JPH0437656B2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a ring system protection system.

Figure 1 is a system diagram showing a conventional example of a ring system protection system. In Figure 1, PO is the power supply, RY ₁ , RY ₂
is short circuit, ground fault relay, RY ₃ is short circuit, ground fault relay,
CT is a current transformer, BUS ₁ to BUS ₄ are bus bars, Tr is a transformer, and L ₁ to _{L 4} are consumers. The protection system shown in FIG. 1 uses a configuration in which current transformers CT are cross-connected to include lines and busbars. Current transformer as above
When using a protection system that cross-connects CTs, it is extremely difficult to identify line faults, customer busbar faults, and customer secondary failures due to line length, customer transformer capacity, short-circuit capacity of the power supply, etc. It was. In addition,
Figure 2 shows the trip sequence of the method shown in Figure 1. In Figure 2, P and N are positive and negative power supply lines,
27 is the normally closed contact of the undervoltage relay, 17S is the normally open contact of the short circuit relay, both contacts are connected in series, and the trip coil TC is also connected in series to both contacts, and is connected between the positive and negative power lines P and N. . 64
17S is a normally open contact of the ground fault overvoltage relay, and 17S is a normally open contact of the ground fault relay. Both contacts are connected in series and connected in parallel to the series connected contacts 27 and 17S.

In the protection system shown in Figure 1 above, the current transformers CT are cross-connected, making it difficult to identify various accidents.To solve this problem, it is necessary to make the current transformers CT non-cross-connected. It was devised. FIG. 3 is a system diagram showing the protection system, in which the same parts as in FIG. 1 are denoted by the same symbols. _{In FIG . 3 , the sections Z 1 ,} Z ₂ , _{Z 3 ,} Line protection of Z ₄ and Z ₅ and bus lines BUS _{1 ,} BUS ₂ , BUS 3 , BUS 4 using currents i ₂ and i ₃ , i ₄ and i ₅ , i ₆ and i ₇ , i ₈ and i _{9 respectively} This distinguishes it from the busbar protection that protects the busbar.

The protection system shown in FIG. 3 is implemented by the trip sequence circuit shown in FIGS. 4A and 4B. Fourth
Figure A is a sequence for line protection, and Figure 4B is a sequence for customer bus protection, both of which are constructed in the same way as Figure 2.

To implement the protection method shown in Figure 3 above,
A centralized protection method is used as shown in the figure. The protection system shown in FIG. 5 is for protection by inputting the current transformer CT information of each customer to the central processing unit CPU via the slave station devices SUB ₁ to SUB ₄ of each customer.
The slave station devices SUB ₁ to _{SUB 4} are A/D conversion circuits,
It consists of a sampling circuit, transmission interface, optical-electrical, electrical-optical conversion circuit, power supply circuit, etc. With the protection system shown in Figure 5, it is possible to identify each of the accidents described above, but if the slave station devices SUB ₁ to
There is a drawback that when an abnormality occurs in SUB ₄ or the transmission line, it becomes impossible to protect both the line and bus bar. For example, when an abnormality occurs in slave station device SUB ₁ , the input information of currents i ₂ and i ₃ will no longer be supplied to the central processing unit CPU, so line protection for section Z ₁ using currents i ₁ and i ₂ information Then, it becomes impossible to protect the customer bus of the slave station device SUB ₁ using the current i ₂ and i ₃ information. Further, if the slave station device SUB ₂ becomes abnormal, it becomes impossible to protect the line in the section Z ₂ and the customer bus of the slave station device SUB ₂ . Note that in the above method, the current transformers are non-cross-connected, but
A similar problem will occur if a centralized protection method is adopted for cross-connected devices.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a ring line system protection system in which a slave station device can reliably protect lines and busbars even when a transmission line abnormality occurs.

An embodiment of the present invention will be described below with reference to the drawings. Since the system diagram of the ring line protection system is the same as that shown in FIG. 5, the explanation thereof will be omitted. FIG. 6 is a flowchart showing the operating state of the central processing unit CPU shown in FIG. _5. In _FIG . Based on the presence or absence of both information i ₁ and i ₂ , an output is sent out that protects the line section Z ₁ . This output is the slave station device of consumer _L1
It is input to the judgment unit Xa which determines whether SUB ₁ is abnormal or not. When the determination unit Xa determines that the slave station device SUB ₁ is normal, it sends out the protection output Z ₁ TC of the section Z ₁ to the “NO” side. In addition, slave station device SUB ₁
When it is determined that there is an abnormality, an output is sent to the "YES" side of the determining section Xa, and this output is input to the collective protection output section POT. Collective protection output section
The POT outputs an output ATC that protects the line sections Z ₁ and Z ₂ and the bus BUS ₁ based on the presence or absence of current information i ₁ and i ₄ from the current transformer CT and the output of the judgment section Xa.

Next, the current information i ₂ , i ₃ is input to the determination unit B,
An output that protects bus line BUS ₁ is sent based on the presence or absence of both information i ₂ and i ₃ . This output is input to the judgment section Xb. The determining unit Xb also makes the same determination as the determining unit Xa, and if the slave station device SUB ₁ is normal, it sends the protection output B ₁ TC of the bus BUS ₁ to the “NO” side of the determining unit Xb. Further, the determination unit C outputs an output that protects the section Z ₂ of the line based on the presence or absence of current information i ₃ and i ₄ . This output is given to the judgment section Xc, and as described above, when it is normal, it sends out the protection output Z ₂ TC of the section Z ₂ to the "NO" side. Note that the judgment section Xb,
When the output is sent to the "YES" side of Xc, it is input to the collective protection output unit POT and processed in the same way as described above. In other words, if there is an abnormality in _the slave station device or the transmission route _, the CT information (bus side information _{i 1 of} the power supply PO and The anti-consumer bus side information _i4 ) in the section _Z2 is used to collectively protect the sections interposed in this information source.

In FIG. 6, determination section A' receives current information i ₇ , i ₈ , determination section B' receives current information i ₈ , i ₉ , and determination section C' receives current information i ₉ ,
i ₁₀ , and this judgment result and judgment section
From the positive and abnormal states of slave station device SUB ₄ in Xa' to Xc', protection outputs of sections Z ₄ and Z ₅ and bus line BUS ₄ are sent out. In addition, the presence or absence of current information i ₇ and i ₁₀ and the judgment section
From the outputs of Xa′ to Xc′, sections Z ₄ , Z ₅ and bus line BUS ₄
Get the batch protection output. Although not shown, the current information i ₅ and i ₆ and the section Z ₃ are processed in the same way.

FIG. 7 is a system diagram showing another embodiment of the present invention, in which the same parts as in FIG. 5 are designated by the same reference numerals.
Figure 7 shows two lines that are constantly connected to the customer bus line.
A wide-area current differential relay that receives current information from the other end of the two lines as an input is installed as backup protection. This configuration includes line sections Z _{1 and} Z ₂ that receive current information i ₁ and i ₄ for consumer L 1, and a current differential relay 87 to collectively protect consumer L ₁ .
Provide B. In other words, this embodiment uses the method shown in FIG. 6 to detect an abnormality in the transmission line of the slave station device.
By using i ₁ , i ₄ (or i ₇ , i ₁₀ ) introduced in the POT as is, the main protection differential relay of section Z ₁ by i ₁ , i _{2 and} the main protection differential relay of bus BUS ₁ by i 2 , i ₃ The protection differential relay and i ₃ and i ₄ provide backup protection for the main protection differential relay in section Z ₂ . This makes it possible to perform non-intersecting wide area backup, which was previously impossible.

As described above, according to the present invention, the current information of each customer is input to the central processing unit via the slave station device and processed, and the current information of each customer bus is When calculating the protection interval, it is determined whether there is an abnormality in the slave station device or the transmission route, and when it is normal, a protection signal for each interval and bus is output, and when there is an abnormality, it is output as information on the two intervals between the customer bus. This switch protects the section sandwiched between these two section information at once.
By doing so, it becomes possible to protect the slave station equipment, which was conventionally unprotected in the event of an abnormality in the transmission route, and it becomes possible to implement a non-cross-connected wide-area backup system of current transformers, which has not been possible in the past.
In this case, the distance relay method, overcurrent or overvoltage ground fault relay method widens the protection range, so the detection sensitivity has to be somewhat degraded, but compared to each of the above relay methods, the detection performance of the fault section is better. The ability to make good choices and decisions is enhanced.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing a conventional loop line system protection system, Fig. 2 is a circuit diagram showing the trip sequence of Fig. 1, Fig. 3 is a system diagram showing a non-cross-connected ring line system protection system, 4A and B are circuit diagrams showing the trip sequence of FIG. 3, FIG. 5 is a system diagram of the centralized protection system, FIG. 6 is a flowchart showing an embodiment of the present invention, and FIG. 7 is a circuit diagram showing the trip sequence of FIG. It is a system diagram showing another example of. Z ₁ to Z ₅ ... Line section, i ₁ to i ₁₀ ... Current information, CT ... Current transformer, BUS ₁ to BUS ₄ ... Bus bar,
SUB ₁ to SUB ₄ ...Slave station device, _L1 to _L4 ...Customer, A, B, C, A', B', C'...Judgment unit, Xa,
Xb, Xc, X′a, X′b, X′c...judgment section, POT,
POT'... Collective protection output section.

Claims (1)

[Claims] 1. In a system that inputs the current information of each customer in the ring line system to the central processing unit via a slave station device installed at each customer, and centrally protects the line of each section and the busbar of each customer, In the event of an abnormality in the slave station device, the presence or absence of current information on the other end of the two lines connected to the customer bus is determined, and the customer bus and the two lines connected thereto are collectively protected. Features a ring system protection system.