Current source simulation network construction control method, electronic equipment and network-following inverter

Abstract

The invention provides a current source simulation network construction control method, electronic equipment and a network-following type inverter. The method comprises the following steps: acquiring the current frequency of a grid-connected point; according to the current frequency of the grid-connected point, determining the current frequency offset of the grid-connected point and the current frequency change rate of the grid-connected point; according to the current frequency offset of the grid-connected point and the current frequency change rate of the grid-connected point, the active power adjustment amount of current source simulation grid construction is determined; the active power adjustment amount of the current source simulation network construction comprises the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter and the active power adjustment amount of the inertia response of the grid-connected inverter; and based on the active power adjustment amount of the current source simulation network construction, performing network tracking type control on the grid-connected inverter to realize the current source simulation network construction. According to the invention, the simulation of the output characteristics of a traditional current source on the constructed network can be realized, so that the current source type network following control has the performance characteristics of a voltage source type constructed network to a certain extent, and the stability of a power grid during the grid connection of the current source can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of networking, and in particular to a control method for current source analog networking, electronic equipment and a grid-following inverter. Background Art

[0002] The gradual increase in the coverage of distributed new energy in the power system has avoided the problem of high energy consumption in traditional power generation and greatly improved resource utilization.

[0003] At present, the grid-connected inverter adopts the mainstream grid-following control mode. Under this control mode, the grid-connected inverter can be equivalent to a current source. However, this control mode lacks rotating reserve capacity and rotational inertia, which reduces the stability of the power grid. The use of virtual synchronous machine control can simulate the output characteristics of synchronous generators, which can increase the inertia of the power grid to a certain extent, thereby enhancing the stability of the power grid, but it is prone to oscillation in a strong network environment.

[0004] Therefore, how to improve the stability of the power grid when the current source is connected to the grid is a problem that needs to be solved urgently. Summary of the invention

[0005] The embodiments of the present invention provide a control method for current source analog networking, electronic equipment and a grid-following inverter to solve the problem of poor grid stability when a traditional current source is connected to the grid.

[0006] In a first aspect, an embodiment of the present invention provides a control method for current source analog networking, including:

[0007] Get the current frequency of the grid-connected point; the grid-connected point is the connection point where the grid-connected inverter is connected to the power grid;

[0008] Determine the current frequency offset of the grid connection point and the current frequency change rate of the grid connection point according to the current frequency of the grid connection point;

[0009] According to the current frequency offset of the grid connection point and the current frequency change rate of the grid connection point, the active power adjustment amount of the current source simulation network is determined; the active power adjustment amount of the current source simulation network includes the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter and the active power adjustment amount of the inertia response of the grid-connected inverter;

[0010] Based on the active power adjustment amount of the current source simulation network, the grid-connected inverter is controlled to realize the current source simulation network.

[0011] In a possible implementation, determining the active power adjustment amount of the current source simulated network according to the current frequency offset of the grid connection point and the current frequency change rate of the grid connection point includes:

[0012] According to the current frequency offset of the grid-connected point, the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter is determined;

[0013] According to the current frequency change rate of the grid-connected point, the active power adjustment amount of the inertia response of the grid-connected inverter is determined;

[0014] Based on the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter and the active power adjustment amount of the inertia response of the grid-connected inverter, the active power adjustment amount of the current source simulation network is determined.

[0015] In a possible implementation, determining the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter according to the current frequency offset of the grid-connected point includes:

[0016] according to Determine the active power adjustment amount P of the primary frequency modulation response of the grid-connected inverter f ; Among them, K f is the active frequency modulation coefficient, P n is the rated power of the grid-connected inverter, f N is the reference frequency of the power grid, and Δf is the current frequency offset of the grid connection point.

[0017] In a possible implementation, determining the active power adjustment amount of the inertia response of the grid-connected inverter according to the current frequency change rate of the grid-connected point includes:

[0018] according to Determine the active power adjustment P of the grid-connected inverter inertia response in ; Among them, P n is the rated power of the grid-connected inverter, f N is the reference frequency of the power grid, T J is the inertia time constant; is the current frequency change rate of the grid connection point.

[0019] In a possible implementation, before performing grid-following control on the grid-connected inverter based on the active power adjustment amount of the current source simulation network to realize the current source simulation network, the control method of the current source simulation network further includes:

[0020] Get the effective value of the current voltage at the grid connection point;

[0021] Calculate the voltage difference between the effective value of the current voltage at the grid connection point and the rated voltage at the grid connection point;

[0022] According to the voltage difference, the reactive power adjustment amount of the primary voltage regulation response of the grid-connected inverter is determined, and the reactive power adjustment amount of the primary voltage regulation response of the grid-connected inverter is used as the reactive power adjustment amount of the current source simulation network;

[0023] Accordingly, based on the active power adjustment amount of the current source simulation network, the grid-connected inverter is controlled to follow the grid to realize the current source simulation network, including:

[0024] Based on the active power adjustment amount of the current source simulation network and the reactive power adjustment amount of the current source simulation network, the grid-connected inverter is controlled to realize the current source simulation network.

[0025] In a possible implementation, determining the reactive power adjustment amount of the primary voltage regulation response of the grid-connected inverter according to the voltage difference includes:

[0026] according to Determine the reactive power adjustment Q of the primary voltage regulation response of the grid-connected inverter v ; Among them, K v is the reactive voltage regulation coefficient, S N is the rated capacity of the virtual synchronous machine, ΔU is the voltage difference, U N is the rated voltage of the grid connection point.

[0027] In a possible implementation, based on the active power adjustment amount of the current source simulation network, the grid-connected inverter is controlled in a grid-following manner, including:

[0028] Obtaining an active power given value, and taking the sum of the active power given value and the active power adjustment amount of the current source simulation network as a new active power given value;

[0029] According to the new active power given value, the grid-connected inverter is controlled in a grid-following manner.

[0030] In a possible implementation, determining the current frequency change rate of the grid connection point according to the current frequency of the grid connection point includes:

[0031] Get the current location identifier;

[0032] Get the frequency corresponding to the current positioning identifier stored in a pre-created array;

[0033] Determine the current frequency change rate of the grid connection point according to the current frequency of the grid connection point, the frequency corresponding to the current positioning identifier and the duration of a preset number of cycles; the preset number is the size of the array;

[0034] The frequency corresponding to the current positioning identifier stored in the array is updated to the current frequency of the grid connection point, and the current positioning identifier is updated.

[0035] In a second aspect, an embodiment of the present invention provides a control device for current source analog networking, including:

[0036] An acquisition module is used to acquire the current frequency of the grid-connected point; the grid-connected point is the connection point where the grid-connected inverter is connected to the power grid;

[0037] A frequency calculation module, used to determine the current frequency offset of the grid connection point and the current frequency change rate of the grid connection point according to the current frequency of the grid connection point;

[0038] The active power adjustment module is used to determine the active power adjustment amount of the current source simulation network according to the current frequency offset of the grid connection point and the current frequency change rate of the grid connection point; the active power adjustment amount of the current source simulation network includes the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter and the active power adjustment amount of the inertia response of the grid-connected inverter;

[0039] The control module is used to perform grid-following control on the grid-connected inverter based on the active power adjustment amount of the current source simulated network to realize the current source simulated network.

[0040] In a third aspect, an embodiment of the present invention provides an electronic device, comprising a memory and a processor, the memory being used to store a computer program, the processor being used to call and run the computer program stored in the memory, and executing the control method for current source simulation networking as described in the first aspect or any possible implementation of the first aspect.

[0041] In a fourth aspect, an embodiment of the present invention provides a grid-connected inverter, comprising the electronic device as described in the third aspect above.

[0042] In a fifth aspect, an embodiment of the present invention provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the steps of the control method of current source simulation networking as described in the first aspect or any possible implementation method of the first aspect.

[0043] The embodiment of the present invention provides a control method for current source simulation networking, an electronic device and a grid-following inverter. The method can simulate the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter and the active power adjustment amount of the inertia response of the grid-connected inverter through the current frequency offset of the grid-connected point and the current frequency change rate of the grid-connected point, thereby obtaining the active power adjustment amount of the current source simulation networking, and based on the active power adjustment amount of the current source simulation networking, the grid-following control of the grid-connected inverter is performed, so that the output characteristics of the traditional current source for the active power of the networking can be simulated, so that the current source type grid-following control has the performance characteristics of the voltage source type networking to a certain extent, thereby improving the stability of the power grid when the current source is connected to the grid. In addition, compared with the traditional control method, the method provided in the embodiment of the present application is relatively simple in control loop modification, and only the corresponding control of the active power adjustment amount of the current source simulation networking needs to be added to the main control loop. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 labor.

[0045] Figure 1 This is the control block diagram of a typical VSG;

[0046] Figure 2 It is a flow chart of a control method of current source simulation network construction provided by an embodiment of the present invention;

[0047] Figure 3 It is a schematic diagram of a control loop corresponding to a control method for current source analog networking provided by an embodiment of the present invention;

[0048] Figure 4 is a flowchart of frequency calculation provided by an embodiment of the present invention;

[0049] Figure 5 is a schematic diagram of a control loop corresponding to a control method for current source analog networking provided by another embodiment of the present invention;

[0050] Figure 6 It is a schematic diagram of experimental verification results of a primary frequency modulation provided by an embodiment of the present invention;

[0051] Figure 7 is a schematic diagram of experimental verification results of inertia response provided by an embodiment of the present invention;

[0052] Figure 8 It is a structural schematic diagram of a control device for current source simulation networking provided by an embodiment of the present invention;

[0053] Fig. 9 It is a schematic diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0054] The present application is described more clearly below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the effects of the present application, but are not intended to limit the present application in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present application. These all fall within the scope of protection of the present application.

[0055] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or combinations thereof.

[0056] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0057] In the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0058] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0059] In addition, the “plurality” mentioned in the embodiments of the present application should be interpreted as two or more.

[0060] As mentioned above, in the grid-connected inverter of the current distributed power generation system, the most mainstream control strategy is grid-following control, which realizes the directional scheme of the grid voltage through a phase-locked loop (PLL). In this control mode, the grid-connected inverter can be equivalent to a current source. When the grid is a strong grid with small impedance, the current source mode can not only maximize the utilization rate of new energy, but also ensure a high grid-connected power quality. At the same time, it also has the advantages of strong controllability, easy to realize maximum power point tracking (MPPT) control, and strong anti-interference of multi-machine parallel connection. However, due to its lack of rotating reserve capacity and rotational inertia, it will cause the system inertia to decrease and reduce the stability of the system. In response to this problem, a virtual synchronous generator (VSG) control strategy is proposed in the relevant technology. Figure 1 The control block diagram of a typical VSG is shown in Figure 2. The control equation of the loop of a typical VSG is:

[0061]

[0062] In the above formula, P ref and P e They are respectively the active power command and actual active power output by VSG; Q ref and Q e They are VSG output reactive power command and output actual reactive power; ω o ,ω ref , U n and U are the rated value and actual value of VSG output voltage frequency, grid output voltage amplitude and grid rated voltage amplitude, respectively. q , k u They are VSG frequency damping coefficient, VSG virtual inertia coefficient, VSG voltage droop coefficient and VSG reactive inertia coefficient; E is the VSG reactive loop output excitation voltage.

[0063] The VSG control strategy can effectively improve the damping and inertia of the power grid and improve the stability of the power grid by simulating the characteristics of the synchronous machine. However, it is prone to oscillation in a strong grid environment. At the same time, VSG technology is rarely used at present, and its actual application needs further research and verification.

[0064] Therefore, how to improve the stability of the power grid when the current source is connected to the grid is a problem that needs to be solved urgently.

[0065] In order to solve the above problems, an embodiment of the present application provides a control method for current source simulation networking. This method can simulate the output characteristics of the traditional current source for the active power of networking by simulating the active power of the primary frequency modulation response of the grid-connected inverter and the active power of the inertia response of the grid-connected inverter, so that the current source type grid-following control has the performance characteristics of the voltage source type networking to a certain extent, thereby improving the stability of the power grid when the current source is connected to the grid.

[0066] Reference below Figures 2 to 4 The control method of current source analog networking provided according to the exemplary embodiment of the present application is described below. The embodiments of the present application can be applied to any applicable scenario.

[0067] It should be noted that the embodiments of the present application can be applied to electronic devices, which may be servers, computers or controllers, etc., that is, the control method of current source simulation networking provided by the exemplary embodiments of the present application can be executed on devices such as servers, computers or controllers.

[0068] It should be noted that the control method for current source analog networking provided in accordance with the exemplary embodiment of the present application may be executed on the same device or on different devices.

[0069] See also Figure 2 , which shows a flow chart of the implementation of the control method of the current source simulation network provided by an embodiment of the present invention. The control method of the current source simulation network may include:

[0070] In S201, the current frequency of the grid connection point is obtained; the grid connection point is the connection point where the grid-connected inverter is connected to the power grid.

[0071] See also Figure 3 , the grid connection point can be Figure 3 The PCC in the middle. The left side of the PCC is the grid-connected inverter, and the right side of the PCC is the grid.

[0072] In this embodiment, the current frequency of the grid connection point can be obtained through a phase-locked loop PLL.

[0073] In S202, according to the current frequency of the grid connection point, the current frequency offset of the grid connection point and the current frequency change rate of the grid connection point are determined.

[0074] The current frequency offset of the grid connection point may be the difference between the current frequency of the grid connection point and the reference frequency of the power grid.

[0075] The current frequency change rate of the grid connection point may be a ratio of a difference between the current frequency of the grid connection point and the historical frequency of the grid connection point to a time interval between the current frequency of the grid connection point and the historical frequency of the grid connection point.

[0076] Exemplarily, the frequency of the grid connection point obtained in this cycle is taken as the current frequency of the grid connection point, and the frequency of the grid connection point obtained in the previous cycle is taken as the historical frequency of the grid connection point. The current frequency change rate of the grid connection point can be the ratio of the difference between the frequency of the grid connection point obtained in this cycle and the frequency of the grid connection point obtained in the previous cycle to the duration of a single cycle.

[0077] In some possible implementations, in order to improve the accuracy of the current frequency change rate of the grid connection point, the frequency change rate of multiple consecutive cycles may be calculated and then averaged to obtain the current frequency change rate of the grid connection point.

[0078] In S203, the active power adjustment amount of the current source simulation network is determined according to the current frequency offset of the grid-connected point and the current frequency change rate of the grid-connected point; the active power adjustment amount of the current source simulation network includes the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter and the active power adjustment amount of the inertia response of the grid-connected inverter.

[0079] Frequency regulation control is the response of active power to the frequency of the grid-connected point, which is mainly reflected in the response of the active power of the grid-connected inverter to the steady-state deviation of frequency (reflected as the current frequency offset) and the dynamic change of frequency (reflected as the current frequency change rate), that is, primary frequency modulation and inertia response.

[0080] In order to simulate the primary frequency modulation characteristics and inertia response characteristics of the network, the embodiment of the present application calculates the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter and the active power adjustment amount of the inertia response of the grid-connected inverter respectively through the current frequency offset of the grid-connected point and the current frequency change rate of the grid-connected point, and then determines the active power adjustment amount of the current source simulated network according to the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter and the active power adjustment amount of the inertia response of the grid-connected inverter. Among them, the active power adjustment amount of the current source simulated network can be the sum of the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter and the active power adjustment amount of the inertia response of the grid-connected inverter.

[0081] In S204, based on the active power adjustment amount of the current source simulated network, the grid-connected inverter is controlled in a grid-following manner to realize the current source simulated network.

[0082] In this embodiment, on the basis of the current source grid-connected control of the grid-connected inverter, the active power adjustment amount of the above-mentioned current source simulated networking is added, and the grid-connected inverter is comprehensively controlled to realize the current source simulated networking, so that the current source type grid-connected control strategy, which is more widely used and more mature in technology, has the voltage source type networking function to a certain extent.

[0083] The embodiment of the present application analyzes the external characteristics of the output power of the voltage source type grid-forming control strategy, and adds corresponding functions to the current source control block diagram so that the grid-following control has grid-forming performance characteristics to a certain extent, thereby improving the stability of the power grid.

[0084] Specifically, the embodiment of the present application can simulate the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter and the active power adjustment amount of the inertia response of the grid-connected inverter through the current frequency offset of the grid-connected point and the current frequency change rate of the grid-connected point, and then obtain the active power adjustment amount of the current source simulated network, and based on the active power adjustment amount of the current source simulated network, the grid-connected inverter is controlled by following the grid, so as to realize the simulation of the output characteristics of the traditional current source for the active power of the network, so that the current source type following grid control has the performance characteristics of the voltage source type network to a certain extent, and thus can improve the stability of the power grid when the current source is connected to the grid. In addition, compared with the traditional control method, the method provided by the embodiment of the present application is relatively simple in control loop modification, and only the corresponding control of the active power adjustment amount of the current source simulated network needs to be added to the main control loop.

[0085] The above embodiment describes the overall process of current source simulation network construction. Figure 3 , further introduces in detail how to determine the active power adjustment amount of the current source simulation network and how to perform grid-following control on the grid-connected inverter according to the active power adjustment amount of the current source simulation network. First, it introduces how to determine the active power adjustment amount of the current source simulation network.

[0086] In some embodiments, the above S203 may include:

[0087] According to the current frequency offset of the grid-connected point, the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter is determined;

[0088] According to the current frequency change rate of the grid-connected point, the active power adjustment amount of the inertia response of the grid-connected inverter is determined;

[0089] Based on the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter and the active power adjustment amount of the inertia response of the grid-connected inverter, the active power adjustment amount of the current source simulation network is determined.

[0090] The response of the active power of the grid-connected inverter to the frequency steady-state deviation is the primary frequency modulation response of the grid-connected inverter, and the frequency steady-state deviation is reflected as the current frequency offset. Therefore, the embodiment of the present application can calculate the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter based on the current frequency offset of the grid-connected point.

[0091] Among them, see Figure 3 , according to the current frequency offset of the grid-connected point, the calculation formula for determining the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter may include: Among them, P f is the active power of the primary frequency modulation response of the grid-connected inverter, K f is the active frequency modulation coefficient, P n is the rated power of the grid-connected inverter, f N is the reference frequency of the power grid, and Δf is the current frequency offset of the grid connection point.

[0092] It should be noted that Figure 3 k f represents a proportional link, which represents P f The constant part of

[0093] The response of the active power of the grid-connected inverter to the dynamic change of frequency is the inertia response of the grid-connected inverter, and the dynamic change of frequency is reflected in the current frequency change rate. Therefore, the embodiment of the present application can calculate the active power of the inertia response of the grid-connected inverter based on the current frequency change rate of the grid-connected point.

[0094] Among them, see Figure 3 , according to the current frequency change rate of the grid-connected point, the calculation formula for determining the active power of the grid-connected inverter inertia response can include: Among them, P in is the active power of the grid-connected inverter inertia response, P n is the rated power of the grid-connected inverter, fN is the reference frequency of the power grid, T J is the inertia time constant; is the current frequency change rate of the grid connection point.

[0095] It should be noted that Figure 3 k in represents a proportional link, which represents P in The constant part of

[0096] In addition, the above-mentioned determining the current frequency change rate of the grid connection point according to the current frequency of the grid connection point may include:

[0097] Get the current location identifier;

[0098] Get the frequency corresponding to the current positioning identifier stored in a pre-created array;

[0099] Determine the current frequency change rate of the grid connection point according to the current frequency of the grid connection point, the frequency corresponding to the current positioning identifier and the duration of a preset number of cycles; the preset number is the size of the array;

[0100] The frequency corresponding to the current positioning identifier stored in the array is updated to the current frequency of the grid connection point, and the current positioning identifier is updated.

[0101] The current frequency change rate of the grid connection point = (the current frequency of the grid connection point - the frequency corresponding to the current positioning identifier) ​​ / the duration of a preset number of cycles.

[0102] This embodiment adopts a frequency extraction method to determine the current frequency change rate and current frequency offset of the grid connection point, that is, Figure 3 The frequency in is calculated and used to construct the current source simulation network.

[0103] The detailed process of frequency calculation can be found in Figure 4 , first create an array or matrix F with a space of N, which is used to store the frequency information output by the phase-locked loop PLL. Among them, N is the above-mentioned preset number, and the size of N needs to consider the delay speed and error influence of the frequency change rate at the same time. When N is small, the real-time performance of the frequency change rate is better, but the error has a greater impact on the calculation; when N is large, the real-time performance of the frequency change rate is poor, but the error has a smaller impact on the calculation.

[0104] Initialize the elements in F to the reference frequency f of the power grid N . Set loop variable n, which is also the current positioning identifier. Initialize n = 0. Obtain the current frequency f of the grid-connected point output by the phase-locked loop; calculate the current frequency offset Δf = ff of the grid-connected point N ; Calculate the current frequency change rate of the grid connection point Among them, TPLL is the duration of a single cycle, which is the cycle of the phase-locked loop output frequency information; update F(n) to the current frequency f of the grid-connected point; update the current positioning identifier n. Wherein, updating the current positioning identifier n may include: automatically adding 1 to the current positioning identifier n to obtain a new n; judging whether the new n is greater than N, if so, jumping to the step of initializing n=0 and executing it in a loop, that is, updating n to 0; if not, jumping to the step of obtaining the current frequency f of the grid-connected point output by the phase-locked loop (at this time, obtaining the current frequency of the new periodic phase-locked loop output) and executing it in a loop, that is, the updated n is the above-mentioned new n.

[0105] This embodiment adopts the above method to calculate the current frequency change rate, which can take into account both accuracy and response speed.

[0106] Finally, the sum of the active power adjustment of the primary frequency modulation response of the grid-connected inverter and the active power adjustment of the inertia response of the grid-connected inverter is the active power adjustment of the current source simulation network.

[0107] The following will introduce how to perform grid-following control on the grid-connected inverter based on the active power adjustment of the current source simulation network.

[0108] In some embodiments, in the above S204, the grid-following control of the grid-connected inverter is performed based on the active power adjustment amount of the current source simulation network, including:

[0109] Obtaining an active power given value, and taking the sum of the active power given value and the active power adjustment amount of the current source simulation network as a new active power given value;

[0110] According to the new active power given value, the grid-connected inverter is controlled in a grid-following manner.

[0111] See also Figure 3 , the dotted box part is the control loop of the current source grid connection in the related art, that is, the control loop of the grid-connected inverter as the current source grid connection. The embodiment of the present application is based on the control loop, and the active power given value P in the control loop is set. ref For improvements, see Figure 3 The part outside the dotted line box is the active power given value P ref The active power adjustment amount of the current source simulated grid is added as the new active power set value, and based on the new active power set value, the grid-connected inverter is continuously controlled according to the control loop of the current source grid-connected, so that the current source type grid-connected control has the performance characteristics of the voltage source type grid-connected to a certain extent.

[0112] in, Figure 3 In the figure, Vdc is the DC voltage; L f is the filter inductor; i Labc is the filter inductor current; ioabc is the current at the grid connection point; u oabc is the current voltage at the grid connection point; U oa , U ob , U oc They are the A-phase voltage, B-phase voltage and C-phase voltage of the grid connection point respectively; u oabc is the current voltage at the grid connection point; u oabc is the current voltage of the grid-connected point; f is the current frequency of the grid-connected point; θ is the current phase angle of the grid-connected point; C f is the filter capacitor; i Cabc is the filter capacitor current; Z g is the grid impedance; P e is the actual value of active power; Q e is the actual value of reactive power; i dref is the given value of the D-axis current at the grid-connected point; i qref is the Q-axis current given value of the grid-connected point; i d is the actual value of the D-axis current at the grid-connected point; i q is the actual value of the Q-axis current at the grid-connected point; I d,max is the maximum limit value of the D-axis current; I q,max is the maximum limit value of Q axis current; i Cd is the actual value of the D-axis current of the filter capacitor; i Cq is the actual value of the Q-axis current of the filter capacitor; U rd is the voltage control value of D axis; U rq is the Q-axis voltage control variable; PI represents PI control; G represents transfer function; SPWM represents sinusoidal pulse width modulation.

[0113] See also Figure 3 The method provided in this application only modifies the active power given value part, and does not make any changes to the main loop of the current source control loop, so it is simple to apply and promote.

[0114] The above-mentioned embodiments introduce how to perform active power simulation. In order to simulate networking more accurately, in addition to active power networking simulation, reactive power networking simulation is also included. The reactive power networking simulation is described in detail below.

[0115] In some embodiments, before the above S204, the above current source simulation network control method may further include:

[0116] Get the effective value of the current voltage at the grid connection point;

[0117] Calculate the voltage difference between the effective value of the current voltage at the grid connection point and the rated voltage at the grid connection point;

[0118] According to the voltage difference, the reactive power adjustment amount of the primary voltage regulation response of the grid-connected inverter is determined, and the reactive power adjustment amount of the primary voltage regulation response of the grid-connected inverter is used as the reactive power adjustment amount of the current source simulation network.

[0119] Accordingly, the above S204 may include:

[0120] Based on the active power adjustment amount of the current source simulation network and the reactive power adjustment amount of the current source simulation network, the grid-connected inverter is controlled to realize the current source simulation network.

[0121] Voltage regulation control is the response of reactive power to the steady-state deviation of the grid-connected point voltage, that is, primary voltage regulation. The reactive power response of the grid-connected inverter to the steady-state deviation of the grid-connected point voltage is the primary voltage regulation response of the grid-connected inverter, and the voltage steady-state deviation is reflected in the above-mentioned voltage difference, that is, the voltage difference between the effective value of the current voltage of the grid-connected point and the rated voltage of the grid-connected point. Therefore, the embodiment of the present application can calculate the reactive power adjustment amount of the primary voltage regulation response of the grid-connected inverter based on the voltage difference between the effective value of the current voltage of the grid-connected point and the rated voltage of the grid-connected point, that is, the reactive power adjustment amount of the current source simulated network.

[0122] Among them, see Figure 5 , according to the voltage difference, the calculation formula for determining the reactive power adjustment amount of the primary voltage regulation response of the grid-connected inverter may include: Among them, Q v is the reactive power adjustment of the primary voltage regulation response of the grid-connected inverter, K v is the reactive voltage regulation coefficient, S N is the rated capacity of the virtual synchronous machine (i.e., apparent power), ΔU is the voltage difference mentioned above, i.e., the voltage difference between the effective value of the current voltage at the grid connection point and the rated voltage at the grid connection point, U N It is the rated voltage of the grid-connected point, which can be understood as the rated voltage of the voltage level where the grid-connected point is located.

[0123] It should be noted that Figure 5 k q represents a proportional link, which represents Q v The constant part of

[0124] The above-mentioned embodiment introduces in detail how to determine the reactive power adjustment amount of the current source simulation network. Next, it will be described how to control the grid-connected inverter based on the active power adjustment amount and reactive power adjustment amount of the current source simulation network.

[0125] In some embodiments, in the above S204, the above-mentioned grid-following control of the grid-connected inverter based on the active power adjustment amount of the current source simulated network and the reactive power adjustment amount of the current source simulated network may include:

[0126] Obtaining an active power given value, and taking the sum of the active power given value and the active power adjustment amount of the current source simulation network as a new active power given value;

[0127] Obtain a reactive power given value, and use the sum of the reactive power given value and the reactive power adjustment amount of the current source simulation network as a new reactive power given value;

[0128] According to the new active power set value and the new reactive power set value, the grid-following control is performed on the grid-connected inverter.

[0129] See also Figure 5 The dotted line frame is the control loop of the current source grid connection in the related art, that is, the control loop of the grid-connected inverter as the current source grid connection, and Figure 3 The embodiment of the present application is based on the control loop, and sets the active power given value P in the control loop. ref And reactive power set value Q ref For improvements, see Figure 5 The part outside the dotted line box is the active power given value P ref Add the active power adjustment of the current source simulation network as the new active power set value, and change the reactive power set value Q ref The reactive power adjustment of the current source simulated grid is added as the new reactive power set value, and based on the new active power set value and the new reactive power set value, the grid-connected inverter is controlled according to the control loop of the current source grid-connected control, so that the current source grid-connected control has the characteristics of the voltage source grid-connected performance to a certain extent.

[0130] See also Figure 5 The method provided in this application only modifies the active power set value and the reactive power set value, and does not make any changes to the main loop of the current source control loop, so it is simple to apply and promote.

[0131] The method provided in this application was verified by corresponding experiments. In the experiment, N was set to 26, and the output end used the off-grid short-circuit method to verify the actual performance of the algorithm. The result of the primary frequency modulation is as follows Figure 6 As shown, it can be seen that when the grid-connected point frequency jumps, the active power of the grid-connected inverter can be adjusted accordingly. Tests under various working conditions were carried out, and the test results are shown in Table 1.

[0132] After the frequency was adjusted once, the inertia test was carried out and the initial power was set to 0.35P nThe frequency change rate is 0.5Hz / s, and the frequency changes from 50Hz to 48.1Hz, 50Hz, 51.4Hz, and 50Hz in sequence. The grid-connected point frequency and the output power waveform of the grid-connected inverter are measured as follows: Figure 7 As shown, it can be seen that when the frequency of the grid-connected point changes, the machine can adjust the active output according to the change rate. The measured indicators are shown in Table 2, and all indicators are good. Similarly, tests under various working conditions were carried out, and the test indicators all met the requirements.

[0133] Table 1 Operating power 0.3P n Results at different frequency changes

[0134]

[0135]

[0136] Table 2 0.35P n Key indicators of lower inertia test

[0137]

[0138] This application analyzes the response of traditional VSG to frequency and grid connection point voltage, and implements current source network simulation control technology based on frequency extraction technology. The loop transformation is simple and there is no need to modify the current source main control loop. When the grid frequency changes, the inverter can respond to the frequency quickly. And through experimental verification, the virtual synchronous machine output characteristic simulation scheme runs well and meets the expected power response rate and accuracy requirements.

[0139] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0140] The following is an embodiment of the device of the present invention. For details not described in detail therein, reference may be made to the corresponding method embodiment described above.

[0141] Figure 8 The structure diagram of the control device for current source simulation network construction provided by an embodiment of the present invention is shown. For the convenience of description, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0142] like Figure 8 As shown, the control device 30 for current source simulation network construction may include: an acquisition module 31 , a frequency calculation module 32 , an active power adjustment module 33 and a control module 34 .

[0143] The acquisition module 31 is used to acquire the current frequency of the grid-connected point; the grid-connected point is the connection point where the grid-connected inverter is connected to the power grid;

[0144] The frequency calculation module 32 is used to determine the current frequency offset of the grid connection point and the current frequency change rate of the grid connection point according to the current frequency of the grid connection point;

[0145] The active power adjustment module 33 is used to determine the active power adjustment amount of the current source simulation network according to the current frequency offset of the grid connection point and the current frequency change rate of the grid connection point; the active power adjustment amount of the current source simulation network includes the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter and the active power adjustment amount of the inertia response of the grid-connected inverter;

[0146] The control module 34 is used to perform grid-following control on the grid-connected inverter based on the active power adjustment amount of the current source simulated grid construction, so as to realize the current source simulated grid construction.

[0147] In a possible implementation, the active power adjustment module 33 is specifically used to:

[0148] According to the current frequency offset of the grid-connected point, the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter is determined;

[0149] According to the current frequency change rate of the grid-connected point, the active power adjustment amount of the inertia response of the grid-connected inverter is determined;

[0150] Based on the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter and the active power adjustment amount of the inertia response of the grid-connected inverter, the active power adjustment amount of the current source simulation network is determined.

[0151] In a possible implementation, in the active power adjustment module 33, the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter is determined according to the current frequency offset of the grid-connected point, including:

[0152] according to Determine the active power adjustment amount P of the primary frequency modulation response of the grid-connected inverter f ; Among them, K f is the active frequency modulation coefficient, P n is the rated power of the grid-connected inverter, f N is the reference frequency of the power grid, and Δf is the current frequency offset of the grid connection point.

[0153] In a possible implementation, in the active power adjustment module 33, the active power adjustment amount of the inertia response of the grid-connected inverter is determined according to the current frequency change rate of the grid-connected point, including:

[0154] according to Determine the active power adjustment P of the grid-connected inverter inertia response in ; Among them, P n is the rated power of the grid-connected inverter, fN is the reference frequency of the power grid, T J is the inertia time constant; is the current frequency change rate of the grid connection point.

[0155] In a possible implementation, the control device 30 for current source simulation networking may further include: a reactive power adjustment module.

[0156] Reactive power regulation module is used for:

[0157] Based on the active power adjustment amount of the current source simulation network, the grid-connected inverter is controlled to follow the grid, so as to obtain the effective value of the current voltage at the grid connection point before the current source simulation network is realized;

[0158] Calculate the voltage difference between the effective value of the current voltage at the grid connection point and the rated voltage at the grid connection point;

[0159] According to the voltage difference, the reactive power adjustment amount of the primary voltage regulation response of the grid-connected inverter is determined, and the reactive power adjustment amount of the primary voltage regulation response of the grid-connected inverter is used as the reactive power adjustment amount of the current source simulation network.

[0160] Accordingly, the control module 34 is specifically used for:

[0161] Based on the active power adjustment amount of the current source simulation network and the reactive power adjustment amount of the current source simulation network, the grid-connected inverter is controlled to realize the current source simulation network.

[0162] In a possible implementation, in the reactive power adjustment module, the reactive power adjustment amount of the primary voltage regulation response of the grid-connected inverter is determined according to the voltage difference, including:

[0163] according to Determine the reactive power adjustment Q of the primary voltage regulation response of the grid-connected inverter v ; Among them, K v is the reactive voltage regulation coefficient, S N is the rated capacity of the virtual synchronous machine, ΔU is the voltage difference, U N is the rated voltage of the grid connection point.

[0164] In a possible implementation, in the control module 34, based on the active power adjustment amount of the current source simulation network, the grid-connected inverter is subjected to grid-following control, including:

[0165] Obtaining an active power given value, and taking the sum of the active power given value and the active power adjustment amount of the current source simulation network as a new active power given value;

[0166] According to the new active power given value, the grid-connected inverter is controlled in a grid-following manner.

[0167] In a possible implementation, in the frequency calculation module 32, the current frequency change rate of the grid connection point is determined according to the current frequency of the grid connection point, including:

[0168] Get the current location identifier;

[0169] Get the frequency corresponding to the current positioning identifier stored in a pre-created array;

[0170] Determine the current frequency change rate of the grid connection point according to the current frequency of the grid connection point, the frequency corresponding to the current positioning identifier and the duration of a preset number of cycles; the preset number is the size of the array;

[0171] The frequency corresponding to the current positioning identifier stored in the array is updated to the current frequency of the grid connection point, and the current positioning identifier is updated.

[0172] Fig. 9 Schematic diagram of an electronic device provided by an embodiment of the present invention. Fig. 9 As shown, the electronic device 4 of this embodiment includes: a processor 40 and a memory 41. The memory 41 is used to store a computer program 42, and the processor 40 is used to call and run the computer program 42 stored in the memory 41 to perform the steps in the above-mentioned control method embodiments of each current source simulation network, such as Figure 2 Alternatively, the processor 40 is used to call and run the computer program 42 stored in the memory 41 to implement the functions of each module / unit in the above-mentioned device embodiments, for example Figure 8 The functions of each module are shown.

[0173] Exemplarily, the computer program 42 may be divided into one or more modules / units, which are stored in the memory 41 and executed by the processor 40 to implement the present invention. The one or more modules / units may be a series of computer program instruction segments capable of implementing specific functions, which are used to describe the execution process of the computer program 42 in the electronic device 4. For example, the computer program 42 may be divided into Figure 8 The modules shown.

[0174] The electronic device 4 may include, but is not limited to, a processor 40 and a memory 41. Those skilled in the art will appreciate that Fig. 9 It is only an example of the electronic device 4 and does not constitute a limitation of the electronic device 4. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device may also include input and output devices, network access devices, buses, etc.

[0175] The processor 40 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0176] The memory 41 may be an internal storage unit of the electronic device 4, such as a hard disk or memory of the electronic device 4. The memory 41 may also be an external storage device of the electronic device 4, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device 4. Further, the memory 41 may also include both an internal storage unit and an external storage device of the electronic device 4. The memory 41 is used to store the computer program and other programs and data required by the electronic device. The memory 41 may also be used to temporarily store data that has been output or is to be output.

[0177] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0178] Corresponding to the above-mentioned electronic device, an embodiment of the present application further provides a grid-connected inverter, comprising the above-mentioned electronic device.

[0179] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0180] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0181] In the embodiments provided by the present invention, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0182] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0183] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0184] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, the steps of the control method embodiments of the above-mentioned current source simulation network can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device that can carry the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium.

[0185] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A control method for current source simulation network construction, characterized in that: include: Obtaining the current frequency of the grid-connected point; the grid-connected point is the connection point where the grid-connected inverter is connected to the power grid; Determining a current frequency offset of the grid connection point and a current frequency change rate of the grid connection point according to the current frequency of the grid connection point; Determine the active power adjustment of the current source simulation network according to the current frequency offset of the grid-connected point and the current frequency change rate of the grid-connected point; the active power adjustment of the current source simulation network includes the active power adjustment of the primary frequency modulation response of the grid-connected inverter and the active power adjustment of the inertia response of the grid-connected inverter; Based on the active power adjustment amount of the current source simulated networking, the grid-connected inverter is subjected to grid-following control to realize the current source simulated networking.

2. The control method for current source simulation network construction according to claim 1, characterized in that: The step of determining the active power adjustment amount of the current source simulated network according to the current frequency offset of the grid connection point and the current frequency change rate of the grid connection point includes: Determining the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter according to the current frequency offset of the grid-connected point; Determining an active power adjustment amount of an inertia response of a grid-connected inverter according to a current frequency change rate of the grid-connected point; Based on the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter and the active power adjustment amount of the inertia response of the grid-connected inverter, the active power adjustment amount of the current source simulated grid is determined.

3. The control method for current source simulation network construction according to claim 2 is characterized in that: The step of determining the active power adjustment amount of the primary frequency modulation response of the grid-connected inverter according to the current frequency offset of the grid-connected point includes: according to Determine the active power adjustment amount P of the primary frequency modulation response of the grid-connected inverter f ; Among them, K f is the active frequency modulation coefficient, P n is the rated power of the grid-connected inverter, f N is the reference frequency of the power grid, and Δf is the current frequency offset of the grid connection point.

4. The control method for current source simulation network construction according to claim 2 is characterized in that: Determining the active power adjustment amount of the inertia response of the grid-connected inverter according to the current frequency change rate of the grid-connected point includes: according to Determine the active power adjustment P of the grid-connected inverter inertia response in ; Among them, P n is the rated power of the grid-connected inverter, f N is the reference frequency of the power grid, T J is the inertia time constant; is the current frequency change rate of the grid connection point.

5. The control method for current source simulation network construction according to claim 1, characterized in that: Before the grid-connected inverter is subjected to grid-following control based on the active power adjustment amount of the current source simulated networking to realize the current source simulated networking, the control method of the current source simulated networking further includes: Obtaining the effective value of the current voltage of the grid connection point; Calculating a voltage difference between an effective value of a current voltage of the grid connection point and a rated voltage of the grid connection point; Determine the reactive power adjustment amount of the primary voltage regulation response of the grid-connected inverter according to the voltage difference, and use the reactive power adjustment amount of the primary voltage regulation response of the grid-connected inverter as the reactive power adjustment amount of the current source simulation network; Correspondingly, the active power adjustment amount based on the current source simulated networking is used to perform grid-following control on the grid-connected inverter to realize the current source simulated networking, including: Based on the active power adjustment amount of the current source simulated networking and the reactive power adjustment amount of the current source simulated networking, the grid-connected inverter is controlled in a grid-following manner to realize the current source simulated networking.

6. The control method for current source simulation network construction according to claim 5, characterized in that: Determining the reactive power adjustment amount of the primary voltage regulation response of the grid-connected inverter according to the voltage difference includes: according to Determine the reactive power adjustment Q of the primary voltage regulation response of the grid-connected inverter v ; Among them, K v is the reactive voltage regulation coefficient, S N is the rated capacity of the virtual synchronous machine, ΔU is the voltage difference, U N is the rated voltage of the grid connection point.

7. The control method for current source simulation network construction according to any one of claims 1 to 6, characterized in that: The active power adjustment amount of the network constructed based on the current source simulation is used to perform grid-following control on the grid-connected inverter, including: Obtaining an active power given value, and taking the sum of the active power given value and the active power adjustment amount of the current source simulated network as a new active power given value; According to the new active power given value, the grid-connected inverter is subjected to grid-following control.

8. The control method for current source analog networking according to any one of claims 1 to 6, characterized in that: Determining a current frequency change rate of the grid connection point according to the current frequency of the grid connection point includes: Get the current location identifier; Get the frequency corresponding to the current positioning identifier stored in a pre-created array; Determine the current frequency change rate of the grid connection point according to the current frequency of the grid connection point, the frequency corresponding to the current positioning identifier and the duration of a preset number of cycles; the preset number is the size of the array; The frequency corresponding to the current positioning identifier stored in the array is updated to the current frequency of the grid connection point, and the current positioning identifier is updated.

9. An electronic device, characterized in that: It comprises a memory and a processor, wherein the memory is used to store a computer program, and the processor is used to call and run the computer program stored in the memory to execute the control method of current source simulation networking as described in any one of claims 1 to 8.

10. A grid-connected inverter, characterized in that: Comprising the electronic device as claimed in claim 9.

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