JP2963294B2 - Step-out separation device for power system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an out-of-step separation apparatus for a power system for detecting out-of-step to protect the power system and separating the power system.

[0002]

2. Description of the Related Art FIG. 6 shows, for example, "Protective Relay Engineering" (Showa 5
July 20, 2006 Published by The Institute of Electrical Engineers of Japan) It is a characteristic diagram showing the operating principle of the conventional power system out-of-step separation device shown on page 231. Reference numeral 3 denotes a blinder characteristic of the distance relay, reference numeral 4 denotes an area surrounded by the moh characteristic 1 and the blinder characteristic 2, reference numeral 5 denotes an area surrounded by the moh characteristic 1 and the blinder characteristic 2.3, and reference numeral 6 denotes a moh characteristic 1 and the blinder characteristic 3. , The R axis is the direction of the resistance of the flow impedance, and the X axis is the direction of the reactance of the flow impedance.

Next, the operation will be described. In the power system, a power flow flows according to the state of the load at each time, but in the case of a forward power flow, the power flow impedance of the power system exists on the positive side of the R axis (for example, exists at point P), and In this case, the power flow impedance of the power system exists on the negative side of the R axis (for example, exists at the point Q).

However, when the step-out phenomenon occurs, the flow impedance gradually approaches the X-axis, and eventually has a characteristic of moving across the X-axis to the opposite side. Referring to FIG. 6, the tidal current impedance moves in the region 4 → 5 → 6 or 6 → 5 → 4. Therefore, in the related art, the step-out is detected by detecting this movement, and when the step-out is detected, the power system is separated to protect the power system.

[0005] Further, as another method for detecting a step-out and separating an electric power system, there is the following method. That is, as shown in FIG. 7, the electrical center point of the step-out (point at which the voltage becomes zero) is located at the center point (the point of Z ₁ = Z ₂ ) of the power flow impedance of the out-of-step power system. Also, the distance to the center point is the same as when the three-phase short-circuit phenomenon occurs at the center point, so that the distance to the center point of step-out is determined using the distance, and based on the distance, In some cases, it is determined whether the power system is separated or not, and the power system is separated.

[0006]

Since the conventional power system step-out separation device is configured as described above, even if the local generator is not out of step, a certain large system is out of step (this system). In the case of a system step-out, it is determined that the local generator has stepped out, so that there is a problem that the local generator that does not need to be separated is separated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and clearly distinguishes between a case where the local generator has stepped out and a case where the local generator may have stepped out. An object of the present invention is to obtain a power system out-of-step separation device that does not unnecessarily separate a local generator.

[0008]

SUMMARY OF THE INVENTION A step-out / separation device for a power system according to the present invention includes a blinder characteristic of a distance relay and a reconnection.
If the area surrounded by the actance characteristics is defined as the first area
In both cases, the reactance component is the reactance in the first region.
The reactance characteristic larger than the
The area surrounded by the same blinder characteristics as the second area
When the impedance trajectory passes through the first region, the local power generator is immediately determined to be out of synchronization, the power system is separated, and when the impedance trajectory passes through the second region, a predetermined time elapses. Only when the impedance locus passes through the second region again, it is determined that the local generator has lost synchronism, and the power system is separated.

[0009]

According to the present invention, when the impedance locus passes through the second region, the system generator separates out of the local generator only when the impedance locus passes through the second region again after a predetermined time has elapsed. Since the judgment is made, the power system is separated only when it is convinced that the local generator is out of step.

[0010]

[Embodiment 1] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an out-of-step separation device for a power system according to an embodiment of the present invention.
7, a predetermined region in which the resistance and reactance components of the power flow impedance in the power system are near zero is defined in advance as a first region (see FIG. 2, details will be described later);
A setting unit that determines a predetermined region in which the reactance component is larger than the reactance component of the first region as a second region (see FIG. 2), and an input unit 8 that sequentially samples current and voltage in the power system.

Numeral 9 denotes a calculation unit for calculating a tidal current impedance from the current / voltage sampled by the input unit 8 to obtain an impedance locus, and an impedance locus obtained by the calculation unit 9 has passed through the first area. In this case, it is immediately determined that the local generator has lost synchronism, the power system is separated, and the impedance trajectory is
Is a system separation unit that determines that the local generator has lost synchronism only when the impedance locus again passes through the second region after a predetermined time has passed after passing through the region, and separates the power system.

FIG. 2 is a characteristic diagram showing the operation principle of the power system out-of-step separation device shown in FIG.
13.14,15 are the blinder characteristics of the distance relay, 1
6.17.18 are the reactance characteristics of the distance relay, A ₁
Are the blender characteristics 12 and 13 and the reactance characteristics 17
- 18 area surrounded by, A ₂ is Blinder characteristics 13 -
14 and the area surrounded by the reactance characteristics 17 and 18, B
₁ is the blender characteristics 12 and 13 and the reactance characteristics 1
Region surrounded by the 6 · 17, B ₂ is Blinder characteristics 13
An area surrounded by 14 and reactance characteristics 16 and 17;
C ₁ is a region surrounded by the blinder characteristics 11 and 12 and the reactance characteristics 16 and 18, and C ₂ is a blinder characteristic 1
This area is surrounded by 4.15 and reactance characteristics 16 and 18.

Here, A ₁ and A ₂ are predetermined regions (first regions) in which the resistance and reactance of the power flow impedance in the power system are near zero, respectively, and B ₁ and B 2.
Reference numeral ₂ denotes a predetermined area (second area) in which the reactance is greater than the reactance of the first areas A ₁ and A ₂ .

FIG. 3 is a block diagram showing a power system to which the power system out-of-step separation apparatus shown in FIG. 1 is applied. CT), 23 is a voltage converter (PT), 24 is C
An input converter for converting the signal of T22, 25 is an input converter for converting the signal of PT23, 26 and 27 are filter sections, 28 and 29 are sample and hold circuits, 30 is a multiplexer, and 31 is an analog / digital converter (A / D
Converter), 32 is a step-out separation device of the power system of FIG.
Is an output circuit.

Further, FIG. 4 is a vector diagram showing the voltage vector and the step-out center point at the time of step-out of the power system (FIG. 4 (b) is a vector diagram at the time of step-out of the main system, and FIG. It is a vector diagram at the time of machine out-of-step.)
4 - 35 of the present system generator, 36 this system, 37 a local system, Z _1, Z ₂ is a step-out center point.

Next, the operation will be described. As described above, when the step-out phenomenon occurs, the power flow impedance gradually approaches the X-axis, and eventually has a characteristic of moving across the X-axis to the opposite side. Therefore, the following can be considered as the movement (impedance trajectory) of the power flow impedance when the step-out phenomenon occurs (see FIG. 2). (1) Area C ₁ → A ₁ → A ₂ (2) Area C ₂ → A ₂ → A ₁ (3) Area C ₁ → B ₁ → B ₂ (4) Area C ₂ → B ₂ → B ₁

Here, as shown in FIGS. 4B and 4C,
Since the distance from the local generator 21 to the step-out center point appears to be farther when the system is out of synchronization than when the local generator is out of synchronization, the power flow impedance is higher when the system is out of sync than when the local generator is out of sync. It can be seen that the reactance of the above becomes large. Therefore, the impedance trajectory becomes the first area A ₁
Or, when the vehicle passes through the second area B ₁ or B ₂ , the possibility of the system out-of-step is higher than when the vehicle passes through A ₂ .

Therefore, the reactance characteristics 16.1
By appropriately setting the set value of 7, when the impedance trajectory passes through the first area A ₁ or A ₂ , it can be determined that the local generator has lost synchronism, while the impedance trajectory is in the second area B ₁ or when passing through the B ₂ can assume the possibility of step-out of the local generator 21.

In the state set as described above, first, the calculation unit 9 calculates the power flow impedance from the current / voltage sampled by the input unit 8 to obtain an impedance locus.

When the impedance trajectory obtained by the operation unit 9 passes through the first area A ₁ or A ₂ , the system separation unit 10 immediately determines that the local generator 21 has stepped out and outputs the result. A signal for separating the power system is output via the circuit 33. On the other hand, if the impedance locus passes through the second area B ₁ or B ₂ , there is a possibility of stepping out of the main system. the impedance locus is determined to local generator 21 only when passing through the second region B ₁ or B ₂ is stepped out output circuit 3
3 to output a signal for separating the power system.

That is, in the case of the main system step-out, when the impedance trajectory first passes through the second area B ₁ or B ₂ , the relay in the main system separates the step-out system. After the lapse of time, the impedance locus does not pass through the _second area B ₁ or B ₂ again, so that the local generator 21 does not need to be separated unnecessarily.

Embodiment 2 FIG. In the first embodiment, the first
The areas A ₁ or A ₂ and the second region B ₁ or B ₂ has described those formed with Blinder characteristics 12, 13 and 14, as shown in FIG. 5, a circular characteristic 41 &
42 may be used, and the same effects as in the first embodiment can be obtained.

[0023]

As described above, according to the present invention, when the impedance trajectory passes through the first region, it is immediately determined that the local generator has stepped out, and the power system is separated. In the case of passing through the area 2, the impedance locus is again changed to the second after a predetermined time has elapsed.
Only when passing through the area, it is determined that the local generator is out of sync and the power system is separated, so it is not necessary to separate local generators that do not need to be separated when the system is out of sync. Has the effect.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an out-of-step separation device for a power system according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing an operation principle of the out-of-step separation device of the power system of FIG.

3 is a configuration diagram showing a power system to which the power system out-of-step separation apparatus of FIG. 1 is applied.

FIG. 4 is a vector diagram showing a voltage vector and a step-out center point at the time of step-out of a power system.

FIG. 5 is a characteristic diagram showing an operation principle of a step-out separation device for a power system according to another embodiment of the present invention.

FIG. 6 is a characteristic diagram showing an operation principle of a conventional power system out-of-step separation device.

FIG. 7 is a vector diagram showing a voltage vector and a step-out center point at the time of step-out of a power system.

[Explanation of symbols]

7 setting section 8 input section 9 calculation section 10 system separation section 21 local generator A ₁ , A ₂ first area B ₁ , B ₂ second area

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toshiki Hattori 1-2-1, Wadasaki-cho, Hyogo-ku, Kobe Mitsubishi Electric Corporation Control Factory (56) References JP-A-52-21637 (JP, A) JP-A-56-141724 (JP, A) JP-B-63-46649 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02H 3/48 H02J 3/24

Claims (1)

(57) [Claims] A distance in which a resistance component and a reactance component of a power flow impedance in a power system are near zero in advance.
Surrounded by the blinder and reactance characteristics of the relay
Is defined as the first region, and the reactance component
Is greater than the reactance of the first region
And the same blinder characteristics as above.
A setting unit that defines a region surrounded by the characteristics as a second region, an input unit that sequentially samples current and voltage in the power system, and a power flow impedance calculated from the current and voltage sampled by the input unit. When the impedance trajectory obtained by the calculation unit passes through the first region, it is immediately determined that the local generator has lost synchronism, and the power system is separated. A system separation unit for determining that the local generator has lost synchronism only when the impedance locus has passed through the second region after a predetermined time has elapsed when the vehicle passes through the second region; A power system out-of-step separation device equipped with: