JP2614285B2 - Method for removing residual output waveform from zero-phase output waveform detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a residual output of a zero-phase output waveform detection device provided with a three-phase output waveform sensor for detecting a voltage or a current (hereinafter referred to as an output waveform) of a distribution line. It relates to a waveform removal method.

[Related Art] Conventionally, for example, as a voltage sensor for detecting an AC voltage, a transformer for an instrument, a capacitor-divided type transformer for an instrument, an optical transformer for measurement, and the like have been proposed. However, each of the voltage sensors has a problem in weight or price.

Therefore, the present applicant has already proposed the zero-phase voltage detecting device Z shown in FIG. 7 as a combination of three voltage sensors having a simple configuration. Describing the zero-phase voltage detection device Z, the voltage sensors Su, Sv, Sw are arranged at a predetermined interval l with respect to the three-phase distribution lines Lu, Lv, Lw, and the voltage sensors Su, Sv, Sw A shield electrode 1 for shielding an external electric field except for the corresponding distribution lines Lu, Lv, Lw; and a distribution line Lu, Lv, Lw and a capacitance C provided in the shield electrode 1.
and u, Cv, and Cw, and a detection electrode 2 that collects the potential of the distribution lines Lu, Lv, and Lw.

Then, in a sound distribution line, the detection signals νu, νv, νw from the respective voltage sensors Su, Sv, Sw are processed by a signal processing circuit 3 including an amplifier circuit and a band-pass filter, and then subjected to three-phase synthesis. Then, the zero-phase output is set to 0 and input to the zero-phase voltage detector 4.

On the other hand, when a ground fault occurs in the distribution lines Lu, Lv, Lw, the three phases become unbalanced and the zero-phase output does not become 0, indicating the failure.

However, in the above-described zero-phase voltage detection device Z, three-phase detection unbalance due to the unbalanced installation of the voltage sensors Su, Sv, Sw arranged for each phase, that is, generation of an initial residual output waveform can be suppressed. It was difficult. Therefore, there is a problem that the zero-phase output does not exactly become 0, and an initial residual output waveform exists in the zero-phase output despite the occurrence of a short circuit or a ground fault.

In order to solve this problem, the applicant of the present invention stores initial residual output waveform data based on an initial residual output waveform generated when three phases are combined in a storage unit, and synchronizes with the period of the initial residual output waveform by a control unit. Alternatively, a zero-phase output waveform detecting device that outputs a zero-phase output waveform by subtracting a signal based on the initial residual output waveform data stored in the storage means from the signal based on the output waveform at the time of the measurement in substantially synchronization. An initial residual output waveform removal method is proposed.

[Problems to be Solved by the Invention] However, the above-mentioned conventional method for removing the initial residual output waveform,
Once the initial residual output waveform data is stored, it is repeatedly used as it is for the subtraction processing. Therefore, even when the residual output waveform changes due to an error factor such as a temporal change of the output waveform sensor or the transmission path, the initial residual output waveform is not changed. There is a problem that the fluctuations cannot be accurately corrected and the accuracy of the zero-phase output cannot be improved.

By the way, a method of sequentially storing new residual output waveform data in a predetermined cycle in the storage means for storing the residual output waveform data is conceivable. In this case, as shown in FIG. When an accident waveform is input, the accident waveform is stored, and thereafter, there is a problem that the residual output waveform cannot be corrected normally.

An object of the present invention is to provide a zero-phase output waveform which can obtain a zero-phase output in which a residual output waveform generated when a signal from each phase output waveform sensor provided for voltage or current detection is synthesized is removed with high precision. An object of the present invention is to provide a method of removing a residual output waveform of a detection device.

Means for Solving the Problems The present invention has been made to achieve the above object, and the invention according to claim 1 is a method for producing a residual signal generated when combining output waveform signals from a three-phase output waveform sensor. The output waveform signal is stored as basic residual output waveform data by the first storage means for a plurality of cycles, the subsequent residual output waveform signal is stored as the current residual output waveform data by the second storage means for a plurality of cycles, and the control means controls the second storage means. After calculating the respective averaged waveforms of the basic residual output waveform data and the current residual output waveform data, the zero-phase output waveform signal is output by subtracting the averaged waveform of the current residual output waveform from the averaged waveform of the basic residual output waveform. Further, when the zero-phase output waveform signal is equal to or less than a set value, the basic residual output waveform data and the current residual output waveform data are compared. The storage is sequentially updated, and when the zero-phase output waveform signal is equal to or larger than a set value, the storage operation to the first storage means is regarded as an accident waveform, and the addition average waveform of the previous basic residual output waveform is subtracted. The method is used for processing.

According to a second aspect of the present invention, in the first aspect of the present invention, the basic output waveform signal and the current residual output waveform signal are added and averaged as digital signals and then subjected to a subtraction process.

According to a third aspect of the present invention, in the first aspect, the basic residual output waveform signal and the current residual output waveform signal are fetched in synchronization with the synchronization signal from the synchronization signal generating means.

[Operation] In the first aspect of the present invention, a residual output waveform due to three-phase imbalance generated at the time of installation from the output waveform sensor is stored by the first storage means as basic residual output waveform data. The next input residual output waveform is stored in the second storage means as the current residual output waveform data. Then, the control means subtracts the addition average waveform of the basic residual output waveform signal from the addition average waveform of the current residual output waveform signal, and outputs the subtraction result, that is, the zero-phase output waveform signal.

When the zero-phase output waveform signal is equal to or greater than a set value,
Since this is regarded as an accident output waveform and is not stored in the first storage means, an accident output waveform containing no residual component is output.

As described above, according to the first aspect of the present invention, even when the residual output waveform changes due to an error factor such as an aging of the output waveform sensor or the transmission path, the changed residual output waveform is reliably removed, and the zero-phase output is reduced. The accuracy of is improved.

According to the second aspect of the present invention, both the current residual output waveform signal and the basic residual output waveform signal are subjected to subtraction processing as digital signals, so that the influence of error factors due to temperature changes and the like when an analog subtraction circuit or the like is used. Is prevented.

Further, according to the third aspect of the present invention, even when a deformed waveform is generated in which a harmonic component is superimposed on the current residual output waveform signal, the subtraction processing is performed accurately.

[Embodiment] An embodiment in which the present invention is embodied in the output difference correction circuit of the zero-phase voltage detection device z shown in FIG. 7 will be described below with reference to the drawings.

In FIG. 1, reference numerals 6, 7, and 8 denote input terminals to which detection signals vu, vv, and vw output from the voltage sensors Su, Sv, and Sw shown in FIG. It is. OP1 is an operational amplifier, the inverting input terminal of which is connected to the input terminals 6, 7, 8 via resistors R1, R2, R3. Further, the non-inverting input terminal of the operational amplifier OP1 is grounded via a resistor R4, and the output terminal is connected to the inverting input terminal via a resistor R5.

The operational amplifier OP1 and the resistors R1, R2, R3, and R5 form a combining circuit that combines the detection signals vu, vv, and vw to obtain a zero-phase output waveform (hereinafter, referred to as a zero-phase output). Therefore,
At the point A on the output terminal side of the operational amplifier OP1, when the distribution line is normal, as shown in FIG.
A zero-phase output including a residual voltage νψ is applied as a residual output waveform due to three-phase imbalance from v and Sw.

Then, as shown in FIG. 6, when a ground fault occurs in the distribution line Lw, the fault voltage E (= Voε) as a fault output waveform in which the unbalanced output component Vo is superimposed on the residual voltage νψ.
+ Νε) is applied.

An output terminal of the operational amplifier OP1 is connected to an A / D converter 10 for digitizing the residual voltage νψ or the fault voltage E via a coupling capacitor C for cutting a DC component. The A / D converter 10 is connected to a central processing control circuit (hereinafter referred to as CPU) 11 as control means for calculating the residual voltage νψ or the fault voltage E.

Reference numeral 12 denotes a read-only memory (hereinafter, referred to as ROM) connected to the CPU 11, which stores a control program, and controls and drives the CPU 11 based on the control program.

Reference numeral 13 denotes a plurality of first memory buffer groups A1 to An as first storage means, a plurality of second memory buffer groups B1 to Bn as second storage means, and a sampling memory buffer Mb (FIG. 3). ), And temporarily stores output waveform data and a result calculated by the CPU 11. Each of the memory buffers A1 to An and the memory buffers B1 to Bn stores one cycle of residual output waveform data, and stores a total of 2n cycles.

On the other hand, the inverting input terminal and the non-inverting input terminal of the open collector type voltage comparator COMP are connected to the input terminals 15 and 16 of the sine waveform synchronizing signal. Resistance to pull up to level
R6 is connected. The point B is connected to the CPU to extract the zero-cross timing of the sine waveform synchronization input signal to obtain a square wave output signal (not shown).

Reference numeral 18 denotes a reset circuit connected to the CPU 11,
A reset switch 18a is provided.

Reference numeral 19 denotes an oscillation circuit connected to the CPU 11, which generates a reference clock.

Reference numeral 20 denotes a D / A converter, which converts a digital zero-phase output waveform signal output from the CPU 11 into an analog signal and outputs the analog signal.

D is connected to the inverting input terminal of the operational amplifier OP2 via the resistor R7.
The / A converter 20 is connected, and the point C provided on the output side of the operational amplifier OP2 and the inverting input terminal are subjected to negative feedback via the variable resistor R8. Further, the non-inverting input terminal of the operational amplifier OP2 is grounded via a resistor R9. Then, a zero-phase output that does not include the residual voltage νψ and becomes zero or a zero-phase output that includes an accident waveform is output to the output terminal 21. The magnitude of the zero-phase output including the fault waveform can be appropriately adjusted by the variable resistor R8.

Next, the operation of the output difference correction circuit of the zero-phase voltage detection device z configured as described above will be described with reference to FIGS. 2 (a) and 2 (b).
This will be mainly described.

First, as shown in step 1 of FIG. 2 (a), it is determined whether a synchronization signal has been input, and when the synchronization signal has been input, initialization is performed in step 2 (variable m is set to 1). The first buffer A1 out of the first memory buffer groups A1 to An is designated.

Next, in step 3, the current residual output waveform data is stored in the memory buffer A1 for one cycle. In addition, 2
Designation of the memory buffer A2 and the memory buffer A2
Similarly, the current residual output waveform data for the subsequent one cycle is stored as the basic residual output waveform data, and the operations of steps 3 to 5 are sequentially repeated, and the set number of times n
Only, that is, data of n cycles are stored as basic residual output waveform data in the first memory buffer groups A1 to An. In steps 6 to 9, the basic residual output to the first memory buffer groups A1 to An described above is performed. Similarly to the operation of storing the waveform data, the second memory buffer groups B1 to Bn
Are sequentially stored as current residual output waveform data.

Note that the above storage operation is performed prior to the next normal processing operation because no data is stored in both memory buffer groups A1 to An and B1 to Bn at power-on or reset operation.

Next, when the synchronizing signal is input again in step 10, further new current residual output waveform data is stored in the sampling memory buffer Mb for one cycle.

Subsequently, the basic residual output waveform data for the n cycles of the first memory buffer groups A1 to An are summed and divided by the set number of times n to store the basic averaged waveform (step 1).
2).

Further, the current residual output waveform data for the n cycles of the second memory buffer groups B1 to Bn are summed, divided by the set number n, and the current averaged waveform is stored (step 13).

Next, in step, the basic averaging waveform is subtracted from the current averaging waveform, and in step, the subtraction result is output to the D / A converter.

In step 16, the currently added closed waveform of step 13 or step 13 'described later is subtracted from the current residual output waveform data of the sampling memory buffer Mb. Then, it is determined whether or not the subtraction result is equal to or greater than the set value in step 17.
If it is equal to or greater than the set value, it is determined that an accident output waveform has occurred, and the flow branches to an accident processing routine, in which memory shift operations in the first memory buffer groups A1 to An described later are not performed. In step 10 ', when the synchronizing signal is input, new current residual output waveform data is stored in the sampling memory buffer Mb for one cycle as in step 11 described above. (Step 11 ′) Further, in Step 13 ′, similarly to Step 13, the current residual output waveform data for n cycles of the second memory buffer groups B 1 to Bn are summed and divided by the set number n to obtain the current averaged waveform. Is stored.

Next, in step 14 ′, the current average waveform is subtracted from the new current residual output waveform data stored in the sampling memory buffer Mb.
Outputs the subtraction result to the D / A converter 10.

On the other hand, as a result of the accident determination processing, when it is determined that the waveform is not an accident output waveform, the data stored in the first memory buffer groups A1 to An and the second memory buffer groups B1 to Bn are sequentially memory-shifted, and the next averaging is performed. It becomes data for operation and subtraction processing. This memory shift processing operation will be described in detail with reference to FIG.

In this operation, first, in step 18, initialization (variable m = 2) is performed, and data in the memory buffer Am is input to Am-1. Thereafter, this operation is sequentially repeated until m = n, and after m = n, and the updating of the data in the memory buffers A1 to An-1 is completed,
The data of the memory buffer B1 is input to the memory buffer An. In this way, the memory buffers A1 to An have A2 to B1
Are sequentially memory-shifted.

Next, also in the memory buffers B1 to Bn, the variable m = 2
Is initialized, the data in the memory buffer Bm is
1 is input. This is sequentially repeated. The output waveform data of the memory buffers B2 to Bn is shifted to the memory buffers B1 to Bn-1. Subsequently, normal data in the sampling memory buffer Mb is input to the memory buffer Bn, and thereafter, the process returns to the normal processing operation described above.

 Next, a second embodiment of the present invention will be described with reference to FIG.

In the second embodiment, a count memory buffer Mb shown in FIG.
I'm using Mc.

The newly input current residual output waveform is directly stored in the memory buffer Bn of the second memory buffer groups B1 to Bn. When the first cycle of the accident output waveform is input, the basic waveform of the output waveform data described in both memory buffer groups A1 to An and B1 to Bn and the subtraction result of the averaging waveform are the accident output waveform data. About 1 / n of the data is output,
In addition, the accident waveform is considerably larger than the residual output waveform level, and even if the average is 1 / n, the level can be easily detected.

Therefore, in the second embodiment, when the subtraction result exceeds a certain set value in step 28 of FIG. 4, it is determined that an accident has occurred, and in step 29, the set number n is stored in the count memory Mc. , The first memory buffer group A1 to An
Without performing the memory shift operation described above, the flow branches to the above-described step 23, and only the second memory buffer groups B1 to Bn are sequentially subjected to memory shift.

Here, storing the set number n in the count memory Mc is an initial setting for counting the number of residual output waveforms after the accident recovery described later.

If the result of the subtraction is equal to or less than the set value, in step 30 the count number n stored in the count memory Mc
Is reduced by 1 to n−1, and the process proceeds to step 31. Thereafter, when the current residual output waveform including no accident waveform is continuously input, the count memory Mc decreases by one. In the meantime, the process branches to step 23 described above, and the memory shift operation of the first memory buffer groups A1 to An is not performed, and
Only the memory buffer groups B1 to Bn are shifted in memory.

Further, when the current residual output waveform that does not include the accident waveform is input for n consecutive cycles, the count memory Mc becomes 0, and the routine branches to a normal memory shift processing routine, and both memory buffer groups A1 to An and B1 to Bn Is memory shifted.
Thereby, the basic residual output waveform is held without the accident waveform being memory-shifted and stored in the memory buffer groups A1 to An.

When the accident output waveforms are continuously input, the result of the subtraction process increases sequentially from 1 / n of the accident output waveform level, and finally becomes an accident output waveform that does not include the residual output waveform. Conversely, even if the accident waveform is no longer input,
The result of the subtraction process gradually decreases and approaches zero.

 The present invention can be embodied as follows.

(1) In the above-described embodiment, the voltage comparator COMP is used to output a synchronization signal based on a sine wave synchronization signal input from the outside. However, a synchronization signal is output based on the oscillation circuit 19 instead. Be generated internally.

(2) In the above embodiment, the basic residual output waveform signal and the current residual output waveform signal are subjected to the subtraction processing as digital signals, but the subtraction processing is performed as an analog signal.

(3) The present invention is embodied in a method for removing a residual output waveform of a current sensor.

[Effects of the Invention] As described above in detail, the invention according to claim 1 performs the subtraction processing based on the residual output waveform even when the residual output waveform changes due to an error factor such as a temporal change of the output waveform sensor and the transmission path. Thus, there is an effect that a zero-phase output can always be obtained accurately.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, the effect of preventing the influence of an error factor due to a temperature change of an analog subtraction circuit or the like can be prevented, and the accuracy can be further improved. is there.

Further, in addition to the effect of the first aspect, the third aspect of the present invention provides a normal subtraction process even when a harmonic component of an input residual waveform is superimposed by a synchronization signal and a deformed output waveform appears. Thus, there is an effect that accuracy can be improved.

[Brief description of the drawings]

FIG. 1 shows a first embodiment in which the present invention is embodied in a zero-sequence voltage detecting device.
2 (a) and 2 (b) are flowchart diagrams, FIG. 3 is a block diagram showing a RAM, FIG. 4 is a flowchart diagram showing a second embodiment of the present invention, FIG. And FIG. 6 is a vector diagram showing the output from each voltage sensor;
FIG. 7 is a diagram showing an installation state of a voltage sensor, and FIG. 8 is a graph showing a residual output waveform and a waveform stored in a RAM in a conventional example. 10 A / D converter, 11 CPU, 12 ROM, 13 RAM,
20: D / A converter, OP1, OP2 ... operational amplifier, COMP ... voltage comparator, A1 to An (B1 to Bn) ... first (second) storage means as first (second) storage means Memory buffer group, Z: Zero-phase voltage detector, Mb: Sampling memory buffer, Su, S
v, Sw: output waveform sensor, vψ: residual voltage.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Fumiaki Kono 1st character small needle in Inuyama-shi, Aichi Energy Support Co., Ltd. (56) References JP-A-63-274322 (JP, A) JP-A-62-214369 (JP, A)

Claims (3)

(57) [Claims] A first storage means stores a residual output waveform signal generated when combining output waveform signals from a three-phase output waveform sensor as basic residual output waveform data for a plurality of cycles, and stores a subsequent residual output waveform signal. A plurality of cycles are stored as the current residual output waveform data by the second storage means, and the control means calculates the respective average waveforms of the basic residual output waveform data and the current residual output waveform data. The zero-phase output waveform signal is output by subtracting the addition average waveform of the current residual output waveform from the average waveform.If the zero-phase output waveform signal is equal to or less than a set value, the basic residual output waveform data and the current The storage of the residual output waveform data is sequentially updated, and when the zero-phase output waveform signal is equal to or more than a set value, the first storage means is regarded as an accident waveform. Stop storing operation, the residual output waveform removal method of the zero phase output waveform detecting device characterized by using the arithmetic mean waveform of the previous basic residual output waveform to the subtraction process. 2. The residual output of a zero-phase output waveform detecting apparatus according to claim 1, wherein the basic residual output waveform signal and the current residual output waveform are digitally averaged and averaged and subtracted. Waveform removal method. 3. The zero-phase output waveform detection according to claim 1, wherein the basic residual output waveform signal and the current residual output waveform signal are taken in synchronism with a synchronizing signal from the synchronizing signal generating means. A method for removing the residual output waveform of the device.