CN114221304B - Low-voltage direct-current distribution network source network load cooperative protection strategy based on solid-state circuit breaker - Google Patents
Low-voltage direct-current distribution network source network load cooperative protection strategy based on solid-state circuit breaker Download PDFInfo
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- CN114221304B CN114221304B CN202110617089.6A CN202110617089A CN114221304B CN 114221304 B CN114221304 B CN 114221304B CN 202110617089 A CN202110617089 A CN 202110617089A CN 114221304 B CN114221304 B CN 114221304B
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- 238000001514 detection method Methods 0.000 claims abstract description 6
- 238000005192 partition Methods 0.000 claims description 8
- 239000007787 solid Substances 0.000 claims description 3
- 238000000034 method Methods 0.000 claims description 2
- 238000012544 monitoring process Methods 0.000 abstract description 2
- 238000012545 processing Methods 0.000 abstract description 2
- 230000002457 bidirectional effect Effects 0.000 abstract 1
- 239000004065 semiconductor Substances 0.000 abstract 1
- 230000001502 supplementing effect Effects 0.000 abstract 1
- 238000010521 absorption reaction Methods 0.000 description 4
- 238000011161 development Methods 0.000 description 4
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- 238000003745 diagnosis Methods 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 239000013589 supplement Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
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- 238000009792 diffusion process Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
- H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
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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
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/14—Balancing the load in a network
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Remote Monitoring And Control Of Power-Distribution Networks (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The on-line current monitoring module is responsible for collecting direct current of each detection point in real time, transmitting current data to a superior system, analyzing and processing the data by an upper computer and then transmitting an instruction back to a fault recognition system. And judging the out-of-zone faults, the in-zone low-resistance faults and the in-zone high-resistance faults by the fault identification system. The main switch branch is composed of a semiconductor device IGBT and diodes D1 and D2 to normally conduct current, the left IGBT and D2 conduct current when the current flows from S1 to S2, and the right IGBT and D1 conduct current when the current flows from S2 to S1, so that bidirectional switching can be conducted. And after the fault is removed, calculating the load removal quantity after the fault occurs through load calculation auxiliary decision, and supplementing the cut load by a scheduling system to realize multi-source coordination control.
Description
Technical Field
The invention relates to a novel low-voltage direct current distribution network source network load cooperative protection strategy based on a solid-state circuit breaker, which is characterized in that a shutdown instruction is issued to the circuit breaker through a protection system after a fault occurs, direct current blocking is carried out in real time, load removal amount after the fault occurs is calculated through load calculation auxiliary decision, and then the cut load is supplemented by a dispatching system, so that multi-source coordination control is realized, the purposes of load dispatching and regional interconnection are achieved, adverse effects caused by load removal can be greatly reduced, and the power supply reliability is improved.
Background
In recent years, with the rapid development of new energy power generation technology, energy storage devices and other direct current technologies, a direct current distribution network has become a powerful development object in the power industry. The most critical requirements for dc distribution networks are reliability and safety, so a reliable and fast protection system is important for ensuring safe operation of dc distribution networks. To accomplish this goal, the studies currently being conducted are largely divided into three directions: protection equipment, fault diagnosis and protection strategies.
The development of the direct current circuit breaker has great significance for guaranteeing the safe operation of the direct current distribution network, fault current can be effectively removed, current diffusion is restrained, and the normal operation of direct current distribution equipment is guaranteed. At present, the research of the direct current circuit breaker is mainly in the field of medium-high voltage direct current transmission, and the research in the field of low voltage distribution is less. The main circuit breakers at present are mechanical direct current circuit breakers which are most widely used; the hybrid circuit breaker fully utilizes the advantages of small on-state loss of the mechanical switch and turn-off of the power electronic device; there are also solid state dc breakers that are emerging with the development of power electronics technology. The solid-state circuit breaker has the advantages of high reliability, short on-off time, low technical difficulty and the like, so the solid-state circuit breaker becomes an important research direction of the low-voltage direct-current distribution circuit breaker. For fault diagnosis and protection strategies of the direct-current distribution network, because the direct-current distribution network integrates a large number of distributed renewable energy sources, matched energy storage devices and the like, the network structure is relatively complex, and therefore, after faults occur, fault currents of all branches have quite large uncertainty, and fault sections are difficult to accurately position. And after the fault is removed, overall configuration is not carried out, so that the power consumption of a load side user is generally influenced, and the power supply reliability of the direct current distribution network is reduced. Under the application background, the power distribution network source network load cooperative protection strategy should control the cut-off load, and the scheduling system supplements the cut-off load, so that the adverse effect caused by load cut-off can be greatly reduced, and the power supply reliability is improved.
Disclosure of Invention
Aiming at the defects or drawbacks of the prior art, the invention aims to realize the cooperative protection of the source network load of the low-voltage direct current distribution network by using a solid-state circuit breaker. Through designing novel protection strategy, can discern fast and excision trouble when the distribution network breaks down, supplement through dispatch load crowd, reduce the adverse effect that load excision caused the user, the supply reliability of the direct current distribution network of furthest guarantee.
Specifically, the invention adopts the following technical scheme:
the direct current of each detection point is collected in real time, and whether faults occur in the area is judged based on direct current fault identification of double-slope longitudinal differences; after judging that the fault occurs, the system calculates a fault current value to judge whether overcurrent exists or not and determine the fault current direction; when the existence of overcurrent is judged at present, the rapid protection devices in each protection partition send the detected fault current direction to the adjacent rapid protection devices in the partition; and then, each protection device identifies a fault occurrence section after the fault current direction of each detection point in the comprehensive protection zone. After the fault area is locked, the protection system issues a turn-off instruction to the circuit breaker, the solid-state circuit breaker signal processing unit receives the turn-off instruction sent by the protection system, and then the communication unit sends a turn-off signal to the IGBT which is in forward through flow, and the IGBT rapidly responds and turns on the fault. And the load cutting-off amount after the faults is calculated through load calculation auxiliary decision, and then the cut-off load is supplemented by the dispatching system, so that the multi-source coordination control is realized, and the purposes of load dispatching and regional interconnection are achieved.
Drawings
FIG. 1 is a block diagram of a switching station DC distribution network system;
fig. 2 is a schematic view of a circuit breaker body structure;
FIG. 3 is a cooperative protection policy control block diagram of the present invention;
fig. 4 (a) to 4 (c) are schematic diagrams of the circuit breaker operation.
Detailed Description
Specific embodiments of the present invention are described below with reference to fig. 1 to 4 (c).
(1) In the normal through-current state as shown in fig. 4 (a), the system current flows into the left IGBT from the incoming terminal S1 and flows out from the outgoing terminal S2 through the diode D2;
(2) The current change condition of the circuit is monitored in real time through a current monitoring unit in the circuit shown in fig. 1, current data is transmitted to a superior system, and an instruction is transmitted back to a fault identification system after the data is analyzed and processed by an upper computer.
(3) Judging whether a fault occurs in the area based on a direct current fault identification scheme of the double-slope longitudinal difference, and after judging that the fault occurs, calculating a fault current value and determining a fault current direction by the system; comparing the collected fault current value with an overcurrent limiting value, and judging that overcurrent exists if the current fault current value exceeds the overcurrent limiting value;
(4) If the current is judged to be over-current, the rapid protection devices in each protection partition in the figure 1 send the detected fault current direction to the adjacent rapid protection devices in the partition; then, each protection device identifies a fault occurrence section after the fault current direction of each detection point in the comprehensive protection zone;
(5) As shown in fig. 4 (b), after the fault area is locked, the protection system sends a switching-off instruction to the circuit breaker shown in fig. 2, the circuit breaker communication unit sends a switching-off signal to the left full-control power electronic device according to the current direction, the main switch branch is disconnected, and the buffer capacitor absorbs fault current and voltage to continuously rise;
(6) When the voltage across the circuit breaker exceeds the conduction threshold of the absorption leg, the absorption leg is turned on as shown in fig. 4 (c). Because the on-state resistance of the absorption branch is very small, the current is quickly transferred to the absorption branch, and the whole switching-on and switching-off process is completed when the fault current is reduced to zero;
(7) Finally, the load cutting-off amount after the fault is calculated through load calculation auxiliary decision by the cooperative protection strategy shown in fig. 3, and the cut-off load is supplemented by the dispatching system for carrying out interrupt load control, so that the purposes of load dispatching and regional interconnection are achieved.
Claims (1)
1. A low-voltage direct current distribution network source network load cooperative protection method based on a solid-state circuit breaker is characterized by comprising the following steps:
(1) The direct current of each detection point is collected in real time, and whether faults occur in the area is judged based on direct current fault identification of double-slope longitudinal current differential;
(2) After judging that the fault occurs, calculating a fault current value, judging whether overcurrent occurs or not, and determining a fault current direction;
(3) If the current is judged to be over-current, the rapid protection devices in each protection partition send the detected fault current direction to the adjacent rapid protection devices in the protection partition;
(4) Then, the rapid protection device in each protection partition synthesizes the fault current direction of each detection point in the protection partition and then identifies the fault occurrence section;
(5) After the fault occurrence section is locked, a turn-off instruction is issued to the solid state circuit breaker, and the solid state circuit breaker rapidly responds and turns on the fault.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110617089.6A CN114221304B (en) | 2021-06-03 | 2021-06-03 | Low-voltage direct-current distribution network source network load cooperative protection strategy based on solid-state circuit breaker |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110617089.6A CN114221304B (en) | 2021-06-03 | 2021-06-03 | Low-voltage direct-current distribution network source network load cooperative protection strategy based on solid-state circuit breaker |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114221304A CN114221304A (en) | 2022-03-22 |
| CN114221304B true CN114221304B (en) | 2024-01-23 |
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| CN202110617089.6A Active CN114221304B (en) | 2021-06-03 | 2021-06-03 | Low-voltage direct-current distribution network source network load cooperative protection strategy based on solid-state circuit breaker |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202455055U (en) * | 2012-01-19 | 2012-09-26 | 无锡市科环自动化设备有限公司 | Current selective tripping and large-zone power supply protecting system of rail transit power supply system |
| CN104810807A (en) * | 2015-04-02 | 2015-07-29 | 南方电网科学研究院有限责任公司 | 10kV power distribution network hybrid high-voltage direct-current circuit breaker |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10928794B2 (en) * | 2018-01-05 | 2021-02-23 | Emera Technologies LLC | Fault detection systems and methods for power grid systems |
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2021
- 2021-06-03 CN CN202110617089.6A patent/CN114221304B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202455055U (en) * | 2012-01-19 | 2012-09-26 | 无锡市科环自动化设备有限公司 | Current selective tripping and large-zone power supply protecting system of rail transit power supply system |
| CN104810807A (en) * | 2015-04-02 | 2015-07-29 | 南方电网科学研究院有限责任公司 | 10kV power distribution network hybrid high-voltage direct-current circuit breaker |
Non-Patent Citations (1)
| Title |
|---|
| 考虑直流固态断路器通态压降的低压直流配电网最优潮流;马骏超;江全元;赵宇明;;电力系统自动化(第05期);全文 * |
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| CN114221304A (en) | 2022-03-22 |
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