JPS5976116A - Current difference protecting relay - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a current differential protection relay for power transmission line protection in electrical power systems.

Conventionally, this type of current differential protection relay is commonly used as shown in Figure 1 (-
A circuit system as shown is known. In Figure 2, 1 is a current-voltage conversion circuit that converts the grid current into a CT (current transformer).
2 is an FM modulation circuit that converts the output signal of the current-voltage conversion circuit 1 into a frequency change in the voice band; 3 is an FM modulation circuit that converts the FM-modulated signal to the other end of the power transmission line. 4 is a radio receiver that receives the signal transmitted upstream from the other end of the power transmission line; 5 is an FM demodulator that detects FM modulated current information at the other end as an AC voltage; Reference numeral 6 denotes a differential performance circuit that operates on the difference between an AC voltage representing the frost at one end of the eye and an AC voltage representing the current at the other end, and 7 represents a circuit in which the output signal of the differential performance circuit 6 is set in advance. When the voltage level is exceeded (two voltage level detection circuits are activated).
FIG. 2 is a waveform diagram illustrating the operation of the circuit shown in FIG. 1.

Next, the operation of the U.S. circuit shown in FIG. 1 will be explained below. System current Ia and current voltage conversion circuit 1 (=Therefore, AC voltage V
a1ζ: Converted n, and further F by the FMff adjustment circuit 2
Transmit to wireless transmission @ Tsuki 3 as a signal a1. In addition, the current information at the other end is received by the radio receiver 4 and sent to the FM demodulator 5 as 2''I voltage Fa2.
After the conversion to 2, the performance is played in the differential performance circuit 6.

When there is no failure in the power system (=, the differential output vA of the differential performance circuit 6 is zero, and when there is a failure, the differential output VA of the differential performance circuit 6 increases. When the constant @SH is exceeded, a breaker trip command TA is output.

As mentioned above, in order to provide current differential protection for each of the A, B, and C phases, it is sufficient to provide three channels of FMi-based transmission paths. However, if the received waveform is disturbed by noise in the transmission line, disturbances, etc. (2), there is a possibility that erroneous outputs may occur (= other than system failure), so a 4th channel other than the above channels is used to detect noise. In other words, the means for transmitting the electricity transmitted on the fourth channel,
Volume (=sum of each phase current, 3 I o = I a + I
b 1 I c is used to obtain ideal noise detection.

However, the conventional current differential protection relay equipment is as described above (:
Since the configuration was 1, the 4th channel (: 3) was transmitted for noise detection, and the zero-sequence current (differential protection due to As a result, there was a major drawback in that the ability to detect ground faults in the power system's transmission lines was low.

The present invention was made in order to eliminate the drawbacks of the conventional current differential protection relay system as described above. and the sum of the FM double-toned output signals for each phase. The purpose is to provide

An embodiment of the present invention will be described below with reference to the figure.

In FIG. 3, the same parts as in FIG. 1 are shown with the same numbers. 8 is the first addition circuit A.

B, C@ phase current c: corresponding voltage Va1. Vb1
Add ゜V c 1 and make 3 steps. Derive the components, also 9
is the Meisoden 1I received from the other end in the same second Kabu circuit.
lfc=corresponding voltage V a 2 r V b 2 *
3I with V c 2.

The circuit for deriving the components, 1o, is the output of the 27th JD% circuit 9 and the 3 components received from the other end. A second differential performance circuit 11 for determining the difference with the component Vo2 is shown by omitting the phase current differential performance circuit 6 and the level detection circuit T in FIG.

The operation of the present invention constructed in this manner will be described below. FIG. 3 (2) The second am circuit 9 and the second differential η circuit 10 generate each phase current value Va 2 + b2.
■Difference between sum Vs of C2 and zero-sequence current 3Io component Vo2 ■E
seek. By doing this, if there is an abnormality such as noise in the transmission path (: output of the second differential performance circuit 10
ぢ■E becomes zero. In addition, if there is an abnormality in the transmission path, the level detection circuit 71 (-) is interlocked by the output signal -@VF of the second differential performance circuit 10, and becomes inactive.The above example uses the fourth channel. However, the amount of electricity transmitted through the fourth channel is a zero-sequence current of 3 I. Since the first differential performance circuit 61 and level detection circuits 71 and 32 If the differential voltage between □ and the other end Vo2 is 1, it becomes possible to use zero-sequence current differential protection at both ends of the power transmission line.

In the above English example, the FMt which modulates the grid current and transmits it
I mentioned the current differential protection relay, but the P that transfers the instantaneous 1 of system Akiryu U1 digitally and converts it into pulses and transmits it.
A similar effect can be obtained in the current differential protection relay C2 using CIVI modulation.

As described above, the present invention (second and first) uses the fourth channel for noise detection as a means for improving the operational reliability of each phase current differential protection relay, that is, the zero-sequence current 3 IoT'i 5 minutes and each phase subsequent @ No. 7 JD Mai. The second differential operation n circuit is operated between the output terminal and the current voltage converter circuit for each phase of the system (= the sum of the output outputs is The first differential performance circuit is activated and the second differential performance q is guided to the Lebel detection circuit.
Circuit (: Therefore, in the event of an abnormality (:) Since the current differential protection relay output is blocked, the number of transmission lines must be increased. In addition, the zero-sequence current differential protection force formula has an extremely high detection ability for high-resistance ground faults during heavy #I flow, so-called micro-ground faults. Figure b (I engineering N
and engineering. U, indicates the inflow and outflow values of each phase current) (=
As shown in Fig. 4, the conventional differential relay for each phase current RY separates the fault current IT from the operating range A due to CT errors, saturation, etc., and malfunctions tJ (because it has a two-ratio characteristic, When a ground fault with a large resistance occurs in a system where the M current follows the same pattern as in By adding a zero-phase differential operating circuit, there is no influence from the power flow (7J) as shown in Figure 4C, which has an excellent effect of improving the operational reliability of the optical current differential protective relay. There is.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional differential relay for each phase current;
The figure is an operation explanatory diagram showing the operating state of Figure 1 as a waveform, and
A block diagram of a zero-sequence current differential relay according to Example C2 of the present invention, Figure 4 is a sensitivity comparison of each phase current differential output and zero-sequence current differential output at the time of a slight ground fault. It is a diagram. 1... Current 'turquoise pressure conversion circuit, 2... FM modulation circuit,
3...Wireless transmitter@machine, 4...Positive line receiver@machine, 5...F
M multi-facet circuit 6... differential performance circuit, 7... level detection circuit, 8... first performance circuit, 9... 2710th device circuit, 10... second differential performance circuit Leg circuit, 61...first differential performance circuit. Note that in the figures, the symbols indicate the same or equivalent parts. Agent: Haku Kuzuno (1 person) Figure 2 Figure 3 Figure L-J Figure 4 is b-9 (1) Mr. Commissioner of the Japan Patent Office 1, Indication of the case Patent application 186313-1983 Relationship with the car number case Patent applicant representative Hitoshi Katayama Department 4 Address of agent 2-2-3-5 Marunouchi, Chiyoda-ku, Tokyo Subject of amendment (1) Claims column of the specification (2) ) Detailed description of the invention in the specification (3) Drawing 6, contents of amendment (1) Amend the claims as shown in the attached sheet. (2) Add l”FM on page 4, line 5 of the specification. "Compound temperature control output signal sum" says, "Correct it to the sum of self-end input currents 5 IoJ. (3) r Iout J on page 6, line 16 of the specification.
Correct it to r l0UT J . (4) Figure 4 (C1 is amended as shown in the attached sheet). 7. List of attached documents (1) One document stating the scope of claims after the amendment (2) Figure 4 after the amendment (C1 is stated) Document: One or more amended patent claims The inflow and outflow currents of each phase transmission line in a power transmission system are applied to a differential calculation circuit of each phase, and the calculation result of the differential calculation circuit exceeds a predetermined set value. In a current differential protective relay that occasionally generates an output command, a zero-sequence current is detected at the current inflow end and outflow end of the power transmission system, and a 19th differential calculation circuit separately detects the inflow current and outflow current. A current differential protection relay is characterized in that a fourth output of the current differential protection relay is generated when a difference between the inflow and outflow current values is generated in a level calculation circuit by a predetermined level value or more.

Claims (1)

[Claims] A current difference between the inflow and outflow currents of each phase transmission line in the power transmission system and the differential performance circuit that generates an output command when the performance R connection in the differential performance circuit exceeds a predetermined setting device. In the dynamic protection relay, a zero-sequence current is detected at the current outflow end of the power transmission system, and the inflow and outflow currents are compared separately by a first differential calculation circuit, and the difference between the inflow and outflow currents ω is determined. A current differential protection relay characterized in that the output number of the current differential protection relay is set to transmit a blocking command when M plus bells D± occur in a level performance circuit.