JPH0548051B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an operation monitoring device for a transformer load tap switching device (hereinafter referred to as a tap changer), and in particular, by constantly monitoring the tap switching time, The present invention relates to a device for early detection of abnormality in a touch engineer.

[Conventional technology]

When changing the voltage ratio while power is being applied, the tap changer of a transformer temporarily shorts the taps to be changed in the tap windings in the transformer through a resistor or reactor, so in the unlikely event that the tap switching mechanism does not operate properly. In this case, an excessive short-circuit current will occur between the taps of the tap winding, leading to a major accident.

In order to prevent this accident and ensure normal operation of the transformer, we have traditionally monitored the number of times the tap-punch engineer operates and replaced parts when the number of operations reaches the specified number of times.
Although monitoring is carried out over a relatively long period of time, including the preparation time for switching operations when the tap engine is operating, it is not possible to monitor the short tap switching time, which is only a few tens of milliseconds, so we can identify precursor phenomena to abnormalities. is difficult and cannot be said to be sufficient as an abnormality prediction method.

On the other hand, during human patrol inspections, abnormalities may be discovered based on the difference between the tap changeover sound and the normal sound, but this auditory abnormality detection requires the patrolman to approach the transformer, and the This is limited to cases where various conditions are met, such as the switching operation being carried out and the patrolman being able to determine whether the target touch engineer is normal or abnormal based on the switching sound. This method required a high level of skill on the part of the patrol personnel, and it was not sufficient as an abnormality detection method, such as the inability to perform constant monitoring.

[Summary of the invention]

The present invention eliminates the drawbacks of the conventional touch engine monitoring method described above, performs constant monitoring, detects the actual tap switching time of several tens of milliseconds, and processes the judgment, thereby automatically controlling the touch engine. The purpose is to detect abnormalities early.

To achieve this object, the present invention provides an operation monitoring device for a load-time tap switching device for a transformer of a switching type in which a current limiting means short-circuits the tap winding when the tap is switched. a first current detecting means for detecting a first superimposed current in which a bridge current and a load current flowing in a first current limiting means connected to the first tap are superimposed when switching to the first current limiting means; a second superimposed current in which a bridging current and a load current flowing through a second current limiting means connected to the second tap are superimposed when the first tap is switched to the second tap; The current detecting means of No. 2 and the logical sum of the first and second superimposed currents are used to determine the duration time, and the duration time is determined in proportion to the reference normal tap switching time to determine whether there is an abnormality in the tap switching device under load of the transformer. a determination means for determining the presence or absence of the
An operation monitoring device for an on-load tap switching device for a transformer, characterized by comprising:

[Embodiments of the invention]

FIG. 1 is a block diagram of a monitoring device showing an embodiment of the present invention, in which 1 is a tap winding of a transformer, 2 is a tap engine body connected to tap leads 3A to 3C from tap winding 1. Tap selector fixed contacts 4A to 4C, tap selector movable contacts 5A and 5B, current limiting resistor (or reactor, etc.) 6A to suppress short-circuit current when switching taps
6D, fixed arc contacts 7A to 7F, and movable arc contacts 8A to 8F which are connected to and released from the fixed arc contacts 7A to 7F from the switching drive mechanism 10 via the insulated drive shaft 9 are built in. 11A and 11B are current sensors that detect the current flowing through the current limiting resistors 6A to 6D, 12 is a transformer operation monitoring device, and 13A and 13B are converters of the signals of the current sensors 11A and 11B into predetermined electrical signals according to the magnitude of the current. 14A and 14B are signal comparison circuits, 15 receives a signal from either of the two signal comparison circuits 14A and 14B,
an OR circuit that outputs an open signal to the gate circuit 17;
16 is a pulse generation circuit, 18 is a pulse counter circuit, and 19 is a judgment processing circuit. In the figure, the solid arrow line indicates the signal transmission path, the broken arrow line indicates the reset signal path from the judgment processing circuit 19 to the pulse counter circuit 18, and the arrows i1 and i2 indicate the signal transmission path to the current limiting resistors 6A to 6D. The flowing current,
And i _L indicates the load current.

In the operation monitoring device for the transformer on-load tap switching device configured as described above, when switching the tap position from the tap selector fixed contact 4B to 4C, the tap selector movable contact 5B is first connected to the tap fixed contact 4C. Ru. Next, the switching drive mechanism 10 moves the movable arm contacts 8A to 8F through the insulated drive shaft 9 from right to left toward the page, that is, movable arc contacts 8A to 8
They are combined with fixed arc contacts 7A to 7F toward F, and are switched by short-circuiting or opening two pairs at a time. At this time, tap leads 3B and 3C of tap winding 1 are connected to, for example, current limiting resistor 6B, contacts 7C, 8C and contacts 8D, 7.
D and current limiting resistor 6C, and as shown in _FIG . A superimposed current i ₁ or i ₂ will flow. As is clear from Fig. 2, the time during which current flows through the current limiting resistors 6A to 6D becomes the actual tap switching time, and at this time, in order to open and close the short circuit current, the fixed arc contacts 7A to 7F and the movable arc contact 8A An arc is generated between ~8F, but the switching drive mechanism 10 has a built-in quick-acting device using a spring, etc. to shorten the arc time in order to reduce oil contamination in the touch engine 2 and contact wear. The rotational power from the switching drive mechanism 10 is transmitted to the movable contact 8 through the insulated drive shaft 9.
A to 8F are transmitted and switched in about tens of milliseconds.

This actual tap switching time of several tens of milliseconds becomes irregular when a failure occurs in the switching drive mechanism 10 or the like, and becomes longer than the normal time.

When switching the taps of the tap engineer 2, the current flowing to the current limiting resistors 6A to 6D is reduced.
i ₁ and i ₂ are connected to current sensors 11A and 11 such as optical CT.
The signals from sensors 11A and 11B are converted into signal converters 13A and 13B, respectively.
is converted into a predetermined electrical level signal and guided to the signal comparison circuits 14A and 14B, and the internally set reference value is converted into a current i ₁ in the signal comparison circuits 14A and 14B.
Alternatively, if i ₂ exceeds, a signal is sent to the OR circuit 15 to open the gate circuit 17 for the duration of the current i ₁ or i ₂ . The OR circuit 15 opens the gate circuit 17 in response to the gate opening signal from either of the two signal comparison circuits 14A and 14B, and also outputs the same signal as the gate circuit 17 to the judgment processing circuit 19.

Next, the gate circuit 17 allows the pulse from the pulse generation circuit 16 to pass through to the pulse counter circuit 18 only while receiving the gate open signal. The pulse counter circuit 18 counts the pulse signals that have passed through the gate circuit 17 and outputs the counted pulse signals to the judgment processing circuit 19. The judgment processing circuit 19 receives the gate open signal from the OR circuit 15, and as shown in Fig. 2, when this signal stops (actually, a certain period of time after the stop is considered to be the end of switching), the pulse counter The output from the circuit 18 is read and the pulse counter circuit 18 is reset.

Next, the judgment processing circuit 19 converts the actual tap switching time from the output value of the pulse counter, and compares it with the normal actual tap switching time preset in the judgment processing circuit 19, and compares the measured actual tap switching time with this set time. If the switching time is longer, the touch engineer 2 determines that there is an abnormality and outputs an alarm. At this time, the abnormality may be determined by comparing an integral multiple N of the set time with the measured actual tap switching time.

In the embodiment shown in FIG. 1 above, the preset actual tap switching time and the measurement time were compared, but as another embodiment, as shown in the block diagram of FIG.
The block diagram in the figure shows the data storage/arithmetic processing circuit 20.
By providing a data storage/arithmetic processing circuit 20, data such as measured actual tap switching time is stored, and the frequency distribution of the recorded data as shown in FIG. If a statistical processing function is added that determines an abnormality when the value is longer than an integer multiple (for example, 3σ) of the standard deviation value σ from the average value (o), more accurate abnormality prediction becomes possible.

〔Effect of the invention〕

As described above, the present invention provides an effective tap switching time, which is a precursor phenomenon of abnormality in the tap engine, in a switching type transformer load tap switching device (tap engine) in which a short circuit is caused by a resistor or the like during tap switching. This system provides a monitoring device that detects abnormality or signs of abnormality in the touch engine by detecting the current flowing through the resistor.Compared to conventional monitoring methods, it automatically monitors the switching operation during operation and detects failures. This has the effect of allowing early detection of signs.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
Fig. 2 is a graph showing the relationship between the current in each part of the touch engine and the actual tap switching time, Fig. 3 is a block diagram showing another embodiment of the present invention, and Fig. 4 is a measurement of the actual tap switching time. A histogram diagram showing frequency is shown. In the figure, 1 is a tap winding, 2 is a tap changer on load, and 6A to 6D.
is a current limiting resistor, 11A, 11B are current sensors, 1
2 is an operation monitoring device, 13A and 13B are signal conversion circuits, 14A and 14B are signal comparison circuits, and 15 is an OR
16 is a pulse generation circuit, 17 is a gate circuit, 18 is a pulse counter circuit, 19 is a judgment processing circuit, and 20 is a data storage/arithmetic processing circuit.
Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. In an operation monitoring device for a load-time tap switching device for a transformer of a switching type in which a current limiting means short-circuits a tap winding when the tap is switched from the first tap to the second tap. , a first current in which the bridging current flowing through the first current limiting means connected to the first tap and the load current are superimposed.
a first current detection means for detecting a superimposed current of the tap; and a bridge current flowing into a second current limiting means connected to the second tap when switching from the first tap to the second tap. a second current detection means for detecting a second superimposed current in which the current and the load current are superimposed, and a duration time of the logical sum of the first and second superimposed currents, and this duration is set as a reference normal tap switching time. 1. An operation monitoring device for a transformer on-load tap switching device, comprising: determination means for determining whether or not there is an abnormality in the on-load tap switching device of the transformer. 2. The determination means includes first and second signal conversion circuits that convert the signals of the first and second current detection means into appropriate electrical signal levels, and outputs of the first and second signal conversion circuits. Common to the first and second signal comparison circuits are first and second signal comparison circuits that compare each signal with a value corresponding to a reference normal current value and generate an output signal only when the former is higher than the latter; a connected OR circuit; a circuit that generates a pulse signal and counts it only while the first or second signal comparison circuit connected to the OR circuit is generating an output signal; and When the switching time exceeds the standard normal actual tap switching time by converting it into an actual tap switching time, it is determined that the tap switching device under load of the transformer is abnormal and an alarm signal is issued. 2. An operation monitoring device for a transformer on-load tap switching device according to claim 1, characterized in that the device includes a judgment processing circuit that generates a signal. 3. The determination means includes first and second signal conversion circuits that convert the signals of the first and second current detection means into appropriate electrical signal levels, respectively, and the outputs of the first and second signal conversion circuits. Common to the first and second signal comparison circuits are first and second signal comparison circuits that compare each signal with a value corresponding to a reference normal current value and generate an output signal only when the former is higher than the latter; an OR circuit connected to the OR circuit; a circuit connected to the OR circuit that generates a pulse signal and counts it only while the first or second signal comparison circuit is generating an output signal; The tap switching time is converted into tap switching time and stored, and the frequency distribution of this stored data is calculated. If the tap switching device is outside the range of a predetermined integral multiple of the standard deviation value calculated from this, it is determined that the tap switching device is abnormal when the transformer is loaded, and an alarm signal is generated. An operation monitoring device for a transformer on-load tap switching device according to claim 1, further comprising a data storage/arithmetic processing circuit.