KR20140099382A - Apparatus for controlling power breaker having finrush current limiting function - Google Patents

Abstract

An apparatus for controlling a power breaker is disclosed. The apparatus for controlling a power breaker comprises a current signal matching unit which receives and matches a current signal of a power system; a voltage signal matching unit which receives and matches a voltage signal of the power system; a zero-cross conversion unit which receives the voltage signal and converts the voltage signal to a zero-crossing output signal corresponding to a zero point of the voltage signal; and a control unit which outputs a breaker control signal for controlling the breaker according to a first operation mode, analyzes the current signal, the voltage signal, or the zero-crossing output signal, and measures and stores an input delay time necessary to change a connection state of the breaker, and outputs the breaker control signal by reflecting a preset input phase angle of the breaker and the input delay time according to a second operation mode. The control unit compares the number of times of storage of the measured input delay time with a preset reference number of times. The control unit operates in the first operation mode when the number of times is less than the reference number or times, and operates in the second operation mode when the number of times exceeds the reference number of times by comparing the measured number of storing time of the input delay time with reference time. The control unit generates an input control signal of the breaker control signal which controls the input of the breaker according to a change in a clock edge of the zero-crossing output signal.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a power cut-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power breaker control apparatus having a function of controlling an input phase angle in order to minimize the occurrence of an inrush current.

A switchboard is installed on the path that supplies power from the power system to the consumer. The breaker control in the switchboard for instantaneous power supply is instantaneously operated by the operation of the switch or the contact output of the protection relay or the control controller. The phase angle of the power source is randomly generated when the breaker is turned on and a very large inrush current and arc are occasionally generated due to the random input phase angle.

This inrush current can be generated when power is supplied to the transformer in a no-load state due to the input of the breaker. Alternatively, an inrush current may be generated when a capacitor bank is provided to improve the power factor of the lower stage and power is supplied while the capacitor bank is discharged.

The inrush current can shorten the lifespan of the electric power facilities and induce arc generation with the risk of fire occurrence. Therefore, although the countermeasures against the inrush current are required, the power facilities are often operated in a defenseless manner, causing damage to the power facilities frequently.

Korean Patent No. 10-1205354

An object of the present invention is to provide a circuit breaker control apparatus and method which can suppress the occurrence of an inrush current and minimize a surge voltage by controlling an input phase angle at the time of inputting a breaker.

A power breaker control apparatus according to an embodiment of the present invention includes a current signal matching unit for receiving and matching a current signal of a power system; A voltage signal matching unit for receiving and matching a voltage signal of a power system; A zero crossing unit for receiving the voltage signal and converting the voltage signal into a zero crossing output signal corresponding to a zero point of the voltage signal; And outputting a breaker control signal for controlling the breaker according to the first operation mode, and analyzing the current signal, the voltage signal, or the zero crossing output signal to measure an input delay time required for changing the connection state of the breaker And a controller for outputting the breaker control signal in response to the input phase angle of the breaker and the closing delay time set in advance according to the second operation mode.

According to an embodiment of the present invention, a breaker control output unit receives a breaker control signal from the control unit and outputs the breaker control signal to the breaker; And a breaker state input unit for receiving the contact connection state of the breaker and transmitting the received state to the control unit.

According to an embodiment of the present invention, an analog / digital (A / D) conversion unit for converting the current signal and the voltage signal matched by the current signal matching unit and the voltage signal matching unit into digital data is further included can do.

According to an embodiment of the present invention, the nonvolatile memory may further include a storage unit for storing the insertion delay time.

According to an embodiment of the present invention, the communication unit may further include a communication unit for transmitting an operation state under the control of the control unit to the outside or transmitting a user's operation instruction to the control unit.

According to an embodiment of the present invention, the control unit may control the closing phase angle at a voltage phase angle of 90 ° or a current phase angle of 0 °.

According to an embodiment of the present invention, the control unit compares the measured number of times of storing the input delay time with a preset reference number, operates in the first operation mode when the reference number is not reached, And can operate in the second operating mode.

According to an embodiment of the present invention, the control unit may generate the closing control signal for controlling the closing of the circuit breaker in accordance with a clock edge change of the zero crossing output signal.

The power breaker control apparatus according to an embodiment of the present invention can suppress the generation of the inrush current and minimize the surge voltage by controlling the closing phase angle when the breaker is turned on.

1 is a block diagram illustrating a configuration of a power breaker control apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating an input delay time measurement of a guard gate according to an exemplary embodiment of the present invention. Referring to FIG.
3 is a simulation circuit diagram comprising a capacitor load circuit.
Figs. 4 to 8 are diagrams showing the result of time-difference injection simulation for each voltage phase angle set in the capacitor load circuit.
9 is a simulation circuit diagram comprising a transformer no-load circuit.
10 to 14 are diagrams showing the result of time difference injection simulation for each voltage phase angle set in the transformer no-load circuit.
15 is a simulation circuit diagram for testing a single-phase short circuit.
Each of Figs. 16 to 20 is a diagram showing voltage and current waveforms for each phase angle set in the single-phase simulation circuit.

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. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present invention, the term "comprises" or "having ", etc. is intended to specify that there is a feature, number, step, operation, element, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, a power breaker control apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a block diagram illustrating a configuration of a power breaker control apparatus according to an embodiment of the present invention.

Referring to FIG. 1, a power breaker control apparatus 100 according to an embodiment of the present invention controls a breaker 70 to transmit or cut off power supplied from a power terminal to a lower terminal in a three-phase power system. In addition, the power breaker control apparatus 100 according to an embodiment of the present invention detects a system fault such as a short circuit or a ground fault at the lower end and opens the breaker 70 to isolate the fault system to protect the entire power system Can play a role.

The power breaker control apparatus 100 according to an embodiment of the present invention includes a current signal matching unit 110, a voltage signal matching unit 120, an A / D converting unit 130, a zero crossing converting unit 140, A control unit 150, a breaker state input unit 160, a breaker control output unit 170, a storage unit 180, and a communication unit 190.

The current signal matching unit 110 receives a current signal from the three-phase current transformer 30 provided in the power system. The current signal matching unit 110 can convert a large current signal received from the three-phase current transformer 30 into a small signal capable of digital processing. For example, the current signal matching unit 110 can convert a voltage signal of a level suitable for processing by the controller 150 in proportion to the magnitude of the current input from the three-phase current transformer 30 and output it.

The voltage signal matching unit 120 receives the voltage signal from the three-phase voltage transformer 50 provided in the power system. The voltage signal matching unit 120 may convert a large voltage signal input from the three-phase voltage transformer 50 into a small signal capable of digital processing. For example, the voltage signal matching unit 120 may convert a voltage signal of a level suitable for processing by the controller 150 in proportion to the magnitude of the voltage input from the three-phase voltage transformer 50, and output the voltage signal.

The A / D conversion unit 130 receives the signal converted from the small signal from the current signal matching unit 110 or the voltage signal matching unit 120, and converts the signal into a digital value.

The zero cross conversion unit 140 receives the voltage signal converted into the small signal from the voltage signal matching unit 120 and outputs the voltage signal as a zero crossing output signal so that the zero cross of the voltage signal can be known Conversion.

The control unit 150 receives a voltage signal or a current signal converted into a digital signal. Also, the controller 150 measures an input voltage signal or a current signal to detect an abnormality in the power system. Also, the control unit 150 generates a breaker control signal in accordance with the abnormality of the power system. For example, the control unit 150 measures a voltage signal or a current signal to determine whether an accident such as a short circuit or a ground fault has occurred in a power system at a lower stage and, if an occurrence of an accident is detected, A control signal can be generated.

In addition, the controller 150 controls the closing phase angle of the circuit breaker so that the current phase angle is set to 0 ° in order to suppress the generation of the rush current when the circuit breaker is charged in the no-load state. The inrush current is suppressed when the voltage phase angle is a peak, that is, when the current phase angle is 90 °. Since the current and voltage have a phase difference of about 90 °, when the current phase angle is 0 ° The occurrence can be suppressed.

The controller 150 receives the zero crossing output signal and can generate a breaker control signal for changing the state of the breaker 70 according to the zero crossing signal. As shown in FIG. 2, the zero-crossing output signal generates an edge change when the phase angle of the voltage signal is 0 °. In response to the edge change of the zero-crossing output signal, the control unit 150 outputs the closing control signal included in the breaker control signal to the breaker 70 so as to apply the breaker 70. The control unit 150 may extract a waveform of the current signal and the voltage signal received from the current signal matching unit 110 and the voltage signal matching unit 120, respectively, and analyze the signals. At this time, the control unit 150 can analyze the waveforms extracted when the circuit breaker 70 is turned on, and detect that the voltage signal changes at the moment when the circuit breaker 70 is turned on. Further, the control unit 150 can detect that the current signal changes at the moment when the breaker 70 is turned on. The zero crossing output signal changes clock edge to the zero point of the voltage signal.

In this case, when the change of the voltage signal at the clock edge change of the zero crossing output signal is compared, the waveform of the voltage signal changes at the time when the contact state of the breaker changes after the clock edge of the zero crossing output signal is changed. That is, the closing control signal of the breaker control signal is outputted, so that the delay time up to the main contact closing completion time of the breaker 70 can be known. This indicates that the breaker control signal outputted from the control unit 150 is transmitted to the breaker control output unit 170 and a certain time is required from the breaker control output unit 170 to the power supply to the breaker 70. [ A predetermined closing delay time Ton is required until the main contact point of the circuit breaker 70 is turned on by the breaker control signal outputted from the control unit 150. [ For example, when the breaker control signal is transmitted to the auxiliary relay of the breaker control output unit 170 and the auxiliary relay operates, power is supplied to the solenoid in the breaker 70 so that the breaker is operated to turn on the main contact Can be made.

This input delay time Ton must be considered in advance when the controller 150 outputs the breaker control signal to suppress the inrush current. Since the time delay occurs in this series of processes, in order to measure the time delay, in the no-load operation test step in which the power breaker control apparatus 100 according to the embodiment of the present invention is installed for the first time, Can be performed. The current signal or the voltage signal generated in accordance with the input of the breaker 70 can be sampled by the A / D converter 130. At this time, the resolution of the A / D converter 130 may be higher than that of the normal operation in order to more precisely detect the injection delay time Ton.

The control unit 150 analyzes the waveform of the current signal or the voltage signal collected after the closing operation of the breaker is completed, and calculates the closing delay time Ton from the output of the breaker control signal to the turning on of the main point of the circuit breaker 70, May be measured and stored in the storage unit 180.

In this case, the measurement of the input delay time (Ton) can be performed by both a visual measurement method of the user and an automatic detection method using a waveform change in the current signal and the voltage signal.

The control unit 150 may be a time delay measurement mode for measuring the closing delay time Ton in a state where the power breaker control apparatus 100 according to an embodiment of the present invention is installed in the initial power system, It can operate in the normal operation mode.

The control unit 150 compares the stored number of times of the measured input delay time Ton with a preset reference number and operates in a first operation mode when the reference number is not reached and in a second operation mode when the reference number is exceeded . The controller 150 determines whether the measured value of the input delay time Ton is stored in the storage unit 180 for a predetermined number of times, and if the measured value is insufficient, the controller 150 may operate in the time delay measurement mode. The controller 150 may operate in the time delay measurement mode and measure the injection delay time Ton. For example, the control unit 150 determines whether about three times of the input delay time (Ton) measurement value is stored in the storage unit 180. If the stored number of times is less than the stored number, the control unit 150 operates in the time delay measurement mode, Can be measured.

In addition, the controller 150 determines whether the measured value of the injection delay time Ton is stored in the storage unit 180 for a predetermined number of times, and if the measured value is satisfied, the controller 150 can operate in the normal operation mode.

The controller 150 sets [N / (2 * Herze) - Ton> 0 (N = integer)] so that the circuit breaker 70 is charged at 0 °, 90 ° or a voltage phase angle of an electric angle desired by the user in the normal operation mode. [s] is used to obtain the minimum value Nmin of N. [ Next, the control unit 150 outputs a breaker control signal after a time delay of [Nmin / (2 * Herze) - Ton (N = integer)] [s] after passing the voltage phase angle of zero degree which is zero cross of the voltage signal can do.

Alternatively, the controller 150 may control the N [(2 * Herze) - Ton> 0 (N = integer)] [s] so that the circuit breaker 70 is turned on at a voltage phase angle of 90 [ Is obtained. Next, the control unit 150 passes the voltage phase angle of zero degree which is the zero cross of the voltage signal, and then, after a time delay of [Nmin / (2 * Herze) + 4 / Herze- Ton (N = integer)] [s] A control signal can be output.

In summary, in order to suppress the inrush current when the power source is no-load-applied, the controller 150 can turn on the circuit breaker 70 at the voltage phase angle of 90 degrees. Alternatively, in order to prevent an inrush current caused by a capacitor for the purpose of power factor correction or the like, the controller 150 may turn on the circuit breaker 70 at the voltage phase angle of 0 °.

Referring back to FIG. 1, the breaker state input unit 160 inputs the breaker state to the controller 150 so that the breaker can be informed of the on or off state of the breaker.

The breaker control output 170 is directly connected to the breaker 70 and operates a mechanism for closing and opening the breaker 70 according to the breaker control signal output from the controller 150.

The storage unit 180 extracts and analyzes the operation program of the control unit 150 and the waveforms of the current signal and the voltage signal to determine the delay time of the voltage, the maximum value and the minimum value of the voltage, the delay time of the current, And a minimum value. Also, the storage unit 180 may store the injection delay time Ton measured by the controller 150. The storage unit 180 may include a non-volatile memory and a data memory. The storage unit 180 may store the injection delay time Ton in the nonvolatile memory.

The control unit 150 may calculate the accurate closing time point of the circuit breaker 70 by reflecting the desired closing phase angle and the closing delay time Ton stored in the storage unit 180 and apply the calculated closing time point to generate the breaker control signal have.

The communication unit 190 may communicate with an external device to transmit an operation state under the control of the control unit 150 to the outside or may transmit a user's operation command to the control unit 150.

Hereinafter, with reference to FIG. 3 to FIG. 14, a description will be given of a simulation result showing a time difference inputting result of the circuit breaker when the load at the lower end is a capacitor load and when the load is a load without a transformer.

3 is a simulation circuit diagram comprising a capacitor load circuit.

Figs. 4 to 8 are diagrams showing the result of time-difference injection simulation for each voltage phase angle set in the capacitor load circuit.

Figs. 4 to 8 show simulation results under simulation conditions in which the voltage is 25.8 kV, the current is 20 A, the short-circuit current is 3.86 kA, the voltage variation rate is 0.5%, and the frequency is 60 Hz.

In FIGS. 4 to 8, when Vad is set to the peak reference phase and the A phase and the B phase are simultaneously charged and the C phase is applied after 2 ms has elapsed, the input phase angle is set to 0 °, 30 °, 60 °, 90 ° And 120 [deg.], Respectively.

In FIG. 4, the initial voltages (kV) Vad, Vbd and Vcd are 0 kV, 18.3 kV and 10 kV, respectively, and peak currents Ap, Ib and Ic are -106 Ap, -54 Ap is shown.

5, the peak voltages Ap, Ia, Ib, and Ic are -59 Ap and +0.5 V, respectively, when the initial phase angle (kV) Vad, Vbd and Vcd is 10.5 kV, 21.1 kV, 96Ap, and -152Ap, respectively.

In FIG. 6, the initial voltages (kV) Vad, Vbd and Vcd are 18.3 kV, 18.3 kV and 21.1 kV, respectively, and peak currents Ap, Ib and Ic are -190 Ap and + 190Ap, and -161Ap, respectively.

7 shows that the peak voltages Ap, Ib and Ic are respectively -157 Ap and +157 Ap when the initial phase angle (kV) Vad, Vbd and Vcd is 21.1 kV, 10.5 kV and 30.0 kV, respectively, 157Ap, and + 215Ap, respectively.

8A and 8B, the initial voltages (kV) Vad, Vbd and Vcd are 18.3 kV, 0 kV and 30.9 kV, respectively, and peak currents Ap, Ib and Ic are -86 Ap and -126 Ap , + 212 Ap, respectively.

4 to 8, when the inrush current is minimum in the capacitor load circuit, the voltage phase angle at the closing time of the breaker is 0 °.

9 is a simulation circuit diagram comprising a transformer no-load circuit.

10 to 14 are diagrams showing the result of time difference injection simulation for each voltage phase angle set in the transformer no-load circuit.

Figs. 10 to 14 show simulation results under simulation conditions in which the voltage is 25.8 kV, the current is 480 A, and the frequency is 60 Hz.

10 to 14, when the Vad is set to the peak reference phase and the C phase is applied after the lapse of 2 ms after the A phase and the B phase are simultaneously supplied, the phase angle of input is 0 degree, 30 degrees, 60 degrees, 90 degrees And 120 [deg.].

10, the initial voltages (kV) Vad, Vbd and Vcd are 0 kV, 18.3 kV and 10 kV, respectively, and the peak currents Ap, Ib and Ic are -1.52 kAp and +0.87 kV, respectively, kAp, and + 1.33kAp, respectively.

11, the initial voltages (kV) Vad, Vbd, and Vcd are 10.5 kV, 21.1 kV, and 6.4 kV, respectively, and the peak currents Ap, Ib, and Ic are -1.31 kAp, -0.72 kAp, and + 1.35 kAp, respectively.

12 shows that the initial voltages (kV) Vad, Vbd and Vcd are 18.3 kV, 18.3 kV and 21.1 kV, respectively, and peak currents Ap, Ib and Ic are -0.94 kAp, -0.94 kAp, and + 1.19 kAp, respectively.

13, the initial voltages (kV) Vad, Vbd, and Vcd are 21.1 kV, 10.5 kV, and 30.0 kV, respectively, and the peak currents Ap, Ib, Ic are +0.87 kAp, -1.09 kAp, and +0.90 kAp, respectively.

14, when the closing phase angle is 120 °, the initial voltages (kV) Vad, Vbd and Vcd are 18.3 kV, 0 kV and 30.9 kV, respectively, and peak currents Ap, Ib and Ic are + 1.26 kAp, 1.13 kAp, and -0.82 kAp, respectively.

10 to 14, when the inrush current is minimum in the transformer no-load circuit, the voltage phase angle at the closing time of the breaker is 90 °.

15 is a simulation circuit diagram for testing a single-phase short circuit.

Each of Figs. 16 to 20 is a diagram showing voltage and current waveforms for each phase angle set in the single-phase simulation circuit.

Figs. 16 to 20 show simulation results in a simulation condition in which the frequency is 60 Hz, the voltage is 18 kV, the total reactance (L) is 10 MHz, and the total resistance (R) is 20 M ?.

Each of Figs. 16 to 20 shows simulation results of current waveforms with input phase angles of 60 deg., 90 deg., 120 deg., 150 deg., And 180 deg. For single phase shorting.

In each of Figs. 16 to 20, the upper graph shows the voltage waveform and the lower graph shows the current waveform.

Closing angle Current peak (kA) Current RMS value (kA) 0 ° 9.43 3.36 30 ° 8.72 3.36 60 ° 7.09 3.36 90 ° 4.75 3.36 120 ° 7.12 3.36 150 ° 8.89 3.36 180 ° 9.43 3.36

Table 1 shows the current rms value detected by the set input phase angle and the current peak value according to the input phase angle.

FIG. 17 shows that the peak-to-zero is smallest in the acceptance criterion when a current is applied at an input phase angle of 90 °.

After the assembling and installation of the switchboard, the controller 150 operates the time delay measurement mode and the normal operation mode to measure the closing delay time Ton and applies the measured closing delay time Ton to the circuit breaker 70, It is possible to determine the closing delay time Ton by repeating the process of confirming the blocking time of the closing delay time Ton by a plurality of times. Also, the controller 150 may detect the closing delay time Ton stored in the storage unit 180 and reflect the detected closing delay time Ton in the breaker control signal.

The power breaker control apparatus according to an embodiment of the present invention can suppress the generation of the inrush current and minimize the surge voltage by controlling the closing phase angle when the breaker is turned on.

Also, the power breaker control apparatus according to an embodiment of the present invention may be installed in a protection relay to control the breaker. Therefore, the power breaker control apparatus according to an embodiment of the present invention can be installed in a protection relay having no closing phase angle control function to control the closing phase angle when the breaker is turned on.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention.

Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments.

The scope of protection of the present invention should be construed according to the following claims, and all technical ideas falling within the scope of the same shall be construed as falling within the scope of the present invention.

Claims (3)

CLAIMS 1. A power breaker control apparatus for controlling a breaker which connects a power source terminal and a negative terminal of a power system,
A current signal matching unit for receiving and matching a current signal of a power system;
A voltage signal matching unit for receiving and matching a voltage signal of a power system;
A zero crossing unit for receiving the voltage signal and converting the voltage signal into a zero crossing output signal corresponding to a zero point of the voltage signal; And
A breaker control signal for controlling the breaker is output in accordance with a first operation mode, and then the current signal, the voltage signal, or the zero crossing output signal is analyzed to measure an input delay time required for changing the connection state of the breaker And a controller for outputting the breaker control signal in response to the input phase angle of the breaker and the closing delay time set in advance according to the second operation mode,
Wherein the controller operates the first operation mode when the measured number of times of storing the input delay time is less than the reference number and the second operation mode when the reference time count is exceeded, And generates an input control signal of the breaker control signal for controlling the input of the breaker in accordance with a clock edge change of a zero crossing output signal.
The method according to claim 1,
And a storage unit for storing the closing delay time in the nonvolatile memory.
The method according to claim 1,
Wherein the control unit controls the closing phase angle in the range of 0 to 360 degrees.

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