Network construction type power generation system voltage support control method, device and system and storage medium

Abstract

The invention discloses a network construction type power generation system voltage support control method, device and system and a storage medium, accurate adjustment of grid-connected point voltage is realized through an adaptive voltage feed-forward compensation control strategy, grid-connected point voltage drop caused by line impedance is eliminated, rapid dynamic response to external faults is realized, and the network construction type power generation system voltage support control method, device and system is suitable for large-scale popularization and application. The voltage supporting capability of the system is effectively improved; meanwhile, the impedance characteristic of the system is improved by adopting a virtual negative impedance control strategy, and active and reactive power output coupling caused by line impedance is inhibited; according to the method, the dynamic support of the grid-connected point voltage can be realized under the local load sudden change working condition, and the stability of the reactive voltage support under the fault working condition is effectively improved. The method can be widely applied to a power generation system based on a grid-forming inverter.

Description

Technical Field

[0001] The present invention relates to the field of renewable energy power generation technology, and in particular to a method, device, system and storage medium for controlling voltage support of a grid-connected power generation system. Background Art

[0002] The existing grid-connected power generation technology still faces many problems when taking line impedance into account: when the line impedance is resistive and inductive, the active and reactive power output by the grid-connected inverter are coupled with each other, making it difficult to achieve precise control of frequency and voltage. In addition, affected by the line impedance voltage drop, the real-time reactive power output of the grid-connected inverter is limited, and the performance of regulating the grid connection point voltage is significantly weakened. When responding to real-time changing load conditions, affected by the line impedance, it is difficult for the grid-connected power generation technology to achieve voltage support control.

[0003] CN118523341A provides a transient reactive voltage control method and system for a new energy-energy storage power generation system, which improves the transient reactive voltage support capability of a network-type new energy-energy storage power generation system. However, this method does not fully consider the impact of transmission line impedance on the reactive voltage support of a network-type new energy power generation system. Due to the influence of line impedance voltage drop, there is a voltage deviation between the real-time voltage of the grid connection point and the real-time voltage of the machine end, which causes the method to require additional measurement of the real-time voltage, current, line impedance, and grid impedance of the grid connection point in practical applications. While over-relying on measurement accuracy, the cost of signal measurement and transmission is also relatively expensive. When taking into account line impedance, in order to achieve ideal reactive voltage support, it is necessary to keep the machine end voltage reference value greater than the real-time voltage of the grid connection point. Therefore, it is required that the network-type power generation system has the ability to autonomously adjust its own machine end 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 a grid-connected power generation system in view of the shortcomings of the existing technology, which does not require additional measurement of the real-time voltage, current, line impedance and grid impedance of the grid connection point, thereby effectively improving the voltage support capability of the system.

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

[0006] Using the given active power P of the grid-connected inverter set Calculate the power angle θ of the grid-connected inverter based on the actual active power P;

[0007] Using the given reactive power Q of the grid-connected 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 power angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U of the three phases a, b, and c of the grid-connected inverter ref_a , U ref_b , U ref_c , according to the virtual voltage reference value U of the three phases a, b, and c of the grid-connected inverter ref_a , U ref_b , U ref_c , and obtain the PWM modulation wave e of the three phases a, b, and c of the grid-type inverter a 、e b 、e c ;

[0009] The PWM modulation wave e of the three phases a, b, and c of the grid-connected inverter a 、e b 、e c The triangular carrier is PWM modulated to obtain a switch duty cycle signal of the grid-type inverter to control the on and off of the switch of the grid-type inverter.

[0010] The present invention utilizes the angle of attack and the adaptively adjusted voltage feedforward compensation coefficient to determine the virtual internal electromotive force reference value, and then obtains the three-phase PWM modulation wave to realize the on-off control of the switch tube of the grid-connected inverter. The control process does not require additional measurement of the real-time voltage, current, line impedance, and grid impedance of the grid-connected point, so that the grid-connected inverter can realize autonomous adjustment of the machine-end output voltage under the conditions of unknown external faults and line impedance, thereby achieving an ideal voltage support effect.

[0011] Using the given reactive power Q of the grid-connected 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: using the given reactive power Q of the grid-connected 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 voltage feedforward compensation coefficient K u The virtual inductance value L of the grid-connected inverter v Calculate the adaptive voltage compensation ΔU and convert the virtual internal electromotive force E of the grid-connected inverter mThe virtual internal electromotive force reference value E of the grid-type inverter after adaptive voltage compensation is obtained by summing the adaptive voltage compensation value ΔU. ref ;in, ω n is the rated angular frequency of the power grid, V n is the rated phase voltage amplitude of the power grid.

[0012] The present invention eliminates the voltage drop at the grid connection point caused by the line impedance voltage drop by setting an adaptive voltage feedforward compensation control strategy, optimizes the precise voltage regulation performance of the system, thereby achieving precise regulation of the grid connection point voltage. The real-time reactive power output of the system is guaranteed, and it has a fast dynamic response to external faults. Therefore, the stability of the reactive voltage support is effectively improved under the condition of local load mutation, and the voltage support capacity of the system is effectively improved. At the same time, a virtual negative impedance control strategy is adopted to improve the impedance characteristics of the system, and the coupling of active and reactive power output caused by the line impedance is suppressed.

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

[0014] Using the power angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U of the three 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 the three phases a, b, and c of the grid-connected inverter 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 are d-axis virtual voltage reference value and q-axis virtual voltage reference value respectively;

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

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

[0017] Virtual internal electromotive force E m The calculation formula is as follows: V n and V are the rated phase voltage amplitude of the power grid and the output phase voltage amplitude of the grid-type inverter, respectively; K is the voltage regulation coefficient of the grid-type inverter; s is the Laplace transformation factor; D q is the reactive voltage damping coefficient of the grid-connected 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 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 is the maximum allowable limit of line impedance voltage drop, ω n is the rated angular frequency of the power grid, V n is the rated phase voltage amplitude of the power grid.

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

[0023] The calculation formula of the power angle θ is as follows:

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

[0025]

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

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

[0028] The present invention improves the impedance characteristics of the grid-type new energy power generation system by setting a virtual negative impedance control strategy, solves the problem of active and reactive power output coupling of the grid-type inverter caused by line impedance, helps to achieve precise control of frequency and voltage, 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-type power generation system, comprising:

[0030] Angle of attack calculation unit, used to use the given active power P of the grid-connected inverter set Calculate the power angle θ of the grid-connected inverter based on the actual active power P;

[0031] A virtual internal electromotive force reference value calculation unit is used to calculate the given reactive power Q of the grid-connected 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 use the power angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U of the three phases a, b, and c of the grid-connected inverter ref_a , U ref_b , U ref_c , according to the virtual voltage reference value U of the three phases a, b, and c of the grid-connected inverter ref_a , U ref_b , U ref_c , and obtain the three-phase PWM modulation wave e of the grid-type inverter a, b, c a 、e b 、e c ;

[0033] Modulation unit, used to modulate the PWM wave of the three phases a, b, and c of the grid-type inverter a 、e b 、e cThe triangular carrier is PWM modulated to obtain a switch duty cycle signal of the grid-type inverter to control the on and off of the switch of the grid-type inverter.

[0034] In the above device, the virtual internal electromotive force reference value calculation unit calculates the virtual internal electromotive force reference value E ref The specific implementation process includes: using the given reactive power Q of the grid-connected inverter set , actual reactive power Q and adaptive voltage feedforward compensation coefficient K u , using the actual reactive power Q and voltage feedforward compensation coefficient K u The virtual inductance value L of the grid-connected inverter v Calculate the adaptive voltage compensation ΔU and convert the virtual internal electromotive force E of the grid-connected inverter m The virtual internal electromotive force reference value E of the grid-type inverter after adaptive voltage compensation is obtained by summing the adaptive voltage compensation value ΔU. ref ;in, ω n is the rated angular frequency of the power grid, V n is the rated phase voltage amplitude of the power grid.

[0035] In the above device, the three-phase modulation wave calculation unit uses the power angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U of the three 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 the three phases a, b, and c of the grid-connected inverter 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 are d-axis virtual voltage reference value and q-axis virtual voltage reference value respectively;

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

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

[0038] Virtual internal electromotive force E m The calculation formula is as follows: V n and V are the rated phase voltage amplitude of the power grid and the output phase voltage amplitude of the grid-type inverter, respectively; K is the voltage regulation coefficient of the grid-type inverter; s is the Laplace transformation factor; D q is the reactive voltage damping coefficient of the grid-connected 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 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 is the maximum allowable limit of line impedance voltage drop, ω n is the rated angular frequency of the power grid, V n is the rated phase voltage amplitude of the power grid.

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

[0044] The calculation formula of the power angle θ is as follows:

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

[0046]

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

[0048] Preferably, d. q-axis virtual impedance voltage U v_d , Uv_q The calculation formula is: U ref_d , U ref_q are the virtual voltage reference values ​​of the d and q axes of the grid-connected inverter, I inv_d ,I inv_q are the actual output currents of the d and q axes, R v is the virtual negative resistance value of the grid-connected inverter, L v is the virtual inductance value of the grid-type inverter, and ω is the output angular frequency of the grid-type inverter. As an inventive concept, the present invention also provides a grid-type power generation system voltage support control 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 / instruction stored thereon; the computer program / instruction implements the steps of the above method when executed by a processor.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] 1. The present invention does not need to additionally measure the real-time voltage, current, line impedance, and grid impedance of the grid-connected point, so that the grid-connected inverter can autonomously adjust the output voltage of the machine end under the conditions of unknown external faults and line impedance, thereby achieving an ideal voltage support effect;

[0052] 2. The present invention realizes precise regulation of the grid connection point voltage through an adaptive voltage feedforward compensation control strategy, eliminates the grid connection point voltage drop caused by line impedance, and has a fast dynamic response to external faults, effectively improving the voltage support capability of the system;

[0053] 3. The virtual negative impedance control strategy is used to improve the impedance characteristics of the system and suppress the coupling of active and reactive power output caused by line impedance. This method can dynamically support the voltage at the grid connection point under the condition of local load mutation and effectively improve the stability of reactive voltage support under fault conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a flow chart of a voltage support control method of a grid-type power generation system with fast dynamic response according to a preferred embodiment of the present invention;

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

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

[0057] Figure 4 A comparison diagram of grid connection point voltage changes under local load sudden increase conditions between conventional control and the proposed voltage support control according to a preferred embodiment of the present invention;

[0058] Figure 5 This is a comparison diagram of the reactive power output changes of the grid-type inverter under the condition of a sudden increase in local load between the conventional control and the proposed voltage support control of the preferred embodiment of the present invention. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] Example 1

[0061] See also Figure 1 The present embodiment provides a voltage support control method for a grid-type power generation system with fast dynamic response, which is applied to the grid-type power generation system. The grid-type power generation system includes a grid-type inverter and a local load. The grid-type inverter is connected to the local load based on a common coupling point and connected to the power grid. The method of the present embodiment includes:

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

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

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

[0065] S4, using the power angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U of the grid-connected inverter ref_abc, and after coordinate transformation, the virtual voltage reference value U of the grid-type inverter in the dq coordinate system is obtained ref_dq ;

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

[0067] S6, the actual voltage reference value U pwm_dq After coordinate transformation, the PWM modulation wave e of the grid-type inverter is obtained. abc , the modulated wave e _abc The triangular carrier passes through the PWM modulation module of the controller to obtain the switch tube duty cycle signal of the grid-type inverter, and then passes through the driving protection circuit to control the opening and closing of the switch tube of the grid-type inverter.

[0068] The above-mentioned voltage support control method realizes precise regulation of the grid connection point voltage through an adaptive voltage feedforward compensation control strategy, eliminates the grid connection point voltage drop caused by line impedance, and has a fast dynamic response to external faults, effectively improving the voltage support capability of the system; at the same time, a virtual negative impedance control strategy is adopted to improve the impedance characteristics of the system, suppressing the active and reactive power output coupling caused by line impedance; this method can realize dynamic support of the grid connection point voltage under local load mutation conditions, effectively improving the stability of reactive voltage support under fault conditions.

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

[0070]

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

[0072] The embodiment of the present invention improves the damping and inertia of the grid-connected power generation system by setting the virtual synchronous generator VSG control as the grid-connected power generation control strategy, supports the stable operation of the system under weak grid conditions, and enables the system to have the frequency and voltage support capability during the power generation and grid connection process.

[0073] In step S3, the implementation process of the adaptive voltage feedforward compensation control strategy includes: using the given reactive power Q of the grid-connected inverter set , actual reactive power Q adaptively adjusts voltage feedforward compensation coefficient K u , combined with the virtual inductance value L of the grid-connected inverter v Calculate the adaptive voltage compensation ΔU, and finally convert the virtual internal electromotive force E of the grid-type inverter into m The virtual internal electromotive force reference value E of the grid-type inverter after adaptive voltage compensation is obtained by summing the adaptive voltage compensation value ΔU. ref .

[0074] Voltage feedforward compensation coefficient K u The parameter adaptive control introduces the adaptive sensitivity factor α, according to the given reactive power Q set The real-time deviation from the actual reactive power Q adjusts the voltage feedforward compensation coefficient K u The size of K u The calculation formula satisfies the following relationship:

[0075] K u =K u0 +α(Q set -Q)

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

[0077] The calculation formula of 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] The embodiment of the present invention eliminates the voltage drop at the grid connection point caused by the line impedance voltage drop by setting an adaptive voltage feedforward compensation control strategy, optimizes the precise voltage regulation performance of the system, and thus realizes precise regulation of the voltage at the grid connection point; at this time, the real-time reactive power output of the system is guaranteed, and it has a rapid dynamic response to external faults, so the stability of the reactive voltage support under local load mutation conditions is effectively improved.

[0082] In step S5, the implementation process of the virtual negative impedance control strategy is: using the virtual negative resistance value R of the grid-connected inverter v , virtual inductance value Lv The 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 Perform a difference operation to obtain the actual voltage reference value U of the grid-type inverter after the virtual negative impedance is introduced. 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] The embodiment of the present invention improves the impedance characteristics of the grid-type power generation system by setting a virtual negative impedance control strategy, solves the problem of active and reactive power output coupling of the grid-type inverter caused by line impedance, helps to achieve precise control of frequency and voltage, and further enhances the stability of system operation.

[0088] like Figure 2 As shown, the grid-type power generation system structure of the embodiment of the present invention includes two parts: circuit structure and control system. In the circuit structure, the grid-type inverter adopts a two-level three-phase bridge circuit topology. In addition, the AD sampling circuit measures the output voltage U inv_abc , grid-type inverter output current I inv_abc Sampling is performed, and the data converted by the AD sampling circuit is sent to the DSP controller for processing. dc is the DC bus capacitance, L f is the filter inductor, C f is the filter capacitor, Z line is the grid voltage, U pcc is the grid voltage, Z g is the grid impedance, U g is the grid voltage; the control system includes a grid-type inverter control, the control system's e abc It is the PWM modulation wave signal of the grid-type inverter. The trigger pulse T of each switch tube of the grid-type inverter is obtained through carrier PWM modulation to control the opening and closing of the switch tube.

[0089] Figure 3The control block diagram of the voltage support control method of the grid-type power generation system with fast dynamic response according to the embodiment of the present invention is shown in FIG. Based on the proposed voltage support control method of the grid-type power generation system with fast dynamic response, an adaptive voltage feedforward compensation control and a virtual negative impedance control are added on the basis of the virtual synchronous generator VSG control. At the starting point of each sampling period, the sampled U inv_abc ,I inv_abc Based on the transformation formula from the abc stationary coordinate system to the αβ coordinate system, the output voltage U of the grid-type inverter in the αβ coordinate system is obtained. inv_α , U inv_β 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:

[0090]

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

[0092]

[0093] Among them, given active power P set And given reactive power Q set It is directly given by the superior through instructions according to the active and reactive power output tasks, ω n and ω are the rated angular frequency of the grid and the output angular frequency of the grid-connected inverter, respectively. n and V are the rated phase voltage amplitude of the power grid and the output phase voltage amplitude of the grid-connected inverter, respectively. p and D q 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, and s is the Laplace transform factor.

[0094] The virtual internal electromotive force E m After the adaptive voltage feedforward compensation control strategy, the virtual internal electromotive force reference value E of the grid-type inverter after the 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 the adaptive sensitivity factor α, according to the given reactive power Q set The real-time deviation from the actual reactive power Q adjusts the voltage feedforward compensation coefficient K u The size of K u The calculation formula satisfies the following relationship:

[0096] K u =K u0 +α(Q set -Q)

[0097] Among them, K u0 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 Calculate the adaptive voltage compensation ΔU. The calculation formula of ΔU satisfies the following relationship:

[0099]

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

[0101] E ref =E m +ΔU;

[0102] The above process is to generate the virtual internal electromotive force reference value E based on the adaptive voltage feedforward compensation control strategy. ref specific implementation process.

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

[0104]

[0105] The virtual voltage reference value U ref_abc After coordinate transformation, the virtual voltage reference value U of the grid-type inverter in the dq coordinate system is obtained. 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 the virtual negative impedance control strategy is adopted, the actual voltage reference value U of the grid-type inverter is obtained after the virtual negative impedance is introduced. pwm_dq The specific implementation process is as follows:

[0108] Using the virtual negative resistance R of the grid-connected inverter v , virtual inductance value L v The 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-connected inverter is ref_dq With virtual impedance voltage U v_dq Perform a difference operation to obtain the actual voltage reference value U of the grid-type inverter after the introduction of virtual negative impedance. pwm_dq , U pwm_dq The calculation formula satisfies the following relationship:

[0111]

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

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

[0114]

[0115] The modulated wave e _abc The triangle carrier passes through the PWM modulation module of the controller to obtain the switch tube duty cycle signal of the grid-type inverter, and then passes through the drive protection circuit to control the opening and closing of the switch tube of the grid-type inverter.

[0116] Figure 4 The conventional control and the voltage support control proposed in the embodiment of the present invention are compared to each other under the condition of sudden increase of local load. pcc Changes from Figure 4It can be seen that under the traditional control method, an obvious voltage drop phenomenon occurs when the local load suddenly increases, and the grid connection point voltage cannot be controlled at the rated voltage in steady state; under the voltage support control method proposed in the embodiment of the present invention, there is no voltage drop phenomenon when the local load suddenly increases, the system smoothly transitions to a new steady-state operating point, and the grid connection point voltage is controlled at the rated voltage before and after the load sudden increase, indicating that the voltage support control method proposed in the embodiment of the present invention has better voltage support capability.

[0117] Figure 5 The change of reactive power Q output by the grid-type inverter under the condition of sudden increase of local load is compared between the conventional control and the voltage support control proposed in the embodiment of the present 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 an obvious shortage of reactive power before and after the local load suddenly increases; under the voltage support control method proposed in the embodiment of the present invention, the system quickly compensates for the reactive power and establishes a new steady-state operating point when the local load suddenly increases, and the reactive output in the steady state can meet the real-time changing local load requirements. It also shows that the voltage support control method proposed in the embodiment of the present invention has a fast dynamic response under the local load change condition.

[0118] In summary, the voltage support control method for a grid-connected power generation system with fast dynamic response provided by the embodiment of the present invention realizes the precise regulation of the grid-connected point voltage by the grid-connected power generation system, optimizes the precise voltage and frequency regulation performance of the system during the grid-connected operation of power generation, and has a fast dynamic response to external faults, effectively improving the voltage support capability of the system. At the same time, the embodiment of the present invention also considers the decoupling of the active and reactive power output of the grid-connected inverter, improves the impedance characteristics of the system, and enhances the stability of the system operation. In step S3, the embodiment of the present invention is equipped with an adaptive voltage feedforward compensation control strategy, which effectively improves the stability of the reactive voltage support under fault conditions to adapt to the complex operating conditions after large-scale power generation access. 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 use the given active power P of the grid-connected inverter set Calculate the power angle θ of the grid-connected inverter with the actual active power P; ω n and ω are the rated angular frequency of the grid and the output angular frequency of the grid-connected inverter, respectively. p and D q are the active frequency damping coefficient and reactive voltage damping coefficient of the grid-forming inverter, J and K are the virtual inertia coefficient and voltage regulation coefficient of the grid-forming inverter, and s is the Laplace transform factor;

[0121] Virtual internal potential calculation unit, used to utilize the given reactive power Q of the grid-connected inverter set , actual reactive power Q calculation virtual internal electromotive force E of grid-connected inverter m ; V is the output phase voltage amplitude of the grid-type inverter, V n is the rated phase voltage amplitude of the power grid;

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

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

[0124] The modulation unit is used to perform PWM modulation on the PWM modulation waves ea, eb, ec and the triangular carrier of the three-phase grid-type inverter a, b, c to obtain the switch tube duty cycle signal of the grid-type inverter to control the on and off of the switch tube 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-connected power generation system corresponding to the above-mentioned embodiment 1, 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 the above-mentioned embodiment 1.

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

[0129] In some other implementations, the processor may be a central processing unit (CPU), a digital signal processor (DSP), or other general-purpose processors of various types, which are not limited herein.

[0130] Example 4

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

[0132] Computer readable storage media can be tangible devices that hold and store instructions used by instruction execution devices. Computer readable storage media can be, for example, but not limited to, electronic storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any combination thereof.

[0133] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may 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 codes. The schemes in the embodiments of the present invention may be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0134] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0135] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0136] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0137] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A voltage support control method for a grid-type power generation system, wherein the grid-type power generation system comprises a grid-type inverter and a local load, wherein the grid-type inverter is connected to the local load and the grid-type inverter is connected to a power grid; characterized in that: The following steps are involved: Using the given active power P of the grid-connected inverter set Calculate the power angle θ of the grid-connected inverter based on the actual active power P; Using the given reactive power Q of the grid-connected 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 power angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U of the three phases a, b, and c of the grid-connected inverter ref_a , U ref_b , U ref_c , according to the virtual voltage reference value U of the three phases a, b, and c of the grid-connected inverter ref_a , U ref_b , U ref_c , and obtain the three-phase PWM modulation wave e of the grid-type inverter a, b, c a 、e b 、e c ; The PWM modulation wave e of the three phases a, b, and c of the grid-connected inverter a 、e b 、e c The triangular carrier is PWM modulated to obtain a switch duty cycle signal of the grid-type inverter to control the on and off of the switch of the grid-type inverter.

2. The voltage support control method for a grid-connected power generation system according to claim 1, characterized in that: Using the given reactive power Q of the grid-connected 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: using the given reactive power Q of the grid-connected 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 voltage feedforward compensation coefficient K u The virtual inductance value L of the grid-connected inverter v Calculate the adaptive voltage compensation ΔU and convert the virtual internal electromotive force E of the grid-connected inverter m The virtual internal electromotive force reference value E of the grid-type inverter after adaptive voltage compensation is obtained by summing the adaptive voltage compensation value ΔU. ref ;in, ω n is the rated angular frequency of the power grid, V n is the rated phase voltage amplitude of the power grid.

3. The voltage support control method for a grid-connected power generation system according to claim 1, characterized in that: The grid-type inverter a, b, c three-phase PWM modulation wave e a 、e b 、e c The specific acquisition process includes: using the power angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U of the three 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 the three phases a, b, and c of the grid-connected inverter 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 are d-axis virtual voltage reference value and q-axis virtual voltage reference value respectively; The virtual voltage reference value U in the dq coordinate system ref_d , U ref_q After virtual negative impedance control, the actual voltage reference value U of the grid-type inverter after the introduction of virtual negative impedance is obtained. pwm_d , U pwm_q ; U pwm_d , U pwm_q They are the actual voltage reference value of the d-axis and the actual voltage reference value of the q-axis respectively; The actual voltage reference value U pwm_d , U pwm_q After coordinate transformation, the PWM modulation wave e of the three phases a, b, and c of the grid-type inverter is obtained. a 、e b 、e c .

4. 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 and V are the rated phase voltage amplitude of the power grid and the output phase voltage amplitude of the grid-type inverter, respectively; K is the voltage regulation coefficient of the grid-type inverter; s is the Laplace transformation factor; D q is the reactive voltage damping coefficient of the grid-connected inverter.

5. The voltage support control method for a grid-connected power generation system according to claim 1, characterized in that: 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 is the initial value of the adaptive voltage feedforward compensation coefficient, and α is the adaptive sensitivity factor.

6. The voltage support control method for a grid-connected power generation system according to claim 5, characterized in that: Initial value of adaptive voltage feedforward compensation coefficient ΔU Lmax is the maximum allowable limit of line impedance voltage drop, ω n is the rated angular frequency of the power grid, V n is the rated phase voltage amplitude of the power grid.

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

8. The voltage support control method for a grid-connected power generation system according to claim 1, characterized in that: The calculation formula of the power angle θ is as follows: Among them, ω n and ω are the rated angular frequency of the grid and the output angular frequency of the grid-connected 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.

9. The voltage support control method for a grid-connected power generation system according to claim 1, characterized in that: Modulation wave a 、e b 、e c The calculation formula is: Among them, U pwm_d , U pwm_q They are the actual voltage reference values ​​of d and q axes respectively; Preferably, d. q-axis virtual impedance voltage U v_d , U v_q The calculation formula is: U ref_d , U ref_q are the virtual voltage reference values ​​of the d and q axes of the grid-connected inverter, I inv_d ,I inv_q are the actual output currents of the d and q axes, R v is the virtual negative resistance value of the grid-connected inverter, L v is the virtual inductance value of the grid-connected inverter, and ω is the output angular frequency of the grid-connected inverter.

10. A voltage support control device for a grid-type power generation system, characterized in that: include: Angle of attack calculation unit, used to use the given active power P of the grid-connected inverter set Calculate the power angle θ of the grid-connected inverter based on the actual active power P; A virtual internal electromotive force reference value calculation unit is used to calculate the given reactive power Q of the grid-connected 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 use the power angle θ and the virtual internal electromotive force reference value E ref Calculate the virtual voltage reference value U of the three phases a, b, and c of the grid-connected inverter ref_a , U ref_b , U ref_c , according to the virtual voltage reference value U of the three phases a, b, and c of the grid-connected inverter ref_a , U ref_b , U ref_c , and obtain the PWM modulation wave e of the three phases a, b, and c of the grid-type inverter a 、e b 、e c ; Modulation unit, used to modulate the PWM wave of the three phases a, b, and c of the grid-type inverter a 、e b 、e c The triangular carrier is PWM modulated to obtain a switch duty cycle signal of the grid-type inverter to control the on and off of the switch of the grid-type inverter.

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