SU331470A1 - METHOD FOR DETERMINING THE STOCK OF STATIC STABILITY OF A SYNCHRONOUS MACHINE - Google Patents

Description

The invention relates to the field of operation of electric power systems and can be used for operational control during operation of the stock of static stability of engines, synchronous generators and compensators.

Modern electric power systems are subject to the requirement of static stability (stability in the “small”) in all possible modes of operation, which is achieved by working with some standard margin of stability.

During operation, the need arises to maintain a static stability margin within certain limits, since excessive reduction can lead to a system failure and stability, and an unreasonable increase leads to a deterioration of the efficiency of the power system due to a decrease in transmitted power, loss of G1HD, etc. .

In order to maintain the stability margin within the prescribed limits, it is necessary to periodically determine the actual stability margin with which the system operates.

The known method of determining the static stability margin of a synchronous machine from the amplitude-phase characteristic of an open-loop system, determined by supplying the input of the regulator's measuring organ to the input

excitement of a test sinusoidal signal of moving frequency and of the measurement of the trial signal and the signal caused by it at the output of the control system. However, with this method of determination, it is impossible to promptly dry out the stability control due to the large amount of computational work. In addition, the accuracy of the known method is small.

The essence of the described method consists in that they additionally measure the lead, регу 1 ÷ 1 regulator 1 yuvann, caused by the application of a test signal, at each frequency find the ratios of the signals on the system output signal and the test signal and the control error signal and cy. these ratios and depending on the received signals determine the static stability margin modulo and phase. In this case, the modulus of stability is defined as the inverse ratio of the signal at the output of the system to the signal of the adjustment error signal, if the specified sum of ratios is equal to one.

The phase stability margin is defined as twice a resin half of the ratio of the test signal to the control error signal, if the ratio of the signal at the system output to the control error signal is one.

the input of the measuring body of the excitation regulator serves a discontinuous test signal, after the end of the transient process, the sign of the ratio of the signal at the system output to the error signal i is determined at a negative sign, the margin of "slipping" is determined as the absolute value of this ratio.

On f-ig. 1 shows a block diagram of an apparatus for carrying out the described method; ia of FIG. 2 - vector diagrams of the signals of the automatic control system (ACS) of a synchronous machine.

The structural scheme of the SAR of a synchronous generator operating in parallel with the network is presented in the form of two blocks — a measuring body of voltage regulator 1 n of the rest of system 2 (power body: regulator, exciter, synchronous generator) having amplitude-phase characteristic (AFC ) W {JM).

To determine the stability margin in phase fn modulo a, a sinusoidal voltage is applied to the input of the measuring unit of voltage regulator 1 (3d, s sinco) from the sinusoidal oscillator 5. The frequency from this voltage and its amplitude and change using the control unit 4.

Under the influence of the voltage U on the input and output of the CAP of the synchronous generator, sinusoidal oscillations of the frequency are established with:

Ol / 2 Uisin (ai / -fil) |),

2 2 (/ asin (il; 2), where Ui, Uz are the effective values of the structure;

1) 1, ф2 - с |) azov shifts. For signals U, (/ 2, f / h, the following relationships are true:

and, - and, b

i2 - -F1 in (co)

where c / 1, Uz, Uu are vectors representing sinusomodilic stresses t / i, (/ 2, f / h.

FIG. Figure 2a shows a t / j vector voltage chart. Uz, and Uz for some arbitrary frequency with.

The vectors 1/1 and {/ 2 are lagging in phase from the vector (/ 3, respectively, at angles |) i and; 2. A phase shift between the vectors L / i n 0-2 constitutes an angle of (co).

When the frequency is changed from, the vector diagram is deformed, as the values (/; n t / 2 and shifts between vectors along c1) change.

FIG. 26 shows the same vector diagram for the frequency co, at which the modulus W (/ o) is equal to one:

A (o /) 1

on the stability margin in phase is related to the relation:

cf 2 arcsin 0.5 -. (i).

Thus, the stability margin of the phase cf can be determined from the ratio of the effective values of the voltages measured by the frequency of co with which condition 1 is fulfilled.

0

FIG. 2c shows a vector diagram for the frequency ω at which the angle is 0 (o)) l. The vectors UI, / 2, 3 are located on the same line. It follows that the ratio for this frequency is true.

five

 -I

(Iii) Ui ui

In this case, the stability margin of the modulus is inversely proportional to the ratio f / 2. / fA:

“-C-ТTakn. In a way, the modulus of the stability margin can be determined from the ratio of the effective values of the voltage Uz / U, measured for the frequency with for which condition III is fulfilled.

In order to determine the range of operation of the synchronous generator and determine the value of the stability margin by "sliding b (if the generator works in the field of artificial stability), at the input of the measuring body of the voltage regulator / stepwise change the voltage of the reference by an amount (L and determine the value and the sign of the ratio of the voltages LZ / UI at the input and output of the measuring body of the regulator, due to the voltage U.

If U2 / LJi 0, then the heptation works in the field of artificial stability (see with {) ig. 2) with the stock and stability of the "slide

- (IG) iv)

If (, then the generator works in the field of natural stability.

about

From the foregoing, the proposed method for determining the static stability margin of a synchronous machine and the principle of operation of the device for carrying out this method (see (}) step 1) become clear.

0

The device includes a sinusoidal oscillator, 9, a control unit 4, a voltage ratio measurement unit 5 and 6, a functional transducer 7 and S, a switch 9 and a recording unit 10.

five

A command from the control unit 4 starts a generator of sinusoidal oscillations 3 and a sinusoidal voltage Uy is fed to the input of the measuring body of the voltage regulator U, some fixed value

. (I). frequency of CO. After a certain time, the system establishes sinusoidal oscillations of the frequency of the cov voltages (/ and t / s are fed to the input of the block 5, in which the ratio of the acting

voltage values. The voltages f / i and f / 2 are fed to the input of block 6, in which the ratio of the effective values of the voltages is measured. The output signals of blocks 5 and 6, proportional to the ratios Uz / Ui and, are fed to the control unit 4 and to the input of functional converters 7 and 5, in which they are converted according to conditions II and IV. The output signals of the functional converters and unit 6 through the switch 9 can alternately be fed to the recording unit 0.

In control unit 4, the ratios are checked (/ 2 / f / i and f / 3 / f / i for conditions I and III. If either of these conditions is fulfilled, the control unit starts the registration unit W. If condition I is satisfied, then control switches switch 9 to a position that ensures registration of the output signal of the functional converter 7, which is equal to the stability margin in phase cf. If condition III is fulfilled, the control unit switches switch 9 to the position that registers the output signal of the functional converter 8, tory margin of stability is modulo a. If the conditions I and III are not performed, the registration is not performed.

After completion of operations at the frequency coi, the control unit 4 sends to the generator of sinusoidal oscillations 3 a command that provides a transition from the frequency to the next fixed value of the operating frequency 2. On the frequency, all operations are repeated. The measurement cycle of the stability margin in phase and modulo ends after the registration in block 10 of the values of ф and с or after bypassing all fixed values of the frequency с.

After the end of the measurement cycle, the control unit and the jump control unit changes by 4 the voltage of the task at the input of the measuring unit of the voltage regulator. After the new control unit is established in the control unit, the sign of the signal that comes from the unit 6, measuring voltage ratio Uz / Ui. If, which indicates the operation of the synchronous machine; in the field of artificial stability, the control unit starts the registration unit 10 and simultaneously switches the switch 9 to the position providing registration of the output signal of unit 6, the absolute value of which is equal to the stability margin of "sliding.

Measurement of the stability margin can be performed with manual control. In this case, a generator of sinusoidal oscillations 3 and meters for effective values of voltages Ui, U, U are necessary.

The described method for determining the static stability margin of a synchronous machine is distinguished by the following basic features:

pressure. Due to this, there is no need to calculate the AFC of an open-loop system W (/ co) from the dynamic characteristics of individual elements, since the values directly related to this system are measured; the time to determine the sustainability margin is significantly reduced; the possibility of fully automating the process of measuring the stability margin appears;

The performance of all measurements is simplified, and their accuracy is improved, since the signals at the input and output of the measuring body of the voltage regulator, as a rule, are reduced to the same scale and are easily measurable.

2. The measurement of the phase shift between two m. Sinusoidal voltages is replaced by the measurement of the ratio of the effective values of the sinusoidal stresses. As is known, devices for measuring the phase shift of two

Low-frequency voltages (phase meters) are usually more complex in terms of design and less accurate, in terms of devices that measure the effective values or ratios of the effective values of the same sinusoidal voltages. Therefore, replacing the measurement of phase shift with a measurement of the ratio of effective values makes it possible to simplify the design and improve the accuracy of measurement of the phase relations. The uniformity of the measuring units is an additional advantage of such a replacement, as it simplifies the manufacture and operation of the device.

3. You are to remove the area of work synchronously: machines and determination of the stability margin

The creep (if the machine works in the field of artificial stability) is performed by abruptly changing the voltage of the voltage regulator setting. Thanks to this. I don’t need to

performing measurements at frequencies corresponding to the low-frequency section of the AFC open loop system. Significantly reduces the time to determine the stability margin of "slipping, increases the accuracy of measurement

and simplifies the design of the apparatus used for this purpose.

4. In the measurement process, only the phase stability margin f, the modulus o stability margin and the "slip b stability margin" are recorded. Peak other parameters are not recorded. The measurement process after determining the values of φ, a, b ends. The measurement time is shortened.

Subject invention

Claims (4)

1. The method of determining the static stability margin of a synchronous machine by the amplitude-phase characteristic of an open-loop .0 of the system, determined by inputting a measuring regulator of the excitation regulator of a test sinusoidal signal of a varying frequency and measuring the value of the test sial and the signal caused by it, is that, in order to improve speed and accuracy of determining the stability margin, it is additionally measured the magnitude of the control error caused by the application of a test signal at each frequency is the ratio of the signals at the system output and the test signal to the control error signal and the sum of these ratios and depending on The received signals determine the static stability margin in terms of absolute value and phase. 2. A method according to claim 1, characterized in that the modulus of stability margin is defined as the reciprocal of the ratio of the signal at the system output to the control error signal, if the specified sum of ratios is equal to one. 3. The method according to claim 1, characterized in that the stability margin and phase are defined as double the arcsin half of the ratio of the test signal to the regulator error signal if the ratio of the signal at the system output to the error signal of the regulation is equal to one. 4. The method according to claim 1, characterized in that the input of the measuring organ of the regulator after the end of the transient process, the sign of the ratio of the signal at the system output to the error signal of the regulation is found and, at a negative sign, the creep margin as the absolute value of this ratio. ,; f 2arc5in0.5-7r 7