CN104063584B - Control parameter setting method for steam turbine speed governing system - Google Patents

Abstract

The invention relates to a control parameter setting method for a steam turbine speed governing system. The control parameter setting method comprises the following steps: (1) building a mathematical model and a transfer function of the steam turbine speed governing system provided with a stand-alone infinitely great system in a power network model; (2) when the control parameters Ki and Kp change within the range of 0-10, unceasingly working out the numerical solutions of the characteristic roots of the transfer function of the system under the given parameters, and the expression of the characteristic root is s=A+Bj; (3) working out the value of the characteristic parameter Xi of each group of the characteristic roots, and obtaining the minimum value of Xi; (4) drawing the tendency chart of the minimum value of the characteristic parameter Xi of each group varying along with the control parameters Ki and Kp; (5) judging whether the system is stabilized on the basis of the positive or negative values of the characteristic parameter Xi, acquiring the value range of the control parameters that stabilize the system, and conducting fine adjustment by adopting the cut-and-try method to set up the optimal control parameter that is veritably practical to a machine set. The control parameter setting method has significance on further normalizing the parameter arrangement of a steam turbine control system and reducing the low-frequency oscillation of the system.

Description

A kind of turbine regulating system control parameter setting method

Technical field

The invention belongs to the control method of steam turbine speed control and power network safety operation, particularly in order to improve power train System dynamic stability, prevent the method to turbine controller parameter tuning in electricity grid oscillating field.

Background technology

In recent years, increase year by year with Electricity Demand, the scale of power system is increasing, on main force's transmission line of electricity The power of conveying is also continuously increased, and the service condition of whole power system becomes increasingly severe, and low-frequency oscillation happens occasionally, Become one of key factor of restriction dominant eigenvalues transmission and interconnected network safe and stable operation.Due in recent years several by electricity The low-frequency oscillation accident that source causes is so that mains side low-frequency oscillation research gradually obtains the attention of people.Many experts pass through Several oscillation of power events of south electric network are analyzed, show that low-frequency oscillation presence unstable to steam turbine side governing system is related Property.

By the analysis of principle that steam turbine is done work, in conjunction with the resonance mechanism of low-frequency oscillation, analyze steam turbine side and cause by force The possible cause of urgent oscillation of power, shows the pressure fluctuation of steam turbine, and timing steam gate swings and all may cause the strong of electrical network Urgent low-frequency oscillation.Although forced power oscillation mechanism can explain some low-frequency oscillations, in the middle of conventional research, For simulating Forced disturbance source, it is all often directly artificially to addition of a cycle disturbance in system link, this and actual feelings Condition does not correspond.There are some researches show if the setting of mains side some control parameters is improper, a negative damping can be provided to system Torque, thus reducing system damping, causes the negative damping vibration of electrical network.Some experts are using the mould of the governing system simplifying Type, analyzes the impact to electrical network damping characteristic for the major parameter it is indicated that proportionality coefficient setting is improper in controller, can lead to once Frequency modulation loop produces effect of negative damping, thus producing electricity grid oscillating after putting into.But controller parameter change can be to system Which kind of impact is stability produce, and how to analyze the zone of reasonableness providing controller parameter, mesh based on stability of power system The research of front still shortage.

Content of the invention

For solving the zone of reasonableness of the reasonable set with regard to controller parameter recited above, the present invention provides a kind of steamer Machine governor system control parameter tuning method, purpose be the setting of further specification steam turbine control system parameter, reduce The generation of system low frequency oscillation, safeguards stablizing of power system.

To achieve these goals, realize as follows by step for the present invention：

Step 1：Set up the mathematical model including the turbine regulating system of one machine infinity bus system during electric network model, Obtain mathematical model and the various parameters of controlled device using object model identification module corresponding in existing working condition system, respectively The transmission function of the mathematical model of turbine regulating system when the transmission function between parameter that is, inclusion electric network model is as follows Shown in formula：

$-{\mathrm{\ΔP}}_m=\left(\frac{1}{(1+T_{1}s)\mathrm{\δ}}\right(1+G_{pid})+\frac{1}{s}{G}_1{G}_{pid})G_e{G}_t\mathrm{\Δ}\mathrm{\ω};$

$({\mathrm{\ΔP}}_m-{\mathrm{\ΔP}}_e)\frac{1}{T_{\mathrm{\σ}}s}=\mathrm{\Δ}\mathrm{\ω};$

${\mathrm{\ΔP}}_e=(K_1-\frac{K_2{K}_3\[K_4(1+{\mathrm{sT}}_R+K_5{K}_A)\]}{s^2{T}_3{T}_R+s(T_3+T_R)+1+K_3{K}_6{K}_A})\mathrm{\Δ}\mathrm{\δ};$

$\⇒\frac{{\mathrm{\ΔP}}_m}{{\mathrm{\Δ\ω}}_r}=\frac{G_2(1+G_{pid})G_e{G}_t}{1+G_3{G}_4};$

K in above-mentioned formula₁, K₂, K₃, K₄, K₅, K₆It is respectively proportionality coefficient, K_AFor exciter proportionality coefficient, s is through Laplace Differential operator after conversion, δ is the difference coefficient of rotating speed, and Δ ω is rotating speed angular velocity deviator, Δ ω_rFor rotating speed disturbed value, Δ δ For generator's power and angle deviation, Δ P_mFor mechanical output increment, Δ P_eFor electromagnetic power increment, T₁Represent that the rotating speed transducer time is normal Number, T₃For energized circuit time constant, T_RFor voltage sensor time constant, T_σFor the time constant of turbine rotor, G₁For list The transmission function of machine Infinite bus system, G₂For the one order inertia transmission function of the rotating speed transducer in control system, G_eWatch for electro-hydraulic Take the transmission function of device, G_tFor the transmission function of tandem compound, single reheat steam turbine, G_pidFor the transmission function of controller, G₃For Turbine regulating system ground transmission function, G₄Be set up for reduced form there is no corresponding physical meaning.Wherein G₁、G₂、 G₃、G₄It is defined as：

$G_1=(K_1-\frac{K_2{K}_3\[K_4(1+{\mathrm{sT}}_R+K_5{K}_A)\]}{s^2{T}_3{T}_R+s(T_3+T_R)+1+K_3{K}_6{K}_A});$

$G_2=\frac{1}{(1+T_{1}s)};$

$G_3=\left(\frac{1}{(1+T_{1}s)\mathrm{\δ}}\right(1+G_{pid})+\frac{1}{s}{G}_1{G}_{pid})G_e{G}_t;$

$G_4=\frac{1}{T_{\mathrm{\σ}}s+G_1\frac{1}{s}};$

Step 2：Transmission function to controllerIn governor system control parameter K_pAnd K_i0～10 In the range of multigroup different array is set, obtain the characteristic root of the transmission function of controlled device under each group array parameter respectively, lead to Cross the numerical solution asking for that numerical method asks for characteristic root, and then ask for the span of the control parameter of governing system, K in formula_i For governing system integration control parameter, K_pFor ratio control parameter, K_dFor differential control parameter, s is differential operator；

The transmission function of analysis controlled device, the characteristic root obtaining controlled device transmission function can be the non-zero root on real axis And conjugate complex is several, is represented with following formula：

S=A+Bj,

In formula, A and B is respectively real part and the imaginary part of characteristic root；

For order Oscillating link, its characteristic root is that a pair of conjugate complex is several, and expression formula is as follows：

$s_{1,2}=-{\mathrm{\ξ\ω}}_n\±{\mathrm{j\ω}}_n\sqrt{1-{\mathrm{\ξ}}^2},$

Wherein characteristic parameter ξ is damping ratio, ω_nFor undamped oscillation frequency；

Step 3：Obtain the size of the characteristic parameter ξ of every stack features root, and obtain the minimum ξ of its intermediate value, by above-mentioned formula Understand,

A=- ξ ω_n,

$B=\±{\mathrm{j\ω}}_n\sqrt{1-{\mathrm{\ξ}}^2},$

By A, B in above-mentioned equation as it is known that simultaneous equations try to achieve damping ratio

$\mathrm{\ξ}=\frac{-A}{\sqrt{A^2+B^2}},$

When knowing that ξ is less than zero by above formula, system features root real part is not negative, and second-order system is unstable, the damping of second-order system Ratio can reflect whether stablizing of second-order system, when whether the turbine regulating system considering electric network model in analysis is stablized, right Each characteristic root asks for its characteristic parameter ξ；

Step 4：Minimal characteristic parameter ξ according to the corresponding characteristic root of each group parameter in the governing system tried to achieve in step 3 Draw parameter K with speed regulator for the characteristic parameter ξ_p、K_iThe curve of change, when this feature root is Conjugate complex roots, ξ is its second order loop The damping ratio of section；When this feature root is non-zero real root, ξ then takes ± 1, if it is 1 that this real root is less than zero, ξ, if this real root is more than Zero ξ is -1；When the system is stable, then the whole characteristic root of system is respectively provided with negative real part, can release all characteristic roots simultaneously Characteristic parameter ξ all takes on the occasion of the characteristic parameter ξ that thus can be presented according to controlled device is with the modified-image of each group control parameter Determine the span of the control parameter making system stability；

Step 5：The mathematical model of the turbine regulating system set up according to abovementioned steps 1 to 3 and step 4 are drawn Changing trend diagram, is finely adjusted using trial and error procedure, adjusts out and is really practically applicable to the optimal control parameter of unit.

The present invention proposes a kind of setting method of the turbine regulating system control parameter based on stability of power system, Because the model of the method contains electrical network side system, even more like with real model, thus relatively with the conventional side of adjusting Method greatly reduces the zone of reasonableness of the controller parameter not leading to system unstability；And have very strong practical, will not picture Former setting method although being stable during unit operation, but it is possible that vibration during multiple unit operation；This is for entering one Step specification steam turbine control system parameter setting, the generation tool reducing low frequency oscillations is of great significance.

Brief description

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

Fig. 2 is the structure chart of the embodiment of governor system control parameter tuning method of the present invention；

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

Fig. 4 is the electrohydraulic servomechanism model schematic of embodiment of the present invention；

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

Fig. 6 is the one machine infinity bus system model schematic of embodiment of the present invention；

Fig. 7 is the changing trend diagram with governor control parameter for the characteristic parameter ξ.

Specific embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.

Fig. 3 is the phantom of control system, and after ignoring nonlinear element, its transmission function isIts Middle T₁Represent rotating speed transducer time constant, value 0.02；Speed governing dead-band value 0.025；Speed governing dead-band link K below Represent primary frequency modulation difference coefficient (i.e. speed diversity factor), value is 20；K_p、K_i、K_dIt is respectively the ratio of load governor PID Amplification coefficient, integration time constant, derivative time constant, value is 1,0.05,0 respectively；K₂Represent that the rotating speed feedforward is amplified Coefficient, it is rotating speed transducer that parameter is taken as in 1, Fig. 31.2 is PID load governor, P_refFor given active power, P_eFor electricity The feedback power of net side.

Fig. 4 is the phantom of electrohydraulic servomechanism, and its transmission function is Wherein P_cvFor pitch instruction；K_p1、K_i1、K_d1It is respectively valve positioner pid parameter, value is 9,0,0 respectively；Tc and To is oil Motivation opens and closes time constant, and parameter is taken as 1.24 and 1.33 respectively；Wherein T₂Represent that the Linear displacement transducer time is normal Number, in Fig. 4,3 is valve PID controller, and 4 is valve on-off controller, and 5 open for servomotor, close delay link, and 6 is that oil is dynamic Machine, 7 is linear displacement transducers, and parameter is taken as 0.02.

Fig. 5 is the phantom of a reheating turbine, and its transmission function isWherein P_GVFor pitch aperture；P_MMechanical work for output Rate；Time constant T_ch、T_rhAnd T_coCorresponding expression by steam chest and air inlet duct, reheater and intersects produced by piping Time delay, parameter is taken as 0.1,12,1；F_hp、F_ipAnd F_lpRepresent share in overall mechanical power for the high, medium and low cylinder pressure amount of work, take It is worth for 0.32,0.68,0 (it is that mesolow cylinder is regarded as an entirety that low pressure (LP) cylinder work done factor takes 0)；λ represents that high pressure cylinder power is natural Toning coefficient, parameter, value is high steam volume in 0.9, Fig. 58, and 9 is reheated steam volume, and 10 is low pressure UNICOM steam Volume.

Fig. 6 is one machine infinity bus system phantom, and after ignoring nonlinear element, its transmission function isWherein K₁, K₂, K₃, K₄, K₅, K₆It is respectively proportionality coefficient；Δ w_rFor rotating speed disturbed value, Δ δ is generator's power and angle deviation；19ΔT_mFor mechanical output increment；18ΔT_eFor electromagnetic power increment； Δψ_fdFor energized circuit magnetic linkage increment；ΔE_fdFor exciter output voltage increment；U_PSSFor power system stabilizer, PSS output signal； T₃For energized circuit time constant；T_RFor voltage sensor time constant；K_AFor exciter proportionality coefficient, Δ V_refIt is with reference to output Voltage, Δ V₁Voltage sensor output voltage.Its parameter all takes representative value, and in Fig. 6,11 is exciter, and 12 is rotating speed with power Transmission function.13 is the transmission function with phase angle for the generator speed, and 14 is voltage sensor, and 15 is energized circuit.

Shown in the schematic flow sheet of method of governor system control parameter tuning as of the present invention in Fig. 1, in the embodiment of the present invention Governor system control parameter tuning method include step：

Step 1：Set up the mathematical model including the turbine regulating system of one machine infinity bus system during electric network model, Set up the phantom figure of current embodiment, the process of the mathematical model of identification existing object is usually to utilize existing operating mode system Corresponding object model identification module in system obtains mathematical model and the various parameters of controlled device, between each major parameter Transmission function that is, include electric network model when turbine regulating system mathematical model, be shown below：

$-{\mathrm{\ΔP}}_m=\left(\frac{1}{(1+T_{1}s)\mathrm{\δ}}\right(1+G_{pid})+\frac{1}{s}{G}_1{G}_{pid})G_e{G}_t\mathrm{\Δ}\mathrm{\ω};$

$({\mathrm{\ΔP}}_m-{\mathrm{\ΔP}}_e)\frac{1}{T_{\mathrm{\σ}}s}=\mathrm{\Δ}\mathrm{\ω};$

${\mathrm{\ΔP}}_e=(K_1-\frac{K_2{K}_3\[K_4(1+{\mathrm{sT}}_R+K_5{K}_A)\]}{s^2{T}_3{T}_R+s(T_3+T_R)+1+K_3{K}_6{K}_A})\mathrm{\Δ}\mathrm{\δ};$

$\⇒\frac{{\mathrm{\ΔP}}_m}{{\mathrm{\Δ\ω}}_r}=\frac{G_2(1+G_{pid})G_e{G}_t}{1+G_3{G}_4};$

K in above-mentioned formula₁, K₂, K₃, K₄, K₅, K₆It is respectively proportionality coefficient, K_AFor exciter proportionality coefficient, s is through Laplace Differential operator after conversion, δ is the difference coefficient of rotating speed, and Δ ω is rotating speed angular velocity deviator, Δ ω_rFor rotating speed disturbed value, Δ δ For generator's power and angle deviation, Δ P_mFor mechanical output increment, Δ P_eFor electromagnetic power increment, T₁Represent that the rotating speed transducer time is normal Number, T₃For energized circuit time constant, T_RFor voltage sensor time constant, T_σFor the time constant of turbine rotor, G₁For list The transmission function of machine Infinite bus system, G₂For the one order inertia transmission function of the rotating speed transducer in control system, G_eWatch for electro-hydraulic Take the transmission function of device, G_tFor the transmission function of tandem compound, single reheat steam turbine, G_pidFor the transmission function of controller, G₃For Turbine regulating system ground transmission function, G₄Be set up for reduced form there is no corresponding physical meaning.

Wherein G₁、G₂、G₃、G₄It is defined as：

$G_1=(K_1-\frac{K_2{K}_3\[K_4(1+{\mathrm{sT}}_R+K_5{K}_A)\]}{s^2{T}_3{T}_R+s(T_3+T_R)+1+K_3{K}_6{K}_A});$

$G_2=\frac{1}{(1+T_{1}s)};$

$G_3=\left(\frac{1}{(1+T_{1}s)\mathrm{\δ}}\right(1+G_{pid})+\frac{1}{s}{G}_1{G}_{pid})G_e{G}_t;$

$G_4=\frac{1}{T_{\mathrm{\σ}}s+G_1\frac{1}{s}};$

Step 2：Transmission function to following formula controllerIn governor system control parameter K_pAnd K_i0 Multigroup different array is set in the range of～10, obtains the feature of the transmission function of controlled device under each group array parameter respectively Root, due to this system features equation exponent number higher it is impossible to try to achieve each parameter in governing system by way of asking for analytic solutions Span, and the numerical solution of characteristic root can only be asked for by asking for numerical method, and then ask for the control parameter of governing system Span.

Because high order system all can turn to the combination of zeroth order, single order, two-step element, oscillating component is mainly second order therein Oscillation element.By analyzing the transmission function of controlled device it is known that it does not have zeroth order link, then the transmission function of controlled device Characteristic root can be the non-zero root on real axis and conjugate complex is several, can be represented with following formula：

S=A+Bj,

In formula, A and B is respectively real part and the imaginary part of characteristic root；

For order Oscillating link, its characteristic root is that a pair of conjugate complex is several, and expression formula is as follows：

$s_{1,2}=-{\mathrm{\ξ\ω}}_n\±{\mathrm{j\ω}}_n\sqrt{1-{\mathrm{\ξ}}^2},$

Wherein characteristic parameter ξ is damping ratio, ω_nFor undamped oscillation frequency.

Step 3：Obtain the size of the characteristic parameter ξ of every stack features root, and obtain the minimum ξ of its intermediate value, by above-mentioned formula Understand,

A=- ξ ω_n,

$B=\±{\mathrm{j\ω}}_n\sqrt{1-{\mathrm{\ξ}}^2},$

By A, B in above-mentioned equation as it is known that simultaneous equations can be tried to achieve by damping ratio

$\mathrm{\ξ}=\frac{-A}{\sqrt{A^2+B^2}},$

When knowing that ξ is less than zero by above formula, system features root real part is not negative, and second-order system is unstable, so second-order system Damping ratio can reflect whether stablizing of second-order system.So considering whether the turbine regulating system of electric network model is steady in analysis Regularly, each characteristic root can be asked for its characteristic parameter ξ.

Step 4：Minimal characteristic parameter ξ according to the corresponding characteristic root of each group parameter in the governing system tried to achieve in step 3 Draw parameter K with speed regulator for the characteristic parameter ξ_p、K_iThe curve of change, as shown in Figure 6.When this feature root is Conjugate complex roots, ξ is the damping ratio of its two-step element；When this feature root is non-zero real root, ξ then takes ± 1, if it is 1 that this real root is less than zero, ξ, if It is -1 that this real root is more than zero ξ.When the system is stable, then the whole characteristic root of system is respectively provided with negative real part, can release institute simultaneously The characteristic parameter ξ having characteristic root all take on the occasion of.So the characteristic parameter ξ that can be presented according to controlled device is with each group control parameter Modified-image determine make system stability control parameter span.

Step 5：The controlled device phantom being had built up by step before, is carried out using trial and error procedure within this range Fine setting, adjusts out and is really practically applicable to the optimal control parameter of unit.

The trial and error procedure taken in embodiment of the present invention be with reference to the accompanying drawings in 7 characteristic parameter ξ with governor control parameter Changing trend diagram, makes integration control parameter K in governing system_iTake a numerical value between 0～3.1, and ensure its constant feelings Ratio control parameter K under condition, to governing system_pSlightly changed in the range of 0～4, by the emulation knot of viewing system Fruit chooses optimal control system array parameter.

Claims (1)

1. a kind of turbine regulating system control parameter setting method is it is characterised in that comprise the steps：

Step 1：Set up the mathematical model including the turbine regulating system of one machine infinity bus system during electric network model, utilize In existing working condition system, corresponding object model identification module obtains the mathematical model of controlled device and each parameter, each parameter it Between transmission function that is, include electric network model when the mathematical model of turbine regulating system transmission function, as following formula institute Show：

$-{\mathrm{\ΔP}}_m=\left(\frac{1}{(1+T_{1}s)\mathrm{\δ}}\right(1+G_{pid})+\frac{1}{s}{G}_1{G}_{pid})G_e{G}_t\mathrm{\Δ}\mathrm{\ω};$

$({\mathrm{\ΔP}}_m-{\mathrm{\ΔP}}_e)\frac{1}{T_{\mathrm{\σ}}s}=\mathrm{\Δ}\mathrm{\ω};$

${\mathrm{\ΔP}}_e=(K_1-\frac{K_2{K}_3\[K_4(1+{\mathrm{sT}}_R+K_5{K}_A)\]}{s^2{T}_3{T}_R+s(T_3+T_R)+1+K_3{K}_6{K}_A})\mathrm{\Δ}\mathrm{\δ};$

$\⇒\frac{{\mathrm{\ΔP}}_m}{{\mathrm{\Δ\ω}}_r}=\frac{G_2(1+G_{pid})G_e{G}_t}{1+G_3{G}_4};$

K in above-mentioned formula₁, K₂, K₃, K₄, K₅, K₆It is respectively proportionality coefficient, K_AFor exciter proportionality coefficient, s is after Laplace transformation Differential operator, δ be rotating speed difference coefficient, Δ ω be rotating speed angular velocity deviator, Δ ω_rFor rotating speed disturbed value, Δ δ is to generate electricity Machine power angle deviation, Δ P_mFor mechanical output increment, Δ P_eFor electromagnetic power increment, T₁Represent rotating speed transducer time constant, T₃For Energized circuit time constant, T_RFor voltage sensor time constant, T_σFor the time constant of turbine rotor, G₁Infinite for unit Big system transter, G₂For the one order inertia transmission function of the rotating speed transducer in control system, G_eFor electrohydraulic servomechanism Transmission function, G_tFor the transmission function of tandem compound, single reheat steam turbine, G_pidFor the transmission function of controller, G₃For steam turbine Governing system ground transmission function, G₄Be set up for reduced form there is no corresponding physical meaning；Wherein G₁、G₂、G₃、G₄Definition For：

$G_1=(K_1-\frac{K_2{K}_3\[K_4(1+{\mathrm{sT}}_R+K_5{K}_A)\]}{s^2{T}_3{T}_R+s(T_3+T_R)+1+K_3{K}_6{K}_A});$

$G_2=\frac{1}{(1+T_{1}s)};$

$G_3=\left(\frac{1}{(1+T_{1}s)\mathrm{\δ}}\right(1+G_{pid})+\frac{1}{s}{G}_1{G}_{pid})G_e{G}_t;$

$G_4=\frac{1}{T_{\mathrm{\σ}}s+G_1\frac{1}{s}};$

Step 2：Transmission function to controllerIn governor system control parameter K_pAnd K_iIn 0～10 scope The multigroup different array of interior setting, obtains the characteristic root of the transmission function of controlled device under each group array parameter, respectively by asking Take numerical method to ask for the numerical solution of characteristic root, and then ask for the span of the control parameter of governing system, K in formula_iFor adjusting Speed system integration control parameter, K_pFor ratio control parameter, K_dFor differential control parameter, s is differential operator；

The transmission function of analysis controlled device, obtain controlled device transmission function characteristic root can for the non-zero root on real axis and Conjugate complex is several, is represented with following formula：

S=A+Bj,

In formula, A and B is respectively real part and the imaginary part of characteristic root；

For order Oscillating link, its characteristic root is that a pair of conjugate complex is several, and expression formula is as follows：

$s_{1,2}=-{\mathrm{\ξ\ω}}_n\±{\mathrm{j\ω}}_n\sqrt{1-{\mathrm{\ξ}}^2},$

Wherein characteristic parameter ξ is damping ratio, ω_nFor undamped oscillation frequency；

Step 3：Obtain the size of the characteristic parameter ξ of every stack features root, and obtain the minimum ξ of its intermediate value, as shown from the above formula,

A=- ξ ω_n,

$B=\±{\mathrm{j\ω}}_n\sqrt{1-{\mathrm{\ξ}}^2},$

By A, B in above-mentioned equation as it is known that simultaneous equations try to achieve damping ratio

$\mathrm{\ξ}=\frac{-A}{\sqrt{A^2+B^2}},$

When knowing that ξ is less than zero by above formula, system features root real part is not negative, and second-order system is unstable, and the damping ratio of second-order system can To reflect whether stablizing of second-order system, when whether the turbine regulating system of analysis consideration electric network model is stablized, to each Characteristic root asks for its characteristic parameter ξ；

Step 4：Minimal characteristic parameter ξ according to the corresponding characteristic root of each group parameter in the governing system tried to achieve in step 3 is drawn Characteristic parameter ξ is with parameter K of speed regulator_p、K_iThe curve of change, when this feature root is Conjugate complex roots, ξ is its two-step element Damping ratio；When this feature root is non-zero real root, ξ then takes ± 1, if it is 1 that this real root is less than zero, ξ, if this real root is more than zero, ξ For -1；When the system is stable, then the whole characteristic root of system is respectively provided with negative real part, can release the feature ginseng of all characteristic roots simultaneously Number ξ all takes on the occasion of thus can be determined with the modified-image of each group control parameter according to the characteristic parameter ξ that controlled device is presented makes The span of the control parameter of system stability；

Step 5：The mathematical model of the turbine regulating system set up according to abovementioned steps 1 to 3 and the change of step 4 drafting Trendgram, is finely adjusted using trial and error procedure, adjusts out and is really practically applicable to the optimal control parameter of unit.