SU393794A1 - STATIC SOURCE OF REACTIVE POWER - Google Patents

Description

The invention relates to the field of automatic control of power systems, in particular, to the regulation of the generated (consumed) reactive power of static valve compensators installed in the corresponding load nodes. In the known sources of reactive power (IRM), using as a regulating link directly a frequency converter (IF) with artificial switching, and as a tip element - a three-phase reactor of increased frequency, the phases of which are cyclically connected to the phases of the mains supply, generated (consumed) reactive power is changed by automatically adjusting the frequency of the current in the reactor. Analytically, the reactor power is determined by the following expression:.

where vp. axes are the voltage at the output of an ICh (fundamental harmonic);

/R. OSP is the frequency of the main harmonic of the current in the reactor; LP - reactor inductance.

Since usually Vp. the axes and LP are the nosing quantities, then the adjusting characteristic (Usually, from the IRM it is required to provide the adjustment range DO 25 + 30, which so far

It is impossible if we take acceptable values (r.mya- 100-200gch).

The purpose of the invention is to expand the range of regulation of the IRM. This is achieved by the fact that it is equipped with an additional reactor,

connected in series with the main sensor of the IRM Q (f (fp. axis.) represents a hyperbolic relationship: The value / p. max (or QMHH) on this characteristic is limited by the frequency properties of the currently existing gates, and the value / p m i, ( or Smake) is determined, on the one hand, by the magnitude of the maximum reactive load at a given network point, on the other hand, by the desire to reduce the dimensions of the reactor. The higher the value / p. of the image, the better the weight and dimensions of the reactor, and therefore the total IRM. leads to a decrease in re range DO test for reactive power of the IRM, so far as the max-m max - UMZKS JJn reaches the maximum frequency of the current fp max in the main reactor. Fig. 1 shows a block diagram of a static source of reactive power; Fig. 2 and 3 are control characteristics IRM with an extended control range (Dz) equal to 9 and 16, respectively. A static reactive power source consists of a direct frequency converter with artificial switching and cyclic connection of the phases of a high-frequency reactor to the phases of the network, the main 2 and an additional 5 n controllable reactors, control system of the IRM 4 and switch 5. The principle of the device operation is as follows. When the mains voltage deviates from the nominal using control system 4, the frequency of the current in the main reactor 2 connected at the output of the frequency converter 1 changes. The additional reactor is bridged by the switch 5. Suppose that the voltage deviation in the network to which the sensor responds control system voltage 4 decreased. Therefore, it is also necessary to reduce the amount of generated (consumed) reactive power, which is accomplished by automatically increasing the frequency of the current in the main reactor (Fig. 2). At the time of reaching the maximum frequency / p. max, determined by the technical characteristics of the IWW, opens switch 5, and the frequency of the current in both reactors abruptly decreases to fp. min In order that the value of reactive power at the moment of switching does not change, it is necessary in proportion to the reduction of frequency to increase the load resistance at the output of the IWS, which is done by an appropriate choice of inductance B dop of the additional reactor. A further decrease in reactive power is produced by increasing the frequency of the current in both reactors from fp. min to fp. max when the switch is open 5. The analysis shows that the resulting DS adjustment range will be equal to the square of the adjustment range of the IWM with one reactor, i.e. Ds Dg. (4) (For example, the control characteristics of the IWM are shown in Figs. 2 and 3. an extended control range equal to DE 9 and 16 respectively), the inductance of the additional reactor B dop is selected from the following condition: + additional max. and its installed power is defined as (6) with respect to the same for the main reactor, expression: Dl For example, and a change in DO from 2 to 6, which corresponds to 2 4-36, the installed capacity of the additional reactor is 25-13.9% of Soon, i.e. a relatively small value. Subject of the Invention A static source of reactive power containing a direct frequency converter with artificial switching and an output reactor, the phases of which cyclically switch from one phase of the supply network to another, characterized in that, in order to expand the range of regulation, it is equipped with an additional reactor connected in series with the main m, and a switch shunting the additional reactor, wherein the switch is opened at the time of reaching the maximum current frequency in the main reactor.

  fcemu.

DOS

one%

Si - 3 -3 2 fp Ning

Rig 2

R. fp ..

 1g. i

WO

6040: ff.

fp. Max.

 R

 fp min

2 J FIG. J