JPS61186865A - Frequency relay - Google Patents

Abstract

PURPOSE:To eliminate the need for a frequency relay of different constitution even when a microcomputer which includes a relay element is used by detecting a change in the polarity of an AC input signal and calculating the time of one cycle which changes from (-) to (+) or vice versa. CONSTITUTION:The AC signal after the detection 2 of the quantity of electricity is sampled and its data yn and yn-1 are supplied to the 1st decision part 6a of a polarity change detection part 6 to decide on yn>0 and yn-1<0; when so they are inputted to the 1st time arithmetic circuit 7a, which calculates a sampling value in one cycle wherein the input signal changes from (-) to (+) or from (+) to (-). When the decision result of the decision part 6a is NO, the 2nd decision part 6b decides on yn<0 and yn-1>0 and the 2nd time arithmetic part 6b calculates a sampling value in one cycle in which the input signal changes from (+) to (-) or from (-) to (+). Then, an operation decision part 8 decides whether an excessive frequency operates for a deficient frequency relay or not from the arithmetic result. Therefore, a frequency relay element is stored in the microcomputer wherein plural relay elements are stored, so relay elements need not be constituted as different constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a frequency relay used to protect generators and the like.

B1 Summary of the Invention This invention uses a microcomputer to sample an AC input signal in a nine-frequency relay, detects all changes in polarity of the AC input signal, and detects the time of one cycle in which the change changes from negative to positive, and changes from 1 to negative
By calculating the cycle time and determining the frequency operation.

Even when using a microcomputer that accommodates many types of relay elements, there is no need to construct a frequency relay in a separate circuit, and there is no need for maintenance and inspection.

C6 Conventional technology Conventional 1 A relay for detecting the frequency of a generator, etc. detects a half cycle of an AC input waveform using a zero cross switch, etc., counts the pulses generated from the oscillator during that cycle, and calculates the frequency from the number of counts. is used to detect.

D0 Problems to be Solved by the Invention The frequency relay configured as described above requires a highly accurate excavator to improve frequency detection accuracy and has a problem in that the circuit configuration is complicated.

It's been nine years since I've been able to do it. Although this microcomputer is used to process a large number of relay elements, there is a problem in that the frequency relay has to be formed with a separate circuit configuration, requiring careful maintenance and inspection.

Precautionary Measures to Solve the E0 Problem The present invention includes an electrical quantity detector installed on a railway line to detect an alternating current signal, and the detection output of this detector is sampled at a predetermined sampling frequency and the digital signal is output. The current sampling value when the polarity of the AC signal is reversed based on the A/D converter to send out and the output signal of this converter, and the current sampling value. From the polarity change detection unit that detects the polarity change detection unit and the result of the detection signal of this detection unit, the time it takes for the AC signal to change from negative to positive, and the time it takes for the AC signal to change from negative to positive, and the time it takes for the AC signal to change from negative to negative after changing from positive to negative, It consists of a time calculation section that calculates the sampling value for one cycle until it changes to , and an operation determination section that receives the output signal of the time calculation section and determines the frequency operation from the signal.

70 action The nine AC signals detected by the electric quantity detector are sampled and then converted into digital signals. From this digital signal, it is determined whether the current sampling value when the polarity of the alternating current signal is reversed and the sampling value immediately before the current moment are greater than, slightly less than, the zero crossing point of the alternating current signal. Based on this judgment result, the sampling value between the time of one cycle when the polarity changes from negative to positive and the time of one cycle when the polarity changes from positive to negative is calculated, and based on the calculation result, it is determined whether the relay operates as an over-frequency or under-frequency relay. Make a judgment.

G. Examples Embodiments of the present invention will be described below with reference to page 1. 0 In the eleventh part, 1 is a power transmission line, and an electrolytic gold detection unit 2 consisting of a current transformer or a transformer is installed on this power transmission line l. establish.

The output signal of this electric quantity detector is filtered through a low-pass filter 3t.
- is input to the A/D converter Hiro. The A/D converter samples the input signal at a predetermined sampling frequency from the generator and outputs the entire digital signal.

This digital signal is the first signal of the polarity change detection section B. The signal is input to the second discrimination circuits 4a and Ab. The polarity change detection section B detects the current sampling value y of the output signal of the electric quantity detection section B.
The polarity is completely discriminated by detecting whether n changes from negative to positive or from positive to negative based on the zero cross 1 standard. The first step is to determine this. Second discrimination circuit Aa.

4b. The first discrimination circuit 6a determines that the current sampling value 7n is larger than the zero cross point ((yn>'1),
And the minute time Δ of the current sampling value is set so that the previous sampling value 7n-1 is smaller than the zero cross point (7n-t<0
) to detect a change in polarity.

In addition, the second discrimination circuit +bq detects a polarity change by determining whether the current sampling value 7n is smaller than the zero crossing point (7n(o)b and the current sampling value is larger than the zero crossing point (yn-t>0). It is something to do.

Said 1st. The discrimination output signal of the second discrimination circuit 4a, ≦b is the discrimination output signal of the second discrimination circuit 4a, ≦b. Second time calculation circuit 7a, 7
Each is input separately to b.

When the discrimination output signal of the first discrimination circuit +a is input, the first time calculation circuit 7a performs sampling for one cycle from when the input signal changes from minus to plus until it changes from minus to plus, as will be described later. Similarly, the second time calculation circuit 7b which calculates the value 0 is the second judgment circuit ≦
When the determination output signal b is input, as will be described later, the sampling value for one cycle from when the input signal changes from positive to negative until it changes from positive to negative is calculated. Both time calculation circuit 7a.

The output signal of 7b is input to the operation determining section ♂.

Next, a case will be described in which the electric quantity detector λ detects the nine alternating current signals f and the A/D converter μ samples them.

FIG. 2 shows how an AC signal is sampled at every time Δ (sampling frequency fIl=1/Δt), and the dots in the figure are sampling data. The polarity of the AC signal can be determined using this sampling data as follows.

Two sampling values before and after the polarity of the AC signal is reversed x + *
Then, both times 1+ and 1- can be obtained from the following equations.

As mentioned above, the means to obtain 1+, 1- total by linear approximation of AC signal t is from t considering that the AC waveform has the most linearity near the zero loss point. Using Figure 2, calculate the time between one cycle of the AC signal 'r ('r+,
In the waveform diagram illustrating the case of obtaining 'r-)', the time T between one cycle is as shown in the following equation.

T==t-+t++Tc...(2) In equation (2), 1-. 1+ can be determined from equation (1), and Tc can be determined from 7txc (a is the number of data items during one cycle - 1). Note that the reason for determining the % 1 cycle time is that it is strong against DC components.

Here, T+1r, as shown in Figure 3, it takes one cycle time from changing from negative to positive until changing from negative to positive, T-'i from changing from positive to negative, then changing from positive to negative. 1 cycle time.

7Cn-X n-7 is the sampling value before and after the zero cross point.

Time i'J] One cycle time of T+ is given by the following formula.

However, Δt = 1/f B :f s is the sampling frequency, and T- is the following equation.

T-=("-' +-5techniques 1--10-)Δt・・(
4) Xn-2In -3Xn-+5 Xn-7 Note that the counter C is obtained as follows.

In the case of C+ In the case of C- The mark ○ in the table means counter increment (set to +1), Xn means counter reset, s7n is the current sampling value 57n-t is Δ
is the previous sampling value.

Relationship FiF between the above 1 cycle time T and system frequency 7
= 1/T, which can generally be expressed by the following formula.

......(5) In the above formula (5), b ''n = sampling value after passing the O point at the current time, xn-1 = sampling value before passing the 0 point at the current time Xn-3 = half cycle before Sampling value after passing the θ point, ``Tl-3 = Sampling value before passing the 0 point half a cycle before, zn-4 = Sampling value after passing the 0 point l cycle before, ``n-5 = Sampling value after passing the 0 point 1 cycle before The sampling value before passing the θ point and the counter during C=1 cycle are shown, respectively.

Next, we will describe the application method to a specific frequency relay.
Relay setting value By substituting equation (5) into the above equation and rearranging it, the following equation is obtained.

FHset4-In-JoCxn-41n-s)+x
n-4°(In In-t)+o-(xn-Xn-1
) ・(xn-4-xfi-1+ ) ) fe ・(
Xn-xn-1)X(xn-4Xn-4)≦0...
(6) (2) Underfrequency relay (95L) '(Hz)♀Lsst (lFIg) Warning FLset:
Relay setting value By substituting equation (5) into the above equation and rearranging it, the following equation is obtained.

F'Lset'f Kn-t・Cxn-4-xfi-5
)+Xn-< e (xn-xn-s)+a-(xn
-cn-1)°(cn-4Xfi-s))gos 6(
Xn1n-s)XCxn-a-Xn4)≧0 ・(
7) The above equations (6) and (7) correspond to the time calculation section 7 shown in FIG. Figure 9 shows the specific configuration of the time calculation section 7 from equations (6) and (7).

In FIG. 4, the output signal of the polarity change detection section B is input to the register tA/ which obtains the sampling data xnk and the register phrase obtained at In-4. The output of the register is Xn-
5 is input to register tA3.

The outputs of Register Hiro/ and Shun are added in the adding section and the output is (
Xnxn-t) is obtained. The output of this (Xfi-xn-1) is supplied to the multipliers. In the multiplication section, the value of counter C is multiplied and the output is C・(Xn)Cn-t)
get. The multiplier section multiplies the signal by the sampling frequency fs and outputs .multidot.(XnXn-t)t''.

In the multiplication section 5, the output Xn-4 of the register Hiroko is multiplied to obtain the output xn-4.(in-Xn-t).

On the other hand, the output of the register Hiroko is input to the register that obtains
obtain. ldl$ I ybpt -yyyyyts i
1 wiz ko, z*output (Xrs -a XH-s
) is input to the multiplier section 0.5/. The multiplication section Hirode is inverted by the three polarity inverting sections "Xn-tt" of the register ≠ 3, and the t output (-xn -t) is multiplied by the addition section a♂0 output, and the output is f-In-t ( Xn-4Xn-5
)) "Th is obtained. The multiplication part 0 multiplies the output of the addition part and the output of the multiplication part, and the output is 0・Cxn-xn-s)
'(XH-i In-g) t-obtain.

The multiplier 3/ multiplies the output of the adder t♂ and the output of the multiplier j to give the output tB ・(xn-xn-1) ・Cxn-4-
xn-s).

j3 is an adder, and this adder j3 adds the output of the multiplier and the output of ≠9 to the output (-XH-1・CXn-a -X
n-a)+xn-a (Xn-Xn-1))'
e get. The output of the adder j3 and the output of the multiplier 50 are added in the adder, and the output is multiplied by the relay setting value FHset or 'La5t in the multiplier 11. The output of this multiplier j3 and the multiplier! The output of r/ is added to the adder j
6, and a determining unit 37 determines whether the added output is larger or smaller than zero, and is supplied to the motion determining unit r.

FIG. 5 is a detailed block diagram of the operation determining section r, which consists of a pair of AND circuits e, r, and s.

T+95I for AND circuit I! Operation output, 'T-95
An H operation output and an output of IN≧ are supplied, and a 95H operation output is obtained from these outputs. in this way'
The AND conditions for r, , T- and the ninth condition are necessary to prevent malfunctions due to distorted waves, etc., and the condition for +V+≧X is because the calculation error will increase unless the voltage is present to a certain extent.

By the way, what about AND circuit evening 9? +95L operating output, T-9
5L operating output and ll≧KO output are supplied 0 Next, the entire operation of the above embodiment will be described with reference to the flowchart of FIG. First, the electromagnetic alternating current signal detected by the electric quantity detector is sampled at a sampling frequency of 8. The sampled data 7n and 7n -1 are processed by the first discrimination section of the polarity change detection section so that 7 n>os yn-1<.

A determination is made. If the result is [YES J, then 0-=
It goes to the time calculation section which performs 10 processing via the O-+1 counter. In this time calculation section, processing is performed based on the processing results of equations (6) and (7) and the C+ counter reset, and then processing is transferred to the operation determination section. The motion determination section performs determination of 1"/I≧, T+ motion, and T- motion, and each determination is "y
If it is msJ, 96 relay operation processing is performed. Note that if even one of the above determination results is "NO", the 95 relay is inoperable processing.

Further, the result of the first discrimination section of the polarity change detection section is "No.
”, the second discriminator uses the counter C+ = C+ + 1 to determine y n (o I y n-t > 0
Performs 0 determination. If this result is [yzsJ, it goes to the time calculation unit which performs T-processing. This time calculation section processes the processing results of equations (6) and (7) above and processes the C-counter reset, and the processing is sent to the operation judgment section. The motion determination section performs the same processing as described above.

Effects of the H0 Invention As described above, according to the present invention, the frequency relay element can also be housed in a microcomputer in which a plurality of relay elements are housed, so that only the frequency relay needs to have a separate port configuration. Therefore, the configuration can be simplified. This is particularly advantageous in that a frequency relay can be added to the transmission Ml# protection relay or the generator protection relay.

Since the above configuration eliminates the need for a separate outlet for maintenance and inspection, the reliability of the device is improved because maintenance and inspection can be performed at the same level.

A brief explanation of the oral aspect FIG. 1 is a block diagram showing an embodiment of the present invention.

Fig. 2 is an explanatory diagram when sampling at the time of each AC signal Idt, Fig. 8 is an explanatory diagram for determining the time of one cycle when the AC signal is not sampled, and Fig. 4 is the same as shown in Fig. 1. tA block diagram showing a specific embodiment of the time calculation unit, FIG. 5 is shown in FIG. FIG. 8 is a flowchart for explaining the operation of FIG. 1.

/...Line, λ...Electricity detection unit, 3...Filter.

Hiroshi... A/D converter % T... Generator, 6... Polarity change detection section, 7... Time calculation section, r... Operation determination section.

Figure 2

Claims (1)

[Claims] (1) An electrical quantity detector installed on the line to detect alternating current signals; the detection signal of this electrical quantity detector is input through a filter, the input signal is sampled at a predetermined sampling frequency, and the output is a digital signal. From the output signal of this A/D converter, the current sampling value when the polarity of the AC signal is reversed and the sampling value a minute time before that current time are calculated from the zero cross point of the AC signal. A polarity change detection section that detects a polarity change by determining whether it is large or small, and a signal that changes the polarity of the AC signal from negative to positive or from positive to negative based on the detection signal of this polarity change detection section. a time calculation unit that determines whether or not the AC signal is present and calculates a sampling value for one cycle of the AC signal; and an operation determination unit that receives the output signal of the time calculation unit and determines the operating frequency from this signal. relay.