JPH0213221A - Inspection method for digital current differential protective relay - Google Patents

Abstract

PURPOSE:To perform a high accuracy inspection by simultaneously applying signals with equal magnitude and phase to a circuit corresponding to each phase of each terminal and, as a result, by detecting the difference between respective phases. CONSTITUTION:When an inspection start command is given, inspection current signals with equal magnitude and phase are applied to each-phase terminals and detected by a detector. Each-phase difference current values idRm, idSm, idTm are computed from detected signals, and respective mutual differences IdRS, IdST, IdTR between these phases are computed and judged to be abnormal at the time of exceeding an allowable value epsilon0. With reference to R-phase being a representative phase, the difference current IdR for the period of time T, during which an inspection input is applied, is judged to be abnormal at the time of not satisfying the formula (1) when ITS is an inspection current and k is a constant.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an inspection method for a digital current differential protective relay device that improves inspection accuracy (Prior art) Current differential The protective relay system is the most sophisticated protection system for detecting accidents with high sensitivity for power transmission line protection, and is widely applied.

The basic principle is to transmit the current waveforms of each terminal of the power transmission line to each other, and to distinguish between internal and external faults based on the sum of current vectors between each terminal, that is, whether the difference current is above a predetermined level. In the case of an internal fault section, a command is sent to the breaker to disconnect it from the healthy system.

An example of a digital current differential protective relay device is shown in FIG. In Fig. 3, each electric station A, B is connected to each bus line 1.
are connected via a terminal breaker 2 and a power transmission line 3.

The current IA of electric station A is converted by a convergence input converter 5 through a current transformer 4 provided at each terminal to a level IA' which is missed for digital calculation. iA' passes through a harmonic removal filter 8, is sampled and held at a sample hold circuit 9, and is sampled at a constant cycle, and then converted from analog to digital by an A/D converter 10 to obtain a digital member i''. j'' is a communication device 11, It is transmitted to electric station B via the communication circuit 12. On the other hand, the electric current 18 at electric station B is converted into digital data in the same manner as described above, and IB'' is transmitted to electric station A. The i'' at the own electric station and the received signal IB have the same phase relationship as the grid current. After passing through the compensation circuit 13 that compensates for the following, the signal is introduced into the relay determination section 7 in the CPU 6. In the relay judgment section 7, it is determined that the current flowing to both A and B is proportional to the current i.
, 1'', the vector sum (l, = B i, ``10i''), that is, the amount corresponding to the difference current, and when this amount exceeds a certain predetermined level, it is determined that an internal accident has occurred. , a disconnection command is issued to the circuit breaker of each terminal determined to be in the fault zone, and the failure is promptly removed.There are various methods for calculation and determination in the relay determination section 7, but all of them are known methods. Since this is the content, its explanation will be omitted.

In such a digital current differential protection relay device, it is the responsibility of the device to respond accurately in the event of an accident in the power system, so the device must be free from defects. Therefore, such digital current differential protection@1 equipment failure of electrical equipment, especially after its input converter 5, harmonic rejection filter 8. Sample and hold circuit9. A/D converter 10
It is absolutely necessary to inspect the analog input section, which consists of the following components, for defects.

The method for inspecting the analog input section for defects is to apply a known current into the device from the input converter 5 using the inspection power supply,
The amplitude value of the current of each phase finally obtained through the device is C
Inspection can be easily carried out by performing calculations in the PU 6 and confirming that the resulting values are within a predetermined range.

The conventional inspection method will be described in detail below.

Figure 4 is a flowchart showing the inspection method of a conventional digital current differential protection relay device. This is a process for trilaglocking the corners of the eyes. After confirming that the trilag is locked, each phase current I, I, 11 at its own end is introduced from the system to the input converter 5 via the current transformer 4 using the inspection current input circuit shown in FIG. t
s is turned on, and the inspection current I is applied from the above-mentioned inspection power supply. The secondary side output of the input converter 5 is each phase T,
The inspection current I□ is superimposed on I and I, resulting in an ST output. This superimposed check current is applied to the harmonic removal filter 8. Sangle hold circuit9. A/D converter 10f: check current data that has been retroactively converted into digital data [r], and current amplitude values of each phase at the edge of the eye are calculated by predetermined amplitude value calculations. The above is carried out in step D.

This inspection current swing @ value is the sum of the power flow from the grid and the inspection current from the inspection power supply, and can be expressed by the following formula.

I=I 10I +ΔI ÷ε RTSRCRTS 1=tfI +ΔI +ε S TSS C8TS I=I +I +ΔWork +ε T TST CT TS Here, I, I, and I are respectively calculated inspection voltage SC current amplitude value 1 inspection The inspection current from the power supply and the power flow from the grid are shown, and the subscripts R, S, and T correspond to the R phase, S phase, and T phase. vinegar,.

Δ■TS is the variation of the power supply for inspection1. ε indicates an error caused by hardware, and these I, I, and I are
T lag If the conditions shown in ■, o, ■ are satisfied, the amplitude values I, I,
I is determined to be normal. Conversely, when the S condition is not satisfied, it is determined that there is a defective ST in the amplitude values I, 1, I, and the output interface section 14 of FIG.
A V@ command, etc. is output through the terminal, and the analog input section is inspected in this way.

(Problem to be Solved by the Invention) In the conventional inspection method described above, the value of K described in step Oo1■ is determined by the fluctuation of the power supply for inspection (ΔI□, ), 'a flow division ■o) and the hardware It is necessary to take into consideration the error (ε) and set it to a value larger than the sum of these values. For this reason,
High inspection accuracy cannot be obtained due to the influence of fluctuations in power flow and inspection current. As a countermeasure to this problem, in order to eliminate the influence of the power flow, a hardware configuration is used that locks the input current from the grid during inspection or cancels the power flow shown in FIG. In the figure, during inspection, contacts 15R to 15T are closed or contacts 16R to 16T are largely opened, so that each phase current 1, I, I of the power system detected by each current transformer 17R to 17T is ST power flow cancelled. will be done. In this case, hardware additions such as additional contacts are required to cancel the current.

In addition, with the conventional inspection method, although it is possible to check the inspection accuracy of the own end, it is not possible to determine whether or not the analog input accuracy at all terminals is good.

As mentioned above, according to the conventional inspection method, inspection accuracy is limited by fluctuations in the power supply for power flow inspection.

■ Additional hardware is required to cancel the power flow.

■ It is not possible to judge whether the analog input accuracy is good considering all the terminals comprehensively.

There is a problem.

The present invention has been made in view of the above circumstances, and when inspecting a digital current differential protection relay device, the on-site reception is used to apply a test input to the device at the same time on all terminals during the installation test. 2. Applying the simultaneous failure occurrence signal to the inspection input application signal. The object of the present invention is to provide an inspection method for a digital current differential protective relay device that allows highly accurate inspection by applying inspection input to all terminals.

[Structure of the invention]

(Means for Solving the Problems) To explain the configuration for achieving the above object, in the present invention, the amount of electricity in the power system is sampled at the same time and at a constant cycle at each electric station, and this sampled value is converted into an analog/digital After conversion, each electrical station sends and receives data between each other via a transmission device, and at each electrical station, the received data and own-end data are introduced into the relay judgment section, and the operating electricity calculated from both data is calculated. In the digital current differential protection #1 electrical system, which processes to determine whether the amount of electricity is equal to or greater than the suppressed amount of electricity, when inspecting the protective relay device, a large number of protective relays are provided at each terminal, corresponding to each phase of the Inspection inputs having the same magnitude and phase are simultaneously applied to the input circuit provided as above, and it is determined whether the magnitude of the difference between each phase of the operating electrical quantity is less than or equal to a predetermined value.

(Operation) First, in response to an inspection command, an inspection input with the same magnitude and phase, which is synchronized to all terminals, is applied to the input circuit of the protective relay device installed at each terminal.

Then, the amount of operating electricity of each phase, etc. is determined, and the amount of difference between these phases is compared. If the amount of difference is less than a predetermined value, it is determined to be normal, and otherwise, it is determined to be abnormal.

(Example) Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a flowchart showing the processing contents of the relay device inspection method according to the present invention, and the determination is made within the CPU 6 in the digital current differential protection relay. Taking the 3@ child configuration as an example, ■ in Figure 1.

When an inspection command is given to the device in ■ and ■, the simultaneous failure occurrence signal described above is generated, and all terminals are synchronized simultaneously from the inspection power supply to the protective relay device of the same configuration installed at each terminal. A check current with the same magnitude and phase is introduced.

The inspection current of all terminals is determined by the communication device 117 and communication concave line 12 mentioned above.
are mutually transmitted via the terminal, and a check current as shown in the formula below can be obtained for each terminal.

A terminal R phase S phase T phase B terminal R phase S phase T phase C terminal R phase S phase T phase Here, ・'AR"' ARL 1As"" ASL 'AT=' ATt + i " BR=1BRL BRTS l =i+i BS BSL BSTSi-i+i BT BTL BTTS+1＾RTS +1＾STS +' ATTS x=i+i CRCRL CRTS + 1 1C8=” C8L C3TS i=i 10i CT CTL CTTSThe above equations all use instantaneous current data. means, subscript The 7th character represents the A to C terminals, the 2nd character represents each phase,
The numbers after the third letter are the current and other errors,
T means the inspection current from the inspection power supply. Most @
The subscript m at the end indicates that each phase of each terminal is the latest data that is sung at the same time and at a constant cycle.

In step (2), the vector sum of each phase, that is, the difference current, is calculated using the inspection current data that can be expressed by the above formula. The difference current value i of the R phase obtained in step ① is given by the following formula.

Rn fi −1−i i dRn = ' ARn BRI
CRa=(i fi +t) ARLn BRLn CRLl+(iARTS
IBRTSICRTSn+i fi) When the system is healthy and there is no defect in the equipment, i fi
fi Medium 0 ARLn 8RLll CRLni
fi fi middle school 3iARTS1
BRTSn CRTSn TS
n (The inspection input value 1TSI with the same phase and the same amplitude value on the remaining ends is 31.) Sn Therefore, if there is no defect in the device, the difference current value of each phase is: 3i in i dRll TSn 31 dsn in TSIi i Medium 3i dT11■SII If there is an abnormality, i ==3i +ε dlln TSn+ Ri
=3i +ε dSI TSi Si =
3i +ε dTI TSn T. Here, εR1εS and ε■ indicate errors generated for each phase.

In steps ① to ②, the difference current in the above equation is compared between each phase, and if the difference is below a predetermined level, it is determined to be normal, and otherwise, it is determined to be abnormal.

The determination formula is as follows.

I 1≦ε ・・・・・・(1) dR
3.

I 1≦ε ・・・・・・(2) ds
T.

■ 1≦ε.

dTR... (3) I 1-31. sl≦kXI11sl (representative phase) dR (4) Here, jI l, if l, jI l are dR8dST dTR respectively i = i -1 dsi dRn dSli
=i −i dsTm dSl dTii =
f −1 dTRn+dTIl dltn is the magnitude of the difference between the phase difference currents obtained from the calculation result, b. Su, ε. is an error caused by the hardware of the device, for example ±1%
2%. Furthermore, k in determination formula (4) is O<k
is a constant in the range <1. If the device is normal (
1) to (4) are all satisfied, and the device is judged to be normal. However, if, for example, there is an abnormality in the R-phase analog input section of A1, judgment formulas (1) and (4) will not hold. Therefore, an alarm command is outputted through the output interface unit 14 as an inspection failure.

Although not shown in the figure, in order to ensure sufficient time for inspection and confirmation, when the start of inspection is detected, the processes from step ① are repeated multiple times. (For example, it is converted into hours and is several 100
113. ) According to the above determination formula (4), it is possible to detect the transient state of the analog input section of all terminals with high sensitivity. In other words, a check current should be applied to the device at the same time to each terminal of the simultaneous failure signal described above, but if there is a time difference, that is, if a check input as shown in Fig. 2 is applied, ΔT During the time period, the difference current "dR" is II=lI
jI +1dRATS BRTS
2 ITs in CRTS, and ended up being IITs in I-31! >k dRTS x l ITSI (o<k<i>, so the judgment formula (4) does not hold and an abnormality is detected.However, in the time period after ΔT, the judgment formula (4) is clearly satisfied.
holds true and is determined to be normal.

Therefore, by calculating the difference between the difference currents of each phase of all terminals, the inspection judgment according to this embodiment can be performed without adding any special hardware. All terminal analog input sections can be inspected with high accuracy without considering fluctuations in the power supply. Furthermore, errors in the transient state of the all-terminal analog input section can be detected with high precision, and this can be used to reduce the need for on-site inspections.

In other words, if the test power supply is driven by the simultaneous failure n occurrence signal that occurs when the inspection starts, and each phase test current set in advance is applied to the input converter 5 of each terminal, the circuit configuration can be changed. Due to the differential current generated transiently, it is possible to prevent operation at locations other than the measurement point. That is, in the case of a differential current during a transient period, the conditions of steps (1) to (4) described above are not satisfied and an abnormality is determined, and by locking the relay judgment output to the return side during the period during which the abnormality is detected, malfunction can be prevented. On the other hand, during steady state, although a difference current is generated between each phase, steps ① to ② are satisfied, so relay determination can be performed and characteristics can be confirmed.

Such a test can be performed at any time by manually starting the inspection.

In the above embodiment, a digital current differential protection relay device for a 3-terminal power transmission line was described, but it is not limited to this, and the protection is for multi-terminal power transmission lines such as 2 @ child power transmission lines, 3 f 4 child or more, and bus bar protection. Needless to say, this also applies to the following. Particularly in the case of multi-terminal power transmission line protection e-electric devices, the inspection method according to the present invention allows simultaneous inspection of all terminal analog input sections with high precision using only software without the addition of special hardware. Since on-site acceptance can reduce the amount of testing required, the effect is greater than that of two-terminal power transmission line protection. X. The above embodiment describes a current differential protection relay device that transmits current data, but
A protective relay device that mutually transmits voltage data and power data and performs relay judgment, for example, JP-A-50-104571
It can also be applied to the step-out detection method described in the issue.

That is, the phase angle θ of the voltages V A and V B at both terminals of the power system
and V A , the magnitude of the vector sum of V a is 10 V B
It can also be applied to a step-out detection method in which the quantity y=cosθ+klvA+vBl (k: constant) is obtained from lc, and step-out within an interval is determined on the condition that this y exceeds a set value.

〔Effect of the invention〕

As explained above, according to the present invention, when inspecting a digital current differential protective relay device, inspection inputs having the same magnitude and phase are simultaneously applied to the circuits corresponding to each phase of each terminal, and as a result, Since the difference between each phase is detected, a digital differential current protection inspection method that allows highly accurate inspection is provided.

[Brief explanation of the drawing]

FIG. 1 shows Il! according to the present invention. Flowchart of the inspection method for electrical equipment box, Figure 2 is an example of the current waveform when applying inspection input, Figure 3 is the circuit configuration diagram of the conventional device, Figure 4 is the flowchart of the conventional inspection method, and Figure 5 is the inspection current. The application circuit, FIG. 6 is a circuit configuration diagram at the time of power flow cancellation. 5...Input converter 6...CPU7...Relay determination section 8...Filter 9...-Sampling hold circuit 10...A/D converter 11...Communication device 12
...Communication line 13...Compensation circuit 14...
・Output interface

Claims (1)

[Claims] The amount of electricity in the power system is sampled at the same time and at regular intervals at each power station, and this sampling value is converted into an analog/
After digital conversion, each electrical station sends and receives the data via transmission equipment, and each electrical station introduces the received data and own-end data to the relay judgment section, and calculates the operation from both data. In a digital current differential protective relay device that processes to determine whether the amount of electricity is equal to or greater than the suppressed amount of electricity, when inspecting the protective relay device, a A digital device characterized in that a check input having the same magnitude and phase is simultaneously applied to an input circuit provided in the input circuit, and it is determined whether the magnitude of the difference between each phase of the operating electrical quantity is less than or equal to a predetermined value. Inspection method of current differential protection relay device.