KR101759890B1 - System and method for controlling load in power systema - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power system load control system, and more particularly, to a power system load control system and method capable of shutting off a power transmission line when a failure occurs in the power system by measuring a load of the power transmission line.
To this end, the power system load control system according to an embodiment of the present invention includes a current meter for measuring a current flowing through each of a plurality of transmission lines, a circuit breaker connected to each of the plurality of transmission lines, A cutoff control relay for receiving current information including respective load current values and selecting at least one power transmission line to be cut off among a plurality of power transmission lines using a predetermined cutoff load value and the current information; And a control unit connected to the at least one power transmission line connected to the at least one power transmission line through the cutoff line to measure a frequency of a voltage flowing in the power transformer for the instrument, determine whether the power system is faulty using the measured frequency information, A cut-off trip signal is transmitted through the cut-off line to the breaker, And a frequency relay for blocking the load current.

Description

TECHNICAL FIELD [0001] The present invention relates to a power system load control system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power system load control system, and more particularly, to a power system load control system and method capable of shutting off a power transmission line when a failure occurs in the power system by measuring a load of the power transmission line.

Power system refers to a system consisting of power generation and consumption by connecting a power station and a substation to a customer (that is, a power consuming entity) by a transmission line. The power system has to be constantly monitored because the demand and supply must be balanced by the homogeneity of power generation and consumption.

In the power system, abnormalities such as frequency, voltage, etc. occur due to the cause of the generator failure and the transmission line failure. In the case of power system failure, there is a shortage of power supply, and the collapse of power system is spreading, so that in the case of Korea, which has a radial structure, the whole area can be out of power. In addition, if the whole area is out of power, it takes a lot of time to recover the power system, resulting in social confusion.

If a fault occurs in the power system, it can not maintain the commercial frequency and falls to the low frequency. To prevent the collapse of the power system, measure the voltage frequency and if the voltage falls below a certain frequency, It is possible to prevent collapse.

However, the cut-off load previously planned for each substation is cut off by investigating the load of the line for a certain period of time, so that the cut-off load can be increased or decreased when the load of the line is changed.

If the cut-off load is large, abnormal cut-off occurs more than necessary, and if the cut-off load is small, it may cause the collapse of the power system due to a lack of the calculated cut-off load.

In addition, if the load line changes, the problem of manually changing the blocking line at the substation occurs.

The matters described in the background section are intended to enhance the understanding of the background of the invention and may include matters not previously known to those skilled in the art.

An embodiment of the present invention provides a power system load control system and method capable of shutting off a power transmission line when a failure occurs in a power system by measuring a load of the power transmission line.

The embodiments of the present invention provide a power system load control system and method capable of measuring a load of a line in real time to determine a breaking load.

According to an embodiment of the present invention, there is provided a current measuring apparatus comprising: a current meter for measuring a current flowing through each of a plurality of transmission lines; A breaker connected to each of the plurality of transmission lines; A current measuring unit for receiving current information including a load current value of each of the plurality of transmission lines from the current measuring unit and for selecting at least one transmission line to be disconnected from the plurality of transmission lines by using a predetermined blocking load value and the current information, relay; And a control unit connected to the circuit breaker through a plurality of cut-off lines, for measuring a frequency of a voltage flowing in the transformer for the instrument, determining whether the power system is faulty using the measured frequency information, And a frequency relay for transmitting a cut-off trip signal through the cut-off line to a circuit breaker connected to one power transmission line to cut off the load current of the power transmission line.

The power system load control system may further include a switch, which is located between the frequency relay and the breaker, and is connected in series with each of the plurality of cut-off lines.

In addition, the shutdown control relay may close a switch corresponding to at least one selected transmission line.

In addition, the frequency relay transmits a blocking trip signal to each of the plurality of blocking lines, and at least one blocking device selected by the blocking control relay can receive a blocking trip signal through the closed switch.

The cutoff control relay may use the current information to select the transmission line so that the cutoff load value is less than or equal to a calculated value of the load current value of at least one transmission line to select.

The calculation value may be a value obtained by adding the load current value of each of at least one transmission line to be selected.

The blocking control relay may select at least one transmission line among the plurality of transmission lines based on the line basic information for the plurality of transmission lines.

In addition, the frequency relay can determine that the power system is out of order if the frequency information is less than a set value.

In addition, the current measuring device can measure a current flowing in a current transformer connected in series to each of the plurality of power transmission lines.

According to another embodiment of the present invention, there is provided a method of controlling a load of a power system by a power system load control system, comprising: checking current information including a load current value measuring a current flowing through each of a plurality of power transmission lines; Selecting at least one transmission line of the plurality of transmission lines by using the current information and the blocking current value; Generating frequency information by measuring a voltage frequency flowing through the meter transformer; Determining whether the power system is faulty using the frequency information; And controlling a breaker connected to at least one transmission line selected when it is determined that there is a failure of the power system, thereby blocking a load current of the transmission line.

According to still another embodiment of the present invention, there is provided a method of measuring current flowing through a plurality of power transmission lines, The blocking control relay receiving the current information including the load current value for each of the plurality of transmission lines from the current meter; Selecting at least one transmission line among the plurality of transmission lines by using the current information and a predetermined blocking load value; Generating frequency information by measuring a voltage frequency of the frequency relay flowing through the meter transformer; Determining whether the frequency relay is faulty or not by determining whether frequency information is less than or equal to a preset value; And determining that the frequency relay is a failure of the power system when the frequency information is less than or equal to the set value, and controlling the breaker selected by the shutdown control relay to shut off the load current of the power transmission line can do.

The embodiment of the present invention can stabilize the power system and facilitate the management of the breaking load since the transmission line can be shut off when a failure occurs in the power system by measuring the load of the transmission line.

In addition, since the load of the line can be measured in real time to determine the blocking load, it is possible to prevent the problem of reducing the blocking load due to the load fluctuation of the line, thereby preventing collapse of the power system.

In addition, effects obtainable or predicted by the embodiments of the present invention will be directly or implicitly disclosed in the detailed description of the embodiments of the present invention. That is, various effects to be predicted according to the embodiment of the present invention will be disclosed in the detailed description to be described later.

1 is a simplified diagram of a power system load control system in accordance with an embodiment of the present invention.
2 is a configuration diagram of a power system load control system according to an embodiment of the present invention.
3 is a flowchart illustrating a power system load control method according to an embodiment of the present invention.
4 is an exemplary diagram for explaining a power system load control method according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an operation principle of an embodiment of a power system load control system and method according to the present invention will be described in detail with reference to the accompanying drawings and description. It should be understood, however, that the drawings and the following detailed description are exemplary and explanatory of various embodiments for effectively illustrating the features of the present invention. Therefore, the present invention should not be limited to the following drawings and descriptions.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The terms used below are defined in consideration of the functions of the present invention, which may vary depending on the user, intention or custom of the operator. Therefore, the definition should be based on the contents throughout the present invention.

In order to efficiently explain the essential technical features of the present invention, the following embodiments will appropriately modify, integrate, or separate terms to be understood by those skilled in the art to which the present invention belongs , And the present invention is by no means thereby limited.

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

1 is a simplified diagram of a power system load control system in accordance with an embodiment of the present invention.

Referring to FIG. 1, a power system load control system 200 includes a current meter 210, a shutdown control relay 230, a breaker 250, and a frequency relay 270.

The current meter 210 measures a current flowing through each of the plurality of transmission lines. The current measuring instrument 210 provides current information including the load current value for each of the plurality of measured transmission lines to the blocking control relay 230. [

The cutoff control relay 230 is electrically connected to the current meter 210 and receives current information from the current meter 210.

The blocking control relay 230 confirms the blocking load value. At this time, the cut-off load value indicates a load value to be cut off when a failure occurs in the power system, and may be different depending on the power system. The cutoff load value may be input from the user or may be provided from a management system that manages the power system.

The cutoff control relay 230 selects at least one transmission line among the plurality of transmission lines by using the current information and the load cutoff value.

The breaker 250 is connected to each of the plurality of transmission lines. The number of circuit breakers 250 may be the same as the number of transmission lines.

The frequency relay 270 generates frequency information by measuring a voltage frequency flowing in a potential transformer (PT). At this time, the instrument transformer may be a bus transformer.

The frequency relay 270 is electrically connected to the breaker 250 to control the breaker 250. That is, the frequency relay 270 determines the failure of the power system using the frequency information. When it is determined that the power system has failed, the frequency relay 270 controls the circuit breaker 250 to cut off the load current of the power transmission line.

The frequency relay 270 controls the breaker 250 connected to at least one power transmission line selected by the cutoff control relay 230 to cut off the load current of the power transmission line when the power system is determined to be faulty.

The frequency relay 270 may be a low frequency relay (UFR).

The power system load control system 200 described above will be described in more detail with reference to FIG.

2 is a configuration diagram of a power system load control system according to an embodiment of the present invention.

Referring to FIG. 2, the power system load control system 200 according to the embodiment of the present invention includes first to fourth blocking lines 131, 133, 135, 137, first to fourth switches 151, 153, 155 and 157, a current measuring device 210, a blocking control relay 230, first to fourth circuit breakers 251, 253, 255 and 257 and a frequency relay 270.

Each of the first to fourth blocking lines 131, 133, 135 and 137 is located between each of the first to fourth circuit breakers 251, 253, 255 and 257 and the frequency relay 270.

Each of the first to fourth switches 151, 153, 155 and 157 is connected to each of the first to fourth power transmission lines 111, 113, 115 and 117.

Each of the first to fourth switches 151, 153, 155 and 157 is located in the first to fourth blocking lines 131, 133, 135 and 137 and the first to fourth blocking lines 131, 133 and 135 And 137, respectively.

The current measuring unit 210 measures a current flowing through each of the first to fourth power transmission lines 111, 113, 115, and 117. That is, the current measuring device 210 includes first to fourth current transformers (CTs) 121, 123, 125, and 127 connected in series with the first to fourth transmission line 111, 113, 115, ) Is measured.

The current meter 210 generates current information including the load current values for the first to fourth power transmission lines 111, 113, 115, and 117, and provides the generated load current value to the shutdown control instrument.

The cutoff control relay 230 receives current information from the current meter 210.

The blocking control relay 230 selects at least one transmission line among the first to fourth transmission lines 111, 113, 115, and 117 using the load cutoff value and the current information.

In other words, the cutoff control relay 230 uses the current information so that the cut-off load value is less than or equal to the calculated value of the load current value of the at least one power transmission line to be selected. The first to fourth power transmission lines 111, 113, 115, 117 are selected.

The blocking control relay 230 closes a switch corresponding to the selected transmission line.

The shutdown control relay 230 may be implemented with one or more microprocessors operating with the set program, and the set program may be implemented as a series of steps for performing the steps included in the power system load control method according to an embodiment of the present invention Command may be included.

Each of the first to fourth circuit breakers 251, 253, 255 and 257 is connected to each of the first to fourth power transmission lines 111, 113, 115 and 117.

Each of the first to fourth circuit breakers 251, 253, 255 and 257 is connected to the frequency relay 270 through each of the first to fourth blocking lines 131, 133, 135 and 137.

The first to fourth circuit breakers 251, 253, 255 and 257 cut off the load currents of the first to fourth power transmission lines 111, 113, 115 and 117 under the control of the frequency relay 270.

The frequency relay 270 is connected to each of the first to fourth circuit breakers 251, 253, 255 and 257 through the first to fourth cut lines 131, 133, 135 and 137.

The frequency relay 270 measures frequency of a voltage flowing through the meter transformer 160 to generate frequency information.

The frequency relay 270 uses the frequency information to determine whether the power system is malfunctioning. The frequency relay 270 detects the failure of the power system through the first to fourth blocking lines 131, 133, 135 and 137 to the first to fourth circuit breakers 251, 253, 255 and 257, . At this time, the breaker selected by the break control relay 230 among the first to fourth breakers 251, 253, 255 and 257 receives the break trip signal through the closed switch under the control of the break control relay 230 . Here, the cut-off trip signal may be a trip signal generated to cut off the power transmission line.

The frequency relay 270 may be implemented by one or more microprocessors operating according to the set program, and the set program may include a series of commands for performing the steps included in the power system load control method according to an embodiment of the present invention, As shown in FIG.

Although the number of transmission lines is four in this example, the number of transmission lines is not limited to four, and the number of transmission lines is irrelevant if power can be transmitted to the customer.

Hereinafter, a method of controlling the load of the power system will be described with reference to FIGS. 3 and 4. FIG.

FIG. 3 is a flowchart illustrating a power system load control method according to an embodiment of the present invention, and FIG. 4 is an exemplary diagram illustrating a power system load control method according to an embodiment of the present invention.

Referring to FIG. 3, the current meter 210 measures currents of the first to fourth power transmission lines 111, 113, 115, and 117 (S310). In other words, the current meter 210 measures the current flowing in the first to fourth current transformers 121, 123, 125, and 127 connected to the first to fourth transmission line 111, 113, 115, do.

The current meter 210 generates current information using the measured current (S315). That is, the current measuring unit 210 generates current information including a load current value for each of the first to fourth power transmission lines 111, 113, 115, and 117

The current meter 210 transmits current information to the shutdown control relay 230 (S320).

The blocking control relay 230 confirms the blocking load value for the power system (S325). That is, the shutdown control relay 230 confirms the cutoff load value with respect to the load value to be cut off when a failure occurs in the power system, substation, etc. of the power system.

The cutoff control relay 230 selects at least one transmission line among the first to fourth transmission lines 111, 113, 115, and 117 (S330). In other words, the cutoff control relay 230 uses the current information to select the transmission line so that the cutoff load value is less than or equal to the calculated value for the load current value of at least one transmission line to select. At this time, the calculation value is a value obtained by adding the load current value of each of at least one transmission line to be selected.

The cutoff control relay 230 confirms line basic information for the first to fourth transmission lines 111, 113, 115, and 117. At this time, the line basic information may indicate a priority order of the first to fourth transmission lines 111, 113, 115, and 117 to be blocked. If the load current value of the transmission line is the same, the blocking control relay 230 can check the line basic information and select the transmission line having a higher priority.

On the other hand, if the line basic information includes the transmission line that should not be blocked, the cut-off control relay 230 excludes the transmission line which should not be blocked among the first to fourth transmission lines 111, 113, 115, Other transmission lines may be blocked.

The blocking control relay 230 controls a switch connected to the selected transmission line (S335). That is, the blocking control relay 230 closes the switch connected to the selected transmission line.

For example, if the cutoff load value is 400A, the load current value of the first transmission line 111 is 200A, the load current value of the second transmission line 113 is 150A, the load of the third transmission line 115 Assuming that the current value is 100A, the load current value of the fourth transmission line 117 is 100A, and the priority of the fourth transmission line among the third transmission line and the fourth transmission line is high, the blocking control relay 230 Is connected to the first power transmission line 111, the second power transmission line 113 and the third power transmission line 115 so that the cut-off load among the first to fourth power transmission lines 111, 113, 115, Or the first transmission line 111, the second transmission line 113 and the fourth transmission line 117 can be selected.

The cutoff control relay 230 confirms the line basic information because the load current values of the third transmission line 115 and the fourth transmission line 117 are the same. The blocking control relay 230 can select the fourth transmission line 117 among the third transmission line 115 and the fourth transmission line 117 by confirming the line basic information.

The blocking control relay 230 includes a first switch 151 connected to the selected first transmission line 111 as shown in FIG. 4, a second switch 153 connected to the second transmission line 113, The fourth switch 157 connected to the line 117 can be closed.

The frequency relay 270 measures the voltage frequency flowing through the meter transformer 160 to generate frequency information (S340 and S345).

The frequency relay 270 determines whether the frequency information is less than a set value and determines whether the power system is malfunctioning (S350). Here, the set value is a value set to determine whether a failure has occurred in the power system, and may be a preset value. The set value may be set by the user or set by a predetermined algorithm (e.g., a program and a probability model).

On the other hand, if the frequency information exceeds the set value, the frequency relay 270 returns to step S340 and measures the voltage frequency of the transformer 160 for the instrument.

If the frequency information is less than the preset value, the frequency relay 270 determines that the power system is out of order, and transmits the interruption trip signal to the breaker (S355). In other words, when it is determined that the power system has failed, the frequency relay 270 transmits a shutoff trip signal to the first to fourth circuit breakers 251, 253, 255, and 257 through the first to fourth cutoff circuits. At this time, a breaker of the first to fourth breakers 251, 253, 255, 257 connected to the closed switch receives the break trip signal from the frequency relay 270. And the breaker connected to the open switch does not receive the break trip signal.

For example, as shown in FIG. 4, the frequency relay 270 transmits a trip trip signal to the first to fourth breakers 251, 253, 255, and 257, but is connected to the closed first switch 151 Only the first breaker 251, the second breaker 253 connected to the closed second switch 153 and the fourth breaker 257 connected to the closed fourth switch 157 receive the break trip signal. The third breaker 255 does not receive the break trip signal by the third switch 155 that is opened.

The breaker receives the cut-off trip signal and cuts off the load current of the power transmission line (S360). 4, each of the first circuit breaker 251, the second circuit breaker 253 and the fourth circuit breaker 257 includes a first transmission line 111, a second transmission line 113, 4 transmission line 117 is cut off.

Accordingly, as described above, the power system load control system 200 according to the present invention periodically measures the load current of the transmission line, selects the transmission line corresponding to the cut-off load value, It can be prevented that the power system is collapsed and the power system can be stabilized because the load current of the selected transmission line is blocked because it is judged that the power system has failed.

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.

111, 113, 115, 117: transmission line
121, 123, 125, 127: Current transformers
131, 133, 135, 137:
151, 153, 155, 157: switches
160: Instrument transformer
200: Power system load control system
210: Current meter
230: Blocking control relay
251, 253, 255, 257:
270: Frequency Relay

Claims (19)

A current measuring unit for measuring a current flowing through each of the plurality of transmission lines;
A breaker connected to each of the plurality of transmission lines;
A current measuring unit for receiving current information including a load current value of each of the plurality of transmission lines from the current measuring unit and for selecting at least one transmission line to be disconnected from the plurality of transmission lines by using a predetermined blocking load value and the current information, relay; And
And a control unit connected to the circuit breaker through a plurality of cut-off lines to measure a frequency of a voltage flowing in the transformer for the instrument, determine whether the power system is faulty using the measured frequency information, And a frequency relay for transmitting a cutoff signal through the cutoff line to cut off the load current of the power transmission line,
Wherein the shutdown control relay closes a switch corresponding to the selected at least one transmission line and the frequency relay transmits a shutdown trip signal to each of the plurality of shutdown lines, Wherein the circuit breaker receives the shutdown trip signal via the closed switch. The method according to claim 1,
Further comprising a switch located between the frequency relay and the breaker and connected in series with each of the plurality of shielding lines. delete delete The method according to claim 1,
The blocking control relay
And selects the power transmission line so that the cut-off load value is equal to or less than a calculated value of the load current value of at least one power transmission line using the current information. 6. The method of claim 5,
The calculated value is
And the load current value of each of the at least one power transmission line to be selected is added. The method according to claim 1,
The blocking control relay
And selects at least one transmission line of the plurality of transmission lines based on the line basic information for the plurality of transmission lines. The method according to claim 1,
The frequency relay
And determines that the power system is in failure if the frequency information is less than a set value. The method according to claim 1,
The current meter
And measures a current flowing in a current transformer connected in series to each of the plurality of power transmission lines. CLAIMS 1. A power system load control system for controlling a load of a power system,
Checking current information including a load current value measuring a current flowing through each of the plurality of transmission lines;
Selecting at least one transmission line of the plurality of transmission lines by using the current information and the blocking current value;
Generating frequency information by measuring a voltage frequency flowing through the meter transformer;
Determining whether the power system is faulty using the frequency information; And
And controlling a breaker connected to at least one transmission line selected when it is determined that there is a failure of the power system, thereby blocking a load current of the transmission line,
Wherein the step of selecting the at least one transmission line includes closing a switch connected to the selected at least one transmission line,
Wherein the step of interrupting the load current of the power transmission line includes the steps of transmitting a shutdown trip signal to a circuit breaker connected to each of the plurality of power transmission lines and transmitting a shutdown trip signal through a closed switch to a circuit breaker connected to at least one selected transmission line The power system load control method comprising: 11. The method of claim 10,
The step of selecting the at least one transmission line
And selecting the transmission line so that the cut-off load value is equal to or less than a calculated value of the load current value of at least one transmission line to be selected using the current information. 12. The method of claim 11,
The step of selecting the at least one transmission line
Further comprising the step of adding the load current values of at least one transmission line to be selected to generate a calculation value. 11. The method of claim 10,
The step of selecting the at least one transmission line
Confirming line basic information for each of a plurality of transmission lines; And
Selecting at least one transmission line among the plurality of transmission lines based on the line basic information;
Wherein said power system load control method comprises: delete delete 11. The method of claim 10,
The step of determining whether the power system is faulty using the frequency information
And determining whether the power system is faulty by determining whether the frequency information is less than a set value. Measuring a current flowing through the plurality of power transmission lines through the current measuring instrument;
The blocking control relay receiving the current information including the load current value for each of the plurality of transmission lines from the current meter;
Selecting at least one transmission line among the plurality of transmission lines by using the current information and a predetermined blocking load value;
Generating frequency information by measuring a voltage frequency of the frequency relay flowing through the meter transformer;
Determining whether the frequency relay is faulty or not by determining whether frequency information is less than or equal to a preset value; And
Determining that the power system is out of order when the frequency information is lower than the set value and blocking the load current of the transmission line by controlling the circuit breaker selected by the shutdown control relay,
Wherein the step of selecting the at least one transmission line includes closing a switch connected to the selected at least one transmission line,
Wherein the step of interrupting the load current of the transmission line includes the steps of the frequency relay transmitting a shutoff trip signal to a circuit breaker connected to each of the plurality of transmission lines and a circuit breaker connected to the closed switch receiving the shutoff trip signal, And shutting off the load current.

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