Dual-power superposition synchronization and feed-forward passive remodeling control method and system for network-forming inverter

Abstract

The invention discloses a dual-power superposition synchronization and feed-forward passive remodeling control method and system for a network-forming inverter, and belongs to the technical field of power electronics, and the method comprises the steps: measuring capacitor voltage, power grid current and inductive current, and calculating actual active power and actual reactive power; calculating an error signal based on the reactive power reference and the actual reactive power, feeding the error signal forward to an active power controller through a dual-power superposition branch, and calculating a reference angle; calculating a voltage amplitude based on the active power reference and the actual active power; performing coordinate transformation on the power grid current to obtain transformed power grid current, and obtaining an inductive current reference value through a feedforward controller; and providing a converter control signal through sine pulse width modulation according to the inductive current reference value and the inductive current after coordinate transformation. According to the invention, the synchronization stability of the network-forming inverter can be improved, the risk of broadband oscillation of the system is reduced, and the stability under various operation conditions is ensured.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a dual-power superposition synchronization and feedforward passive reshaping control method and system for a grid-connected inverter. Background Art

[0002] With the large-scale grid connection of distributed energy and renewable energy in the power system, the importance of grid-connected inverters in improving power quality, improving grid stability and achieving multi-energy complementarity has become increasingly prominent. Grid-connected inverters in the prior art usually adopt multi-time scale control systems such as power control loops, AC control loops and synchronization loops to achieve control of active and reactive power through sequential regulation. However, power electronic grid-connected equipment interacts with the AC grid in a wider frequency band (from a few Hz to several thousand Hz), resulting in the oscillation frequency of the power system showing broadband characteristics. With the increase in the proportion of renewable energy and distributed power generation, the equivalent grid impedance at the common coupling point has gradually become significant, resulting in a closer dynamic coupling between the inverter and the grid, thereby increasing the risk of broadband oscillation in the system, which directly affects the synchronous stability of the inverter and the safety of power feed-in.

[0003] In the prior art, PI control or cascade feedback control is often used to adjust active and reactive power respectively, and the coordination between the control loops is insufficient. Under the conditions of grid disturbance or load mutation, the inherent delay effect of feedback control makes the response to sudden disturbances untimely, which may cause wide-band oscillations, thereby reducing the dynamic stability of the system. At the same time, the traditional control strategy lacks sufficient damping in suppressing high-frequency dynamic disturbances, and it is difficult to eliminate high-frequency oscillations in time. In the case of a large change in grid impedance or the presence of wide-band disturbances, the traditional control strategy is difficult to effectively suppress power coupling oscillations, which may lead to synchronous instability or wide-band resonance problems, thereby causing the inverter output voltage and current quality to decrease, and may threaten the safe operation of the entire power system. In summary, the grid-type inverter in the prior art has significant technical problems in terms of wide-band oscillation risks, insufficient response speed, and lack of high-frequency dynamic suppression capabilities. Therefore, a new control method is urgently needed to solve the above problems and improve the overall performance of the inverter. Summary of the invention

[0004] The present application aims to provide a dual-power superposition synchronization and feedforward passive reshaping control method and system for a grid-type inverter that solves the problems of broadband oscillation risk, insufficient response speed, and lack of high-frequency dynamic suppression capability of a grid-type inverter.

[0005] In order to achieve the above-mentioned purpose, the technical solution of this application is: A dual-power superposition synchronization and feedforward passive reshaping control method for a grid-connected inverter, comprising: Step S1: Measure capacitor voltage vo , grid current i g , after abc / αβ transformation, the actual active power is calculated using the instantaneous power calculation theory p and actual reactive power q ; Step S2: Based on reactive power reference Q set The actual reactive power q , calculate the error signal e Q , and through the proportional link K Q After processing, pass through a high-pass filter G HPF Feed forward to active power controller G APC Output signal; Step S3: Based on the active power reference P set The actual active power p and error signal e Q , calculate the reference angle required for Clarke transform or inverse Clarke transform i ; Step S4: Based on reactive power reference Q set and actual reactive power q , through the reactive power controller G PRC Calculate voltage amplitude V , combined with the reference angle required for the Clarke transform or inverse Clarke transform i , the α-axis component of the voltage reference value is obtained through voltage reference calculation v orefα , the β-axis component of the voltage reference value v orefβ ; Step S5: Based on the reference angle required for Clarke transform or Clarke inverse transform i , the grid current i g , capacitor voltage v o and the inductor current i L After abc / αβ transformation, the α-axis component of the transformed grid current is obtained i gα , the β-axis component of the grid current i gβ , the α-axis component of the capacitor voltage v oα , the β-axis component of the capacitor voltagev oβ and the α-axis component of the inductor current i Lα , the β-axis component of the inductor current i Lβ , the α-axis component of the grid current i gα , the β-axis component of the grid current i gβ Through the grid current feedforward controller G f Processing to obtain the current feedforward signal; based on the α-axis component of the voltage reference value v orefα , the β-axis component of the voltage reference value v orefβ , the α-axis component of the capacitor voltage v oα , the β-axis component of the capacitor voltage v oβ , Voltage Controller G V And the current feedforward signal, calculate the α-axis component of the current reference value i Lrefα 、 β-axis component of the current reference value i Lrefβ ; Step S6: Based on the α-axis component of the inductor current i Lα , the β-axis component of the inductor current i Lβ and the α-axis component of the current reference value i Lrefα 、 β-axis component of the current reference value i Lrefβ , through the current controller G i , get the α-axis component of the reference voltage required for sinusoidal pulse width modulation v modα 、 β-axis component of the reference voltage v modβ , after αβ / abc transformation, the reference voltage required for sinusoidal pulse width modulation is obtained v mod abc , three-phase inverter control signals are generated through sinusoidal pulse width modulation.

[0006] Optionally, in step S2, the error signal is calculated e Q The formula is: in, Q set is the reactive power reference, q is the actual reactive power; Proportional Link K Q The expression is: in, Dth max is the maximum angle deviation allowed by the grid-type inverter, Q max is the maximum reactive power deviation allowed by the grid-connected inverter. is the proportionality coefficient; High Pass Filter G HPF The transfer function is: in, oh c For high pass filter G HPF Cut-off frequency, g is the damping ratio, s is the Laplace transform variable; Active Power Controller G APC The expression of the low-pass filter is: in, oh p is the cutoff frequency of the low-pass filter in the active power error path, m p is the active power droop coefficient, s is the Laplace transform variable; Active power droop coefficient m p The expression is as follows: in, Give max The maximum frequency deviation allowed for grid-type inverters is: P max The maximum active power deviation allowed by the grid-connected inverter under specific working conditions. k 1 is the proportionality coefficient.

[0007] Optionally, in step S3, a reference angle for Clarke transform or inverse Clarke transform is calculated. i The formula is: in, Give is the angular frequency adjustment value of the grid-type inverter, oh n is the reference angular frequency of the grid-connected inverter, oh p is the cutoff frequency of the low-pass filter in the active power error path, m p is the active power droop coefficient, P set is the active power reference, p is the actual active power, s is the Laplace transform variable.

[0008] Optionally, in step S4, the reactive power controller G RPC The expression of the low-pass filter is: in, oh q is the cut-off frequency of the low-pass filter in the reactive power error path, n q is the reactive power droop coefficient, s is the Laplace transform variable; Reactive power droop factor n q The expression is as follows: in, ΔV max is the maximum voltage amplitude adjustment allowed by the grid-type inverter, Q max is the maximum reactive power deviation allowed by the grid-connected inverter, k 2 is the proportionality coefficient; Calculate voltage amplitude V The formula is: in, n q is the reactive power droop coefficient, V n is the reference voltage of the grid-type inverter, oh q is the cut-off frequency of the low-pass filter in the reactive power error path, ΔV is the voltage amplitude V The amount of adjustment; Calculate the α-axis component of the voltage reference value v orefα , the β-axis component of the voltage reference value v orefβ The formula is: in, v orefα and v orefβ is the voltage reference value, i is the reference angle used for Clarke transform or inverse Clarke transform.

[0009] Optionally, in step S5, the grid current feedforward controller G f The formula is: in, K pf is the proportional gain of the grid current feedforward controller, K df is the differential gain of the grid current feedforward controller, is the time constant of the differential filter, s is the Laplace transform variable; Voltage Controller G v The formula is: in, K pv is the voltage controller proportional coefficient, K r is the resonant gain coefficient, oh r is the bandwidth factor, oh 0 is the resonant center frequency, s is the Laplace transform variable; Calculate the α-axis component of the current reference value i Lrefα 、 β-axis component of the current reference value i Lrefβ The formula is: in, i Lrefα is the α-axis component of the inductor current reference value, i Lrefβis the β-axis component of the inductor current reference value, v orefα is the α-axis component of the voltage reference value, v orefβ is the β-axis component of the voltage reference value, v oα is the α-axis component of the capacitor voltage, v oβ is the β-axis component of the capacitor voltage.

[0010] Optionally, in step S6, the current controller G i The formula is: in, K pi is the current controller proportional coefficient; Calculate the α-axis component of the reference voltage required for sinusoidal pulse width modulation v modα 、 β-axis component of the reference voltage v modβ The formula is: in, i Lα is the α-axis component of the inductor current, i Lβ is the β-axis component of the inductor current, i Lrefα is the α-axis component of the inductor current reference value, i Lrefβ is the β-axis component of the inductor current reference value; Get the reference voltage required for the converted sinusoidal pulse width modulation v mod abc The formula is: in, v moda is the a-axis component of the reference voltage, v modb is the b-axis component of the reference voltage, v modc is the c-axis component of the reference voltage, v modα is the α-axis component of the reference voltage, v modβ is the β-axis component of the reference voltage.

[0011] Optionally, in step S1, the actual active power is calculatedp and actual reactive power q The formula is: in ,voa is the α-axis component of the capacitor voltage, vob is the β-axis component of the capacitor voltage, iga is the α-axis component of the grid current, igβ is the β-axis component of the grid current.

[0012] A dual-power superposition synchronization and feedforward passive reshaping control system for a grid-type inverter executes a dual-power superposition synchronization and feedforward passive reshaping control method for a grid-type inverter as described in any one of the above items, including: a power synchronization loop and an output voltage loop, wherein the power synchronization loop and the output voltage loop are connected in sequence.

[0013] Optionally, the power synchronization loop includes: an instantaneous power calculation module, an active power control branch, a dual power superposition branch, a reactive power control branch, and a voltage reference calculation module; The first end of the instantaneous power calculation module is respectively connected to the first end of the active power control branch and the first end of the reactive power control branch, the second end of the active power control branch and the second end of the reactive power control branch are respectively connected to the first end of the voltage reference calculation module, the second end of the voltage reference calculation module is connected to the first end of the output voltage loop, the third end of the reactive power control branch is connected to the first end of the dual power superposition branch, and the second end of the dual power superposition branch is connected to the third end of the active power control branch.

[0014] Optionally, the output voltage loop includes: a current feed-forward branch; The second end of the voltage reference calculation module is respectively connected to a voltage controller G v The second end of the current feedforward branch is connected to a current controller. G i .

[0015] The dual-power superposition synchronization and feedforward passive reshaping control method and system of the grid-type inverter provided in this application can achieve accurate and independent control of the actual active power and the actual reactive power under various working conditions through the dual-power superposition of the actual active power and the actual reactive power, avoid the synchronous frequency resonance phenomenon of the grid-type inverter, and improve the synchronous stability and anti-disturbance ability of the inverter. The control method of feedforward and feedback coordinated regulation can effectively reduce the risk of wideband oscillation and ensure that the grid-type inverter maintains efficient and stable grid-connected performance under dynamic load changes and disturbances.

[0016] In order to make the above features and advantages of the application more obvious and easy to understand, the following embodiments are specifically cited and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A flow chart of the dual-power superposition synchronization and feedforward passive reshaping control method for the grid-connected inverter provided in this application.

[0018] Figure 2 This is a control block diagram of the dual-power superposition synchronization and feedforward passive reshaping control system of the grid-connected inverter proposed in this application.

[0019] Figure 3 A schematic diagram of a power synchronization ring performing dual power superposition under the method provided in this application.

[0020] Figure 4 This is a simulation waveform diagram of a grid-connected inverter using the traditional method.

[0021] Figure 5 The following is a simulation waveform diagram of a grid-connected inverter using the method provided in the present application.

[0022] Description of reference numerals: DC power supply 21, inverter bridge 22, LC filter 23, public power grid 24, dual power superposition synchronization and feedforward passive reshaping control system 25 of grid-type inverter; Power synchronization loop 251, output voltage loop 252; Instantaneous power calculation module 2511, active power control branch 2512, dual power superposition branch 2513, reactive power control branch 2514, voltage reference calculation module 2515, current feedforward branch 2521. DETAILED DESCRIPTION

[0023] In order to make the purpose and technical solution of the embodiment of the present application clearer, the technical solution of the embodiment of the present application will be clearly and completely described in conjunction with the drawings of the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, not all of the embodiments. Based on the described embodiment of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0024] In one embodiment of the present application, please refer to Figure 1 , Figure 1 The present invention provides a flow chart of a dual-power superposition synchronization and feedforward passive reshaping control method for a grid-type inverter. The dual-power superposition synchronization and feedforward passive reshaping control method for a grid-type inverter provided by the present invention comprises the following steps: Step S1: Measure capacitor voltage v o , grid current i g , after abc / αβ transformation, the actual active power is calculated using the instantaneous power calculation theory p and actual reactive power q ; Step S2: Based on reactive power reference Q set The actual reactive power q , calculate the error signal e Q , and through the proportional link K Q After processing, pass through a high-pass filter G HPF Feed forward to active power controller G APC Output signal; Step S3: Based on the active power reference P set The actual active power p and error signal e Q , calculate the reference angle required for Clarke transform or inverse Clarke transform i ; Step S4: Based on reactive power reference Q set and actual reactive power q , through the reactive power controller G PRC Calculate voltage amplitude V , combined with the reference angle required for the Clarke transform or inverse Clarke transform i , the α-axis component of the voltage reference value is obtained through voltage reference calculation v orefα , the β-axis component of the voltage reference value v orefβ ; Step S5: Based on the reference angle required for Clarke transform or Clarke inverse transform i , the grid current i g , capacitor voltage v o and the inductor current i L After abc / αβ transformation, the α-axis component of the transformed grid current is obtained i gα , the β-axis component of the grid current i gβ , the α-axis component of the capacitor voltage voα , the β-axis component of the capacitor voltage v oβ and the α-axis component of the inductor current i Lα , the β-axis component of the inductor current i Lβ , the α-axis component of the grid current i gα , the β-axis component of the grid current i gβ Through the grid current feedforward controller G f Processing to obtain the current feedforward signal; based on the α-axis component of the voltage reference value v orefα , the β-axis component of the voltage reference value v orefβ , the α-axis component of the capacitor voltage v oα , the β-axis component of the capacitor voltage v oβ , Voltage Controller G V And the current feedforward signal, calculate the α-axis component of the current reference value i Lrefα 、 β-axis component of the current reference value i Lrefβ ; Step S6: Based on the α-axis component of the inductor current i Lα , the β-axis component of the inductor current i Lβ and the α-axis component of the current reference value i Lrefα 、 β-axis component of the current reference value i Lrefβ , through the current controller G i , get the α-axis component of the reference voltage required for sinusoidal pulse width modulation v modα 、 β-axis component of the reference voltage v modβ , after αβ / abc transformation, the reference voltage required for sinusoidal pulse width modulation is obtained v mod abc , three-phase inverter control signals are generated through sinusoidal pulse width modulation.

[0025] Specifically, in step S1, the actual active power is calculated p and actual reactive power q The formula is: in ,voa is the α-axis component of the capacitor voltage, vob is the β-axis component of the capacitor voltage, iga is the α-axis component of the grid current, igβ is the β-axis component of the grid current.

[0026] Specifically, in step S2, the error signal is calculated e Q The formula is: in, Q set is the reactive power reference, q is the actual reactive power.

[0027] Proportional Link K Q The expression is: in, Dth max is the maximum angle deviation allowed by the grid-type inverter, Q max is the maximum reactive power deviation allowed by the grid-connected inverter. is the proportionality coefficient.

[0028] High Pass Filter G HPF The transfer function is: in, oh c For high pass filter G HPF Cut-off frequency, g is the damping ratio, s is the Laplace transform variable.

[0029] Active Power Controller G APC The expression of the low-pass filter is: in, oh p is the cutoff frequency of the low-pass filter in the active power error path, m p is the active power droop coefficient, s is the Laplace transform variable.

[0030] Active power droop coefficient m p The expression is as follows: in, Give max The maximum frequency deviation allowed for grid-type inverters is: P max The maximum active power deviation allowed by the grid-connected inverter under specific working conditions. k 1 is the proportionality coefficient.

[0031] Specifically, in step S3, the reference angle for Clarke transform or Clarke inverse transform is calculated. i The formula is: in, Give is the angular frequency adjustment value of the grid-type inverter, oh n is the reference angular frequency of the grid-connected inverter, oh p is the cutoff frequency of the low-pass filter in the active power error path, m p is the active power droop coefficient, P set is the active power reference, p is the actual active power, s is the Laplace transform variable.

[0032] Specifically, in step S4, the reactive power controller G RPC The expression of the low-pass filter is: in, oh q is the cut-off frequency of the low-pass filter in the reactive power error path, n q is the reactive power droop coefficient, s is the Laplace transform variable.

[0033] Reactive power droop factor n q The expression is as follows: in, ΔV max is the maximum voltage amplitude adjustment allowed by the grid-type inverter, Q maxis the maximum reactive power deviation allowed by the grid-connected inverter, k 2 is the proportionality coefficient.

[0034] Calculate voltage amplitude V The formula is: in, n q is the reactive power droop coefficient, V n is the reference voltage of the grid-type inverter, oh q is the cut-off frequency of the low-pass filter in the reactive power error path, ΔV is the voltage amplitude V The amount of adjustment.

[0035] Calculate the α-axis component of the voltage reference value v orefα , the β-axis component of the voltage reference value v orefβ The formula is: in, v orefα and v orefβ is the voltage reference value, i is the reference angle used for Clarke transform or inverse Clarke transform.

[0036] Specifically, in step S5, the grid current feedforward controller G f The formula is: in, K pf is the proportional gain of the grid current feedforward controller, K df is the differential gain of the grid current feedforward controller, is the time constant of the differential filter, s is the Laplace transform variable.

[0037] Voltage Controller G v The formula is: in, K pv is the voltage controller proportional coefficient, Kr is the resonant gain coefficient, oh r is the bandwidth factor, oh 0 is the resonant center frequency, s is the Laplace transform variable.

[0038] Calculate the α-axis component of the current reference value i Lrefα 、 β-axis component of the current reference value i Lrefβ The formula is: in, i Lrefα is the α-axis component of the inductor current reference value, i Lrefβ is the β-axis component of the inductor current reference value, v orefα is the α-axis component of the voltage reference value, v orefβ is the β-axis component of the voltage reference value, v oα is the α-axis component of the capacitor voltage, v oβ is the β-axis component of the capacitor voltage.

[0039] Specifically, in step S6, the current controller G i The formula is: in, K pi is the current controller proportional coefficient.

[0040] Calculate the α-axis component of the reference voltage required for sinusoidal pulse width modulation v modα 、 β-axis component of the reference voltage v modβ The formula is: in, i Lα is the α-axis component of the inductor current, i Lβ is the β-axis component of the inductor current, i Lrefα is the α-axis component of the inductor current reference value, iLrefβ is the β-axis component of the inductor current reference value.

[0041] Get the reference voltage required for the converted sinusoidal pulse width modulation v mod abc The formula is: in, v moda is the a-axis component of the reference voltage, v modb is the b-axis component of the reference voltage, v modc is the c-axis component of the reference voltage, v modα is the α-axis component of the reference voltage, v modβ is the β-axis component of the reference voltage.

[0042] In another embodiment of the present application, please refer to Figure 2 , Figure 2 This is a control block diagram of the dual-power superposition synchronization and feedforward passive reshaping control system of the meshed inverter proposed in this application. The dual-power superposition synchronization and feedforward passive reshaping control system 25 of the meshed inverter includes: a power synchronization ring 251 and an output voltage ring 252. The power synchronization ring 251 and the output voltage ring 252 are connected in sequence.

[0043] As an example, the power synchronization loop 251 includes: an instantaneous power calculation module 2511, an active power control branch 2512, a dual power superposition branch 2513, a reactive power control branch 2514, and a voltage reference calculation module 2515. The first end of the instantaneous power calculation module 2511 is respectively connected to the first end of the active power control branch 2512 and the first end of the reactive power control branch 2514, the second end of the active power control branch 2512 and the second end of the reactive power control branch 2514 are respectively connected to the first end of the voltage reference calculation module 2515, the second end of the voltage reference calculation module 2515 is connected to the first end of the output voltage loop 252, the third end of the reactive power control branch 2514 is connected to the first end of the dual power superposition branch 2513, and the second end of the dual power superposition branch 2513 is connected to the third end of the active power control branch 2512.

[0044] The output voltage loop 252 includes: a current feedforward branch 2521, a second end of the voltage reference calculation module 2515 passes through a voltage controller G v Then connected to the first end of the current feedforward branch 2521, the second end of the current feedforward branch 2521 is connected to a current controller G i .

[0045] Please continue reading Figure 2 The dual-power superposition synchronization and feedforward passive reshaping control system of the grid-forming inverter proposed in this application is used for the grid-forming inverter, and the grid-forming inverter includes: a DC power supply 21, an inverter bridge 22, an LC filter 23, and a public power grid 24. The DC power supply 21, the inverter bridge 22, the LC filter 23 and the public power grid 24 are connected in sequence. Among them, the inverter bridge 22 includes a switch tube and its corresponding freewheeling diode; the LC filter 23 includes a filter inductor L and a filter capacitor C, the first end of the filter inductor L is connected to the first end of the inverter bridge 22, the second end of the filter inductor L is connected to the first end of the filter capacitor C, and the second end of the filter capacitor C is grounded; the public power grid 24 includes a three-phase voltage source v g , equivalent grid impedance z g and transformer K T ,transformer K T The first end of the transformer is connected to the first end of the filter capacitor C. K T The second end of the equivalent grid impedance z g The first end of the connection, the equivalent grid impedance z g The second end of the three-phase voltage source v g The first end is connected to a three-phase voltage source v g The second end of the DC power supply 21 is grounded. The voltage across the DC power supply 21 is V dc .

[0046] As an example, the power synchronization loop 251 is used to convert the reactive power reference Q set , through the proportional link K Q and high pass filter G HPF , feedforward introduces active power controller G APC .

[0047] Specifically, the instantaneous power calculation module 2511 is used to use the capacitor voltage v o and grid current i g Calculate the actual active power of the grid-connected inverter p and actual reactive power q .

[0048] Reactive power control branch 2514 is used to utilize reactive power reference Qset The actual reactive power q , and get the error signal e Q . And based on the reactive power benchmark Q set and actual reactive power q , through the reactive power controller G PRC Calculate the voltage amplitude V .

[0049] The dual power superposition branch 2513 is used to convert the error signal e Q Through the proportion link K Q After processing, pass through a high-pass filter G HPF Processing, feed it forward to the active power controller of the active power control branch 2512 G APC To achieve fast dynamic compensation.

[0050] Active power control branch 2512 is used to control the active power reference P set , Actual active power p and error signal e Q , calculate the reference angle for Clarke transform or inverse Clarke transform i .

[0051] The voltage reference calculation module 2515 is used to calculate the voltage reference based on the reference angle for Clarke transform or Clarke inverse transform. i and voltage amplitude V , calculate the voltage reference value v orefα 、v orefβ , and sent to the output voltage loop 252.

[0052] As an example, the output voltage loop 252 is used to convert the grid current i g , capacitor voltage v o and the inductor current i L After abc / αβ transformation, the α-axis component of the transformed grid current is obtained i gα , the β-axis component of the grid current i gβ , the α-axis component of the capacitor voltage v oα , the β-axis component of the capacitor voltage v oβand the α-axis component of the inductor current i Lα , the β-axis component of the inductor current i Lβ ; The α-axis component of the voltage reference value is detected v orefα , the β-axis component of the voltage reference value v orefβ , the α-axis component of the capacitor voltage v oα , the β-axis component of the capacitor voltage v oβ , the α-axis component of the voltage reference value v orefα , the β-axis component of the voltage reference value v orefβ The α-axis component of the capacitor voltage v oα , the β-axis component of the capacitor voltage v oβ Subtract, through the voltage controller G V After that, the current is fed forward in the current feedforward branch 2521 to obtain the α-axis component of the current reference value. i Lrefα 、 β-axis component of the current reference value i Lrefβ The α-axis component of the current reference value i Lrefα 、 β-axis component of the current reference value i Lrefβ The α-axis component of the inductor current i Lα , the β-axis component of the inductor current i Lβ Subtract, through the current controller G i , get the α-axis component of the reference voltage required for sinusoidal pulse width modulation v modα 、 β-axis component of the reference voltage v modβ , after αβ / abc transformation, the reference voltage required for sinusoidal pulse width modulation is obtained v mod abc , a sinusoidal pulse width control signal for each switch tube of the inverter bridge 22 is generated by sinusoidal pulse width modulation. Finally, the control signal after sinusoidal pulse width modulation is input into the inverter bridge 22 to control the switch tube of the inverter bridge 22.

[0053] Specifically, the current feed-forward branch 2521 is used to feed the α-axis component of the grid current. igα , the β-axis component of the grid current i gβ Through the grid current feedforward controller G f Processing, get the current feedforward signal; voltage reference value v oref Capacitor voltage v o Subtract, through the voltage controller G V Then subtract the current feedforward signal to get the α-axis component of the current reference value i Lrefα 、 β-axis component of the current reference value i Lrefβ .

[0054] As an example, see Figure 3 , Figure 3 Schematic diagram of a power synchronization ring performing dual power superposition under the method provided in this application, wherein in the active power control branch 2512, the active power controller G APC Including low-pass filtering m p oh p / s+ oh p In the reactive power control branch 2514, the reactive power controller G RPC Including low-pass filtering n q oh q / s+ω q Active power control branch 2512 and reactive power control branch 2514 are conventionally controlled with a low-pass filter (LPF) by converting the reactive power error signal e Q The dynamic decoupling mechanism that feeds forward to the active power control branch 2512 through the dual power superposition branch 2513 realizes the coordinated regulation of active and reactive power.

[0055] As an example, see Figure 4 and Figure 5 , Figure 4 This is the simulation waveform of the grid-connected inverter using the traditional method. Figure 5The simulation waveform of the grid-type inverter using the method provided by this application is shown in Figure 2. The operation of the grid-type inverter controlled by the dual-power superposition synchronization and feedforward passive reshaping control method of the grid-type inverter is simulated and verified by MATLAB / Simulink software. Under specific grid conditions, such as when the grid impedance is purely inductive and the equivalent short-circuit capacity ratio is 30, the traditional control method and the control method proposed in this application are used to verify the effectiveness of the control method proposed in this application. The simulation results are shown in Figure 2. Figure 4 and Figure 5 As shown. It can be seen from the figure that under the grid condition, the grid-type inverter using the traditional control method has obvious oscillations, while the control method proposed in this application is adopted, and the output voltage and output current of the grid-type inverter are both presented as sinusoidal stable waveforms. The experimental results show that the dual-power superposition synchronization and feedforward passive reshaping control method and system of the grid-type inverter provided in this application can realize accurate and independent control of the actual active power and the actual reactive power under various working conditions through the dual-power superposition of the actual active power and the actual reactive power, avoid the synchronous frequency resonance phenomenon of the grid-type inverter, and improve the synchronous stability and anti-disturbance ability of the inverter. The control method of feedforward and feedback coordinated regulation can effectively reduce the risk of wide-band oscillations, ensure that the grid-type inverter maintains efficient and stable grid-connected performance under dynamic load changes and disturbances, and enable the grid-type inverter to operate reliably under complex grid conditions, realizing the plug-and-play function of the grid-type inverter.

[0056] Although the present application has been disclosed as above with the embodiments, it is not intended to limit the present application. Any person with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be determined by the scope of the attached patent application.

Claims

1. A dual-power superposition synchronization and feedforward passive reshaping control method for a grid-connected inverter, characterized in that: include, Step S1: Measure capacitor voltage v o , grid current i g , after abc / αβ transformation, the actual active power is calculated using the instantaneous power calculation theory p and actual reactive power q ; Step S2: Based on reactive power reference Q set The actual reactive power q , calculate the error signal e Q , and through the proportional link K Q After processing, pass through a high-pass filter G HPF Feed forward to active power controller G APC Output signal; Step S3: Based on the active power reference P set The actual active power p and error signal e Q , calculate the reference angle required for Clarke transform or inverse Clarke transform θ ; Step S4: Based on reactive power reference Q set and actual reactive power q , through the reactive power controller G PRC Calculate voltage amplitude V , combined with the reference angle required for the Clarke transform or inverse Clarke transform θ , the α-axis component of the voltage reference value is obtained through voltage reference calculation v orefα , the β-axis component of the voltage reference value v orefβ ; Step S5: Based on the reference angle required for Clarke transform or Clarke inverse transform θ , the grid current i g , capacitor voltage v o and the inductor current i L After abc / αβ transformation, the α-axis component of the transformed grid current is obtained i gα , the β-axis component of the grid current i gβ , the α-axis component of the capacitor voltage v oα , the β-axis component of the capacitor voltage v oβ and the α-axis component of the inductor current i Lα , the β-axis component of the inductor current i Lβ , the α-axis component of the grid current i gα , the β-axis component of the grid current i gβ Through the grid current feedforward controller G f Processing to obtain the current feedforward signal; based on the α-axis component of the voltage reference value v orefα , the β-axis component of the voltage reference value v orefβ , the α-axis component of the capacitor voltage v oα , the β-axis component of the capacitor voltage v oβ , Voltage Controller G V And the current feedforward signal, calculate the α-axis component of the current reference value i Lrefα 、 β-axis component of the current reference value i Lrefβ ; Step S6: Based on the α-axis component of the inductor current i Lα , the β-axis component of the inductor current i Lβ and the α-axis component of the current reference value i Lrefα 、 β-axis component of the current reference value i Lrefβ , through the current controller G i , get the α-axis component of the reference voltage required for sinusoidal pulse width modulation v modα 、 β-axis component of the reference voltage v modβ , after αβ / abc transformation, the reference voltage v required for sinusoidal pulse width modulation is obtained mod abc , three-phase inverter control signals are generated through sinusoidal pulse width modulation.

2. The dual-power superposition synchronization and feedforward passive reshaping control method of the grid-connected inverter according to claim 1, characterized in that: In step S2, the error signal is calculated e Q The formula is: in, Q set is the reactive power reference, q is the actual reactive power; Proportional Link K Q The expression is: in, Δθ max is the maximum angle deviation allowed by the grid-type inverter, Q max is the maximum reactive power deviation allowed by the grid-connected inverter. k q is the proportionality coefficient; High Pass Filter G HPF The transfer function is: in, ω c For high pass filter G HPF Cut-off frequency, ζ is the damping ratio, s is the Laplace transform variable; Active Power Controller G APC The expression of the low-pass filter is: in, ω p is the cutoff frequency of the low-pass filter in the active power error path, m p is the active power droop coefficient, s is the Laplace transform variable; Active power droop coefficient m p The expression is as follows: in, Δω max The maximum frequency deviation allowed for grid-type inverters is: P max The maximum active power deviation allowed by the grid-connected inverter under specific working conditions. k 1 is the proportionality coefficient.

3. The dual-power superposition synchronization and feedforward passive reshaping control method of the grid-connected inverter according to claim 2, characterized in that: In step S3, the reference angle for Clarke transform or inverse Clarke transform is calculated. θ The formula is: in, Δω is the angular frequency adjustment value of the grid-type inverter, ω n is the reference angular frequency of the grid-connected inverter, ω p is the cutoff frequency of the low-pass filter in the active power error path, m p is the active power droop coefficient, P set is the active power reference, p is the actual active power, s is the Laplace transform variable.

4. The dual-power superposition synchronization and feedforward passive reshaping control method of the grid-connected inverter according to claim 1, characterized in that: In step S4, the reactive power controller G RPC The expression of the low-pass filter is: in, ω q is the cut-off frequency of the low-pass filter in the reactive power error path, n q is the reactive power droop coefficient, s is the Laplace transform variable; Reactive power droop factor n q The expression is as follows: in, ΔV max is the maximum voltage amplitude adjustment allowed by the grid-type inverter, Q max is the maximum reactive power deviation allowed by the grid-connected inverter, k 2 is the proportionality coefficient; Calculate voltage amplitude V The formula is: in, n q is the reactive power droop coefficient, V n is the reference voltage of the grid-type inverter, ω q is the cut-off frequency of the low-pass filter in the reactive power error path, ΔV is the voltage amplitude V The amount of adjustment; Calculate the α-axis component of the voltage reference value v orefα , the β-axis component of the voltage reference value v orefβ The formula is: in, v orefα and v orefβ is the voltage reference value, θ is the reference angle used for Clarke transform or inverse Clarke transform.

5. The dual-power superposition synchronization and feedforward passive reshaping control method of the grid-connected inverter according to claim 4, characterized in that: In step S5, the grid current feedforward controller G f The formula is: in, K pf is the proportional gain of the grid current feedforward controller, K df is the differential gain of the grid current feedforward controller, is the time constant of the differential filter, s is the Laplace transform variable; Voltage Controller G v The formula is: in, K pv is the voltage controller proportional coefficient, K r is the resonant gain coefficient, ω r is the bandwidth factor, ω 0 is the resonant center frequency, s is the Laplace transform variable; Calculate the α-axis component of the current reference value i Lrefα 、 β-axis component of the current reference value i Lrefβ The formula is: in, i Lrefα is the α-axis component of the inductor current reference value, i Lrefβ is the β-axis component of the inductor current reference value, v orefα is the α-axis component of the voltage reference value, v orefβ is the β-axis component of the voltage reference value, v oα is the α-axis component of the capacitor voltage, v oβ is the β-axis component of the capacitor voltage.

6. The dual-power superposition synchronization and feedforward passive reshaping control method of the grid-connected inverter according to claim 1, characterized in that: In step S6, the current controller G i The formula is: in, K pi is the current controller proportional coefficient; Calculate the α-axis component of the reference voltage required for sinusoidal pulse width modulation v modα 、 β-axis component of the reference voltage v modβ The formula is: in, i Lα is the α-axis component of the inductor current, i Lβ is the β-axis component of the inductor current, i Lrefα is the α-axis component of the inductor current reference value, i Lrefβ is the β-axis component of the inductor current reference value; Get the reference voltage required for the converted sinusoidal pulse width modulation v mod abc The formula is: in, v moda is the a-axis component of the reference voltage, v modb is the b-axis component of the reference voltage, v modc is the c-axis component of the reference voltage, v modα is the α-axis component of the reference voltage, v modβ is the β-axis component of the reference voltage.

7. The dual-power superposition synchronization and feedforward passive reshaping control method of the grid-connected inverter according to claim 1, characterized in that: In step S1, the actual active power is calculated p and actual reactive power q The formula is: in ,voα is the α-axis component of the capacitor voltage, voβ is the β-axis component of the capacitor voltage, igα is the α-axis component of the grid current, igβ is the β-axis component of the grid current.

8. A dual-power superposition synchronization and feedforward passive reshaping control system for a grid-type inverter, executing a dual-power superposition synchronization and feedforward passive reshaping control method for a grid-type inverter as claimed in any one of claims 1 to 7, characterized in that: include: A power synchronization ring and an output voltage ring are connected in sequence.

9. The dual-power superposition synchronization and feedforward passive reshaping control system of the grid-type inverter according to claim 8, characterized in that: The power synchronization loop includes: an instantaneous power calculation module, an active power control branch, a dual power superposition branch, a reactive power control branch, and a voltage reference calculation module; The first end of the instantaneous power calculation module is respectively connected to the first end of the active power control branch and the first end of the reactive power control branch, the second end of the active power control branch and the second end of the reactive power control branch are respectively connected to the first end of the voltage reference calculation module, the second end of the voltage reference calculation module is connected to the first end of the output voltage loop, the third end of the reactive power control branch is connected to the first end of the dual power superposition branch, and the second end of the dual power superposition branch is connected to the third end of the active power control branch.

10. The dual-power superposition synchronization and feedforward passive reshaping control system of the grid-connected inverter according to claim 9, characterized in that: The output voltage loop comprises: a current feed-forward branch; The second end of the voltage reference calculation module is respectively connected to a voltage controller G v The second end of the current feedforward branch is connected to a current controller. G i .

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