JPS6035889B2 - Accident detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fault detection method when an internal fault occurs when a line fault charging is performed from only one end of a system in which a phase comparison transfer protection relay system is installed.

As a protective relay layer for important power transmission lines such as so-called main power transmission lines in power systems, a high-speed operation, high-reliability type transport protection relay layer with excellent protection performance is generally adopted.

In particular, ultra-high-voltage and ultra-super-high-voltage power transmission lines are equipped with a phase comparison transport protection relay system for each phase that can apply a multiphase reclosing method that selectively disconnects only the failed phase and recloses the circuit at high speed. By the way, even if an internal accident occurs in a system where the power supply terminals are treated as both ends in which a phase comparison transfer protection relay layer is installed, and the power transmission line is being charged from only one end, the conventional accident detection circuit will not detect the power at the idle end. Internal accidents are not detected in many electrical stations, and therefore, for example, it becomes impossible to grasp the fault point or start the oscilloscope, which causes serious problems in the analysis of accident phenomena. The present invention was developed in view of these problems, and it detects only the occurrence of internal accidents by determining the nature of the phase signal from the charging end even on the idle end of a power transmission line that is being charged from only one end. This is an attempt to understand the accident phenomenon by displaying it in the necessary places or starting an oscilloscope to reliably record the accident phenomenon.

Below, a conventional accident detection circuit will be described with reference to FIG. 3, and then an embodiment of the present invention will be explained with reference to FIGS. 4 and 5. The operating principle of the lightning method will be explained.

FIG. 1 shows a power system in which the phase ratio shark relay 7 is installed, and the phase ratio shark relay is installed at electric station A and electric station B.

Items common to both electrical stations are designated by the same reference numerals. 1 is a busbar, and 2 is a combination of generators behind the electric station. When an accident occurs on a power transmission line or the like, fault current is supplied from this generator.

The busbars 1 of electric stations A and B are interconnected by a power transmission line 5 via a power disconnector 4, respectively. When a fault occurs on the power transmission line 5, the current transformers 3 installed at both electric stations generate a secondary current 6 proportional to the fault current flowing through the power transmission line 5 to the phase ratio shark relay 7.
The output circuit 11 of 7 opens the breaker 4. The secondary current 6 guided to the phase ratio relay 7 is converted from a sinusoidal alternating current into a rectangular wave by a rectangular wave shaping circuit 8 inside the phase ratio relay.

The rectangular wave created by the rectangular wave shaping circuit 8 is guided to the matching circuit 9 of the own-end phase ratio shark relay 7 (actually, the transmission delay time until the signal transmitted from the other end reaches the matching circuit 9 of the own end) (although it is omitted here to simplify the explanation), it is simultaneously transmitted to the transmitter 13 of the information transmission device 12, and generally transmitted to the microwave line 15.
The information is transmitted to the receiver 14 of the other party's information transmission device 12 via. On the other hand, similarly, the other end rectangular wave sent through the microwave line 15 by the transmitter 13 of the other end information transmission device 12 is transmitted to the receiver 14 of the information transmission device 12 at the other end.
is introduced into another input of the matching circuit 9 of the phase ratio relay 7. In the matching circuit 9, an AND signal of the rectangular wave signals at both ends is created, and this magnitude is determined by the next integrating circuit 10.
If the magnitude is greater than (generally 60 degrees) which can be determined as an internal accident to be protected against, the output circuit 11 issues a command to trip the sheath breaker 4. In Figure 1, only one set of phase ratio shark relays is shown, but in reality A
, B, and C phases, and the above-mentioned operation is performed independently for each phase. Next, referring to FIG. 2, the response of the device shown in FIG. 1 to a system accident will be explained.

Components in FIG. 2 that are the same as those in FIG. 1 are designated by the same reference numerals. Second
Figure a shows the response to an accident outside the protected area, and as shown, the accident point F is outside the electrical station B.

Therefore, the secondary side A-terminal current 6A and B-terminal current 6A of the transformer 3
In B, the magnitude and phase are the same as shown in the figure. Here, to explain the promise of conversion into a rectangular wave in the rectangular wave shaping circuit 8, the A terminal current treated as the power supply terminal is
As shown in , it is converted into a rectangular wave by the slice level LH, and the positive half wave becomes a trip permission signal (hereinafter referred to as F2 signal), and the other section becomes a trip lock signal (hereinafter referred to as F signal). The B terminal current, which is treated as a variable power supply end, is converted into a rectangular wave by the low slice level L, and the A terminal current, which is treated as a power supply terminal, is
Contrary to the electric station, as shown in Figure 8B, the negative half wave is the F2 signal, and the other sections are the F2 signal. It becomes a signal. In the matching circuit 9, the F2 signals of the outputs 8A and 8B of the rectangular wave shaping circuits of the respective terminals are ANDed, but as shown in the output waveforms 9A and 8B in FIG. ,
The 11 output circuits have 10A, B, 11A, and B, respectively.
As shown in Figure 2, there is no signal at all, so no breaker tripping signal is issued. It is a well-known fact that the slice level LH at the power source end and the slice level LL at the variable power source end are configured such that LH>LL so that the F2 signals at both ends do not overlap due to an external accident. Figure 2b is
This is a case of an internal accident when power is supplied at both ends, and as shown in the figure, the fault point F is on the power transmission line 5 connecting electric station A and electric station B.

Due to the internal accident in the section, contrary to Figure 2a, the A secondary current 6A and the B end secondary current 6B of the transformer 3 are almost in opposite phase, as shown in the outputs 8A and 8B of the square wave shaping circuit. As shown in FIG. 2B, a rectangular wave is generated at each terminal station, and the F, signal, and F2 signal are generated. Therefore, coincidence outputs 9A and B as shown in FIG. 10, the slice level S of the integrating circuit is reached as shown in the integrating circuit outputs 10A and 10B, outputs 11A and 11B are output from the output circuit 11, and this signal causes the breaker to open. Therefore, accident F will be eliminated. In Fig. 2c, the accident point is inside the protected area, as in Fig. 2b, but unlike in b, there is no power source behind electric station B at the variable power source end (there is no generator 2), so B This is the case where no fault current is supplied from the end.

Therefore, the secondary current 6A at the A terminal and the rectangular wave shaping circuit output 8A at the A terminal are exactly the same as in diagram b. However, since there is no secondary current at the B end as shown at 6B, it is always below the LL level, and as shown by the rectangular wave shaping circuit output 88 at the B end, it becomes F2, that is, a continuous trip permission signal over the entire section.
Therefore, the F2 signal of the rectangular wave shaping circuit output 8A at the A end appears as it is at the outputs 9A and B of the double-end matching circuit 9, and as is clear from the integrating circuit output 10A and the B output circuit output 11A and B, the circuit breaker is tripped. A signal is emitted. In other words, one end (
If the slice level LL level of the rectangular wave shaping circuit 8 is set at the B terminal here, the F2 signal is generated by the negative half wave, so that it is possible to trip the breaker even if no fault current flows. As explained above, in general, one end is LH level operation type like at electric station A (this is called the power supply terminal), and the other end is LH level operation type like at electric station B.
It is assumed to be an L level operation type (this type of operation is referred to as being treated as a variable power supply terminal).

However, as is well known, in some systems, there is always a large power source behind both ends, and if the power cannot be turned off, both ends may be treated as LH level operation type power supply terminals. At this time, the explanatory diagram in Fig. 2 shows that both the electric stations A and B at both ends are in LH level operation, and the electric station B! Although not shown, the input current to the phase ratio relay is reversed.

In other words, treating both ends as power supply terminals means that if the current detected at each end is of the same polarity when an inflow current occurs during an internal fault, then at each end, when the current is greater than a certain value LH of the positive half wave, This means that it is used as a trip permission signal at certain times, and as a trip prevention signal at other times. Therefore, in the case of the external fault shown in FIG. 2a, the sine waves of the secondary currents 6A and 6B at each end will be in opposite phases, and the F2 signals generated above the LH level at both ends will not overlap. In addition, in the case of the internal fault shown in Figure 2b, the sine waves of the secondary currents 6A and 6B at each end will be in phase, and an F2 signal will be generated in the current range above the LH level, and since these will match, the output circuit 1
An output of 1 is output. However, as shown in Fig. 2c, when LH level operation is performed in the case where one end is loaded and both ends are treated as power supplies, the F2 signal cannot be generated at electric station B because the current is always below the LH level, and the operating output is 11 despite the internal fault. will never appear.
In other words, if both ends are treated as power supply ends, a case like the one shown in FIG. 2c should not exist. In other words, the main premise that both ends can be treated as power supply ends is that there is always a power source behind both ends that can supply sufficient fault current. However, even when this assumption is satisfied, power may be lost depending on the operation of the grid. This is a single-end charging operation, which will be described later, and when an internal accident occurs, it is possible to open the breaker closing terminal, but it has been found that it is not possible to detect the occurrence of an internal accident with an open terminal. FIG. 3 is a diagram illustrating a conventional internal fault detection circuit. Among the components shown in the diagram, the same components as those in FIG. 1 are denoted by the same reference numerals. I would like to clarify here that I will follow the same idea.

Fig. 3a shows the concept of a phase comparison transfer protection relay system for counterfeiting and disconnection, 7-1a is the output contact of the phase ratio shark relay 7, and 16 is the output contact of the undervoltage relay (not shown). When the grid voltage is input and an accident occurs in the grid,
Since the grid voltage drops, this is detected and the contact 1 is activated.
6 is closed. 17 is a coil of an auxiliary relay, and when this coil is excited, contacts 17 (not shown) are closed.
This contact energizes a tripping coil (not shown) of a breaker, thereby opening the breaker 4.

18-1a is a pallet switch for the breaker 4, which closes when the breaker is turned on and closes when it opens.

P and N are positive and negative busbars of the DC operation busbars, respectively. FIG. 3b shows a secondary internal fault detection circuit, 171a is a normally open contact of the auxiliary relay 17, and 712a is another output contact of the phase ratio shark relay 7 like 71a. The operation of the conventional internal fault detection circuit shown in FIG. 3 is as follows.

In the system shown in Figure 1, 7 at electrical station A is a phase ratio shark relay that operates at the LH level and is treated as a power supply terminal, and 7 at electrical station B is a phase ratio shark relay that operates at LL level and is treated as a variable power supply terminal. Now, when the power disconnectors 4 at both electrical stations are turned on and in normal operating condition, if an internal accident occurs in the transmission line 5, the phase ratio relays 7 at both ends will operate as shown in Fig. 2. , 7-2a are closed. In addition, due to a grid accident, the grid voltage decreased and
6 is also closed. However, since the breaker is in the closed state, the pallet switch 18-la is closed, so the auxiliary relay 17 is energized and its a contact 17-a is closed. That is, since both 171a and 7-2a are closed, the internal fault detection circuit (FIG. 3b) is established, and a starting signal is supplied to, for example, a display panel or an oscilloscope starting circuit. Next, consider an operating state in which the power transmission line 5 is charged only from electric station A, and the disconnector 4 at electric station B is in an open state.

The power supply conditions are the same as before: LH level operation at electric station A and LL level operation at electric station B. At this time, when an internal fault occurs in the power transmission line 5, the B electric station generates a continuous F2 signal with current ○, so the operation is the same as in Fig. 2c, and the internal fault detection circuits of the A electric station are 17-a, 7-2a. Both circuits are opened to reliably detect internal accidents. The pallet contact 18-la is open because the edge and disconnector of the B electric station are open, and the auxiliary relay 17 is not energized. Since the F2 signal of approximately 180 degrees is transmitted, the phase ratio shark relay 7 of the B electric station is operated and 7-2a is closed, so that an internal fault can be detected at the B electric station as well. Next, let's consider the case where both electric stations A and B operate at the LH level, that is, are treated as both-end power supplies.

If an accident occurs on the transmission line 5 during normal operation when the disconnector 4 is turned on at both electric stations, the phase ratio shark relay 7 will operate at both electric stations as described above.
A is open, and internal accidents can be detected at both electrical stations. Therefore, both power stations are treated as power supply terminals at both ends of the LH level operation, and only the switch 4 of the power station A is turned on, and the switch breaker of the power station B is opened, and one end of the power transmission line 5 is connected to the charging transmission line. Let us consider that an internal accident occurs on the power transmission line 5.

Terminal B with the breaker open transmits a continuous F2 signal, which will be described later in FIG. 5a. Therefore, when an accident occurs and a large fault current flows through the transformer 3 of electric station A, the rectangular wave shaping circuit 8 generates an F2 signal of about 180o, which activates the phase ratio relay 7 at electric station A, causing the internal fault detection circuit. Both 171a and 7-2a are closed, and internal accidents can be recorded. However, at this time, the breaker 4 at the electric station B is open, and the input current to the phase ratio relay 7 is ○, so the F2 signal is not generated at all, but is a continuous F signal. Therefore B
The contacts 7-2a and 17-a of the internal fault detection circuit of the electric station remain open, and the internal fault detection circuit is not established.For example, a signal is not given to the display or oscilloscope that receives this condition at the electric station B. Since the accident phenomenon is not recorded in the first place, this poses a major hindrance to later analysis of the accident phenomenon. Therefore, the fourth
An embodiment of the present invention will be described with reference to FIG. 5 and FIG. 5, and its effectiveness will be discussed. FIGS. 4 and 5 show internal fault detection circuits of the phase comparison transport protection relay system according to the present invention.

18-1b The b contact of the pallet switch of the breaker is open when the breaker is turned on, and closed when the breaker is opened.

23-b and 24-b are normally closed contacts of auxiliary relays 23 and 24, which will be described later.

FIG. 5a shows a known transport control circuit that has been implemented in the past. 18-2b Hashiya disconnector pallet switch 18
- This is a separate contact that operates in the same way as lb.

19 represents an OR gate, and PT represents a power supply for the transistor circuit.

When there is a signal from the rectangular wave shaping circuit 8 of the phase comparator 7 to the transmitter 13 of the information transmission device 12, the F2 signal is transmitted, and when there is no signal to the transmitter 13, the F signal is transmitted to the other end. Therefore, a command is issued to the shatter breaker, and when the shatter breaker opens, 18-2b closes, and a signal is continuously supplied from the power supply PT to 13 via 19, so that the other end is The F2 signal is sent continuously and the F2 signal is sent to the other end.
The signal does not depend solely on the output from the rectangular wave shaping circuit 8 (approximately 1800 repetitions of the F, . . . F2 signals) and is made more reliable by the contact operation of 18-2b. 20 to 24 in FIG. 5b are provided for the purpose of the present invention;
, 22 is a timer, which is set to operate within a time limit of approximately 4 seconds. Coils 23 and 24 of auxiliary relays are excited by the outputs of the timers 21 and 22, respectively.

In other words, the output of the receiver 14 of the information transmission device 12 is generally a repetition of F,, F2 signals, but when continuous F2 signals are received, the timer 21 outputs the output approximately 4 hs after it starts receiving continuous F2 signals. is emitted and energizes 23.
Also, when a continuous F signal is received, the input of the NOT circuit 20 is continuously 0, so the output of 20 is continuous.
Therefore, the timer 22 continuously outputs an output approximately 4 hs after starting to receive the signal, and excites the timer 24. From FIG. 4, it can be seen that the present invention has 181b
, 24-b, and 23-b are connected together, so its function is as follows.

This will be explained with reference to FIG. Both A and B electric stations are treated as LH level operation at both ends of the power supply, and the power supply terminals at electric station A are turned on, and the line disconnector 4 at electric station B is opened, and the power transmission line 5 is connected from electric station A. It is only charging.

Now, considering that a time ramoko accident occurs on the power transmission line 5 in this state, before the accident occurred, the A terminal current IA was almost 0 due to only charging, and since the electric station A operates at LH level, the carrier signal CaA is continuous F, sending a signal. Since the circuit breaker 48 at the electric station B is open, the carrier signal CaB is transmitting a continuous F2 signal by the circuit shown in FIG. 5a. Therefore, when looking at the circuit shown in FIG. 4 at the B end, the pallet switch 181b is closed due to the opening of 4B. In addition, in the circuit of FIG. 5b, the auxiliary relay 24 is in the operating state due to the reception of the continuous F signal, and the auxiliary relay 23 is in the inactive state.
Contact 24-b is open and contact 231b is closed. As a result, the circuit shown in FIG. 4 at the B end does not output any output and does not detect an internal fault. Next, considering that an internal accident has occurred, since the A terminal is receiving the continuous bait 2 signal, the F2 signal is generated at the self terminal due to the accident current, which activates the phase ratio shark relay 7A, and the time At t2, the breaker 4A is opened.

Then, the carrier signal CaA generated by the A end is made into a continuous F2 signal. When the carrier signal CaA at the A terminal changes as described above, in the circuit shown in FIG. do. Then, as the signal changes to a continuous F2 signal at the time, the auxiliary relay 23 operates at t3, 4 hs later. On the other hand, regarding the B-end breaker 4B, it remains open regardless of the presence or absence of an accident. Therefore, regarding the contacts 23-b, 24-b, and 18-b, they are closed simultaneously only in the event of an internal accident in which the carrier repeats F, F2, and the accident can be detected correctly. In other words, by applying the circuit of the present invention, it is possible to instantly detect an accident during one-end charging operation when handling both power supply terminals, which was impossible with the conventional method, and instantly detect only internal accidents, and activate equipment such as an oscilloscope that is required only during an accident. can give a signal.

Therefore, a device that operates under the conditions of the circuit of the present invention will not malfunction, and for example, the present invention will eliminate any malfunctions that would make it impossible to detect an internal fault when starting an oscilloscope, causing inconvenience in the analysis of subsequent accident phenomena. Solve it all at once.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the principle of phase comparison conveyance relay relay system, Figure 2
The figure is an explanatory diagram of the response of the same system under various conditions, Figure 3 is a conventional internal accident detection circuit, Figures 4 and 5 are examples of the internal accident detection circuit according to the present invention, and Figure 6 is an example of the internal accident detection circuit according to the present invention. FIG. 1... Bus bar, 2... Generator, 3...
・Current transformer, 4...Shiya disconnector, 5...
・Power transmission line, 6... Relay input current, 7...
...Phase ratio shark relay, 8...Square wave shaping circuit,
9... Matching circuit, 10... Integrating circuit,
11... Output circuit, 12... Information transmission device, 13... Transmitter, 14... Receiver, 15... Microwave line, 16...Undervoltage relay output contact, 18-26...Pallet switch contact of the breaker, 19...OR gate, 20...Not gate, 21, 22...Timer, 23, 24... Auxiliary relay. Figure 1 Figure 2 Figure 4 Figure 5 Figure 3 Figure 6

Claims (1)

[Claims] 1. When a power transmission line to be protected has a power source at both ends, and the current detected at each end is of the same polarity when an inflow current occurs in the event of an internal fault, the current at each terminal is rectangular at the same slice level. A phase comparison carrier that shapes the signals into waves, transmits carriers that mean trip permission on positive half waves and trip block on negative half waves, and opens the self-end or disconnection depending on the time when the trip permission signals match. In a protective relay device, each terminal is forced to allow the carrier to trip continuously when the self-terminal or disconnector is opened, and the carrier is allowed to trip continuously from the other end when the self-terminal or disconnector is open. An accident detection device for a phase comparison conveyance protection relay device that detects the occurrence of an accident in the power transmission line on the condition that the power transmission line is not in either a continuous trip block or continuous trip permission state.