Judgment method and device for periodic rail of full-power voltage source type grid-connected converter, storage medium and electronic equipment

Abstract

The invention provides a full-power voltage source type grid-connected converter periodic rail judgment method and device, a storage medium and electronic equipment, and relates to the technical field of power grid facility problem analysis, and the method comprises the steps: calculating the position of a singular surface of a target model in a phase space formed by state variables, and obtaining a feasible region of the target model; the target model is a full-power voltage source type grid-connected converter three-order power system model constructed based on target control parameters; and calculating a judgment factor based on the state variable, and judging whether the target model has a periodic orbit based on the judgment factor and the feasible region. According to the method and device for judging the periodic rail of the full-power voltage source type grid-connected converter, the storage medium and the electronic equipment provided by the invention, whether the periodic rail can appear in the full-power voltage source type grid-connected converter or not can be predicted, and the control parameters are adjusted before the periodic rail appears, so that the occurrence of the periodic rail is avoided.

Description

Technical Field

[0001] The present application relates to the technical field of power grid facility problem analysis, and in particular to a method, device, storage medium and electronic device for determining a periodic orbit of a full-power voltage source grid-connected converter. Background Art

[0002] New energy sources are mainly fed into the power grid through power electronic devices (inverters, frequency converters and rectifiers). The function of power electronic devices is to convert the electric energy generated by new energy sources (such as solar energy, wind energy, etc.) into a form of electric energy suitable for use by the power grid. For example, solar panels generate direct current, which cannot be directly supplied to the power grid. At this time, an inverter is needed to convert direct current into alternating current and adjust the voltage and frequency to meet the requirements of the power grid.

[0003] The full-power voltage source grid-connected converter (VSC) is the main power electronic interface device for connecting new energy power sources to the power grid. When a large disturbance occurs, due to the inherent characteristics of the high-order power system, it is very easy to generate a limit cycle near the operating point, causing the system to have a periodic orbit after the disturbance. At this time, the state variables of the VSC will oscillate periodically, which has an important impact on the safe and stable operation of the system.

[0004] Based on this, there is an urgent need for a judgment method that can make timely judgments and early warnings to avoid the generation of periodic orbits and improve the stability of power grid operation. Summary of the invention

[0005] The purpose of the present application is to provide a method, device, storage medium and electronic device for determining the periodic orbit of a full-power voltage source grid-connected converter, which can predict whether a full-power voltage source grid-connected converter can have a periodic orbit, and adjust the control parameters before the periodic orbit appears, thereby avoiding the occurrence of the periodic orbit.

[0006] The present application provides a method for determining a periodic orbit of a full-power voltage source grid-connected converter, comprising: The position of the singular surface of the target model in the phase space spanned by the state variables is calculated to obtain the feasible domain of the target model; the target model is: a third-order power system model of a full-power voltage source grid-connected converter constructed based on target control parameters; a judgment factor is calculated based on the state variables, and based on the judgment factor and the feasible domain, it is judged whether the target model has a periodic orbit; wherein the state variables include: the DC side capacitor voltage of the target model, the DC voltage outer loop integral variable of the target model, and the AC voltage outer loop integral variable of the target model.

[0007] Optionally, after determining whether the target model has a periodic orbit based on the judgment factor and the feasible domain, the method further includes: if it is determined that the target model has a periodic orbit, adjusting the target parameter until the comparison result between the judgment factor and the feasible domain indicates that the target model does not have a periodic orbit.

[0008] Optionally, the singular surface of the target model is calculated based on the following formula:

[0009] in, and For the strange side, is the grid voltage, is the line reactance, is the DC side capacitor voltage of the target model, is the proportional coefficient of the DC voltage outer loop proportional-integral control, is the proportional coefficient of the AC voltage outer loop proportional-integral control, is the integral coefficient of the DC voltage outer loop proportional integral control, is the integral coefficient of the AC voltage outer loop proportional integral control, is the DC voltage outer loop integral variable, is the AC side voltage reference value of the target model.

[0010] Optionally, the feasible domain of the target model is expressed based on the following formula:

[0011] in, is the feasible domain, is the state variable, is the AC voltage outer loop integral variable of the target model.

[0012] Optionally, the calculating the judgment factor based on the state variable includes: The judgment factor is defined as: , Satisfies the following formula:

[0013] in, is a vector field, P is the active output of the target model, is the active input of the target model, is the DC side capacitance of the target model, is the AC side capacitor voltage of the target model, is the direct-axis current of the target model.

[0014] Optionally, judging whether the target model has a periodic orbit based on the judgment factor and the feasible domain includes: if the judgment factor has no solution in the feasible domain, determining that the target model does not have a periodic orbit; otherwise, determining that the target model may have a periodic orbit.

[0015] The present application also provides a device for determining a periodic rail of a full-power voltage source grid-connected converter, comprising: A calculation module is used to calculate the position of the singular surface of the target model in the phase space spanned by the state variables to obtain the feasible domain of the target model; the target model is: a third-order power system model of a full-power voltage source grid-connected converter constructed based on target control parameters; the calculation module is also used to calculate a judgment factor based on the state variables; a judgment module is used to judge whether the target model has a periodic orbit based on the judgment factor and the feasible domain; wherein the state variables include: the DC side capacitor voltage of the target model, the DC voltage outer loop integral variable of the target model, and the AC voltage outer loop integral variable of the target model.

[0016] Optionally, the device further includes: a control module; the control module is used to adjust the target parameter when it is determined that the target model has a periodic orbit, until the comparison result between the judgment factor and the feasible domain indicates that the target model does not have a periodic orbit.

[0017] Optionally, the singular surface of the target model is calculated based on the following formula:

[0018] in, and For the strange side, is the grid voltage, is the line reactance, is the DC side capacitor voltage of the target model, is the proportional coefficient of the DC voltage outer loop proportional-integral control, is the proportional coefficient of the AC voltage outer loop proportional-integral control, is the integral coefficient of the DC voltage outer loop proportional integral control, is the integral coefficient of the AC voltage outer loop proportional integral control, is the DC voltage outer loop integral variable, is the AC side voltage reference value of the target model.

[0019] Optionally, the feasible domain of the target model is expressed based on the following formula:

[0020] in, is the feasible domain, is the state variable, is the AC voltage outer loop integral variable of the target model.

[0021] Optionally, the calculating the judgment factor based on the state variable includes: The judgment factor is defined as: , Satisfies the following formula:

[0022] in, is a vector field, P is the active output of the target model, is the active input of the target model, is the DC side capacitance of the target model, is the AC side capacitor voltage of the target model, is the direct-axis current of the target model.

[0023] Optionally, the judgment module is specifically configured to determine that the target model does not have a periodic orbit if the judgment factor has no solution in the feasible domain; otherwise, determine that the target model may have a periodic orbit.

[0024] The present application also provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of the method for determining the periodic rail of a full-power voltage source grid-connected converter as described in any one of the above.

[0025] The present application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the method for determining the periodic rail of a full-power voltage source grid-connected converter as described in any one of the above are implemented.

[0026] The present application also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the method for determining the periodic rail of a full-power voltage source grid-connected converter as described in any one of the above are implemented.

[0027] The present application provides a method, device, storage medium and electronic device for determining the periodic orbit of a full-power voltage source grid-connected converter. First, the position of the singular surface of the target model in the phase space formed by the state variables is calculated to obtain the feasible domain of the target model; the target model is: a third-order power system model of a full-power voltage source grid-connected converter constructed based on the target control parameters; then, a judgment factor is calculated based on the state variables, and based on the judgment factor and the feasible domain, it is determined whether the target model has a periodic orbit; wherein the state variables include: the DC side capacitor voltage of the target model, the DC voltage outer loop integral variable of the target model, and the AC voltage outer loop integral variable of the target model. In this way, it is possible to predict whether a full-power voltage source grid-connected converter can have a periodic orbit, and adjust the control parameters before the periodic orbit appears, thereby avoiding the appearance of the periodic orbit. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 It is a power loop control structure diagram of the VSC provided by the present application; Figure 2 It is a schematic diagram of the relationship between the voltage phasors of the VSC provided in this application; Figure 3 It is a flow chart of a method for determining a periodic orbit of a full-power voltage source grid-connected converter provided by the present application; Figure 4 It is one of the schematic diagrams comparing the third-order power system model of VSC and the detailed full-order model of VSC provided in this application; Figure 5 This is the second schematic diagram comparing the third-order power system model of VSC provided in this application with the detailed full-order model of VSC; Figure 6 It is a schematic diagram of the VSC operation balance point provided by this application; Figure 7 It is a schematic diagram of the VSC state variable provided by the present application performing equal amplitude oscillation in the time domain; Figure 8 It is one of the schematic diagrams of changes in the feasible domain determined by the VSC during operation provided by the present application; Fig. 9 This is the second schematic diagram of the change in the feasible domain determined by the VSC during operation provided by the present application; Fig.10It is one of the electromagnetic transient simulation schematic diagrams of the third-order power system model of the VSC provided in this application; Fig.11 This is the second electromagnetic transient simulation schematic diagram of the third-order power system model of the VSC provided in this application; Fig.12 It is a structural schematic diagram of a device for determining a periodic orbit of a full-power voltage source grid-connected converter provided by the present application; Fig.13 It is a structural schematic diagram of the electronic device provided by this application. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0032] When a full-power voltage source grid-connected converter VSC is subjected to a large disturbance, due to the inherent characteristics of the high-order power system, it is very easy to generate limit cycles near the operating point, causing the system to have a periodic orbit after the disturbance. At this time, the state variables of the VSC will oscillate periodically, which will have an important impact on the safe and stable operation of the system. Therefore, the system should try to avoid the generation of limit cycles when designing operating parameters. The internal control links of the VSC that are prone to cause limit cycles are the phase-locked loop and the power loop. The phase-locked loop is a second-order dynamic process, and the existing research and engineering applications have been relatively sufficient to study the limit cycles caused by it. The power loop is a third-order dynamic process, and the limit cycles caused by it are difficult to fully reveal in terms of mathematical principles and engineering applications. It is even more urgent to propose a practical parameter optimization method to exclude the periodic orbit of the system.

[0033] Based on this, the embodiment of the present application provides a method for determining the periodic orbit of a full-power voltage source grid-connected converter, which can determine the existence of the limit cycle caused by the VSC outer loop during the transient process, and optimize the parameters based on the proposed criteria to avoid the system from generating periodic orbits. In addition, the method for determining the periodic orbit of a full-power voltage source grid-connected converter in the embodiment of the present application can be completed in advance, without relying on the actual operation data of the system or a large amount of numerical simulation, and can be completed only based on control parameters and structural parameters. System operators can reasonably adjust the operating parameters to eliminate the system limit cycle, thereby improving system stability.

[0034] The following is a detailed explanation of the VSC power loop control structure diagram involved in the embodiment of the present application. Figure 1 As shown in the figure is its active input, For active output; is the VSC DC side capacitance; is the VSC DC side capacitor voltage, is the VSC DC side capacitor voltage reference value; ( ) and ( ) are the proportional coefficient and integral coefficient of the DC voltage (AC voltage) outer loop proportional-integral controller respectively; and are VSC d / q axis current reference values ​​respectively; is the potential inside the VSC; is the capacitor voltage on the AC side of VSC, is the VSC AC side voltage reference value; is the VSC output current; is the VSC phase-locked loop phase.

[0035] The third-order differential equation model of the full-power voltage source grid-connected converter can be expressed by the following formula 1: (Formula 1)

[0036] For a typical VSC control, its control links include phase-locked loop, current loop and voltage loop. Since the time scale of VSC current loop and phase-locked loop is relatively fast, when analyzing the voltage loop characteristics, it can be approximately considered that the other two links reach a quasi-steady state, which can be described mathematically by algebraic equations, as shown in the following formula 2, where is a state variable, is the DC voltage outer loop integral variable, is the integral variable of the AC voltage outer loop.

[0037] (Formula 2)

[0038] in, and All of them are nonlinear algebraic equations, and their derivations are given below. The VSC output active power satisfies the following formula 3: (Formula 3)

[0039] In the above formula 3, and yes The component on the d / q axis can be calculated using the following formula 4: (Formula 4)

[0040] Further considering the line resistance of VSC connected to the grid and line reactance And the grid voltage , each voltage phasor satisfies Figure 2 Considering that high voltage transmission lines often have , based on Figure 2 The geometric relationship shown in The expression is: (Formula 5)

[0041] In summary, the third-order power system model of the power loop of the full-power voltage source grid-connected converter can be constructed according to the above formulas 1, 2, 3 and 5.

[0042] The following is a detailed description of the method for determining the periodic orbit of the full-power voltage source grid-connected converter provided in the embodiment of the present application through specific embodiments and application scenarios in conjunction with the accompanying drawings.

[0043] like Figure 3 As shown, an embodiment of the present application provides a method for determining a periodic rail of a full-power voltage source grid-connected converter, and the method may include the following steps 301 and 302: Step 301: Calculate the position of the singular surface of the target model in the phase space spanned by the state variables to obtain the feasible domain of the target model.

[0044] Wherein, the target model is: a third-order power system model of a full-power voltage source grid-connected converter constructed based on target control parameters.

[0045] Exemplarily, after completing the construction of the third-order power system model of the full-power voltage source grid-connected converter, according to the above formula 5, it can be known that the sufficient condition for the above formula 5 to have a solution is , in the state variable In the phase space of Zhang Cheng, this condition can be described as a parallelepiped region , that is, the feasible domain of the target model. Among them, is the feasible domain, is the state variable, is the AC voltage outer loop integral variable of the target model, and is a singular surface, which can be specifically expressed by the following formula 6 and formula 7: (Formula 6)

[0046] (Formula 7)

[0047] in, is the grid voltage, is the line reactance, is the DC side capacitor voltage of the target model, is the proportional coefficient of the DC voltage outer loop proportional-integral control, is the proportional coefficient of the AC voltage outer loop proportional-integral control, is the integral coefficient of the DC voltage outer loop proportional integral control, is the integral coefficient of the AC voltage outer loop proportional integral control, is the DC voltage outer loop integral variable, is the AC side voltage reference value of the target model.

[0048] For example, a full electromagnetic transient simulation model was built based on MATLAB, and the proposed third-order power system model was compared with the VSC detailed full-order model. The results are as follows: Figure 4 and Figure 5 As shown, it can be seen that the proposed model can well characterize the dynamic behavior of the system in both stable and unstable modes.

[0049] Exemplarily, in the embodiment of the present application, the target model may be constructed based on the system parameters shown in the representation:

[0050] Table 1

[0051] For example, based on the above formula 6 and formula 7, the position of the singular surface of the target model in the phase space can be calculated, and then the feasible domain of the target model can be obtained: .

[0052] Step 302: Calculate a judgment factor based on the state variable, and judge whether the target model has a periodic orbit based on the judgment factor and the feasible domain.

[0053] The state variables include: the DC side capacitor voltage of the target model, the DC voltage outer loop integral variable of the target model, and the AC voltage outer loop integral variable of the target model.

[0054] For example, based on the above third-order dynamic system model (i.e., the above target model), it is further found that the system In the case of periodic orbit phenomenon, Figure 6 As shown in the figure, SEP is the equilibrium point of VSC operation. Assume that at 5s, the VSC operation is disturbed and the disturbance is set to the grid voltage. From 1.0 to 0.78, is the disturbance clearing time. Figure 6 It can be found that the state variable shown by the black curve The trajectory in the phase plane is a closed circle, based on Figure 6 ,like Figure 7 As shown, the corresponding VSC state variable oscillates with equal amplitude in the time domain.

[0055] For example, it is generally believed that the appearance of periodic orbits will make the transient behavior of the system more complicated, and the continuous periodic oscillation of the state variables will greatly reduce the stability of the system. Therefore, the actual system hopes to avoid the appearance of periodic orbits during operation, thereby enhancing the stability of the system. For high-order nonlinear systems, the characteristics of their periodic orbits can be analyzed in the following ways.

[0056] For example, in the embodiment of the present application, for the target model, the judgment factor can be defined as: , Satisfies the following formula:

[0057] in, is a vector field, P is the active output of the target model, is the active input of the target model, is the DC side capacitance of the target model, is the AC side capacitor voltage of the target model, is the direct-axis current of the target model.

[0058] For example, based on the above judgment factors, the criterion for excluding the periodic orbit of the VSC third-order power system model (ie, the above target model) can be obtained: 1. If In the area There is no solution in the region In, there is always or , then VSC can exclude periodic orbits.

[0059] 2. If In the area There is a solution in the region middle, If there are zero crossings, VSC cannot exclude periodic orbits, and under certain parameter conditions, periodic orbits may appear.

[0060] Specifically, the above step 302 may further include the following step 302a: Step 302a: If the judgment factor has no solution in the feasible domain, it is determined that the target model does not have a periodic orbit; otherwise, it is determined that the target model may have a periodic orbit.

[0061] It should be noted that, in the embodiments of the present application, when In the area When there is no solution in , it can be determined that there is no periodic orbit; when In the area When there is a solution in , the system has the possibility of having a periodic orbit, that is, it may exist or not. At this time, in order to avoid missing judgment, it can be regarded as a periodic orbit and the control parameters can be adjusted until In the area There is no solution.

[0062] Optionally, in the embodiment of the present application, when it is determined that the target model may have a periodic orbit, the periodic orbit may be eliminated by adjusting control parameters.

[0063] Exemplarily, after the above step 302, the method for determining the periodic rail of the full-power voltage source grid-connected converter provided in the embodiment of the present application may further include the following step 303: Step 303: When it is determined that the target model has a periodic orbit, the target parameter is adjusted until the comparison result between the judgment factor and the feasible region indicates that the target model does not have a periodic orbit.

[0064] The verification of the criterion proposed by the present invention is given below. Under the parameter conditions shown in Table 1, when When Figure 6 and Figure 7 It can be seen that there is a periodic orbit in the VSC operation process. Figure 8 As shown, the judgment factor is given in the feasible domain at this time The changes can be seen. In the area There is a solution in , the criterion is not satisfied, and there is a limit cycle.

[0065] Further reduce When When the other parameters remain unchanged, the judgment factor is in the feasible region. Changes such as Fig. 9 As shown. In the area There is no solution in the area In, there is always , VSC can exclude periodic orbits. Fig.10 and Fig.11 Given the electromagnetic transient simulation at this time, it can be seen that Figure 6 and Figure 7 Under the same fault setting conditions, there is no periodic orbit in the system, the system is stable after being disturbed, and the system stability is enhanced.

[0066] The method for determining the periodic orbit of a full-power voltage source grid-connected converter provided in an embodiment of the present application, first, calculate the position of the singular surface of the target model in the phase space formed by the state variables to obtain the feasible domain of the target model; the target model is: a third-order power system model of a full-power voltage source grid-connected converter constructed based on the target control parameters; then, calculate the judgment factor based on the state variables, and determine whether the target model has a periodic orbit based on the judgment factor and the feasible domain; wherein the state variables include: the DC side capacitor voltage of the target model, the DC voltage outer loop integral variable of the target model, and the AC voltage outer loop integral variable of the target model. In this way, it is possible to predict whether a full-power voltage source grid-connected converter can have a periodic orbit, and adjust the control parameters before the periodic orbit appears, thereby avoiding the appearance of the periodic orbit.

[0067] It should be noted that the method for determining the periodic rail of a full-power voltage source type grid-connected converter provided in the embodiment of the present application may be executed by a device for determining the periodic rail of a full-power voltage source type grid-connected converter, or a control module for executing the method for determining the periodic rail of a full-power voltage source type grid-connected converter in the device for determining the periodic rail of a full-power voltage source type grid-connected converter. In the embodiment of the present application, the device for determining the periodic rail of a full-power voltage source type grid-connected converter is taken as an example to illustrate the device for determining the periodic rail of a full-power voltage source type grid-connected converter provided in the embodiment of the present application.

[0068] It should be noted that in the embodiments of the present application, the methods shown in the above-mentioned drawings of the methods. The methods for determining the periodic rail of the full-power voltage source type grid-connected converter are all illustrated by combining an accompanying drawing in the embodiments of the present application as an example. In specific implementation, the methods for determining the periodic rail of the full-power voltage source type grid-connected converter shown in the above-mentioned drawings of the methods can also be implemented in combination with any other drawings that can be combined as shown in the above-mentioned embodiments, and will not be repeated here.

[0069] The following is a description of the device for determining the periodic orbit of the full-power voltage source grid-connected converter provided in the present application. The method for determining the periodic orbit of the full-power voltage source grid-connected converter described below and described above can refer to each other.

[0070] Fig.12 A schematic diagram of the structure of a device for determining a periodic rail of a full-power voltage source grid-connected converter provided in an embodiment of the present application is shown in FIG. Fig.12 As shown, specifically including: The calculation module 1021 is used to calculate the position of the singular surface of the target model in the phase space spanned by the state variables to obtain the feasible domain of the target model; the target model is: a third-order power system model of a full-power voltage source grid-connected converter constructed based on the target control parameters; the calculation module 1201 is also used to calculate the judgment factor based on the state variables; the judgment module 1202 is used to judge whether the target model has a periodic orbit based on the judgment factor and the feasible domain; wherein the state variables include: the DC side capacitor voltage of the target model, the DC voltage outer loop integral variable of the target model and the AC voltage outer loop integral variable of the target model.

[0071] Optionally, the device further includes: a control module 1203; the control module 1203 is used to adjust the target parameter when it is determined that the target model has a periodic orbit, until the comparison result between the judgment factor and the feasible domain indicates that the target model does not have a periodic orbit.

[0072] Optionally, the singular surface of the target model is calculated based on the following formula:

[0073] in, and For the strange side, is the grid voltage, is the line reactance, is the DC side capacitor voltage of the target model, is the proportional coefficient of the DC voltage outer loop proportional-integral control, is the proportional coefficient of the AC voltage outer loop proportional-integral control, is the integral coefficient of the DC voltage outer loop proportional integral control, is the integral coefficient of the AC voltage outer loop proportional integral control, is the DC voltage outer loop integral variable, is the AC side voltage reference value of the target model.

[0074] Optionally, the feasible domain of the target model is expressed based on the following formula:

[0075] in, is the feasible domain, is the state variable, is the AC voltage outer loop integral variable of the target model.

[0076] Optionally, the calculating the judgment factor based on the state variable includes: The judgment factor is defined as: , Satisfies the following formula:

[0077] in, is a vector field, P is the active output of the target model, is the active input of the target model, is the DC side capacitance of the target model, is the AC side capacitor voltage of the target model, is the direct-axis current of the target model.

[0078] Optionally, the judgment module 1202 is specifically configured to determine that the target model does not have a periodic orbit if the judgment factor has no solution in the feasible domain; otherwise, determine that the target model may have a periodic orbit.

[0079] The present application provides a device for determining the periodic orbit of a full-power voltage source grid-connected converter. First, the position of the singular surface of the target model in the phase space formed by the state variables is calculated to obtain the feasible domain of the target model; the target model is: a third-order power system model of a full-power voltage source grid-connected converter constructed based on the target control parameters; then, a determination factor is calculated based on the state variables, and whether the target model has a periodic orbit is determined based on the determination factor and the feasible domain; wherein the state variables include: the DC side capacitor voltage of the target model, the DC voltage outer loop integral variable of the target model, and the AC voltage outer loop integral variable of the target model. In this way, it is possible to predict whether a full-power voltage source grid-connected converter can have a periodic orbit, and adjust the control parameters before the periodic orbit appears, thereby avoiding the appearance of the periodic orbit.

[0080] Fig.13 An example of a physical structure diagram of an electronic device is shown in FIG. Fig.13As shown, the electronic device may include: a processor 1310, a communication interface 1320, a memory 1330 and a communication bus 1340, wherein the processor 1310, the communication interface 1320 and the memory 1330 communicate with each other through the communication bus 1340. The processor 1310 may call the logic instructions in the memory 1330 to execute a method for determining a periodic orbit of a full-power voltage source grid-connected converter, the method comprising: calculating the position of a singular surface of a target model in a phase space spanned by state variables to obtain a feasible domain of the target model; the target model is: a third-order power system model of a full-power voltage source grid-connected converter constructed based on target control parameters; calculating a determination factor based on the state variables, and determining whether the target model has a periodic orbit based on the determination factor and the feasible domain; wherein the state variables include: a DC side capacitor voltage of the target model, a DC voltage outer loop integral variable of the target model and an AC voltage outer loop integral variable of the target model.

[0081] In addition, the logic instructions in the above-mentioned memory 1330 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0082] On the other hand, the present application also provides a computer program product, which includes a computer program stored on a computer-readable storage medium, and the computer program includes program instructions. When the program instructions are executed by a computer, the computer can execute the method for determining the periodic orbit of a full-power voltage source grid-connected converter provided by the above methods, the method including: calculating the position of a singular surface of a target model in a phase space spanned by state variables to obtain a feasible domain of the target model; the target model is: a third-order power system model of a full-power voltage source grid-connected converter constructed based on target control parameters; calculating a judgment factor based on the state variables, and determining whether the target model has a periodic orbit based on the judgment factor and the feasible domain; wherein the state variables include: the DC side capacitor voltage of the target model, the DC voltage outer loop integral variable of the target model, and the AC voltage outer loop integral variable of the target model.

[0083] On the other hand, the present application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute the above-mentioned method for determining the periodic orbit of the full-power voltage source grid-connected converter, the method comprising: calculating the position of the singular surface of the target model in the phase space spanned by the state variables, and obtaining the feasible domain of the target model; the target model is: a third-order power system model of a full-power voltage source grid-connected converter constructed based on the target control parameters; calculating a judgment factor based on the state variables, and determining whether the target model has a periodic orbit based on the judgment factor and the feasible domain; wherein the state variables include: the DC side capacitor voltage of the target model, the DC voltage outer loop integral variable of the target model, and the AC voltage outer loop integral variable of the target model.

[0084] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0085] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for determining the periodic orbit of a full-power voltage source grid-connected converter, characterized in that: include: Calculating the position of the singular surface of the target model in the phase space spanned by the state variables to obtain the feasible domain of the target model; The target model is: a third-order power system model of a full-power voltage source grid-connected converter constructed based on target control parameters; Calculating a judgment factor based on the state variable, and judging whether the target model has a periodic orbit based on the judgment factor and the feasible domain; The state variables include: the DC side capacitor voltage of the target model, the DC voltage outer loop integral variable of the target model, and the AC voltage outer loop integral variable of the target model.

2. The method according to claim 1, characterized in that After determining whether the target model has a periodic orbit based on the determination factor and the feasible domain, the method further includes: In the case where it is determined that the target model has a periodic orbit, the target parameter is adjusted until a comparison result between the judgment factor and the feasible domain indicates that the target model does not have a periodic orbit.

3. The method according to claim 1 or 2, characterized in that: The singular surface of the target model is calculated based on the following formula: in, and For the strange side, is the grid voltage, is the line reactance, is the DC side capacitor voltage of the target model, is the proportional coefficient of the DC voltage outer loop proportional-integral control, is the proportional coefficient of the AC voltage outer loop proportional-integral control, is the integral coefficient of the DC voltage outer loop proportional integral control, is the integral coefficient of the AC voltage outer loop proportional integral control, is the DC voltage outer loop integral variable, is the AC side voltage reference value of the target model.

4. The method according to claim 3, characterized in that The feasible domain of the target model is expressed based on the following formula: in, is the feasible domain, is the state variable, is the AC voltage outer loop integral variable of the target model.

5. The method according to claim 3, characterized in that: The calculating of the judgment factor based on the state variable comprises: The judgment factor is defined as: , Satisfies the following formula: in, is a vector field, P is the active output of the target model, is the active input of the target model, is the DC side capacitance of the target model, is the AC side capacitor voltage of the target model, is the direct-axis current of the target model.

6. The method according to claim 5, characterized in that The step of judging whether the target model has a periodic orbit based on the judgment factor and the feasible domain includes: If the judgment factor has no solution in the feasible domain, it is determined that the target model does not have a periodic orbit; otherwise, it is determined that the target model may have a periodic orbit.

7. A device for determining the periodic orbit of a full-power voltage source grid-connected converter, characterized in that: The device comprises: A calculation module, used for calculating the position of the singular surface of the target model in the phase space spanned by the state variables, and obtaining the feasible domain of the target model; the target model is: a third-order power system model of a full-power voltage source grid-connected converter constructed based on target control parameters; The calculation module is further used to calculate the judgment factor based on the state variable; A judgment module, used for judging whether the target model has a periodic orbit based on the judgment factor and the feasible domain; The state variables include: the DC side capacitor voltage of the target model, the DC voltage outer loop integral variable of the target model, and the AC voltage outer loop integral variable of the target model.

8. The device according to claim 7, characterized in that The device also includes: a control module; The control module is used to adjust the target parameter when it is determined that the target model has a periodic orbit, until the comparison result between the judgment factor and the feasible domain indicates that the target model does not have a periodic orbit.

9. An electronic device, characterized in that: It comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the method for determining the periodic rail of a full-power voltage source grid-connected converter as claimed in any one of claims 1 to 6 are implemented.

10. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed by a processor, the steps of the method for determining the periodic rail of a full-power voltage source grid-connected converter as claimed in any one of claims 1 to 6 are implemented.

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