JP3227653B2 - Power system protection controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power system protection control device for suppressing an overvoltage when a circuit breaker of a power system is cut off.

[0002]

2. Description of the Related Art Conventionally, when an accidental current in a transmission line is turned on and off by a power circuit breaker, an overvoltage is generated, and a device for suppressing the overvoltage to protect and control the power system has been used.

[0003] The overvoltage generated during the operation of the circuit breaker includes an input surge in which the charging voltage of the transmission line becomes a traveling wave when the power supply is turned on and is reflected back and forth to form an overvoltage, and a voltage drop of the transmission line when the system ground fault is interrupted. However, there is also a shut-off surge which becomes a traveling wave and is reflected back and forth and becomes an overvoltage.

[0004] These overvoltages can be as high as three times the phase voltage at high levels. Conventionally, for this overvoltage, while using a resistance closing circuit breaker and a resistance breaking circuit breaker,
Designs have been made to ensure that the insulation level of the transmission line is sufficiently resistant to such overvoltages.

[0005] In recent years, a 1000 kV transmission system has been planned in order to increase the transmission capacity in response to an increase in power demand. With such an ultra-high-voltage transmission line, it is not economically advantageous to construct a transmission line that is insulated and designed to sufficiently withstand the conventional overvoltage during circuit breaker operation.

For example, in a 1000 kV power transmission system, it is required to suppress an overvoltage to 1.6 times or less of a system phase voltage peak value. At present, for a closing surge, a resistance closing circuit breaker that absorbs traveling wave energy with a resistor is used in a power transmission system having a lower voltage. However, this method has no effect on breaking surge. Therefore, there has been proposed a resistance cutoff circuit breaker that cuts off via a resistor.

[0007]

However, in the puffer-type gas circuit breaker which is mainly used today, when an accident is cut off, the time for energizing the resistor is as long as about 30 ms, and the voltage responsibility of the circuit breaker is two times.
In order to withstand the duty of step-out and shut-off, which is doubled, the resistor becomes extremely large, and a complicated delay operation mechanism is required to drive the resistance-turning mechanism and the resistance cut-off mechanism.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power system protection and control device in which an overvoltage suppression device is turned on to suppress a transmission line overvoltage that occurs when a circuit breaker is opened, such as when a ground fault occurs in a three-phase transmission line. It is.

[0009]

In order to achieve the above-mentioned object, in order to achieve the above object, power system protection for a power system consisting of a bus connected to a power supply and a plurality of three-phase transmission lines drawn from the bus via a circuit breaker. In the control device, an overvoltage suppression device in which switching means and impedance provided in series between at least one of the bus or each of the three-phase transmission lines and the ground are connected in series, and the current and voltage of the transmission line An accident detecting means for detecting an accident of the three-phase transmission line, and the opening / closing means other than the one installed on the accidental transmission line is closed by the accident detection output of the accident detection means, and after the closing operation, And a control means for opening the circuit breaker and opening the switching means according to the output of the accident detection means for eliminating the accident.

The circuit breaker of the faulty transmission line is opened according to the fault detection output of the fault detection means, and the switching means other than those installed on the faulty transmission line are closed before the current cutoff of the breaker is completed. Control means for opening the opening / closing means based on the output of the accident detection means for eliminating the accident may be used.

Alternatively, a transient recovery voltage detecting means for opening the circuit breaker of the faulty transmission line based on the output of the fault detection of the fault detecting means and detecting a rise of a transient recovery voltage immediately after the breakage, and the transient recovery voltage detecting means The detection means may be a control means for closing the opening / closing means other than the one installed on the accident power transmission line, and for opening the opening / closing means in response to the output of the accident detection means for removing the accident.

Further, the opening / closing means for performing the closing operation may be control means for performing only the same phase as that of the circuit breaker which performs the fault current interruption operation first.

[0013]

According to the present invention, the above object is attained by the following operation according to the present invention. According to the present invention, an overvoltage suppression device including switching means and impedance is provided between at least one of the busbar side and the transmission line side of the circuit breaker and the ground, and when a transmission line ground fault occurs, the Prior to the fault current interruption operation of the circuit breaker installed on the transmission line or the completion of the current interruption, the switching means of the overvoltage suppression device of the healthy transmission line is closed to insert the impedance between the transmission line and the ground. As a result, the breaking surge voltage of the circuit breaker is reduced by being damped by the impedance.

Further, since the overvoltage suppression device is turned on after detecting the transient recovery voltage generated after the fault current interruption of the circuit breaker, the transient recovery voltage is also braked and reduced in the same manner as the interruption surge voltage.

Further, since the cutoff surge voltage and the transient recovery voltage are generated in the fault current cutoff phase, the overvoltage can be reduced even if the closing operation of the switching means is only in the same phase as the faulty phase.

[0016]

FIG. 1 shows the configuration of an embodiment of the present invention. In the figure, a power system 1 includes a power generator 6 connected to a bus 10 via a power transformer 5 and a circuit breaker 4.
And a transmission line 2a connected to the bus 10 via a circuit breaker 3a, and a transmission line 2b connected to the bus 10 via a circuit breaker 3b.
Are composed of two sets. In addition, the transmission lines 2a, 2b
Lightning arresters 9a and 9b
Is installed. A switch 7a and a resistor 8a connected in series between a circuit connecting the circuit breaker 3a and the transmission line 2a and the ground.
Is provided. The switch 7a and the resistor 8a connected in series constitute an overvoltage suppressing device. Similarly, a switch 7b and a resistor 8b connected in series are provided between a circuit connecting the circuit breaker 3b and the transmission line 2b and the ground.

Information such as current and voltage of the current transformer and the like is transmitted from the detector 35 to the power system protection controller 31 via the signal line 103. Although FIG. 1 shows the power transmission line 2a side in detail, a similar device is also connected to the power transmission line 2b side, but is partially omitted in the figure. The power system protection control device 31 includes an information input unit 4 for receiving information from the detector 35.
1, an input unit 42 for capturing the open / close state information of the circuit breaker 3a and the switch 7b, and a control unit 40 for controlling the circuit breaker 3a and the switch 7b based on the information.

In FIG. 1, consider a case where a ground fault has occurred in one phase of the transmission line 2a. FIG. 4 shows voltage fluctuations at various parts of the transmission line when a ground fault occurs. When a ground fault occurs, a large ground fault current flows in the direct grounding system at the neutral point, and the amplitude of the power supply voltage decreases as shown by a curve 20 in FIG. The terminal voltage of the circuit breaker 3a of FIG.
From Vo to Vt. At this time, in the sound transmission line 2b, at the location corresponding to the fault point due to the electromagnetic induction from the faulty transmission line 2a, the voltage further drops by dV to Vm as shown by the curve 22 in FIG. 4C. I have. In such a state, when the ground fault current is interrupted by the circuit breaker 3a, the power supply voltage 20 in FIG. 4A is restored to the original voltage. At this time, the voltage Vs is changed due to the transient vibration of the power supply system. To rise.

On the other hand, the voltage of the interrupted transmission line 2a reciprocates in the transmission line 2a. By the way, since the transmission line 2b which was sound also had a voltage drop of dV due to the induction, the transmission line 2b reflected and reciprocated in the transmission line 2b and vibrated. In addition, vibration induced by the reciprocating voltage vibration of the interrupted accident transmission line 2a is superimposed. As a result, a high-frequency vibration kdV (k> 1) much larger than dV is superimposed. Therefore, at the fault-response position of the sound transmission line 2b, the maximum voltage rises to VL where kdV is superimposed on Vs, resulting in an excessive surge voltage.

However, in one embodiment of the present invention, when the circuit breaker is in operation, the overvoltage suppression device is inserted between the healthy power transmission line 2b and the ground, so that the transient vibration of the power supply side voltage is reduced between the healthy power transmission line 2b and the ground. And the amplitude is reduced by the resistor 8b connected to the resistor 8b. And the reciprocating voltage oscillation in the healthy transmission line 2b is also damped by this. A resistor 8a is connected to the accident transmission line 2a. Since the reciprocating reflection vibration of the accident transmission line 2a is damped by the resistor 8a, the induction to the healthy transmission line 2b by the voltage reciprocation vibration of the accident transmission line 2a is reduced. As a result, the ground-fault interruption surge is much smaller than before.

Hereinafter, an embodiment of the present invention will be described in detail.

In FIG. 1, when a system fault 30 occurs in the transmission line 2a, the power system protection control device 31 takes in information from the detector 35 from the input unit 41 through the signal line 103 and outputs the result of the accident determination to the signal line 108. , Or the information of the detector 35 is output from the input unit 41 to the control unit 40 via the signal line 108, and the control unit 40 determines an accident. This may be performed by either the control unit 40 or the input unit 41, and either one may be selected according to the hardware configuration.

The operation after it is determined that an accident has occurred will be described with reference to the configuration shown in FIG. 1 and the flowchart of FIG.
When the control unit 40 or the input unit 41 determines that there is an accident in the transmission line (process 201 in FIG. 2), the control unit 40
b through a signal line 102 (FIG. 2).
Process 202). In synchronization with this input command, the control unit 40
Is connected to the other protection control device 32 as necessary.
It is also possible to give a shut-off lock command via 06. This is a process for preventing unnecessary disconnection, because there is a possibility that this may be mistaken for a system accident depending on the device when the switch 7b is turned on. As a method of the unnecessary cutoff prevention processing, in addition to the method using the cutoff lock signal, the currents and voltages of the switches 7a and 7b or the resistors 8a and 8b and the like can be input and determined.
For example, when the switches 7a and 7b are turned on, or when a certain current flows in the overvoltage suppression device, the cutoff lock can be performed. When it is determined based on the electric current or the like, when a certain amount is exceeded, it is possible to determine that a system fault has occurred and release the shutoff lock. By doing so, it becomes possible to turn on the switches 7a and 7b and to discriminate the system fault, and it is possible to construct a more reliable power system.

The control unit 40 gives a tripping command to the circuit breaker 3a via the signal line 101 after or simultaneously with the execution of the process 202 in FIG. 2 (process 203 in FIG. 2).

When giving the trip command, the circuit breaker 3
When the operation coordination between a and the switch 7b is required, the operation can be performed as follows.

For example, after the switch 7b is turned on, the circuit breaker 3a
When the switch is tripped, the state of the switch 7b is input to the input section 42 via the signal line 104, and this state is
To the control unit 40 via the. When the control unit 40 determines that the switch 7b is turned on based on the state of the switch 7b taken in, the control unit 40 gives a tripping command to the circuit breaker 3a. As means for knowing the open / close state of the switch 7b, pallets indicating the state of the switch 7b, state confirmation by a sensor, or the like,
Alternatively, it can be confirmed by the current, voltage and the like flowing through the switch 7b. The signal line 104 may be an optical communication unit or the like. This is the same for the other signal lines 101 to 108.

In the above-described embodiment, after the state of the switch 7b is confirmed, the tripping command of the circuit breaker 3a is output. However, without confirming the state of the switch 7b, the closing command is given to the switch 7b. Is given by the control unit 40, and after this time, a trip command can be output to the circuit breaker 3a.

Further, when the operation coordination between the switch 7b and the circuit breaker 3a is previously established, the switch 7b and the circuit breaker 3a
It is also possible to output a command at the same time.

Regarding these three embodiments, in addition to individually configuring, three or two arbitrary types are incorporated in advance, and at least one or more of the optional embodiments is selected by switching means such as settling and tapping. Is also possible.

When the switch 7b is turned on and the circuit breaker 3a is tripped, the system fault 30 is eliminated.
As the information on the removal of the system fault 30, information from the detector 35 can be taken into the control unit 40 via the signal line 103, or information such as the opening of the circuit breaker 3a can be taken through the signal line 105.
If there is the system fault 30 removal information obtained from these, the control unit 40 gives an opening command to the switch 7b (process 205 in FIG. 2), and the operation of the system fault removal is completed.

Another embodiment of the present invention will be described with reference to FIG.

As in the above embodiment, when the power system protection controller 31 detects a system fault 30, the power system protection controller 31 outputs a tripping command to the circuit breaker 3a.
The circuit breaker 3a is tripped, and a transient recovery voltage is generated immediately after the circuit breaker 3a is cut off. This transient recovery voltage is taken into the protection device 31 from the detector 35 in the same manner as in the above embodiment. In the power system protection control device 31, the control unit 40 or the input unit 41 determines whether or not the voltage is a transient recovery voltage based on the voltage information. The switch 7b is opened and closed.

FIG. 3 shows a flowchart of this procedure. As a method of determining whether or not the voltage is a transient recovery voltage in the process 303, a method of determining the amount of analog-to-digital conversion of a voltage rise from a voltage at a steady state by high-speed sampling by software, or a method of determining the voltage at a steady state A method of determining the logical product of the condition of the voltage rise from the system and the condition of the occurrence of a system fault by software or a logic circuit, etc.

In the embodiments described so far, the phases controlled by the circuit breakers 3a and 3b and the switches 7a and 7b are not particularly described. It is possible to control the signal line 101 for each phase,
The signal line 102 is connected to the three phases at a time or the signal lines 101 and 1
Also in each of the phases 02, if the control unit 40 outputs a command simultaneously for the three phases, the three-phase collective control is possible.

If the control unit 40 receives from the input units 41 and 42 information about the open / closed state of each phase of the circuit breaker, the open / closed state of each phase of the switch, and the phase in which the system fault occurred, the system fault occurs. It is also possible to control the circuit breaker and the switch only for the phase in which the circuit breaker has occurred, and to control the circuit breaker only for the phase in which a system failure has occurred, and to control the three-phase switch all together. In order to perform these controls, the signal lines 101, 10
2 may be set to each phase or three phases as needed.
It goes without saying that the control method can be easily implemented in the embodiments described so far.

Still another embodiment of the present invention is as follows. The timing of giving a tripping command to the circuit breaker and a switching command to the switch is the same as in the embodiments described so far. If the information and the command for giving commands to the circuit breaker and the switch are performed using communication means, for example, optical communication, wireless communication, wired communication, etc., the power system protection control device 31 can be installed in another place. Can be. Alternatively, simultaneous control can be performed between electric stations that want to control switches and the like at the same time. This simultaneous control method is possible if the signal lines 101, 102 and 106 output from the control unit 40 are performed by communication means, and the signal lines 108 and 107 from the input units 41 and 42 are used as communication means. It is also possible to install the control unit 40 at another location or to transfer information to the control unit 40 and to a protection control device installed at another location. This is because the signal lines 103, 104, 1
The same applies to 05. The control method of the command given to the switch and the circuit breaker can be realized by the same method as that of the embodiments described so far, since the signal line is merely replaced by the communication means.

The power system to which the power system protection control apparatus according to one embodiment of the present invention is applied is shown in FIGS.
In any case, the same control as in the embodiment of the present invention can be performed.

In each of FIGS. 5 to 9, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.

FIG. 5 shows an example having the same configuration as that of FIG. 1, but using non-linear resistors as the resistors 8a and 8b constituting the overvoltage suppressing device.

FIG. 6 shows an example in which an overvoltage suppressing device comprising a switch 7 and a non-linear resistor 8 is provided on a bus 10.

FIG. 7 shows a configuration in which the lightning arresters 9a and 9b for transmission lines are omitted from the configuration of FIG. 5, and an overvoltage suppression device comprising switches 7a and 7b and non-linear resistors 8a and 8b on transmission lines 2a and 2b. This is an example in which is provided.

FIG. 8 shows a lightning arrester for transmission lines in which taps are provided on the non-linear resistor, and switches 7a and 7b are provided in parallel on the transmission line side separated by the taps. The protection control devices 31a and 31b are provided for the transmission lines 2a and 2b, respectively. Also in this case, some of the signal lines are omitted.

FIG. 9 shows an example in which a tap is provided on the non-linear resistor of the surge arrester 9 provided on the bus 10, and a switch is provided in parallel on the ground side separated by the tap.

[0044]

According to the present invention, the overvoltage suppression level can be greatly reduced, so that the insulation level of the entire power transmission system can be reduced and an economical power system can be provided. Also, since overvoltage is suppressed,
There is an effect that a highly reliable power system with few accidents can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart illustrating the operation of one embodiment of the present invention.

FIG. 3 is a flowchart illustrating the operation of another embodiment of the present invention.

FIG. 4 is a diagram showing an example of an overvoltage waveform at the time of a transmission line ground fault, where (a) is a power supply voltage, (b) is a breaker terminal voltage,
(C) is a voltage corresponding to a healthy transmission line accident corresponding point.

FIG. 5 is a diagram showing an example in which a non-linear resistance is applied to the impedance of the overvoltage suppression device in one embodiment of the present invention.

FIG. 6 is a diagram showing another example in which a non-linear resistance is applied to the impedance of the overvoltage suppression device in one embodiment of the present invention.

FIG. 7 is a diagram showing still another example in which a non-linear resistance is applied to the impedance of the overvoltage suppression device in one embodiment of the present invention.

FIG. 8 is a diagram illustrating an example in which a non-linear resistance of a lightning arrester is applied to the impedance of the overvoltage suppression device in one embodiment of the present invention.

FIG. 9 is a diagram showing another example in which the nonlinear resistance of the lightning arrester is applied to the impedance of the overvoltage suppression device in one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Power system 2a, 2b Three-phase power transmission line 3a, 3b, 4 Circuit breaker 5 Power transformer 6 Power supply 7, 7a, 7b Switching means 8, 8a, 8b Impedance 9, 9a, 9b Lightning arrester 10 Bus bar 31, 31a, 31b Protection Control device 32 Protection control device 35, 35a, 35b Detector 40 Control unit 41, 42 Input unit, 101-108, 101a-106a, 101b-10
6b signal line

Continuation of front page (72) Inventor Minoru Seya 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture Inside the Kokubu Plant of Hitachi, Ltd. (56) References JP-A-53-145038 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) H02J 3/24 H02H 7/26 H02H 9/04

Claims (5)

(57) [Claims] 1. A power system protection control device for a power system comprising a bus connected to a power supply and a plurality of three-phase transmission lines drawn out from the bus via a circuit breaker. An overvoltage suppression device in which switching means provided between at least one of the electric wires and the ground and an impedance are connected in series, and an accident detecting means for detecting an accident of the three-phase transmission line from the current and voltage of the transmission line And closing the switching means other than those installed on the accident transmission line by the accident detection output of the accident detection means, opening the circuit breaker of the accident transmission line after the closing operation, And a control means for opening the switching means in response to the output of the removal of the accident. 2. A power system protection control device for a power system comprising a bus connected to a power supply and a plurality of three-phase transmission lines drawn out from the bus via a circuit breaker. An overvoltage suppression device in which switching means provided between at least one of the electric wires and the ground and an impedance are connected in series, and an accident detecting means for detecting an accident of the three-phase transmission line from the current and voltage of the transmission line Opening the circuit breaker of the accident transmission line by the accident detection output of the accident detection means, closing the opening and closing means other than the one installed on the accident transmission line before the completion of current interruption of the circuit breaker, A control means for opening the switching means in response to the output of the fault detection means for removing the fault. 3. A power system protection and control device for a power system comprising a bus connected to a power supply and a plurality of three-phase transmission lines drawn out from the bus via a circuit breaker. An overvoltage suppression device in which switching means provided between at least one of the electric wires and the ground and an impedance are connected in series, and an accident detecting means for detecting an accident of the three-phase transmission line from the current and voltage of the transmission line A transient recovery voltage detecting means for detecting a rise of a transient recovery voltage immediately after the breaker of the faulty transmission line is cut off, and the switching means other than the switching means provided on the faulty transmission line after detection by the transient recovery voltage detecting means. Close operation, by the output of the accident removal of the accident detection means,
And a control means for opening the opening / closing means. 4. The power system protection control device according to claim 2, wherein the circuit breaker before the completion of the current interruption is a circuit breaker of a phase in which the current is interrupted first. 5. The power system protection control device according to claim 3, wherein the output of the transient recovery voltage detecting means is an output detected first.