JPS63129812A - Network protector - 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 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. 5 shows the basic configuration of a high-voltage spot network power reception system. In the figure, consumer A and consumer B are high-voltage power distribution! Power is received from A51 through three lines each. The voltage of the high-voltage distribution line 51 is determined by a primary disconnector 5 for each line.
It is connected to the primary side of a step-down network transformer 53 connected to Δ- through 2, and its secondary side is connected to a network bus 56 via a protector fuse 54 and 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 has a connection between the secondary side of the network transformer 53 and the network bus 56 side from between its poles. The primary side of a differential voltage meter transformer 58 that directly introduces a differential voltage is connected, and a main relay 59 is connected between the secondary sides of this differential voltage meter transformer 58 and the current transformer 57. be done. Further, on the secondary side of the network transformer 53, a reference voltage meter for detecting the secondary side voltage of the network transformer 53 is provided 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. Transformer 6
0 is connected, and its secondary side and the secondary side of the differential voltage meter transformer 58 are connected to a phase check relay 61. Note that loads are connected to the network busbars 56 via tick-off circuit breakers 62, respectively. Here, the network protector 63 is connected to the protector fuse 54.
Protector circuit breaker 55. Main relay 59 and phase check relay 61 as network protector relay. Current transformer57. Differential voltage meter transformer 58. It is constituted by a reference voltage meter transformer 60.

Next, as a specific example of this type of network protector, a voltage on the network bus 56 side is detected instead of the differential voltage instrument transformer 58, and a reference voltage instrument transformer 6
FIG. 6 shows a network protector 63' equipped with a potential transformer 58' for obtaining a voltage difference between the secondary side voltage of the network transformer 53 detected at 0 and introducing the voltage to the network protector relay.

That is, in FIG. 6, the reference voltage instrument transformer 60 and the instrument transformer 58' connected to the network bus 56 side are all connected, and their secondary side phase voltages are connected to the phase check relay 61 and It is configured to be introduced into the main relay 59 so that each relay operates. In other words,
The secondary side phase and neutral point of the reference voltage instrument transformer 60 are connected to a reference voltage coil 72 in the phase check relay 61,
The secondary side of each potential transformer 60°58' is connected to the differential voltage coil 73 in the phase check relay 61, and the secondary side of each phase 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 terminals between the secondary sides of each instrument transformer 60° 58' are connected to the differential voltage coil 76 in the main relay 59, and the two terminals of the current transformer 57 The next side is connected to the current coil 74 in the main relay 59, respectively. With this circuit configuration, the main relay 59
The phase check relay 61 detects the differential voltage and phase angle between the secondary side of the network transformer 53 and the network bus 56 side, and contacts the cutoff contact 64 and the make contact 6 of the main relay 59.
5 and the contacts 66 of the phase check relay 61 are operated to automatically open and close the protector circuit breaker 55.

From FIG. 6, only the secondary side load of the reference voltage instrument transformer 60 is extracted and shown as shown in FIG. 7. As is clear from this figure, the load on the phase check relay 61 (reference voltage coil 72) is connected only between phases un (n is the neutral point), and the load on the main relay 59 (reference voltage coil 75) is Since they are connected between the un, vn, and wn phases, the loads on each phase are unbalanced.

On the other hand, since the network transformer 53 is wire-connected and has no neutral point, the neutral point of the reference voltage instrument transformer 60 becomes a virtual neutral point depending on the magnitude of the load on the secondary side, and each phase The voltage becomes unbalanced. As is well known, the base '1! ! When applying a differential voltage to the protector circuit breaker 55 using a three-phase balanced voltage as the voltage, the secondary voltage Vt of the network transformer 53 and the voltage Vn of the network bus 56 are Vt - Vn from the differential voltage application characteristics of the network protector. ≧Δ■(
Since the protector circuit breaker 55 is automatically closed when there is a difference voltage) and the phase angle of each voltage Vt, Vn is an appropriate value, the unbalanced load on the secondary side causes the reference voltage meter to If the magnitude and phase of each phase voltage on the secondary side of the transformer 60 is inconsistent, the above conditions will not be satisfied.

Therefore, conventionally, as shown in FIGS. 6 and 7, v-n on the secondary side of the reference voltage meter transformer 60.

Correction impedances 67 and 68 were connected between the w and n phases, respectively, and these correction impedances 67 and 68 were adjusted so that each phase voltage was balanced for all three phases.

In addition, considering the characteristic difference in the voltage fluctuation rate of each potential transformer 60.58', the magnitude and phase of the secondary 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 breaker 55 is disconnected, the above-mentioned closing conditions are adjusted. V t −V n≧71■
I needed to make sure that they were satisfied.

(Problem to be solved by the invention) However, according to this, the correction impedance 67~
71 and confirmation of the three-phase balanced voltage are extremely complicated and require a lot of time for adjustment, etc., and a large number of correction impedances 67 to 71 are required, which increases costs and complicates the circuit. I had this problem.

The present invention has been proposed to solve the above problems, and its purpose is to
Even if the load on the next side is unbalanced, the input reference voltage of the network protector relay can be balanced in three phases without using correction impedance.

This eliminates the work of adjusting the correction impedance, reduces costs, and simplifies the circuit configuration. Moreover, the voltage difference is not affected by the characteristic difference between the reference voltage voltage transformer and the voltage transformer on the network bus side. It is an object of the present invention to provide a network protector that can obtain closing characteristics and reverse excitation (reverse power) cutoff characteristics.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides 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. In a network protector, the current transformer is connected to the secondary side of the network transformer, and the midpoint of each phase on the secondary side of the current transformer is connected to the secondary side of the network transformer and is connected to the secondary side of the network transformer. A reference voltage potential transformer outputs as a reference voltage a three-phase balanced voltage with a phase lead of 90" in electrical angle than the line voltage, and a voltage between the poles of the protector circuit breaker is connected to the secondary side of the network transformer and the network. A differential voltage measuring transformer that detects a differential voltage with respect to the bus bar side, and a network protector relay that automatically closes or disconnects a protector circuit breaker by introducing the current output of the current transformer, the reference voltage, and the differential voltage, respectively. It is characterized by having the following.

(Function) In the present invention, the secondary side of the reference voltage instrument transformer is connected by △,
By extracting the voltage with a phase lead of 90° relative to the line voltage from the midpoint of each phase and introducing these as reference voltages to the network protector relay, three Phase balanced voltage is obtained without using correction impedance. Also, based on the voltage between the poles of the network bus (differential voltage), 4! ! Since it is directly detected by a voltage transformer separate from the voltage voltage transformer and introduced into the network protector relay, there is no need for a correction impedance to compensate for the characteristic difference with the reference voltage voltage transformer, allowing for good differential voltage input. characteristics and reverse excitation cutoff characteristics.

(Example) The present invention will be described in detail below 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 Δ-Δ in the same manner as described above, and its primary side is connected to a high-voltage distribution line (not shown). It is connected. The network protector 1 according to the present invention is connected to the secondary side of this network transformer 53. For convenience, network transformer 5
The protector fuse connected to the secondary side of 3 is omitted from illustration.

In the network protector 1, 2 is a current transformer, and current coils 3, 4.5 of a main relay 6, which constitutes a network protector relay, are connected to the secondary side of the current transformer 2, together with a phase check relay 11, which will be described later. Further, each phase on the secondary side of the network transformer 53 is connected to each terminal U, V, W on the primary side of the reference voltage instrument transformer 7 connected by Δ-Δ. Furthermore, the reference voltage instrument transformer 7-2
On the next side, as shown in Fig. 2, midpoints n, n2゜n3 are provided between the terminals v and w, between w and u, and between uv, respectively, and the U terminal and the midpoint n□ are Main relay 6
to the reference voltage coil 8 of the phase check relay 11, the ■terminal and the middle point n2 to the reference voltage coil 9 of the main relay 6, and the W terminal and the middle point n to the reference voltage coil of the main relay 6. 10.

On the other hand, in FIG. 1, a protector circuit breaker 13 is connected between the secondary side of the network transformer 53 and the network bus (not shown), and the protector circuit breaker 13 is connected between the secondary side and the network bus (not shown) between its poles. A differential voltage potential transformer 14 with a human-to-human connection is connected for directly detecting the differential voltage between the two. A differential voltage coil 15 of the phase check relay 11 is connected between the secondary side phases and the neutral point of this instrument transformer 14, and a main relay is connected between each phase of 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.

In such a configuration, the secondary side line voltages *uv, *vv, and Vwu of the reference voltage instrument transformer 7.

The voltage between the U terminal and the midpoint n *u n L The voltage between the HV terminal and the midpoint n2 V Vn2 and the voltage between the W terminal and the midpoint 03 *wn3 are expressed by the voltage vectors in FIG.

Here, ゛・pressure※un , riνnil※un, is the ゛・voltage■νν between each line.

*Wu and ΩUν are 90 degrees in electrical angle.

Suppose that the magnitude of the line voltage ■νV, *wu, Vuv is 1
If it is 10V, the voltage *un1. *Vnz, Vwn
, are all 110X (1'f/2)≠95.3V
becomes. Here, since the magnitude of each line voltage Ωuv, *VW, *wu is always constant regardless of the unbalance of the load on the secondary side, the potential at the midpoint n1ln21n3 is also constant, so the voltages V unl, Vvnz r V n3 becomes a three-phase balanced voltage that is not affected by the unbalanced load on the secondary side. Therefore,
By introducing these voltages into the main relay 6 and phase check relay 11, a three-phase balanced voltage can be obtained as a reference voltage.

On the other hand, since the differential voltage is directly introduced into the main relay 6 and phase check relay 11 from the voltage transformer 14 on the network bus side, the voltage difference between +14 and the reference voltage voltage voltage transformer 7 is applied to the voltage transformer. Even if there is a difference, the differential voltage itself is not affected, and the differential voltage turning on characteristics and reverse excitation (reverse power) cutting characteristics of the network protector 1 are not affected at all.

Next, FIG. 4 shows a second embodiment of the present invention. In this embodiment, the network transformer 53' is connected in a Δ-direction connection, and the reference voltage instrument transformer 7' is connected in a large-Δ connection, and the large connection side of these transformers 53' and 7' Both neutral points are grounded. The rest of the configuration is exactly the same as the first embodiment, and even in this network protector 1', the three-phase balanced voltage is supplied from the secondary side of the reference voltage potential transformer 7' as the reference voltage regardless of the unbalanced load. can be introduced into each relay 6.11.

(Effects of the Invention) As described above, according to the present invention, the three-phase normal S voltage is generated from each phase on the secondary side connected to the reference voltage instrument transformer and used as the reference voltage of the network protector relay. This eliminates the need for a large number of correction impedances as in the prior art, simplifying the circuit configuration and reducing costs, and at the same time eliminates the need for complicated adjustment work to balance three-phase voltages.

Further, 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 not affected by characteristic differences with the reference voltage voltage transformer.

Furthermore, since the secondary side of the reference voltage instrument transformer is Δ-connected, there is an effect that there is no variation in line voltage due to harmonic component voltage from the grid.

[Brief explanation of the drawing]

1 to 3 show a first embodiment of the present invention, in which 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, 4th
The figure is a circuit configuration diagram showing the second embodiment of the present invention, FIG. 5 is a basic configuration diagram of a spot network power receiving system, FIG. 6 is a circuit configuration diagram showing a conventional network protector, and FIG. FIG. 2 is an explanatory diagram of the secondary side load of the reference voltage instrument transformer. 1.1'...Network protector 2...Current transformer 6...Main relay 7.7'...Group'f!
! Voltage meter transformer 11...phase check relay 13
...Protector circuit breaker 14...Differential voltage meter transformer 53, 53'...Network transformer 56...Network bus VW Fig. 2 Fig. 3

Claims (1)

[Scope of Claims] A network protector comprising a protector circuit breaker connected between a network bus and a secondary side of a network transformer whose primary side is connected to a distribution line, comprising: a current transformer connected to the secondary side of said network transformer, and △
a reference voltage instrument transformer that outputs, as a reference voltage, a three-phase balanced voltage whose phase is 90 degrees ahead of the line voltage from the midpoint of each of its own secondary-side phases connected to each other; and the protector circuit breaker. 2 of the network transformer
A differential voltage potential 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 to automatically close the protector circuit breaker. or a network protector relay for blocking.