JPS607457B2 - Reactive power regulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention combines an AC power source and an AC IJ vector having a switching means consisting of an anti-parallel circuit of a thyristor and a diode or a reverse conduction thyristor, and supplies only delayed reactive power to the grid power source. The present invention relates to a reactive power adjustment device.

In conventional reactive power adjustment devices, the AC reactor was directly connected to the grid power supply using a thyristor switch, so the capacity of the AC reactor was required to be equal to the reactive power supplied to the grid power supply. That is, FIG. 1 is a block diagram of a conventional reactive power adjusting device, and FIG. 2 is a diagram explaining the operation of the conventional device shown in FIG. In FIG. 1, 1 is a system power supply, 2 and 3 are thyristors, and 4 is an AC reactor. In Fig. 2, a shows the voltage waveform of the system power supply 1, and b shows the current waveform flowing through the circuit. can be made variable, and the delayed reactive power absorbed by the circuit can be controlled. This delayed reactive power is generated by thyristor 2.
The maximum value is reached when 3 and 3 are completely ignited, and AC reactor 4
The capacity of is the maximum reactive power. That is, when absorbing 4 MVA delayed power from the system power supply 1, the AC reactor 4 needs to have a capacity of 40 MNA. The present invention aims to absorb large lagging reactive power using a small capacity AC reactor.

FIG. 3 is a diagram showing the connection of two AC power supplies for explaining the principle of the invention, and FIGS. 4 and 5 are diagrams explaining this operation. In FIG. 3, 1 is a system power supply, 5 is a variable AC power supply, and 6 is an AC reactor. In the following drawings, the same reference numerals indicate the same components. By making the voltage phase of the variable AC power source 5 match the voltage phase of the system power source 1 and making the voltage amplitude of the variable AC power source 5 variable, reactive power can be adjusted.

In FIG. 4, a is the voltage V of the system power supply 1 and the voltage V5 of the variable AC power supply 5, b is the voltage applied to the reactor 6, and c
indicates the delayed current 1 flowing through the circuit. This current 1 is the fifth
As shown in the figure, it is determined by dividing the difference voltage between the voltage vector Es of the system current 1 and the voltage vector Ec of the variable AC power source 5 by the AC inductance value.

Now change the voltage oscillation of the variable AC power supply 5 from 100% to 90% of the voltage oscillation of the grid power supply 1, and set the reactance value of the AC reactor so that the % voltage drop of the AC reactor 6 becomes 10%. 40MVA of delayed power can be absorbed by an AC reactor with a small WA capacity. The present invention supplies an AC variable voltage with a simple configuration and reduces the value of an AC reactor. FIG. 6 is a block diagram showing one embodiment of the present invention, and FIG. 7 is a diagram explaining this operation. In Fig. 6, 1 is a system power supply, 6 is an AC reactor, 11 and 12 are variable DC power supplies, 13 and 14 are thyristors, 15 and 16 are diodes, and 17 is a system power supply 1.
Voltage transformers 18 and 19 each transmit an ignition pulse to the thyristor 1 at the voltage zero point of the grid power supply 1.
3 and 14. Reference numeral 10 denotes a variable AC power source which is comprised of components from the variable DC power source 11 to the ignition circuit 19.

In FIG. 7, a is the system power supply voltage V and the voltage V of the variable AC power supply 10, o and b are the voltages applied to the AC reactor 6, c is the current flowing in the system, d is the current flowing to the thyristor 13, and e is the diode. 15, f is the current flowing through the thyristor 14, g is the current flowing through the diode 16, h is the firing pulse of the thyristor 13, and i is the firing pulse of the thyristor 14. Next, its operation will be explained.

The voltage of the variable DC power supplies 11 and 12 is the output voltage V of the variable AC power supply.

is adjusted so that it is equal to or less than the voltage V of the system power supply. Now, if the thyristor 13 is fired, the grid current, which is delayed by 90 degrees compared to the grid power supply V, is 11 → 13 → 6 → 1
→Flows through 11 circuits.

When this system current reaches zero and the direction reverses, thyristor 1
The current flows through a diode 15 connected in antiparallel to 3. That is, it flows through the circuit 1→6→15→11→1. Next, if a firing pulse is given to the thyristor 14 when the system power supply voltage V, reaches zero, the DC power supply 11,1
2 is applied as a reverse bias, the current in the diode 15 becomes zero, and the current is immediately commutated to the thyristor 14. That is, since the grid current lags behind the grid power supply voltage by 900°, by firing the thyristor, the diode that had been conducting current will be reverse biased by the DC power supply voltage, and the forced extinguishing means will be forced to switch. It is possible to do so. Delaying the system current by 90 degrees from the system power supply voltage V, that is, supplying delayed reactive power to the system power supply, is achieved by making the output voltages y and o of the variable AC power supply 10 smaller than the system power supply voltage V. For example, when the output voltage V,o of the variable AC power source is made larger than the system power supply voltage V, the system current advances by 90 degrees with respect to the system wire voltage, supplying advanced reactive power.

In this case, when the grid power supply voltage is zero, thyristor 13 or 14 is conducting, whereas diode 15 or 16 was necessarily conducting in the case of delayed reactive power supply. Therefore, for example, the commutation from the thyristor 13 to the diode 16 is due to the fact that the voltages of the DC power supplies 11 and 12 are in direct relation to the thyristor 13.
It is not possible to reduce the current to zero. In other words, when supplying advanced reactive power V, there is no commutation option without a forced arc extinguishing circuit. The reactive power adjusting device of the present invention supplies only the delayed reactive power to the grid power supply, and enables commutation of the switch means without the forced arc extinguishing means.

Thus, by changing the voltages of the variable DC power supplies 11 and 12, the output voltages V and o of the variable AC power supply 10 can be changed, and the lag current can be controlled.

FIG. 8 shows another embodiment of the invention.

In FIG. 8, 6 is an AC reactor, 20 is a variable DC power supply, and 21, 22, 23 and 24 are reverse conducting thyristors. 21, 24, 22 depending on the gutter characteristics of the grid power supply voltage 1
and 23 are fired alternately, but after the thyristor parts 21 and 24 are energized, the diode parts 2 ZI and 24 are energized, and when 22 and 23 are ignited, 21 and 24 are extinguished. Current is commutated to 22 and 23. By changing the voltage value of the variable DC power supply 20, the reactive power absorbed from the system power supply 1 can be made variable. This Z embodiment also does not require an arc extinguishing circuit, so the circuit configuration is simple and the loss in the conversion portion is small. FIG. 9 is a diagram showing an embodiment in which the present invention is applied to a three-phase circuit, and FIG. 10 explains the operation of FIG. 9. In Figure 9, there are three river system power supplies, 321 is an AC reactor, 32 is a variable DC power supply, 33 is a transformer, 34, 35, 36, 37, 3
8 and 39 are thyristors, and 40 is a capacitor. u
, v, w, x, y and z are thyristors, Du, Dv, D
w, Dx, Dy and Dz are diodes connected anti-parallel to the thyristor. The DC voltage can be made variable by controlling the firing phase of the thyristors 34 to 39, and the capacitor 40 smoothes the DC voltage. In Figure 10, a
is the system power supply phase voltage, and b to g are firing signals of each thyristor, which are generated when each phase voltage is zero.

h, i, and j represent the interphase voltages of the converter, and k represents the phase voltage of the R phase of the converter. When the voltage of the DC power supply 32 is controlled and the converter R-phase voltage is controlled to a value lower than the system power supply R-phase voltage,
The R-phase current becomes a delayed current as shown in 1. In 1, each element that bears the conducting current is Dx-u-Du-x-D
It shows that current is passed through each part in the order of x.

In this case as well, when the other thyristor fires, the current in that arm is passed through the diode, and can be commutated without the need for a forced extinguishing circuit. o indicates a current ld flowing through the DC circuit, and charging and discharging at a frequency six times the system frequency is repeated, and the losses from converters u to z are supplied as a DC component from the DC power supply 32. The capacity of the DC power supply 32 is small, about 1% of the reactive power capacity from the system power supply. Each of the embodiments shown in FIGS. 6, 8, and 9 described above is equipped with a variable DC power supply, and this power supply supplies the loss of the converter to change the value of the DC voltage and control the reactive power. Met.

By the way, if we pay attention to the fact that the converter is connected to the grid, it may be possible to supply the loss of the converter from the grid and omit the variable DC power supply. That is, the switching point of the converter is delayed from the point in time when the system power supply voltage becomes zero, and the capacitor provided in the DC circuit is charged, so that the loss of the converter is supplied from the system power supply. FIG. 11 is a block diagram showing other embodiments of the present invention, FIG. 12 and FIG.
FIG. 3 is a diagram for explaining the operation of the invention shown in FIG. 11.

In Figure 11, 30 is a system power supply, 31 is an AC reactor,
41 is a capacitor, u', v', w', x', y' and z' are reverse conducting thyristors, Gu', Gv', Gw', G
x', Gy' and Gz' are ignition circuits from u' to z', 42 is a control transformer that detects the voltage phase of the grid power supply,
43 is a current transformer, 44 is a voltage transformer, 45 is the current transformer 4
3 and a reactive power detector that calculates the reactive power from the system power supply 30 based on the signals from the voltage transformer 44; 46 is a reference circuit that determines the reactive power to be supplied; 47 is a circuit that matches the detection signal and the reference signal; 48 is an arithmetic circuit, and the output signal ec of this arithmetic circuit 48 becomes the input signal of the ignition circuits Gu to Gz'. In Fig. 12, a is the system power supply phase voltage, b
is a diagram showing the operation of the ignition circuit Gu', in which the system power supply voltage detected by the control transformer 42 and the in-phase sinusoidal voltage Vu and ec are compared, and at the time t when both match, the u-arm ignition signal is activated. It is generated as shown in c. If the point in time when the R-phase voltage of the grid power supply becomes zero is to, and the phase angle from to to t is 8, the R-phase voltage of the converter is 8 phases lower than the R-phase voltage of the grid power supply, as shown in d. I'm late. FIG. 13 is a vector diagram illustrating the operation when this phase angle is changed. In FIG. 13a, when the converter is operated with a phase difference of 8 degrees between the system power supply voltage Es and the converter voltage Eco, a current of lo flows from the system. This current lo is an effective current that is in the same phase as the system power supply and compensates for the loss of the converter. As shown in FIG. 13b, when the phase difference 8· is reduced from 8o,
Since the effective current flowing from the system power supply decreases, the voltage charged in the capacitor 41 decreases, and the converter voltage Ec decreases.

Due to this decrease, a current 1, flows in from the system power supply, but this current includes components of an effective current 1,R and a delayed reactive current 1,L. The delayed reactive current can be increased by reducing the phase difference, and the control circuits 45, 46, 47
, 48 and the ignition circuits Gu' to Gz' to adjust the phase difference, the reactive power can be made variable. Incidentally, FIG. 14 shows a device in which a fixed amount of capacitors are combined with the above-described reactive power adjusting device of the present invention, and as a result, it is possible to equivalently control the phase-advanced surprise effective power.

In FIG. 14, 50 is an AC reactor, 51 is a conversion device for deriving AC voltage, 52 is a variable DC power supply,
53 indicates a capacitor.

As explained above using the embodiments, according to the present invention, reactive power can be adjusted using a small-capacity AC reactor, and the configuration of the AC power supply for this purpose is extremely simple and does not require a forced arc extinguishing circuit. It can be configured as follows.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a subordinate reactive power adjustment device, Fig. 2 is a diagram explaining the operation of the conventional device, and Fig. 3 shows the connection of two AC power supplies to explain the principle of the present invention. 4 and 5 are diagrams explaining the operation of FIG. 3, FIG. 6 is a configuration diagram showing an embodiment of the present invention, and FIG. 7 is a diagram explaining the operation of FIG. 8 and 9 are diagrams showing other embodiments of the present invention; FIG. 10 is a diagram explaining the operation of FIG. 9; FIG. 11 is a block diagram showing another embodiment of the invention; Figures 12 and 13 are diagrams explaining the operation of Figure 11, and Figure 14 is a diagram showing another embodiment of the present invention for adjusting the lead current. , 3 is Siris Yu' 4
is an AC reactor, 5 is a variable AC power supply, 6 is an AC reactor, 10' is a variable AC power supply, 11 and 12 are variable DC power supplies, 13 and 14 are thyristors, 15 and 16 are diodes, 20 is a variable DC power supply, 21 to 24 are reverse conducting thyristors, 30 is a system power supply, 31 is an AC reactor, 32 is a variable DC power supply, u, v, w, x, y and z are thyristors, D
↓Dv, Dw, Dx, Dy and Dz are diodes, 41
is a capacitor, 42 is a control transformer, u', v', w,
x, y' and 〆 are reverse conducting sirens, Gu', Gv',
GW? Gx', Gy' and Gz' indicate ignition circuits. Figure 1 Figure 3 Figure 2 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 11 Figure 10 Figure 12 Figure 13 Figure 14

Claims (1)

[Scope of Claims] 1. Switching means consisting of an anti-parallel circuit of a thyristor and a diode or a reverse conducting thyristor, and a DC power supply connected to the input side of the switching means, so as to output an AC quantity of electricity from the output side. the output side of the AC power supply is connected to a grid power supply via an AC reactor, and the voltage of the DC power supply is adjusted so that the output voltage value of the AC power supply is equal to or lower than the voltage value of the grid power supply, A reactive power adjustment device characterized by supplying only delayed reactive power to the above system power supply. 2.Equipped with a switching means consisting of an anti-parallel circuit of a thyristor and a diode or a reverse conduction thyristor, and an AC power source having a capacitor connected to the input side of the switching means and outputting an alternating current amount of electricity from the output side, The output side of the AC power supply is connected to a grid power supply via an AC reactor, and a phase adjustment means is used to delay the phase of the output voltage of the AC power supply from the phase of the voltage of the grid power supply, and to adjust the phase difference between the two voltages. The reactive power is characterized in that the charging voltage of the capacitor is controlled and the output voltage value of the AC power source is lower than the voltage value of the system power supply, and only delayed reactive power is supplied to the system power supply. Adjustment device.