CN104063584A - Control parameter setting method for steam turbine speed governing system - Google Patents

Abstract

A method for tuning control parameters of a steam turbine speed control system, comprising the following steps: 1) establishing a mathematical model and a transfer function of the steam turbine speed control system of the single-machine infinite system when the grid model is included; 2) when the control parameters K _i and K _p are in When changes occur within the range of 0 to 10, continuously find the numerical solution of the characteristic root of the system transfer function under the given parameters; the expression of the characteristic root is: s=A+Bj; 4) draw the change trend diagram of the minimum value of each characteristic parameter ξ with the control parameters K _i and K _p ; 5) judge whether the system is stable or not according to the positive or negative of the characteristic parameter ξ, from The value range of the control parameters that make the system stable is obtained in the figure, and the trial and error method is used for fine-tuning to set the optimal control parameters that are actually applicable to the unit. The invention has very important significance for further standardizing the parameter setting of the steam turbine control system and reducing the occurrence of low-frequency oscillation of the system.

Description

A Method for Tuning Control Parameters of Steam Turbine Speed Governing System

technical field

The invention belongs to a control method for speed regulation of a steam turbine and a safe and stable operation of a power grid, in particular to a method for setting parameters of a steam turbine controller in the field of improving the dynamic stability of a power system and preventing low-frequency oscillation of the power grid.

Background technique

In recent years, as my country's electricity demand has increased year by year, the scale of the power system has become larger and larger, and the power transmitted on the main transmission line has also continued to increase. The operating conditions of the entire power system have become increasingly harsh, and low-frequency oscillations occur from time to time. It is one of the important factors restricting the power transmission of the tie line and the safe and stable operation of the interconnected grid. Due to several low-frequency oscillation accidents caused by the power supply side in recent years, the research on low-frequency oscillation on the power supply side has gradually attracted people's attention. Many experts have analyzed several power oscillation events in the Southern Power Grid, indicating that there is a correlation between low-frequency oscillation and the instability of the speed regulation system on the turbine side.

Through the analysis of the working principle of the steam turbine, combined with the resonance mechanism of low-frequency oscillation, the possible causes of forced power oscillation on the turbine side are analyzed. Although the forced power oscillation mechanism can explain some low-frequency oscillation phenomena, in previous studies, in order to simulate the forced disturbance source, a periodic disturbance was often artificially added directly to a certain link of the system, which is inconsistent with the actual situation. Studies have shown that if some control parameters on the power supply side are not set properly, a negative damping torque will be provided to the system, thereby reducing system damping and causing negative damping oscillation of the power grid. Some experts analyzed the influence of the main parameters on the damping characteristics of the power grid by using the simplified model of the speed control system, and pointed out that the improper setting of the proportional coefficient in the controller will lead to negative damping effect after the primary frequency regulation circuit is put into operation, resulting in low-frequency oscillation of the power grid. However, there is still a lack of research on how controller parameter changes will affect system stability, and how to give a reasonable range of controller parameters based on power system stability analysis.

Contents of the invention

In order to solve the above-mentioned reasonable range of the reasonable setting of the controller parameters, the present invention provides a method for setting the control parameters of the steam turbine speed control system, the purpose of which is to further standardize the setting of the parameters of the steam turbine control system and reduce the occurrence of low frequency oscillations in the system , to maintain the stability of the power system.

In order to achieve the above object, the present invention realizes according to the following method steps:

Step 1: Establish the mathematical model of the steam turbine speed control system of the single-unit infinite system including the power grid model, and use the corresponding object model identification module in the existing working condition system to obtain the mathematical model of the controlled object and various parameters, the main parameters The transfer function between is the transfer function of the mathematical model of the steam turbine speed control system when the grid model is included, as shown in the following formula:

$<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&delta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; pid</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; pid</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;\&omega;</span>}<span\; class="notranslate">\; ;</span>$

$<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; )</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&Delta;\&omega;</span>}<span\; class="notranslate">\; ;</span>$

$\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&Delta;\&delta;</span>}<span\; class="notranslate">\; ;</span>$

$<span\; class="notranslate">\; \&DoubleRightArrow;</span>\frac{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; pid</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}<span\; class="notranslate">\; ;</span>$

In the above formulas, K ₁ , K ₂ , K ₃ , K ₄ , K ₅ , and K ₆ are proportional coefficients, K _A is the proportional coefficient of the exciter, s is the differential operator after Laplace transformation, and δ is the speed adjustment Difference coefficient, Δw is the rotational speed angular velocity deviation, Δw _r is the rotational speed disturbance value, Δδ is the generator power angle deviation, ΔP _m is the mechanical power increment, ΔP _e is the electromagnetic power increment, T ₁ represents the time constant of the speed transmitter , T ₃ is the time constant of the excitation circuit, T _R is the time constant of the voltage sensor, T _σ is the time constant of the steam turbine rotor, G1 is the transfer function of the single-machine infinite system, G2 is the first-order inertia transfer of the speed transmitter in the control system function, G _e is the transfer function of the electro-hydraulic servo, G _t is the transfer function of the series combination and single reheat steam turbine, G _pid is the transfer function of the controller, G3 is the transfer function of the steam turbine speed control system, and G ₄ is the Simplified forms have no corresponding physical meaning. Among them, G1, G2, G3, and G4 are defined as:

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ;</span>$

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&delta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; pid</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; pid</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; ;</span>$

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; ;</span>$

Step 2: Transfer function to the control system model The control parameters Kp and Ki of the speed control system in , set multiple groups of different arrays in the range of 0 to 10, and respectively calculate the characteristic root of the transfer function of the controlled object under each group of array parameters, and obtain the characteristic root by calculating the numerical method The value range of the control parameters of the speed control system is obtained, where K _i is the integral control parameter of the speed control system, K _p is the proportional control parameter, K _d is the differential control parameter, and s is the differential operator;

Analyzing the transfer function of the controlled object, it can be obtained that the characteristic root of the controlled object transfer function can be a non-zero root and a conjugate complex root on the real axis, expressed by the following formula:

s=A+Bj,

where A and B are the real and imaginary parts of the characteristic root, respectively;

For the second-order oscillation link, its characteristic root is a pair of conjugate complex roots, and the expression is as follows:

${\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 1,2</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&xi;</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \&PlusMinus;</span>\mathrm{<span\; class="notranslate">\; j</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span>$

Among them, the characteristic parameter ξ is the damping ratio, and ω _n is the undamped oscillation frequency.

Step 3: Calculate the size of the characteristic parameter ξ of each group of characteristic roots, and obtain the smallest value of ξ, as can be seen from the above formula,

A=-ξω _n ,

$\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; \&PlusMinus;</span>\mathrm{<span\; class="notranslate">\; j</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span>$

Taking A and B in the above equation as known, the damping ratio can be obtained by the simultaneous equation

$\mathrm{<span\; class="notranslate">\; \&xi;</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; A</span>}}{\sqrt{{\mathrm{<span\; class="notranslate">\; A</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; B</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span>}$

It is known from the above formula that when ξ is less than zero, the real part of the characteristic root of the system is not negative, and the second-order system is unstable. The damping ratio of the second-order system can reflect the stability of the second-order system. In the analysis of the steam turbine speed control system considering the grid model Whether it is stable or not, obtain its characteristic parameter ξ for each characteristic root;

Step 4: According to the minimum characteristic parameter ξ of the characteristic root corresponding to each group of parameters in the speed control system obtained in step 3, draw the curve of the characteristic parameter ξ changing with the parameters K _p and K _i of the governor. When the characteristic root is When the complex conjugate root is used, ξ is the damping ratio of the second-order link; when the characteristic root is a non-zero real root, ξ takes ±1, if the real root is less than zero, ξ is 1, and if the real root is greater than zero Then ξ is -1; when the system is stable, all the characteristic roots of the system have negative real parts, and at the same time, it can be deduced that the characteristic parameters ξ of all characteristic roots take positive values, so according to the characteristic parameters ξ presented by the controlled object Determine the value range of the control parameters that make the system stable with the change image of each group of control parameters;

Step 5: According to the mathematical model of the steam turbine speed control system established in the above steps 1 to 3 and the change trend diagram drawn in step 4, fine-tuning is carried out by trial and error method, and the optimal control parameters that are actually applicable to the unit are adjusted.

The present invention proposes a method for setting the control parameters of the steam turbine speed control system based on the stability of the power system. Since the model of this method includes the power grid side system, it is more similar to the real model, so it is greatly reduced compared with the previous setting method. Reasonable range of controller parameters that will not cause system instability; and it is very practical, unlike the previous tuning method, although it is stable when a single machine is running, it may oscillate when multiple machines are running; this is for further It is of great significance to standardize the parameter setting of the steam turbine control system and reduce the occurrence of low-frequency oscillation of the system.

Description of drawings

Fig. 1 is the schematic flow chart of the embodiment of the governor control system parameter setting method of the present invention;

Fig. 2 is the structural diagram of the embodiment of the speed control system control parameter tuning method of the present invention;

Fig. 3 is the schematic diagram of the control system model of the embodiment of the present invention;

Fig. 4 is the schematic diagram of the model of the electro-hydraulic servo of the embodiment of the present invention;

Fig. 5 is the steam turbine model schematic diagram of the embodiment of the present invention;

Fig. 6 is a schematic diagram of a stand-alone infinite system model of an embodiment of the present invention;

Fig. 7 is a graph showing the variation trend of the characteristic parameter ξ with the control parameters of the governor.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Figure 3 is the simulation model of the control system. After ignoring the nonlinear link, its transfer function is Among them, _T1 represents the time constant of the speed transmitter, with a value of 0.02; the value of the slow rate of speed regulation is 0.025; the K behind the link of the slow rate of speed regulation represents the primary frequency modulation difference coefficient (that is, the speed unequal rate), and the value is 20; K _p , K _i , and K _d are the proportional amplification factor, integral time constant, and differential time constant of the load controller PID, respectively, and the values are 1, 0.05, and 0 respectively; K ₂ represents the amplification factor of the speed feedforward control, and the parameters are taken as 1, 1 in Figure 3 is the speed transmitter. 2 is the PID load controller, _Pref is the given active power, and P _e is the feedback power of the grid side.

Figure 4 is the simulation model of the electro-hydraulic servo, and its transfer function is Among them, P _cv is the door adjustment instruction; K _p1 , K _i1 , and K _d1 are the PID parameters of the valve controller, and the values are 9, 0, and 0; and 1.33; where T ₂ represents the time constant of the linear displacement sensor, 3 in Fig. 4 is the valve PID controller, 4 is the valve switch controller, 5 is the opening and closing delay link of the oil motor, 6 is the oil motor, and 7 is the linear displacement variable Transmitter, the parameter is taken as 0.02.

Fig. 5 is a simulation model of a steam turbine with intermediate reheating, and its transfer function is

$G_T=\frac{((1+\mathrm{\&lambda;})(1+T_{\mathrm{rh}}\mathrm{the\; s})(1+T_{\mathrm{co}}\mathrm{the\; s})f_{\mathrm{hp}}+(f_{\mathrm{ip}}-\mathrm{\&lambda;}{f}_{\mathrm{hp}})(1+T_{\mathrm{co}}\mathrm{the\; s})+f_{1p})}{\left((1+T_{\mathrm{ch}}\mathrm{the\; s})(1+\stackrel{}{T_{\mathrm{rh}}}\mathrm{the\; s})(1+T_{\mathrm{co}}\mathrm{the\; s})\right)},$ Among them, P _GV is the opening degree of the regulating door; _PM is the output mechanical power; the time constants T _ch , T _rh and T _co respectively represent the time delay produced by the steam chamber and the air inlet pipe, the reheater and the cross pipe system , the parameters are taken as 0.1, 12, 1; F _hp , F _ip and F _lp represent the shares of the high, medium and low pressure cylinders in the total mechanical power, and the values are 0.32, 0.68, 0 (the work coefficient of the low pressure cylinder is 0 is to regard the middle and low pressure cylinders as a whole); λ represents the natural overadjustment coefficient of the high pressure cylinder power, a parameter with a value of 0.9, 8 in Figure 5 is the volume of high pressure steam, 9 is the volume of reheated steam, and 10 is the volume of low pressure steam connected .

Figure 6 is the simulation model of a single-machine infinite system. After ignoring the nonlinear link, its transfer function is

$G_1\left(\mathrm{the\; s}\right)=\frac{\mathrm{\&Delta;}{P}_e}{\mathrm{\&Delta;\&delta;}}=(K_1-\frac{K_2{K}_3\left[K_4(1+\mathrm{the\; s}{T}_R+K_5{K}_A)\right]}{{\mathrm{the\; s}}^2{T}_3{T}_R+\mathrm{the\; s}(T_3+T_R)+1+K_3{K}_6{K}_A}),$ Among them, K ₁ , K ₂ , K ₃ , K ₄ , K ₅ , and K ₆ are proportional coefficients; Δw _r is the speed disturbance value, Δδ is the generator power angle deviation; 19ΔT _m is the mechanical power increment; 18ΔT _e is the electromagnetic Power increment; Δψ _f d is the flux linkage increment of the excitation circuit; ΔE _fd is the output voltage increment of the exciter; U _PSS is the output signal of the power system stabilizer; T ₃ is the time constant of the excitation circuit; T _R is the time constant of the voltage sensor ; K _A is the proportional coefficient of the exciter, ΔV _ref is the reference output voltage, and ΔV ₁ is the output voltage of the voltage sensor. The parameters are all typical values. In Figure 6, 11 is the exciter, and 12 is the transfer function of speed and power. 13 is the transfer function of generator speed and phase angle, 14 is a voltage sensor, and 15 is an excitation circuit.

As shown in the flow diagram of the method for adjusting the control parameters of the speed control system of the present invention in Fig. 1, the method for setting the control parameters of the speed control system in the embodiment of the present invention includes steps:

Step 1 (S101): Establish the mathematical model of the steam turbine speed control system of the single-unit infinite system when the grid model is included, establish the simulation model diagram of the current implementation example, and the process of identifying the mathematical model of the current object generally uses the existing working condition system The corresponding object model identification module in the system obtains the mathematical model of the controlled object and various parameters, and the transfer function between the main parameters is the mathematical model of the steam turbine speed control system when the power grid model is included, as shown in the following formula:

$<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&delta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; pid</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; pid</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;\&omega;</span>}<span\; class="notranslate">\; ;</span>$

$<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; )</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&Delta;\&omega;</span>}<span\; class="notranslate">\; ;</span>$

$\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&Delta;\&delta;</span>}<span\; class="notranslate">\; ;</span>$

$<span\; class="notranslate">\; \&DoubleRightArrow;</span>\frac{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; pid</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}<span\; class="notranslate">\; ;</span>$

In the above formulas, K ₁ , K ₂ , K ₃ , K ₄ , K ₅ , and K ₆ are proportional coefficients, K _A is the proportional coefficient of the exciter, s is the differential operator after Laplace transformation, and δ is the speed adjustment Difference coefficient, Δw is the rotational speed angular velocity deviation, Δw _r is the rotational speed disturbance value, Δδ is the generator power angle deviation, ΔP _m is the mechanical power increment, ΔP _e is the electromagnetic power increment, T ₁ represents the time constant of the speed transmitter , T ₃ is the time constant of the excitation circuit, T _R is the time constant of the voltage sensor, T _σ is the time constant of the steam turbine rotor, G1 is the transfer function of the single-machine infinite system, G2 is the first-order inertia transfer of the speed transmitter in the control system function, G _e is the transfer function of the electro-hydraulic servo, G _t is the transfer function of the series combination and single reheat steam turbine, G _pid is the transfer function of the controller, G3 is the transfer function of the steam turbine speed control system, and G ₄ is the Simplified forms have no corresponding physical meaning.

Among them, G1, G2, G3, and G4 are defined as:

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ;</span>$

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&delta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; pid</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; pid</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; ;</span>$

${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; ;</span>$

Step 2 (S102): For the following control system model transfer function In the speed control system control parameters Kp and Ki in the range of 0 to 10, set multiple groups of different arrays, respectively calculate the characteristic root of the transfer function of the controlled object under each group of array parameters, because the order of the characteristic equation of the system is relatively high , the value range of each parameter in the speed control system cannot be obtained by obtaining the analytical solution, but the numerical solution of the characteristic root can only be obtained by obtaining the numerical method, and then the value of the control parameters of the speed control system can be obtained scope.

Since the high-order system can be reduced to a combination of zero-order, first-order, and second-order links, the oscillation component is mainly the second-order oscillation link. By analyzing the transfer function of the controlled object, it can be known that there is no zero-order link, then the characteristic roots of the transferred function of the controlled object can be non-zero roots and conjugate complex roots on the real axis, which can be expressed by the following formula:

s=A+Bj,

where A and B are the real and imaginary parts of the characteristic root, respectively;

For the second-order oscillation link, its characteristic root is a pair of conjugate complex roots, and the expression is as follows:

${\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 1,2</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&xi;</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \&PlusMinus;</span>\mathrm{<span\; class="notranslate">\; j</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span>$

Among them, the characteristic parameter ξ is the damping ratio, and ω _n is the undamped oscillation frequency.

Step 3 (S103): Calculate the size of the characteristic parameter ξ of each group of characteristic roots, and obtain the smallest value of ξ. It can be seen from the above formula that,

A=-ξω _n ,

$\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; \&PlusMinus;</span>\mathrm{<span\; class="notranslate">\; j</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span>$

Taking A and B in the above equation as known, the damping ratio can be obtained from the simultaneous equations

$\mathrm{<span\; class="notranslate">\; \&xi;</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; A</span>}}{\sqrt{{\mathrm{<span\; class="notranslate">\; A</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; B</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span>}$

From the above formula, when ξ is less than zero, the real part of the characteristic root of the system is not negative, and the second-order system is unstable, so the damping ratio of the second-order system can reflect whether the second-order system is stable or not. Therefore, when analyzing whether the steam turbine speed control system of the grid model is stable, the characteristic parameter ξ can be obtained for each characteristic root.

Step 4 (S104): According to the minimum characteristic parameter ξ of the characteristic root corresponding to each group of parameters in the speed control system obtained in step 3, draw the curve of the characteristic parameter ξ changing with the parameters K _p and K _i of the governor, such as Shown in accompanying drawing 6. When the characteristic root is a conjugate complex root, ξ is the damping ratio of the second-order link; when the characteristic root is a non-zero real root, ξ is taken as ±1, and if the real root is less than zero, ξ is 1, if If this real root is greater than zero, then ξ is -1. When the system is stable, all the characteristic roots of the system have negative real parts, and at the same time, it can be deduced that the characteristic parameters ξ of all characteristic roots take positive values. Therefore, the value range of the control parameters that stabilize the system can be determined according to the characteristic parameter ξ presented by the controlled object with the change image of each group of control parameters.

Step 5 (S105): Through the simulation model of the controlled object established in the previous steps, use the trial and error method to fine-tune within this range, and set the optimal control parameters that are actually applicable to the unit.

The trial and error method adopted in the embodiment of the present invention is to make the integral control parameter K in the speed regulating system _take a value between 0～3.1 according to the variation trend diagram of the characteristic parameter ξ in the accompanying drawing 7 with the governor control parameter, And keep it unchanged, slightly change the proportional control parameter K _p of the speed control system in the range of 0 to 4, and select the optimal control system array parameters by observing the simulation results of the system.

Claims (1)

1. a steam turbine speed control system control parameter tuning method, is characterized in that comprising the steps: Step 1: Establish the mathematical model of the steam turbine speed control system of the single-unit infinite system including the power grid model, and use the corresponding object model identification module in the existing working condition system to obtain the mathematical model of the controlled object and various parameters, the main parameters The transfer function between is the transfer function of the mathematical model of the steam turbine speed control system when the grid model is included, as shown in the following formula: $<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&delta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; pid</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; pid</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}\mathrm{<span\; class="notranslate">\; \&Delta;\&omega;</span>}<span\; class="notranslate">\; ;</span>$ $<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; )</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; \&Delta;\&omega;</span>}<span\; class="notranslate">\; ;</span>$ $\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&Delta;\&delta;</span>}<span\; class="notranslate">\; ;</span>$ $<span\; class="notranslate">\; \&DoubleRightArrow;</span>\frac{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; pid</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}}<span\; class="notranslate">\; ;</span>$ In the above formulas, K ₁ , K ₂ , K ₃ , K ₄ , K ₅ , and K ₆ are proportional coefficients, K _A is the proportional coefficient of the exciter, s is the differential operator after Laplace transformation, and δ is the speed adjustment Difference coefficient, Δw is the rotational speed angular velocity deviation, Δw _r is the rotational speed disturbance value, Δδ is the generator power angle deviation, ΔP _m is the mechanical power increment, ΔP _e is the electromagnetic power increment, T ₁ represents the time constant of the speed transmitter , T ₃ is the time constant of the excitation circuit, T _R is the time constant of the voltage sensor, T _σ is the time constant of the steam turbine rotor, G1 is the transfer function of the single-machine infinite system, G2 is the first-order inertia transfer of the speed transmitter in the control system function, G _e is the transfer function of the electro-hydraulic servo, G _t is the transfer function of the series combination and single reheat steam turbine, G _pid is the transfer function of the controller, G3 is the transfer function of the steam turbine speed control system, and G ₄ is the Simplified forms have no corresponding physical meaning. Among them, G1, G2, G3, and G4 are defined as: ${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 5</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>}{{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; R</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 6</span>}}{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ;</span>$ ${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; ;</span>$ ${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; \&delta;</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; pid</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; pid</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; ;</span>$ ${\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; G</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; ;</span>$ Step 2: Transfer function to the control system model The control parameters Kp and Ki of the speed control system in , set multiple groups of different arrays in the range of 0 to 10, and respectively calculate the characteristic root of the transfer function of the controlled object under each group of array parameters, and obtain the characteristic root by calculating the numerical method The value range of the control parameters of the speed control system is obtained, where K _i is the integral control parameter of the speed control system, K _p is the proportional control parameter, K _d is the differential control parameter, and s is the differential operator; Analyzing the transfer function of the controlled object, it can be obtained that the characteristic root of the controlled object transfer function can be a non-zero root and a conjugate complex root on the real axis, expressed by the following formula: s=A+Bj, where A and B are the real and imaginary parts of the characteristic root, respectively; For the second-order oscillation link, its characteristic root is a pair of conjugate complex roots, and the expression is as follows: ${\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 1,2</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; \&xi;</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \&PlusMinus;</span>\mathrm{<span\; class="notranslate">\; j</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span>$ Among them, the characteristic parameter ξ is the damping ratio, and ω _n is the undamped oscillation frequency. Step 3: Calculate the size of the characteristic parameter ξ of each group of characteristic roots, and obtain the smallest value of ξ, as can be seen from the above formula, A=-ξω _n , $\mathrm{<span\; class="notranslate">\; B</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; \&PlusMinus;</span>\mathrm{<span\; class="notranslate">\; j</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}\sqrt{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&xi;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span>$ Taking A and B in the above equation as known, the damping ratio can be obtained by the simultaneous equation $\mathrm{<span\; class="notranslate">\; \&xi;</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; A</span>}}{\sqrt{{\mathrm{<span\; class="notranslate">\; A</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; B</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; ,</span>}$ It is known from the above formula that when ξ is less than zero, the real part of the characteristic root of the system is not negative, and the second-order system is unstable. The damping ratio of the second-order system can reflect the stability of the second-order system. Whether it is stable or not, obtain its characteristic parameter ξ for each characteristic root; Step 4: According to the minimum characteristic parameter ξ of the characteristic root corresponding to each group of parameters in the speed control system obtained in step 3, draw the curve of the characteristic parameter ξ changing with the parameters K _p and K _i of the governor. When the characteristic root is When the complex conjugate root is used, ξ is the damping ratio of the second-order link; when the characteristic root is a non-zero real root, ξ takes ±1, if the real root is less than zero, ξ is 1, and if the real root is greater than zero Then ξ is -1; when the system is stable, all the characteristic roots of the system have negative real parts, and at the same time, it can be deduced that the characteristic parameters ξ of all characteristic roots take positive values, so according to the characteristic parameters ξ presented by the controlled object Determine the value range of the control parameters that make the system stable with the change image of each group of control parameters; Step 5: According to the mathematical model of the steam turbine speed control system established in the above steps 1 to 3 and the change trend diagram drawn in step 4, the trial and error method is used for fine-tuning to set the optimal control parameters that are actually applicable to the unit.