JPS5950728A - 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 relates to a relay that operates by inputting AC electricity from a power system and detecting the range of change thereof.

[Technical background of the invention and its problems]

7 types of relays are used as safety relays to check the connection between lightning and power systems, and one of them is an electric quantity change range detection device that detects the change range of the input electric quantity. There is. Hereinafter, the principle of operation of the TLR and air volume change range detection relay according to the prior art will be explained with reference to FIGS. 1 and 2.

Fig. 1 is a block diagram showing an example of the configuration of an electric power/variation range detection relay.
a bandpass filter circuit (BPF) whose resonance point is the fundamental wave frequency, a difference detection circuit (ADD) which detects the difference between the output of the two-digit bandpass filter circuit 1 and the above-mentioned AC electricity amount 81, and a three-digit difference detection circuit (ADD) A level detection circuit (LD) that detects the level of the output of the difference detection circuit 2 + 4 is a time-limited return circuit (TDD) that makes the output of the level detection circuit 3 continuous.
It is. In other words, the bandpass filter circuit FIbl is a circuit that has the function of storing analog signal waveforms, and the difference between the input and output of this bandpass filter circuit 10 is detected by the difference detection circuit 2 at the next stage. A signal proportional to the width of change in electrical ISiel is obtained. The level of the output of the difference detection circuit 2 is detected by the level detection circuit 3 at the next stage, and if it exceeds a predetermined value, the output is produced. moreover,
The output of this level detection circuit 3 is made continuous for a certain period of time by a time-limited return circuit 4, and is sent out as a relay output e8.

Figure 2 shows the operating characteristics of the electrical quantity change range detection relay shown in Figure 1. As shown in the figure, 82eto is the AC quantity vector before the state change, and i and l are the AC quantity vector after the state change. Assuming that the electric vector is the vector, the operating formula of this relay is l etl
- t, I≧, and the operating range is outside the circle having the illustrated radius.

By the way, as is well known, the current change width detection relay that introduces the AC current of the power system as AC electricity ff1el in Figure 1 can detect a system fault even in the presence of 1f power flow (large power flow). Therefore, it is widely applied as a fail-safe relay for distance relays, etc. In this case, generally speaking, considering the shunting effect of fault current, etc., it is desirable to set the current change width detection relay to be as sensitive as possible. In case g:, the distance relay as the main relay malfunctions, causing the breaker to be erroneously shut off over a very wide area. This means that the current change width relay electrical appliance cannot fully demonstrate its function as a 7-work safety relay, and a solution to this problem has been strongly desired in recent years.

[Investigation: Ming's purpose]

The present invention was made in view of the above circumstances, and
The purpose is to provide a highly reliable maintenance relay that can protect the power system by preventing unnecessary responses by switching the operating sensitivity based on the amount of electricity in advance.

[Summary of the invention]

In order to achieve the above object, the present invention provides a band-pass filter circuit that introduces a current taken out from a power system, an output of this band-pass filter circuit and a current of the power system, and calculates the difference between the two input electrical quantities. a current change range relay, which is provided with a level detection circuit that inputs a quantity of electricity and generates a C2 output when the input quantity of electricity is equal to or higher than a set level, and is capable of switching the set level by an external signal C2; A protection relay C2 is constructed of a sensitivity switching circuit that introduces a current and switches the set level of the level detection circuit to a lower sensitivity side when the magnitude of the current is equal to or higher than the current reference value, and is related to the power system. This greatly improves the reliability of power supply.

[Embodiments of the invention]

Hereinafter, a bell-holding relay according to the present invention will be explained with reference to the drawings.

FIG. 3 is a block diagram illustrating the configuration of a Nφ relay according to an embodiment of the present invention, and the same parts as in FIG. 1 are designated by the same reference numerals. In the diagram, the original waveform is subjected to appropriate signal processing (not shown) such as insulation and noise removal, and then is inputted as an alternating current quantity of electricity θl to an electric quantity change width detection element 6 and a full-wave rectifier circuit 7C. Among these, only the level detection circuit 5 in the electric quantity change width detection element 6 is different, and the other configurations are the same as the block diagram of FIG. 1 already described. That is, 1 is a band-pass filter circuit (BPF) which inputs the alternating current quantity e1 and uses its fundamental wave frequency as the resonance point, and 2 detects the difference between the output of this band-pass filter circuit 1 and the alternating current quantity e1. The difference detection circuit (ADD) 5 is a level detection circuit (LD) for detecting the level of the output of the difference detection circuit 2, and has, for example, a circuit configuration as shown in FIG. 4, which will be explained later. This is a time-limited return circuit for making the output of the 4-digit level detection circuit 5 continuous. Since the six electrical quantity change width detection elements are configured in the same manner as described above, the difference between the input and output of the bandpass filter circuit 1 is detected by the difference detection circuit 2 in the next stage, thereby detecting the alternating current voltage.
A signal proportional to the change width of 1 is obtained, and this difference detection circuit 2
The level of the output is detected by the level detection circuit 5 at the next stage, and an output is generated if the output exceeds a predetermined value.

Further, this output is made continuous for a certain period of time by a time-limited return circuit 4 and sent out as a relay output e8.

On the other hand, AC electric jttel is a full wave rectifier circuit (REC) 7
After full-wave rectification, the signal is led to a smoothing circuit (Lpy) and converted into a smooth signal. The voltage is then input to the next-stage σ section comparator 9, where it is compared with a predetermined reference potential Ref, and if it is greater than the reference potential Ref, it is output. This output is input to the delay β2 circuit 10 for appropriate time coordination.

Then, the output of the delay circuit 10 is inputted to the level detection circuit 5 of the above-mentioned electricity a'' change width detection-9 element 6, and the zero-order C2 level detection circuit that controls the operating sensitivity of the electric quantity change width detection element 6 is inputted. An example of the configuration of ?↑5 is shown in Fig. 4.Fig.
It is an ET switch. Control terminal t'j of this level detection circuit 5: Gate G of TRI, and this control terminal G
The output end of the delay circuit 1°, which is the output of the preliminary electric quantity detection section, is connected to.

Next, is the operation of the shielded relay of the present invention configured as shown in the block diagram of FIG. 3 mentioned above? , reveal.

In Fig. 3, when the input AC quantity θ1 of the current before changing (hereinafter referred to as pre-input current) is small, that is, the load current is small, and when the pre-input current is large, that is, the background power supply interference is small. large load t
i. Effect 5 of the present invention will be explained assuming two cases where a current flows.0 First, the time chart of item 51 will be explained for the case where the pre-input current is small.

It is assumed that the input current from the grid is converted into an appropriate amount of electricity θ1, and for example, 4th cycle 1: There is a slight change. Full-wave rectification of electric power e2 by this full-wave rectification circuit 7 of e1
It is further smoothed by the smoothing circuit 8 and becomes electric f, 1I
It becomes eB. Then, the comparison circuit 9 in the next stage compares it with a predetermined quantity of electricity, that is, a predetermined reference potential Rθf, and when this reference potential Ref is an unvortexed quantity of electricity, the output quantity of electricity e41d of the comparison circuit 9 becomes "0", and the reference potential More than Ref!
When the temperature is low, the output electricity e4 of the comparator circuit 9 is "'
Therefore, as shown in FIG. 5, the electric quantity e4 becomes "0" until the third cycle, and when the electric quantity θl changes, the output electric power fi!'e.

becomes “1”. A signal delay for time coordination is measured by the delay circuit for this "1" output, and the output il- for the delay circuit becomes time-delayed like e5. The output 85 of the delay circuit 10 causes the detection level of the level detection circuit 5 of the change width detection element 6 to be switched from the initial high sensitivity of 1 to the low sensitivity of 2.

Now, since the mud is small, the output of the difference detection circuit 2 is 8.
(The sensitivity level of the level detection circuit 5 is set to the high sensitivity level 1 by 1. Therefore, the output θ, , l17 of the level detection circuit 5 is as shown in the figure (changes in the 4th cycle of the electric firefly powered by two people). On the other hand, the level detection circuit 5 responds to the sensitivity L2, and the output becomes "1"' as shown in Figure ζ2,
It is made continuous by the next-stage time-limited return circuit (TDD) 4 and becomes the final output e8.

As explained above, if the pre-input current is small, its change can be detected with high sensitivity.

Next, a case where a slight change that does not require a response occurs when the preliminary current is large will be explained with reference to the time chart of FIG. 6.

In this case as well, the same response as in the case shown in FIG. 5, 12 is shown. In other words, the input current from the grid is converted into the appropriate electrical power 'jA'el. For example, suppose that there is a slight change in the fourth cycle. The full-wave rectifier circuit 7 converts the τte and air resistance °e1 into full-wave rectified electricity t1θ, which is further smoothed by a smoothing circuit 8 to become electricity and airflow θ8.

Then, the comparison circuit 9 at the next stage sets a predetermined reference potential Ref.
compared to By the way, since the input current before M4 is large, the output e4 of the comparator circuit 9 becomes "1" as shown in the figure, and passes through the delay circuit 10 to the level detection circuit 5, that is, the variable level detector of FIG. is input to the gate G of the FET switch at. In this case, two resistor peaks will be short-circuited, so the DC reference value must be increased. This means that the operating sensitivity of the switching level detection circuit 5 has been switched from high sensitivity, 1, to low sensitivity, 2. Therefore, for a slight change in input box b1 in the fourth cycle, Variable level detection circuit 5I#j: does not respond, and the final output of the width and volume change width detection element 6 is 0. In other words, it can be said that the box 6 does not need to respond to slight changes when the pre-input electric oil is large.

As described in detail above, according to the four-way relay of the present invention, when the amount of electricity required for high-sensitivity operation is small, the level detector operates at a high-sensitivity level. (2) Detect changes in the input electrical part more reliably than 1., i fr, in the case of a system where the back impedance is small, the input room is very sensitive and slight changes that do not require a response are detected. In contrast, the conventional high-sensitivity setting results in unnecessary responses.[2] However, by changing the operating sensitivity of the level detector to low sensitivity, it is possible to avoid unnecessary responses.

What about the above? , an embodiment of the present invention has been described with reference to FIG. 3, but it goes without saying that the present invention is not limited thereto and can be applied. For example, as a configuration for detecting the magnitude of the amount of electricity input in advance, a circuit consisting of a smoothing circuit 8 and a comparator 9 is used in FIG. 3, but instead of this circuit configuration, a level The same effect as in the above embodiment can be obtained by using a circuit consisting of the detection circuit 11 and the recovery delay circuit 12.

In the variable type level detector shown in Fig. 4, the operating sensitivity was controlled by varying the DC reference amount E [7], but as shown in Fig. 8, when the DC reference amount was fixed, the input electricity amount was Side IN
It is obvious that the same effect as that of the variable level detector described above can be obtained even if . Note that 13 in FIG. 8C2 is an inverting circuit that converts the input signal to an appropriate level.

Furthermore, in the variable level detector shown in FIG. 4, F1ii
Sensitivity switching is carried out using a T switch, but as shown in FIG. 9, an auxiliary relay 14 is provided that operates with the output of the operation delay circuit 10, and the variable level can be changed by turning on and off the contact X of this auxiliary relay 14. To change the sensitivity of detector 5 (
You can also do two.

〔Effect of the invention〕

As explained above, C2, according to the present invention (2), the sensitivity of the level detector can be changed according to the magnitude of the pre-human frost'1 air (2) The change in the input box, which should be operated It is possible to provide a relay for detecting the width of change in electrical quantity and a protection switching system that reliably identify changes that do not require operation, thereby significantly improving the reliability of the power supply of the system.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional furrow sweeping change width detection relay.
FIG. 2 is an operating characteristic diagram of the relay shown in FIG. 1di1, FIG. 3 is a block diagram of an embodiment of the present invention, FIG. 4 is a circuit diagram of the variable level detector shown in FIG. The figure is a time chart when the pre-input current is small or large in Figure 3 [2], Figures 7 and 9 are block diagrams of other embodiments of the present invention, and Figure 8 is a book different from Figure 4. This is a circuit diagram of the variable level detector of the invention. 1... Bandpass filter circuit 2... Difference detection circuit 3
．． 11...Level detection circuit 4.12...Return delay circuit 5...Variable sensitivity level detection circuit 6...Current amount change width detection element 7...Full wave rectifier circuit 8...Smoothing circuit 9...Comparator IO...Operation delay circuit 13...Inversion circuit 14...Auxiliary relay (8733) Agent Patent attorney Yoshiaki Inomata (and 1 other person) Figure 3A Figure 4 Figure 5 Figure Cθθ7 Figure 7. −−11−−−〜−−−−−−11−−111−
--------Figure 8 Figure 9 B

Claims (1)

[Scope of Claims] (1) A band-pass filter circuit that introduces a current taken out from an electric power system, and a difference detection that inputs the output of this band-pass filter circuit and the current of the electric power system and detects the difference between the two input electric quantities. circuit, a current change width relay comprising a level detection circuit which inputs the output electricity of the difference detection circuit, generates an output when the input electricity is equal to or higher than a set level, and can switch the set level by an external signal; A protection relay (which is constructed of a sensitivity switching circuit that introduces the current extracted from the power system and switches the set level of the level detection circuit to the low sensitivity side C when the magnitude of the current is equal to or higher than the current reference value) 2) The safety relay according to claim 1, wherein the detection of the magnitude of the current is comprised of a smoothing circuit and a comparison circuit, or a level detection circuit and a recovery delay circuit. (8) The protective relay according to claim 1, wherein the operating sensitivity is either a DC reference amount of the level detection circuit or an input electricity amount. (4) The sensitivity switching device is the FIT of the level detection circuit.
The electrical appliance according to claim 1, which is constituted by a switch or a contact of a cross-over auxiliary relay.