KR101090425B1 - Protection Coordination system in ungrounded distribution system and its operating method - Google Patents

Abstract

The present invention relates to a distribution protection coordination system and its operation method. More specifically, when a ground fault occurs in an ungrounded distribution line, it determines whether there is a fault and a fault in the switch, and removes the fault using the corresponding fault information. The present invention relates to a distribution protection coordination system and a method of operating the same, informing the operator of the occurrence of a failure by transmitting the corresponding failure information to the central control unit. In the distribution protection coordination system according to an embodiment of the present invention, when a ground fault occurs in an ungrounded distribution line, a failure occurs and a fault phase are determined using the phase difference between the image current and the phase voltage of the distribution line, and the failure occurs. And a terminal device for generating and transmitting fault recognition information including fault phase information, a switchgear for opening and closing the distribution line under control of the terminal device, and receiving the fault recognition information from the terminal device, and receiving at least one terminal device. It may include a distribution protection cooperation system including a distribution control device for transmitting a control signal for blocking the failure section by operating the switch at the point of failure through cooperation.

Power Distribution Protection Cooperation

Description

Protection Coordination system in ungrounded distribution system and its operating method}

The present invention relates to a distribution protection coordination system and its operation method. More specifically, when a ground fault occurs in an ungrounded distribution line, it determines whether there is a fault and a fault in the switch, and removes the fault using the corresponding fault information. The present invention relates to a distribution protection coordination system and a method of operating the same, informing the operator of a failure by transmitting the corresponding failure information to the distribution control device.

In case of short-circuit failure between phases in ungrounded power distribution line, similar to the ground line, a large fault current flows smoothly to identify the fault.However, in case of ground fault, the fault current is very small (hundreds to thousands of mA). It is difficult to judge whether or not.

It is an advantage of the ungrounded line because the fault current is small and the power supply can be continued, but if the fault persists due to abnormal voltage at the time of ground fault, there is a risk of equipment damage and safety accident and should be removed as soon as possible.

At present, Korea Electric Power Corporation has distributed TDAS since 1999, and has been expanded to offices nationwide.However, failure detection and removal of 6.6kV ungrounded distribution lines used in island areas in Korea are efficient. The situation was not operated.

Conventionally, the fault determination and removal of the ungrounded distribution line uses a method of determining a fault when the value exceeds a preset value by using the image current and the image voltage when a ground fault occurs. However, this method can only determine the presence of a failure, there is a problem that can not determine the failure.

In addition, since the switch is to send the fault information to the central control unit to remove the fault at the operator's discretion, there is a problem that takes a considerable time to remove the fault.

The present invention has been made to solve the above problems, to provide a power distribution protection coordination system and its operation method to accurately determine the failure section and fault when a ground fault occurs in the ungrounded distribution system.

In addition, the present invention provides a stable and effective protection coordination system by reducing the failure identification and failure removal time by effectively separating the failure interval through the protection coordination method of each opening and closing period based on the information on the failure interval and the fault phase It is to provide an operation method.

According to one aspect of the present invention, a power distribution protection coordination system is provided.

In the power distribution protection coordination system according to an embodiment of the present invention, when a ground fault occurs in an ungrounded distribution line, the occurrence of the fault and the fault phase are determined by using a phase difference between the image current and the phase voltage of the distribution line, and the fault occurs. A terminal device for generating and transmitting failure identification information including whether and failure information, a switchge that opens and closes the distribution line under control of the terminal device, and receives the failure recognition information from the terminal device, and receives at least one terminal device. It may include a power distribution protection cooperative system including a power distribution control device for transmitting a control signal for blocking the fault section by operating the switch at the point of failure through inter-cooperation.

According to another aspect of the present invention, a method of operating protection coordination in a distribution system is provided. The method of operating protection coordination in a distribution system according to an embodiment of the present invention provides an image of a ground fault occurring in an ungrounded distribution line. It may include a distribution protection cooperative operation method comprising the step of determining a fault phase by using the phase difference between the current and the phase voltage, and the fault blocking through the time cooperation of the switching period using the fault phase identification information.

The present invention is to determine the exact fault phase for the ground fault, which is the most fault occurring in the distribution line, and through this time coordination of the automatic switchgear period in order to eliminate the fault through smooth operation cooperation by operating only the potential switch at the fault point Can operate.

In addition, the present invention can determine the exact fault phase for the non-grounded distribution system to provide accurate fault information to the operator, it is possible to shorten the line instantaneous time for checking the fault point and eliminate the fault.

In addition, the present invention can achieve the efficient operation of the distribution line by performing the failure blocking operation using the time coordination of the existing automatic switching period by using the small fault current in the non-grounded distribution line.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

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

1 is a view for explaining the configuration of the power distribution protection cooperation system according to an embodiment of the present invention.

As shown in FIG. 1, the power distribution protection cooperative system includes a power distribution control device 100, a communication network 200, a terminal device 300, and an automated switch 400.

The distribution control apparatus 100 includes a distribution automation server 110 and a HMI (Human Machine Interface) device for operation and a front end processor (FEP) 130.

The distribution automation server 110 according to the present invention receives a failure recognition information 420 including a failure occurrence and a failure phase from the terminal device 300 when a ground fault occurs in an ungrounded distribution line, and the terminal device 300. ) Interrupt the fault section by operating only the switch on the potential side at the point of fault occurrence.

That is, the distribution automation server 110 receives the Fault Indicator (FI), which is information on the occurrence of the fault and the fault, when the fault phase is determined in the terminal device 300, and sets the cutoff time counter Td to 0. Shut off the fault section.

The distribution automation server 110 transmits a control signal for setting Td, which is a time difference with respect to the time until the switch 400 is opened to each terminal device 300 to block the fault current. Here, the setting of the Td_set of each terminal device 300 is set shorter as the load side.

In the HMI (Human Machine Interface) 120, the distribution system diagram 104 for the operating area is displayed.

The front end processor (FEP) 130 is connected to the automation switch 400, the substation CB (Circuit Breaker 310) and the automation terminal device (FRTU) 300 installed in the distribution line through a communication network.

The communication network 200 transmits a control command of the power distribution control device 100 to each terminal device 300 according to a communication method or sends information obtained from the terminal device to the power distribution control device 100.

The communication network 200 may use various communication methods such as optical communication, telephone line, wireless communication, voice communication, and the like.

Terminal unit (FRTU, Feeder Remote Terminal Unit, 300) is installed in a set with the distribution automation switch 400 installed in the middle of the distribution line to measure the current and voltage flowing through the switch 400 or to change the input / open state Detect.

The terminal device 300 determines whether a fault occurs and a fault phase by using an image current and a phase voltage, and generates fault recognition information (FI).

The terminal device 300 transmits the failure recognition information 420 to the distribution control apparatus 100 so that the same failure identification information 420 is displayed on the distribution control apparatus 100.

The terminal device 300 operates only the potential side switch 400 at the point of failure through the coordination between the terminal devices 300 of the switch 400 under the control of the distribution control device 100 to block the fault section. Ensure cooperation.

This will be described in more detail with reference to FIGS. 2 to 5.

When the failure occurs in the non-grounded distribution line, the switch 400 opens and closes the distribution line under the control of the terminal device 300 to block the failure section.

2 is a view for explaining the flow of fault current when a ground fault occurs in an ungrounded distribution line.

If a ground fault occurs in an ungrounded distribution line, there is no return conductor through which a fault current flows, and only a charging current flows due to the capacitance between the line and the ground.

And since the impedance of the line and the transformer is much smaller than this capacitance, it becomes negligible, and the ground fault current is almost determined by the capacitance component. Thus, the current is advanced almost 90 ° relative to the voltage at the point of failure.

FIG. 3 is a diagram for explaining phases of voltage and current in normal and ground fault in an ungrounded distribution line.

As shown in FIG. 3, in the normal vector diagram 301, each phase voltage is balanced by forming a 120 ° phase difference.

However, in the vector diagram 302 at the time of ground fault, phase A moves to the ground point in the case of complete phase A ground fault.

In addition, the voltage between each phase and the phase current form a 90 ° phase angle.

At this time, since 3Io = I _A + I _B + I _C , in the case of ground fault of phase A, the potential of phase _A drops to zero and I _A becomes zero.

In addition, since I _B and I _C flow only the charging current due to the charging capacitance between each conductor and the ground, the direction of 3Io forms a phase difference of 180 ° with V _BC as shown at 302.

Similarly, in the case of a phase B ground fault, 3Io has a phase difference of 180 ° with V _CA, and in the case of a phase C ground fault, 3Io has a phase difference of 180 ° with V _AB .

At this time, charge capacitance contributes the most to the fault current, but considering the effects of line impedance and fault resistance, the phase angle between 3Io and phase voltage in each fault is less than 180 ° and theoretically 90 ° ~ It has a range of 180 °.

4 is a view for explaining a failure determination region of the phase angle of Io with respect to the interphase voltage for each ground fault.

As shown in FIG. 4, the terminal device 300 has a phase A ground fault when Io is in the range of about 120 to 180 ° (theoretically, 90 ° to 180 °) with V _BC which is an interphase voltage with respect to the ground fault of the distribution line. Determine by failure.

Similarly, the terminal device 300 is Io is to determine the B-phase earth fault is in the phase-to-phase voltage, V _CA with approximately 120 ~ 180 ° range (which is theoretically 90 ° ~ 180 °), the Io the phase to phase voltage V _AB and If it is in the range of about 120 ~ 180 ° (in theory, it is 90 ° ~ 180 °), it is regarded as phase C ground fault. Here, when calculating the phase angle difference, the phase angle of Io is calculated counterclockwise based on the phase-to-phase voltage. In this way, it is possible to determine whether a fault occurs on the ground fault in the automated switch 400 and the terminal device 300 attached to the non-grounded distribution line and whether the fault occurs. ) Can be set.

In addition, in a non-grounded distribution line, when a one-line ground fault occurs, the magnitude of the fault current is not large compared to the normal load current, so that the fault current can be sufficiently blocked by the general automated switch 400.

Therefore, if the time difference for the time to open the switchgear in order to determine the failure between the terminal device 300 and cut off the fault current, it is possible to achieve the cooperation between the automatic switchgear terminal device 300 to block the failure section.

In this case, the shorter the time is, the shorter the disconnection time is from the substation to the load side, so that the fault can be interrupted first from the power switch closest to the point of failure.

For example, the interruption time may be set to 1 second from the most end switch, and the interruption time may be increased by 1 second to the power supply side.

If the fault is released before the interruption time set by the switch indicating the fault information, it is determined that the fault is removed from any switch on the load side and the fault is released.

5 is a view for explaining a distribution protection cooperative operation method in a terminal device according to an embodiment of the present invention.

As shown in FIG. 5, in step S100, the terminal device 300 first calculates an image current value 3Io as a vector sum of currents measured by each switch 400.

In step S200, the terminal device 300 calculates whether the image current value 3Io exceeds the preset image current setting value Ioset and determines whether there is a failure.

In step S300 to step S302, the terminal device 300 determines that a failure has occurred when the image current value 3Io exceeds a preset image current set value Ioset, and when the failure is determined, the image current and the phase voltage Calculate the phase angle difference of.

In step S310 to step S312, the terminal device 300 determines whether each phase calculated by calculating the phase difference between Io and each phase voltage is within a fault phase angle range. Here, the determined fault phase range may be changed depending on the system configuration, but set to about 120 ° ~ 180 °.

In step S320 to step S322, the terminal device 300 determines the failure phase.

In step S400, when the fault phase is determined, the terminal device 300 displays fault occurrence information about fault occurrence and fault information as FI (Fault Indication).

In step S500, the terminal device 300 transmits the FI information to the power distribution control device 100 and sets the cutoff time counter Td to zero.

In operation S600, the terminal device 300 determines whether the cutoff time counter Td is greater than a preset Td_set.

 As a result of the determination in step S800, when the Td is greater than the predetermined Td_set, the terminal device 300 is issued a control command to open the switch 400 to block the failure. Here, the predetermined Td_set is determined by the power distribution control device 100 that has received the FI information, and is received by each terminal device 100. Here, Td_set is set shorter as it goes to the load side from the power distribution station. For example, assuming that four switchboards are installed in an ungrounded distribution line, Td_set of the last terminal switch is set to 1 sec, and Td_set is set by adding 0.5 sec in the direction close to the power supply side. In other words, each switch is set to 1 sec, 1.5 sec, 2.0 sec, and 2.5 sec in order from the end side to the power side.

In step S700, if the Td is not greater than the preset Td_set, the terminal device 300 recalculates the video current 3Io and if the Td is smaller than the video current set value Ioset, the fault is removed from the load side, so the FI is released and the power distribution control device Send to 100 and end the process. The terminal device 300 recalculates the image current 3Io, and if it is not smaller than the set value Ioset, increases the Td and returns to the previous step S600.

The distribution protection coordination system and its operation method for ground fault in the ungrounded distribution line according to the present invention can be determined only by determining whether there is an existing failure in the country, or by finding a fault line in a foreign country and sequentially finding a fault section. Automatically identify the section and fault phase, and use it to divide the breaker break time of each distribution automation to separate the fault section through mutual cooperation, and through this, quick fault by fault discrimination and protection cooperation of ungrounded distribution line Eliminate stars and failures and achieve efficient track operation.

An embodiment of the present invention may include a computer readable medium including program instructions for performing various computer-implemented operations. The computer readable medium may include a program command, a local data file, a local data structure, etc. alone or in combination. The media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be understood that the invention may be varied and varied without departing from the scope of the invention.

1 is a view for explaining the configuration of the power distribution protection cooperation system according to an embodiment of the present invention.

2 is a view for explaining the flow of fault current when a ground fault occurs in an ungrounded distribution line.

3 is a diagram for explaining phases of voltage and current in normal and ground fault in an ungrounded distribution line;

4 is a view for explaining a failure determination region of the phase angle of Io with respect to the phase-to-phase voltage for each ground fault.

5 is a view for explaining a distribution protection cooperative operation method in a terminal device according to an embodiment of the present invention.

Claims (12)

In case of a ground fault in the ungrounded distribution line, the video current value of the distribution line is compared with the preset video current setting value, and it is determined whether or not a fault has occurred. A terminal device for determining a fault phase by determining whether it is included in a range of 120 ° to 180 °, and generating and transmitting fault identification information including information on whether the fault occurs and the fault condition; A switch to open and close the distribution line under control of the terminal device; And The distribution control device that receives the failure recognition information from the terminal device and transmits a control signal for blocking the failure section by operating the switch at the point of failure through cooperation between at least one terminal device to the at least one terminal device. Including but not limited to: The terminal apparatus sets a break time counter by setting a break time difference of the switchgear against a ground fault occurring in the ungrounded power distribution line from the power distribution control device, and the break time difference of the switch increases as the distance from the substation to the load side. Distribution protection cooperative operation system, characterized in that to set a short. The method of claim 1, The distribution control device And a front end processor connected to the switch and the terminal device corresponding to the switch and installed in the distribution line through a communication network. 3. The method of claim 2, The communication network is a distribution protection coordination system, characterized in that by at least one communication method of optical communication, telephone line, wireless communication and voice communication. delete delete delete In the distribution protection cooperative operating method in a distribution protection cooperative operation system including a terminal device, a switch and a distribution control device, If a ground fault occurs in the ungrounded distribution line in the terminal device, determining whether a failure occurs by comparing the image current value of the distribution line with a preset image current setting value; Determining that a fault phase is determined by determining whether a phase difference between each phase voltage and an image current falls within a range of 120 ° to 180 ° when the terminal device determines that a fault has occurred; Generating and transmitting failure identification information including information on whether the failure occurred and the failure phase in a terminal device; And Receiving the control signal for blocking the fault section by operating the switchgear at the point of failure from the distribution control device that has received the fault recognition information at the terminal device, the break time counter (Td_set) Including the steps to set up, The failure protection time difference of the switchgear distribution protection coordination operation method characterized in that the shorter the time set as the distance from the substation to the load side. delete delete delete delete In the recording medium recording a program for implementing the distribution protection cooperative operation method in a distribution protection cooperative operation system including a terminal device, a switchgear and a distribution control device, If a ground fault occurs in the ungrounded distribution line in the terminal device, determining whether a failure occurs by comparing the image current value of the distribution line with a preset image current setting value; Determining that a fault phase is determined by determining whether a phase difference between each phase voltage and an image current falls within a range of 120 ° to 180 ° when the terminal device determines that a fault has occurred; Generating and transmitting failure identification information including information on whether the failure occurred and the failure phase in a terminal device; And Receiving a control signal for blocking the failure section by operating the switch at the point of failure from the distribution control device that has received the failure recognition information in the terminal device, and setting the cut-off time counter by setting the break time difference of the switch Including but not limited to: The recording medium recording a program for implementing the power distribution protection cooperative operation method, characterized in that the breakdown time difference of the switch is set shorter as the distance from the substation to the load side.

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