JPH0584129B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention connects a load connected to a low-voltage single-phase three-wire distribution line to an adjacent low-voltage single-phase three-wire distribution line that belongs to the same high-voltage distribution system and has different phase connections. In order to be able to switch and connect the live wires, the voltage vector difference between the left and right track conductors facing the different bank matching points is derived from the low-voltage three-phase three-wire power distribution line running parallel to the line. Different-phase live wires of a low-voltage single-phase three-wire distribution line in which the pole-mounted transformer on the side to be switched is disconnected from the system after the left and right systems are temporarily put into parallel operation by canceling out the voltage caused by the current voltage. Regarding the switching method. [Background technology] Figures 6 to 8 separate and organize the current circuit configurations near the points where different banks of electric light and power overhead distribution lines meet, focusing on the differences in the connected phases of the transformers on the poles.
It is illustrated together with a vector diagram of the ground voltage of each line conductor. In these figures, L _A ′, L _B ′,
L _C ′ is the line conductor constituting the high-voltage three-phase three-wire distribution line, V _A ′, V _B ′, and V _C ′ are the phase voltages, V _AB ′,
V _BC ′ and V _CA ′ are the line voltages (usually 6000V)
means. FIG. 5 shows a vector diagram of each of the voltages, and V _A ′→V _B ′→
V _C ′ and V _A ′→V _C ′→V _B ′ respectively indicate the phase rotation order of the high-voltage distribution line voltage. Note that N means a neutral point potential. T ₁ and T ₂ are pole transformers,
The secondary side (low voltage side) voltage is usually 100/200V,
L _A1 , L _B1 and L _B2 , L _C2 are pole transformers T ₁ and
The line conductors connected to T ₂ respectively, and the conductors N described later
Together with this, a single-phase three-wire electric lighting circuit is constructed. Also,
T _A3 , T _B3 , T _C3 are the same high voltage side line conductors L _A ′, L _B ′,
The power pole transformer is connected to L _C ', and two parts (for example, T _C3 and T _A3 in Figure 6a) are connected to V
It constitutes a three-phase wired transformer, and the voltage of its secondary (low voltage side) winding is usually 200V. L _A3 , L _B3 , L _C3 are low voltage line conductors connected to the pole transformers T _A3 , T _B3 , T _C3 respectively, and together with the conductor N, they constitute a low voltage V-connected three-phase three-wire distribution line. , are installed on the same utility pole as the aforementioned single-phase three-wire line conductors L _A1 , L _B1 , and L _B2 , L _C2 . S _A , S _B , and S _C (=1, 2, and 3; the same applies hereafter) are low-voltage switches that disconnect continuity between pole transformers T _A , T _B , and T _C , respectively; W _A ,
W _B and W _C mean single-phase loads connected between the line conductors L _A , L _B , and L _C and the conductor N, respectively.
As shown in Figures 6 to 8a, the conductor N serves as the neutral conductor of the single-phase three-wire distribution line and the middle conductor of the V-connection low-voltage three-phase three-wire distribution line. They are connected semi-permanently at bank butting points and are grounded at various locations, forming an overhead common ground line over a wide area. In addition, the pole transformer T _A ,
The black circle mark near the terminal on one side of each winding of T _B and T _C means that the phase of the voltage at that terminal is in the same phase within the same transformer. Now, the ground voltages of the low voltage side line conductors L _A , L _B , L _C are respectively V _A ,
If expressed as V _B and V _C , and if the line voltages of single-phase three-wire and three-phase three-wire distribution lines are respectively 100V/200V and 200V, then the high-voltage line conductor voltage in Figure 5 a and b is From the vector diagram of and the circuit diagram of Figures 6 to 8a, the voltages V _A , V _B ,
Vector diagrams for V _C Figures 6 to 8 b, c
can be easily guided. As is clear from these figures, when the connection phases of distribution lines in adjacent banks are different, there is a voltage vector difference between the outer line conductors (line conductors excluding the neutral line) facing the matching point, and this Table 1 organizes the data and displays it together with the line voltage of the three-phase three-wire distribution line.

【table】

[Problem that the invention seeks to solve]

However, in the configuration shown in Figure 9, in order to complete the switching work without power outage, it is necessary to
It is necessary to set the timing of the operation of low _{voltage switch S A1 ,} S _B1 of T 1 and switch S _L1 of isolation transformer T _L1 reasonably, and these transformers are usually located several tens to hundreds of meters apart. Due to their location, the interlocking operation of these switches requires fairly complex additional means. Furthermore, since the switch S _L1 is closed after the low voltage switches S _A1 and S _A1 are opened, there are also problems such as a momentary interruption in the power supply to the loads W _A1 and W _B1 . [Means and effects for solving the problems] The present invention has been made in view of the above, and it simplifies the device, eliminates the need for complicated interlocking operations between each switch, and provides The following measures will be taken to eliminate momentary power supply interruptions.
In other words, the winding ratio is 2:1:1 (the winding voltage ratio is 200/
Prepare a 3-winding isolation transformer (100/100V), and
A 200V winding is connected between two appropriately selected line conductors of a parallel V-connected three-phase 200V distribution line, and an electromotive force of 100V is induced in each of the remaining two windings. Next, these windings are connected to the opposing outer wire conductors so that the voltage vector difference between the two outer wire conductors on the left and right facing the different bank abutting points is canceled out by the induced electromotive force in the two windings. Insert and connect them between each. As a result, both the left and right systems are temporarily placed in parallel operation. Next, the low-voltage switch of the pole-mounted transformer to be switched is sequentially opened and closed, and the pole-mounted transformer to be switched is separated from the line conductor. There is no change in the voltage applied to the switched loads before and after the low voltage switch is opened, and after the low voltage switch is opened, the voltage applied to these loads is applied from the switching side pole transformer and the two-winding isolation transformer. Power will continue to be supplied. Hereinafter, the different-phase live line switching system of the low-voltage single-phase three-wire distribution line of the present invention will be described in detail. [Embodiment] Figures 1, 2 and 3 each show an embodiment of the present invention, and the manner of phase connection of the pole transformers in these figures is the same as in Figures 6-8a, respectively. In these figures, the meanings of the constituent elements indicated by the same symbols as in the case of Nos. 6 to 8a are the same as in the case of these figures, and therefore the explanation will be omitted. Hereinafter, the configuration and operation of the embodiment will first be described with reference to FIG. 6a. T _L is a three-winding insulating transformer with a winding ratio of 2:1:1 (winding voltage 200/100/100V) newly added in the present invention, and P ₁ , P ₂ ′, P ₃ , P ₄ ′ , P ₄ and P ₅ respectively indicate both terminals of the 200V, 100V, and 100V windings of the same transformer, and the black circle mark near one terminal of each winding indicates that the voltage at that terminal is the same for each winding. Indicates that it is a phase. Both terminals P ₁ and P ₂ of the 200V winding are
They are connected to the line conductors L _A3 and L _C3 of the V-connected three-phase three-wire 200V distribution line, respectively, and therefore the terminal P ₃ −
A voltage of 100V is induced between P ₄ and P ₅ -P ₆ , respectively. Terminals P ₃ and P ₆ on one side of both 100V windings are connected to line conductors L _A1 and L _B1 on the switched side, respectively, and terminals P ₄ and P ₅ on the other side are connected via switches S ₁ and S _2, respectively. and connected to the line conductors L _C2 and L _B2 on the switching side. V ₁ and V ₂ are AC voltmeters connected in parallel with the switches S ₁ and S ₂ , respectively, and are used to check whether the above-mentioned connection work has been performed correctly. In the above configuration, the connection work between each winding terminal of the isolation transformer T _L and each line conductor is performed with both switches S ₁ and S ₂ open. As mentioned above, the vector diagram of the voltage between opposing line conductors in this case is as shown in Figure 6 b and c, and from this it can be seen that the following relationship exists between the voltages between opposing line conductors. . V _C2-A1 = V _C2 −V _A1 , V _B2-B1 = V _B2 −V _B1 , V _C2-A1 = − (V _B2 − V _B1 ) = 1/2 (V _C3 − V _A3 ) = V _C2 − V _A1 , while the terminals P ₃ − of both 100V windings of the isolation transformer T _L
The voltage induced between P ₄ and P ₅ −P ₆ is, respectively,
If expressed as V _P3-P4 and V _P5-P6 , V _P3-P4 = V _P5-P6 = 1/2V _A3-C3 = - (V _C2 - V _A1 ) = V _B2 - V _B1 Therefore, 100V winding Voltage to earth of line terminals P ₄ and P ₅
V _P4 and V _P5 can be written respectively as follows. V _P4 =V _A1 +V _P4-P3 =V _A1 −V _P3-P4 =V _A1 +(V _C2 −V _A1 )=V _C2 V _P5 =V _B1 +V _P5-P6 =V _B1 +V _B2 −V _B1 =V As per _B2 and above, the ground voltages of terminals P ₄ and P ₅ are equal to those of switching side line conductors L _C2 and L _B2 , respectively. Therefore, if the above connection work is done correctly, the voltage vector difference that initially existed between the opposing line conductors will be canceled by the induced voltage in the 100V winding of the isolation transformer, and the readings on the voltmeters V ₁ and V ₂ will be Both become zero. In other words, if the readings on the voltmeters V ₁ and V ₂ are both zero, it can be determined that the above-mentioned work has been performed correctly. After confirming that the connection work has been performed correctly through the above operations, turn on switches S ₁ and S _{2 one} after another. When both switches are turned on, both the left and right systems are placed in parallel operation. As mentioned above, switches S ₁ and S ₂ are closed after eliminating the voltage vector difference between the left and right line conductors, so there is no danger in this closing operation, and there is no risk of voltage distribution in both the left and right systems before and after closing. There is almost no change in Next, the low voltage switches S _A1 and S _C1 of the switched pole transformer T ₁ are sequentially opened to disconnect the pole transformer T ₁ from the system.
The cost to be paid by the switched party during and after the process.
Regular voltage continues to be applied to W _A1 and W _C1 from each low voltage winding of the switching side pole transformer T ₂ and the V-connected three-phase transformers T _A3 and T _C3 , and there is no fluctuation in the power supply. Does not occur. Thus, the loads on the switched side W _A1 , W _C1
The switching connection work to the pole transformer _T2 side has been completed.
In addition, in the above connection work, for example, if you take out the line conductor L _A1 on the switched side, connect it to the 100V winding of the isolation transformer T _L (in this case, the winding between terminals P ₃ and P ₄ ). Switching side line conductor L _C2 to be connected
In some cases, it may not be possible to immediately identify which conductor the conductor is.
In this case, as is clear from the vector diagrams in Figure 6b and c, the voltage between the conductor L _A1 and the line conductors of the two systems to be switched (excluding the ground conductor N) is measured, and the value is 100V. It is only necessary to select a conductor that satisfies the condition as the other conductor. When the replacement or maintenance/inspection work of the pole-mounted transformer T ₁ on the switched side is completed and the connections are made to switch back the loads W _a1 and W _c1 to the switched side transformer T ₁ , the following sequence is followed. That is, the low voltage switches S _A1 and S _C1 of the switched pole transformer T ₁ are sequentially turned on, and both the left and right systems are temporarily placed in parallel operation. As is clear from the vector diagrams in Fig. 6b and c, the low voltage switch S _A1 ,
Since the voltage between both connection terminals of S _C1 is approximately zero, there is no danger in turning it on. Then a switch bridging between the line conductors on the switched side and the switched side
By sequentially opening _S1 and _S2 , both the left and right systems enter separate and independent operating states, completing the load switching operation. Figures 2 and 3 are examples in which the connected phases of each pole transformer are different from those in Figure 1, but the operation is similar to that in Figure 1, so the explanation will be omitted. . In the embodiments shown in Figures 1 to 3, the phase of the voltage applied to the primary winding (200V winding) of the three-winding isolation transformer T _L is different from that of the pole transformers T ₁ and T ₂ . Different ones (for example, T ₁ is U phase,
If T ₂ is V phase, T _L is required to be W phase). In the embodiments shown in FIGS. 1 to 3, the loads W _A1 ,
_The switching side transformer for loads W _{A1 and} W _B1 is
Power is supplied from T ₂ and an isolation transformer T _L.
Therefore, the isolation transformer T _L is required to have a power capacity that can withstand this, and it is inevitable that the isolation transformer T L will be larger.
FIG. 4 shows an embodiment that improves this point, and the manner of phase connection of each pole transformer is the same as in FIGS. 1 and 6a. In the same figure, COS is a changeover switch newly added in this embodiment.
Over Switch), the fixed piece P ₇ is connected to the line conductor L _C3 ,
The same P ₃ is connected to the line conductor L _A3 and the primary winding terminal P ₈ of the three-winding isolation transformer T _L , and its movable piece P ₉ is connected to the other terminal P ₂ of the same primary winding, respectively. . The rest of the configuration is the same as that in FIG. 1a. In the above configuration, when switching the load, first, with the movable piece _P9 tilted towards the fixed piece _P7 side, the three-winding isolation transformer T _L ,
Incorporate switches S ₁ and S ₂ and voltmeters V ₁ and V ₂ into the circuit,
Place the systems on the left and right sides of the butt point in parallel operation. Then the low voltage switch of the switched pole transformer T ₁
Open S _A1 and S _B1 one after another to disconnect the transformer, and then without delay move the movable piece P ₉ of the switching switch COS to the fixed piece P ₈ side. This creates a three-winding isolation transformer.
The voltage applied to the primary winding of T _L disappears, and
A switching switch is installed between both terminals P ₁ and P ₂ of the same winding.
shorted by the COS and thus the terminals of the 100V winding
The impedance between P ₃ −P ₄ and P ₅ −P ₆ becomes approximately zero. Therefore, power is continuously supplied to the loads W _A1 and W _B1 from the switching transformer T ₂ side. In this case, the three-winding isolation transformer T _L shares the power supply to the loads W _A1 and W _B1 , and the two low voltage switches S _A1 and
Since this is an extremely short period of time between when S _B1 is opened and when the switching opener COS is pushed to the P ₈ side, the capacity of the three-winding isolation transformer T _L is determined based on the short-time rating. This makes it possible to significantly reduce the size compared to the case shown in FIG. 1a. When replacing the pole-mounted transformer T ₁ on the switched side or completing the maintenance inspection, when switching the loads W _A1 and W _B1 back to the same transformer T ₁ side, first move the movable piece P ₉ of the switching switch COS.
Fold the fixed piece toward the _P7 side. This restores the function of the B-winding isolation transformer T _L , and the primary winding (between terminals P ₁ and P ₂ ) receives 200 V from the line conductors L _A3 and L _C3 .
voltage is applied. Next, the low voltage switches S _A1 and S _B1 of T ₁ of the pole transformer to be switched are turned on, and immediately thereafter, the movable piece P ₉ of the switching switch COS is placed in the neutral position. This cuts off the supply voltage to the primary winding of the three-winding isolation transformer T _L , and at the same time
The impedance between P ₃ and P ₄ and between P ₅ and P ₆ becomes an extremely high value, and the systems on the left and right sides of the butt point are virtually separated, and the load switching operation is completed. In this case as well, the three-winding isolation transformer T _L
The time during which power is distributed to the loads W _A1 and W _B1 is extremely short. A similar configuration is also possible in the case where the connected phases of each pole transformer are as shown in FIGS. 7 and 8a, but the explanation will be omitted. [Effects of the Invention] As explained above, according to the different-phase live line switching method of the low-voltage single-phase three-wire distribution line of the present invention, the voltage vector between the two outer line conductors on the left and right sides facing the different bank matching points is The difference is canceled out by two induced starting forces of equal magnitude derived from a low-voltage three-phase three-wire power distribution line running parallel to the line using a three-winding insulation transformer, and After both systems are temporarily operated in parallel, the pole transformer to be switched is disconnected from the system, allowing a simple and economical device to handle load switching and switching back while the line is live. This makes it possible to reduce the momentary interruption of the power supply to the load completely to zero or to an extremely short period of time during the same operation. Furthermore, in another improved embodiment, a switching switch is connected to the primary winding of the three-winding isolation transformer, and when parallel operation of the left and right systems is started,
The pole transformer on the switched side is disconnected from the system without delay, and the switching switch is operated to interrupt the continuity between the primary winding and the line conductor on the switched side, and at the same time
Since both terminals of the next winding are short-circuited to directly connect both the left and right systems, the time during which the three-winding isolation transformer is involved in the parallel operation (i.e., supplying power to the load on the switched side) is significantly shortened. Therefore, the capacity of the transformer was determined based on the short-time rating, making it possible to significantly reduce the size of the transformer.

[Brief explanation of the drawing]

FIGS. 1 to 3 are explanatory diagrams each showing an embodiment of the present invention. FIG. 4 is an explanatory diagram showing an improved embodiment. 5A and 5B are vector diagrams showing the voltage of each line conductor on the high-voltage side, and FIGS. 5A and 5B show the case where the phase voltage is in forward rotation and reverse rotation, respectively. Figure 6a,
b, c, Fig. 7 a, b, c and Fig. 8 a, b,
c is an explanatory diagram showing the configuration of the current single-phase three-wire distribution line near the abutment point of different banks and the voltage state of each conductor; a is the circuit configuration; b and c are the left and right opposite the abutment point A vector diagram showing the voltage of a conductor. FIG. 9 is an explanatory diagram showing the configuration of a different-phase live line switching system for a single-phase three-wire distribution line that has already been proposed by the present inventor. Explanation of symbols, L _A ′, L _B ′, L _C ′...High voltage side line conductor, V _A ′, V _B ′, V _C ′...High voltage side phase voltage, V _AB ′,
V _BC ′, V _CA ′……High voltage side line voltage, L _A ′, L _B ′,
L _C ′ (=1, 2, 3, the same applies hereafter)...Low voltage side line conductor, V _A ′, V _B ′, V _C ′... Ground voltage of the low voltage side line conductor, N... Ground conductor, T ₁ , _T2 ,
T _A3 , T _B3 , T _C3 ...Pole transformer, S _A , V _B ,
V _C ... Low voltage switch, T ₁ ... 3-winding insulating transformer, P ₁ , P ₂ , P ₃ , P ₄ , P ₅ , P ₆ ... Same winding terminal,
S ₁ , S ₂ ... Switch, V ₁ , V ₂ ... AC voltmeter,
COS...Switching switch, P ₇ , P ₈ ...Fixing piece, P ₉
...Same movable piece, T ₄ ... Connection transformer, S _U ... Switch.

Claims (1)

[Claims] 1. Loads connected to a low-voltage single-phase three-wire distribution line with the first voltage as the line voltage belong to the same high-voltage distribution line, have different connected phases, and have the first voltage as the line voltage. In a different-phase live line switching method for a low voltage single phase 3 wire distribution line, in which the load is switched and connected as a live line to an adjacent low voltage single phase 3 wire distribution line, or the load is then switched back to the original distribution line. , A three-winding isolation transformer that belongs to the same high-voltage distribution system and applies one of the line voltages of a low-voltage three-phase three-wire distribution line whose line voltage is the second voltage to both ends of its primary winding. As a result, an electromotive force of the same magnitude as the first voltage is induced in each of the remaining two windings, and when the load is switched, the voltage between the two outer line conductors on each of the left and right sides facing the different bank abutment points is induced in the two windings. These two windings are inserted and connected between the opposing left and right conductors so that the induced electromotive force in the lines cancels them out, and both the left and right systems are temporarily operated in parallel, and then the pole-mounted transformer on the side to be switched is connected. At the time of subsequent load switching connection, after restoring the connection state between the three-winding insulating transformer and each line conductor to that during parallel operation of both left and right systems, A different-phase live line switching method for a low-voltage single-phase three-wire distribution line, which is characterized by sequentially connecting the conduction between the switching side pole transformer and the line conductor, and then disconnecting the line conductors of the left and right systems. 2. The low-voltage unit according to claim 1, wherein the continuity between the pole-mounted transformer to be switched and the line conductor is interrupted by opening and closing a low-voltage switch of the pole-mounted transformer to be switched. Different-phase live line switching method for three-phase distribution lines. 3. The three-winding insulating transformer has a switching switch connected to its primary winding terminal, and when the load switching is connected, the switch connects between the pole-mounted transformer on the switched side and the line conductor. After the continuity is broken, the continuity between the low-voltage three-phase three-wire distribution line and the primary winding of the three-winding insulation transformer is cut without delay, and immediately after that, the continuity between the two terminals of the primary winding is broken. When the load switch is connected, the short circuit between both terminals of the primary winding is released, and immediately after that, the low voltage three-phase 3
A different-phase live switching connection method for a low-voltage single-phase three-wire distribution line, which is characterized by restoring continuity with the wire distribution line.