
    • H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
    • H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
    • H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
    • H02M1/007—Plural converter units in cascade
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

The invention provides a control method of a working condition simulation system of a cascaded converter submodule, wherein the system comprises the following steps: the system comprises a system parameter model, a current generator, an object to be detected, a port voltage sampler, a low-pass filter, a current controller and a voltage controller. The method comprises the steps of compensating feed-forward voltage in a current controller, offsetting pulse voltage interference of a port of an object to be detected, specifically, sampling a voltage signal of the port of the object to be detected, carrying out low-pass filtering on the voltage signal, compensating the filtered signal to an output end of a controller of a current generator, offsetting the interference of the pulse voltage of the port of the object to be detected on the controller, and accordingly suppressing bridge arm current distortion in the cascaded converter to be detected. The working condition simulation system of the cascaded converter submodule and the current control method thereof can better realize the working condition simulation of the cascaded converter submodule based on the nearest level approximation modulation.

Description

Cascaded converter submodule working condition simulation system and current control method thereof
Technical Field
The invention relates to the technical field of power electronics, in particular to a working condition simulation system (simulation test circuit) of a cascaded converter submodule and a current control method thereof.
Background
In recent years, the cascade converter is widely applied to medium-high voltage power transmission occasions by virtue of the characteristics of modularization, easiness in expansion and the like. With the continuous improvement of the capacity and the voltage grade of the cascaded converter, the evaluation and the detection of the reliability of the cascaded converter in the operation process are concerned more and more widely. In the early stage, in order to evaluate and detect the reliability of the cascaded converter, a complete cascaded converter system is often required to be built, but the reliability of the cascaded converter mainly depends on the reliability of a cascaded converter submodule, so that the reliability of the cascaded system is evaluated through a cascaded converter submodule working condition simulation test circuit, and the method becomes a more efficient and cost-saving method.
At present, the modulation method of the cascaded converter is mainly the nearest level approximation modulation method. Under the modulation method, the pulse voltage output by the submodule of the cascade converter has the characteristics of large pulse amplitude, wide pulse width and the like, and the submodule can be turned on or turned off for a long time, so that the pulse voltage of the submodule generates large interference on a current controller, and the current controller is difficult to stably control the current.
In a traditional cascading converter submodule working condition simulation test circuit based on recent level approximation modulation, in order to eliminate the influence of submodule output pulse voltage, an additional auxiliary circuit is generally required to be added, and the auxiliary circuit and the submodule are controlled to cooperatively operate, so that the interference of submodule pulse voltage on a current controller is counteracted. The additional control circuitry adds complexity to the control and cost of manufacturing the analog test circuitry. Therefore, a simpler and more cost-effective system for simulating the working conditions of the submodule of the cascaded converter and a corresponding current control method are needed.
At present, no explanation or report of the similar technology of the invention is found, and similar data at home and abroad are not collected.
Disclosure of Invention
The invention provides a working condition simulation system of a cascaded converter submodule and a current control method thereof, aiming at the problems in the prior art.
The invention is realized by the following technical scheme.
According to one aspect of the invention, a system for simulating the working condition of the cascaded converter submodule is provided, which comprises:
and the system parameter model outputs a reference current signal and a reference voltage signal to the current controller and the voltage controller according to the bridge arm current, the bridge arm voltage and the capacitance voltage of the actual cascade converter to be simulated.
The current generator is used for receiving the switching sequence input by the current controller and outputting bridge arm current required by the working condition simulation system;
the object to be tested comprises an inversion type sub-module group to be tested and a rectification type sub-module group to be tested of a cascade type converter, wherein the inversion type sub-module group and the rectification type sub-module group to be tested are respectively composed of a plurality of sub-modules working in an inversion state and a rectification state, and are connected with the current generator in series in a main circuit of the working condition simulation system, and the inversion type sub-module group and the rectification type sub-module group are respectively used for receiving bridge arm current input by the current generator and a switch sequence input by the voltage controller and outputting capacitance voltage signals of sub-modules in the current;
the voltage sampler is used for sampling voltage difference signals of ports of the two sub-module groups to be tested, namely voltage difference signals between a node 1 and a node 2, and outputting the voltage difference signals obtained by sampling;
the low-pass filter receives the voltage difference signal input by the port voltage sampler, performs low-pass filtering on the received voltage difference signal, and outputs the filtered voltage difference signal to the current controller;
the current controller receives a bridge arm current signal input by the current generator, receives a filtered voltage difference signal of the ports of the two sub-module groups to be tested, namely a filtered voltage difference signal between a node 1 and a node 2, input by the low-pass filter, receives a reference current signal input by the system parameter model, and outputs a switching sequence for controlling the current generator through a controller and a modulator link so that the bridge arm current in the system to be tested tracks the reference current signal;
and the voltage controller receives a capacitance voltage signal of a submodule of the object to be detected, receives a bridge arm current signal actually input by the current generator, receives a reference voltage signal input by the system parameter model, and outputs a switch sequence for controlling the submodule to be detected, so that the submodule capacitance voltage in the two submodule groups of the object to be detected tracks the reference voltage signal.
Preferably, the voltage modulation method of the cascaded converter submodule condition simulation system includes, but is not limited to: nearest Level approximation Modulation (NLC) and Carrier phase shift Modulation (Carrier phase shift-singular Pulse Width Modulation).
Preferably, the current generator comprises a direct-current power supply and a controllable full-bridge or half-bridge type switch circuit, and the bridge arm current in the working condition simulation system is controlled by controlling the on-off of the full-bridge or half-bridge circuit.
Preferably, in the object to be tested, the number of the sub-modules included in the sub-module groups to be tested of the inverter type and the rectification type is adjusted within the total number of the sub-modules of a single bridge arm of the simulated actual cascaded converter according to actual needs, and the number of the sub-modules included in the sub-module groups to be tested of the inverter type and the rectification type is not necessarily equal; meanwhile, the circuit structures of the neutron modules of the inversion type and rectification type objects to be detected can be selected from a full-bridge structure or a half-bridge structure.
Preferably, the cut-off frequency of the low-pass filter is selected from 1/10 to 1/100 of the frequency of the high-frequency voltage pulse, because the dead zone of the switch of the sub-module to be tested and the current generator will cause the voltage signal sampled by the voltage sampler to have the high-frequency voltage pulse.
Preferably, the low-pass filter can be implemented by means of an analog circuit or a digital circuit.
Preferably, the control method in the current controller adopts proportional-integral Resonance (PIR) control, and the modulation method adopts Sinusoidal Pulse Width Modulation (SPWM).
Preferably, the method for the voltage controller to output the switching sequence is as follows: sampling the capacitance voltage of all sub-modules in an object to be detected, subtracting the capacitance voltage reference signal in the voltage reference signal from the obtained average value of the capacitance voltage of the inversion type sub-module to be detected and the rectification type sub-module to be detected, inputting the difference value into a proportional integral regulator (PI), compensating the output of the proportional integral regulator to a bridge arm voltage reference signal in the voltage reference signal, and finally generating a switch sequence through an NLC (nearest level approximation modulation) or CPS-PWM (carrier phase shift modulation) according to the compensated modulation voltage so as to control the capacitance voltage of all sub-modules in the object to be detected.
According to another aspect of the invention, a current control method of any one or more cascaded converter submodule working condition simulation systems is provided, wherein pulse voltage interference of a port of an object to be measured is counteracted by compensating feed-forward voltage in a current controller; the method comprises the following steps:
the voltage difference signal of the port of the object to be detected, namely the voltage difference signal between the node 1 and the node 2, is sampled by the voltage sampler, and after the sampled voltage difference signal is subjected to low-pass filtering, the sampled voltage difference signal is compensated to the output end of the proportional-integral resonance regulator of the current controller, so that the interference of the pulse voltage of the port of the object to be detected on the proportional-integral resonance regulator is counteracted, and the current distortion caused by the pulse voltage interference is suppressed.
Preferably, the current control method according to claim 8, wherein in the method for compensating the feedforward voltage in the current controller to counteract the impulse voltage disturbance of the measured object, the control process expression is:
Figure BDA0002467312050000031
in the formula (I), the compound is shown in the specification,
Figure BDA0002467312050000032
for bridge arm current reference values, i, flowing into submodulesarmFor the bridge arm current signal, Δ i is the difference between the reference value of the bridge arm current and the bridge arm current signal, uPIRIs the output value of the proportional-integral resonance regulator, u'DUTIs a low-pass filtered voltage signal u across the object to be measuredmModulating current for current generatorPressure, omega1Is the current frequency one, omega2Current frequency of two, KPiIs a proportional control coefficient of a current controller, KIiIs an integral control coefficient of a current controller, Kri1A resonance control coefficient, K, corresponding to a current frequency one for the current controllerri2And the resonance control coefficient of the current controller corresponding to the current frequency II.
Compared with the prior art, the invention has the following beneficial effects:
the working condition simulation system of the cascaded converter submodule and the current control method thereof provided by the invention directly offset the interference of the submodule pulse voltage to the current controller in a mode of compensating the feedforward voltage without adding an additional auxiliary circuit, thereby reducing the complexity of control, saving the manufacturing cost of an analog circuit and being a valuable technical improvement.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
fig. 1 is a schematic structural diagram of a working condition simulation system of a cascaded converter submodule provided in a preferred embodiment of the present invention;
fig. 2 is a schematic diagram of a topology structure of a main circuit in a working condition simulation system of a cascaded converter sub-module according to a preferred embodiment of the present invention;
FIG. 3 is a schematic block diagram of a current controller in a condition simulation system of a cascaded converter sub-module according to a preferred embodiment of the present invention;
fig. 4 is a block diagram of a current control loop of a working condition simulation system of a cascaded converter submodule according to a preferred embodiment of the present invention;
fig. 5 is a schematic block diagram of a voltage controller in a working condition simulation system of a cascaded converter submodule provided in a preferred embodiment of the present invention;
in the figure: 1-a current generator; 2-an object to be measured; 3-a current controller; a 4-port voltage sampler; 5-a low-pass filter; 6-a voltage controller; 7-system parameter model.
Detailed Description
The following examples illustrate the invention in detail: the embodiment is implemented on the premise of the technical scheme of the invention, and a detailed implementation mode and a specific operation process are given. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.
The embodiment of the invention provides a working condition simulation system for a cascaded converter submodule. Fig. 1 is a schematic structural diagram of a working condition simulation system (referred to as a simulation test circuit for short) of a cascaded converter sub-module according to an embodiment of the present invention. The method comprises the following steps:
and the system parameter model 7 outputs a reference current signal and a reference voltage signal to the current controller and the voltage controller according to the bridge arm current, the bridge arm voltage and the capacitor voltage of the actual cascaded converter to be simulated.
The current generator 1 is used for receiving a switching sequence input by the current controller and outputting bridge arm current required by the working condition simulation system;
the object to be tested 2 comprises an inversion type sub-module group to be tested and a rectification type sub-module group to be tested of the cascade type converter, the inversion type sub-module group and the rectification type sub-module group to be tested are respectively composed of a plurality of sub-modules working in an inversion state and a rectification state, the inversion type sub-module group and the rectification type sub-module group to be tested are connected with the current generator in series in a main circuit of the working condition simulation system, and the inversion type sub-module group and the rectification type sub-module group are respectively used for receiving bridge arm current input by the current generator and a switch sequence input;
the port voltage sampler 4 is used for sampling the voltage difference signals of the ports of the two sub-module groups to be tested and outputting the voltage difference signals obtained by sampling;
a low pass filter 5 receiving the voltage difference signal input by the port voltage sampler, performing low pass filtering on the received voltage difference signal, and outputting the filtered voltage difference signal to the current controller;
the current controller 3 receives a bridge arm current signal input by the current generator, a filtered voltage difference signal input by the low-pass filter and a reference current signal input by the system parameter model, and outputs a switching sequence for controlling the current generator through a controller and a modulator link so that the bridge arm current in the system to be tested tracks the reference current signal;
and the voltage controller 6 is used for receiving the capacitance voltage signal of the submodule of the object to be detected, the bridge arm current signal actually input by the current generator and the reference voltage signal input by the system parameter model, and outputting a switch sequence for controlling the submodule to be detected, so that the submodule capacitance voltage in the two submodule groups of the object to be detected tracks the reference voltage signal.
Further, the voltage modulation method of the cascaded converter submodule working condition simulation system comprises but is not limited to: nearest Level approximation Modulation (NLC) and carrier phase Shift Modulation (CPS-PWM).
Further, the current controller receives the current reference signal, the bridge arm current signal and the voltage difference signal at the two ends of the sub-module group to be tested after low-pass filtering, and outputs a switching sequence to control the current generator to output the required current. Therefore, the bridge arm current in the working condition simulation system is the same as the simulated bridge arm current in the actual cascaded converter system.
Further, the current controller specifically works in a process that the current controller inputs a difference value between the read bridge arm reference current signal and the sampled bridge arm current signal in the working condition simulation system into a Proportional Integral Resonance (PIR) controller, then compensates the read voltage signals at two ends of the sub-module to be tested after low-pass filtering to an output end of the PIR controller, and finally generates a corresponding switch sequence through SPWM modulation according to the compensated modulation voltage to control the current generator.
Further, the voltage controller receives the capacitance voltage signal and the bridge arm current signal of the submodule group to be tested, as well as the capacitance voltage reference value and the bridge arm voltage reference value of the simulated system, and outputs the switch signal of the submodule group to be tested based on a nearest level approximation modulation method.
Further, the specific working process of the voltage controller is to sample the capacitance voltage signals of all the sub-modules in the object to be measured and input the capacitance voltage signals into the voltage controller. In the voltage controller, making a difference between a capacitance voltage reference value and a read average value of the capacitance voltage of the inversion and rectification type sub-module group to be detected, inputting the difference value into a proportional-integral regulator, compensating the output of the proportional-integral regulator to a bridge arm voltage reference value, and finally generating a switch sequence according to the compensated modulation voltage by a modulation method of nearest level approximation so as to control the sub-module in the object to be detected.
Further, the current generator comprises a direct-current power supply and a controllable full-bridge or half-bridge type switch circuit, and the bridge arm current in the working condition simulation system is controlled by controlling the on-off of the full-bridge or half-bridge circuit.
Furthermore, the object to be measured consists of an inversion type sub-module group to be measured and a rectification type sub-module group to be measured, and the two sub-module groups to be measured respectively consist of a plurality of sub-modules to be measured which work in inversion and rectification states.
Further, the system parameter simulation gives a reference current and a reference voltage of a working condition simulation system of the cascade type converter according to a bridge arm current, a bridge arm voltage and a capacitance voltage of the actual cascade type converter.
In this embodiment, the constructed working condition simulation system is used for simulating the working condition of the neutron module of the actual cascaded converter, so that the electrical characteristics of the submodule to be tested (i.e. the object to be tested) in the working condition simulation system are the same as those of the submodule in the actual cascaded converter, and the working condition of the neutron module of the actual cascaded converter can be evaluated through the constructed working condition simulation system.
In this embodiment, the voltage modulation method of the working condition simulation system of the Cascaded Converter sub-module may adopt, but is not limited to, a Nearest Level approximation modulation (NLC) method, and may simulate, but is not limited to, a Cascaded Converter, and the simulated sub-module structure includes, but is not limited to, a half Bridge, a full Bridge Modular Multilevel Converter (MMC), and a Cascaded H-Bridge Converter (CHB).
In this embodiment, the voltage controller receives the capacitance voltage signal and the bridge arm current signal of the object to be measured, and the capacitance voltage reference value and the bridge arm voltage reference value of the simulated system, and outputs the switching signal of the object to be measured based on the nearest level approximation modulation method.
Specifically, the capacitance voltage signals of all the sub-modules in the object 2 to be measured are sampled and input to the voltage controller 6. As shown in fig. 5, in the voltage controller, the capacitance voltage reference value is subtracted from the average value of the capacitance voltages read from the sub-module groups to be tested of the inverter type and the rectifier type, the difference value is input into the proportional-integral regulator, the output of the proportional-integral regulator is compensated to the bridge arm voltage reference value, and finally the object to be tested 2 is controlled by a modulation method of nearest level approximation, and the control process can be expressed by a formula as follows:
Figure BDA0002467312050000071
the formula corresponding to the rectification type sub-module group to be tested is as follows:
Figure BDA0002467312050000072
wherein n is the number of all sub-modules in the object to be tested, ucinv_iAnd ucrec_iRespectively are capacitance voltage signals of the ith sub-module in the inversion model sub-module group to be tested and the rectification model sub-module group to be tested,
Figure BDA0002467312050000073
and
Figure BDA0002467312050000074
respectively is the average value of capacitance voltage signals of i sub-modules in the inversion model sub-module group to be tested and the rectification model sub-module group to be tested,
Figure BDA0002467312050000075
and
Figure BDA0002467312050000076
respectively is a sub-module capacitance voltage reference value, delta u, in the inversion type sub-module group to be tested and the rectification type sub-module group to be testedinvAnd Δ urecDifference value u between the capacitor voltage reference value in the inversion type sub-module to be tested and the average value of the sub-module capacitor voltage signals in the rectification type sub-module to be testedPI_invAnd uPI_recRespectively output signals of proportional-integral regulators in the inversion model sub-module to be tested and the rectification model sub-module to be tested,
Figure BDA0002467312050000077
and
Figure BDA0002467312050000078
the reference values u of bridge arm voltages in the inverter model sub-module group to be tested and the rectifier model sub-module group to be testedm_invAnd um_recThe modulation voltage value K used for nearest level approximation in the inverter model sub-module to be tested and the rectifier model sub-module to be testedPuIs a proportional control coefficient of a voltage controller, KIuIs the integral control coefficient of the voltage controller. It should be noted that, the difference between the simulated system capacitor voltage reference value and the capacitor voltage of the object to be measured needs to be compensated to the bridge arm voltage reference value through the proportional-integral regulator, because the total charge and discharge amounts of the sub-module voltages in one period may not be completely equal in the operating process of the working condition simulation system, which may cause the capacitor voltage average value of the sub-modules to continuously increase or decrease, and therefore, the deviation value between the capacitor voltage and the reference capacitor voltage needs to be compensated to stabilize the capacitor voltage of the sub-modules.
Based on the working condition simulation system of the cascaded converter submodule provided by the embodiment of the invention, the embodiment of the invention also provides a current control method of the working condition simulation system of the cascaded converter submodule, and the pulse voltage interference of an object to be measured is counteracted by a method of compensating feedforward voltage for a current controller;
the method for compensating the feedforward voltage to offset the voltage interference comprises the steps of reading voltage signals at two ends of a submodule group to be tested of a cascade converter submodule working condition simulation system, compensating the sampled voltage signals to the output end of a proportional-integral resonance regulator of a current controller after low-pass filtering the sampled voltage signals, offsetting the interference of pulse voltage at two ends of the submodule group to be tested to the proportional-integral resonance regulator, and inhibiting current distortion caused by pulse voltage interference.
The method for compensating the feedforward voltage to counteract the voltage disturbance can be applied to, but is not limited to, the nearest level approximation modulation method. When a recent level approximation modulation method is adopted in a cascade type converter submodule working condition simulation system, a switch dead zone can cause voltage signals at two ends of a submodule group to be detected to generate high-frequency voltage pulses, the pulse width of the high-frequency pulses is extremely narrow, the interference on a current controller is very small, if the high-frequency voltage pulses are sampled and compensated to the current controller, the current controller is subjected to larger interference due to the delay of the compensated high-frequency pulse voltage and the actual high-frequency pulse voltage, and therefore after the voltages at two ends of the submodule group to be detected are obtained through sampling, low-pass filtering is conducted on the sampled signals through a low-pass filter, and therefore the high-frequency pulse voltage is eliminated in compensation voltage.
Specifically, the voltage sampler 4 samples a voltage signal between ports of an object to be measured, that is, between the node 1 and the node 2 in fig. 2, inputs the sampled voltage signal into the low-pass filter 5 for filtering, compensates the filtered voltage signal to the output end of the proportional-integral resonance controller in the current controller, and finally performs Sinusoidal Pulse Width Modulation (SPWM) according to the compensated controller signal to output a corresponding switch sequence for controlling the current generator 1. The whole control process can be expressed by the following formula:
Figure BDA0002467312050000081
wherein the content of the first and second substances,
Figure BDA0002467312050000082
for bridge arm current reference values, i, flowing into submodulesarmFor the bridge arm current signal, Δ i is the difference between the reference value of the bridge arm current and the bridge arm current signal, uPIRIs the output value of the proportional-integral resonance regulator, u'DUTIs a low-pass filtered voltage signal u across the object to be measuredmIs the modulation voltage, omega, of a current generator1Is the current frequency one, omega2Current frequency of two, KPiIs a proportional control coefficient of a current controller, KIiIs an integral control coefficient of a current controller, Kri1Is the resonance control coefficient, K, of the current controller corresponding to the current frequency oneri2And the resonance control coefficient is the resonance control coefficient of the current controller corresponding to the power frequency two.
The block diagram of the whole bridge arm current control loop is shown in fig. 4, and it can be obviously seen that after the compensation voltage is added, the influence of the pulse voltage at two ends of the object to be detected on the current control loop is counteracted by the compensation voltage, so that the interference of the pulse voltage can be inhibited, and the reference current can be stably tracked. It should be noted here that the low-pass filtering of the sampled voltage signals at the two ends of the object to be measured is required because there may be high-frequency voltage pulses at the two ends, and the pulse width of such pulses is very narrow, and thus the interference to the current controller is very small, but if these high-frequency voltage pulses are sampled and compensated to the current controller, the current controller is more interfered by the delay between the compensated high-frequency pulse voltage and the actual high-frequency pulse voltage (the delay is determined by the sampling frequency of the voltage sampler), and therefore the low-pass filtering of the sampled pulse voltages at the two ends of the object to be measured is required.
Compared with the current control method applied in the conventional cascading type converter submodule working condition simulation system, the current control method provided by the embodiment of the invention directly offsets the interference of submodule pulse voltage on a current controller by a method of compensating feedforward voltage without adding an additional auxiliary circuit, thereby reducing the control complexity, saving the manufacturing cost of the working condition simulation system and being a valuable technical improvement.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.

Claims (10)

1. A working condition simulation system for cascaded converter sub-modules is characterized by comprising:
and the system parameter model outputs a reference current signal and a reference voltage signal to the current controller and the voltage controller according to the bridge arm current, the bridge arm voltage and the capacitance voltage of the actual cascade converter to be simulated.
The current generator is used for receiving the switching sequence input by the current controller and outputting bridge arm current required by the working condition simulation system;
the object to be tested comprises an inversion type sub-module group to be tested and a rectification type sub-module group to be tested of a cascade type converter, wherein the inversion type sub-module group and the rectification type sub-module group to be tested are respectively composed of a plurality of sub-modules working in an inversion state and a rectification state, and are connected with the current generator in series in a main circuit of the working condition simulation system, and the inversion type sub-module group and the rectification type sub-module group are respectively used for receiving bridge arm current input by the current generator and a switch sequence input by the voltage controller and outputting capacitance voltage signals of sub-modules in the current;
the port voltage sampler is used for sampling voltage difference signals of the ports of the two sub-module groups to be tested and outputting the voltage difference signals obtained by sampling;
the low-pass filter receives the voltage difference signal input by the port voltage sampler, performs low-pass filtering on the received voltage difference signal, and outputs the filtered voltage difference signal to the current controller;
the current controller receives a bridge arm current signal input by the current generator, a filtered voltage difference signal input by the low-pass filter and a reference current signal input by the system parameter model, and outputs a switching sequence for controlling the current generator through the controller and the modulator link so that the bridge arm current in the system to be tested tracks the reference current signal;
and the voltage controller receives a capacitance voltage signal of a submodule of the object to be detected, a bridge arm current signal actually input by the current generator and a reference voltage signal input by the system parameter model, and outputs a switch sequence for controlling the submodule to be detected, so that the submodule capacitance voltage in the two submodule groups of the object to be detected tracks the reference voltage signal.
2. The cascaded converter submodule working condition simulation system of claim 1, wherein a voltage modulation method of the cascaded converter submodule working condition simulation system comprises the following steps: nearest level approximation modulation and carrier phase shift modulation.
3. The system of claim 1, wherein the current generator comprises a dc power supply and a controllable full-bridge or half-bridge switching circuit, and the bridge arm current in the system is controlled by controlling the on/off of the full-bridge or half-bridge switching circuit.
4. The cascaded converter submodule working condition simulation system of claim 1, wherein in the object to be tested, the number of submodules included in the inversion and rectification submodule groups to be tested is adjusted within the total number of submodules of a single bridge arm of the simulated actual cascaded converter according to actual needs; and/or
The circuit structure of the neutron module of the inversion type and the rectification type to-be-detected object adopts a full-bridge structure or a half-bridge structure.
5. The cascaded converter submodule condition simulation system of claim 1, wherein a cut-off frequency of the low-pass filter is selected to be 1/10 to 1/100 of a high-frequency voltage pulse frequency.
6. The cascaded converter submodule condition simulation system of claim 1, wherein the low-pass filter is implemented by means of an analog circuit or a digital circuit.
7. The cascaded converter submodule condition simulation system of claim 1, wherein a control method in the current controller adopts proportional-integral resonance control, and a modulation method adopts sinusoidal pulse width modulation.
8. The cascaded converter submodule condition simulation system of claim 1, wherein the method for the voltage controller to output the switching sequence is as follows:
sampling the capacitance voltages of all sub-modules in an object to be detected, subtracting the capacitance voltage reference signal in the voltage reference signal from the obtained average value of the capacitance voltages of the inversion type sub-module group to be detected and the rectification type sub-module group to be detected, inputting the difference value into a proportional-integral regulator, compensating the output of the proportional-integral regulator to a bridge arm voltage reference signal in the voltage reference signal, and finally generating a switch sequence by a nearest level approximation modulation method or a carrier phase shift modulation method according to the compensated modulation voltage so as to control the capacitance voltages of all sub-modules in the object to be detected.
9. A current control method of a cascade converter submodule working condition simulation system is characterized in that pulse voltage interference of a port of an object to be measured is counteracted by compensating feedforward voltage in a current controller; the method comprises the following steps:
the voltage difference signal of the port of the object to be detected is sampled by the voltage sampler, and after the sampled voltage difference signal is subjected to low-pass filtering, the sampled voltage difference signal is compensated to the output end of the proportional-integral resonance regulator of the current controller, so that the interference of the pulse voltage of the port of the object to be detected on the proportional-integral resonance regulator is counteracted, and the current distortion caused by the pulse voltage interference is suppressed.
10. The current control method according to claim 9, wherein in the method for compensating the feedforward voltage in the current controller to cancel the impulse voltage disturbance of the measured object, the control process expression is:
Figure FDA0002467312040000021
in the formula (I), the compound is shown in the specification,
Figure FDA0002467312040000022
for bridge arm current reference values, i, flowing into submodulesarmFor the bridge arm current signal, Δ i is the difference between the reference value of the bridge arm current and the bridge arm current signal, uPIRIs the output value of the proportional-integral resonance regulator, u'DUTIs a low-pass filtered voltage signal u across the object to be measuredmIs the modulation voltage, omega, of a current generator1Is the current frequency one, omega2Current frequency of two, KPiIs a proportional control coefficient of a current controller, KIiIs an integral control coefficient of a current controller, Kri1A resonance control coefficient, K, corresponding to a current frequency one for the current controllerri2And the resonance control coefficient of the current controller corresponding to the current frequency II.
CN202010337959.XA 2020-04-26 2020-04-26 Cascaded converter submodule working condition simulation system and current control method thereof Withdrawn CN111521946A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN202010337959.XA CN111521946A (en) 2020-04-26 2020-04-26 Cascaded converter submodule working condition simulation system and current control method thereof
CN202010942352.4A CN111965468B (en) 2020-04-26 2020-09-09 Current control method of cascade submodule working condition simulation system suitable for NLC

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010337959.XA CN111521946A (en) 2020-04-26 2020-04-26 Cascaded converter submodule working condition simulation system and current control method thereof

Publications (1)

Publication Number Publication Date
CN111521946A true CN111521946A (en) 2020-08-11

Family

ID=71903463

Family Applications (2)

Application Number Title Priority Date Filing Date
CN202010337959.XA Withdrawn CN111521946A (en) 2020-04-26 2020-04-26 Cascaded converter submodule working condition simulation system and current control method thereof
CN202010942352.4A Active CN111965468B (en) 2020-04-26 2020-09-09 Current control method of cascade submodule working condition simulation system suitable for NLC

Family Applications After (1)

Application Number Title Priority Date Filing Date
CN202010942352.4A Active CN111965468B (en) 2020-04-26 2020-09-09 Current control method of cascade submodule working condition simulation system suitable for NLC

Country Status (1)

Country Link
CN (2) CN111521946A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112636620A (en) * 2020-12-03 2021-04-09 上海交通大学 Method for generating nearest level approximation control signal for working condition simulation of cascaded converter
CN113176428A (en) * 2021-03-16 2021-07-27 上海交通大学 Current distortion eliminating system and method for working condition simulation of cascaded converter

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105186897B (en) * 2015-08-20 2017-12-15 华中科技大学 A kind of nearest level control method suitable for Modular multilevel converter rectifier
CN106787884B (en) * 2017-01-24 2019-06-25 特变电工新疆新能源股份有限公司 The pressure modulator approach and press modulating device that nearest level approaches
WO2019003290A1 (en) * 2017-06-27 2019-01-03 三菱電機株式会社 Power conversion device
CN107196327B (en) * 2017-07-12 2020-03-27 华北电力科学研究院有限责任公司 Feedforward control method for restraining power oscillation of modular voltage source type converter valve
CN107677956B (en) * 2017-09-29 2020-02-18 山东建筑大学 Current control method of flexible direct-current transmission MMC converter valve operation test device
CN109217687A (en) * 2018-08-24 2019-01-15 南京理工大学 Power distribution network electric power electric transformer and its control method based on MMC
CN109347352B (en) * 2018-11-21 2020-08-25 上海交通大学 Cascaded converter submodule capacitor voltage balance control method
CN109709363B (en) * 2019-01-29 2020-06-16 上海交通大学 Control method and system of cascade type converter multi-submodule multi-working-condition simulation device
CN109709434B (en) * 2019-01-29 2020-06-16 上海交通大学 Test circuit for multi-submodule and multi-working-condition simulation of cascaded converter
CN111030496B (en) * 2019-04-04 2022-11-11 沈阳工业大学 Variable carrier hybrid modulation method suitable for modular multilevel converter
CN110488115B (en) * 2019-07-23 2021-07-06 上海交通大学 Cascaded converter submodule single-phase test circuit based on symmetrical bridge arm structure
CN110850194B (en) * 2019-10-15 2020-10-30 上海交通大学 Working condition simulation test circuit and method for cascaded converter submodule

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112636620A (en) * 2020-12-03 2021-04-09 上海交通大学 Method for generating nearest level approximation control signal for working condition simulation of cascaded converter
CN113176428A (en) * 2021-03-16 2021-07-27 上海交通大学 Current distortion eliminating system and method for working condition simulation of cascaded converter
CN113176428B (en) * 2021-03-16 2022-05-03 上海交通大学 Current distortion eliminating system and method for working condition simulation of cascaded converter

Also Published As

Publication number Publication date
CN111965468B (en) 2021-08-03
CN111965468A (en) 2020-11-20

Similar Documents

Publication Publication Date Title
US11899067B2 (en) Testing circuit, system and control method for multiple submodules of cascaded converter
CN109709363B (en) Control method and system of cascade type converter multi-submodule multi-working-condition simulation device
CN111521946A (en) Cascaded converter submodule working condition simulation system and current control method thereof
CN110518820B (en) Fault-tolerant control method and system for open-circuit faults of T-type three-level inverter
CN107732921B (en) Electric energy quality composite control device based on nine-switch-tube inverter and working method
CN113346785B (en) Adaptive error compensation control system and method for inverter
CN108551271A (en) UPS three-phase PWMs voltage source inverter based on Active Disturbance Rejection Control and control method
CN110429603B (en) Six-switch seven-level active power filter and compensation method
Djerboub et al. Particle swarm optimization trained artificial neural network to control shunt active power filter based on multilevel flying capacitor inverter
CN112636348B (en) Control method of modular three-phase current type grid-connected inverter
US5388041A (en) Method and a circuit for controlling an inverter to switch in the sliding mode and by PWM with a three-level output voltage
CN110426649B (en) Single-phase test method and system for cascaded converter submodule
CN116979535A (en) Dual harmonic current detection method for active power filter
CN115128317A (en) Cascade structure current generator, converter submodule test circuit and control system
CN100466449C (en) Neutral point voltage controller
CN113176428B (en) Current distortion eliminating system and method for working condition simulation of cascaded converter
CN114977747A (en) Resonant filter, cascaded converter submodule test circuit and control
CN112787350A (en) Low-frequency oscillation circulating current suppression method and system for modular multilevel converter
Matsui et al. On-line impedance meter to measure the impedance of a distribution line using inverter
CN110912132A (en) Harmonic compensation control method for single-phase cascade active power filter
Villalva et al. Current controller with artificial neural network for 3-phase 4-wire active filter
CN112671257B (en) Four-switch three-phase inverter based on Cuk converter and integral sliding mode controller
Yamamoto et al. Compensating characteristics of voltage sag compensator utilizing single-phase matrix converter
Chakravorty et al. Harmonics Mitigation Based on Fuzzy Logic Controller
Li et al. A novel composite control strategy of three-phase intermediate frequency multiple inverter power supply

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
WW01 Invention patent application withdrawn after publication

Application publication date: 20200811

WW01 Invention patent application withdrawn after publication