JPH0279719A - Ground protective relay for generator - Google Patents

Abstract

PURPOSE:To catch the abnormality of a generator previously by monitoring the voltage characteristics of a third harmonic wave obtained from an actual machine data and protective characteristics set in a setting memory by a CRT, liquid-crystal display, etc. CONSTITUTION:Third harmonic voltage 7 from a generator neutral-point grounding transformer 6 and generator load currents 9 acquired from a current transformer 8 are input to an input conversion means 11 in a generator ground relay 10. An input voltage characteristic curve 4 is obtained by an input-voltage characteristic arithmetic means 13. The data 14C of C of a protective setting characteristic curve 5 and the data 14A of the input voltage characteristic curve 4 are compared by a comparison means 17, and a trip contact or an alarm contact 18 is turned ON and an alarm signal 19 is output when the value of the data 14A exceeds the value of the data 14C. Accordingly, trouble is diagnosed easily.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Field of Application) The present invention is directed to a generator ground fault that detects a ground fault in the stator winding of a generator to prevent the spread of generator failure. Regarding short circuit protection relays.

(Prior Art) A ground fault protection relay for a generator uses both an overvoltage detection method that outputs zero-sequence voltage in the event of a failure and an undervoltage detection relay method that detects third harmonic voltage. One type of undervoltage detection relay is used to protect the 10% ground fault on the neutral side of one generator winding by converting the third harmonic that is constantly generated in one generator armature coil to voltage using a neutral point grounding device. This third harmonic voltage is detected by utilizing the fact that the ground fault point becomes smaller as it gets closer to the neutral point of the generator. When setting the protection characteristics of generator ground fault protection relays equipped with these methods, it is possible to set the protection of one-type overvoltage detection relay using zero-sequence voltage reliably based on the results of theoretical calculations. However, it is difficult to calculate the protection setting for a one-type undervoltage detection relay using the third harmonic voltage on a desk, so the first generator is operated after the protection setting has been estimated, and at that point the third adjustment is performed. The wave voltage was actually measured and the protection settings were reconfigured based on that data.

(Problems to be Solved by the Invention) As described above, in the voltage detection relay type, which performs ground fault protection by detecting the zero-sequence voltage that appears in the generator neutral grounding device in the event of an accident, the impedance and Reliable protection setting is possible by calculation using constants such as capacitance. However, 10% of the neutral point side of the generator winding
In one type of undervoltage relay that uses the third harmonic voltage appearing in the neutral grounding device to protect against ground faults, the third harmonic is determined by the slot shape of the generator rotor and their arrangement.

Also, the magnetic saturation state of each part of the rotor and armature.

Alternatively, it is virtually impossible to theoretically grasp the voltage characteristics of the third harmonic that appears in the generator neutral point grounding device because it varies depending on the load condition of the generator.

For this purpose, we actually measured the above voltage characteristics for each generator.

Protection characteristics are established based on the measured data.

In addition, since the generator ground fault protection relay is manufactured assuming the voltage characteristics of the third harmonic that is cursed by the generator neutral point grounding device, it is not possible to obtain ideal protection characteristics in accordance with the measurement data. In addition, there is a problem in that if the measured data and the voltage characteristics that have been prepared in advance do not match, it is necessary to rebuild the generator ground fault protection relay.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a digital protection setting device for a generator that can easily obtain protection setting characteristics based on actual machine data.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides an input voltage characteristic calculation means for calculating input terminal characteristics of a third harmonic voltage with respect to a generator load current; automatic setting calculation means for calculating a protection setting characteristic taking into account a predetermined tolerance value α by an automatic algorithm based on the characteristics calculated by the automatic setting calculation means; and a setting storage means for storing the protection setting characteristic calculated by the automatic setting calculation means; It is comprised of an external means display device for displaying a characteristic curve, and a comparison means for comparing the output of the input voltage characteristic calculation means and the output of the setting storage means.

(Function) According to the present invention, the third
It is possible to accurately and easily understand the voltage characteristics of harmonics, and 1. The generator ground fault protection relay protects 10% of the ground fault on the neutral point side of the generator armature. The third that appears on the neutral grounding device to do! l! When setting the protection of a one-way undervoltage relay using one wave, the protection is set based on predictions, then the generator is operated, and then the protection characteristics of the equipment are collected based on actual machine data and readjusted, without any manual intervention. This has the advantage of being able to be stabilized.

According to the present invention, since the 1-generator earth fault protection relay is manufactured with the voltage protection characteristics of the third harmonic assumed in advance, the relay may be damaged due to the incoordination with the voltage characteristics of the third harmonic obtained from the actual machine data. It is possible to eliminate the need for re-creation, etc. Furthermore, the automatic setting algorithm built into the relay enables ideal protection setting in accordance with the voltage characteristics of the third harmonic obtained from actual machine data.

According to the present invention, the voltage characteristics of the third harmonic obtained from actual machine data and the protection characteristics set in the setting memory can be CR
Since it is possible to monitor using an external device such as a T or a liquid crystal display, abnormalities in one generator can be known in advance, and it is also possible to know when it is time for repair.

(Example) FIG. 1 is a block diagram explaining the principle of the present invention, and FIG. 2 is a characteristic diagram showing the input voltage characteristics of the third harmonic voltage of the generator and its protection setting characteristics.

The actual machine data calculation means 1 actually measures and calculates the input voltage characteristic curve 4 of the third harmonic voltage in the generator shown in FIG.
Automatic setting calculation means 2 based on this input voltage characteristic curve 4
A protective settling characteristic curve 5 is calculated by taking into account the allowable value α using the automatic setting algorithm. This protective settling characteristic curve 5 is then stored in the settling storage means 3.

In this state, updating of the setting storage means 3 is prohibited.

During operation of the generator, the actual machine data calculation means 1 compares the input voltage characteristic curve 4 with the protection setting characteristic curve stored in the setting storage means 3, and the value of the input voltage characteristic curve 4 is determined to be that of the protection setting curve 5. When the value exceeds this value, a trip signal for the protective relay is output.

FIG. 3 shows a specific embodiment of a ground fault protection relay for a generator according to the present invention.

In FIG. 3, the third harmonic voltage 7 obtained from the generator neutral point grounding transformer 6 and the generator load current 9 obtained from the current transformer 8 are converted into input converting means 11 in the generator ground fault relay IO.
Enter. The input conversion means 11 converts the digital signal 12B corresponding to the amount of change in the third harmonic voltage 7 and the digital signal 12A corresponding to the amount of change in the generator load current 9, and converts these digital signals 12A and 12B into the input voltage characteristic calculation means 13. send to The input voltage characteristic calculation means 13 calculates the generator load current 9 based on the digital signals 12A and 12B on an X-Y coordinate with the generator load current on the X axis and the third harmonic voltage on the Y axis. The amount of change in the third harmonic voltage 7 with respect to the change is obtained. That is, as shown in FIG. 2, an input voltage characteristic curve 4 is obtained.

The data 14A calculated by the input voltage characteristic calculation means 13 is manually inputted to the automatic setting calculation means 15 having an automatic setting algorithm. The automatic setting calculating means 15 obtains the protection setting characteristic curve 5 by an automatic setting algorithm based on the data 14A of the input voltage characteristic curve 4 calculated and obtained by the input voltage characteristic calculating means 13.

The data 14B calculated by the automatic setting calculation means 15 is sent to the setting storage means 16. The setting storage means 16 stores the data 14G of the protection setting characteristic curve 5 sent from the automatic setting calculation means 15, and also sends the data 14c to the comparison means 17.

Here, the setting storage means 16 is provided with a switch 20 for determining whether or not to store the data 14B of the protective setting characteristic curve 5 from the automatic setting calculation means 15, and this switch 20 stores the protective setting characteristic once set. is prevented from being updated due to changes in the data 14B sent from the automatic settling calculation means 15.

Further, a manual setting switch 21 is provided in case the protection setting characteristics are changed manually.

In the comparison means 17, data 1 of C of the protection setting characteristic curve 5
Compare 4C with data 14A of input voltage characteristic curve 4,
When the value of the data 14A of the input voltage characteristic curve 4 exceeds the value of the data 14C of the protection setting characteristic curve 5, the trip contact or the alarm contact 18 is turned ON, and the trip signal or
An alarm signal 19 is output.

The external interface 22 includes a CRT 23 and a computer 2.
4, and external interface 2.
By connecting 2 and CRT 23, input voltage characteristic curve 4 and protection setting characteristic curve 5 can be monitored.

[Effects of the Invention] As explained above, according to the present invention, it is possible to automatically set the protection setting of the generator ground fault protection relay without the trouble of setting it after collecting actual machine data, and also Ideal setting that matches the characteristic curve is possible. or,
Since the interface with an external monitoring device is facilitated, fault diagnosis is also facilitated, and a highly reliable generator ground fault protection relay can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a block diagram explaining the principle of the present invention, Fig. 2 is a characteristic diagram showing the input voltage characteristic curve of the third harmonic voltage of the generator and its protective setting characteristic curve, and Fig. 3 is a detailed diagram of the present invention. FIG. 1 is a configuration diagram of a generator ground fault protection relay showing an example. l...actual machine data, 2...automatic setting calculation means, 3.
... Setting storage means, 4... Input voltage characteristic curve, 5...
・Protection setting characteristic curve, 6... Neutral point grounding device, 7...
- Third harmonic voltage, 8... Current transformer, 9... Generator load current, IO... Generator earth fault protection relay, 11... Input conversion means, 12... Digital signal, 13... Input voltage characteristic curve calculation means, 14... Data, 15...
- Automatic setting calculation means, 16... Setting storage means, 17.
... Comparison means, 18... Trip contact or alarm contact,
19... Trip signal or alarm signal, 20... Switch, 21... Manual setting switch, 22... External interface, 23... CRT, 24... Computer. (7317) Agent Patent Attorney Aide Kensuke (886
9) Ken Daishimaru Figure 2 Figure 3

Claims (1)

[Claims] In a ground fault protection relay for a generator that detects a ground fault in a stator winding of the generator, an input voltage characteristic calculation means for calculating the amount of change in the third harmonic voltage with respect to the generator added current, and an input voltage characteristic calculation means an automatic setting calculation means for calculating protection setting characteristics by an automatic algorithm based on the characteristics calculated by the automatic setting calculation means; a setting storage means for storing the protection setting characteristics calculated by the automatic setting calculation means; and an external device capable of monitoring each of the above characteristics. 1. A ground fault protection relay for a generator, comprising: a display device; and comparison means for comparing the output of the input voltage characteristic calculation means and the output of the setting storage means.