JP2011078292A - Disconnection protective relay device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a disconnection protective relay device, capable of protecting a three-phase AC circuit against disconnection fault with only current elements even if there is an imbalance or a branched load in each phase current. <P>SOLUTION: The disconnection protective relay device 10 for protecting a power transmission line from the disconnection faults has a current change rate computing section 14 for determining the disconnection faults based on the symmetry of current change rates R, S, T and phase change angles Δθ<SB>R</SB>, Δθ<SB>S</SB>, Δθ<SB>T</SB>of R-phase, S-phase and T-phase currents I<SB>R</SB>, I<SB>S</SB>, I<SB>T</SB>respectively flowing through R-phase, S-phase and T-phase of the power transmission line, a phase change angle computing section 15, and a relay arithmetic processor 16. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a disconnection protection relay device, and more particularly to a disconnection protection relay device suitable for protecting a three-phase AC circuit from a disconnection accident.

Conventionally, in order to protect the three-phase AC circuit from the disconnection accident, the reverse phase current I ₂ (or zero phase current I ₀ ) generated at the disconnection accident is detected, and the following four determination conditions a _{1 to} a ₄ If all of the above are satisfied, it is judged as a disconnection accident.
[Determination condition a ₁ ] The reverse phase current I ₂ is k times or more (k (reverse phase current detection sensitivity) = 10 to 20%) of the positive phase current I ₁ (generation of the reverse phase current).
[Judgment condition a ₂ ] The load current of one or two phases out of the three phases is less than the minimum load current I _min (loss of load current in the accident phase).
[Judgment condition a ₃ ] The remaining two-phase or one-phase load current of the three phases is _{equal to} or greater than the minimum load current I _min (presence of a healthy phase).
[Judgment condition a ₄ ] No zero-phase voltage V ₀ is generated (not a ground fault).

Taking a two-terminal transmission / distribution line (three-phase) as shown in FIG. 11 as an example of a three-phase AC circuit, the transmission / distribution line laid between the A end (power supply end) and the B end (load end) The disconnection protection relay device 110 is installed on the A end side, and the disconnection protection relay device 110 transmits and distributes the zero-phase voltage V ₀ inputted from the instrument transformer (GPT) 2 provided on the power source bus. R-phase, S-phase, and T-phase currents I _R input from _first to _third current transformers 3 ₁ to ₃ 3 respectively installed on the A-end side of the R-phase, S-phase, and T-phase of the electric wire, If it is determined that the disconnection accident is based on I _S and I _T as follows, the first to third circuit breakers 4 respectively installed on the A-end side of the R-phase, S-phase, and T-phase of the transmission and distribution lines. Blocks ₁ to 4 ₃ at once.

The disconnection protection relay device 110 uses the equations (1-1) and (1-2) based on the R-phase, S-phase, and T-phase currents I _R , I _S , I _T and the positive-phase current I ₁ and seeking negative sequence current I _2, respectively, reverse-phase current I ₂ always monitors whether the higher k times the positive phase current _{I 1 (I 2 ≧ kI 1} ).
I ₁ = (I _R + aI _S + a ² I _T ) / 3 (1-1)
I ₂ = (I _R + a ² I _S + aI _T ) / 3 (1-2)
Here, a (vector operator) = − ^1/2 + j × 3 ^1/2 / 2
The disconnection protection relay device 110 compares the R-phase, S-phase, and T-phase currents I _R , I _S , I _T with the minimum load current I _min (charging current), It is constantly monitoring whether only one or two of the phase currents I _R , I _S , I _T are less than the minimum load current I _min .
Furthermore, disconnection protective relay device 110 compares the zero-phase voltage V ₀ and the zero-phase voltage sensitivity V during ground fault, constantly monitors the zero-phase voltage V ₀ is a less than or zero-phase voltage sensitivity V ing.

For example, disconnection accident R-phase transmission and distribution lines are generated, through S-phase current I _S and T phase current I _T is reversed without flow R-phase current I _R as shown by the solid line in FIG. 12 (a) Therefore, as shown in FIG. 5B, assuming that the magnitudes of the R-phase, S-phase, and T-phase currents I _R ′, I _S ′, I _T ′ at normal time are the reference (= 1), the positive phase current I The magnitudes of ₁ and negative phase current I ₂ are both 0.5. As a result, if the negative-phase current detection sensitivity k = 20%, the negative-phase current I ₂ becomes k times (= 0.2 × 0.5 = 0.1) or more of the positive-phase current I _1. The electric device 110 determines that “the determination condition a ₁ is satisfied”.
Further, since only the R-phase current I _R becomes smaller than the minimum load current I _min , the disconnection protection relay device 110 determines that “the determination condition a ₂ and the determination condition a ₃ are also satisfied”.
Further, since no ground fault has occurred, the zero-phase voltage V ₀ remains lower than the zero-phase voltage detection sensitivity V, so the disconnection protection relay device 110 determines that “the determination condition a ₄ is also satisfied”. To do.
As a result, since the disconnection protection relay device 110 has satisfied all the _four determination conditions a _{1 to} a ₄ , the disconnection protection relay device 110 determines that a disconnection accident has occurred and collectively shuts off the _first to _third circuit breakers 4 ₁ to 4 _3. To do.

In Patent Document 1 below, the three-phase current of the power system is protected and relayed in order to reliably determine a one-phase disconnection regardless of load current fluctuations or current transformer differences in the digital protection relay device. The three-phase current input to the device via a current transformer, sampled through the analog input section, and digitized into a digital processing quantity is led to the arithmetic processing section to calculate the zero-phase current I ₀ , the positive-phase current I ₁ and the negative-phase current I ₂ Thus, there is disclosed a constant monitoring method in which the following formulas are satisfied and a one-phase disconnection is determined for a predetermined time.
3I ₀ / (3T ₁ + K ₀ )> K ₁ I ₁ > K ₂
3T ₀ / 3I ₁ > K ₃
Here, K ₁ and K ₃ = zero phase / positive phase set value.
K ₀ = positive phase offset amount corresponding to the analog input section error.
K ₂ = Positive phase current setting value including error in the analog input section.

JP-A-7-107653

However, in the conventional disconnection protection relay device 110, when a ground fault occurs and a ground fault current flows in each phase of the transmission and distribution line, a negative phase current I ₂ (zero phase current I _{2) having} a magnitude of 1/3. ₀ ) occurs, and all of the _three determination conditions a _{1 to} a ₃ are satisfied. Therefore, it is necessary to use the _zero- phase voltage V ₀ (voltage element) to determine that it is not a ground fault (determination condition a ₄ ). There was a problem that there was.

In addition, since the reverse phase current I ₂ generated at the time of the disconnection accident is used, there is no particular problem even if the reverse phase current detection sensitivity k is increased when each phase current of the transmission and distribution lines is balanced. When there is an unbalance in each phase current of the distribution line, there is a possibility of malfunction due to the reverse phase current I ₂ generated in the normal state, and there is a problem that the reverse phase current detection sensitivity k cannot be increased.

Further, in a three-terminal transmission / distribution line (three phases) as shown in FIG. 13, assuming that the reverse phase current detection sensitivity k is 20%, the branch load factor m on the C end (branch load end) side is less than 30%. Since it is not possible to determine a disconnection accident with a certain transmission / distribution line, it is necessary to lower the reverse-phase current detection sensitivity k for such a transmission / distribution line, but even if the reverse-phase current detection sensitivity k is reduced to 10%, There is a problem that a transmission / distribution line having a branch load factor m of less than 19% cannot be determined as a disconnection accident.
For example, if a disconnection accident occurs at a point (a point) before the branch point when viewed from the A end (power supply end) of the R phase of a three-terminal transmission and distribution line with a branch load factor m of 30%, the positive phase The magnitude of the current I ₁ is 0.850, and the magnitude of the reverse phase current I ₂ is 0.150. As a result, when the negative phase current detection sensitivity k is 20%, the negative phase current I ₂ (= 0.150) is less than k times the positive phase current I ₁ (= 0.2 × 0.850 = 0.17). And the determination condition a ₁ is not satisfied.
Therefore, when the negative-phase current detection sensitivity k is lowered to 10%, the negative-phase current I ₂ (= 0.150) is k times (= 0.1 × 0.850 = 0.085) or more of the positive-phase current I _1. since the can to satisfy the determination condition a _1, the transmission and distribution lines branching load factor m is 18%, the magnitude of the positive sequence current I ₁ is becomes 0.910, negative sequence current I ₂ Therefore, even if the negative phase current detection sensitivity k is 10%, the negative phase current I ₂ (= 0.090) is k times the positive phase current I ₁ (= 0.1 × 0). .910 = 0.091) and the determination condition a ₁ is not satisfied.

  Furthermore, in the case of a 3-terminal transmission / distribution line, a disconnection accident occurred at a point before the branch point (a point) as viewed from the A end, or a point on the B end (load end) side after the branch (b point) Therefore, there is a problem that it is impossible to determine whether a disconnection accident has occurred or whether a disconnection accident has occurred at a point on the C-end side after branching (C point).

  An object of the present invention is to provide a disconnection protection relay device that can protect a three-phase AC circuit from a disconnection accident even if there is only a current element and each phase current is unbalanced or has a branch load. There is to do.

The disconnection protection relay device of the present invention is a disconnection protection relay device (10) for protecting a three-phase AC circuit from a disconnection accident, and includes phase currents (I _R , A disconnection accident determination means (14-16) for determining a disconnection accident based only on I _S , I _T ) is provided.
Here, the disconnection accident determination means may determine a disconnection accident based on the current change rate of the phase current flowing through the healthy phase of the three-phase AC circuit and the symmetry of the phase change angle.
The disconnection accident determination means determines that the current change rate (Y) of the lagging phase current (I _Y ) of the three-phase AC circuit is multiplied by the margin (β) of the current change rate (Z) of the leading phase current (I _Z ). And the absolute value of the phase change angle (Δθ _Y ) of the delayed phase current is a value obtained by multiplying the absolute value of the phase change angle (Δθ _Z ) of the lead phase current by the tolerance. A disconnection accident may be determined on the condition that it is within the range.
In the case where the three-phase AC circuit is a three-terminal three-phase AC circuit, the disconnection accident determination means determines the phase change angle (Δθ _Y ) of the delayed phase current (I _Y ) of the three-terminal three-phase AC circuit. You may determine the point of a disconnection accident based on.

The disconnection protection relay device of the present invention has the following effects.
(1) By determining the disconnection accident based on the current change rate of the phase current flowing through the healthy phase of the three-phase AC circuit and the symmetry of the phase change angle, the current element (the phase current flowing through each phase of the three-phase AC circuit) ) Alone can protect the three-phase AC circuit from disconnection accidents.
(2) Since the disconnection accident is determined based on the current change rate that is not affected by the unbalanced current of each phase, the three-phase AC circuit can be protected from the disconnection accident even if each phase current is unbalanced. At the same time, it is not necessary to lower the detection sensitivity even if there is a branch load.
(3) By determining the location of the disconnection accident based on the phase change angle of the delayed phase current, the location of the disconnection accident in the three-terminal three-phase AC circuit can be determined.

It is a figure which shows the state which installed the disconnection protection relay apparatus 10 by one Example of this invention in the transmission / distribution electric wire of 2 terminals. I _R, R-phase S-phase and T-phase current when a disconnection fault in the R phase of transmission and distribution lines of the two-terminal phase current is balanced has occurred is a vector diagram showing the I _S, I _T. FIG. 5 is a vector diagram showing R-phase, S-phase, and T-phase currents I _R , I _S , I _T in a two-terminal transmission / distribution line in which each phase current is unbalanced, and FIG. FIG. 6 is a vector diagram showing phase and T phase currents I _R ′, I _S ′, and I _T ′, and (b) shows R phase, S phase, and T phase currents I _R , I when a disconnection accident occurs in the R phase. _S, is a vector diagram showing the I _T. It is a block diagram which shows the specific structural example of the disconnection protection relay apparatus 10 shown in FIG. It is a flowchart for demonstrating the disconnection determination processing method in the relay arithmetic processing part 16 shown in FIG. It is a figure which shows the state which installed the disconnection protection relay apparatus 10 by one Example of this invention in the transmission / distribution electric wire of 3 terminals. FIG. 5 is a vector diagram showing R-phase S-phase and T-phase currents I _R , I _S , I _T when a disconnection accident occurs in the R-phase of a three-terminal transmission and distribution line in which each phase current is balanced; FIG. 7 is a vector diagram showing R-phase S-phase and T-phase currents I _R , I _S , I _T when a disconnection accident occurs at point B shown in FIG. 6, and (b) is a disconnection at point C shown in FIG. It is a vector diagram showing R phase S phase and T phase currents I _R , I _S , I _T when an accident occurs. It is a flowchart for demonstrating the disconnection determination processing method in the relay arithmetic processing part 16 shown in FIG. 4 when a disconnection accident generate | occur | produces in the transmission / distribution line of 3 terminals with which each phase current is balanced. FIG. 7 is a vector diagram showing R-phase S-phase and T-phase currents I _R , I _S , I _T when a disconnection accident occurs in the R-phase of a three-terminal transmission / distribution line in which each phase current is unbalanced; ) Is a vector diagram showing R-phase S-phase and T-phase currents I _R , I _S , I _T when a disconnection accident occurs at point B shown in FIG. 6, and (b) is a point C shown in FIG. R phase S phase and T-phase currents I _R when the disconnection accident occurs, I _S, is a vector diagram showing the I _T. It is a flowchart for demonstrating the disconnection determination processing method in the relay arithmetic processing part 16 shown in FIG. 4 when a disconnection accident generate | occur | produces with the transmission / distribution line of 3 terminals where each phase current is unbalanced. It is a figure for demonstrating the conventional disconnection protection relay apparatus 110. FIG. It is a figure for demonstrating operation | movement of the disconnection protection relay apparatus 110 when a disconnection accident generate | occur | produces in the R phase of the power transmission and distribution line shown in FIG. It is a figure for demonstrating a problem when the disconnection protection relay apparatus 110 shown in FIG. 11 is used for a 3-terminal power transmission and distribution line.

  The above object has been realized by determining the disconnection accident based on the current change rate of the phase current flowing through the healthy phase of the three-phase AC circuit and the symmetry of the phase change angle.

Embodiments of the disconnection protection relay device of the present invention will be described below with reference to the drawings.
In the following explanation,
(1) The phase θ _{R of the} normal R-phase current I _R ′ with the magnitudes of the normal R-phase, S-phase, and T-phase currents I _R ′, I _S ′, I _T ′ as the reference (= 1) 'Is the reference (= 0 °).
(2) The rate of current change with respect to the R-phase, S-phase, and T-phase currents I _R ′, I _S ′, I _T ′ when the R-phase, S-phase, and T-phase currents I _R , I _S , I _T are normal. (= | I _R | / | I _R '|), S (= | I _S | / | I _S ' |) and T (= | I _T | / | I _T '|), R phase, S phase and T-phase currents I _R, I _S, the phase theta _R of I _T, θ _S, normal state R-phase theta _T, S-phase and T-phase currents I _R ', I _S', the phase theta _R of I _T ' The phase change angles for ', θ _S ', and θ _T 'are Δθ _R (= θ _R −θ _R '), Δθ _S (= θ _S −θ _S '), Δθ _T (= θ _T −θ _T '). To do.
(3) The phase current flowing through the accident phase X where the disconnection accident occurred is defined as the accident phase current I _X , the phase current flowing through the delay phase Y with respect to the accident phase X is defined as the delay phase current I _Y, and A phase current flowing through the leading phase _Z is _defined as a leading phase current I _Z. Further, the rate of change of current with respect to the accident phase, delay phase, and lead phase currents I _X ′, I _Y ′, I _Z ′ of the fault phase, delay phase, and lead phase currents I _X , I _Y , I _Z when normal is represented by X ( = | I _X | / | I _X '|), Y (= | I _Y | / | I _Y ' |), and Z (= | I _Z | / | I _Z '|) and proceeds phase currents I _X, I _Y, the phase theta _X of I _Z, θ _Y, fault phase during normal theta _Z, lag phase and proceeds phase currents I _X ', I _Y', the phase theta _X of I _Z ' The phase change angles for ', θ _Y ', and θ _Z 'are Δθ _X (= θ _X −θ _X '), Δθ _Y (= θ _Y −θ _Y '), Δθ _Z (= θ _Z −θ _Z '). To do.
(4) The first tolerance α = 0.2, the second tolerance β = 0.9 to 1.1, the third tolerance γ = −10 ° to 10 °, and the fourth tolerance The degree δ = 0.9 and the fifth tolerance ε = 1.1.
(5) For a 3-terminal transmission and distribution line, the load at the A end (power supply end) is 100%, the branch load factor at the B end (load end) is (100-m)%, and the C end (branch load end) The branch load factor of is m%.
(6) The B-side R-phase, S-phase, and T-phase currents I _BR , I _BS , I Let _BT be the phase current flowing on the C end side from the branch point, and let the C end side R phase, S phase, and T phase currents I _CR , I _CS , and I _CT .
(7) When the phase currents of the two-terminal transmission and distribution lines are unbalanced, the normal S-phase and T-phase currents I _S ′ and I _T with respect to the normal R-phase current I _R ′ The ratio of the magnitudes of 'is assumed to be the S-phase and T-phase unbalance ratio n _S (= | I _S ' | / | I _R '|), n _T (= | I _T ' | / | I _R '|) .
(8) When the phase currents of the 3-terminal transmission and distribution lines are unbalanced, the B-end side S-phase and T-phase currents in the normal state with respect to the magnitude of the B-end side R-phase current I _BR ′ in the normal state I _BS ', I _BT' size ratio of the B-end side S-phase and T-phase unbalanced ratio _{n BS (= | I BS '} | / | I BR' |), n BT (= | I BT '| / | I _BR '|), and the ratio of the magnitude of the C-terminal side S-phase current and the T-phase current I _CS ′, I _CT ′ to the magnitude of the normal C-terminal side R-phase current I _CR ′ The C-side S-phase and T-phase unbalance ratios n _CS (= | I _CS '| / | I _CR ' |), n _CT (= | I _CT '| / | I _CR ' |).
(9) The sixth tolerance ζ = 1 / (n _CS + n _CT ) to (n _CS + n _CT ).

  The disconnection protection relay device of the present invention has a symmetrical change in the magnitude and phase of the phase current flowing through the healthy phase in the event of a disconnection accident (the current change rate and the absolute value of the phase change angle during the fault / normal phase of the healthy phase) It is characterized in that a disconnection accident is determined only by a current element by determining a disconnection accident by paying attention to a change in which the two are the same.

Next, the case where the disconnection protection relay device 10 according to one embodiment of the present invention is used for a two-terminal transmission / distribution line (three phases) as shown in FIG. 1 will be described with reference to FIGS. .
If each phase current of the 2-terminal transmission / distribution line is balanced, if a disconnection accident occurs in the R-phase of this transmission / distribution line, the R-phase current I _R, which is the phase current flowing through the accident phase, becomes 0, a phase current flowing through the sound phase S-phase and T-phase current I _S, the rate of change of current I _T S, T are both 3 ^1/2 / 2, of the S-phase current I _S phase theta _S is the normal S-phase current I _S 30 ° advances against 'phase theta _S' of the phase theta _T T-phase current I _T is delayed 30 ° with respect to 'the phase theta _T of' normal state T phase current I _T.

Also, as shown in FIG. 3 (a), when each phase current of the two-terminal transmission / distribution line is unbalanced, if a disconnection accident occurs in the R-phase of this transmission / distribution line, as shown by the solid line, the R-phase current I _R becomes 0, S-phase and T-phase current I _S, the rate of change of current I _T S, T are both in ^{_{3 1/2 (n S + n T}} ) / 4 , S-phase current I phase theta _S of _S advances 30 ° with respect to 'the phase theta _S of' S-phase current I _S during normal, T-phase current I _T of the phase theta _T is in a normal T-phase current I _T Delayed by 30 ° with respect to 'phase θ _T '.

Therefore, the disconnection protection relay device 10 is considered to be a disconnection accident when all of the following four determination conditions A to D defined using the first to third tolerances α, β, and γ are satisfied. judge.
[Criteria A] The current change rate X of the accident phase current I _X is not more than the first tolerance α.
[Criteria B] The current change rate _Y of the delayed phase current I _Y is within the range of 3 ^1/2 (n _S + n _T ) / 4 multiplied by the second tolerance β, and the delayed phase current The absolute value of the phase change angle Δθ _Y of I _Y is within the range of the third tolerance γ with 30 ° as the center.
[Criteria C] The rate of change Z of the leading phase current I _Z is within the range of 3 ^1/2 (n _S + n _T ) / 4 multiplied by the second tolerance β, and the leading phase current The absolute value of the phase change angle Δθ _Z (= θ _Z −θ _Z ′) of I _Z is within the range of the third tolerance γ with 30 ° as the center.
Is in the range of [the determination condition D] late-phase current I obtained by multiplying the second margin β to the current change rate Z of current change rate Y advances phase current I _Z of _Y, and late-phase current I _Y The absolute value of the phase change angle Δθ _Y is within the range of the value obtained by multiplying the absolute value of the phase change angle Δθ _Z of the phase current I _Z by the second tolerance β.

Next, a specific configuration example of the disconnection protection relay device 10 will be described with reference to FIG.
As shown in FIG. 4, the disconnection protection relay device 10 includes an input converter 11, an analog input unit 12, a memory 13, a current change rate calculation unit 14, a phase change angle calculation unit 15, and a relay calculation process. Unit 16, settling / display unit 17, input / output unit 18, and external device interface unit (external device I / F unit) 19.

The input converter 11 determines the levels of the R-phase, S-phase, and T-phase currents I _R , I _S , and I _T respectively input from the _first to _third current transformers 3 _{1 to} 3 ₃ (see FIG. 1). The level is converted to a level suitable for processing of the analog input unit 12. For simplicity of explanation, the current transformation ratio of the first to _third current transformers 3 _{1 to} 3 ₃ is 1: 1.
The analog input unit 12 includes a bandpass filter, a sampling hold circuit, a multiplexer circuit, and an analog / digital converter, and analog R-phase, S-phase, and T-phase currents I _R and I _S input from the input converter 11. , I _T are converted into digital R-phase, S-phase and T-phase currents I _R , I _S , I _T.
The memory 13 is for storing the R-phase, S-phase, and T-phase currents I _R , I _S , I _T converted into digital data by the analog input unit 12.

The current change rate calculation unit 14 stores the magnitudes of the R-phase, S-phase, and T-phase currents I _R , I _S , and I _T input from the analog input unit 12 in the memory 13 one cycle before the R-phase. , S-phase and T-phase currents I _R , I _S , and I _T.
Thereby, at the time of a disconnection accident, the current change rate calculation unit 14 sets the magnitudes of the R phase, S phase, and T phase currents I _R , I _S , I _T to the R phase, S phase, and T phase currents I one cycle before. By dividing by the magnitudes of _{R 1} , I _S , I _T (ie, normal R phase, S phase and T phase currents I _R ′, I _S ′, I _T ′), R phase, S phase and T phase current I _R, I _S, the rate of change of current I _T R, S, to calculate the T.

The phase change angle calculation unit 15 is stored in the memory 13 from the phases θ _R , θ _S , θ _{T of the} R-phase, S-phase, and T-phase currents I _R , I _S , I _T input from the analog input unit 12. The phases θ _R , θ _S , and θ _T of the R-phase, S-phase, and T-phase currents I _R , I _S , and I _T one cycle before are subtracted.
Thus, in the event of a disconnection accident, the phase change angle calculation unit 15 causes the R phase one cycle before the phases θ _R , θ _S , θ _T of the R phase, S phase, and T phase currents I _R , I _S , I _T , Phases θ _R , θ _S , θ _{T of} S phase and T phase currents I _R , I _S , I _T (ie, normal R phase, S phase and T phase currents I _R ′, I _S ′, I _T ′) phase θ _R ', θ _S', by subtracting the theta _T '), R phase, S phase and T-phase currents I _R, I _S, the phase change angle [Delta] [theta] _R of I _T, [Delta] [theta] _S, calculates the [Delta] [theta] _T To do.

The relay calculation processing unit 16 is based on the current change rates R, S, T calculated by the current change rate calculating unit 14 and the phase change angles Δθ _R , Δθ _S , Δθ _T calculated by the phase change angle calculating unit 15. Then, it is determined whether or not there is a disconnection accident by performing a disconnection determination process to be described later, and if it is determined that the disconnection accident occurs, a trip signal T is generated to collectively disconnect the _first to _third circuit breakers 4 ₁ to 4 _3. The generated trip signal T is output to the _first to _third circuit breakers 4 ₁ to 4 ₃ via the input / output unit 18 and the external device interface unit 19.

  The settling / display unit 17 performs relay settling processing and displays the settling value and the like to the outside.

  Next, the disconnection determination processing method in the relay calculation processing unit 16 of the disconnection protection relay device 10 will be described with reference to the flowchart shown in FIG.

Relay processing section 16, R phase, S phase and T-phase currents I _R, I _S, the fault phase currents to investigate whether the rate of change of current I _T R, S, T is there is less than 0.2 A determination process is performed (step S11).
As a result, when there is a corresponding phase current, the relay calculation processing unit 16 sets the corresponding phase as the accident phase X.

If the result in step S11 is "YES", the relay processing unit 16, it is determined that the determination condition A is satisfied, a delay phase current I current change rate Y of _Y is 3 ^1/2 (n _S + N _T ) / 4 multiplied by 0.9 to 1.1, and the absolute value of the phase change angle Δθ _Y of the delayed phase current I _Y is −10 ° to 10 centered on 30 ° A delayed phase current determination process is performed to check whether or not the angle is within the range of ° (step S12).

In that case the result is "YES", the relay processing unit 16, it is determined that the determination condition B is satisfied, the current change rate Z of the advance phase current I _Z is 3 ^1/2 (n _S + n _T ) / 4 multiplied by 0.9 to 1.1, and the absolute value of the phase change angle Δθ _Z of the leading phase current I _Z is within a range of −10 ° to 10 ° centering on 30 °. A lead phase current determination process is performed to check whether or not the current is in the range (step S13).

When the result is “YES”, the relay calculation processing unit 16 determines that the determination condition C is satisfied, and the current change rate Y of the delayed phase current I _{Y is} the current change rate of the advanced phase current I _Z. Whether Z is within a range of 0.9 to 1.1 is checked, and the absolute value of the phase change angle Δθ _Y of the delayed phase current I _Y is advanced, and the phase change angle Δθ of the phase current I _Z is Delayed phase / leading phase current symmetry determination processing is performed to determine whether the absolute value of _Z is within a range of values obtained by multiplying 0.9 to 1.1. (Step S14).

  When the result is “YES”, it is determined that the determination condition D is satisfied, and the relay calculation processing unit 16 determines that a disconnection accident has occurred in the accident phase X (step S15).

  Thereby, even if it is only an electric current element and there is an imbalance in each phase current, it is possible to protect the two-terminal transmission and distribution line from a disconnection accident.

  Next, the case where the disconnection protection relay device 10 is used for a three-terminal transmission / distribution line (three phases) as shown in FIG. 6 will be described with reference to FIGS.

When each phase current of the 3-terminal transmission / distribution line is balanced, for example, when a disconnection accident occurs at a point (a point) before the branch point when viewed from the A-phase end of the R-phase of this transmission / distribution line, in the same manner as when a disconnection in the R phase the transmission and distribution lines of the two-terminal described above accident occurs, the R-phase current I _R becomes 0, S-phase and T-phase current I _S, the rate of change of current I _T S, T becomes both the 3 ^1/2 / 2, S-phase current I phase theta _S of _S advances 30 ° with respect to 'the phase theta _S of' S-phase current I _S of the normal, the T-phase current I _T phase θ _T is delayed by 30 ° with respect to the phase θ _T ′ of the normal T-phase current I _T ′.

In addition, when a disconnection accident occurs at a point (B point) on the B end side of the branch point when viewed from the A end of the R phase of the transmission and distribution line, the B end side R phase, S phase and T phase currents I _BR , I _BS , I _BT and C-terminal side R-phase, S-phase and T-phase currents I _CR , I _CS , I _CT are expressed by equations (2-1) to (2-6).
I _BR = 0 (2-1)
I _BS = (100−m) / 100 (2-2)
I _BT = (100-m) / 100 (2-3)
I _CR = m / 100 (2-4)
I _CS = m / 100 (2-5)
I _CT = m / 100 (2-6)
Thus, R phase, S phase and T-phase currents I _R, I _S, the rate of change of current I _T R, S, T and the phase change angle Δθ _R, Δθ _S, Δθ _T is (3-1) to (3 −6) It is expressed by the formula (see FIG. 7A).
R = m / 100 (3-1)
Δθ _R = 0 ° (3-2)
S = {(100−m) / 100} ∠120 ° + (m / 100) ∠90 °
= [(3 ^1/2 / 2) ² + {(100-m) / 200} ² ] ^1/2 (3-3)
Δθ _S = −30 ° + tan [{(100−m) / 200} / (3 ^1/2 / 2)]
= −30 ° + tan {(100−m) / (3 ^1/2 × 100)} (3-4)
T = {(100−m) / 100} ∠ (−120 °) + (m / 100) ∠ (−90 °)
= [(3 ^1/2 / 2) ² + {(100-m) / 200} ² ] ^1/2 (3-5)
Δθ _T = 30 ° −tan [{(100−m) / 200} / (3 ^1/2 / 2)]
= 30 ° -tan {(100-m) / (3 ^1/2 × 100)} (3-6)

Furthermore, when a disconnection accident occurs at a point (C point) on the C end side of the branch point as viewed from the A end of the R phase of this transmission and distribution line, the B end side R phase current I _BR and the C end side R phase current I _CR is expressed by the equations (4-1) and (4-2), and the B-terminal side S-phase and T-phase currents I _BS and I _BT and the C-terminal side S-phase and T-phase currents I _CS and I _CT Is represented by the above formulas (2-3) to (2-6).
I _BR = (100−m) / 100 (4-1)
I _CR = 0 (4-3)
Accordingly, the current rate of change of the R-phase current I _R R is represented by (5-1) equation, S-phase and T-phase current I _S, the rate of change of current I _T S, T and R phase S phase and T-phase current The phase change angles Δθ _R , Δθ _S , and Δθ _{T of} I _R , I _S , and I _T are expressed by the above expressions (3-2) to (3-6) (see FIG. 7B).
R = (100-m) / 100 (5-1)

Therefore, the disconnection protection relay device 10 determines that a disconnection accident occurs when all of the following four determination conditions A ′ to D ′ defined using the second and fourth tolerances β and δ are satisfied. judge.
[Determination Conditions A '] fault phase currents I _X of the current change rate X is (100-m) / 100 be less.
[Judgment condition B ′] Current change rate _Y of delayed phase current I _Y is changed from [(3 ^1/2 / 2) ² + {(100−m) / 200} ² ] ^1/2 to (3 ^1/2 / 2 ) to in the range of up to the value obtained by multiplying the fourth margin [delta], and the phase change angle [Delta] [theta] _Y of the delay phase current I _Y is -30 ° + tan {(100- m) / (3 1/2 × 100)} or less.
[Criteria C ′] Current change rate _Z of lead phase current I _Z is changed from [(3 ^1/2 / 2) ² + {(100−m) / 200} ² ] ^1/2 to (3 ^1/2 / 2 ) to in the range of up to the value obtained by multiplying the fourth margin [delta], and the phase change angle [Delta] [theta] _Z of the advance phase current I _Z phase theta _Z is 30 ° -tan {(100-m ) / (3 ^1/2 × 100)} or more.
Is in the range of [Determination Conditions D '] late phase current I obtained by multiplying the second margin β to the current change rate Z of current change rate Y advances phase current I _Z of _Y, and late-phase current I lying within the range of values obtained by multiplying the second margin β to the absolute value of the phase change angle [Delta] [theta] _Z of the absolute value advances phase current I _Z phase change angle [Delta] [theta] _Y of the _Y.

Further, the disconnection protection relay device 10 uses the second, fourth, and fifth tolerances β, δ, ε to determine the point of the disconnection accident as follows.
(1) determined that when the phase change angle [Delta] [theta] _Y of the delay phase current I _Y is within the range of values obtained by multiplying the second margin β in -30 °, the disconnection accident occurred at a point before the branch To do.
(2) a delay phase current I _Y phase change angle [Delta] [theta] _Y is -30 ° to less than 4 and greater than a value obtained by multiplying the tolerance δ of -13.9 ° to multiplied by the fifth tolerance ε values of If it is, it is determined that a disconnection accident has occurred at the point on the B end side after branching.
(3) delay of phase current I phase shift angle [Delta] [theta] _{Y Y} is -13.9 ° in the fourth margin δ the multiplied greatly and -30 ° than the value + tan {(100-m) / (3 1 / ² <100)}, it is determined that a disconnection accident has occurred at the point on the C-end side after the branch.
(4) When the phase change angle [Delta] [theta] _Y of the delay phase current I _Y is within the range of values obtained by multiplying the second margin β in -13.9 °, the branch after the B-end side or C-terminal It is determined that a disconnection accident has occurred at that point.

  Next, the disconnection determination processing method in the relay calculation processing unit 16 of the disconnection protection relay device 10 in this case will be described with reference to the flowchart shown in FIG.

Relay processing section 16, R phase, S phase and T-phase currents I _R, I _S, the rate of change of current I _T R, S, whether T there is a (100-m) / 100 following ones A fault phase current determination process is performed (step S21).
As a result, when there is a corresponding phase current, the relay calculation processing unit 16 sets the corresponding phase as the accident phase X.

If the result at step S21 is "YES", the relay processing unit 16, it is determined that the determination condition A 'is satisfied, the current change rate Y of the delay phase current I _Y is [(3 ^1/2 / 2) ² + {(100−m) / 200} ² ] ^1/2 to (3 ^1/2 / 2) multiplied by 0.9 (= 0.78), and , the phase change angle [Delta] [theta] _Y of the delay phase current I _Y makes a -30 ° + tan {(100- m) / (3 1/2 × 100)} lag phase current determination process checks if it is less (step S22).

In that case the result is "YES", the relay processing unit 16, it is determined that the determination condition B 'are met, the current change rate of the advance phase current I _Z Z is [(3 ^1/2 / 2 ) ² + is in {(100-m) / 200 } 2] value multiplied by 0.9 to ^1/2 (3 ^1/2 / 2) (= 0.78) in the range up to, and proceeds phase current I _Z phase theta _Z of the phase change angle [Delta] [theta] _Z performs 30 ° -tan {(100-m ) / (3 1/2 × 100)} examined by whether or advances phase current determination process (Step S23).

When the result is “YES”, the relay calculation processing unit 16 determines that the determination condition C ′ is satisfied, and the current change rate Y of the delayed phase current I _Y increases and the current change of the advanced phase current I _Z. The absolute value of the phase change angle Δθ _Y of the delayed phase current I _Y is within the range of the value obtained by multiplying the rate Z by 0.9 to 1.1, and the absolute value of the phase change angle Δθ _Z of the lead phase current I _Z Delayed phase / leading phase current symmetry determination processing is performed to check whether the value is within a range of values obtained by multiplying 0.9 to 1.1. (Step S24).

When the result is “YES”, it is determined that the determination condition D ′ is satisfied, and the relay calculation processing unit 16 examines the phase change angle Δθ _Y of the delayed phase current I _Y , and according to the result. The point where the disconnection accident occurred is determined as follows.
(1) a delay phase current I _Y of the phase change angle [Delta] [theta] _Y is within the range of values obtained by multiplying the 0.9 to 1.1 to -30 ° (= -27 ° ~- 33 °) ( i.e., -33 (° ≦ Δθ _Y ≦ −27 °), it is determined that a disconnection accident has occurred at a point before branching (steps S25 and S29a).
(2) a delay phase current I value phase shift angle [Delta] [theta] _Y is multiplied by 0.9 to -30 ° for _Y (= -27 °) and greater than -13.9 value obtained by multiplying 1.1 ° ( = −15.3 °) (ie, −27 ° <Δθ _Y <−15.3 °), it is determined that a disconnection accident has occurred at the point on the B-end side after branching (step S26, S29b).
(3) The value phase shift angle [Delta] [theta] _Y of the delay phase current I _Y is multiplied by 0.9 to -13.9 ° (= -12.5 °) greater than and -30 ° + tan {(100- m) / (3 ^1/2 × 100)}, it is determined that a disconnection accident has occurred at a point on the C-end side after branching (steps S27 and S29c).
(4) a phase change angle [Delta] [theta] _Y of the delay phase current I _Y is within a range of values multiplied by 0.9 to 1.1 to -13.9 ° (-12.5 ° ~-15.3 °) In the case of (that is, −15.3 ° ≦ Δθ _Y ≦ −12.5 °), it is determined that a disconnection accident has occurred at a point on the B end side or the C end side after branching (steps S28 and S29d).

  Thereby, the transmission / distribution line of 3 terminals can be protected from a disconnection accident with only the current element.

If each phase current of the 3-terminal transmission / distribution line is unbalanced, if a disconnection accident occurs at a point (a point) before the branch point when viewed from the A-phase end of the R-phase of this transmission / distribution line, The R-phase current I _R becomes 0, and the S-phase and T-phase currents I _{S in the same} manner as when the disconnection accident occurs in the R-phase when the phase currents of the three-terminal transmission and distribution lines are balanced. , the rate of change of current I _T S, T are both the 3 ^1/2 / 2, 30 ° with respect to 'the phase theta _S of' S-phase current I _S of the phase theta _S is S-phase current I _S during normal It advances the phase theta _T T-phase current I _T is delayed 30 ° with respect to 'the phase theta _T of' normal state T phase current I _T.

B-terminal side R-phase, S-phase and T-phase currents I _BR ', I _BS ', I _BT 'in normal state and C-terminal side R-phase, S-phase and T-phase currents I _CR ', I _CS ', I _CT ′ is expressed by equations (6-1) to (6-6).
I _BR '= (100-m) / 100 (6-1)
I _BS ′ = {(100−m) / 100} × n _BS (6-2)
I _BT ′ = {(100−m) / 100} × n _BT (6-3)
I _CR '= m / 100 (6-4)
I _CS '= (m / 100) × n _CS (6-5)
I _CT '= (m / 100) × n _CT (6-6)
Therefore, the normal R-phase, S-phase, and T-phase currents I _R ′, I _S ′, and I _T ′ are expressed by equations (6-7) to (6-9).
I _R ′ = (100−m) / 100 + m / 100 = 1 (6-7)
I _S ′ = {(100−m) / 100} × n _BS + {m / 100} × n _CS (6-8)
I _T ′ = {(100−m) / 100} × n _BT + {m / 100} × n _CT (6-9)

In addition, when a disconnection accident occurs at a point (B point) on the B end side of the branch point when viewed from the A end of the R phase of the transmission and distribution line, the B end side R phase, S phase and T phase currents I _BR , I _BS and I _BT and the C-terminal side R-phase, S-phase and T-phase currents I _CR , I _CS and I _CT are expressed by equations (7-1) to (7-6).
I _BR = 0 (7-1)
I _BS = {(100−m) / 100} × n _BS (7-2)
I _BT = {(100−m) / 100} × n _BT (7-3)
I _CR = m / 100 (7-4)
I _CS = {(I _CS '+ IC _T ') / 2} × (3 ^1/2 / 2)
= [{(M / 100) × n _CS + (m / 100) × n _CT } / 2] × (3 ^1/2 / 2)
= {(3 ^1/2 × m) / 200} × {(n _CS + n _CT ) / 2} (7-5)
I _CT = {(I _CS '+ IC _T ') / 2} × (3 ^1/2 / 2)
= {(3 ^1/2 × m) / 200} × {(n _CS + n _CT ) / 2} (7-6)
At this time, the current change rate R of the R phase current I _R and the R phase current I _R , the phase change angle Δθ _{S of the} S phase current I _S and the S phase current I _S , the T phase current I _T and the T phase current I _T phase. The change angle Δθ _T is expressed by equations (8-1) to (8-6) (see FIG. 9A).
I _R = I _BR + I _CR = 0 + m / 100 = m / 100 (8-1)
R = I _R / I _R '= (m / 100) / 1 = m / 100 (8-2)
I _S = I _BS ∠120 ° + I _CS ∠90 °
= (I _BS ² + I _CS ² −2 × I _BS × I _CS × cos 150 °) ^1/2 (8-3)
Δθ _S = −sin ⁻¹ {(I _CS × sin 150 °) / I _S } (8-4)
I _T = I _BT ∠120 ° + I _CT ∠90 °
^{_{= (I BT 2 + I CT}} 2 -2 × I BT × I CT × cos150 °) 1/2 (8-5)
^{_{Δθ T = sin -1 {(I}} CT × sin150 °) / I T} (8-6)

Furthermore, when a disconnection accident occurs at a point (C point) on the C end side of the branch point as viewed from the A end of the R phase of this transmission and distribution line, the B end side R phase current I _BR and the C end side R phase current I _CR is expressed by the formulas (9-1) and (9-2), and the B-terminal side S-phase and T-phase currents I _BS and I _BT and the C-terminal side S-phase and T-phase currents I _CS and I _CT. Is represented by the above formulas (7-2), (7-3), (7-5) and (7-6).
I _BR = (100−m) / 100 (9-1)
I _CR = 0 (9-2)
The current change rate R of the R phase current I _R and the R phase current I _R at this time is expressed by the equations (10-1) and (10-2), and the phase of the S phase current I _S and the S phase current I _S. The change angle Δθ _S , the T phase current I _T, and the T phase current I _T phase change angle Δθ _T are expressed by the above equations (8-2) to (8-6) (see FIG. 9B).
I _R = I _BR + I _CR = (100−m) / 100 (10−1)
_{R = I R / I R '} = {(100-m) / 100} / 1 = (100-m) / 100 (10-2)

Therefore, the disconnection protection relay device 10 determines that a disconnection accident occurs when all of the following four determination conditions A ″ to D ″ defined using the second and sixth tolerances β and ζ are satisfied. judge.
[Determination Conditions A "] fault phase currents I _X of the current change rate X is (100-m) / 100 be less.
[Judgment condition B ″] The magnitude of the C-side delayed phase current I _CY is {(3 ^1/2 × m) / 200} × {(n _CS + n _CT ) / 2} or more, and the delayed phase current phase shift angle [Delta] [theta] _Y of I _Y is _{^{-sin -1 {(I CS × sin150}} °) / I S} or less.
[Criteria C ″] The C-terminal side leading phase current I _CZ is {(3 ^1/2 × m) / 200} × {(n _CS + n _CT ) / 2} or more, and the leading phase current I _Z phase theta _Z of the phase change angle [Delta] [theta] _Z is _{^{sin -1 {(I CT × sin150}} °) / I T} or that it is.
[Determination Condition D ″] The magnitude of the C-side delayed phase current I _{CY is in the range} of the magnitude of the C-side advanced phase current I _CZ multiplied by the second tolerance β, and the delayed phase current I lying within the range of values obtained by multiplying the sixth tolerance ζ of the absolute value of the phase change angle [Delta] [theta] _Z of the absolute value advances phase current I _Z phase change angle [Delta] [theta] _Y of the _Y.

Further, the disconnection protection relay device 10 includes the second tolerance β and the first reference angle θ ₁ (−sin ⁻¹ {(I _CS × sin 150 °) / I when the branch load factor m = 50%). _S } value) and the second reference angle θ ₂ (branch load factor m = 50%, B-end S-phase and T-phase imbalance are 1 / n _BS and 1 / n _BT , and C-end S-phase and Using -sin ⁻¹ {(I _CS × sin 150 °) / I _S }) when the T-phase unbalance rate is 1 / n _CS and 1 / n _CT , a disconnection accident is performed as follows. Determine the point.
(1) determined that when the phase change angle [Delta] [theta] _Y of the delay phase current I _Y is within the range of values obtained by multiplying the second margin β in -30 °, the disconnection accident occurred at a point before the branch To do.
(2) When the phase change angle Δθ _Y of the delayed phase current I _Y is less than the first reference angle θ _1, it is determined that a disconnection accident has occurred at a point on the B end side after branching.
(3) When the phase change angle Δθ _Y of the delayed phase current I _Y is equal to or greater than the second reference angle θ _2, it is determined that a disconnection accident has occurred at a point on the C-end side after branching.
(4) When the phase change angle Δθ _Y of the delayed phase current I _Y is within the range from the _first reference angle θ ₁ to the second reference angle θ ₂ , It is determined that a disconnection accident has occurred at that point.

  Next, the disconnection determination processing method in the relay calculation processing unit 16 of the disconnection protection relay device 10 in this case will be described with reference to the flowchart shown in FIG.

Relay processing section 16, R phase, S phase and T-phase currents I _R, I _S, the rate of change of current I _T R, S, whether T there is a (100-m) / 100 following ones A fault phase current determination process is performed (step S31).
As a result, when there is a corresponding phase current, the relay calculation processing unit 16 sets the corresponding phase as the accident phase X.

When the result in step S31 is “YES”, the relay calculation processing unit 16 determines that the determination condition A ”is satisfied, and the magnitude of the C-terminal delayed phase current I _CY is {(3 ^{1 / 2} × m) / 200} is a _{× {(n CS + n CT} ) / 2} or more, and, the phase change angle [Delta] [theta] _Y of the delay phase current I _Y is _{^{-sin -1 {(I CS × sin150}} °) / I _S } A delayed phase current determination process is performed to check whether or not it is less than or equal to (step S32).

When the result is “YES”, the relay calculation processing unit 16 determines that the determination condition B ”is satisfied, and the magnitude of the C-terminal side advanced phase current I _CZ is {(3 ^1/2 × m) / 200} × {( n CS + n CT) / 2} or more, and, the phase change angle [Delta] [theta] _Z of the advance phase current I _Z phase theta _Z is _{^{sin -1 {(I CT × sin150}} °) / I _T } is performed to determine whether or not the advanced phase current is determined (step S33).

When the result is “YES”, the relay calculation processing unit 16 determines that the determination condition C ”is satisfied, and the magnitude of the C-side delayed phase current I _CY is equal to the C-side advanced phase current I _CZ . The magnitude is within a range of 0.9 to 1.1, and the absolute value of the phase change angle Δθ _Y of the delayed phase current I _Y is the absolute value of the phase change angle Δθ _Z of the lead phase current I _Z. Delayed phase / leading phase current symmetry determination processing is performed to determine whether or not the value is within a range of values multiplied by 1 / (n _CS + n _CT ) to (n _CS + n _CT ) (step S34).

When the result is “YES”, it is determined that the determination condition D ”is satisfied, and the relay calculation processing unit 16 examines the phase change angle Δθ _Y of the delayed phase current I _Y , and according to the result. The point where the disconnection accident occurred is determined as follows.
(1) a delay phase current I _Y of the phase change angle [Delta] [theta] _Y is within the range of values obtained by multiplying the 0.9 to 1.1 to -30 ° (= -27 ° ~- 33 °) ( i.e., -33 (° ≦ Δθ _Y ≦ −27 °), it is determined that a disconnection accident has occurred at a point before branching (steps S35 and S39a).
(2) When the phase change angle Δθ _Y of the delayed phase current I _Y is less than the first reference angle θ _1, it is determined that a disconnection accident has occurred at a point on the B-end side after branching (steps S36 and S39b). ).
(3) When the phase change angle Δθ _Y of the delayed phase current I _Y is equal to or greater than the second reference angle θ _2, it is determined that a disconnection accident has occurred at a point on the C-end side after branching (steps S37 and S39c). ).
(4) When the phase change angle Δθ _Y of the delayed phase current I _Y is within the range from the _first reference angle θ ₁ to the second reference angle θ ₂ , It is determined that a disconnection accident has occurred at the point (steps S38 and S39d).

  Thereby, even if it has only an electric current element and each phase current has imbalance, it can protect a 3-terminal transmission and distribution line from a disconnection accident.

1 Power supply 2 Instrument transformer (GPT)
3 ₁ to ₃ 3 _1st to _3rd current transformers 4 ₁ to 4 _{3 1st} to _3rd circuit breakers 10 and 110 Disconnection protection relay device 11 Input converter 12 Analog input unit 13 Memory 14 Current change rate calculation Unit 15 Phase change angle calculation unit 16 Relay operation processing unit 17 Setting / display unit 18 Input / output unit 19 External device interface unit (external device I / F unit)
a Vector operator k Reverse phase current detection sensitivity m Branch load factor n _S , n _T S phase and T phase unbalance ratio n _BS , n _BT B side S phase and T phase unbalance ratio n _CS , n _CT C side S-phase and T-phase unbalance ratios I _R , I _S , I _T R-phase, S-phase and T-phase currents I _R ′, I _S ′, I _T ′ Normal R-phase, S-phase and T-phase currents I _BR , I _BS , I _BT B side R phase, S phase and T phase currents I _CR , I _CS , I _CT C side R phase, S phase and T phase currents I _BR ′, I _BS ′, I _BT ′ Normal B-side R-phase, S-phase, and T-phase currents I _CR ′, I _CS ′, I _CT ′ Normal C-side R-phase, S-phase, and T-phase currents I _X , I _Y , I _Z Accident phase , Lagging phase and leading phase currents I _X ′, I _Y ′, I _Z ′ Normal fault phase, lagging phase and leading phase current I ₀ zero phase current I ₁ positive phase current I ₂ reverse phase current I _min minimum load current V ₀ the zero-phase zero-phase voltage V voltage detection sensitivity T trip signal R S, T, X, Y, Z current change rate X, Y, Z fault phase, lag phase and proceeds phase _{θ R, θ S, θ T} , θ R ', θ S', θ T ' phase [Delta] [theta] _R, [Delta] [theta] _S , Δθ _T , Δθ _X , Δθ _Y , Δθ _Z phase change angles θ ₁ , θ ₂ first and second reference angles α, β, γ, δ, ε, ζ first to sixth tolerances S11 to S11. S15, S21 to S28, S29a to S29d, S31 to S38, S39a to S39d Steps

Claims (4)

A disconnection protection relay device (10) for protecting a three-phase AC circuit from a disconnection accident,
Disconnection protection comprising disconnection accident determination means (14 to 16) for determining a disconnection accident based only on phase currents (I _R , I _S , I _T ) flowing through each phase of the three-phase AC circuit Relay device.   2. The disconnection accident according to claim 1, wherein the disconnection accident determination means determines a disconnection accident based on a current change rate and a phase change angle symmetry of a phase current flowing through a healthy phase of the three-phase AC circuit. Protective relay device. The disconnection accident determination means determines that the current change rate (Y) of the lagging phase current (I _Y ) of the three-phase AC circuit is multiplied by the margin (β) of the current change rate (Z) of the leading phase current (I _Z ). And the absolute value of the phase change angle (Δθ _Y ) of the delayed phase current is a value obtained by multiplying the absolute value of the phase change angle (Δθ _Z ) of the lead phase current by the tolerance. The disconnection protection relay device according to claim 2, wherein a disconnection accident is determined on condition that it is within a range. In the case where the three-phase AC circuit is a three-terminal three-phase AC circuit, the disconnection accident determination means determines the phase change angle (Δθ _Y ) of the delayed phase current (I _Y ) of the three-terminal three-phase AC circuit. The disconnection protection relay device according to any one of claims 1 to 3, wherein the location of the disconnection accident is determined on the basis of the above.