KR-20260067832-A - CIRCUT FOR CONTROLLING RELAY, RELAY, METHOD FOR CONTROLLING RELAY AND DISTRIBUTION SYSTEM

KR20260067832AKR 20260067832 AKR20260067832 AKR 20260067832AKR-20260067832-A

Abstract

The present specification relates to an embodiment of a control circuit for a relay, a relay, a method for controlling a relay, and a power distribution system, wherein the current and voltage at a point where the relay is installed are detected, the current is determined based on the detection result to determine whether the current corresponds to a current to be cut off, the positive and zero directionality of the voltage is calculated and compared according to the determination result, and the point is opened or closed according to the comparison result.

Inventors

이현명

Assignees

엘에스일렉트릭(주)

Dates

Publication Date: 20260513
Application Date: 20241106

Claims (16)

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.
In Article 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.
In Article 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.
In Paragraph 3, The above operation unit is, A control circuit of 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.
In Article 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
In Article 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.
In Article 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.
In Article 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.
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.
In Article 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.
In Article 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.
In Article 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.
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.
In Article 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, as a result of the above comparison, the normal component direction and the zero component direction match in opposite directions.
In Article 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.
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.

Description

Control circuit for relay, relay, method for controlling relay and distribution system 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. 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. 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. 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. Figure 4 illustrates the operation sequence of such a conventional directional ground fault overcurrent relay. Normal current measurement is performed, and a fault is recognized when a current exceeding a designated Pickup current value (I pick_up ) 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 forward, it is determined that there is a fault in the self-section, 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. 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. One of the problems that arises when protecting the CB-IED section with DOCR/DOCGR (non-communication) in this way is the case illustrated