A method and system for power control of a virtual synchronous generator with additional damping regulation

Abstract

The application relates to a virtual synchronous generator power control method and system with additional damping adjustment, which comprises the following steps: determining a power adjustment quantity unit value of a virtual synchronous generator based on a transfer function of a pre-established damping controller and a rotor angular frequency unit value of the synchronous generator; and controlling active power output by the virtual synchronous generator according to the power adjustment quantity unit value of the virtual synchronous generator. The technical scheme provided by the application can effectively configure the electromechanical oscillation mode dominant pole of the synchronous generator by reasonably designing the additional damping controller of the virtual synchronous generator, thereby weakening the rotor speed oscillation of the synchronous generator under disturbance, and improving the damping characteristics of the power system and inhibiting the low-frequency oscillation of the system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy power generation operation control, and particularly relates to a virtual synchronous generator power control method and system with additional damping adjustment. BACKGROUND

[0002] The relative swing between the rotors of the generator will occur under the disturbance of the power system, and the sustained low-frequency oscillation of the frequency will be caused when the damping is lacking. At this time, the power on the transmission line will also oscillate accordingly. Long-term low-frequency oscillation can cause overcurrent of the tie line, misoperation of the relay protection and even oscillation out of step, which seriously affects the safe and stable operation of the power grid.

[0003] New energy has the characteristics of small equivalent moment of inertia and insufficient frequency modulation, which reduces the disturbance resistance of the power grid and affects the low-frequency oscillation characteristics. Research shows that the influence of new energy on damping characteristics is closely related to the location of its access, the capacity of its grid connection and the control strategy used.

[0004] In order to enable the converter to provide inertia and damping support under the dynamic condition of the power grid, the virtual synchronous generator control strategy is generally used. However, at present, only the inertia support provided by the virtual synchronous generator and the dynamic response of the grid frequency are considered, and the influence of the converter with the virtual synchronous generator control strategy on the damping characteristics of the power system is ignored. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a virtual synchronous generator power control method with additional damping adjustment, which rationally designs the additional damping controller of the virtual synchronous generator, effectively configures the dominant pole of the electromechanical oscillation mode of the synchronous generator, weakens the rotor speed oscillation of the synchronous generator under disturbance, and thus improves the damping characteristics of the power system and suppresses the low-frequency oscillation of the system.

[0006] The purpose of the present application is achieved by using the following technical solutions:

[0007] The present application provides a virtual synchronous generator power control method with additional damping adjustment, which is improved in that the method comprises:

[0008] Determine the power regulation quantity per unit of the virtual synchronous generator based on the transfer function of the pre-established damping controller and the rotor angular frequency per unit of the synchronous generator;

[0009] Control the active power output by the virtual synchronous generator according to the power regulation quantity per unit of the virtual synchronous generator;

[0010] The transfer function of the damping controller is constructed according to the dominant pole of the electromechanical oscillation mode of the synchronous generator.

[0011] The application provides a virtual synchronous generator power control system with additional damping adjustment, which is improved in that the system comprises:

[0012] A determination module is configured to determine a power adjustment amount unit value of the virtual synchronous generator based on a transfer function of a pre-established damping controller and a rotor angular frequency unit value of the synchronous generator.

[0013] A control module is configured to control active power output by the virtual synchronous generator according to the power adjustment amount unit value of the virtual synchronous generator.

[0014] The transfer function of the damping controller is constructed according to a dominant pole of an electromechanical oscillation mode of the synchronous generator.

[0015] Compared with the closest prior art, the application has the beneficial effects that:

[0016] The technical scheme provided by the application determines a power adjustment amount unit value of the virtual synchronous generator based on a transfer function of a pre-established damping controller and a rotor angular frequency unit value of the synchronous generator, and controls active power output by the virtual synchronous generator according to the power adjustment amount unit value of the virtual synchronous generator. The additional damping controller of the virtual synchronous generator can be reasonably designed through the dominant pole of the electromechanical oscillation mode of the synchronous generator, the rotor speed oscillation of the synchronous generator during disturbance is weakened, the damping characteristics of the power system are improved, and the low-frequency oscillation of the system is inhibited. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 FIG. 1 is a control block diagram of a virtual synchronous generator in an embodiment of the application;

[0018] Figure 2 FIG. 2 is a flowchart of a virtual synchronous generator power control method with additional damping adjustment;

[0019] Figure 3 FIG. 3 is a virtual synchronous generator power control block diagram with additional damping adjustment;

[0020] Figure 4 FIG. 4 is a control block diagram of a damping controller in an embodiment of the application;

[0021] Figure 5 FIG. 5 is a control block diagram of a closed-loop control system in an embodiment of the application;

[0022] Figure 6 FIG. 6 is a single-machine non-group large system with new energy in an embodiment of the application;

[0023] Figure 7 FIG. 7 is a structural diagram of a virtual synchronous generator power control system with additional damping adjustment. DETAILED DESCRIPTION

[0024] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0025] To make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of the present application.

[0026] The present application deeply analyzes the grid-connection characteristics of new energy with a virtual synchronous generator control strategy, as shown in FIG. 1. Figure 1 The active power control loop of the virtual synchronous generator simulates the inertia and primary frequency modulation characteristics of the synchronous generator, and the reactive power control loop of the virtual synchronous generator simulates the primary voltage regulation characteristics of the synchronous generator, and the mathematical model can be expressed as:

[0027]

[0028] The mathematical model converted into per-unit values can be expressed as:

[0029]

[0030] wherein, δ VSG is the phase angle difference between the internal electromotive force of the virtual synchronous generator and the grid voltage, is the per-unit value of the virtual angular velocity of the virtual synchronous generator, ω n is the rated angular velocity of the virtual synchronous generator, θ pcc is the phase angle of the grid voltage, θ is the phase angle of the internal electromotive force of the virtual synchronous generator, H JVSG is the inertia time constant of the virtual synchronous generator, is the per-unit value of the active power reference value output by the virtual synchronous generator, is the per-unit value of the active power output by the virtual synchronous generator, is the per-unit value of the power regulation amount of the virtual synchronous generator, is the virtual damping coefficient in per-unit values, E * is the per-unit value of the effective value of the internal electromotive force of the virtual synchronous generator, is the per-unit value of the effective value of the phase voltage at the grid-connection point of the virtual synchronous generator, is the impedance of the inverter commutation reactor, is the per-unit value of the reactive power output by the virtual synchronous generator, H K is the time constant of the reactive power control loop of the virtual synchronous generator in per-unit values, a power reference value of the virtual synchronous generator, P a voltage droop coefficient, ω VSG a virtual angular velocity of the virtual synchronous generator, P ref a power reference value of the virtual synchronous generator, P VSG a power output of the virtual synchronous generator, D p a virtual damping coefficient, K a power control loop time constant of the virtual synchronous generator, E an effective value of an internal electromotive force of the virtual synchronous generator, Q ref a power reference value of the virtual synchronous generator, Q VSG a power output of the virtual synchronous generator, D q a voltage droop coefficient, U pcc an effective value of a grid-connected point phase voltage of the virtual synchronous generator, U n a rated voltage of the grid, wherein U B a reference voltage of the grid, S B a reference capacity of the grid.

[0031] Through the control block diagram and the mathematical model of the virtual synchronous generator, it can be seen that the influence of the converter access on the damping characteristics of the power system is not considered in the control strategy of the virtual synchronous generator, and the sustained frequency low-frequency oscillation caused by the lack of damping is not processed. Based on this, the application provides a power control method of a virtual synchronous generator with additional damping adjustment, as shown in the formula (1), the method comprises the steps of: Figure 2 as shown in the formula (1), the method comprises the steps of:

[0032] Step 101. Determine the power adjustment value of the virtual synchronous generator based on the transfer function of the pre-established damping controller and the rotor angular frequency unit value of the synchronous generator.

[0033] Step 102. Control the active power output of the virtual synchronous generator according to the power adjustment value of the virtual synchronous generator.

[0034] The transfer function of the damping controller is constructed according to the dominant pole of the electromechanical oscillation mode of the synchronous generator.

[0035] In the specific embodiment of the application, the control block diagram of the virtual synchronous generator with the damping controller is as shown in the formula (2), it can be seen that when the rotor angular frequency of the synchronous generator changes, the damping controller starts to work, and provides a power adjustment value for the virtual synchronous generator, thereby changing the active power output of the virtual synchronous generator. Figure 3

[0036] Specifically, the step 101 comprises the following steps.

[0037] ​A power regulation quantity unit value of a virtual synchronous generator is determined according to the following formula

[0038]

[0039] In the formula, H(s) is a transfer function of a pre-established damping controller, is a rotor angular frequency unit value of the synchronous generator.

[0040] Further, the transfer function of the damping controller is constructed according to a synchronous generator electromechanical oscillation mode dominant pole, and includes:

[0041] The transfer function H(s) of the pre-established damping controller is determined according to the following formula:

[0042]

[0043] In the formula, K dmp is a gain coefficient of the transfer function of the damping controller, T w is a direct-current time constant of the transfer function of the damping controller, T1 is a phase correction time constant of the transfer function of the damping controller, T2 is a phase compensation time constant of the transfer function of the damping controller, and s is a Laplace operator.

[0044] The T1 and K dmp are determined based on a synchronous generator electromechanical oscillation mode dominant pole.

[0045] In a specific embodiment of the present application, a control block diagram of the damping controller is as shown in Figure 4 A damping signal is added to an active control loop of the virtual synchronous generator, so as to further suppress power low-frequency oscillation of the system.

[0046] When the power system is in normal operation, the synchronous generator rotor angular velocity change ω G is zero, and the input signal of the added damping controller is unchanged.

[0047] When the low-frequency oscillation occurs, the added damping controller adjusts the active power given value P G of the VSG according to the input signal ω ref : when the synchronous generator rotor angular velocity is higher than a rated value, the system is active surplus, the output signal of the added damping controller compensates the active power given value P ref to reduce the active power output of the VSG; and when the synchronous generator rotor angular velocity is lower than the rated value, the system is active deficient, the output signal of the added damping controller compensates the active power given value P ref to increase the active power output of the VSG.

[0048] Further, the T1 and K dmpdetermined based on dominant poles of the electromechanical oscillation mode of the synchronous generator, including:

[0049] The phase correction time constant T1 of the transfer function of the damping controller is solved by the following formula:

[0050]

[0051] wherein arc(H(λ0)) is the phase of the transfer function of the damping controller at the dominant pole of the electromechanical oscillation mode of the synchronous generator, and λ0 is the dominant pole of the electromechanical oscillation mode of the synchronous generator;

[0052] The gain coefficient K of the transfer function of the damping controller is solved by the following formula: dmp

[0053]

[0054] wherein |H(λ0)| is the amplitude of the transfer function of the damping controller at the dominant pole of the electromechanical oscillation mode of the synchronous generator.

[0055] Further, the phase arc(H(λ0)) of the transfer function of the damping controller at the dominant pole of the electromechanical oscillation mode of the synchronous generator is determined by the following formula:

[0056] arc(H(λ0))=180°-arc(G(λ0))

[0057] wherein arc(G(λ0)) is the phase of the open-loop transfer function between the active power reference of the virtual synchronous generator and the rotor angular velocity of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator;

[0058] The amplitude |H(λ0)| of the transfer function of the damping controller at the dominant pole of the electromechanical oscillation mode of the synchronous generator is determined by the following formula:

[0059]

[0060] wherein |G(λ0)| is the amplitude of the open-loop transfer function between the active power reference of the virtual synchronous generator and the rotor angular velocity of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator.

[0061] Before constructing the damping controller, a closed-loop control system as shown in Figure 5 must be constructed, and the transfer function of the closed-loop control system is: ​Wherein, G(s) is the open-loop transfer function between the active power given value of the virtual synchronous generator and the rotor angular velocity of the synchronous generator, H(s) is the transfer function of the damping controller, thus, if the dominant pole of the electromechanical oscillation mode of the synchronous generator of the closed-loop control system is configured as λ0, the following relationship must be satisfied:

[0062]

[0063] In the formula, |G(λ0)| is the amplitude of the open-loop transfer function between the active power given value of the virtual synchronous generator and the rotor angular velocity of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator, and arc(G(λ0)) is the phase of the open-loop transfer function between the active power given value of the virtual synchronous generator and the rotor angular velocity of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator.

[0064] Further, the process of obtaining the dominant pole λ0 of the electromechanical oscillation mode of the synchronous generator comprises:

[0065] Solving Obtaining the dominant pole of the electromechanical oscillation mode of the synchronous generator;

[0066] Wherein, ζ is the damping ratio control value, R e (λ0) is the real part of the dominant pole of the electromechanical oscillation mode of the synchronous generator, [I m (λ0)] is the imaginary part of the dominant pole of the electromechanical oscillation mode of the synchronous generator.

[0067] In the preferred embodiment of the present application, it is generally desired that the damping ratio in the low-frequency oscillation mode is not less than 0.1-0.3, and the damping ratio is controlled to be 0.217, at this time, the dominant pole of the electromechanical oscillation mode of the synchronous generator is configured as λ0=-2±9i, and λ0 is substituted into the open-loop transfer function between the active power given value of the virtual synchronous generator and the rotor angular velocity of the synchronous generator, |G(λ0)| is equal to 0.0063, and arc(G(λ0)) is equal to 133.1645 degrees, thus, |H(λ0)| is equal to 158.8254, and arg(H(λ0)) is equal to 46.8355 degrees;

[0068] Suppose that the direct-axis time constant of the damping controller is selected to be 10 (the value is determined by the actual working condition, and is generally 3-10S), and the phase compensation time constant is selected to be 0.05 (the value is determined by the actual working condition, and is generally 0.05-0.1S), which are substituted into the formula , the calculated phase correction time constant is 0.105, and the above value is substituted into to calculate that the gain coefficient of the transfer function of the damping controller is 105.8; thus far, the transfer function of the damping controller is configured.

[0069] Further, the process of obtaining the amplitude |G(λ0)| and the phase arc(G(λ0)) of the open-loop transfer function between the active power given value of the virtual synchronous generator and the rotor angular velocity of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator comprises:

[0070] Solving G(λ0)=G1(λ0)·G2(λ0), the amplitude |G(λ0)| and the phase arc(G(λ0)) of the open-loop transfer function between the active power given value of the virtual synchronous generator and the rotor angular velocity of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator are obtained;

[0071] Wherein, G(λ0) is the value of the open-loop transfer function between the active power given value of the virtual synchronous generator and the rotor angular velocity of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator, G1(λ0) is the value of the transfer function of the VSG active power control loop at the dominant pole of the electromechanical oscillation mode of the synchronous generator, and G2(λ0) is the value of the open-loop transfer function between the active power output of the virtual synchronous generator and the rotor angular frequency of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator.

[0072] Further, the value G1(λ0) of the transfer function of the VSG active power control loop at the dominant pole of the electromechanical oscillation mode of the synchronous generator is determined according to the following formula:

[0073]

[0074] In the formula, ΔP is the unit value of the change amount of the active power output of the virtual synchronous generator, is the unit value of the change amount of the active power reference value of the output of the virtual synchronous generator, ω n is the rated angular velocity of the virtual synchronous generator, E * is the unit value of the effective value of the internal electromotive force of the virtual synchronous generator, H JVSG is the inertia time constant of the virtual synchronous generator, is the unit value of the effective value of the grid-connected point phase voltage of the virtual synchronous generator, is the impedance of the inverter commutation reactor, is the virtual damping coefficient in the unit, and λ0 is the dominant pole of the electromechanical oscillation mode of the synchronous generator.

[0075] In the specific embodiments of the present application, the transfer function of the VSG active power control loop is obtained by small signal transformation and Laplace transformation in the control strategy of the virtual synchronous generator, wherein D p may be 10000, D q may be 24500, H JVSG may be 0.1, H K may be 0.045.

[0076] The open-loop transfer function between the active output of the virtual synchronous generator and the rotor angle frequency of the synchronous generator is determined according to the following formula:

[0077]

[0078] In the formula, k1 is the first parameter, k2 is the second parameter, M is the inertia time constant of the synchronous generator, and D is the damping coefficient of the synchronous generator.

[0079] In the preferred embodiment of the present application, k1 can be 2.634, k2 can be 11.947, M can be 7.4 s, and D can be 2.6 p.u.

[0080] The inertia time constant H of the virtual synchronous generator is determined according to the following formula: JVSG

[0081]

[0082] In the formula, J is the moment of inertia of the virtual synchronous generator, S B is the reference capacity of the power grid.

[0083] The virtual damping coefficient in the per-unit system is determined according to the following formula:

[0084]

[0085] In the formula, D p is the virtual damping coefficient.

[0086] The first parameter k1 is determined according to the following formula:

[0087]

[0088] In the formula, E Go is the steady-state value of the internal electromotive force of the synchronous generator, U po is the steady-state value of the voltage vector at the point of common coupling, x Σ1 is the impedance of the line between the secondary side of the transformer connected to the synchronous generator and the point of common coupling, δ Go is the steady-state value of the voltage angle frequency of the synchronous generator, δ po is the steady-state value of the voltage angle frequency at the point of common coupling.

[0089] The second parameter k2 is determined according to the following formula:

[0090]

[0091] In the formula, U o ​​x is the steady-state value of the bus voltage. Σ3 This is the impedance of the line between the point of common coupling and the busbar.

[0092] In a specific embodiment of the present invention, a large-scale motor system containing a new energy power station is as follows: Figure 6 As shown in the figure, the infinite bus voltage U has a phase angle of 0 and serves as the reference node for the entire system; the generator internal potential, generator terminal voltage, inverter output voltage, inverter grid connection point voltage, and point of common coupling voltage vectors are represented by E, respectively. G U G E, U pcc and U p This indicates that, when line losses are ignored, the active power equation of the power grid yields:

[0093]

[0094] In the formula: x Σ1 x is the reactance on line 1. Σ3 For the reactance on line 3, δ G Let δ be the voltage angular frequency of the synchronous generator. p The voltage angular frequency of the point of common coupling (the point of common coupling is the intersection of the synchronous generator power output line, the virtual synchronous generator power output line, and the bus lead-out line);

[0095] Assume the internal electromotive force of the generator is E G If constant, then the small-signal model of the above equation is:

[0096]

[0097] In the formula, the subscript 0 indicates the steady-state value of the variable, and Δ indicates the change. From the above formula, the voltage phase angle disturbance on bus 3 can be expressed as:

[0098]

[0099] In the formula:

[0100] The electromagnetic power output of the synchronous generator can then be expressed as:

[0101]

[0102] The above four equations hold true for both nominal and per-unit values. Since frequency and phase angle are the main factors affecting active power in a power system, the voltage change in the third term of the above equations can be ignored, resulting in a simplified expression for the output electromagnetic power of a synchronous generator:

[0103]

[0104] likeFigure 6 The synchronous generator shown adopts a classical second-order model, and then the rotor small disturbance motion equation is as shown in the following formula.

[0105]

[0106] The rotor small disturbance motion equation of the second-order model of the synchronous generator is substituted into the simplified expression of the output electromagnetic power of the synchronous generator to obtain the virtual synchronous generator output active power P VSG * and the small disturbance function relationship of the rotor angular frequency ω G * of the synchronous generator is:

[0107]

[0108] In the formula, M is the inertia time constant of the synchronous generator; D is the damping coefficient of the synchronous generator; P e is the output electromagnetic power of the synchronous generator.

[0109] The Laplace transformation is performed to obtain the open-loop transfer function G2(s) between the active output of the virtual synchronous generator and the rotor angular frequency of the synchronous generator.

[0110] Specifically, the active power output by the virtual synchronous generator is controlled according to the power regulation amount unit value of the virtual synchronous generator, including:

[0111] The power regulation amount unit value of the virtual synchronous generator is substituted into the VSG mathematical control model to obtain the active output unit value of the virtual synchronous generator;

[0112] The active output unit value of the virtual synchronous generator is converted into an active output value of the virtual synchronous generator, and the active power output by the virtual synchronous generator is controlled to be the active output value of the virtual synchronous generator.

[0113] Further, the VSG mathematical control model is determined according to the following formula:

[0114]

[0115] In the formula, δ VSG is the phase angle difference between the internal potential of the virtual synchronous generator and the grid voltage, is the unit value of the virtual angular velocity of the virtual synchronous generator, ω n is the rated angular velocity of the virtual synchronous generator, θ pcc is the phase angle of the grid voltage, θ is the phase angle of the internal potential of the virtual synchronous generator, H JVSG is the inertia time constant of the virtual synchronous generator, is the unit value of the active power reference value output by the virtual synchronous generator, A unit for an active power output of the virtual synchronous generator, A unit for a power regulation of the virtual synchronous generator, A virtual damping coefficient in a unit, * A unit for an internal electromotive force effective value of the virtual synchronous generator, A unit for a phase voltage effective value of a grid connection point of the virtual synchronous generator, An inverter converter reactor impedance.

[0116] The application adopts a mechanism analysis method to analyze the coupling influence of a new energy controlled by a virtual synchronous generator on a synchronous generator, and proposes an active control method of additional damping of the new energy grid connection, and the following conclusions are obtained compared with the existing method: by reasonably designing an additional damping controller of the virtual synchronous generator, the dominant pole of an electromechanical oscillation mode of the synchronous generator can be effectively configured by using a power system pole configuration method, the rotor speed oscillation of the synchronous generator during disturbance is weakened, and then the damping characteristics of the system are improved, and the low-frequency oscillation of the system is suppressed.

[0117] The application provides a virtual synchronous generator power control system with additional damping regulation, as shown in Figure 7 The system comprises:

[0118] A determination module configured to determine a power regulation unit of the virtual synchronous generator in a unit based on a transfer function of a pre-established damping controller and a rotor angular frequency unit of the synchronous generator;

[0119] A control module configured to control an active power output by the virtual synchronous generator according to the power regulation unit of the virtual synchronous generator in a unit.

[0120] The transfer function of the damping controller is constructed according to the dominant pole of the electromechanical oscillation mode of the synchronous generator.

[0121] Specifically, the determination module is configured to:

[0122] determine the power regulation unit of the virtual synchronous generator in a unit according to the following formula

[0123]

[0124] In the formula, H(s) is the transfer function of the pre-established damping controller, and ω is the rotor angular frequency unit of the synchronous generator.

[0125] Further, the system further comprises a function construction module, and the function construction module is specifically configured to:

[0126] determine the transfer function H(s) of the pre-established damping controller according to the following formula

[0127]

[0128] wherein K dmp is a gain coefficient of the transfer function of the damping controller, T w is a washout time constant of the transfer function of the damping controller, T1 is a phase correction time constant of the transfer function of the damping controller, T2 is a phase compensation time constant of the transfer function of the damping controller, and s is a Laplace operator;

[0129] wherein T1 and K dmp are determined based on a dominant pole of an electromechanical oscillation mode of the synchronous generator.

[0130] Further, the T1 and K dmp are determined based on a dominant pole of an electromechanical oscillation mode of the synchronous generator, comprising:

[0131] The phase correction time constant T1 of the transfer function of the damping controller is solved by the following formula:

[0132]

[0133] wherein arc(H(λ0)) is a phase of the transfer function of the damping controller at the dominant pole of the electromechanical oscillation mode of the synchronous generator, and λ0 is the dominant pole of the electromechanical oscillation mode of the synchronous generator;

[0134] The gain coefficient K dmp of the transfer function of the damping controller is solved by the following formula:

[0135]

[0136] wherein |H(λ0)| is an amplitude of the transfer function of the damping controller at the dominant pole of the electromechanical oscillation mode of the synchronous generator.

[0137] Specifically, the phase arc(H(λ0)) of the transfer function of the damping controller at the dominant pole of the electromechanical oscillation mode of the synchronous generator is determined by the following formula:

[0138] arc(H(λ0))=180°-arc(G(λ0))

[0139] wherein arc(G(λ0)) is a phase of an open-loop transfer function between the active power given value of the virtual synchronous generator and the rotor angular velocity of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator;

[0140] The amplitude |H(λ0)| of the transfer function of the damping controller at the dominant pole of the electromechanical oscillation mode of the synchronous generator is determined by the following formula:

[0141]

[0142] wherein |G(λ0)| is the amplitude of the open-loop transfer function between the active power reference of the VSG and the rotor angular speed of the SG at the dominant pole of the electromechanical oscillation mode of the SG.

[0143] Further, the process of obtaining the dominant pole λ0 of the electromechanical oscillation mode of the SG comprises:

[0144] solving obtaining the dominant pole of the electromechanical oscillation mode of the SG;

[0145] wherein ζ is the damping ratio control value, R e (λ0) is the real part of the dominant pole of the electromechanical oscillation mode of the SG, [I m (λ0) is the imaginary part of the dominant pole of the electromechanical oscillation mode of the SG.

[0146] Further, the process of obtaining the amplitude |G(λ0)| and the phase arc(G(λ0)) of the open-loop transfer function between the active power reference of the VSG and the rotor angular speed of the SG at the dominant pole of the electromechanical oscillation mode of the SG comprises:

[0147] solving G(λ0) = G1(λ0)·G2(λ0) to obtain the amplitude |G(λ0)| and the phase arc(G(λ0)) of the open-loop transfer function between the active power reference of the VSG and the rotor angular speed of the SG at the dominant pole of the electromechanical oscillation mode of the SG;

[0148] wherein G(λ0) is the value of the open-loop transfer function between the active power reference of the VSG and the rotor angular speed of the SG at the dominant pole of the electromechanical oscillation mode of the SG, G1(λ0) is the value of the transfer function of the VSG active power control loop at the dominant pole of the electromechanical oscillation mode of the SG, and G2(λ0) is the value of the open-loop transfer function between the active power output of the VSG and the rotor angular frequency of the SG at the dominant pole of the electromechanical oscillation mode of the SG.

[0149] Further, the value G1(λ0) of the transfer function of the VSG active power control loop at the dominant pole of the electromechanical oscillation mode of the SG is determined according to the following formula:

[0150]

[0151] wherein is the per-unit value of the variation of the active power output of the VSG, is the per-unit value of the variation of the active power reference of the VSG output, ω n is the rated angular speed of the VSG, and E* is the per-unit value of the internal electromotive force of the VSG.JVSG inertia time constant of the virtual synchronous generator, per-unit of the effective value of the grid point phase voltage of the virtual synchronous generator, impedance of the inverter commutation reactor, virtual damping coefficient in per-unit, λ0is the dominant pole of the electromechanical oscillation mode of the synchronous generator;

[0152] The open-loop transfer function between the active output of the virtual synchronous generator and the angular frequency of the rotor of the synchronous generator is determined according to the following formula:

[0153]

[0154] In the formula, is the per-unit of the change amount of the angular frequency of the rotor of the synchronous generator, k1is the first parameter, k2is the second parameter, M is the inertia time constant of the synchronous generator, and D is the damping coefficient of the synchronous generator;

[0155] The inertia time constant H of the virtual synchronous generator is determined according to the following formula: JVSG

[0156]

[0157] In the formula, J is the moment of inertia of the virtual synchronous generator, S B is the reference capacity of the power grid;

[0158] The virtual damping coefficient in per-unit is determined according to the following formula:

[0159]

[0160] In the formula, D p is the virtual damping coefficient;

[0161] The first parameter k1is determined according to the following formula:

[0162]

[0163] In the formula, E Go is the steady-state value of the internal electromotive force of the synchronous generator, U po is the steady-state value of the voltage vector of the point of common coupling, x Σ1 is the impedance of the line between the secondary side of the transformer connected to the synchronous generator and the point of common coupling, δ Go is the steady-state value of the angular frequency of the voltage of the synchronous generator, δ po is the steady-state value of the angular frequency of the voltage of the point of common coupling;

[0164] The second parameter k2is determined according to the following formula: ​

[0165]

[0166] In the formula, U o is the steady-state value of the bus voltage, x Σ3 is the impedance of the line between the point of common coupling and the bus.

[0167] Specifically, the active power output of the virtual synchronous generator is controlled according to the power regulation amount per unit value of the virtual synchronous generator, including:

[0168] The power regulation amount per unit value of the virtual synchronous generator is substituted into the VSG mathematical control model to obtain the active output per unit value of the virtual synchronous generator;

[0169] The active output per unit value of the virtual synchronous generator is converted into an active output value of the virtual synchronous generator, and the active power output of the virtual synchronous generator is controlled to be the active output value of the virtual synchronous generator.

[0170] Further, the VSG mathematical control model is determined according to the following formula:

[0171]

[0172] In the formula, δ VSG is the phase angle difference between the internal potential of the virtual synchronous generator and the grid voltage, is the per unit value of the virtual angular velocity of the virtual synchronous generator, ω n is the rated angular velocity of the virtual synchronous generator, θ pcc is the phase angle of the grid voltage, θ is the phase angle of the internal potential of the virtual synchronous generator, H JVSG is the inertia time constant of the virtual synchronous generator, is the per unit value of the active power reference value output by the virtual synchronous generator, is the per unit value of the active output of the virtual synchronous generator, is the power regulation amount per unit value of the virtual synchronous generator, is the virtual damping coefficient per unit value, E * is the per unit value of the effective value of the internal potential of the virtual synchronous generator, is the per unit value of the effective value of the phase voltage at the grid connection point of the virtual synchronous generator, is the impedance of the inverter commutation reactor.

[0173] Those skilled in the art will appreciate that embodiments of the application can be devised for a method, a system, or a computer program product. Accordingly, the present application can be embodied in the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) embodying computer readable program code.

[0174] The present application is described in reference to the flowchart illustrations and / or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0175] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0176] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams. Figure 1 one or more functions specified in the flowchart illustrations and / or block diagrams.

[0177] Finally, it should be noted that the above-mentioned embodiments are merely intended for describing and illustrating, not limiting the technical solutions of the present application. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, and any modification or equivalent replacement without departing from the spirit and scope of the present application should be covered in the protection scope of the claims of the present application.

Claims

1. A method for power control of a virtual synchronous generator with additional damping regulation, characterized in that, The method includes: The per-unit value of the power regulation of the virtual synchronous generator is determined based on the pre-established transfer function of the damping controller and the per-unit value of the rotor angular frequency of the synchronous generator. The active power output of the virtual synchronous generator is controlled according to the per-unit value of the power regulation of the virtual synchronous generator. The transfer function of the damping controller is constructed based on the dominant poles of the electromechanical oscillation mode of the synchronous generator; The transfer function of the damping controller is constructed based on the dominant poles of the electromechanical oscillation mode of the synchronous generator, including: The transfer function H(s) of the pre-established damping controller is determined by the following formula: In the formula, K dmp T represents the gain coefficient of the transfer function of the damping controller. w T1 is the DC blocking time constant of the transfer function of the damping controller, T2 is the phase correction time constant of the transfer function of the damping controller, and s is the Laplace operator. The T1 and K dmp The dominant poles are determined based on the electromechanical oscillation mode of synchronous generators; The T1 and K dmp The determination is based on the dominant poles of the electromechanical oscillation mode of the synchronous generator, including: The phase correction time constant T1 of the transfer function of the damped controller is calculated using the following formula: Where arc(H(λ0)) is the phase of the transfer function of the damping controller at the dominant pole of the synchronous generator electromechanical oscillation mode, and λ0 is the dominant pole of the synchronous generator electromechanical oscillation mode; The gain coefficient K of the transfer function of the damped controller is calculated using the following formula. dmp : Where |H(λ0)| is the amplitude of the transfer function of the damping controller at the dominant pole of the synchronous generator electromechanical oscillation mode.

2. The method as described in claim 1, characterized in that, The determination of the per-unit value of the power regulation of the virtual synchronous generator based on the pre-established transfer function of the damping controller and the per-unit value of the rotor angular frequency of the synchronous generator includes: The per-unit value of the power regulation of the virtual synchronous generator is determined by the following formula. In the formula, H(s) is the transfer function of the pre-established damping controller. This is the per-unit value of the rotor angular frequency of the synchronous generator.

3. The method as described in claim 1, characterized in that, The phase arc(H(λ0)) of the transfer function of the damping controller at the dominant pole of the synchronous generator electromechanical oscillation mode is determined by the following formula: arc(H(λ0))=180°-arc(G(λ0)) In the formula, arc(G(λ0)) is the phase of the open-loop transfer function between the given active power of the virtual synchronous generator and the rotor angular velocity of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator. The amplitude |H(λ0)| of the transfer function of the damping controller at the dominant pole of the synchronous generator electromechanical oscillation mode is determined by the following formula: In the formula, |G(λ0)| is the amplitude of the open-loop transfer function between the given active power of the virtual synchronous generator and the rotor angular velocity of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator.

4. The method as described in claim 1, characterized in that, The process of obtaining the dominant pole λ0 of the electromechanical oscillation mode of a synchronous generator includes: Solve Obtain the dominant pole of the electromechanical oscillation mode of the synchronous generator; Where ζ is the damping ratio control value, R e (λ0) is the real part of the dominant pole of the electromechanical oscillation mode of the synchronous generator, [I m [λ0] represents the imaginary part of the dominant pole of the electromechanical oscillation mode of the synchronous generator.

5. The method as described in claim 3, characterized in that, The process of obtaining the amplitude |G(λ0)| and phase arc(G(λ0)) of the open-loop transfer function between the virtual synchronous generator's active power setpoint and the synchronous generator's rotor angular velocity at the dominant pole of the synchronous generator's electromechanical oscillation mode. include: Solve for G(λ0)=G1(λ0)·G2(λ0) to obtain the amplitude |G(λ0)| and phase arc(G(λ0)) of the open-loop transfer function between the rotor angular velocities of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator; Wherein, G(λ0) is the value of the open-loop transfer function between the virtual synchronous generator's active power setpoint and the synchronous generator's rotor angular velocity at the dominant pole of the synchronous generator's electromechanical oscillation mode, G1(λ0) is the value of the transfer function of the VSG active power control loop at the dominant pole of the synchronous generator's electromechanical oscillation mode, and G2(λ0) is the value of the open-loop transfer function between the virtual synchronous generator's active power output and the synchronous generator's rotor angular frequency at the dominant pole of the synchronous generator's electromechanical oscillation mode.

6. The method as described in claim 5, characterized in that, The value of the transfer function G1(λ0) of the active power control loop of the VSG at the dominant pole of the synchronous generator electromechanical oscillation mode is determined by the following formula: In the formula, This represents the per-unit value of the change in active power output of the virtual synchronous generator. ω is the per-unit value of the change in the reference value of active power output by the virtual synchronous generator. n E is the rated angular velocity of the virtual synchronous generator. * H is the per-unit value of the effective internal potential of the virtual synchronous generator. JVSG The inertial time constant of the virtual synchronous generator. This represents the per-unit value of the effective phase voltage at the grid connection point of the virtual synchronous generator. For the inverter commutator reactor impedance, λ is the virtual damping coefficient in per unit value, and λ0 is the dominant pole of the electromechanical oscillation mode of the synchronous generator; The value of G2(λ0) of the open-loop transfer function between the active power output of the virtual synchronous generator and the rotor angular frequency of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator is determined by the following formula: In the formula, Here, k1 is the per-unit value of the change in rotor angular frequency of the synchronous generator, k2 is the first parameter, M is the inertial time constant of the synchronous generator, and D is the damping coefficient of the synchronous generator. The inertial time constant H of the virtual synchronous generator is determined by the following formula. JVSG : In the formula, J is the moment of inertia of the virtual synchronous generator, and S... B This is the grid's base capacity; Determine the virtual damping coefficient per unit value using the following formula In the formula, D p This is the virtual damping coefficient; The first parameter k1 is determined by the following formula: In the formula, E Go U is the steady-state value of the internal electromotive force of the synchronous generator. po Let x be the steady-state value of the voltage vector at the point of common coupling. Σ1 δ is the impedance of the line between the secondary side of the transformer connected to the synchronous generator and the point of common coupling. Go δ is the steady-state value of the voltage angular frequency of the synchronous generator. po This is the steady-state value of the angular frequency of the voltage at the point of common coupling; The second parameter k2 is determined by the following formula: In the formula, U o x is the steady-state value of the bus voltage. Σ3 This is the impedance of the line between the point of common coupling and the busbar.

7. The method as described in claim 1, characterized in that, The control of the active power output of the virtual synchronous generator based on the per-unit value of the power regulation amount of the virtual synchronous generator includes: Substitute the per-unit value of the power regulation of the virtual synchronous generator into the VSG mathematical control model to obtain the per-unit value of the active power output of the virtual synchronous generator. The active power output per unit value of the virtual synchronous generator is converted into the active power output value of the virtual synchronous generator, and the active power output of the virtual synchronous generator is controlled to be the active power output value of the virtual synchronous generator.

8. The method as described in claim 7, characterized in that, The VSG mathematical control model is determined by the following formula: In the formula, δ VSG The phase angle difference between the internal potential of the virtual synchronous generator and the grid voltage. ω is the per-unit value of the virtual angular velocity of the virtual synchronous generator. n θ is the rated angular velocity of the virtual synchronous generator. pcc H is the phase angle of the grid voltage, θ is the phase angle of the internal electromotive force of the virtual synchronous generator, and H is the phase angle of the grid voltage. JVSG The inertial time constant of the virtual synchronous generator. This is the per-unit value of the active power reference value output by the virtual synchronous generator. This represents the per-unit value of the active power output of the virtual synchronous generator. This represents the per-unit value of the power regulation of the virtual synchronous generator. Virtual damping coefficient, E per unit * This represents the per-unit value of the effective internal potential of the virtual synchronous generator. Per-unit value of the effective phase voltage at the grid connection point of the virtual synchronous generator. This refers to the impedance of the inverter's commutator reactor.

9. A virtual synchronous generator power control system with additional damping regulation, characterized in that, The system includes: The determination module is used to determine the per-unit value of the power regulation of the virtual synchronous generator based on the pre-established transfer function of the damping controller and the per-unit value of the rotor angular frequency of the synchronous generator; The control module is used to control the active power output of the virtual synchronous generator according to the per-unit value of the power regulation of the virtual synchronous generator. The transfer function of the damping controller is constructed based on the dominant poles of the electromechanical oscillation mode of the synchronous generator; The system further includes a function construction module, used for: The transfer function H(s) of the pre-established damping controller is determined by the following formula: In the formula, K dmp T represents the gain coefficient of the transfer function of the damping controller. w T1 is the DC blocking time constant of the transfer function of the damping controller, T2 is the phase correction time constant of the transfer function of the damping controller, and s is the Laplace operator. The T1 and K dmp The dominant poles are determined based on the electromechanical oscillation mode of synchronous generators; The T1 and K dmp The determination is based on the dominant poles of the electromechanical oscillation mode of the synchronous generator, including: The phase correction time constant T1 of the transfer function of the damped controller is solved by the following formula: Where arc(H(λ0)) is the phase of the transfer function of the damping controller at the dominant pole of the synchronous generator electromechanical oscillation mode, and λ0 is the dominant pole of the synchronous generator electromechanical oscillation mode; The gain coefficient K of the transfer function of the damped controller is obtained by solving the following formula. dmp : Where |H(λ0)| is the amplitude of the transfer function of the damping controller at the dominant pole of the synchronous generator electromechanical oscillation mode.

10. The system as described in claim 9, characterized in that, The determining module is used for: The per-unit value of the power regulation of the virtual synchronous generator is determined by the following formula. In the formula, H(s) is the transfer function of the pre-established damping controller. This is the per-unit value of the rotor angular frequency of the synchronous generator.

11. The system as described in claim 9, characterized in that, The phase arc(H(λ0)) of the transfer function of the damping controller at the dominant pole of the synchronous generator electromechanical oscillation mode is determined by the following formula: arc(H(λ0))=180°-arc(G(λ0)) In the formula, arc(G(λ0)) is the phase of the open-loop transfer function between the given active power of the virtual synchronous generator and the rotor angular velocity of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator. The amplitude |H(λ0)| of the transfer function of the damping controller at the dominant pole of the synchronous generator electromechanical oscillation mode is determined by the following formula: In the formula, |G(λ0)| is the amplitude of the open-loop transfer function between the given active power of the virtual synchronous generator and the rotor angular velocity of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator.

12. The system as described in claim 9, characterized in that, The process of obtaining the dominant pole λ0 of the electromechanical oscillation mode of a synchronous generator includes: Solve Obtain the dominant pole of the electromechanical oscillation mode of the synchronous generator; Where ζ is the damping ratio control value, R e (λ0) is the real part of the dominant pole of the electromechanical oscillation mode of the synchronous generator, [I m [λ0] represents the imaginary part of the dominant pole of the electromechanical oscillation mode of the synchronous generator.

13. The system as described in claim 11, characterized in that, The process of obtaining the amplitude |G(λ0)| and phase arc(G(λ0)) of the open-loop transfer function between the virtual synchronous generator's active power setpoint and the synchronous generator's rotor angular velocity at the dominant pole of the synchronous generator's electromechanical oscillation mode. include: Solve for G(λ0)=G1(λ0)·G2(λ0) to obtain the amplitude |G(λ0)| and phase arc(G(λ0)) of the open-loop transfer function between the rotor angular velocities of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator; Wherein, G(λ0) is the value of the open-loop transfer function between the virtual synchronous generator's active power setpoint and the synchronous generator's rotor angular velocity at the dominant pole of the synchronous generator's electromechanical oscillation mode, G1(λ0) is the value of the transfer function of the VSG active power control loop at the dominant pole of the synchronous generator's electromechanical oscillation mode, and G2(λ0) is the value of the open-loop transfer function between the virtual synchronous generator's active power output and the synchronous generator's rotor angular frequency at the dominant pole of the synchronous generator's electromechanical oscillation mode.

14. The system as described in claim 13, characterized in that, The value of the transfer function G1(λ0) of the active power control loop of the VSG at the dominant pole of the synchronous generator electromechanical oscillation mode is determined by the following formula: In the formula, This represents the per-unit value of the change in active power output of the virtual synchronous generator. ω is the per-unit value of the change in the reference value of active power output by the virtual synchronous generator. n E is the rated angular velocity of the virtual synchronous generator. * H is the per-unit value of the effective internal potential of the virtual synchronous generator. JVSG The inertial time constant of the virtual synchronous generator. This represents the per-unit value of the effective phase voltage at the grid connection point of the virtual synchronous generator. For the inverter commutator reactor impedance, λ is the virtual damping coefficient in per unit value, and λ0 is the dominant pole of the electromechanical oscillation mode of the synchronous generator; The value of G2(λ0) of the open-loop transfer function between the active power output of the virtual synchronous generator and the rotor angular frequency of the synchronous generator at the dominant pole of the electromechanical oscillation mode of the synchronous generator is determined by the following formula: In the formula, Here, k1 is the per-unit value of the change in rotor angular frequency of the synchronous generator, k2 is the first parameter, M is the inertial time constant of the synchronous generator, and D is the damping coefficient of the synchronous generator. The inertial time constant H of the virtual synchronous generator is determined by the following formula. JVSG : In the formula, J is the moment of inertia of the virtual synchronous generator, and S... B This is the grid's base capacity; Determine the virtual damping coefficient per unit value using the following formula In the formula, D p This is the virtual damping coefficient; The first parameter k1 is determined by the following formula: In the formula, E Go U is the steady-state value of the internal electromotive force of the synchronous generator. po Let x be the steady-state value of the voltage vector at the point of common coupling. Σ1 δ is the impedance of the line between the secondary side of the transformer connected to the synchronous generator and the point of common coupling. Go δ is the steady-state value of the voltage angular frequency of the synchronous generator. po This is the steady-state value of the angular frequency of the voltage at the point of common coupling; The second parameter k2 is determined by the following formula: In the formula, U o x is the steady-state value of the bus voltage. Σ3 This is the impedance of the line between the point of common coupling and the busbar.

15. The system as described in claim 9, characterized in that, The control of the active power output of the virtual synchronous generator based on the per-unit value of the power regulation amount of the virtual synchronous generator includes: Substitute the per-unit value of the power regulation of the virtual synchronous generator into the VSG mathematical control model to obtain the per-unit value of the active power output of the virtual synchronous generator. The active power output per unit value of the virtual synchronous generator is converted into the active power output value of the virtual synchronous generator, and the active power output of the virtual synchronous generator is controlled to be the active power output value of the virtual synchronous generator.

16. The system as described in claim 15, characterized in that, The VSG mathematical control model is determined by the following formula: In the formula, δ VSG The phase angle difference between the internal potential of the virtual synchronous generator and the grid voltage. ω is the per-unit value of the virtual angular velocity of the virtual synchronous generator. n θ is the rated angular velocity of the virtual synchronous generator. pcc H is the phase angle of the grid voltage, θ is the phase angle of the internal electromotive force of the virtual synchronous generator, and H is the phase angle of the grid voltage. JVSG The inertial time constant of the virtual synchronous generator. This is the per-unit value of the active power reference value output by the virtual synchronous generator. This represents the per-unit value of the active power output of the virtual synchronous generator. This represents the per-unit value of the power regulation of the virtual synchronous generator. Virtual damping coefficient, E per unit * This represents the per-unit value of the effective internal potential of the virtual synchronous generator. Per-unit value of the effective phase voltage at the grid connection point of the virtual synchronous generator. This refers to the impedance of the inverter's commutator reactor.

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