Relay control circuit, relay, relay control method, and distribution system

Abstract

The present specification relates to embodiments of a relay control circuit, a relay, a relay control method, and a distribution system, the control circuit detecting the current and voltage of one point where the relay is provided so as to determine, on the basis of the detection results, whether the current corresponds to a current to be interrupted, calculating and comparing a positive sequence directionality and a zero sequence directionality of the voltage according to the determination results, and opening or not opening the one point according to the comparison results.

Description

Relay control circuit, relay, relay control method and power distribution system

[0001] The present invention relates to a control circuit for controlling a relay installed in a power distribution line, a relay, a method for controlling a relay, and a power distribution system.

[0002] Over 99% of domestic distribution lines are connected as radial distribution lines (systems) as shown in Fig. 1. This line system is designed and installed to supply the maximum load throughout the year, but it has the disadvantage of low line utilization, as the time during which the load connected to the line reaches its maximum is less than 20% of the year. In addition, when a fault occurs in a distribution line, nearby circuit breakers take action, but power outages occur for all loads beyond the fault section, resulting in power outages even in healthy sections that are not the fault section, which limits the reliability of the system.

[0003] To compensate for the limitations and disadvantages of the aforementioned dendritic distribution lines, research on loop / mesh systems as illustrated in Fig. 2 is being conducted, and these systems have been continuously introduced in developed countries where electricity privatization has taken place, such as the United States and Europe. The loop distribution method involves electrically connecting the ends of two dendritic distribution lines at all times, while the mesh distribution method involves interconnecting the middle and ends of multiple distribution lines. Since two or more distribution lines share / distribute the load, there are advantages such as increased line utilization and favorable conditions for maintaining line voltage. However, in the event of a fault, the fault current occurs in both directions rather than unidirectionally, and the direction of the fault may vary depending on the line section, making it technically difficult to coordinate fault interruption and protection. The relay elements and technologies used in existing dendritic distribution systems are limited.

[0004] Figure 3 illustrates the protection coordination structure of a loop / mesh system as depicted in Figure 2, in which a CB (VCB) is connected to the line outgoing end, and an IED is connected to the subsequent section. The two distribution line ends are continuously connected and operated. The purpose of protection coordination is to isolate fault sections, and sections in a loop distribution system can be classified into two types: CB-IED and IED-IED. In the case of the CB-IED section, communication- or non-communication-based protection coordination is possible. Communication-based protection coordination has technical and cost disadvantages because it requires the use of an interface (dedicated hardware) to enable the CB to communicate with the IED, and off-the-shelf CB products cannot be used. Therefore, it is necessary to configure it using non-communication-based protection coordination. The CB-IED section is protected using a non-communication-based directional overcurrent relay. 67F stands for Directional OverCurrent Relay (DOCR), and 67NF stands for Directional OverCurrent Ground Relay (DOCGR). DOCR typically performs directional determination using the positive component, while DOCGR performs directional determination using the zero component.

[0005] Figure 4 shows the operation sequence of such a conventional directional ground fault overcurrent relay, wherein normal current measurement is performed, and then a designated pickup current value (I pick_upA fault is recognized when a current exceeding the threshold is measured. The opening delay time of the circuit breaker is determined based on the magnitude of the fault current recognized by the relay (according to the time-current curve). When a fault current exceeding the opening delay time is experienced, and the zero-sequence voltage exceeds the zero-sequence threshold voltage and the zero-sequence directionality is positive, it is determined that there is a fault in the circuit breaker, and a command to open the circuit breaker is issued. If the measured current falls below the Pickup current value within the opening delay time, it is determined that the fault has been resolved, and all sequences are reset.

[0006] Meanwhile, in the section between IEDs, a communication-based Directional Comparison Trip (DCT) as illustrated in Fig. 5 is used. When a fault occurs between IED circuits, the fault current is equal to the CT polarity of the IED (detecting a forward fault), and this is transmitted to the other IED. Only when the IED on the opposite side, which is the communication target, also detects a forward fault is the corresponding IED that trips. If a fault occurs outside this section, one IED will detect a forward or reverse direction while the other IED detects the opposite direction, so the trip condition is not met and the method does not operate.

[0007] One of the problems that arises when protecting the CB-IED section with DOCR / DOCGR (non-communication) in this way is the case illustrated in Fig. 6. Fig. 6 shows an example of a system in which four distribution lines are connected to the same substation. Distribution lines #1 and #2 operate in a loop distribution system with their ends connected, while distribution lines #3 and #4 operate in a radial manner (the same problem can occur even if #3 and #4 are operated as a loop distribution system). When a ground fault occurs directly under distribution line #3, CB #3, the corresponding ground fault current flows to the earth through CB #3. However, the current flowing to the earth is divided and flows to the ground of the distributed power source connection transformer (TR for DG in Fig. 6) connected to the line and to the neutral point ground of the substation (Substation in Fig. 6). The problem lies in the ground fault current flowing through the transformer for interconnecting distributed power sources, and this current flows not only to the faulty distribution line but also to distribution lines #1 and #2. In this case, taking distribution line #1 as an example, IED#1-4 & IED#2-1 and IED#2-4 & IED#3-1 will perform a Directional Compare Trip (DCT), while CB#1 and IED#1 will operate as DOCR / DOCGR. Among the IED#2-4 & IED#3-1 DCTs, IED#2-4 detects a reverse fault and IED#3-1 detects a forward fault; therefore, they do not trip as they do not meet the DCT trip conditions. Similarly, among the IED#1-4 & IED#2-1 DCTs, IED#1-4 detects a reverse fault and IED#2-1 detects a forward fault; therefore, they also do not trip as they do not meet the DCT trip conditions. CB#1 also detects a fault in the reverse direction, so it does not trip. However, IED#1-1 detects a fault in the forward direction, so there is a risk of malfunction. The same applies to IED#4-1 of distribution line #2. In other words, there is a risk of malfunction even if the fault occurs in a different section (other line) rather than in its own section (self line).In addition, if IED#1-1 or IED#4-1 opens, CB#2, CB#1, or other IED circuits may also open. This is because if a load is connected to a loop distribution line considering the capacity of two lines, and IED#1-1 or IED#4-1 opens, one line must eventually handle the capacity of two lines, resulting in an overload situation. Consequently, in the worst-case scenario, a power outage may occur in all sections connected to the loop distribution line.

[0008] As such, there exist blind spots that cannot be protected by the existing DOCGR's algorithm for detecting self-direction faults (zero-sequence forward direction, exceeding V0Threshold (zero-sequence threshold voltage)).

[0009] The present invention aims to improve upon the limitations of the prior art as described above.

[0010] Accordingly, the present specification aims to provide an embodiment capable of accurately determining a fault in a self-line / other-line.

[0011] In addition, we intend to provide an embodiment capable of accurately determining failures in self-sections / other sections.

[0012] Furthermore, we intend to provide an embodiment in which accurate fault determination can be achieved even in non-communication-based protection coordination sections.

[0013] In addition, we intend to provide an embodiment in which protection coordination in power distribution lines can be achieved accurately and stably.

[0014] The present invention, for solving the problem described above, provides a solution means of performing relay operations according to the directionality of the positive and zero components of the voltage.

[0015] Specifically, the current and voltage at a point where a relay is installed are detected, and based on the detection result, it is determined whether the current corresponds to a current to be cut off. Based on the determination result, the positive and zero-sequence directionality of the voltage is calculated and compared, and the point is opened or closed according to the comparison result.

[0016] Such technical features can be applied to and implemented in control circuits of all protection devices including relays, protection devices, methods of operation of protection devices, methods of control of protection devices, protection coordination systems, distribution systems, system protection methods, and system operation methods, and this specification aims to provide embodiments of a control circuit of a relay, a relay, a method of control of a relay, and a distribution system that utilize the above technical features as a means of solution.

[0017] A control circuit for a relay having the above technical features as a means for solving the problem is a control circuit for a relay installed at a point on a distribution line where a circuit breaker is installed, comprising a detection unit that detects the current and voltage at the said point and a calculation unit that controls the relay unit of the said relay to open or not open the said point based on the detection result of the detection unit, wherein the calculation unit determines whether the said current corresponds to a current to be interrupted based on the detection result, calculates and compares the positive and zero directionality of the said voltage respectively according to the determination result, and controls the relay unit to open or not open the said point according to the comparison result.

[0018] In an embodiment, the calculation unit can calculate the positive component directionality and the zero component directionality, respectively, if, based on the judgment result, the current corresponds to the current to be blocked.

[0019] In an embodiment, the operation unit may not calculate the positive component directionality and the zero component directionality, respectively, if, based on the judgment result, the current does not correspond to the current to be blocked.

[0020] In an embodiment, the operation unit can control the relay unit to open or not open the one point according to the matching direction when, based on the comparison result, the normal component direction and the zero component direction match.

[0021] In an embodiment, the operation unit can control the opening of the one point if, based on the comparison result, the normal component directionality and the image component directionality are in the forward direction.

[0022] In an embodiment, the operation unit can control the one point to remain closed if, based on the comparison result, the normal component directionality and the image component directionality are in opposite directions.

[0023] In an embodiment, the operation unit can control the relay unit to open or not open the one point according to the zero-sequence direction if, as a result of the comparison, the positive component direction and the zero-sequence direction do not match.

[0024] In an embodiment, the calculation unit can control the relay unit to open or not open the one point according to the result of the recalculation, by recalculating the direction of the image component after a certain period of time if the direction of the image component is in the forward direction based on the comparison result.

[0025] In the embodiment, the fixed time may be the operating time of another protection device installed on the power distribution line.

[0026] In an embodiment, the operation unit can control the opening of the one point if, based on the result of the recalculation, the image component directionality is in the forward direction.

[0027] In an embodiment, the operation unit can control the one point to remain closed if, based on the recalculation result, the image component directionality is reversed.

[0028] In an embodiment, the operation unit can control the one point to remain closed if, based on the comparison result, the image component directionality is reversed.

[0029] In addition, an embodiment of a relay having the above technical features as a means of solving the problem includes a relay installed at a point on a distribution line where a circuit breaker is installed, a relay unit that opens the said point when a trip signal is applied, and a control unit that determines whether the current corresponds to a current to be cut off based on the result of detecting the current and voltage at the said point, and if the current corresponds to the current to be cut off, calculates the positive component directionality and zero component directionality of the voltage, and if the zero component directionality is in the forward directionality, generates the trip signal according to whether it matches the positive component directionality and applies it to the relay unit.

[0030] In an embodiment, the control unit may not generate the trip signal if the current does not correspond to the current to be cut off.

[0031] In an embodiment, the relay may not open the one point if the current does not correspond to the current to be cut off.

[0032] In an embodiment, the control unit can generate the trip signal and apply it to the relay unit when the positive component directionality matches the zero component directionality in the forward direction.

[0033] In an embodiment, the relay unit can open the one point when the positive component directionality matches the zero component directionality in the forward direction.

[0034] In an embodiment, the control unit may not generate the trip signal if the normal component directionality does not match the image component directionality in the forward direction.

[0035] In an embodiment, the relay unit may not open the one point if the positive component directionality does not match the zero component directionality in the forward direction.

[0036] In an embodiment, the control unit can recalculate the direction of the zero component after a certain period of time if the direction of the positive component is in the reverse direction and does not match the direction of the zero component, and if the result of the recalculation is that the direction of the zero component is in the forward direction, generate the trip signal and apply it to the relay unit.

[0037] In an embodiment, the relay unit can open the one point if, after a certain period of time has elapsed, the direction of the zero-sequence component becomes forward while the direction of the positive component is in the reverse direction and does not match the direction of the zero-sequence component.

[0038] In an embodiment, the control unit may recalculate the direction of the zero component after a certain period of time if the direction of the normal component is in the reverse direction and does not match the direction of the zero component, and if the result of the recalculation is that the direction of the zero component is in the reverse direction, it may not generate the trip signal.

[0039] In an embodiment, the relay unit may not open the one point if, after a certain period of time has elapsed, the direction of the zero-sequence component is in the reverse direction while the direction of the positive component is in the reverse direction and does not match the direction of the zero-sequence component.

[0040] In addition, an embodiment of a relay control method having the above technical features as a means of solving the problem is a control method for a relay installed at a point on a distribution line where a circuit breaker is installed, comprising the steps of: detecting the current and voltage at said point; determining whether said current corresponds to a current to be interrupted based on the detection result; calculating and comparing the positive and zero directionality of said voltage according to the determination result; and controlling the operation of said relay to open or not open said point according to the comparison result.

[0041] In an embodiment, the comparing step may calculate and compare the positive and zero directionality of the voltage if, based on the judgment result, the current corresponds to the current to be blocked.

[0042] In an embodiment, the controlling step may control the operation of the relay to open the one point if, as a result of the comparison, the positive component direction and the zero component direction match in the forward direction.

[0043] In an embodiment, the controlling step may control the operation of the relay so as not to open the one point if, as a result of the comparison, the positive component direction and the zero component direction match in opposite directions.

[0044] In an embodiment, the controlling step may control the operation of the relay to open the one point if, based on the comparison result, the positive component direction is reversed and the zero component direction is forward, recalculate the zero component direction after a certain period of time, and if, based on the recalculation result, the zero component direction is forward.

[0045] In an embodiment, the controlling step may control the operation of the relay such that, if the positive component direction is reversed and the zero component direction is forward based on the comparison result, the zero component direction after a certain period of time elapses is recalculated, and if the zero component direction is reversed based on the recalculation result, the operation of the relay is not opened at the one point.

[0046] In an embodiment, the controlling step may control the operation of the relay so as not to open the one point if, based on the comparison result, the positive component direction is in the forward direction and the zero component direction is in the reverse direction.

[0047] In addition, an embodiment of a distribution system having the above technical features as a means for solving the problem comprises: a plurality of distribution lines branched from a system and connected by at least one pair of loop distribution lines; a plurality of circuit breakers installed at each branching point where the plurality of distribution lines branch off from the system; and a plurality of relays installed at each of the plurality of points of each of the plurality of distribution lines to open or not open the installed points. The plurality of relays of the loop lines connected by loop distribution include a plurality of first relays installed at each of the points adjacent to each of the branching points among the plurality of points, and a plurality of second relays installed at each of one or more points after the first point. Each of the plurality of first relays determines whether the current corresponds to a current to be cut off based on the results of detecting the current and voltage of each of the first points, and if the current corresponds to the current to be cut off, calculates the positive and zero directionality of the voltage, and if the zero directionality is positive, opens the first point according to whether it matches the positive directionality.

[0048] In an embodiment, the plurality of first relays may not open the one point if the current does not correspond to the current to be cut off.

[0049] In an embodiment, the plurality of first relays can open the one point when the positive component directionality matches the zero component directionality in the forward direction.

[0050] In an embodiment, the plurality of first relays may not open the one point if the positive component directionality does not match the zero component directionality in the forward direction.

[0051] In an embodiment, the plurality of first relays can recalculate the zero-sequence direction after a certain period of time if the positive-sequence direction does not match the zero-sequence direction in the reverse direction, and if the recalculation result shows that the zero-sequence direction is in the forward direction, they can open the one point.

[0052] In an embodiment, the plurality of first relays can recalculate the zero-sequence direction after a certain period of time if the positive-sequence direction does not match the zero-sequence direction in the reverse direction, and if the recalculation result shows that the zero-sequence direction is in the reverse direction, the one point can be kept closed.

[0053] The embodiments of the relay control circuit, relay, relay control method, and power distribution system described above are not limited to those described above and may include embodiments described in the specific description below or inferred / derived from the specific description.

[0054] According to the embodiment of the relay control circuit, relay, relay control method, and power distribution system described above, by performing relay operations according to the directionality of the positive and zero-sequence components of the voltage, there is an effect of accurately distinguishing faults between other lines and child lines, and between child sections and other sections.

[0055] Accordingly, this also has the effect of accurately protecting landlocked areas that could not be protected by conventional technology.

[0056] In addition, it enables accurate differentiation between other lines and branch lines, as well as between branch sections and other sections, and has the effect of accurately protecting lines even in non-communication-based sections.

[0057] Accordingly, this not only enables the expansion of the protection coordination range of protection devices in the power distribution system but also has the effect of increasing the operational stability of the power distribution system.

[0058] The effects according to the embodiments of the relay control circuit, relay, relay control method, and power distribution system described above are not limited to those described above and may include effects described in the specific description below or inferred / derived from the specific description.

[0059] Figure 1 is an example diagram of a power distribution system according to a dendritic power distribution method.

[0060] Figure 2 is an example diagram of a power distribution system according to a loop power distribution method.

[0061] FIG. 3 is an example diagram showing the protection coordination structure of the loop power distribution method illustrated in FIG. 2.

[0062] FIG. 4 is a flowchart showing the operation sequence of a directional ground fault overcurrent relay used in the CB-IED section shown in FIG. 3.

[0063] FIG. 5 is an example diagram showing a communication-based protection coordination structure applied to the IED-IED section illustrated in FIG. 3.

[0064] Figure 6 is an example diagram showing an example of a fault occurring in a loop distribution system.

[0065] FIG. 7 is a configuration diagram of a power distribution system in which a relay is installed according to an embodiment.

[0066] FIG. 8 is a detailed configuration diagram of a relay according to an embodiment.

[0067] FIG. 9 is a flowchart showing the specific operation sequence of a relay according to an embodiment.

[0068] FIG. 10 is a flowchart of a relay control method according to an embodiment.

[0069] FIG. 11 is a configuration diagram of a power distribution system according to an embodiment.

[0070] Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Identical or similar components are given the same reference numeral regardless of the drawing symbols, and redundant descriptions thereof are omitted. Furthermore, in describing the embodiments disclosed in this specification, if it is determined that a detailed description of related prior art may obscure the essence of the embodiments disclosed in this specification, such detailed description is omitted.

[0071] In addition, the attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification, and the technical concept disclosed in this specification is not limited by the attached drawings; it should be understood that all modifications, equivalents, and substitutions included within the concept and technical scope of the present invention are included.

[0072] The control circuit of the relay (100) according to the embodiment may be a circuit that controls the operation of the relay (100) installed at a point (P) of the distribution line (DG) where a circuit breaker (CB) is installed, as shown in FIG. 7.

[0073] That is, the control circuit may be a control device of the relay (100).

[0074] The above relay (100) may be a protection device installed at one point (P) in a power distribution system (1) as shown in FIG. 7.

[0075] The above relay (100) may be a Directional Over Current Ground Replay (DOCGR).

[0076] The above relay (100) can detect a fault current occurring in a section of the distribution line (DG) including the above point (P) and open the above point (P) in response to the fault current.

[0077] As shown in FIG. 8, the above relay (100) includes a relay unit (10) that opens or closes the one point (P) and a control unit (20) that controls the relay unit (10).

[0078] Here, the control unit (20) may correspond to the control circuit.

[0079] The above relay unit (10) can keep the above one point (P) closed during normal operation and open the above one point (P) during operation.

[0080] That is, the above relay unit (10) can be closed during normal operation to connect the above one point (P), and opened during operation to disconnect the above one point (P).

[0081] The control circuit (20) corresponding to the control unit of the above relay (100) includes a plurality of circuit elements and can control the operation of the above relay unit (10).

[0082] The above control circuit (20) may include a plurality of circuit elements for controlling the operation of the above relay unit (10).

[0083] The control circuit (20) includes a detection unit (21) that detects the current and voltage of the one point (P) and a calculation unit (22) that controls the relay unit (10) to open or not open the one point (P) based on the detection result of the detection unit (21).

[0084] That is, the control circuit (20) may control the operation of the relay unit (10) based on the result of detecting the current and voltage at the one point (P) that is opened or closed by the relay unit (10), by including the detection unit (21) and the calculation unit (22).

[0085] In the above control circuit (20), the detection unit (21) may include a current detection means for detecting the current at the one point (P) and a voltage detection means for detecting the voltage at the one point (P).

[0086] For example, it may include CT (Current Transformer) and PT (Potential Transformer).

[0087] The detection unit (21) can detect the current and voltage at the one point (P) and transmit the detection result to the calculation unit (22).

[0088] In the above control circuit (20), the calculation unit (22) may include a calculation device and a signal processing device for controlling the operation of the relay unit (10) based on the detection result.

[0089] The above calculation unit (22) can control the relay unit (10) so that the relay unit (10) opens or closes the one point (P) according to the detection result.

[0090] The above operation unit (22) can generate a control signal (trip signal) to control the operation of the relay unit (10) based on the detection result, and apply the control signal to the relay unit (10) to control the operation of the relay unit (10).

[0091] For example, when an accident occurs at the above-mentioned point (P), the above-mentioned relay unit (10) may generate a control signal to control the above-mentioned point (P) to open and apply it to the above-mentioned relay unit (10).

[0092] In the control circuit (20) including the detection unit (21) and the calculation unit (22) as described above, the calculation unit (22) determines whether the current corresponds to a current to be cut off based on the detection result, calculates and compares the positive and zero directionality of the voltage respectively according to the determination result, and controls the relay unit (10) so that the relay unit (10) opens or does not open the one point (P) according to the comparison result.

[0093] That is, the above calculation unit (22) may control the relay unit (10) according to the positive component directionality and the zero component directionality of the voltage when the current corresponds to the current to be cut off.

[0094] Accordingly, the control circuit (20) can determine whether there is a fault in the magnetic section based on the positive component directionality and the zero component directionality, and control the relay unit (10) to open or not open the line when there is a fault in the magnetic section.

[0095] In this way, unlike conventional relay operations that open the line by only determining whether the current is subject to interruption, the control circuit (20) further calculates the positive and zero directionality of the voltage and, based on this, accurately determines whether there is a fault in the self-section / other section and controls the relay operation, so that the relay unit (10) does not operate when there is a fault in the other section and operates the relay only when there is a fault in the self-section.

[0096] The process by which the above-mentioned control circuit (20) controls the relay unit (10) and the relay unit (10) operates may be as illustrated in FIG. 9.

[0097] In FIG. 9, steps (1) to (5) are performed in the same order as the operation of the conventional directional ground fault overcurrent relay shown in FIG. 4, and the control circuit (20) may further perform steps (6) to (9) to control the relay unit (10).

[0098] The above calculation unit (22) can determine (1 to 5) whether the current corresponds to the current to be blocked, and if the result of the determination (5) indicates that the current corresponds to the current to be blocked, it can calculate (6) the positive component directionality (D1) and the zero component directionality (DO), respectively.

[0099] That is, when the above calculation unit (22) determines that the current corresponds to the current to be blocked, it may calculate (6) the positive component directionality (D1) and the zero component directionality (DO), respectively.

[0100] In this case, the above calculation unit (22) may calculate (6) each of the normal component directionality (D1) and the image component directionality (DO), and then compare (7) each of the normal component directionality (D1) and the image component directionality (DO).

[0101] The above calculation unit (22) can calculate the normal component directionality (D1) and the zero component directionality (D0) respectively if, based on the above judgment result (5), the current does not correspond to the current to be blocked.

[0102] That is, if the above calculation unit (22) determines that the current does not correspond to the current to be blocked, the above normal component directionality (D1) and the above zero component directionality (DO) may each not be calculated.

[0103] In this case, the above operation unit (22) may control the relay unit (10) so that the relay unit (10) is not opened.

[0104] The above calculation unit (22) can control the relay unit (10) to open or not open the above point (P) according to the matching direction when the above comparison result (7) and the above normal component direction (D1) and the above zero component direction (D0) match.

[0105] That is, the above operation unit (22) may control the relay unit (10) to open or not open the above point (P) depending on whether the above normal component direction (D1) and the above zero component direction (D0) match in the forward direction (F) or whether the above normal component direction (D1) and the above zero component direction (D0) match in the reverse direction (R).

[0106] The above operation unit (22) can control the opening of the above point (P) if, based on the above comparison result (7), the normal component directionality (D1) and the above image component directionality (D0) are in the forward direction (F) (8).

[0107] That is, the above calculation unit (22) can determine that there is a fault in the self-section when the above normal component directionality (D1) and the above zero component directionality (D0) match in the forward direction (F) (8-YES), and control the above relay unit (10) to open the above one point (P).

[0108] The above operation unit (22) can control the above point (P) to remain closed if, based on the above comparison result (7), the above normal component directionality (D1) and the above image component directionality (D0) are in reverse direction (R) (8).

[0109] That is, the above calculation unit (22) can determine that there is a fault in another section when the above normal component directionality (D1) and the above zero component directionality (D0) match in the reverse direction (R) (8-NO), and control the above relay unit (10) to keep the above one point (P) closed.

[0110] The above calculation unit (22) can control the relay unit (10) (9) to open or not open the above point (P) according to the above-mentioned direction (D0) if the above-mentioned comparison result (7) and the above-mentioned direction (D0) do not match.

[0111] That is, the above operation unit (22) may control the relay unit (10) to open or not open the above point (P) depending on whether the above positive component direction (D1) and the above zero component direction (D0) do not match in the forward direction (F), or whether the above zero component direction (D0) is in the forward direction (F) or the above zero component direction (D0) is in the reverse direction (R).

[0112] The above calculation unit (22) can control the above relay unit (10) to open or not open the above point (P) according to the result of the recalculation, by recalculating (⑾) the above-mentioned directionality (D0) after a certain period of time has elapsed (⑽) if the above-mentioned comparison result (⑺) is in the forward direction (F).

[0113] That is, the above operation unit (22) may control the relay unit (10) to open or not open the above point (P) according to the above-mentioned direction (D0) after a certain period of time has elapsed (10), when the above-mentioned direction (D1) is reverse direction (R) and the above-mentioned direction (D0) is forward direction (F) (9-YES).

[0114] Here, the above-mentioned time may be the operating time of another protection device (CB or 100') installed on the distribution line (DG).

[0115] The above fixed time may be the minimum response time of the other protection device (CB or 100').

[0116] The above specified time may mean the minimum maintenance time until the other protection device (CB or 100') experiences a failure and operates.

[0117] In cases where a local circuit breaker experiences a failure due to a fault in another line, there is a high probability that the relays (breakers) in the other line will experience a large current. Therefore, even if the calculated opening delay time is short, if the circuit breaker waits for the aforementioned fixed time and then trips, the fault in the other line is resolved after the fixed time, and the fault experienced by the local circuit breaker is also resolved, making it unnecessary to trip the local line.

[0118] Accordingly, the above relay unit (10) may wait for a certain amount of time (⑽) even if the opening delay time calculated as a result of experiencing a high current fault is 50 [ms], and may open if the fault persists (⑾) even after the certain amount of time has elapsed (⑽).

[0119] The above calculation unit (22) can control the opening of the above point (P) if the above recalculation result (⑾) indicates that the above image component directionality (D0) is in the forward direction (F).

[0120] That is, the above calculation unit (22) can determine that the above normal component directionality (D1) is reverse direction (R) and the above zero component directionality (D0) is forward direction (F) (9), and if the above zero component directionality (D0) after a certain period of time (10) is forward direction (F) (11-YES), the above calculation unit (22) can control the above relay unit (10) to open the above one point (P) by determining that there is a fault in the self-section.

[0121] The above calculation unit (22) can control the above point (P) to remain closed if the above recalculation result (⑾) indicates that the above image component directionality (D0) is in the reverse direction (R).

[0122] That is, the above calculation unit (22) can determine that the normal direction (D1) is reverse direction (R) and the zero direction (D0) is forward direction (F) (9), and if the zero direction (D0) after a certain period of time has elapsed (10) is reverse direction (R) (11-NO), the above calculation unit (22) can control the above relay unit (10) to keep the above point (P) closed by determining that there is a fault in another section.

[0123] The above operation unit (22) can control the above point (P) to remain closed if, based on the comparison result (7), the image component directionality (D0) is reverse (R).

[0124] That is, the above calculation unit (22) can determine that the normal component directionality (D1) is in the forward direction (F) and the zero component directionality (D0) is in the reverse direction (R) (9-NO), and control the above relay unit (10) to keep the above point (P) closed by determining that there is a fault in another section.

[0125] In this way, the control circuit (20) that controls the relay unit (10) by determining whether there is a fault in the self-section / other-section based on the normal component directionality (D1) and the zero component directionality (D0) can be included as the control unit (20) of the relay (100) according to the embodiment and control the operation of the relay (100).

[0126] The above relay (100) is a relay installed at a point (P) of the distribution line (DG) where the circuit breaker (CB) is installed as shown in FIG. 7, and includes the relay unit (10) and the control unit (20) as shown in FIG. 8, and can operate in the order shown in FIG. 9.

[0127] In the above relay (100), the relay unit (10) opens the above point (P) when a trip signal is applied, and the control unit (20) determines whether the current corresponds to the current to be cut off based on the result of detecting the current and voltage at the above point (P) (1 to 5), and if the current corresponds to the current to be cut off (5-YES), calculates the positive component directionality (D1) and the zero component directionality (D0) of the voltage (6), and if the zero component directionality (D0) is in the forward direction (F) (8-YES OR 9-YES), generates the trip signal according to whether it matches the positive component directionality (D1) and applies it to the relay unit (10).

[0128] That is, when the current corresponds to the current to be cut off and the zero-sequence directionality (D0) is in the forward direction (F) (8-YES OR 9-YES), the control unit (20) generates the trip signal according to the directionality of the normal-sequence directionality (D1) and applies it to the relay unit (10), thereby causing the relay unit (10) to open the one point (P).

[0129] The control unit (20) can determine whether there is a fault in the self-section / other-section based on the positive component directionality (D1) and the zero component directionality (D0) by calculating (6) each of the positive component directionality (D1) and the zero component directionality (D0) when the current corresponds to the current to be cut off (5-YES).

[0130] The control unit (20) may not generate the trip signal if the current does not correspond to the current to be cut off (5-NO).

[0131] That is, if the current does not correspond to the current to be cut off (5-NO), the control unit (20) determines that the current is not the current to be cut off and may not generate the trip signal so that the one point (P) is not opened.

[0132] Accordingly, the relay unit (10) may not open the one point (P) when the current does not correspond to the current to be cut off (5-NO).

[0133] The control unit (20) can generate a trip signal and apply it to the relay unit (10) when the normal component directionality (D1) matches the zero component directionality (D0) in the forward direction (F) (8-YES).

[0134] That is, the control unit (20) can determine that the current is a fault current between sections when the current corresponds to the current to be cut off (5-YES) and the positive direction (D1) and the zero direction (D0) correspond to the positive direction (F) (8-YES), and generate the trip signal to open the one point (P) and apply it to the relay unit (10).

[0135] Accordingly, the relay unit (10) can open the one point (P) when the positive component directionality (D1) matches the zero component directionality (D0) in the forward direction (F) (8-YES).

[0136] The above control unit (20) may not generate the trip signal if the normal component directionality (D1) matches the image component directionality (D0) in the reverse direction (R) (8-NO).

[0137] That is, the control unit (20) may determine that the current is a fault current of another section when the current corresponds to the current to be cut off (5-YES) and the positive direction (D1) and the zero direction (D0) correspond to the reverse direction (R) (8-NO), and thus may not generate the trip signal so that the one point (P) is not opened.

[0138] Accordingly, the relay unit (10) can keep the above point (P) closed when the above normal component directionality (D1) matches the above zero component directionality (D0) in the reverse direction (R) (8-NO).

[0139] The control unit (20) may not generate the trip signal if the normal component directionality (D1) is in the forward direction (F) and does not match (9-NO) the image component directionality (D0).

[0140] That is, the control unit (20) determines that the current is a fault current of another section when the current corresponds to the current to be cut off (5-YES), the positive component directionality (D1) corresponds to the forward direction (F), and the zero component directionality (D0) corresponds to the reverse direction (R) (9-NO), and thus the trip signal may not be generated so that the one point (P) is not opened.

[0141] Accordingly, the relay unit (10) can keep the one point (P) closed when the positive component directionality (D1) is in the forward direction (F) and does not match (9-NO) the zero component directionality (D0).

[0142] The control unit (20) can recalculate the zero-sequence direction (D0) after a certain period of time (11) if the positive-sequence direction (D1) is in the reverse direction (R) and does not match the zero-sequence direction (D0) (19-YES), and if the result of the recalculation is that the zero-sequence direction (D0) is in the forward direction (F) (11-YES), it can generate the trip signal and apply it to the relay unit (10).

[0143] That is, the control unit (20) can determine that the current is a fault current in the self-interval when the current corresponds to the current to be cut off (5-YES), the positive direction (D1) corresponds to the reverse direction (R), the zero direction (D0) corresponds to the forward direction (F) (9-YES), and after a certain period of time (10), the zero direction (D0) corresponds to the forward direction (F) (11-YES), and generate the trip signal and apply it to the relay unit (10).

[0144] Accordingly, the relay unit (10) can open the one point (P) when the zero-sequence direction (DO) is in the forward direction (F) (⑾-YES) after a certain period of time has elapsed (⑽) while the positive-sequence direction (D1) is in the reverse direction (R) and does not match the zero-sequence direction (D0) (⑼-YES).

[0145] The control unit (20) can recalculate (⑾) the direction of the image component (D0) after a certain period of time has elapsed (⑽) if the direction of the normal component (D1) is in the reverse direction (R) and does not match (⑼-YES), and if the result of the recalculation is that the direction of the image component (D0) is in the reverse direction (R) (⑾-NO), it can not generate the trip signal.

[0146] That is, the control unit (20) may determine that the current is a fault current of another section and not generate the trip signal if the current corresponds to the current to be cut off (5-YES), the positive direction (D1) corresponds to the reverse direction (R), the zero direction (D0) corresponds to the forward direction (F) (9-YES), and after a certain period of time elapses (10), the zero direction (D0) corresponds to the reverse direction (R) (11-NO).

[0147] Accordingly, the relay unit (10) may not open the above point (P) when the above-mentioned positive component direction (D1) is in the reverse direction (R) and does not match the above-mentioned zero component direction (D0) (⑼-YES), and the above-mentioned zero component direction (DO) after a certain period of time (⑽) is in the reverse direction (R) (⑾-NO).

[0148] Here, the above-mentioned time may be the operating time of another protection device (CB or 100') installed on the distribution line (DG).

[0149] Meanwhile, the relay (100), which operates by determining whether there is a fault in the self-section / other-section based on the normal section directionality (D1) and the zero section directionality (D0) as described above, can be controlled in the order of the relay control method according to the embodiment as shown in FIG. 10.

[0150] That is, the control unit (20) may control the relay unit (10) in the order of the control method as shown in FIG. 10.

[0151] In addition, the relay (100) may operate in the order of the control method as shown in FIG. 10.

[0152] The above control method is a method for controlling the relay (100) installed at a point (P) of the distribution line (DG) where the circuit breaker (CB) is installed as shown in FIG. 7, and as shown in FIG. 10, includes the steps of detecting the current and voltage at the point (P) (S10), determining whether the current corresponds to a current to be cut off based on the detection result (S20), calculating and comparing the positive directionality (D1) and zero directionality (D0) of the voltage based on the determination result (S30), and controlling the operation of the relay (100) to open or not open the point (P) based on the comparison result (S40).

[0153] That is, the control circuit (20) detects the current and voltage at the one point (P) (S10), determines whether the current corresponds to the current to be cut off based on the detection result (S20), calculates and compares the positive direction (D1) and the zero direction (D0) based on the determination result (S30), and controls the operation of the relay (100) to open or not open the one point (P) based on the comparison result (S40).

[0154] The above detection step (S10) can detect the current and voltage of the above one point (P) in real time.

[0155] The above-mentioned judgment step (S20) can determine in real time whether the current corresponds to the blocking target current based on the detection result.

[0156] The above-determining step (S20) can calculate the opening delay time corresponding to the current to be cut off when the current corresponds to a certain magnitude standard for the current to be cut off, and check whether the current to be cut off is maintained during the opening delay time.

[0157] The above-determining step (S20) may determine that the current corresponds to the current to be cut off if the current to be cut off is maintained even after the opening delay time.

[0158] The comparison step (S30) above can calculate and compare the normal component directionality (D1) and the zero component directionality (D0) if, based on the judgment result (S20), the current corresponds to the current to be blocked.

[0159] The above-mentioned controlling step (S40) can control the operation of the relay (100) based on the comparison result of the normal component directionality (D1) and the zero component directionality (D0) calculated and compared in the above-mentioned comparing step (S30).

[0160] The above-mentioned controlling step (S40) can control the operation of the relay (100) to open the one point (P) if, based on the comparison result (S30), the normal component directionality (D1) and the zero component directionality (D0) match in the forward direction (F).

[0161] The above-mentioned controlling step (S40) can control the operation of the relay (100) to open the one point (P) by determining that there is a fault in the self-section when the normal direction (D1) and the zero direction (D0) match in the forward direction (F).

[0162] For example, the trip signal may be applied to the relay unit (10), or the control signal currently being applied to the relay unit (10) may be generated as a signal to open the one point (P) and applied to the relay unit (10).

[0163] Accordingly, the relay (100) may open the one point (P) when the positive component directionality (D1) and the zero component directionality (D0) match in the forward direction (F).

[0164] The above-mentioned controlling step (S40) can control the operation of the relay (100) so as not to open the above-mentioned point (P) if, based on the comparison result (S30), the normal component directionality (D1) and the zero component directionality (D0) match in the reverse direction (R).

[0165] The above-mentioned controlling step (S40) can control the operation of the relay (100) to keep the above-mentioned point (P) closed by determining that there is a fault in another section when the above-mentioned normal direction (D1) and the above-mentioned zero direction (D0) match in the reverse direction (R).

[0166] For example, the trip signal may not be applied to the relay unit (10), or the control signal currently being applied to the relay unit (10) may be generated as a signal that keeps the one point (P) closed and applied to the relay unit (10).

[0167] Accordingly, the relay (100) may keep the one point (P) closed when the positive component directionality (D1) and the zero component directionality (D0) match in the reverse direction (R).

[0168] The above-mentioned controlling step (S40) can control the operation of the relay (100) by recalculating the zero-sequence directionality (D0) after a certain period of time if, based on the comparison result (S30), the normal directionality (D1) is reverse direction (R) and the zero-sequence directionality (D0) is forward direction (F), and if, as a result of the recalculation, the zero-sequence directionality (D0) is forward direction (F), opening the one point (P).

[0169] The above-mentioned controlling step (S40) can control the operation of the relay (100) to open the above-mentioned point (P) by determining that there is a fault in the self-section when, in a state where the above-mentioned positive component direction (D1) is reverse direction (R) and the above-mentioned zero component direction (D0) is forward direction (F), the above-mentioned zero component direction (D0) is recalculated after a certain period of time and the result is that the above-mentioned zero component direction (D0) is forward direction (F).

[0170] For example, the trip signal may be applied to the relay unit (10), or the control signal currently being applied to the relay unit (10) may be generated as a signal to open the one point (P) and applied to the relay unit (10).

[0171] Accordingly, the relay (100) may open the one point (P) if, after a certain period of time, the zero-sequence direction (D0) becomes the forward direction (F) while the positive-sequence direction (D1) is in the reverse direction (R) and the zero-sequence direction (D0) is in the forward direction (F).

[0172] The above-mentioned controlling step (S40) can control the operation of the relay (100) such that if, based on the comparison result (S30), the normal component directionality (D1) is reverse direction (R) and the zero component directionality (D0) is forward direction (F), the zero component directionality (D0) after a certain period of time is recalculated, and if, as a result of the recalculation, the zero component directionality (D0) is reverse direction (R), the one point (P) is not opened.

[0173] The above-mentioned controlling step (S40) can control the operation of the relay (100) so that, when the above-mentioned normal direction (D1) is reverse direction (R) and the above-mentioned zero direction (D0) is forward direction (F), and the result of recalculating the above-mentioned zero direction (D0) after a certain period of time has elapsed is that the above-mentioned zero direction (D0) is reverse direction (R), it is determined that there is a fault in another section and the above-mentioned point (P) is not opened.

[0174] For example, the trip signal may not be applied to the relay unit (10), or the control signal currently being applied to the relay unit (10) may be generated as a signal that keeps the one point (P) closed and applied to the relay unit (10).

[0175] Accordingly, the relay (100) may keep the one point (P) closed if, after a certain period of time, the zero-sequence direction (D0) becomes the reverse direction (R) while the positive-sequence direction (D1) is in the reverse direction (R) and the zero-sequence direction (D0) is in the forward direction (F).

[0176] The above-mentioned controlling step (S40) can control the operation of the relay (100) so that if, based on the comparison result (S30), the positive component directionality (D1) is in the forward direction (F) and the zero component directionality (D0) is in the reverse direction (R), the one point (P) is not opened.

[0177] The above-mentioned controlling step (S40) can control the operation of the relay (100) to keep the one point (P) closed by determining that there is a fault in another section when the normal direction (D1) is in the forward direction (F) and the zero direction (D0) is in the reverse direction.

[0178] For example, the trip signal may not be applied to the relay unit (10), or the control signal currently being applied to the relay unit (10) may be generated as a signal that keeps the one point (P) closed and applied to the relay unit (10).

[0179] Accordingly, the relay (100) may keep the one point (P) closed if the positive component directionality (D1) is in the forward direction (F) and the zero component directionality (D0) is in the reverse direction (R).

[0180] The operation algorithm according to the above-described control circuit (20), the above-described relay (100), and the above-described control method is summarized as follows.

[0181] <When the normal component direction (D1) and the image component direction (D0) are the same>

[0182] If a fault in the forward direction (F) is detected, it is determined to be a self-interval and the circuit breaker is opened.

[0183] It can be determined that the fault is in the magnetic path because the directionality of the normal and zero components is the same, and since both detected a fault in the forward direction, it can be determined that the fault is between the magnetic sections.

[0184] Therefore, the above one point (P) is opened.

[0185] <When the normal component direction (D1) and the image component direction (D0) are the same>

[0186] If a reverse (R) fault is detected, determine it to be a different section and do not open the circuit breaker.

[0187] It can be determined that the fault is in the self-direction path because the directionality of the normal and zero components is the same, and it can be determined that the fault is in another section because both detected a fault in the reverse direction.

[0188] Therefore, the above-mentioned point (P) is not opened.

[0189] <When the normal component direction (D1) and the image component direction (D0) are different>

[0190] If the zero-sequence direction (D0) is detected as forward (F) (the normal-sequence direction (D1) is reverse), wait for the MRT (minimum response time) of another circuit breaker (CB) in the system, and then check only the zero-sequence direction (D0) and open the circuit breaker only if it is in the forward direction (F).

[0191] When the normal component and the image component have different orientations and the image component is in the forward direction, wait for a certain amount of time (MRT or 100ms).

[0192] There are two possible cases of failure: (1) a failure in another line, or (2) a high-resistance ground fault between the self-line and the self-section.

[0193] In both cases, after a certain period of time, it becomes possible to determine whether the fault is on another line or within the same section, and the reason is as follows.

[0194] (1) In the event of a fault in another line, the fault is resolved if protection coordination for the fault in another line is achieved before this circuit breaker opens. For this reason, it is possible to wait for a certain amount of time (MRT or 100ms), and the fault condition of this circuit breaker is resolved and it may not open.

[0195] (2) In the event of a ground fault between the main circuit and the main section, if the opposite circuit breaker that coordinates protection with this circuit breaker opens first, the magnitude of the fault current experienced by this circuit breaker increases, and consequently, if the normal portion of the fault current becomes larger than the normal portion of the load, the directionality of both the normal portion and the zero portion becomes positive.

[0196] In this case, the fault between the self-path and self-section is clearly identified, and the circuit breaker is opened immediately with priority even during the opening waiting time.

[0197] Even after the entire opening waiting time has elapsed, if the zero-sequence directional is forward and the positive-sequence directional is reverse, it indicates that the fault persists despite the completion of protection coordination with other lines; therefore, it is determined to be a high-resistance ground fault between the self-line and self-section.

[0198] <When the normal component direction (D1) and the image component direction (D0) are different>

[0199] If the zero-sequence directionality (D0) detects a reverse direction (R) (the positive-sequence directionality (D1) is forward), the circuit breaker is not opened because it is not a ground fault between sections.

[0200] In this way, the control circuit (20), the relay (100), and the control method according to the embodiment calculate both the positive component directionality (D1) and the zero component directionality (D0) to distinguish between self-section and other-section faults, thereby enabling accurate distinction between self-section and other-section faults even in the protection blind spot area of ​​the existing method of determining faults between self and other lines based on whether the threshold voltage is exceeded using only the zero component voltage.

[0201] In conventional detection methods, the closer the outgoing circuit breaker is to the outgoing distribution line, the higher the possibility of misidentifying a fault in another line as a fault in the self line. However, by calculating both the positive directionality (D1) and the zero directionality (D0) as in the control circuit (20), relay (100), and control method according to the embodiment to distinguish between self-line and other-line faults, accurate fault classification and accurate operation can be achieved.

[0202] Meanwhile, the method for determining self-section / other-section according to the above-described control circuit (20), relay (100), and control method may be implemented as a power distribution system (1) according to the embodiment shown in FIG. 11.

[0203] The above distribution system (1) is a distribution system comprising, as shown in FIG. 11, a plurality of distribution lines (DG#N) branched from a system (MG) and connected by loop distribution in at least one pair, a plurality of circuit breakers (CB) installed at each branching point where the plurality of distribution lines (DG#N) branch off from the system (MG), and a plurality of relays (100, 100') installed at each of each of the plurality of distribution lines (DG#N) to open or close the installed points, wherein the plurality of relays (100) of the loop lines (DG#1, DG#2) connected by loop distribution include a plurality of first relays (100) installed at each of the branching points and adjacent points (P) among the plurality of points, and a plurality of second relays (100') installed at each of one or more points after the branching point (P).

[0204] The above-mentioned power distribution system (1) can be applied to a loop power distribution system as illustrated in FIG. 6. In the above-mentioned power distribution system (1), each of the plurality of first relays (100) determines whether the current corresponds to a current to be cut off based on the result of detecting the current and voltage of each of the above-mentioned points (P). If the current corresponds to a current to be cut off, the positive component directionality (D1) and zero component directionality (D0) of the voltage are calculated, and if the zero component directionality (D0) is in the forward direction, the above-mentioned point (P) is opened according to whether it matches the positive component directionality (D1).

[0205] The above plurality of first relays (100) may not communicate with each of the above plurality of circuit breakers (CB).

[0206] The above plurality of first relays (100) can keep the one point (P) open if the current does not correspond to the current to be cut off.

[0207] The above plurality of first relays (100) can open the one point (P) when the positive component directionality (D1) matches the zero component directionality (D0) in the forward direction (F).

[0208] That is, the plurality of first relays (100) can open the one point (P) by determining that there is a fault in the self-section when the positive component directionality (D1) is in the forward direction (F) and the zero component directionality (D0) is in the forward direction (F).

[0209] The above plurality of first relays (100) can keep the one point (P) closed if the positive component directionality (D1) does not match the zero component directionality (D0) in the forward direction (F).

[0210] That is, the plurality of first relays (100) can determine that the fault in another section is a fault when the positive component directionality (D1) is in the forward direction (F) and the zero component directionality (D0) is in the reverse direction (R), and thus keep the one point (P) closed.

[0211] The above plurality of first relays (100) can recalculate the zero-sequence direction (D0) after a certain period of time if the positive-sequence direction (D1) is in the reverse direction (R) and does not match the zero-sequence direction (D0), and if the recalculation result shows that the zero-sequence direction (D0) is in the forward direction (F), the above one point (P) can be opened.

[0212] That is, the plurality of first relays (100) can open the one point (P) by determining that there is a fault in the self-section when, after a certain period of time has elapsed, the zero-sequence direction (D0) becomes the forward direction (F) while the positive-sequence direction (D1) is in the reverse direction (R) and the zero-sequence direction (D0) is in the forward direction (F).

[0213] The above plurality of first relays (100) can recalculate the zero-sequence direction (D0) after a certain period of time if the positive-sequence direction (D1) is in the reverse direction (R) and does not match the zero-sequence direction (D0), and if the recalculation result shows that the zero-sequence direction (D0) is in the reverse direction (R), the above one point (P) can be kept closed.

[0214] That is, the plurality of first relays (100) can determine that the zero-sequence direction (D0) is reversed (R) and the zero-sequence direction (D0) is forward (F) after a certain period of time has elapsed, and thus the one point (P) can be kept closed by determining that there is a fault in another section.

[0215] Although embodiments of the control circuit (20), the relay (100), the control method, and the power distribution system (1) have been described so far, the described embodiments may be modified in various ways without departing from the scope of the present invention, and the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims set forth below as well as equivalents thereof.

Claims

1. In a control circuit of a relay installed at a point on a distribution line where a circuit breaker is installed, A detection unit for detecting current and voltage at the above-mentioned point; and It includes a calculation unit that controls the relay unit of the relay to open or not open the one point based on the detection result of the detection unit, and The above operation unit is, A control circuit for a relay characterized by determining whether the current corresponds to a current to be blocked based on the above detection result, calculating and comparing the positive and zero directionality of the voltage respectively according to the determination result, and controlling the relay to open or not open the above point according to the comparison result.

2. In Paragraph 1, The above operation unit is, A control circuit of a relay characterized by calculating the positive component directionality and the zero component directionality, respectively, if, based on the above judgment result, the above current corresponds to the current to be blocked.

3. In Paragraph 1, The above operation unit is, A control circuit for a relay characterized by controlling the relay unit to open or not open the aforementioned point according to the matching direction when the above comparison result shows that the above normal component direction and the above zero component direction match.

4. In Paragraph 3, The above operation unit is, A control circuit for a relay characterized by controlling to open the one point if, based on the above comparison result, the above positive component directionality and the above zero component directionality are in the forward direction.

5. In Paragraph 1, The above operation unit is, A control circuit for a relay characterized by controlling the relay unit to open or not open the aforementioned point according to the aforementioned direction of 6. In Paragraph 5, The above operation unit is, A control circuit for a relay characterized by controlling the relay unit to open or not open the above point according to the result of the recalculation, wherein if the above comparison result indicates that the above-mentioned directionality is in the forward directionality, the above-mentioned directionality is recalculated after a certain period of time.

7. In Paragraph 6, The above schedule time is, A control circuit of a relay characterized by being the operating time of another protection device installed on the above distribution line.

8. In Paragraph 6, The above operation unit is, A control circuit for a relay characterized by controlling to open the above point if, as a result of the above recalculation, the above image component directionality is in the forward direction.

9. In a relay installed at a point on a distribution line where a circuit breaker is installed, A relay unit that opens the above-mentioned point upon application of a trip signal; and A relay characterized by including a control unit that determines whether the current corresponds to a current to be cut off based on the result of detecting the current and voltage at the above-mentioned point, calculates and compares the positive and zero-sequence directionality of the voltage respectively according to the determination result, and controls the relay unit to open or not open the above-mentioned point according to the comparison result.

10. In Paragraph 9, The above control unit is, If the above current corresponds to the above blocking target current, the positive component directionality and zero component directionality of the above voltage are calculated, and A relay characterized by generating the trip signal and applying it to the relay unit depending on whether it matches the normal direction of the above-mentioned image component direction when the above-mentioned image component direction is in the forward direction.

11. In Paragraph 10, The above control unit is, A relay characterized by generating a trip signal and applying it to the relay unit when the above-mentioned positive component directionality matches the above-mentioned zero component directionality in the forward direction.

12. In Paragraph 10, The above control unit is, A relay characterized by recalculating the direction of the zero component after a certain period of time if the direction of the positive component is in the reverse direction and does not match the direction of the zero component, and generating the trip signal and applying it to the relay unit if the result of the recalculation is that the direction of the zero component is in the forward direction.

13. A method for controlling a relay installed at a point on a distribution line where a circuit breaker is installed, A step of detecting the current and voltage at the above-mentioned point; A step of determining whether the above current corresponds to a current to be blocked based on the detection result; A step of calculating and comparing the positive component directionality and zero component directionality of the above voltage according to the judgment result; and A method for controlling a relay, characterized by including a step of controlling the operation of the relay to open or not open the above-mentioned point according to a comparison result.

14. In Paragraph 13, The above-mentioned controlling step is, Based on the above comparison result, if the above positive component direction and the above zero component direction match in the forward direction, the operation of the relay is controlled to open the above one point, and A method for controlling a relay, characterized by controlling the operation of the relay to keep the one point closed when, based on the above comparison result, the normal component direction and the zero component direction match in opposite directions.

15. In Paragraph 13, The above-mentioned controlling step is, Based on the above comparison result, if the positive component direction is reversed and the zero component direction is forward, the zero component direction after a certain period of time is recalculated, and if the recalculated result shows that the zero component direction is forward, the operation of the relay is controlled to open the one point, and if the zero component direction is reversed, the one point is not opened. A method for controlling a relay, characterized by controlling the operation of the relay such that, based on the above comparison result, if the normal component direction is forward and the zero component direction is reverse, the one point is not opened.

16. Multiple distribution lines branched from the system, with at least one pair connected to loop distribution; A plurality of circuit breakers installed at each of the branching points where the above plurality of distribution lines branch off from the system; and In a power distribution system comprising a plurality of relays installed at each of a plurality of points of each of the plurality of power distribution lines, for opening or closing the installed points, A plurality of relays of the loop line connected to the above-mentioned loop distribution, A plurality of first relays installed at each of the branch points and each of the adjacent points among the plurality of points; and It includes a plurality of second relays installed at each of one or more points after the above-mentioned point, and Each of the above plurality of first relays is, A power distribution system characterized by determining whether the current corresponds to a current to be cut off based on the results of detecting the current and voltage at each of the above points, and if the current corresponds to the current to be cut off, calculating the positive and zero directionality of the voltage, and if the zero directionality is positive, opening the above points according to whether it matches the positive directionality.

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