JPS60109717A - Protecting relay system - 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] [Field of Application of the Invention] The present invention relates to a power line conveyance protection relay system for protecting against ground faults in resistance-grounded power transmission lines, and particularly relates to ground fault protection in parallel or multi-terminal systems. The present invention relates to a protective relay system having protective performance suitable for protection.

[Background of the invention]

As a ground fault protection system for parallel or multi-terminal resistive grounding transmission lines, there is a ground fault active current ratio differential system that uses power line carriers as a transmission means. As an example of this, the effective zero-sequence current at each end of the protection zone is converted into the time width of carrier wave transmission or transmission stop and mutually transmitted, and upon reception, it is integrated in proportion to that time and the required ratio difference is calculated. There is a so-called pulse width modulation transmission ground fault effective current ratio differential method that obtains dynamic characteristics.

・Figure 1 shows a diagram of the principle when applied to a three-terminal power transmission line. A one-line ground fault occurs at point F within the protection zone of the transmission line, and zero-sequence fault currents IAIIB, IC flow at each terminal station A, B, and CK, and zero-sequence voltages V OA, Von .

Assume that Voc occurs. To explain the operation of each end using the A end as a representative, the above zero-sequence voltage VoA is generated from the voltage transformer PD.
An accident detection circuit (earth fault overpressure detection circuit) 1 is used to detect an accident. Furthermore, from the zero-sequence voltage voA of In-phase or anti-phase component) IAcoS
Derive θ^. Then, the ground fault active current I m sin
The current/time conversion circuit 4 converts θ to the required pulse width (time width), and passes it through the carrier terminal station device 3 as an own-end signal.
It is transmitted to the other end stations B and C, and is also introduced into the time integration circuit 7A of the own end. Effective current IBcO at the other end
s(L, I c cosθC(Fig. 2(b), (C
The information converted into the pulse width (see ) is received by following the carrier terminal device 3, and is introduced into the receiving circuits 5 and 6 to establish the necessary interface with the carrier terminal device 3. Furthermore, the effective current information converted into the pulse width of the other end obtained by the receiving circuits 5 and 6 is introduced into the time integration circuits 7B and 7C in the same way as in the case of the own end signal (1 reception Sθ^). . Here, the time integration is started under the condition of the fault detection circuit of fault detection circuit l, and the pulse width information at each end is integrated, and the effective current at each end is
coSθA+I+cosθB.

Obtain I CCO3θC as an integral value. Further, these integral values are introduced into an integral determination circuit 8, which performs the necessary ratio differential calculation, and if it is determined that an internal fault has occurred, an output is output from the output terminal 9.

The above operation will be further explained using waveform diagrams as shown in FIG. Incidentally, in FIG. 3, the transmission delay time is arbitrary. First, a one-line ground fault occurs in the system, and a zero-sequence voltage is generated, which is detected by the fault detection circuit 1 and outputted. At the same time, in the current/intercostal conversion circuit 4 at its own end, the effective component 1 of the preceding stage [the effective component current detected by the i current detection circuit 2]
The pulse width is converted to a pulse width corresponding to a time Tm proportional to sθA. In the example of Figure 3, the effective component i and cos θ. 〉0... Effective component without signal I * cos θ, <0...... With signal, but in addition to this, effective component ゎ + X + S θ, = 00 and proportional to effective component current After the pulse width has been changed for a while, control is performed so that the wave becomes a continuous wave.

The output waveform of the current/time conversion circuit 4 at its own end shown in FIG. 3 shows the example shown in FIG. 2 where ACOSθ^>0.

Further, information on the opposite ends B and C can be obtained through the carrier terminal equipment 3 and the receiving circuit 5.6, and the waveform thereof is shown as the output waveform of the receiving circuit 5.6 shown in FIG. be able to. At this time, the effective current In θBIICCOSθC at the 13 A+C end is 0 as shown in FIG. Based on the pulse width introduced as described above, the time integration circuits 7A, 7B, and 7C perform integration, and the effective current at each end can be obtained as the integral value. This integral value is introduced into the integral judgment circuit 8, and the sum of the residual effective currents is calculated as ΣI = I A CO3θA k (IBCOSθn-
1-Iccosθc) = (1), and when the value of Σ is higher than the required set level, it is reported as an internal accident. In Shobu (1), there is a ratio coefficient (>1), which may be set according to the amount of outflow of parallel zero-sequence current in the event of an internal accident or the amount of shunt outflow current from the beginning of a multi-terminal.

The conventional ground fault effective ratio differential method has been explained above, but in this conventional method, after the current/time exchange is completed or
When the effective current is -00, the waveform is an intermittent wave, so the following problem actually occurs. That is, the passage shown in Figure 4,
In the example of the own end (A end), the wave becomes intermittent after the time TA which is proportional to the effective current (T) θm, but if this state continues, it may be due to hardware errors or errors in the transmission system. The output of the time integration circuit 7A (same as 7B and 7C) is a sawtooth wave, and its average value is not a constant value as in a of Figure 4, but has an error as in b or c. The integral value increases or decreases due to integration, making it difficult to accurately determine the ratio difference and causing unnecessary response.

In particular, when applied to other terminal systems, the errors at each end of the mining section will be superimposed, making the conditions even more severe.

[Purpose of the invention]

From the above, it is an object of the present invention to obtain an accurate ratio difference i! without being greatly affected by various errors! It is an object of the present invention to provide a differential protection pass percentage method capable of calculating tII7pI.

[Summary of the invention]

In order to solve the above-mentioned drawbacks of the conventional method, the present invention is characterized in that an intermittent wave detection circuit is provided to derive an accurate integral value.

[Embodiments of the invention]

The content of the present invention is shown in FIG. .

Furthermore, the output of the time integration circuit 7A is introduced into an integral value storage circuit 11 to be stored for a necessary time period which will be described later. Here, if the intermittent wave detection circuit 10 detects that the output of the current/time conversion circuit 4 becomes an intermittent wave, the integral value storage circuit 11 extracts the stored data immediately before the output becomes an intermittent wave, Integral value freezing circuit 1
2, the data is frozen to obtain an accurate integral value of the effective current that is not influenced by the intermittent wave signal, and the integral determination circuit 8 performs ratio differential determination. The above operation,
A more detailed explanation using the waveform diagram of FIG. 6 is as follows. In other words, if the output of the current/time conversion circuit 4 becomes an intermittent wave, the intermittent wave detection circuit 10 detects this (in the example shown in Fig. 6, two cycles of intermittent waves are confirmed), and the output immediately before the intermittent wave becomes an intermittent wave. Data of the coupling effective component i and cos θA (d in Fig. 6)
6) is extracted from the integral value storage circuit 11, the data (indicated by e in FIG. 6) is processed in the integral value freezing circuit 12, and the integral is determined based on this frozen data. Here, the data storage time in the integral value storage circuit 11 may be set equal to the detection time of the intermittent wave detection circuit 10 (equivalent to two cycles of the intermittent wave in the example of FIG. 6).

In the above, Fig. 5 and Fig. 6 were explained focusing on the self-end signal.
By applying the circuit according to the present invention shown in FIG. 5 to the effective current signal at the other end (that is, the output of the receiving circuit 5.6 in FIG. 1) transmitted from the other end through the carrier terminal equipment, , similarly unaffected by intermittent wave signals,
An integral value corresponding to an accurate effective current can be derived.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to perform ratio differential judgment based on the accurate integral value of the active component current, which is not affected by the intermittent wave signal, and it is possible to perform ratio differential judgment based on the integral value of the accurate active component current, which is not affected by the discontinuous wave signal. It is possible to achieve highly accurate judgment without worrying about unnecessary responses due to superimposition and integration.

[Brief explanation of drawings]

Figure 1 is a circuit explanatory diagram of the conventional ground fault effective ratio differential method.
Figure 2 is a vector diagram showing examples of voltage and current at each end of the protection zone, Figure 3 is a waveform diagram to explain the operation of the conventional ground fault effective ratio differential method, and Figure 4 is a waveform diagram of the conventional method. A waveform diagram for explaining the problem, FIG. 5 is a circuit explanatory diagram of the present invention, and FIG.
The figure is a waveform diagram for explaining the present invention in detail. 1... Accident detection circuit, 2... Effective current detection circuit, 3... Carrier terminal station device, 4... Current/time conversion circuit, 5... Receiving circuit, 6... Receiving circuit, 7A, 7B,
7C... Time integration circuit, 8... Integral judgment circuit, 9.
・・Output terminal, 1st concave 2nd <l C et al.) (C) IcC6suσC 3rd layer ΣI, lAθ7's I, θshame θ8su ItQ Ririkaya
4 mouths 5 mouths

Claims (1)

[Claims] 1. In the protective relay method, which obtains differential characteristics by mutually transmitting time-converted signals according to the magnitude of the effective zero-sequence current at each end of the protection interval and time-integrating the signals, the effective zero-sequence After the time width conversion of the current is completed or when the effective zero-sequence current is zero, a predetermined intermittent wave is transmitted, and when an intermittent wave is detected, differential part determination is performed based on the time integral value immediately before the intermittent wave becomes intermittent. Features a protective relay system.