SU1203443A1 - Method of determining emf and inductive impedance of synchronous generator - Google Patents

Abstract

The invention makes it possible to improve the accuracy of determining the emf and inductive resistance by higher harmonics. The method involves loading the generator at the fundamental harmonic from idle to rated power, and the generator current and voltage are measured. In addition, in the method, the component of the highest harmonic is extracted from the load current, by changing the correction circuit connected in parallel to the load, the maximum value of the highest harmonic current is obtained, the highest harmonic in the voltage is measured, and the inductance and EMF are determined from the measured values. This method allows one to substantiate the choice of filter parameters that limit the harmonic components of the generator voltages to the required level. 4 il. i (L o o 00 4 4 00

Description

The invention relates to the field of electric machines, namely to measuring their parameters, and could be used to select filter parameters limiting the highest harmonic components of the voltage at the generator terminals to the required level, as well as to assess the quality of electricity in autonomous power supply systems and in designing low-power synchronous generators.

The purpose of the invention is to improve the accuracy of measurement of EMF and inductive resistance by higher harmonics.

Fig. 1 shows the initial generator replacement circuit for the n-th harmonic when operating on active load according to the fundamental harmonic; Fig. 2 is a diagram of the experimental setup for determining the parameters of the machine on the harmonic under investigation; in Fig. 3, a typical dependence of the current of the studied harmonic in the generator branch on the capacitor capacitance in the correction branch; 4 shows graphs of the desired parameters of a synchronous generator and the voltage of the harmonic under study at its terminals as a function of the load current, as well as calculated and experimental dependencies of the voltage of the investigated harmonic as a function of the generator load current when there are higher harmonics of the filter generator with the known parameters at the filtering frequency.

The replacement circuit of synchronous generator 1 as a source of high-harmonic emf (order of harmonics n) with internal resistance for

pth harmonic

Zan

Jx

l

X,

 ZW} ft: a (r;) (c r,) + n.

an

 ; -xsM

where TO is the active resistance of the cor.

In expression (5), the parameter X., determined from (1), is calculated from the value of the capacitance of the capacitor 6, at which the current Ian of the generator branch is maximum (fixed by the harmonic analyzer 8).

In determining the EMF E, the machines use experimental data to determine the voltage of the harmonic under study at the terminals of the generator2034432

working on linear active

load with resistance g. The desired parameters are generator resistance I X and its E ,,

A device for measuring the source 1X parameters of the synchronous generator 1 connected to the load 2 contains a correction circuit 3 consisting of inductors 4 with L connected in parallel and capacitor C with capacitance C, tuned to resonance at the fundamental frequency, and filter -tube for this harmonic. A capacitor 6 of variable capacitor C is connected in series with this filter, a shunt 7 is connected in series with a load 2, to which the harmonic analyzer 8 is connected.

Equivalent resistance of the correction chain 3 X (. "Is determined by

one)

where u; - circular frequency of the main harmonic.

Since the p-th harmonic current in the system is a synchronous generator — an external circuit is equal to IQH П 2, is the resulting resistance, the condition under which the current value takes the maximum value is the zero value of the derivative of the resulting resistance

Determined by the well-known rules 2 and taking a derivative of it in Xf from it, we obtain the inductive resistance of the core phase in terms of the harmonic

(2)

pa with a given load on the main harmonic with the correction branch 3 disconnected. According to the XQ ,, U, found from the experiment, and known

HEY and, | l + ri-) + fl (3) n Oi

The method of work to determine the parameters of the synchronous generator by higher harmonics with mixed

3

load (active-inductive) is similar.

The method is carried out as follows.

Connect the generator 1 to the load 2 and set the load current. In parallel with the load 2, a correction chain 3 is connected, the current of the p-th harmonic is extracted from the load current by the harmonic analyzer 8. By changing the capacitor capacitance 6, the maximum value of the nth harmonic current is achieved. Then the capacitance 6 of the capacitor 6 is measured, corresponding to the maximum current value of the p-th harmonic. The correction chain 3 is disconnected, the voltage harmonic is measured by an 8 p harmonic analyzer, and the EMF and inductive resistance of the synchronous generator are calculated using p harmonics using formulas.

The above method for determining the parameters E (d and X is used for single-phase and three-phase synchronous generators with a capacity of 0.2–6.0 kVA. As an example, FIGS. 3 and 4 show the results of studies of the parameters of a single-phase generator of the aviation converter PO-500 at the seventh harmonic with checking the correctness of the found parameters Ef, and X (j through the seventh harmonic filter with known parameters. From figure 4 it is clear that the calculated and experimental curves Uj f () when the machine is running with the seventh harmonic filter almost coincide, o confirms the correctness of the definition of the parameters E ,, and XQf, no to the method described.

The use of the invention allows:

to substantiate the choice of the parameters of fillers that limit the higher harmonic components of the voltage of the generators to the required level;

assess the quality of electricity in autonomous power supply systems;

justify the TOR for receivers sensitive to higher harmonics in the supply voltage;

2034434

improve working conditions for receivers sensitive to higher harmonics;

take into account the results obtained in the design of promising autonomous sources of electrical energy;

to estimate the change in the EMF and inductance of the resistance of low-power synchronous generators at frequencies of higher harmonics depending on the magnitude of the load (with a constant nature of the load);

to estimate the change of EMF and inductive resistances of low-power generators at frequencies of higher harmonics depending on the nature of the load (at a constant value of 45

20

loads).

Claims (1)

Invention Formula 25 A method for determining the EMF and inductive resistance of a synchronous generator by higher harmonics by loading the generator by the main harmonic from idling to but minal power, measuring the current and voltage of the generator, characterized in that, in order to improve the accuracy of determining EMF and inductive resistance by higher harmonics set  a fixed value of the load current is connected in parallel with the resistance of the load correction circuit, consisting of a filter plug on the main harmonic and in series With a switched-on variable capacitor connected to it, the component of the highest harmonic is separated from the load current, changing the capacitance of the capacitor, achieving the maximum value The indicated current component determines the value of the capacitance corresponding to the maximum value of the highest harmonic current, turns off the correction circuit, AND measures the highest 50 harmonic of the same order in the voltage, and calculates the inductance and the highest harmonic voltage from the measured parameters. R Xan .yv one Phage. I 0.1 0.2 O.J 0, U 0.5 0.6 0.7 0.7 C, Fig.Z Experiment Payment and -G (1n) 7 - Y (1n) Uj-f (l) I with Heauvuu Vutitmpa 7 ta / H t 0U9.i , VNIIPI Order 8411/48 Circulation 747 Subscription - - --- "... .- - I.II .----. Branch P1Sh Patent, Uzhgorod, Project.A, A 5 IH.A cosfM