CN112952861B - Additional virtual double-PSS control method for active support type new energy unit - Google Patents

Abstract

The invention discloses an additional virtual double PSS control method for an active support type new energy unit, and particularly relates to an additional virtual double PSS control method for an active support type new energy unit, which comprises the following steps: the method comprises the steps of establishing an active support type VSC infinite system linearization model, analyzing an oscillation mechanism of the active support type new energy VSC, designing an active support type VSC virtual double PSS, introducing a virtual double PSS link into a control loop on the basis of active support control of a new energy power grid, compensating a damping torque of a virtual excitation regulator, improving damping characteristics, effectively inhibiting power oscillation, improving system stability, and enabling the double PSS to exert the maximum advantages of the double PSS through parameter optimization of an excitation PSS and an angle PSS.

Description

Additional virtual dual PSS control method for actively supported new energy units

technical field

The invention belongs to the technical field of electromechanical oscillation of a new generation energy power system, and in particular relates to an additional virtual dual PSS control method for actively supported new energy units.

Background technique

At present, the excessive use of fossil energy has aggravated environmental pollution and caused a series of problems such as the greenhouse effect. Therefore, it is urgent to improve the existing energy structure and vigorously develop clean energy to replace fossil energy. The centralized connection of large-scale new energy stations to the power grid is a typical feature of the new generation power system. However, a high proportion of new energy grid-connected operation will replace the traditional units that rely on the rotating shaft to provide inertia support, resulting in a decrease in the overall rigid inertia of the system, affecting the safe operation of the power system and the reliable supply of electric energy. In this regard, the active support type new energy unit can simulate the output characteristics of traditional generators, provide flexible inertia for the system, and improve the anti-disturbance ability of the system. Since the active support type new energy unit simulates the electromechanical transient characteristics of the traditional synchronous generator, the power oscillation problem of the traditional synchronous generator is also introduced into the active support type new energy unit.

Contents of the invention

The purpose of the present invention is to provide an additional virtual double PSS control method for actively supported new energy units, which solves the power oscillation problem caused by the grid connection of actively supported new energy units in the new generation power system.

The technical solution adopted in the present invention is an additional virtual double PSS control method for actively supported new energy units, which is specifically implemented according to the following steps:

Step 1. Establish the linearization model of the active support type VSC infinite system;

Step 2. Design the active support type VSC virtual double PSS;

Step 3. Optimizing the virtual dual PSS parameters of the active support VSC.

The present invention is also characterized in that:

The specific process of step 1 is:

Step 1.1, constructing the electromechanical transient model of the actively supported VSC;

Step 1.2. Deriving the Heffron-Phillips model of the actively supported VSC.

The specific process of step 1.1 is:

According to the second-order rotor motion equation, first-order excitation circuit equation and excitation voltage regulation equation of the synchronous generator, the electromechanical transient model of the actively supported VSC is constructed:

In formula (1): P _m is the mechanical power, P _e is the electromagnetic power, H is the virtual inertia, D is the damping coefficient, δ is the power angle of the generator, Δω is the deviation between the rated speed and the actual speed, E _q ′ is the temporary State electromotive force, E _q is the no-load electromotive force, E _fd is the forced no-load electromotive force, E _fd ′ is the excitation electromotive force output by the automatic voltage regulator, ΔU _t is the voltage deviation value of the inverter terminal, K _A is the automatic voltage regulator Gain, T _A is the time constant of the automatic voltage regulator, T _d0 ′ is the time constant of the excitation winding of the synchronous generator, ω ₀ is the rated angular frequency, dω/dt is the change rate of the angular frequency, dδ/dt is the change rate of the power angle rate of change;

In formula (1), the expressions of electromagnetic power P _e and no-load electromotive force E _q are:

In formula (2): U _d , U _q are the d-axis component and q-axis component of the infinite bus voltage U _b , I _d , I _q are the d-axis component and q-axis component of the line current I _t , X′ _d is the direct axis transient reactance, X _d is the direct axis synchronous reactance.

The specific process of step 1.2 is:

The virtual impedance model for constructing the actively supported VSC is:

U _td and U _tq in formula (3) are the d-axis component and q-axis component of VSC terminal voltage U _t ;

The voltage equation of the transmission line of the actively supported VSC infinite system is:

U _t =jX _t I _t +U _b (4)

In formula (4), X _t is the line reactance, I _t is the line current, U _b is the infinite bus voltage, U _t is the inverter terminal voltage;

Obtained by formula (1)-(4):

By linearizing equation (5) at the steady-state operating point and simplifying it, we get:

Among them, the coefficients K ₁ ~ K ₆ are constants related to the system structure, parameters and operating conditions;

Putting formula (6) into formula (1), the Heffron-Phillips model of actively supported VSC is obtained:

In step 2, the design of the virtual double PSS of the actively supported VSC includes the design of the virtual excitation PSS and the virtual angle PSS of the electromagnetic torque of the synchronous motor. The specific process is as follows:

Construct virtual PSS according to the Heffron-Phillips model of actively supported VSC;

The virtual excitation PSS design process is as follows:

Δω is used as the control signal, so that the control signal is fed back to the excitation circuit after the transfer function G' _pss (s), and an additional electromagnetic torque ΔT' _pss is generated;

Then the additional electromagnetic torque ΔT′ _pss provided by the virtual excitation PSS is:

The virtual angle PSS design process is:

The correction amount Δδ _pss of the power angle Δδ is introduced as an additional control, where Δδ _pss = G″ _pss (s) Δω, so that the corrected power angle Δδ = Δδ _pss + Δδ ₀ , and an additional electromagnetic torque ΔT is generated in the excitation circuit " _pss , the additional electromagnetic torque ΔT " _pss of virtual angle PSS is:

The specific process of step 3 is: optimize the virtual excitation PSS parameters and virtual angle PSS parameters in the virtual dual PSS of the active support VSC;

Optimization of virtual excitation PSS parameters:

Suppose the value of the control signal Δω phase correction is Δu _pss , that is, Δu _pss = Δω*G′ _pss (s), the transfer function from Δu _pss to ΔT′ _pss is F′ _pss (s), the formula is as follows:

Let the damping coefficient provided by the virtual excitation PSS be D′ _pss , that is

D' _pss = G' _pss (s) F' _pss (s) (14)

Express F′ _pss (s) and G′ _pss (s) as follows:

为传递函数F′_pss(s)的相位角，γ′为传递函数G′_pss(s)的相位角；In the formula,

Be the phase angle of transfer function F' _pss (s), γ ' is the phase angle of transfer function G' _pss (s);

According to the phase compensation method, there are

In the formula, T′ _pssd is the additional damping torque provided by the virtual excitation PSS, and T′ _psss is the additional synchronous torque provided by the virtual excitation PSS;

which is

Set the transfer function G′ _pss (s) as a proportional link and a lead-lag link, expressed as:

In the formula, T ₁ ~ T ₄ all represent the time constant of the lead-lag link, K′ ₁ and K′ ₂ are the parameter setting values of the virtual excitation PSS;

Assuming that the virtual excitation PSS provides a positive damping torque, it can be obtained from (16):

Given the values of T ₁ and T ₃ , calculate T ₂ , T ₄ , K′ ₁ , K′ ₂ according to formula (19), and obtain the transfer function G′ _pss after parameter optimization according to formula (15) and (18) (s);

Optimization of virtual angle PSS parameters:

Assuming that the virtual angle PSS provides positive pure damping torque, ΔT″ _pss is the electromagnetic torque provided by the virtual angle PSS, the correction amount Δδ _pss of the power angle Δδ is the output stability control signal of the virtual angle PSS, and the value provided by the virtual angle PSS The electromagnetic torque is ΔT″ _pss , and F″ _pss (s) is the transfer function from _Δδpss to ΔT″ _pss , then:

ΔT″ _pss = F″ _pss (s) Δδ _pss (21)

Let the phase compensation of the transfer function G″ _pss (s) be the phase of the transfer function F″ _pss (s), set the transfer function G″ _pss (s) as a proportional link and a lead-lag link, expressed as:

In the formula, T′ ₁ ~ T′ ₄ all represent the time constant of the lead-lag link, K″ ₁ and K″ ₂ are the parameter setting values of the virtual angle PSS;

Similarly, the virtual excitation PSS can be obtained

为传递函数F″_pss(s)的相位角，γ″为传递函数G″_pss(s)的相位角；In the formula,

Be the phase angle of transfer function F " _pss (s), γ " be the phase angle of transfer function G " _pss (s);

Given the values of T′ ₁ and T′ ₃ , calculate T′ ₂ , T′ ₄ , K′ ₁ , K′ ₂ according to formula (23), and obtain the transfer function G″ _pss after parameter optimization according to formula (22) (s).

The beneficial effects of the present invention are:

The invention is oriented to the additional virtual dual PSS control method of the active support type new energy unit, and the proposed additional virtual dual PSS control method can provide an additional damping torque through the virtual dual PSS control strategy when the system is disturbed and generates power oscillation , so as to suppress power oscillation and improve the anti-disturbance ability of the new generation energy power system.

Description of drawings

Fig. 1 is a block diagram of the electromechanical transient model of the active support type new energy unit of the present invention;

Fig. 2 is the active support type VSC infinity system diagram of the present invention;

Fig. 3 is the Heffron-Phillips model of active support type VSC of the present invention;

Fig. 4 is the transfer function block diagram from Δδ to ΔT _e of the present invention;

Fig. 5 is the infinite electromagnetic torque vector diagram of active support type VSC of the present invention;

Fig. 6 is the damping control block diagram of the additional virtual excitation PSS of the present invention;

Fig. 7 is the transfer function block diagram from Δu _pss to ΔT' _pss of the present invention;

Fig. 8 is the electromagnetic torque vector diagram of introducing virtual excitation PSS of the present invention;

Fig. 9 is the damping control block diagram of additional virtual angle PSS of the present invention;

Fig. 10 is the transfer function block diagram from Δδ _pss to ΔT " _pss of the present invention;

Fig. 11 is the electromagnetic torque vector diagram introducing virtual angle PSS of the present invention;

Fig. 12 is the damping control block diagram of the additional double PSS of the present invention;

Fig. 13 is the active support type VSC infinite system frequency response waveform of the present invention;

Fig. 14 is the power response waveform of the active support type VSC infinite system of the present invention.

Detailed ways

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

The present invention is oriented to an additional virtual double PSS control method for active support type new energy units, which is specifically implemented according to the following steps:

Step 1. In order to analyze the power oscillation problem of the power system, a linearized model of the active support type VSC infinite system is established; the specific process of step 1 is as follows:

Step 1.1. According to the second-order rotor motion equation of the synchronous generator, the first-order excitation circuit equation and the excitation voltage regulation equation, the active support type VSC electromechanical transient model is obtained. The control block diagram is shown in Figure 1, and the formula is as follows:

In formula (1): P _m is the mechanical power, P _e is the electromagnetic power, H is the virtual inertia, D is the damping coefficient, δ is the power angle of the generator, Δω is the deviation between the rated speed and the actual speed, E _q ′ is the temporary State electromotive force, E _q is the no-load electromotive force, E _fd is the forced no-load electromotive force, E _fd ′ is the excitation electromotive force output by the automatic voltage regulator, ΔU _t is the voltage deviation value of the inverter terminal, K _A is the automatic voltage regulator Gain, T _A is the time constant of the automatic voltage regulator, T _d0 ′ is the time constant of the excitation winding of the synchronous generator, ω ₀ is the rated angular frequency, dω/dt is the change rate of the angular frequency, dδ/dt is the change rate of the power angle rate of change;

In formula (1), the expressions of electromagnetic power P _e and no-load electromotive force E _q are:

In formula (2): U _d , U _q are the d-axis component and q-axis component of the infinite bus voltage U _b , I _d , I _q are the d-axis component and q-axis component of the line current I _t , X′ _d is the direct axis transient reactance, X _d is the direct axis synchronous reactance.

Step 1.2, constructing the virtual impedance model of the actively supported VSC is:

U _td and U _tq in formula (3) are the d-axis component and q-axis component of VSC terminal voltage U _t ;

The actively supported VSC infinite system is shown in Figure 2, and the voltage equation of its transmission line is:

U _t =jX _t I _t +U _b (4)

In formula (4), X _t is the line reactance, I _t is the line current, U _b is the infinite bus voltage, U _t is the inverter terminal voltage;

Obtained by formula (1)-(4):

By linearizing equation (5) at the steady-state operating point and simplifying it, we get:

Among them, the coefficients K ₁ ~ K ₆ are constants related to the system structure, parameters and operating conditions;

Putting formula (6) into formula (1), the Heffron-Phillips model of actively supported VSC is shown in Figure 3:

The state space expression of the actively supported VSC infinite system is:

Step 2. In order to reduce the power oscillation problem caused by negative damping torque and improve the system robustness, design the active support type VSC virtual double PSS; the design of the active support type VSC virtual double PSS includes the design of the virtual excitation of the electromagnetic torque of the synchronous motor PSS and virtual angle PSS,

Figure 4 is a block diagram of the transfer function from Δδ to ΔT _e , which can be obtained from Figure 4, the electromagnetic torque provided by the actively supported VSC is

According to formula (9), the electromagnetic torque vector diagram of the actively supported VSC can be drawn, as shown in Fig. 5. Since the _K4 branch in Fig. 4 does not produce negative damping torque, in order to simplify the analysis, Fig. 5 does not consider the influence of the _K4 branch. It can be seen that in the environment of fast excitation system with fast response and high magnification, the synthetic torque ΔT _e is located in the fourth quadrant of the vector diagram, and the damping torque ΔT _d is negative, which easily causes power oscillation and reduces system stability.

Therefore, the present invention provides additional damping torque by adding virtual excitation PSS and virtual angle PSS to suppress power oscillation.

The specific process is:

Construct virtual PSS according to the Heffron-Phillips model of actively supported VSC;

The virtual excitation PSS design process is as follows:

The control block diagram of the additional virtual excitation PSS is as shown in Figure 6, and Δω is used as the control signal, so that the control signal is fed back to the excitation circuit through the transfer function G' _pss (s), and the additional electromagnetic torque ΔT' _pss is generated;

According to Fig. 7, the additional electromagnetic torque ΔT′ _pss provided by the virtual excitation PSS is:

According to formula (10), the electromagnetic torque ΔT′ _pss vector diagram can be drawn. To simplify the analysis, temporarily set G′ _pss (s) as a constant coefficient, and then focus on considering the G′ _pss (s) parameter in the parameter optimization link. The moment ΔT′ _pss vector diagram is shown in Fig. 8 .

According to Fig. 8, the additional electromagnetic torque ΔT′ _pss provided by the virtual excitation PSS can provide a positive damping torque ΔT′ _d in the first quadrant, which reduces the original negative damping torque of the system.

The virtual angle PSS design process is:

Due to the limited damping torque provided by the virtual excitation PSS, when the value of G′ _pss (s) is too large, it may affect the stability of the system. Therefore, the present invention can provide an additional damping torque on the basis of the excitation PSS by designing the angle virtual PSS.

The control block diagram of the additional virtual angle PSS is shown in Figure 9. In the overall control framework of the system, the correction amount Δδ _pss of the power angle Δδ is introduced as an additional control, where Δδ _pss = G″ _pss (s) Δω, so that the corrected power angle Δδ = Δδ _pss + Δδ ₀ , in the excitation circuit Produce additional electromagnetic torque ΔT " _pss , as shown in Figure 10, the additional electromagnetic torque ΔT " _pss of virtual angle PSS is:

According to formula (11), the electromagnetic torque ΔT″ _pss vector diagram can be drawn. To simplify the analysis, temporarily set G″ _pss (s) as a constant coefficient, ignore the influence of the _K4 branch, and then focus on G″ in the parameter optimization link _{The pss} (s) parameter and the electromagnetic torque ΔT″ _pss vector diagram are shown in Figure 11.

According to Fig. 11, the additional electromagnetic torque ΔT″ _pss provided by the virtual angle PSS is in the first quadrant, which can provide a positive damping torque ΔT″ _d and reduce the original negative damping torque of the system.

To sum up, the control block diagram of the virtual dual PSS is shown in Fig. 12, and the total electromagnetic torque ΔT _e ^* provided by the virtual dual PSS is

ΔT _e ^* = ΔT _e +ΔT _p ′ _ss + ΔT″ _pss (12)

By adding virtual dual PSS control, the system damping torque can be greatly increased and the system stability can be improved.

Step 3. In order to improve the oscillation mode of the system and improve the controllability of the virtual dual PSS, optimize the parameters of the virtual dual PSS of the actively supported VSC. The specific process of step 3 is:

Optimize the virtual excitation PSS parameters and virtual angle PSS parameters in the virtual dual PSS of active support VSC;

In order to simplify the analysis above, the transfer functions G′ _pss (s) and G″ _pss (s) are temporarily set as constant coefficients. In order to make the virtual double PSS provide positive pure damping torque, the parameters of the virtual double PSS are optimized below .

Optimization of virtual excitation PSS parameters:

Assuming that the value of the control signal Δω phase correction is Δu _pss , in order to enable the virtual excitation PSS to provide positive pure damping torque, the phase of the transfer function G′ _pss (s) needs to be able to compensate the transfer function from Δu _pss to ΔT′ _pss Phase, namely Δu _pss = Δω*G′ _pss (s), the transfer function from Δu _pss to ΔT′ _pss is F′ _pss (s), the formula is as follows:

Let the damping coefficient provided by the virtual excitation PSS be D′ _pss , that is

D' _pss = G' _pss (s) F' _pss (s) (14)

Express F′ _pss (s) and G′ _pss (s) as follows:

为传递函数F′_pss(s)的相位角，γ′为传递函数G′_pss(s)的相位角；In the formula,

Be the phase angle of transfer function F' _pss (s), γ ' is the phase angle of transfer function G' _pss (s);

According to the phase compensation method, there are

In the formula, T′ _pssd is the additional damping torque provided by the virtual excitation PSS, and T′ _psss is the additional synchronous torque provided by the virtual excitation PSS;

which is

Set the transfer function G′ _pss (s) as a proportional link and a lead-lag link, expressed as:

In the formula, T ₁ ~ T ₄ all represent the time constant of the lead-lag link, K′ ₁ and K′ ₂ are the parameter setting values of the virtual excitation PSS;

Assuming that the virtual excitation PSS provides a positive damping torque, it can be obtained from (16):

Given the values of T ₁ and T ₃ , calculate T ₂ , T ₄ , K′ ₁ , K′ ₂ according to formula (19), and obtain the transfer function G′ _pss after parameter optimization according to formula (15) and (18) (s);

Optimization of virtual angle PSS parameters:

Assuming that the virtual angle PSS provides positive pure damping torque, ΔT″ _pss is the electromagnetic torque provided by the virtual angle PSS, the correction amount Δδ _pss of the power angle Δδ is the output stability control signal of the virtual angle PSS, and the value provided by the virtual angle PSS The electromagnetic torque is ΔT″ _pss , and F″ _pss (s) is the transfer function from _Δδpss to ΔT″ _pss , then:

ΔT″ _pss = F″ _pss (s) Δδ _pss (21)

In order to make the virtual angle PSS provide a positive pure damping torque, it is necessary to make the phase of the transfer function G″ _pss (s) compensate the phase of the transfer function F″ _pss (s), and set the transfer function G″ _pss (s) as a proportional link and the lead-lag link, expressed as:

In the formula, T′ ₁ ~ T′ ₄ all represent the time constant of the lead-lag link, K″ ₁ and K″ ₂ are the parameter setting values of the virtual angle PSS;

Similarly, the virtual excitation PSS can be obtained

为传递函数F″_pss(s)的相位角，γ″为传递函数G″_pss(s)的相位角；In the formula,

Be the phase angle of transfer function F " _pss (s), γ " be the phase angle of transfer function G " _pss (s);

Given the values of T′ ₁ and T′ ₃ , calculate T′ ₂ , T′ ₄ , K′ ₁ , K′ ₂ according to formula (23), and obtain the transfer function G″ _pss after parameter optimization according to formula (22) (s).

Finally, a single-machine infinite power grid simulation example is built in the DIgSILENT/PoweFactory simulation software, and the system power disturbance is set at t=200s. Figure 10 shows the system frequency response waveform, and Figure 11 shows the converter output power waveform. It can be clearly seen that the oscillation amplitude of system frequency and power can be reduced by introducing virtual excitation PSS, and the damping characteristics of the system can be further improved by introducing virtual angle PSS.

Through the above method, the invention’s additional virtual double PSS control method for actively supported new energy units can effectively suppress Power oscillation to improve system stability. The accuracy and rationality of the proposed method are verified by simulation.

Claims (1)

1. The additional virtual dual PSS control method for active support type new energy units is characterized in that it is specifically implemented according to the following steps: Step 1. Establish the linearization model of the active support type VSC infinite system; the specific process is: Step 1.1. Construct the electromechanical transient model of active support VSC; the specific process is: According to the second-order rotor motion equation, first-order excitation circuit equation and excitation voltage regulation equation of the synchronous generator, the electromechanical transient model of the actively supported VSC is constructed:

In formula (1): P _m is the mechanical power, P _e is the electromagnetic power, H is the virtual inertia, D is the damping coefficient, δ is the power angle of the generator, Δω is the deviation between the rated speed and the actual speed, E _q ′ is the temporary State electromotive force, E _q is the no-load electromotive force, E _fd is the forced no-load electromotive force, E _fd ′ is the excitation electromotive force output by the automatic voltage regulator, ΔU _t is the voltage deviation value of the inverter terminal, and K _A is the automatic voltage regulator Gain, T _A is the time constant of the automatic voltage regulator, T _d0 ′ is the time constant of the excitation winding of the synchronous generator, ω ₀ is the rated angular frequency, dω/dt is the change rate of the angular frequency, dδ/dt is the change rate of the power angle rate of change; In formula (1), the expressions of electromagnetic power P _e and no-load electromotive force E _q are:

In formula (2): U _d , U _q are the d-axis component and q-axis component of the infinite bus voltage U _b , I _d , I _q are the d-axis component and q-axis component of the line current I _t , X′ _d is the direct axis transient reactance, X _d is direct axis synchronous reactance; Step 1.2, deriving the Heffron-Phillips model of the actively supported VSC; the specific process is: The virtual impedance model for constructing the actively supported VSC is:

U _td and U _tq in formula (3) are the d-axis component and q-axis component of VSC terminal voltage U _t ; The voltage equation of the transmission line of the actively supported VSC infinite system is: U _t =jX _t I _t +U _b (4) In formula (4), X _t is the line reactance, I _t is the line current, U _b is the infinite bus voltage, U _t is the inverter terminal voltage; Obtained by formula (1)-(4):

By linearizing equation (5) at the steady-state operating point and simplifying it, we get:

Among them, the coefficients K ₁ ~ K ₆ are constants related to the system structure, parameters and operating conditions; Putting formula (6) into formula (1), the Heffron-Phillips model of actively supported VSC is obtained, that is, the linearized control model of actively supported VSC infinite system:

Step 2. Design the active support type VSC virtual double PSS; Designing the virtual double PSS of the actively supported VSC includes designing the virtual excitation PSS and virtual angle PSS of the electromagnetic torque of the synchronous motor. The specific process is as follows: Construct virtual PSS according to the Heffron-Phillips model of actively supported VSC; The virtual excitation PSS design process is as follows: Δω is used as the control signal, so that the control signal is fed back to the excitation circuit after the transfer function G' _pss (s), and an additional electromagnetic torque ΔT' _pss is generated; Then the additional electromagnetic torque ΔT′ _pss provided by the virtual excitation PSS is:

The virtual angle PSS design process is: The correction amount Δδ _pss of the power angle Δδ is introduced as an additional control, where Δδ _pss = G″ _pss (s) Δω, so that the corrected power angle Δδ = Δδ _pss + Δδ ₀ , and an additional electromagnetic torque ΔT is generated in the excitation circuit " _pss , the additional electromagnetic torque ΔT " _pss of virtual angle PSS is:

Step 3. Optimizing the virtual dual PSS parameters of the active support VSC; the specific process is: optimizing the virtual excitation PSS parameters and virtual angle PSS parameters in the active support VSC virtual dual PSS; Optimization of virtual excitation PSS parameters: Suppose the value of the control signal Δω phase correction is Δu _pss , that is, Δu _pss = Δω*G′ _pss (s), the transfer function from Δu _pss to ΔT′ _pss is F′ _pss (s), the formula is as follows:

Let the damping coefficient provided by the virtual excitation PSS be D′ _pss , that is D' _pss = G' _pss (s) F' _pss (s) (14) Express F′ _pss (s) and G′ _pss (s) as follows:

In the formula,

Be the phase angle of transfer function F' _pss (s), γ ' is the phase angle of transfer function G' _pss (s); According to the phase compensation method, there are

In the formula, T′ _pssd is the additional damping torque provided by the virtual excitation PSS, and T′ _psss is the additional synchronous torque provided by the virtual excitation PSS; which is

Set the transfer function G′ _pss (s) as a proportional link and a lead-lag link, expressed as:

In the formula, T ₁ ~ T ₄ all represent the time constant of the lead-lag link, K′ ₁ and K′ ₂ are the parameter setting values of the virtual excitation PSS; Assuming that the virtual excitation PSS provides a positive damping torque, it can be obtained from (16):

Given the values of T ₁ and T ₃ , calculate T ₂ , T ₄ , K′ ₁ , K′ ₂ according to formula (19), and obtain the transfer function G′ _pss after parameter optimization according to formula (15) and (18) (s); Optimization of virtual angle PSS parameters: Assuming that the virtual angle PSS provides a positive pure damping torque, ΔT″ _pss is the electromagnetic torque provided by the virtual angle PSS, the correction amount Δδ _pss of the power angle Δδ is the output stability control signal of the virtual angle PSS, and the value provided by the virtual angle PSS The electromagnetic torque is ΔT″ _pss , and F″ _pss (s) is the transfer function from _Δδpss to ΔT″ _pss , then:

ΔT″ _pss = F″ _pss (s) Δδ _pss (21) Let the phase compensation of the transfer function G″ _pss (s) be the phase of the transfer function F″ _pss (s), set the transfer function G″ _pss (s) as a proportional link and a lead-lag link, expressed as:

In the formula, T′ ₁ ~ T′ ₄ all represent the time constant of the lead-lag link, K″ ₁ and K″ ₂ are the parameter setting values of the virtual angle PSS; Similarly, the virtual excitation PSS can be obtained

In the formula,

Be the phase angle of transfer function F " _pss (s), γ " be the phase angle of transfer function G " _pss (s); Given the values of T′ ₁ and T′ ₃ , calculate T′ ₂ , T′ ₄ , K′ ₁ , K′ ₂ according to formula (23), and obtain the transfer function G″ _pss after parameter optimization according to formula (22) (s).

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