JP5349037B2 - Current differential protection relay device - Google Patents

Description

  The present invention relates to a current differential protection relay device.

  The current differential protection relay device uses information on the difference between the current at the transmission line and the current at the other end to determine the accident (ground fault, short circuit, etc.) that occurred in the transmission line, etc. It is a relay device. This type of current differential protection relay device is called a PCM current differential relay in Japan. It constructs a PCM communication line between its own end and the other end of the transmission line, and measures at each end. The instantaneous value data of the measured current is communicated with each other through the PCM communication line, thereby calculating the difference current necessary for determining the accident.

  On the other hand, since the PCM communication line is very expensive, in recent years, there is a trend to construct a current differential protection relay device using an inexpensive communication line. However, an inexpensive communication line has a low communication speed, and it is difficult to achieve strict synchronization of instantaneous current value data. Therefore, by transmitting data in place of the instantaneous value data, it is possible to transmit at a cycle different from the generation cycle of the instantaneous value data, realizing a lower transmission speed, and using a standard communication device There is a publication that discloses a current differential protection relay device that can be used (for example, Patent Document 1 below).

  Regardless of whether or not a high-speed PCM communication line is used, current differential relays that communicate instantaneous value data of measured currents with each other can be used for power transmission lines such as distribution substations and oversized customers. When there is a branch load, there is a problem that an erroneous accident determination may be made due to the influence of the branch load current (for example, Patent Document 2 below).

JP 2004-088920 A JP 2001-197656 A

  As described above, the current differential protection relay device disclosed in Patent Document 1 is characterized in that data transmission is performed at a cycle different from the generation cycle of instantaneous value data. In this case, on the receiving side that performs the calculation of the difference current, information on the generation period of the actual instantaneous value data, that is, information on the actual system frequency is required. On the other hand, in Patent Document 1, transmission of system frequency information is not performed. Patent Document 1 also states that “it is clear that the data transmission functions even if it is not periodic” (paragraph “0055”). As is clear from these facts, the method disclosed in Patent Document 1 is based on the premise that the system frequency is the rated frequency, that is, the system frequency does not vary.

  However, in reality, the system frequency often deviates from the rated frequency. Therefore, in the technique shown in Patent Document 1, the calculation error increases due to the fluctuation of the system frequency, and the calculation accuracy is reduced in combination with the reduction of the data amount and the transmission in order to realize the lower transmission speed. There is a recognized problem of malfunction.

  Further, the influence of the branch load current proposed in the above-mentioned Patent Document 2 is positioned as a problem that must be solved in configuring a future current differential protection relay device.

  The present invention has been made in view of the above, and even when an inexpensive communication line is used, it is possible to ensure the calculation accuracy for accident determination and improve the reliability of accident start-up. An object is to provide a differential protection relay device. It is another object of the present invention to provide a current differential protection relay device that ensures calculation accuracy for accident determination even when a transmission line has a branch load.

  In order to solve the above-described problems and achieve the object, the current differential protection relay device according to the present invention is based on the self-current instantaneous value data measured at the self-end side of the transmission line to be protected. A first calculation unit that calculates a change amount of the own-end current rotation vector that is a change amount of the end-current rotation vector, the own-end current rotation vector, and the other end side of the power transmission line. Based on the other end current rotation vector calculated using the transmitted opposite end current instantaneous value data, a change in both end current rotation vector that is a difference component between the current end current rotation vector and the other end current rotation vector at the present time And a both-end current rotation vector that is an amplitude value corresponding to the change in the self-current rotation vector and an amplitude value corresponding to the change in the both-end current rotation vector. A determination unit that determines whether or not an abnormality that has occurred in the transmission line is an accident in a protected area based on an amplitude of a torque change; and when the determination unit determines that an accident in the protected area is detected, And a trip command output unit for outputting a trip command to the device.

  According to the current differential protection relay device according to the present invention, as the temporal rotation vector change, the self-end which is a difference component between the current end current rotation vector at the present time and the current end current rotation vector at the previous cycle time. As the current rotation vector change amount and the spatial rotation vector change amount, the both-end current rotation vector change amount, which is the difference component between the current end current rotation vector and the other end current rotation vector, is calculated, and the end current The presence or absence of an accident in the protected area based on the amplitude of the current rotation vector change, which is the amplitude value of the rotation vector change, and the amplitude of the current rotation vector change, the amplitude of the both-end current rotation vector, Therefore, it is possible to ensure the calculation accuracy for accident determination and improve the reliability of accident start-up. The effect is obtained that.

  Embodiments of a current differential protection relay device according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

(Definition of terms)
The spiral vector theory that is the base of the current differential protection relay device according to the present invention is not sufficiently popular in the world. First, terms used in this specification are defined.

・ Current differential protection relay device: A protection device that determines accidents (protection accidents) in protected areas on power transmission lines (overhead power transmission lines, cables, etc.) and operates a specified relay based on the determination results .
Rotation vector: A rotation vector is a dynamic phasor that rotates counterclockwise on a complex plane, and an actual measurement value is a real part of the rotation vector. In recent AC theory, it is common practice to simulate an AC wave with a cosine function (in the conventional AC theory, an AC wave is simulated with a sine function).
Rotational vector change: A difference component between two rotational vectors around one or several cycle times. The rotation vector change is a complex state variable having a real part and an imaginary part, like the rotation vector. Note that there are two types of rotation vector changes: a temporal rotation vector change and a spatial rotation vector change.
Current rotation vector: A current state variable whose real part is an instantaneous measured current value.
Self-end current rotation vector: current rotation vector on the self-end side.
• Counter-end current rotation vector: current rotation vector at the counter end side.
• Self-end current rotation vector change: A difference component between the current end-current rotation vector at the present time and the self-end current rotation vector at one or several cycles before, and is a temporal current rotation vector change.
-Amplitude of change of own-end current rotation vector: Absolute value of change of own-end current rotation vector.
-Counter-end current rotation vector change: This is a difference component between the counter-end current rotation vector at the present time and the counter-end current rotation vector at one or several cycles before.
-Amplitude of change of counter end current rotation vector: Absolute value of change of counter end current rotation vector.
• Both-end current rotation vector change: A difference component between the current end current rotation vector and the other end current rotation vector, and a spatial current rotation vector change.
-Amplitude of change in current rotation vector at both ends: Absolute value of change in current rotation vector at both ends.
The Institute of Electrical Engineers of Japan EAST10 model system: A model system established in Japan, which is a representative model system for simulating an electric power system.

(Device configuration)
FIG. 1 is a diagram showing a configuration of a current differential protection relay device according to an embodiment of the present invention. In FIG. 1, a current differential protection relay device 1 according to the present embodiment includes a self-end current measurement / A / D conversion unit 2, a self-end current rotation vector change calculation unit 3 as a first calculation unit, Counter end current time-series data receiving unit 4, both-end current rotation vector change calculation unit 5 as the second calculation unit, counter end current rotation vector change calculation unit 6 as the third calculation unit, and current as the determination unit A differential protection determination unit 7, a circuit breaker (CB) trip command transmission unit 8 as a trip command output unit, an interface 9, a storage unit 10, and a remote transmission unit 11 are provided. Here, the current differential protection relay device 1 is a device installed at one end (own end) of the protection section of the transmission line, and is equivalent to the other end (partner end) of the protection section of the transmission line. Current differential protection relay device (shown as the counterpart device 16) is arranged.

(Function of each component)
Next, functions of the components shown in FIG. 1 will be described. Here, only the description of the schematic function will be given here, and the detailed function of each part will be described in the flowchart described later.

  The own-end current measurement / A / D converter 2 measures the current on the own-end side flowing through the transmission line 22 using the CT 13 which is a current transformer installed in the transmission line 22 near the own-end bus 12. , Time-series digital data (instantaneous current instantaneous value data) obtained by sampling at each sample timing that divides one cycle of the reference wave into 4N (N is a positive integer) with respect to the measured current (measured current) ) Is generated.

  The own-end current rotation vector change calculation unit 3 uses the instantaneous current value data generated by the own-end current measurement / A / D conversion unit 2 to calculate the change of the current rotation vector in each phase of the own end.

  The counterpart end current time series data receiving unit 4 receives the current time series data (partner end current instantaneous value data) measured and generated by the counterpart end device 16 via the communication line 15.

  The both-end current rotation vector change calculation unit 5 uses the current instantaneous value data of the own end and the received current instantaneous value data of the other end, and calculates the difference between the current end current rotation vector and the other end current rotation vector. A spatial rotation vector change (a change in both ends current rotation vector) as a component is calculated.

  The other end current rotation vector change calculation unit 6 calculates the amount of change in the current rotation vector (the other end current rotation vector change) in each phase of the other end using the received current value data of the other end.

  The current differential protection determination unit 7 includes an amplitude value corresponding to the change in the current rotation vector (amplitude corresponding to the change in the current rotation vector), an amplitude value corresponding to the change in the current rotation vector at both ends (amplitude corresponding to the change in the current rotation vector at both ends) Based on the above, it is determined whether the abnormality that occurred in the transmission line 22 is an accident in the ward (accident in the protected area), an accident outside the ward (accident outside the protected area), or any other accident (failure) To do.

  The circuit breaker (CB) trip command transmission unit 8 transmits a trip command to the CB 14 that is a circuit breaker on its own end when the current differential protection determination unit 7 determines that the accident is within the ward.

  The interface 9 provides an output function for outputting the above-described calculation results and determination results to an external device or the like. The memory | storage part 10 provides the memory | storage function for hold | maintaining the above-mentioned calculation result and determination result. The remote transmission unit 11 has a function for transmitting current time series data (own end current time series data) measured and generated at its own end to the counterpart device 16 side, and monitoring at a point away from the own end device. Provides a transmission function for transmitting necessary information to employees.

  Note that the counterpart device 16 also flows to the power transmission line 22 using the CT 18 installed in the power transmission line 22 in the vicinity of the counterpart bus 17, similarly to the current differential protection relay device 1 that is the self-end device. While measuring the current on the other end side, time-series digital data (counter end current time-series data) is generated based on the measured current (measured current) and transmitted to the current differential protection relay device 1. The transmitted partner terminal current time series data is received by the partner terminal current time series data receiving unit 4 and taken into the terminal side. Also, on the partner device 16 side, it is determined whether the accident that occurred in the transmission line 22 is a city accident or an out-of-city accident. A trip command is transmitted to the CB 19, which is a container.

  Next, a processing concept (algorithm) in the current differential protection relay device according to the present embodiment will be described.

FIG. 2 is a diagram obtained by modeling an electric power system including a transmission line that is a target of an accident determination. More specifically, FIG. 2A is a model system diagram of an orientation target, and FIG. It is a figure which shows the current rotation vector of a normal state. For convenience of explanation, in each of the following drawings, the current direction of the current instantaneous value i ₁ on the own end side and the current direction of the current instantaneous value i ₂ on the other end side are opposite to each other. Define (see FIG. 2A).

  First, the current rotation vector in the normal state can be expressed as shown in FIG. 2B on the complex plane. At this time, the current rotation vector on the own end side can be expressed by the following equation.

Here, the meaning of each symbol in the above equation (1) is as follows.
I ₁ : Current amplitude ω: Angular velocity θ ₁ : Current initial phase

  Further, the self-end current rotation vector shown in the above equation (2) can be expressed separately as a real part and an imaginary part as in the following expression.

  Here, the self-current instantaneous value data generated by the self-current measurement / A / D conversion unit 2 is substituted into the real part of the above equation (2). Moreover, although an imaginary part is calculated | required by a calculation, this point is mentioned later. In the theory of the present embodiment, the measured instantaneous value is defined as a real part, and the instantaneous current waveform is represented by a cosine function (in the conventional theory (for example, Patent Document 1 above), the instantaneous current waveform is represented by a sine function. Mock)

  Further, the current rotation vector on the other end side (the other end current rotation vector) can also be expressed by the following equation following the above equations (1) and (2).

Here, the meaning of each symbol in the above equations (3) and (4) is as follows.
I ₂ : Current amplitude ω: Angular velocity θ ₂ : Current initial phase

  In the normal state, the local end current rotation vector and the counter end current rotation vector rotate counterclockwise with a phase difference of 180 degrees on the complex plane, so that the following conditional expression is satisfied.

  On the other hand, the change in the current rotation vector at both ends is defined as follows.

  The amount of current change shown in the above equation (6) is obtained by calculating the amount of change in the current rotation vector at two different locations at the same time, and represents the amount of change in the current current rotation vector. On the other hand, the following formula is established from FIG. 2 and formulas (5) and (6).

In the above equation (7), ΔI ₁₂ is the amplitude of the change in the current rotation vector at both ends defined above. In the normal state, each change in the real part (measured instantaneous current value) and the imaginary part of the current rotation vector at both ends is normal. Is zero.

  Here, the point to be noted in the above equation (7) is not the amount of change in the instantaneous current value used in the conventional theory, but the amount of change in the current rotation vector at both ends, which is the effective value of the spatial current rotation vector change. It uses the amplitude. While the accident continues (before the accident is cleared by the circuit breaker), there is a change in the current rotation vector at both ends, and the amplitude takes a large value.

  Further, the change in the self-current rotation vector is defined as follows:

In the above equation (8), T ₀ is one cycle time, T ₀ = 1/60 = 16.6667 ms in the 60 Hz power system, and T ₀ = 1/50 = 20 ms in the 50 Hz power system. is there.

  In the normal state, the following equation is established.

In the above equation (9), ΔI ₁ is the amplitude of the change in the self-end current rotation vector defined above, and is zero in the normal state. That is, in the normal state, it can be seen that the self-current rotation vector on the complex plane exists at the same position before and after one or several cycle times.

  In the period of 1 and 2 cycles immediately after the accident, there is a change in the self-current rotation vector, and the amplitude takes a large value. After one or two cycles, the change in the self-current rotation vector returns to zero. That is, only when the event of accident exists, there is a change in the self-current rotation vector. This fact is advantageous for the current differential protection relay device that is responsible for the main protection of the transmission line.

FIG. 3 is a diagram illustrating a current rotation vector when an in-city accident occurs in the transmission line. In FIG. 3B, the meaning of each symbol is as follows.
i ₁ (t−): Own end current rotation vector immediately before the accident i ₂ (t−): Counter end current rotation vector immediately before the accident i ₁ (t +): Own end current rotation vector immediately after the accident i ₂ (t +): Counter-end current rotation vector immediately after the accident Δi ₁ (t): change in own-end current rotation vector before and after the accident Δi ₁₂ (t): change in both-end current rotation vector before and after the accident

Further, in FIG. 3B, the own-end current rotation vector i ₁ (t−) immediately before the accident is in the fourth quadrant, and the opposite-end current rotation vector i ₂ (t−) immediately before the accident is in the second quadrant. The change between them is zero. On the other hand, the current rotation vector i ₁ (t +) immediately after the accident remains in the fourth quadrant, whereas the current rotation vector i ₂ (t +) immediately after the accident is instantaneously changed from the second quadrant to the fourth quadrant. Inverted to quadrant. That is, when a city accident occurs, one of the two current rotation vectors (in the example of the figure, the counterpart current rotation vector i ₂ (t)) is inverted on the complex plane. For this reason, when a city accident occurs, a large change also occurs in the change in both-end current rotation vector, and the amplitude Δi ₁₂ (t) of the both-end current rotation vector change that is the amplitude value also takes a large value. . In addition, it can be seen that since the accident in the city occurred, the amplitude Δi ₁ (t) of the change in current rotation vector, which is the change in current rotation vector over time, also takes a large value. Thus, FIG. 3 is a diagram accurately showing the principle (inversion of the current rotation vector) relating to the accident determination of the present invention.

FIG. 4 is a diagram showing a current rotation vector when an out-of-city accident occurs, and the meaning of each symbol is the same as FIG. In FIG. 4B, the own end current rotation vector i ₁ (t−) immediately before the accident is in the fourth quadrant, and the other end current rotation vector i ₂ (t−) immediately before the accident is in the second quadrant. The change of is zero. This point is the same as in the case of the city accident (see FIG. 3B). On the other hand, the own end current rotation vector i ₁ (t +) immediately after the accident remains in the fourth quadrant, and the other end current rotation vector i ₂ (t +) immediately after the accident remains in the second quadrant. In other words, the other end current rotation vector i ₂ (t +) immediately after the accident remains in the second quadrant, which is different from the case of the intra-city accident (see FIG. 3B). Thus, in the case of an out-of-city accident, the current rotation vector does not invert on the complex plane. For this reason, when a city accident occurs, the amplitude Δi ₁₂ (t) of the both-end current rotation vector change does not take a large value. Since the out-of-city accident occurred, it can be seen that the amplitude Δi ₁ (t) of the self-current rotation vector change, which is the temporal current rotation vector change, takes a value larger than zero.

  FIG. 5 is a graph showing the relationship between the amplitude of the current rotation vector variation and the amplitude of the both-end current rotation vector variation. In FIG. 5, the horizontal axis indicates the amplitude of the current rotation vector variation, and the vertical axis indicates the amplitude of the current rotation vector variation. Hereinafter, the graph of FIG. 5 is referred to as an “operation characteristic diagram of the current differential protection relay device” or simply an “operation characteristic diagram”.

In FIG. 5, the meaning of each symbol is as follows.
ΔI ₁ : Amplitude of change of own-end current rotation vector ΔI ₁₂ : Amplitude of change of current-end rotation current vector ΔI ₁₀ : Threshold amplitude for evaluating magnitude of change of own-end current rotation vector (when distinguished from other threshold amplitudes) (Referred to as “first threshold amplitude”)
ΔI ₁₂₀ : threshold amplitude for evaluating the magnitude of the amplitude of change in both-end current rotation vector (referred to as “second threshold amplitude” when distinguished from other threshold amplitudes)
α: threshold angle (for example, 5 degrees) for evaluating the ratio of the current rotation vector variation amplitude to the both-end current rotation vector variation amplitude (for example, “first threshold angle” when distinguished from other threshold angles) Called)
β: Threshold angle (for example, 5 degrees) for evaluating the ratio of the amplitude of the current rotation vector variation to the amplitude of the current rotation vector variation at both ends (“second threshold angle” when distinguished from other threshold angles) Called)

  In the operation characteristic diagram of FIG. 5, a region satisfying the following expression is defined as “dead zone I”.

  In a system having a normal state and a branch load, the current differential vector relay amplitude and the both-end current rotational vector variation amplitude are in the dead band I, so the current differential protection relay device does not start.

  Further, in the operation characteristic diagram of FIG. 5, a region satisfying the following expression is defined as “dead zone II”.

  When the above equation (11) is satisfied, the current rotation vector variation amplitude does not exceed the activation threshold even though the current rotation vector variation amplitude exceeds the activation threshold. Even if it exceeds, the ratio of the amplitude of the current rotation vector change with respect to the current rotation vector change amplitude is small, so that it can be determined as an out-of-city accident.

  Furthermore, in the operation characteristic diagram of FIG. 5, a region satisfying the following expression is defined as “dead zone III”.

  When the above equation (12) is established, the amplitude of the current rotation vector change amount does not exceed the start threshold value even though the both-end current rotation vector change amount amplitude exceeds the start threshold value. Even if it exceeds, since the ratio of the amplitude of the change in the current rotation vector relative to the amplitude of the change in current rotation vector at both ends is small, it is determined that no accident has occurred. Note that examples of the case where the amplitude of the change in the current rotation vector at both ends takes a large value although it is not an accident include disconnection of the counterpart CT and interruption of the communication circuit. However, in the electric power system, disconnection of the counterpart terminal CT, communication circuit interruption, and the like are usually performed by another monitoring device, and the necessity of determining an accident by the current differential protection relay device is small.

  In the operation characteristic diagram of FIG. 5, an area satisfying the following expression is defined as an “operation area”.

  When the above equation (13) is satisfied, both the current-end current rotation vector change amplitude and the both-end current rotation vector change amplitude exceed the start threshold value, and it can be determined that the in-city accident occurs.

  When a disconnection or the like of the own-end CT occurs, both the own-end current rotation vector change amplitude and the both-end current rotation vector change amplitude may simultaneously increase and enter the operation region. The lock can be applied with the magnitude of the amplitude of the current rotation vector change. This is because, even when a disconnection of the own-end CT occurs, the amplitude of the other-end current rotation vector change takes a small value when no accident has occurred. For this reason, it is possible to use the magnitude of the amplitude of the counterpart current rotation vector change as a lock element.

  As can be understood from the above description, the “first threshold amplitude” which is a threshold for evaluating the magnitude of the amplitude of the current end rotation vector change and the threshold for evaluating the magnitude of the amplitude of the current end rotation vector change. The “second threshold amplitude” is an activation threshold (current value parameter) for immediately determining that no accident has occurred.

  Further, this is a threshold angle for evaluating the ratio of both-end current rotation vector change amplitude to the end-end current rotation vector change amplitude (ratio of both-end current rotation vector change amplitude and own-end current rotation vector change amplitude). The “first threshold angle” is an activation threshold (threshold angle parameter) for defining an area for determining whether the accident is an intra-city accident or an out-of-city accident.

  Further, this is a threshold angle for evaluating the ratio of the current rotation vector variation amplitude to the both-end current rotation vector variation amplitude (ratio of the current rotation vector variation amplitude and the current rotation vector variation amplitude). The “second threshold angle” is an activation threshold (threshold angle parameter) for defining an area for determining whether the accident is within the city or not.

  Note that the above-described determination method is a method that uses the amplitude of the current-end current rotation vector change and the amplitude of both-end current rotation vector change that occur simultaneously with the occurrence of the accident, and thus inherently has a high speed of start determination.

  FIG. 6 is a diagram in which operating points when an accident in the city occurs are plotted on an operating characteristic diagram. Immediately before the occurrence of the accident in the ward, both the amplitude of the change in the current rotation vector and the amplitude of the change in the current rotation vector at both ends are zero and are located at the origin on the operation characteristic diagram. Thereafter, within one cycle immediately after the accident, for example, both the self-end current vector change amplitude and the double-ended current rotation vector change amplitude both take large values and enter the region indicated by the broken line in the operation region, for example. At this time, the current differential protection relay device is activated. Since the current differential protection relay device is expected to be used as the main protection, the high speed startup determination of the current differential protection relay device of this embodiment is convenient for the power system.

  Furthermore, after one cycle elapses from the occurrence of the accident, for example, the amplitude of the current rotation vector change amount is small, while the both-end current rotation vector change amplitude remains large. In addition, the amplitude of the change in the self-current rotation vector takes a small value but is not zero. The reason is that during the accident, the fault current of the power system includes DC and harmonic components other than the commercial frequency component, and the commercial frequency component also changes. When the circuit breaker (CB) trips, both the self-current rotation vector and both-end current rotation vector change amplitudes become zero.

  FIG. 7 is a diagram in which operating points when an out-of-city accident occurs are plotted on an operating characteristic diagram. Immediately before the occurrence of an out-of-city accident, both the amplitude of the current rotation vector change and the amplitude of the current rotation vector change are both zero and are located at the origin on the operation characteristic diagram. Thereafter, in one cycle immediately after the accident, for example, only the amplitude of the change in the self-current vector takes a large value and enters the area indicated by the broken line in the dead zone II area, for example. Furthermore, after, for example, one cycle has elapsed since the occurrence of the accident, the amplitude of the change in the self-current rotation vector becomes a small value and returns to the dead zone I region.

  FIG. 8 is a diagram in which, for example, operating points when a disconnection occurs at the mating end CT (hereinafter simply referred to as “mating end disconnection accident”) are plotted on the operation characteristic diagram. Immediately before the other end disconnection accident occurs, both the self-end current rotation vector change amplitude and the both-end current rotation vector change amplitude are zero, but immediately after the other end disconnection accident, the own end current vector change amplitude Maintains a zero state, while the amplitude of the current rotation vector change at both ends takes a large value and moves to the dead zone III region.

  FIG. 9 is a flowchart showing the operation of the current differential protection relay device according to the present embodiment, and is a flowchart embodying the processing concept (algorithm) described above.

(Step S101)
In step S <b> 101, the self-end current measurement / A / D conversion unit 2 generates self-end current instantaneous value data. The instantaneous current instantaneous value data is represented by the above formulas (1) and (2), but the measured instantaneous current instantaneous value data is substituted into the real part of the above formula (2).

(Step S102)
In step S102, the self-end current rotation vector change calculation unit 3 calculates the self-end current rotation vector change and the self-end current rotation vector change amplitude. In this process, first, the amount of change in the self-current rotation vector can be calculated using the following equation.

In the above equation (14), T ₀ is one cycle time. Note that an actual measurement value is substituted for the real part, and a value calculated using, for example, the following equation is substituted for the imaginary part.

  Further, the amplitude of the change in the current end rotation vector can be calculated using the following equation.

  It should be noted that the amplitude of the change in the current end rotation vector can also be calculated by the following equation.

  The advantage of using the equation (17) is that the influence of harmonic components can be reduced by integral calculation. However, since the integral calculation is used in the equation (17), the calculation time is longer than the equation (16).

(Step S103)
In step S103, time-series digital data (mating-end current time-series data) generated by the counterpart device 16 is transmitted to the own-end side, and the transmitted time-series digital data is transmitted to the counterpart-end current time-series data receiving unit. 4 is received by the current differential protection relay device 1.

(Step S104)
In step S104, the both-end current rotation vector change calculation unit 5 calculates the both-end current rotation vector change and the both-end current rotation vector change amplitude. In this process, first, the change in the current rotation vector at both ends can be calculated using the following equation.

  In the above equation (18), the actual values shown in the above equations (2) and (4) are substituted into the real part, and the above equation (15) and the later-described equation (22) are used as the imaginary part. The calculated value is substituted.

  Further, the amplitude of the change in the current rotation vector at both ends can be calculated using the following equation.

  The amplitude of the change in the current rotation vector at both ends can also be calculated by the following equation.

  The advantage of using the above equation (20) is that the influence of harmonic components can be reduced by integral calculation. However, since the integral calculation is used in the equation (20), the calculation time is longer than the equation (19).

  In order to maintain simultaneity, it is preferable to calculate the calculation formulas for the amplitude of the change in the current rotation vector and the amplitude of the change in the current rotation vector at both ends by the same type of calculation formula. That is, when calculating the amplitude of the change in the current rotation vector using the equation (16), it is preferable to calculate the amplitude of the change in the current rotation vector using the equation (19). When calculating the amplitude of the current rotation vector change by using the self-end, it is preferable to calculate the amplitude of the current rotation vector change by the equation (20).

(Step S105)
In step S105, the other end current rotation vector change calculation unit 6 calculates the other end current rotation vector change and the other end current rotation vector change amplitude. In this process, first, the change in the counterpart current rotation vector can be calculated using the following equation.

In the above equation (21), T ₀ is one cycle time. Note that an actual measurement value is substituted for the real part, and a value calculated using, for example, the following equation is substituted for the imaginary part.

  The amplitude of the counterpart current rotation vector change can be calculated using the following equation.

  The amplitude of the other end current rotation vector change can also be calculated by the following equation.

  The advantage of using the above equation (24) is that the influence of harmonic components can be reduced by integral calculation. However, since the integral calculation is used in the equation (24), the calculation time is longer than the equation (23).

(Step S106)
In step S106, a determination process is performed as to whether or not there is a ward accident. This determination process can be determined using the following equation. In addition, when it determines with it not being a city accident (step S106, No), it returns to the process of step S101, and when it determines with it being a city accident (step S106, Yes), it transfers to step S107.

  In step 105, the following processing is performed. First, the operating point determined by the amplitude of the current rotation vector variation and the amplitude of the current rotation vector variation of the both ends is a case where three points are continuously plotted in the operation region of the operation characteristic diagram. It can be determined that an accident in the city has occurred when the conditional expression is satisfied.

The meaning of each symbol in the above equation (25) is as follows.
ΔI ₂ (t): Amplitude of change of current-end current rotation vector ΔI ₂₀ : A threshold amplitude for evaluating the magnitude of the amplitude of current-end rotation vector change of the other end Called "Amplitude")

  Here, the case where three points are continuously plotted in the operation region of the operation characteristic diagram is a case where the above expression (13) is satisfied in a time of 5 ms if the system is a 50 Hz system sampled at 30 degrees, for example. . Further, the above expression (25) is a conditional expression that fulfills the lock function when the disconnection of the self-end CT occurs as described above. The reason for this is that when the own-end CT is disconnected rather than an accident, both the own-end current rotation vector change amplitude and the both-end current rotation vector change amplitude simultaneously become large values. This is because it does not become a large value. Therefore, by using the equation (25) as an activation condition, even if the equation (13) is established, the protection activation is locked unless the equation (25) is established.

  Here, a case where three consecutive operating points enter the operating region is shown as an example, but the present invention is not limited to this example.

(Step S107)
In step S106, a circuit breaker (CB) trip signal for tripping the circuit breaker (CB) is transmitted.

(simulation result)
Next, simulation results performed on the current differential protection relay device according to the present embodiment will be described with reference to FIGS.

  FIG. 10 is a diagram showing a typical IEEJ EAST10 model system (50 Hz system) in Japan. Numbers in parentheses indicate node numbers, and numbers in <> indicate branch numbers. Now, in this model system, it is assumed that the own end device is arranged at the node 11 and the opposite end device is arranged at the node 21. The following accident case is simulated.

Case 1: A phase A ground fault of a transmission line occurs once at a point A of 50% from node 11.
Case 2: A transmission line A-phase ground fault occurs at a point B of 90% from the node 11 once.
Case 3: There is a two-time transmission line from the node 21 to the node 22, but an A-phase ground fault of the one-time transmission line occurs at the closest point C of the node 21 on the transmission line.

  FIG. 11 is a diagram showing a phase A current waveform in case 1 (phase A, ward accident 50%). As shown in FIG. 11, at the accident time (t = 0 second), it can be seen that the current rotation vector at the opposite end indicated by the broken line is reversed. That is, both currents change in opposite phases before the occurrence of the accident, but both currents change in the same phase after the occurrence of the accident.

  FIG. 12 is a diagram showing the A-phase operation characteristics in Case 1 (A-phase, 50% accident in the ward). Each straight line shown with a broken line is a boundary line which shows the boundary of each area | region shown in FIGS.

  As shown in FIG. 12, it can be seen that the amplitude of the change in the current rotation vector and the amplitude of the change in the current rotation vector increase simultaneously and the accident starts. Here, in this simulation, the third point after the operating point determined by the amplitude of the current rotation vector variation and the amplitude of the both-end current rotation vector change enters the operation region is set as the accident starting point (the following simulation). But the same). Note that the total operation time in this case is “5 ms + communication transfer time of the partner end current” when the sampling frequency of the apparatus is 600 Hz (= 50 Hz × 360 ° / 30 ° (in the case of 30 ° sampling)). Therefore, it can be said that it has high speed necessary for main protection of the transmission line.

  In the simulation results, only the A-phase operating characteristics are shown, and the B-phase operating characteristics and the C-phase operating characteristics are not shown. However, both the B-phase operating characteristics and the C-phase operating characteristics are in the dead zone region, and both are inoperative.

  FIG. 13 is a diagram showing a phase A current waveform in case 2 (A phase, 90% in the ward accident). As shown in FIG. 13, at the accident time (t = 0 second), it can be seen that the current rotation vector at the opposite end indicated by the broken line is reversed. In addition, since the accident has occurred in the near end of the other end, it can be understood that the other end current is larger than that in the case of FIG. 11 (A phase, 50% in the ward accident).

  FIG. 14 is a diagram showing the A-phase operation characteristics in Case 2 (A-phase, 90% accident in the ward). As shown in FIG. 14, it can be seen that the self-current rotation vector variation amplitude and the both-end current rotation vector variation amplitude simultaneously increase and an accident is started. In addition, since the accident has occurred in the near end of the other end, it can be understood that the slope of the straight line connecting the operating points is larger than in the case of FIG. 12 (A phase, 50% in the ward accident). Also, in the simulation results, the display of the B-phase operation characteristics and the C-phase operation characteristics is omitted, but both the B-phase operation characteristics and the C-phase operation characteristics are in the dead zone region, and both do not operate.

  FIG. 15 is a diagram showing a phase A current waveform in case 3 (phase A, out-of-city accident). Since this case is an out-of-city accident, it can be seen that no phase reversal of the current rotation vector at the other end occurs. That is, the waveforms of both currents that change in opposite phases do not change before and after the occurrence of the accident.

  FIG. 16 is a diagram showing the A-phase operation characteristics in Case 3 (A-phase, out-of-city accident). Since an out-of-city accident has occurred in this case, the amplitude of the change in the current rotation vector has a relatively large value. However, since phase inversion does not occur in the counterpart current rotation vector, the amplitude of the change in both-end current rotation vector is small. Therefore, it can be seen that the accident does not start in this case. In the simulation results, the display of the B-phase operating characteristics and the C-phase operating characteristics is omitted, but both the B-phase operating characteristics and the C-phase operating characteristics are in the dead zone, and both are inoperative.

  In the above simulation results, the A-phase ground fault accident has been described as an example, but it goes without saying that the same result can be obtained for a ground fault accident of another phase or a short-circuit accident.

  As described above, according to the current differential protection relay device according to the present embodiment, as the temporal rotation vector change amount, the current end current rotation vector at the present time and the current end current at the time one or several cycles before Changes in both ends current rotation vector, which is the difference component between the current end current rotation vector and the other end current rotation vector, as the amount of change in the end current rotation vector that is the difference component from the rotation vector and the amount of change in the spatial rotation vector Based on the amplitude of the current rotation vector change that is the amplitude of the current rotation vector change and the amplitude of the current rotation vector change that is the amplitude of the current rotation vector change. Therefore, it is possible to ensure the accuracy of the calculation for accident determination, because it is determined whether there is an accident in the protected area. It is possible to improve the reliability of the dynamic.

  In addition, since the above method is a method that uses the both-end current rotation vector change that is a spatial rotation vector change in addition to the self-end current rotation vector change that is a temporal rotation vector change, the system frequency As a result, the desired calculation accuracy can be ensured by the action of the change in the current rotation vector at both ends that is not affected by the temporal variation element that deviates from the rated frequency. In addition, due to this action, it is possible to ensure desired calculation accuracy even for a transmission line having a branch load with a large temporal variation factor.

  Further, according to the current differential protection relay device according to the present embodiment, as one of the conditions for determining an accident in the protected area, the counterpart current rotation vector calculated using the received counterpart current instantaneous value data is used. Since the information on the change amplitude is further used, the certainty of the accident start can be further improved.

  As described above, the current differential protection relay device according to the present invention ensures calculation accuracy for accident determination and improves the reliability of accident start-up even when an inexpensive communication line is used. It is useful as an invention that can

It is a figure which shows the structure of the current differential protection relay apparatus concerning one Embodiment of this invention. It is the figure which modeled the electric power grid | system containing the transmission line used as the object of accident determination. It is a figure which shows the current rotation vector when the accident in a ward occurs in a power transmission line. It is a figure which shows the electric current rotation vector when an out-of-city accident occurs. It is a graph which shows the relationship between a self-end current rotation vector change part amplitude and a both-ends current rotation vector change part amplitude. It is the figure which plotted the operating point at the time of the occurrence of a city accident on the operation characteristic diagram. It is the figure which plotted the operating point at the time of an out-of-city accident on the operation characteristic figure. It is the figure which plotted the operating point in case the disconnection generate | occur | produces in the other party CT on the operating characteristic figure. It is a flowchart which shows operation | movement of the current differential protection relay apparatus concerning this Embodiment. It is a figure which shows a typical electrical society EAST10 model system | strain (50Hz system | strain) in Japan. It is a figure which shows the A phase electric current waveform in case 1 (A phase, 50% of accidents in a ward). It is a figure which shows the A phase operation characteristic in case 1 (A phase, 50% of accidents in a ward). It is a figure which shows the A phase current waveform in case 2 (A phase, 90% of accidents in a ward). It is a figure which shows the A phase operation characteristic in case 2 (A phase, 90% of accidents in a ward). It is a figure which shows the A phase electric current waveform in case 3 (A phase, out-of-city accident). It is a figure which shows the A-phase operation characteristic in case 3 (A-phase, out-of-city accident).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Current differential protection relay apparatus 2 Self end current measurement and A / D conversion part 3 Self end current rotation vector change part calculation part (1st calculation part)
4 Counter end current time-series data receiving unit 5 Double-ended current rotation vector change calculation unit (second calculation unit)
6 Counterpart current rotation vector change calculation unit (third calculation unit)
7 Current differential protection judgment part (judgment part)
8 Circuit breaker (CB) trip command transmitter (trip command output unit)
9 Interface 10 Storage unit 11 Remote transmission unit 12 Self-end bus 13, 18 CT
14, 19 CB
15 Communication Line 16 Opposite End Device 17 Opposite End Bus 22 Transmission Line

Claims (4)

Based on the instantaneous current value data measured on the local end side of the transmission line to be protected, a change amount of the local current rotation vector, which is a change amount of the local current rotation vector, is calculated by integration calculation. A calculation unit of
Based on the other end current rotation vector and the other end current rotation vector measured using the other end current instantaneous value data measured on the other end side of the transmission line and transmitted to the other end side, A second calculation unit for calculating a change in both-end current rotation vector, which is a difference component between the own-end current rotation vector and the counterpart end-current rotation vector, by integral calculation ;
Generated in the transmission line based on the amplitude of the current rotation vector change corresponding to the amplitude of the current rotation vector change and the amplitude of the current rotation vector change corresponding to the both ends current rotation vector change. A determination unit for determining whether or not the abnormality is a protected area accident,
A trip command output unit that outputs a trip command to a circuit breaker to be controlled when the determination unit determines that an accident in a protected area;
A current differential protection relay device comprising: A first threshold amplitude (ΔI ₁₀ ) that evaluates the magnitude of the amplitude (ΔI ₁ ) of the current-end current rotation vector change;
A second threshold amplitude (ΔI ₁₂₀ ) for evaluating the magnitude of the amplitude (ΔI ₁₂ ) of the current rotation vector change amount at both ends;
A first threshold angle (α) for evaluating a ratio of the both-end current rotation vector variation amplitude to the self-current rotation vector variation amplitude;
A second threshold angle (β) for evaluating the ratio of the amplitude of the current rotation vector variation with respect to the current rotation vector variation amplitude at both ends;
Is set when
The current differential protection relay device according to claim 1, wherein the determination unit determines that an accident in the protected area has occurred when the following expression is satisfied.

A third calculation unit for calculating, by integration calculation , a counterpart end current rotation vector change, which is a change amount of a current rotation vector at the counterpart end, using the received counterpart end current instantaneous value data;
The determination unit uses, as one of the conditions for determining an accident in a protected area, information on an amplitude of the other end current rotation vector change that is an amplitude value of the other end current rotation vector change. The current differential protection relay device according to 1. A first threshold amplitude (ΔI ₁₀ ) that evaluates the magnitude of the amplitude (ΔI ₁ ) of the current-end current rotation vector change;
A second threshold amplitude (ΔI ₁₂₀ ) for evaluating the magnitude of the amplitude (ΔI ₁₂ ) of the current rotation vector change amount at both ends;
A third threshold amplitude (ΔI ₂₀ ) for evaluating the magnitude of the amplitude (ΔI ₂ ) of the counterpart current rotation vector change;
A first threshold angle (α) for evaluating a ratio of the both-end current rotation vector variation amplitude to the self-current rotation vector variation amplitude;
A second threshold angle (β) for evaluating the ratio of the amplitude of the current rotation vector variation with respect to the current rotation vector variation amplitude at both ends;
Is set when
The current differential protection relay device according to claim 3, wherein the determination unit determines that an accident in the protected area has occurred when the following expression is satisfied.

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