JPH0216096B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a protective relay, and particularly to a protective relay that introduces electrical quantities of multiple phases.

[Conventional technology and its problems]

Generally, an undervoltage relay with current compensation is used as a failure detection device for a power system. This undervoltage relay with current compensation introduces the current I and the voltage V of the power system, respectively, and has characteristics that change depending on the current at the time of a failure, as shown in FIG. FIG. 2 shows an example of its configuration. Here, we will explain the short-circuit failure detection relay installed in the RS phase as an example.

In the figure, the quantity of electricity V〓 is the quantity of electricity proportional to the line voltage V〓 _RS , and the quantity of electricity I〓Z〓 is the current I〓 _R −I〓 _S (however,
_I〓R ,
I〓 _S is the electrical quantity obtained by shifting the phase currents of the R phase and S phase, respectively, by the line impedance angle or an angle approximating it (hereinafter simply referred to as the line impedance angle), and Z〓 means the settling impedance. do.
Furthermore, each output of rectifier circuit (REC) 1 and 2 is |V〓|,
|I〓Z〓|, and these are introduced into the addition/subtraction circuit (ADD) 3 to obtain the quantity |V〓|−|I〓Z〓|. This output is introduced into the level detection circuit (LD) 4 at the next stage, where the level is compared with a predetermined value K, and |
When V〓｜−｜I〓Z〓｜＞K, level detection circuit (LD)
4 sends out a logical value "1". Time limit circuit (T)5
sends out an output when the output of the level detection circuit (LD) 4 has a logic value of "0" for a certain period of time.

However, when detecting faults in the power system, for example in the case of a direct-to-ground system, it is necessary to install the above-mentioned relays for each phase to detect short circuits and ground faults, and the disadvantage is that the scale of the equipment increases in this case. have.

[Purpose of the invention]

The present invention has been made with the aim of solving the above-mentioned drawbacks, and aims to provide a protective relay that can protect multiple phases by introducing electric quantities of multiple phases and is small in scale. The purpose is

[Summary of the invention]

The present invention introduces a plurality of electrical quantities from the power system into a selection circuit, and sequentially selects one or more required electrical quantities from among them in response to a signal from the microcomputer, and then selects one or more electrical quantities from among them in sequence, thereby transmitting the electrical quantities to the microcomputer via a comparison circuit. The system is designed to perform a selection switching operation and perform a series of protection calculations according to a predetermined program.

[Embodiments of the invention]

Examples will be described below with reference to the drawings.

FIG. 3 is a configuration diagram of an embodiment of a protective relay according to the present invention. In the figure, V〓 and I〓Z〓 are RS and T, respectively.
It is the electrical quantity of the phase. Reference numeral 6 denotes a selection circuit which incorporates electronic or electromagnetic switches SW ₁ to _{SW 6} , and the outputs of the switches SW ₁ to _{SW 3} are sent out as a signal S ₁ , and the switches SW ₄ to _{SW 6} output is signal
Sent as S ₂ . The opening and closing of each of the switches is controlled by a control signal _S6 from a digital processing circuit (MPU) 11 using a microcomputer or the like, which will be described later. Rectifier circuit (REC) 7 is a signal
The signal _S3 is obtained by half-wave rectification of the _S2 output. The comparison circuit 8 introduces the signals S ₁ and S ₃ respectively,
It consists of a well-known adder/subtractor 9 that obtains these combined quantities e _x and a comparator (LD) 10 that compares the magnitude of a predetermined value e _r with the combined quantity. Output of comparison circuit 8
S ₄ is a digital processing circuit (hereinafter referred to as MPU) 11
According to the internally stored program, the MPU 11 selects and controls the input by the selection circuit 6, takes in the output S ₄ of the comparison circuit 8, and outputs the polyphase protection outputs S _5R , S _5S , and S _5T . Decide and output.

FIG. 4 is a program for explaining the operation of the protective relay according to the present invention. In the figure, step _a1 sends a control signal _S6 to the selection circuit 6,
Processing is performed to close switches SW ₁ and SW ₄ . Step _a2 is the comparator output _S4 , that is, the comparator input
A signal S ₄ that detects whether the combined amount _ex of S ₁ and S ₃ is equal to or higher than a predetermined level _er is taken in, and processing is performed to branch the program step according to the value. step
A ₃ and a ₄ perform a process of counting up or resetting their count values, respectively, based on the value of S ₄ above. In step _a5 , the program is branched depending on whether the count value exceeds a predetermined value M or not. Then, based on the result of step a ₅ above, step a _6-1
outputs a protection output S _5R =1, and step _a6-2 performs processing to output a protection output S _5R =0. Step _a7 , like step _a1 above, sends a control signal _S6 to the selection circuit 6 and closes the switches _SW2 and _SW5 , and the following steps _a8 to _a12 are the same as step a above. ₂ -a Perform processing according to ₆ . Furthermore,
Steps _a13 to _a18 also perform processing similar to _a1 to _a6 above, and step _a19 performs processing of other calculation elements, such as monitoring calculations.

Next, the operation of the protective relay having the above configuration will be explained according to a program. In the program shown in FIG. 4, at step _a1 , switches SW ₁ and SW ₄ of the selection circuit 6 are closed, and switches SW ₂ , SW ₃ ,
SW ₅ and SW ₆ are controlled to be open. In this state, the selection circuit 6 outputs only V _R and I _R Z _R , which are sent to the adder/subtractor 9 as a signal S ₁ and to the rectifier circuit (REC) 7 as a signal S ₂ . on the other hand,
In the rectifier circuit (REC) 7, the signal S ₂ is half-wave rectified and applied to the adder/subtractor 9 as a signal S ₃ . In the adder/subtractor 9, e _x =V〓−｜I〓Z〓｜ from the signals S ₁ and S ₃
is obtained and compared with a constant value e _r in the comparator (LD) 10, and the output S ₄ becomes _{S 4 =}
1. When V〓−|I〓Z〓|<e _r, S ₄ =0. Step _a2 in FIG. 4 introduces the signal _S4 and performs branch processing according to its value. That is, when S ₄ = 1, the process branches to step a ₄ and the count value of the counter is set to 0.
to be reset. On the other hand, in step a ₂ S ₄
When =0, the process branches to step _a3 and the count value of the counter is incremented by 1. In step _a5 , it is determined whether the count value exceeds a predetermined value M or not. In steady state, the reset period of the counter is approximately 360 degrees in electrical angle, so
The value of M above is selected to be 360°+α. step a ₅
Step when the count value exceeds M in
Branch to a _6-1 and send out protection output S _5R as 1.
Also, if the count value does not reach M, step
a Branch to _6-2 and perform processing to reset the protection output _S5R to 0. After that, the process branches to step _a7 . In step _a7 , the control signal _S6 is sent out again in the same manner as in step _a1 , switches _SW2 and _SW5 in the selection circuit 6 are closed, and the following steps are performed.
The processing up to _{step a18} is carried out in a manner similar to steps _a1 to _a6 described above. In step _a19 , processing such as automatic monitoring calculation is performed, and then the process returns to step _a1 , and the series of processes described above are repeated at regular intervals.

In the above explanation of FIG. 3, the comparator circuit 8
Although S ₁ and S ₃ are combined by the adder/subtractor 9 and then compared in magnitude with the reference amount er in the comparator ₁₀ , the comparison circuit is not limited to this configuration. That is, after combining the signal S ₁ or S ₃ and the reference amount e _r in the adder/subtractor 9, the comparator 10
The configuration may be such that the magnitude is compared with the signal S ₃ or S ₁ at . Furthermore, the signals S ₁ , S ₃ and the reference e _r may be simultaneously introduced into the adder/subtractor.

Figure 5 shows the signal waveform diagram, where the signal S ₁ is V〓, the signal
This is a waveform diagram when the switches SW ₁ and SW ₄ maintain the closed circuit state by changing S ₃ to |I〓Z〓|. The three input quantities of R, S, and T of V〓, I〓Z〓 are cyclically introduced by the control signal _S6 , and the input _ex to the comparator 10 is given in time series. That is, e _x = (V〓−
|I〓Z〓|) Values at each time point t=t ₀ , t ₁ , t _{2 .} . . of the waveform are sequentially input to the comparator (LD) 10 and compared with a constant value e _r .

That is, in the figure, at t = t ₀ and t ₁ , it is less than the constant value e _r , but at t = t ₂ , it exceeds e _r ,
The output S ₄ of the comparison circuit 8 therefore delivers S ₄ =1. However, in the steady state, e _r is still exceeded even at t _C+2 after one cycle t _c , but in the next cycle t=t _2C+2 when a system abnormality occurs, e _x < e _r
As a result, S ₄ =0 is transmitted. This is done chronologically for each phase of R, S, and T, and the MPU 11 identifies the signals while identifying them.
Incorporating S ₄ . By the above operation, V〓−|
The period during which the magnitude of I〓Z〓｜ is less than a predetermined value is the electrical angle
When the angle continues for 360°+α or more, an operational output is obtained and the phase characteristics shown in Figure 1 are realized.

FIG. 6 is a block diagram of another embodiment. Reference numerals 6 to 11 and other signals in the figure correspond to those in FIG. (REF) 12 is a reference quantity generating circuit, which is connected to the comparator (LD) 10 and configured to change the reference quantity e _r in response to a control signal S ₇ from the MPU 11 . Therefore, the MPU 11 sends a control signal _S6 to the selection circuit 6 and a reference amount generation circuit (REF).
The control signal S ₇ for 12 is outputted, the output S ₄ from the comparator circuit is introduced, and the same protection operation as explained in FIG. 3 is performed.

FIG. 7 shows an embodiment of the reference amount generating circuit. That is, a well-known digital/analog conversion circuit is used as the reference amount generating circuit 12.
Digital input via control signal _S7 from MPU11
A predetermined digital code is given to D _1N , and the analog signal corresponding to the digital code is the reference amount.
Output from Vout as e _r .

The digital code given to the digital input D _1N is the setting value of the protective relay, and a code corresponding to the above setting value is given from outside the MPU 11 by a digital switch or the like, and is given to the reference amount generation circuit 12 via the MPU 11. It's okay. Alternatively, the output of the digital switch or the like may be supplied to the linear reference quantity generating circuit 12, and this may be supplied as the reference quantity to the comparator (LD) 10.

FIG. 8 is a block diagram of another embodiment. Reference numerals 6, 8, 9, 10, and 11 in the figure correspond to those in FIG. (REC ₁ ) 13 is a rectifier circuit that allows only positive waves to pass through. (REC ₂ ) 14 is also a rectifier circuit that allows only negative waves to pass through. Reference numeral 15 denotes a second selection circuit consisting of switches SW ₇ and SW ₈ , whose switching is controlled by a control signal S ₇ from the MPU 11. Reference numeral 16 denotes a third selection circuit, which has a switch SW ₉ for the reference amount + _er and a switch SW ₁₀ for the reference amount _-er . and these are
This is performed using a control signal _S8 from the MPU 11.
In addition, by the control signal _S6 from the MPU 11, _V〓R ,
Deriving the signal S ₁ by switching V〓 _S , V〓 _T and I〓 _R
As described above, the signal S ₂ is derived by switching Z〓 _R , I〓 _S Z〓 _S , I〓 _T Z〓 _T.

FIG. 9 is a timing chart showing the process of generating the input e _x of the comparator (LD) 10. Positive wave of I〓Z〓｜
Using I〓Z〓｜ ⁺ , negative wave｜I〓Z〓｜ ^- , V〓−｜I〓Z〓｜
^± is formed and applied to the comparator (LD) 10. Reference amount + e _r
Alternatively, the magnitude comparison with _−er can ^be performed using the control signals S ₇ and S ₈ from the MPU 11, respectively.
−|I〓Z〓| ^- is selected and executed.

FIG. 10 is an embodiment of a flowchart showing program processing. In the figure, in step _b1 , the MPU 11 sends a control signal _S6 to switch the input of the selection circuit 6, and in the next step _b2 , the control signal S6 is sent out from the MPU 11 to switch the input of the selection circuit 6.
S ₇ and S ₈ are sent out, and the switch of the second selection circuit 15 is activated.
By closing SW ₇ and closing switch SW ₉ of the third selection circuit 16, the positive wave of I〓Z〓 and the reference amount +
e _r is selected. Steps _b3 to _b6 are similar to steps _{a2 to a5} explained in FIG _.
and the switch SW ₁₀ by the third selection circuit 16 are both controlled to close, and the negative wave of I〓Z〓 and the reference amount _-er are selected.

Then, the branching step of S ₄ in step b ₈ leads to step b ₁₀ which resets the counter NCNT 1 to 0 when S ₄ =0, and resets the counter NCNT ₁ to 0 when S ₄ =1.
Select one of Step b ₉ to increase NCNT ₁ by +1. That is, when a positive wave is input, the counter PCNT ₁ is turned up when S ₄ is 0, and when a negative wave is input, the counter NCNT ₁ is turned up when S ₄ is 1, and both counters are set to the predetermined value M. When the value exceeds 1, the protection output _S5R is set to 1 and output in step _b12-1 . Each step b ₁₃ below
Step _b36 is processed in accordance with steps _b1 to _b12 described so far. Thereafter, other processing is performed in step _b37 , and the program returns to step _b1 .

FIG. 11 shows a flowchart of another embodiment showing program processing. In this embodiment, the count-up is started when _S4 changes from 0 to 1. That is, in the figure, step _c1 performs processing that branches to steps _c2 and _c4 depending on the content of the control signal _S6 to the selection circuit 6. switch here
After closing SW ₁ and SW ₄ , proceed to step c ₂ and read the captured S _4. When S ₄ = 0, that is, the input e _x of the comparator (LD) 10 has a constant value e _r. If it is exceeded, branch to step _c3 . Here, the branch destination is determined by the sign of the condition label _Z1 . In FIG. 5, if the signal _S4 that has just been captured is at time t= _t2 , then at the time t= _t1 one before this, e _x < e _r , so step c shown in FIG. ₂
At the branch, proceed to step c ₄ and condition label Z ₁ is 0.
is set, and then a branch is made to step _c7 . Therefore, the step at time t=t ₂
The branch of _c3 proceeds to step _c5 , where _Z1 is reset to ₁ , that is, _Z1 changes from 0 to 1. After passing through step _c6 in which the counter _CNT1 is set to 0, a count-up is performed in which the counter is incremented by one in step _c7 . In step _c8 , as long as this count value does not reach the set value M, the process proceeds to step _c9-2 , where the protective output _S5R is set to 0, and the process proceeds to step _c10 , but when it exceeds the set value M, the process proceeds to step _c9-2. Proceed to ₁ and output the protection output S _5R as 1.
For example, if the calculation cycle is 4 degrees electrically (equivalent to t ₁ −t ₀ =0.22 ms in the 50 Hz system in FIG. 5), the above count value corresponds to 90+α counts. The following steps c ₁₀ to c ₂₇ are processed in accordance with steps c ₁ to _{c 9} described so far. Thereafter, other processing is performed in step _c28 ,
As in the previous embodiment, the program returns to step _c1 . In the above explanation, a counter method using program processing at a constant cycle has been used, but this counter function may be entrusted to a timer using hardware outside the MPU. That is, when counting up, the MPU outputs a count start signal for a hardware-based timer, and when the timer reaches a set value, the MPU is notified of this fact.

FIG. 12 is a configuration diagram of another embodiment. Reference numerals 6, 11, 13, and 14 in the figure correspond to those in FIG. 8-1 is a comparison circuit for positive waves, 8-2 is a comparison circuit for negative waves, and each circuit includes an addition/subtraction circuit 9-.
1, 9-2 and comparison circuits 10-1, 10-2. S _3-1 and S _3-2 are positive wave rectifier circuits (FEC ₁ )
13 and the negative wave rectifier circuit (REC ₂ ) 14, and are input to addition/subtraction circuits 9-1 and 9-2, respectively.

Therefore, the _S1 signal, which is the I〓Z〓 quantity and the V〓 quantity introduced into the positive wave rectifier circuit (REC ₁ ) 13, is sent to the addition/subtraction circuit 9.
-1, the _S1 signal, which is the I〓Z〓 quantity and the V〓 quantity introduced into the negative wave rectifier circuit (REC ₂ ) 14, is sent to the addition/subtraction circuit 9-2.
are introduced into _the MPU _{11 as signals S 4-1 and} S _4-2 , and are subjected to arithmetic processing according to the flowchart described above. .

FIG. 13 shows an embodiment of the rectifier circuit. That is, in this embodiment, a selection circuit is used to derive a positive wave rectified output and a negative wave rectified output. In the figure, (LD) 17 is a comparator in which the signal S ₂ from the selection circuit 6 is compared with 0V, and the signal S ₂
The signal _S9 is output only during the positive wave period. Reference numeral 18 denotes a selection circuit, in which the signal _S2 is inputted to the switch _SW12 , and at the same time, 0V is inputted to the switch _SW11 . These two switches are activated by the above signal _S9 .
SW ₁₁ and SW ₁₂ are controlled to open and close to obtain an output signal S ₃ '.
That is, when the signal S ₉ is a positive wave input, the switch SW ₁₂ is closed and S ₂ is output as S ₃ '.
On the other hand, when the signal _S9 is a negative wave input and is not sent out, the switch _SW11 is closed and 0V is output as _S3 '.

FIG. 14 is a configuration diagram of still another embodiment. Reference numerals 8 to 11 and 16 in the figure correspond to those in FIG. 19 is the first selection circuit and input amount
V _R , V _S , V _T and 0V are input, and the control signal S ₁₀ from the MPU 11 causes the switches SW ₁₃ to
By switching SW ₁₉ , the following electric quantities are obtained as outputs of the first addition/subtraction circuit 21. That is,
When SW ₁₃ and SW ₁₇ are closed, V〓 _R −V〓 _S , When SW ₁₄ and SW ₁₈ are closed, V〓 _S −V〓 _T , When SW ₁₅ and SW ₁₆ are closed, V〓 _T −V〓 _S Each of these is input to the comparator circuit 8 as a Δ amount. on the other hand,
SW ₁₃ , SW ₁₉ closed V〓 _R , SW ₁₄ , SW ₁₉ closed V〓 _S ,
When SW ₁₅ and SW ₁₉ are closed, _V〓T is input to the comparator circuit 8 as a quantity, respectively. 20 is the second selection circuit, and similarly to the above, I〓 _R Z〓 _R , I〓 _S Z〓 _S , I〓 _T Z〓 _T and 0V are the MPU
The second addition/subtraction circuit 22 is controlled by the control signal S ₁₀ from 11.
The amount of electricity shown below is obtained as the output. That is, when SW ₂₀ and SW ₂₄ are closed, I〓 _R Z〓 _R −I〓 _S Z〓 _R , SW ₂₁ , SW ₂₅
When closed I〓 _S Z〓 _S −I〓 _T Z〓 _T , SW ₂₂ , SW ₂₃ When closed I〓 _T Z〓 _T
−I〓 _R Z〓 _R
are each input to the rectifier circuit (REC) 7 as a Δ amount. On the other hand, when SW ₂₀ and SW ₂₆ are closed, I〓 _R Z〓 _R , SW ₂₁ ,
When SW ₂₆ is closed, I〓 _S Z〓 _S , when SW _{26 is} closed, I〓 _T Z〓 _T are respectively input to the rectifier circuit (REC) 7 as quantities.
The following operation is almost the same as that in Figure 3 or Figure 8, so it will be omitted, but the comparator (LD) 10
The reference amount of K is determined using the control signal _S8 from the MPU11.
Alternatively, switching by an amount of √3K is performed by the selection circuit 16. That is, when the amount Δ is input, the switch SW ₁₀ is closed and √3K is sent out, and when the amount is input, the switch SW ₉ is closed and K is sent out. Then, the comparator 10 determines the magnitude relationship between the reference amount and the output of the adder/subtractor 9, and the MPU
11.

In the above explanation, the current input I〓Z〓 is input to the selection circuit and then guided to the rectifier circuit, but in order to vary the magnitude, a variable gain circuit is inserted before or after the selection circuit, and this By sending the output to a rectifier circuit, the impedance Z can be made variable.

FIG. 15 is a configuration diagram of still another embodiment. That is, whereas the previous embodiment had a configuration in which the quantity and the Δ quantity were obtained using two selection circuits having 7 channels, this embodiment uses a configuration using 3 channels. Reference numerals 8, 11, and 16 in the figure correspond to those in FIG. 23
is the first selection circuit, and the voltage inputs V〓 _R , V〓 _S , V〓 _T
is input. 24 is a second selection circuit to which current inputs I〓 _R Z〓 _R , I〓 _S Z〓 _S , and I〓 _T Z〓 _T are respectively input. 25
is the first holding circuit, and the first selection circuit 23
Take V〓 _R from and hold it, then take V〓 _S ,
These form the Δ amount V〓 _R −V〓 _S in the addition/subtraction circuit 27 . These take in and operate in accordance with a control signal _S10 from the MPU 11, and then the holding voltage of the holding circuit 25 is reset by a control signal _S11 . A similar operation is performed for the second selection circuit 24 for current input. Other operations are as described above.

FIG. 16 shows another example of program processing. In this embodiment, from the viewpoint of reliability of the protective relay, the counter is incremented with S ₄ =0 only when S ₄ =1 continues n times (n is an integer). Therefore, in the flowchart of _FIG .
a ₂₀ , a ₂₁ , a ₂₂ , and a ₂₃ are added, and similar additions are made to the branch routines of steps a ₈ and a ₁₄ .

First, when S ₄ =1 is read at step _a2 , the counter L is set to +1 at step _a20 . At the next counter _a21 , it is determined whether the count value L has reached a predetermined value n, and if it has reached n, the counter L is reset to 0 at step _a22 , and then step a explained in FIG. Processing from ₅ onwards is performed. If S ₄ =0 is determined at step a ₂ in the next S ₄ read cycle, the counter L has already been reset to 0, so the branch of step a ₂₃ moves to step a ₃ and the counter L is reset to 0.
Count up CNT ₁ by +1. That is,
The period of S ₄ =0 is counted up only when S ₄ =1 continues n times in a row.

In the above explanation, the amount of electricity introduced was expressed as a quantity,
I compensated by zero-sequence current instead of I〓 _R , I〓 _S , I〓 _T
〓R ＋
KI〓 _O , I〓 _S + KI〓 _O , I〓 _T + KI _O (K is a constant) may be used.

Further, although the voltage amount is not rectified, a rectifier circuit may be added and the voltage amount may be introduced into the comparison circuit after half-wave rectification, as in the case of current input.

Furthermore, a single quantity relay function can be added by changing the control signal from the MPU 11 so that only voltage input or only current input is input. That is, it is possible to easily obtain an overvoltage relay by inputting the zero-sequence voltage amount, and an overcurrent relay using I〓Z〓 as input.

〔Effect of the invention〕

As explained above, according to the present invention, a plurality of electric quantities from the electric power system are introduced into the selection circuit, and the selection circuit selects the necessary one or more electric quantities among them by means of a signal from the microcomputer. Since the configuration is configured to select a quantity and perform a series of protection calculations, not only can a three-phase current-compensated undervoltage relay that introduces three-phase electrical quantities be constructed with extremely simple hardware, but also the characteristics of a single quantity relay can be configured. The reduction in the size of the device, especially the reduction in the number of parts, contributes to improving the reliability of the protective relay, and at the same time, it is possible to standardize the protective relay.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram of an undervoltage relay with current compensation.
FIG. 2 is a conventional configuration diagram for obtaining the characteristics shown in FIG. 1, FIG. 3 is a configuration diagram of an embodiment of the protective relay according to the present invention, FIG. is a signal waveform diagram, FIG. 6 is a configuration diagram of another embodiment of the protective relay, FIG. 7 is a configuration diagram of one embodiment of the reference amount generation circuit, FIG. 8 is a configuration diagram of another embodiment of the protection relay, and FIG. The figure is a signal waveform diagram, and Figure 10 is a flowchart of another embodiment of the calculation program.
FIG. 11 is a flowchart of another embodiment of the calculation program, FIG. 12 is a block diagram of another embodiment of the protective relay, and FIG. 13 is a block diagram of one embodiment of the rectifier circuit.
Fig. 14 is a configuration diagram of another embodiment of the protective relay, the first
Figure 5 is a configuration diagram of yet another embodiment of the protective relay, the first
FIG. 6 is a flowchart of yet another embodiment of the calculation program. 6, 19, 20, 23, 24... selection circuit, 1
1...Digital calculation processing section, 8, 8-1, 8-2
... Comparison circuit, 7, 13, 14 ... Rectifier circuit,
9, 9-1, 9-2, 27, 28...Addition/subtraction circuit, 12...Reference amount generation circuit.

Claims (1)

[Claims] 1. A selection circuit that selects and outputs a plurality of voltages and currents from among the amounts of electricity introduced from the power system;
a rectifier circuit that rectifies the current output from the selection circuit; a comparison circuit that forms a composite output of the voltage output from the selection circuit and the current output from the rectification circuit and determines a magnitude relationship with a predetermined level; and a digital arithmetic processing section that takes the comparison circuit output as an input quantity, and the digital arithmetic processing section sends a control signal to the selection circuit to sequentially select and output the input electrical quantity from the power system in time series. means for introducing a comparison circuit output; and means for determining whether a comparison circuit output signal corresponding to a specific selection control state of the selection circuit is in a predetermined state continuously for a predetermined period of time and determining a protection output. A protective relay comprising: 2. The protective relay according to claim 1, further comprising a reference amount generating circuit for generating a predetermined level, and the predetermined level being made variable by a control signal from a digital arithmetic processing section. 3. A first selection circuit that selects and outputs a plurality of voltages and currents from among the amounts of electricity introduced from the power system, and a positive wave rectifier circuit that rectifies the positive wave current output from the first selection circuit. , a negative wave rectifier circuit that rectifies the negative wave current output, a second selection circuit that selects each of the rectified outputs, a third selection circuit that switches between positive and negative predetermined levels as reference quantities, and the first selection circuit. a comparison circuit that forms a composite output of a voltage output from the circuit and a current output from the second selection circuit and determines a magnitude relationship with the output of the third selection circuit; and a comparison circuit that uses the output of the comparison circuit as an input amount. a digital arithmetic processing section; the digital arithmetic processing section sends a control signal to the first selection circuit to sequentially select and output the amount of electricity input from the power system in time series; and a second selection circuit. means for deriving rectified outputs for positive waves and negative waves for the third selection circuit; means for introducing the reference amounts of the positive and negative waves into the comparison circuit by selecting reference amounts for each of the positive and negative waves for the third selection circuit; and means for determining whether or not the comparator circuit output signal corresponding to a specific selection control state of the first selection circuit is continuously in a predetermined state for a predetermined period of time and determining a protection output. A protective relay featuring: 4. A selection circuit that selects and outputs a plurality of voltages and currents from among the amounts of electricity introduced from the power system;
a positive wave rectifier circuit that rectifies the positive wave current output from the selection circuit; a negative wave rectifier circuit that rectifies the negative wave current output; and a voltage output from the selection circuit and a current output from the positive wave rectification circuit. a first comparison circuit that forms a composite output and determines a magnitude relationship with a positive reference amount; and a first comparison circuit that forms a composite output of the voltage output from the selection circuit and the current output from the negative wave rectifier circuit and a second comparator circuit that determines the magnitude relationship with a reference quantity; and a digital arithmetic processing section that uses the outputs of the first and second comparator circuits as input quantities, and the digital arithmetic processing section is a selection circuit. means for transmitting a control signal to sequentially select and output the amount of electricity inputted from the electric power system in time series, and each comparison circuit output signal corresponding to a specific selected control state by the selection circuit is continuously transmitted for a predetermined period of time. 1. A protective relay comprising means for determining whether or not a predetermined state is present and determining a protective output. 5. First and second units that select and output a plurality of voltages and currents from the amount of electricity introduced from the power system.
a selection circuit, a first addition/subtraction circuit that receives a voltage input from the first selection circuit and outputs each voltage amount of Δ, and a current input from the second selection circuit, a second addition/subtraction circuit that outputs each current of Δ; a rectification circuit that rectifies the current output from the second addition/subtraction circuit; and a combination of the output from the first addition/subtraction circuit and the output from the rectification circuit. A comparison circuit that forms an output and determines a magnitude relationship with a reference quantity having a Δ constant, and a digital arithmetic processing unit that uses the output of the comparison circuit as an input quantity,
The digital arithmetic processing unit sends a control signal to the first and second selection circuits to sequentially select and output the amount of electricity input from the power system in time series, and the reference amount is switched to Δ. and means for determining a protection output by determining whether or not a comparison circuit output signal corresponding to a specific selected control state by the selection circuit is continuously in a predetermined state for a predetermined period of time. protective relay. 6. First and second units that select and output a plurality of voltages and currents from the amount of electricity introduced from the power system.
a selection circuit, first and second holding circuits that hold outputs of the first and second selection circuits, respectively, and a first holding circuit that combines the outputs of the respective holding circuits and the outputs of the selection circuits, respectively. and a second addition/subtraction circuit, a comparison circuit that introduces the outputs from each of the addition/subtraction circuits and determines the magnitude relationship with a reference amount, and a digital arithmetic processing section that uses the output of the comparison circuit as an input amount, The arithmetic processing unit sends a control signal to the first and second selection circuits to sequentially select and output the amount of electricity input from the power system in a time-series manner, and to the first and second holding circuits. A means for sending out a control signal, a means for switching and controlling a reference amount, and a comparison circuit corresponding to a specific selected control state by a selection circuit Determines and protects whether an output signal is continuously in a predetermined state for a predetermined period of time. A protective relay comprising means for determining an output.