JPH0446056B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a protection relay device, particularly a protective relay device that protects a power grid by mutually transmitting the amount of power of the grid via a transmission means at both ends of a power transmission line. This invention relates to a protective relay device.

[Technical background of the invention]

FIG. 1 shows an example of the configuration of a conventional protective relay device to which a digital transmission method is applied. In FIG. 1, a protective relay device 1 is installed at both ends of a power transmission line 2 to protect the power transmission line 2 by, for example, a current differential relay system. The protective relay device 1 for each terminal is composed of a converter 3, an arithmetic device 4, and a transmitting/receiving device 5. The conversion device 3 inputs the system electrical quantity I of the power transmission line 2, samples this input at appropriate intervals, converts it into a digital value, and outputs it to the transmitting/receiving device 5. The transmitting/receiving device 5 and the transmitting device 6 constitute a digital transmission system, and the transmitting/receiving device 5 transmits the sampling data of the system electrical quantity outputted from the conversion device 3 to the opposite end via the transmitting device 6, and at the same time transmits the sampling data from the opposite end. It receives a transmitted signal related to the amount of grid electricity at the other end and outputs it to the arithmetic unit 4. Also, the calculation device 4
detects a failure in the transmission line 2 by performing protection calculations such as current differential protection based on the system electricity amount at the own end inputted from the converter 3 and the system electricity amount at the other end inputted via the transmitting/receiving device 5. Do this.

[Problems with background technology]

One of the problems with a protective relay device that performs a protective operation using digital transmission as described above is the transmission speed of the digital transmission system. That is, each protective relay device in FIG. 1 needs to transmit the amount of system electricity sampled at its own end and converted into a digital value to the other end before the next sampling is performed. Therefore, the transmission device 6
must have sufficient transmission speed to perform the above transmission. As an example, suppose that the system electrical quantities sampled at each relay terminal are four quantities: three-phase currents, I _R , _IS , and _IT , and zero-phase currents, and each is transmitted as a 12-bit digital quantity. The number of digital data bits required to transmit one sampling data is the 13-bit synchronization frame signal generally required for digital transmission, and
Including the 16-bit CRC check signal, the total is 77 bits. If this is sampled at 30° intervals in a 60Hz power system, the above digital signal needs to be transmitted 720 times per second, and in order to do so, the transmission device 6 needs to transmit 77 x 720 = 55.4Kbps (bau per second). It is necessary to have a transmission speed higher than that. This value is higher than the transmission speed of a standard transmission device, 48 Kbps, and is difficult to transmit using the standard transmission device. Therefore, in such cases, conventionally
Standard transmission speed one rank higher than 48Kbps transmission equipment
A transmission device with a transmission speed of 1544Kbps (PCM 1st order group) was used, or a transmission device with a special non-standard transmission speed was created and used. There were problems such as a decrease in transmission efficiency because of the high-speed transmission, and an expensive transmission system because it was a non-standard transmission device.

[Purpose of the invention]

The present invention has been made with the aim of solving the above-mentioned problems, and aims to provide a protective relay device that can efficiently transmit data using a transmission device having a standard transmission speed. .

[Summary of the invention]

In the present invention, each end of the protected section is connected by a plurality of transmission devices, and the sampled grid electricity amount at the own end is transmitted to the other end with different transmission timings, and the shifted transmission data from the other end is transmitted to the other end. The purpose is to perform a protection calculation using the transmission data rearranged by combining the data and the converted system electrical quantity at its own end.

[Embodiments of the invention]

Examples will be described below with reference to the drawings. Prior to describing embodiments of the present invention, the basic idea of the present invention will be explained with reference to FIGS. 2 and 3.

FIG. 2 is a block diagram showing the configuration of the first invention. This idea is to convert the amount of grid electricity input from current transformer a into a digital value by sampling it through converter b, and to transmit this digital value in multiple ways by shifting the transmission timing of each sampling data in transmitting/receiving device c. It is transmitted to the other end via means d.

On the other hand, sampling data from the other end is introduced into the arithmetic unit e via the transmitting/receiving device c, and the timing is combined to restore the original amount of system electricity and perform protection calculation. Here, if there is an abnormality in the sampling data from the other end by the transmitting/receiving device c, the output from the abnormality detecting means f is introduced into the arithmetic device e to change the protection calculation. That is, it attempts to cover the transmission speed by shifting sampling data and transmitting it alternately.

FIG. 3 is a functional block diagram showing the configuration of the second invention. This idea is to convert the amount of grid electricity input from current transformer a into a digital value by sampling it through converter b, and then convert this into a digital value by dividing it into a plurality of equally spaced sampling data at transmitting/receiving device c. The information is transmitted via the transmission means d.

On the other hand, the sampling data from the other party is introduced into the arithmetic unit e via the transmitting/receiving device c and is subjected to a combination calculation, and the calculation is changed depending on the type from the abnormality detection means f. In this case, if there is an abnormality in one of the sampling data, only one of the healthy data is used for calculation. Similar to the first concept described above, this method attempts to cover the transmission speed by dividing the sampling data and transmitting them separately.

FIG. 4 is a configuration diagram of an embodiment of the protective relay device according to the present invention. In FIG. 4, the same symbols as in FIG. 1 indicate the same components. Note that this embodiment is based on the basic idea shown in FIG. In FIG. 4, the transmitting/receiving devices 5 and 7 respectively input the sampling data of the system electrical quantity output from the converter 3, and output transmission signals to the respective transmission devices 6 and 8, and at the same time transmit signals from the other end. It receives the incoming transmission signal and outputs the sampled system electrical quantity to the arithmetic unit 4 at the other end. Further, each of the transmitting and receiving devices 5 and 7 is connected to abnormality detection devices 9 and 10 that detect abnormalities in the transmission system. Here, the abnormality detection devices 9 and 10 respectively monitor the digital transmission system, and output abnormality detection signals A ₁ and A ₂ to the arithmetic device 4 when an abnormality is detected.

FIG. 5 is a diagram for explaining how sampling data is transmitted. In FIG. 5, the horizontal axis indicates time, and t ₁ to _{t 12} shown next to T are conversion device 3.
indicates the sampling time at which the grid electricity amount is sampled. Further, A and B indicate transmission signals transmitted via the respective transmission devices 6 and 8, and symbols S ₁ to S ₁₁ within each frame indicate sampling data to be transmitted.

Next, the operation will be explained. First, a case where the transmitting/receiving devices 5, 7 and the transmitting devices 6, 8 are operating normally will be described. In this case, the conversion device 3 samples the amount of system electricity of the power transmission line 2 at sampling times t ₁ to _{t 12} at regular intervals, converts this into a digital amount, and then outputs it to each transmitting/receiving device 5 and 7 . Here, the transmitting/receiving devices 5 and 7 alternately transmit the data at each sampling time outputted from the converting device 3 with respective transmission timings shifted.

That is, as shown _{in FIG} .
S ₁ is transmitted, and the sampling data S ₃ is transmitted during the period from sampling time t ₃ to _{t 5} . 7
transmits the even-numbered sampled system electrical quantity at each sampling time.

In this case, as is clear from FIG. 5, transmission of the system electrical quantity in one sampling may be performed within a time corresponding to two samplings. Therefore, in transmitting the amount of grid electricity, transmission devices 6 and 8
The transmission speed required for this is 54.4Kbps, which is an example of the transmission speed in the conventional example mentioned earlier.
It is 27.2Kbps or more, which is 1/2. However, since the transmission speed of the standard transmission device is 48 Kbps, the standard transmission device can be used sufficiently for the transmission devices 6 and 8. The transmission signals transmitted via the transmission devices 6 and 8 are received by the transmitting and receiving devices 5 and 7 and then output to the arithmetic device 4, where the respective output signals are combined and rearranged in the order of sampling time. It will be done. After obtaining regular sampling data through this rearrangement, the arithmetic unit 4 performs arithmetic operations related to normal protective relay operation based on the respective data.

FIG. 6 shows another embodiment of how sampling data is transmitted.

In this embodiment, sampling data transmitted using a plurality of transmission devices is divided and transmitted. Note that this embodiment is based on the basic idea shown in FIG.

In FIG. 6, I is the system electricity quantity input to the converter 3, t ₁ , t ₂ . Indicates the sampling data to be transmitted. As is clear from FIG. 6, the sampling data A and B transmitted by the transmission devices 6 and 8 are data sampled separately at equal intervals with respect to the system electricity quantity I. Therefore, the arithmetic unit 4 can perform protection-related calculations using only either A or B.

In addition, when calculating the system electricity amount from sampling data, if you use the amplitude calculation formula (1) or (2) shown below, you can correct the amount of electricity by just correcting the coefficient regardless of the sampling period of the source data. Amplitude values can be obtained.

I ² = (i ² _n +i ² _n-1 −2i _n i _n-1 cosωT) /sin ² ωT …(1) kI ² =i ² _n −Ki ² _n-1 +i ² _n-2 …(2) However, T: sampling period i _n , i _n-1 , i _n-2 : continuous sampling data As shown in Figure 6, calculation speed and judgment when based on sampling data of only A or B Although the time required for this calculation is inferior to that based on the original sampling data I, in many cases it is possible to perform protection calculations within a range that causes no practical problems.

Next, the operation when an abnormality occurs in the transmission of sampling data will be explained. In FIG. 4, the abnormality detection devices 9 and 10 detect a drop in the level of the transmission signal,
Data transmission is monitored using methods such as parity detection, cyclic code (CRC) verification, and double matching, and when an abnormality is detected in the transmitted signal, an abnormality detection signal A ₁ or A ₂ is output to the arithmetic unit 4 .
When the calculation device 4 detects an abnormality in the transmission system based on the abnormality detection signals A ₁ and A ₂ , it changes the internal calculation to a calculation method that uses only the data of the healthy transmission system.

Note that the sampling data transmitted from each transmission system is sampled at equal intervals as described above, and the protection calculation can be performed using only one of the transmitted data.

Therefore, the arithmetic device 4 switches the data used for internal computation to the normal transmission system side, and at the same time changes the computation method and the number of systems used in the computation to a form that corresponds to 1/2 of the normal data.

FIG. 7 is a flowchart of arithmetic processing. In step 51, the presence or absence of abnormality detection signals A ₁ and A ₂ output from the abnormality detection devices 9 and 10 is determined. If neither the abnormality detection signal A ₁ nor A ₂ is output here, the transmission system is all normal, so the process moves to step 52, and all the sampling data shown in FIG. 6 I are used as the data for the calculation. It is usable, so a normal protection operation is performed in step 53. If it is determined in step 51 that the abnormality detection signal (A ₁ , A ₂ ) is present, the process moves to step 54 to determine the type of the abnormality detection signal, and performs each process in steps 55 to 57.

That is, if an abnormality occurs in the first transmission device 6 and the abnormality detection signal _A1 is output from the abnormality detection device 9, the process moves to step 56, and even-numbered sampling data transmitted via the second transmission device 8 is output. Enter only (B). Here, the even-numbered data (B) corresponds to the data obtained by thinning out the odd-numbered data from the regular sampling data (I), so the sampling period is doubled when performing the protection operation. It needs to be treated as Therefore, in step 58, a protective calculation is performed using an arithmetic expression corresponding to the above conditions or coefficients used in the calculation.

Next, when an abnormality occurs in the second transmission device 8 and the abnormality detection signal _A2 is output from the abnormality detection device 10, the above explanation is reversed, and only the odd-numbered sampling data (A) is input in step 55. However, the transmission device operates in the same manner as the first transmission device. Further, if the abnormality detection signals _A1 and _A2 are output in step 54, the calculation becomes impossible in step 57.

As is clear from the above explanation, the calculation device 4 is able to continue the protection calculation to some extent even when an abnormality occurs in one side of the transmission system, and it is possible that the operation of the protective relay device may be abnormal due to an abnormality in the transmission system. sex is significantly reduced.

Although the above embodiment has been described as using two sets of transmission systems for transmitting sampling data, the number of transmission systems is not limited, and if a large amount of sampling data is to be transmitted, It is possible to use three or more sets of transmission systems.

Note that when three or more sets of transmission systems are used, various methods can be considered as calculation processing when an abnormality occurs in one of them. As an example, data to be transmitted by a transmission system in which an abnormality has occurred may be interpolated with data transmitted by another healthy transmission system, or a part of the data transmitted by a healthy transmission system may be truncated to make it easier to calculate. Processing such as thinning out the data can be considered. Also, the sampling interval is
In the case of 30 degrees, if the number of transmission systems is three, the sampling interval of each transmission data will be 90 degrees, and the amplitude value can be calculated using data from only one transmission system.

In addition, in the above embodiment, depending on the sampling time,
Although the description has been made assuming that the divided data is transmitted through separate transmission devices, the present invention is not limited to this, and for example, a multi-line transmission device using microwaves or optical fibers may be used. You can also do that. In this case, although the abnormality is limited to the modulation/demodulation section in the superimposed transmission device, the transmitter/receiver section in the protective relay, and the connection between the two, it is expected that reliability will be improved compared to the conventional system.

Furthermore, although the above embodiment has been explained using two-terminal protection of a power transmission line as an example, it is also applicable to multi-terminal protection with three or more terminals. In this case, multiple transmission systems are provided between the multi-terminals, and the Of course, the processing of the flowchart described above is performed by the arithmetic unit of each terminal.

〔Effect of the invention〕

As explained above, according to the present invention, a plurality of transmission systems are provided between each terminal, and the system electrical quantity sampled at each end is divided into mutually shifted sampling times and transmitted, and when an abnormality occurs in the transmission equipment, Since the structure is configured such that arithmetic processing is performed using transmission data on the healthy side depending on the type of abnormality, it is possible to provide a highly reliable protective relay device in which protective operation can be continued.

[Brief explanation of the drawing]

Fig. 1 is a configuration example of a conventional protective relay device using a digital transmission method, Fig. 2 is a functional block diagram for explaining one of the basic ideas of the present invention, and Fig. 3 is a functional block diagram of the present invention. Fig. 4 is a functional block diagram for explaining another basic idea of the present invention, Fig. 4 is a configuration diagram of an embodiment of the protective relay device according to the present invention, and Fig. 5 is for explaining the method of transmitting sampling data. 6 shows another embodiment of how to transmit sampling data, and FIG. 7 shows a flowchart of arithmetic processing. DESCRIPTION OF SYMBOLS 1... Protective relay device, 2... Power transmission line, 3... Conversion device, 4... Arithmetic device, 5, 7... Transmission/reception device, 6, 8
...Transmission device, 9,10... Abnormality detection device.

Claims (1)

[Claims] 1. In a protective relay device that performs system protection by sampling the amount of grid electricity at each end of the power system and transmitting data regarding the amount of grid electricity to each other via a transmission means, the data is converted into data at sampling times that are shifted from each other. a plurality of transmission means for dividing and transmitting data, an abnormality detection means for detecting an abnormality in each of the transmission means and inputting the detected abnormality to a calculation device, and a calculation device for performing protection calculation, and the calculation device always transmits the plurality of means for performing a protection calculation using the data transmitted by the transmission means whose transmission timing is shifted; and means for performing a protection calculation using the data transmitted by the transmission means with shifted transmission timings; A protective relay device characterized by comprising means for performing protection calculations using only data.