CN111106621B - Harmonic isolation power supply device with low voltage ride through function and control method - Google Patents
Harmonic isolation power supply device with low voltage ride through function and control method Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/01—Arrangements for reducing harmonics or ripples
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
- H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
- H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
- H02J9/062—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for AC powered loads
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- 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
- H02M1/36—Means for starting or stopping converters
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- 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
- H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
- H02M1/4208—Arrangements for improving power factor of AC input
- H02M1/4216—Arrangements for improving power factor of AC input operating from a three-phase input voltage
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- 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
- H02M5/4585—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 having a rectifier with controlled elements
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- 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
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- 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
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
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Abstract
The invention provides a harmonic isolation power supply device with a low voltage ride through function and a control method, wherein the isolation power supply device comprises: the input alternating current filtering module filters background harmonics in the power grid and blocks harmonic current generated by the harmonic isolation power supply device to be injected into the power grid; the power factor correction module is used for rectifying the alternating current input into the alternating current filtering module into direct current; the direct current support module enters a discharging mode when the power factor correction module enters a current-limiting working mode and provides current to maintain stable output; the inverter circuit module inverts the direct current of the direct current support module into alternating current for output; the output alternating current filtering module is used for filtering the output alternating current of the inverter circuit module; and the control circuit module is used for realizing a control algorithm and protection logic of the harmonic isolation power supply device. The harmonic isolation power supply device with the low voltage ride through function provided by the invention has good harmonic isolation performance and can realize the low voltage ride through function.
Description
Technical Field
The invention relates to power electronics and harmonic isolation, in particular to a harmonic isolation technology of a power distribution network under a complex background harmonic condition, and specifically relates to a harmonic isolation power supply device with a low voltage ride through function and a control method.
Background
With the increasing of various nonlinear loads in power transmission and distribution systems, especially the rapid development of power electronic technology, various power devices and converter devices are applied to save energy, improve efficiency and quality of life of people, and simultaneously, due to the characteristics of nonlinearity and diversity, a large amount of harmonic waves are injected into a power grid, so that certain low-voltage electric equipment sensitive to the harmonic waves are damaged, failed or abnormally operated, and great economic loss is caused in certain fields.
At present, two methods are mainly used for weakening the influence of harmonic waves on loads, one method is a parallel technology, and a filtering means is adopted at an input side to eliminate background harmonic waves; the other is a series connection technology, and a direct current link is adopted for carrying out input and output harmonic isolation. The problem of the parallel technology is that if the background harmonic voltage is large, the parallel technology cannot completely eliminate the influence of the background harmonic on the load. The scheme of adopting the direct current link for isolation can completely isolate input and output harmonic waves theoretically, and eliminate the influence of background harmonic waves on the load. However, the current scheme of using a direct current link for harmonic isolation has the disadvantages of low power factor, complex control, no low voltage ride through function and the like.
Disclosure of Invention
Therefore, the technical problem to be solved by the present invention is to overcome the defects of low power factor, complex control and no low voltage ride through function in the prior art during harmonic isolation, thereby providing a harmonic isolation power supply device with a low voltage ride through function and a control method thereof.
Therefore, the embodiment of the invention provides the following technical scheme:
in a first aspect, an embodiment of the present invention provides a harmonic isolation power supply apparatus with a low voltage ride through function, including: the power supply device comprises an input alternating current filtering module, a power factor correction module, a direct current support module, an inverter circuit module, an output alternating current filtering module and a control circuit module, wherein the input alternating current filtering module is connected to a power distribution network and is used for filtering background harmonics in the power grid and blocking harmonic current generated by a harmonic isolation power supply device from being injected into the power grid; the power factor correction module is used for rectifying alternating current input into the alternating current filtering module into direct current, charging the direct current supporting module and adjusting the power factor of the harmonic isolation power supply device; the direct current support module is used for entering a discharging mode to provide current to maintain stable output when the power factor correction module enters a current-limiting working mode and cannot normally charge the direct current support module; the inverter circuit module is used for inverting the direct current of the direct current support module into alternating current to be output; the output alternating current filtering module is used for filtering the output alternating current of the inverter circuit module; and the control circuit module is used for realizing a control algorithm and protection logic of the harmonic isolation power supply device.
In one embodiment, the power factor correction module enters a current-limiting operating mode when the input voltage is lower than a preset threshold.
In one embodiment, the power factor correction module employs a control strategy that combines a variable switching frequency single cycle continuous control and a low voltage ride through algorithm.
In one embodiment, the power factor correction module comprises: the device comprises a soft start circuit, an uncontrolled rectifying circuit and a power factor correction circuit, wherein the soft start circuit is used for charging the direct current support module in a soft start mode; the uncontrolled rectifying circuit is used for rectifying alternating current into direct current; and the power factor correction circuit is used for adjusting the power factor of the alternating current side.
In one embodiment, the direct current support module adopts a structure that a capacitor and a battery pack are connected in parallel.
In one embodiment, the inverter circuit module outputs a rated voltage when the input voltage is lower than a preset threshold and the dc bus voltage is greater than a first preset voltage value; when the input voltage is lower than the preset threshold value and the direct current bus voltage is within the range of the first preset voltage value and the second preset voltage value, 90% of the rated voltage is output.
In one embodiment, the control circuit module includes: the device comprises a main controller, a sampling conditioning circuit, a switching value input/output interface circuit, a driving circuit and a human-computer interaction interface module, wherein the main controller is used for realizing a control algorithm and protection logic of a harmonic isolation power supply device; the sampling conditioning circuit is used for collecting alternating current voltage, current, direct current voltage and current, and sending digital quantity to the main controller after filtering, conditioning and analog-to-digital conversion; the switching value input/output interface circuit is used for level matching of input and output switching values; the driving circuit is used for receiving and executing a driving command issued by the main controller, finishing the driving functions of the power factor correction circuit and the inverter circuit module and feeding the states of the power factor correction circuit and the inverter circuit module back to the main controller; and the human-computer interaction interface module is used for displaying the state of each module and the power grid, recording fault events and sending the control parameters and the protection parameters to the main controller.
In a second aspect, an embodiment of the present invention provides a method for controlling a harmonic isolation power supply apparatus with a low voltage ride through function, including the following steps: starting the main controller, and performing self-checking and power grid condition state evaluation; after the state evaluation is passed, switching on and off the harmonic isolation power supply device to perform phase locking, and when the state evaluation is failed, alarming is performed, and the switching on and off of the harmonic isolation power supply device is not switched on; the direct current support module is charged through the soft start circuit, when the direct current support module is charged to a third preset voltage value, the control of the soft start circuit is quitted, the control is converted into the variable switching frequency single-cycle continuous control, and the direct current support module is continuously charged; when the direct current support module is detected to be charged to a fourth preset voltage value, starting a constant voltage current limiting mode of the inverter circuit module, and simultaneously detecting whether a short circuit or an overcurrent exists on a load side; when the constant voltage current-limiting mode lasts for the preset time without faults, the inverter circuit module enters a constant voltage source mode, and the harmonic isolation power supply device enters a normal operation mode.
In one embodiment, the method for controlling the harmonic isolation power supply device to realize low voltage ride through comprises the following steps: detecting whether the input voltage of the power grid has voltage sag, putting a low-voltage ride through program when the voltage sag occurs, and quitting the low-voltage ride through program when the voltage sag does not occur; when voltage sag is detected and the voltage is lower than a preset threshold value, executing a current limiting algorithm of a power factor correction module, and simultaneously sending a low-voltage ride-through enabling signal to an inverter circuit module; detecting the voltage of a direct current bus, wherein when the voltage of the direct current bus is greater than a first preset voltage value, the inverter circuit module outputs rated voltage, when the voltage of the direct current bus is within a range between the first preset voltage value and a second preset voltage value, the inverter circuit module outputs 90% of the rated voltage, and when the voltage of the direct current bus is less than the second preset voltage value, the harmonic isolation power supply device exits; and exiting the low voltage ride through program when the input voltage is detected to be recovered, automatically executing a starting program of the harmonic isolation power supply device if the harmonic isolation power supply device exits from running, and directly switching to a normal running mode if the harmonic isolation power supply device does not exit from running.
The technical scheme of the invention has the following advantages:
the harmonic isolation power supply device with the low voltage ride through function and the control method thereof provided by the invention have the advantages of good harmonic isolation performance, low voltage ride through function, good maneuverability, smaller volume and weight of the harmonic isolation power supply device, low cost and simple control method.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a block diagram showing a specific example of a harmonic isolation power supply device having a low voltage ride through function according to an embodiment of the present invention;
fig. 2 is a main circuit configuration diagram of a specific example of a harmonic isolation power supply apparatus having a low voltage ride through function according to an embodiment of the present invention;
fig. 3 is a block diagram of a specific example of a control circuit module in the embodiment of the present invention;
fig. 4 is a flowchart showing a specific example of a control method of the harmonic isolation power supply apparatus having the low voltage ride through function according to the embodiment of the present invention;
fig. 5 is a flowchart illustrating another specific example of a control method of the harmonic isolation power supply apparatus having the low voltage ride through function according to the embodiment of the present invention;
fig. 6 is a flowchart showing still another specific example of a control method of the harmonic isolation power supply apparatus having the low voltage ride through function according to the embodiment of the present invention;
FIG. 7 is a schematic diagram of a phase lock and low voltage ride through algorithm in accordance with an embodiment of the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "first", "second", and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In addition, the technical features involved in the different embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Example 1
The embodiment of the invention provides a harmonic isolation power supply device with a low voltage ride through function, which is suitable for harmonic isolation of a power distribution network under a complex background harmonic condition. As shown in fig. 1, the harmonic isolation power supply apparatus includes: the power supply device comprises an input alternating current filtering module 1, a power factor correction module 2, a direct current support module 3, an inverter circuit module 4, an output alternating current filtering module 5 and a control circuit module 6, wherein the input alternating current filtering module 1 is connected to a power distribution network and used for filtering background harmonics in the power grid and blocking harmonic currents generated by the harmonic isolation power supply device from being injected into the power grid.
In the embodiment of the invention, the harmonic isolation power supply device is connected to a 380V power distribution network through the input alternating current filter module 1 when the input switch is closed. As shown in fig. 2, the input ac filter module 1 employs a high-efficiency low-power-consumption EMI filter circuit, and provides a bleed-off channel for harmonics through a coupling network with the ground, so as to filter background harmonics in the power grid, reduce the influence on the subsequent circuit, and prevent the harmonics generated by the device from adversely affecting the power grid. The EMI filter circuit has a low-pass characteristic and an operating frequency of 0-60 Hz.
And the power factor correction module 2 is used for rectifying the alternating current input into the alternating current filter module 1 into direct current, charging the direct current support module 3 and adjusting the power factor of the harmonic isolation power supply device. In the embodiment of the present invention, as shown in fig. 2, the power factor correction module 2 adjusts the power factor of the harmonic isolation power supply device to be more than 0.99.
And the direct current support module 3 is used for enabling the direct current support module 3 to enter a discharging mode when the power factor correction module 2 enters a current-limiting working mode and cannot normally charge the direct current support module 3, and providing current to maintain stable output. In the embodiment of the present invention, as shown in fig. 2, the dc support module 3 adopts a structure in which a capacitor and a battery pack are connected in parallel, wherein the capacitor is preferably a film capacitor with good high-frequency characteristics, and the battery pack is preferably a lithium iron phosphate battery pack with high charge-discharge rate performance.
And the inverter circuit module 4 is used for inverting the direct current of the direct current support module 3 into alternating current to be output. In the embodiment of the present invention, as shown in fig. 2, the inverter circuit module 4 employs a three-phase half-bridge inverter formed by high-speed IGBTs, and inverts the dc power of the dc support module 3 into ac power for output by using a feed-forward control strategy.
And the output alternating current filtering module 5 is used for filtering the output alternating current of the inverter circuit module 4. In the embodiment of the present invention, as shown in fig. 2, the output ac filtering module 5 employs a high-efficiency low-power-consumption EMI filtering circuit to filter the output of the inverter, and mainly filters the characteristic subharmonic of the inverter.
And the control circuit module 6 is used for realizing a control algorithm and protection logic of the harmonic isolation power supply device. In the embodiment of the present invention, the control circuit module 6 is a high-performance DSP system formed based on TMS320LF28335, and is configured to implement a control algorithm and protection logic of the harmonic isolation power supply device.
In one embodiment, the power factor correction module 2 enters the current limiting mode of operation when the input voltage is below a predetermined threshold. In the embodiment of the present invention, the preset threshold is preferably 65% of the rated voltage, which is only used as an example and not limited thereto, and in other embodiments, the preset threshold may be reasonably set according to actual requirements.
In one embodiment, the power factor correction module 2 employs a control strategy that combines a variable switching frequency single cycle continuous control and a low voltage ride through algorithm. In the embodiment of the invention, the control of the power factor correction module 2 and the control of the inverter circuit module 4 are decoupled, so that the control of the power factor correction module 2 and the control of the inverter circuit module 4 are independent and do not influence each other.
In one embodiment, the power factor correction module 2 includes: soft start circuit, uncontrolled rectifier circuit and power factor correction circuit, wherein:
and the soft start circuit is used for soft start charging of the direct current support module 3. In the embodiment of the invention, the soft start circuit adopts a structure that a resistor is matched with a switch.
And the uncontrolled rectifying circuit is used for rectifying the alternating current into direct current. In the embodiment of the invention, the uncontrolled rectifying circuit adopts the silicon carbide diode, so that the uncontrolled rectifying circuit has high-temperature stability on one hand, and the loss of the power correcting circuit can be effectively reduced on the other hand.
And the power factor correction circuit is used for adjusting the power factor of the alternating current side. In the embodiment of the invention, the power factor correction circuit is an active power factor correction circuit adopting a Boost structure. The Boost structure active power factor correction circuit adopts a high-speed IGBT, and can work near an optimal operation point all the time by utilizing a variable switching frequency single-period continuous control mode.
In one embodiment, the dc support module 3 is configured with a capacitor and a battery in parallel.
In one embodiment, the inverter circuit module 4 outputs the rated voltage when the input voltage is lower than the preset threshold and the dc bus voltage is greater than the first preset voltage value; when the input voltage is lower than the preset threshold value and the direct current bus voltage is within the range of the first preset voltage value and the second preset voltage value, 90% of the rated voltage is output. In the embodiment of the present invention, the preset threshold is preferably 65% of the rated voltage, the first preset voltage value is preferably 540V, and the second preset voltage value is preferably 490V.
In one embodiment, as shown in fig. 3, the control circuit module 6 includes: a main controller 61, a sampling conditioning circuit 62, a switching value input/output interface circuit 63, a driving circuit 64 and a human-computer interaction interface module 65, wherein,
and the main controller 61 is used for realizing a control algorithm and protection logic of the harmonic isolation power supply device. In the embodiment of the present invention, the chip of the main controller 61 uses a TMS320F28335 floating-point DSP to implement all control algorithms and protection logic, which is only used as an example and is not limited thereto.
And the sampling conditioning circuit 62 is used for collecting alternating current voltage, current, direct current voltage and current, and sending digital quantity to the main controller 61 after filtering, conditioning and analog-to-digital conversion. In the embodiment of the present invention, the sampling conditioning circuit 62 includes CT, PT and hall elements, and the CT, PT and hall elements are used to collect ac voltage, current, dc voltage, current, and the like.
And a switching value input/output interface circuit 63 for level matching of the switching values of the input and output. In the embodiment of the present invention, the switching value input/output interface circuit 63 performs level matching of the input and output switching values by using a relay, a level conversion chip, and the like, and the interface between the switching value input/output interface circuit 63 and the main controller 61 is in a bus form.
The driving circuit 64 is configured to receive and execute a driving command issued by the main controller 61, complete the driving functions of the power factor correction circuit and the inverter circuit module 4, and feed back the states of the power factor correction circuit and the inverter circuit module 4 to the main controller 61. In the embodiment of the present invention, the driving circuit 64 receives and executes the driving command issued by the main controller 61, completes the driving functions of the Boost structure active power factor correction circuit and the inverter circuit module 4, and feeds back the states of the Boost structure active power factor correction circuit and the inverter circuit module 4 to the main controller 61.
And the human-computer interaction interface module 65 is used for displaying the states of all the modules and the power grid, recording fault events and sending control parameters and protection parameters to the main controller 61.
The harmonic isolation power supply device with the low voltage ride through function has good harmonic isolation performance, and when the background harmonic level is more than 2 times of the 3-type compatible level specified in GB/T18039.4-2003, the output electric energy can meet the 1-type compatible level specified in GB/T18039.4-2003; the efficiency is higher, and under the rated working condition, the efficiency is not less than 95%; a power factor greater than 0.99; the low-voltage ride through function is realized, and the SEMI F47 curve is met; the harmonic isolation power supply device provided by the embodiment of the invention has the advantages of good maneuverability, unit rated power, smaller volume and weight and low cost.
Example 2
The embodiment of the invention provides a control method of a harmonic isolation power supply device with a low voltage ride through function, which comprises the following steps as shown in fig. 4:
step S11: and starting the main controller, and performing self-checking and power grid condition state evaluation. In the embodiment of the invention, the state evaluation comprises self-checking and power grid condition evaluation.
Step S12: and after the state evaluation is passed, switching into a harmonic isolation power supply device switch for phase locking, and when the state evaluation is failed, alarming and switching into the harmonic isolation power supply device switch are not performed. In the embodiment of the invention, the phase locking is performed by an open-loop control quick phase locking algorithm based on dq transformation.
Step S13: and charging the direct current support module through the soft start circuit, and when the direct current support module is charged to a third preset voltage value, quitting the control of the soft start circuit, converting the control into the variable switching frequency single-cycle continuous control, and continuously charging the direct current support module. In the embodiment of the present invention, the third preset voltage value is preferably 500V, and when the dc bus capacitor is charged to 500V, the soft start circuit control is exited, the control is converted into the variable switching frequency single-cycle continuous control, and the charging of the dc bus capacitor is continued.
Step S14: and when the direct current support module is detected to be charged to a fourth preset voltage value, starting a constant voltage current limiting mode of the inverter circuit module, and simultaneously detecting whether a short circuit or an overcurrent exists on the load side. In the embodiment of the invention, the fourth preset voltage value is preferably 600V, when it is detected that the dc bus capacitor is charged to 600V, the inverter starts to operate, the initial operating mode is a constant voltage current limiting mode, the output voltage is 50Hz/380V, the current limit is within 0.5 times of the rated voltage, and whether a short circuit or an overcurrent exists on the load side is detected.
Step S15: when the constant voltage current-limiting mode lasts for the preset time without faults, the inverter circuit module enters a constant voltage source mode, and the harmonic isolation power supply device enters a normal operation mode. In the embodiment of the present invention, the preset time is preferably 2 seconds, which is only an example and not limited thereto.
In one embodiment, the control method of the harmonic isolation power supply apparatus is as shown in fig. 6:
in the first step, the master controller starts and performs a state evaluation.
Secondly, evaluating the state to be normal, switching in a switch, and performing phase locking; and if the state evaluation is abnormal, alarming and exiting.
And thirdly, charging the direct current support module through soft start, when the direct current bus capacitor is charged to 500V, quitting the soft start control, converting the soft start control into single-cycle continuous control, and continuously charging the direct current bus capacitor.
And fourthly, when the direct current bus capacitor is detected to be charged to 600V, the inverter starts to work, and whether a fault exists on the load side is detected.
Fifthly, the constant voltage current limiting mode lasts for 2 seconds, and if the load side is normal, the harmonic isolation power supply device enters a normal operation mode; and if the load side is abnormal, alarming and exiting.
In one embodiment, controlling the real harmonic isolation power supply device to realize low voltage ride through, as shown in fig. 5, includes the following steps:
step S21: and detecting whether the input voltage of the power grid has voltage sag, putting in a low-voltage ride through program when the voltage sag occurs, and exiting the low-voltage ride through program when the voltage sag does not occur.
Step S22: and when the voltage sag is detected and the voltage is lower than the preset threshold value, executing a current limiting algorithm of the power factor correction module, and simultaneously sending a low-voltage ride-through enabling signal to the inverter circuit module.
In the embodiment of the present invention, the preset threshold is preferably 65% of the rated voltage, and the lower the voltage, the smaller the current limit when executing the pfc module direct proportional current limiting algorithm. Wherein, in a positive ratioThe current limit algorithm, shown in fig. 7, inputs the influence factor of the voltage sag on the dc voltage, i.e., Δ v. The concrete implementation is as follows: (1) through dq conversion link, three-phase voltage signals are converted into angular frequency thetarefDq components in a rotating coordinate system. (2) The filter switches the filtering method according to the magnitude of the negative sequence and harmonic in the input voltage, and when the negative sequence and harmonic are smaller, the filter is not used; when the negative sequence is larger and the harmonic is smaller, a time delay cancellation method is used for eliminating the frequency multiplication component in the dq axis voltage; if the harmonic is larger and the negative sequence is smaller, a second-order Butterworth filter with the cut-off frequency of 100Hz is adopted; when both harmonic waves and negative sequences are large, a time delay cancellation method and a second-order Butterworth filter with the cut-off frequency of 100Hz are used for filtering the non-direct-current component of the dq-axis voltage. (3) The dq axis component under the rectangular coordinate system is converted into an amplitude M and an amplitude P under a polar coordinate; and subtracting the reference value Vref from the amplitude factor M of the three-phase voltage at each sampling point, leading the difference value to pass through a PI link, and adding a value obtained by the direct-current voltage through a differential link to obtain delta v. (4) In the direct proportional current limiting algorithm, when voltage sag occurs, the power factor and the direct current bus voltage are no longer control targets, the control targets are only the output current of a Boost circuit, Δ v is in nonlinear positive correlation with the switching frequency in a power correction circuit, and Δ v is in nonlinear negative correlation with the output current of the power correction circuit. The calculation period of the algorithm is the same as the sampling period of the controller.
Step S23: the method comprises the steps of detecting the voltage of a direct current bus, outputting rated voltage by an inverter circuit module when the voltage of the direct current bus is larger than a first preset voltage value, outputting 90% of the rated voltage by the inverter circuit module when the voltage of the direct current bus is within a range between the first preset voltage value and a second preset voltage value, and exiting a harmonic isolation power supply device when the voltage of the direct current bus is smaller than the second preset voltage value. In the embodiment of the present invention, the first preset voltage value is preferably 540V, and the second preset voltage value is preferably 490V.
Step S24: and when the input voltage is detected to be recovered, exiting the low voltage ride through program, automatically executing a starting program of the harmonic isolation power supply device if the harmonic isolation power supply device exits from operation, and directly switching to a normal operation mode if the harmonic isolation power supply device does not exit from operation.
The control method of the harmonic isolation power supply device with the low voltage ride through function provided by the invention utilizes the control circuit module to operate the software program of the isolation power supply device to realize the harmonic isolation function, and simultaneously has the low voltage ride through function, simple control process and low cost.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (6)
1. A harmonic isolation power supply apparatus having a low voltage ride through function, comprising: an input AC filter module, a power factor correction module, a DC support module, an inverter circuit module, an output AC filter module, and a control circuit module,
the input alternating current filtering module is connected to the power distribution network and is used for filtering background harmonics in the power grid and blocking harmonic current generated by the harmonic isolation power supply device from being injected into the power grid;
the power factor correction module is used for rectifying alternating current input into the alternating current filtering module into direct current, charging the direct current supporting module and adjusting the power factor of the harmonic isolation power supply device;
the direct current support module is used for entering a discharging mode to provide current to maintain stable output when the power factor correction module enters a current-limiting working mode and cannot normally charge the direct current support module;
the inverter circuit module is used for inverting the direct current of the direct current support module into alternating current to be output;
the output alternating current filtering module is used for filtering the alternating current output by the inverter circuit module;
the control circuit module is used for realizing a control algorithm and protection logic of the harmonic isolation power supply device;
the power factor correction module enters a current-limiting working mode when the input voltage is lower than a preset threshold value;
the power factor correction module adopts a control strategy combining variable switching frequency single-period continuous control and a low voltage ride through algorithm;
the power factor correction module includes: a soft start circuit, an uncontrolled rectifying circuit and a power factor correction circuit, wherein,
the soft start circuit is used for charging the direct current support module in a soft start mode;
the uncontrolled rectifying circuit is used for rectifying alternating current into direct current;
and the power factor correction circuit is used for adjusting the power factor of the alternating current side.
2. The harmonic isolation power supply device with low voltage ride through function according to claim 1, wherein the dc support module adopts a parallel structure of a capacitor and a battery pack.
3. The harmonic isolation power supply device with the low voltage ride-through function according to claim 1, wherein the inverter circuit module outputs a rated voltage when the input voltage is lower than a preset threshold value and the dc bus voltage is greater than a first preset voltage value;
when the input voltage is lower than the preset threshold value and the direct current bus voltage is within the range of the first preset voltage value and the second preset voltage value, 90% of the rated voltage is output.
4. The harmonic isolation power supply apparatus with low voltage ride through of claim 1, wherein the control circuit module comprises: a main controller, a sampling conditioning circuit, a switching value input and output interface circuit, a driving circuit and a man-machine interaction interface module, wherein,
the main controller is used for realizing a control algorithm and protection logic of the harmonic isolation power supply device;
the sampling conditioning circuit is used for collecting alternating current voltage, current, direct current voltage and current, and sending digital quantity to the main controller after filtering, conditioning and analog-to-digital conversion;
the switching value input/output interface circuit is used for level matching of input and output switching values;
the driving circuit is used for receiving and executing a driving command issued by the main controller, finishing the driving functions of the power factor correction circuit and the inverter circuit module and feeding the states of the power factor correction circuit and the inverter circuit module back to the main controller;
and the human-computer interaction interface module is used for displaying the state of each module and the power grid, recording fault events and sending the control parameters and the protection parameters to the main controller.
5. A control method of a harmonic isolation power supply device with a low voltage ride through function based on any one of claims 1 to 4 is characterized by comprising the following steps:
starting the main controller, and performing self-checking and power grid condition state evaluation;
after the state evaluation is passed, switching on and off the harmonic isolation power supply device to perform phase locking, and when the state evaluation is failed, alarming is performed, and the switching on and off of the harmonic isolation power supply device is not switched on;
the direct current support module is charged through the soft start circuit, when the direct current support module is charged to a third preset voltage value, the control of the soft start circuit is quitted, the control is converted into the variable switching frequency single-cycle continuous control, and the direct current support module is continuously charged;
when the direct current support module is detected to be charged to a fourth preset voltage value, starting a constant voltage current limiting mode of the inverter circuit module, and simultaneously detecting whether a short circuit or an overcurrent exists on a load side;
when the constant voltage current-limiting mode lasts for the preset time without faults, the inverter circuit module enters a constant voltage source mode, and the harmonic isolation power supply device enters a normal operation mode.
6. The method for controlling a harmonic isolation power supply apparatus having a low voltage ride through function according to claim 5, further comprising: the method for controlling the harmonic isolation power supply device to realize low voltage ride through comprises the following steps:
detecting whether the input voltage of the power grid has voltage sag, putting a low-voltage ride through program when the voltage sag occurs, and quitting the low-voltage ride through program when the voltage sag does not occur;
when voltage sag is detected and the voltage is lower than a preset threshold value, executing a current limiting algorithm of a power factor correction module, and simultaneously sending a low-voltage ride-through enabling signal to an inverter circuit module;
detecting the voltage of a direct current bus, wherein when the voltage of the direct current bus is greater than a first preset voltage value, the inverter circuit module outputs rated voltage, when the voltage of the direct current bus is within a range between the first preset voltage value and a second preset voltage value, the inverter circuit module outputs 90% of the rated voltage, and when the voltage of the direct current bus is less than the second preset voltage value, the harmonic isolation power supply device exits;
and exiting the low voltage ride through program when the input voltage is detected to be recovered, automatically executing a starting program of the harmonic isolation power supply device if the harmonic isolation power supply device exits from running, and directly switching to a normal running mode if the harmonic isolation power supply device does not exit from running.
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