Voltage support control methods, devices, systems and storage media for grid-connected power generation systems

Abstract

This invention discloses a voltage support control method, device, system, and storage medium for a grid-connected power generation system. It achieves precise regulation of the grid connection point voltage through an adaptive voltage feedforward compensation control strategy, eliminating voltage dips caused by line impedance and providing rapid dynamic response to external faults, effectively improving the system's voltage support capability. Simultaneously, a virtual negative impedance control strategy improves the system's impedance characteristics, suppressing active and reactive power output coupling caused by line impedance. This method can achieve dynamic support of the grid connection point voltage under conditions of sudden local load changes, effectively improving the stability of reactive voltage support under fault conditions. This invention can be widely applied to power generation systems based on grid-connected inverters.

Description

Technical Field

[0001] This invention relates to the field of new energy power generation technology, and in particular to a voltage support control method, device, system and storage medium for grid-type power generation systems. Background Technology

[0002] Existing grid-connected power generation technologies still face many problems when considering line impedance: when the line impedance is resistive and inductive, the active and reactive power output of the grid-connected inverter are coupled, making it difficult to achieve precise frequency and voltage control. Furthermore, the real-time reactive power output of the grid-connected inverter is limited due to the voltage drop caused by the line impedance, and the performance of regulating the grid connection point voltage is significantly weakened. When dealing with real-time changing load conditions, grid-connected power generation technology faces difficulties in achieving voltage support control due to the influence of line impedance.

[0003] CN118523341A provides a transient reactive voltage control method and system for new energy-storage power generation systems, which improves the transient reactive voltage support capability of grid-connected new energy-storage power generation systems. However, this method does not fully consider the impact of transmission line impedance on the reactive voltage support of grid-connected new energy power generation systems. Due to the voltage drop caused by line impedance, there is a voltage deviation between the real-time voltage at the grid connection point and the real-time voltage at the generator terminal. This means that in practical applications, this method requires additional measurements of the real-time voltage and current at the grid connection point, as well as line impedance and grid impedance. This over-reliance on measurement accuracy also results in high costs for signal measurement and transmission. When considering line impedance, to achieve ideal reactive voltage support, the reference value of the generator terminal voltage must be greater than the real-time voltage at the grid connection point. Therefore, the grid-connected power generation system is required to have autonomous adjustment capability for its own generator terminal output voltage to cope with complex external faults and unknown line impedance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a voltage support control method, device, system and storage medium for grid-connected power generation systems, which addresses the shortcomings of the prior art and eliminates the need for additional measurement of real-time voltage and current at the grid connection point, as well as line impedance and grid impedance, thereby effectively improving the voltage support capability of the system.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a voltage support control method for a grid-connected power generation system, wherein the grid-connected power generation system includes a grid-connected inverter and a local load, the grid-connected inverter is connected to the local load, and the grid-connected inverter is connected to the power grid; comprising the following steps:

[0006] Using the given active power P of the grid-connected inverter set The power angle θ of the grid-type inverter is calculated based on the actual active power P.

[0007] Using the given reactive power Q of the grid-type inverter set Actual reactive power Q and adaptive voltage feedforward compensation coefficient K u Calculate the virtual internal electromotive force reference value E ref ;

[0008] Using the work angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U for phases a, b, and c of the grid-connected inverter. ref_a U ref_b U ref_c Based on the virtual voltage reference value U of phases a, b, and c of the grid-connected inverter ref_a U ref_b U ref_c The PWM modulation waveforms e of the three phases a, b, and c of the grid-type inverter are obtained. a e b e c ;

[0009] The PWM modulation waveform of phases a, b, and c of the grid-connected inverter. a e b e c The switching transistors of the grid-type inverter are modulated with a triangular carrier wave using PWM to obtain the duty cycle signal of the switching transistors, thereby controlling the switching on and off of the grid-type inverter.

[0010] This invention utilizes the angle of attack and adaptive voltage feedforward compensation coefficient to determine the virtual internal electromotive force reference value, thereby obtaining a three-phase PWM modulation wave and realizing the on / off control of the switching transistors of the grid-connected inverter. The control process does not require additional measurement of the real-time voltage and current at the grid connection point, as well as the line impedance and grid impedance. This enables the grid-connected inverter to achieve autonomous adjustment of the output voltage at the generator terminal under unknown external faults and line impedance conditions, thereby achieving an ideal voltage support effect.

[0011] Using the given reactive power Q of the grid-type inverter set Actual reactive power Q and adaptive voltage feedforward compensation coefficient K u Calculate the virtual internal electromotive force reference value E ref The specific implementation process includes: utilizing the given reactive power Q of the grid-type inverter set The actual reactive power Q is used to obtain the adaptive voltage feedforward compensation coefficient K. u Using the actual reactive power Q and the voltage feedforward compensation coefficient K u The virtual inductance value L of the grid-connected inverter v Calculate the adaptive voltage compensation amount ΔU, and then calculate the virtual internal electromotive force E of the grid-type inverter. mThe virtual internal electromotive force reference value E of the grid-type inverter after adaptive voltage compensation is obtained by summing the value with the adaptive voltage compensation amount ΔU. ref ;in, ω n V is the rated angular frequency of the power grid. n This refers to the rated phase voltage amplitude of the power grid.

[0012] This invention eliminates the voltage drop at the grid connection point caused by line impedance voltage drop by setting an adaptive voltage feedforward compensation control strategy, optimizes the precise voltage regulation performance of the system, and thus achieves precise regulation of the grid connection point voltage. The real-time reactive power output of the system is guaranteed, and it has a rapid dynamic response to external faults. Therefore, the stability of reactive voltage support under local load change conditions is effectively improved, and the voltage support capability of the system is effectively enhanced. At the same time, the virtual negative impedance control strategy improves the impedance characteristics of the system and suppresses the coupling of active and reactive power output caused by line impedance.

[0013] The PWM modulation waveforms e of phases a, b, and c of the grid-type inverter a e b e c The specific acquisition process includes:

[0014] Using the work angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U for phases a, b, and c of the grid-connected inverter. ref_a U ref_b U ref_c The virtual voltage reference value U of phases a, b, and c of the grid-connected inverter is... ref_a U ref_b U ref_c After coordinate transformation, the virtual voltage reference value U of the grid-type inverter in the dq coordinate system is obtained. ref_d U ref_q ;U ref_d U ref_q These are the virtual voltage reference values ​​for the d-axis and q-axis, respectively.

[0015] The virtual voltage reference value U in the dq coordinate system ref_d U ref_q After passing through virtual negative impedance control, the actual voltage reference value U of the grid-type inverter after introducing virtual negative impedance is obtained. pwm_d U pwm_q ;U pwm_d U pwm_q These are the actual voltage reference values ​​for the d-axis and q-axis, respectively.

[0016] The actual voltage reference value U pwm_d U pwm_qAfter coordinate transformation, the PWM modulation waveforms e of phases a, b, and c of the grid-type inverter are obtained. a e b e c .

[0017] Virtual internal electromotive force E m The calculation formula is as follows: V n V and V represent the rated phase voltage amplitude of the grid and the output phase voltage amplitude of the grid-connected inverter, respectively; K is the voltage regulation coefficient of the grid-connected inverter; s is the Laplace transform factor; D q is the reactive voltage damping coefficient of the grid-type inverter.

[0018] Adaptive adjustment of voltage feedforward compensation coefficient K u The calculation formula is:

[0019] K u =K u0 +α(Q set -Q);

[0020] Among them, K u0 α is the initial value of the adaptive voltage feedforward compensation coefficient, and α is the adaptive sensitivity factor.

[0021] Initial value of adaptive voltage feedforward compensation coefficient ΔU Lmax ω is the maximum permissible limit for line impedance voltage drop. n V is the rated angular frequency of the power grid. n This refers to the rated phase voltage amplitude of the power grid.

[0022] Adaptive sensitivity factor ω n V is the rated angular frequency of the power grid. n This refers to the rated phase voltage amplitude of the power grid.

[0023] The formula for calculating the work angle θ is as follows:

[0024] Modulated wave e a e b e c The calculation formula is:

[0025]

[0026] Among them, U pwm_d U pwm_q These are the actual voltage reference values ​​for the d and q axes, respectively.

[0027] Preferably, d-axis and q-axis virtual impedance voltage U v_d Uv_q The calculation formula is: U ref_d U ref_q These are the virtual voltage reference values ​​for the d and q axes of the grid-connected inverter, respectively. inv_d I inv_q These are the actual output currents of the d and q axes, respectively, R v L represents the virtual negative resistance value of the grid-connected inverter. v ω is the virtual inductance value of the grid-connected inverter, and ω is the output angular frequency of the grid-connected inverter.

[0028] This invention improves the impedance characteristics of grid-connected new energy power generation systems by setting a virtual negative impedance control strategy, solves the problem of active and reactive power output coupling caused by line impedance in grid-connected inverters, helps to achieve precise frequency and voltage control, and further enhances the stability of system operation.

[0029] As an inventive concept, the present invention also provides a voltage support control device for a grid-connected power generation system, comprising:

[0030] Angle of attack calculation unit, used to calculate the given active power P of the grid-type inverter. set The power angle θ of the grid-type inverter is calculated based on the actual active power P.

[0031] The virtual internal electromotive force reference calculation unit is used to calculate the given reactive power Q of the grid-type inverter. set Actual reactive power Q and adaptive voltage feedforward compensation coefficient K u Calculate the virtual internal electromotive force reference value E ref ;

[0032] The three-phase modulation wave calculation unit is used to calculate the power angle θ and the virtual internal electromotive force reference value E. ref Calculate the virtual voltage reference value U for phases a, b, and c of the grid-connected inverter. ref_a U ref_b U ref_c Based on the virtual voltage reference value U of phases a, b, and c of the grid-connected inverter ref_a U ref_b U ref_c The three-phase PWM modulation waveforms e of the grid-type inverter (a, b, c) are obtained. a e b e c ;

[0033] The modulation unit is used to modulate the PWM waveforms of phases a, b, and c of the grid-type inverter. a e b e cThe switching transistors of the grid-type inverter are modulated with a triangular carrier wave using PWM to obtain the duty cycle signal of the switching transistors, thereby controlling the switching on and off of the grid-type inverter.

[0034] In the aforementioned device, the virtual internal electromotive force (EMF) reference value calculation unit calculates the virtual internal EMF reference value E. ref The specific implementation process includes: utilizing the given reactive power Q of the grid-type inverter set Actual reactive power Q and adaptive voltage feedforward compensation coefficient K u Using the actual reactive power Q and the voltage feedforward compensation coefficient K u The virtual inductance value L of the grid-connected inverter v Calculate the adaptive voltage compensation amount ΔU, and then calculate the virtual internal electromotive force E of the grid-type inverter. m The virtual internal electromotive force reference value E of the grid-type inverter after adaptive voltage compensation is obtained by summing the value with the adaptive voltage compensation amount ΔU. ref ;in, ω n V is the rated angular frequency of the power grid. n This refers to the rated phase voltage amplitude of the power grid.

[0035] In the aforementioned device, the three-phase modulation wave calculation unit utilizes the power angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U for phases a, b, and c of the grid-connected inverter. ref_a U ref_b U ref_c The virtual voltage reference value U of phases a, b, and c of the grid-connected inverter is... ref_a U ref_b U ref_c After coordinate transformation, the virtual voltage reference value U of the grid-type inverter in the dq coordinate system is obtained. ref_d U ref_q ;U ref_d U ref_q These are the virtual voltage reference values ​​for the d-axis and q-axis, respectively.

[0036] The virtual voltage reference value U in the dq coordinate system ref_d U ref_q After passing through virtual negative impedance control, the actual voltage reference value U of the grid-type inverter after introducing virtual negative impedance is obtained. pwm_d U pwm_q ;U pwm_d U pwm_q These are the actual voltage reference values ​​for the d-axis and q-axis, respectively.

[0037] The actual voltage reference value U pwm_d U pwm_qAfter coordinate transformation, the PWM modulation waveforms e of phases a, b, and c of the grid-type inverter are obtained. a e b e c .

[0038] Virtual internal electromotive force E m The calculation formula is as follows: V n V and V represent the rated phase voltage amplitude of the grid and the output phase voltage amplitude of the grid-connected inverter, respectively; K is the voltage regulation coefficient of the grid-connected inverter; s is the Laplace transform factor; D q is the reactive voltage damping coefficient of the grid-type inverter.

[0039] Adaptive adjustment of voltage feedforward compensation coefficient K u The calculation formula is:

[0040] K u =K u0 +α(Q set -Q);

[0041] Among them, K u0 α is the initial value of the adaptive voltage feedforward compensation coefficient, and α is the adaptive sensitivity factor.

[0042] Initial value of adaptive voltage feedforward compensation coefficient ΔU Lmax ω is the maximum permissible limit for line impedance voltage drop. n V is the rated angular frequency of the power grid. n This refers to the rated phase voltage amplitude of the power grid.

[0043] Adaptive sensitivity factor ω n V is the rated angular frequency of the power grid. n This refers to the rated phase voltage amplitude of the power grid.

[0044] The formula for calculating the work angle θ is as follows:

[0045] Modulated wave e a e b e c The calculation formula is:

[0046]

[0047] Among them, U pwm_d U pwm_q These are the actual voltage reference values ​​for the d and q axes, respectively.

[0048] Preferably, d-axis and q-axis virtual impedance voltage U v_d Uv_q The calculation formula is: U ref_d U ref_q These are the virtual voltage reference values ​​for the d and q axes of the grid-connected inverter, respectively. inv_d I inv_q These are the actual output currents of the d and q axes, respectively, R v L represents the virtual negative resistance value of the grid-connected inverter. v ω represents the virtual inductance value of the grid-connected inverter, and ω is the output angular frequency of the grid-connected inverter. As an inventive concept, this invention also provides a voltage support control system for a grid-connected power generation system, including a memory, a processor, and a computer program stored in the memory; the processor executes the computer program to implement the steps of the above method.

[0049] As an inventive concept, the present invention also provides a computer-readable storage medium having a computer program / instructions stored thereon; when the computer program / instructions are executed by a processor, they implement the steps of the above-described method.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0051] 1. This invention eliminates the need for additional measurement of real-time voltage and current at the grid connection point, as well as line impedance and grid impedance, enabling the grid-connected inverter to autonomously adjust the output voltage at the generator terminal under unknown external faults and line impedance conditions, thereby achieving an ideal voltage support effect.

[0052] 2. This invention achieves precise regulation of the grid connection point voltage through an adaptive voltage feedforward compensation control strategy, eliminating the voltage drop at the grid connection point caused by line impedance, and has a rapid dynamic response to external faults, effectively improving the voltage support capability of the system.

[0053] 3. The virtual negative impedance control strategy improves the impedance characteristics of the system and suppresses the coupling of active and reactive power output caused by line impedance. This method can achieve dynamic support for the grid connection point voltage under local load change conditions, and effectively improve the stability of reactive voltage support under fault conditions. Attached Figure Description

[0054] Figure 1 A flowchart illustrating a preferred embodiment of the voltage support control method for a grid-connected power generation system with rapid dynamic response according to the present invention;

[0055] Figure 2 This is a circuit and control system structure diagram of a preferred embodiment of the grid-type power generation system of the present invention;

[0056] Figure 3This is a control block diagram of a grid-connected power generation system voltage support control method with fast dynamic response, according to a preferred embodiment of the present invention.

[0057] Figure 4 A comparison diagram of the voltage changes at the grid connection point under local load surge conditions between the conventional control and the proposed voltage support control in a preferred embodiment of the present invention.

[0058] Figure 5 A comparison diagram of the reactive power output of a grid-type inverter under conditions of sudden local load increase, showing the conventional control and the proposed voltage support control in a preferred embodiment of the present invention. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0060] Example 1

[0061] See Figure 1 This embodiment provides a voltage support control method for a grid-connected power generation system with fast dynamic response, applied to a grid-connected power generation system including a grid-connected inverter and local loads. The grid-connected inverter is connected to the local loads via a common coupling point and is connected to the power grid. The method of this embodiment includes:

[0062] S1. Initialize the relevant characteristic parameters of the system operation and collect and update the system electrical quantity information in real time;

[0063] S2. Utilizing the given active power P of the grid-type inverter set The power angle θ of the grid-connected inverter is calculated using the actual active power P, and the given reactive power Q of the grid-connected inverter is used. set The actual reactive power Q is used to calculate the virtual internal electromotive force E of the grid-type inverter. m ;

[0064] S3, the virtual internal electromotive force E m After applying the adaptive voltage feedforward compensation control strategy, the virtual internal electromotive force reference value E of the grid-type inverter after adaptive voltage compensation is obtained. ref ;

[0065] S4. Using the work angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U of the grid-type inverter. ref_abcThe virtual voltage reference value U of the grid-type inverter in the dq coordinate system is obtained through coordinate transformation. ref_dq ;

[0066] S5. Set the virtual voltage reference value U in the dq coordinate system. ref_dq After employing a virtual negative impedance control strategy, the actual voltage reference value U of the grid-type inverter after introducing virtual negative impedance is obtained. pwm_dq ;

[0067] S6, Set the actual voltage reference value U pwm_dq The PWM modulation wave e of the grid-type inverter is obtained after coordinate transformation. abc , modulate the wave e _abc The triangular carrier wave passes through the PWM modulation module of the controller to obtain the duty cycle signal of the switching transistor of the grid inverter. Then, through the drive protection circuit, the switching transistor of the grid inverter is controlled to turn on and off.

[0068] The voltage support control method described above achieves precise regulation of the grid connection point voltage through an adaptive voltage feedforward compensation control strategy, eliminating voltage dips at the grid connection point caused by line impedance and providing rapid dynamic response to external faults, effectively improving the system's voltage support capability. Simultaneously, it employs a virtual negative impedance control strategy to improve the system's impedance characteristics, suppressing the coupling of active and reactive power output caused by line impedance. This method can achieve dynamic support of the grid connection point voltage under local load change conditions, effectively improving the stability of reactive voltage support under fault conditions.

[0069] Optionally, in step S2, the work angle θ and the virtual internal electromotive force E m The calculation formula satisfies the following relationship:

[0070]

[0071] Where, ω n ω and V are the rated angular frequency of the power grid and the output angular frequency of the grid-type inverter, respectively. n V and D are the rated phase voltage amplitude of the grid and the output phase voltage amplitude of the grid-connected inverter, respectively. p and D q , respectively, are the active frequency damping coefficient and reactive voltage damping coefficient of the grid-type inverter, J and K are the virtual inertia coefficient and voltage regulation coefficient of the grid-type inverter, respectively, and s is the Laplace transform factor.

[0072] This invention improves the damping and inertia of the grid-connected power generation system by setting up virtual synchronous generator (VSG) control as a grid-connected power generation control strategy, supports the stable operation of the system under weak grid conditions, and enables the system to have frequency and voltage support capabilities during power generation and grid connection.

[0073] In step S3, the implementation process of the adaptive voltage feedforward compensation control strategy includes: utilizing the given reactive power Q of the grid-type inverter set Actual reactive power Q adaptive adjustment voltage feedforward compensation coefficient K u Combined with the virtual inductance value L of the grid-type inverter v Calculate the adaptive voltage compensation amount ΔU, and finally, calculate the virtual internal electromotive force E of the grid-type inverter. m The virtual internal electromotive force reference value E of the grid-type inverter after adaptive voltage compensation is obtained by summing the value with the adaptive voltage compensation amount ΔU. ref .

[0074] Voltage feedforward compensation coefficient K u The parameter adaptive control introduces an adaptive sensitivity factor α, based on the given reactive power Q. set Adjust the voltage feedforward compensation coefficient K based on the real-time deviation from the actual reactive power Q. u Size, K u The calculation formula satisfies the following relationship:

[0075] K u =K u0 +α(Q set -Q)

[0076] Among them, K u0 This represents the initial value of the adaptive voltage feedforward compensation coefficient.

[0077] The formula for calculating the adaptive voltage compensation amount ΔU satisfies the following relationship:

[0078]

[0079] Virtual internal electromotive force reference value E ref The calculation formula satisfies the following relationship:

[0080] E ref =E m +ΔU

[0081] This invention eliminates the voltage drop at the grid connection point caused by line impedance voltage drop by setting an adaptive voltage feedforward compensation control strategy, optimizes the precise voltage regulation performance of the system, and thus achieves precise regulation of the grid connection point voltage. At this time, the real-time reactive power output of the system is guaranteed, and it has a rapid dynamic response to external faults. Therefore, the stability of reactive voltage support under local load change conditions is effectively improved.

[0082] In step S5, the implementation process of the virtual negative impedance control strategy is as follows: utilizing the virtual negative resistance value R of the grid-connected inverter... v Virtual inductance value Lv With actual output current I inv_dq Calculate the virtual impedance voltage U v_dq Finally, the virtual voltage reference value U of the grid-connected inverter is... ref_dq With virtual impedance voltage U v_dq By performing a difference operation, the actual voltage reference value U of the grid-type inverter after introducing virtual negative impedance is obtained. pwm_dq .

[0083] Virtual impedance voltage U v_dq The calculation formula satisfies the following relationship:

[0084]

[0085] Actual voltage reference value U pwm_dq The calculation formula satisfies the following relationship:

[0086]

[0087] This invention improves the impedance characteristics of grid-connected power generation systems by setting a virtual negative impedance control strategy, solves the problem of active and reactive power output coupling caused by line impedance in grid-connected inverters, helps to achieve precise frequency and voltage control, and further enhances the stability of system operation.

[0088] like Figure 2 As shown, the grid-connected power generation system structure of this embodiment includes two parts: a circuit structure and a control system. In the circuit structure, the grid-connected inverter adopts a two-level three-phase bridge circuit topology. Furthermore, the AD sampling circuit samples the output voltage U of the grid-connected inverter. inv_abc The output current I of the grid-connected inverter inv_abc Sampling is performed, and the data converted by the AD sampling circuit is sent to the DSP controller for processing. dc It is the DC bus capacitor, L f It is a filter inductor, C f It is a filter capacitor, Z line It is the grid connection point voltage, U pcc It is the grid connection point voltage, Z g It is the power grid impedance, U g It is the grid voltage; the control system includes grid-connected inverter control, and the control system's e abc The PWM modulation wave signal for the grid-type inverter is used to obtain the trigger pulse T of each switch in the grid-type inverter through carrier PWM modulation, thereby controlling the switching on and off of the switch.

[0089] Figure 3This is a control block diagram of a grid-connected power generation system voltage support control method with fast dynamic response, according to an embodiment of the present invention. Based on the proposed grid-connected power generation system voltage support control method with fast dynamic response, adaptive voltage feedforward compensation control and virtual negative impedance control are added to the virtual synchronous generator (VSG) control. At the beginning of each sampling period, the sampled U... inv_abc I inv_abc The output voltage U of the grid-type inverter in the αβ coordinate system is obtained by calculating based on the transformation formula from the abc stationary coordinate system to the αβ coordinate system. inv_α U inv_β With the output current I of the grid-connected inverter inv_α I inv_β And by U inv_α U inv_β I inv_α I inv_β The real-time active power P, real-time power Q, and output phase voltage amplitude V of the grid-connected inverter are calculated. The calculation process is as follows:

[0090]

[0091] The given active power P of the grid-connected inverter set The power angle θ of the grid-connected inverter is calculated from the actual active power P through the active power control loop, and the given reactive power Q of the grid-connected inverter is also calculated. set The actual reactive power Q is used to calculate the virtual internal electromotive force E of the grid-type inverter through the reactive power control loop. m θ and E m The calculation formula satisfies the following relationship:

[0092]

[0093] Wherein, given active power P set and given reactive power Q set The task of outputting energy is directly assigned by the superior through instructions based on whether it is productive or reactive. n ω and V are the rated angular frequency of the power grid and the output angular frequency of the grid-connected inverter, respectively. n V and D are the rated phase voltage amplitude of the grid and the output phase voltage amplitude of the grid-connected inverter, respectively. p and D q , respectively, are the active frequency damping coefficient and reactive voltage damping coefficient of the grid-connected inverter, J and K are the virtual inertia coefficient and voltage regulation coefficient of the grid-connected inverter, respectively, and s is the Laplace transform factor.

[0094] The virtual internal electromotive force E m After applying the adaptive voltage feedforward compensation control strategy, the virtual internal electromotive force reference value E of the grid-type inverter after adaptive voltage compensation is obtained.ref The specific implementation process is as follows:

[0095] Voltage feedforward compensation coefficient K u The parameter adaptive control introduces an adaptive sensitivity factor α, based on the given reactive power Q. set Adjust the voltage feedforward compensation coefficient K based on the real-time deviation from the actual reactive power Q. u Size, K u The calculation formula satisfies the following relationship:

[0096] K u =K u0 +α(Q set -Q)

[0097] Among them, K u0 α is the initial value of the adaptive voltage feedforward compensation coefficient, and α is the adaptive sensitivity factor.

[0098] Combined with the virtual inductance value L of the grid-connected inverter v The adaptive voltage compensation amount ΔU is calculated, and the formula for calculating ΔU satisfies the following relationship:

[0099]

[0100] Finally, the virtual internal electromotive force E of the grid-connected inverter is... m The virtual internal electromotive force reference value E of the grid-type inverter after adaptive voltage compensation is obtained by summing the value with the adaptive voltage compensation amount ΔU. ref E ref The calculation formula satisfies the following relationship:

[0101] E ref =E m +ΔU;

[0102] The above process generates a virtual internal electromotive force reference value E based on an adaptive voltage feedforward compensation control strategy. ref The specific implementation process.

[0103] Using the work angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U of the grid-type inverter. ref_abc U ref_abc The calculation formula satisfies the following relationship:

[0104]

[0105] The virtual voltage reference value U ref_abc The virtual voltage reference value U of the grid-type inverter in the dq coordinate system is obtained after coordinate transformation. ref_dq U ref_dqThe calculation formula satisfies the following relationship:

[0106]

[0107] The virtual voltage reference value U in the dq coordinate system ref_dq After employing a virtual negative impedance control strategy, the actual voltage reference value U of the grid-type inverter after introducing virtual negative impedance is obtained. pwm_dq The specific implementation process is as follows:

[0108] Using the virtual negative resistance value R of the grid-connected inverter v Virtual inductance value L v With actual output current I inv_dq Calculate the virtual impedance voltage U v_dq Virtual impedance voltage U v_dq The calculation formula satisfies the following relationship:

[0109]

[0110] Finally, the virtual voltage reference value U of the grid-type inverter is... ref_dq With virtual impedance voltage U v_dq By performing a subtraction operation, the actual voltage reference value U of the grid-type inverter after introducing virtual negative impedance is obtained. pwm_dq U pwm_dq The calculation formula satisfies the following relationship:

[0111]

[0112] The above process generates the actual voltage reference value U based on the virtual negative impedance control strategy. pwm_dq The specific implementation process.

[0113] The actual voltage reference value U pwm_dq The PWM modulation signal e of the grid-type inverter is obtained after coordinate transformation. abc e abc The calculation formula satisfies the following relationship:

[0114]

[0115] modulated wave e _abc The triangular carrier wave passes through the PWM modulation module of the controller to obtain the duty cycle signal of the switching transistor of the grid inverter. Then, through the drive protection circuit, the switching transistor of the grid inverter is controlled to turn on and off.

[0116] Figure 4 The voltage support control proposed in this invention, compared with conventional control, was used to measure the grid connection point voltage U under conditions of sudden local load increases. pcc The changes. From Figure 4It can be seen that under the traditional control method, a significant voltage drop occurs when the local load suddenly increases, and the grid connection point voltage cannot be controlled at the rated voltage under steady state. Under the voltage support control method proposed in this embodiment of the invention, no voltage drop occurs when the local load suddenly increases, the system smoothly transitions to the new steady-state operating point, and the grid connection point voltage is controlled at the rated voltage before and after the load surge, indicating that the voltage support control method proposed in this embodiment of the invention has better voltage support capability.

[0117] Figure 5 The changes in reactive power Q of a grid-connected inverter under conditions of sudden local load surge were compared between conventional control and the voltage support control proposed in this embodiment of the invention. Figure 5 It can be seen that under the traditional control method, the reactive power compensation response speed is slow when the local load suddenly increases, and there is a significant shortage of reactive power output before and after the local load surge. Under the voltage support control method proposed in this embodiment of the invention, the system quickly compensates for reactive power and establishes a new steady-state operating point when the local load suddenly increases, and the reactive power output under steady state can meet the real-time changing local load demand. This also shows that the voltage support control method proposed in this embodiment of the invention has a fast dynamic response under local load change conditions.

[0118] In summary, the voltage support control method for grid-connected power generation systems with rapid dynamic response provided by this invention achieves precise regulation of the grid connection point voltage, optimizes the system's precise voltage and frequency regulation performance during grid-connected operation, and provides rapid dynamic response to external faults, effectively improving the system's voltage support capability. Furthermore, this invention also considers the decoupling of active and reactive power output from the grid-connected inverter, improving the system's impedance characteristics and enhancing its operational stability. In step S3, this invention incorporates an adaptive voltage feedforward compensation control strategy, effectively improving the stability of reactive voltage support under fault conditions to adapt to the complex operating conditions after large-scale power generation integration. Example 2

[0119] This embodiment provides a voltage support control device for a grid-connected power generation system, including:

[0120] Angle of attack calculation unit, used to calculate the given active power P of the grid-type inverter. set Calculate the power angle θ of the grid-type inverter based on the actual active power P; ω n ω and D are the rated angular frequency of the power grid and the output angular frequency of the grid-type inverter, respectively. p and D q , respectively, are the active frequency damping coefficient and reactive voltage damping coefficient of the grid-type inverter, J and K are the virtual inertia coefficient and voltage regulation coefficient of the grid-type inverter, respectively, and s is the Laplace transform factor;

[0121] The virtual internal potential calculation unit is used to calculate the given reactive power Q of the grid-connected inverter. set The actual reactive power Q is calculated to determine the virtual internal electromotive force E of the grid-type inverter. m ; V is the output phase voltage amplitude of the grid-connected inverter. n This refers to the rated phase voltage amplitude of the power grid.

[0122] The virtual internal electromotive force reference calculation unit is used to calculate the given reactive power Q of the grid-connected inverter. set Actual reactive power Q adaptive adjustment voltage feedforward compensation coefficient K u Using the actual reactive power Q and the voltage feedforward compensation coefficient K u The virtual inductance value L of the grid-connected inverter v Calculate the adaptive voltage compensation amount ΔU; K u =K u0 +α(Q set -Q), ω n K is the rated angular frequency of the power grid. u0 Let α be the initial value of the adaptive voltage feedforward compensation coefficient, and α be the adaptive sensitivity factor. ΔU Lmax The maximum permissible limit for line impedance voltage drop; adaptive sensitivity factor. The virtual internal electromotive force E of the grid-type inverter m The virtual internal electromotive force reference value E of the grid-type inverter after adaptive voltage compensation is obtained by summing the value with the adaptive voltage compensation amount ΔU. ref ;

[0123] The three-phase modulation wave calculation unit is used to calculate the power angle θ and the virtual internal electromotive force reference value E. ref Calculate the virtual voltage reference value U for phases a, b, and c of the grid-connected inverter. ref_a U ref_b U ref_c The virtual voltage reference values ​​Uref_a, Uref_b, and Uref_c of the three phases a, b, and c of the grid-connected inverter are transformed by coordinates to obtain the virtual voltage reference value U of the grid-connected inverter in the dq coordinate system. ref_d U ref_q ;U ref_d U ref_q These are the virtual voltage reference values ​​for the d-axis and q-axis, respectively; the virtual voltage reference value U in the dq coordinate system... ref_d U ref_qAfter passing through virtual negative impedance control, the actual voltage reference value U of the grid-type inverter after introducing virtual negative impedance is obtained. pwm_d U pwm_q ;U pwm_d U pwm_q These are the actual voltage reference values ​​for the d-axis and q-axis, respectively; actual voltage reference value U pwm_d U pwm_q The calculation formula is: Among them, the virtual impedance voltages U on the d and q axes v_d U v_q The calculation formula is: U pwm_d U pwm_q These are the actual voltage reference values ​​for the d and q axes, respectively, U. ref_d U ref_q These are the virtual voltage reference values ​​for the d and q axes of the grid-connected inverter, respectively. inv_d I inv_q These are the actual output currents of the d and q axes, respectively, R v L represents the virtual negative resistance value of the grid-connected inverter. v The virtual inductance value of the grid-connected inverter is ω, where ω is the output angular frequency of the grid-connected inverter; the actual voltage reference value U is used. pwm_d U pwm_q After coordinate transformation, the PWM modulation waveforms e of phases a, b, and c of the grid-type inverter are obtained. a e b e c ;

[0124] The modulation unit is used to perform PWM modulation on the PWM modulation waves ea, eb, ec of the three phases a, b, and c of the grid-type inverter and the triangular carrier wave to obtain the duty cycle signal of the switching transistors of the grid-type inverter, so as to control the switching on and off of the switching transistors of the grid-type inverter; the modulation wave e a e b e c The calculation formula is:

[0125]

[0126] Example 3

[0127] Embodiment 3 of the present invention provides a voltage support control system for a grid-type power generation system corresponding to Embodiment 1 above, including a memory, a processor and a computer program stored in the memory; the processor executes the computer program in the memory to implement the steps of the method in Embodiment 1 above.

[0128] In some implementations, the memory may be high-speed random access memory (RAM), and may also include non-volatile memory, such as at least one disk storage device.

[0129] In other implementations, the processor can be any type of general-purpose processor, such as a central processing unit (CPU) or a digital signal processor (DSP), and there is no limitation here.

[0130] Example 4

[0131] Embodiment 4 of the present invention provides a computer-readable storage medium corresponding to Embodiment 1 above, on which a computer program / instructions are stored. When the computer program / instructions are executed by a processor, they implement the steps of the method of Embodiment 1 above.

[0132] A computer-readable storage medium can be a tangible device that holds and stores instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any combination thereof.

[0133] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0134] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. 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, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0135] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0136] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0137] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A voltage support control method for a grid-connected power generation system, the grid-connected power generation system comprising a grid-connected inverter and a local load, wherein the grid-connected inverter is connected to the local load and the grid-connected inverter is connected to the power grid; characterized in that, Includes the following steps: Using the given active power P of the grid-connected inverter set The power angle θ of the grid-type inverter is calculated based on the actual active power P. Using the given reactive power Q of the grid-type inverter set Actual reactive power Q and adaptive voltage feedforward compensation coefficient K u Calculate the virtual internal electromotive force reference value E ref ; Using the work angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U for phases a, b, and c of the grid-connected inverter. ref_a U ref_b U ref_c Based on the virtual voltage reference value U of phases a, b, and c of the grid-connected inverter ref_a U ref_b U ref_c The three-phase PWM modulation waveforms e of the grid-type inverter (a, b, c) are obtained. a e b e c ; The PWM modulation waveform of phases a, b, and c of the grid-connected inverter. a e b e c The switching transistors of the grid-type inverter are modulated with a triangular carrier wave using PWM to obtain the duty cycle signal of the switching transistors, so as to control the switching transistors of the grid-type inverter to turn on and off. The three-phase PWM modulation waveforms e of the grid-type inverter (a, b, c) a e b e c The specific acquisition process includes: using the work angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U for phases a, b, and c of the grid-connected inverter. ref_a U ref_b U ref_c The virtual voltage reference value U of phases a, b, and c of the grid-connected inverter is... ref_a U ref_b U ref_c After coordinate transformation, the virtual voltage reference value U of the grid-type inverter in the dq coordinate system is obtained. ref_d U ref_q ;U ref_d U ref_q These are the virtual voltage reference values ​​for the d-axis and q-axis, respectively. The virtual voltage reference value U in the dq coordinate system ref_d U ref_q After passing through virtual negative impedance control, the actual voltage reference value U of the grid-type inverter after introducing virtual negative impedance is obtained. pwm_d U pwm_q ; U pwm_d U pwm_q These are the actual voltage reference values ​​for the d-axis and q-axis, respectively. The actual voltage reference value U pwm_d U pwm_q After coordinate transformation, the PWM modulation waveforms e of phases a, b, and c of the grid-type inverter are obtained. a e b e c ; Adaptive adjustment of voltage feedforward compensation coefficient K u The calculation formula is: K u =K u0 +α(Q set -Q); Among them, K u0 α is the initial value of the adaptive voltage feedforward compensation coefficient, and α is the adaptive sensitivity factor. Modulated wave e a e b e c The calculation formula is: Among them, U pwm_d U pwm_q These are the actual voltage reference values ​​for the d and q axes, respectively. d-axis and q-axis virtual impedance voltage U v_d U v_q The calculation formula is: U ref_d U ref_q These are the virtual voltage reference values ​​for the d and q axes of the grid-connected inverter, respectively. inv_d I inv_q These are the actual output currents of the d and q axes, respectively, R v L represents the virtual negative resistance value of the grid-connected inverter. v ω is the virtual inductance value of the grid-connected inverter, and ω is the output angular frequency of the grid-connected inverter.

2. The voltage support control method for a grid-type power generation system according to claim 1, characterized in that, Using the given reactive power Q of the grid-type inverter set Actual reactive power Q and adaptive voltage feedforward compensation coefficient K u Calculate the virtual internal electromotive force reference value E ref The specific implementation process includes: utilizing the given reactive power Q of the grid-type inverter set The actual reactive power Q is used to obtain the adaptive voltage feedforward compensation coefficient K. u Using the actual reactive power Q and the voltage feedforward compensation coefficient K u The virtual inductance value L of the grid-connected inverter v Calculate the adaptive voltage compensation amount ΔU, and then calculate the virtual internal electromotive force E of the grid-type inverter. m The virtual internal electromotive force reference value E of the grid-type inverter after adaptive voltage compensation is obtained by summing the value with the adaptive voltage compensation amount ΔU. ref ;in, ω n V is the rated angular frequency of the power grid. n This refers to the rated phase voltage amplitude of the power grid.

3. The voltage support control method for a grid-type power generation system according to claim 2, characterized in that, Virtual internal electromotive force E m The calculation formula is as follows: V n V and V represent the rated phase voltage amplitude of the grid and the output phase voltage amplitude of the grid-connected inverter, respectively; K is the voltage regulation coefficient of the grid-connected inverter; s is the Laplace transform factor; D q is the reactive voltage damping coefficient of the grid-type inverter.

4. The voltage support control method for a grid-connected power generation system according to claim 1, characterized in that, Initial value of adaptive voltage feedforward compensation coefficient ΔU Lmax ω is the maximum permissible limit for line impedance voltage drop. n V is the rated angular frequency of the power grid. n This refers to the rated phase voltage amplitude of the power grid.

5. The voltage support control method for a grid-type power generation system according to claim 1, characterized in that, Adaptive sensitivity factor ω n V is the rated angular frequency of the power grid. n This refers to the rated phase voltage amplitude of the power grid.

6. The voltage support control method for a grid-connected power generation system according to claim 1, characterized in that, The formula for calculating the work angle θ is as follows: Where, ω n ω and D are the rated angular frequency of the power grid and the output angular frequency of the grid-type inverter, respectively. p is the active frequency damping coefficient of the grid-type inverter, J is the virtual inertia coefficient of the grid-type inverter, and s is the Laplace transform factor.

7. A voltage support control device for a grid-type power generation system, characterized in that, include: Angle of attack calculation unit, used to calculate the given active power P of the grid-type inverter. set The power angle θ of the grid-type inverter is calculated based on the actual active power P. The virtual internal electromotive force reference calculation unit is used to calculate the given reactive power Q of the grid-type inverter. set Actual reactive power Q and adaptive voltage feedforward compensation coefficient K u Calculate the virtual internal electromotive force reference value E ref ; The three-phase modulation wave calculation unit is used to calculate the power angle θ and the virtual internal electromotive force reference value E. ref Calculate the virtual voltage reference value U for phases a, b, and c of the grid-connected inverter. ref_a U ref_b U ref_c Based on the virtual voltage reference value U of phases a, b, and c of the grid-connected inverter ref_a U ref_b U ref_c The PWM modulation waveforms e of the three phases a, b, and c of the grid-type inverter are obtained. a e b e c ; The modulation unit is used to modulate the PWM waveforms of phases a, b, and c of the grid-type inverter. a e b e c The switching transistors of the grid-type inverter are modulated with a triangular carrier wave using PWM to obtain the duty cycle signal of the switching transistors, so as to control the switching transistors of the grid-type inverter to turn on and off. The three-phase PWM modulation waveforms e of the grid-type inverter (a, b, c) a e b e c The specific acquisition process includes: using the work angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U for phases a, b, and c of the grid-connected inverter. refa U refb U refc The virtual voltage reference value U of phases a, b, and c of the grid-connected inverter is... ref_a U ref_b U ref_c After coordinate transformation, the virtual voltage reference value U of the grid-type inverter in the dq coordinate system is obtained. ref_d U ref_q ;U ref_d U ref_q These are the virtual voltage reference values ​​for the d-axis and q-axis, respectively. The virtual voltage reference value U in the dq coordinate system ref_d U ref_q After passing through virtual negative impedance control, the actual voltage reference value U of the grid-type inverter after introducing virtual negative impedance is obtained. pwm_d U pwm_q ;U pwm_d U pwm_q These are the actual voltage reference values ​​for the d-axis and q-axis, respectively. The actual voltage reference value U pwm_d U pwm_q After coordinate transformation, the PWM modulation waveforms e of phases a, b, and c of the grid-type inverter are obtained. a e b e c ; Adaptive adjustment of voltage feedforward compensation coefficient K u The calculation formula is: K u =K u0 +α(Q set -Q); Among them, K u0 α is the initial value of the adaptive voltage feedforward compensation coefficient, and α is the adaptive sensitivity factor. Modulated wave e a e b e c The calculation formula is: Among them, U pwm_d U pwm_q These are the actual voltage reference values ​​for the d and q axes, respectively. d-axis and q-axis virtual impedance voltage U v_d U v_q The calculation formula is: U ref_d U ref_q These are the virtual voltage reference values ​​for the d and q axes of the grid-connected inverter, respectively. inv_d I inv_q These are the actual output currents of the d and q axes, respectively, R v L represents the virtual negative resistance value of the grid-connected inverter. v ω is the virtual inductance value of the grid-connected inverter, and ω is the output angular frequency of the grid-connected inverter.

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