Converter tracking-networking fusion phase angle control method and device

Abstract

The invention relates to the technical field of power systems, in particular to a control method and device for a tracking-networking fusion phase angle of a converter, and the method comprises the steps: respectively obtaining initial phase angles of a tracking control link and a networking control link in the tracking-networking fusion converter; determining an initial fusion coefficient according to the SCR and the system inertia of the power system accessed by the tracking-networking fusion converter; adjusting the initial fusion coefficient by using the direct current side current and the grid side current to obtain a final fusion coefficient; and calculating a fusion phase angle of the tracking-networking fusion converter according to the final fusion coefficient, the initial tracking phase angle and the initial networking phase angle. Therefore, the problems that in the related technology, only the influence of SCR is considered, the influence of the inertia of the connected system and the power amplitude limiting of the converter itself is not considered, the fusion coefficient cannot be adaptively adjusted under multiple working condition power grids, consequently, the supporting capacity of the power grids and the stability of the converter are poor, solving is complex, the response time is long, and the stability of the converter is poor are solved. And actual conditions such as different faults and current limiting cannot be adapted.

Description

Technical Field

[0001] The present application relates to the technical field of power systems, and in particular to a method and device for controlling a phase angle of a converter and a grid-connected fusion converter. Background Art

[0002] With the widespread access of new energy represented by wind power and photovoltaic power to the power grid, the new power system has gradually shown the dual-high characteristics of "high proportion of new energy and high proportion of power electronics". The low inertia and volatility of new energy make the problem of power grid stability increasingly serious. At present, new energy widely adopts grid-following control, which cannot independently build voltage and frequency, and is prone to oscillation, frequency instability and other problems in weak power grids. Grid-building control simulates the operating characteristics of synchronous generators, which has good stability in weak power grids, but may become unstable in strong power grids due to the parallel connection of voltage sources.

[0003] In the related technology, the grid-following frequency deviation and the grid-forming frequency deviation can be calculated by collecting the grid-connected point voltage, current and DC bus voltage, and the virtual phase angle can be obtained by combining the preset frequency reference value to solve the parameter values ​​such as the grid-connected point voltage d-axis component and q-axis component, and then the grid-connected point current d-axis and q-axis component reference values ​​are generated using the grid-connected point voltage d-axis component and other parameters; the current operating mode of the target converter can also be detected based on the frequency unlimited range and the current unlimited range, and then different judgment strategies are entered according to the current operating mode of the target converter.

[0004] However, in the related technology, only the influence of SCR (Short Circuit Ratio) is considered, and the influence of the inertia of the connected system and the power limitation of the converter itself is not considered. It is impossible to adaptively adjust the fusion coefficient under various working conditions of the power grid, resulting in poor support capacity of the power grid and stability of the converter. The solution is complex and the response time is long. It cannot adapt to different faults, current limiting and other actual situations, and it is in urgent need of improvement. Summary of the invention

[0005] The present application provides a control method and device for the phase angle of the inverter-grid fusion, so as to solve the problems in the related technology that only the influence of SCR is considered, and the influence of the inertia of the connected system and the power limitation of the inverter itself are not considered, and the fusion coefficient cannot be adaptively adjusted under various working conditions of the power grid, resulting in poor support capacity of the power grid and stability of the inverter, and the solution is complex, the response time is long, and it is impossible to adapt to different faults, current limiting and other actual situations.

[0006] The first aspect of the present application provides a method for controlling the phase angle of a follow-grid fusion of a converter, comprising the following steps: obtaining an initial follow-grid phase angle of a follow-grid control link and an initial grid-forming phase angle of a grid-forming control link in a follow-grid fusion converter; determining an initial fusion coefficient of the follow-grid fusion converter control according to the SCR and system inertia of the follow-grid fusion converter connected to the power system; adjusting the initial fusion coefficient using the DC side current and the grid side current to obtain a final fusion coefficient of the follow-grid fusion converter control; and calculating the fusion phase angle of the follow-grid fusion converter according to the final fusion coefficient, the initial follow-grid phase angle and the initial grid-forming phase angle.

[0007] Optionally, in one embodiment of the present application, determining the initial fusion coefficient of the control of the grid-connected fusion converter based on the SCR and system inertia of the grid-connected fusion converter connected to the power system includes: obtaining a first fusion coefficient of the control of the grid-connected fusion converter based on the SCR; obtaining a second fusion coefficient of the control of the grid-connected fusion converter based on the system inertia; and obtaining the initial fusion coefficient based on the first fusion coefficient and the second fusion coefficient.

[0008] Optionally, in one embodiment of the present application, before adjusting the initial fusion coefficient using the DC side current and the grid side current, it also includes: calculating the DC side current based on the DC current reference value of the root-grid fusion converter; obtaining the grid-side d-axis current reference value and q-axis current reference value of the root-grid fusion converter; and calculating the grid-side current based on the d-axis current reference value and the q-axis current reference value.

[0009] Optionally, in one embodiment of the present application, the calculation formula of the final fusion coefficient may be but is not limited to:

[0010]

[0011] in, is the d-axis and q-axis current i of the grid-side converter d 、i q With the DC side current i dc The arithmetic mean of SCR is the short circuit ratio, H sys is the system inertia, and a is the current adjustment coefficient.

[0012] Optionally, in one embodiment of the present application, the calculation formula of the fusion phase angle may be but is not limited to:

[0013] θ Hyb =k Hyb θ ref +(1-k Hyb )θ pll ,

[0014] Among them, θ pll is the grid-following phase angle of the converter grid-following control, θ ref It is the grid phase angle of the converter grid control.

[0015] The second aspect of the present application provides a control device for the phase angle of the following-grid fusion of the converter, including: a first acquisition module, used to obtain the initial following-grid phase angle of the following-grid control link and the initial grid-forming phase angle of the grid-forming control link in the following-grid fusion converter; a determination module, used to determine the initial fusion coefficient of the following-grid fusion converter control according to the SCR and system inertia of the following-grid fusion converter connected to the power system; a generation module, used to adjust the initial fusion coefficient using the DC side current and the grid side current to obtain the final fusion coefficient of the following-grid fusion converter control; a first calculation module, used to calculate the fusion phase angle of the following-grid fusion converter according to the final fusion coefficient, the initial following-grid phase angle and the initial grid-forming phase angle.

[0016] Optionally, in one embodiment of the present application, the determination module includes: a first determination unit, used to obtain a first fusion coefficient of the follow-up-grid fusion converter control based on the SCR; a second determination unit, used to obtain a second fusion coefficient of the follow-up-grid fusion converter control based on the system inertia; and a generation unit, used to obtain the initial fusion coefficient based on the first fusion coefficient and the second fusion coefficient.

[0017] Optionally, in one embodiment of the present application, it also includes: a second calculation module, used to calculate the DC side current based on the DC current reference value of the root-grid fusion converter before adjusting the initial fusion coefficient using the DC side current and the grid side current; a second acquisition module, used to obtain the grid-side d-axis current reference value and q-axis current reference value of the root-grid fusion converter; a third calculation module, used to calculate the grid-side current based on the d-axis current reference value and the q-axis current reference value.

[0018] Optionally, in one embodiment of the present application, the calculation formula of the final fusion coefficient may be but is not limited to:

[0019]

[0020] in, is the d-axis and q-axis current i of the grid-side converter d 、i q With the DC side current i dc The arithmetic mean of SCR is the short circuit ratio, H sys is the system inertia, and a is the current adjustment coefficient.

[0021] Optionally, in one embodiment of the present application, the calculation formula of the fusion phase angle may be but is not limited to:

[0022] θ Hyb =k Hyb θ ref +(1-k Hyb )θ pll ,

[0023] Among them, θ pll is the grid-following phase angle of the converter grid-following control, θ ref It is the grid phase angle of the converter grid control.

[0024] The third aspect of the present application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for controlling the phase angle of the converter and the grid fusion as described in the above embodiment.

[0025] The fourth aspect of the present application provides a computer-readable storage medium, which stores a computer program. When the program is executed by a processor, it implements the above-mentioned method for controlling the phase angle of the converter-grid fusion.

[0026] The fifth aspect of the present application provides a computer program product, including a computer program, which, when executed, implements the above-mentioned method for controlling the phase angle of the converter and the grid fusion.

[0027] The embodiment of the present application can obtain the initial grid-following phase angle of the grid-following control and the initial grid-forming phase angle of the grid-forming control in the following-grid fusion converter, and determine the initial fusion coefficient according to the SCR and the system inertia, and then adjust the initial fusion coefficient using the DC side current and the grid side current to obtain the final fusion coefficient, so as to calculate the fusion phase angle of the following-grid fusion converter according to the final fusion coefficient, the initial grid-following phase angle and the initial grid-forming phase angle, comprehensively consider the influence of the SCR and the system inertia, and can adaptively adjust the fusion coefficient under various working conditions of the power grid to ensure the supporting capacity of the power system and the stability of the converter, and by adding the grid-side converter and the DC side current limiting conditions into the fusion coefficient for adjustment, the fusion coefficient can be optimized for different faults and current limiting conditions, the solution speed is faster, the process is simpler, and it can adapt to different faults, current limiting and other actual conditions. This solves the problem that in the related technology, only the influence of SCR is considered, but the influence of the inertia of the connected system and the power limitation of the converter itself are not considered, and the fusion coefficient cannot be adaptively adjusted under various working conditions of the power grid, resulting in poor support capacity of the power grid and stability of the converter, complex solution, long response time, and inability to adapt to different faults, current limiting and other actual situations.

[0028] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0030] Figure 1 A flow chart of a method for controlling a phase angle of a converter and a grid-connected grid according to an embodiment of the present application;

[0031] Figure 2 A schematic diagram of a converter-grid fusion phase angle control according to an embodiment of the present application;

[0032] Figure 3 A schematic block diagram of a one-dimensional correspondence between an SCR and a first fusion coefficient provided according to an embodiment of the present application;

[0033] Figure 4 A schematic block diagram of a one-dimensional correspondence between system inertia and a second fusion coefficient according to an embodiment of the present application;

[0034] Figure 5 A block diagram of a two-dimensional correspondence between an SCR, a system inertia and an initial fusion coefficient provided according to an embodiment of the present application;

[0035] Figure 6 A flowchart of the working principle of a method for controlling a phase angle of a converter and a grid-connected grid according to an embodiment of the present application;

[0036] Figure 7 It is a block diagram of a control device for a converter-grid fusion phase angle provided according to an embodiment of the present application;

[0037] Figure 8 It is a schematic diagram of the structure of an electronic device provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0038] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0039] The following describes the control method and device of the inverter follow-grid fusion phase angle of the embodiment of the present application with reference to the accompanying drawings. In view of the above-mentioned background technology that only considers the influence of SCR, but does not consider the influence of the inertia of the connected system and the power limitation of the inverter itself, and cannot adaptively adjust the fusion coefficient under various working conditions of the power grid, resulting in poor support capacity of the power grid and stability of the inverter, and the solution is complex, the response time is long, and it cannot adapt to different faults, current limiting and other actual situations. The present application provides a control method of the inverter follow-grid fusion phase angle. In this method, the initial follow-grid phase angle of the follow-grid control and the initial grid phase angle of the grid control in the follow-grid fusion inverter can be obtained, and the initial fusion coefficient can be determined according to the SCR and the system inertia, so as to utilize The initial fusion coefficient is adjusted by the DC side current and the grid side current to obtain the final fusion coefficient, so as to calculate the fusion phase angle of the grid-forming fusion converter according to the final fusion coefficient, the initial grid-forming phase angle and the initial grid-forming phase angle, comprehensively considering the influence of SCR and system inertia, and being able to adaptively adjust the fusion coefficient under various working conditions of the power grid to ensure the support capacity of the power system and the stability of the converter, and by adding the grid-side converter and the DC side current limiting conditions into the fusion coefficient for adjustment, the fusion coefficient can be optimized for different faults and current limiting conditions, with faster solution speed and simpler process, and can adapt to different faults, current limiting and other actual conditions. Thus, the problem that only the influence of SCR is considered in the related technology, and the influence of the connected system inertia and the converter's own power limiting is not considered, and the fusion coefficient cannot be adaptively adjusted under various working conditions of the power grid, resulting in poor support capacity of the power grid and converter stability, and complex solution, long response time, and inability to adapt to different faults, current limiting and other actual conditions is solved.

[0040] Specifically, Figure 1 The present invention is a flowchart of a method for controlling a phase angle of a converter and a grid-connected fusion converter according to an embodiment of the present application.

[0041] like Figure 1 As shown, the control method of the converter-grid fusion phase angle includes the following steps:

[0042] In step S101, an initial grid-following phase angle of a grid-following control link and an initial grid-forming phase angle of a grid-forming control link in a grid-following-forming fusion converter are obtained.

[0043] Among them, in the embodiments of the present application, the following-grid-building integrated converter can be understood as a structure in which the converter is connected to the power grid system, including the following-grid control link and the building-grid control link, and the present application does not make any specific restrictions.

[0044] In some embodiments, the initial grid-following phase angle of the grid-following control in the grid-following fusion converter of the embodiment of the present application can be determined by a phase-locked loop, and its calculation formula can be but is not limited to expressed as:

[0045]

[0046] Among them, θ g is the phase angle of the power system to which the converter is connected, G pll (s) is the phase-locked loop transfer function, k ppll , k ipll are the proportional and integral parameters of the phase-locked loop respectively, and s is the complex frequency.

[0047] In some embodiments, the embodiments of the present application do not rely on a phase-locked loop to measure the grid phase angle for the grid-forming control in the grid-forming fusion converter, but autonomously construct the phase angle and frequency like a synchronous generator. Taking virtual synchronous machine control as an example, which simulates the second-order rotor motion equation of the synchronous machine, the initial grid-forming phase angle of the grid-forming control in the grid-forming fusion converter can be, but is not limited to, expressed as:

[0048]

[0049] Among them, T J and D p is the virtual inertia and damping coefficient, P ref , P e To build a network to control the active power reference value and the actual value of active power, ω ref and ω0 are the electrical angular frequency of network control and the rated electrical angular frequency.

[0050] For example, the embodiments of the present application may be Figure 2 The initial grid-following phase angle θ of the grid-following control in the grid-following fusion converter is obtained from the control diagram shown in the figure. pll and the initial network phase angle θ of network control ref .

[0051] In step S102, an initial fusion coefficient of the grid-connected fusion converter control is determined according to the SCR of the grid-connected fusion converter connected to the power system and the system inertia.

[0052] As a possible implementation method, the embodiment of the present application can use SCR and system inertia to comprehensively determine the initial fusion coefficient.

[0053] Optionally, in one embodiment of the present application, before adjusting the initial fusion coefficient using the DC side current and the grid side current, it also includes: calculating the DC side current based on the DC current reference value of the follow-grid fusion converter; obtaining the grid side d-axis current reference value and q-axis current reference value of the follow-grid fusion converter; and calculating the grid side current based on the d-axis current reference value and the q-axis current reference value.

[0054] In the actual implementation process, before using the DC side current and the grid side current to adjust the initial fusion coefficient, the embodiment of the present application may also analyze the DC side current and the grid side current, and the main contents may include:

[0055] In the embodiment of the present application, on the DC side of the grid-connected fusion converter, the DC side current can be obtained according to the DC capacitor voltage-active power relationship, wherein the relationship satisfied by the DC side current can be, but is not limited to, expressed as:

[0056]

[0057] Among them, C dc is the DC side capacitance, U dc is the DC voltage value, i dc is the DC side current value, i d is the grid-side d-axis current value, k loss is the DC loss factor.

[0058] Furthermore, the embodiments of the present application are for i dc , its DC current reference value i dcref It can be expressed as, but not limited to:

[0059]

[0060] Among them, k dc is the DC voltage regulation coefficient, U dcref is the DC voltage reference value, P Tref , P T They are the reference value and actual value of the voltage power of the DC capacitor supported by the machine side, representing the active power supporting capability of the energy source side of the converter.

[0061] In addition, it should be noted that the embodiment of the present application is for the DC side current i dc , which is not always equal to its reference value i dcref Since the power support capacity of the energy source side of the grid-connected fusion converter is not unlimited, when its power output reaches the limit, i dc will be saturated and no longer affected by dcref Therefore, in the per-unit system, the embodiment of the present application can dc The saturation value is set to 1. At this time, i dc with i dcref The relationship can be expressed as, but not limited to:

[0062]

[0063] Among them, T d is the saturation delay.

[0064] In the embodiment of the present application, at the grid side of the grid-connected integrated converter, for the grid side d-axis current i d , q-axis current i q Since the overcurrent capacity of the converter is not infinite, it is related to the grid-side current reference value i dref , q-axis current reference value i qref The relationship can be expressed as, but not limited to:

[0065]

[0066] For example, the embodiments of the present application may be Figure 2 The DC side current i is obtained from the control diagram shown in dc , grid-side d-axis current i d , q-axis current i q .

[0067] Optionally, in one embodiment of the present application, the initial fusion coefficient of the control of the grid-connected fusion converter is determined according to the SCR and system inertia of the grid-connected fusion converter connected to the power system, including: obtaining a first fusion coefficient of the grid-connected fusion converter control based on the SCR; obtaining a second fusion coefficient of the grid-connected fusion converter control based on the system inertia; and obtaining an initial fusion coefficient based on the first fusion coefficient and the second fusion coefficient.

[0068] In some embodiments, the SCR of the embodiment of the present application is used as a characterization index of the voltage strength at the grid connection point. The impedances of each branch can be connected in series and in parallel. At the grid connection point, the system connected to the grid-connected fusion converter is equivalent to a single-machine system, and then the SCR is obtained. The expression can be, but is not limited to, expressed as:

[0069]

[0070] Among them, U g is the equivalent system voltage, I g is the current delivered by the converter to the equivalent system in steady state, z g It should be noted that, in the embodiment of the present application, each variable is assumed to be the result in the per-unit system, so in the steady state, SCR can be approximately simplified to Y g , that is, the equivalent admittance between the converter and the connected system.

[0071] In addition, in the embodiments of the present application, formula (7) may also be expressed in other ways, which may be specifically configured by technicians in this field according to actual conditions, and the present application does not impose any specific limitations.

[0072] Furthermore, the embodiment of the present application can obtain a first fusion coefficient based on the measured SCR and a quasi-saturation function expression, wherein the first fusion coefficient k isHyb The one-dimensional correspondence with SCR can be expressed as but not limited to:

[0073]

[0074] Among them, e is a natural constant.

[0075] It can be seen from formula (8) that in the embodiment of the present application, under different system strengths, the fusion control phase angle θ Hyb Different composition changes occur. That is, when the SCR is low, the system is weaker and k Hyb is larger and closer to 1, then θ Hyb The phase angle θ is mainly controlled by the network ref On the contrary, when SCR is higher, the system is stronger, k Hyb Close to 0, the converter shows a grid-following characteristic. Specifically, the schematic diagram of the one-dimensional correspondence between the SCR and the first fusion coefficient in the embodiment of the present application is as follows: Figure 3 shown.

[0076] In some embodiments, the present application embodiment is for the system inertia H sys , which is closely related to the active power fluctuation and frequency change rate of the power grid. In order to realize the simplified engineering detection of inertia, its calculation formula can be expressed as but not limited to:

[0077]

[0078] Among them, ΔP m is the mechanical power change of the synchronous machine after the disturbance, ΔP e is the change of electromagnetic power such as disturbance, Δf is the change of system frequency, and Δt is the inertia calculation time window.

[0079] It can be seen from formula (9) that H in the embodiment of the present application sys It can be calculated by dividing the power change by the frequency change rate. Since the short-term mechanical power change is small, ΔP can be ignored. m To simplify the calculation.

[0080] In addition, in the embodiments of the present application, formula (9) may also be expressed in other ways, which may be specifically configured by technicians in this field according to actual conditions, and the present application does not impose any specific limitations.

[0081] Furthermore, in parallel with the short-circuit ratio, the embodiment of the present application obtains a second fusion coefficient based on the measured system inertia value and a quasi-saturation function expression, wherein the second fusion coefficient k Hyb The one-dimensional correspondence with the system inertia can be expressed as, but not limited to:

[0082]

[0083] It can be seen from formula (10) that in the embodiment of the present application, when H sys When it is low, the frequency stability is weak and inertial support is urgently needed. Hyb is larger and closer to 1, then θ Hyb The phase angle θ is mainly controlled by the network ref decision, and appears to be closer to the grid-connected converter. sys When it is higher, the system frequency is more robust. To avoid power interaction between the converter and the grid, k Hyb Close to 0, the converter shows a grid-following characteristic. Specifically, the schematic diagram of the one-dimensional correspondence between the system inertia and the second fusion coefficient in the embodiment of the present application is as follows: Figure 4 shown.

[0084] In some embodiments, the embodiment of the present application comprehensively considers the influence of SCR and system inertia, takes the arithmetic mean of the results obtained by equation (8) and equation (10), and obtains the initial fusion coefficient, where the initial fusion coefficient k Hyb The calculation formula can be expressed as but not limited to:

[0085]

[0086] It can be seen from formula (11) that in the embodiment of the present application, the SCR and H sys are very small, the grid has both low inertia and low voltage strength, k Hyb Directly approach 1 to reflect the network characteristics, and the arithmetic mean can make k Hyb On the contrary, when SCR and H sys When both are large, k Hyb For the intermediate state, if the SCR is small but the inertia is large or the SCR is large but the inertia is small, although this situation is not common in the existing power grid, k Hyb The intermediate value can still be obtained to meet the needs of the power grid, and because of the arithmetic mean, the result is generally inclined to form a network to provide more effective frequency and voltage active support. Specifically, the embodiment of the present application comprehensively considers SCR and system inertia, and the obtained two-dimensional corresponding relationship diagram of SCR, system inertia and initial fusion coefficient is as follows Figure 5 shown.

[0087] In step S103, the initial fusion coefficient is adjusted using the DC side current and the grid side current to obtain the final fusion coefficient of the grid-connected fusion converter control. The calculation formula of the final fusion coefficient can be but is not limited to:

[0088]

[0089] in, is the d-axis and q-axis current i of the grid-side converter d 、i q With the DC side current i dc The arithmetic mean of SCR is the short circuit ratio, H sys is the system inertia, and a is the current adjustment coefficient.

[0090] It can be understood by those skilled in the art that the embodiments of the present application can further consider the influence of the DC side current and the grid side current on the basis of the initial fusion coefficient obtained by comprehensively considering the SCR and the system inertia. It can be understood that, in the embodiments of the present application, whether it is the case of grid-side converter current limiting or DC-side current limiting, the general network control cannot normally achieve its power support effect. On the contrary, since the network control independently determines its voltage and phase angle, its power is uncontrollable, which may lead to instability. Therefore, the embodiments of the present application can adjust the initial fusion coefficient according to the grid-side current and the DC side current, and then obtain the final fusion coefficient, and its calculation formula can be but is not limited to expressed as:

[0091]

[0092] in, is the d-axis and q-axis current i of the grid-side converter d 、i q With the DC side current i dc The arithmetic mean of SCR is the short circuit ratio, H sys is the system inertia, a is the current adjustment factor, which can be changed according to the fault type.

[0093] Furthermore, in the embodiments of the present application, The calculation formula can be expressed as but not limited to:

[0094]

[0095] According to equations (11) and (12), the coefficient term added in the embodiment of the present application represents the influence of the grid-side converter and the DC-side current on the final fusion coefficient. When it is less than 0.9, it is almost 0 and does not affect the results under normal conditions. When it is greater than 1.0, it is a, which plays the role of reducing the phase angle of network formation and increasing the phase angle of network following; i When it is 0.9 to 1, it increases linearly. For faults such as large frequency drops and large power demands, the power control is more important than the voltage source behavior, so a can take a larger value close to 1; for large voltage drops and short circuit faults, the voltage source behavior is more important than the precise control of the vector angle, so a can take a smaller value close to 0.

[0096] In step S104, the fusion phase angle of the following-grid fusion converter is calculated according to the final fusion coefficient, the initial following-grid phase angle and the initial grid-forming phase angle. The calculation formula of the fusion phase angle can be but is not limited to:

[0097] θ Hyb =k Hyb θ ref +(1-k Hyb )θ pll ,

[0098] Among them, θ pll is the grid-following phase angle of the converter grid-following control, θ ref It is the grid phase angle of the converter grid control.

[0099] As a possible implementation method, the embodiment of the present application can calculate the fusion phase angle of the following-grid fusion converter according to the final fusion coefficient, the initial following-grid phase angle and the initial grid-forming phase angle. It can be understood that the initial following-grid phase angle and the initial grid-forming phase angle of the embodiment of the present application can be comprehensively calculated by the final fusion coefficient, and then the fusion phase angle of the initial following-grid phase angle and the initial grid-forming phase angle is determined. Among them, the calculation formula of the fusion phase angle can be but is not limited to:

[0100] θ Hyb =k Hyb θ ref +(1-k Hyb )θ pll , (14)

[0101] Among them, θ pll is the grid-following phase angle of the converter grid-following control, θ ref It is the grid phase angle of the converter grid control.

[0102] The working principle of the method for controlling the phase angle of the converter and the grid-connected network proposed in the embodiment of the present application is described in detail below with reference to a specific embodiment.

[0103] in, Figure 6 The present invention is a flow chart showing the working principle of a method for controlling the phase angle of a converter and a grid-connected fusion converter according to an embodiment of the present application.

[0104] Step S601: Determine the initial phase angles of the grid-following control link and the grid-forming control link in the grid-following-forming fusion converter.

[0105] Among them, the embodiments of the present application can be combined with Figure 2 The initial grid-following phase angle θ of the grid-following control of the grid-following fusion converter can be obtained by using equations (1) and (2) respectively: pll and the initial network phase angle θ of network control ref .

[0106] Step S602: Measure the SCR and system inertia, and analyze the grid-side converter and DC-side current.

[0107] In this embodiment of the present application, the SCR can be obtained by using equation (7), and the system inertia can be obtained by using equation (9). Further, in this embodiment of the present application, equations (3) to (6) can be used in the following manner: Figure 2 The DC side current i is obtained from the control diagram shown in dc , grid-side d-axis current i d , q-axis current i q .

[0108] Step S603: Determine the initial fusion coefficient based on the SCR and system inertia.

[0109] Among them, the embodiment of the present application can obtain the initial fusion coefficient shown in formula (11) according to the one-dimensional correspondence between SCR and the first fusion coefficient, and the one-dimensional correspondence between the system inertia and the second fusion coefficient.

[0110] Step S604: adjusting the initial fusion coefficient according to the grid-side converter and the DC-side current to obtain the final fusion coefficient to calculate the fusion phase angle of the grid-connected fusion converter.

[0111] Among them, the embodiment of the present application can adjust the initial fusion coefficient according to the grid-side current and the DC-side current to obtain the final fusion coefficient as shown in formula (12), and then calculate the fusion phase angle of the initial grid-following phase angle and the initial grid-forming phase angle, and its calculation formula is shown in formula (14).

[0112] According to the control method of the converter following-grid fusion phase angle proposed in the embodiment of the present application, the initial following-grid phase angle of the following-grid control and the initial grid-forming phase angle of the grid-forming control in the following-grid fusion converter can be obtained, and the initial fusion coefficient can be determined according to the SCR and the system inertia, and then the initial fusion coefficient is adjusted using the DC side current and the grid side current to obtain the final fusion coefficient, so as to calculate the fusion phase angle of the following-grid fusion converter according to the final fusion coefficient, the initial following-grid phase angle and the initial grid-forming phase angle, and comprehensively consider the influence of the SCR and the system inertia, and can adaptively adjust the fusion coefficient under various working conditions of the power grid to ensure the supporting capacity of the power system and the stability of the converter, and by adding the grid-side converter and the DC side current limiting conditions into the fusion coefficient for adjustment, the fusion coefficient can be optimized for different faults and current limiting conditions, the solution speed is faster, the process is simpler, and it can adapt to different faults, current limiting and other actual conditions. This solves the problem that in the related technology, only the influence of SCR is considered, but the influence of the inertia of the connected system and the power limitation of the converter itself are not considered, and the fusion coefficient cannot be adaptively adjusted under various working conditions of the power grid, resulting in poor support capacity of the power grid and stability of the converter, complex solution, long response time, and inability to adapt to different faults, current limiting and other actual situations.

[0113] Next, a control device for the inverter-grid fusion phase angle proposed in an embodiment of the present application will be described with reference to the accompanying drawings.

[0114] Figure 7 It is a block diagram of a control device for the inverter-grid fusion phase angle provided according to an embodiment of the present application.

[0115] like Figure 7 As shown, the control device 10 for the converter-grid fusion phase angle includes: a first acquisition module 100, a determination module 200, a generation module 300 and a first calculation module 400.

[0116] The first acquisition module 100 is used to acquire an initial grid-following phase angle of a grid-following control link and an initial grid-forming phase angle of a grid-forming control link in a grid-following-forming integrated converter.

[0117] The determination module 200 is used to determine the initial fusion coefficient of the control of the grid-connected fusion converter according to the SCR and system inertia of the grid-connected fusion converter connected to the power system.

[0118] The generating module 300 is used to adjust the initial fusion coefficient by using the DC side current and the grid side current to obtain the final fusion coefficient of the grid-connected fusion converter control.

[0119] The first calculation module 400 is used to calculate the fusion phase angle of the following-grid-forming fusion converter according to the final fusion coefficient, the initial following-grid phase angle and the initial forming-grid phase angle.

[0120] Optionally, in one embodiment of the present application, the determination module 200 includes: a first determination unit, a second determination unit and a generation unit.

[0121] Among them, the first determination unit is used to obtain a first fusion coefficient of the follow-grid fusion converter control based on the SCR.

[0122] The second determination unit is used to obtain a second fusion coefficient of the follow-grid fusion converter control based on the system inertia.

[0123] A generating unit is used to obtain an initial fusion coefficient based on the first fusion coefficient and the second fusion coefficient.

[0124] Optionally, in one embodiment of the present application, it further includes: a second calculation module, a second acquisition module and a third calculation module.

[0125] The second calculation module is used to calculate the DC side current based on the DC current reference value of the grid-connected fusion converter before adjusting the initial fusion coefficient using the DC side current and the grid side current.

[0126] The second acquisition module is used to obtain the grid-side d-axis current reference value and q-axis current reference value of the grid-connected grid-integrated converter.

[0127] The third calculation module is used to calculate the grid-side current based on the d-axis current reference value and the q-axis current reference value.

[0128] Optionally, in one embodiment of the present application, the calculation formula of the final fusion coefficient may be, but is not limited to,:

[0129]

[0130] in, is the d-axis and q-axis current i of the grid-side converter d 、i q With the DC side current i dc The arithmetic mean of SCR is the short circuit ratio, H sys is the system inertia, and a is the current adjustment coefficient.

[0131] Optionally, in one embodiment of the present application, the calculation formula of the fusion phase angle may be, but is not limited to,:

[0132] θ Hyb =k Hyb θ ref +(1-k Hyb )θ pll ,

[0133] Among them, θ pll is the grid-following phase angle of the converter grid-following control, θ ref It is the grid phase angle of the converter grid control.

[0134] It should be noted that the above explanation of the embodiment of the control method for the converter-grid fusion phase angle is also applicable to the control device for the converter-grid fusion phase angle of this embodiment, and will not be repeated here.

[0135] According to the control device of the converter following-grid fusion phase angle proposed in the embodiment of the present application, the initial following-grid phase angle of the following-grid control and the initial grid-forming phase angle of the grid-forming control in the following-grid fusion converter can be obtained, and the initial fusion coefficient can be determined according to the SCR and the system inertia, and then the initial fusion coefficient is adjusted by using the DC side current and the grid side current to obtain the final fusion coefficient, so as to calculate the fusion phase angle of the following-grid fusion converter according to the final fusion coefficient, the initial following-grid phase angle and the initial grid-forming phase angle, and comprehensively consider the influence of the SCR and the system inertia, and can adaptively adjust the fusion coefficient under various working conditions of the power grid to ensure the supporting capacity of the power system and the stability of the converter, and by adding the grid-side converter and the DC side current limiting conditions into the fusion coefficient for adjustment, the fusion coefficient can be optimized for different faults and current limiting conditions, the solution speed is faster, the process is simpler, and it can adapt to different faults, current limiting and other actual conditions. This solves the problem that in the related technology, only the influence of SCR is considered, but the influence of the inertia of the connected system and the power limitation of the converter itself are not considered, and the fusion coefficient cannot be adaptively adjusted under various working conditions of the power grid, resulting in poor support capacity of the power grid and stability of the converter, complex solution, long response time, and inability to adapt to different faults, current limiting and other actual situations.

[0136] Figure 8 This is a schematic diagram of the structure of an electronic device provided according to an embodiment of the present application. The electronic device may include:

[0137] A memory 801 , a processor 802 , and a computer program stored in the memory 801 and executable on the processor 802 .

[0138] When the processor 802 executes the program, the control method for the converter-grid fusion phase angle provided in the above embodiment is implemented.

[0139] Furthermore, the electronic device further comprises:

[0140] The communication interface 803 is used for communication between the memory 801 and the processor 802 .

[0141] The memory 801 is used to store computer programs that can be executed on the processor 802 .

[0142] The memory 801 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0143] If the memory 801, the processor 802 and the communication interface 803 are implemented independently, the communication interface 803, the memory 801 and the processor 802 can be connected to each other through a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 8 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0144] Optionally, in a specific implementation, if the memory 801, the processor 802 and the communication interface 803 are integrated on a chip, the memory 801, the processor 802 and the communication interface 803 can communicate with each other through an internal interface.

[0145] The processor 802 may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0146] An embodiment of the present application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned method for controlling the phase angle of the converter-grid fusion.

[0147] An embodiment of the present application also provides a computer program product, including a computer program, which, when executed, implements the above-mentioned method for controlling the phase angle of the converter-grid fusion.

[0148] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0149] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0150] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0151] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or N wirings (electronic devices), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways as necessary and then storing it in a computer memory.

[0152] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. If implemented by hardware, as in another embodiment, it can be implemented by any one or a combination of multiple of the following technologies known in the art: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0153] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0154] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0155] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for controlling the phase angle of a converter and a grid-connected converter, characterized in that: The following steps are involved: Obtaining an initial grid-following phase angle of a grid-following control link and an initial grid-forming phase angle of a grid-forming control link in a grid-following-forming fusion converter; Determine the initial fusion coefficient of the control of the grid-connected fusion converter according to the short-circuit ratio SCR and system inertia of the grid-connected fusion converter connected to the power system; The initial fusion coefficient is adjusted by using the DC side current and the grid side current to obtain the final fusion coefficient of the root-grid fusion converter control; The fusion phase angle of the following-grid-forming fusion converter is calculated according to the final fusion coefficient, the initial following-grid phase angle and the initial forming-grid phase angle.

2. The method according to claim 1, characterized in that The determining of the initial fusion coefficient of the control of the grid-connected fusion converter according to the SCR and system inertia of the grid-connected fusion converter connected to the power system includes: Obtaining a first fusion coefficient of the root-grid fusion converter control based on the SCR; Obtaining a second fusion coefficient of the follow-grid fusion converter control based on the system inertia; The initial fusion coefficient is obtained based on the first fusion coefficient and the second fusion coefficient.

3. The method according to claim 1, characterized in that Before the adjusting the initial fusion coefficient by using the DC side current and the grid side current, the method further includes: Calculating the DC side current based on the DC current reference value of the root-grid fusion converter; Obtaining a grid-side d-axis current reference value and a q-axis current reference value of the root-grid fusion converter; The grid-side current is calculated based on the d-axis current reference value and the q-axis current reference value.

4. The method according to claim 1, characterized in that: The calculation formula of the final fusion coefficient is: in, is the d-axis and q-axis current i of the grid-side converter d 、i q With the DC side current i dc The arithmetic mean of SCR is the short circuit ratio, H sys is the system inertia, and a is the current adjustment coefficient.

5. The method according to claim 1, characterized in that The calculation formula of the fusion phase angle is: i Hyb =k Hyb i ref +(1-k Hyb )i pll , Among them, θ pll is the grid-following phase angle of the converter grid-following control, θ ref It is the grid phase angle of the converter grid control.

6. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for controlling the phase angle of the converter and the grid fusion as described in any one of claims 1 to 5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the method for controlling the phase angle of the converter and the grid as described in any one of claims 1 to 5.

8. A computer program product, characterized in that It comprises a computer program which, when executed, is used to implement the method for controlling the phase angle of the converter and the grid fusion as described in any one of claims 1 to 5.

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