JPS6244818A - Single winding transformer for adjusting voltage/phase - Google Patents

Abstract

PURPOSE:To improve the dynamic stability and to increase the reliability of a device by constituting tap windings of the combinations of specific connections and connecting the combinations by anti-parallel bodies consisting of two pairs of thyristors. CONSTITUTION:A voltage/phase adjusting single winding transformer is constituted of a single winding main transformer 1 and a serial transformer 2, the single winding main transformer 1 consists of a serial winding 3, a shunt winding 5 and a low voltage winding 6 and the serial transformer 2 consists of an exciting winding 9, a stable winding 10 and a serial winding 13. In this case, an adjusting transformer 12 is added and thyristor groups are used in stead of tap switches. The serial winding 13 is connected to a node between the serial winding 3 and the shunt winding 5 and the adjusting transformer 12 is constituted of an adjusting winding 14 connected in parallel with the low voltage winding 6, voltage adjusting tap windings 15, 16 for a quadrature component and an in-phase component and their thyristor groups 17, 18 and connected as shown in a wiring diagram. Consequently, voltage and phase adjustment can be attained by thyristor control and rapid control and continuous switching can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a voltage phase adjustment autotransformer for electric power that enables high-speed control.

[Technical background of the invention and its problems]

A voltage phase adjustment autotransformer is a device that not only transforms the voltage but also controls the power system by changing the voltage phase on the primary and secondary sides.The taps are changed using mechanical contact taps. A switch has been used.

However, in the tap changer method that involves mechanical operation,
The time required for switching is long, and there is no function to improve transient stability in the event of an emergency system failure.

On the other hand, with the expansion of power systems, efficient equipment with high reliability is required, and it has become desirable to realize voltage phase adjustment autotransformers that also have the function of improving transient stability. .

In recent years, silicon-controlled rectifying elements (hereinafter referred to as thyristors) have been developed.
The application of thyristors is expanding in various fields due to the remarkable progress of semiconductor technology including thyristor technology, and research has been conducted into voltage phase adjustment transformers and regulators that perform tap switching by thyristor control using thyristor technology. Its effectiveness has been recognized. Recently, the practical application of high-voltage, large-capacity devices for power use has been studied.

Such a thyristor type is capable of high-speed control within one cycle and continuous switching, providing characteristics not found in conventional devices. In other words, it has the function of controlling the stain force flow by rapidly changing the voltage and phase to improve dynamic stability in the event of a system failure, and also actively controls the loop system power flow at all times. This can play a role in eliminating overloads on power transmission lines and reducing transmission losses.

One of the conventional examples of voltage phase adjustment autotransformers is shown in Figure 7.6! 1. It consists of an auto main transformer 1 and a series transformer 2. Auto main transformer 1 has series winding 'ftt
M a , in-phase voltage adjustment tap winding 4, shunt winding 5
and a low voltage winding 6, and three single-phase tap changers 7 are attached to the tap winding 4. The series transformer 2 includes a quadrature voltage adjustment tap winding 8, an excitation winding 9, and a stabilizing winding 10, and the tap winding 8 has three single-phase tap changers 11 attached thereto.

In such a configuration, the in-phase voltage adjustment is performed by the tap changer 7, and the right-angle voltage adjustment is performed by the tap changer 11, each using a direct switching method, but the tap changers 7 and 11 have mechanical contacts. Therefore, it cannot be said that it is compatible with the above-mentioned high-speed control.

On the other hand, since thyristors are made of semiconductor, their overcurrent withstand characteristics and insulation characteristics against abnormal voltages such as lightning impulse voltages are much worse than transformer windings. Therefore, it is necessary to design a structure that takes sufficient precautions against transient overcurrents and overvoltages in the event of a system failure or thyristor malfunction.

Therefore, in the means of replacing the tap changer 7.11 in Fig. 7 with a thyristor system, the current flowing through the thyristor is the medium voltage side line current, and since the tap winding is connected to the medium voltage line end, the generated voltage is also Due to the large size, the number of times the thyristor is used becomes very large, and malfunctions when the thyristor malfunctions, for example, open phase problems due to the thyristor being turned off, occur in the system, which poses a problem in its operational reliability. Therefore, in general, an indirect switching method using a series transformer is often more advantageous than such a direct switching method.

[Purpose of the invention]

In view of the above points, the present invention provides a highly reliable voltage phase adjustment unit that enables high-speed control and continuous switching, improves dynamic stability in the event of a system fault, simplifies maintenance, and enables high-frequency operation. The purpose is to obtain a winding transformer.

[Summary of the invention]

The voltage phase adjusting autotransformer according to the present invention has tap windings consisting of a triangular connection for quadrature voltage adjustment and a star connection for in-phase voltage adjustment, and these connections are made in two sets. This is achieved through a group of thyristors connected in anti-parallel to each other, so that the vector sum voltage of the quadrature voltage adjustment component and the in-phase voltage adjustment component is applied to the excitation winding of one series transformer. That's what I mean.

[Embodiments of the invention]

The present invention will be described below with reference to embodiments shown in FIGS. 1 to 6. In Figure 1, the same parts as in Figure 7 are designated with the same reference numerals as 7.
J), large differences in its configuration
and changed the tap changer to a thyristor.

The automain transformer l has a star-connected series winding 3, a shunt winding 5, and a triangular-connected low-voltage winding 6 wound around a main transformer core (not shown).

The series transformer 2 has another series winding 13 connected to the connection point between the series winding 3 and the shunt winding 5, and its neutral point n.
The excitation winding 9 and the stabilizing winding 10 are connected in a star shape and are grounded.
is wound around a series transformer core (not shown).

In the regulating transformer 12, a regulating winding 14 connected in parallel with the low voltage winding 6, a quadrature voltage regulating tap winding 15, and an in-phase voltage regulating tap winding 16 are connected to a regulating transformer iron core (not shown). Both tap windings 15 and 16 are connected by a right-angle voltage adjusting thyristor group 17 and an in-phase voltage adjusting thyristor group 18, each of which has two sets of thyristors connected in antiparallel to each other. . The thyristor group 17 for quadrature voltage adjustment is triangularly connected, and the thyristor group 18 for in-phase voltage adjustment is connected to the phase connection point (xI
+ V+ + ) t), and the other end is connected to the line terminal (Xz r Yt + 1) 2) of the excitation winding 9.
Connect to each.

FIG. 2 shows the connections between the tap coils 19, 20, 21 and the thyristor group 22. Thyristor group 2
2 is configured so that two sets of thyristors are connected in antiparallel to each other, and both Q and Q are made conductive in one direction by a signal pulse, and both are made non-conductive by stopping the signal. be. Set the induced voltage ratio of the tap coils 19 and 20°21 to 113:9, and turn on each thyristor (1) to [phase] as shown in the following table.

By OFF control, the voltage E generated at the terminal of the thyristor group 22 is adjusted to 27 tap points from +13e to 0 to -13e.

(Left below) If the two tap coils 19 and 20 are thyristors ■ to ■, the voltage E generated at the terminal and l should be +4e to 0 to -4.
The number of tap points for e can be adjusted to 9 points.

This structural effect is well known, and it has the advantage that even if the number of tap coils is small, the number of taps can be increased.

In Figure 1, two tap coils are used for the tap winding 15 and thyristor group 17 for quadrature voltage adjustment, and three tap coils are used for the tap winding 16 and thyristor group 18 for in-phase voltage adjustment. The case where it is applied is shown.

Next, the effects of the present invention will be explained. FIGS. 3 to 5 are vector diagrams of induced voltage to explain that the voltage and phase can be adjusted, and only the necessary portions are extracted from FIG.

First, in FIG. 3, when the voltage generated by the in-phase voltage adjustment thyristor group 18 is zero, only the voltage generated by the quadrature voltage adjustment thyristor group 17 is generated, and this voltage excites the excitation winding 9 to connect the series transformer. A state in which only the quadrature voltage E1 is generated in the winding 13 is shown.

In this case, the voltage Es generated on the intermediate voltage side has a magnitude of m and a phase difference θ of tan-'E'/Em. However, h
is the voltage of the shunt winding.

Next, in FIG. 4, the voltage generated by the thyristor group 170 for quadrature voltage adjustment is zero, and only the voltage generated by the thyristor group 18 for in-phase voltage adjustment is generated, which excites the excitation winding 9 and transforms the series transformer. A state in which only the in-phase voltage Ey is generated in the series winding 13 is shown.

In this case, the voltage E8 generated on the intermediate voltage side has a magnitude of (Ev+Em) and a phase difference θ of zero.

FIG. 5 shows that a voltage is generated in both the quadrature voltage adjustment thyristor group 17 and the in-phase voltage adjustment thyristor group 18, the combined voltage excites the excitation winding 9, and the series transformer series winding 13 This shows a state in which a voltage Et-5, which is a vector sum of the in-phase voltage N1 voltage Dv and the quadrature voltage component, is generated.

In this case, the voltage Es generated on the medium voltage side has a magnitude of
(Ern+Ev)"+Ei" and the phase difference θ is tan-
'El/(Em+Ev).

In this way, instead of applying the in-phase voltage and the quadrature voltage to separate series transformers, there is a method in which they are applied to one series transformer, and the thyristor is turned on.

Terminal k of thyristor group 17, 18 by OFF control.

By adjusting the magnitude and polarity of the voltage E between 1 and 1 and changing the magnitude and phase of the voltage Et generated in the series winding 13 of the series transformer, the magnitude and phase difference θ of the voltage E8 generated on the intermediate voltage side can be adjusted. 0 can be arbitrarily adjusted. Next, the current flowing through the thyristor and the applied voltage will be explained.

The overcurrent capability of a thyristor is often determined by the short-circuit current that occurs when a system short-circuits, rather than by the steady load current or overload current. The short circuit current on the medium voltage line side is the excitation winding 9.
It is transformed into and flows to the thyristor groups 17 and 18. The magnitude of the short-circuit current flowing through the silisk is proportional to the turns ratio between the series winding 13 and the excitation winding 9.

On the other hand, the dielectric strength of a thyristor is often determined not by the steady induced voltage but by the voltage that shifts when a signal impulse voltage is applied to the line terminal. The portion transferred from the transformer series winding 13 to the excitation winding 9 and the portion transferred from the adjustment winding 14 to the tap winding 15
．． 16, but the former is the excitation winding 9
By reducing the number of turns of the circuit, its value can be reduced, and since the latter is a low-voltage circuit, its voltage value is low, and the number of thyristors used in series can be reduced.

Increasing the number of turns of the excitation winding 9 and the tap windings 15, 16 increases the transition voltage or decreases the conducting current; conversely, decreasing the number of turns decreases the transition voltage and increases the conducting current. Based on this relationship, when determining the number of turns, there is a great advantage that the thyristor to be used can be optimally selected.

Furthermore, even if a short circuit occurs in the tap coil due to a malfunction of the thyristor, it is relatively easy to increase the winding impedance of the regulating transformer 12 compared to the direct switching method, so the cross current can be reduced. , when the number of parallel thyristors is determined by the cross current, the number of thyristors used is reduced by that amount.

If the applied current and applied voltage are reduced in this way, the total number of thyristors used can be reduced, and the device can be made smaller and lower in price.

Even if the excitation winding 9 is opened due to the thyristor's gland operation being turned off, the series winding 13 is always connected, so the thyristor's O
The problem of temporary opening of the system circuit due to the FF will no longer occur.

By the way, the application of a thyristor-controlled voltage phase-adjusting autotransformer as shown in Figure 1 is essential for interconnection of large power systems, and since its voltage is high and the unit capacity is very large, it is difficult to get to the installation location. This is due to the transportation method being an issue. It is well known that when transportation by freight car or trailer is required, single-phase units are often manufactured to overcome transportation restrictions. If we look at the configuration of FIG. 1 from this perspective, we can see the following.

The automain transformer 1 has a series winding 3, a shunt winding 5, and a low voltage winding 6.
Since there is no complicated tap winding or tap switching device, it can be applied to a larger capacity by configuring three single-phase generators.

Since the sled, lever row transformer 2 and leg adjustment transformer 12 are separated, transportation is easy, and the number of connections between each transformer, including the single-winding main transformer 1, is reduced to the minimum number of three. There is an advantage to using books.

In addition, when inspecting the thyristor or in the unlikely event that it breaks down, it is also possible to operate with only the single-winding modified EF: 1.

If the capacity is relatively small or the installation location allows for sea transportation, tap winding 15.16 as shown in Figure 6.
It is also possible to wind the coil around the single-turn main transformer core and omit the adjustment winding 14, that is, the adjustment transformer 12.

For the configuration of the tap coil and thyristor group as shown in Figure 2, the induced voltage ratio of the tap coil is l:2:
The thyristor system is also well known and can be applied to such a coil configuration.In addition to the tap-switching type without firing angle control as described above, the thyristor system also includes a tap switching type without firing angle control. There is a firing angle control type that controls the firing angle.

The firing angle control formula is the three tap coils 19 in Figure 2.
, 20.21, and the thyristor is connected to the terminals of a thyristor group consisting of four sets such as It is something to be adjusted.

This method requires complicated thyristor control compared to the tap switching type, and harmonics may be generated due to distorted waveforms, but it has the advantage of simplifying the configuration of the tap winding and simplifying the connection method with the thyristor group. It is clear that the present invention can be applied to this case in exactly the same way.

〔Effect of the invention〕

As described above, according to the present invention, it has the function of a conventional voltage phase adjustment autotransformer, and voltage and phase adjustment can be performed by thyristor control, so high-speed control and continuous switching are possible, and in the event of a system fault. This helps improve dynamic stability, and the non-contact design simplifies maintenance and enables high-frequency operation, improving reliability.

Furthermore, it is possible to provide a new type of thyristor-controlled voltage phase-adjustable autotransformer that can reduce the number of thyristors used and is convenient to transport.

[Brief explanation of the drawing]

FIG. 1 is a wiring diagram showing an embodiment of the thyristor-controlled voltage phase adjusting autotransformer according to the present invention, FIG. 2 is a wiring diagram showing the configuration of a well-known tap coil and thyristor group, and FIG.
4 and 5 are voltage vector diagrams showing the principle of voltage phase adjustment according to the present invention, FIG. 6 is a wiring diagram showing another embodiment according to the present invention, and FIG. 7 is a conventional voltage phase adjustment method. You can see the wiring diagram of the transformer. 1...Automatic main transformer 2...Series transformer 12...Adjusting transformer 3...Main transformer series winding 5...Shunt winding 6...Low voltage winding 4. 16...Tap winding for in-phase voltage adjustment 8.15.
... Tap winding for quadrature voltage adjustment 7.11 ... Tap changer 9 with mechanical contacts ... Excitation winding 10 ... Stability winding 13 ... Series transformer series winding 14 ... ...Adjustment windings 17, 18...Thyristor group for right-angle and in-phase voltage adjustment 19.20.21...Tap coil 22...Thyristor group Agent Patent attorney Noriyuki Chika Agent Patent attorney 3 Written by Hiroshi Mata Figure 1 Figure 2

Claims (2)

[Claims] (1) In a voltage phase adjustment autotransformer consisting of a main autotransformer, a series transformer, and a regulating transformer, the main autotransformer has a series winding, a shunt winding, and a triangular connection. The series transformer is equipped with a low voltage winding, and the other series winding is connected to the connection point of the series winding and the shunt winding of the automain transformer, and the excitation winding and stabilizing winding are connected in a star configuration. The regulating transformer is equipped with a tap winding consisting of a triangularly connected regulating winding connected in parallel with the low-voltage winding of the automain transformer, a triangularly connected wire, and a star-shaped wire. The winding has one end connected to the connection point of the two phases of the triangularly connected tap winding which does not have a voltage of an in-phase component with its own phase, and the other end connected to the excitation winding. A voltage phase adjustment autotransformer characterized in that a star-connected tap winding is connected to a thyristor group in which two sets of thyristors are connected in antiparallel to each other. (2) In a voltage phase regulator consisting of an auto-wound main transformer and a series transformer, the auto-wound main transformer has a star-connected series winding and a shunt winding, a triangular connection, a triangular connection, and a star-shaped The series transformer is equipped with a tapped winding consisting of a wire connection, another series winding connected to the connection point of the series winding and the shunt winding of the automain transformer, and an excitation winding of star connection and a stabilizing winding. The voltage phase adjusting autotransformer according to claim 1, characterized in that the voltage phase adjusting autotransformer is configured to include a winding.