JPH0559651B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a network protector used in high-voltage spot network power reception systems and the like.

(Prior Art) FIG. 6 shows the basic configuration of a high voltage spot network power receiving system. In the figure, consumer A and consumer B each receive power from the high-voltage distribution line 51 through three lines. The voltage of the high-voltage distribution line 51 is connected to the primary side of a step-down network transformer 53 connected △-△ via a primary disconnector 52 for each line, and the secondary side is connected to the protector fuse 5.
4 and a network bus 56 via a protector circuit breaker 55.

Further, a current transformer 57 is connected between the protector fuse 54 and the protector breaker 55, and the protector breaker 55 is connected from between its poles to the secondary side of the network transformer 53 and the network bus 56 side. The primary side of a differential voltage measuring transformer 58 that directly introduces the differential voltage between the
This differential voltage meter transformer 58 and the current transformer 5
A main relay 59 is connected between the secondary sides of 7. Further, on the secondary side of the network transformer 53, there is provided a standard for detecting the secondary side voltage of the network transformer 53 as an input circuit for obtaining a three-phase balanced voltage for the reference voltage in the differential voltage input characteristic of the network protector. The primary side of voltage meter transformer 60 is connected, and the secondary side thereof and the secondary side of differential voltage meter transformer 58 are connected to phase check relay 61 .
Note that loads are connected to the network busbars 56 via takeoff circuit breakers 62, respectively. Here, the network protector 63 includes a protector fuse 54, a protector circuit breaker 55, a main relay 59 as a network protector relay, a phase check relay 61, a current transformer 57, a differential voltage meter transformer 58, and a reference voltage meter transformer. It is composed of a container 60.

Next, as a specific example of this type of network protector, the voltage on the network bus 56 side is detected instead of the differential voltage instrument transformer 58, and the network protector detected by the reference voltage instrument transformer 60 is FIG. 7 shows a network protector 63' equipped with a potential transformer 58' for obtaining a voltage difference between the voltage on the secondary side of the transformer 53 and introducing the voltage to the network protector relay.

That is, in FIG. 7, the reference voltage voltage transformer 60 and the voltage transformer 58' connected to the network bus 56 are both connected to the negative terminal.
These secondary side phase voltages are introduced into the phase check relay 61 and the main relay 59 so that each relay operates. That is, the secondary side one phase and the neutral point of the reference voltage instrument transformer 60 are connected to the reference voltage coil 72 in the phase check relay 61,
One phase on the secondary side of each potential transformer 60, 58' is connected to the differential voltage coil 73 in the phase check relay 61, and each phase on the secondary side and the neutral point of the reference voltage potential transformer 60 are connected to the main It is connected to the reference voltage coil 75 in the relay 59, and the differential voltage coil 7 in the main relay 59 is connected between each phase on the secondary side of each potential transformer 60, 58'.
6 of the current transformer 57, respectively.
The next side is connected to the current coil 74 in the main relay 59, respectively. With this circuit configuration, the main relay 59 and the phase check relay 61 detect the differential voltage and phase angle between the secondary side of the network transformer 53 and the network bus 56 side, and detect the cutoff contact 64 and the make contact of the main relay 59. 65 and the contact 66 of the phase check relay 61 are operated, and the protector circuit breaker 5
5 is automatically opened and closed.

In this FIG. 7, the reference voltage instrument transformer 60
Figure 8 shows an excerpt of only the secondary side burden. As is clear from this figure, the burden on the phase check relay 61 (reference voltage coil 72)
is connected only between phases u and n (n is the neutral point), and the burden on the main relay 59 (reference voltage coil 7
5) is connected between the un, vn, and wn phases, so that the loads on each phase are unbalanced.

On the other hand, since the network transformer 53 is Δ-connected and has no neutral point, the reference voltage instrument transformer 60
The neutral point becomes a virtual neutral point that depends on the magnitude of the load on the secondary side, and the voltages of each phase become unbalanced. As is well known, when applying a differential voltage to the protector circuit breaker 55 using a three-phase balanced voltage as a reference voltage, the secondary voltage Vt of the network transformer 53 and the network bus line are determined from the differential voltage application characteristics of the network protector. Since the protector circuit breaker 55 is automatically closed when the voltage Vn of 56 is in the relationship of Vt-Vn≧ΔV (differential voltage) and the phase angle of each voltage Vt, Vn is an appropriate value, as described above. If the magnitude and phase of each phase voltage on the secondary side of the reference voltage meter transformer 60 is uneven due to unbalanced load on the secondary side, the above condition will not be satisfied.

Therefore, conventionally, as shown in FIGS. 7 and 8, the v-
Correction impedance 67, 68 between n and wn phases
These correction impedances 67 and 68 were adjusted so that the voltages of each phase were balanced for all three phases.

In addition, considering the characteristic difference in voltage fluctuation rate of each potential transformer 60, 58', the magnitude and phase of the secondary side voltage of each potential transformer 60, 58' are adjusted when the protector circuit breaker 55 is closed. Correcting impedances 69 to 71 are connected between each phase of the secondary side of the potential transformer 58' and the neutral point so that the impedances are equal, and when the protector circuit breaker 55 is disconnected, the above-mentioned closing conditions are adjusted. It was necessary to confirm that Vt−Vn≧ΔV was satisfied.

(Problems to be Solved by the Invention) However, according to this method, the work of adjusting the correction impedances 67 to 71 and checking the three-phase balanced voltage is extremely complicated, and a lot of time is required for adjustment, etc. Since a large number of circuits 71 to 71 are required, there are problems such as an increase in cost and a complicated circuit.

The present invention was proposed in order to solve the above problems, and its purpose is to provide a network without using correction impedance even if the secondary side load of the reference voltage voltage transformer is unbalanced. Balance the input reference voltage of the protector relay in three phases,
This eliminates the work of adjusting the correction impedance, reduces costs, and simplifies the circuit configuration, and is not affected by differences in characteristics between the reference voltage voltage transformer and the network bus side voltage transformer. It is an object of the present invention to provide a network protector capable of obtaining differential voltage application characteristics and reverse excitation (reverse power) interruption characteristics.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a protector connected between a network busbar and the secondary side of a network transformer whose primary side is connected to a distribution line. In a network protector equipped with a circuit breaker, a current transformer connected to the secondary side of the network transformer, and its own secondary side connected to the secondary side of the network transformer and △ connected. Between the poles of the protector circuit breaker and the reference voltage potential transformer that outputs the three-phase balanced voltage, which is 90 degrees ahead of the line voltage from the midpoint of each phase, as the reference voltage via the auxiliary transformer. Voltage network transformer 2
A differential voltage instrument transformer detects the differential voltage between the next side and the network bus side, the current output of the current transformer, the reference voltage and the differential voltage are respectively introduced and the protector circuit breaker is automatically closed or It is characterized by comprising a network protector relay that cuts off the network.

(Function) In the present invention, the secondary side of the reference voltage instrument transformer is
By connecting the wires and extracting the voltage that is 90 degrees ahead of the line voltage from the midpoint of each phase, and introducing these voltages as reference voltages to the network protector relay via the auxiliary transformer, a reference voltage meter can be created. A three-phase balanced voltage that is not affected by the secondary load of the transformer is obtained without using correction impedance. In addition, since the interpole voltage (differential voltage) of the network busbar is directly detected by a voltage transformer separate from the reference voltage voltage transformer and introduced into the network protector relay, A correction impedance for compensating for characteristic differences is also not required, and good differential voltage application characteristics and reverse excitation cut-off characteristics can be obtained.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.
First, FIG. 1 shows a first embodiment of the present invention. In the figure, 53 is a network transformer connected △-△ in the same manner as described above, and its primary side is connected to a high-voltage distribution line (not shown). It is connected to the. The network protector 1 according to the present invention is connected to the secondary side of the network transformer 53. For convenience, the network transformer 53-2
The protector fuse connected to the next side is not shown.

In the network protector 1, 2 is a current transformer, and current coils 3, 4, 5 of a main relay 6, which together with a phase check relay 11 (described later) constitute a network protector relay, are connected to the secondary side of the current transformer. . In addition, 2 of the network transformer 53
Each phase on the next side is connected to each terminal U, V, and W on the primary side of the reference voltage measuring transformer 7 connected by Δ-Δ. Furthermore, the reference voltage instrument transformer 7-2
On the next side, as shown in Figure 2 in detail, the terminal v
-w, w-n, and uv are the midpoints n ₁ ,
n ₂ and n ₃ are provided respectively, and the u terminal and the midpoint n ₁
is connected to the reference voltage coil 8 of the main relay 6 and the reference voltage coil 12 of the phase check relay 11 via the auxiliary transformer 19, and the v terminal and the midpoint _n2 are connected to the reference voltage coil of the main relay 6 via the auxiliary transformer 19. See you at 9 lol
The terminal and midpoint n ₃ are connected to the reference voltage coil 10 of the main relay 6 via an auxiliary transformer.

On the other hand, in FIG.
A protector circuit breaker 13 is connected between the secondary side of the circuit and a network bus (not shown), and a voltage difference between the secondary side and the network bus is directly detected between its poles. A wired differential voltage potential transformer 14 is connected. A differential voltage coil 15 of the phase check relay 11 is connected between one phase and the neutral point on the secondary side of the instrument transformer 14, and a main relay is connected between each phase on the secondary side and the neutral point. Six differential voltage coils 16 to 18 are connected, respectively. Although not shown, the network protector 1 is provided with a closing contact and a closing contact of the main relay 6 that closes or disconnects the protector circuit breaker 13, and a contact of the phase check relay 11.

Therefore, in such a configuration, the secondary side line voltages V・uv, V・vw,
V・wu, the voltage V・un ₁ between the u terminal and the midpoint n ₁ , the voltage V・vn ₂ between the v terminal and the midpoint n ₂ , and the voltage V・wn ₃ between the w terminal and the midpoint n ₃ are It is expressed by the voltage vector in Figure 3. Here, the voltages V・un ₁ , V・vn ₂ , and V・wn ₃ lead the line voltages V・vw, V・wu, and V・uv by 90° in electrical angle, and if the line voltage V・vw,V・wu,V・
If the magnitude of uv is 110V, the voltages V・un ₁ , V・vn ₂ ,
V·wn ₃ , that is, each primary side voltage of the auxiliary transformer 19 is 110×(√3/2)≒95.3V·. Here, the magnitude of each line voltage V・uv, V・vw, V・wu is 2
Since the voltages at the midpoints n ₁ , n ₂ , and n ₃ are also constant regardless of the unbalance of the load on the next side, the voltages V・un ₁ , V・vn ₂ , and V・wn ₃ are This results in a three-phase balanced voltage that is not affected by unbalanced loads on the secondary side. Therefore, by introducing these voltages into the main relay 6 and the phase check relay 11 through each secondary side of the auxiliary transformer 19, a three-phase balanced voltage can be obtained as a reference voltage.

On the other hand, the voltage transformer 14 on the network bus side
Since the differential voltage is introduced directly into the main relay 6 and the phase check relay 11 from the voltage transformer 14
Even if there is a characteristic difference between the voltage difference and the reference voltage instrument transformer 7, the differential voltage itself is not affected, and the differential voltage input characteristics and reverse excitation (reverse power) cut-off characteristics of the network protector 1 are not affected in any way. There is no.

The auxiliary transformer 19 connected to the output side of the reference voltage instrument transformer 7 has a secondary output voltage of, for example, 110 V and contributes to standardization of the rated specifications of the main relay 6 and phase check relay 11. As the auxiliary transformer 19, autotransformers 19a, 19b, and 19c can be used as shown in FIG. is possible.

Next, FIG. 5 shows a second embodiment of the present invention. In this embodiment, the network transformer 53' is Δ-connected, and the reference voltage meter transformer 7'
are connected to -△, and these transformers 5
The connection side neutral points of 3' and 7' are both grounded. The rest of the configuration is exactly the same as the first embodiment, and even in this network protector 1',
A three-phase balanced voltage can be introduced into each relay 6, 11 as a reference voltage from the secondary side of the reference voltage meter transformer 7' via the auxiliary transformer 19, regardless of load unbalance. In this embodiment as well, it is possible to use autotransformers 19a, 19b, and 19c as shown in FIG. 4 as the auxiliary transformer 19.

(Effects of the Invention) As described above, according to the present invention, a three-phase balanced voltage is generated from each phase of the △-connected secondary side of a reference voltage instrument transformer, and is connected to a network protector relay via an auxiliary transformer. Since the reference voltage is set at
At the same time, this has the effect of eliminating the need for complicated adjustment work to balance the three-phase voltages.

Furthermore, since the differential voltage is directly introduced from the voltage transformer on the network bus side, it is possible to obtain differential voltage turning-on characteristics and reverse excitation cut-off characteristics that are unaffected by characteristic differences with the reference voltage voltage transformer.

Furthermore, the auxiliary transformer connected to the output side of the reference voltage instrument transformer allows the network protector relay to be used regardless of its rating.

In addition, since the secondary side of the reference voltage instrument transformer is Δ-connected, there is an advantage that there is no fluctuation in line voltage due to harmonic voltage from the grid.

[Brief explanation of the drawing]

1 to 4 show a first embodiment of the present invention. FIG. 1 is a circuit configuration diagram, FIG. 2 is an explanatory diagram of the main parts in FIG. 1, and FIG. Voltage vector diagram, Figure 4 is a circuit diagram showing another example of the auxiliary transformer, Figure 5 is a circuit diagram showing the second embodiment of the present invention, and Figure 6 is the basic configuration of the spot network power reception system. Figure 7 is a circuit diagram showing a conventional network protector, and Figure 8 is a circuit diagram showing a conventional network protector.
It is an explanatory view of the secondary side load of the reference voltage meter transformer in the figure. 1, 1'...Network protector, 2...Current transformer, 6...Main relay, 7,7'...Reference voltage instrument transformer, 11...Phase check relay, 13...Protector breaker, 14...Differential voltage instrument Transformer, 19... Auxiliary transformer, 53, 53'... Network transformer, 5
6...Network bus line.

Claims (1)

[Scope of Claims] 1. A network protector comprising a protector circuit breaker connected between a network busbar and the secondary side of a network transformer whose primary side is connected to a distribution line, comprising: The voltage between the current transformer connected to the secondary side of the transformer and the midpoint of each phase of the secondary side connected to the secondary side of the network transformer and connected △ is higher than the line voltage, respectively. A reference voltage potential transformer outputs a three-phase balanced voltage with a phase lead of 90 degrees in electrical angle as a reference voltage via an auxiliary transformer, and a voltage between poles of the protector circuit breaker is output on the secondary side of the network transformer. and the network bus side, the current output of the current transformer, the reference voltage, and the voltage difference are respectively introduced to automatically close or close the protector circuit breaker. A network protector comprising: a network protector relay for blocking a network.