SU66346A1 - Device for stabilizing the voltage of a synchronous generator - Google Patents

Description

It is known that a synchronous generator with permanent magnets has a substantial / advantage over a conventional synchronous generator, in the absence of a driver, contact rings, etc.

However, a generator with permanent magnets has a sharply falling external characteristic. At the same time, due to the absence of a field winding in the generator, conventional voltage regulators cannot be applied here.

To stabilize the voltage of the permanent magnet generator oHHXpoHBOIRO (it was proposed to switch on a transformer with a saturated magnetic circuit, i

The use of one saturated transformer connected to the generator in parallel reduces the range of voltage fluctuations due to a sharp increase in magnetizing current with decreasing load and voltage increase and, conversely, decreasing magnetizing current with increasing load and voltage reduction at the generator terminals.

However, in this case, a decrease in voltage fluctuation, or rather, voltage stabilization within the required limits, is achieved by the fact that the generator must be designed for a large ballast reactive current and, therefore, designed for significantly more power than 1 useful load power. With a FULL load, the current in the winding of the core will flow. the magnitude of which will be determined by the magnitude of the load current plus the magnitude of the magnetisation current of the transformer, which the transformer with a saturated core will be sufficiently large. Wherein. the greater the accuracy required for stabilization, the greater the magnitude of the magnetizing current.

It was further proposed for the same purpose to include in series with the generator capacity; however, such a capacitance is turned on (it can stabilize the voltage at the load terminals provided that l: ,, la, r / CAd is the full longitudinal reactance of the generator, and Xe is the reactance of the capacitor.

Stabilizer circuits were also proposed, in which both elements appear in combination: a series-connected capacitor and a parallel-connected saturated transformer. However, such a scheme does not provide stabilization; The npHMeHeHiHe capacitors connected in series in the circuit, there are elements with a saturated iron magnetic circuit, in particular, a transformer with a saturated core, leads to great complications: a) in the form of a multiple increase in magnetizing current, distortion of the magnetization current curve and distortion of the voltage curve in the secondary winding of the transformer, which leads to an overvoltage in the secondary circuit of the transformer, b) to the appearance of voltage resonance. Both these phenomena do not lead to stabilization, but to disruption of the system, i.e. to emergency mode.

Finally, a stabilizer circuit was proposed, in which a parallel to the generator terminals an parallel transformer (with an unsaturated core), to which capacitors are connected to the secondary circuit. This circuit also cannot guarantee voltage stabilization. Here, the transformer only serves in order to increase the voltage on the capacitors (for reducing their capacitance) and is not involved in the stabilization process; The replacement circuit of this stabilizer will consist only of capacitors connected to the generator. Such a circuit cannot provide stabilization, since with a decrease in the voltage, the current in the capacitors decreases, while it is necessary that this value increase. If, however, a contactor is used to adjust the voltage of the transformer, then all the advantages of contactless adjustment are lost.

The present invention is based on the use, in voltage stabilization gaps of a permanent magnet synchronous generator, of a stabilizer consisting, in equivalent circuit, of inductors connected in parallel with a saturated core and capacitance 1I connected on the terminals of the generator being stabilized. The capacitance and inductance are selected so that the nominal voltage of the machine when idling in the stabilizer circuit has a current resonance and, consequently, the inductance current is fully compounded by the capacitive current of the capacitors. Prts p-eZHY1M e load on the terminals of the generator. Under the influence of internal reactance, the voltage will tend to decrease. But with a slight decrease in voltage at the terminals of the generator, the current in the inductor, under the influence of a decrease in saturation, will start to decrease sharply and the current of the capacitors will remain almost unchanged. As a result, the total current of the stabilizer, being purely capacitive, will begin to increase significantly, thereby compensating for the reactive voltage drop of the generator and stabilizing the voltage on the clamp ah.

This basic principle, according to the invention, is carried out in an improved form of performance: to reduce the capacitance of the stabilizer capacitors, the latter are connected through a transformer and instead of independent inductance with a saturated core, the same boost transformer is used. which is made with saturated core.

For the case when the voltage of the generator idling differs somewhat from the specified nominal voltage, the transformer primary winding may have additional turns and taps, like an autotransformer, so that the required voltage could be applied to the load terminals.

The foregoing is illustrated in FIG. 1 of which is shown. And the electrical circuit of the device proposed in FIG. 2 - the same circuit for a three-phase generator. In the drawing it is indicated: G-generator of alternating current - with excitation from constant 1 magnetovitov, T - transformer with saturated

a power supply circuit, K-capacitors, D - chokes. I - load the clamps.

The equivalent circuit (or replacement circuit) of the T-D-K system. The system consists of a circuit consisting of parallel capacitance and inductance, having a saturated magnetic conductor and connected to the generator G in parallel. The above remark about the resonance of the currents, the onset of a permanent magnet generator, referred to the replacement circuit. In fact, in the diagrams of FIG. 1 and 2, the resonance of the currents occurs in the primary winding of the transformer T, and the magnetizing current of the transformer and the current of the capacitors leading to the primary winding enter into resonance. Under the condition of such a resonance, a transformer when the generator is idling. It consumes only a small active current corresponding to the losses of the transformer and capacitors.

At. To the load of the Generator, three insignificant voltage drops (2-4%), the transformer starts to consume the leading (capacitive) current the more, than 1 more than the voltage drop. It is the presence of this current that makes it possible to keep the voltage on the proper level. Thus: in the proposed scheme, the transformer and co-condensers provide an automatic change in the capacitive current, i.e., automatic compensation of the reactive load current. Obviously, to obtain the indicated automaticity, the paralymeters of the transformer and capacitors must be chosen in strict accordance with the parameters of the generator

(ed. with. idling, short-circuit current, longitudinal and transverse reactance, etc.).

Unsaturated throttles D according to this scheme are selected so that the voltage resonance occurs for the 5th and 7th harmonic, i.e., for a fivefold and sevenfold frequency (relative to the fundamental frequency), which is necessary to ensure the filtering effect of the filter string. With this choice of chokes, all the possibility of resonance of the fundamental frequency voltage, the undesirability of which was indicated above, is excluded.

Subject invention

Device for voltage stabilization of a synchronous generator with constant excitation, magnets, consisting of a transformer with core saturation, adventured to the generator in parallel, characterized in that capacitors and chokes connected in series in the transformer secondary circuit are sized so that during idle run) a current resonance occurred in the transformer circuit and the current in the transformer primary winding was minimal. and with a decrease in the voltage caused by the load, the said resonance was completely violated, a capacitive current appeared in the primary winding of the transformer to compensate for the reactive voltage drop in the generator and thereby stabilizing the voltage at the terminals of the latter.

No. 66346

I T G

Shl