JPS6096137A - Harmonic filter of reactive power compensator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention relates to a static non-active power compensator that controls reactive power by adjusting the current flowing in a reactor by controlling the phase of a thyristor connected in series with the reactor. This relates to harmonic filters.

[Prior art and its problems]

Generally, a static passive power compensator using a thyristor converter is used to control the reactive power of an ultra-high voltage power system to maintain stability and stability of the voltage of the power system.

As this type of static non-dynamic power compensator, one having a circuit configuration shown in FIG. 1, for example, is known. That is, in FIG. 1, reference numeral 10 is a power system, 12 is a transformer, which is used to drop an appropriate voltage from the power system 10 to the static passive power compensator, and 14 is a thyristor switch. The ignition is controlled every cycle by a control angle α delayed from the time when the AC voltage passes the zero point, 16 is connected in series to the thyristor switch 14 or an actuator, and 18 is a harmonic filter. It is. An equivalent circuit for controlling the ignition of the current flowing through the reactor 16 by the thyristor switch 14 every cycle using the static type non-dynamic power compensator configured as described above is as shown in FIG. In this case, the control angle α (α
=90, α=120. The current waveform when the thyristor switch 14 is controlled to fire at α=150) is shown in FIG. 3 (u, (21, (5)).

As is clear from FIG. 6 (1) to β), the current waveform i when the thyristor switch 14 is controlled to fire at a predetermined control angle α is an intermittent waveform, and its fundamental wave component is controlled. By adjusting the angle α, the °C can be changed. Moreover, this fundamental wave reactive power becomes variable delayed reactive power, just like when a variable reactor is connected.

As described above, the current waveform i when the thyristor switch 14 is controlled to fire at the predetermined control angle α is an intermittent waveform and includes harmonic current. Therefore, when this harmonic current flows into the power system, it causes voltage distortion in the power system, causing a 9-induction disturbance that heats equipment.

From this point of view, in the conventional static type non-active power compensator, as shown in FIG.
4. [Phase control rL7' (A harmonic filter 18 is provided to absorb harmonics generated from the reactor 16 and suppress harmonics flowing into the power system. In this case,
It is also possible to provide a plurality of harmonic filters 18 having different harmonic orders. However, the harmonic filter 18 is constituted by a series circuit of a reactor L and a capacitor C, and has the lowest impedance at its resonant frequency, but is capacitive at the fundamental frequency. In addition, the harmonic filter 18 is designed taking into consideration errors in component equipment and fluctuations in the frequency of the power system, and the larger the fundamental wave phase advancing capacity, the higher the filtering effect against errors and fluctuations. The wave filter 18 must have a certain finite appropriate phase advance capacity, and moreover, it must have a large phase advance capacity as the amount of high-harmonics generated increases.

On the other hand, the reactive power adjustment range in a static non-active power compensator is uniquely determined from the stability of the power system and voltage maintenance characteristics. Therefore, the control range of the static passive power compensator must be selected so as to satisfy the adjustment range. For example, in the circuit shown in FIG. 1, the reactive power adjustment range is Q. (advance) to QL (lag) shall be soft-wooded. In this case, the slow phase capacitance of the thyristor switch 14 and the reactor 16 (thyristor control reactor) controlled by the thyristor switch 14 needs to be at least a value that can be omitted in the following equation (1).

QR = 1 QL ... Let the phase fundamental wave capacity be .

In this case, QF<Q. If so, harmonic filter 1
The octal phase response amount is increased to make QF=Qo, or a phase advance capacitor is provided separately from the harmonic filter 18 to obtain a desired phase advance capacitance. With this configuration, a desired adjustment range can be obtained without increasing the capacity of the thyristor-controlled reactor 16. However, if QF−>Qo, that is, if a harmonic filter 18 with a phase advance capacity exceeding the desired phase advance capacity is required, in order to satisfy the reactive power adjustment range of the static passive power compensator. , the capacity of the thyristor-controlled reactor increases as shown in the following equation (2).

Cheer = QI! , +QL > Cheers +QL ... scolding) In this way, when the capacity of the thyristor control reactor 16 increases, the amount of harmonics generated increases in proportion to this capacity, and the harmonic filter 18 also inevitably increases its capacity. It has to be bigger.

As described above, if the capacity of the harmonic filter 18 is increased, the capacity of the thyristor control reactor 16 must be increased, and therefore the installed capacity of the device becomes large.

Therefore, for example, the capacitance QF of the harmonic filter 18 can be calculated using the following equation B.
) and substituting equation (S) into equation (2), we get
The capacity of the thyristor-controlled reactor, Torr 16, is expressed by the following formula (4):
It will be shown as follows.

QF = kf QR......β) Furthermore, the thyristor control reactor 16 is expensive as well as the thyristor switch 14, and the fc high WIJ wave filter 18 is also designed with higher harmonic tolerance than ordinary glue handles and capacitors. This makes it more expensive. For this reason, the conventional static type passive power compensator has the disadvantage that manufacturing costs increase significantly as the equipment capacity increases.

[Purpose of the invention]

An object of the present invention is to improve a harmonic filter provided to suppress harmonic current generated from a thyristor-controlled reactor from flowing into the power system, without increasing the capacity of the thyristor-controlled reactor. To provide an economical reactive power adjustment range that can set a desired reactive power adjustment range at low cost.

[Key points of the invention]

The harmonic filter of the reactive power compensator according to the present invention includes means for connecting a reactor and a thyristor switch in series and adjusting the firing angle of the thyristor switch to adjust the delayed phase reactive power of an AC power system; A reactive power compensator comprising a harmonic filter that absorbs harmonics generated by phase control of the method, characterized in that a reactor is connected in parallel with the harmonic filter.

That is, in the present invention, a reactor is connected in parallel with a conventional harmonic filter provided to suppress harmonic current generated from a thyristor control reactor from flowing into the power system, and a phase-advanced It is possible to provide a harmonic filter for a reactive power compensator that can secure a desired reactive power adjustment range at low cost without increasing the capacity of a thyristor-controlled reactor by canceling out an appropriate amount of external energy. can.

Further, the harmonic filter of the present invention preferably has a configuration in which a reactor and a capacitor are connected in series, and a reactor is further connected in parallel with the capacitor.

[Embodiments of the invention]

Next, embodiments of the harmonic filter of the reactive power compensator according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 4 is a circuit diagram showing an embodiment of a harmonic filter according to the present invention. For convenience of explanation, the same reference numerals are given to the same components as those of the circuit of the conventional static type non-active power compensator shown in FIG. 1, and detailed explanation thereof will be omitted.

That is, in the embodiment shown in FIG. 4, the harmonic filter has a reactor 20 connected in parallel to the harmonic filter circuit 18 shown in FIG. be. The other configuration is the same as the circuit configuration of the conventional static type static power compensator shown in FIG.

Therefore, the difference in the composite impedance zf between the harmonic filter circuit 18 and the parallel reactor 20 in the harmonic filter of the embodiment shown in FIG. 4 is expressed by the following equation, where n is the harmonic order.

... (5) However, xt: Impedance of reactor L xc: Impedance of capacitor C It is shown by the formula.

Further, the reactive power when the power source voltage is set to 1.0 P, U is expressed by the following equation.

Therefore, the impedance X of the parallel reactor 20 that makes the advanced fundamental wave reactive power the adjustment range Qc of the reactive power compensator
, is the above formula (where QF is Q.

If we put

As shown in the above formula (8), if the impedance xpf of the parallel reactor 20 is selected, the desired result can be achieved by adding the inexpensive parallel reactor 20 without increasing the capacity of the silice control reactor 16 or the harmonic filter circuit 18. The adjustment range of the reactive power compensator can be secured.

FIG. 5 shows the frequency characteristics of the composite impedance Zf representing the effect of the harmonic filter of the embodiment shown in FIG. Therefore, in the characteristic curve shown in FIG. 5, the solid line indicates the case where the parallel reactor 20 is connected, and the broken line indicates the case where the parallel reactor 20 is not connected. In this case, as is clear from FIG. 5, the resonant frequency f. Although there is no difference between the two in impedance characteristics in the vicinity, it is understood that the filter effect is higher when the parallel reactor 20 is connected.

FIG. 6 is a circuit diagram showing another embodiment of the harmonic filter according to the present invention. In the circuit of this embodiment as well, the same components as those of the conventional static static power compensator shown in FIG. 1 are designated by the same reference numerals, and detailed explanation thereof will be omitted. That is, in the embodiment shown in FIG.

The harmonic filter is constructed by connecting a reactor 20 in parallel with the capacitor C to a harmonic filter circuit 18 shown in FIG. 1 in which a reactor L and a capacitor C are connected in series. The other configuration is the same as the circuit configuration of the conventional static type static power compensator shown in FIG.

Therefore, if the composite impedance Zfk in the harmonic filter of the embodiment shown in FIG. 6 is calculated, it is expressed by the following equation, where n is the harmonic order.

elI...(9) However, Xt: Impedance of reactor L xo: Impedance of capacitor C x,: Impedance of parallel reactor 20 According to the above equation (9), resonance frequency f. varies depending on the impedance Xp of the parallel reactor 20, which means that the parallel reactor 20 should also be considered when selecting filter constants.

Furthermore, in the above equation (91), impedance Zf (11) at the fundamental frequency is expressed by the following equation.

Furthermore, increase the power supply voltage to 1. The reactive power when oP and U are expressed by the following equation.

Therefore, from the above equation (11), the impedance Xp of the parallel reactor 20 can be set so that the advanced fundamental wave reactive power falls within the adjustment range Qc of the reactive power compensator.

According to this embodiment, only the fundamental current Qc of the adjustment range of the reactive power compensator and the harmonic current flow through the series reactor L that determines the resonance frequency of the harmonic filter, so that the combined impedance Z.

is smaller than the characteristic value shown in FIG. 5, which has the advantage of lower equipment cost.

〔Effect of the invention〕

As is clear from the embodiments described above, according to the present invention,
If the phase lead outside of the reactive power adjustment range of the reactive power compensator is smaller than the phase lead capacity of the appropriately selected harmonic trough amount, the Alternatively, by connecting a reactor in parallel with the capacitor, the composite phase-advanced reactive power can be set to a desired value, and the desired reactive power adjustment range of the reactive power compensator can be achieved without increasing the capacity of the thyristor control reactor. Since it is possible to secure the cost, it is possible to manufacture the reactive power compensator at low cost, and it is possible to economically improve its performance and reliability.

Although the preferred embodiments of the present invention have been described above, it is of course possible to make various design changes without departing from the spirit of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the basic configuration of a conventional static static power compensator, and FIG. 2 is an equivalent circuit diagram of the circuit shown in FIG. 1 in the operating state of the thyristor switch and control reactor.
3 (1) to (5) are operational waveform diagrams of the thyristor switch at different control angles α in the circuit shown in FIG. 2, and FIG. 4 is a reactive power diagram showing an embodiment of the harmonic filter according to the present invention. A circuit diagram of the compensator, FIG. 5 is a characteristic curve diagram showing a comparison of the frequency characteristics of the composite impedance of the harmonic filter shown in FIG. 4 and a conventional harmonic filter, and FIG. FIG. 3 is a circuit diagram of a reactive power compensator showing another example of a wave filter. 10... Power system 12... Transformer 14...
Thyristor switch 16...Reactor 18...Harmonic filter 2
0... Parallel reactor Fl (3, 5

Claims (1)

[Claims] (1) A means for adjusting the delayed phase reactive power of an AC power system by connecting a reactor and a thyristor switch in series and adjusting the firing angle of the thyristor switch, and for absorbing harmonics generated by the phase control of the thyristor. A harmonic filter for a reactive power compensator comprising a harmonic filter, characterized in that a reactor is connected in parallel with the harmonic filter. (21) In the harmonic filter of the reactive power compensator according to claim 1, the harmonic filter is configured with a series circuit of a reactor and a capacitor, and a reactor is connected in parallel with the capacitor. Compensator harmonic filter.