JPS61109420A - Protective relay device - 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 protection relay device that detects and protects changes in magnetic current in a magnetic transmission line of a power system.

[Technical background of the invention and its problems]

Overcurrent relays are generally used as relays for detecting faults in power transmission lines. However, in a power transmission line with a large load current such as a heavily loaded power transmission line, the set value of the overcurrent relay becomes smaller than the load current, and the overcurrent relay may operate constantly. In such cases, a current change relay is used, which operates by detecting the change in current. In this relay, the current change is small during normal times, but the change becomes large in the event of an accident. It detects failures.

However, conventional current-changing relays have the problem of malfunction due to frequency changes.

[Purpose of the invention]

An object of the present invention is to obtain a highly reliable protective relay device that does not malfunction even when the system frequency changes.

[Summary of the invention]

The present invention includes a current variation range detection element for detecting changes in grid current of a power system and a frequency detection element, and is configured to reduce the sensitivity of the current variation range detection element by the output of the frequency detection element when the frequency fluctuates. The current change 111 detection element includes a first detection element and a second detection element whose sensitivity is lower than that of the first detection element. A protective relay device characterized in that the first detection element is controlled by the output of the frequency detection element, and the output of the first detection element of the magnetic current change range detection element is an output controlled by the output of the frequency detection element. , second
A protective relay device is provided, characterized in that the output of a detection element is configured to meet a logical sum condition.

That is, the protective relay device according to the present invention is characterized in that a frequency detection element is added, and the sensitivity of the magnetic current variation range detection element is lowered by the output of the frequency detection element.

[Embodiments of the invention]

Next, examples of the present invention will be described.

Figure 1 shows a detection element 6A that detects changes in the alternating current flowing through the power system, and a secondary side of 6 detection elements and 5 units of parallel C secondary side connected to each other, and the sensitivity is lowered than that of the 6 detection elements. A signal obtained by inverting the frequency detection signal 7a from the frequency detection element 7 by the logic negation circuit 8 8a, and an AND circuit 9 that outputs the AND condition of the current detection signals 6c from the six C two detection elements, and the logic of the AND output signal 9a of the AND circuit 9 and the current detection signal 6d from the detection element 6B. A protective relay device is shown which includes an OR circuit 10 that outputs a sum condition.

That is, in the embodiment not shown in FIG. 1 (2), the system current ■ is introduced into the current variation range detection element 6. It consists of a second detection element 6B set to low sensitivity.On the other hand, the system' magnetic pressure V is introduced into the frequency detection element 7.The output of the frequency detection element 7 passes through the NOT circuit 8 and then goes to the AND circuit 9. In addition, the output of 4 (iA) is also introduced into the AND circuit 9, and the AND circuit 9 is introduced into the OR circuit 101n.Detection of the magnetic current change range detection element 6 is required. The output of the element 6B is also introduced into the OR circuit 1042, so that the output of the OR circuit 10 becomes the final output 10A of the relay device.

The frequency detection element 7 has the frequency characteristics shown in FIG.
In addition, an insufficient frequency state below the setting value fI and a setting of 11k
It has a function of detecting and outputting an overfrequency state of ft or more. For example, in the frequency characteristics shown in FIG. 2, the set value f1 of the underfrequency is set to 0.9910 (10=fundamental frequency), and the set value f1 of the overfrequency is set to 1.01f0. The frequency is now 0.98/.

If this is the case, the operating source (gain) of the current variation range detection element 6 will be approximately 0.5 times the characteristic shown in FIG. 2, for example, and malfunction will occur easily. On the other hand, since the system frequency is 0.9810, the frequency detection element 7 naturally operates and generates an output.

The output of the frequency detection element 7 is turned ON by the NOT circuit 8C2 and is introduced into the AND circuit 9. Even if the six detection elements of the current variation range detection element 6 operate and output, the output of the NOT circuit 8 is "ON", so the output of the AND circuit 9 is "O". For example, in the detection element 6B, the detection height of the level detection circuit of the detection element 6B is increased to make the operating sensitivity 1/2 of that of the six detection elements.
If the sensitivity is low enough, the second detection element 6B will not operate and its output will be 0. Therefore, the output of the OR circuit 10 will be 0.
'', and the final output is θ'', so there is no risk of malfunction.

On the other hand, suppose that an accident occurs in the grid and the frequency drops, for example, to 0.98fo. At this time, the six detection elements operate and output. Since the frequency of the frequency detection element 7 is less than the set value 0.99f0, it naturally operates, so the output of the NOT circuit 8 becomes ``+''.The input of the AND circuit 9 becomes 1'' and 0'', so the AND circuit 9 The output of is '0'.

The detection element 6B of the current change range detection element 6 is set to have lower sensitivity than the 6 detection elements, or the frequency is 0.98f0, and the current change is caused by a failure in the system. It is operational and emits output. Since the inputs of the OR circuit become 0'' and 1'', the final output of the relay device becomes 1'', making it possible to detect an accident.

In the embodiment shown in Fig. 1 (in Fig. 2, the frequency detection element 7 is used, and the current change range detection element 6
Since the sensitivity of the sensor is set to low sensitivity, there is no risk of malfunction.

In the embodiment shown in FIG. 1, the frequency detection element 7 is configured to generate an output at underfrequency and overfrequency, that is, output "1" at frequency fluctuation.

In the embodiment shown in FIG. 8, the frequency detecting element 7 is configured to output an output "O" when the frequency fluctuates, and in this case, the NOT circuit 8 is unnecessary.

Furthermore, in the embodiment shown in FIG. 1, the frequency was detected using the system voltage in the frequency detection element 7, but the fourth
As in the worst embodiment, the same effect can be obtained even if ≦Two frequency detection required $7 (Two system currents are introduced and the current change range detection element 6 and the input are shared. By sharing the voltage, an effect can be obtained in that the instrument transformer and input conversion circuit required in the embodiment of FIG. 1 are not required.

〔Effect of the invention〕

Since the sensitivity of the current change detection element is changed from this to the output element, a highly reliable protective relay device that does not malfunction when the frequency fluctuates can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the protective relay device according to the present invention, FIG. 2 is an explanatory diagram of frequency characteristics of the protective relay device according to the present invention, and FIGS. 8 and 4 are respective diagrams of the protective relay device according to the present invention. FIG. 3 is a block diagram showing another different embodiment. 6...Current change range detection element 7...Frequency detection element 8...NOT circuit 9...AND circuit 10...OR circuit l) Agent Patent attorney Noriyuki Chika (1 other person) ) Figure 1 7α 2B! !

Claims (1)

[Claims] a first detection element that detects changes in alternating current flowing through the power system; and a primary side connected in parallel to the first detection element, and set with lower sensitivity than the first detection element. a second detection element, a frequency detection element that detects that the frequency of the power system has changed to a predetermined set value, and a frequency detection signal from this frequency detection element, or a signal that is an inversion of this frequency detection signal. , and an AND circuit that outputs an AND condition of the current detection signal from the first detection element, and an OR condition of the AND output signal of this AND circuit and the current detection signal from the second detection element. A protective relay device comprising an OR circuit that outputs