JPS6281924A - Distance 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 relates to a distance relay, and particularly to a distance relay that stably performs its protective operation in the event of an accident in a power system that causes frequency fluctuations. It is.

[Technical disadvantages of the invention] In recent years, as power systems have become larger and more complex, their protection has also become more sophisticated. In particular, in order to maintain high operational reliability, there is a strong need for protective relays that have a mechanism that allows them to operate reliably even when there are frequency fluctuations in the event of a system fault. Here, the prior art will be explained. FIGS. 4 to 5 show a Moh type distance relay, which is a typical i-second type of conventional protective relay.

Figure 4 is a block diagram showing Mo-Katabori wi relay evaporation, Figure 5
6 is a diagram showing its phase characteristics, and FIG. 6 is a detailed dimensional diagram of the memory circuit 3 shown in the block diagram of FIG. 4.

In the above-mentioned Moh type distance joint ff1Z, in order to clearly distinguish whether the fault near the origin O of the phase characteristics in Figure 5 is in the Moe direction or in the (U force direction), the pre-fault voltage is stored in a memory circuit as the pre-fault voltage. It is attenuated at the same frequency, introduced into the square wave conversion circuit 4, and used as a polarity of 3V.

In FIG. 4, reference numerals 1 and 2 are an auxiliary transformer and an auxiliary current converter that respectively introduce a voltage and a current into a Moh type distance relay.The voltage signal introduced into the relay is passed through a memory circuit 3 The voltage signal is set to 3 V and is input to the square wave conversion circuit 4.

On the other hand, the current signal is advanced by the line angle (θ) of the power transmission line to a current signal of 1 (1) in the phase shift circuit 5, and then applied to the vector synthesis circuit 6. Further, in the vector synthesis circuit 6, the voltage signal KV from the auxiliary transformer 1 is converted into a voltage signal via the distance setting circuit 7 and applied to the square wave conversion circuit 8. The outputs of the square wave conversion circuits 4 and 8 are applied to an on-delay circuit 10 via an AND circuit 9 at the next stage. Therefore,
If the output of the AND circuit 9 continues for more than 100 hours (90° time to obtain the phase characteristics shown in FIG. 5) of the on-delay circuit, the relay outputs a trip output. This operating principle is known as a Moh type distance relay.

[Problems with the seven technologies] The above-mentioned memory circuit is a kind of filter, and for example, as shown in FIG.
It is composed of a second-order bandpass filter consisting of C2 and amplification file1.

The transfer function in the case of FIG. 6 is expressed as follows, where Wl is the angular velocity corresponding to the rated frequency of the system. By selecting Wl as described above and appropriately determining α, it is possible to obtain a waveform that attenuates by 1 while maintaining the angular velocity of Wl even if the input voltage completely disappears in the event of a system fault. This attenuation is l! In order to suppress the memory effect, the above-mentioned α should be made small, that is, the so-called 01 direct (
It is necessary to set Q=1> high. But 1. When the Q value is increased, the phase angle of the memory circuit changes greatly due to undesired fluctuations in the input frequency. This means that the phase characteristics of the Moh type distance relay will change greatly (for example, from characteristic 11 to characteristic 12 in Fig. 5), and there is a possibility of malfunction or malfunction. increase The frequency of the grid always fluctuates, albeit slightly, and the possibility of frequency fluctuations is increasing, especially when the operation of protective relays is required. Therefore, large fluctuations in the protection characteristics as described above are , it is definitely not something that can be overlooked.

[Object of the Invention] The present invention has been made to solve the above problems, and an object of the present invention is to provide a distance relay whose phase characteristics do not change even under frequency fluctuations.

[Summary of the Invention] The present invention provides a distance relay that receives the voltage and current of the grid and obtains an operational output when the phase and magnitude of these voltages and currents have a predetermined relationship. A phase detection element having a predetermined level detection function is provided, and depending on the presence or absence of the output of this phase detection element, voltage polarity can be electrified by using an electric current through a memory circuit, or
This attempts to control whether or not to use a voltage that does not go through the memory circuit.

[Embodiments of the Invention] FIG. 1 shows an embodiment in which the present invention is applied to a Moh type distance relay. In FIG. 1, the same parts as in FIG. 4 are not shown with the same reference numerals.

Further, FIG. 2 is a diagram without showing a time chart of the phase detection circuit used in one embodiment of the present invention.

In FIG. 1, 1 and 2 are an auxiliary transformer 1 and an auxiliary current transformer 2 for introducing the system voltage (1) and current (I) into the Mokataburi [[[[[]]. The voltage signal V introduced by the auxiliary transformer 1 is connected to a memory circuit 3, a square wave conversion circuit 14, and a distance setting circuit 7.

The output of the memory circuit 3 is converted into a voltage signal of 3 V and is input to the inhibit circuit 18 via the second square wave conversion circuit 4.

Further, the outputs of the square wave conversion circuits 4 and 14 are connected to a phase detection circuit 15. The phase detection circuit 15 connects the output of the square wave conversion circuit 4 to a NOT circuit 16, uses the output of the square wave conversion circuit 14 as an input to an AND circuit 17, and connects the output of the AND circuit 17 to an on-delay circuit. (TOE
)21. Further, its output is connected to an off-delay circuit (TOO) 22, and its output is connected to a phase detection circuit 1.
The output will be 5. Then, the output of the phase detection circuit 15 is
The inhibit 1 circuit 18 is connected to the inhibit terminal. Further, the output of the phase detection circuit 15 is output from the AND circuit 1.
It is also connected to terminal 9. On the other hand, the square wave conversion circuit 1
4 is connected to the AND circuit 19, and the outputs of the inhibit circuit 18 and the AND circuit 19 are connected to the
It is connected to the R circuit 20.

On the other hand, the output of the auxiliary current transformer 2 is phase-shifted by a line angle θ in a phase shift circuit 5 and connected to a vector synthesis circuit 6. Furthermore, in the vector synthesis circuit 6, the output terminal of the distance setting circuit 7 is also connected, which is connected to the square wave conversion circuit 8, and is connected to the NO.
Connected to circuit 9.

The output of the OR circuit 20 is also connected to the NO circuit 9, and is used as the output of the Moh type distance relay via the on-delay circuit 10.

[Action 1 of the Invention Next, the action of the present invention will be explained. In the following, the operation will be explained separately into the phase detection circuit 15 in the configuration example of FIG. 1 and the entire embodiment of the present invention. The contents are: if there is a fault voltage and the frequency is fluctuating, if there is a fault voltage but the frequency is not fluctuating, if there is no fault voltage and the pre-fault frequency is not fluctuating, and if the pre-fault frequency is fluctuating. Let me explain the case.

In addition, the square wave conversion circuits 4.8 and 14 in the operation explanation are as follows:
It has the ability to convert into a square wave at a predetermined input level.

(1) Operation of the phase detection circuit 15 The operation of the phase detection circuit 15 will be explained using the configuration example shown in FIG. 1 and the time chart shown in FIG. 2.

■Before the accident If there is a Fi pressure and the frequency is fluctuating, an accident has occurred in the system, and the voltage V and current I at the time of the accident are
applied to the relay shown in the figure. Since the frequency of the voltage V at this time is fluctuating, as shown in the time chart of FIG. A deviation T1 occurs. Therefore, there is a phase shift between the wave that is converted into a square wave by the square wave conversion circuit 4 via the memory circuit 3 and the wave that is directly converted into a square wave by the square wave conversion circuit 14 without going through the memory circuit 3. A square wave is applied to the phase detection circuit 15.

In the phase detection circuit 15, the output of the square wave conversion circuit 4 is inverted by the NOT circuit 16, and the output of the square wave conversion circuit 1 is inverted.
8 HO is obtained by the AND circuit 17 with the output of 4. AN
Since there is a phase difference between the output of the D circuit 17 and the output that does not go through the memory circuit 3, the output of the D circuit 17 is as long as the time T of the phase difference. This output is measured for a certain period of time T2 by the on-delay circuit (TDE) 21 connected to the next stage, and is made continuous via the off-delay circuit (TDD) 22 of the next stage to be output as "1" output of the phase detection circuit 15. shall be.

■If there is a voltage before the fault and the frequency does not fluctuate, the input of the memory circuit 3 (the input of the square wave conversion circuit 14) is There is no phase shift between the output (same as ) and the output.Therefore, the outputs of the square wave conversion circuit 4 and the square wave conversion circuit 14 are in phase, and the output of the square wave conversion circuit 4 is inverted by the NOOR circuit 20. and square wave conversion circuit 1
The output via the ND circuit 17 to the output of 4 is "0". Therefore, the output of the phase detection circuit 15 is "0".

■If there is no fault voltage and the frequency before the fault does not deviate from the rating, if the fault voltage disappears, the AND circuit 17 of the phase detection circuit 15
The output of the square wave conversion circuit 14 is continuous rOJ.
Therefore, the output of the AND circuit 17 is continuous rOJ. Therefore, the output of the phase detection circuit 15 is also rOJ.

■If there is no fault voltage and the frequency has already shifted before the fault, in this case as well, as in item 0 above, there is no voltage before the fault, so the square waveform is Since the output of the conversion circuit 14 is continuous rOJ, the phase detection circuit 15
The output of is also "0".

(2) Effects of the entire embodiment of the present invention ■ If the frequency fluctuates at the pre-fault frequency, a fault occurs in the grid, and the voltage V and current I at the time of the fault are applied to the relay shown in Figure 1. be done. Since the frequency of the voltage V at this time is fluctuating, the phase detection circuit 15 outputs "1". 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 blocked by the inhibit circuit 18 controlled by the phase detection circuit 15, and the OR circuit 20 is never applied. However, since the output of the phase detection circuit 15 is 11'', the output of the square wave conversion circuit 14 using the output KV of the auxiliary transformer 1 is blocked by the AND circuit 17 and is applied to the OR circuit 20.

On the other hand, the current signal is advanced by the line angle θ of the power transmission line to +I in the phase shift circuit 5, and then applied to the vector synthesis circuit 6. In the vector synthesis circuit 6,
A voltage signal from the auxiliary transformer 1 is applied to a voltage signal shape wave conversion circuit 8 via a distance setting circuit 7. The output of the square wave conversion circuit 8 and the output of the Of circuit 20 are passed through the ND circuit 9 to the next stage on-delay circuit 10, where the outputs of the square wave conversion circuit 8 and the OR circuit 20 both produce a "1" output. When the time (time required to obtain the phase characteristics shown in FIG. 5 and 11) reaches a predetermined value, a trip output is output.

■When there is a fault voltage and the frequency does not fluctuate, the output of the phase detection circuit 15 becomes rOJ because there is no frequency fluctuation at the time of a system fault, and the output of the square wave conversion circuit 14 connected to the auxiliary transformer 1 is blocked by the NO circuit 19.

However, the inhibit circuit 18
Since the circuit is opened at the "0" output of the memory circuit 3, the 3V output from the memory circuit 3 is applied to the OR circuit 20 via the square wave conversion circuit 4. Therefore, the AND circuit 9 and the on-delay circuit 10 perform the same response as in the operation (2) to output a trip output of the relay.

■When 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 phase detection circuit 15 is
0". At that time, the inhibit circuit 18 is opened by the "0" output of the phase detection circuit 15, so the 3 V output from the memory circuit 3 becomes a square wave'! ! It is applied to the OR circuit 20 via the L conversion circuit 4.

Therefore, the AND circuit 9 and the on-delay circuit 10 are used to avoid the same response as in the action (2) and output the trip output of the relay.

■If there is no fault voltage and the frequency has already deviated from the rated value before the fault, the output phase of the memory circuit 3 is selected, as is clear from the above explanation. However, the phase signal causes fluctuations in the relay characteristics as described in the prior art due to the phase shift of the memory circuit 3. However, when the input voltage disappears, the Moh type distance relay works as a directional relay IIi only by selecting the direction. Therefore, even if an accident occurs in which the system frequency at the time of the accident deviates significantly from the rated value, the phase shift of the memory circuit 3 can be practically ignored as long as only the direction can be reliably determined.

As shown in ■ to ■ 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 and no voltage. It is possible to obtain a Morph type separation relay which is not affected by the phase shift of the memory circuit 3 and whose phase characteristics do not fluctuate.

[Other Embodiments] Although the above description has been made using a Moh type distance relay as an example, the present invention is not limited to this. For example, from the Moh type distance relay shown in FIG. 1, which is an embodiment of the present invention, the distance setting circuit 7
It is clear that a directional relay shown in FIG. 3 in which the vector synthesis circuit 6 is removed and the phase shift circuit 5 and the square wave conversion circuit 8 are connected has the same effect.

As described above, according to the present invention, fluctuations in phase characteristics due to frequency fluctuations of input voltage are eliminated, so there is an advantage that the system can be reliably protected.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a Moh type distance relay according to an embodiment of the present invention, FIG. 2 is a diagram showing a time chart of an embodiment of the present invention, and FIG. 3 is a diagram showing another embodiment of the present invention. Figure 4 is a diagram showing the configuration of a conventional seven-way relay, and Figure 5 is a diagram showing the characteristics of the conventional seven-way relay and the present invention. , FIG. 6 is a diagram showing a memory circuit of the Moh type distance relay shown in FIG. 4. 1...Auxiliary transformer 2...Auxiliary current transformer 3...Memory circuit 4.8.14...Square wave conversion circuit 5...Phase shift circuit 6...Betta 1-L synthesis circuit 7...Distance setting circuit 9.17.19...AND circuit 10.21...On delay circuit 15...Phase detection 1j circuit

Claims (1)

[Claims] In a distance relay that obtains an operating output when the voltage and current of the grid are input quantities and the phase and magnitude of these voltages and currents have a predetermined relationship, the voltage as introduced and the voltage as introduced are A phase detection element is provided to detect the phase when the voltage stored for a predetermined time reaches a predetermined level value, and depending on the presence or absence of the output of this phase detection element, the voltage polarity as introduced is determined as the electrical quantity. A distance relay characterized in that it controls whether to use a voltage or to use a voltage obtained by storing an introduced voltage for a predetermined period of time.