CN113675829B - Direct-current short-circuit fault current limiting circuit of low-voltage treatment device and control method thereof - Google Patents
Direct-current short-circuit fault current limiting circuit of low-voltage treatment device and control method thereof Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
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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
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
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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
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- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
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Abstract
The invention discloses a direct current short circuit fault current limiting circuit of a low voltage treatment device and a control method thereof, wherein the current limiting circuit comprises a rectifying side direct current short circuit fault current limiting circuit, and BUCK topology is adopted; the inversion side direct current short circuit fault current limiting circuit adopts a BOOST topology; when short-circuit fault occurs on the DC transmission line, short-circuit current of the rectifier and the DC port of the inverter of the low-voltage treatment device is limited; the control method of the current limiting circuit needs to obtain the working information of the circuit through data sampling; and the current is taken as a judgment condition, so that the accurate switching of a normal working mode, a current-limiting hysteresis mode and a BOOST mode is realized, the current limiting of a direct current port, the operation with faults, the quick recovery after the fault removal and the reliable execution of a long-time overload judgment protection function are ensured, and the high-performance control of the current-limiting circuit is realized.
Description
Technical Field
The invention relates to the technical field of power electronics and control thereof, in particular to a direct-current short-circuit fault current limiting circuit of a low-voltage treatment device and a control method thereof.
Background
In some remote mountainous areas and rural areas, the problem of low voltage at the tail end of a low-voltage distribution network is common due to various reasons such as long power supply radius, small power supply line diameter and the like. The low voltage problem has an adverse effect on the electricity consumption experience of the resident user and on the power supply reliability of the power grid. The conventional measures for treating the low-voltage problem are transformation and capacity expansion of a distribution transformer and a circuit, and the problems of long construction period, high construction cost, low return on investment and the like exist. The low-voltage treatment device is based on the existing distribution network, rectifies and boosts low-voltage alternating-current distribution near a distribution transformer into direct-current distribution, inverts and stabilizes the direct-current distribution near resident users into standard low-voltage alternating-current distribution, and solves the problem of low voltage at the tail end of long-distance transmission of the original alternating-current low-voltage distribution network. The scheme fully utilizes the existing distribution line, is convenient for equipment installation and construction, and reduces comprehensive transformation cost; and the boosted direct current distribution is adopted, so that the flowing current is reduced, and the line loss is reduced.
The low-voltage treatment device adopts a long transmission line of an original alternating-current low-voltage distribution network to transmit direct current, and short circuit faults caused by insulation aging, misoperation and even bad weather seriously affect the reliability of direct-current transmission and even cause equipment damage. For a power grid, a traditional air switch and other switching devices of an alternating current line have certain alternating current short circuit fault removal capability; for electrical equipment, the ac port of the power electronics has a mature short circuit detection and current limiting protection scheme. However, for direct current transmission, the zero-crossing arc extinction characteristic of alternating current arc is not available, the traditional switch is difficult to break large short-circuit fault current, even the problem that the arc burns out contacts of a switching device exists, and the direct current switching device such as a direct current breaker also faces the contradiction between price and service life; for electric equipment, the direct current port of the power electronic equipment usually has a large capacitance, so that when a direct current circuit has a short circuit fault, the fault current is usually large, and the severe requirements are put on the tolerance capability of the direct current switching device and the power electronic equipment.
Disclosure of Invention
The invention provides a direct current short circuit fault current limiting circuit of a low voltage treatment device and a control method thereof, aiming at the defects and the shortcomings of the prior art, wherein the current limiting circuit comprises a rectifying side direct current short circuit fault current limiting circuit and an inverting side direct current short circuit fault current limiting circuit, and is used for limiting the short circuit current of a rectifier and an inverter direct current port of the low voltage treatment device when a short circuit fault occurs on a direct current transmission line; the control method of the current limiting circuit takes the current magnitude as a judgment condition, realizes the accurate switching of a normal working mode, a current limiting hysteresis mode and a BOOST mode, and realizes the high-performance control of the current limiting circuit.
The aim of the invention can be achieved by the following technical scheme:
the utility model provides a low voltage governance device direct current short circuit fault current limiting circuit, contains rectification side direct current short circuit fault circuit and contravariant side direct current short circuit fault current limiting circuit, its characterized in that when short circuit fault takes place on direct current transmission line, restriction low voltage governance device rectifier and dc-to-ac converter port's short circuit current, the area trouble operation of low voltage governance device is permitted, supplementary dc-to-ac converter direct current busbar is quick to step up, resume after the trouble excision, have long-term overload judgement, protect function, wherein:
the rectifying side direct current short circuit fault current limiting circuit includes: switch tube S 1 Diode D 1 Reactor L 1 Wherein, the positive pole and the switch tube S of the rectifier direct current side of the low voltage treatment device 1 Is connected with the collector of the diode D 1 Anode of (C) is connected with switch tube S 1 Emitter, diode D of (2) 1 Cathode of (c) and reactor L 1 Is connected with one end of reactor L 1 The other end of the diode D is connected with the positive pole of the direct current transmission line 1 The anode of the direct current transmission line is connected with the cathode of the direct current transmission line;
the inversion side direct current short circuit fault current limiting circuit comprises: switch tube S 2 And S is equal to 3 Reactor L 2 Wherein, the positive pole of the inverter of the low voltage treatment device and the switch tube S 2 Is connected with the collector of the switch tube S 3 Emitter connected to, switch tube S 2 Emitter, switch tube S of (2) 3 Collector and reactor L of (c) 2 Is connected with one end of reactor L 2 The other end of the switch tube S is connected with the positive pole of the direct current transmission line 3 The emitter of which is connected with the negative pole of the direct current transmission line.
Further, the rectifying side direct current short circuit fault current limiting circuit adopts BUCK voltage reduction topology, is connected with the direct current bus of the rectifier and the output direct current port of the rectifier, and achieves the functions of current limiting and voltage reduction of the direct current port when the direct current port has a short circuit fault.
Further, the inversion side direct current short circuit fault current limiting circuit adopts a BOOST topology, is connected with the inverter direct current bus and the input direct current port thereof, and realizes the functions of current limiting, fault operation and quick recovery after fault removal of the direct current port when the direct current port has a short circuit fault.
Further, the direct current short circuit fault current limiting circuit has long-term overload judging and protecting functions, and the fault and the large current under the short-term overload provide important fault information for the judgment of the fault and the action of the protecting device, but the long-term large current works, so that the temperature rise of the current limiting circuit is unfavorable and cannot occur under normal working conditions, and therefore, the shutdown of the low voltage treatment device can be triggered after the long-term overload judging condition is met due to the self-protection of the equipment.
The invention also provides a control method of the direct current short circuit fault current limiting circuit of the low voltage treatment device, which comprises the following steps:
data sampling, sampling current I of direct current short circuit fault current limiting circuit L1 And I L2 ；
And judging the overload for a long time, and triggering the overload protection for a long time to stop the rectifier or the inverter if the current is at a larger value for a long time.
Judging the working mode, namely judging that the direct current short circuit fault current limiting circuit is in a normal working mode or a current limiting hysteresis mode according to the current magnitude;
the BOOST mode is used for the BOOST mode of the direct current short circuit fault current limiting circuit at the inversion side, and is used for the operation with faults of the inverter or the rapid BOOST and recovery of the direct current bus of the auxiliary inverter;
further, the long-time overload judgment is performed when the current I of the rectifying side direct current short circuit fault current limiting circuit is detected L1_N ≤I L1 ≤I L1_max Or detecting the current-I of the inversion side direct current short circuit fault current-limiting circuit L2_max ≤I L2 ≤I L2_N Duration t OL Time, or the direct current short circuit fault current limiting circuit is in a current limiting hysteresis mode andduration t OL And (3) time, performing long-time overload protection operation, and stopping the rectifier or the inverter of the low-voltage treatment device.
Further, the switching tube S in the normal working mode 1 And S is equal to 2 Conduction and switch tube S 3 The low-voltage treatment device is turned off, and the energy bidirectional flow function is still realized.
Further, the current-limiting hysteresis mode adopts a current hysteresis control technology, when the current I of the rectifying side direct current short circuit fault current-limiting circuit is detected L1 ≥I L1_max Switch tube S 1 Turn off when I is detected L1 <I L1_max -ΔI L1 Switch tube S 1 Conducting; when detecting the current I of the inversion side direct current short circuit fault current limiting circuit L2 ≤-I L2_max Switch tube S 2 Turn off, S 3 Turn off when I is detected L2 >-I L2_max +ΔI L2 Switch tube S 2 Conduction, S 3 And (5) switching off.
Further, the BOOST mode has short circuit fault and V on the DC side bus2 ≤V bst When the current limiting circuit is triggered, the direct current short circuit fault current limiting circuit at the inversion side performs duty ratio calculation and hysteresis current limiting, so that the fault current limiting circuit has certain boosting capability on the premise of no overcurrent.
The duty cycle calculation formula is:
D＝V in /V N
switch tube S 2 、S 3 Complementary on-off, S 2 Is of duty cycle D, S 3 The duty cycle of (2) is 1-D.
When I is detected L2 ≥I L2_max When the current is limited by the hysteresis loop, the switching tube is not controlled according to the result of duty ratio calculation, and the switching tube S 2 Conduction, S 3 Turn off when I is detected L2 <I L2_max -ΔI L2 And when the flow is stopped, the hysteresis loop is stopped for limiting the flow.
When V is bus2 ≥V nor -ΔV bus2 When the system is in the BOOST mode, the system exits the BOOST mode and enters the normal working mode; when V is bus2 <V min And when the BOOST mode is exited, stopping the inverter.
The beneficial technical effects of the invention are as follows:
1. when the rectifying side direct current short circuit fault current limiting circuit and the inverting side direct current short circuit fault current limiting circuit generate short circuit faults on the direct current circuit, the magnitudes of short circuit currents of a rectifier and a direct current port of an inverter of the low voltage treatment device are limited, so that certain large currents can be provided for fault judgment and important fault information for the action of a protection device, and self-protection of equipment is facilitated.
2. The direct current short circuit fault current limiting circuit of the low voltage treatment device is combined with the control method thereof, so that the system is allowed to run for a period of time with short circuit faults, has the functions of automatic and quick recovery after fault removal and long-time overload judgment and protection, and improves the power supply reliability to a certain extent.
Drawings
Fig. 1 is a topology diagram of a low voltage abatement device and a low voltage distribution system in which it resides.
Fig. 2 is a topology diagram of an AC/DC rectifier of a low voltage abatement device and its rectifying side DC short circuit fault current limiting circuit.
Fig. 3 is a topology diagram of a DC/AC inverter of a low voltage abatement device and its inverter side DC short circuit fault current limiting circuit.
Fig. 4 is a block diagram of an implementation flow of a control method of the dc short-circuit fault current limiting circuit of the low voltage treatment device according to the control method of the present invention.
Fig. 5 is a block diagram of an implementation flow of the control method of the dc short-circuit fault current limiting circuit of the low voltage treatment device according to the control method of the dc short-circuit fault current limiting circuit of the present invention.
Fig. 6 is a simulation result in the case of a severe short-circuit fault of the low voltage treatment apparatus.
Fig. 7 is a simulation result in the case of a slight short-circuit fault of the low voltage treatment apparatus.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
The topology diagram of the low-voltage treatment device and the low-voltage distribution system thereof applied by the invention is shown in figure 1, the low-voltage treatment device mainly comprises an AC/DC rectifier, a DC/AC inverter and a switch group thereof, and the original low-voltage distribution system mainly comprises a distribution transformer, a long transmission line and a user by taking a single-phase system as an example. When the low-voltage treatment device works, an alternating current input switch and a direct current input switch are closed, the alternating current output by the distribution transformer is boosted and rectified into direct current by the AC/DC rectifier, the direct current is transmitted to the DC/AC inverter through an existing distribution line, and the direct current is inverted into standard single-phase alternating current by the DC/AC inverter and is transmitted to a user through the existing distribution line. The problem of terminal low voltage of former alternating current low voltage distribution network long distance transmission is solved.
The AC/DC rectifier of the low-voltage treatment device and the rectifying side direct-current short-circuit fault current-limiting circuit thereof are shown in fig. 2, and the DC/AC inverter of the low-voltage treatment device and the inverting side direct-current short-circuit fault current-limiting circuit thereof are shown in fig. 3. The AC/DC rectifier and the DC/AC inverter of the low-voltage harnessing device have the same topological structure and comprise a voltage equalizing circuit, a direct current bus, an NPC three-level inverter bridge and an LC filter. The NPC three-level inverter bridge realizes the rectification function of rectifying alternating current into direct current or the inversion function of inverting direct current into alternating current. The LC filter is used to filter out switching subharmonics of the ac port. The DC bus is composed of an upper capacitor and a lower capacitor which are connected in series to obtain three levels, and has the functions of filtering switching subharmonic waves of a DC port and providing energy buffering.
The low-voltage treatment device direct-current short-circuit fault current limiting circuit comprises a rectifying side direct-current short-circuit fault current limiting circuit and an inverting side direct-current short-circuit fault current limiting circuit in fig. 2 and 3, and is used for limiting short-circuit currents of a rectifier and an inverter direct-current port of the low-voltage treatment device when a short-circuit fault occurs on a direct-current transmission line.
The rectifying side DC short-circuit fault current limiting circuit shown in FIG. 2 comprises a switching tube S 1 Diode D 1 Reactor L 1 Three parts. Positive pole and switching tube S of rectifier DC side of low voltage treatment device 1 Is connected with the collector of the diode D 1 Anode of (C) is connected with switch tube S 1 Emitter, diode D of (2) 1 Cathode of (c) and reactor L 1 Is connected with one end of reactor L 1 The other end of the diode D is connected with the positive pole of the direct current transmission line 1 The anode of the direct current transmission line is connected with the cathode of the direct current transmission line. The rectifying side direct current short circuit fault current limiting circuit is in BUCK voltage reduction topology, is connected with a direct current bus of a rectifier and an output direct current port of the rectifier, and achieves the functions of current limiting and voltage reduction of the direct current port when the direct current port has a short circuit fault.
As shown in fig. 3, the inverter-side dc short-circuit fault current limiting circuit includes: switch tube S 2 And S is equal to 3 Reactor L 2 Three parts. Positive pole of inverter of low-voltage treatment device and switching tube S 2 Is connected with the collector of the switch tube S 3 Emitter connected to, switch tube S 2 Emitter, switch tube S of (2) 3 Collector and reactor L of (c) 2 Is connected with one end of reactor L 2 The other end of the switch tube S is connected with the positive pole of the direct current transmission line 3 The emitter of which is connected with the negative pole of the direct current transmission line. The direct current short circuit fault current limiting circuit at the inversion side is in a BOOST topology and is connected with the direct current bus of the inverter and the input direct current port of the direct current bus, and when the direct current port has a short circuit fault, the functions of current limiting, fault operation and quick recovery after fault removal of the direct current port are realized.
The direct current short circuit fault current limiting circuits shown in fig. 2 and 3 have long-term overload judging and protecting functions, and the fault and the large current under the short-term overload provide important fault information for the judgment of the fault and the action of a protecting device, but the long-term large current works, so that the temperature rise of the current limiting circuit is unfavorable, and the current limiting circuit cannot occur under normal working conditions, so that the low voltage treatment device is triggered to stop after the long-term overload judging condition is met due to the self protection of equipment.
Fig. 4 shows an implementation flow of the control method of the rectifying side dc short-circuit fault current limiting circuit of the present invention, and fig. 5 shows an implementation flow of the control method of the inverting side dc short-circuit fault current limiting circuit of the present invention. The working information of the circuit is obtained through data sampling, the current is used as a judging condition, the accurate switching of a normal working mode, a current-limiting hysteresis mode and a BOOST mode is realized, and the high-performance control of the current-limiting circuit is realized.
The invention discloses a control method of a direct current short circuit fault current limiting circuit of a low voltage treatment device, which comprises the following steps:
step 1: data sampling, sampling current I of direct current short circuit fault current limiting circuit L1 And I L2 。
Step 2: and judging the overload for a long time, and triggering the overload protection for a long time to stop the rectifier or the inverter if the current is at a larger value for a long time.
When detecting the current I of the rectifying side direct current short circuit fault current limiting circuit L1_N ≤I L1 ≤I L1_max Or detecting the current-I of the inversion side direct current short circuit fault current-limiting circuit L2_max ≤I L2 ≤I L2_N Duration t OL Time, or the direct current short circuit fault current limiting circuit is in a current limiting hysteresis mode and lasts for t OL And (3) time, performing long-time overload protection operation, and stopping the rectifier or the inverter of the low-voltage treatment device.
Step 3: and judging the working mode, namely judging that the direct current short circuit fault current limiting circuit is in a normal working mode or a current limiting hysteresis mode according to the current magnitude.
Wherein, the switch tube S in normal working mode 1 And S is equal to 2 Conduction and switch tube S 3 The low-voltage treatment device is turned off, and the energy bidirectional flow function is still realized.
The current-limiting hysteresis mode adopts a current hysteresis control technology, when the current I of the rectifying side direct current short circuit fault current-limiting circuit is detected L1 ≥I L1_max Switch tube S 1 Turn off when I is detected L1 <I L1_max -ΔI L1 Switch tube S 1 Conducting; when detecting the current I of the inversion side direct current short circuit fault current limiting circuit L2 ≤-I L2_max Switch tube S 2 Turn off, S 3 Turn off when I is detected L2 >-I L2_max +ΔI L2 Switch tube S 2 Conduction, S 3 And (5) switching off.
Step 4: the BOOST mode is used for the BOOST mode of the direct current short circuit fault current limiting circuit at the inversion side, and is used for the operation with faults of the inverter or the rapid BOOST and recovery of the direct current bus of the auxiliary inverter.
BOOST mode short circuit fault, V, on dc side bus2 ≤V bst When the current limiting circuit is triggered, the direct current short circuit fault current limiting circuit at the inversion side performs duty ratio calculation and hysteresis current limiting, so that the fault current limiting circuit has certain boosting capability on the premise of no overcurrent.
The duty cycle calculation formula is:
D＝V in /V N
switch tube S 2 、S 3 Complementary on-off, S 2 Is of duty cycle D, S 3 The duty cycle of (2) is 1-D.
When I is detected L2 ≥I L2_max When the current is limited by the hysteresis loop, the switching tube is not controlled according to the result of duty ratio calculation, and the switching tube S 2 Conduction, S 3 Turn off when I is detected L2 <I L2_max -ΔI L2 And when the flow is stopped, the hysteresis loop is stopped for limiting the flow.
When V is bus2 ≥V nor -ΔV bus2 When the system is in the BOOST mode, the system exits the BOOST mode and enters the normal working mode; when V is bus2 <V min And when the BOOST mode is exited, stopping the inverter.
The simulation result of the DC short-circuit fault current limiting circuit of the low-voltage treatment device and the control method thereof under the condition of serious short-circuit fault is shown in figure 6, which shows the DC bus voltage V of the rectifier bus1 Current I of rectifying side DC short-circuit fault current-limiting circuit L1 DC port of the sameVoltage V out DC bus voltage V of inverter bus2 Current I of inversion side direct current short circuit fault current limiting circuit L2 Dc port voltage V in Is a waveform of the simulation result of (a). At t 1 Serious short-circuit fault appears on the direct-current transmission line at any moment, and current I of rectifying side direct-current short-circuit fault current-limiting circuit L1 Rapidly increasing, entering into a current-limiting hysteresis mode, and performing high-current operation in the current-limiting hysteresis mode for a long time, wherein at t 3 Triggering long-time overload protection, and stopping the rectifier. Current I of inversion side direct current short circuit fault current limiting circuit L2 At the beginning of the fault, changing from forward to reverse and entering into a current limiting hysteresis mode; then along with the DC bus voltage V of the inverter bus2 The inverter-side current limiting circuit enters a BOOST mode, and the current I is L2 Gradually change from reverse to forward, but the short-circuit fault is too serious, V bus2 Continuously decrease at t 2 The inverter shutdown is triggered at the moment. The simulation results of fig. 6 demonstrate the effectiveness of the present invention in severe short circuit fault conditions.
The simulation result of the direct current short circuit fault current limiting circuit of the low voltage treatment device and the control method thereof under the condition of slight short circuit fault is shown in fig. 7. At t 4 At moment, a slight short-circuit fault appears on the direct-current transmission line, and the current I of the rectifying side direct-current short-circuit fault current-limiting circuit L1 Faster increase, enter the current limiting hysteresis mode over a period of time, at t 8 Short-circuit fault on direct current transmission line is cut off at moment, current I at rectifying side L1 Lowering and entering into a normal working mode. Current I of inversion side direct current short circuit fault current limiting circuit L2 At the beginning of the fault, the forward direction is gradually changed into the reverse direction, but the short circuit fault is slight, so that the current-limiting hysteresis mode is not entered; then along with the DC bus voltage V of the inverter bus2 Is reduced by (c), at t 5 The current limiting circuit at the moment inversion side enters a BOOST mode, and the current I L2 Gradually change from reverse to forward, and the DC bus voltage V of the inverter bus2 Gradually rise, at t 6 The inverter side current limiting circuit enters a normal working mode at any moment; but due to short-circuit failureStill present, at t 6 Current I after time L2 The voltage is changed from the forward direction to the reverse direction and the DC bus voltage V bus2 Gradually decrease and at t 7 The BOOST mode is re-entered at time, at t 8 After the short-circuit fault on the direct-current transmission line is cut off at moment, the BOOST mode of the BOOST current-limiting circuit for the direct-current short-circuit fault on the inversion side is carried out for a period of time, and then at t 9 And the normal working mode is recovered at any time, and the function of quick recovery after slight fault removal is realized. The simulation results of fig. 7 demonstrate the effectiveness of the present invention in the event of a slight short circuit fault.
The above embodiments are illustrative of the specific embodiments of the present invention, and not restrictive, and various changes and modifications may be made by those skilled in the relevant art without departing from the spirit and scope of the invention, so that all such equivalent embodiments are intended to be within the scope of the invention.
Claims (9)
1. The direct current short circuit fault current limiting circuit of the low voltage treatment device comprises a rectifying side direct current short circuit fault current limiting circuit and an inverting side direct current short circuit fault current limiting circuit, and is characterized in that a rectifier is arranged near a distribution transformer and used for rectifying and boosting low-voltage alternating current distribution into direct current distribution;
when a short circuit fault occurs on the direct current transmission line, limiting short circuit current of a rectifier of the low voltage treatment device and a direct current port of the inverter, allowing the low voltage treatment device to operate with the fault, and after the fault is removed, assisting the direct current bus of the inverter to quickly boost and recover, thereby having long-time overload judging and protecting functions, wherein:
the rectifying side direct current short circuit fault current limiting circuit includes: switch tube S 1 Diode D 1 Reactor L 1 Wherein, the positive pole and the switch of the rectifier direct current side of the low voltage governance deviceTube S 1 Is connected with the collector of the diode D 1 Anode of (C) is connected with switch tube S 1 Emitter, diode D of (2) 1 Cathode of (c) and reactor L 1 Is connected with one end of reactor L 1 The other end of the diode D is connected with the positive pole of the direct current transmission line 1 The anode of the direct current transmission line is connected with the cathode of the direct current transmission line;
the inversion side direct current short circuit fault current limiting circuit comprises: switch tube S 2 And S is equal to 3 Reactor L 2 Wherein, the positive pole of the inverter of the low voltage treatment device and the switch tube S 2 Is connected with the collector of the switch tube S 3 Emitter connected to, switch tube S 2 Emitter, switch tube S of (2) 3 Collector and reactor L of (c) 2 Is connected with one end of reactor L 2 The other end of the switch tube S is connected with the positive pole of the direct current transmission line 3 The emitter of which is connected with the negative pole of the direct current transmission line.
2. The direct current short circuit fault current limiting circuit of the low voltage treatment device according to claim 1, wherein the rectifying side direct current short circuit fault current limiting circuit adopts a BUCK topology, is connected with a direct current bus of a rectifier and an output direct current port of the rectifier, and realizes the functions of current limiting and voltage reducing of the direct current port when the direct current port has a short circuit fault.
3. The direct current short circuit fault current limiting circuit of the low voltage treatment device according to claim 1, wherein the direct current short circuit fault current limiting circuit of the inversion side adopts BOOST topology, is connected with a direct current bus of an inverter and an input direct current port thereof, and realizes the functions of current limiting, operation with faults and quick recovery after fault removal of the direct current port when the direct current port has a short circuit fault.
4. The direct current short circuit fault current limiting circuit of the low voltage treatment device according to claim 1, wherein the direct current short circuit fault current limiting circuit has long-term overload judging and protecting functions, the fault and the large current under the short-term overload provide important fault information for the judgment of the fault and the action of the protecting device, but the long-term large current works, the temperature rise of the current limiting circuit is unfavorable, and the direct current short circuit fault current limiting circuit can not occur under normal working conditions, so that the low voltage treatment device is triggered to stop after the long-term overload judging condition is met for self protection of equipment.
5. A control method for a dc short-circuit fault current limiting circuit of a low voltage treatment device, which is characterized by being used for controlling the dc short-circuit fault current limiting circuit of the low voltage treatment device according to claim 1, specifically comprising the following steps:
sampling data, namely sampling the current of a reactor L1 and the current of a reactor L2 of a direct current short-circuit fault current limiting circuit;
judging long-time overload, and triggering long-time overload protection to stop the rectifier or the inverter if the current is at a larger value for a long time;
judging the working mode, namely judging that the direct current short circuit fault current limiting circuit is in a normal working mode or a current limiting hysteresis mode according to the current magnitude;
the BOOST mode is used for the BOOST mode of the direct current short circuit fault current limiting circuit at the inversion side, and is used for the operation with faults of the inverter or the rapid BOOST and recovery of the direct current bus of the auxiliary inverter.
6. The method for controlling a direct current short circuit fault current limiting circuit of a low voltage managing device as claimed in claim 5, wherein said long time overload judgment is performed when detecting a current I of a reactor L1 of the rectifying side direct current short circuit fault current limiting circuit L1 Satisfy I L1N ≤I L1 ≤I L1max Or the current I of the reactor L2 of the inversion side direct current short circuit fault current limiting circuit is detected L2 satisfy-I L2_max ≤I L2 ≤I L2_N Duration t OL Time, or the direct current short circuit fault current limiting circuit is in a current limiting hysteresis mode and lasts for t OL And (3) time, performing long-time overload protection operation, and stopping the rectifier or the inverter of the low-voltage treatment device.
7. The control method of the direct current short circuit fault current limiting circuit of the low voltage management device according to claim 5, wherein the switching tube S in the normal operation mode 1 And S is equal to 2 Conduction and switch tube S 3 The low-voltage treatment device is turned off, and the energy bidirectional flow function is still realized.
8. The control method of a low voltage regulator DC short-circuit fault current limiting circuit according to claim 5, wherein said current limiting hysteresis mode employs a current hysteresis control technique, when detecting a current I of the rectifying side DC short-circuit fault current limiting circuit L1 ≥I L1_max Switch tube S 1 Turn off when I is detected L1 <I L1_max -ΔI L1 Switch tube S 1 Conducting; when detecting the current I of the inversion side direct current short circuit fault current limiting circuit L2 ≤-I L2_max Switch tube S 2 Turn off, S 3 Turn off when I is detected L2 >-I L2_max +ΔI L2 Switch tube S 2 Conduction, S 3 And (5) switching off.
9. The method for controlling a direct current short circuit fault current limiting circuit of a low voltage managing apparatus according to claim 5, wherein said BOOST mode is a BOOST mode in which a short circuit fault, V, occurs on a direct current side bus2 ≤V bst Triggering the inverter side direct current short circuit fault current limiting circuit to perform duty ratio calculation and hysteresis current limiting, so that the fault current limiting circuit has certain boosting capacity on the premise of no overcurrent;
the duty cycle calculation formula is:
D＝V in /V N
switch tube S 2 、S 3 Complementary on-off, S 2 Is of duty cycle D, S 3 The duty cycle of (2) is 1-D;
when I is detected L2 ≥I L2_max When the time is over, the hysteresis loop current limit is entered, and the calculation is not performed according to the duty ratioThe result of (2) controlling the switching tube, switching tube S 2 Conduction, S 3 Turn off when I is detected L2 <I L2_max -ΔI L2 When the hysteresis loop is exited, the current is limited;
when V is bus2 ≥V nor -ΔV bus2 When the system is in the BOOST mode, the system exits the BOOST mode and enters the normal working mode; when V is bus2 <V min And when the BOOST mode is exited, stopping the inverter.
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|---|---|---|---|---|
| CN205724912U (en) * | 2016-04-19 | 2016-11-23 | 北京英博电气股份有限公司 | A kind of rural power grids low-voltage controlling device |
| CN208986607U (en) * | 2018-11-16 | 2019-06-14 | 国网山西省电力公司临汾供电公司 | A kind of low-voltage network three-phase line low-voltage governing system |
| CN112615381A (en) * | 2020-12-12 | 2021-04-06 | 青岛鼎信通讯股份有限公司 | Device is administered to terminal low voltage of distributing type low voltage distribution network |
| CN113113930A (en) * | 2020-09-27 | 2021-07-13 | 青岛鼎信通讯股份有限公司 | Single-phase-locked loop method applied to low-voltage treatment equipment |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US20120120697A1 (en) * | 2010-11-13 | 2012-05-17 | Cuks, Llc. | Three-phase isolated rectifer with power factor correction |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN205724912U (en) * | 2016-04-19 | 2016-11-23 | 北京英博电气股份有限公司 | A kind of rural power grids low-voltage controlling device |
| CN208986607U (en) * | 2018-11-16 | 2019-06-14 | 国网山西省电力公司临汾供电公司 | A kind of low-voltage network three-phase line low-voltage governing system |
| CN113113930A (en) * | 2020-09-27 | 2021-07-13 | 青岛鼎信通讯股份有限公司 | Single-phase-locked loop method applied to low-voltage treatment equipment |
| CN112615381A (en) * | 2020-12-12 | 2021-04-06 | 青岛鼎信通讯股份有限公司 | Device is administered to terminal low voltage of distributing type low voltage distribution network |
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