Energy storage inverter and control method, device and computer readable storage medium thereof

Abstract

The embodiment of the application provides a kind of energy storage inverter control method, comprising: obtaining the output current of the virtual synchronous generator constructed in advance;The synchronous angular velocity of the power grid and the voltage value of the point of common coupling are obtained, the point of common coupling is the coupling point of the power grid and the energy storage inverter;Determine whether the synchronous angular velocity of the power grid and the voltage value of the point of common coupling are within the allowable range;In response to determining that the synchronous angular velocity of the power grid and / or the voltage value of the point of common coupling are not within the allowable range, then input power regulation instruction to the virtual synchronous generator, to update the output current of the virtual synchronous generator;According to the output current of virtual synchronous generator, determine the command current, according to the command current, update the output state of energy storage inverter.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of grid-connected inverter control, and particularly relates to a storage inverter, a control method and device thereof, and a computer readable storage medium. BACKGROUND

[0002] As a link between distributed power sources such as photovoltaic power and wind power and a power grid, a grid-connected inverter belongs to power electronic devices, has almost no rotational inertia, and is difficult to participate in power grid regulation. By drawing on the operation experience of a traditional power system, a control strategy based on a virtual synchronous generator (VSG) is applied to the control of a grid-connected inverter. The VSG can increase the inertia of the grid-connected inverter, but the commonly used control method is greatly affected by feedback errors, it is difficult to achieve smooth switching between grid-connected and off-grid, and it is easy to cause instability of the power grid system. SUMMARY

[0003] Embodiments of the present application provide a storage inverter, a control method and device thereof, and a computer readable storage medium, and aim to solve the problem of non-smooth switching between grid-connected and off-grid in the prior art.

[0004] In a first aspect, embodiments of the present application provide a control method of a storage inverter, comprising: obtaining an output current of a pre-constructed virtual synchronous generator; obtaining a synchronous angular velocity of a power grid and a voltage value of a point of common coupling, the point of common coupling being a coupling point of the power grid and the storage inverter; determining whether the synchronous angular velocity of the power grid and the voltage value of the point of common coupling are both within an allowable range; in response to determining that the synchronous angular velocity of the power grid and / or the voltage value of the point of common coupling is not within the allowable range, inputting a power regulation instruction to the virtual synchronous generator to update the output current of the virtual synchronous generator; determining an instruction current according to the output current of the virtual synchronous generator, and updating an output state of the storage inverter according to the instruction current.

[0005] In some embodiments, the obtaining of the output current of the pre-constructed virtual synchronous generator comprises: obtaining a power instruction value and a power measurement value of the storage inverter; inputting the power instruction value and the power measurement value of the storage inverter into a mathematical model of the virtual synchronous generator to determine the output current of the virtual synchronous generator.

[0006] In some embodiments, before determining the instruction current according to the output current of the virtual synchronous generator, comprising: obtaining the synchronous angular velocity of the power grid and the voltage value of the point of common coupling, the point of common coupling being the coupling point of the power grid and the energy storage inverter; determining whether the synchronous angular velocity of the power grid and the voltage value of the point of common coupling are both within the allowable range; in response to determining that the synchronous angular velocity of the power grid and / or the voltage value of the point of common coupling are not within the allowable range, inputting a power adjustment instruction to the virtual synchronous generator to update the output current of the virtual synchronous generator.

[0007] In some embodiments, the power instruction value of the energy storage inverter includes an active power instruction value and a reactive power instruction value of the energy storage inverter, and the power measurement value of the energy storage inverter includes an active power measurement value and a reactive power measurement value of the energy storage inverter; the inputting the power instruction value of the energy storage inverter and the power measurement value into the virtual synchronous generator to determine the output current of the virtual synchronous generator comprises: inputting the active power instruction value and the active power measurement value of the energy storage inverter into the virtual synchronous generator to determine the power angle of the virtual synchronous generator; inputting the reactive power instruction value and the reactive power measurement value of the energy storage inverter into the virtual synchronous generator to determine the excitation voltage of the virtual synchronous generator; determining the output voltage of the virtual synchronous generator according to the power angle and the excitation voltage of the virtual synchronous generator; obtaining the equivalent resistance and the equivalent inductance of the virtual synchronous generator, and determining the output current of the virtual synchronous generator according to the output voltage of the virtual synchronous generator and the equivalent resistance and the equivalent inductance of the virtual synchronous generator.

[0008] In some embodiments, the inputting a power adjustment instruction to the virtual synchronous generator to update the output current of the virtual synchronous generator in response to determining that the synchronous angular velocity of the power grid and / or the voltage value of the point of common coupling are not within the allowable range comprises: determining whether the synchronous angular velocity of the power grid is within the allowable range; in response to determining that the synchronous angular velocity of the power grid is not within the allowable range, performing the following operations: inputting a first power adjustment instruction to the virtual synchronous generator, the first power adjustment instruction being an active power adjustment instruction; updating the power angle of the virtual synchronous generator according to the first power adjustment instruction, the active power instruction value and the active power measurement value of the energy storage inverter based on the virtual synchronous generator; updating the output current of the virtual synchronous generator according to the power angle and the excitation voltage of the virtual synchronous generator.

[0009] In some embodiments, the step of inputting a power regulation instruction to the virtual synchronous generator to update the output current of the virtual synchronous generator in response to determining that the synchronous angular velocity of the power grid and / or the voltage value of the point of common coupling is not within the allowable range comprises: determining whether the voltage value of the point of common coupling is within the allowable range; in response to determining that the voltage value of the point of common coupling is not within the allowable range, inputting a second power regulation instruction to the virtual synchronous generator, the second power regulation instruction being a reactive power regulation instruction; updating the field voltage of the virtual synchronous generator based on the virtual synchronous generator, the reactive power instruction value and the reactive power measurement value of the energy storage inverter according to the second power regulation instruction; and updating the output current of the virtual synchronous generator according to the power angle and the field voltage of the virtual synchronous generator.

[0010] In some embodiments, the step of determining an instruction current based on the output current of the virtual synchronous generator and updating the output state of the energy storage inverter according to the instruction current comprises: extracting a harmonic component in the load current and superimposing the harmonic component and the output current of the virtual synchronous generator to obtain a superimposed current; obtaining the output current of the energy storage inverter and a pre-constructed current controller; inputting the output current of the energy storage inverter and the superimposed current into the current controller to determine the output current of the current controller; and taking the output current of the current controller as the instruction current and adjusting the output state of the energy storage inverter according to the instruction current.

[0011] In some embodiments, the current controller comprises a repetitive controller and a proportional controller connected in parallel.

[0012] In some embodiments, the step of superimposing the harmonic component and the output current of the virtual synchronous generator to obtain a superimposed current comprises: obtaining a harmonic clipping coefficient k I ; multiplying the harmonic component by the harmonic clipping coefficient k I and superimposing the harmonic component and the output current of the virtual synchronous generator to obtain the superimposed current.

[0013] In some embodiments, the harmonic clipping coefficient k I is determined by the following equation set:

[0014]

[0015] wherein 0 < k I < 1; I a is a current eigenvalue of the energy storage inverter, I lim is a current limit value of the energy storage inverter, I load_基波 is a fundamental value of the load current, and I d_refis a d-axis current of the virtual synchronous generator, I q_ref is a q-axis current of the virtual synchronous generator; U dc is a DC voltage of the energy storage inverter, L 逆 is a filter inductance of the energy storage inverter; k is an approximate value coefficient; ω g is an angular velocity of the power grid.

[0016] In some embodiments, extracting a harmonic component in the load current comprises:

[0017] obtaining a phase angle of the power grid and the load current;

[0018] harmonically filtering the load current according to the phase angle of the power grid to determine a fundamental value of the load current;

[0019] determining the harmonic component of the load current according to the load current and the fundamental value of the load current.

[0020] In some embodiments, superimposing the harmonic component and an output current of the virtual synchronous generator to obtain a superimposed current comprises:

[0021] obtaining a phase angle of the power grid and a d-axis current and a q-axis current of the virtual synchronous generator;

[0022] performing a phase coordinate transformation on the d-axis current and the q-axis current of the virtual synchronous generator according to the phase angle of the power grid to determine the output current of the virtual synchronous generator;

[0023] superimposing the harmonic component and the output current of the virtual synchronous generator to obtain a superimposed current.

[0024] In some embodiments, the energy storage inverter control method further comprises:

[0025] obtaining a phase angle and a three-phase voltage of the power grid;

[0026] performing a phase coordinate transformation on the three-phase voltage of the power grid according to the phase angle of the power grid to determine a d-axis voltage and a q-axis voltage of the power grid;

[0027] adjusting the d-axis current and the q-axis current of the virtual synchronous generator according to the d-axis voltage and the q-axis voltage of the power grid.

[0028] In a second aspect, the embodiments of the present application provide a storage inverter control device, comprising: a virtual power generation control circuit configured to perform the following operations: obtaining an output current of a pre-constructed virtual synchronous generator; determining an instruction current according to the output current of the virtual synchronous generator, and updating an output state of the storage inverter according to the instruction current; a frequency limiting control circuit configured to perform the following operations: obtaining a synchronous angular velocity of a power grid; determining whether the synchronous angular velocity of the power grid is within an allowable range; in response to determining that the synchronous angular velocity of the power grid is not within the allowable range, inputting a first power regulation instruction to the virtual synchronous generator to update the output current of the virtual synchronous generator; an amplitude limiting control circuit configured to perform the following operations: obtaining voltage values of a point of common coupling, the point of common coupling being a coupling point of the power grid and the storage inverter; determining whether the voltage values of the point of common coupling are within an allowable range; in response to determining that the voltage values of the point of common coupling are not within the allowable range, inputting a second power regulation instruction to the virtual synchronous generator to update the output current of the virtual synchronous generator.

[0029] In some embodiments, the storage inverter control device further comprises a composite current control circuit comprising a current controller; the composite current control circuit is configured to perform the following operations: extracting a harmonic component in a load current, and superimposing the harmonic component and the output current of the virtual synchronous generator to obtain a superimposed current; obtaining an output current of the storage inverter; inputting the output current of the storage inverter and the superimposed current to the current controller to determine an output current of the current controller; taking the output current of the current controller as an instruction current, and updating an output state of the storage inverter according to the instruction current.

[0030] In a third aspect, the embodiments of the present application provide a storage inverter, comprising a memory and a processor, the memory storing a computer program, and the computer program is executed by the processor to implement the storage inverter control method in any of the above embodiments.

[0031] In a fourth aspect, the embodiments of the present application provide a computer readable storage medium, which stores a computer program, and the computer program is loaded by a processor to perform the steps in the storage inverter control method in any of the above embodiments.

[0032] The embodiments of the present application introduce a frequency limiting link and an amplitude limiting link on the basis of a virtual synchronous generator, continuously monitor the synchronous angular velocity of the power grid and the voltage value of the point of common coupling, and input a power adjustment instruction to the virtual synchronous generator to update the output current of the virtual synchronous generator when any of the two exceeds the allowed range. In this way, when the power grid is disturbed due to an unexpected accident such as a power failure or when switching between grid-connected and off-grid, the power can be quickly output to intervene in the output state of the energy storage inverter, so that the output voltage and output current of the energy storage inverter remain stable, the smoothness of the grid-connected and off-grid switching process is improved, the output state of the energy storage inverter is prevented from changing abruptly, and the power quality of the grid and load safety and fast switching between grid-connected and off-grid is ensured.

[0033] Some embodiments of the present application use a virtual synchronous generator control strategy in the power outer loop, use a repetitive control to control the output current of the virtual synchronous generator in the current inner loop, and use proportional control to dynamically compensate the repetitive control to improve the dynamic response capability, thereby realizing the combination of the virtual synchronous generator and the repetitive control strategy. On the one hand, the dual-loop control requirement of the outer loop power control and the inner loop current control is met, and on the other hand, based on the volatility characteristics of the distributed power supply, the excess capacity of the energy storage inverter can be used to suppress the load harmonics in the power grid in time, improve the power quality of the power grid, and improve the capacity utilization efficiency of the energy storage inverter.

[0034] Some embodiments of the present application use a phase-locked loop to lock the phase of the harmonic filtering link, which can ensure that the fundamental value of the determined load current is relatively accurate, thereby ensuring the accuracy of the harmonic component extracted from the load current and providing an accurate reference for subsequent harmonic suppression.

[0035] Some embodiments of the present application use a phase-locked loop to lock the phase of the phase coordinate transformation link, which can ensure the phase synchronization of the transformation process and the accuracy of the output current, thereby obtaining a relatively accurate superimposed current and providing an accurate basis for subsequent harmonic suppression. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0037] Figure 1 is a flowchart of the energy storage inverter control method provided by some embodiments of the present application;

[0038] Figure 2 is a partial flowchart of the energy storage inverter control method provided by some embodiments of the present application;

[0039] Figure 3 is a block diagram of a method for controlling a storage inverter according to some embodiments of the present application;

[0040] Figure 4 is another partial flowchart of a method for controlling a storage inverter according to some embodiments of the present application;

[0041] Figure 5 is yet another partial flowchart of a method for controlling a storage inverter according to some embodiments of the present application;

[0042] Figure 6 is a topology diagram of a micro-grid system to which a method for controlling a storage inverter according to some embodiments of the present application is applied;

[0043] Figure 7 is yet another partial flowchart of a method for controlling a storage inverter according to some embodiments of the present application;

[0044] Figure 8 is still another partial flowchart of a method for controlling a storage inverter according to some embodiments of the present application;

[0045] Figure 9 is still another partial flowchart of a method for controlling a storage inverter according to some embodiments of the present application;

[0046] Figure 10 is still another partial flowchart of a method for controlling a storage inverter according to some embodiments of the present application;

[0047] Figure 11 is still another partial flowchart of a method for controlling a storage inverter according to some embodiments of the present application;

[0048] Figure 12 is another block diagram of a method for controlling a storage inverter according to some embodiments of the present application;

[0049] Figure 13 is a waveform diagram of a load current obtained by harmonic suppression simulation of a method for controlling a storage inverter according to some embodiments of the present application;

[0050] Figure 14 is a spectrum diagram of a grid-connected current obtained by harmonic suppression simulation of a method for controlling a storage inverter according to some embodiments of the present application;

[0051] Figure 15 is a waveform diagram of a grid-connected current obtained by harmonic suppression simulation of a method for controlling a storage inverter according to some embodiments of the present application;

[0052] Figure 16 is a spectrum diagram of a grid-connected current obtained by harmonic suppression simulation of a method for controlling a storage inverter according to some embodiments of the present application;

[0053] Figure 17 is a waveform diagram of output current of the energy storage inverter obtained by simulating harmonic suppression by the energy storage inverter control method provided by some embodiments of the present application;

[0054] Figure 18 is a waveform diagram of output voltage of the energy storage inverter obtained by simulating on-off grid switching by the energy storage inverter control method provided by some embodiments of the present application;

[0055] Figure 19 is a waveform diagram of output current of the energy storage inverter obtained by simulating on-off grid switching by the energy storage inverter control method provided by some embodiments of the present application;

[0056] Figure 20 is a numerical change diagram of output voltage of the energy storage inverter obtained by simulating on-off grid switching by the energy storage inverter control method provided by some embodiments of the present application;

[0057] Figure 21 is a numerical change diagram of frequency of the energy storage inverter obtained by simulating on-off grid switching by the energy storage inverter control method provided by some embodiments of the present application;

[0058] Figure 22 is a structural diagram of the energy storage inverter control device provided by some embodiments of the present application.

[0059] Figure 23 is a structural diagram of the energy storage inverter provided by some embodiments of the present application. DETAILED DESCRIPTION

[0060] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0061] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are intended to refer to the orientation or position of the apparatus or element shown in the drawings as viewed in the drawings under the normal or upright position, and are merely used for convenience and for brevity in describing the present application and the related drawings, and therefore, they are not intended to indicate or imply that the apparatus or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed or understood in this regard as limiting the present application. In addition, the terms "first", "second", and the like, are used only to describe all of the embodiments, and do not imply or suggest relative importance or a specific number of the technical features indicated. Thus, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, "a plurality of" means two or more, unless otherwise expressly and specifically limited.

[0062] "A and / or B" includes the following three combinations: only A, only B, and a combination of A and B.

[0063] The use of "adapted to" or "configured to" in the present application means open and inclusive language that does not exclude devices adapted to or configured to perform additional tasks or steps. In addition, the use of "based on" means open and inclusive, as a process, step, calculation or other action that is "based on" one or more stated conditions or values can in practice be based on additional conditions or values beyond those stated.

[0064] In the present application, the word "exemplary" is used to mean "serving as an example, instance, or illustration." Any implementation described as "exemplary" in the present application is not necessarily to be construed as preferred or advantageous over other implementations. The following description is presented to enable any person skilled in the art to make and use the present application. In the following description, for purposes of explanation, specific details are set forth. It will be apparent to those skilled in the art that the present application can be practiced without the specific details. In other instances, well-known structures and processes are not described in detail in order to avoid obscuring the present application. Thus, the present application is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features presented herein.

[0065] New energy such as photovoltaic power generation and wind power generation has better environmental protection, but due to the particularity of the power generation method, there is great volatility. Photovoltaic power generation is to generate electricity by using solar energy, and the power generation process can only be carried out during the day and cannot be carried out at night. In addition, the power generation power is significantly affected by the weather, has obvious intermittency and unpredictability, and is easy to cause impact on the power grid 2. Similarly, the power generation power of wind power generation is also significantly affected by the weather and seasons, has intermittency and unpredictability, and is easy to cause large power fluctuation. The energy storage inverter 10 has energy storage capability, and can store the power output by the distributed power supply during the load valley, and release the stored power during the load peak to reduce the pressure on the power grid 2 and smooth the fluctuation of the distributed power supply on the power grid 2.

[0066] As shown in Figure 1 , in a first aspect, the embodiments of the present application provide a kind of energy storage inverter control method, using virtual synchronous generation control to control energy storage inverter 10, and introduce frequency limiting link and limiting link, to guarantee the smooth switching between on-grid and off-grid state.The control method includes S10-S50.

[0067] S10: obtain the output current of the pre-constructed virtual synchronous generator. The virtual synchronous generator is based on the mathematical model of the synchronous generator, which is embedded in the energy storage inverter 10, so that the energy storage inverter 10 as a static power electronic device can be simulated as a rotating motor. As shown in Figure 6 , in some examples, the virtual synchronous generator system can include energy storage inverter 10, three-phase filter inductance L i And three-phase filter capacitance C f .

[0068] The body mathematical model of the synchronous generator includes mechanical equation and electromagnetic equation, which reflect the inertia and damping characteristics of the synchronous generator respectively. When mainly focusing on the simulation of inertia characteristics, only the mechanical equation can be used. In some embodiments, the mechanical equation of the virtual synchronous generator is:

[0069]

[0070] Wherein, J is the moment of inertia of the virtual synchronous generator, T m is the mechanical torque of the virtual synchronous generator, T e is the electromagnetic torque of the virtual synchronous generator, D is the damping coefficient, ω g is the synchronous angular velocity of the power grid 2, ω R is the rotor angular velocity of the virtual synchronous generator. Here, the moment of inertia J and the damping coefficient D are usually artificially given according to the actual parameters of the energy storage inverter 10.

[0071] As shown in Figure 2As shown, in some examples, S10 can include S11-S12.

[0072] S11: Obtain the power instruction value and the power measurement value of the energy storage inverter 10. The power instruction value of the energy storage inverter 10 is the instruction power required to be output by the energy storage inverter 10; the power measurement value of the energy storage inverter 10 is the actual output power of the energy storage inverter 10 measured in real time.

[0073] S12: Input the power instruction value and the power measurement value of the energy storage inverter 10 into the virtual synchronous generator to determine the output current of the virtual synchronous generator. The virtual synchronous generator is based on the mathematical model of the synchronous generator, and the power instruction value and the power measurement value are input into the synchronous generator as input quantities, which can drive the synchronous generator to generate virtual power and generate corresponding output current. The power instruction value is a given value, and the power measurement value is a measured value.

[0074] In some embodiments, the power instruction value of the energy storage inverter 10 includes the active power instruction value P * and the reactive power instruction value Q * of the energy storage inverter 10, and the power measurement value of the energy storage inverter 10 includes the active power measurement value P meas and the reactive power measurement value Q meas of the energy storage inverter 10. The active power is the electrical power required to keep the electrical equipment running normally, that is, the electrical power that converts electrical energy into other forms of energy such as mechanical energy, light energy, and thermal energy; the reactive power is the electrical power in the electrical equipment to establish and maintain the magnetic field, which does not work externally, but is converted into other forms of energy.

[0075] Figure 3 A block diagram of the energy storage inverter control method based on virtual synchronous generation control is shown. Wherein, P m is the active power of the virtual synchronous generator, K gd is the proportional coefficient along the d-axis of the virtual synchronous generator, K gq is the proportional coefficient along the q-axis of the virtual synchronous generator, s is the complex variable in Laplace transform, i.e. Laplace operator, θ R is the rotor phase angle of the virtual synchronous generator, θ g is the phase angle of the power grid, and PI is proportional integral control. Figures 3-4 As shown, correspondingly, S12 can include S121-S124.

[0076] S121: Input the active power instruction value P * and the active power measurement value P measThe input of the virtual synchronous generator is determined to determine the power angle δ of the virtual synchronous generator. The power angle is the phase angle difference between the excitation potential and the terminal voltage of the generator. In some examples, a transfer function between the input power of the virtual synchronous generator and the power angle of the virtual synchronous generator can be determined according to a mechanical equation of the virtual synchronous generator; in this way, the active power command value and the active power measurement value of the energy storage inverter 10 are taken as the input power of the virtual synchronous generator, and the power angle of the virtual synchronous generator can be determined according to the transfer function. For example, the active power command value and the active power measurement value of the energy storage inverter 10 can be compared, and the adjustment current required by the virtual synchronous generator to output can be determined according to the power difference between the two, and the actual active power output of the energy storage inverter 10 is adjusted by using the adjustment current.

[0077] S122: The reactive power command value Q * of the energy storage inverter 10 is input into the virtual synchronous generator VSG to determine the excitation voltage E meas of the virtual synchronous generator. f In some examples, a transfer function between the input power of the virtual synchronous generator and the power angle of the virtual synchronous generator can be determined according to an electromagnetic equation of the virtual synchronous generator; in this way, the reactive power command value and the reactive power measurement value of the energy storage inverter 10 are taken as the input power of the virtual synchronous generator, and the excitation voltage of the virtual synchronous generator can be determined according to the transfer function.

[0078] S123: The output voltage of the virtual synchronous generator is determined according to the power angle and the excitation voltage of the virtual synchronous generator. Based on the mathematical model of the synchronous generator, the output voltage of the synchronous generator can be solved under the premise of the determination of the power angle and the excitation voltage. Here, the output voltage of the virtual synchronous generator can be a three-phase voltage.

[0079] S124: The equivalent resistance R and the equivalent inductance L of the virtual synchronous generator are obtained, and the output current of the virtual synchronous generator is determined according to the output voltage, the equivalent resistance R and the equivalent inductance L of the virtual synchronous generator.

[0080] S20: As shown in Figure 1 , the synchronous angular velocity of the power grid 2 and the voltage value of the point of common coupling are obtained. The power grid 2 refers to an alternating current power grid, and the point of common coupling is the coupling point of the power grid 2 and the energy storage inverter 10.

[0081] S30: It is determined whether the synchronous angular velocity ω g of the power grid 2 and the voltage value V PCC of the point of common coupling (PCC) are both within the allowable range. Here, the synchronous angular velocity of the power grid 2 corresponds to the frequency allowable range, and the voltage value of the point of common coupling corresponds to the voltage allowable range. As shown in Figure 3 , ωmax and ω min ω in sequence g The upper and lower limits of allowable limits, and V max and V min V in sequence PCC The upper and lower limits of the allowable limits.

[0082] S40: In response to determining that the synchronism angular velocity of the power grid 2 and / or the voltage value of the common coupling point are outside the allowable range, a power regulation command is input to the virtual synchronous generator to update the output current of the virtual synchronous generator. When a disturbance occurs due to a fault or power outage in the power grid 2, at least one of the synchronism angular velocity of the power grid 2 and the voltage value of the common coupling point will become abnormal, exceeding the upper limit or falling below the lower limit of the allowable range. At this time, by inputting a power regulation command to the virtual synchronous generator, the output current of the virtual synchronous generator can be adjusted and updated to the target value, thereby intervening in and controlling the output state of the energy storage inverter 10, keeping the output voltage and output current of the energy storage inverter 10 stable, preventing sudden changes in the output state of the energy storage inverter 10, ensuring the safety of the power grid and load, and providing power quality for rapid off-grid switching.

[0083] like Figures 3-5 As shown, in some embodiments, considering that the output current of the virtual synchronous generator is affected by the power angle and excitation voltage of the virtual synchronous generator, the output current of the virtual synchronous generator can be updated by updating the power angle and / or excitation voltage of the virtual synchronous generator. In some examples, the output current of the virtual synchronous generator can be updated by updating the power angle of the virtual synchronous generator. S30 may include S31, and S40 may include S41.

[0084] S31: Determine whether the synchronizing angular velocity of power grid 2 is within the allowable range.

[0085] S41: In response to the determination that the synchronization angular velocity of power grid 2 is not within the allowable range, execute S411 to S412.

[0086] S411: Input a first power regulation command to the virtual synchronous generator, wherein the first power regulation command is an active power regulation command.

[0087] S412: updating the power angle of the virtual synchronous generator based on the virtual synchronous generator according to the first power regulation instruction, the active power instruction value and the active power measurement value of the energy storage inverter 10. Here, compared with S121, in addition to the active power instruction value and the active power measurement value of the energy storage inverter 10, the first power regulation instruction is also input into the virtual synchronous generator; in this way, the input of the virtual synchronous generator is changed to update, and accordingly, the power angle of the virtual synchronous generator determined according to the transfer function as in S121 is also changed to update.

[0088] In other examples, the updating of the output current of the virtual synchronous generator can be realized by updating the field voltage of the virtual synchronous generator, and S30 can include S32 and S40 can include S42.

[0089] S32: determining whether the voltage value of the point of common coupling is within the allowable range.

[0090] S42: in response to determining that the voltage value of the point of common coupling is not within the allowable range, performing S421-S422.

[0091] S421: inputting a second power regulation instruction into the virtual synchronous generator, the second power regulation instruction being a reactive power regulation instruction.

[0092] S422: updating the field voltage of the virtual synchronous generator based on the virtual synchronous generator according to the second power regulation instruction, the reactive power instruction value and the reactive power measurement value of the energy storage inverter 10. Here, compared with S122, in addition to the reactive power instruction value and the reactive power measurement value of the energy storage inverter 10, the second power regulation instruction is also input into the virtual synchronous generator; in this way, the input of the virtual synchronous generator is changed to update, and accordingly, the power angle of the virtual synchronous generator determined according to the transfer function as in S122 is also changed to update.

[0093] Based on this, S123 may include S123': updating the output current of the virtual synchronous generator according to the power angle and excitation voltage of the virtual synchronous generator. In some examples, the power angle of the virtual synchronous generator is updated while the excitation voltage remains unchanged; the output current of the virtual synchronous generator can be updated according to the updated power angle and the original excitation voltage without executing S421 to S422. In other examples, the power angle of the virtual synchronous generator remains unchanged while the excitation voltage is updated; the output current of the virtual synchronous generator can be updated according to the original power angle and the updated excitation voltage without executing S411 to S412. In still other examples, both the power angle and the excitation voltage of the virtual synchronous generator are updated; the output current of the virtual synchronous generator can be updated according to the updated power angle and the updated excitation voltage, executing S41, S42, and S123'. It should be noted that there is no sequential requirement between S31 to S41 and S32 to S42; they are independent steps.

[0094] Of course, in response to the determination that the synchronous angular velocity of the power grid 2 and the voltage value of the common coupling point are both within the allowable range, no power regulation command is input to the virtual synchronous generator. If the synchronous angular velocity of the power grid 2 and the voltage value of the common coupling point are both within the allowable range, it indicates that the power grid 2 has not experienced any abnormal fluctuations such as faults or power outages, and no intervention is required for the energy storage inverter 10.

[0095] S50: such as Figure 1 As shown, the command current is determined based on the output current of the virtual synchronous generator, and the output state of the energy storage inverter 10 is updated based on the command current. After the output current of the virtual synchronous generator is determined, the final command current can be further determined based on it; the energy storage inverter 10 is adjusted according to the command current so that the output state of the energy storage inverter 10 is updated to the control target state. The adjustment and update of the energy storage inverter 10 based on the command current can convert the command current into a command voltage, and can be implemented using different control methods such as pulse width modulation (PWM). Other parameters related to the corresponding control method can also be further introduced, which are not limited in this embodiment.

[0096] In some embodiments, the output current of the virtual synchronous generator can be controlled to obtain the command current, so that the command current has a better regulation effect and ensures the power quality of the power grid 2. Figure 6 A topology diagram of a microgrid system 1 under which the energy storage inverter control method operates is shown. Microgrid system 1 is connected to grid 2 via energy storage inverter 10. Load 3 is connected to grid 2, and a current controller 441 is introduced to perform composite control on the output current of a virtual synchronous generator. Wherein, U abcI is the three-phase voltage of power grid 2. v_abc I is the three-phase current output by the energy storage inverter 10 to the grid 2. d_ref I q_ref For the d-axis and q-axis currents of the virtual synchronous generator, I load_abc The load current can be determined through sampling.

[0097] like Figures 6-7 As shown, S50 may include S51 to S54.

[0098] S51: Extract load current I load_abc The harmonic components in the data, and the harmonic components and the output current I of the virtual synchronous generator. ref Superimposed currents are obtained. The load current is the current flowing through load 3, which may contain certain harmonic components; these harmonic components are called harmonic currents. For example, the load current of an uncontrolled rectified load will contain more harmonic components. Here, the harmonic components in the load current can be extracted using a harmonic filtering stage. In some examples, I... ref The d-axis current I of the virtual synchronous generator can be used as a reference. d_ref and q-axis current I q_ref Determined through phase coordinate transformation. For example, the phase coordinate transformation can be a dq / abc transformation. The dq / abc transformation can determine the d-axis current I in a synchronously rotating coordinate system. d_ref The q-axis current is converted into the phase current in a three-phase coordinate system, thereby determining the output current I of the virtual synchronous generator. ref .

[0099] like Figures 7-8 As shown, in some examples, S51 may include S511 to S512.

[0100] S511: Obtain the harmonic limiting coefficient k I For example, the harmonic limiting factor k I It can be determined by the following system of equations:

[0101]

[0102] Among them, 0 <k I <1;I a The current characteristic value of the energy storage inverter 10 is determined based on the hardware parameters of the energy storage inverter 10, characterizing the hardware characteristics of the energy storage inverter 10; I lim The current limit for energy storage inverter 10; I load_基波 The fundamental value of the load current can be the load current I. load_abc The value obtained after harmonic filtering; I d_ref Let I be the d-axis current of the virtual synchronous generator.q_ref is a q-axis current of the virtual synchronous generator; U dc is a DC voltage of the energy storage inverter 10, L 逆 is a filter inductance of the energy storage inverter 10; k is an approximate value coefficient; ω g is an angular velocity of the power grid 2. Here, k can be determined by using Taylor series to approximate the maximum transient amount of harmonic currents below a target number; for example, for harmonic currents below the 25th order, the approximate value coefficient k is

[0103] S512: multiplying the harmonic component by the harmonic limiting coefficient k I to obtain the superimposed current.

[0104] By S511-S512, the extracted harmonic component can be multiplied by the harmonic limiting coefficient k I after amplitude limiting, and then superimposed with the output current of the synchronous generator, which can avoid the harmonic component in the superimposed current exceeding the harmonic suppression capability of the energy storage inverter 10, so that the energy storage inverter 10 cannot suppress the harmonic current according to the corresponding harmonic suppression instruction, thereby ensuring the harmonic suppression capability.

[0105] As shown in Figure 6 and Figure 9 in some examples, extracting the harmonic component in the load current I load_abc may include S511'-S513'.

[0106] S511': obtaining the load current I load_abc and the phase angle θ of the power grid 2. As described above, the load current I load_abc may be obtained by sampling. The phase angle of the power grid 2 can be determined by using a phase-locked loop, and the three-phase voltage U abc of the power grid 2 can be obtained by the phase-locked loop to obtain the phase angle θ of the power grid 2.

[0107] S512': performing harmonic filtering on the load current I load_abc according to the phase angle θ of the power grid 2 to determine the fundamental value I load_基波 of the load current. The load current usually includes a fundamental component and a harmonic component, and the harmonic component is filtered out by the harmonic filtering link, so that the fundamental component is obtained. Here, the phase angle θ can be input as a reference quantity into the harmonic filtering link, and the load current I load_abc is phase-locked in the harmonic filtering link, so that the phase difference between I load_abc and the power grid 2 does not change, thereby obtaining the accurate fundamental value I load_基波 of the load current.

[0108] S513': according to the load current I load_abc and the fundamental value I load_基波 of the load current, determine the harmonic component in the load current. In the case where the load current I load_abc and the fundamental value I load_基波 of the load current have been determined, by subtracting the two values, the difference is the harmonic component of the load current I load_abc .

[0109] S511'~S513' can ensure that the determined fundamental value I load_基波 of the load current is relatively accurate, thereby ensuring the accuracy of the extracted harmonic component in the load current I load_abc , and providing an accurate reference for subsequent harmonic suppression.

[0110] As shown in Figure 6 and Figure 10 , in some examples, the harmonic component and the output current I ref of the virtual synchronous generator are superimposed to obtain a superimposed current, including S511"~S513".

[0111] S511": obtain the phase angle θ of the power grid 2 and the d-axis current I d_ref and the q-axis current I q_ref of the virtual synchronous generator.

[0112] S512": according to the phase angle θ of the power grid 2, perform a phase coordinate transformation on the d-axis current I d_ref and the q-axis current I q_ref of the virtual synchronous generator to determine the output current I ref of the virtual synchronous generator. Here, the phase angle θ can be input as a reference quantity into the phase coordinate transformation link, and in this link, I d_ref and I q_ref are phase-locked, so that the phase difference between I d_ref and the power grid 2 and the phase difference between I q_ref and the power grid 2 do not change in the phase coordinate transformation, thereby obtaining an accurate output current I ref .

[0113] S513": superimpose the harmonic component and the output current I ref of the virtual synchronous generator to obtain a superimposed current.

[0114] S511"~S513" can ensure phase synchronization in the transformation process and the accuracy of the output current I ref by phase-locked loop of the phase coordinate transformation link, thereby obtaining a relatively accurate superimposed current, providing an accurate basis for subsequent harmonic suppression.

[0115] S52: Obtain the output current of the energy storage inverter 10 and a pre-constructed current controller 441. The current controller 441 can be a computer program module executed by a processor or an IC (Integrated Circuit) to realize the control of the current. In some examples, the current controller 441 can adopt a compound control mode, for example, the current controller 441 can include a repetitive controller and a proportional controller connected in parallel. The repetitive controller adopts the repetitive control principle, and adds a "past control deviation" to the input signal of the controlled object in addition to the deviation signal, which is the control deviation at this time in the last one or several periods. The advantage of repetitive control is that the output has no static error and can suppress periodic disturbances, and the disadvantage is that the response speed is slow. Since the virtual synchronous generator needs to reflect the system inertia and does not pursue rapid response to the instruction, the repetitive control can be combined with the virtual synchronous generator, and the output current of the virtual synchronous generator is taken as the input quantity of the repetitive controller, and the output current is controlled to meet the dual-loop control requirements of the inner loop current control and the outer loop power control. The proportional controller adopts the proportional control (Proportional control) principle, which can dynamically compensate the repetitive controller to make up for the defect of slow response speed of the repetitive control and ensure the dynamic response ability of the current controller 441. Exemplarily, the current controller 441 can also adopt a repetitive controller and a proportional integral controller connected in parallel.

[0116] S53: Input the output current of the energy storage inverter 10 and the superimposed current into the current controller 441 to determine the output current of the current controller 441. Here, the output current of the energy storage inverter 10 and the superimposed current are taken as the input quantity of the current controller 441, and the output current of the current controller 441 can be determined according to the transfer function from the input to the output of the current controller 441. In some examples, according to the repetitive controller and the proportional controller connected in parallel, the transfer function from the input to the output of the current controller 441 can be determined.

[0117] S54: Take the output current of the current controller 441 as the instruction current, and adjust the output state of the energy storage inverter 10 according to the instruction current.

[0118] On the basis of adopting a virtual synchronous generator to control a power outer loop, a repetitive controller and a proportional controller are connected in parallel to control a current inner loop in S41-S44. Due to the fluctuation characteristics of the distributed power supply 20, the energy storage inverter 10 matched therewith has low utilization efficiency and has idle excess capacity. The repetitive controller in the compound control mode can utilize the excess capacity to suppress load harmonics in the power grid 2, thereby improving the power quality of the power grid 2 and improving the capacity utilization efficiency of the energy storage inverter 10; the proportional controller can dynamically compensate the repetitive controller to make up for the slow response speed of the repetitive control and ensure the dynamic response capability of the current controller 441. In this way, when a load such as an uncontrolled rectification load that can introduce harmonic currents is connected to the power grid 2, the harmonic currents can be suppressed in time to ensure the power quality of the power grid 2. At the same time, the output current of the energy storage inverter 10 can be close to the designed current peak value and reach the current rated value, so that the capacity of the energy storage inverter 10 is fully utilized.

[0119] As shown in Figure 6 and Figure 11 , in the example in which the current controller 441 includes a repetitive controller and a proportional controller connected in parallel, the transfer function from input to output of the repetitive controller and the proportional controller connected in parallel can be:

[0120]

[0121] wherein Q(z) is an internal model of the repetitive controller and can be a low-pass filter or a normal number not greater than 1; z is a complex variable in Z transform, and n is the number of samples in one period. m z is a phase lead compensator configured to eliminate the phase lag generated by the repetitive controller, m is an integer greater than 1; k r is a proportional coefficient of the repetitive control; S(z) is a filter; k p is a proportional coefficient of the proportional controller. Exemplarily, , S1(z) is a lead-lag element that keeps the low-frequency gain of the system to be 1; and S2(z) is a second-order low-pass filter.

[0122] Exemplarily, I ref may be three-phase currents obtained by dq / abc transformation of I d_ref and I q_ref . out The controlled object G(z) can be the energy storage inverter 10, and I v_abc corresponds to the three-phase current output by the energy storage inverter 10 to the power grid 2; V g is set as the voltage of the power grid 2, and the three-phase form thereof can be U abc .

[0123] AsFigure 12 As shown, in some examples, the energy storage inverter control method further includes S61 to S63.

[0124] S61: Obtain the phase angle θ and three-phase voltage U of power grid 2. abc ;

[0125] S62: Based on the phase angle θ of grid 2, the three-phase voltage U of the grid abc Perform phase coordinate transformation to determine the d-axis voltage U of power grid 2. sd and q-axis voltage U sq Here, the phase angle θ can be used as a reference input to the phase coordinate transformation stage, where U... abc Perform phase-locked loop, so that U abc The phase difference between the voltage and grid 2 remains unchanged during the phase coordinate transformation, thus obtaining an accurate d-axis voltage U. sd and q-axis voltage U sq .

[0126] S63: Based on the d-axis voltage U of power grid 2 sd and q-axis voltage U sq Adjusting the d-axis current I of the virtual synchronous generator d_ref and q-axis current I q_ref Here, U can be used sd and U sq As a feedback regulation input to the virtual synchronous generator, the d-axis and q-axis currents I of the virtual synchronous generator are controlled in the synchronous rotating coordinate system. d_ref and I q_ref Perform feedback adjustments.

[0127] To illustrate the technical effects of the embodiments of this application, a simulation example of the energy storage inverter control method is provided here. In the simulation example, the grid-connected power of the energy storage inverter 10 is 50kW, the DC bus voltage is 700V, the filter inductance is 1.5mH, the filter capacitor is 10uF, and the rated line voltage is 380V, while the moment of inertia of the virtual synchronous generator is set to J = 1.6kg·m. 2 The damping coefficient is set to D = 20. The synchronous angular velocity ω of power grid 2... g The permissible frequency range is [0.98, 1.02] pu, and the voltage value at the common coupling point is V. PCC The allowable voltage range is [0.95, 1.05] pu; that is, the upper limit of the synchronous angular velocity of power grid 2 is 1.02 times the reference frequency, the lower limit is 0.98 times the reference frequency, and the upper limit of the voltage value at the common coupling point is 0.95 times the reference voltage, the lower limit is 1.05 times the reference voltage. p The value of k is 3. ris 0.1. The low frequency cutoff frequency of S(z) filter is 1.5 Hz, the bandwidth is 1 kHz, and the highest order of the current harmonics that can be suppressed is 20. It can be calculated that the harmonic current that can be suppressed by the energy storage inverter 10 is 20 A, which is approximately the harmonic of the 9 ohm load of the uncontrolled rectifier. The design current rating of the energy storage inverter 10 is 75 A, and the design current peak value is 106 A.

[0128] In order to verify the harmonic suppression and capacity utilization efficiency of the energy storage inverter 10, the following current command is input to the simulation process: I d_ref = 0, I q_ref = 55 A; and the load 3 of the simulation process is set to a 9 ohm resistive load of the uncontrolled rectifier. By using the window function tool based on Fourier transform for simulation analysis, the waveform diagram of the load current as shown in Figure 13 , the frequency spectrum diagram of the load current as shown in Figure 14 , the waveform diagram of the grid-connected current as shown in Figure 15 , and the frequency spectrum diagram of the grid-connected current as shown in Figure 16 can be obtained. As shown in Figures 13-14 , the harmonic current on the load side is about 30% of the fundamental wave, the harmonic current value is close to 20 A, and the harmonic value below 20 times is large. As shown in Figures 15-16 , the harmonic current on the grid-connected side within 20 times is reduced to less than 1% of the fundamental wave, the harmonic amplitude on the grid-connected side is significantly reduced, and the performance of the current controller 441 is better. The waveform diagram of the output current of the energy storage inverter 10 is as shown in Figure 17 , in which the peak value of the output current is close to 110 A, which is very close to the design peak value 106 A, and the rated value is designed to be the design rated current value, indicating that the capacity of the energy storage inverter 10 is fully utilized.

[0129] In order to verify the dynamic response capability of the energy storage inverter 10, the on-off grid switching process of the energy storage inverter 10 and the grid 2 is simulated, the load 3 of the simulation process is set to a 50 kW resistive load, the energy storage inverter 10 is instructed to output 10 kW active power, and the energy storage inverter 10 is disconnected from the grid 2 at t = 2 s. The waveform diagram of the output voltage of the energy storage inverter 10 as shown in Figure 18 , the waveform diagram of the output current of the energy storage inverter 10 as shown in Figure 19 , the numerical change diagram of the output voltage of the energy storage inverter 10 as shown in Figure 20 , and the numerical change diagram of the output current of the energy storage inverter 10 as shown in Figure 21A numerical change diagram of the frequency of the energy storage inverter 10 is shown. After the energy storage inverter 10 is disconnected from the power grid 2 and enters an off-grid state, the changes of the output voltage and the output current of the energy storage inverter 10 are relatively smooth, the fluctuation ranges of the output voltage, the output current and the frequency are small, the response speed of the current controller 441 to the current instruction can ensure smooth switching in and off-grid, and the parameters are controlled within the allowed range of the frequency and the allowed range of the voltage amplitude, which meets the requirements of the virtual synchronous generator control.

[0130] As shown in Figure 22 In a second aspect, the embodiments of the present application provide an energy storage inverter control device 4, which includes a virtual discharge control circuit 41, a frequency limiting control circuit 42 and an amplitude limiting control circuit 43.

[0131] The virtual discharge control circuit 41 is configured to perform the following operations: obtaining an output current of a pre-constructed virtual synchronous generator; determining an instruction current according to the output current of the virtual synchronous generator, and updating an output state of the energy storage inverter 10 according to the instruction current.

[0132] The frequency limiting control circuit 42 is configured to perform the following operations: obtaining a synchronous angular velocity of the power grid 2; determining whether the synchronous angular velocity of the power grid 2 and the voltage value of the common coupling point are within an allowed range; in response to determining that the synchronous angular velocity of the power grid 2 is not within the allowed range, inputting a first power adjustment instruction to the virtual synchronous generator to update the output current of the virtual synchronous generator.

[0133] The amplitude limiting control circuit 43 is configured to perform the following operations: obtaining a voltage value of a common coupling point, which is a coupling point of the power grid 2 and the energy storage inverter 10; determining whether the synchronous angular velocity of the power grid 2 and the voltage value of the common coupling point are within an allowed range; in response to determining that the voltage value of the common coupling point is not within the allowed range, inputting a second power adjustment instruction to the virtual synchronous generator to update the output current of the virtual synchronous generator.

[0134] In some embodiments, the virtual generator control circuit is further configured to perform the following operations: obtaining a power instruction value and a power measurement value of the energy storage inverter 10; inputting the power instruction value and the power measurement value of the energy storage inverter 10 to the virtual synchronous generator to determine the output current of the virtual synchronous generator.

[0135] In some examples, the virtual power generation control circuit is also configured to perform the following operations: inputting the active power command value and active power measurement value of the energy storage inverter 10 into the virtual synchronous generator to determine the power angle of the virtual synchronous generator; inputting the reactive power command value and reactive power measurement value of the energy storage inverter 10 into the virtual synchronous generator to determine the excitation voltage of the virtual synchronous generator; determining the output voltage of the virtual synchronous generator based on the power angle and excitation voltage of the virtual synchronous generator; obtaining the equivalent resistance and equivalent inductance of the virtual synchronous generator; and determining the output current of the virtual synchronous generator based on the output voltage and the equivalent resistance and equivalent inductance of the virtual synchronous generator.

[0136] like Figure 6 and Figure 22 As shown, in some embodiments, the energy storage inverter control device 4 further includes a composite current control circuit 44, which includes a current controller 441. The composite current control circuit 44 is configured to perform the following operations: extract harmonic components from the load current and superimpose the harmonic components with the output current of the virtual synchronous generator to obtain a superimposed current; obtain the output current of the energy storage inverter 10; input the output current of the energy storage inverter 10 and the superimposed current into the current controller 441 to determine the output current of the current controller 441; use the output current of the current controller 441 as a command current, and update the output state of the energy storage inverter 10 according to the command current.

[0137] In some examples, the current controller 441 includes a repetitive controller and a proportional controller connected in parallel.

[0138] In some examples, the composite current control circuit 44 is also configured to perform the following operation: obtain the harmonic limiting coefficient k. I Multiply the harmonic component by the harmonic limiting coefficient k. I The superimposed current is then obtained by superimposing it with the output current of the virtual synchronous generator. Harmonic limiting coefficient k I The method for determining this has been described above and will not be repeated here.

[0139] like Figure 23As shown in the third aspect, the embodiment of the present application provides a storage inverter 10, comprising an inverter 101, a storage device 102, a processor 103 and a memory 104. The inverter 101 is a converter for converting direct current power (such as a battery, a storage battery and the like) into fixed-frequency fixed-voltage or frequency-regulated voltage alternating current (commonly 220V, 50Hz sine wave). The storage device 102 is a storage unit, which can be a capacitor, a battery or the like that can store power. The memory 104 stores a computer program, and the computer program is executed by the processor to implement the above-mentioned storage inverter control method.

[0140] The processor 103 can perform various actions and processes according to the program stored in the memory 104. Specifically, the processor 103 can be an integrated circuit chip with signal processing capability. The processor 103 described above can be a general processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a ready programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, and can implement or execute the disclosed methods, steps and logic block diagrams in the embodiments of the present application. The general processor can be a microprocessor or the processor can be any conventional processor or the like, which can be of X86 architecture or ARM architecture.

[0141] The memory 104 can be a volatile memory or a non-volatile memory, or can include both volatile and non-volatile memories. The non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM) or a flash memory. The volatile memory can be a random access memory (RAM) used as an external cache. By way of example, but not limitation, many forms of RAM can be used, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM) and direct memory bus random access memory (DRRAM). It should be noted that the memory of the method described herein is intended to include, but not limited to, these and any other suitable types of memory.

[0142] In the fourth aspect, the embodiment of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is loaded by a processor to execute the steps of the control method described in any of the above embodiments.

[0143] By way of example, the computer-readable storage media described above can include, but is not limited to, magnetic storage (e.g., one or more magnetic disks, magnetic tapes, or magnetic drums), optical storage (e.g., one or more Compact Discs (CDs), Digital Versatile Discs (DVDs), or Blu-Ray Discs), smart cards, and flash storage (e.g., EPROM, a card, a stick, or a key drive). The various computer-readable storage media described above can represent one or more devices and / or other machine-readable storage media for storing information. The term "machine-readable storage medium" can include, without being limited to, wireless channels and various other media capable of storing, containing, and / or carrying instruction(s) and / or data.

[0144] The above provides a detailed description of the energy storage inverter control method and device provided by the embodiments of the present application. The principles and implementation manners of the present application are described by using specific examples. The above description of the embodiments is only used to help understand the method and its core idea of the present application. Meanwhile, for those skilled in the art, the specific implementation manners and application ranges will be changed according to the idea of the present application. In summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A method of controlling an energy storage inverter, the method comprising: The method comprises: obtaining an output current of a pre-constructed virtual synchronous generator; obtaining a synchronous angular velocity of a power grid and a voltage value of a point of common coupling, the point of common coupling being a coupling point of the power grid and the energy storage inverter; determining whether the synchronous angular velocity of the power grid and the voltage value of the point of common coupling are both within an allowable range; in response to determining that the synchronous angular velocity of the power grid and / or the voltage value of the point of common coupling are not within the allowable range, inputting a power adjustment instruction to the virtual synchronous generator to update the output current of the virtual synchronous generator; determining an instruction current according to the output current of the virtual synchronous generator, and updating an output state of the energy storage inverter according to the instruction current. The method further comprises: obtaining a power instruction value and a power measurement value of the energy storage inverter; inputting the power instruction value and the power measurement value of the energy storage inverter into a mathematical model of the virtual synchronous generator to determine the output current of the virtual synchronous generator. The method further comprises: determining whether the synchronous angular velocity of the power grid is within the allowable range; in response to determining that the synchronous angular velocity of the power grid is not within the allowable range, performing the following operations: inputting a first power adjustment instruction to the virtual synchronous generator, the first power adjustment instruction being an active power adjustment instruction; updating a power angle of the virtual synchronous generator according to the first power adjustment instruction, an active power instruction value and an active power measurement value of the energy storage inverter based on the virtual synchronous generator; updating the output current of the virtual synchronous generator according to the power angle and an excitation voltage of the virtual synchronous generator; determining an instruction current according to the output current of the virtual synchronous generator, and updating an output state of the energy storage inverter according to the instruction current, the method comprising: extracting a harmonic component in a load current, and superimposing the harmonic component and the output current of the virtual synchronous generator to obtain a superimposed current; obtaining an output current of the energy storage inverter and a pre-constructed current controller; inputting the output current of the energy storage inverter and the superimposed current into the current controller to determine an output current of the current controller; taking the output current of the current controller as an instruction current, and adjusting the output state of the energy storage inverter according to the instruction current.

2. The energy storage inverter control method of claim 1, wherein, The power instruction value of the energy storage inverter comprises an active power instruction value and a reactive power instruction value of the energy storage inverter, and the power measurement value of the energy storage inverter comprises an active power measurement value and a reactive power measurement value of the energy storage inverter; the method further comprises: inputting the active power instruction value and the active power measurement value of the energy storage inverter into the virtual synchronous generator to determine a power angle of the virtual synchronous generator. inputting a reactive power instruction value and a reactive power measurement value of the energy storage inverter into the virtual synchronous generator to determine an excitation voltage of the virtual synchronous generator; determining an output voltage of the virtual synchronous generator according to a power angle and the excitation voltage of the virtual synchronous generator; obtaining an equivalent resistance and an equivalent inductance of the virtual synchronous generator, and determining an output current of the virtual synchronous generator according to the output voltage of the virtual synchronous generator and the equivalent resistance and the equivalent inductance of the virtual synchronous generator.

3. The energy storage inverter control method of claim 1, wherein, The power adjustment instruction input into the virtual synchronous generator to update the output current of the virtual synchronous generator in response to determining that the synchronous angular velocity of the power grid and / or the voltage value of the point of common coupling is not within the allowable range, comprises: determining whether the voltage value of the point of common coupling is within the allowable range; in response to determining that the voltage value of the point of common coupling is not within the allowable range, performing the following operations: inputting a second power adjustment instruction into the virtual synchronous generator, the second power adjustment instruction being a reactive power adjustment instruction; updating the excitation voltage of the virtual synchronous generator according to the second power adjustment instruction, the reactive power instruction value and the reactive power measurement value of the energy storage inverter based on the virtual synchronous generator; updating the output current of the virtual synchronous generator according to the power angle and the excitation voltage of the virtual synchronous generator.

4. The energy storage inverter control method of claim 1, wherein, The current controller comprises a repetitive controller and a proportional controller connected in parallel.

5. The energy storage inverter control method of claim 1, wherein, The superimposing the harmonic component and the output current of the virtual synchronous generator to obtain a superimposed current, comprises: Harmonic limiting coefficient k is acquired I ; multiplying the harmonic component by the harmonic clipping coefficient k I the output current of the virtual synchronous generator to obtain the superimposed current.

6. The energy storage inverter control method of claim 5, wherein, The harmonic clipping coefficient k I is determined by the following system of equations: Wherein, 0 < k I <1; I a is the current characteristic value of the energy storage inverter, I lim is the current limit value of the energy storage inverter, I load_基波 is the fundamental value of the load current, I d_ref is the d-axis current of the virtual synchronous generator, I q_ref is the q-axis current of the virtual synchronous generator; U dc is the DC voltage of the energy storage inverter, L 逆 is the filter inductance of the energy storage inverter; k is an approximate value coefficient; ω g is the angular velocity of the power grid.

7. The energy storage inverter control method of claim 1, wherein, extracting a harmonic component in a load current, comprising: obtaining a load current and a phase angle of the power grid; harmonic filtering the load current according to the phase angle of the power grid to determine a fundamental value of the load current; determining the harmonic component of the load current according to the load current and the fundamental value of the load current.

8. The energy storage inverter control method of claim 1, wherein, The superimposing the harmonic component and the output current of the virtual synchronous generator to obtain a superimposed current, comprises: obtaining a phase angle of the power grid and d-axis current and q-axis current of the virtual synchronous generator; performing phase coordinate transformation on the d-axis current and the q-axis current of the virtual synchronous generator according to the phase angle of the power grid to determine the output current of the virtual synchronous generator; The superimposing the harmonic component and the output current of the virtual synchronous generator to obtain a superimposed current.

9. The energy storage inverter control method of claim 1, wherein, Further comprising: obtaining a phase angle and a three-phase voltage of the power grid; performing phase coordinate transformation on the three-phase voltage of the power grid according to the phase angle of the power grid to determine d-axis voltage and q-axis voltage of the power grid; adjusting the d-axis current and the q-axis current of the virtual synchronous generator according to the d-axis voltage and the q-axis voltage of the power grid.

10. An energy storage inverter control device, characterized by, Comprise: a virtual power generation control circuit configured to perform the following operations: obtaining a pre-constructed output current of a virtual synchronous generator; determining an instruction current according to the output current of the virtual synchronous generator, and updating an output state of the energy storage inverter according to the instruction current; a frequency limiting control circuit configured to perform the following operations: obtaining a synchronous angular velocity of a power grid; determining whether the synchronous angular velocity of the power grid is within an allowable range; in response to the synchronous angular velocity of the power grid not being within the allowable range, inputting a first power regulation instruction to the virtual synchronous generator to update the output current of the virtual synchronous generator; and an amplitude limiting control circuit configured to perform the following operations: obtaining a voltage value of a point of common coupling, the point of common coupling being a coupling point of the power grid and the energy storage inverter; determining whether the voltage value of the point of common coupling is within an allowable range; in response to the voltage value of the point of common coupling not being within the allowable range, inputting a second power regulation instruction to the virtual synchronous generator to update the output current of the virtual synchronous generator.

11. The energy storage inverter control device of claim 10, wherein, a composite current control circuit including a current controller; the composite current control circuit is configured to perform the following operations: extracting a harmonic component in the load current, and superimposing the harmonic component and the output current of the virtual synchronous generator to obtain a superimposed current; obtaining the output current of the energy storage inverter; inputting the output current of the energy storage inverter and the superimposed current into the current controller to determine the output current of the current controller; taking the output current of the current controller as an instruction current, and updating the output state of the energy storage inverter according to the instruction current.

12. An energy storage inverter, characterized by, a memory and a processor, the memory storing a computer program, the computer program being executed by the processor to implement the energy storage inverter control method of any one of claims 1-9.

13. A computer-readable storage medium, characterized in that, a computer program stored thereon, the computer program being loaded by a processor to execute the steps in the control method of any one of claims 1-9.

Images