KR20220008644A - Overcurrent relay used for electric power system provided with a fault current limiter, overcurrent relay method thereby, protection cooperation system and protection cooperation method - Google Patents

Abstract

Provided is an overcurrent relay device which measures a line current of a system, measures a voltage of a bus bar connected to the system, and measures a voltage of a fault current limiter provided on a line to calculate fault current limiter impedance caused by a fault current occurring at any point on the line from a fault current limiter voltage and calculate an operating variable so as to compensate for the calculated fault current limiter impedance, thereby performing a protection operation according to the operating variable.

Description

OVERCURRENT RELAY USED FOR ELECTRIC POWER SYSTEM PROVIDED WITH A FAULT CURRENT LIMITER, OVERCURRENT RELAY METHOD THEREBY, PROTECTION COOPERATION SYSTEM AND PROTECTION COOPERATION SYSTEM AND PROTECTION COOPERATION SYSTEM METHOD}

The present invention relates to an overcurrent relay used in a power system provided with a current limiter, an overcurrent relay method, a protection cooperation system and a protection cooperation method using the same, and more particularly, an overcurrent relay for performing a protection operation in a power system provided with a current limiter, It relates to an overcurrent relay method, a protection coordination system using the same, and a protection coordination method.

The overcurrent relay is a protective relay that controls the circuit breaker to block the line when a fault occurs in the system and a very large fault current flows. The overcurrent relay accumulates a value according to the internal operation of the overcurrent relay when a fault current greater than a set threshold is continuously detected, and operates the circuit breaker when the accumulated value exceeds a certain value.

On the other hand, as an effective method for limiting the fault current, there is a method of applying a superconducting fault current limiter (SFCL). The superconducting current limiter has the characteristic of quickly limiting the fault current within 1/4 cycle, and has the advantage of no loss because the resistance is 0 in normal use.

However, when the fault current is limited by using a superconducting current limiter, the operation of an overcurrent relay (OCR) installed in the same system is affected, and a negative operation occurs due to a change in the operation area of the overcurrent relay. Therefore, there is a need for a method capable of minimizing the influence of the overcurrent relay due to a fault current limiter (FCL) in the power system.

The technical problem to be solved by the present invention is to provide an overcurrent relay capable of minimizing the delay of a trip time due to a current limiter and a method therefor.

In addition, the technical problem to be solved by the present invention is a protective cooperation system and method using an overcurrent relay capable of minimizing the delay of the trip time by the current limiter for the protective cooperative operation of a plurality of overcurrent relays provided in the power system in which the current limiter is installed. is to provide

One aspect of the present invention, the line current measuring unit for measuring the line current of the line connected to the load side from the grid power; a bus voltage measuring unit for measuring a bus voltage of a bus connected to the grid power; a current-limiting voltage measuring unit for measuring a current-limiting voltage of the current-limiting device provided on the line; and a fault current that occurs at any point on the line from the fault current limiter voltage and calculates a fault current limiter impedance generated by a fault current appearing from the line current, and based on the fault current and the bus voltage, the calculated fault current limiter The control unit may include a control unit that calculates an operating variable so that impedance is compensated, and performs a protection operation according to the operating variable.

In addition, the control unit includes a trip time indicating a time interval from the time when the fault current occurs to the time at which the protection operation is performed, with respect to a change in fault current caused by a fault current occurring at an arbitrary point on the line. The operation variable provided to be constant may be calculated.

In addition, the control unit extracts, on the line, a first proportional coefficient matching the bus voltage that is changed according to a point at which the fault current occurs, and a fault that occurs at any point on the line to generate the fault current A second proportional coefficient matching at least one of a type of , or a transient state of the fault current may be extracted.

In addition, the controller is configured to divide a product of the first scaffolding coefficient and a preset operating impedance by a value obtained by subtracting the product of the second proportional coefficient and the current limiter impedance from the line impedance according to the line current. variables can be calculated.

In addition, the control unit calculates a line resistance representing an active component and a line reactance representing an ineffective component from the line impedance according to a frequency appearing in the line current, and according to a frequency appearing from the fault current limiter voltage, the current limiter impedance The current limiter resistance representing the active component and the current limiter reactance representing the reactive component may be calculated from , and the operating variables may be calculated so that the active and reactive components of the line current and the current limiter voltage are corrected.

Also, the controller may compare the operation variable with a preset reference value, and generate a trip signal provided to perform a protection operation when the operation variable is greater than the reference value.

Another aspect of the present invention provides an overcurrent relay method using an overcurrent relay used in a power system provided with a current limiter, comprising: measuring a line current of a line connected from a grid power source to a load side; measuring a bus voltage of a bus connected to the grid power; From the fault current limiter voltage, a fault current limiter impedance generated by a fault current appearing from the line current generated at an arbitrary point on the line is calculated, and the fault current limiter impedance is calculated based on the fault current and the bus voltage. calculating an operation variable to compensate for ; and performing a protection operation according to the operation variable.

In addition, the calculating of the operation variable may include: a time interval from a time point at which the fault current occurs to a time point at which the protection operation is performed with respect to a change in current limiter impedance due to a fault current occurring at an arbitrary point on the line. It is possible to calculate the operation variable provided so that the trip time indicating the constant.

In addition, the calculating of the operating variable may include extracting, on the line, a first proportional coefficient matching the bus voltage, which is changed according to a point at which the fault current occurs, and generating the fault at any point on the line. A second proportional coefficient matching at least one of a type of fault generating a current or a transient state of the fault current may be extracted.

In addition, the calculating of the operating variable may include dividing a product of the first scaffolding coefficient and a preset operating impedance by a value obtained by subtracting the product of the second proportional coefficient and the current-limiting impedance from the line impedance according to the line current. It is possible to calculate an action variable that appears as a result value.

In addition, the calculating of the operating variable includes calculating a line resistance representing an active component and a line reactance representing an ineffective component from the line impedance according to a frequency appearing in the line current, and according to a frequency appearing from the current limiter voltage , by calculating a fault current limiter resistance representing an active component and a fault current limiter reactance representing a reactive component from the fault current limiter impedance, an operating variable may be calculated such that the active and reactive components of the line current and the fault current limiter voltage are corrected.

In addition, the calculating of the operating variable may include comparing the operating variable with a preset reference value, and generating a trip signal provided to perform a protection operation when the operating variable is greater than the reference value. .

In another aspect of the present invention, in a protection cooperation system using an overcurrent relay used in a power system provided with a current limiter, it is installed on a line connecting the system power source and a first load, and the current limiter of the current limiter provided on the line Calculating a fault current limiter impedance generated by a fault current occurring at an arbitrary point on the line from a voltage, calculating an operation variable so that the calculated fault current limiter impedance is compensated, and performing a protection operation according to the operation variable 1 overcurrent relay; And it is installed on the line connecting the first overcurrent relay and the second load, the current limiter impedance generated by the fault current generated at any point on the line from the current limiter voltage of the current limiter provided on the line is calculated, , a second overcurrent relay that calculates an operation variable so that the calculated current-limiting impedance is compensated, and performs a protection operation according to the operation variable.

In addition, the first overcurrent relay may be provided to perform one of a potential protection operation and a back-up protection operation according to a point at which a fault current occurs on the line.

In addition, the first overcurrent relay determines the point at which the fault current occurs, and when it is determined that the second overcurrent relay is installed between the point at which the fault current occurs and the first overcurrent relay, a back-up protection operation can be done

In addition, when it is determined that the first overcurrent relay generates a trip signal indicating that the second overcurrent relay performs the protection operation, it is possible to perform a backup protection operation for the fault current generated on the line. .

Another aspect of the present invention provides a protection cooperation method using an overcurrent relay used in a power system provided with a current limiter, comprising: measuring a current limiter voltage of the current limiter provided on the line; calculating a fault current limiter impedance generated by a fault current occurring at an arbitrary point on the line from the fault current limiter voltage, and calculating an operating variable so that the calculated fault current limiter impedance is compensated; determining a point at which the fault current occurs; and performing one of a potential protection operation and a back-up protection operation according to the operation variable and a point at which the fault current occurs.

In addition, in the step of performing one of the potential protection operation and the back-up protection operation, when it is determined that a second over-current relay is installed between the point where the fault current occurs and the first over-current relay, the back-up protection operation can be performed.

In addition, in the step of performing one of the potential protection operation and the back-up protection operation, when it is determined that a trip signal indicating that the protection operation is performed in the second overcurrent relay is generated, a fault current generated on the line , a reserve protection operation may be performed.

According to the above-described aspect of the present invention, by providing an overcurrent relay used in a power system provided with a current limiter and a method therefor, it is possible to minimize the delay in trip time by the current limiter.

In addition, according to the above-described aspect of the present invention, it is possible to minimize the delay of the trip time by the current limiter with respect to the protective cooperative operation of the plurality of overcurrent relays provided in the power system in which the current limiter is installed.

1 is a schematic diagram of a system in which an overcurrent relay according to an embodiment of the present invention is installed.
2 is a control block diagram of the overcurrent relay of FIG.
3 is a schematic diagram illustrating a process of performing a protection operation in the control unit of FIG. 2 .
4 is a schematic diagram illustrating an embodiment of a system in which a plurality of overcurrent relays of FIG. 1 are installed.
5 is a flowchart of an overcurrent relay method according to an embodiment of the present invention.
6 is a flowchart of a protection cooperation method using an overcurrent relay according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0010] Reference is made to the accompanying drawings, which show by way of illustration specific embodiments in which the present invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present invention. It should be understood that the various embodiments of the present invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein with respect to one embodiment may be implemented in other embodiments without departing from the spirit and scope of the invention. In addition, it should be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the present invention. Accordingly, the detailed description set forth below is not intended to be taken in a limiting sense, and the scope of the present invention, if properly described, is limited only by the appended claims, along with all scope equivalents as those claimed. Like reference numerals in the drawings refer to the same or similar functions throughout the various aspects.

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

1 is a schematic diagram of a system in which an overcurrent relay according to an embodiment of the present invention is installed.

The overcurrent relay 400 may be installed on a line 600 connected from the grid power source 100 to the load 200 side.

Here, the grid power 100 may include an AC power source and a transformer connected to the AC power source, and a protection device may be constructed between the AC power source and the transformer.

Accordingly, the line 600 may be provided to transmit power output from the grid power source 100 to the load 200, and at this time, the region from the grid power source 100 to the load 200 may be understood as a grid. have.

In this regard, the grid may include a grid power source 100 and a load 200, and the grid is a bus connected to the grid power source 100, a circuit breaker 300, an overcurrent relay 400, a line 600, Electrical equipment such as a fault current limiter (FCL) 500 may be included.

Here, the current limiter 500 may be provided to electrically cut off the circuit or generate a certain resistance in the current limiter 500 when the current flowing through the current limiter 500 exceeds a predetermined value, for example. For example, the current limiter 500 operates with a resistance of 0 when a current less than a preset threshold value passes through the current limiter 500 , and a current exceeding the threshold value flows through the current limiter 500 . When passing through the current limiter 500 , a superconducting fault current limiter (SFCL) in which the resistance of the current limiter 500 increases according to the magnitude of the current passing through the current limiter 500 may be used.

As such, the current limiter 500 may be connected to one side of the circuit breaker 300 to limit the fault current when a fault current occurs at any point in the system.

Meanwhile, the system may include a plurality of loads 200 , and in this case, the overcurrent relay 400 may be installed on the line 600 connected to each load 200 .

For example, the overcurrent relay 400 may be installed in the line 600 to which the bus bar connected to the grid power supply 100 and the arbitrary load 200 are connected, and the overcurrent relay 400 is an arbitrary load ( From a point where 200 is connected to the line 600 , it may be installed on the line 600 to which another load 200 is connected.

Here, the overcurrent relay 400 may be included in the circuit breaker 300, and in this case, the overcurrent relay 400 measures the line current flowing through the line 600, and according to the line current, electrical such as a short circuit accident. When a fault current is generated due to an accident, the circuit breaker 300 may be provided to block the line 600 .

Here, the line current may mean a line current flowing through the line 600 .

Meanwhile, the circuit breaker 300 may be provided to electrically cut off the line 600 when a fault current greater than or equal to the rated current of the circuit breaker 300 occurs in the line 600 .

Also, the circuit breaker 300 may electrically cut off the line 600 when a trip signal provided for the circuit breaker 300 to block the line 600 is transmitted from the overcurrent relay 400 .

Here, the trip signal may be a signal provided so that the overcurrent relay 400 determines that a fault current has occurred in the line 600 , and the circuit breaker 300 electrically cuts the line 600 . At this time, the line 600 .

In other words, the trip time may represent a time interval from a point in time when a fault current occurs in the line 600 due to an electrical accident to a point in time when the overcurrent relay 400 determines that a fault current occurs in the line 600 .

Hereinafter, the overcurrent relay 400 according to an embodiment of the present invention will be described in detail.

2 is a control block diagram of the overcurrent relay of FIG.

The overcurrent relay 400 may include a line current measurement unit 410 , a bus voltage measurement unit 420 , a current limiter voltage measurement unit 430 , and a control unit 440 .

The line current measuring unit 410 and the line current measuring unit 410 may measure the line current of the line 600 connected from the grid power 100 to the load 200 .

To this end, the line current measuring unit 410 may be connected to the line 600 in the form of a current transformer to measure the line current flowing through the line 600 .

The bus voltage measuring unit 420 may measure a bus voltage of a bus connected to the grid power source 100 .

To this end, the bus voltage measuring unit 420 may be connected to the bus in the form of a transformer or an instrument transformer to measure the bus voltage.

In this case, the bus voltage measuring unit 420 may be provided to measure the bus voltage of the bus closest to the grid power 100 side when a plurality of bus bars are provided in the system.

The current limiter voltage measuring unit 430 may measure the current limiter voltage of the current limiter 500 provided on the line 600 .

To this end, the current limiter voltage measuring unit 430 may be connected to the current limiter 500 in the form of a transformer or an instrument transformer to measure the current limiter voltage.

Here, the fault current limiter voltage measuring unit 430 may be provided to measure the voltage difference between both ends of the fault current limiter 500 provided on the line 600 . In this case, the fault current limiter voltage is the current limiter 500 . It can be understood as the voltage difference between the two ends.

The control unit 440 may calculate a fault current limiter impedance generated by a fault current occurring at an arbitrary point on the line 600 from the fault current limiter voltage, and the control unit 440 calculates it based on the fault current and the bus voltage. An operating variable may be calculated so that the current fault current-limiting impedance is compensated, and the controller 440 may perform a protection operation according to the operating variable.

Here, the fault current may mean an abnormal current that appears in the line 600 due to an electrical accident such as a ground fault, short circuit, disconnection, lightning strike, etc. occurring at any point in the system, and this fault current is on the line 600 . It can occur at any point, resulting from the line current.

In addition, the fault current limiter impedance may mean resistance or reactance appearing from the fault current limiter 500 .

The controller 440 may calculate an operation variable according to Equation 1 below.

Here, M_Z may mean an operating variable, Z_feeder may mean a line impedance, and Z_FCL may mean a current-limiting impedance. In addition, Z_pickup may mean an operating impedance set so that the overcurrent relay 400 performs a protection operation, and K_1 is a first proportionality matched to the bus voltage that is changed according to the point where the fault current occurs on the line 600 . may mean a coefficient, and K_2 may mean a second proportional coefficient that matches at least one element of a type of failure that occurs at any point on the line 600 and generates a fault current or a transient state of the fault current. have.

Accordingly, the control unit 440 divides the product of the first scaffolding coefficient and the preset operating impedance by the value obtained by subtracting the product of the second proportional coefficient and the current limiter impedance from the line impedance according to the line current. can be calculated.

Here, the first proportional coefficient may be preset according to the value of the bus voltage that changes depending on the point at which the fault current occurs. In this case, the control unit 440 determines the point at which the fault current occurs, and the point at which the fault current occurs. If it is determined that another overcurrent relay 400 is installed between the overcurrent relay 400, the first overcurrent relay 400 installed between the point where the fault current occurs and the overcurrent relay 400 is installed according to the number of the first You can set the proportional coefficient to any other value.

For example, when the overcurrent relay 400 operates as a potential with respect to a fault current generated in the system, the control unit 440 may set the first proportional coefficient to 0.49, and the control unit 440 may control the overcurrent relay 400. In the case where the system operates as a backup for the fault current generated in the system, the first proportional coefficient may be set to 0.75.

At this time, with respect to the fault current generated in the system, the control unit 440 may determine whether the overcurrent relay 400 operates at a potential or operates as a reserve, depending on the presence or absence of a trip signal generated from another overcurrent relay 400. have.

To this end, the overcurrent relay 400 may provide a separate communication unit to receive a trip signal generated from another overcurrent relay 400 or transmit a trip signal to another overcurrent relay 400 .

In addition, the second proportionality coefficient may be set in advance according to at least one factor of a type of fault generating a fault current generated at an arbitrary point on the line 600 or a transient state of the fault current, for example, The second proportionality coefficient may be set differently depending on the type of electrical accident such as a ground fault, short circuit, disconnection, or lightning strike occurring at any point on the line 600 .

Meanwhile, the control unit 440 may calculate the operating variable so that the active and ineffective components of the line current and the current-limiting voltage are corrected according to Equation 2 below.

Here, M_Z may mean an operating variable, Z_feeder may mean a line impedance, and Z_FCL may mean a current-limiting impedance. In addition, Z_pickup may mean an operating impedance set so that the overcurrent relay 400 performs a protection operation, K_1 may mean a first proportional coefficient, and K_2 may mean a second proportional coefficient. Also, Theta_feeder may mean a phase of line impedance, and Theta_FCL may mean a phase of a fault current limiter impedance.

In this way, the control unit 440 can calculate the line resistance representing the active component and the line reactance representing the ineffective component from the line impedance according to the frequency shown in the line current, and the control unit 440 is the frequency shown from the fault current limiter voltage. Accordingly, the fault current limiter resistance representing the active component and the fault current limiter reactance representing the invalid component can be calculated from the fault current limiter impedance.

Accordingly, the controller 440 may calculate the operating variable so that the active and ineffective components of the line current and the fault current limiter voltage are corrected.

The control unit 440 sets a trip time indicating a time interval from the time when the fault current occurs to the time when the protection operation is performed, with respect to a change in the fault current limiter impedance due to a fault current occurring at an arbitrary point on the line 600 . It is possible to calculate an operation variable that is provided to be changed.

In this case, the controller 440 may compare the operation variable with a preset reference value, and when the operation variable is greater than the reference value, the controller 440 may generate a trip signal to perform the protection operation.

Here, the protection operation may be that the controller 440 generates a trip signal and transmits the trip signal to the circuit breaker 300 so that the circuit breaker 300 electrically blocks the line 600 .

For example, the preset reference value may be set to 2, and in this case, the control unit 440 may generate a trip signal when the operation variable calculated by the control unit 440 exceeds 2 have.

In this regard, the trip time from the point in time when a fault current is generated in the line 600 due to an electrical accident to the point in time when the trip signal is generated in the controller 440 may be calculated according to Equation 3 below.

In Equation 3, T_trip may represent a trip time, and M may represent an operation variable. In addition, TD may represent a time dial (Time Dial), A, B, P may represent a characteristic value of the overcurrent relay 400, where TD, A, B, P are preset values can be understood as

Here, since the operating variable may be maintained at a constant value with respect to the current limiter impedance changed by the fault current generated in the system, the trip time may appear at regular time intervals even if the current limiter impedance changes.

As such, in the overcurrent relay 400, even if the fault current that occurs in the system changes the fault current limiter impedance, there may be an effect that the trip time according to the generation of the fault current is constant.

3 is a schematic diagram illustrating a process of performing a protection operation in the control unit of FIG. 2 .

Referring to FIG. 3 , the line current measuring unit 410 and the line current measuring unit 410 may measure the line current of the line 600 connected from the grid power 100 to the load 200 side, and the bus voltage The measurement unit 420 may measure a bus voltage of a bus connected to the grid power 100 .

In this case, the current limiter voltage measuring unit 430 may measure the current limiter voltage of the current limiter 500 provided on the line 600 .

Accordingly, the controller 440 can calculate the current limiter impedance generated by a fault current generated at an arbitrary point on the line 600 from the current limiter voltage, and the controller 440 compensates for the calculated current limiter impedance. The operation variable can be calculated as much as possible.

Here, the control unit 440 divides the product of the first scaffolding coefficient and the preset operating impedance by the value obtained by subtracting the product of the second proportional coefficient and the current limiter impedance from the line impedance according to the line current. can be calculated.

In this regard, the control unit 440 may calculate a line resistance representing an effective component and a line reactance representing an invalid component from the line impedance according to a frequency appearing in the line current, and the control unit 440 may calculate a frequency appearing from the fault current limiter voltage. Accordingly, it is possible to calculate the fault current limiter resistance representing the active component and the fault current limiter reactance representing the invalid component from the fault current limiter impedance.

Accordingly, the controller 440 may calculate the operating variable so that the active and ineffective components of the line current and the fault current limiter voltage are corrected.

In this way, the control unit 440, in response to a change in current limiter impedance due to a fault current occurring at an arbitrary point on the line 600, a trip indicating a time interval from the time when the fault current occurs to the time when the protection operation is performed. It is possible to calculate an operation variable provided so that the time is constant.

The controller 440 may perform a protection operation according to an operation variable. Here, the protection operation may be that the controller 440 generates a trip signal and transmits the trip signal to the circuit breaker 300 so that the circuit breaker 300 electrically blocks the line 600 .

To this end, the controller 440 may compare the operation variable with a preset reference value, and when the operation variable is greater than the reference value, the controller 440 may generate a trip signal provided to perform the protection operation. .

4 is a schematic diagram illustrating an embodiment of a system in which a plurality of overcurrent relays of FIG. 1 are installed.

4, it can be seen that the first overcurrent relay 400a is installed on the line 600 connecting the grid power 100 and the first load 200a, and the second overcurrent relay 400b is the first It can be seen that it is installed on the line 600 connecting the overcurrent relay 400a and the second load 200b.

In this regard, in one embodiment, it can be understood that the simulated distribution system is installed with a peripheral voltage of 154-22.9 kV, and the lines 600a, 600b, 600c, and 600d are installed at 10Km. At this time, it can be understood that each line represents 2.5Km.

In this case, the first overcurrent relay 400a may be provided to perform one of a potential protection operation and a back-up protection operation according to a point at which a fault current occurs on the line 600 .

Accordingly, the first overcurrent relay 400a determines the point at which the fault current occurs, and the second overcurrent relay 400b is installed between the point at which the fault current occurs and the first overcurrent relay 400a. , it is possible to perform a back-up protection operation.

Here, the reserve protection operation may mean an operation of another overcurrent relay 400 that performs a protection operation after any overcurrent relay 400 performs the protection operation, for example, the backup protection operation is After the overcurrent relay 400b performs the protection operation, when the first overcurrent relay 400a performs the protection operation, it may mean the protection operation performed by the first overcurrent relay 400a.

At this time, it can be understood that the second overcurrent relay 400b has performed a potential protection operation.

In addition, when it is determined that the first overcurrent relay 400a generates a trip signal indicating that the protection operation is performed in the second overcurrent relay 400b, a backup protection operation for a fault current generated on the line 600 is performed. can be performed.

For example, when a failure occurs at point F1 on the line, the first overcurrent relay 400a may operate to block the line 600, and the first overcurrent relay 400a fails at point F2 on the line. When this occurs, a backup protection operation can be performed.

In addition, the second overcurrent relay 400b may perform a potential protection operation when a failure occurs at the point F2 on the line.

In other words, when a failure occurs at the point F2 on the line, the second overcurrent relay 400b performs a potential protection operation, and then the first overcurrent relay 400a may be provided to perform a back-up protection operation. have.

In this regard, the first proportional coefficient of the first overcurrent relay 400a is determined when the first overcurrent relay 400a performs a potential protection operation and when the first overcurrent relay 400a performs a backup protection operation. For each, it may be set differently.

For example, when the first overcurrent relay 400a operates at a potential with respect to the fault current generated in the system, the first proportional coefficient may be set to 0.49, and the first overcurrent relay 400a is the fault current generated in the system In the case of operating as a secondary ratio for , the first proportional coefficient may be set to 0.75.

In this regard, a plurality of overcurrent relays 400 may be installed in the system, and in this case, the overcurrent relay 400 may change the order of protection operations according to the protective cooperative relationship with other overcurrent relays 400. In the overcurrent relay 400, the first proportional coefficient may be set to a different value according to the order of the protection operation.

In this way, a plurality of overcurrent relays 400 are installed in the system, and a protective cooperation system in which a protective cooperative relationship between each overcurrent relay 400 is set can be established. Accordingly, the protective cooperative system using the overcurrent relay is It may be provided to perform a protection operation according to a protection cooperative relationship between a plurality of overcurrent relays 400 installed in the system.

5 is a flowchart of an overcurrent relay method according to an embodiment of the present invention.

Since the overcurrent relay method according to an embodiment of the present invention proceeds in substantially the same configuration as the overcurrent relay 400 shown in FIG. 1 , the same reference numerals are given to the same components as the overcurrent relay 400 of FIG. 1 . and repeated descriptions will be omitted.

The overcurrent relay method includes the steps of measuring the line current (600), measuring the bus voltage (610), measuring the current limiter voltage (620), calculating the operation variable (630), and performing a protection operation. step 640 .

The step 600 of measuring the line current may be a step in which the line current measuring unit 410 measures the line current of the line 600 connected from the grid power source 100 to the load 200 side.

The step 610 of measuring the bus voltage may be a step in which the bus voltage measuring unit 420 measures the bus voltage of the bus connected to the grid power source 100 .

The step 620 of measuring the fault current limiter voltage may be a step in which the fault current limiter voltage measuring unit 430 measures the fault current limiter voltage of the fault current limiter 500 provided on the line 600 .

In the step 630 of calculating the operation variable, the controller 440 calculates the fault current caused by a fault current occurring at an arbitrary point on the line 600 from the fault current limiter voltage, and the calculated fault current limiter impedance is compensated. It may be a step of calculating an operation variable as much as possible.

The step 640 of performing the protection operation may be a step in which the controller 440 performs the protection operation according to an operation variable.

6 is a flowchart of a protection cooperation method using an overcurrent relay according to an embodiment of the present invention.

The protection cooperation method using an overcurrent relay includes the steps of measuring the current-limiting voltage (800), calculating the operation variable (810), determining the point at which the fault current occurs (820), and the potential protection operation or the back-up protection operation. performing 830 .

The step 800 of measuring the fault current limiter voltage may be a step of measuring the fault current limiter voltage of the fault current limiter 500 provided on the line 600 .

In the step 810 of calculating the operation variable, the current-limiting impedance generated by a fault current generated at an arbitrary point on the line 600 from the current-limiting voltage is calculated, and the operation variable is calculated so that the calculated current-limiting impedance is compensated. It may be a step to

The step 820 of determining the point at which the fault current occurs may be the step of determining the point at which the fault current occurs.

The step 830 of performing the potential protection operation or the backup protection operation may be a step of performing one of the potential protection operation or the backup protection operation according to an operation variable and a point at which a fault current occurs.

Although the above has been described with reference to the embodiments, it will be understood by those skilled in the art that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the following claims. will be able

100: grid power
200: load
300: breaker
400: overcurrent relay
500: Korean Wave
600: track

Claims (19)

a line current measuring unit for measuring a line current of a line connected from the grid power source to the load side;
a bus voltage measuring unit for measuring a bus voltage of a bus connected to the grid power;
a current-limiting voltage measuring unit for measuring a current-limiting voltage of the current-limiting device provided on the line; and
From the fault current limiter voltage, a fault current limiter impedance generated by a fault current appearing from the line current generated at an arbitrary point on the line is calculated, and the fault current limiter impedance calculated based on the fault current and the bus voltage Comprising a control unit that calculates an operation variable to compensate for, and performs a protection operation according to the operation variable, the overcurrent relay.
According to claim 1, wherein the control unit,
The trip time indicating a time interval from the time when the fault current occurs to the time when the protection operation is performed is provided to be constant in response to a change in fault current caused by a fault current occurring at an arbitrary point on the line. An overcurrent relay that produces an operating variable.
According to claim 1, wherein the control unit,
extracting a first proportional coefficient matching the bus voltage that is changed according to the point where the fault current occurs on the line;
and extracting a second proportional coefficient matching at least one of a type of a fault generating the fault current and a transient state of the fault current occurring at an arbitrary point on the line.
According to claim 3, wherein the control unit,
Calculating an operating variable expressed as a result of dividing the product of the first scaffolding coefficient and the preset operating impedance by a value obtained by subtracting the product of the second proportional coefficient and the current limiter impedance from the line impedance according to the line current relay.
According to claim 4, wherein the control unit,
Line resistance representing the active component and line reactance representing the reactive component are calculated from the line impedance according to the frequency appearing in the line current, and the current limiting representing the active component from the fault current limiter impedance according to the frequency represented by the fault current limiter voltage An overcurrent relay, which calculates a current limiter reactance representing a resistance and a reactive component, and calculates an operating variable such that an active component and a reactive component of the line current and the current limiter voltage are corrected.
According to claim 1, wherein the control unit,
An overcurrent relay that compares the operation variable with a preset reference value and generates a trip signal configured to perform a protection operation when the operation variable is greater than the reference value.
In the overcurrent relay method using an overcurrent relay used in a power system provided with a current limiter,
measuring a line current of a line connected from the grid power source to the load side;
measuring a bus voltage of a bus connected to the grid power;
measuring a current limiter voltage of a current limiter provided on the line;
From the fault current limiter voltage, a fault current limiter impedance generated by a fault current appearing from the line current generated at an arbitrary point on the line is calculated, and the fault current limiter impedance calculated based on the fault current and the bus voltage calculating an operation variable to compensate for ; and
and performing a protection operation according to the operation variable.
The method of claim 7, wherein the calculating of the operation variable comprises:
The trip time indicating a time interval from the time when the fault current occurs to the time when the protection operation is performed is provided to be constant in response to a change in fault current caused by a fault current occurring at an arbitrary point on the line. An overcurrent relay method that calculates an operating variable.
The method of claim 7, wherein the calculating of the operation variable comprises:
extracting a first proportional coefficient matching the bus voltage that is changed according to the point where the fault current occurs on the line;
and extracting a second proportional coefficient matching at least one of a type of a fault generating the fault current and a transient state of the fault current occurring at an arbitrary point on the line.
The method of claim 9, wherein the calculating of the operation variable comprises:
Calculating an operating variable expressed as a result of dividing the product of the first scaffolding coefficient and the preset operating impedance by a value obtained by subtracting the product of the second proportional coefficient and the current limiter impedance from the line impedance according to the line current relay method.
The method of claim 10, wherein the calculating of the operation variable comprises:
Line resistance representing the active component and line reactance representing the reactive component are calculated from the line impedance according to the frequency appearing in the line current, and the current limiting representing the active component from the fault current limiter impedance according to the frequency represented by the fault current limiter voltage An overcurrent relaying method comprising calculating a current limiter reactance representing a resistance and a reactive component to calculate an operating variable such that an active component and a reactive component of the line current and the current limiter voltage are corrected.
The method of claim 7, wherein the calculating of the operation variable comprises:
Comparing the operating variable with a preset reference value, and generating a trip signal configured to perform a protection operation when the operating variable is greater than the reference value, the overcurrent relaying method.
In the protection cooperation system using an overcurrent relay used in a power system provided with a current limiter,
Installed on the line connecting the system power source and the first load, the current limiter impedance generated by a fault current occurring at any point on the line is calculated from the current limiter voltage of the current limiter provided on the line, and the calculated a first overcurrent relay that calculates an operation variable so that the current-limiting impedance is compensated and performs a protection operation according to the operation variable; and
Installed on the line connecting the first overcurrent relay and the second load, the current limiter impedance generated by the fault current occurring at any point on the line is calculated from the current limiter voltage of the current limiter provided on the line, and a second overcurrent relay that calculates an operation variable so that the calculated current-limiting impedance is compensated and performs a protection operation according to the operation variable.
The method of claim 13, wherein the first overcurrent relay,
A protection cooperation system using an overcurrent relay, which is provided to perform one of a potential protection operation and a back-up protection operation on the line according to a point at which a fault current occurs.
15. The method of claim 14, wherein the first overcurrent relay,
By determining the point at which the fault current occurs, when it is determined that the second overcurrent relay is installed between the point at which the fault current occurs and the first overcurrent relay, a back-up protection operation is performed, protection cooperation using an overcurrent relay system.
15. The method of claim 14, wherein the first overcurrent relay,
When it is determined that a trip signal indicating that the protection operation is performed in the second overcurrent relay is generated, a back-up protection operation is performed for a fault current generated on the line. A protection cooperation system using an overcurrent relay.
In the protection cooperation method using an overcurrent relay used in a power system provided with a current limiter,
measuring a current limiter voltage of a current limiter provided on the line;
calculating a fault current limiter impedance generated by a fault current occurring at an arbitrary point on the line from the fault current limiter voltage, and calculating an operating variable so that the calculated fault current limiter impedance is compensated;
determining a point at which the fault current occurs; and
and performing one of a potential protection operation and a back-up protection operation according to the operation variable and the point at which the fault current occurs.
18. The method of claim 17, wherein performing one of the potential protection operation and the back-up protection operation comprises:
When it is determined that a second overcurrent relay is installed between the point where the fault current occurs and the first overcurrent relay, a back-up protection operation is performed, a protection cooperation method using an overcurrent relay.
18. The method of claim 17, wherein performing one of the potential protection operation and the back-up protection operation comprises:
When it is determined that a trip signal indicating that the protection operation is performed in the second overcurrent relay is generated, a back-up protection operation is performed for a fault current generated on the line.

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