JPS59149723A - Protecting relay - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is directed to a body relay for power use, which stabilizes its protective operation in the event of an accident involving frequency fluctuation in the S-break of the power system. There are two types of protective relays.

[Technical background of the invention]

In recent years, as power systems have become larger and more complex, their protection has become more sophisticated (2). In order to maintain especially high operational reliability, in the event of a system fault (even if there is a two-layer wave number fluctuation),
There is a strong need for protective relays with a mechanism to ensure reliable operation. Here, we will explain the prior art. Figures 1 to 3 are representative examples of conventional protective relays. This is a Moo-type distance relay, which is a typical model.

FIG. 1 is a block diagram showing a Moh type distance relay, FIG. 2 is a diagram showing its phase characteristics, and FIG. 3 is a diagram showing details of the memory circuit 3 shown in the block diagram of FIG. 1.

Fig. 1 (In 1, 1 and 2 are an auxiliary transformer and an auxiliary current transformer that introduce the respective voltages / current ÷ into the Moh type distance relay. is converted into a voltage signal of 8V through a memory circuit 3, and is input to a square wave conversion circuit 4.On the other hand, the current signal is converted to a current signal Kl'r advanced by the phase shift circuit 5 by the fIs path (affan pull) of the power transmission line.
After applying 1, 2 is applied to the vector synthesis circuit 6. Furthermore, (in the ni-vector synthesis circuit 6 (1), ※ is applied to the voltage signal from the transformer 1 as Ryu through the setting circuit 7, and 2* is applied to the synthesized signal and τ- is applied to the square wave conversion circuit 8. The outputs of the square wave conversion circuits 4 and 8 are applied to the AN of the next stage.
The on-delay circuit 10 (two voltages are applied through the D circuit 9).

Therefore, if the output of the AND circuit 9 is continued for longer than the time of the on-delay circuit 10 (the phase characteristic shown in Fig. 2 is obtained (2 is the time of 90°)), the relay outputs a trip output.This operating principle is known as a Moh type distance relay. It is something.

In order to clearly distinguish whether the accident near the origin O of the phase characteristics in Figure 2 is in the forward or backward direction, the voltage before the accident is stored in the memory circuit (2). The voltage is attenuated at the same frequency as the square wave conversion circuit 4 (2), which is used as a polarity cover.

[Problems with background technology]

However, this memory circuit is a kind of filter, and for example, as shown in FIG.

The transfer function in the case of Fig. 3 is expressed as follows, where Wl is the angular velocity corresponding to the system's rated frequency (2).Wl is selected as described above (2), and α is determined appropriately (2). At the time of an accident, a waveform is obtained that attenuates while maintaining the angular velocity of Wl even if the input pressure completely disappears.In order to slow down this attenuation and lengthen the memory effect (-, the above-mentioned α is made small, that is, the so-called It is necessary to set the filter's Q'flf (Q-L) high.However, if the Q value is set, the phase angle of the memory circuit will change sharply with the slightest change in the input frequency.This means that This means that the phase characteristics as a mortar carving machine will change greatly (for example, 11 in Fig. 2).
to 12 (changes by 1). The possibility of malfunction or malfunction increases. The frequency of the grid always fluctuates, albeit slightly, especially when the operation of protective relays is required. This is definitely not something that can be overlooked.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of conventional relays and to provide a protective relay whose phase characteristics do not change even under frequency fluctuations.

[Summary of the invention]

The present invention is a protective relay that receives system voltage and current, and obtains an operational output when the phase and magnitude of these voltages and currents are in a predetermined relationship (2), and a frequency detector that detects the frequency of the system voltage. A protective relay (related to -) characterized in that a protection relay is provided with a frequency detection element and controls whether to use the pre-fault voltage or the post-fault voltage as the voltage polarity electrical quantity depending on the presence or absence of the output of the frequency detection element.

[Embodiments of the invention]

An embodiment of the Moh type distance relay according to the present invention when applied is shown in FIG. 4 (2). In FIG. This shows that it is possible to have the same configuration as .

In Fig. 4C2, 1 and 2 are the auxiliary transformer 1 and the auxiliary current transformer 2 that are to be introduced. The output voltage signal t is connected to the memory circuit 3, the square wave conversion circuit 14, the frequency detection circuit 15, and the distance setting circuit 7.

The frequency detection circuit 15 can be configured in many ways using well-known techniques, such as detecting the frequency by counting the period of the input voltage. The output of memory circuit 3 is a voltage signal of 3? The output of the frequency detection circuit 15, which is input to the inhibit circuit 18 via the second square wave conversion circuit 4, is connected to the off-delay circuit 16 and is connected to the NOT circuit 17.
After that, it is connected to the inhibit terminal of the inhibit circuit 18. The output of the frequency detection circuit 15 is also connected to an inhibit terminal of a second inhibit circuit 19. On the other hand, the output of the square wave conversion circuit 14 is connected to a second inhibit circuit 19. Furthermore, the outputs of the inhibit circuits 18 and 19 are connected to an OR circuit.

On the other hand, the output of the auxiliary current transformer 2 is connected to the phase shift circuit 5 (the phase is shifted by the Hiji angle θ) and connected to the vector synthesis circuit 6. Furthermore, in the vector synthesis circuit 6, the output terminal of the setting circuit 7 is also connected to the vector synthesis circuit 6. connected to the square wave conversion circuit 8 (two connected and connected to the AND circuit 9. Also, the AND circuit 9 (- indicates the OR circuit 18
The output of the above-described Moh type distance relay is also connected to the on-delay circuit 10.

Next, the operation of this embodiment) will be explained. The following is an explanation of the effects: when there is a fault voltage and the frequency is fluctuating, when there is a fault voltage and the frequency is not fluctuating, when there is no fault voltage and the pre-fault frequency is not fluctuating, when the fault voltage is If the frequency before the accident is fluctuating (explained separately), the configuration example in Fig. 4 (the frequency detection circuit 15 in 1 is
It is assumed that there is an output (1" output) near the rated frequency, and when the frequency fluctuation increases to a certain extent, there is no output (0' output). (1) If the voltage before the fault is present and the frequency is fluctuating, the system (- fault occurs, voltage at the time of the fault! and current ÷ is applied to the relay foot shown in Figure 4 (-). Since the frequency of the voltage t of 6 is fluctuating, the frequency detection circuit 15
0" output. Therefore, the output of the memory circuit 3 connected to the auxiliary transformer 1 (?) is applied to the square wave conversion circuit 4, but the output is applied to the frequency detection circuit 15, off-delay circuit 16 and NOT It is blocked by the inhibit circuit 18 controlled by the circuit 17 and is not applied to the OR circuit 18. However, the output of the square wave conversion circuit 14 using ? at the output of the auxiliary transformer 1 is the output of the frequency detection circuit 15. Therefore, OR is not blocked by the inhibit circuit 16.
Circuit 18 (: applied. On the other hand, the current signal is applied to the phase shift circuit 5
The torrent signal is advanced by the line angle θ of the power transmission line, and then applied to the vector synthesis circuit 6. In the vector synthesis circuit 6 (1), the voltage signal from the pre-transformer 1 is applied to the voltage signal as V via the setting circuit 7, and K1÷
- To,? The signal is applied to the square wave conversion circuit 4 as a signal. The output of the square wave conversion circuit 4 and the output of the OR circuit are passed through an AND circuit 9, and the outputs of the square wave conversion circuit 4 and the OR circuit are connected to the next stage on-day circuit 10. When the occurrence time (time to obtain the phase characteristics shown in Fig. 2, 11) reaches a predetermined value (2), a trip output is issued. Therefore, the output of the frequency detection circuit 15 is '1''C''-, and the output of the square wave conversion circuit 14 connected to the transformer 1 is the inhibit circuit 19.
will be blocked. However, since the inhibit circuit 18 is opened at the '1'' output of the frequency detection circuit, the 3+ output from the memory circuit 3 is applied to the OR circuit 20 via the square wave conversion circuit 4. 9 and the on-delay circuit 10 to respond in the same way as the action (:) to determine how the relay will trip. (lft) There is no fault voltage and the frequency before the fault does not deviate from the rated value.

When there is no fault voltage, the output of the frequency detection circuit 15 changes from ``1'' to 0. However, the inhibit circuit 18 is opened due to the inverted (NOT circuit 17) output of the off-delay circuit 16 which extends the output of the frequency detection circuit 15 for longer than one hour from the memory circuit 3 connected to the frequency detection circuit 150, and the inhibit circuit 18 is opened. 3 output Ks
v is applied to the subsequent circuit (-) as in action (11), responds in the same manner as action (1), and outputs a trip output. (There is no fault voltage and the frequency has already deviated from the rated value before the fault If you are.

As is clear from the above description, the output phase of the memory circuit 3 is selected. However, due to the phase shift of the memory circuit 3, the phase signal causes variations in the repeater characteristics as described in the prior art. However, when there is no input voltage, the Moh type distance relay works as a simple directional relay that only selects the direction. Therefore, even if an accident occurs, such as when the system frequency deviates significantly from the rated value, it will not be possible to determine the direction. If possible, the phase shift of the memory circuit 3 can be practically ignored.

As shown in actions (1) to (IV) above (=, when there is a frequency fluctuation in the fault voltage, the signal from the memory circuit 3 is not used, and the signal from the memory circuit 3 is used only when there is no frequency fluctuation or when there is no voltage. By using the memory circuit 30, it is possible to obtain a Moh type distance relay which is not affected by the phase shift and whose phase characteristics do not tilt.

[Other Examples]

(1) The above explanation was given using a Moo type distance relay as an example. However, the present invention (2) is not limited to the present invention.For example, the distance setting circuit 7 and the vector synthesis circuit 6 are removed from the Mohau type distance relay shown in FIG. 4 (2), and the phase shift circuit 5 and square wave The conversion circuit 8 was connected.It is clear that the directional relay shown in FIG. 5 (2) has the same effect.

(2) Moh type distance relay that performs analog calculation (two times) to determine the operation (Although I have described it as two, the voltage and current of the system are converted from analog to digital, and then digital calculation (digital Moh type distance relay that performs multiple action determination) Relays (-) can also be applied in the same way as the Moh type relay.

FIG. 5 is a block diagram of a digital distance relay.

FIG. 5 (As shown in Figure 2, the input transformer 21 and the input current transformer 2
2 (calculated input voltage and current ÷ converted to appropriate voltage)
is introduced into the output of the frequency detection circuit 5 connected to the input transformer 21 (=an analog/digital conversion circuit B at the next stage where the sub-ring frequency can be changed), and its output is connected to the DigiMole calculation section B.

In the DigiMole calculation section, the current ÷ (2 proportional ′)
Heavy pressure i <t; and input voltage
.

KsV Kara (2 to Kl"-?) To Ks? To to ys wo Motome constant 1 shift (when it becomes -, output is output.In the above-mentioned digital type motor distance relay (1), the frequency detection circuit Even if the sampling frequency of the analog-to-digital converter B changes during operation and non-operation, the analog type distance RY
It is clear that it has the same effect.

〔Effect of the invention〕

As described in detail above, according to the present invention (-), the slope of the phase characteristic due to the frequency fluctuation of the input voltage is removed, so there is an advantage that the system can be reliably protected.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a conventional Moh type distance extender;
Fig. 2 is a diagram showing the characteristics of the conventional and present invention Moh type distance relays, and Fig. 3 is a diagram showing the memory circuit of the Moh type distance relay shown in Fig. 1). , FIG. 4 is a diagram showing the configuration of a Moh type distance relay according to one embodiment of the present invention, FIG. 5 is a diagram showing the configuration of a directional relay according to another embodiment of the present invention, and FIG. 6 is a diagram showing the configuration of a directional relay according to another embodiment of the present invention. , and (2) are diagrams showing the configuration of a digital type Moh distance relay which is another embodiment of the present invention. 1... Auxiliary transformer 2... Auxiliary current transformer 3...
Memory circuit 15... Frequency detection circuit 19...
Inhibit Circuit (7317) Agent Patent Attorney Rule Chika * f6 (and 1 other person) Figure 1 Figure 2 Figure 3 Figure 4 ``Kei Toga Shoulder Shogi'' JP-A-59-149723 (5) Figure 5 Figure 6 figure

Claims (1)

[Claims] In a protective relay that receives grid voltage and current and obtains an operational output when the phase and magnitude of these voltages and currents have a predetermined relationship, a frequency detection element that detects the frequency of the grid voltage is provided, and this frequency detection element is provided. A protective relay characterized by controlling whether to use a pre-failure voltage or a post-fault voltage as a voltage polarity abrasive amount depending on the presence or absence of an output from an element.