JP2001238346A - Step-out detection relay device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect any stepping out in a system to be protected with accuracy by correctly calculating the phase difference between electric power stations, even if the voltage from a line transformer and the voltage from a bus transformer are taken in to calculate the positive phase voltage. SOLUTION: The step-out detection relay device comprises a positive phase voltage computing portion 4, which takes in the three-phase voltage from a power system wherein at least two electric power stations are connected with each other through a transmission line and obtains a positive phase voltage from the three-phase voltage, a transmission portion 7, which transmits and receives the positive phase voltage between the electric power stations, a phase difference computing portion 5, which determines the phase difference between positive phase voltage from the electric power station on this end and positive phase voltage from the electric power station on the other end, and a step-out detection judging portion 6 which detects stepping out in the system, when the phase difference is inverted 180 deg. between the electric power stations. The step-out detection relay device is provided with an interruption phase judging portion 3, which when it is fed with a three-phase voltage and detects interruption phase of the transmission line, zeros the voltage of the interruption phase and inputs the result to the positive phase voltage computing portion 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step-out detection relay for detecting a step-out of a system from a phase difference of a positive-phase voltage between electric stations of a power system.

[0002]

2. Description of the Related Art Conventionally, as a system for detecting a step-out of a power system, as shown in FIG. 8, both electric stations A and B which are power supply terminals are connected by a transmission line L via a circuit breaker CB. In the two-terminal system, the bus voltage of both electric stations A and B and the current flowing through the transmission line L are measured, and these are inputted to the step-out detection relays RY-A and RY-B, respectively, to obtain the positive phase voltage. There is a system in which a step-out of a system is detected from a phase difference between positive-phase voltages transmitted between both electric stations, and a trip command is given to a circuit breaker CB to protect a system to be protected.

The step-out detecting relay RY-A receives a voltage and a current measured at both electric stations by an analog input unit 11 as shown in FIG. The positive-phase voltage calculator 12 calculates the positive-phase voltage of the terminal itself, inputs the same to the phase difference calculator 14, and transmits the positive-phase voltage to the other end through the transmission processor 16. Then, the phase difference calculator 14 takes in the positive phase voltage of the own end and the positive phase voltage from the other end received by the transmission processor 16 and calculates the phase difference between the positive phase voltage of the own end and the positive phase voltage of the other end. This is input to the step-out detection determination unit 15. In this step-out detection judging unit 15, the voltage phase difference between the electric stations is 1
The step-out is detected by being inverted by 80 °, and a trip command is given to the circuit breaker CB.

The out-of-step detection relay RY-B of the substation B
Has the same configuration as above.

Here, the determination (principle) of step-out detection of the system will be described with reference to FIG.

In FIG. 9A, reference numerals 21a and 21b denote system power supplies of electric stations A and B, and reference numeral 22 denotes a three-phase transmission line connecting the electric stations A and B, respectively.

[0007] First, the positive phase voltage V ₁ of the substation A (A) is _{V 1 (A) = (1/3} ) (V R + aV s + a 2 V T) (1) ∵a = ε jθ (= 1 ∠θ) θ = 120 ° VR, VS, VT is the positive phase voltage V ₁ of the three-phase voltage substation B at the substation a (B) is _{V 1 (B) = (1/3} ) (V R + aV s + a ² V _T ) (2) ∵a = ε ^jθ (= 1∠θ) θ = 120 ° VR, VS, VT are three-phase voltages at the substation B. In the power system, if there is no step-out phenomenon, the substation A The phase difference between the positive-phase voltage and the positive-phase voltage at the substation B does not change at a certain value. However, when the step-out phenomenon occurs, the substation A
9B, the phase difference between the positive phase voltage of the substation and the positive phase voltage of the substation S slips. A method is known in which the phase difference between the positive phase voltage at the electric station A and the positive phase voltage at the electric station B is inverted by 180 °, and a step-out phenomenon is detected.

Here, when the positive-phase voltage is used, the three-phase circuit has an advantage that even if one phase is lost, the calculation of the phase difference is not affected.

[0009]

In such a step-out detection relay device, an instrument transformer is generally used in order to take in the voltage of the power system. The instrument transformers include a line transformer (hereinafter referred to as LPT) that takes in the voltage of the transmission line, and a bus transformer (hereinafter called BPT) that takes in the bus voltage.

[0010] By the way, a method of taking in a voltage at an electric station is as follows.
Not all are taken from the same instrument transformer. For example, the substation A may be combined with the LPT and the substation B may be combined with the BPT. In this case, if one phase of the three-phase transmission line between the two substations is interrupted, the substation that takes in the voltage using the BPT will output the three-phase balanced voltage regardless of the interruption of the transmission line. Can be captured.

[0011] However, in an electric power plant that uses the LPT to take in the voltage, the voltage of the unbroken line of the transmission line can take in a healthy voltage, but the voltage of the broken line can be a healthy phase or other voltage. Induction from another transmission line or the like that is overlaid causes frequency fluctuations and phase changes.

When calculating the phase difference of the positive phase voltage between the electric stations as described above, the phase difference is obtained from the positive phase voltage obtained from the three-phase balanced voltage taken from the BPT and the voltage including the voltage derived from the LPT. The phase difference between electric stations cannot be calculated correctly with the positive-sequence voltage.

[0013] The present invention has been made in view of the above-described circumstances. Even if the voltage from the line transformer and the voltage from the bus transformer are taken into account and the positive-phase voltage is calculated, the voltage between electric stations can be correctly calculated. It is an object of the present invention to provide a step-out detection relay device capable of calculating the phase difference of the step-out and detecting the step-out of the protection target system with high accuracy.

[0014]

According to the present invention, in order to achieve the above object, a step-out detecting relay device is constituted by the following means.

The invention corresponding to claim 1 has at least 2
Positive-phase voltage calculating means for taking in a three-phase voltage from a power system connecting power stations with a transmission line and obtaining a positive-phase voltage from the three-phase voltage, and transmitting and receiving the positive-phase voltage between the power stations Transmission processing means, a phase difference calculating means for calculating a phase difference between the positive phase voltage of the own electric station and the positive phase voltage from the partner electric station, and a condition that this phase difference is inverted by 180 ° between the two electric stations. In the step-out detection relay device comprising a step-out detection determining means for detecting step-out of the system, the three-phase voltage is input, and when the cut-off phase of the transmission line is detected, the voltage of the cut-off phase is An interrupting phase judging means for setting the value to zero and inputting it to the positive phase voltage calculating means is provided.

According to a second aspect of the present invention, in the step-out detection relay device according to the first aspect of the present invention, the cut-off phase determining means includes a three-phase each phase provided on a transmission line connected to an electric substation. In this case, the cutoff phase is detected by inputting a cutoff command signal of the circuit breaker corresponding to.

A third aspect of the present invention is the step-out detection relay device according to the first aspect of the present invention, wherein the cut-off phase determining means detects a cut-off phase by inputting a circuit breaker open condition signal. is there.

According to a fourth aspect of the present invention, in the step-out detection relay device according to the first aspect of the present invention, the shut-off phase determining means combines a shut-off command signal to the breaker and an open condition of the breaker. This is to detect a blocking phase.

According to a fifth aspect of the present invention, in the step-out detection relay device according to the first aspect of the present invention, the cut-off phase determining means detects a cut-off phase based on an output signal of an undervoltage relay.

According to a sixth aspect of the present invention, in the out-of-step detection relay device according to the first aspect of the present invention, the cut-off phase determining means detects a cut-off phase by detecting a change in system frequency.

According to a seventh aspect of the present invention, in the out-of-step detection relay device according to the first aspect of the present invention, the cut-off phase determining means detects a cut-off phase based on an output signal of a power flow detection relay.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a system configuration diagram showing a first embodiment of a step-out detection relay device according to the present invention. The system to be protected is the same as that shown in FIG. 8, and a description thereof will be omitted.

In FIG. 1, reference numeral 1 denotes an analog input unit 1;
The analog input unit 1 is connected to a current transformer 8 provided on the transmission line L.
And the transmission line or bus voltage measured by the instrument transformer 9 are input, respectively, and these are input to the cut-off phase determination unit 3 via the A / D converter 2. The cut-off phase determination unit 3 determines whether or not there is a cut-off phase based on the three-phase voltage, the breaker condition from the protection / control device, and the presence or absence of a cut-off command signal. The voltage value at that time is input to the arithmetic unit 4.

The positive-sequence voltage calculating section 4 obtains the positive-phase voltage at its own end, inputs the same to the phase difference calculating section 5, and transmits the positive-phase voltage to the other end through the transmission processing section 7. Then, the phase difference calculating section 5 takes in the positive phase voltage of the own end and the positive phase voltage from the other end received by the transmission processing section 7 to calculate the phase difference between the positive phase voltage of the own end and the positive phase voltage of the other end. This is input to the step-out detection determination unit 6. The out-of-step detection determining unit 6 detects out-of-step because the voltage phase difference between the electric stations is inverted by 180 °, and gives a trip command to the circuit breaker CB.

Next, the operation of the step-out detection system having such a configuration will be described with reference to the flowchart shown in FIG.

When the voltage and current of the protection target system taken into the analog input unit 1 are input to the A / D converter 2, they are digitally converted by the A / D converter 2, and the cutoff phase determination unit 3 The voltage corresponding to each of the three phases is taken in.

When the interruption of the three-phase voltage is completed (S21), the cut-off phase determining section 3 first determines whether or not there is a cut-off command for the first phase (S22).
23, and if there is a cutoff command, the first phase voltage is set to 0V
(S24), and then proceed to S23.

Next, at S23, it is determined whether or not there is a second-phase cutoff command. If there is no cutoff command, the process proceeds to S25. If there is a cutoff command, the voltage of the second phase is set to 0 V (S26). Proceed to S25.

Subsequently, in S25, it is determined whether or not there is a third phase shutoff command. If there is no shutoff command, the process proceeds to S27,
If there is a cutoff command, the voltage of the third phase is set to 0 V (S28), and the process proceeds to S27.

Then, in S27, it is determined whether or not there is a three-phase cutoff command.
The calculation of the positive-phase voltage is performed (S29), and the step-out detection determination unit 6 performs the calculation of the step-out detection (S30). If there is a three-phase cutoff command, the calculation of the positive-phase voltage and the step-out detection calculation are not performed.

As described above, the three-phase voltage is taken into the cut-off phase judging unit 3, and it is sequentially judged whether or not there is a cut-off command for each phase output from the protection / control device. If there is, the voltage value of the phase is set to 0 V, the positive-phase voltage is calculated using the voltage value, and the calculated voltage is used for the calculation of the step-out detection, whereby the correct phase between the electric stations can be calculated.

Therefore, according to the first embodiment, since the voltage of the cutoff phase is set to 0 V before the breaker is actually cut off, the input of the voltage transient characteristic when the breaker is opened is also eliminated. it can.

FIG. 3 is a flowchart for explaining the operation of the out-of-step detection relay device according to the second embodiment of the present invention. Since it is the same as FIG. 1 except that the open circuit condition of the circuit breaker is used as the phase detecting means, the description is omitted here.

When a voltage corresponding to each of the three phases is taken into the shutoff phase determining section 3 (S31), it is first determined whether or not there is an open condition for the first phase (S32). S3
3. If there is an open circuit condition, the voltage of the first phase is set to 0V.
(S34), and then proceed to S33.

Next, in S33, it is determined whether or not there is an open condition of the second phase. If there is no open condition, the process proceeds to S35. If there is an open condition, the voltage of the second phase is set to 0V (S36). Proceed to S35.

Subsequently, in S35, it is determined whether or not there is a shutoff command of the third phase. If there is no shutoff command, the process proceeds to S37,
If there is a cutoff command, the voltage of the third phase is set to 0 V (S38), and the process proceeds to S37.

Then, in S37, it is determined whether or not there is an open condition for the three-phase circuit breaker. If there is no open condition, the positive-phase voltage calculation unit 4 calculates the positive-phase voltage (S39). The step-out detection determining unit 6 performs a step-out detection calculation (S4).
0). If there is a three-phase cutoff command, the calculation of the positive-phase voltage and the step-out detection calculation are not performed.

As described above, the three-phase voltage is taken into the cut-off phase judging section 3, and it is sequentially judged whether or not there is an open condition in the circuit breaker of each phase. For example, by setting the voltage value of the phase to 0 V, calculating the positive-phase voltage using the voltage value, and using the voltage for the step-out detection calculation, the correct phase between the electric stations can be calculated.

Therefore, according to the second embodiment, following the response of the circuit breaker, the voltage of the cutoff phase is reduced to 0 during the cutoff.
V, and the calculation of the positive-phase voltage can be resumed with the three-phase voltage input from the analog input unit from the time when the circuit breaker is closed.

FIG. 4 is a flowchart for explaining the operation of the out-of-step detection relay device according to the third embodiment of the present invention. Protection and
Since it is the same as FIG. 1 except that the shutoff command of each phase from the control device and the open condition of the circuit breaker are used, the description thereof is omitted here.

When the voltage corresponding to each of the three phases is taken into the cut-off phase determining section 3 (S41), it is determined whether or not there is a cut-off command for the first phase (S42). It is determined whether the first-phase opening condition is satisfied (S43), and if there is no opening condition, the process proceeds to S44. Further, if it is determined in S42 that there is a first-phase cutoff command, or if it is determined in S43 that there is a first-phase open circuit condition, the first-phase voltage is set to 0 (S4
Then, go to S44.

Next, in S44, it is determined whether or not there is a second-phase shutoff command.
It is determined whether or not there is an open condition for the phase breaker. If there is no open condition, the process proceeds to S47. If it is determined in S44 that there is a second-phase shutoff command, or if it is determined in S46 that the open condition of the second-phase circuit breaker is present, the voltage of the second phase is set to 0 V (S48). Proceed to S47.

Subsequently, in a step S47, it is determined whether or not there is a shut-off command of the third phase.
It is determined whether or not there is an open condition of the third phase of the circuit breaker at,
If there is no open circuit condition, the process proceeds to S50. In S47, the third
If it is determined that there is a phase cutoff command, or if it is determined in S49 that there is an open condition for the third phase breaker, the voltage of the third phase is set to 0 V (S51), and the process proceeds to S50.

Then, in S50, it is determined whether or not the three-phase voltage is 0V.
The calculation of the positive phase voltage is performed at (S52), and the step-out detection determination unit 6 performs the calculation of the step-out detection (S53). Also,
If the three-phase voltage is 0 V, the calculation of the positive-phase voltage and the step-out detection calculation are not performed.

As described above, the three-phase voltage is taken into the cut-off phase judging section 3 to sequentially judge whether or not there is a cut-off command for each phase from the protection / control device and an open condition from the circuit breaker for each phase. 1
If there is a disconnection command and an open circuit condition from the third phase to the third phase, the voltage value of the phase is set to 0 V, the positive-phase voltage is calculated using the voltage value, and used for the calculation of the step-out detection. The correct phase between them can be calculated.

Therefore, according to the third embodiment, the first
In the embodiment, the removal of the transient characteristic voltage when the circuit breaker is cut off and the calculation of the positive-phase voltage by the three-phase voltage input following the response of the circuit breaker can be performed.

FIG. 5 is a flow chart for explaining the operation of the out-of-step detection relay device according to the fourth embodiment of the present invention. Since it is the same as FIG. 1 except that the output of the undervoltage relay is used as the phase detecting means, the description is omitted here. The undervoltage relay is provided on the transmission lines L at both ends of the protection target system shown in FIG.

When the voltage corresponding to each of the three phases is taken into the cut-off phase determining section 3 (S61), it is first determined whether or not the output from the undervoltage relay is a voltage drop of the first phase (S6).
2) If there is no voltage drop, the process proceeds to S63, and if there is a voltage drop, the voltage of the first phase is set to 0 V (S64), and
Proceed to.

Next, in S63, it is determined whether or not the voltage of the second phase is low. If the voltage is not low, the process proceeds to S65. If the voltage is low, the voltage of the second phase is set to 0 V (S66). Proceed to S65.

Subsequently, in S65, it is determined whether or not the voltage drop of the third phase is present. If not, the process proceeds to S67,
If the voltage drops, the voltage of the third phase is set to 0 V (S68), and the process proceeds to S67.

Then, in S67, it is determined whether or not all three phases have a voltage drop.
The calculation of the positive phase voltage is performed (S69), and the step-out detection determination unit 6 performs the calculation of the step-out detection (S70). Also,
If all three phases have a voltage drop, the calculation of the positive phase voltage and the step-out detection calculation are not performed.

As described above, the three-phase voltages are taken into the cut-off phase judging section 3 and the presence or absence of the voltage drop of each phase is sequentially judged from the output of the undervoltage relay, and there is a voltage drop among the first to third phases. For example, by setting the voltage value of the phase to 0 V, calculating the positive-phase voltage using the voltage value, and using the voltage for the step-out detection calculation, the correct phase between the electric stations can be calculated.

Therefore, according to the fourth embodiment, the normal phase voltage calculation can be restarted with the three-phase voltage input from the analog input unit, because the voltage of the interrupted phase has returned to the normal voltage.

FIG. 6 is a flowchart for explaining the operation of the out-of-step detection relay device according to the fifth embodiment of the present invention. Since it is the same as FIG. 1 except that the output of the frequency detection relay is used as the phase detecting means, the description is omitted here. The frequency detection relay is provided on the transmission line L at each end of the protection target system shown in FIG.

When the voltage corresponding to each of the three phases is taken into the cut-off phase determining section 3 (S71), it is first determined whether or not there is a change in the frequency of the first phase from the output of the frequency detecting relay (S7).
2) If there is no change in the frequency, the process proceeds to S73, and if there is a change in the frequency, the voltage of the first phase is set to 0 V (S74), and the process proceeds to S73.

Next, in S73, it is determined whether or not there is a change in the frequency of the second phase. If there is no change in the frequency, the process proceeds to S75, and if there is a change in the frequency, the voltage of the second phase is reduced to 0V.
(S76), and then proceed to S75.

Subsequently, in S75, it is determined whether or not there is a change in the frequency of the third phase.
If there is a change in the frequency, the voltage of the third phase is set to 0 V (S
78), and then proceed to S77.

Then, in S37, it is determined whether or not there is a change in the three-phase common frequency. If there is no change in the frequency, the positive-phase voltage calculator 4 calculates the positive-phase voltage (S79). The out-of-step detection calculation is performed in the out-of-step detection determination unit 6 (S8).
0). If there is a three-phase cutoff command, the calculation of the positive-phase voltage and the step-out detection calculation are not performed.

As described above, the three-phase voltage is taken into the cut-off phase determining unit 3 and it is sequentially determined from the output of the frequency detection relay whether or not there is a change in the frequency of each phase. If there is a change in the frequency, the voltage value of the phase is set to 0 V, the positive-phase voltage is calculated using the voltage value, and the calculated voltage is used for the step-out detection calculation, whereby the correct phase between the electric stations can be calculated. .

Therefore, according to the fifth embodiment, when the frequency of the phase that has been cut off becomes the normal frequency, the calculation of the positive-phase voltage can be restarted with the three-phase voltage input from the analog input unit.

FIG. 7 is a flow chart for explaining the operation of the out-of-step detection relay device according to the sixth embodiment of the present invention. Since it is the same as FIG. 1 except that the output of the power flow detection relay is used as the phase detecting means, the description is omitted here. The tidal current detection relays are provided on the transmission lines L at both ends of the protection target system shown in FIG.

When the voltage corresponding to each of the three phases is taken into the cut-off phase determination unit 3 (S81), it is first determined from the output of the power flow detection relay whether or not there is a first phase power flow (S82). If there is no, the process proceeds to S83, and if there is a power flow, the voltage of the first phase is set to 0 V (S84), and the process proceeds to S83.

Next, in S83, it is determined whether or not there is a second phase power flow. If there is no power flow, the process proceeds to S85. If there is a power flow, the voltage of the second phase is set to 0 V (S86), and the process proceeds to S85. .

Subsequently, in S85, it is determined whether or not there is a third phase power flow. If there is no power flow, the process proceeds to S87. If there is a power flow, the third phase voltage is set to 0 V (S88), and the process proceeds to S87. move on.

Then, in S87, it is determined whether or not there is a change in the three-phase common power flow. If there is no power flow, the positive-phase voltage calculator 4 calculates the positive-phase voltage (S79), and detects step-out. The step-out detection calculation is performed by the determination unit 6 (S80). If there is a three-phase cutoff command, the calculation of the positive-phase voltage and the step-out detection calculation are not performed.

As described above, the three-phase voltage is taken into the cut-off phase determining section 3 and it is sequentially determined whether or not there is a power flow of each phase from the output of the power flow detection relay, and the power flow in the first to third phases is determined. If there is, the voltage value of the phase is set to 0 V, the positive-phase voltage is calculated using the voltage value, and the calculated voltage is used for the step-out detection calculation, whereby the correct phase between the electric stations can be calculated.

Therefore, according to the sixth embodiment, since the current value increases due to the step-out phenomenon, the uninterrupted phase can surely detect the tidal current, and the interrupted phase does not flow the electric current but the tidal current. Since no detection is performed, the phase that has been shut off can be reliably detected.

[0069]

As described above, according to the present invention, even if the voltage from the line transformer and the voltage from the bus transformer are taken in and the positive phase voltage is calculated, the phase difference between the electric stations can be correctly calculated. Can be calculated to detect out-of-step of the protection target system with high accuracy.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram showing a first embodiment of a step-out detection relay device according to the present invention.

FIG. 2 is a flowchart for explaining the operation of the embodiment.

FIG. 3 is a flowchart for explaining the operation of the second embodiment of the present invention.

FIG. 4 is a flowchart for explaining the operation of the third embodiment of the present invention.

FIG. 5 is a flowchart for explaining the operation of the fourth embodiment of the present invention.

FIG. 6 is a flowchart for explaining the operation of the fifth embodiment of the present invention.

FIG. 7 is a flowchart for explaining the operation of the sixth embodiment of the present invention.

FIG. 8 is a system configuration diagram showing an example of a conventional step-out detection relay device.

FIG. 9 is an explanatory diagram of a principle of step-out detection in a conventional step-out detection relay device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Analog input part 2 ... A / D conversion part 3 ... Blocking phase determination part 4 ... Positive phase voltage calculation part 5 ... Phase difference calculation part 6 ... Step-out detection determination part 7 ... Transmission processing part 8 ... current transformer 9 ... instrument transformer

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Jin Matsui 2-24-24 Harumicho, Fuchu-shi, Tokyo F-term (reference) in Toshiba System Technology Corporation 5G058 HH01 HH06

Claims (7)

[Claims] 1. A positive-phase voltage calculating means for taking in a three-phase voltage from a power system in which at least two electrical stations are connected by a transmission line, and obtaining a positive-phase voltage from the three-phase voltage; Transmission processing means for transmitting and receiving between the electric stations, phase difference calculating means for calculating the phase difference between the positive phase voltage of the own electric station and the positive phase voltage from the other electric station, and the phase difference between the two electric stations 1
A step-out detection relay device comprising: a step-out detection determination means for detecting step-out of the system on the condition that the phase is inverted by 80 °; wherein the three-phase voltage is input, and when a cut-off phase of the transmission line is detected. A step-out detecting relay device, wherein a cut-off phase determining means for setting the voltage of the cut-off phase to zero and inputting the voltage to the positive-phase voltage calculating means is provided. 2. The step-out detection relay device according to claim 1, wherein said cut-off phase determining means is provided with a cut-off command signal for a circuit breaker corresponding to each of three phases provided on a transmission line connected to an electric substation. A step-out detecting relay device, wherein a cut-off phase is detected by an input. 3. The step-out detection relay device according to claim 1, wherein said cut-off phase determining means detects a cut-off phase by inputting an open circuit condition signal of a circuit breaker. 4. The step-out detection relay device according to claim 1, wherein the cut-off phase determining means detects a cut-off phase by combining a cut-off command signal to the breaker and an open-circuit condition of the breaker. Step-out detection relay. 5. The step-out detecting relay device according to claim 1, wherein said cut-off phase determining means detects a cut-off phase based on an output signal of an undervoltage relay. 6. The step-out detection relay device according to claim 1, wherein said cut-off phase determining means detects a cut-off phase by detecting a change in system frequency. 7. The step-out detection relay device according to claim 1, wherein said cut-off phase determination means detects a cut-off phase based on an output signal of a power flow detection relay.