JPS62236013A - Thyristor control type voltage phase regulator - Google Patents

Abstract

PURPOSE:To decrease the number of thyristors by improving both the overcurrent tolerance characteristics and the insulation resistance characteristics according to the turn ratio between a series winding and an energizing winding. CONSTITUTION:The short-circuit currents flowing to thyristor groups 7 and 8 are decided by a system current and the turn ratio between a series winding 9 and an energizing winding 10. In contrast, an abnormal voltage applied to those thyristor groups through the shift to the winding 10 from the winding 9 produces a problem. In other words, the value of the voltage shifted to both groups 7 and 8 from the winding 9 is reduced with the conduction current increased when the turn ratio between both windings 9 and 10 is increased. On the contrary, said shift voltage is increased with the conduction current reduced when said turn ratio is decreased. Thus it is possible to improve both the overcurrent tolerance characteristics and the insulation resistance characteristics and minimize the number of thyristors by setting the turn ratio between both windings 9 and 10 at proper level.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a voltage phase regulator used in a power system, and in particular to an indirect switching type circuit configuration using a thyristor. This invention relates to a thyristor-controlled voltage phase regulator that enables high-speed control.

(Prior art) A voltage phase regulator is a device that performs voltage transformation and also changes the voltage phase on the primary and secondary sides to control power flow in the power system. Tap changers with fixed contacts have been used. One known example of such a voltage phase regulator is one constructed from a main transformer 21 and a series transformer 22 as shown in FIG. 21 includes a high voltage main winding 23, an in-phase voltage adjustment tap winding 24, and a medium voltage winding 25.
and a low voltage winding 26, and three single-phase tap changers 27 are connected to the in-phase voltage adjustment tap winding 24. The series transformer 22 is equipped with a tap winding 28 for direct voltage adjustment, an excitation VII winding 29, and a stabilizing winding 30, and the tap winding 28 for right angle voltage adjustment includes a three-phase neutral point tap. A switch 31 is connected.

In this configuration, in-phase voltage adjustment is performed by the single-phase tap changer 27, and quadrature voltage adjustment is performed by the three-phase neutral point tap changer 31, respectively. However, these tap changers27.31
Since it has mechanical contacts, the time required for switching is relatively long, and it is impossible to handle high-speed control or continuous switching, etc., and it is a function that improves excessive stability in the event of an emergency system failure. There isn't.

On the other hand, with the expansion of power systems, highly reliable and efficient equipment is no longer needed, and it is desired to realize a voltage phase regulator that also has the function of improving transient stability1.

By the way, in recent years, with the remarkable progress of semiconductor technology including silicon-controlled rectifying elements (hereinafter referred to as thyristors), the application of thyristors has expanded in various fields, and the use of thyristor technology has also been utilized in the power field. Research has been conducted on voltage phase regulators that operate as tap changers, and their effectiveness has been recognized, and recently, consideration has been given to putting them into practical use.

In a voltage phase regulator using such a thyristor, high-speed control within one cycle and continuous switching are possible, and superior characteristics not available in the past can be obtained.

In other words, it has the ability to control the power flow by rapidly changing the voltage and phase to improve transient stability in the event of a grid failure, and it also has the ability to actively control the power flow in the loop system during normal times. This can play a role in eliminating overloads on power transmission lines and reducing transmission losses.

However, when the tap changers 27 and 31 in FIG. 6 are replaced with thyristor systems in order to realize high-speed switching, the following problems occur.

That is, since thyristors are semiconductors, their overcurrent withstand characteristics and insulation characteristics against abnormal voltages such as lightning impulse voltages are much worse than transformer windings, so these must be taken into consideration in the circuit configuration. Furthermore, since the current flowing through the thyristor is a high-voltage side line current and the generated voltage also tends to increase, there is a problem that the number of thyristors used becomes extremely large and the configuration becomes complicated. Therefore, indirect switching type thyristor control using a series transformer has generally been considered more promising than such direct switching type thyristor control.

Furthermore, in the voltage phase regulator shown in FIG. 6, the original function of the series transformer 22 can be performed only by the configuration consisting of the tap winding 28, the tap changer 31, and the excitation winding 29;
By reducing the zero-sequence impedance or by reducing the
Since a triangular winding is required to circulate harmonic components, the stabilizing winding 30 is provided solely for this role, and as a result, the problem of complicating the configuration of the series transformer 22 is rarely encountered. .

(Problems to be Solved by the Invention) As mentioned above, in conventional voltage phase regulators, when the tap changer is replaced with direct switching type thyristor control, the circuit configuration is poor due to poor insulation properties. becomes difficult,
There were problems in that the number of thyristors used increased and the series transformer required a stable winding, making the configuration complicated.

The present invention was proposed to solve these problems, and its purpose is to perform indirect switching type thyristor control to enable high-speed control and continuous switching, thereby reducing excessive stability in the event of a system fault. This reduces the number of thyristors used, and simplifies the configuration of the series transformer by omitting the stabilizing winding. An object of the present invention is to provide a si-risk controlled voltage phase regulator that can realize the following.

[Structure of the Invention] (Means for Solving the Problems) A thyristor-controlled voltage phase regulator according to the present invention includes a regulating transformer having a shunt winding, a tap winding, and a stabilizing winding;
Consists of a series transformer with a series winding and an excitation winding,
The tap winding is configured with a star connection for quadrature voltage adjustment and an open star connection for in-phase voltage adjustment,
These connections are made through a thyristor group in which two sets of thyristors are connected in antiparallel to each other, so that the vector sum voltage of the quadrature voltage adjustment valve and the in-phase voltage adjustment component is applied to the excitation winding of the series transformer. It is characterized by the following.

(Function) By having the above-described configuration, the present invention enables high-speed control, continuous switching, and non-contact operation, which are characteristics of thyristor control, to simplify maintenance and high-frequency operation. By changing the turn ratio between the wire and the excitation winding, the overcurrent withstand characteristics and insulation characteristics can be improved, and the number of thyristors used can be reduced. Furthermore, there is an advantage that the stabilizing winding of the series transformer can be omitted.

(Example) Next, an example of the thyristor-controlled voltage phase regulator according to the present invention will be specifically described with reference to the drawings.

Structure of this Embodiment FIG. 1 is a wiring diagram showing the structure of this embodiment, in which 1 is a regulating transformer and 2 is a series transformer.

In FIG. 1, a regulating transformer 1 includes a star-connected shunt winding 3, a star-connected right-angle voltage regulating tap winding 4, and an in-phase component connected in a star-shaped manner with an open neutral point. It is composed of a voltage regulating tap winding 5 and a triangularly connected stabilizing winding 6, and both tap windings 4.5 are composed of a quadrature voltage regulating thyristor parking 7 consisting of two sets of thyristors connected in antiparallel to each other. Each is connected to a group of in-phase voltage adjusting thyristors 8.

The series transformer 2 is composed of a series winding 9 and an excitation winding 10, and one end of the series winding 9 is connected to the line side connection point (U, V, W>) of the shunt winding 3. The other end of the series winding is connected to the secondary line (U, V, W>).

One end of the excitation winding 10 (Xz, ')'1, Zt
) is the in-phase voltage regulating thyristor group 8 of the regulating transformer 1.
and the other end of the excitation 1 winding 10 (×2, V
z, Zz) is a quadrature voltage adjusting thyristor group 7 having a phase difference of 120° from the in-phase voltage adjusting thyristor group 8.
They are each connected to one end that is not on the neutral point side and one end of the in-phase voltage adjusting thyristor group 8 having a phase difference of 120 degrees.

FIG. 2 (A>(B) is a diagram showing the connections between the tap coils 11 to 13 and the thyristor group 14 and their effects.
As shown in A), the thyristor group 14 is configured such that two sets of thyristors are connected in reverse to each other, and both are made conductive in one direction by a signal pulse, and one and both are made non-conductive by stopping the signal pulse. has been done. The induced voltage ratio of the tap coils 11 to 13 is set to 1:3:9, and as shown in FIG. 2(B), the terminal k of the thyristor group 14 is controlled by conduction/nonconduction control of each thyristor (1) to (2).

The voltage E generated at the voltage is adjusted to 27 tap points ranging from +13e to 0 to -138, and this configuration is well known.

In the embodiment shown in FIG. 1, the quadrature voltage adjustment tap winding 4 and the thyristor group 7 have three tap coils, and the in-phase voltage adjustment tap winding 5 and the thyristor group 8 have three tap coils. The two are applied respectively.

Effects of this embodiment Next, the effects of this embodiment will be explained. Figure 3 (A>
5(B) to 5(A) and 5(B) are induced voltage vector diagrams for explaining voltage and phase adjustment, and only necessary portions are extracted from FIG. 1 and shown.

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 8 for in-phase voltage adjustment is generated, and that voltage is used for the excitation vi1 winding 1.
0 is excited, and only the in-phase voltage E1 is generated in the series winding 9.

In this case, if the phase-to-phase voltage on U, V, and W sides is El), then U,
The phase-to-phase voltage ES generated on the V and W sides is (Ep+2EtCO
330°)=Ep+/TEt, and the phase difference is U, V,
It becomes zero on the W side and on the U, V, and W sides.

Figure 4 (A) and (B) show the in-phase voltage adjustment thyristor group 8.
The generated voltage is zero, only the voltage generated by the quadrature component voltage adjustment thyristor group 7 is generated, the excitation winding 10 is excited by this voltage, and only the quadrature component is generated in the series winding 9. show. In this case, the voltage Es generated on the U, V, and W sides is determined by the phase difference θha tan −'(/'ff
E2/E p).

FIG. 5 (A>(B)) shows that a voltage is generated in both the thyristor group 7 for quadrature voltage adjustment and the thyristor group 8 for in-phase voltage adjustment, and the combined voltage excites the excitation line 10, and the series winding Line 9 shows a state in which a vector sum Es '' +E2 ''- of the in-phase voltage E1 and the quadrature voltage E2 is generated. In this case, U, V.

The voltage E s generated on the W side, and the phase difference θ is tan ' (E2 / (E l)//
ff+Et)).

In this way, in this embodiment, the in-phase voltage and the quadrature voltage are applied to one series transformer instead of being applied to separate series transformers. By adjusting the magnitude and polarity of the alternating voltage at the terminals of thyristor groups 7 and 8, the series transformer 2
The amplitude of the voltage ES generated on the secondary side by changing the amplitude and phase of the voltage generated in the series winding 9 of
The phase difference θ between the next side (U, V, W> and the secondary side (U, V, W)) can be adjusted as desired.

Next, the current flowing through the thyristor and the applied voltage will be explained. In general, the overcurrent withstand capacity and dielectric withstand capacity of a thyristor are not determined by normal load current or steady operating voltage, but are often determined by short circuits and ground currents in the event of a grid fault, as well as lightning impulse voltage and switching impulse voltage that occur in the grid. This is a well-known fact. Since the switching system of this embodiment is an indirect switching system, the short circuit current flowing through the thyristor groups 7 and 8 is determined by the system current and the turns ratio between the series winding 9 and the excitation winding 10. On the other hand, the abnormal voltage applied to the thyristor group includes both those coming from the shunt winding 3 to the tap winding 4.5 or from the series winding 9 to the excitation winding 10. The latter is the problem. That is, when the turns ratio between the series winding 9 and the excitation winding 10 is increased, the voltage transferred from the series winding 9 to the thyristor group 7.8 becomes smaller, but the current flowing therein becomes larger. Conversely, if the turns ratio is decreased, the transition voltage will increase, but the conducting current will decrease.

From this relationship, by appropriately selecting the turns ratio between the series winding 9 and the excitation winding 10, the overcurrent withstand characteristics and insulation characteristics can be improved, and the number of thyristors used can be minimized. . In addition, the circuit to which the thyristor groups 7 and 8 are connected is not directly connected to the grid, and the insulation level can be freely selected. By protecting 0.8, the transition to a thyristor group can be made smaller, and the number of thyristors connected in series can be further reduced.

Furthermore, the circuit of this embodiment has the advantage that the stabilizing winding of the series transformer 2, which was conventionally necessary, is not required. The reason for this will be explained next.

First, in FIG. 3 when only the in-phase voltage adjustment thyristor group 8 is generating voltage, the first excitation winding 10 and the in-phase voltage adjustment tap winding 5 constitute a single-phase circuit. The zero-sequence current circulates between the excitation vi1 winding 10 and the in-phase voltage adjustment tap winding 5, and the current flowing through the in-phase voltage adjustment tap winding 5 flows through the triangular connection of the adjustment transformer 1. Since the current is canceled by the zero-sequence current circulating through the stable winding 6, the stable winding of the series transformer 2 becomes unnecessary.

Next, in FIG. 4, where only the quadrature voltage adjustment thyristor group 7 is generating voltage, it is equivalent to the excitation winding 10 being triangularly connected, and a zero-sequence current flows through this circuit. The stabilizing winding of the series transformer 2 is not required.

Next, thyristor groups 7 and 8 for right-angle and in-phase voltage adjustment
In FIG. 5, when both are generating voltages, the zero-phase current is, for example, excitation winding (Xl) - in-phase voltage adjustment tap winding (Xl - V2 ) - excitation winding (yz - Vl )−
In-phase voltage adjustment tap winding (Vt -22) - Excitation winding (Z2-Zt) - In-phase voltage adjustment tap winding (
Zl-X2) - Excitation winding (X2) - Excitation winding (Xl)
The current that flows through the circuit and the in-phase voltage adjustment tap winding 4 is canceled by the circulating zero-sequence current of the triangularly connected stable winding 6 of the regulating transformer 1. Lines are no longer needed.

*Another embodiment: In addition to the above-mentioned tap-switching type without firing angle control, the thyristor system includes a firing angle control type that controls firing angle. This firing angle control method uses one tap coil corresponding to the three tap coils 11 to 13 in Fig. 2 to connect the terminals of a thyristor group consisting of four sets such as thyristors ■ to ■. The magnitude and polarity of the voltage E between the two are adjusted by controlling the firing angle of the thyristor. In this method, the thyristor control is complicated compared to the tap switching type, and high frequencies may be generated due to the distorted waveform. It is clear that the same applies.

[Effects of the Invention] As described above, according to the present invention, voltage and phase adjustment can be performed by thyristor control, which enables high-speed control and continuous switching, which improves transient stability in the event of a system fault. , and reliability is improved by simplifying maintenance and enabling high-frequency operation due to the non-contact system, and by reducing the number of thyristors used and omitting the stabilizing winding in the series transformer, which was difficult in the past. It is possible to provide a new type of thyristor-controlled voltage phase regulator that can simplify the configuration.

[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>(8) is a wiring diagram showing the configuration and operation of a well-known tap coil and thyristor group, respectively. and table, Figure 3 (A>(B), Figure 4 (A)
(B), FIGS. 5A and 5B are voltage vector diagrams showing the principle of voltage phase adjustment in the embodiment of FIG. 1, respectively.
In each figure (A> is a shunt winding and a series winding, (B) is an excitation winding and a tap winding, and FIG. 6 is a wiring diagram showing a conventional voltage phase regulator. 1... Adjustment Transformer, 2, 22... Series transformer, 3.
...Shunt winding, 4.28...Tap winding for quadrature voltage adjustment, 5,24...Tap winding for in-phase voltage adjustment, 6
゜30... Stable winding, 7... Thyristor group for quadrature voltage adjustment, 8... Thyristor group for in-phase voltage adjustment, 9
...Series winding, 10.29...Excitation vi1 winding, 11
~13...Tap coil, 14...Thyristor group,
21... Main transformer, 23... High voltage main winding, 25...
- Medium voltage winding, 26...low voltage winding, 27.31...tap changer with functional contacts.

Claims (1)

[Claims] A star-connected shunt winding, a star-connected right-angle voltage adjustment tap winding, an open star-connected in-phase voltage adjustment tap winding, and a triangular connection. A voltage phase regulator comprising a regulating transformer with a stabilizing winding, and a series transformer with a series winding and an excitation winding, wherein one end of the series winding is connected to 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, one end of the in-phase voltage adjustment tap winding is connected to one end of the excitation winding, and the other end of the excitation winding is One end is connected to one end of a quadrature voltage adjustment tap winding of a phase different from the in-phase voltage adjustment tap winding, and further connected to one end of an in-phase voltage adjustment tap winding of a different phase. Thyristor-controlled voltage phase regulator.