JPS62184513A - Voltage phase regulating device of thyrister control type - Google Patents

Abstract

PURPOSE:To attain quick control and continuous switching, to improve reliability and to simplify a constitution by phase regulating a voltage by thyrister control. CONSTITUTION:A regulating transformer 1 is comprised of the bypass coil 3 of a triangle connection, the same phase voltage regulating tap coil 4 and the perpendicular voltage regulating tap coil 5 of a star connection. The tap coils 4 and 5 are connected to the same phase voltage regulating thyrister group 6 and a perpendicular voltage regulating thyrister group 7, both of which connect two sets of thyristers in parallel reversely with each other. A serial transformer 2 is composed of a serial coil 8, an exciting coil 9 and a stable coil 10. In the coil 8, its one end is connected to the triangle junction of the coil 3 of the transformer 1, while both ends are serially connected to the line. The one end of the thyrister group 7 of the transformer 1 is connected to the junction in the middle of the thyrister group 6 which has no voltage of the same phase component as its own phase, and the other end is connected to some part of the coil 9 of the transformer 2. Thus a shorted current conducting to the thyrister groups is compiled to the exciting coil. By varying the turn ratio of the serial coil to the exciting one, the current value can be changed.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a thyristor-controlled voltage phase regulator for power that enables high-speed control, and in particular uses an indirect switching method to improve reliability. This invention relates to a thyristor-controlled voltage phase regulator that has been improved and has a simplified configuration.

[Technical background of the invention and its problems] A voltage phase regulator or regulating transformer is a device that transforms voltage and also controls power flow in a power system by changing the voltage phase on the primary and secondary sides. Conventionally, an on-load tap changer with mechanical contacts has been used to change the taps. However, tap switching systems that involve mechanical operation have long switching times and do not have the ability to improve transient stability in the event of an emergency system failure.

On the other hand, with the expansion of power systems, highly reliable and efficient equipment is required, and it is desired to realize voltage phase adjustment autotransformers that also have the function of improving transient voltage stability. .

Incidentally, in recent years, with the remarkable progress in semiconductor technology including silicon-controlled rectifying elements (hereinafter referred to as thyristors), their application has been expanded in various fields. In line with this situation, voltage phase regulators and regulating transformers that utilize this thyristor technology to perform tap conversion through thyristor control have been researched in the power field, and their effectiveness has come to be recognized. The practical application of high-voltage, large-capacity devices for industrial use is also being considered.

This thyristor control system enables high-speed control within one cycle or continuous switching, and therefore can provide excellent characteristics that were not available with conventional devices. In other words, by rapidly changing voltage and phase, power flow is controlled to improve dynamic stability in the event of a grid failure, and by actively controlling power flow in a constant loop system, transmission line It can play a role in eliminating overloads and reducing power transmission losses.

One conventional example of a voltage phase adjusting autotransformer is shown in FIG. It consists of a main transformer 21 and a series transformer 22. The main transformer 21 has a high voltage main winding 23, an in-phase voltage adjustment tap winding 24, an intermediate voltage winding 25, and a low voltage winding 26. Three tap changers 27 are connected. The series transformer 22 has a tap winding 28 for quadrature voltage adjustment, an excitation winding 29, and a stabilizing winding 30, and the tap winding 28 for quadrature voltage adjustment includes a three-phase neutral point tap changer. 31 is connected.

In such a configuration, the in-phase voltage adjustment is performed by the tap changer 27, and the quadrature voltage adjustment is performed by the tap changer 31, each using a direct switching method, but the tap changers 27 and 31 are mechanically operated. Since it has a contact point, it cannot support the above-mentioned high-speed control, etc.

In order to solve such problems and realize high-speed control of tap switching for the purpose of improving transient stability, etc., the tap changers 27 and 31 may be replaced with thyristor-controlled ones. However, since thyristors are semiconductors, their overcurrent withstand characteristics and insulation characteristics against abnormal voltages such as lightning impulse voltages are very poor compared to transformer windings. It is necessary to have a configuration that has sufficient resistance to overcurrent and overvoltage.

For example, in the example shown in Fig. 6, if the tap changers 27 and 31 are replaced with the thyristor control system, the high-voltage line current flows through the thyristor, and the tap winding is connected to the high-voltage line. The generated voltage also increases, and furthermore, when a short circuit or ground fault occurs, the short circuit current flows directly to the thyristor, so the number of thyristors to be used, which is determined by the abnormal voltage and current, becomes extremely large. There is a problem that the configuration becomes complicated. In addition, malfunctions caused by thyristor malfunctions, such as open-phase problems caused by thyristor OFF, continue to occur in the system, which poses a problem in its operational reliability.

Therefore, in general, when a thyristor system is adopted, an indirect switching system using a series transformer is more advantageous than a direct switching system.

[Objective of the Invention] The object of the present invention is to adopt a thyristor-controlled tap switching method, which is a new technical issue, and which is capable of high-speed switching operations necessary to improve the transient stability of the system, and to achieve high reliability and It is an object of the present invention to provide a thyristor-controlled voltage phase regulator that can simplify the configuration.

[Summary of the Invention] The thyristor-controlled voltage phase regulator according to the present invention has a tap winding of a regulating transformer that has a star connection for quadrature voltage adjustment and a triangular connection for in-phase voltage adjustment. The connection is made through a thyristor group in which two sets of thyristors are connected in antiparallel to each other, and one end of the tap winding for quadrature voltage adjustment is connected to an in-phase component that does not have a voltage of the same-phase component as the own-phase component. Connect to the 2-phase connection point of the voltage adjustment tap winding,
The other end of the quadrature voltage regulating tap winding is connected to the excitation winding of the series transformer, and one end of the series winding of the series transformer is connected to the triangular connection point of the shunt winding of the regulating transformer. This is a characteristic feature.

−〇 − With such a configuration, the short-circuit current flowing through the thyristor group is organized into the excitation winding, and the turns ratio between the series winding and the excitation winding of the series transformer can be changed. Therefore, the current value can be changed as appropriate. Therefore, even when overcurrent or overvoltage is applied, the current value flowing through the thyristor group can be suppressed to a low value, so reliability can be improved and the configuration can be simplified.

[Embodiments of the Invention] An embodiment of the si-risk controlled voltage phase regulator according to the present invention as described above will be specifically described using FIGS. 1 to 5 (A>(B>).

*Configuration In Fig. 1, 1 is a regulating transformer and 2 is a series transformer. The regulating transformer 1 is composed of a triangularly connected shunt winding 3, a triangularly connected in-phase voltage adjusting tap winding 4, and a star-connected right-angle voltage adjusting tap winding 5. . Both tap windings 4 and 5 are respectively connected to an in-phase voltage adjustment thyristor group 6 and a quadrature voltage adjustment thyristor group 7, which are formed by connecting two sets of thyristors in antiparallel to each other.

The series transformer 2 includes a series winding 8, an excitation winding 9, and a stabilizing winding 1.
0. The series winding 8 connects one end to the triangular connection point (U, V, W>
and both of the series winding @(U, V, W>, (u
, v, w) are connected in series to the line.

The quadrature voltage regulating thyristor group 7 of the regulating transformer 1 converts its −@(Xt, Vt, zt) into the in-phase voltage regulating thyristor group 6 which does not have a voltage of its own phase and an in-phase component.
are connected to the two-phase connection points (Xl, '11.Zt), respectively, and the other end (X
2. 'J2. Z2) is connected to one end (x2, y2, Z2) of the excitation winding 9 of the series transformer 2.

Next, FIG. 2 (A>(B)) shows an example of the configuration of a well-known tap winding and thyristor group and its operation.

In FIG. 2(A), tap windings 11 to 13 are connected by a thyristor group 14. In FIG.

The thyristor group 14 has two sets of thyristors connected in antiparallel to each other, and is configured such that both are made conductive in one direction by a gate pulse, and are made non-conductive by stopping the signal pulse. Figure 2 (A>(B)
The example is the turns ratio (induced voltage ratio) of tap windings 11 to 13.
When the ratio is 1:3:9, each thyristor ■～■ is turned on and off.
As is clear from the figure, by FF control, the voltage E generated at the terminal of the thyristor group 14 is increased from +136 to O.
-13e can be adjusted to 27 tap points.

Therefore, there is an advantage that at least the number of tap windings can be increased, and it is well known that such a configuration effect exists in the thyristor control type.

In the embodiment shown in FIG. 1, the quadrature voltage adjustment tap winding 5 and the thyristor group 7 have three tap windings, and the in-phase voltage adjustment tap winding 4 and the thyristor group 6 have three tap windings. Although the case where there are two lines is shown, the combination of these lines is appropriately determined according to the needs at the time.

*Effect The effect of the embodiment is shown in Figure 3 (A
)(B) to FIG. 5(A>(,B). Here, FIG. 3(A>(B) to FIG. 5(A>(B)).
FIG. 1 shows only the necessary parts extracted from FIG. 1, and is a vector diagram of induced voltage to explain adjustment of voltage and phase.

In FIG. 3 (A>(B), the voltage generated by the thyristor group 7 for quadrature voltage adjustment is zero, only the voltage generated by the thyristor group 6 for in-phase voltage adjustment is generated, and that voltage is applied to the excitation winding 9. is excited, and only the in-phase voltage E1 is generated in the series winding 8 of the series transformer 2.In this case, if the phase-to-phase voltage on the u, y, and w sides is Ep, the voltage on the U, V, and W sides is The magnitude of the generated phase-to-phase voltage Es is (El)+2Et cos30
)=ElD+FE1, and the phase difference becomes zero.

In FIGS. 4(A) and 4(B), the voltage generated by the thyristor group 6 for in-phase voltage adjustment is zero, only the voltage generated by the thyristor group 7 for quadrature voltage adjustment is generated, and that voltage is applied to the excitation winding 9. is excited, and only the quadrature voltage E2 is generated in the series winding 8. In this case, the magnitude of the phase-to-phase voltage ES generated on the U, V, and W sides is ix v'7 70,000Y +
E2-r 100cm shoulder] At 7-inch, the phase difference θ is tan-'(
ffE2/Ep).

In FIG. 5 (A>(B), a voltage is generated in both the quadrature voltage adjustment thyristor group 7 and the in-phase voltage adjustment thyristor group 6, and the excitation winding 9 is excited by the combined voltage. The series winding 8 of the series transformer 2 has f'T, which is the vector sum of the in-phase voltage E1 and the quadrature voltage E2.
]+-E2'- is occurring. In this case, U, V, W
The phase difference θ is jan' [E2 /((Ep//'ff>
10Et)].

In this way, in this embodiment, since the composite voltage of the in-phase voltage and the right-angle voltage is applied to one series transformer, the thyristor group 6 , 7 is the magnitude of the voltage E generated between the two terminals.
By adjusting the polarity, the magnitude and phase of the voltages E1 and E2 generated in the series winding 8 of the series transformer 2 are changed, and U,
The magnitude ES of the voltage generated on the V and W sides and the phase difference θ can be adjusted as desired.

Next, the current flowing through the thyristor and the applied voltage will be explained.

The required number of thyristors is often determined by the lightning impulse voltage that enters from the line end or the short-circuit current that occurs when the system is short-circuited, rather than by the normal operating voltage and current applied to the thyristor. As described above, when a thyristor control type is applied in a thyristor control system, the thyristor group is located in the high-voltage winding, so the number of thyristors increases, the configuration becomes complicated, and the reliability decreases.

In contrast, according to the configuration of this embodiment as described above, the number of necessary thyristors can be reduced, and the structure can be simplified and reliability can be improved, as described below.

First, since this embodiment uses an indirect switching method, the short-circuit current that actually flows through the thyristor groups 6 and 7 is the short-circuit current that flows through the series winding 8 of the series transformer 2 and is transformed into the excitation winding 9. be. Therefore, the magnitude of the short circuit current flowing through the thyristor groups 6 and 7 can be changed proportionally by changing the turns ratio between the series winding 8 and the excitation winding 9.

Furthermore, the dielectric strength of a thyristor is often determined not by a steady induced voltage but by an abnormal voltage that occurs when a lightning impulse voltage is applied to a line terminal. In the configuration of this embodiment, when a lightning impulse voltage is applied to the line terminal, the abnormal voltage applied to the thyristor groups 6 and 7 is the amount that transfers from the shunt winding 3 to the tap windings 4 and 5. , there is a transition from the series winding 8 to the excitation winding 9. Among these, the former voltage value is low and does not pose much of a problem, while the following can be said about the latter abnormal voltage. That is, when the turns ratio between the series winding 8 and the excitation winding 9 is increased, the transition voltage from the series winding to the thyrisk groups 6 and 7 becomes smaller, but the current flowing therein becomes larger. Conversely, if the turns ratio is decreased, the transition voltage will increase, but the current flowing will decrease. From this relationship, there is an advantage that the number of thyristors used can be minimized by appropriately selecting the turns ratio between the series winding and the excitation winding.

Furthermore, since the circuit to which the thyristor groups 6 and 7 are connected is not directly connected to the grid, the insulation level can be freely selected. By protecting the thyristor group, the transition voltage to the thyristor group can be further reduced, and from this point of view as well, the number of thyristors connected in series can be reduced.

In addition, even if the tap windings 4 and 5 open due to a thyristor malfunction turning OFF, the windings directly connected to the grid will not become open, so it will not be possible to turn off the thyristor as in the direct switching method. The occurrence of malfunction reduction due to temporary opening of the grid circuit is eliminated.

[Other Embodiments] The thyristor control type includes, in addition to the tap switching type without firing angle control as shown in the above embodiment, a firing angle control type that performs firing angle control. This firing angle control formula is shown in Figure 2 (
The three tap windings 11 to 13 in A) are combined into one tap winding, and the magnitude and polarity of the voltage E between the two are connected to the terminals of the thyristor group consisting of four sets such as thyristors ■ to ■. This is adjusted by controlling the firing angle of the thyristor.

Compared to the tap-switching type, this firing angle control type has more complicated thyristor control and may generate harmonics due to distorted waveforms, but the configuration of the tap winding is simplified and the connection method with the thyrisk group is simpler. There are advantages.

It is clear that the present invention can be applied in exactly the same way to this firing angle control type, and the same effects can be achieved.

[Effects of the Invention] As explained above, according to the present invention, voltage and phase adjustment is performed by thyristor control, which enables high-speed control and continuous switching, which is useful for improving dynamic stability in the event of a system fault. In addition, since the current value flowing through the thyristor group can be adjusted, it is possible to provide a thyristor-controlled voltage phase regulator that has improved reliability and simplified configuration by reducing the number of thyristors.

[Brief explanation of drawings]

FIG. 1 is a wiring diagram showing an embodiment of the thyristor-controlled voltage phase regulator according to the present invention, and FIG. 2 (A>(B) shows the configuration and operation of the well-known tap winding and thyristor group. Connection diagrams, ON/OFF tables, and FIGS. 3 (A), (B) to 5 (A>(B)) are voltage vector diagrams showing the principle of voltage phase adjustment according to the present invention, and each figure (A> 6 is a wiring diagram showing an example of a conventional voltage phase adjustment transformer. 1... Adjustment transformer, 2, 22...Series transformer, 3.
... Shunt winding, 4, 24... Tap winding for in-phase voltage adjustment, 5, 28... Tap winding for right-angle voltage adjustment, 6
... Thyristor group for in-phase voltage adjustment, 7... Thyristor group for right-angle voltage adjustment, 8... Series winding, 9.29
... Excitation winding, 10.30 ... Stability winding, 11-1
3...Tap winding, 14...Thyristor group.

Claims (1)

[Claims] A regulating transformer comprising a triangularly connected shunt winding, a triangularly connected in-phase voltage regulating tap winding, and a star-shaped right-angle voltage regulating tap winding; In a voltage phase regulator composed of a series winding, a star-connected excitation winding, and a series transformer with a stabilizing winding, one end of the series winding is connected to a triangular connection point of the shunt winding. The tap windings are each connected by a thyristor group in which two sets of thyristors are connected in antiparallel to each other, and the star-connected tap windings for quadrature voltage adjustment have triangular connections that do not have voltages of their own phase and in-phase components. 2 of the tap winding for adjusting the in-phase voltage of
A thyristor-controlled voltage phase regulator, characterized in that one end of each of the tap windings is connected to a phase connection point, and the other end of a star-connected quadrature voltage adjustment tap winding is connected to the excitation winding.