Inverter control method, system and device and storage medium

Abstract

The invention discloses a control method, system and device of an inverter and a storage medium, and the method comprises the steps: determining a power grid voltage frequency, a power grid voltage phase and a power grid voltage amplitude synchronization coefficient based on a current control reference value, a power grid current actual value and a power grid voltage amplitude, and then determining a first control potential and a second control potential; therefore, the modulation wave of the inverter is adjusted based on the first control potential, the second control potential and the power grid voltage phase, so that the output current of the output end of the inverter follows the current control reference value, the actual power grid current value follows the current control reference value, the stability of the power grid current is ensured, and the reliability of the inverter is improved. The frequency of the output voltage of the output end of the inverter can follow the frequency of the power grid voltage, and the phase of the output voltage of the output end of the inverter can follow the phase of the power grid voltage. Therefore, the inverter system simulates the behavior of the synchronous generator, provides inertia for the power grid, and maintains the stability of the frequency of the power grid.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and in particular to a control method, system, device and storage medium of an inverter. Background Art

[0002] When traditional fossil fuel power plants put the generated electricity into the grid, large synchronous generators are usually used to provide inertial response to maintain the stability of the grid frequency. However, as renewable energy continues to replace traditional fossil energy, renewable energy is usually direct current, which is connected to the grid through inverters. Synchronous generators are gradually replaced, resulting in reduced grid inertia and reduced grid frequency stability. Therefore, when the direct current generated by renewable energy is unstable, the grid frequency will fluctuate greatly. Summary of the invention

[0003] The purpose of the present invention is to provide a control method, system, device and storage medium of an inverter, firstly determine the grid voltage frequency, grid voltage phase and grid voltage amplitude synchronization coefficient based on the current control reference value, the actual value of the grid current and the grid voltage amplitude, and then respectively determine the first control potential and the second control potential, so as to adjust the modulation wave of the inverter based on the first control potential, the second control potential and the grid voltage phase, so that the output current of the output end of the inverter follows the current control reference value, and then the actual value of the grid current follows the current control reference value, so as to ensure the stability of the grid current, and also enable the frequency of the output voltage of the output end of the inverter to follow the grid voltage frequency, and enable the phase of the output voltage of the output end of the inverter to follow the grid voltage phase. Thus, the inverter system simulates the behavior of a synchronous generator, provides inertia for the grid, and maintains the stability of the grid frequency.

[0004] In order to solve the above technical problems, the present invention provides a control method of an inverter, comprising:

[0005] Determine a grid voltage frequency, a grid voltage phase, and a grid voltage amplitude synchronization coefficient based on a current control reference value, an actual grid current value, and a grid voltage amplitude;

[0006] converting the current control reference value, the grid voltage frequency and the grid current actual value into a first control potential;

[0007] determining a second control potential based on the grid voltage frequency and the grid voltage amplitude synchronization coefficient;

[0008] The modulation wave of the inverter is adjusted based on the first control potential, the second control potential and the grid voltage phase so that the output current at the output end of the inverter follows the current control reference value, the frequency of the output voltage at the output end of the inverter follows the grid voltage frequency, and the phase of the output voltage at the output end of the inverter follows the grid voltage phase.

[0009] Preferably, generating a first control potential based on the current control reference value, the grid voltage frequency and the grid current actual value comprises:

[0010] Calculating a current error value based on the current control reference value and the actual value of the grid current;

[0011] Performing proportional-integral calculation based on the current error value to determine a target grid current actual value and a differential value of the target grid current actual value;

[0012] The first control potential is determined by the target grid current actual value, a differential value of the target grid current actual value, and the grid voltage frequency.

[0013] Preferably, determining the first control potential by the target grid current actual value, the differential value of the target grid current actual value and the grid voltage frequency comprises:

[0014] Calculating the first control potential using a first expression based on the target grid current actual value, the differential value of the target grid current actual value, and the grid voltage frequency;

[0015] The first expression is:

[0016] ;

[0017] in, is the d-axis component of the first control potential, is the q-axis component of the first control potential, is the grid-side filter resistor, is the grid-side filter inductor, is the grid voltage frequency, is the d-axis component of the actual value of the target grid current, is the q-axis component of the actual value of the target grid current, is the d-axis component of the differential value of the actual value of the target grid current, It is the q-axis component of the differential value of the actual value of the target grid current.

[0018] Preferably, determining the grid voltage frequency, grid voltage phase and grid voltage amplitude synchronization coefficient based on the current control reference value, the grid current actual value and the grid voltage amplitude includes:

[0019] multiplying the current control reference value by a torque coefficient to determine a mechanical torque value;

[0020] Multiplying the actual value of the grid current by the torque coefficient to determine the electromagnetic torque value;

[0021] determining a torque error value based on a difference between the mechanical torque value and the electromagnetic torque value;

[0022] Calculating the grid voltage frequency based on the torque error value and the swing equation;

[0023] Integrating the grid voltage frequency to determine the grid voltage phase;

[0024] The grid voltage amplitude synchronization coefficient is calculated based on the grid voltage frequency and the grid voltage amplitude.

[0025] Preferably, before multiplying the current control reference value and the torque coefficient to determine the mechanical torque value, the method further comprises:

[0026] Performing filtering on the current control reference value to obtain the filtered current control reference value;

[0027] The current control reference value is multiplied by a torque coefficient to determine a mechanical torque value, comprising:

[0028] The filtered current control reference value is multiplied by a torque coefficient to determine a mechanical torque value.

[0029] Preferably, it also includes:

[0030] Calculating a damping torque based on the grid voltage frequency and a damping coefficient;

[0031] Determining a torque error value based on a difference between the mechanical torque value and the electromagnetic torque value includes:

[0032] A torque error value is determined based on a difference value obtained by subtracting the electromagnetic torque value and the damping torque from the mechanical torque value.

[0033] Preferably, before adjusting the modulation wave of the inverter based on the first control potential, the second control potential and the grid voltage phase, the method further includes:

[0034] determining a disturbance amount in a process of controlling the inverter based on the first control potential, the second control potential, an actual value of a grid voltage, and an actual value of a grid current;

[0035] The method further comprises: adjusting a modulation wave of an inverter based on the first control potential, the second control potential and the grid voltage phase, comprising:

[0036] Determine the inverter control potential based on the sum of the first control potential and the second control potential minus the difference of the disturbance amount;

[0037] The modulation wave of the inverter is adjusted based on the inverter control potential and the grid voltage phase.

[0038] In order to solve the above technical problems, the present invention provides a control system of an inverter, comprising:

[0039] A first determination unit is used to determine a grid voltage frequency, a grid voltage phase and a grid voltage amplitude synchronization coefficient based on a current control reference value, an actual grid current value and a grid voltage amplitude;

[0040] A first conversion unit, configured to convert the current control reference value, the grid voltage frequency and the grid current actual value into a first control potential;

[0041] a second determining unit, configured to determine a second control potential based on the grid voltage frequency and the grid voltage amplitude synchronization coefficient;

[0042] An adjustment unit is used to adjust the modulation wave of the inverter based on the first control potential, the second control potential and the grid voltage phase, so that the output current of the output end of the inverter follows the current control reference value, the frequency of the output voltage of the output end of the inverter follows the grid voltage frequency, and the phase of the output voltage of the output end of the inverter follows the grid voltage phase.

[0043] In order to solve the above technical problems, the present invention provides a control device for an inverter, comprising:

[0044] Memory for storing computer programs;

[0045] The processor is used to implement the steps of the inverter control method as described above when executing a computer program.

[0046] In order to solve the above technical problem, the present invention provides a non-volatile storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the inverter control method as described above are implemented.

[0047] The present application provides a control method, system, device and storage medium for an inverter, which first determines the grid voltage frequency, grid voltage phase and grid voltage amplitude synchronization coefficient based on the current control reference value, the actual grid current value and the grid voltage amplitude, and then determines the first control potential and the second control potential respectively, so as to adjust the modulation wave of the inverter based on the first control potential, the second control potential and the grid voltage phase, so that the output current of the output end of the inverter follows the current control reference value, and then the actual grid current value follows the current control reference value, so as to ensure the stability of the grid current, and also enable the frequency of the output voltage of the output end of the inverter to follow the grid voltage frequency, and enable the phase of the output voltage of the output end of the inverter to follow the grid voltage phase. Thus, the inverter system simulates the behavior of a synchronous generator, provides inertia for the grid, and maintains the stability of the grid frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 A schematic diagram of a flow chart of a control method for an inverter provided in the present application;

[0050] Figure 2 A control block diagram for generating a first control potential provided by the present application;

[0051] Figure 3 A control block diagram for generating a grid voltage amplitude synchronization coefficient provided by the present application;

[0052] Figure 4 A structural block diagram for generating a grid voltage frequency and a grid voltage phase provided by the present application;

[0053] Figure 5 A control block diagram of a disturbance observer provided in this application;

[0054] Figure 6 A control block diagram for controlling an inverter provided in the present application;

[0055] Figure 7 A schematic diagram of the structure of a control system of an inverter provided in this application;

[0056] Figure 8 A schematic diagram of the structure of a control device for an inverter provided in the present application;

[0057] Fig. 9A schematic diagram of the structure of a non-volatile storage medium provided in this application. DETAILED DESCRIPTION

[0058] The core of the present invention is to provide a control method, system, device and storage medium for an inverter, firstly determine the grid voltage frequency, grid voltage phase and grid voltage amplitude synchronization coefficient based on the current control reference value, the actual grid current value and the grid voltage amplitude, and then respectively determine the first control potential and the second control potential, so as to adjust the modulation wave of the inverter based on the first control potential, the second control potential and the grid voltage phase, so that the output current of the output end of the inverter follows the current control reference value, and then the actual grid current value follows the current control reference value, so as to ensure the stability of the grid current, and also enable the frequency of the output voltage of the output end of the inverter to follow the grid voltage frequency, and enable the phase of the output voltage of the output end of the inverter to follow the grid voltage phase. Thus, the inverter system simulates the behavior of a synchronous generator, provides inertia for the grid, and maintains the stability of the grid frequency.

[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] Please refer to Figure 1 , Figure 1 A flow chart of a control method for an inverter provided in the present application, the method comprising:

[0061] S11: determining a grid voltage frequency, a grid voltage phase, and a grid voltage amplitude synchronization coefficient based on a current control reference value, an actual grid current value, and a grid voltage amplitude;

[0062] The increasing demand for renewable energy supply has brought huge fluctuations to the power grid. Traditional fossil fuel power plants are usually provided with inertial response by large synchronous generators to maintain the stability of the power grid frequency. However, as renewable energy continues to replace traditional fossil energy, synchronous generators are gradually replaced, resulting in a decrease in grid inertia and a decrease in frequency stability.

[0063] Renewable energy is usually connected to the grid through an inverter. The inverter converts the DC power output by renewable energy into AC power and then inputs it into the grid. However, since the inverter cannot provide inertial response for the grid, it is also unable to maintain the stability of the grid frequency. If the output current of the inverter is inconsistent with the actual current of the grid, then the inverter will also cause fluctuations in the grid frequency after connecting the AC power to the grid.

[0064] In order to solve the above technical problems, in the present application, when controlling the inverter, data processing is performed on the actual grid current value and grid voltage amplitude collected on the grid side according to a predetermined current control reference value, so as to determine the grid voltage frequency, grid voltage phase and grid voltage amplitude synchronization coefficient, wherein the grid voltage frequency refers to the frequency determined by the actual grid current value and the current control reference value, that is, the desired grid current frequency or grid voltage frequency. The grid voltage phase is the phase of the alternating current in the grid. For example, if the alternating current in the grid is three-phase alternating current, the phase difference of each phase voltage in the three-phase alternating current is 120°. Similarly, the grid voltage phase can be determined based on the actual grid current value. The grid voltage amplitude synchronization coefficient is a coefficient determined based on the collected grid voltage amplitude and the predetermined current control reference value, and is used to adjust the amplitude of the output voltage of the inverter to ensure that the amplitude of the output voltage of the inverter is based on the grid voltage amplitude, thereby ensuring the stability of the grid.

[0065] S12: converting the current control reference value, the grid voltage frequency and the grid current actual value into a first control potential;

[0066] After the grid voltage frequency is determined, the grid current control reference value, the grid voltage frequency and the actual grid current value are converted into a first control potential. Since the output current of the inverter changes with the output voltage, the inverter is adjusted by the first control potential to indirectly adjust the output current of the inverter, so that the output current of the inverter is adjusted to follow the current control reference value, and then the actual grid current value follows the current control reference value. Through continuous dynamic adjustment, the stability of the grid current is guaranteed.

[0067] S13: determining a second control potential based on a grid voltage frequency and a grid voltage amplitude synchronization coefficient;

[0068] In addition, the second control potential is determined by the grid voltage frequency and the grid voltage amplitude synchronization coefficient, and the inverter is adjusted by the second control potential so that the frequency of the inverter's output voltage follows the grid voltage frequency to ensure the stability of the grid frequency.

[0069] S14: Adjust the modulation wave of the inverter based on the first control potential, the second control potential and the grid voltage phase so that the output current of the output end of the inverter follows the current control reference value, the frequency of the output voltage of the output end of the inverter follows the grid voltage frequency, and the phase of the output voltage of the output end of the inverter follows the grid voltage phase.

[0070] In the present application, the modulation wave of the inverter is adjusted by the first control potential and the second control potential, so as to adjust the output voltage of the inverter. In the process of adjusting the output voltage of the inverter, not only the frequency of the output voltage of the inverter follows the grid voltage frequency, but also the output current of the inverter changes accordingly, so that the output current of the inverter follows the current control reference value. In addition, the modulation wave of the inverter is also adjusted by the grid voltage phase, so that the phase of the output voltage of the inverter follows the grid voltage phase, so that the system remains in a stable state.

[0071] It can be seen that the control of the inverter in the present application simulates the control method of the current reference virtual synchronous machine. The energy storage system of renewable energy is connected to the inverter and then connected to the power grid through the RLC filter circuit. The inverter converts the DC power in the energy storage system into AC power and transmits the AC power to the power grid through the RLC filter. Therefore, the inverter can be regarded as a synchronous machine with a small static capacitor connected in parallel to the armature winding terminals. The inductance and resistance in the RLC filter circuit correspond to the armature winding of the synchronous machine. Therefore, the three-phase current output by the inverter corresponds to the armature current, the three-phase AC power output by the inverter corresponds to the potential of the synchronous machine, and the grid voltage corresponds to the armature winding terminal voltage. The first control potential and the second control potential simulate the two electromagnetic fields of the current reference virtual synchronous machine.

[0072] It should also be noted that in the present application, the current control expected value can be set first, and the current control expected value and the power grid can be drooped to generate a current control reference value, thereby realizing the control of active power and reactive power. When the active power output by the inverter is large, the current control reference value is adjusted using the droop characteristic to increase the output frequency of the inverter, thereby reducing the active power output by the inverter; when the active power output by the inverter is small, the output frequency of the inverter is reduced using the droop characteristic, thereby increasing the active power output.

[0073] In summary, in this application, the grid voltage frequency, grid voltage phase and grid voltage amplitude synchronization coefficient are first determined based on the current control reference value, the actual grid current value and the grid voltage amplitude, and then the first control potential and the second control potential are determined respectively, so as to adjust the modulation wave of the inverter based on the first control potential, the second control potential and the grid voltage phase, so that the output current of the output end of the inverter follows the current control reference value, and then the actual grid current value follows the current control reference value, so as to ensure the stability of the grid current, and also enable the frequency of the output voltage of the output end of the inverter to follow the grid voltage frequency, and enable the phase of the output voltage of the output end of the inverter to follow the grid voltage phase. Thus, the inverter system simulates the behavior of a synchronous generator, provides inertia for the grid, and maintains the stability of the grid frequency.

[0074] Based on the above embodiments:

[0075] As a preferred embodiment, generating the first control potential based on the current control reference value, the grid voltage frequency and the grid current actual value includes:

[0076] Calculating a current error value based on a current control reference value and an actual grid current value;

[0077] Performing proportional integral calculation based on the current error value to determine the actual value of the target grid current and the differential value of the actual value of the target grid current;

[0078] The first control potential is determined by the target grid current actual value and the differential value of the target grid current actual value and the grid voltage frequency.

[0079] In this embodiment, in order to make the actual value of the grid current follow the current control reference value, specifically, the current error value is first calculated according to the current control reference value and the actual value of the grid current, that is, the difference between the actual value of the grid current and the current control reference value, and the target actual value of the grid current is obtained by proportional integral calculation of the current error value. In fact, after the inverter is adjusted, the target actual value of the grid current and the actual value of the grid current are consistent in value. The difference between the two is that the actual value of the grid current is obtained by actual measurement from the grid side, and the target actual value of the grid current is calculated by the current error value. Based on this, there is no need to directly differentiate the actual value of the grid current to obtain the differential value of the target actual value of the grid current, thereby ensuring more accurate control of the inverter, and the calculated target actual value of the grid current can be directly added to the feedback adjustment process, and the current error value is directly calculated according to the current control reference value and the target actual value of the grid current, which also avoids the instability of system control caused by the error in the acquisition of the actual value of the grid current.

[0080] After obtaining the target grid current actual value and its differential value, the first control potential is calculated so that when the inverter is subsequently controlled based on the first control potential, the output current of the inverter follows the target grid current actual value, that is, the actual value of the grid current is kept consistent with the actual value of the target grid current, so that the output current of the inverter follows the target grid current actual value. In other words, the output current of the inverter follows the current control reference value, which is reflected in the control system by controlling the inverter so that the current error value approaches 0.

[0081] As a preferred embodiment, determining the first control potential by the target grid current actual value, the differential value of the target grid current actual value, and the grid voltage frequency includes:

[0082] Calculating a first control potential using a first expression based on a target grid current actual value, a differential value of the target grid current actual value, and a grid voltage frequency;

[0083] The first expression is:

[0084] ;

[0085] in, is the d-axis component of the first control potential, is the q-axis component of the first control potential, is the grid-side filter resistor, is the grid-side filter inductor, is the grid voltage frequency, is the d-axis component of the actual value of the target grid current, is the q-axis component of the actual value of the target grid current, is the d-axis component of the differential value of the actual value of the target grid current, It is the q-axis component of the differential value of the actual value of the target grid current.

[0086] In this embodiment, when calculating the first control potential, the d-axis component and q-axis component of the first control potential are calculated respectively, and the d-axis component of the first control potential is calculated by the d-axis component of the actual value of the target grid current, and the q-axis component of the first control potential is calculated by the q-axis component of the actual value of the target grid current. Taking the calculation of the d-axis component of the first control potential as an example, the voltage drop caused by the equivalent stator resistance and the voltage drop caused by the equivalent stator inductance are added, and then the voltage drop caused by the grid voltage frequency is subtracted to obtain the d-axis component of the first control potential. The q-axis component of the first control potential refers to the calculation of the d-axis component, and this application will not repeat it. Based on this, after adjusting the inverter based on the first control potential, it can be ensured that the output current of the inverter follows the current control reference value, thereby stabilizing the actual current value of the grid to the current control reference value.

[0087] Please refer to Figure 2 , Figure 2 A control block diagram for generating a first control potential provided in the present application, wherein: is the first control potential, is the actual value of the target grid current, is the differential value of the actual value of the target grid current, t is the time, The proportional coefficient is specifically expressed as the multiplication of the current error value and the proportional coefficient. The obtained product is the same as the differential value of the actual value of the target grid current. The differential value of the actual value of the target grid current is then integrated to obtain the actual value of the target grid current, thereby avoiding direct differentiation of the collected grid current and avoiding the influence of interference in the current collection process on the control of the inverter.

[0088] It should also be noted that in the process of determining the first control potential and the second control potential, the three-phase alternating current of the power grid is first collected to obtain the actual value of the three-phase power grid current, and then the three-phase actual value of the power grid current is converted into the actual value of the power grid current in the dq rotating coordinate system, and then calculation is performed. Correspondingly, when obtaining the grid voltage amplitude, the three-phase alternating current of the power grid is first collected to obtain the three-phase actual value of the power grid voltage, and then the three-phase actual value of the power grid voltage is converted into the actual value of the power grid voltage in the dq rotating coordinate system, so as to determine the grid voltage amplitude.

[0089] As a preferred embodiment, determining the grid voltage frequency, grid voltage phase and grid voltage amplitude synchronization coefficient based on the current control reference value, the grid current actual value and the grid voltage amplitude includes:

[0090] Multiplying the current control reference value by the torque coefficient to determine the mechanical torque value;

[0091] The actual value of the grid current is multiplied by the torque coefficient to determine the electromagnetic torque value;

[0092] determining a torque error value based on a difference between the mechanical torque value and the electromagnetic torque value;

[0093] Calculate the grid voltage frequency based on the torque error value and the swing equation;

[0094] Integrate the grid voltage frequency to determine the grid voltage phase;

[0095] A grid voltage amplitude synchronization coefficient is calculated based on the grid voltage frequency and the grid voltage amplitude.

[0096] In this embodiment, when determining the grid voltage frequency, the current control reference value and the actual grid current value are first multiplied by the torque coefficient respectively to obtain the mechanical torque value and the electromagnetic torque value to simulate the current reference virtual synchronous machine. The mechanical torque refers to the torque output by the synchronous machine, which is used to drive the mechanical device to complete a specific task. The size of the mechanical torque is related to the design and load characteristics of the synchronous machine; the electromagnetic torque refers to the torque generated by the synchronous machine under electromagnetic action. When current passes through the armature coil, the Lorentz force exerted on the armature coil generates a torque, causing the motor to start rotating. The size of the electromagnetic torque is related to the current intensity and the magnetic flux of the electromagnetic field.

[0097] After the electromagnetic torque value and the mechanical torque value are determined, the difference between the mechanical torque value and the electromagnetic torque value is determined as the torque error value, and then the grid voltage frequency is calculated by the swing equation, and the grid voltage frequency is integrated to obtain the grid voltage phase, and finally the grid voltage amplitude synchronization coefficient is calculated according to the determined grid voltage frequency and grid voltage amplitude. Specifically, the grid voltage amplitude synchronization coefficient can be calculated by the closed-loop function of the flux controller.

[0098] The swing equation is , J is the moment of inertia, is the grid voltage frequency, is the differential value of the grid voltage frequency, T m is the mechanical torque value, T e is the electromagnetic torque value. The closed-loop function G of the flux controller fc (s) ,in, is the grid voltage amplitude synchronization coefficient, is the grid voltage amplitude, is the flux control bandwidth, and s in the denominator represents the integral operation in the Laplace transform. Figure 3 , Figure 3 A control block diagram for generating a grid voltage amplitude synchronization coefficient provided in the present application, wherein, through a closed loop function G fc (s) Calculate the grid voltage amplitude synchronization coefficient Afterwards, With grid voltage frequency Multiply and adjust the grid voltage amplitude synchronization coefficient Perform negative feedback regulation.

[0099] As a preferred embodiment, before multiplying the current control reference value and the torque coefficient to determine the mechanical torque value, the method further includes:

[0100] Filtering the current control reference value to obtain a filtered current control reference value;

[0101] The current control reference is multiplied by the torque factor to determine the mechanical torque value, including:

[0102] The filtered current control reference value is multiplied by the torque coefficient to determine the mechanical torque value.

[0103] In this embodiment, the current control reference value is also filtered to avoid the instability of the control system caused by the interference in the current control reference value. Based on this, the filtered current control reference value needs to be multiplied by the torque coefficient to determine the mechanical torque value.

[0104] As a preferred embodiment, it also includes:

[0105] Calculate the damping torque based on the grid voltage frequency and the damping coefficient;

[0106] A torque error value is determined based on a difference between a mechanical torque value and an electromagnetic torque value, including:

[0107] The torque error value is determined based on a difference value obtained by subtracting the electromagnetic torque value and the damping torque from the mechanical torque value.

[0108] In this embodiment, after the grid voltage frequency is determined, the damping torque is also calculated using the grid voltage frequency and the damping coefficient, and the damping torque is added to the feedback adjustment for determining the torque error value. Based on this, the damping torque can be used to simulate the effect of the damping winding of the current reference virtual synchronous machine, so that it can play a role in suppressing changes in the angular frequency of the grid during system transients.

[0109] Since the damping torque is added as a feedback value to the calculation of the torque error value, the swing equation is: , where T d is the damping torque.

[0110] Please refer to Figure 4 , Figure 4 A structural block diagram of generating a grid voltage frequency and a grid voltage phase provided by the present application, wherein only the q-axis component of the current control reference value is selected and the q-axis component of the actual value of the grid current Perform calculations, Indicates filtering of the q-axis component of the current control reference value, k t is the torque coefficient, Indicates that the grid voltage frequency is calculated by the swing equation , Indicates that the grid voltage frequency is integrated to obtain the grid voltage phase , k d is the damping coefficient, is the cutoff frequency of the high-pass filter, Indicates the grid voltage frequency To calculate the damping torque T d .

[0111] In addition, when calculating the second control potential, the second expression can be used for calculation, and the second expression is ,in, is the second control potential, [] T is transposed.

[0112] As a preferred embodiment, before adjusting the modulation wave of the inverter based on the first control potential, the second control potential and the grid voltage phase, the method further includes:

[0113] Determining a disturbance amount in a process of controlling the inverter based on the first control potential, the second control potential, the actual value of the grid voltage, and the actual value of the grid current;

[0114] The modulation wave of the inverter is adjusted based on the first control potential, the second control potential and the grid voltage phase, including:

[0115] Determine the inverter control potential based on the sum of the first control potential and the second control potential minus the difference of the disturbance amount;

[0116] The modulation wave of the inverter is adjusted based on the inverter control potential and the grid voltage phase.

[0117] Considering that there may be disturbances caused by errors or inverter nonlinearity during the control process of the inverter, which will affect the accuracy of the inverter control, in this embodiment, the disturbance amount during the control process of the inverter is also determined based on the first control potential, the second control potential, the actual value of the grid voltage and the actual value of the grid current. Specifically, the sum of the first control potential and the second control potential is first calculated to obtain the target control potential. Since the first control potential and the second control potential are both potentials in the dq rotating coordinate system, the target control potential is also the potential in the dq rotating coordinate system. The disturbance amount is calculated based on the difference between the target control potential and the actual value of the grid voltage, and the actual current value of the grid, so that when the inverter is adjusted based on the first control potential and the second control potential, the calculated disturbance is subtracted to ensure the stability of the inverter during the control process, that is, the target control potential is subtracted from the disturbance amount, and the inverter control potential for adjusting the modulation wave of the inverter can be obtained.

[0118] Please refer to Figure 5 , Figure 5 A control block diagram of a disturbance observer provided in the present application, wherein the parameter expressions of the disturbance observer are:

[0119] ;

[0120] ;

[0121] ;

[0122] ;

[0123] ;

[0124] ;

[0125] ;

[0126] in, is the actual value of the grid current, is the d-axis component of the actual value of the grid current, is the q-axis component of the actual value of the grid current, is the disturbance amount, is the d-axis component of the disturbance, is the q-axis component of the disturbance, u is the input of the disturbance observer, To control the potential for the target, is the d-axis component of the target control potential, is the q-axis component of the target control potential, is the actual value of the grid voltage, is the d-axis component of the actual value of the grid voltage, is the q-axis component of the actual value of the grid voltage, - is the difference between the d-axis component of the target control potential and the d-axis component of the actual value of the grid voltage, - is the difference between the q-axis component of the target control potential and the q-axis component of the actual value of the grid voltage, u is the input of the disturbance observer, y is the output of the disturbance observer, x is the state vector in the disturbance observer, and A, B, and C are all disturbance observer coefficients.

[0127] Based on this, the disturbance observer can be designed as:

[0128] ;

[0129] .

[0130] in, represents the estimated value of the state vector, L is the gain of the disturbance observer, which is used to make the estimated error of the state vector approach 0, ~ are the elements in the L matrix respectively.

[0131] In summary, please refer to Figure 6 , Figure 6 A control block diagram for controlling an inverter provided in the present application, wherein C f is the grid-side filter capacitor, |u| is the amplitude of the actual grid voltage, is the desired value of current control, In order to convert the target control potential in the dq rotating coordinate system into the target control potential in the three-phase abc stationary coordinate system, is the output voltage of the inverter. After the inverter is controlled in this application, the expected response of the output current of the inverter is:

[0132] ;

[0133] The first term on the right side of the equation above shows the first control potential, which is a first-order dynamic response link and is not affected by factors such as the inertia coefficient. The second term represents the current through the filter inductor, which is caused by the voltage vector difference between the second control potential and the actual voltage value of the grid. The voltage vector difference is usually kept at 0 in a stable state.

[0134] Please refer to Figure 7 , Figure 7 A schematic diagram of the structure of a control system of an inverter provided in the present application, the system comprising:

[0135] A first determining unit 71, configured to determine a grid voltage frequency, a grid voltage phase, and a grid voltage amplitude synchronization coefficient based on a current control reference value, an actual grid current value, and a grid voltage amplitude;

[0136] A first conversion unit 72, configured to convert a current control reference value, a grid voltage frequency and a grid current actual value into a first control potential;

[0137] A second determining unit 73, configured to determine a second control potential based on a grid voltage frequency and a grid voltage amplitude synchronization coefficient;

[0138] The adjustment unit 74 is used to adjust the modulation wave of the inverter based on the first control potential, the second control potential and the grid voltage phase, so that the output current of the output end of the inverter follows the current control reference value, the frequency of the output voltage of the output end of the inverter follows the grid voltage frequency, and the phase of the output voltage of the output end of the inverter follows the grid voltage phase.

[0139] For an introduction to the control system of the inverter provided by the present invention, please refer to the above method embodiment, and the present invention will not be repeated here.

[0140] Please refer to Figure 8 , Figure 8 A schematic diagram of the structure of a control device for an inverter provided in the present application, the device comprising:

[0141] A memory 81, used for storing computer programs;

[0142] The processor 82 is used to implement the steps of the inverter control method as described above when executing the computer program.

[0143] For an introduction to the control device of the inverter provided by the present invention, please refer to the above method embodiment, and the present invention will not be described in detail here.

[0144] Please refer to Fig. 9 , Fig. 9 A schematic diagram of the structure of a non-volatile storage medium provided in the present application. A computer program 92 is stored on the non-volatile storage medium 91. When the computer program 92 is executed by a processor, the steps of the inverter control method as described above are implemented.

[0145] For an introduction to the non-volatile storage medium 91 provided by the present invention, please refer to the above method embodiment, and the present invention will not be repeated here.

[0146] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0147] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for an inverter, characterized in that: include: Determine a grid voltage frequency, a grid voltage phase, and a grid voltage amplitude synchronization coefficient based on a current control reference value, an actual grid current value, and a grid voltage amplitude; converting the current control reference value, the grid voltage frequency and the grid current actual value into a first control potential; determining a second control potential based on the grid voltage frequency and the grid voltage amplitude synchronization coefficient; The modulation wave of the inverter is adjusted based on the first control potential, the second control potential and the grid voltage phase so that the output current at the output end of the inverter follows the current control reference value, the frequency of the output voltage at the output end of the inverter follows the grid voltage frequency, and the phase of the output voltage at the output end of the inverter follows the grid voltage phase.

2. The inverter control method according to claim 1, characterized in that: Generating a first control potential based on the current control reference value, the grid voltage frequency and the grid current actual value comprises: Calculating a current error value based on the current control reference value and the actual value of the grid current; Performing proportional integral calculation based on the current error value to determine a target grid current actual value and a differential value of the target grid current actual value; The first control potential is determined by the target grid current actual value, a differential value of the target grid current actual value, and the grid voltage frequency.

3. The control method of the inverter according to claim 2, characterized in that: Determining the first control potential by using the target grid current actual value, the differential value of the target grid current actual value, and the grid voltage frequency includes: Calculating the first control potential using a first expression based on the target grid current actual value, the differential value of the target grid current actual value, and the grid voltage frequency; The first expression is: ； in, is the d-axis component of the first control potential, is the q-axis component of the first control potential, is the grid-side filter resistor, is the grid-side filter inductor, is the grid voltage frequency, is the d-axis component of the actual value of the target grid current, is the q-axis component of the actual value of the target grid current, is the d-axis component of the differential value of the actual value of the target grid current, It is the q-axis component of the differential value of the actual value of the target grid current.

4. The control method of the inverter according to claim 1, characterized in that: The grid voltage frequency, grid voltage phase and grid voltage amplitude synchronization coefficient are determined based on the current control reference value, the grid current actual value and the grid voltage amplitude, including: multiplying the current control reference value by a torque coefficient to determine a mechanical torque value; Multiplying the actual value of the grid current by the torque coefficient to determine the electromagnetic torque value; determining a torque error value based on a difference between the mechanical torque value and the electromagnetic torque value; Calculating the grid voltage frequency based on the torque error value and the swing equation; Integrating the grid voltage frequency to determine the grid voltage phase; The grid voltage amplitude synchronization coefficient is calculated based on the grid voltage frequency and the grid voltage amplitude.

5. The control method of the inverter according to claim 4, characterized in that: Before multiplying the current control reference value by the torque coefficient to determine the mechanical torque value, the method further includes: Performing filtering on the current control reference value to obtain the filtered current control reference value; Multiplying the current control reference value by a torque coefficient to determine a mechanical torque value comprises: The filtered current control reference value is multiplied by a torque coefficient to determine a mechanical torque value.

6. The inverter control method according to claim 4, characterized in that: Also includes: Calculating a damping torque based on the grid voltage frequency and a damping coefficient; Determining a torque error value based on a difference between the mechanical torque value and the electromagnetic torque value includes: A torque error value is determined based on a difference value obtained by subtracting the electromagnetic torque value and the damping torque from the mechanical torque value.

7. The inverter control method according to any one of claims 1 to 6, characterized in that: Before adjusting the modulation wave of the inverter based on the first control potential, the second control potential and the grid voltage phase, the method further includes: determining a disturbance amount in a process of controlling the inverter based on the first control potential, the second control potential, an actual value of a grid voltage, and an actual value of a grid current; The method further comprises: adjusting a modulation wave of an inverter based on the first control potential, the second control potential and the grid voltage phase, comprising: Determine the inverter control potential based on the sum of the first control potential and the second control potential minus the difference of the disturbance amount; The modulation wave of the inverter is adjusted based on the inverter control potential and the grid voltage phase.

8. A control system for an inverter, characterized in that: include: A first determination unit is used to determine a grid voltage frequency, a grid voltage phase and a grid voltage amplitude synchronization coefficient based on a current control reference value, an actual grid current value and a grid voltage amplitude; A first conversion unit, configured to convert the current control reference value, the grid voltage frequency and the grid current actual value into a first control potential; a second determining unit, configured to determine a second control potential based on the grid voltage frequency and the grid voltage amplitude synchronization coefficient; An adjustment unit is used to adjust the modulation wave of the inverter based on the first control potential, the second control potential and the grid voltage phase, so that the output current of the output end of the inverter follows the current control reference value, the frequency of the output voltage of the output end of the inverter follows the grid voltage frequency, and the phase of the output voltage of the output end of the inverter follows the grid voltage phase.

9. A control device for an inverter, characterized in that: include: Memory for storing computer programs; A processor, configured to implement the steps of the inverter control method according to any one of claims 1 to 7 when executing a computer program.

10. A non-volatile storage medium, characterized in that: The non-volatile storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the inverter control method according to any one of claims 1 to 7 are implemented.

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