A current inner loop control parameter identification method of a new energy grid-connected converter

Abstract

The embodiment of the application discloses a current inner loop control parameter identification method of a new energy grid-connected converter, comprising the following steps: determining a target transfer function according to a first transfer function of a zero-order holder, a second transfer function of a PWM controller, a third transfer function of a current inner loop control link and a fourth transfer function of a main circuit control link; then replacing the third transfer function and the fourth transfer function with the target transfer function and removing a proportional integral item of a fifth transfer function of a voltage outer loop control link; finally, performing step disturbance on a q-axis component reactive power reference value and a d-axis component DC voltage reference value of the voltage outer loop control link respectively, obtaining a first response curve and a second response curve of current feedback values of q-axis components and d-axis components of the current inner loop control link respectively, and determining control parameters of the q-axis components and the d-axis components of the current inner loop control link respectively; the method can effectively solve the technical problems existing in the prior art.

Description

Technical Field

[0001] This invention relates to the field of power system technology, and in particular to a method for identifying the inner loop control parameters of a new energy grid-connected converter. Background Technology

[0002] In the field of new energy power generation, the widespread application of mainstream models such as direct-drive wind turbines, doubly-fed induction generators (DFIGs), and photovoltaic power plants has placed higher demands on the accuracy and stability of power grid simulation. However, the "black box" nature of new energy unit controllers makes it difficult to directly obtain their control models, and traditional electromechanical transient simulation methods are no longer sufficient to meet the simulation needs of "high-proportion renewable energy integration and high power electronic equipment penetration" power systems. To accurately simulate the dynamic behavior of new energy units in the power grid, especially their response characteristics under fault conditions, it is urgent to conduct electromagnetic transient modeling work for new energy. This work will not only help improve the accuracy of power grid simulation but also provide strong support for the safe and reliable operation of the power grid.

[0003] However, due to commercial confidentiality considerations, current new energy manufacturers have not disclosed their complete electromagnetic transient models, leaving users with only "black box" models. This prevents them from deeply studying the internal dynamic response parameters of the units and their impact on grid stability, and makes it even more difficult to improve control and protection based on the original models. This limitation seriously hinders the development of research on grid connection of new energy units.

[0004] Therefore, the identification of control parameters is particularly important. By identifying control parameters, a relatively complete structured electromagnetic model of a new energy unit can be constructed without relying on the manufacturer's model, thereby revealing the dynamic characteristics inside the unit and providing a foundation for grid simulation, stability analysis, and control strategy optimization. However, existing control parameter identification methods still have many shortcomings, such as strong data dependence, numerous model assumptions, high algorithm complexity, and lack of universality. These shortcomings limit the accuracy and practicality of the identification results. Summary of the Invention

[0005] Based on this, it is necessary to propose a method for identifying the current inner loop control parameters of new energy grid-connected converters to address the above problems. This method can effectively solve the technical problems existing in the current technology, improve the accuracy and practicality of the identification results, and provide strong support for electromagnetic transient modeling and grid connection research of new energy units.

[0006] To achieve the above objectives, the present invention provides, in a first aspect, a method for identifying the inner loop control parameters of a new energy grid-connected converter, the method comprising:

[0007] acquire a first transfer function of a zero-order holder, a second transfer function of a PWM controller, a third transfer function of an i-axis component of a current inner loop control link in a new energy grid-connected system, and a fourth transfer function of an i-axis component of a main circuit control link, and determine a target transfer function according to the first transfer function, the second transfer function, the third transfer function, and the fourth transfer function; replace the third transfer function and the fourth transfer function in the new energy grid-connected system with the target transfer function, and remove a proportional integral term of a fifth transfer function of an i-axis component of a voltage outer loop control link in the new energy grid-connected system; wherein i is q and d in turn, to obtain the new energy grid-connected system after replacement and removal;

[0008] make a step disturbance to a reactive power reference value of a q-axis component of the voltage outer loop control link in the new energy grid-connected system after replacement and removal, acquire a first response curve of a current feedback value of a q-axis component of a current inner loop control link in the new energy grid-connected system, and determine a control parameter of the q-axis component of the current inner loop control link according to the first response curve;

[0009] make a step disturbance to a direct current voltage reference value of a d-axis component of the voltage outer loop control link in the new energy grid-connected system after replacement and removal, acquire a second response curve of a current feedback value of a d-axis component of a current inner loop control link in the new energy grid-connected system, and determine a control parameter of the d-axis component of the current inner loop control link according to the second response curve.

[0010] Optionally, the determining of the target transfer function according to the first transfer function, the second transfer function, the third transfer function, and the fourth transfer function comprises:

[0011] equivalent simplification is performed on the third transfer function and the fourth transfer function to obtain an initial transfer function;

[0012] the first transfer function and the second transfer function are substituted into the initial transfer function to obtain a detailed transfer function;

[0013] equivalent simplification is performed on the detailed transfer function to obtain the target transfer function.

[0014] Optionally,

[0015] in the case that i is q, the third transfer function is:

[0016] in the case that i is d, the third transfer function is:

[0017] in the case that i is q, the fourth transfer function is:

[0018] In the case of i taking d, the fourth transfer function is:

[0019] wherein, is a voltage reference value of a q-axis component of the current inner loop control link, is a current reference value of the q-axis component of the current inner loop control link, i g,q is a current feedback value of the q-axis component of the current inner loop control link, K p,q is a proportional coefficient of a PI controller of the q-axis component of the current inner loop control link, τ i,q is an integral time constant of the PI controller of the q-axis component of the current inner loop control link, s being a Laplace operator, i g,d is a current feedback value of a d-axis component of the current inner loop control link, ω1 being a synchronous angular frequency of a power grid in the new energy grid-connected system, L g is a connecting inductance of a converter in the new energy grid-connected system, is a voltage reference value of the d-axis component of the current inner loop control link, is a current reference value of the d-axis component of the current inner loop control link, K p,d is a proportional coefficient of a PI controller of the d-axis component of the current inner loop control link, τ i,d is an integral time constant of the PI controller of the d-axis component of the current inner loop control link, u g,d is a voltage feedback value of the d-axis component of the current inner loop control link, R g is a connecting resistance of the converter in the new energy grid-connected system.

[0020] Optionally,

[0021] In the case of i taking q, the initial transfer function is:

[0022] In the case of i taking d, the initial transfer function is:

[0023] wherein, i g,q is a current feedback value of a q-axis component of the current inner loop control link, is a current reference value of the q-axis component of the current inner loop control link, K p,q is a proportional coefficient of a PI controller of the q-axis component of the current inner loop control link, τ i,q is an integral time constant of the PI controller of the q-axis component of the current inner loop control link, s being a Laplace operator, L g is a connecting inductance of a converter in the new energy grid-connected system, Rg is a connection resistance of a converter in the new energy grid-connected system, i g,d is a current feedback value of a d-axis component of the current inner loop control link, is a current reference value of the d-axis component of the current inner loop control link, K p,d is a proportional coefficient of a PI controller of the d-axis component of the current inner loop control link, τ i,d is an integral time constant of the PI controller of the d-axis component of the current inner loop control link.

[0024] Optionally,

[0025] The first transfer function is:

[0026] The second transfer function is:

[0027] wherein,

[0028] wherein, ZOH(s) is an output value of the zero-order holder, e is a natural constant, T s is a delay time of the PWM controller, s is a Laplace operator, W(s) is an output value of the PWM controller, K PWM is an amplification coefficient of the PWM controller, U dc,ins is a direct current voltage instantaneous value of a converter in the new energy grid-connected system, U sp is a sawtooth wave peak value of the PWM controller.

[0029] Optionally,

[0030] In the case of i taking q, the detailed transfer function is:

[0031] In the case of i taking d, the detailed transfer function is:

[0032] wherein, i g,q is a current feedback value of a q-axis component of the current inner loop control link, is a current reference value of the q-axis component of the current inner loop control link, K p,q is a proportional coefficient of a PI controller of the q-axis component of the current inner loop control link, τ i,q is an integral time constant of the PI controller of the q-axis component of the current inner loop control link, s is a Laplace operator, T s is a delay time of the PWM controller, K PWM is an amplification coefficient of the PWM controller, Lg L is a connection inductance of the converter in the new energy grid-connected system, g R is a connection resistance of the converter in the new energy grid-connected system, g,d id is a current feedback value of the d-axis component of the current inner loop control link, id* is a current reference value of the d-axis component of the current inner loop control link, p,d Kp is a proportional coefficient of the PI controller of the d-axis component of the current inner loop control link, i,d τ is an integral time constant of the PI controller of the d-axis component of the current inner loop control link.

[0033] Optionally, the control parameter of the q-axis component of the current inner loop control link is determined according to the first response curve.

[0034] In the case of i taking q, the target transfer function is:

[0035] In the case of i taking d, the target transfer function is:

[0036] Kp is a proportional coefficient of the PI controller of the q-axis component of the current inner loop control link, i,q τ is an integral time constant of the PI controller of the q-axis component of the current inner loop control link, s is a Laplace operator, i,d τ is an integral time constant of the PI controller of the d-axis component of the current inner loop control link, g L is a connection inductance of the converter in the new energy grid-connected system, g R is a connection resistance of the converter in the new energy grid-connected system, g,q id is a current feedback value of the q-axis component of the current inner loop control link, id* is a current reference value of the q-axis component of the current inner loop control link, p,q Kp is a proportional coefficient of the PI controller of the q-axis component of the current inner loop control link, PWM K is an amplification coefficient of the PWM controller, g L is a connection inductance of the converter in the new energy grid-connected system, s T is a delay time of the PWM controller, g,d id is a current feedback value of the d-axis component of the current inner loop control link, id* is a current reference value of the d-axis component of the current inner loop control link, p,d Kp is a proportional coefficient of the PI controller of the d-axis component of the current inner loop control link.

[0037] Optionally, the control parameter of the q-axis component of the current inner loop control link is determined according to the first response curve, comprising:

[0038] determine a first overshoot amount according to the first response curve;

[0039] determine a first damping ratio according to the first overshoot amount;

[0040] determine a control parameter of a q-axis component of the current inner loop control link according to the first damping ratio;

[0041] The determining the control parameter of the d-axis component of the current inner loop control link according to the second response curve comprises:

[0042] determine a second overshoot amount according to the second response curve;

[0043] determine a second damping ratio according to the second overshoot amount;

[0044] determine the control parameter of the d-axis component of the current inner loop control link according to the second damping ratio.

[0045] Optionally, the determining the control parameter of the q-axis component of the current inner loop control link according to the first damping ratio comprises:

[0046] determining the control parameter of the q-axis component of the current inner loop control link by using a formula

[0047] The determining the control parameter of the d-axis component of the current inner loop control link according to the second damping ratio comprises:

[0048] determining the control parameter of the d-axis component of the current inner loop control link by using a formula

[0049] wherein,

[0050] wherein, K p,q and K i,q is the control parameter of the q-axis component of the current inner loop control link, K p,q is a proportional coefficient of a PI controller of the q-axis component of the current inner loop control link, K i,q is an integral coefficient of the PI controller of the q-axis component of the current inner loop control link, L g is a connection inductance of a converter in the new energy grid-connected system, K PWM is an amplification coefficient of the PWM controller, T s is a delay time of the PWM controller, ξ 1,q is the first damping ratio, τ i,q is an integral time constant of the PI controller of the q-axis component of the current inner loop control link, K p,d and K i,d ​​K is a control parameter of a d-axis component of the current inner loop control link p,d K is a proportional coefficient of a PI controller of a d-axis component of the current inner loop control link i,d K is an integral coefficient of a PI controller of a d-axis component of the current inner loop control link 2,d K is the second damping ratio i,d K is an integral time constant of a PI controller of a d-axis component of the current inner loop control link g K is a connection resistance of a converter in the new energy grid-connected system.

[0051] Optionally, the first overshoot is determined according to the first response curve, comprising:

[0052] determining a steady-state current value and a first current peak value of the first response curve according to the first response curve;

[0053] determining the first overshoot according to the steady-state current value and the first current peak value of the first response curve;

[0054] The second overshoot is determined according to the second response curve, comprising:

[0055] determining a steady-state current value and a first current peak value of the second response curve according to the second response curve;

[0056] determining the second overshoot according to the steady-state current value and the first current peak value of the second response curve.

[0057] To achieve the above object, the application provides a current inner loop control parameter identification device of a new energy grid-connected converter in a second aspect, which comprises:

[0058] a system adjustment module, configured to acquire a first transfer function of a zero-order holder, a second transfer function of a PWM controller, a third transfer function of an i-axis component of a current inner loop control link in a new energy grid-connected system, and a fourth transfer function of an i-axis component of a main circuit control link, and determine a target transfer function according to the first transfer function, the second transfer function, the third transfer function and the fourth transfer function; replace the third transfer function and the fourth transfer function in the new energy grid-connected system with the target transfer function, and remove a proportional integral term of a fifth transfer function of an i-axis component of a voltage outer loop control link in the new energy grid-connected system; wherein i is q, d in turn, to obtain the new energy grid-connected system after replacement and removal;

[0059] The first identification module is used for making step disturbance to a reactive power reference value of a q-axis component of a voltage outer loop control link in the new energy grid-connected system after the replacement and removal, obtaining a first response curve of a current feedback value of a q-axis component of a current inner loop control link in the new energy grid-connected system after the replacement and removal, and determining a control parameter of the q-axis component of the current inner loop control link according to the first response curve.

[0060] The second identification module is used for making step disturbance to a direct current voltage reference value of a d-axis component of the voltage outer loop control link in the new energy grid-connected system after the replacement and removal, obtaining a second response curve of a current feedback value of a d-axis component of the current inner loop control link in the new energy grid-connected system after the replacement and removal, and determining a control parameter of the d-axis component of the current inner loop control link according to the second response curve.

[0061] To achieve the above object, the present application provides a computer readable storage medium storing a computer program in a third aspect, the computer program is executed by a processor, so that the processor executes the method as any one of the first aspect.

[0062] To achieve the above object, the present application provides a computer device in a fourth aspect, comprising a memory and a processor, the memory stores a computer program, the computer program is executed by the processor, so that the processor executes the method as any one of the first aspect.

[0063] The embodiment of the present application has the following beneficial effects: the method obtains the first transfer function of the zero-order holder, the second transfer function of the PWM controller, the third transfer function of the i-axis component of the current inner loop control link in the new energy grid-connected system, and the fourth transfer function of the i-axis component of the main circuit control link, and determines the target transfer function according to the first transfer function, the second transfer function, the third transfer function, and the fourth transfer function; the third transfer function and the fourth transfer function in the new energy grid-connected system are replaced with the target transfer function, and the proportional integral term of the fifth transfer function of the i-axis component of the voltage outer loop control link in the new energy grid-connected system is removed; wherein i is q, d in turn; the reactive power reference value of the q-axis component of the voltage outer loop control link is subjected to a step disturbance, the first response curve of the current feedback value of the q-axis component of the current inner loop control link is obtained, and the control parameter of the q-axis component of the current inner loop control link is determined according to the first response curve; the direct current voltage reference value of the d-axis component of the voltage outer loop control link is subjected to a step disturbance, the second response curve of the current feedback value of the d-axis component of the current inner loop control link is obtained, and the control parameter of the d-axis component of the current inner loop control link is determined according to the second response curve; the new energy grid-connected system after replacement and removal is obtained, and then the new energy grid-connected system after replacement and removal is subjected to disturbance test, so that the technical problems existing in the prior art can be effectively solved, the accuracy and practicality of the identification result can be effectively improved, and strong support is provided for electromagnetic transient modeling and grid connection research of new energy units. BRIEF DESCRIPTION OF DRAWINGS

[0064] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. 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.

[0065] Among them:

[0066] Figure 1 It is a schematic diagram of a current inner loop control parameter identification method of a new energy grid-connected converter in the embodiment of the present application;

[0067] Figure 2 It is a schematic diagram of the third transfer function of the current inner loop control link and the fourth transfer function of the main circuit control link in the embodiment of the present application;

[0068] Figure 3 It is a schematic diagram of the initial transfer function of the current inner loop control link and the main circuit control link in the embodiment of the present application;

[0069] Figure 4A schematic diagram of a detailed transfer function of the current inner loop control link and the main circuit control link in the embodiment of the present application;

[0070] Figure 5 A schematic diagram of a target transfer function of the current inner loop control link and the main circuit control link in the embodiment of the present application;

[0071] Figure 6 A schematic diagram of the first response curve or the second response curve in the embodiment of the present application;

[0072] Figure 7 A schematic diagram of a fifth transfer function of the voltage outer loop control link in the embodiment of the present application before the proportional integral term is removed;

[0073] Figure 8 Another schematic diagram of the fifth transfer function of the voltage outer loop control link in the embodiment of the present application before the proportional integral term is removed;

[0074] Figure 9 A schematic diagram of the fifth transfer function of the voltage outer loop control link in the embodiment of the present application after the proportional integral term is removed;

[0075] Figure 10 Another schematic diagram of the fifth transfer function of the voltage outer loop control link in the embodiment of the present application after the proportional integral term is removed;

[0076] Figure 11 A schematic diagram of a current inner loop control parameter identification device of a new energy grid-connected converter in the embodiment of the present application;

[0077] Figure 12 An internal structure diagram of a computer device in some embodiments. DETAILED DESCRIPTION

[0078] The technical solutions in the embodiments of the present application will be described clearly and completely 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. 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.

[0079] In the field of new energy power generation, the widespread application of mainstream models such as direct-drive wind turbines, doubly-fed wind turbines and photovoltaic systems has put forward higher requirements for the simulation accuracy and stability of the power grid. However, the current situation of "black box" of new energy unit controller makes it difficult to obtain its control model directly, and the traditional electromechanical transient simulation method has been difficult to meet the simulation needs of "double high" (high proportion of renewable energy access, high penetration rate of power electronic equipment) power system. In order to accurately simulate the dynamic behavior of new energy units in the power grid, especially the response characteristics under fault conditions, it is urgent to carry out new energy electromagnetic transient modeling work. This work not only helps to improve the accuracy of power grid simulation, but also provides strong support for the safe and reliable operation of the power grid.

[0080] However, current new energy manufacturers do not disclose their complete electromagnetic transient model due to commercial secrets, resulting in users only being able to obtain "black box" models, making it difficult to deeply study the internal dynamic response parameters of the unit and their impact on grid stability, and even more difficult to improve control and protection based on the original model. This limitation has seriously hindered the development of new energy unit grid connection research.

[0081] Therefore, the identification of control parameters is particularly important. By identifying control parameters, a relatively complete structured electromagnetic model of new energy units can be constructed without relying on manufacturer models, thereby revealing the internal dynamic characteristics of the unit and providing a basis for power grid simulation, stability analysis and control strategy optimization. However, existing control parameter identification methods still have many shortcomings, such as strong data dependence, many model assumptions, high algorithm complexity and lack of universality, which limit the accuracy and practicality of the identification results.

[0082] To solve the above problems, the present application provides a current inner loop control parameter identification method for new energy grid-connected converters, which can effectively solve the technical problems existing in the prior art, improve the accuracy and practicality of the identification results, and provide strong support for electromagnetic transient modeling and grid connection research of new energy units. The specific implementation principle will be described in detail in the following embodiments.

[0083] In a first aspect, the present application provides a current inner loop control parameter identification method for new energy grid-connected converters.

[0084] Please refer to Figure 1 , a schematic diagram of a current inner loop control parameter identification method for new energy grid-connected converters in an embodiment of the present application, the method comprises:

[0085] Step 110: obtaining a first transfer function of the zero-order holder, a second transfer function of the PWM controller, a third transfer function of an i-axis component of a current inner loop control link in the new energy grid-connected system, and a fourth transfer function of an i-axis component of a main circuit control link, and determining a target transfer function according to the first transfer function, the second transfer function, the third transfer function, and the fourth transfer function; replacing the third transfer function and the fourth transfer function in the new energy grid-connected system with the target transfer function, and removing a proportional integral term of a fifth transfer function of an i-axis component of a voltage outer loop control link in the new energy grid-connected system; wherein i is q, d in turn, to obtain the new energy grid-connected system after replacement and removal.

[0086] PWM is Pulse-Width Modulation, i.e. pulse width modulation; for the first transfer function of the zero-order holder, the second transfer function of the PWM controller, the third transfer function of the current inner loop control link, the fourth transfer function of the main circuit control link, and the fifth transfer function of the voltage outer loop control link, mathematical equation transfer functions in the prior art can be used, which are not limited here.

[0087] It should be noted that the proportional integral term of the fifth transfer function of the voltage outer loop control link refers to the transfer function of the PI controller of the voltage outer loop control link; for example, the transfer function of the PI controller is G q,or,d (s) or is the proportional integral term of the fifth transfer function of the voltage outer loop control link; wherein G q,or,d (s) is the output value of the PI controller of the q or d-axis component of the voltage outer loop control link, K q,or,d is the proportional coefficient of the PI controller of the q or d-axis component of the voltage outer loop control link, τ q,or,d is the integral time constant of the PI controller of the q or d-axis component of the voltage outer loop control link, s is the Laplace operator, and PI is Proportional Integral, i.e. proportional integral.

[0088] Of course, in some embodiments, if the voltage outer loop control link does not have a PI controller, there is naturally no need to remove the proportional integral term of the fifth transfer function of the voltage outer loop control link; for example, the fifth transfer function of the d-axis component of the voltage outer loop control link has a proportional integral term, while the fifth transfer function of the q-axis component of the voltage outer loop control link does not have a proportional integral term, at this time, only the proportional integral term of the fifth transfer function of the d-axis component of the voltage outer loop control link needs to be removed.

[0089] It needs to be further explained that, in the present application, the target transfer function is determined according to the first transfer function of the zero-order holder, the second transfer function of the PWM controller, the third transfer function of the current inner loop control link in the new energy grid-connected system, and the fourth transfer function of the main circuit control link, and the third transfer function and the fourth transfer function in the new energy grid-connected system are replaced by the target transfer function, which is to simplify the new energy grid-connected system from the transfer function of the control, so as to facilitate the subsequent identification of the control parameters of the current inner loop control link.

[0090] It can be understood that, "determining the target transfer function according to the first transfer function of the zero-order holder, the second transfer function of the PWM controller, the third transfer function of the current inner loop control link in the new energy grid-connected system, and the fourth transfer function of the main circuit control link", wherein the first transfer function of the zero-order holder takes into account the discreteness of the actual data of the new energy grid-connected system, and the second transfer function of the PWM controller takes into account the actual influence of the converter on the new energy grid-connected system, that is, by adding the first transfer function of the zero-order holder and the second transfer function of the PWM controller, the simplified new energy grid-connected system (i.e. the new energy grid-connected system after replacing the third transfer function and the fourth transfer function in the new energy grid-connected system with the target transfer function) can be more consistent with the actual new energy grid-connected system, so as to obtain current inner loop control parameters with higher accuracy; "replacing the third transfer function and the fourth transfer function in the new energy grid-connected system with the target transfer function", at this time, the transfer functions of the current inner loop control link and the main circuit control link in the new energy grid-connected system are the target transfer function, that is, the new energy grid-connected system is simplified from the transfer function of the control, so as to facilitate the subsequent identification of the current inner loop control parameters.

[0091] Further, after simplifying the new energy grid-connected system, the proportional integral term of the fifth transfer function of the voltage outer loop control link in the new energy grid-connected system also needs to be removed; it can be understood that the identification of the control parameters of the current inner loop control link refers to the identification of the control parameters of the PI controller of the current inner loop control link, if the proportional integral term of the fifth transfer function of the voltage outer loop control link is not removed, that is, the PI controller of the voltage outer loop control link is not removed, since the PI controller of the voltage outer loop control link also has control parameters, the identification of the control parameters of the current inner loop control link will be affected, resulting in the inability to identify the control parameters of the current inner loop control link.

[0092] It needs to be particularly pointed out that by replacing the third transfer function of the current inner loop control link and the fourth transfer function of the main circuit control link in the new energy grid-connected system with the target transfer function and removing the proportional integral term of the fifth transfer function of the voltage outer loop control link in the new energy grid-connected system, the new energy grid-connected system after replacement and removal can be obtained.

[0093] Step 120: A step disturbance is made to the reactive power reference value of the q-axis component of the voltage outer loop control link in the new energy grid-connected system after replacement and removal, a first response curve of the current feedback value of the q-axis component of the current inner loop control link in the new energy grid-connected system after replacement and removal is obtained, and the control parameter of the q-axis component of the current inner loop control link is determined according to the first response curve.

[0094] It needs to be particularly pointed out that by replacing the third transfer function of the current inner loop control link and the fourth transfer function of the main circuit control link in the new energy grid-connected system with the target transfer function and removing the proportional integral term of the fifth transfer function of the voltage outer loop control link in the new energy grid-connected system, the new energy grid-connected system after replacement and removal can be obtained.

[0095] In some embodiments, a 10% step disturbance can be made to the reactive power reference value of the q-axis component of the voltage outer loop control link in the new energy grid-connected system after replacement and removal.

[0096] In some embodiments, the control parameter of the q-axis component of the current inner loop control link includes the proportional coefficient and the integral coefficient of the PI controller of the q-axis component of the current inner loop control link.

[0097] Step 130: A step disturbance is made to the direct current voltage reference value of the d-axis component of the voltage outer loop control link in the new energy grid-connected system after replacement and removal, a second response curve of the current feedback value of the d-axis component of the current inner loop control link in the new energy grid-connected system after replacement and removal is obtained, and the control parameter of the d-axis component of the current inner loop control link is determined according to the second response curve.

[0098] For the explanation of “a step disturbance is made to the direct current voltage reference value of the d-axis component of the voltage outer loop control link in the new energy grid-connected system after replacement and removal”, reference can be made to the related content of “a step disturbance is made to the reactive power reference value of the q-axis component of the voltage outer loop control link in the new energy grid-connected system after replacement and removal” in the above-mentioned embodiments, which will not be repeated here.

[0099] In some embodiments, a 10% step disturbance can be applied to the reactive power reference value of the q-axis component of the voltage outer loop control link in the new energy grid-connected system after replacement and removal.

[0100] In some embodiments, the control parameters of the d-axis component of the current inner loop control link include the proportional coefficient and the integral coefficient of the PI controller of the d-axis component of the current inner loop control link.

[0101] In the embodiments of the present application, the target transfer function is determined according to the first transfer function of the zero-order holder, the second transfer function of the PWM controller, the third transfer function of the current inner loop control link and the fourth transfer function of the main circuit control link, then the third transfer function and the fourth transfer function are replaced by the target transfer function, the proportional integral term of the fifth transfer function of the voltage outer loop control link is removed, and finally the first response curve and the second response curve of the current feedback values of the q-axis component and the d-axis component of the current inner loop control link are obtained by respectively applying step disturbances to the reactive power reference value of the q-axis component and the DC voltage reference value of the d-axis component of the voltage outer loop control link, so as to determine the control parameters of the q-axis component and the d-axis component of the current inner loop control link. The above-mentioned method can effectively solve the technical problems existing in the prior art, can effectively improve the accuracy and practicality of the identification result, and can provide strong support for the electromagnetic transient state modeling and grid connection research of new energy units.

[0102] In a feasible implementation manner, the step 110 in the above-mentioned embodiments, determining the target transfer function according to the first transfer function, the second transfer function, the third transfer function and the fourth transfer function, includes: equivalently simplifying the third transfer function and the fourth transfer function to obtain an initial transfer function; substituting the first transfer function and the second transfer function into the initial transfer function to obtain a detailed transfer function; equivalently simplifying the detailed transfer function to obtain the target transfer function.

[0103] It should be noted that the initial transfer function refers to the ideal transfer function obtained by canceling and simplifying the similar terms of the third transfer function and the fourth transfer function; the detailed transfer function refers to the transfer function obtained by considering the discreteness of the data of the actual new energy grid-connected system and the actual influence of the converter on the new energy grid-connected system after substituting the first transfer function and the second transfer function into the initial transfer function; and the target transfer function refers to the most simplified transfer function obtained by canceling and simplifying the similar terms of the detailed transfer function.

[0104] In the embodiments of the present application, the third transfer function and the fourth transfer function are equivalently simplified to obtain an initial transfer function, then the first transfer function and the second transfer function are substituted into the initial transfer function to obtain a detailed transfer function, and finally the detailed transfer function is equivalently simplified to obtain the target transfer function, which can improve the accuracy of the identification result and reduce the complexity.

[0105] It can be understood that the accuracy of the identification result is improved: by considering the transfer functions of the zero-order holder (reflecting the discreteness of the actual system) and the PWM controller (reflecting the influence of the converter on the system), the simplified new energy grid-connected system model is closer to the actual situation, which helps to improve the accuracy of the identification result and better reflect the dynamic behavior of the new energy unit in the power grid; the complexity is reduced: by mutual cancellation and simplification of the like terms of the initial transfer function, and further simplification of the detailed transfer function, the most simplified target transfer function is obtained, which reduces the complexity and makes the subsequent control parameter identification more efficient and accurate.

[0106] In a feasible implementation manner, the third transfer function and the fourth transfer function in the above embodiments are as follows:

[0107] In the case of i taking q, the third transfer function is:

[0108] In the case of i taking d, the third transfer function is:

[0109] In the case of i taking q, the fourth transfer function is:

[0110] In the case of i taking d, the fourth transfer function is:

[0111] wherein, is a voltage reference value of the q-axis component of the current inner loop control link, is a current reference value of the q-axis component of the current inner loop control link, i g,q is a current feedback value of the q-axis component of the current inner loop control link, K p,q is a proportional coefficient of the PI controller of the q-axis component of the current inner loop control link, τ i,q is an integral time constant of the PI controller of the q-axis component of the current inner loop control link, s is a Laplace operator, i g,d is a current feedback value of the d-axis component of the current inner loop control link, ω1 is a synchronous angular frequency of the power grid in the new energy grid-connected system, L g is a connection inductance of the converter in the new energy grid-connected system, is a voltage reference value of the d-axis component of the current inner loop control link, is a current reference value of a d-axis component of a current inner loop control link, K p,d is a proportional coefficient of a PI controller of a d-axis component of a current inner loop control link, τ i,d is an integral time constant of a PI controller of a d-axis component of a current inner loop control link, u g,d is a voltage feedback value of a d-axis component of a current inner loop control link, R g is a connection resistance of a converter in a new energy grid-connected system.

[0112] It should be noted that, is an output value of a transfer function of a PI controller of a q-axis component of a current inner loop control link, is an output value of a transfer function of a PI controller of a d-axis component of a current inner loop control link.

[0113] For the convenience of intuitive understanding of the control strategy of the third transfer function of the current inner loop control link and the fourth transfer function of the main circuit control link in the new energy grid-connected system, the application provides a schematic diagram of the third transfer function of the current inner loop control link and the fourth transfer function of the main circuit control link. Please refer to Figure 2 , which is a schematic diagram of the third transfer function of the current inner loop control link and the fourth transfer function of the main circuit control link in the embodiment of the application.

[0114] It should be noted that, from Figure 2 The schematic diagram shown can be known that i g,q is a current feedback value of a q-axis component of a current inner loop control link, and also an output current value of a q-axis component of a converter of a main circuit control link; i g,d is a current feedback value of a d-axis component of a current inner loop control link, and also an output current value of a d-axis component of a converter of a main circuit control link.

[0115] Further, similarly, u g,d is a voltage feedback value of a d-axis component of a current inner loop control link, and also an output voltage value of a d-axis component of a converter of a main circuit control link.

[0116] In the embodiment of the application, the third transfer function of the current inner loop control link and the fourth transfer function of the main circuit control link are provided from the mathematical point of view. The accuracy of the third transfer function and the fourth transfer function can be ensured from the mathematical logic rigor, and the above-mentioned transfer functions are preferably shown in order to provide a reference for technicians and understanding, etc., so as to simplify the new energy grid-connected system.

[0117] In a feasible implementation manner, the initial transfer function in the above-mentioned embodiment is as follows:

[0118] In the case of i taking q, the initial transfer function is:

[0119] In the case of i taking d, the initial transfer function is:

[0120] Wherein, i g,q is the current feedback value of the q-axis component of the current inner loop control link, is the current reference value of the q-axis component of the current inner loop control link, K p,q is the proportional coefficient of the PI controller of the q-axis component of the current inner loop control link, τ i,q is the integral time constant of the PI controller of the q-axis component of the current inner loop control link, s is the Laplace operator, L g is the connection inductance of the converter in the new energy grid-connected system, R g is the connection resistance of the converter in the new energy grid-connected system, i g,d is the current feedback value of the d-axis component of the current inner loop control link, is the current reference value of the d-axis component of the current inner loop control link, K p,d is the proportional coefficient of the PI controller of the d-axis component of the current inner loop control link, τ i,d is the integral time constant of the PI controller of the d-axis component of the current inner loop control link.

[0121] For example, in order to intuitively understand that the same terms of the third transfer function of the current inner loop control link and the fourth transfer function of the main circuit control link in the new energy grid-connected system are offset to each other, and the control strategy of the initial transfer function in the ideal case is obtained after simplification, the application provides a schematic diagram of the initial transfer function of the current inner loop control link and the main circuit control link. Please refer to Figure 3 , which is a schematic diagram of the initial transfer function of the current inner loop control link and the main circuit control link in the embodiment of the application.

[0122] It should be noted that from Figure 3 the schematic diagram shown, it can be understood that the initial transfer function is the control strategy of the new energy grid-connected system in the ideal case.

[0123] In the embodiment of the application, the initial transfer function of the current inner loop control link and the main circuit control link is provided from the mathematical point of view. The accuracy of the initial transfer function can be ensured from the rigor of the mathematical logic, and the above-mentioned transfer function is preferably shown in order to provide reference, understanding, etc. for the technical personnel, so as to simplify the new energy grid-connected system.

[0124] In a feasible implementation manner, the first transfer function and the second transfer function in the above-mentioned embodiment are as follows:

[0125] The first transfer function is:

[0126] The second transfer function is:

[0127] wherein,

[0128] wherein, ZOH(s) is the output value of the zero-order holder, e is a natural constant, T s is the delay time of the PWM controller, s is the Laplace operator, W(s) is the output value of the PWM controller, K PWM is the amplification coefficient of the PWM controller, U dc,ins is the DC voltage instantaneous value of the converter in the new energy grid-connected system, U sp is the sawtooth wave peak value of the PWM controller.

[0129] In the embodiments of the present application, the first transfer function of the zero-order holder and the second transfer function of the PWM controller are provided from the mathematical point of view, and the accuracy of the first transfer function and the second transfer function can be ensured from the mathematical logic rigor, and the above-mentioned transfer functions are preferably shown, so as to provide a reference for technicians, understand, etc., so as to simplify the new energy grid-connected system.

[0130] In a feasible implementation manner, the detailed transfer functions in the above-mentioned embodiments are as follows:

[0131] In the case of i taking q, the detailed transfer function is:

[0132] In the case of i taking d, the detailed transfer function is:

[0133] wherein, i g,q is the current feedback value of the q-axis component of the current inner loop control link, is the current reference value of the q-axis component of the current inner loop control link, K p,q is the proportional coefficient of the PI controller of the q-axis component of the current inner loop control link, τ i,q is the integral time constant of the PI controller of the q-axis component of the current inner loop control link, s is the Laplace operator, T s is the delay time of the PWM controller, K PWM is the amplification coefficient of the PWM controller, L g is the connection inductance of the converter in the new energy grid-connected system, R g is the connection resistance of the converter in the new energy grid-connected system, i g,da current feedback value of a d-axis component of a current inner loop control link, a current reference value of a d-axis component of a current inner loop control link, K p,d a proportional coefficient of a PI controller of a d-axis component of a current inner loop control link, τ i,d an integral time constant of a PI controller of a d-axis component of a current inner loop control link.

[0134] For example, in order to intuitively understand the first transfer function of the zero-order holder and the second transfer function of the PWM controller in the new energy grid-connected system, and the detailed transfer function control strategy after the initial transfer function is substituted, that is, considering the discreteness of the actual data of the new energy grid-connected system, and considering the detailed transfer function of the actual influence of the converter on the new energy grid-connected system, the application provides a detailed transfer function schematic diagram of the current inner loop control link and the main circuit control link. Please refer to Figure 4 , which is a detailed transfer function schematic diagram of the current inner loop control link and the main circuit control link in the embodiment of the application.

[0135] It should be noted that, from Figure 4 The schematic diagram shown can be known that the detailed transfer function belongs to the control strategy considering the discreteness of the actual data of the new energy grid-connected system, and considering the influence of the converter on the new energy grid-connected system.

[0136] In the embodiment of the application, the rigorous detailed transfer function of the current inner loop control link and the main circuit control link is provided from the mathematical point of view. The accuracy of the detailed transfer function can be ensured from the rigor of the mathematical logic, and the above-mentioned transfer function is preferably shown in order to provide reference, understanding, etc. for the technical personnel, so as to simplify the new energy grid-connected system.

[0137] In a feasible implementation manner, the detailed transfer function in the above-mentioned embodiment is

[0138] The target transfer function in the above-mentioned embodiment is as follows:

[0139] In the case of i taking q, the target transfer function is:

[0140] In the case of i taking d, the target transfer function is:

[0141] Wherein, τ i,q an integral time constant of a PI controller of a q-axis component of a current inner loop control link, s is a Laplace operator, τ i,d an integral time constant of a PI controller of a d-axis component of a current inner loop control link, L gR is the connection inductance of the converter in a new energy grid-connected system. g i is the connection resistance of the converter in a new energy grid-connected system. g,q This represents the current feedback value of the q-axis component of the current inner loop control loop. K is the current reference value for the q-axis component of the current inner loop control loop. p,q K is the proportional coefficient of the PI controller for the q-axis component of the current inner loop control loop. PWM L is the amplification factor of the PWM controller. g T is the connection inductance of the converter in a new energy grid-connected system. s For the delay time of the PWM controller, i g,d This represents the current feedback value of the d-axis component of the current inner loop control loop. K is the current reference value for the d-axis component of the current inner loop control loop. p,d This is the proportional coefficient of the PI controller for the d-axis component of the current inner loop control loop.

[0142] It should be noted that, in this application, in addition to including like terms τ i,q s+1 and τ i,q s+1 and They cancel each other out, and like terms τ i,q s and τ i,d s all with They cancel each other out, and their delays are also added together based on their respective delay times. and T s The two are equivalent to s+1

[0143] For example, to facilitate a clear understanding of the control strategy for canceling out similar terms in the detailed transfer functions of the current inner loop control and main circuit control in a new energy grid-connected system, and to simplify the control strategy to obtain the most simplified target transfer function, this application provides a schematic diagram of the target transfer functions of the current inner loop control and main circuit control. Please refer to [link / reference]. Figure 5 This is a schematic diagram of the target transfer function of the current inner loop control loop and the main circuit control loop in the embodiments of this application.

[0144] It should be noted that, from Figure 5 As shown in the schematic diagram, the target transfer function is the simplest control strategy for new energy grid-connected systems.

[0145] In this application embodiment, a rigorous target transfer function for the current inner loop control link and the main circuit control link is provided from a mathematical perspective. The rigor of the mathematical logic can ensure the accuracy of the target transfer function. Furthermore, by showing the above-mentioned transfer function in a preferred manner, it is convenient to provide technical personnel with reference and understanding, thereby simplifying the new energy grid connection system.

[0146] In addition, the identification of the control parameters of the simplified new energy grid-connected system can make the identification of the control parameters more efficient and accurate.

[0147] In a possible implementation, the step 120 in the above embodiment, determining the control parameter of the q-axis component of the current inner loop control link according to the first response curve, includes: determining a first overshoot according to the first response curve; determining a first damping ratio value according to the first overshoot; and determining the control parameter of the q-axis component of the current inner loop control link according to the first damping ratio value.

[0148] The step 130 in the above embodiment, determining the control parameter of the d-axis component of the current inner loop control link according to the second response curve, includes: determining a second overshoot according to the second response curve; determining a second damping ratio value according to the second overshoot; and determining the control parameter of the d-axis component of the current inner loop control link according to the second damping ratio value.

[0149] For the determination of the damping ratio value according to the overshoot, in some embodiments, the formula may be used to determine the damping ratio value; wherein M p,1,q,or,2,d is the first overshoot or the second overshoot, e is a natural constant, π is a circular constant, and ξ 1,q,or,2,d is the first damping ratio value or the second damping ratio value.

[0150] In the embodiments of the present application, by determining the overshoot according to the response curve, then determining the damping ratio value according to the overshoot, and finally determining the control parameter of the current inner loop control link according to the damping ratio value, the accuracy of the identification of the control parameter can be improved, the system performance can be optimized, the identification process can be simplified, the robustness of the system can be improved, and the development of the new energy grid-connected technology can be promoted.

[0151] It can be understood that the accuracy of control parameter identification is improved: by determining the overshoot according to the response curve (i.e. the step response curve), the damping ratio value is determined, and then the control parameters are determined, which is more intuitive and accurate than the traditional theoretical calculation or empirical estimation method, which fully considers the dynamic characteristics of the actual system, so that the identified control parameters are more in line with the actual situation; optimizing system performance: the current inner loop control link is an important part of the new energy grid-connected converter, and its performance directly affects the stability and dynamic response of the entire system. By accurately identifying the control parameters of the q-axis and d-axis components, the control effect of the current inner loop can be optimized, the overshoot can be reduced, and the stability and response speed of the system can be improved; simplify the identification process: the traditional control parameter identification method often requires complex mathematical operations and model derivation, while the identification method based on the response curve is relatively simple and intuitive. It does not need to deeply understand the internal structure and mathematical model of the system, but only needs to observe and analyze the response curve to determine the control parameters, thereby simplifying the identification process; improve system robustness: in actual application, the new energy grid-connected system may face various complex working conditions and disturbances. By accurately identifying the control parameters of the current inner loop control link, the adaptability of the system to various working conditions and disturbances can be improved (note: the control parameter identification method of the present application does not need to perform disturbance tests on various working conditions, i.e. only one disturbance test is needed), and the robustness of the system is enhanced; promote the development of new energy grid-connected technology: accurate identification of the current inner loop control parameters is an important part of new energy grid-connected technology. By continuously optimizing the control parameters, the performance of the new energy grid-connected system can be improved, the operation and maintenance cost can be reduced, and the further development of new energy grid-connected technology can be promoted.

[0152] In a feasible implementation manner, the control parameter of the q-axis component of the current inner loop control link determined according to the first damping ratio value in the above embodiment includes:

[0153] The control parameter of the q-axis component of the current inner loop control link is determined by using the formula

[0154] The control parameter of the d-axis component of the current inner loop control link determined according to the second damping ratio value in the above embodiment includes:

[0155] The control parameter of the d-axis component of the current inner loop control link is determined by using the formula

[0156] Wherein,

[0157] Wherein, K p,q and K i,q are the control parameters of the q-axis component of the current inner loop control link, K p,q is the proportional coefficient of the PI controller of the q-axis component of the current inner loop control link, and K i,q ​​is an integral coefficient of a PI controller of a q-axis component of a current inner loop control link, L g is a connecting inductance of a converter in a new energy grid-connected system, K PWM is an amplification coefficient of a PWM controller, T s is a delay time of a PWM controller, ξ 1,q is a first damping ratio, τ i,q is an integral time constant of a PI controller of a q-axis component of a current inner loop control link, K p,d and K i,d is a control parameter of a d-axis component of a current inner loop control link, K p,d is a proportional coefficient of a PI controller of a d-axis component of a current inner loop control link, K i,d is an integral coefficient of a PI controller of a d-axis component of a current inner loop control link, ξ 2,d is a second damping ratio, τ i,d is an integral time constant of a PI controller of a d-axis component of a current inner loop control link, s is a Laplace operator, R g is a connecting resistance of a converter in a new energy grid-connected system.

[0158] In the embodiments of the present application, the calculation formula of the control parameter of the current inner loop control link is provided from the mathematical point of view, and the accuracy of the calculated control parameter of the current inner loop control link can be ensured from the mathematical logic rigor, and the calculation formula of the control parameter of the current inner loop control link is preferably shown, so as to provide reference, understanding and calculation for the technical personnel.

[0159] In a feasible implementation manner, the first overshoot is determined according to the first response curve in the above-mentioned embodiments, comprising: determining a steady-state current value and a first current peak value of the first response curve according to the first response curve; and determining the first overshoot according to the steady-state current value and the first current peak value of the first response curve.

[0160] The second overshoot is determined according to the second response curve in the above-mentioned embodiments, comprising: determining a steady-state current value and a first current peak value of the second response curve according to the second response curve; and determining the second overshoot according to the steady-state current value and the first current peak value of the second response curve.

[0161] For the determination manner of determining the overshoot according to the steady-state current value and the first current peak value of the response curve, in some embodiments, the overshoot can be determined by using the formula ; wherein, M p,1,q,or,2,d is the first overshoot or the second overshoot, I 2,1,q,or,2,d is the steady-state current value of the first response curve or the second response curve, I 3,1,q,or,2,d is the first current peak value of the first response curve or the second response curve.

[0162] For example, refer to Figure 6 For example, refer to 1,1,q,or,2,d I is an initial current value of the first response curve or the second response curve, 2,1,q,or,2,d I is a steady-state current value of the first response curve or the second response curve, 3,1,q,or,2,d I is a first current peak value of the first response curve or the second response curve, and t is time.

[0163] In the embodiments of the present application, the overshoot is determined according to the steady-state current value and the first current peak value of the response curve, and then the overshoot is determined according to the steady-state current value and the first current peak value of the response curve, which can intuitively and accurately calculate the overshoot, avoid complex mathematical calculation and derivation, and make the determination process of the overshoot more simple and efficient. Further, by accurately determining the overshoot, the dynamic performance of the system can be more accurately evaluated, and a basis is provided for subsequent control parameter identification.

[0164] In a feasible implementation, the fifth transfer function before the proportional integral term is removed in step 110 in the above embodiment is as follows:

[0165] In the case of i taking q, the fifth transfer function is:

[0166] In the case of i taking d, the fifth transfer function is:

[0167] The fifth transfer function after the proportional integral term is removed in step 110 in the above embodiment is as follows:

[0168] In the case of i taking q, the fifth transfer function is:

[0169] In the case of i taking d, the fifth transfer function is:

[0170] wherein, Q is a current reference value of a q-axis component of a current inner loop control link, * Q is a reactive power reference value of a q-axis component of a voltage outer loop control link, Q is a reactive power feedback value of a q-axis component of a voltage outer loop control link (also a reactive power value of a converter of a main circuit control link), K q K is a proportional coefficient of a PI controller of a q-axis component of a voltage outer loop control link, q τ is an integral time constant of a PI controller of a q-axis component of a voltage outer loop control link, and s is a Laplace operator, Q is a current reference value of a d-axis component of a current inner loop control link, U is a DC voltage reference value of the d-axis component of the voltage outer loop control link dc K is a DC voltage feedback value of the d-axis component of the voltage outer loop control link (also a DC side voltage value of the converter of the main circuit control link) d τ is a proportional coefficient of the PI controller of the d-axis component of the voltage outer loop control link d is an integral time constant of the PI controller of the d-axis component of the voltage outer loop control link.

[0171] It should be noted that, is an output value of the transfer function of the PI controller of the q-axis component of the voltage outer loop control link, is an output value of the transfer function of the PI controller of the d-axis component of the voltage outer loop control link.

[0172] In other embodiments, in the case of i taking q, the fifth transfer function is: That is, in the case where there is no proportional integral term in the fifth transfer function, the step 120 in the above embodiment can be modified to "make a step disturbance to the current reference value of the q-axis component of the current inner loop control link", and the rest remains unchanged.

[0173] For example, in order to intuitively understand the control strategy of the fifth transfer function of the voltage outer loop control link in the new energy grid-connected system before the proportional integral term is removed, the present application provides a schematic diagram of the fifth transfer function of the voltage outer loop control link before the proportional integral term is removed, please refer to Figure 7 , which is a schematic diagram of the fifth transfer function of the voltage outer loop control link before the proportional integral term is removed in the embodiment of the present application, and Figure 8 , which is another schematic diagram of the fifth transfer function of the voltage outer loop control link before the proportional integral term is removed in the embodiment of the present application.

[0174] For further example, in order to intuitively understand the control strategy of the fifth transfer function of the voltage outer loop control link in the new energy grid-connected system after the proportional integral term is removed, the present application provides a schematic diagram of the fifth transfer function of the voltage outer loop control link after the proportional integral term is removed, please refer to Figure 9 , which is a schematic diagram of the fifth transfer function of the voltage outer loop control link after the proportional integral term is removed in the embodiment of the present application, and Figure 10 , which is another schematic diagram of the fifth transfer function of the voltage outer loop control link after the proportional integral term is removed in the embodiment of the present application.

[0175] In the embodiment of the present application, the fifth transfer function before the proportional integral term of the voltage outer loop control link is removed and the fifth transfer function after the proportional integral term of the voltage outer loop control link is removed are provided from the mathematical point of view. The accuracy of the fifth transfer function can be ensured from the mathematical logic rigor, and the above-mentioned transfer functions are preferably shown in order to provide a reference for technicians to understand, etc., so as to utilize the simplified new energy grid-connected system to perform disturbance test, and then identify the current inner loop control parameters.

[0176] The present application provides a current inner loop control parameter identification device of a new energy grid-connected converter in the second aspect.

[0177] Please refer to Figure 11 The device 1110 includes the following in the embodiment of the present application, a current inner loop control parameter identification device of a new energy grid-connected converter:

[0178] The system adjustment module 1111 is configured to obtain a first transfer function of a zero-order holder, a second transfer function of a PWM controller, a third transfer function of an i-axis component of a current inner loop control link in the new energy grid-connected system, and a fourth transfer function of an i-axis component of a main circuit control link, and determine a target transfer function according to the first transfer function, the second transfer function, the third transfer function, and the fourth transfer function; replace the third transfer function and the fourth transfer function in the new energy grid-connected system with the target transfer function, and remove a proportional integral term of a fifth transfer function of an i-axis component of a voltage outer loop control link in the new energy grid-connected system; wherein i is q, d in turn, to obtain the new energy grid-connected system after replacement and removal;

[0179] The first identification module 1112 is configured to perform a step disturbance on a reactive power reference value of a q-axis component of the voltage outer loop control link in the new energy grid-connected system after replacement and removal, obtain a first response curve of a current feedback value of the q-axis component of the current inner loop control link in the new energy grid-connected system after replacement and removal, and determine a control parameter of the q-axis component of the current inner loop control link according to the first response curve.

[0180] The second identification module 1113 is configured to perform a step disturbance on a direct current voltage reference value of a d-axis component of the voltage outer loop control link in the new energy grid-connected system after replacement and removal, obtain a second response curve of a current feedback value of the d-axis component of the current inner loop control link in the new energy grid-connected system after replacement and removal, and determine a control parameter of the d-axis component of the current inner loop control link according to the second response curve.

[0181] In the embodiment of the present application, the related content of the above-mentioned system adjustment module 1111, the first identification module 1112, and the second identification module 1113 can be referred to Figure 1The content in the illustrated embodiment is not described here.

[0182] It should be noted that the device 1110 of the present application also includes some other modules, and it can be understood that the method of the present application has a one-to-one correspondence with the device 1110, so some other modules of the device 1110 of the present application are the corresponding content of the method of the present application in the above-mentioned embodiments.

[0183] In the embodiment of the present application, the target transfer function is determined according to the first transfer function of the zero-order holder and the second transfer function of the PWM controller, and the third transfer function of the current inner loop control link and the fourth transfer function of the main circuit control link, then the third transfer function and the fourth transfer function are replaced by the target transfer function, and the proportional integral term of the fifth transfer function of the voltage outer loop control link is removed, and finally the q-axis component reactive power reference value and the d-axis component DC voltage reference value of the voltage outer loop control link are subjected to step disturbance respectively, and the first response curve and the second response curve of the current feedback value of the q-axis component and the d-axis component of the current inner loop control link are obtained respectively, to determine the control parameters of the q-axis component and the d-axis component of the current inner loop control link; This method can effectively solve the technical problems existing in the prior art, and can effectively improve the accuracy and practicality of the identification result, and provide strong support for the electromagnetic transient modeling and grid connection research of new energy units.

[0184] The present application further provides a computer readable storage medium in the third aspect, which stores a computer program, and the computer program is executed by a processor to make the processor execute the current inner loop control parameter identification method of the new energy grid-connected converter in the above-mentioned method embodiment.

[0185] The present application further provides a computer device in the fourth aspect, which includes a memory and a processor, and the memory stores a computer program, and the computer program is executed by the processor to make the processor execute the current inner loop control parameter identification method of the new energy grid-connected converter in the above-mentioned method embodiment.

[0186] Figure 12 The internal structure diagram of the computer device in some embodiments is shown. The computer device can be a terminal, a server, or a gateway. As Figure 12 As shown, the computer device includes a processor, a memory and a network interface connected through a system bus.

[0187] The memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the computer device stores an operating system, and can also store a computer program. When the computer program is executed by the processor, the processor can implement each step in the above method embodiments. The internal memory can also store a computer program. When the computer program is executed by the processor, the processor can execute each step in the above method embodiments. Those skilled in the art can understand that Figure 12 The structure shown in the figure is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. A specific computer device can include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0188] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be completed by a computer program instructing related hardware. The program can be stored in a non-volatile computer readable storage medium. When the program is executed, it can include the processes of the above-mentioned embodiments.

[0189] Any reference to memory, storage, databases, or other media in the embodiments provided by the present application can include non-volatile and / or volatile storage. Non-volatile storage can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile storage can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synch Link) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0190] Each technical feature of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of each technical feature in the above embodiments are described. However, as long as the combination of these technical features does not exist, it should be considered as within the scope of the present application.

[0191] The above-described embodiments are merely illustrative of several embodiments of the present application, which are described in more detail and in a specific manner, but should not be construed as limiting the scope of the patent of the present application. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method for identifying the inner loop control parameters of a new energy grid-connected converter, characterized in that, The method includes: Obtain the first transfer function of the zero-order hold and the second transfer function of the PWM controller, as well as the third transfer function of the i-axis component of the current inner loop control loop and the fourth transfer function of the i-axis component of the main circuit control loop in the new energy grid-connected system. Determine the target transfer function based on the first, second, third, and fourth transfer functions. Replace the third and fourth transfer functions in the new energy grid-connected system with the target transfer function and remove the proportional-integral term of the fifth transfer function of the i-axis component of the voltage outer loop control loop in the new energy grid-connected system. Wherein, i takes the values ​​q and d in sequence, to obtain the new energy grid-connected system after replacement and removal. A step disturbance is made to the reactive power reference value of the q-axis component of the voltage outer loop control link in the replaced and removed new energy grid-connected system. The first response curve of the current feedback value of the q-axis component of the current inner loop control link in the replaced and removed new energy grid-connected system is obtained, and the control parameters of the q-axis component of the current inner loop control link are determined according to the first response curve. A step disturbance is made to the DC voltage reference value of the d-axis component of the voltage outer loop control link in the replaced and removed new energy grid-connected system, and a second response curve of the current feedback value of the d-axis component of the current inner loop control link in the replaced and removed new energy grid-connected system is obtained. The control parameters of the d-axis component of the current inner loop control link are determined according to the second response curve. When i takes the value q, the third transfer function is: ; When i takes the value d, the third transfer function is: ; When i takes the value q, the fourth transfer function is: ; When i takes the value d, the fourth transfer function is: ; in, This is the voltage reference value for the q-axis component of the current inner loop control loop. This is the current reference value for the q-axis component of the current inner loop control loop. This refers to the current feedback value of the q-axis component of the current inner loop control loop. This is the proportional coefficient of the PI controller for the q-axis component of the current inner loop control loop. Let be the integral time constant of the PI controller for the q-axis component of the current inner loop control loop. For the Laplace operator, This refers to the current feedback value of the d-axis component of the current inner loop control loop. The synchronous angular frequency of the power grid in the aforementioned new energy grid-connected system. The inductance is the connection inductance of the converter in the aforementioned new energy grid-connected system. This is the voltage reference value for the d-axis component of the current inner loop control loop. This is the current reference value for the d-axis component of the current inner loop control loop. This refers to the proportional coefficient of the PI controller for the d-axis component of the current inner loop control loop. Let be the integral time constant of the PI controller for the d-axis component of the current inner loop control loop. This is the voltage feedback value of the d-axis component of the current inner loop control loop. The connection resistance of the converter in the new energy grid-connected system; The first transfer function is: ; The second transfer function is: ; in, , ; in, This is the first transfer function. It is a natural constant. The delay time of the PWM controller, This is the second transfer function. The amplification factor of the PWM controller is... This refers to the instantaneous DC voltage value of the converter in the aforementioned new energy grid-connected system. The peak value of the sawtooth wave of the PWM controller; make , ; When i takes the value q, the target transfer function is: ; When i takes the value d, the target transfer function is: .

2. The method according to claim 1, characterized in that, Determining the target transfer function based on the first transfer function, the second transfer function, the third transfer function, and the fourth transfer function includes: The third and fourth transfer functions are simplified by equivalent means to obtain the initial transfer function; Substituting the first transfer function and the second transfer function into the initial transfer function yields the detailed transfer function; The target transfer function is obtained by performing an equivalent simplification on the detailed transfer function.

3. The method according to claim 2, characterized in that, When i is q, the initial transfer function is: ; When i is d, the initial transfer function is: .

4. The method according to claim 2, characterized in that, When i is q, the detailed transfer function is: ； When i takes the value d, the detailed transfer function is as follows: 。 5. The method according to claim 1, characterized in that, The step of determining the control parameters of the q-axis component of the current inner loop control element based on the first response curve includes: The first overshoot is determined based on the first response curve; The first damping ratio is determined based on the first overshoot. The control parameters of the q-axis component of the current inner loop control loop are determined based on the first damping ratio value. The step of determining the control parameters of the d-axis component of the current inner loop control element based on the second response curve includes: The second overshoot is determined based on the second response curve; The second damping ratio is determined based on the second overshoot. The control parameters of the d-axis component of the current inner loop control element are determined based on the second damping ratio.

6. The method according to claim 5, characterized in that, The step of determining the control parameters of the q-axis component of the current inner loop control element based on the first damping ratio includes: Using formula Determine the control parameters of the q-axis component of the current inner loop control loop; The step of determining the control parameters of the d-axis component of the current inner loop control element based on the second damping ratio includes: Using formula Determine the control parameters of the d-axis component of the current inner loop control loop; in, ; in, and These are the control parameters for the q-axis component of the current inner loop control loop. The integral coefficient of the PI controller for the q-axis component of the current inner loop control loop is given. This is the first damping ratio value. and These are the control parameters for the d-axis component of the current inner loop control loop. The integral coefficient of the PI controller for the d-axis component of the current inner loop control loop is given. This is the second damping ratio.

7. The method according to claim 5, characterized in that, Determining the first overshoot based on the first response curve includes: The steady-state current value and the initial peak current value of the first response curve are determined based on the first response curve. The first overshoot is determined based on the steady-state current value and the initial peak current value of the first response curve; Determining the second overshoot based on the second response curve includes: The steady-state current value and the initial peak current value of the second response curve are determined based on the second response curve. The second overshoot is determined based on the steady-state current value and the initial current peak value of the second response curve.

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