JPS6062819A - 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 can stably maintain its operation in the event of a power system fault with frequency fluctuations.

[Technical background of the invention]

In recent years, as power systems have become larger and more complex, their protection has also become more sophisticated. In particular, because it is necessary to maintain high operational reliability, there is a strong need for protective relays that have a mechanism that can operate reliably even when there are frequency fluctuations in the event of a system fault. . Here, the prior art will be explained. FIGS. 1 to 3 show a Moo-type distance relay, which is a typical model of a conventional protection relay.

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 FIGS.

In FIG. 1, 1 and 2 are respective voltages Q.

An auxiliary transformer and an auxiliary current transformer that introduce the current l into the Moh type distance relay. The voltage signal introduced into the relay passes through the memory circuit 3t and becomes a voltage signal V, which is input to the square wave conversion circuit 40. - 10,000, the current signal is advanced by the line angle of the power transmission line in the phase shift circuit 5, and after changing it to I, it is applied to the vector synthesis circuit 6.Furthermore, in the vector synthesis circuit 6, Good stain pressure signal Kv
is applied to the voltage signal via the distance setting circuit 7 after 2*
The composite signal is applied to the square wave conversion circuit 8 as I-K2V.

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. So AND
If the output of the circuit 9 is continued for the time of the on-delay circuit 1o (time 90' to obtain the phase characteristics shown in FIG. 2), the relay will trip. This operating principle is known as a Moh type distance relay. In the Moh type distance relay mentioned above, in order to clearly distinguish whether the fault near the origin θ of the phase characteristics in Figure 2 occurs in the forward direction or backward direction, the pre-fault voltage is stored in the memory circuit at the same frequency as the pre-fault voltage. It is attenuated and introduced into the square wave conversion circuit 4, and the polarity is divided by 3 and used. However, this memory circuit is a kind of filter, and is composed of a second-order bandpass filter consisting of resistors R, , R2, capacitors C, , C2, and an operational amplifier ICI, as shown in FIG.

[Problems with background technology]

The transfer function in the case of Fig. 3 is expressed as follows, where ω is the angular velocity corresponding to the rated frequency of the system. By selecting ω as described above and appropriately determining α, it is possible to obtain a waveform that attenuates while maintaining the angular velocity of ω even if the input voltage completely disappears in the event of a system fault. In order to slow down this attenuation and prolong the memory effect, the above-mentioned α must be made small, that is, the so-called Q value of the filter (Q=
') is required. However, when the Q value is increased, the phase angle of the memory circuit changes greatly with a slight change in the input frequency. This means that the phase characteristics of the modified Moh type distance relay will change significantly (for example, it will change from 11 to 12 in Figure 2), increasing the possibility of malfunction or malfunction. increase The frequency of the grid always fluctuates slightly, and the possibility of frequency fluctuations increases, especially when protective relays need to operate, so large fluctuations in mining characteristics as described above are inevitable. It is not something that can be overlooked.

[Purpose of the invention]

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a distance relay whose phase characteristics do not change due to frequency fluctuations.

[Summary of the invention]

In the present invention, a direction distance element having no memory effect detects a fault in the direction of the protection interval up to a preset distance of 1I71I, and a fault in the direction of the protection interval up to a settling distance that is sufficiently shorter than this settling distance. The relay output is derived when either one of the directional distance element with memory and the memory-equipped directional distance element that detects the relay is activated.

[Embodiments of the invention]

Examples will be described below with reference to the drawings. FIG. 4 is a block diagram showing an embodiment of the Moh type distance relay of the present invention. In FIG. 4, the same symbols as in FIG. 1 indicate that the same configuration as in FIG. 1 is obtained. FIG. 5 is a diagram combining the characteristics of the memory-less MoW element 13 and the memory-equipped MoW element 14 housed in the MoW type distance relay.

In FIG. 4, reference numerals 1 and 2 indicate an auxiliary transformer and an auxiliary current transformer that introduce the voltage divided by the current i into the Moh type distance relay. A phase shift circuit 5 is connected to the auxiliary current transformer 2, which shifts the phase of its output (current signals x, i) by the line angle θ of the power transmission line. Further, the output of the auxiliary transformer 1 and the output of the auxiliary current transformer 2 are both applied to a memory-less Moh element 13 and a memory-equipped Moh element 14, and the outputs of both elements are applied to an OR circuit 15,
The on-delay circuit 16 and the off-delay circuit 17 are shared. Here, the configurations of the memory-less memory element 13 and the memory-equipped memory element 14 described above will be explained.

(a) The output of the memoryless motor element auxiliary transformer 1 is connected to the rectangular VF conversion circuit 18. Further, the output 6I of the phase shift circuit 5 is connected to the vector synthesis circuit 19 together with the output 5* of the distance setting circuit 7, and the square wave conversion circuit 2 is outputted as a synthesis output x6i -K5V.
Connect to 0. Further, the output is AND circuit 21
is connected to the output pressure of the square wave conversion circuit 18, and the ANDt- and the
Circuit 15, on-delay circuit 16, off-delay circuit 1
7, the memoryless mode element appears.

(b) The output X4V of the memory-equipped motor element auxiliary transformer l is converted into an output 7* via the memory circuit 3, connected to the square wave conversion circuit 22, and converted into a square wave as a composite output --K5*. It is connected to the circuit 25. Furthermore, the output is connected to the AND circuit 26, and the output from the square wave conversion circuit 22 is AND i and 9.
, an OR circuit 15 shared with the memoryless mode element;
It is outputted from the memory-equipped motor element via an on-delay circuit 16 and an off-delay circuit 17. It goes without saying that the outputs of the elements (a) and (b) explained above are the outputs of the Moh type distance relay.

The operation of the configuration example configured as described above will be explained below. The following is an explanation of the operation: - the operating principle of the configuration example, the response to an accident in that configuration when there is tortoise pressure and the frequency fluctuates, the case where there is no fault voltage and the frequency of the pre-fault voltage does not fluctuate, and the accident. We will separately explain the response when the frequency shell of the pre-fault voltage fluctuates without voltage.

■ - Operating principle of the configuration example When an accident occurs in the system, the voltage stand at the time of the accident and ■ are respectively introduced into the Moh type distance relay. The introduced voltage ÷ is converted into a voltage signal of 4* by the auxiliary transformer l, and the distance setting circuit 7
Mo element 1 without memory with 5V to voltage signal via
3, and is applied to the memory-equipped mor element 14. Further, the current i is converted into a current signal No. 5 of 8I by the auxiliary current transformer 2, phase-shifted by the phase shift circuit 5, and changed to a current signal of 61.
C, are applied respectively. The functions of the memory-less memory element 13 and the memory-equipped memory element 14 will be described below.

0) 4Q is applied to the output of the memoryless motor element auxiliary transformer l to the square wave conversion circuit 18. Further, the output from the phase shift circuit 5 is applied to the vector synthesis circuit 19, and the synthesized output is applied to the backward shape wave conversion circuit 20 where 6i- is set to 5V.

The outputs of the two wave conversion circuits 18 and 20 are passed through an AND circuit 21, passed through the OR circuit 15 in the next stage, and time-measured by an on-delay circuit 16 (to obtain the characteristics shown in FIG. ) to be done. Furthermore, the output is made continuous via the off-delay circuit 17 in the next stage, and then the output of the memoryless mode element is obtained.

(b) The output 4* of the memory-equipped Mo-element auxiliary transformer 1 is tied to the output 7* via the memory circuit 3, and is applied to the square wave conversion circuit 22. or,
The output from the phase shift circuit 5 61 is applied to the attenuation circuit 6f. After being set to - at 23, the output from the distance setting circuit 7 is applied to the vector synthesis circuit 24 along with 5V to the output n, which is 1,
Wow. Legs = E5, Kaukou □A. 5. applied. The outputs of the above-mentioned two-wave conversion circuits are passed through the circuit 26, and the OR circuit 15, the on-delay circuit 16, and the off-delay circuit 17, which are shared with the memory-less MoE element 13, are subjected to the same judgment conditions as the memory-less MoE element 13 (fifth In order to obtain the characteristics shown in FIG. 28, the output of the memory-equipped motor element 14 is obtained at the time d). Needless to say, the operating reach of the memory-equipped mo element 14 at this time is 1, which is sufficiently smaller than that of the memory-less element 13.

The outputs (a) and (b) above are the outputs of a Moo type distance relay.

■ If the frequency is fluctuating when there is a fault voltage present 9, If the frequency is fluctuating when there is a fault voltage 9 The mode element 13 without memory that is not equipped with the memory circuit 3 is
There is no effect of the phase shift deviation, and the result remains as shown in FIG. 5, 27. Furthermore, as shown in FIG. 5, the characteristics of the memory-equipped MoE element 14 are sufficiently smaller than those of the memory-less MoE element 13, so that the memory-equipped MoE element 14 is outside the operating range in the presence or absence of a fault voltage. Even if there is a fault voltage in the operating range, the phase characteristics will incline in the same direction as shown in FIG. 2 11-12, but as shown in the phase characteristics in FIG. ) The increase in the protection range due to the slope is extremely small and does not affect the protection characteristics.

■ If there is no pre-fault voltage and the pre-fault frequency has not shifted, in this case, the memory-equipped motor element 14 operates reliably, so a reliable relay response can be expected.

■ If there is no fault voltage and the pre-fault frequency has shifted, the impedance seen by the memoryless motor element 13 due to the pre-fault voltage is outside the operating range, so no trip output will be issued. Furthermore, if an accident occurs and the voltage V disappears, the memory-equipped motor element 14 reliably looks inward, so a reliable relay response can be expected. As can be seen from the above explanation, the slope of the relay characteristics (intrinsic nature) caused by the phase shift of the memory circuit, which was a conventional technique, can be prevented by using the present invention, and the A point accident shown in Fig. 6 can also be prevented. Protectable.

FIG. 7 shows another embodiment of the distance relay according to the present invention.

In this embodiment, an amplifier circuit 27t for amplifying the signal by n times is provided between the vector synthesis circuit 24 and the distance setting circuit 7, and the attenuation circuit is omitted, and the other configuration is the same as that in FIG.

〔Effect of the invention〕

As explained above, according to the present invention, since the slope of the phase characteristic due to the frequency fluctuation of the input voltage is removed, 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 conventional Moh-type distance relay, Fig. 2 is a diagram showing the characteristics of the Moh-type distance relay shown in Fig. 1, and Fig. 3 is a diagram showing the Moh-type distance relay shown in Fig. 1. A diagram showing a memory circuit of a relay, a Maw type distance relay according to one embodiment of the present invention shown in Fig. 4, and a memory circuit of a Mho type distance relay according to another embodiment of the present invention shown in Fig. 7. FIG. 5 is a diagram showing the Moh type distance relay of the embodiment, and FIG. FIG. 4 is a diagram showing the operating range of the Moau type distance relay shown in FIG. l...Auxiliary transformer 2...Auxiliary current transformer 3...Memory circuit 4.8.18t20゜22.25...Square wave conversion circuit 5...Phase shift circuit 6.19.24. ...Vector synthesis circuit 7...Distance setting circuit 9.21.26...AND circuit 10.16...On delay circuit 13...Mo element without memory 14...Mo element with memory 15... OR circuit 23...Attenuation circuit 27...Amplification circuit (7317) Agent Patent attorney Kensuke Norichika (and 1 other person) Picture 1 Picture 4 Ward 5 Illustration 5 Open/open. 7 pictures! ”

Claims (1)

[Claims] In a distance relay that introduces voltage and current from the power system, performs a phase comparison using the composite value of each electrical quantity, and produces an operation when the phase and magnitude have a predetermined relationship, A directional distance element without memory effect that detects faults in the protection interval direction up to a settled distance, and a directional distance element with memory that detects faults in the protection interval direction up to a sufficiently small settling distance (than said settling distance). and,
A distance relay characterized in that an operation output is derived when at least one of the distance elements operates.