CN101382967B - Method for emulating main servo of hydrogovernor - Google Patents

Abstract

The invention relates to a simulation method of a main servomotor of a speed governor of a hydraulic turbine, and solves the technical problems that in the existing electric system calculation, the adopted simulation method of the main servomotor of the speed governor of the hydraulic turbine has poor veracity and big error when frequency fluctuation is large. The method includes an amplifying step, a servomotor speed amplitude limiting step and an integration amplitude limiting step, wherein, the amplifying step is that the amplification of an input signal is carried out and a relative speed of a follow-up system is obtained, the servomotor speed amplitude limiting step is that speed limiting to the main servomotor is carried out, and the integration amplitude limiting step is that the relative speed of the main servomotor is integrated and a relative displacement value of the main servomotor is obtained, and then the limiting to the displacement of the main servomotor is carried out according to the relative displacement value. The method can theoretically explain the operation process of every step of the main servomotor and every step and parameters have clear physical meanings; every parameter can be determined by practical measurement or parameter identification; the method has the advantages of being capable of simulating primary frequency modulation, the increase and decrease of load and large fluctuation modulation with higher precision degree.

Description

The emulation mode of main servo of hydrogovernor

Technical field

The present invention relates generally to the emulation mode of a kind of main servo of hydrogovernor that is used for the power system stability analytical calculation.

Background technology

Hydrogovernor is hydropower unit most important control parts, and main servomotor is as the topworks of speed regulator, and the correctness of its emulation mode and accuracy are directly connected to the electric system simulation result calculated.And the emulation mode that present general simulation analysis and electric system software for calculation the inside are adopted as shown in Figure 1, this emulation mode is simpler, do not consider the restrictive condition in the main servomotor motion process, physical significance is indeterminate, influence the accuracy of its emulation, under the bigger situation of frequency jitter, bigger error will occur.

Summary of the invention

The purpose of this invention is to provide a kind of new main servo of hydrogovernor emulation mode that usefulness is calculated in electric system that is used for, it has solved main servo of hydrogovernor emulation mode emulation poor accuracy that existing electric system adopted in calculating, the bigger technical matters of error under the bigger situation of frequency jitter.

Technical solution of the present invention is:

A kind of emulation mode of main servo of hydrogovernor, it comprises amplification procedure, sluggish step, main servomotor speed limiting step and integration amplitude limit step,

Described amplification procedure is the relative velocity that speed regulator servomechanism input signal is carried out the amplification of input signal divided by main servomotor reaction time constant and obtain main servomotor:

$v^{\′}=y_u\frac{1}{T_y}$

Wherein, v '-main servomotor relative velocity; y _uThe input of-servomechanism; T _y-main servomotor reaction time constant;

Described sluggish step is used to overcome the main control valve dead band,

The parameter value of described sluggish step obtains by parameter identification:

$y_c=\left\{\begin{array}{c}{y}_0+a/2,(y_1-y_0)\≤-a/2\\ y_0,-a/2\≤(y_1-y_0)\≤a/2\end{array}\right.$

y ₀-a/2，(y ₁-y ₀)≥a/2

Wherein, y ₀The initial value of the sluggish link of-input; y ₁The value of the sluggish link of-input; y _cThe output valve of-sluggish link; A-hysteresis loop pitch width degree;

Described main servomotor speed limiting step is to limit according to the size of the main servomotor relative velocity speed to main servomotor:

$v=\left\{\begin{array}{c}{v}_{\max },v^{\′}{\≥v}_{\max }\\ v^{\′},v_{\min }\≤v^{\′}{\≤v}_{\max }\\ v_{\min },v^{\′}\≤v_{\min }\end{array}\right.$

Wherein, v-main servomotor speed; v _MaxThe fastest opening speed of-main servomotor; v _Min-main servomotor is closed speed the soonest;

Described integration amplitude limit step is that the relative velocity with main servomotor carries out the relative displacement value that integration obtains main servomotor, and the displacement to main servomotor limits according to this relative displacement value then;

$y=\left\{\begin{array}{c}1,y^{\′}\≥1\\ y^{\′},0\≤y^{\′}\≤1\\ 0,y^{\′}\≤0\end{array}\right.$

Wherein, the displacement of y-main servomotor, y '-main servomotor relative displacement.

Advantage of the present invention is:

1, adopt emulation mode of the present invention can explain each step course of work of main servomotor, the explicit physical meaning of each step and parameter theoretically;

2, each parameter can be determined by actual measurement or parameter identification in this emulation mode;

3, big or great fluctuation process process is inappropriate to former emulation method for frequency disturbance, and emulation mode of the present invention can the emulation primary frequency modulation, increasing and decreasing load and great fluctuation process adjustment process, and simulation accuracy is higher.

Description of drawings

Fig. 1 is the structural representation of existing main servomotor emulation mode;

Fig. 2 is the structural representation of main control valve dead band main servomotor emulation mode of the present invention when big;

Fig. 3 hour can ignore the structural representation of the main servomotor emulation mode of main control valve dead band step (ignoring sluggish step) for the main control valve dead band;

Wherein: y _uThe input of-speed regulator servomechanism; T _y-main servomotor reaction time constant; v _MaxThe fastest opening speed of-main servomotor, v _Max=1/T _gv _Min-main servomotor is closed speed the soonest, v _Min=-1/T _fy _Max-main servomotor displacement the upper limit, i.e. fully open position, its value is 1; y _Min-main servomotor displacement lower limit, i.e. complete shut-down position, its value is 0.

Embodiment

Main servomotor emulation mode of the present invention specifically comprises four steps, is respectively amplification procedure (referring to first module among Fig. 2 or Fig. 3), sluggish step (referring to second module among Fig. 2), main servomotor speed limiting step (referring to the 3rd module among Fig. 2 or second module among Fig. 3), integration amplitude limit step (referring to the 4th module among Fig. 2 or the 3rd module among Fig. 3).

The coefficient T of amplification procedure _yBe main servomotor reaction time constant.

Sluggish step is meant because dead band and the main servomotor control lag that the lap of main control valve causes.

Main servomotor speed limiting step is meant that main servomotor speed is subjected to the restriction of the fastest open and close machine time, determines the speed limiting v on the opening direction by testing the fastest open and close machine time of main servomotor _Max=1/T _f, the speed limiting v on the closing direction _Min=-1/T _g

Integration amplitude limit step has been described the acting characteristic of main servomotor, and the main servomotor displacement to fully open position, represents with relative value that from the complete shut-down position corresponding amplitude limit minimum value is y _Min=0, corresponding amplitude limit maximal value is y _Max=1.

The principle of the invention:

Generally form in the hydrogovernor servomechanism by amplifier, electric liquid/machine conversion, main control valve, main servomotor, its course of work is that amplifier at first amplifies and digital-to-analog conversion the input signal of servomechanism, by being converted to hydraulic pressure or the displacement signal that can control main control valve after the conversion of electric liquid/machine, the motion action main servomotor by main control valve moves.Therefore need to reflect the course of work and the restrictive condition of each step in the emulation mode.

Main servomotor reaction time constant T _yBe numerically equal to open loop amplification coefficient K _OpInverse.Open loop amplification coefficient K in servomechanism _OpBe adjustable, the amplification coefficient of the LOCAL FEEDBACK lever ratio by changing the mechanical-hydraulic servomechanism or the electric group amplifier of electric hydraulic servomechanism.

For reducing the leakage of pressure oil, the bush hole open height deposited by main control valve and there is certain lap in valve disc in the main control valve of hydrogovernor.The main servomotor piston also bears the power R that Hydraulic Moment caused that acts on the stator in real work, and the main servomotor piston is also wanted overcome friction T when mobile, the resistance that need overcome toward a direction motion time is R+T, is R-T at the resistance that need overcome when opposite direction is moved.The displacement of main control valve valve body from middle position when the opening and closing direction need surpass certain position main servomotor just begin to move, this scope is called the main control valve dead band, valve body moves in this scope, main servomotor does not move.This dead band makes speed regulator have rotating speed dead band and main servomotor control lag, hour can ignore in the dead band, and can not ignore when big in the dead band, represents with a sluggish step.

In practical work process, main servomotor speed is subjected to the restriction of the fastest open and close motor speed of main servomotor.Speed limit on the start direction is numerically equal to main servomotor with the time T of prestissimo from the complete shut-down position to fully open position _gInverse.The speed limit of shutdown on the direction, be numerically equal to main servomotor with prestissimo the time T from fully open position to the complete shut-down position _fThe opposite number of inverse.The shift value of main servomotor, therefore need limit the shift value of main servomotor to the complete shut-down position from fully open position, represents from 0 to 1 with relative value, represents complete shut-down position and fully open position respectively.

Under the less situation of frequency disturbance, former emulation method and emulation mode of the present invention differ not obvious, but under big frequency disturbance, because former emulation method does not limit main servomotor speed, bigger difference will appear in emulation.Fig. 4 is the comparison of the curve of the simulation curve of the simulation curve of the former emulation method that adopts Fig. 1, the bright emulation mode of this law among Fig. 2 and field measurement, obviously the curve and the measured curve of emulation mode of the present invention are more approaching, and bigger error appears in the curve of former emulation method.

Claims (1)

1. the emulation mode of a main servo of hydrogovernor, it is characterized in that: it comprises amplification procedure, sluggish step, main servomotor speed limiting step and integration amplitude limit step,

Described amplification procedure is the relative velocity that speed regulator servomechanism input signal is carried out the amplification of input signal divided by main servomotor reaction time constant and obtain main servomotor:

$v^{\′}=y_u\frac{1}{T_y}$

Wherein, v '-main servomotor relative velocity; y _uThe input of-servomechanism; T _y-main servomotor reaction time constant;

Described sluggish step is used to overcome the main control valve dead band,

The parameter value of described sluggish step obtains by parameter identification:

$y_c=\left\{\begin{array}{c}{y}_0+a/2,(y_1-y_0)\≤-a/2\\ y_0,-a/2\≤(y_1-y_0)\≤a/2\\ y_0-a/2,(y_1-y_0)\≥a/2\end{array}\right.$

Wherein, y ₀The initial value of the sluggish link of-input; y ₁The value of the sluggish link of-input; y _cThe output valve of-sluggish link; A-hysteresis loop pitch width degree;

Described main servomotor speed limiting step is to limit according to the size of the main servomotor relative velocity speed to main servomotor:

$v=\left\{\begin{array}{c}{v}_{\max },v^{\′}\≥v_{\max }\\ v^{\′},v_{\min }\≤v^{\′}\≤v_{\max }\\ v_{\min },v^{\′}\≤v_{\min }\end{array}\right.$

Wherein, v-main servomotor speed; v _MaxThe fastest opening speed of-main servomotor; v _Min-main servomotor is closed speed the soonest;

Described integration amplitude limit step is that the relative velocity with main servomotor carries out the relative displacement value that integration obtains main servomotor, and the displacement to main servomotor limits according to this relative displacement value then;

$y=\left\{\begin{array}{c}1,y^{\′}\≥1\\ y^{\′},0\≤y^{\′}\≤1\\ 0,y^{\′}\≤0\end{array}\right.$

Wherein, the displacement of y-main servomotor, y '-main servomotor relative displacement.

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