KR102617970B1 - System for protection management of lvds distribution and method for protection management - Google Patents

Abstract

Provides protection management systems and protection management methods for low-voltage direct current distribution systems. The protection management system for the low-voltage direct current distribution system sets each protection section for each low-voltage direct current distribution system that supplies power from the system power terminal to at least one load and distributed power terminal, and for each distribution line formed in the low-voltage direct current distribution system, and protects each. A relay device for relaying relay elements of distribution lines for each section, at least one wireless repeater for wirelessly transmitting relay results for distribution lines for each protection section, and blocking or blocking fault current according to the relay results for each protection section. It includes a protection management device that corrects the operating standards for protection relaying between each protection section.

Description

Protection management system and protection management method of low-voltage direct current distribution system {SYSTEM FOR PROTECTION MANAGEMENT OF LVDS DISTRIBUTION AND METHOD FOR PROTECTION MANAGEMENT}

The present invention relates to a protection management system and protection management method for a low-voltage direct current distribution system.

Demand for the low voltage direct current (LVDC) distribution system has decreased because it has been difficult to supply power on a city scale due to the short transmission distance. However, recently, advantages such as increased transmission capacity, reduced transmission loss, low environmental impact, and reduced investment costs have emerged, and it is receiving attention again due to the rapid increase in digital loads using DC power.

The demand for low-voltage direct current distribution systems is increasing as voltage can be changed through DC/DC converters as power electronics technology advances, and digital devices such as computers and network devices are used explosively.

The low-voltage direct current distribution system includes a DC breaker (Direct Current circuit breaker) to block the fault current when a direct current transmission line failure occurs due to a short circuit, ground fault, or overcurrent. The DC breaker opens and blocks the fault current to prevent it from affecting the normal system when a fault current occurs.

Conventionally, when a fault current occurs, an operation is performed to cut off the entire system, including distribution lines, branched lines, and load wiring, within the shortest period of time. For this purpose, many high-speed semiconductor type DC circuit breakers that eliminate faults within a few milliseconds have been deployed on DC distribution lines.

However, if all branched lines or load wiring, including the distribution line, are blocked due to a fault current, excessive recovery time and recovery manpower are required, and the reliability and efficiency of the low-voltage DC distribution system are reduced due to an overall power outage. do. Accordingly, in recent years, efforts have been required to increase the efficiency and stability of low-voltage direct current distribution systems.

The problem to be solved by the present invention is to provide a protection management system and protection management method for a low-voltage direct current distribution system that can set a protection section for each distribution line to block fault current for each protection section or correct operating standards for protective relaying. will be.

The problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by those skilled in the art from the description below.

A protection management system for a low-voltage direct current distribution system according to one aspect of the present invention to solve the above-described problem is a low-voltage direct current distribution system that supplies power from the system power source to at least one load and distributed power source, and a low-voltage direct current distribution system. A relay device that sets each protection section for each formed distribution line and relays relay elements of the distribution lines for each protection section, at least one wireless repeater device that wirelessly transmits relay results for the distribution lines for each protection section, and It includes a protection management device that blocks fault current or corrects operating standards for protective relaying between each protection section according to the relay results for each protection section.

A low-voltage direct current distribution system according to an embodiment includes an AC/DC rectifier that rectifies and modulates the power of the system power terminal and outputs it, a first protective relay breaker that blocks or protectively relays the power at the input terminal of the AC/DC rectifier, and an AC/DC A first DC/DC converter that modulates the distribution power distributed through a rectifier into direct current power of a preset size, a second protective relay breaker that blocks or protectively relays the power at the input terminal of the first DC/DC converter, and a first DC/DC A third protective relay breaker that blocks or protectively relays the power to the output terminal of the converter, and a fourth protective relay that is disposed between the output terminal of the first DC/DC converter and the first load input terminal to block or protectively relay the power distributed to the first load. May include a circuit breaker.

The protection management device according to an embodiment sets each protection section for each main line, at least one branch line, at least one distribution line, and at least one load line formed in the low-voltage direct current distribution system, and inputs in real time It includes a data processing unit that identifies a protection section corresponding to the relay result. In addition, a protection device identification unit that identifies the protection relay breakers included in the protection section identified by the data processing unit among the protection relay breakers placed in each protection section, and a protection relay for each protection section by monitoring the occurrence of a fault current. It further includes a set value correction unit that controls the blocking operation of the circuit breaker or corrects the operating standards of the protective relay circuit breakers in real time according to relay results.

The protection management method of a low-voltage direct current distribution system according to one aspect of the present invention to solve the above-described problem includes the steps of setting each protection section for each distribution line formed in the low-voltage direct current distribution system, and each protection section set through a measuring device. Relaying the relay elements of each distribution line, wirelessly transmitting the relay results for the distribution lines for each protection section to the protection management device, and blocking the fault current according to the relay result for each protection section or between each protection section. It includes the step of controlling the relay by correcting the operating standards for the protective relay.

The protection management system and protection management method of a low-voltage direct current distribution system according to an embodiment of the present invention can set a protection section for each distribution line to block fault current for each protection section or correct operating standards for protection relay. Therefore, even if a high-speed semiconductor type DC breaker is not used, the fault current can be blocked or the operating standards can be corrected for each protection section by using a general DC breaker for a protection relay.

In addition, the protection management system and protection management method of the low-voltage direct current distribution system according to an embodiment of the present invention provide a protection section for each line, such as the main line connected to the busbar, the branch line branched from the main line, and the load line connected to the loads. Set it. In addition, the fault current can be blocked or the operating standards can be corrected for each protection section. Accordingly, overall power outages can be prevented, each protection section can be restored quickly, and the operating standards for protection relays for each protection relay or DC breaker can be corrected and set in real time.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

Figure 1 is a block diagram showing a protection management system for a low-voltage direct current distribution system according to an embodiment of the present invention.
FIG. 2 is a block diagram specifically illustrating the protection management device shown in FIG. 1.
FIG. 3 is a circuit diagram showing an example of a current limiting circuit of the AC/DC rectifier shown in FIG. 1.
FIG. 4 is a graph showing the change in fault current applied to the AC/DC rectifier shown in FIG. 3.
FIG. 5 is a circuit diagram showing an example of a current-limiting circuit of the DAB type DC/DC converter shown in FIG. 1.
FIG. 6 is a graph showing the change in fault current applied to the DAB type DC/DC converter shown in FIG. 5.
FIG. 7 is a block diagram showing an example of protection section settings for each line of the low-voltage direct current distribution system shown in FIG. 1.
FIG. 8 is a flowchart sequentially showing the DC breaker identification operation for each line of the protection management device shown in FIG. 2.
FIG. 9 is a block diagram for explaining a control operation according to the occurrence of a fault current in the first protection section of the low-voltage direct current distribution system shown in FIG. 7.
FIG. 10 is a block diagram for explaining a control operation according to the occurrence of a fault current in the second protection section of the low-voltage direct current distribution system shown in FIG. 7.
FIG. 11 is a block diagram for explaining a control operation according to the occurrence of a fault current in the third protection section of the low-voltage direct current distribution system shown in FIG. 7.
FIG. 12 is a block diagram for explaining a control operation according to the occurrence of a fault current in the fourth protection section of the low-voltage direct current distribution system shown in FIG. 7.
FIG. 13 is a block diagram for explaining a control operation according to the occurrence of a fault current in the fifth protection section of the low-voltage direct current distribution system shown in FIG. 7.
Figure 14 is a block diagram showing the configuration of a low-voltage direct current distribution system and an example of protection section settings for each line according to another embodiment of the present invention.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. The present embodiments are merely provided to ensure that the disclosure of the present invention is complete and to provide a general understanding of the technical field to which the present invention pertains. It is provided to fully inform the skilled person of the scope of the present invention, and the present invention is only defined by the scope of the claims.

The terminology used herein is for describing embodiments and is not intended to limit the invention. As used herein, singular forms also include plural forms, unless specifically stated otherwise in the context. As used in the specification, “comprises” and/or “comprising” does not exclude the presence or addition of one or more other elements in addition to the mentioned elements. Like reference numerals refer to like elements throughout the specification, and “and/or” includes each and every combination of one or more of the referenced elements. Although “first”, “second”, etc. are used to describe various components, these components are of course not limited by these terms. These terms are merely used to distinguish one component from another. Therefore, it goes without saying that the first component mentioned below may also be a second component within the technical spirit of the present invention.

Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used with meanings commonly understood by those skilled in the art to which the present invention pertains. Additionally, terms defined in commonly used dictionaries are not interpreted ideally or excessively unless clearly specifically defined.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

Figure 1 is a block diagram showing a protection management system for a low-voltage direct current distribution system according to an embodiment of the present invention.

The protection management system of the low-voltage direct current distribution system shown in FIG. 1 includes a low-voltage direct current distribution system 100 that distributes the power of the power system to the first load 21 and the first distributed power supply terminal 12, and a relay for each distribution line. It includes a relay device 200 for relaying elements, a wireless relay device 300 for wirelessly transmitting relay results, and a protection management device 500 for blocking fault currents or correcting operating standards for protective relaying between distribution lines. do.

The low-voltage direct current distribution system 100 modulates the power of the power system, that is, the system power terminal 10, into direct current power and distributes it to at least one first load 21 and the first distributed power terminal 12. To this end, the low-voltage direct current distribution system 100 may include at least one AC/DC rectifier 101, at least one DC/DC converter 104 and 108, and a plurality of protective relay circuit breakers 102, 103, 105, 106 and 107.

The low-voltage direct current distribution system 100 is a means for rectifying and distributing power from the system power terminal 10, and may include at least one AC/DC rectifier 101 and a first protective relay circuit breaker 102. Here, the AC/DC rectifier 101 rectifies the power of the system power supply terminal 10 through a rectifier circuit with current limiting characteristics and outputs it to the main line such as a busbar. In addition, the first protective relay breaker 102 is provided with a DC breaker for a protective relay, and can protect the input or output terminal power of the AC/DC rectifier 101 or block it to protect the AC/DC rectifier 101. .

In addition, the low-voltage direct current distribution system 100 is a means for modulating direct current power rectified through the AC/DC rectifier 101 into direct current power of a preset size and distributing it to the first load 21, It may further include a DC/DC converter 104 and second to fourth protective relay circuit breakers (103, 105, and 106). Here, the first DC/DC converter 104 can modulate the distribution power output through the AC/DC rectifier 101 of the main line into DC power of a preset size and distribute it to each branch line. In addition, the second protective relay breaker 103 may protectively relay or block the power at the input terminal of the first DC/DC converter 104 at the input terminal of the first DC/DC converter 104. On the other hand, the third protective relay breaker 105 may protectively relay or block the output power of the first DC/DC converter 104 output from the output terminal of the first DC/DC converter 104 to the distributed line. In addition, the fourth protective relay circuit breaker 106 is disposed on the load line at the input terminal of the first load 21, and relays the load power distributed to the first load 21 according to the control of the protection management device 500. You can do this or block it.

Additionally, the low-voltage direct current distribution system 100 is a means for distributing distribution power distributed from the main line to the first distributed power terminal 12 or supplying distributed power from the first distributed power terminal 12 to the main line. , It may further include a second DC/DC converter 108 and a fifth protective relay breaker 107. Here, the second DC/DC converter 108 modulates the distribution power output through the AC/DC rectifier 101 of the main line into DC power of a preset size and supplies it to the first distributed power supply terminal 12, or Power from the first distributed power supply terminal 12 may be supplied to the main line or another branch line (for example, the input terminal of the first DC/DC converter 104). Here, the fifth protective relay breaker 107 is disposed at the input terminal or output terminal of the second DC/DC converter 108, and is connected to the input terminal or output terminal of the second DC/DC converter 108 according to the control of the protection management device 500. The output terminal power can be protectively relayed or blocked.

At least one relay device 200 is provided for each protection section divided by distribution lines (e.g., main line, branch line, distribution line, load line, etc.) of the low-voltage DC distribution system 100, and the corresponding distribution line. Relay relay elements for these elements. And, the relay results for the distribution lines for each protection section are transmitted to the protection management device 500 through the wireless relay device 300. As an example, each protection section may be divided and set for a main line, at least one branch line, a distribution line, and at least one load line.

Specifically, the relay device 200 determines the voltage magnitude, current amount, and current direction, which are relay elements in the distribution lines for each protection section, according to the detection control signal of the protection management device 500 input through the wireless relay device 300. Information, etc. is detected and transmitted to the protection management device 500. At this time, the relay device 200 may correct and relay the relay elements of the distribution lines for each protection section based on the operation standard value set and corrected by the protection management device 500. And, protective relay circuit breakers 102, 103, 105, 106, and 107 formed on each distribution line (i.e., main line, at least one branch line, distribution line, and at least one load line) in response to the operation standard set by the protection management device 500. The TCC (Time Current Curve) operating characteristics can be corrected (Setting).

In addition, the relay device 200 selectively controls the protection relay circuit breakers 102, 103, 105, 106, and 107 formed on each distribution line in response to a blocking control signal from the protection management device 500, thereby selectively blocking the distribution lines. . That is, the relay device 200 selectively blocks the first to fifth protective relay circuit breakers 102, 103, 105, 106, and 107 in response to the blocking control signal, thereby selectively blocking direct current power transmitted to the main line, branch line, load line, etc. You can.

At least one wireless relay device 300 includes at least one wireless communication module, such as a short-range wireless communication module such as Wi-Fi, Bluetooth, or ZigBee, and a long-distance wireless communication module such as LTE or 5G. This wireless relay device 300 transmits relay results for distribution lines for each protection section relayed through at least one relay device 200 to the protection management device 500. In addition, the operation reference value, blocking control signal, relay element information, etc. of the relay device 200 received from the protection management device 500 are transmitted to each relay device 200 and the protection relay circuit breakers 102, 103, 105, 106, 107, etc.

The protection management device 500 divides each protection section for each distribution line formed in the low-voltage direct current distribution system 100 and sets relay elements for each distribution line in each protection section. Each protection section may be set as a section according to the main line, the first and second branch lines, at least one distributed line, and at least one load line (or a line connecting the first load 21). The protection management device 500 sequentially analyzes the relay results for the distribution lines for each protection section received from the relay device 200 with the operation standard value to block the fault current for each distribution line in each protection section or perform an operation for protection relay. Standard values can be corrected.

Specifically, the protection management device 500 controls the relay operation of the relay device 200 by setting relay elements for each distribution line in each protection section. At this time, the protection management device 500 may set the voltage magnitude, current amount, and current direction information for the distribution lines for each protection section as relay elements and transmit them to the relay device 200.

The protection management device 500 identifies the protection relay breakers 102, 103, 105, 106, and 107 arranged in each protection section in order for each protection section. In addition, the occurrence of fault currents such as overcurrent, overvoltage, or low voltage is monitored by comparing and analyzing the voltage magnitude, current amount, and current direction information for each protection section with the operation standard value. And, when a fault current occurs, a blocking control signal is transmitted to the relay device 200 or the corresponding protective relay breaker so that the protective relay breaker in the protection section where the fault current occurs is blocked. Accordingly, the protection management device 500 may perform a blocking operation according to the occurrence of a fault current for each pre-divided protection section.

In contrast, the protection management device 500 analyzes the relay results (voltage magnitude, current amount, current direction information, etc.) for the distribution lines for each protection section and sets the operating standards of the protection relay circuit breakers 102, 103, 105, 106, and 107 formed in each distribution line. can be corrected. That is, the protection management device 500 sequentially corrects the operation standard value for each protection section and provides it to the relay device 200 and the protection relay breakers (102, 103, 105, 106, and 107), so that the protection relay breaker ( 102, 103, 105, 106, 107) operating standards are corrected. Accordingly, the protection management device 500 can ensure protection cooperation between protection sections by the protection relay breakers 102, 103, 105, 106, and 107 according to the power change characteristics for each protection section.

The operating reference values for the protective relay circuit breakers (102, 103, 105, 106, and 107) may include the TCC (Time Current Curve) operation characteristic correction value, overcurrent setting value, overvoltage setting value, and low voltage setting value of each protective relay circuit breaker (102, 103, 105, 106, 107). Here, the method of correcting the TCC operation characteristics for each protective relay circuit breaker (102, 103, 105, 106, and 107) is a method of setting and correcting the definite, inverse time-delay, or instantaneous curve-type operation characteristics. This can be applied.

FIG. 2 is a block diagram specifically illustrating the protection management device shown in FIG. 1.

Referring to FIG. 2, the protection management device 500 includes a data processing unit 501, a protection device identification unit 502, a database 503, a protection device change setting unit 504, and a setting value correction unit 505. Includes.

Specifically, the data processing unit 501 sets each protection section for each main line, at least one branch line, at least one distribution line, and at least one load line formed in the low-voltage direct current distribution system 100. Then, when a relay result including at least one of voltage magnitude, current amount, and current direction information is input from the relay device 200, each protection section corresponding to the input relay result is identified.

In order to identify each protection section, the data processing unit 501 receives topology information, impedance information, power capacity information, and rated capacity for electrical devices for each protection section, for example, protection relay breakers, etc., from the database 503. Information, Korean wave information, etc. are provided. In addition, the data processing unit 501 compares the voltage magnitude, current amount, and current direction information of a protection section input in real time with the topology information, impedance information, power capacity information, rated capacity information, and current limitation information for each protection relay breaker, etc. , identify the corresponding protection section according to the relay and comparison results.

When the corresponding protection section is identified in the data processing unit 501, the protection device identification unit 502 is included in the protection section identified in the data processing unit 501 among the protection relay breakers 102, 103, 105, 106, and 107 arranged in each protection section. Identify at least one protective relay circuit breaker. At this time. The protection device identification unit 502 compares the voltage magnitude, current amount, and current direction information of a protection section input in real time with the topology information, impedance information, power capacity information, rated capacity information, and current limit information for each protection relay breaker, etc. , at least one protective relay breaker can be identified according to the comparison result.

[Table 1]

Table 1 shows capacity and parameter information for each DC/DC converter (104, 108), including the AC/DC rectifier (101) provided with each protection section.

Referring to Table 1, the database 503 includes each protection relay circuit breaker (102, 103, 105, 106, 107) and at least one electrical device (e.g., rectifier, converter, load, distributed power source, battery, breaker) disposed in each protection section. and switches, etc.) are stored and shared with the data processing unit 501 and the protection device identification unit 502. As an example, the database 503 includes topology information (e.g., connection relationship information, busbar-equipment information), impedance (R, L, C) for the protection relay circuit breakers or electrical devices placed in each protection section. At least one of information, power capacity information, distance or length information, rated capacity information, current limitation information, and opening/closing operation information can be stored and shared.

The protection device change setting unit 504 compares the operation characteristics of the protective relay breaker identified in the protection device identification unit 502 with the relay result detected through the relay device 200 to identify the data processing unit 501 and the protection device. Check whether the unit 502 is identified normally. If the operation characteristics of the protection relay breaker identified in the protection device identification unit 502 and the relay result detected by the relay device 200 are different, the protection device change setting unit 504 re-identifies the protection section and the protection relay breaker. The action can proceed. Accordingly, the data processing unit 501 and the protection device identification unit 502 can re-identify the corresponding protection section and protection relay breaker, etc. according to the relay result re-entered in real time.

The set value correction unit 505 monitors whether a fault current occurs and controls the blocking operation of the protection relay breaker for each protection section. In addition, the set value correction unit 505 analyzes the relay results (voltage magnitude, current amount, current direction information, etc.) for the distribution lines for each protection section and operates the protective relay circuit breakers 102, 103, 105, 106, and 107 formed on each distribution line. Reference values can be corrected and reset. The operation standard value correction technology for each protective relay circuit breaker (102, 103, 105, 106, and 107) of the set value correction unit 505 will be described in detail later with reference to the attached drawings.

FIG. 3 is a circuit diagram showing an example of a current limiting circuit of the AC/DC rectifier shown in FIG. 1. And, FIG. 4 is a graph showing the change in fault current applied to the AC/DC rectifier shown in FIG. 3.

Referring to FIG. 3, the AC/DC rectifier 101 according to an embodiment rectifies and converts the power of the system power supply terminal 10 to direct current through a rectifier circuit with current limiting characteristics and outputs it to the main line such as a bus bar. do. For this purpose, the AC/DC rectifier 101 includes at least one protection switching element (T1) connected in series to the system power terminal 10 through the first switching element (SW1), and in series and parallel to the output terminal of the protection switching element (T1). It may include a combination of direct current conversion elements (L, C), at least one rectifier diode (D), and a rectifier output element (SW2). The circuit structure of the AC/DC rectifier 101 including a rectifier circuit with current limiting characteristics is not limited to the example shown in FIG. 3. The circuit structure of the AC/DC rectifier 101 can be applied to various AC/DC circuits designed to perform AC/DC conversion and rectification operations.

As an example, the AC/DC rectifier 101 may include power electronics-based switching elements (SW1, SW2) and impedance elements (L, C), and these switching elements (SW1, SW2) and impedance elements (L ,C) are weak in durability against large fault currents. Accordingly, it generally includes a protective fuse or a protective switching element (T1) inside, and a current-limiting circuit can be configured to limit the expected large fault current to about 1.5 to 2.0 times the rating. As shown in FIG. 4, the fault current applied to the AC/DC rectifier 101 may be limited to within 1.5 to 2.0 times the rated value.

FIG. 5 is a circuit diagram showing an example of a current-limiting circuit of the DAB type DC/DC converter shown in FIG. 1. And, FIG. 6 is a graph showing the change in fault current applied to the DAB type DC/DC converter shown in FIG. 5.

Referring to FIG. 5, the first and second DC/DC converters 104 and 108 modulate the distribution power distributed to the main line through the AC/DC rectifier 101 into direct current power of a preset size or level to be converted to branch lines or It can be output to load lines, etc. To this end, at least one DC/DC converter (104, 108) is formed as a dual active bridge (DAB) type and can be arranged to perform a current limiting function. As an example, at least one DC/DC converter (104, 108) includes a bridge-type first inverter (T1 to T4) and a bridge-type second inverter (T5 to T8) arranged with the impedance elements (L, C) to connect the transformer, etc. By being connected in parallel, the current-limiting function is performed. The circuit structure of the DC/DC converters 104 and 108 including a bridge circuit with current limiting characteristics is not limited to the example shown in FIG. 5, and various DC/DC circuits or devices designed to perform DC/DC conversion operations can be applied. possible. Accordingly, as shown in FIG. 6, like the AC/DC rectifier 101, the fault current applied to the DC/DC converters 104 and 108 may be limited to within 1.5 to 2.0 times the rating.

FIG. 7 is a block diagram showing an example of protection section settings for each line of the low-voltage direct current distribution system shown in FIG. 1.

Referring to FIG. 7, the data processing unit 501 of the protection management device 500 can classify and set protection sections for each main line, each branch line, and each load line formed in the low-voltage direct current distribution system 100.

For example, the data processing unit 501 may set the distribution line at the output stage of the AC/DC rectifier 101, which rectifies and converts the power of the system power terminal 10 into direct current and outputs it, as the bus bar and main line (①). And, the data processing unit 501 is connected to the distribution line of the first protective relay circuit breaker 102 connected to the AC/DC rectifier 101, the input terminal of the first DC/DC converter 104 connected to the main line ①, and the second The distribution line between the protective relay circuit breaker 103, and the distribution line between the input terminal of the second DC/DC converter 108 connected to the main line (①) and the fifth protective relay circuit breaker 107 are connected to each first branch line (②) ) can be set.

Additionally, the data processing unit 501 may set the distribution line between the output terminal of the first DC/DC converter 104 and the third protective relay breaker 105 as the second branch line (③). The distribution line between the output terminal of the first DC/DC converter 104 and the fourth protective relay circuit breaker 106, and the distribution line between the fifth protective relay circuit breaker 107 and the distributed power terminal 12 are distributed lines (④). can be set. And, the distribution line between the fourth protective relay circuit breaker 106 and the input terminal of the first load 21 may be set as the load line (⑤).

In this way, the data processing unit 501 sets a protection section for each main line (①), each first and second branch line (②,③), each distribution line (④), and each load line (⑤). And, each protection section can be identified by comparing the voltage magnitude, current amount, and current direction information relayed for each protection section with the topology information, impedance information, and power capacity information of the database 503.

FIG. 8 is a flowchart sequentially showing the DC breaker identification operation for each line of the protection management device shown in FIG. 2.

Referring to Table 2 below along with FIG. 8, first, the data processing unit 501 provides relay results (i.e., voltage magnitude, current amount, and current direction information) in real time through the relay device 200 and the wireless relay device 300. Once input, power capacity information and topology information for the protection relay circuit breakers placed in each protection section are read. (ST1, ST2)

[Table 2]

Table 2 shows examples of operating reference values for the first to fifth protective relay circuit breakers (102, 103, 105, 106, and 107).

Then, the input relay results are selectively compared with the read power capacity information and topology information (ST3). As an example, the real-time input voltage magnitude, current amount, and current direction information is placed on the main line (①). If the current amount and current direction information of the DC/DC converter 104 or AC/DC rectifier 101 are the same, the data processing unit 501 can identify the corresponding protection section according to the relay result as the main line (①). (ST4)

On the other hand, the voltage magnitude, current amount, and current direction information relayed in real time are the same as the operating current amount and current direction information of the second and fifth protective relay circuit breakers (103, 107) arranged on the first or second branch lines (②,③). Then, the data processing unit 501 can identify the corresponding protection section according to the relay result as the first or third branch line (②,③). (ST5)

If the voltage magnitude, current amount, and current direction information relayed in real time are the same as the output current amount and direction information of the first and second DC/DC converters (104.108) arranged in each distribution line (③), the data processing unit ( 501) can identify the corresponding protection section according to the relay result as a distributed line (④). (ST6, ST7)

Likewise, if the real-time relay voltage magnitude, current amount, and current direction information are the same as the operation current amount and direction information of the fourth protective relay breaker 106 arranged on each load line (⑤), the data processing unit 501 relays According to the results, the corresponding protection section can be identified as the load line (⑤). (ST8, ST8)

As described above, the data processing unit 501 sequentially compares relay information input in real time with power capacity information and topology information for electric devices placed in each protection section, and the protection device identification unit 502 Among the protection relay breakers 102, 103, 105, 106, and 107 arranged in each protection section, at least one protection relay breaker included in the identified protection section can be identified in the data processing unit 501. (ST10, ST11)

FIG. 9 is a block diagram for explaining a control operation according to the occurrence of a fault current in the first protection section of the low-voltage direct current distribution system shown in FIG. 7.

Referring to Table 3 below along with FIG. 9, the set point correction unit 505 provides real-time relay voltage magnitude, current amount, and current direction information, as well as protection section information identified in the data processing unit 501, and protection device identification. Unit 502 monitors and analyzes protection relay breaker information included in the identified corresponding protection section. In addition, the set value correction unit 505 monitors the TCC (Time Current Curve) operation characteristics of each protection relay breaker installed in each protection section in real time.

[Table 3]

As a result of analyzing the relay results (voltage magnitude, current amount, current direction information, etc.) for the distribution lines for each protection section, the set value correction unit 505 determines that a fault current has occurred in the bus bar and main line (①). , the main line (①) can be blocked through the protection relay breaker (102) by transmitting a blocking control signal to the first protective relay breaker (102) of the main line (①).

In order to provide consistent protection when a fault current occurs in the main line (①), it is required to block the fault current contributing source by opening or blocking all protective relay circuit breakers in the main line (①).

Tables 4 and 5 below show the operation control characteristics of the first to fifth protective relay breakers (102, 103, 105, 106, and 107) according to the occurrence of fault current in each protection area.

[Table 4]

[Table 5]

Referring to Table 4 and Table 5, the set point correction unit 505 determines the TCC (Time Current Curve) operation characteristics for the first protective relay breaker 102 of the main line (①), for example, for protective relaying. Definite, time-delay, or instantaneous curved operating characteristic correction values may be transmitted to the first protective relay breaker 102.

As an example, referring to Table 6 below, the set point correction unit 505 sets the operation standard value for the relay device 200 to relay relay elements for the low voltage set point, forward/reverse direction information, etc. for the main line (①). It can be reset. In addition, when a fault current occurs in the main line (①), the TCC (Time Current Curve) operation characteristics of the first protective relay breaker (102) of the main line (①) are defined or instantaneous curved. The characteristic correction value can be selected and transmitted to the first protective relay breaker (102).

[Table 6]

Meanwhile, when a fault current occurs, the set value correction unit 505 sets the relay elements for each protection relay breaker (102, 103, 105, 106, 107) in the fault current occurrence section, for example, overcurrent set value, operating reference voltage, phase difference between voltage and current, and overvoltage. The set value and low voltage set value can be selectively corrected and set to each protective relay breaker (102, 103, 105, 106, 107).

As an example, when a fault current occurs, the set value correction unit 505 uses the following equations 1 to 3 to calculate the operation reference current, operation reference voltage, voltage- The phase difference between currents can be changed and set.

[Equation 1]

I _pickup = I _rated ×α

Here, I _pickup is the operating reference current of the protective relay breaker, and I _rated is the rated maximum current. In the case of the protective relay breaker, it is based on the rated capacity of the connected AC/DC rectifier or DC/DC converter, and the load and branch In the case of circuit breakers, the load capacity of the corresponding protection area is referenced. In addition, α is a setting coefficient: 1.0 < α < I _max (PU)?嵐活? It can be set to within. I _max (PU) is the unit value (per unit, PU) of the maximum effective value of fault current penetrating each protective relay breaker calculated by the set point correction unit 505 and is a value with a duration of at least 1 ms or more.

Next, the set value correction unit 505 can change and set the operating reference voltage of each protective relay breaker using Equation 2 below.

[Equation 2]

V _pickup = V _normal ×β

Here, V _pickup is the reference voltage for operation of the protection device (or rectifier/converter), and V _norminal is the nominal voltage at the installation point of the corresponding protection relay breaker. β is a setting coefficient and is set in the range 0 < β < V _norminal (PU).

Additionally, the set point correction unit 505 can change and set the low voltage set point using Equation 2 below.

[Equation 3]

θ _pickup = θ _normal ± γ

Here, θ _pickup is the phase difference between voltage and current of the reverse reference angle of the protective relay breaker. θ _normal is the reference angle just before the event at the installation point of the protective relay breaker. γ is a setting coefficient and can be set in the range of 90 degrees < γ < 180 degrees.

FIG. 10 is a block diagram for explaining a control operation according to the occurrence of a fault current in the second protection section of the low-voltage direct current distribution system shown in FIG. 7.

Referring to Table 3 above along with FIG. 10, the set point correction unit 505 analyzes the relay results (voltage magnitude, current amount, current direction information, etc.) for the distribution lines for each protection section in real time to determine which one You can check the fault current occurring in the first branch line (②).

If it is determined that a fault current has occurred in one of the first branch lines (②), a blocking control signal is transmitted to the fifth protective relay breaker (107) of the first branch line (②) to activate the fifth protective relay breaker ( The first branch line (②) can also be blocked through 107).

On the other hand, the set value correction unit 505 may transmit the TCC operation characteristic correction value for the fifth protective relay breaker 107 of the first branch line (②) to the fifth protective relay breaker 107 for protective relaying. there is.

As an example, as shown in Tables 4 to 6, the set point correction unit 505 is configured to relay relay elements for the low voltage set point, overcurrent set point, etc. for the first branch line (②). You can set operating standards. In addition, when a fault current occurs in the first branch line (②), the TCC (Time Current Curve) operation characteristics of the fifth protective relay breaker 107 of the first branch line (②) are set to instantaneous curved operation characteristics. It can be selected as set and transmitted to the fifth protective relay breaker (107).

FIG. 11 is a block diagram for explaining a control operation according to the occurrence of a fault current in the third protection section of the low-voltage direct current distribution system shown in FIG. 7.

Referring to Table 3 above along with FIG. 11, the set value correction unit 505 analyzes the relay results (voltage magnitude, current amount, current direction information, etc.) for the distribution lines for each protection section in real time to determine which one You can check the fault current occurring in the second branch line (③).

If it is determined that a fault current has occurred in the second branch line (③), a blocking control signal is transmitted to the third protective relay breaker (103) of the second branch line (③) to close the second protective relay breaker (103). It is also possible to block the second branch line (③) through.

In contrast, the set value correction unit 505 transmits the TCC operation characteristic correction value for the second protective relay breaker 103 of the second branch line (③) to the second protective relay breaker 103 for protective relaying. You can.

As an example, as shown in Tables 4 to 6, the set point correction unit 505 sets an operating reference value for the relay device 200 to relay the relay element for the overcurrent set point for the second branch line (③). You can set it. In addition, when a fault current occurs in the second branch line (③), the TCC (Time Current Curve) operation characteristics of the second protective relay breaker (103) of the second branch line (③) are set to instantaneous curved operation characteristics. It can be selected as set and transmitted to the second protective relay breaker (103).

FIG. 12 is a block diagram for explaining a control operation according to the occurrence of a fault current in the fourth protection section of the low-voltage direct current distribution system shown in FIG. 7.

Referring to Table 3 above along with FIG. 12, the set point correction unit 505 analyzes the relay results for the distribution lines for each protection section in real time and can check the fault current occurring in the distributed line (④).

If it is determined that a fault current has occurred in the distribution line (④), a blocking control signal is transmitted to the third protection relay breaker 105 of the distribution line (④) and the distribution line (④) is transmitted through the third protection relay breaker 105. ④) can also be blocked.

In contrast, the set value correction unit 505 may transmit the TCC operation characteristic correction value for the third protective relay breaker 105 of the distributed line ④ to the third protective relay breaker 105 for protective relaying.

As an example, as shown in Tables 4 to 6, the set value correction unit 505 may set an operation standard for the relay device 200 to relay relay elements for overcurrent on the distributed line ④. . In addition, when a fault current occurs in the distribution line (④), the TCC operation characteristics of the third protective relay breaker 105 of the distribution line (④) can be set to the instantaneous curve-type operation characteristic correction value.

FIG. 13 is a block diagram for explaining a control operation according to the occurrence of a fault current in the fifth protection section of the low-voltage direct current distribution system shown in FIG. 7.

Referring to Table 3 above along with FIG. 13, the set point correction unit 505 can check the fault current generated in the load line (⑤) by analyzing the relay results for the distribution lines for each protection section in real time.

If it is determined that a fault current has occurred in the load line (⑤), a blocking control signal is transmitted to the fourth protection relay breaker 106 of the load line (⑤) and the corresponding distributed line ( ④) can also be blocked.

In contrast, the set value correction unit 505 may transmit the TCC operation characteristic correction value for the fourth protective relay breaker 106 of the distributed line ④ to the fourth protective relay breaker 106 for protective relaying.

As an example, as shown in Tables 4 to 6, the set value correction unit 505 may set an operation standard for the relay device 200 to relay relay elements for overcurrent on the distributed line ④. . In addition, when a fault current occurs in the distribution line (④), the TCC operation characteristics of the fourth protective relay breaker 106 of the distribution line (④) can be set to the instantaneous curve-type operation characteristic correction value.

Figure 14 is a block diagram showing the configuration of a low-voltage direct current distribution system and an example of protection section settings for each line according to another embodiment of the present invention.

Referring to FIG. 14, the low-voltage direct current distribution system 100 distributes the distribution power distributed from the main line to the second distributed power terminal 13, or the second distributed power terminal 13. As a means for supplying distributed power to the main line, a third DC/DC converter 132 and a sixth protective relay breaker 131 may be further included.

The third DC/DC converter 132 modulates the distribution power output through the AC/DC rectifier 101 of the main line into direct current power of a preset size and supplies it to the second distributed power terminal 13, or the second distributed power supply terminal 13. Power from the distributed power supply terminal 13 can be supplied to the main line or another branch line (for example, the input terminal of the first DC/DC converter 104). Here, the sixth protective relay breaker 131 is disposed at the input terminal or output terminal of the third DC/DC converter 132, and is connected to the input terminal or output terminal of the third DC/DC converter 132 according to the control of the protection management device 500. The output terminal power can be protectively relayed or blocked.

In addition, the low-voltage direct current distribution system 100 is a means for distributing the direct current power output to the distribution line, which is the output terminal of the first DC/DC converter 104, to the second load 22, and includes a seventh protective relay circuit breaker ( 121) may be further included. Here, the seventh protective relay circuit breaker 121 is disposed on the load line at the input terminal of the second load 22, and protects the load power distributed to the second load 22 according to the control of the protection management device 500. You can do this or block it.

In addition, the low-voltage direct current distribution system 100 is a means for modulating the direct current power rectified through the AC/DC rectifier 101 into direct current power of a preset size and distributing it to the third load 23, and the fourth load 23. It may further include a DC/DC converter 142 and eighth to tenth protective relay circuit breakers (141, 143, and 144). Here, the fourth DC/DC converter 142 can modulate the distribution power output through the AC/DC rectifier 101 of the main line into DC power of a preset size and distribute it to each branch line. In addition, the eighth protective relay breaker 141 may protectively relay or block the power at the input terminal of the fourth DC/DC converter 142 at the input terminal of the fourth DC/DC converter 142. On the other hand, the ninth protective relay breaker 143 may protectively relay or block the output power of the fourth DC/DC converter 142 output from the output terminal of the fourth DC/DC converter 142 to the branch line. In addition, the tenth protective relay circuit breaker 144 is disposed on the load line at the input terminal of the third load 23, and provides protective relay for the load power distributed to the third load 23 under the control of the protection management device 500. You can do this or block it.

The protection management system and protection management method of the low-voltage direct current distribution system according to the embodiment of the present invention configured as described above sets a protection section (① to ⑤) for each distribution line and operates to block the fault current for each protection section or for protective relay. The baseline values can be corrected. Therefore, even if a high-speed semiconductor type DC breaker is not used, the fault current can be blocked or the operating standards can be corrected for each protection section by using a general DC breaker for a protection relay.

In addition, the main line to which the busbar is connected (①), the first and second branch lines branched from the main line (②,③), the distributed line extended from the branch line (④), and the load line connected to the loads (⑤) Set a protection section for each line. In addition, the fault current can be blocked or the operating standards can be corrected for each protection section. Accordingly, overall power outages can be prevented, each protection section can be restored quickly, and the operating standards for protection relays for each protection relay or DC breaker can be corrected and set in real time.

The steps of the method or algorithm described in connection with embodiments of the present invention may be implemented directly in hardware, implemented as a software module executed by hardware, or a combination thereof. The software module may be RAM (Random Access Memory), ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), Flash Memory, hard disk, removable disk, CD-ROM, or It may reside on any type of computer-readable recording medium well known in the art to which the present invention pertains.

Above, embodiments of the present invention have been described with reference to the attached drawings, but those skilled in the art will understand that the present invention can be implemented in other specific forms without changing its technical idea or essential features. You will be able to understand it. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive.

10: System power terminal 100: Low voltage direct current distribution system
101: AC/DC rectifier 102: First protective relay breaker
104: first DC/DC converter 108: second DC/DC converter
200: relay device 300: wireless relay device
500: protection management device 501: data processing unit

Claims (20)

A low-voltage direct current distribution system that supplies power from the system power stage to at least one load and distributed power stage;
a relay device that sets each protection section for each distribution line formed in the low-voltage direct current distribution system and relays relay elements of the distribution lines for each protection section;
At least one wireless relay device that wirelessly transmits relay results for the distribution lines for each protection section; and
It includes a protection management device that blocks fault current or corrects operating standards for protective relaying between each protection section according to the relay results of the relay elements for each protection section,
The low-voltage direct current distribution system is,
An AC/DC rectifier that rectifies and modulates the power of the system power terminal and outputs it;
A first protective relay circuit breaker that blocks or protectively relays power at the input terminal of the AC/DC rectifier;
A first DC/DC converter that modulates the distribution power distributed through the AC/DC rectifier into direct current power of a preset size;
a second protective relay breaker that blocks or protectively relays power at the input terminal of the first DC/DC converter;
a third protective relay circuit breaker that blocks or provides protective relay power to the output terminal of the first DC/DC converter;
a fourth protective relay breaker disposed between the output terminal of the first DC/DC converter and the first load input terminal to block or protectively relay power distributed to the first load;
A second device modulates the distribution power distributed through the AC/DC rectifier into direct current power of a preset size and distributes it to the first distributed power supply terminal, or supplies power from the first distributed power supply terminal to the output terminal of the AC/DC rectifier. DC/DC converter;
A fifth protective relay circuit breaker that blocks or provides protective relay power to the input or output terminal of the second DC/DC converter;
The distribution power output through the AC/DC rectifier is modulated into DC power of a preset size and supplied to the second distributed power source, or the power from the second distributed power source is supplied to the input terminal of the first DC/DC converter. a third DC/DC converter; and
It includes a sixth protective relay breaker disposed at the input terminal or output terminal of the third DC/DC converter to protectively relay or block power at the input terminal or output terminal of the third DC/DC converter,
The AC/DC rectifier includes a first switching element, a protection switching element, and an inductor, which are electrically connected to each other to rectify and convert the power of the system power supply to direct current through a rectifier circuit with current limiting characteristics and output it to the main line. A protection management system comprising a capacitor, a rectifier diode, and a rectifier output element. delete delete delete According to claim 1,
The protection management device is
Each protection section is set for each main line, at least one branch line, at least one distribution line, and at least one load line formed in the low-voltage direct current distribution system, and a protection section corresponding to the relay result input in real time. a data processing unit that identifies;
a protection device identification unit that identifies a protection relay circuit breaker included in the protection section identified by the data processing unit among the protection relay circuit breakers arranged in each protection section; and
A protection management system comprising a set value correction unit that monitors the occurrence of the fault current and controls the blocking operation of the protection relay circuit breaker for each protection section or corrects the operating standards of the protection relay circuit breakers in real time according to the relay results. According to clause 5,
The protection management device is
Compare the operation characteristics of the protection relay breaker identified in the protection device identification unit with the relay result detected through the relay device to check whether the protection device identification unit is normally identified, and control the re-identification operation for the protection relay breaker. A protection device change setting unit; and
At least one of topology information, impedance information, power capacity information, distance or length information, rated capacity information, current limiting information, and switching operation information for each protective relay circuit breaker and at least one electrical device disposed in each protection section. A protection management system further comprising a database that stores information in advance and shares it with the data processing unit and the protection device identification unit. According to clause 6,
The protection device change setting section
Compare the operation characteristics of the protection relay breaker identified in the protection device identification unit with the relay result detected through the relay device to check whether the data processing unit and the protection device identification unit are normally identified, and identify them in the protection device identification unit. A protection management system that performs a re-identification operation for each protection section and the protection relay breaker for each protection section when the operation characteristics of the selected protective relay breaker and the relay result detected by the relay device are different. According to clause 5,
The relay device is
Based on the operation standard set and corrected from the protection management device, the relay elements of the distribution lines for each protection section are corrected and relayed,
Protection that corrects TCC (Time Current Curve) operation characteristics of each of the protective relay circuit breakers formed on the main line, the at least one branch line, the at least one distribution line, and the at least one load line in response to the operating reference value. Management system. According to clause 8,
The data processing unit
Topology information, impedance information, power capacity information, rated capacity information, and current limitation information for the protection relay breakers for each protection section are provided and stored, and the voltage size input as a relay result of a certain protection section input in real time, A protection management system that compares current amount and current direction information with topology information, impedance information, power capacity information, rated capacity information, and current limitation information for the protection relay circuit breakers and identifies the corresponding protection section according to the relay and comparison results. According to clause 5,
The set value correction unit
By analyzing the relay results for the distribution lines for each protection section, if a fault current occurs in the main line,
Reset the operating reference value for the relay device to relay the relay element for the low voltage set value and forward/reverse direction information, and define the TCC (Time Current Curve) operation characteristics for the protective relay breaker installed on the main line. or a protection management system that sets an instantaneous curved operating characteristic constant. According to claim 10,
The set value correction unit
A protection management system that changes and sets the operation reference current, operation reference voltage, and voltage-current phase difference for the protection relay breaker installed in the fault current occurrence section when a fault current occurs in any one of the protection sections. According to claim 10,
The set value correction unit
When a fault current occurs in the at least one branch line, an operating reference value for the relay device is set to relay relay elements for the low voltage set point and the overcurrent set point, and TCC operation characteristics for the protective relay breaker installed on the branch line are set. A protection management system that sets instantaneous curved operating characteristics to a fixed value. According to claim 10,
The set value correction unit
When a fault current occurs in the at least one distributed line, an operating reference value for the relay device is set to relay a relay element for the overcurrent of the distributed line where the fault current occurred, and a protective relay breaker installed in the distributed line is set. A protection management system that sets the TCC operating characteristics to the instantaneous curved operating characteristic correction value. According to claim 10,
The set value correction unit
When a fault current occurs in the at least one load line, an operating reference value for the relay device is set to relay a relay element for overcurrent of the load line, and TCC operation characteristics for a protective relay breaker installed on the load line A protection management system that sets the instantaneous curved operating characteristic correction value. Setting each protection section for each distribution line formed in the low-voltage direct current distribution system;
Relaying relay elements of the distribution lines for each of the set protection sections through a relay device;
Wirelessly transmitting relay results for the distribution lines for each protection section to a protection management device; and
It includes the step of controlling the relay by blocking the fault current or correcting the operating standards for the protection relay between each protection section according to the relay result for each protection section,
The low-voltage direct current distribution system is,
An AC/DC rectifier that rectifies and modulates the power of the system power terminal and outputs it;
A first protective relay circuit breaker that blocks or protectively relays power at the input terminal of the AC/DC rectifier;
A first DC/DC converter that modulates the distribution power distributed through the AC/DC rectifier into direct current power of a preset size;
a second protective relay breaker that blocks or protectively relays power at the input terminal of the first DC/DC converter;
a third protective relay circuit breaker that blocks or provides protective relay power to the output terminal of the first DC/DC converter;
a fourth protective relay breaker disposed between the output terminal of the first DC/DC converter and the first load input terminal to block or protectively relay power distributed to the first load;
A second device modulates the distribution power distributed through the AC/DC rectifier into direct current power of a preset size and distributes it to the first distributed power supply terminal, or supplies power from the first distributed power supply terminal to the output terminal of the AC/DC rectifier. DC/DC converter;
A fifth protective relay circuit breaker that blocks or provides protective relay power to the input or output terminal of the second DC/DC converter;
The distribution power output through the AC/DC rectifier is modulated into DC power of a preset size and supplied to the second distributed power source, or the power from the second distributed power source is supplied to the input terminal of the first DC/DC converter. a third DC/DC converter; and
It includes a sixth protective relay breaker disposed at the input terminal or output terminal of the third DC/DC converter to protectively relay or block power at the input terminal or output terminal of the third DC/DC converter,
The AC/DC rectifier includes a first switching element, a protection switching element, and an inductor, which are electrically connected to each other to rectify and convert the power of the system power supply to direct current through a rectifier circuit with current limiting characteristics and output it to the main line. A protection management method for a low-voltage direct current distribution system, comprising a capacitor, a rectifier diode, and a rectifier output element. According to claim 15,
The step of controlling the protection relay between each protection section is
Setting each protection section for each main line, at least one branch line, at least one distribution line, and at least one load line formed in the low-voltage direct current distribution system;
Identifying a protection section corresponding to a relay result input in real time;
Identifying a protection relay breaker included in the identified protection section among the protection relay breakers arranged in each protection section; and
Protection of the low-voltage direct current distribution system, including the step of monitoring whether a fault current occurs and controlling the blocking operation of the protection relay circuit breaker for each protection section or correcting the operating standards of the protection relay circuit breaker in real time according to the relay results. How to manage. According to claim 16,
The step of controlling the protection relay between each protection section is
Comparing the operation characteristics of the identified protective relay breaker with relay results detected through a relay device to check whether the identified protective relay breaker is normally identified and controlling a re-identification operation for the protective relay breaker; and
Topology information, impedance information, power capacity information, distance or length information, rated capacity information, current limitation information, and switching operation information for each protection relay breaker and at least one electrical device arranged in each protection section in the database. A protection management method for a low-voltage direct current distribution system further comprising the step of pre-storing and sharing at least one piece of information. According to claim 16,
The step of relaying the relay element is
Based on the operation standard set and corrected from the protection management device, the relay elements of the distribution lines for each protection section are corrected and relayed,
A low voltage that corrects TCC (Time Current Curve) operation characteristics of each protective relay circuit breaker formed on the main line, the at least one branch line, the at least one distribution line, and the at least one load line in response to the operating reference value. Protection management methods for direct current distribution systems. According to claim 16,
The step of correcting the operating reference values in real time is
If it is determined that a fault current has occurred in the main line by analyzing the relay results for the distribution lines for each protection section,
Reset the operating reference value for the relay device to relay the relay element for low voltage setpoint and forward/reverse directionality information,
A protection management method for a low-voltage direct current distribution system that sets the TCC (Time Current Curve) operation characteristics of the protective relay breaker installed on the main line to a defined or instantaneous curve-shaped operation characteristic set value. According to clause 19,
The step of correcting the operating reference values in real time is
If it is determined that a fault current has occurred in the at least one branch line,
Set an operation reference value for the relay device to relay relay elements for the low voltage set point and overcurrent set point, and set the TCC operation characteristic for the protective relay breaker installed on the branch line to an instantaneous curved operation characteristic correction value. A protection management method for low-voltage direct current distribution systems.

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