Adaptive Method and Device for Virtual Synchronization Parameters of a Flexible DC Transmission Island System

Abstract

The present application relates to a virtual synchronous parameter adaptive method, device and equipment for a flexible DC transmission island system. The method includes obtaining first power data, connection impedance data, moment of inertia data and second power data of the flexible DC transmission island system; calculating a power conversion coefficient according to the first power data, the connection impedance data and the second power data; calculating an inertia coefficient according to the connection impedance data and the moment of inertia data; using the first DC output power of the first power data, the second DC output power of the second power data, the power conversion coefficient and the inertia coefficient as control parameters for virtual synchronous control. This method uses the first DC output power, the second DC output power, the power conversion coefficient and the inertia coefficient as control parameters for virtual synchronous control in the flexible DC transmission island system, avoiding the occurrence of power angle instability in the flexible DC transmission island system caused by improper setting of the inertia time constant of virtual synchronous control.

Description

Technical Field

[0001] The present application relates to the technical field of power system control, and in particular, to a method, device, and equipment for adaptively adjusting virtual synchronous parameters of a flexible DC transmission island system. Background Art

[0002] Most large-scale new energy resources are located in remote areas such as deserts, gobi, and wastelands, where the local power grid is weak and it is difficult to operate the new energy island for transmission. Therefore, large-scale new energy can be weakly connected to the local power grid and then transmitted through flexible DC. In a large-scale new energy weak-interconnection transmission system, the electrical distance of the local power grid is long and the support ability for new energy is insufficient, so flexible DC is often required to form a network. Flexible DC adopts constant amplitude and constant frequency control (VF control). Among them, there are two ways of constant frequency control, namely using a given value and virtual synchronous control. Virtual synchronous control is further divided into two types: controlling the frequency deviation according to a certain proportional coefficient based on the power deviation and dynamically adjusting the frequency control according to the power deviation according to the inertia time constant.

[0003] The problems existing in the constant amplitude and constant frequency control in a large-scale new energy weak-interconnection transmission system are as follows:

[0004] The frequency of the flexible DC using constant frequency control is constant and cannot participate in primary frequency modulation. If there are large-power disturbances such as generator tripping / load shedding in the local power grid, the flexible DC will bear a large amount of unbalanced power. When the power of generator tripping / load shedding is greater than the adjustable capacity of the flexible DC, the power of the flexible DC converter station will saturate, resulting in control failure, and further bringing risks to the safe operation of the transmission system.

[0005] The frequency of the flexible DC using virtual synchronous control can be adjusted according to the unbalanced power, which can reduce the amount of unbalanced power borne. However, if the inertia time constant is set improperly, it is easy to cause power angle instability with the weak power grid due to excessive phase angle swing of the flexible DC after a fault. Summary of the Invention

[0006] The embodiments of the present application provide a method, device, and equipment for adaptively adjusting virtual synchronous parameters of a flexible DC transmission island system, which are used to solve the technical problem that when virtual synchronous control is adopted in an existing new energy weak-interconnection transmission island system through flexible DC, power angle instability is likely to occur after a fault due to improper setting of the inertia time constant.

[0007] To achieve the above object, the embodiments of the present application provide the following technical solutions:

[0008] On the one hand, a method for adaptively adjusting virtual synchronous parameters of a flexible DC transmission island system is provided, including the following steps:

[0009] Obtain the first power data, connection impedance data, moment of inertia data, and second power data of the transmission line in the flexible DC transmission island system, where the second power data is obtained after low-pass filtering the transmission power of the transmission line in the flexible DC transmission island system;

[0010] Calculate based on the first power data, the connection impedance data, and the second power data to obtain the power conversion coefficient of virtual synchronous control in the flexible DC transmission island system;

[0011] Calculate based on the connection impedance data and the moment of inertia data to obtain the inertia coefficient of virtual synchronous control;

[0012] Use the first DC output power of the first power data, the second DC output power of the second power data, the power conversion coefficient, and the inertia coefficient as the control parameters of virtual synchronous control to control the operation of the flexible DC transmission island system.

[0013] Preferably, the first power data includes the first output power, the first DC output power, and the first tie line power of each synchronous machine group, the second power data includes the second output power, the second DC output power, and the second tie line power of each synchronous machine group, both the first tie line power and the second tie line power are the tie line powers between the flexible DC transmission island system and the local synchronous power grid of the power system, the connection impedance data includes the machine group connection impedance and the synchronous connection impedance of each synchronous machine group, and the moment of inertia data includes the machine group moment of inertia and the synchronous power grid moment of inertia of each synchronous machine group.

[0014] Preferably, calculating based on the first power data, the connection impedance data, and the second power data to obtain the power conversion coefficient of virtual synchronous control in the flexible DC transmission island system includes:

[0015] Calculate the first output power of each synchronous machine group with its corresponding second output power to obtain the output power difference of each synchronous machine group;

[0016] Calculate the first DC output power with the second DC output power to obtain the DC output power difference; calculate the first tie line power with the second tie line power to obtain the tie line power difference;

[0017] Calculate the output power difference of each synchronous machine group with the corresponding machine group connection impedance to obtain the first data of each synchronous machine group; calculate the tie line power difference with the synchronous connection impedance to obtain the second data;

[0018] Calculate all the first data, the second data, and the DC output power difference to obtain the power conversion coefficient of virtual synchronous control in the flexible DC transmission island system.

[0019] Preferably, the virtual synchronous parameter adaptive method for the flexible DC transmission island system includes: calculating according to the first power data, the connection impedance data, and the second power data using the power conversion coefficient calculation formula to obtain the power conversion coefficient of virtual synchronous control in the flexible DC transmission island system, and the power conversion coefficient calculation formula is:

[0020]

[0021] In the formula, K p is the power conversion coefficient, n is the total number of synchronous machine groups in the flexible DC transmission island system, P sgi(0) is the first output power of the i-th synchronous machine group, P sgi is the second output power of the i-th synchronous machine group, P grid(0) is the first tie line power, P grid is the second tie line power, X sgi is the machine group connection impedance of the i-th synchronous machine group, X grid is the synchronous connection impedance, P hvdc(0) is the first DC output power, P hvdc is the second DC output power.

[0022] Preferably, calculating according to the connection impedance data and the moment of inertia data to obtain the inertia coefficient of virtual synchronous control includes:

[0023] Calculating the machine group connection impedance of each synchronous machine group with its corresponding machine group moment of inertia to obtain the first inertia data of each synchronous machine group;

[0024] Calculating the synchronous connection impedance with the synchronous grid moment of inertia to obtain the second inertia data;

[0025] Calculating according to all the first inertia data and the second inertia data to obtain the inertia coefficient of virtual synchronous control.

[0026] Preferably, the virtual synchronous parameter adaptive method for the flexible DC transmission island system includes: calculating according to the connection impedance data and the moment of inertia data using the inertia coefficient calculation formula to obtain the inertia coefficient of virtual synchronous control; the inertia coefficient calculation formula is:

[0027]

[0028] In the formula, J is the inertia coefficient of virtual synchronous control, n is the total number of synchronous machine groups in the flexible DC transmission island system, Xsgi is the cluster connection impedance of the i-th synchronous machine cluster, X grid is the synchronous connection impedance, J sgi is the cluster moment of inertia of the i-th synchronous machine cluster, J grid is the moment of inertia of the synchronous power grid.

[0029] On the other hand, a virtual synchronous parameter adaptive device for a flexible DC transmission island system is provided, including a data acquisition module, a first calculation module, a second calculation module, and an execution control module;

[0030] The data acquisition module is used to acquire the first power data, connection impedance data, moment of inertia data, and second power data of the transmission line in the flexible DC transmission island system. The second power data is obtained by performing low-pass filtering on the transmission power of the transmission line in the flexible DC transmission island system;

[0031] The first calculation module is used to calculate according to the first power data, the connection impedance data, and the second power data to obtain the power conversion coefficient of virtual synchronous control in the flexible DC transmission island system;

[0032] The second calculation module is used to calculate according to the connection impedance data and the moment of inertia data to obtain the inertia coefficient of virtual synchronous control;

[0033] The execution control module is used to control the operation of the flexible DC transmission island system according to the first DC output power of the first power data, the second DC output power of the second power data, the power conversion coefficient, and the inertia coefficient as the control parameters of virtual synchronous control.

[0034] Preferably, the first calculation module is further used to calculate according to the first power data, the connection impedance data, and the second power data by using a power conversion coefficient calculation formula to obtain the power conversion coefficient of virtual synchronous control in the flexible DC transmission island system. The power conversion coefficient calculation formula is:

[0035]

[0036] In the formula, K p is the power conversion coefficient, n is the total number of synchronous machine clusters in the flexible DC transmission island system, P sgi(0) is the first transmission power of the i-th synchronous machine cluster, P sgi is the second transmission power of the i-th synchronous machine cluster, P grid(0) is the first tie line power, P grid is the second tie line power, X sgi is the cluster connection impedance of the i-th synchronous machine cluster, X grid is the synchronous connection impedance, Phvdc(0) is the first DC output power, P hvdc is the second DC output power.

[0037] Preferably, the second calculation module is further configured to calculate, according to the connection impedance data and the moment of inertia data, by using an inertia coefficient calculation formula, an inertia coefficient of virtual synchronous control; the inertia coefficient calculation formula is:

[0038]

[0039] In the formula, J is the inertia coefficient of virtual synchronous control, n is the total number of synchronous machine groups in the flexible DC transmission island system, X sgi is the machine group connection impedance of the i-th synchronous machine group, X grid is the synchronous connection impedance, J sgi is the machine group moment of inertia of the i-th synchronous machine group, J grid is the moment of inertia of the synchronous power grid.

[0040] On the other hand, a terminal device is provided, including a processor and a memory;

[0041] The memory is configured to store program codes and transmit the program codes to the processor;

[0042] The processor is configured to execute the virtual synchronous parameter adaptive method for the flexible DC transmission island system according to the instructions in the program codes.

[0043] As can be seen from the above technical solutions, the embodiments of the present application have the following advantages: The virtual synchronous parameter adaptive method, device and equipment for a flexible DC transmission islanding system. The method includes obtaining first power data, connection impedance data, moment of inertia data and second power data of a transmission line in the flexible DC transmission islanding system; calculating based on the first power data, connection impedance data and second power data to obtain a power conversion coefficient for virtual synchronous control in the flexible DC transmission islanding system; calculating based on the connection impedance data and moment of inertia data to obtain an inertia coefficient for virtual synchronous control; using the first DC output power of the first power data, the second DC output power of the second power data, the power conversion coefficient and the inertia coefficient as control parameters for virtual synchronous control to control the operation of the flexible DC transmission islanding system. The virtual synchronous parameter adaptive method for the flexible DC transmission islanding system calculates the power conversion coefficient and inertia coefficient for virtual synchronous control by calculating the obtained first power data, connection impedance data, moment of inertia data and second power data, and uses the first DC output power of the first power data, the second DC output power of the second power data, the power conversion coefficient and the inertia coefficient as control parameters for virtual synchronous control. The virtual synchronous control of the flexible DC transmission islanding system controls the operation of the flexible DC transmission islanding system according to these control parameters, avoiding the occurrence of power angle instability in the flexible DC transmission islanding system after a fault due to improper setting of the inertia time constant of the virtual synchronous control, and solving the technical problem that in the existing new energy weak grid-connected flexible DC transmission islanding system using virtual synchronous control, power angle instability is likely to occur after a fault due to improper setting of the inertia time constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0045] Figure 1 It is a flowchart of the steps of the virtual synchronous parameter adaptive method for the flexible DC transmission islanding system described in the embodiments of the present application;

[0046] Figure 2 It is a topological schematic diagram of the flexible DC transmission islanding system in the virtual synchronous parameter adaptive method for the flexible DC transmission islanding system described in the embodiments of the present application;

[0047] Figure 3 It is a framework schematic diagram of the virtual synchronous control of the flexible DC transmission islanding system in the virtual synchronous parameter adaptive method for the flexible DC transmission islanding system described in the embodiments of the present application;

[0048] Figure 4 It is a framework diagram of the virtual synchronous parameter adaptive device for the flexible DC transmission island system of the embodiment of the present application. Specific implementation manners

[0049] To make the invention objectives, features, and advantages of the present application more obvious and understandable, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the embodiments described below are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present application.

[0050] In the description of the embodiments of the present application, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present application, "a plurality of" means two or more, unless otherwise specifically defined.

[0051] In the embodiments of the present application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0052] The embodiments of the present application provide a virtual synchronous parameter adaptive method, device, and equipment for a flexible DC transmission island system, which are used to solve the technical problem that in the existing new energy weak grid-connected flexible DC transmission island system using virtual synchronous control, due to improper setting of the inertia time constant, power angle instability is likely to occur after a fault.

[0053] Embodiment 1:

[0054] Figure 1 It is a step flow chart of the virtual synchronous parameter adaptive method for the flexible DC transmission island system described in the embodiments of the present application. Figure 2 It is a topological schematic diagram of the flexible DC transmission island system in the virtual synchronous parameter adaptive method for the flexible DC transmission island system described in the embodiments of the present application. Figure 3It is a schematic diagram of the framework of the virtual synchronous control of the flexible DC transmission island system in the virtual synchronous parameter adaptive method of the flexible DC transmission island system described in the embodiments of the present application.

[0055] As Figure 1 shown, the embodiments of the present application provide a virtual synchronous parameter adaptive method for a flexible DC transmission island system, including the following steps:

[0056] S1. Obtain the first power data, connection impedance data, moment of inertia data, and second power data of the transmission line in the flexible DC transmission island system. The second power data is obtained by performing low-pass filtering on the transmission power of the transmission line in the flexible DC transmission island system.

[0057] It should be noted that in step S1, the data required to obtain the virtual synchronous parameters of the flexible DC transmission island system is obtained. The first power data includes the first output power, first DC output power, and first tie line power of each synchronous machine group. The second power data includes the second output power, second DC output power, and second tie line power of each synchronous machine group. The first tie line power and the second tie line power are both the tie line powers between the flexible DC transmission island system and the local synchronous power grid of the power system. The connection impedance data includes the machine group connection impedance and synchronous connection impedance of each synchronous machine group. The moment of inertia data includes the machine group moment of inertia and synchronous power grid moment of inertia of each synchronous machine group. In this embodiment, the transmission power on the transmission line of the flexible DC transmission island system is obtained at regular intervals as the first power data, and the transmission power on the transmission line of the flexible DC transmission island system is obtained in real time and low-pass filtered with a bandwidth less than 10 Hz to obtain each transmission power as the second power data.

[0058] In the embodiments of the present application, as Figure 2 shown, taking the flexible DC transmission island system with two synchronous machine groups as an example for the virtual synchronous parameter adaptive method of the flexible DC transmission island system, the obtained first power data includes the first output power P of synchronous machine group 1 sg1(0) , the first output power P of synchronous machine group 2 sg2(0) , the first DC output power P hvdc(0) and the first tie line power P grid(0) . The second power data includes the second output power P of synchronous machine group 1 sg1 , the second output power P of synchronous machine group 2 sg2 , the second DC output power P hvdc and the second tie line power P grid . The connection impedance data includes the machine group connection impedance X of synchronous machine group 1 sg1 , the machine group connection impedance X of synchronous machine group 2 sg2 and the synchronous connection impedance Xgrid , the moment of inertia data includes the group moment of inertia J of the synchronous machine group 1 sg1 , the group moment of inertia J of the synchronous machine group 2 sg2 and the moment of inertia J of the synchronous power grid grid .

[0059] S2. Calculate according to the first power data, the connection impedance data and the second power data to obtain the power conversion coefficient of the virtual synchronous control in the flexible DC transmission island system.

[0060] It should be noted that in step S2, the calculation is performed based on the data obtained in step S1 to obtain the power conversion coefficient of the virtual synchronous control in the flexible DC transmission island system.

[0061] S3. Calculate according to the connection impedance data and the moment of inertia data to obtain the inertia coefficient of the virtual synchronous control.

[0062] It should be noted that in step S3, the calculation is performed based on the data obtained in step S1 to obtain the inertia coefficient of the virtual synchronous control in the flexible DC transmission island system.

[0063] S4. Use the first DC output power of the first power data, the second DC output power of the second power data, the power conversion coefficient and the inertia coefficient as the control parameters of the virtual synchronous control to control the operation of the flexible DC transmission island system.

[0064] It should be noted that in step S4, the first DC output power, the second DC output power obtained in step S1, the power conversion coefficient calculated in step S2, and the inertia coefficient obtained in step S3 are used as the control parameters of the virtual synchronous control. The virtual synchronous control of the flexible DC transmission island system controls the operation of the flexible DC transmission island system according to these control parameters, avoiding the occurrence of power angle instability in the flexible DC transmission island system after a fault due to improper setting of the inertia time constant of the virtual synchronous control. In this embodiment, the virtual synchronous control of the virtual synchronous parameter adaptive method of the flexible DC transmission island system is executed according to the Figure 3 shown control structure.

[0065] A virtual synchronous parameter adaptive method for a flexible DC transmission islanding system provided by this application. This method includes obtaining the first power data, connection impedance data, moment of inertia data, and second power data of the transmission line in the flexible DC transmission islanding system; calculating based on the first power data, connection impedance data, and second power data to obtain the power conversion coefficient of virtual synchronous control in the flexible DC transmission islanding system; calculating based on the connection impedance data and moment of inertia data to obtain the inertia coefficient of virtual synchronous control; using the first DC output power of the first power data, the second DC output power of the second power data, the power conversion coefficient, and the inertia coefficient as the control parameters of virtual synchronous control to control the operation of the flexible DC transmission islanding system. The virtual synchronous parameter adaptive method of this flexible DC transmission islanding system calculates the power conversion coefficient and inertia coefficient of virtual synchronous control by calculating the obtained first power data, connection impedance data, moment of inertia data, and second power data, and uses the first DC output power of the first power data, the second DC output power of the second power data, the power conversion coefficient, and the inertia coefficient as the control parameters of virtual synchronous control. The virtual synchronous control of this flexible DC transmission islanding system controls the operation of this flexible DC transmission islanding system according to these control parameters, avoiding the occurrence of power angle instability in the flexible DC transmission islanding system after a fault due to improper setting of the inertia time constant of virtual synchronous control, and solving the technical problem that in the existing new energy weak grid-connected via a flexible DC transmission islanding system using virtual synchronous control, power angle instability is likely to occur after a fault due to improper setting of the inertia time constant.

[0066] In an embodiment of this application, calculating based on the first power data, connection impedance data, and second power data to obtain the power conversion coefficient of virtual synchronous control in the flexible DC transmission islanding system includes:

[0067] Calculating the first output power of each synchronous machine group and its corresponding second output power to obtain the output power difference of each synchronous machine group;

[0068] Calculating the first DC output power and the second DC output power to obtain the DC output power difference; calculating the first tie line power and the second tie line power to obtain the tie line power difference;

[0069] Calculating the output power difference of each synchronous machine group and its corresponding machine group connection impedance to obtain the first data of each synchronous machine group; calculating the tie line power difference and the synchronous connection impedance to obtain the second data;

[0070] Calculating all the first data, second data, and DC output power difference to obtain the power conversion coefficient of virtual synchronous control in the flexible DC transmission islanding system.

[0071] It should be noted that the difference in the transmitted power of each synchronous machine group is calculated by subtracting the second transmitted power corresponding to each synchronous machine group from the first transmitted power of each synchronous machine group. The difference in the DC output power is calculated by subtracting the second DC output power from the first DC output power. The difference in the tie-line power is calculated by subtracting the second tie-line power from the first tie-line power. The first data is calculated by multiplying the difference in the transmitted power of each synchronous machine group by the machine group tie impedance corresponding to each synchronous machine group. The second data is calculated by multiplying the difference in the tie-line power by the synchronous tie impedance. The power conversion coefficient is calculated by dividing the data obtained by adding all the first data and the second data by the difference in the DC output power.

[0072] In an embodiment of the present application, the virtual synchronous parameter adaptive method for the flexible DC transmission island system includes: calculating according to the first power data, the tie impedance data, and the second power data using the power conversion coefficient calculation formula to obtain the power conversion coefficient for virtual synchronous control in the flexible DC transmission island system. The power conversion coefficient calculation formula is:

[0073]

[0074] In the formula, K p is the power conversion coefficient, n is the total number of synchronous machine groups in the flexible DC transmission island system, P sgi(0) is the first transmitted power of the i-th synchronous machine group, P sgi is the second transmitted power of the i-th synchronous machine group, P grid(0) is the first tie-line power, P grid is the second tie-line power, X sgi is the machine group tie impedance of the i-th synchronous machine group, X grid is the synchronous tie impedance, P hvdc(0) is the first DC output power, P hvdc is the second DC output power.

[0075] It should be noted that the virtual synchronous parameter adaptive method for the flexible DC transmission island system takes the Figure 2 shown flexible DC transmission island system and calculates the power conversion coefficient for virtual synchronous control in the flexible DC transmission island system as:

[0076]

[0077] The synchronous machine groups for this calculated power conversion coefficient are two.

[0078] In an embodiment of the present application, calculating according to the tie impedance data and the moment of inertia data to obtain the inertia coefficient for virtual synchronous control includes:

[0079] Calculate the cluster connection impedance of each synchronous machine cluster and its corresponding cluster moment of inertia to obtain the first inertia data of each synchronous machine cluster;

[0080] Calculate the synchronous connection impedance and the synchronous power grid moment of inertia to obtain the second inertia data;

[0081] Calculate based on all the first inertia data and the second inertia data to obtain the inertia coefficient of the virtual synchronous control.

[0082] It should be noted that the first inertia data is calculated by multiplying the cluster connection impedance of a synchronous machine cluster by the cluster moment of inertia of that synchronous machine cluster. The second inertia data is calculated by multiplying the synchronous connection impedance by the synchronous power grid moment of inertia. The inertia coefficient of the virtual synchronous control is calculated by adding all the first inertia data and the second inertia data.

[0083] In an embodiment of the present application, the virtual synchronous parameter adaptive method for the flexible DC transmission island system includes: calculating according to the connection impedance data and the moment of inertia data using the inertia coefficient calculation formula to obtain the inertia coefficient of the virtual synchronous control; the inertia coefficient calculation formula is:

[0084]

[0085] In the formula, J is the inertia coefficient of the virtual synchronous control, n is the total number of synchronous machine clusters in the flexible DC transmission island system, X sgi is the cluster connection impedance of the i-th synchronous machine cluster, X grid is the synchronous connection impedance, J sgi is the cluster moment of inertia of the i-th synchronous machine cluster, J grid is the synchronous power grid moment of inertia.

[0086] It should be noted that the virtual synchronous parameter adaptive method for the flexible DC transmission island system takes the Figure 2 shown flexible DC transmission island system, and calculates the power conversion coefficient of the virtual synchronous control in the flexible DC transmission island system as: J hvdc = J sg1 X sg1 + J sg2 X sg2 + J grid X grid .

[0087] Embodiment 2:

[0088] Figure 4 This is the framework flowchart of the virtual synchronous parameter adaptive device for the flexible DC transmission island system described in the embodiment of the present application.

[0089] As Figure 4As shown in the figure, an embodiment of the present application provides a virtual synchronous parameter adaptive device for a flexible DC transmission island system, including a data acquisition module 10, a first calculation module 20, a second calculation module 30, and an execution control module 40;

[0090] The data acquisition module 10 is configured to acquire first power data, connection impedance data, moment of inertia data, and second power data of a transmission line in the flexible DC transmission island system, where the second power data is obtained by performing low-pass filtering on the transmission power of the transmission line in the flexible DC transmission island system;

[0091] The first calculation module 20 is configured to calculate, according to the first power data, the connection impedance data, and the second power data, to obtain a power conversion coefficient for virtual synchronous control in the flexible DC transmission island system;

[0092] The second calculation module 30 is configured to calculate, according to the connection impedance data and the moment of inertia data, to obtain an inertia coefficient for virtual synchronous control;

[0093] The execution control module 40 is configured to control the operation of the flexible DC transmission island system by using the first DC output power of the first power data, the second DC output power of the second power data, the power conversion coefficient, and the inertia coefficient as control parameters for virtual synchronous control.

[0094] In the embodiment of the present application, the first calculation module 20 is further configured to calculate, according to the first power data, the connection impedance data, and the second power data by using a power conversion coefficient calculation formula, to obtain a power conversion coefficient for virtual synchronous control in the flexible DC transmission island system, and the power conversion coefficient calculation formula is:

[0095]

[0096] In the formula, K p is the power conversion coefficient, n is the total number of synchronous machine groups in the flexible DC transmission island system, P sgi(0) is the first output power of the i-th synchronous machine group, P sgi is the second output power of the i-th synchronous machine group, P grid(0) is the first tie line power, P grid is the second tie line power, X sgi is the machine group connection impedance of the i-th synchronous machine group, X grid is the synchronous connection impedance, P hvdc(0) is the first DC output power, P hvdc is the second DC output power.

[0097] In the embodiment of the present application, the second calculation module 30 is further configured to calculate the inertia coefficient of the virtual synchronous control according to the connection impedance data and the moment of inertia data by using an inertia coefficient calculation formula; the inertia coefficient calculation formula is:

[0098]

[0099] In the formula, J is the inertia coefficient of the virtual synchronous control, n is the total number of synchronous machine groups in the flexible DC transmission island system, X sgi is the connection impedance of the i-th synchronous machine group, X grid is the synchronous connection impedance, J sgi is the moment of inertia of the i-th synchronous machine group, J grid is the moment of inertia of the synchronous power grid.

[0100] It should be noted that the modules in the device of the second embodiment correspond to the steps in the method of the first embodiment. The content of the virtual synchronous parameter adaptive method for the flexible DC transmission island system has been described in detail in the first embodiment, and the content of the modules in the device will not be described in detail in the second embodiment.

[0101] Embodiment Three:

[0102] The embodiment of the present application provides a terminal device, including a processor and a memory;

[0103] The memory is used to store program codes and transmit the program codes to the processor;

[0104] The processor is configured to execute the above-mentioned virtual synchronous parameter adaptive method for the flexible DC transmission island system according to the instructions in the program codes.

[0105] It should be noted that the processor is configured to execute the steps in the above-mentioned embodiment of the virtual synchronous parameter adaptive method for a flexible DC transmission island system according to the instructions in the program codes. Alternatively, when the processor executes a computer program, it implements the functions of each module / unit in the above-mentioned system / device embodiments.

[0106] Exemplarily, the computer program can be divided into one or more modules / units. One or more modules / units are stored in the memory and executed by the processor to complete the present application. One or more modules / units can be a series of computer program instruction segments capable of performing specific functions, and these instruction segments are used to describe the execution process of the computer program in the terminal device.

[0107] The terminal device can be a computing device such as a desktop computer, a notebook, a palm computer, and a cloud server. The terminal device may include, but is not limited to, a processor and a memory. Those skilled in the art can understand that this does not constitute a limitation on the terminal device, and it may include more or fewer components than shown in the figure, or combine certain components, or different components. For example, the terminal device may also include input / output devices, network access devices, a bus, etc.

[0108] The so-called processor may be a central processing unit (CPU), or may also be other general-purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0109] The memory may be an internal storage unit of the terminal device, such as the hard disk or memory of the terminal device. The memory may also be an external storage device of the terminal device, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the terminal device. Further, the memory may also include both the internal storage unit and the external storage device of the terminal device. The memory is used to store computer programs and other programs and data required by the terminal device. The memory may also be used to temporarily store data that has been output or is to be output.

[0110] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, devices, and units described above may refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0111] In several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there can be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection between each other can be through some interfaces, and the indirect coupling or communication connection of the device or unit can be in electrical, mechanical, or other forms.

[0112] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0113] In addition, each functional unit in various embodiments of this application can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0114] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this application. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0115] As described above, the above embodiments are only used to illustrate the technical solution of this application and are not intended to limit it; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of various embodiments of this application.

Claims

1. A virtual synchronous parameter adaptive method for a flexible DC transmission islanding system, characterized in that Including the following steps: Obtain the first power data, connection impedance data, moment of inertia data, and second power data of the transmission line in the flexible DC transmission island system. The second power data is obtained by performing low-pass filtering on the transmission power of the transmission line in the flexible DC transmission island system; Calculate based on the first power data, the connection impedance data, and the second power data to obtain the power conversion coefficient of the virtual synchronous control in the flexible DC transmission island system; Calculate based on the connection impedance data and the moment of inertia data to obtain the inertia coefficient of the virtual synchronous control; Use the first DC output power of the first power data, the second DC output power of the second power data, the power conversion coefficient, and the inertia coefficient as the control parameters of the virtual synchronous control to control the operation of the flexible DC transmission island system; The first power data includes the first power output, the first DC output power, and the first tie-line power of each synchronous machine group. The second power data includes the second power output, the second DC output power, and the second tie-line power of each synchronous machine group. Both the first tie-line power and the second tie-line power are the tie-line powers between the flexible DC transmission island system and the local synchronous power grid of the power system. The connection impedance data includes the group connection impedance and the synchronous connection impedance of each synchronous machine group. The moment of inertia data includes the group moment of inertia and the synchronous power grid moment of inertia of each synchronous machine group; Calculating based on the first power data, the connection impedance data, and the second power data to obtain the power conversion coefficient of the virtual synchronous control in the flexible DC transmission island system includes: Calculate the first power output of each synchronous machine group and its corresponding second power output to obtain the power output difference of each synchronous machine group; Calculate the first DC output power and the second DC output power to obtain the DC output power difference; calculate the first tie-line power and the second tie-line power to obtain the tie-line power difference; Calculate the power output difference of each synchronous machine group and its corresponding group connection impedance to obtain the first data of each synchronous machine group; calculate the tie-line power difference and the synchronous connection impedance to obtain the second data; Calculate all the first data, the second data, and the DC output power difference to obtain the power conversion coefficient of the virtual synchronous control in the flexible DC transmission island system; Calculating based on the connection impedance data and the moment of inertia data to obtain the inertia coefficient of the virtual synchronous control includes: Calculate the group connection impedance of each synchronous machine group and its corresponding group moment of inertia to obtain the first inertia data of each synchronous machine group; Calculate the synchronous connection impedance and the synchronous power grid moment of inertia to obtain the second inertia data; Calculate based on all the first inertia data and the second inertia data to obtain the inertia coefficient of the virtual synchronous control.

2. The virtual synchronous parameter adaptive method for the flexible DC transmission island system according to claim 1, wherein Including: Calculate according to the first power data, the connection impedance data, and the second power data using the power conversion coefficient calculation formula to obtain the power conversion coefficient of virtual synchronous control in the flexible DC transmission island system. The power conversion coefficient calculation formula is: Where K p is the power conversion coefficient, n is the total number of synchronous machine groups in the flexible DC transmission island system, P sgi(0) is the first transmission power of the i-th synchronous machine group, P sgi is the second transmission power of the i-th synchronous machine group, P grid(0) is the first tie line power, P grid is the second tie line power, X sgi is the machine group tie impedance of the i-th synchronous machine group, X grid is the synchronous tie impedance, P hvdc(0) is the first DC output power, P hvdc is the second DC output power.

3. The virtual synchronous parameter adaptive method for the flexible DC transmission island system according to claim 1, characterized in that Including: Calculate according to the connection impedance data and the moment of inertia data using the inertia coefficient calculation formula to obtain the inertia coefficient of virtual synchronous control; The inertia coefficient calculation formula is: Wherein, J is the inertia coefficient of virtual synchronous control, n is the total number of synchronous machine groups in the flexible DC transmission islanding system, X sgi is the group connection impedance of the i-th synchronous machine group, X grid is the synchronous connection impedance, J sgi is the group moment of inertia of the i-th synchronous machine group, J grid is the moment of inertia of the synchronous power grid.

4. A virtual synchronous parameter adaptive device for a flexible DC transmission islanding system, characterized in that, It includes a data acquisition module, a first calculation module, a second calculation module, and an execution control module; The data acquisition module is used to acquire the first power data, connection impedance data, moment of inertia data, and second power data of the transmission line in the flexible DC transmission island system. The second power data is obtained by performing low-pass filtering on the transmission power of the transmission line in the flexible DC transmission island system; The first calculation module is used to calculate according to the first power data, the connection impedance data, and the second power data to obtain the power conversion coefficient of virtual synchronous control in the flexible DC transmission island system; The second calculation module is used to calculate according to the connection impedance data and the moment of inertia data to obtain the inertia coefficient of virtual synchronous control; The execution control module is used to control the operation of the flexible DC transmission island system according to the first DC output power of the first power data, the second DC output power of the second power data, the power conversion coefficient, and the inertia coefficient as the control parameters of virtual synchronous control; The first calculation module is also used to calculate according to the first power data, the connection impedance data, and the second power data using the power conversion coefficient calculation formula to obtain the power conversion coefficient of virtual synchronous control in the flexible DC transmission island system. The power conversion coefficient calculation formula is: Where K p is the power conversion coefficient, n is the total number of synchronous machine groups in the flexible DC transmission island system, P sgi(0) is the first transmission power of the i-th synchronous machine group, P sgi is the second transmission power of the i-th synchronous machine group, P grid(0) is the first tie-line power, P grid is the second tie-line power, X sgi is the machine group tie impedance of the i-th synchronous machine group, X grid is the synchronous tie impedance, P hvdc(0) is the first DC output power, P hvdc is the second DC output power; The second calculation module is also used to calculate according to the connection impedance data and the moment of inertia data using the inertia coefficient calculation formula to obtain the inertia coefficient of virtual synchronous control; The inertia coefficient calculation formula is: Where, J is the inertia coefficient of virtual synchronous control, n is the total number of synchronous machine groups in the flexible DC transmission island system, X sgi is the group connection impedance of the i-th synchronous machine group, X grid is the synchronous connection impedance, J sgi is the group moment of inertia of the i-th synchronous machine group, J grid is the moment of inertia of the synchronous power grid.

5. A terminal device, characterized in that, It includes a processor and a memory; The memory is used to store program codes and transmit the program codes to the processor; The processor is used to execute the virtual synchronous parameter adaptive method of the flexible DC transmission island system according to the instructions in the program codes as described in any one of claims 1-3.

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