JPH0251311A - Current differential relay - Google Patents

Abstract

PURPOSE:To eliminate unnecessary trip due to function of a current operation relay by the uncompensated charge current component, when a system is charged from one terminal, by delaying the function of a current differential relay for a predetermined time after closing of a circuitbreaker at self terminal. CONSTITUTION:Function of a current differential relay 23 is delayed by a time (t2) through an ON delay timer 18 for an interval (t1) determined by an ON delay timer 17 from a time point when an output representing change of a self terminal circuitbreaker from open to close is produced, thereafter switching is made to the output from the current operation relay 23. A circuitbreaker is tripped on AND condition of the outputs from the current operation relay 23 and an under voltage relay 24. The current operation relay 23 may molfunction due to uncompensated charge current when the circuitbreaker is closed, but the circuitbreaker does not trip because of the delay function of the OFF delay timer.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a protective relay device for protecting a power system, particularly a current differential relay device for protecting power transmission lines based on the current differential principle. Regarding.

(Prior art) As a protection method for power transmission lines, a current differential method is often used to identify internal and external faults on power transmission lines by using the instantaneous value of the current at each terminal, and current differential relays that use this method are often used. ing.

A problem when applying current differential relays is the effect of charging capacity within the protection zone. That is, in FIG. 4, a current transformer 28 is installed at each of A and B 111 of the protected power transmission line 1.

The current differential relays 3A and 3B, which perform current differential protection by transmitting and receiving instantaneous values of electrical quantities corresponding to the current amounts t^ and tH at each end using the relays 2B, adopt the following determination principle.

(Id is a differential current and corresponds to a fault current.

t^ and tB introduce currents in the internal direction so that they have the same polarity. ) Id=lt^tental ・・・・・・■
However, due to the influence of the charging capacity C within the protection zone, the charging current tc flows out in the event of an external fault at the F point, so the amount taken in at the B end becomes to +tc. Therefore, the differential current Id
becomes the following formula 0.

td=1t^+t^+tel ・・・・・・■
In the case of an external accident in Type 0, t^10tB =.

Therefore, the formula 0 becomes Id=ltcl, and if the internal charging capacity is large, the current differential relay may malfunction.

The internal charging capacity has a large value between the ground and the cable section of the power transmission line, and due to the long distance of 1000kV class trunk power transmission lines, the internal charging capacity has a large value between lines or between phases within the line even in an overhead system. It is known for its large charging capacity.

For this reason, measures are taken to prevent malfunctions due to charging current by compensating the amount of electricity due to the charging capacity within the protected area inside the relay using the voltage value of its own terminal.

[Reference 1: Electric Kyodo Research Vol. 41 No. 4 "Charging current compensation in digital relay JP178r ultra-high voltage current differential relay" (published January 21, 1986)] Figure 5 shows a conventional system to which the above technology is applied. It is an example figure of a device. The voltage at the A terminal is taken in by the line side voltage transformer (line PD) 58, and sampled at the same time by the input processing unit 6A together with the amount of electricity taken in from the current transformer (CT) 28, and is converted into an analog signal.
converted to digital.

The calculation section 7A performs the following calculation based on the output of the input processing section 6A.

i,=t^-ni Takumi ・・・・・・■t Similarly, at the B end, the following calculation is performed.

t B −t'B K ! lL! L
・・・・・・■t This is how it was obtained! A' and "B" are transmitted and received between the opposing electrical stations via the transmitter/receiver section 8^.The arithmetic section 7A uses the output of the transmitter/receiver section to perform current differential determination by calculating the equation 0.

dt dt ≧, ・・・・・・■
In the above equation, iA, t is the current data at each terminal, x d V A= is the data corresponding to the dt differential value of the voltage taken at the A terminal, and x d V R is the data corresponding to the dt differential value of the voltage taken at the A terminal (K is the constant t The amount corresponds to the internal charging current.

In the 2@ child configuration as shown in Figure 4, the internal charging current is 17
2 at each terminal.

0 is the relay's operating degree, and when this rising differential current 1d is large, it is determined that there is an internal fault.

The opposite B@ also has the same angle as above.

(Problems to be Solved by the Invention) Consider a case where only the power transmission line 1 is charged from one terminal (terminal A) as shown in FIG. In Figure 6, terminal A is treated as the power supply terminal, and terminal B is treated as load@. At this time, the B end is the rest end, so Bfli
Generally, the current data tB transmitted from the ij is treated as zero at the A terminal. (To ensure that the current differential relay operates even if an internal accident occurs while charging the power transmission line) Therefore, when the breaker 9A is turned on, to' = o,
From i^=4C, the 0 formula is Id= lt'c Kd! -L
l≠0.

dt Normally, when the circuit breakers 9A and 9B at both terminals are closed, charging current compensation is considered, so in the case shown below, only 172 of the charging current tc is compensated, and the remaining 1/2 is the uncompensated portion. Therefore, charging current compensation is not perfect. If this uncompensated amount exceeds the sensitivity of the current differential relay, unnecessary operation will occur. On the other hand, the determination of internal accidents is generally made using the differential relay output 1, which is the main detection relay.
5A and an undervoltage relay output of 16A that serves as an accident detection relay to detect when the system voltage falls below a certain value.
Perform under ND conditions. When there is a voltage transformer on the line side, the above-mentioned coos can be expressed as a time chart as shown in FIG. 7.

Assuming that the time from turning on the breaker 9A until voltage is applied to the power transmission line and the undervoltage relay returns is t4, and the time until the differential relay operates unnecessarily due to the uncompensated portion of the charging current is illusory, e4 where the condition t4 > 63 is satisfied
- There is a possibility that it will be mistakenly determined to be an internal accident for t3 hours and trip.

Example of actual value of C4; 8 to 28 Ils Example of actual value of C3; 9 to 25 m5 The present invention was made to solve the above problems, and it takes in the voltage amount of the grid and It is an object of the present invention to provide a protective relay device that can protect a power transmission line without malfunctioning even during system charging from one terminal when using a current differential relay that compensates for charging current.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention is configured to delay the operation of the current differential relay for a certain period of time after the self-ended breaker is closed.

(Function) By adopting the above configuration, even if the current differential relay malfunctions due to the uncompensated portion of the charging current when charging from one terminal to the grid, the NO condition with the undervoltage relay will not be established, making it unnecessary. Trips can be prevented.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the functions of a current differential relay device installed between the A terminal and the B terminal in FIG. 6. The breaker closed output 22, which is output when the breaker of its own terminal is open or changes from open to leap (when the breaker is closed), is the output 23 of the current differential relay until time C1 determined by the on-delay timer 17. is delayed for C2 time by the on-delay timer 18, and thereafter the output C of the current differential relay is switched as is.
An AND configuration of this output and the undervoltage relay output 24 is configured to output a breaker trilag command.

FIG. 2 shows a response time chart of this circuit when the breaker at the opposite end is closed and the breaker at the own end is closed. Since voltage is applied to the power transmission line by turning on the breaker, the undervoltage relay returns after the return time t4. The current differential relay operates after operation time 03 if the uncompensated portion exceeds the operating value due to the uncompensated portion of charging current compensation. The output signal 18A of the on-delay timer 18 becomes '1' after C2 of the current differential relay operation.

Here tl>C4l1ax and t2+6311n>
By configuring the on-delay timers 17 and 18 to satisfy the interval of C41aX, unnecessary tripping can be reliably prevented even if the current differential relay malfunctions due to the uncompensated portion of the charging current.

However, 631n; the minimum possible value of 63; t41aX; the maximum possible value of C4; In the above embodiment, the breaker close signal is used to control whether or not to add a timer to the output of the current differential relay; As shown in FIG.
It goes without saying that even if the output 23 of the current differential relay is delayed for the time extended by 6, the same effect as in the embodiment can be obtained.

[Effects of the Invention] As explained above, according to the present invention, in a device in which internal charging current compensation is added to the current at each end and transmitted, and current differential protection is performed using the obtained electrical quantity, when the other end is a rest end, Even if the current differential relay malfunctions during grid charging due to the uncompensated internal charging current that occurs due to the uncompensated internal charging current, it is definitely unnecessary because the operational output of the current differential relay is delayed for a short time when the breaker is closed. Trips can be prevented.

[Brief explanation of the drawing]

Fig. 1 shows the equipment configuration of one embodiment of the present invention, Fig. 2 shows a time chart for explaining the invention in detail, Fig. 3 shows the equipment configuration of another embodiment of the invention, and Fig. 4 shows the internal structure. Figure 5 is a diagram explaining the influence of charging current. Figure 5 is a diagram showing the conventional configuration of a current differential device that performs charging current compensation. Figure 6 is a diagram explaining the problems of the conventional device. Figure 7 is a diagram explaining the problems of the conventional device. It is a time chart explaining the problem. Id...Differential current -tc...Charging current 3A, 3B
... Current differential relay 9A, 9B ... Circuit breaker agent Patent attorney Norihiro Ken Yudo Daishimaru Ken Figure 5 Figure 3 Figure 7 - One dispute

Claims (1)

[Claims] The amount of electricity obtained by combining the amount of charging current compensation due to the voltage at the other end terminal with respect to the current at the other end is received from the other end electrical station, and the amount of electricity obtained by combining the amount of charging current compensation due to the own terminal voltage against the current at the own terminal is received. In a current differential relay device that protects a power system with a differential relay by obtaining a differential current using the amount of electricity received from the electric power station received from the opposite end electric power station, the differential relay has its own terminal. A current differential relay device characterized by delaying operation for a predetermined period of time after the circuit breaker is turned on.