JPH0731220B2 - Hot wire insulation deterioration diagnosis device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a device capable of quickly and simultaneously diagnosing insulation deterioration of a rotating machine winding, a CV insulated cable, or the like by various diagnostic methods in a live state. Is.

(Prior art and its problems) In order to ensure stable power transmission in a power system without power failure, the insulation state of rotating machines, cables, transformers, etc. that compose the system is highly accurate in the actual use state, that is, the live line state. Ideally, non-destructive diagnosis is possible.

By the way, conventionally, it is well known that the maximum level of the partial discharge pulse generated at the time of insulation deterioration, that is, the apparent maximum discharge charge qmax, the increase Δtan δ of the loss angle (tan δ), and the increase ΔI of the alternating current (capacitance current). Insulation deterioration diagnosis method, and further, an insulation deterioration diagnosis method utilizing the fact that the skewness of the φ-q distribution, which is the partial discharge phase characteristic based on the present inventors, changes based on insulation deterioration (Tokukai Sho 60-203866). (See No.) and other various diagnostic parameters are used together to compensate for the merits and demerits of insulation deterioration diagnosis by each method, and highly accurate insulation deterioration diagnosis is performed.

However, in such a conventional method, various diagnostic parameters as described above are separately obtained by using different measuring devices. Therefore, the measurement work is complicated and requires a lot of time, which leads to an increase in the work cost, and the price of the entire measurement device becomes expensive.

In addition to this, a major drawback is that when measuring the increase Δtan δ of the loss angle and the increase Δl of the alternating current among the above-mentioned diagnostic parameters, it is well known that the operation of the rotating machine or other diagnostic object is stopped, that is, during measurement. There is a drawback that power transmission must be stopped.

(Object of the Invention) In the present invention, not only the partial discharge phase characteristic, that is, the deterioration of the skewness of the φ-q distribution and the maximum discharge charge qmax, but also the loss angle which is conventionally obtained by a separate measuring device in a non-active state. In order to solve the above-mentioned problems of the conventional method, diagnostic parameters such as the increase Δtan δ of the AC current and the increase ΔI of the AC current are simultaneously and easily obtained by a single measuring device in a live state. It is a thing.

(Means of the Present Invention for Solving Problems) The present invention detects a partial discharge pulse generated due to insulation deterioration, for example, a void defect, and measures during t seconds (a plurality of cycles), for example, as shown in FIG. Such partial discharge pulse signal data group is (qi, φi) i = 1 ... n (where qi and φi are the magnitude of the i-th pulse, the phase angle of the i-th pulse, and the number of measured pulses, respectively) age,
The number n of pulses having a size q of this partial discharge pulse data group is taught, and n (q) as a function of the pulse size q, that is, the q-n distribution of the cycle average and the cycle of the applied voltage phase angle φ per cycle It is possible to obtain the maximum discharge charge qmax, the increase in loss angle Δtanδ, and the increase in charging current ΔI by obtaining q (φ), which is the average pulse height q of φ as a function of φ, that is, φ-q distribution. Was made clear. That is, the maximum discharge charge qmax is a constant pulse generation frequency n (q)
Since it is defined as the pulse detection level when qm, qm that satisfies the following equation (1) using the qn distribution
It can be obtained by calculating ax.

The increase Δtanδ of the loss angle is obtained using the φ-q distribution. That is, the current formula without partial discharge is Further, the current equation in the case of partial discharge is given as I '(φ) = I (φ) + q (d).

Here, if the loss angle tanδ without partial discharge and the loss angle with discharge tanδ 'are defined as Δtanδ = tanδ'-tanδ Is given as here Therefore, by knowing the current I from the measured voltage and the rated capacity of the device to be diagnosed, Required by. In the range where the loss angle is not so large, that is, tanδ <<, | q (φ) | << I, cosδ1, qtan
Since it is considered to be δ0, Required by.

If the effective value of the alternating current without partial discharge is I, the increase ΔI of the charging current is the current with partial charge.
Id (φ) is the same as when calculating the loss angle (Where q (φ) is the partial discharge current per phase angle) and the effective value Ie of Id is Given by.

Here, the increment ΔI [%] of the charging current is, by definition, a ratio of I to the difference between the effective value Ie of the alternating current when there is partial charging and the effective value I of the alternating current when there is no partial discharge. . Therefore, if the current I is known from the measured voltage and the rated capacity of the insulation deterioration diagnosis device, ΔI is Required by.

Therefore, from the above, as shown in the principle circuit diagram shown in FIG. 2, the ground line current in the live state of the insulation deterioration diagnosing device (1) is detected by the current detector (2) such as a current transformer, and q- n
In addition to the distribution [n (q)] measuring device and the [phi] -q distribution [q ([phi])] measuring device (3), the q-n distribution output of the calculated outputs is used to calculate the maximum discharge charge qmax. In addition to (4),
In addition, the φ-q distribution output is added to the computing unit (5) of the increase amount Δtanδ of the loss angle to which the AC current is applied when there is no partial discharge, and the computing unit (6) of the increase amount ΔI [%] of the AC current. Then, for example, the calculations of the above formulas (1), (3), and (4) are executed, and the measurement result of the φ-q distribution is added to the skewness calculator (7). It is possible to simultaneously, easily and quickly obtain the values in a live state by using individual measuring devices. Next, the present invention will be specifically described with reference to examples.

(Embodiment) FIG. 3 is a block circuit diagram of an embodiment of the present invention. In the figure, CT is a current transformer, and detects the ground line current of the insulation deterioration diagnostic device M. BF is a bandpass filter, which detects a partial discharge pulse from the detected ground line current. AM is an amplifier, which constitutes a partial discharge pulse detection circuit A and detects a partial discharge pulse.

B is a phase angle discriminating signal generating circuit, of which SV is a synchronizing signal input terminal, and the voltage applied to the insulation deterioration diagnosis device M by an existing transformer or a capacitor voltage divider,
That is, the voltage e of FIG. 4 (a), which is the system voltage lowered, is applied as the synchronizing signal voltage. ZC is a zero-cross signal generating circuit, which sends out a pulse generated at the zero point of the synchronizing signal voltage e as shown in FIG. 4 (b). CD is a phase angle division pulse oscillation circuit, PC is a phase counter,
The CD outputs a pulse signal having a frequency higher than the frequency of the synchronizing signal voltage e, and the phase counter PC counts the phase angle division pulses from the oscillating circuit CD using the pulse signal from the zero-cross signal generating circuit ZC as a synchronizing signal. Then, for a predetermined count, one cycle of the sync signal voltage e as shown in FIG.
A phase angle division pulse is transmitted for each point obtained by dividing 360 ° into N equal parts.

C is a detection circuit of nq distribution and φ-q distribution, of which PH is a peak hold circuit, AS is an auto threshold circuit, and the peak hold circuit PH is the output of the partial discharge pulse detection circuit A. Is input and the peak level is held every time a partial discharge pulse above the threshold level set by the auto-threshold circuit AS is input. AD is an analog-digital conversion circuit, PS is a polarity determination circuit, TO is a totaling circuit, the totaling circuit TO is a phase angle division pulse from the phase counter PC, the output of the peak hold circuit PH and the polarity determination circuit PS. Partial discharge pulses generated in N phase angle sections of each cycle in the measurement period (a plurality of cycles) using the output as an input, for example, FIG. 4 (d) (e) (f)
As shown in (g), in the first cycle, q _10.1 , q
_{13.1 ,,} q _90.1 , q _10.2 , q _37.2 , q in the second cycle
_45.1 , q _6.3 , q _13.3 , q _15.3 , q in the 3rd cycle
_{46.3 In} the Nth cycle, q ₃ n, q ₁₀ n, q ₁₅ n, q ₃₄ n, q
_40.n , q _44.n (Note that the first number in the foot _print is the phase angle classification number,
The next foot mark indicates the cycle number) and the applied voltage phase angle characteristic of the occurrence frequency of the partial charge pulse, that is, the sill mean distribution of φ-n is obtained. At the same time, the peak level values of the partial discharge pulses obtained by the peak hold circuit PH are tabulated for each phase angle section as shown in FIG. 4 (g), and the apparent discharge charge q and the generated phase angle φ are calculated. The cycle average distribution of the distribution (φ-q distribution) is obtained.

D is a calculation display circuit, of which BM is a buffer memory, CP
U is a microcomputer, PR is a printer, and the microcomputer CPU reads the φ-n distribution and the φ-q distribution from the totaling circuit TO stored in the buffer memory BM after one measurement period, and the maximum is calculated by the above-mentioned equations. Discharge charge qma
x, loss angle increment Δtanδ, and AC current increment Δ
I is calculated, and the skewness of the φ-q distribution is calculated and printed out.

Next, examples of the present invention will be described.

Table 1 shows the maximum discharge charge qma according to the present invention and the conventional method measured on the windings of a generator with a voltage of 6.6 KV and a capacity of 10,000 kVA.
It is a comparison between x, the increase amount of loss angle Δtan δ, and the increase amount of charging current ΔI, and the diagnostic accuracy is almost the same as the conventional diagnostic method in the non-active state.

(Effects of the Invention) As described above, according to the present invention, only by measuring the partial discharge pulse, not only the maximum discharge charge qmax but also the increase amount of the loss angle Δta
nδ and the charging current increase ΔI can be measured simultaneously without using dedicated measuring instruments. Therefore, not only the cost of the measuring device can be reduced as compared with the conventional method, but also the measurement time can be shortened and the work can be facilitated, so that the cost required for the insulation diagnosis can be significantly reduced. In addition to this, the maximum discharge charge and the like can be measured in a live state, so that the diagnostic accuracy can be improved. In the above, qmax, Δtanδ, ΔI
Although the above is measured at the same time, it goes without saying that only the necessary ones can be measured by selectively operating the arithmetic circuit.

[Brief description of drawings]

FIG. 1 is a partial discharge pulse generation state diagram, FIG. 2 is a diagram explaining the principle of the present invention, FIG. 3 is a circuit diagram of one embodiment of the present invention, and FIG.
The figure is a waveform diagram for explaining the operation. (1) …… Insulation deterioration diagnosis device, (2) …… Current detector, (3) …… Detector for nq distribution and φq distribution,
(4) ... calculator for maximum discharge charge, (5) ... calculator for increase in loss angle Δtanδ [%], (6) ... calculator for increase in alternating current ΔI, (7) ... φ-q distribution skewness calculator, M ... Insulation deterioration diagnosis device, CT ... Current transformer, BF ...
Band pass filter, AM ... Amplifier, B ... Phase angle division signal generator, SV ... Synchronous signal input terminal, PT ... Transformer, ZC ... Zero cross signal generator, CD ... Clock pulse oscillator, PC ... Phase counter, C ... nq and φ-q distribution detection circuit, PH ... Peak hold circuit,
AS ... Auto threshold circuit, AD ... Analog
Digital conversion circuit, PS …… Polarity discrimination circuit, TO …… Totaling circuit, D …… Computation display circuit, BM …… Buffer memory, CPU
…… Microcomputer, PR …… Printer.

Claims (1)

[Claims] 1. A circuit for detecting a grounding wire current of an apparatus for diagnosing insulation deterioration in a live state, a distribution q of partial discharge pulses detected by this circuit and a distribution of the number of occurrences n, and the partial discharge pulse. A circuit for obtaining the distribution of the magnitude q and its generated phase angle φ as a cycle average in a plurality of measurement cycles, a circuit for calculating the maximum discharge charge qmax using the qn distribution by this circuit, and the φ-q distribution The increase in loss angle Δtan
A circuit for calculating δ, a circuit for calculating the increment ΔI of the charging current by using the φ-q distribution and I of the insulation deterioration diagnosis device, and a circuit for calculating the skewness of the φ-q distribution. Prepare,
Diagnosis of hot-line insulation deterioration by enabling maximum discharge charge qmax, loss angle increment Δtanδ, charging current increment ΔI, and skewness of φ-q distribution to be measured simultaneously or individually in a live state. apparatus.