JPS60220413A - Active/reactive power controller using self-arc extinguishing element - Google Patents

Abstract

PURPOSE:To control the active power and the reactive power of advance/delay phase by connetcting a switch circuit between the neutral point of a 3-phase power supply and an intermediate tap of a reactor serving as a load. CONSTITUTION:The phase voltages 1-3 of a 3-phase power supply are rectified by a full-wave rectifier using thyristors 4-9, and these output voltages are connected to a reactor 10 serving as a load. A switch circuit 11 using a self-arc extinguishing element is connected between the neutral point of the 3-phase power supply and an intermediate tap of the reactor 10. Then the active power and the reactive power of advance/delay phase are controlled by the switching action of the circuit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a three-phase power control device using self-groove arc elements having a smaller number and smaller capacity than conventional ones, and particularly relates to an effective and leading/lag phase reactive power control device.

In a circuit in which a reactor is connected as the load of a three-phase full-wave rectifier circuit using reverse-blocking three-terminal thyristor elements (hereinafter referred to as thyristors), the thyristors are all self-extinguishing semiconductor elements (hereinafter referred to as self-groove arc elements). For example, GTO
etc.), devices that can control leading and lagging phase reactive power without connecting capacitors in parallel have been announced (for example, a reactive power compensator using a current-type PWM converter in 1982). Institute of Electrical Engineers of Japan National Conference 606
).

Since all the thyristors in the converter circuit are replaced with self-groove arc elements, six self-groove arc elements are required in a unit configuration, which is disadvantageous in terms of cost and reliability.

The present invention attempts to control effective, leading and lagging phase reactive power using a small number of self-groove arc elements of small capacity. FIG. 1 shows the configuration of an apparatus according to the present invention. 1.
2.3 is the voltage of each phase of the three-phase power supply (1: A phase, 2: B phase, 3
:C phase), 4.5.6.7.8.9 is thyristor, 10
1 is a reactor having an intermediate tap, and 11 is a switch circuit consisting of a self-groove arc element. FIG. 2 shows an example of the configuration of this switch circuit 11. In the same figure (a), a switch circuit is arranged between the neutral point of the three-phase power supply and the center point of the accelerator, in which 12.13 is a diode, 14.15 is a thyristor, 16 is a self-grooved arc element, 17.18 is a DC voltage source. In the same figure (b), the switch circuit is placed between the neutral point of the three-phase power supply and the center tap of the accelerator.
9.20 is a self-extinguishing element, and 21.22 is a DC voltage source.

Figure 3 shows an example of circuit operation when the device shown in Figure 1 is connected to a second
It shows the conduction timing and voltage/current waveforms of the thyristor and the self-extinguishing element when the switch circuit shown in FIG. 3(a) is used. In this figure, the circuit has a control angle α = -72 degrees (3rd
(see figure), and the generated reactive power is leading reactive power, and CO8φ=0.13. However, φ is the phase angle between the power supply voltage and the fundamental wave of the current. The circuit operation will be explained starting from the time when the thyristor 4 is fired.

At time T], the self-arc extinguishing element 16 extinguishes the arc, and the thyristor 4
When ignition occurs, the current that has been flowing from the middle point of the three-phase power supply through the switch circuit 11 stops flowing, and the current flows from the input phase voltage l through the thyristor 4, reactor 10, and thyristor 8 to B. Current flows to phase voltage 2, and current flows from A phase to B phase. Next, when the thyristor 14 is ignited at time T2 and the self-extinguishing element 16 is made conductive, the DC voltage source 17
, is applied to the thyristor 8 as a reverse bias voltage, the thyristor 8 is turned off, and the current flows between the thyristor 4 and the reactor 1.
0, switch circuit diode 12, self-extinguishing element 1
6, flows through the DC voltage source 17 and the thyristor 14.

When the self-arc-extinguishing element is made conductive for the time Δ, and the self-arc-extinguishing element is extinguished at time T3, the thyristor 7 is fired at the same time, the current flowing through the switch circuit stops flowing.
The current circulates through the thyristor 4, the reactor 10, and the thyristor 7. This circuit operating state (hereinafter referred to as circulation moat) is set only between stations with circulation moat angle γ, and time T4
When the thyristor 14 is ignited and the self-extinguishing element 16 is made conductive, the DC voltage source 17 no longer applies a reverse bias voltage to the thyristor, the thyristor 7 is extinguished, and the current flows between the thyristor 4 and the reactor 10. It flows through the diode 12 of the switch circuit, the self-extinguishing element 16, the DC voltage source 17, and the thyristor 14. When the self-extinguishing element is made conductive for the time Δ, and the self-extinguishing element is extinguished at time T5, the thyristor 9 is fired at the same time, the current that was flowing through the switch circuit stops flowing, and the current flows through the thyristor 4. It passes through the reactor 10 and the thyristor 9 and flows from the A phase to the C phase. Thereafter, similar operations are performed to perform commutation operations at arbitrary times to control the current flowing through the power supply. Also, in order to perform this commutation operation, the DC voltage it! The magnitude of the voltages 17 and 18 may be greater than the phase voltage of the three-phase power supply.

In this way, by changing the control angle α and the circulation mode angle γ, the leading reactive power can be controlled. Note that the current flows through the switch circuit only during the visit of Δt, which is a very short time, so the capacity of the switch circuit may be small.

Similarly to the leading reactive power, the lagging reactive power can be controlled by operating a switch circuit and changing the control angle α and the circulation mode angle γ. In addition, to control the delayed reactive power, only the thyristor 4.5.6.7.8.9 is operated without operating the switch circuit, and the control angle α
and circulation mode Monthly, the power control characteristics when controlling the control angle α and the circulation moat angle γ will be explained. Here, the inductance L of the reactor (the inductance between the midpoint of the reactor and one end) is infinite, the magnetic energy held by the reactor is constant, and the left and right windings of the reactor are magnetically completely The mutual inductance M between the left and right windings of the reactor is M = L, and the operating time of the self-extinguishing element only needs to be the time to complete the commutation of the current, and that time is limited to the power supply. It is assumed that Δ1=0, which is very short compared to one cycle.

The effective and reactive components of the fundamental wave component of the current with respect to the control angle α and the circulation mode angle γ are expressed as Ip (α, γ) and Iq (α,
γ), it can be expressed by the following equation.

Ip(α, γ)=21dO/π(C05(α+π/6)
-CO5(α-γ+π/2)+C05(α+π/2)-
CO5 (α-γ+stt 16)) ・・・・・・・・・
・・・・・・・・・(1) Iq(α, γ)=2 r do/
π(5IN(α-γ+π/2)=SIN(α+π/6)
+5IN(α-γ+5π/6)-5IN(α+π12)
) IILIjI+19 conflict・LI φ・Pot...(2) However, IdO is the average value of the current flowing through the acdle.

Therefore, active power P (α, γ) and reactive power Q (α, γ)
If the effective value of the phase voltage of the power supply is E, then P(
α, γ) = E◆Ip (α, γ) φ dispute number one - 114 - φ
φφ(3)Q(α, γ)−E−1q(α, γ)・・・・
.........It is expressed as (4).

FIG. 4 shows the control characteristics determined from equations (3) and (4).

In other words, the control angle α can be controlled within the range of -180 degrees to 180 degrees, and the circulation mode angle γ can be controlled within the range of 0 degrees to 60 degrees, and by changing α and γ, the effective, leading and lagging reactive power can be controlled. Can be controlled continuously.

The circuit operation when the switch circuit shown in FIG. 2(b) is used in the device shown in FIG. 1 is basically the same as when the switch circuit shown in FIG. 2(a) described above is used. Two arc-shaped elements are used, each connected to two symmetrical taps on the reactor. By dividing the connection between the reactor and the switch circuit into two in this way, it is attempted to suppress the current flowing through the switch circuit, the reactor, and the thyristor during commutation. In other words, Fig. 2 (a
), the current during commutation is twice as much as when it is not flowing through the switch circuit, but as shown in Figure 2 (b
), the current during commutation can be suppressed to less than twice by appropriately setting the tap of the accelerator, which is more suppressed than in the previous case. This can reduce the capacitance of the components, especially the capacitance of the switch circuit,
Additionally, unnecessary jumps in current during commutation can be suppressed.

As explained above, the device according to the present invention can commutate the current flowing through the thyristor at any time by using a switch circuit having one or two self-extinguishing elements, and is capable of commutating the current flowing through the thyristor at any time. It is advantageous in terms of cost and reliability because the phase reactive power can be controlled and the number of self-extinguishing elements used is small and the capacity can be small.

[Brief explanation of the drawing]

Fig. 1 shows a power control device according to the present invention, Fig. 2 shows a configuration example of a switch circuit using self-extinguishing elements, Fig. 3 shows conduction timing and voltage/current waveforms of each element in this device, and Fig. 4 is the power control characteristic in the operation shown in Fig. 3. 1.2.3 Three-phase power supply each phase 4.5.6.7.8.9.14.15 Thyristor 10 Adle with intermediate tap 11 Switch circuit 12.13 Diode 16.19.20 Self-extinguishing element 17.18.21.22 DC voltage source Figure 1

Claims (1)

[Claims] In a configuration in which a reactor is connected as the load of a three-phase full-wave rectifier circuit using a thyristor, and a switch circuit using a self-groove arc element is connected to the intermediate tap of the reactor, the switching operation of this switch circuit allows the effective and A device that attempts to control reactive power in leading and lagging phases.