Loss determination method, apparatus, device, storage medium, and program product

Abstract

The application relates to a loss determination method, device, equipment, storage medium and program product. The method comprises the following steps: obtaining a preset number of target bridge arm current values in a sampling period of a bridge arm current of a flexible DC converter valve; obtaining the loss of each component in the flexible DC converter valve according to the target bridge arm current values; obtaining the loss of a half-bridge sub-module in the flexible DC converter valve according to the loss of each component; and determining the target loss of the flexible DC converter valve according to the loss of the half-bridge sub-module. The loss determination method adopts a limited sampling mode to obtain the bridge arm current, so that the accuracy of the determined loss of the flexible DC converter valve is relatively high.

Description

Technical Field

[0001] The present application relates to the field of electrical technology, and in particular to a loss determination method, apparatus, device, storage medium, and program product. Background Art

[0002] With the development of the electrical industry, flexible DC converter valves based on modular multi-level converters (MMCs) have received extensive attention and research due to their excellent output characteristics and low switching losses.

[0003] During the transmission and distribution of electrical energy, each grid component incurs a certain amount of active power and energy losses. Loss assessment is particularly important in HVDC Flexible systems, and therefore, loss analysis of HVDC Flexible converter valves is a crucial step in valve design. Existing techniques typically use analytical algorithms to assess HVDC Flexible converter valve losses. For example, the average arm current in the HVDC Flexible converter valve is obtained and used to estimate the losses.

[0004] However, the current loss calculation method described above has the problem of low accuracy of loss assessment results. Summary of the Invention

[0005] Based on this, it is necessary to provide a loss determination method, device, equipment, storage medium and program product that can improve the accuracy of loss assessment results in response to the above technical problems.

[0006] In a first aspect, the present application provides a method for determining loss. The method comprises:

[0007] Acquiring a preset number of target bridge arm current values ​​within a sampling period of the bridge arm current of the flexible DC converter valve;

[0008] Obtaining the loss of each component in the flexible DC converter valve according to the target bridge arm current value;

[0009] Obtaining the loss of the half-bridge submodule in the flexible DC converter valve according to the loss of each of the components;

[0010] The target loss of the flexible DC converter valve is determined according to the loss of the half-bridge submodule.

[0011] In one embodiment, obtaining a preset number of target bridge arm current values ​​within a sampling period of the bridge arm current of the flexible DC converter valve includes:

[0012] Acquiring recorded data of the HVDC Flexible converter valve and historical operating condition information corresponding to the recorded data;

[0013] The preset number of target bridge arm current values ​​are determined according to the historical operating condition information, the current operating condition information of the flexible DC converter valve and the recorded data.

[0014] In one embodiment, determining the preset number of target bridge arm current values ​​according to the historical operating condition information, the current operating condition information of the flexible DC converter valve, and the recorded data includes:

[0015] Determining whether the historical operating condition information is consistent with the current operating condition information;

[0016] If they are consistent, determining the preset number of target bridge arm current values ​​from the recorded data;

[0017] If they are inconsistent, the first bridge arm current value corresponding to the historical operating condition information is calculated based on the recorded data, and the target bridge arm current value is obtained according to the first bridge arm current value and the second bridge arm current value in the recorded data.

[0018] In one embodiment, obtaining the target bridge arm current value according to the first bridge arm current value and the second bridge arm current value in the recorded data includes:

[0019] If the current difference between the first bridge arm current value and the second bridge arm current value is less than a preset threshold, obtaining the target bridge arm current value according to the current operating condition information and the bridge arm current calculation method;

[0020] If the current difference between the first bridge arm current value and the second bridge arm current value is greater than or equal to the preset threshold, a correction coefficient is determined based on the current difference, and the target bridge arm current value is obtained based on the correction coefficient, the current operating condition information and the bridge arm current calculation method.

[0021] In one embodiment, the current operating condition information includes the apparent power, DC voltage, and fundamental frequency of each submodule in the flexible DC converter valve at each sampling moment; and obtaining the target bridge arm current value according to the current operating condition information and a bridge arm current calculation method includes:

[0022] determining a DC current component of the bridge arm current according to the apparent power and the DC voltage at each sampling moment;

[0023] determining an AC current of each phase in the submodule according to the apparent power, the DC voltage, and the fundamental frequency;

[0024] The target bridge arm current value is determined according to the direct current component and the alternating current.

[0025] In one embodiment, the components in the HVDC flexible converter valve include insulated gate bipolar transistors (IGBTs) and diodes; and obtaining the loss of each component in the HVDC flexible converter valve according to the target bridge arm current value includes:

[0026] Determining the average on-state loss and switching loss of the IGBT according to the preset number of target bridge arm current values;

[0027] The average conduction loss and reverse recovery loss of the diode are determined according to the preset number of target bridge arm current values.

[0028] In one embodiment, the switching loss includes turn-on loss and turn-off loss; and determining the average on-state loss and switching loss of the IGBT according to the preset number of target bridge arm current values ​​comprises:

[0029] Determining a first voltage corresponding to each target bridge arm current value according to an output characteristic curve of the IGBT, and determining an average on-state loss of the IGBT according to each target bridge arm current value and the corresponding first voltage;

[0030] According to the switching loss characteristic curve of the IGBT, the turn-on loss and turn-off loss corresponding to each target bridge arm current value are determined, and the turn-on loss and turn-off loss of the IGBT within the sampling period are determined according to the turn-on loss, the turn-off loss and the first switching number corresponding to each target bridge arm current value.

[0031] In one embodiment, determining the average conduction loss and reverse recovery loss of the diode according to the preset number of target bridge arm current values ​​includes:

[0032] Determining a second voltage corresponding to each target bridge arm current value according to an output characteristic curve of the diode, and determining an average conduction loss of the diode according to each target bridge arm current value and the corresponding second voltage;

[0033] According to the reverse loss characteristic curve of the diode, the reverse recovery loss corresponding to each target bridge arm current value is determined, and the reverse recovery loss of the diode is determined according to the reverse recovery loss corresponding to each target bridge arm current value and the second switching number.

[0034] In one embodiment, obtaining the loss of the half-bridge submodule in the flexible DC converter valve according to the loss of each component includes:

[0035] Determining the average on-state loss of the half-bridge submodule in the flexible DC converter valve according to the average on-state loss of the IGBT and the average on-state loss of the diode;

[0036] The switching loss of the half-bridge sub-module is determined according to the switching loss of the IGBT and the reverse recovery loss of the diode.

[0037] In one embodiment, determining the target loss of the flexible DC converter valve according to the loss of the half-bridge submodule includes:

[0038] Determining the total loss of the half-bridge submodule according to the average on-state loss of the half-bridge submodule and the switching loss of the half-bridge submodule;

[0039] Determining the total loss of the full-bridge submodule according to the total loss of the half-bridge submodule;

[0040] determining an initial loss according to the total loss of the half-bridge submodule, the number of the half-bridge submodules, the total loss of the full-bridge submodule, and the number of the full-bridge submodules;

[0041] A target loss of the flexible DC converter valve is determined according to the initial loss and the fundamental frequency.

[0042] In a second aspect, the present application further provides a loss determination device. The device comprises:

[0043] A first acquisition module is configured to acquire a preset number of target bridge arm current values ​​within a sampling period of the bridge arm current of the flexible DC converter valve;

[0044] a second acquisition module, configured to acquire the loss of each component in the flexible DC converter valve according to the target bridge arm current value;

[0045] a third acquisition module, configured to acquire the loss of the half-bridge submodule in the flexible DC converter valve according to the loss of each component;

[0046] A determination module is used to determine the target loss of the flexible DC converter valve according to the loss of the half-bridge sub-module.

[0047] In a third aspect, the present application further provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the loss determination method as described in any embodiment of the first aspect is implemented.

[0048] In a fourth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the loss determination method as described in any embodiment of the first aspect.

[0049] In a fifth aspect, the present application further provides a computer program product, comprising a computer program, which, when executed by a processor, implements the loss determination method as described in any embodiment of the first aspect.

[0050] The aforementioned loss determination method, apparatus, device, storage medium, and program product obtain a preset number of target arm current values ​​within a sampling period of the arm current of the flexible DC converter valve, obtain the losses of each component in the flexible DC converter valve based on the target arm current values, obtain the losses of the half-bridge submodule in the flexible DC converter valve based on the losses of each component, and determine the target loss of the flexible DC converter valve based on the losses of the half-bridge submodule. In the embodiments of the present application, since multiple target arm current values ​​are obtained within the sampling period of the arm current of the flexible DC converter valve, a finite sampling method is used to obtain multiple arm current values ​​within the sampling period of the arm current, and the component losses are calculated based on the multiple arm current values ​​distributed at different times during the sampling period, ultimately obtaining the target loss of the flexible DC converter valve. Compared to the prior art method that uses a single average current value, the loss determination method of the present application takes into account multiple arm current values ​​within the sampling period, which is more consistent with the operating conditions of the flexible DC converter valve. Therefore, the obtained loss of the flexible DC converter valve is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 A diagram illustrating an application environment of a loss determination method according to an embodiment;

[0052] Figure 2 is a flow chart of a loss determination method according to an embodiment;

[0053] Figure 3 A schematic diagram of a process for obtaining a preset number of target bridge arm current values ​​in one embodiment;

[0054] Figure 4 A schematic diagram of a flow chart for determining a preset number of target bridge arm current values ​​in another embodiment;

[0055] Figure 5 A schematic diagram of a process for determining a target bridge arm current value in one embodiment;

[0056] Figure 6 A schematic diagram of a process for obtaining a target bridge arm current value in another embodiment;

[0057] Figure 7 A schematic flow chart of a method for obtaining the loss of each component in one embodiment;

[0058] Figure 8 A schematic flow chart of a method for determining IGBT losses in one embodiment;

[0059] Figure 9 Schematic diagram of an output characteristic curve of an IGBT in one embodiment;

[0060] Figure 10 A schematic diagram of an output characteristic fitting curve of an IGBT in one embodiment;

[0061] Figure 11 Schematic diagram of turn-on / turn-off loss curve of IGBT in one embodiment;

[0062] Figure 12 Schematic diagram of turn-on / turn-off loss fitting curve of IGBT in one embodiment;

[0063] Figure 13 A schematic flow chart of a method for determining diode loss in one embodiment;

[0064] Figure 14 FIG1 is a flow chart of a method for determining the loss of a half-bridge sub-module in one embodiment;

[0065] Figure 15 A schematic flow chart of a method for determining target loss in one embodiment;

[0066] Figure 16 Schematic diagram of the main components and structure of a loss determination method in one embodiment;

[0067] Figure 17 is a flow chart of a loss determination method according to an embodiment;

[0068] Figure 18 is a structural diagram of a loss determination device in one embodiment;

[0069] Figure 19 A structural diagram of a loss determination device in another embodiment;

[0070] Figure 20 FIG. 1 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0071] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0072] With the development of high-voltage direct current (VSC-HVDC) systems using IGBTs to form voltage source converters, different forms and modulation methods of converter valves have continued to emerge. MMC's flexible DC converter valve has received extensive attention and research due to its excellent output characteristics and low switching losses. During the transmission and distribution of electric energy, each component of the power grid will generate a certain amount of active power loss and electric energy loss, such as heat generation, which shortens the life of electrical components and reduces safety factors, resulting in economic losses and energy waste. In flexible DC transmission systems, converter valves are one of the key devices of flexible DC transmission. Accurate loss analysis of flexible DC converter valves can guide efficiency optimization, component selection and heat sink design, and is an important step in converter valve design.

[0073] However, direct measurement of converter valve losses is difficult due to the closed structure of the converter valve and the limited accuracy of the measurement equipment. While the currently used analytical algorithms offer simplicity and rapid computation, they use the average value of the bridge arm current as input, resulting in low accuracy and inability to accurately calculate losses over long periods of time and under varying operating conditions.

[0074] The loss determination method provided in the embodiment of the present application can be applied to Figure 1 In the application environment shown. Figure 1 A computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 1 As shown. The computer device includes a processor, memory, and a network interface connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The database of the computer device is used to store data involved in the loss determination method. The network interface of the computer device is used to communicate with an external terminal via a network connection. When executed by the processor, the computer program implements a loss determination method.

[0075] In one embodiment, Figure 2 As shown, a loss determination method is provided, which is applied to Figure 1 The computer device in the example is used to illustrate the process, including the following steps:

[0076] S201: Acquire a preset number of target bridge arm current values ​​within a sampling period of a bridge arm current of a flexible DC converter valve.

[0077] The arm current may be a unidirectional arm current in the HVDC Flexible converter valve, and the sampling period may be a sinusoidal period of the arm current. The preset number may be determined based on actual needs, for example, 100, 150, 200, etc., and is not limited in the embodiments of this application. The target arm current value may be an actual measured current value or a current value calculated based on device parameters of the HVDC Flexible converter valve.

[0078] In this embodiment, during the operation of the flexible DC converter valve, a limited number of samplings can be performed within a sampling period of the bridge arm current to obtain a preset number of target bridge arm current values. For example, the bridge arm current can be actually detected during the operation of the flexible DC converter valve to obtain multiple target bridge arm current values. Alternatively, the voltage and resistance of the bridge arm can be obtained during the operation of the flexible DC converter valve, and the target bridge arm current value can be calculated based on the voltage and resistance. Alternatively, when the current operating condition of the flexible DC converter valve is consistent with the historical operating condition, the target bridge arm current value can be determined from recorded data corresponding to the historical operating condition of the flexible DC converter valve.

[0079] S202: Obtain the loss of each component in the flexible DC converter valve according to the target bridge arm current value.

[0080] The components in the HVDC Flexible converter valve may include IGBTs, diodes, etc., and component losses refer to losses incurred by the IGBTs and diodes during operation of the HVDC Flexible converter valve. Optionally, IGBT losses may include IGBT conduction losses and switching losses, and diode losses may include diode conduction losses and reverse recovery losses.

[0081] In this embodiment, the loss of each component can be calculated based on the target bridge arm current value. For example, for the loss of an IGBT, the voltage of the IGBT can be determined based on the output characteristic curve of the IGBT and the target bridge arm current value, and the loss of the IGBT can be calculated based on the target bridge arm current value and the voltage of the IGBT; alternatively, the loss of the IGBT can be determined based on the switching loss curve of the IGBT and the target bridge arm current value; alternatively, for a diode, the voltage of the diode can be determined based on the output characteristic curve of the diode and the target bridge arm current value, and the loss of the diode can be calculated based on the target bridge arm current value and the voltage of the diode; alternatively, the conduction loss power and reverse recovery loss energy of the diode can be determined based on the loss curve of the diode and the target bridge arm current value, and the loss of the diode can be calculated based on the conduction loss power and reverse recovery loss energy of the diode, which are not limited in the embodiments of the present application.

[0082] S203 : Obtain the loss of the half-bridge submodule in the flexible DC converter valve according to the loss of each component.

[0083] Among them, MMC is composed of multiple cascaded sub-modules (SM) with the same structure. The structure of the sub-module can be divided into three types: half H-bridge type, full H-bridge type and double-clamp sub-module type. The half-bridge sub-module refers to the half-bridge composed of sub-modules in the MMC.

[0084] In this embodiment, after obtaining the losses of the aforementioned components, since each submodule is composed of one or more components, the loss of each submodule can be calculated based on the losses of each component. For example, the losses of the components that make up the submodule can be added together to obtain the submodule loss, or the losses of the components that make up the submodule can be multiplied by a certain proportionality factor and then added together to obtain the submodule loss. Furthermore, after calculating the loss of each submodule, the loss of the half-bridge submodule can be determined based on the losses of the submodules that make up the half-bridge.

[0085] S204: Determine the target loss of the flexible DC converter valve according to the loss of the half-bridge sub-module.

[0086] The target loss refers to the overall loss of the flexible DC converter valve.

[0087] In this embodiment, the flexible DC converter valve includes a full-bridge submodule and a half-bridge submodule. Analysis of the steady-state operating path of the full-bridge module reveals that, at any given moment, the full-bridge submodule has twice as many components in its path as the half-bridge submodule. Therefore, the device losses in the full-bridge structure are twice the losses in the half-bridge structure. Therefore, after determining the losses of the half-bridge submodules, the losses of the half-bridge submodules that comprise the full bridge can be summed to obtain the losses of the full-bridge submodule. The target losses of the flexible DC converter valve can then be determined based on the losses of the full-bridge submodules. Alternatively, if the full bridge is symmetrical, meaning that each half-bridge comprising the full bridge has the same structure, the losses of each half-bridge submodule are also identical. The losses of the half-bridge submodules can be multiplied by the number of half-bridge submodules to obtain the losses of the full-bridge submodule. The target losses of the flexible DC converter valve can then be determined based on the losses of the full-bridge submodules. Alternatively, after determining the total losses of the full-bridge submodules, the target losses can be determined based on the losses of the full-bridge submodules and the losses of the half-bridge submodules.

[0088] The loss determination method provided in an embodiment of the present application obtains a preset number of target arm current values ​​within a sampling period of the arm current of a flexible DC converter valve, obtains the losses of each component in the flexible DC converter valve based on the target arm current values, obtains the losses of a half-bridge submodule in the flexible DC converter valve based on the losses of each component, and determines the target loss of the flexible DC converter valve based on the losses of the half-bridge submodule. In the embodiment of the present application, multiple target arm current values ​​are obtained within the sampling period of the arm current of the flexible DC converter valve, and a finite sampling method is used to obtain multiple arm current values ​​within the sampling period of the arm current. The component losses are calculated based on the multiple arm current values ​​distributed at different times during the sampling period, and the target loss of the flexible DC converter valve is ultimately obtained. Compared to the prior art method that uses a single current value, namely the average current value, the loss determination method of the present application takes into account multiple arm current values ​​within the sampling period, which is more consistent with the operating conditions of the flexible DC converter valve. Therefore, the loss determination method of the flexible DC converter valve is more accurate.

[0089] Further, in Figure 2 Based on the embodiment shown, the target bridge arm current value can be determined according to the operating conditions, such as Figure 3 As shown, step S201: "obtaining a preset number of target bridge arm current values ​​within a sampling period of the bridge arm current of the flexible DC converter valve" may include the following steps:

[0090] S301: Obtain recorded data of a flexible DC converter valve and historical operating condition information corresponding to the recorded data.

[0091] Among them, the recorded data can be the current, resistance, voltage and other information corresponding to the historical operating conditions of the flexible DC converter valve. The historical operating condition information can include the operating power, DC voltage, AC voltage, switching element frequency, component junction temperature and other information corresponding to the flexible DC converter valve under the historical operating conditions.

[0092] In this embodiment, the recorded data of the flexible DC converter valve can be obtained based on the recording of various data generated during the operation process in an actual project. For example, the data can be recorded and obtained through a recorder, or can be obtained through a current sensor, voltage sensor, etc.

[0093] S302: Determine a preset number of target bridge arm current values ​​based on historical operating condition information, current operating condition information, and recorded waveform data of the flexible DC converter valve.

[0094] The current operating conditions may include information such as operating power, DC voltage, AC voltage, switching element frequency, and component junction temperature corresponding to the flexible DC converter valve under historical operating conditions.

[0095] In this embodiment, the historical operating condition information and the current operating condition information can be compared to determine whether the historical operating condition and the current operating condition are consistent. If the historical operating condition and the current operating condition are consistent, a preset number of target bridge arm current values ​​can be determined directly from the bridge arm current of the recorded data collected under the historical operating condition; or if the historical operating condition and the current operating condition are inconsistent, the bridge arm current value under the current operating condition is calculated using the current operating condition information to determine the preset number of target bridge arm current values.

[0096] The embodiments of the present application provide a method for determining target arm current values ​​based on operating conditions. This method obtains recorded data of a flexible DC converter valve and historical operating condition information corresponding to the recorded data. Based on the historical operating condition information, current operating condition information, and the recorded data, a preset number of target arm current values ​​are determined. This embodiment of the present application considers the arm current values ​​of the flexible DC converter valve based on different operating condition information, thereby achieving a higher degree of accuracy in the determined target arm current values.

[0097] Alternatively, as Figure 4 As shown, step S302: "Determining a preset number of target bridge arm current values ​​based on historical operating condition information, current operating condition information of the flexible DC converter valve, and recorded data" may include the following steps:

[0098] S401. Determine whether the historical operating condition information is consistent with the current operating condition information; if the historical operating condition information is consistent with the current operating condition information, execute step S402; if the historical operating condition information is inconsistent with the current operating condition information, execute step S403.

[0099] In this embodiment, whether the information is consistent can be determined by comparing the historical operating condition information and the current operating condition information one by one. If they are completely consistent, they are considered consistent; alternatively, the similarity between the historical operating condition information and the current operating condition information can be calculated. If the similarity is greater than a similarity threshold, they are considered consistent. For example, the similarity threshold is 95%, 90%, etc.

[0100] S402: Determine a preset number of target bridge arm current values ​​from the recorded data of the flexible DC converter valve.

[0101] In this embodiment, if the historical operating condition information is consistent with the current operating condition information, it means that the historical operating condition and the current operating condition are the same. Then, the bridge arm current value under the historical operating condition can also be considered to be equivalent to the bridge arm current value under the current operating condition. Therefore, the bridge arm current value of the recorded data of the flexible DC converter valve can be used as the input bridge arm current value to obtain a preset number of target bridge arm current values.

[0102] S403 : Calculate a first bridge arm current value corresponding to historical operating condition information based on the recorded data of the flexible DC converter valve, and obtain a target bridge arm current value according to the first bridge arm current value and a second bridge arm current value in the recorded data.

[0103] In this embodiment, if the historical operating condition information and the current operating condition information are inconsistent, it means that the historical operating condition and the current operating condition are different. Then, the first bridge arm current value can be calculated based on the historical operating condition information corresponding to the recording data of the flexible DC converter valve and the calculation method of the bridge arm current, and the first bridge arm current value and the second bridge arm current value in the recording data of the flexible DC converter valve are compared, and whether the calculation method of the bridge arm current is accurate is determined based on the comparison result; alternatively, the current difference between the first bridge arm current value and the second bridge arm current value can be calculated, and whether the calculation method of the bridge arm current is accurate is determined based on the current difference. If the calculation method of the bridge arm current is inaccurate, the calculation method of the bridge arm current can be further corrected so that the bridge arm current calculated according to the corrected bridge arm current calculation method is more accurate.

[0104] Optionally, if the current difference between the first bridge arm current value and the second bridge arm current value is less than a preset threshold, the target bridge arm current value is obtained based on the current operating condition information and the bridge arm current calculation method; if the current difference between the first bridge arm current value and the second bridge arm current value is greater than or equal to the preset threshold, the correction coefficient is determined based on the current difference, and the target bridge arm current value is obtained based on the correction coefficient, the current operating condition information and the bridge arm current calculation method.

[0105] The preset threshold value can be determined according to the accuracy requirement of the flexible DC converter valve. For example, the preset threshold value can be 10e -5 .

[0106] In this example, if the current difference between the first bridge arm current value and the second bridge arm current value is less than a preset threshold, it indicates that the error between the first bridge arm current value and the second bridge arm current value is relatively small, proving that the bridge arm current calculation method is accurate, and the bridge arm current value can be directly calculated based on the bridge arm current calculation method. If the current difference between the first bridge arm current value and the second bridge arm current value is greater than or equal to the preset threshold, it indicates that the bridge arm current calculation method is inaccurate, and the bridge arm current calculation method can be corrected based on the current difference, and the bridge arm current can be calculated based on the corrected bridge arm current calculation method.

[0107] Furthermore, if Figure 5 As shown, the method for determining the target bridge arm current value may include the following steps:

[0108] S501. Input historical operating condition information, current operating condition information, and recorded data under historical operating condition information.

[0109] S502. Determine whether the historical operating condition information is consistent with the current operating condition information; if the historical operating condition information is consistent with the current operating condition information, execute step S503; if the historical operating condition information is inconsistent with the current operating condition information, execute step S504.

[0110] S503 : Calculate the loss by taking the second bridge arm current value of the recorded data under the historical operating condition information as the target bridge arm current value.

[0111] S504 : Calculate a first bridge arm current value corresponding to historical operating condition information according to a bridge arm current calculation method.

[0112] S505. Determine whether the current difference between the first bridge arm current value corresponding to the historical operating condition information and the second bridge arm current value of the recorded data under the historical operating condition information is less than a preset error threshold. If it is less than the error threshold, execute step S506; if it is greater than or equal to the error threshold, execute step S507.

[0113] S506 , calculating the bridge arm current value under the current operating condition according to the bridge arm current calculation method, taking the bridge arm current value as the target bridge arm current value, and performing loss calculation.

[0114] S507 , calibrating the bridge arm current calculation method, and then calculating the bridge arm current value under the current operating condition according to the calibrated bridge arm current calculation method, taking the bridge arm current value as the target bridge arm current value, and performing loss calculation.

[0115] In an embodiment of the present application, a determination is made as to whether the historical operating condition information and the current operating condition information are consistent. If so, a preset number of target bridge arm current values ​​are determined from the waveform data of the flexible DC converter valve. If not, a first bridge arm current value corresponding to the historical operating condition information is calculated based on the waveform data of the flexible DC converter valve, and then the target bridge arm current value is obtained based on the first bridge arm current value and the second bridge arm current value in the waveform data. In this embodiment of the present application, because the first bridge arm current value calculated under the historical operating condition is compared and corrected with the second bridge arm current value from the waveform data under the historical operating condition, the accuracy of the preset number of target bridge arm current values ​​required for subsequent calculations is further improved.

[0116] Furthermore, the current operating condition information includes the apparent power, DC voltage and fundamental frequency of each submodule in the flexible DC converter valve at each sampling moment; Figure 6 As shown, the step of "obtaining the target bridge arm current value according to the current operating condition information and the bridge arm current calculation method" includes the following steps:

[0117] S601 : Determine the DC current component of the bridge arm current according to the apparent power and the DC voltage at each sampling moment.

[0118] In this embodiment, the DC current component of the bridge arm current can be calculated according to formula (1).

[0119]

[0120] Where, I dc is the DC current component of the bridge arm current, in A; S mmc is the apparent power of each submodule; U dc_mmc is the DC voltage in V.

[0121] S602: Determine the AC current of each phase in the submodule according to the apparent power, DC voltage, and fundamental frequency.

[0122] In this embodiment, the AC current of each phase in the submodule can be calculated according to formula (2).

[0123]

[0124] Where, I p_ac is the AC current of each phase in the submodule, in A; U p_ac is the AC voltage of each phase, in V; f n is the fundamental frequency, in HZ; t is the time, in s.

[0125] S603: Determine a target bridge arm current value according to the DC current component and the AC current.

[0126] In this embodiment, the target bridge arm current value is calculated according to formula (3).

[0127]

[0128] Where, I arm is the target bridge arm current, in A. I arm Is a unidirectional bridge arm current, the unit is A, the bridge arm current calculation formula does not contain the double frequency component, if the circulation suppression is not performed in the flexible direct current control, the double frequency current component can be supplemented, which is not limited in the embodiment of the present application. Optionally, when the bridge arm current calculation method is inaccurate, the bridge arm current calculation method can be corrected according to the current difference, and the correction coefficient a is determined. The corresponding bridge arm current calculation method can be

[0129] In an embodiment of the present application, the DC current component of the bridge arm current is determined based on the apparent power and DC voltage at each sampling moment, the AC current of each phase in the sub-module is determined based on the apparent power, DC voltage and fundamental frequency, and the target bridge arm current value is determined based on the DC current component and the AC current, so that the target bridge arm current value is obtained with higher accuracy.

[0130] In one embodiment, taking the components IGBT and diode included in the flexible DC converter valve as an example, calculating the losses of the components may include calculating the losses of the IGBT and the losses of the diode, such as Figure 7 As shown, step S202, "obtaining the loss of each component in the flexible DC converter valve according to the target bridge arm current value," includes the following steps:

[0131] S701 : Determine the average on-state loss and switching loss of the IGBT according to a preset number of target bridge arm current values.

[0132] Among them, the average on-state loss and switching loss of the IGBT can be read as loss-related data based on the characteristic curve of the corresponding model IGBT. For example, the loss fitting curve of the IGBT can be obtained by fitting using the least squares method based on the correspondence between the current and loss in the experimental data of the IGBT. The loss fitting curve of the IGBT may include the correspondence between the current of the IGBT and the average on-state loss, and may also include the correspondence between the current of the IGBT and the switching loss. When the target bridge arm current value is determined, the average on-state loss and switching loss corresponding to the target bridge arm current value can be directly determined based on the loss fitting curve.

[0133] Alternatively, as Figure 8 As shown, step S701 “determining the average on-state loss and switching loss of the IGBT according to a preset number of target bridge arm current values” may include the following steps:

[0134] S801 : Determine a first voltage corresponding to each target bridge arm current value according to an output characteristic curve of the IGBT, and determine an average on-state loss of the IGBT within a sampling period according to each target bridge arm current value and the corresponding first voltage.

[0135] The output characteristic curve of the IGBT may include the corresponding relationship between the current and voltage of the bridge arm. Therefore, the first voltage corresponding to each target bridge arm current value may be determined according to the output characteristic curve of the IGBT. Figure 9 As shown, taking IGBT as an example, the output characteristic curve of IGBT includes the corresponding relationship between the current and voltage of the flexible DC converter valve, and the first voltage can be determined according to the target bridge arm current value. The average on-state loss of IGBT in the sampling period can be read from the IGBT output characteristic fitting curve corresponding to each target bridge arm current value. Figure 10 As shown, taking IGBT as an example, the output characteristic fitting curve of the IGBT includes the corresponding relationship between the on-state current and the first voltage of the flexible DC converter valve, and the on-state average loss corresponding to each target bridge arm current value can be read according to the output characteristic fitting curve.

[0136] In this embodiment, the average on-state loss of the IGBT during the sampling period can be calculated according to formula (4).

[0137]

[0138] Where, P igbt_onstate_ave is the average on-state loss of the IGBT during the sampling period; m is the preset number of samples, m∈[1,100]; i (m) is the target bridge arm current value of the preset quantity, in A; It is the first voltage corresponding to each target bridge arm current value, in V.

[0139] Optionally, the switching loss includes turn-on loss and turn-off loss. Figure 8 As shown, the turn-on loss and turn-off loss of the IGBT can be determined according to a preset number of target bridge arm current values.

[0140] S802. Determine the turn-on loss and turn-off loss corresponding to each target bridge arm current value according to the switching loss curve of the IGBT, and determine the turn-on loss and turn-off loss of the IGBT within the sampling period according to the turn-on loss, turn-off loss and the first switching number corresponding to each target bridge arm current value.

[0141] Among them, the switching loss curve of the IGBT may include the corresponding relationship between the bridge arm current value and the turn-on loss and turn-off loss. Therefore, the turn-on loss and turn-off loss corresponding to each target bridge arm current value can be determined according to the turn-on / turn-off loss curve of the IGBT. Figure 11 As shown, taking IGBT as an example, the IGBT turn-on / off loss curve includes the corresponding relationship between the current of the flexible DC converter valve and the turn-on loss and turn-off loss. The turn-on loss and turn-off loss can be determined according to the target bridge arm current value. The turn-on loss and turn-off loss of the IGBT during the sampling period can be read through the IGBT turn-on / turn-off loss fitting curve. Figure 12 As shown, taking IGBT as an example, the turn-on / off loss fitting curve of the IGBT includes the corresponding relationship between the target bridge arm current value of the flexible DC converter valve and the turn-on / off loss. The turn-on loss and turn-off loss corresponding to each target bridge arm current value can be read according to the turn-on / off fitting curve.

[0142] In this embodiment, the average turn-on loss of the IGBT during the sampling period can be calculated according to formula (5).

[0143]

[0144] Where, E igbt_on_ave is the average turn-on loss of the IGBT during the sampling period, in J; It is the turn-on loss corresponding to each target bridge arm current value of the IGBT during the sampling period. The unit is J and can be obtained from the turn-on loss fitting curve of the IGBT.

[0145] In this embodiment, the average turn-off loss of the IGBT during the sampling period can be calculated according to formula (6).

[0146]

[0147] Where, E igbt_off_ave is the average turn-off loss of the IGBT during the sampling period, in J; It is the turn-off loss corresponding to the target arm current value of the preset number of IGBTs within the sampling period. The unit is J and can be obtained from the turn-off loss fitting curve of the IGBT.

[0148] In this embodiment, the first switching times of the IGBT in the sampling period can be calculated according to formula (7).

[0149] T s =f c / f n (7);

[0150] Where, T s is the first switching number of the IGBT in the sampling period; f c It is the switching frequency of the switching device, measured in HZ.

[0151] In this embodiment, the turn-on loss of the IGBT during the sampling period can be calculated according to formula (8).

[0152] E on =T s ×E igbt_on_ave (8);

[0153] Where, E on It is the turn-on loss of IGBT during the sampling period, and its unit is J.

[0154] In this embodiment, the turn-on loss and turn-off loss of the IGBT during the sampling period can be calculated according to formula (9).

[0155] E off =T s ×E igbt_on_ave (9);

[0156] Where, E off It is the turn-off loss of IGBT during the sampling period, with the unit of J.

[0157] S702 : Determine the average forward loss and reverse recovery loss of the diode according to a preset number of target bridge arm current values.

[0158] Among them, the average conduction loss and reverse recovery loss of the diode can be used to read loss-related data based on the characteristic curve of the corresponding model diode. For example, the loss fitting curve of the diode can be obtained by fitting using the least squares method based on the correspondence between the current and loss in the experimental data of the diode. The loss fitting curve of the diode may include the correspondence between the current of the diode and the average conduction loss, and may also include the correspondence between the current of the diode and the reverse recovery loss. When the target bridge arm current value is determined, the average conduction loss and reverse recovery loss corresponding to the target bridge arm current value can be directly determined based on the loss fitting curve.

[0159] Alternatively, as Figure 13 As shown, step S702 “determining the average conduction loss and reverse recovery loss of the diode according to a preset number of target bridge arm current values” may include the following steps:

[0160] S1301 : Determine a second voltage corresponding to each target bridge arm current value according to an output characteristic curve of the diode, and determine an average conduction loss of the diode within a sampling period according to each target bridge arm current value and the corresponding second voltage.

[0161] In this embodiment, the average conduction loss of the diode during the sampling period can be calculated according to formula (10).

[0162]

[0163] Where, P diode_onstate_ave is the average conduction loss of the diode during the sampling period; m is the preset number of samples, m∈[1,100]; i (m) is the target bridge arm current value of the preset quantity, in A; is the second voltage corresponding to each target bridge arm current value, in V.

[0164] S1302. Determine the reverse recovery loss corresponding to each target bridge arm current value according to the reverse recovery loss curve of the diode, and determine the reverse recovery loss of the diode within the sampling period according to the reverse recovery loss corresponding to each target bridge arm current value and the second switching number.

[0165] In this embodiment, the reverse recovery loss of the diode during the sampling period can be calculated according to formula (11).

[0166]

[0167] Where, E diode_rec_ave is the reverse recovery loss of the diode during the sampling period, in J; It is the reverse recovery loss of the diode corresponding to the target bridge arm current value of the preset number within the sampling period. The unit is J and can be obtained from the reverse recovery loss fitting curve of the diode.

[0168] In this embodiment, the reverse recovery loss of the diode during the sampling period can be calculated according to formula (12).

[0169] E rec =T s ·E diode_rec_ave (12);

[0170] In this formula, E rec is the reverse recovery loss of the diode during the sampling period, in J.

[0171] In this embodiment, the average on-state loss and switching loss of the IGBT, and the average on-state loss and reverse recovery loss of the diode are determined based on a preset number of target bridge arm current values. By calculating and determining the target bridge arm current values ​​using a finite sampling method, the accuracy of the bridge arm current sampling is fully considered, thereby improving the accuracy of the loss results.

[0172] exist Figure 8 and Figure 13 Based on the embodiment, the loss of the half-bridge submodule in the flexible DC converter valve can be calculated based on the loss of the half-bridge submodule including the loss of the IGBT and the loss of the diode. Figure 14 As shown, step S203, "obtaining the loss of the half-bridge submodule in the flexible DC converter valve according to the loss of each component", the method includes the following steps:

[0173] S1401. Determine the average on-state loss of a half-bridge submodule in a flexible DC converter valve according to the average on-state loss of an IGBT and the average on-state loss of a diode.

[0174] In this embodiment, the average on-state loss of the half-bridge submodule in the flexible DC converter valve can be calculated according to formulas (13) and (14).

[0175]

[0176] W onstate_hb =50%·T·(P igbt_onstate_ave +P diode_onstate_ave ) (14);

[0177] Where T is based on the fundamental frequency f n The cycle of Wonstate_hb is the conduction loss of the half-bridge submodule; P igbt_onstate_ave is the average on-state loss of the IGBT during the sampling period; P diode_onstate_ave is the average conduction loss of the diode during the sampling period.

[0178] S1402: Determine the switching loss of the half-bridge submodule in the flexible DC converter valve based on the switching loss of the IGBT and the reverse recovery loss of the diode.

[0179] In this embodiment, the switching loss of the half-bridge sub-module can be calculated according to formula (15).

[0180] W switch_hb =E on +E off +E rec (15);

[0181] Where W switch_hb is the switching loss of the half-bridge submodule; E on Is the IGBT turn-on loss during the sampling period, unit is J; E off is the IGBT turn-off loss during the sampling period, in J; E rec is the reverse recovery loss of the diode during the sampling period, in J.

[0182] The loss determination method provided in the embodiment of the present application determines the average on-state loss and switching loss of the IGBT according to a preset number of target bridge arm current values, and determines the average on-state loss and reverse recovery loss of the diode according to the preset number of target bridge arm current values. Specifically, the first voltage corresponding to each target bridge arm current value can be determined according to the output characteristic curve of the IGBT, and the average on-state loss of the IGBT within the sampling period can be determined according to each target bridge arm current value and the corresponding first voltage. The turn-on loss and turn-off loss corresponding to each target bridge arm current value can be determined according to the switching loss curve of the IGBT. The number of switching times determines the turn-on loss and turn-off loss of the IGBT within the sampling period. The target bridge arm current value can be used to accurately calculate the loss of the IGBT. Furthermore, based on the output characteristic curve of the diode, the second voltage corresponding to each target bridge arm current value is determined. Based on each target bridge arm current value and the corresponding second voltage, the average conduction loss of the diode within the sampling period is determined. Based on the reverse recovery loss curve of the diode, the reverse recovery loss corresponding to each target bridge arm current value is determined. Based on the reverse recovery loss corresponding to each target bridge arm current value and the second number of switching times, the reverse recovery loss of the diode within the sampling period is determined, and a more accurate diode loss can also be calculated.

[0183] Further, in Figure 14Based on the embodiment shown, the loss of the full-bridge submodule can be calculated based on the loss of the half-bridge submodule, and then the target loss of the flexible DC converter valve can be calculated based on the loss of the full-bridge submodule. Figure 15 As shown, step S204 "determining the target loss of the flexible DC converter valve according to the loss of the half-bridge sub-module" may include the following steps:

[0184] S1501 : Determine the total loss of the half-bridge sub-module according to the average on-state loss of the half-bridge sub-module and the switching loss of the half-bridge sub-module.

[0185] In this embodiment, the total loss of the half-bridge submodule can be calculated according to formula (16).

[0186] W sm_hb =W onstate_hb +W switch_hb (16);

[0187] Where W sm_hb is the total loss of the half-bridge submodule; W onstate_hb is the conduction loss of the half-bridge submodule; W switch_hb is the switching loss of the half-bridge submodule.

[0188] S1502 : Determine the total loss of the full-bridge sub-module according to the total loss of the half-bridge sub-module.

[0189] The submodule loss calculation refers to the sum of the conduction and switching losses of all IGBTs and diodes within a single submodule within a single cycle. After a submodule enters steady-state mode, only one switching element is on, while the other three are off. Therefore, the mathematical analysis assumes that the IGBT and diode are on for the same proportion of the cycle. The actual conduction ratio can be corrected through simulation or measured pulse waveforms. Analysis of the steady-state operating path of a full-bridge module shows that at any given moment, the full-bridge module has twice as many components in the path as the half-bridge module. Therefore, the device losses in a full-bridge configuration are twice those of a half-bridge configuration.

[0190] In this embodiment, the total loss of the full-bridge submodule can be calculated according to formula (17).

[0191] W sm_fb =W sm_hb ·2 (17);

[0192] Where W sm_fb is the total loss of the full-bridge submodule; W sm_hb is the total loss of the half-bridge submodule.

[0193] S1503 : Determine the initial loss of the flexible DC converter valve according to the total loss of the half-bridge submodules, the number of the half-bridge submodules, the total loss of the full-bridge submodules, and the number of the full-bridge submodules.

[0194] In this embodiment, the initial loss of the flexible DC converter valve can be calculated according to formulas (18) and (19).

[0195] N cell =N cell_fb +N cell_hb (18);

[0196] W mmc =W sm_fb ·N cell_fb +W sm_hb ·N cell_hb (19);

[0197] Where N cell is the total number of submodules; N cell_fb is the number of full-bridge submodules; N cell_hb is the number of half-bridge submodules; W sm_fb is the total loss of the full-bridge submodule; W sm_hb is the total loss of the half-bridge submodule; W mmc is the initial loss.

[0198] S1504: Determine the target loss of the flexible DC converter valve according to the initial loss and the fundamental frequency.

[0199] In this embodiment, the target loss can be calculated according to formula (20).

[0200] P mmc_loss =W mmc ·f n (20);

[0201] Where, P mmc_loss Target losses of HVDC-flexible converter valves.

[0202] In the above loss determination method, the total loss of the half-bridge submodule is determined based on the average on-state loss of the half-bridge submodule and the switching loss of the half-bridge submodule, the total loss of the full-bridge submodule is determined based on the total loss of the half-bridge submodule, the initial loss is determined based on the total loss of the half-bridge submodule, the number of half-bridge submodules, the total loss of the full-bridge submodule, and the number of full-bridge submodules, and the target loss of the flexible DC converter valve is determined based on the initial loss and the fundamental frequency. In the process of calculating the target loss of the flexible DC converter valve, the loss of the half-bridge submodule and the loss of the full-bridge submodule are fully considered, so that the calculated target loss of the flexible DC converter valve is more accurate and more in line with the current operating conditions.

[0203] like Figure 16 As shown, the main components and structures of a loss determination method proposed in this application may include A, an input module, B, an operation module, and C, an output module. Among them, the A input module may include: A1 equipment parameter input, A2 operating condition input, and A3 recording data input. The A input module is mainly divided into three parts. The equipment parameter input includes the transformer short-circuit impedance parameters, the transformer grid-side / valve-side voltage, the fundamental frequency, the number of half-bridge and full-bridge sub-modules, the output characteristic curves and on / off loss curves of each component; the operating condition input includes the operating power, DC voltage, AC voltage, the frequency of the switching element, and the junction temperature of the component; the recording data input includes the recording data of the bridge arm current value, which is compared with the calculated bridge arm current value in subsequent calculations. The B operation module includes B1 bridge arm current calculation and correction, and B2 calculation of the loss of each component. The C output module includes C1 various types of loss results, C2 overall loss of the converter valve, and long-term loss results.

[0204] Further, Figure 16 For example, Figure 17 As shown, the embodiment of the present application provides a loss determination method, comprising the following steps:

[0205] S1701. Parameter input.

[0206] The parameters include basic parameters of each device, historical operating condition information, current operating condition information and recorded data of actual projects.

[0207] S1702. Calculation and verification of bridge arm current.

[0208] The target bridge arm current value entering the calculation process will be calculated in this step and accurately verified based on the recorded data provided by the actual project.

[0209] S1703. Fit the output characteristics and turn-on / off loss curves of each component.

[0210] Among them, the output characteristic fitting curve and the turn-on / off loss fitting curve of each component can be obtained by using the least square method according to the instructions of each component used in the parameter input.

[0211] S1704. Calculation of IGBT losses and diode losses.

[0212] Specifically includes IGBT conduction loss, IGBT switching loss, diode conduction loss and diode reverse recovery loss.

[0213] S1705. Calculate submodule loss.

[0214] This step will calculate the half-bridge sub-module losses and full-bridge sub-module losses separately.

[0215] S1706. Calculate the total loss of the MMC converter valve group.

[0216] Among them, the total loss of the converter valve group is calculated according to the number of half-bridge and full-bridge sub-modules in the parameter input.

[0217] The loss determination method provided in the embodiment of the present application can have the following beneficial effects:

[0218] 1. Existing technologies cannot accurately measure losses in flexible DC converter valve groups, and commonly used analytical algorithms often use the current average method, resulting in large errors in loss calculation results. This invention improves on this analytical algorithm by incorporating a finite sampling method into the arm current calculation process, thereby improving the accuracy of loss results.

[0219] 2. Existing technologies typically use simulation methods to ensure the accuracy of HVDC converter valve loss results. However, this method is complex in modeling and time-consuming, making it unsuitable for calculating converter valve losses under complex operating conditions. The optimized analytical algorithm in this invention ensures the accuracy of loss calculation results while overcoming the time-consuming nature of simulation algorithms, enabling long-term loss calculations.

[0220] 3. The existing technology does not have a module for secondary verification of the target bridge arm current value during the loss calculation process, and cannot maximize the accuracy of the results under complex operating conditions. The present invention adds a verification module to the target bridge arm current value calculation module at the beginning of the algorithm. The bridge arm current value under the current operating conditions is verified with the bridge arm current value of the recorded data under historical operating conditions and a correction coefficient is determined. This further improves the accuracy of the target bridge arm current value required in subsequent calculations.

[0221] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0222] Based on the same inventive concept, embodiments of the present application also provide a loss determination device for implementing the aforementioned loss determination method. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more loss determination device embodiments provided below can be found in the limitations of the loss determination method above and will not be further elaborated here.

[0223] In one embodiment, Figure 18 As shown, a loss determination device is provided, comprising:

[0224] A first acquisition module 11 is configured to acquire a preset number of target bridge arm current values ​​within a sampling period of the bridge arm current of the flexible DC converter valve;

[0225] A second acquisition module 12 is configured to acquire the loss of each component in the flexible DC converter valve according to the target bridge arm current value;

[0226] A third acquisition module 13 is configured to acquire the loss of the half-bridge submodule in the flexible DC converter valve according to the loss of each component;

[0227] The determination module 14 is configured to determine a target loss of the flexible DC converter valve according to the loss of the half-bridge submodule.

[0228] In one embodiment, Figure 19 As shown, the first acquisition module 11 includes:

[0229] A first acquiring unit 111 is configured to acquire recorded data of the HVDC Flexible converter valve and historical operating condition information corresponding to the recorded data;

[0230] The first determining unit 112 is configured to determine the preset number of target bridge arm current values ​​according to the historical operating condition information, the current operating condition information of the flexible DC converter valve, and the recorded data.

[0231] In one embodiment, the first determination unit 112 is specifically used to determine whether the historical operating condition information and the current operating condition information are consistent; if they are consistent, determining the preset number of target bridge arm current values ​​from the recorded data; if they are inconsistent, calculating the first bridge arm current value corresponding to the historical operating condition information based on the recorded data, and obtaining the target bridge arm current value based on the first bridge arm current value and the second bridge arm current value in the recorded data.

[0232] In one embodiment, the first determination unit 112 is specifically used to obtain the target bridge arm current value according to the current operating condition information and the bridge arm current calculation method if the current difference between the first bridge arm current value and the second bridge arm current value is less than a preset threshold; if the current difference between the first bridge arm current value and the second bridge arm current value is greater than or equal to the preset threshold, determine the correction coefficient according to the current difference, and obtain the target bridge arm current value according to the correction coefficient, the current operating condition information and the bridge arm current calculation method.

[0233] In one embodiment, the current operating condition information includes the apparent power, DC voltage and fundamental frequency of each submodule in the flexible DC converter valve at each sampling moment; the first determination unit 112 is specifically used to determine the DC current component of the bridge arm current according to the apparent power and the DC voltage at each sampling moment; determine the AC current of each phase in the submodule according to the apparent power, the DC voltage and the fundamental frequency; and determine the target bridge arm current value according to the DC current component and the AC current.

[0234] In one embodiment, the components in the flexible DC converter valve include an insulated gate bipolar transistor (IGBT) and a diode, and the second acquisition module 12 includes:

[0235] A second determining unit is configured to determine an average on-state loss and a switching loss of the IGBT according to the preset number of target bridge arm current values;

[0236] The third determining unit is used to determine the average conduction loss and reverse recovery loss of the diode according to the preset number of target bridge arm current values.

[0237] In one embodiment, the switching loss includes turn-on loss and turn-off loss; the second determination unit is specifically used to determine the first voltage corresponding to each target bridge arm current value according to the output characteristic curve of the IGBT, and determine the average on-state loss of the IGBT according to each target bridge arm current value and the corresponding first voltage; determine the turn-on loss and turn-off loss corresponding to each target bridge arm current value according to the switching loss curve of the IGBT, and determine the turn-on loss and turn-off loss of the IGBT within the sampling period according to the turn-on loss, turn-off loss and first switching number corresponding to each target bridge arm current value.

[0238] In one embodiment, the third determination unit is specifically used to determine the second voltage corresponding to each target bridge arm current value according to the output characteristic curve of the diode, and determine the average conduction loss of the diode according to each target bridge arm current value and the corresponding second voltage; determine the reverse recovery loss corresponding to each target bridge arm current value according to the reverse loss characteristic curve of the diode, and determine the reverse recovery loss of the diode according to the reverse recovery loss corresponding to each target bridge arm current value and the second switching number.

[0239] In one embodiment, the third acquisition module 13 includes:

[0240] a fourth determining unit, configured to determine an average on-state loss of a half-bridge submodule in the flexible DC converter valve according to an average on-state loss of the IGBT and an average on-state loss of the diode;

[0241] A fifth determining unit is configured to determine the switching loss of the half-bridge sub-module according to the switching loss of the IGBT and the reverse recovery loss of the diode.

[0242] In one embodiment, the first determining module 14 includes:

[0243] a sixth determining unit, configured to determine a total loss of the half-bridge submodule according to an average on-state loss of the half-bridge submodule and a switching loss of the half-bridge submodule;

[0244] a seventh determining unit, configured to determine the total loss of the full-bridge submodule according to the total loss of the half-bridge submodule;

[0245] an eighth determining unit, configured to determine an initial loss according to the total loss of the half-bridge submodule, the number of the half-bridge submodules, the total loss of the full-bridge submodule, and the number of the full-bridge submodules;

[0246] A ninth determining unit is configured to determine a target loss of the flexible DC converter valve according to the initial loss and the fundamental frequency.

[0247] The implementation principle and beneficial effects of the loss determination device provided in the embodiment of the present application can refer to the implementation principle and beneficial effects of the loss determination method provided in the above method embodiment, and will not be repeated here.

[0248] Each module in the aforementioned loss determination device may be implemented in whole or in part through software, hardware, or a combination thereof. Each module may be embedded in or independent of a processor in a computer device in the form of hardware, or may be stored in a memory in the computer device in the form of software, so that the processor can call and execute the corresponding operations of each module.

[0249] In one embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure diagram may be as follows: Figure 20 As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, a mobile cellular network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a loss determination method is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or a button, trackball or touchpad provided on the computer device housing, or an external keyboard, touchpad or mouse.

[0250] Those skilled in the art will understand that Figure 20 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0251] In one embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the processor executes the computer program, the following steps are implemented:

[0252] Acquiring a preset number of target bridge arm current values ​​within a sampling period of the bridge arm current of the flexible DC converter valve;

[0253] Obtaining the loss of each component in the flexible DC converter valve according to the target bridge arm current value;

[0254] Obtaining the loss of the half-bridge submodule in the flexible DC converter valve according to the loss of each of the components;

[0255] The target loss of the flexible DC converter valve is determined according to the loss of the half-bridge submodule.

[0256] In one embodiment, when the processor executes the computer program, the processor further implements the following steps: obtaining a preset number of target bridge arm current values ​​within the sampling period of the bridge arm current of the flexible DC converter valve, including:

[0257] Acquiring recorded data of the HVDC Flexible converter valve and historical operating condition information corresponding to the recorded data;

[0258] The preset number of target bridge arm current values ​​are determined according to the historical operating condition information, the current operating condition information of the flexible DC converter valve and the recorded data.

[0259] In one embodiment, when the processor executes the computer program, the processor further implements the following steps: determining the preset number of target bridge arm current values ​​based on the historical operating condition information, the current operating condition information of the flexible DC converter valve, and the recorded data, including:

[0260] Determining whether the historical operating condition information is consistent with the current operating condition information;

[0261] If they are consistent, determining the preset number of target bridge arm current values ​​from the recorded data;

[0262] If they are inconsistent, the first bridge arm current value corresponding to the historical operating condition information is calculated based on the recorded data, and the target bridge arm current value is obtained according to the first bridge arm current value and the second bridge arm current value in the recorded data.

[0263] In one embodiment, when the processor executes the computer program, the processor further implements the following steps: obtaining the target bridge arm current value according to the first bridge arm current value and the second bridge arm current value in the recorded data, including:

[0264] If the current difference between the first bridge arm current value and the second bridge arm current value is less than a preset threshold, obtaining the target bridge arm current value according to the current operating condition information and the bridge arm current calculation method;

[0265] If the current difference between the first bridge arm current value and the second bridge arm current value is greater than or equal to the preset threshold, a correction coefficient is determined based on the current difference, and the target bridge arm current value is obtained based on the correction coefficient, the current operating condition information and the bridge arm current calculation method.

[0266] In one embodiment, when executing the computer program, the processor further implements the following steps: the current operating condition information includes the apparent power, DC voltage, and fundamental frequency of each submodule in the flexible DC converter valve at each sampling moment; and obtaining the target bridge arm current value according to the current operating condition information and the bridge arm current calculation method, including:

[0267] determining a DC current component of the bridge arm current according to the apparent power and the DC voltage at each sampling moment;

[0268] determining an AC current of each phase in the submodule according to the apparent power, the DC voltage, and the fundamental frequency;

[0269] The target bridge arm current value is determined according to the direct current component and the alternating current.

[0270] In one embodiment, when executing the computer program, the processor further implements the following steps: the components in the HVDC flexible converter valve include an insulated gate bipolar transistor (IGBT) and a diode; and according to the target bridge arm current value, obtaining the loss of each component in the HVDC flexible converter valve includes:

[0271] Determining the average on-state loss and switching loss of the IGBT according to the preset number of target bridge arm current values;

[0272] The average conduction loss and reverse recovery loss of the diode are determined according to the preset number of target bridge arm current values.

[0273] In one embodiment, when the processor executes the computer program, the following steps are further implemented: the switching loss includes turn-on loss and turn-off loss; and according to the preset number of target bridge arm current values, the average on-state loss and switching loss of the IGBT are determined, including:

[0274] Determining a first voltage corresponding to each target bridge arm current value according to an output characteristic curve of the IGBT, and determining an average on-state loss of the IGBT according to each target bridge arm current value and the corresponding first voltage;

[0275] According to the on / off loss characteristic curve of the IGBT, the turn-on loss and turn-off loss corresponding to each target bridge arm current value are determined, and the turn-on loss and turn-off loss of the IGBT within the sampling period are determined according to the turn-on loss, the turn-off loss and the first switching number corresponding to each target bridge arm current value.

[0276] In one embodiment, when the processor executes the computer program, the processor further implements the following steps: determining the average conduction loss and reverse recovery loss of the diode according to the preset number of target bridge arm current values, including:

[0277] Determining a second voltage corresponding to each target bridge arm current value according to an output characteristic curve of the diode, and determining an average conduction loss of the diode according to each target bridge arm current value and the corresponding second voltage;

[0278] According to the reverse loss characteristic curve of the diode, the reverse recovery loss corresponding to each target bridge arm current value is determined, and the reverse recovery loss of the diode is determined according to the reverse recovery loss corresponding to each target bridge arm current value and the second switching number.

[0279] In one embodiment, when the processor executes the computer program, the processor further implements the following steps: obtaining the loss of the half-bridge submodule in the flexible DC converter valve according to the loss of each component, including:

[0280] Determining the average on-state loss of the half-bridge submodule in the flexible DC converter valve according to the average on-state loss of the IGBT and the average on-state loss of the diode;

[0281] The switching loss of the half-bridge sub-module is determined according to the switching loss of the IGBT and the reverse recovery loss of the diode.

[0282] In one embodiment, when the processor executes the computer program, the processor further implements the following steps: determining the target loss of the flexible DC converter valve according to the loss of the half-bridge sub-module, including:

[0283] Determining the total loss of the half-bridge submodule according to the average on-state loss of the half-bridge submodule and the switching loss of the half-bridge submodule;

[0284] Determining the total loss of the full-bridge submodule according to the total loss of the half-bridge submodule;

[0285] determining an initial loss according to the total loss of the half-bridge submodule, the number of the half-bridge submodules, the total loss of the full-bridge submodule, and the number of the full-bridge submodules;

[0286] A target loss of the flexible DC converter valve is determined according to the initial loss and the fundamental frequency.

[0287] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0288] Acquiring a preset number of target bridge arm current values ​​within a sampling period of the bridge arm current of the flexible DC converter valve;

[0289] Obtaining the loss of each component in the flexible DC converter valve according to the target bridge arm current value;

[0290] Obtaining the loss of the half-bridge submodule in the flexible DC converter valve according to the loss of each of the components;

[0291] The target loss of the flexible DC converter valve is determined according to the loss of the half-bridge submodule.

[0292] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: obtaining a preset number of target bridge arm current values ​​within the sampling period of the bridge arm current of the flexible DC converter valve, including:

[0293] Acquiring recorded data of the HVDC Flexible converter valve and historical operating condition information corresponding to the recorded data;

[0294] The preset number of target bridge arm current values ​​are determined according to the historical operating condition information, the current operating condition information of the flexible DC converter valve and the recorded data.

[0295] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: determining the preset number of target bridge arm current values ​​based on the historical operating condition information, the current operating condition information of the flexible DC converter valve, and the recorded data, including:

[0296] Determining whether the historical operating condition information is consistent with the current operating condition information;

[0297] If they are consistent, determining the preset number of target bridge arm current values ​​from the recorded data;

[0298] If they are inconsistent, the first bridge arm current value corresponding to the historical operating condition information is calculated based on the recorded data, and the target bridge arm current value is obtained according to the first bridge arm current value and the second bridge arm current value in the recorded data.

[0299] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: obtaining the target bridge arm current value according to the first bridge arm current value and the second bridge arm current value in the recorded data, including:

[0300] If the current difference between the first bridge arm current value and the second bridge arm current value is less than a preset threshold, obtaining the target bridge arm current value according to the current operating condition information and the bridge arm current calculation method;

[0301] If the current difference between the first bridge arm current value and the second bridge arm current value is greater than or equal to the preset threshold, a correction coefficient is determined based on the current difference, and the target bridge arm current value is obtained based on the correction coefficient, the current operating condition information and the bridge arm current calculation method.

[0302] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: the current operating condition information includes the apparent power, DC voltage, and fundamental frequency of each submodule in the flexible DC converter valve at each sampling moment; and obtaining the target bridge arm current value according to the current operating condition information and the bridge arm current calculation method, including:

[0303] determining a DC current component of the bridge arm current according to the apparent power and the DC voltage at each sampling moment;

[0304] determining an AC current of each phase in the submodule according to the apparent power, the DC voltage, and the fundamental frequency;

[0305] The target bridge arm current value is determined according to the direct current component and the alternating current.

[0306] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: the components in the HVDC flexible converter valve include an insulated gate bipolar transistor (IGBT) and a diode; and according to the target bridge arm current value, the loss of each component in the HVDC flexible converter valve is obtained, including:

[0307] Determining the average on-state loss and switching loss of the IGBT according to the preset number of target bridge arm current values;

[0308] The average conduction loss and reverse recovery loss of the diode are determined according to the preset number of target bridge arm current values.

[0309] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: the switching loss includes turn-on loss and turn-off loss; and according to the preset number of target bridge arm current values, the average on-state loss and switching loss of the IGBT are determined, including:

[0310] Determining a first voltage corresponding to each target bridge arm current value according to an output characteristic curve of the IGBT, and determining an average on-state loss of the IGBT according to each target bridge arm current value and the corresponding first voltage;

[0311] According to the switching loss characteristic curve of the IGBT, the turn-on loss and turn-off loss corresponding to each target bridge arm current value are determined, and the turn-on loss and turn-off loss of the IGBT within the sampling period are determined according to the turn-on loss, the turn-off loss and the first switching number corresponding to each target bridge arm current value.

[0312] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: determining the average conduction loss and reverse recovery loss of the diode according to the preset number of target bridge arm current values, including:

[0313] Determining a second voltage corresponding to each target bridge arm current value according to an output characteristic curve of the diode, and determining an average conduction loss of the diode according to each target bridge arm current value and the corresponding second voltage;

[0314] According to the reverse loss characteristic curve of the diode, the reverse recovery loss corresponding to each target bridge arm current value is determined, and the reverse recovery loss of the diode is determined according to the reverse recovery loss corresponding to each target bridge arm current value and the second switching number.

[0315] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: obtaining the loss of the half-bridge submodule in the flexible DC converter valve according to the loss of each component, including:

[0316] Determining the average on-state loss of the half-bridge submodule in the flexible DC converter valve according to the average on-state loss of the IGBT and the average on-state loss of the diode;

[0317] The switching loss of the half-bridge sub-module is determined according to the switching loss of the IGBT and the reverse recovery loss of the diode.

[0318] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: determining the target loss of the flexible DC converter valve according to the loss of the half-bridge sub-module, including:

[0319] Determining the total loss of the half-bridge submodule according to the average on-state loss of the half-bridge submodule and the switching loss of the half-bridge submodule;

[0320] Determining the total loss of the full-bridge submodule according to the total loss of the half-bridge submodule;

[0321] determining an initial loss according to the total loss of the half-bridge submodule, the number of the half-bridge submodules, the total loss of the full-bridge submodule, and the number of the full-bridge submodules;

[0322] A target loss of the flexible DC converter valve is determined according to the initial loss and the fundamental frequency.

[0323] In one embodiment, a computer program product is provided, comprising a computer program, which, when executed by a processor, implements the following steps:

[0324] Acquiring a preset number of target bridge arm current values ​​within a sampling period of the bridge arm current of the flexible DC converter valve;

[0325] Obtaining the loss of each component in the flexible DC converter valve according to the target bridge arm current value;

[0326] Obtaining the loss of the half-bridge submodule in the flexible DC converter valve according to the loss of each of the components;

[0327] The target loss of the flexible DC converter valve is determined according to the loss of the half-bridge submodule.

[0328] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: obtaining a preset number of target bridge arm current values ​​within the sampling period of the bridge arm current of the flexible DC converter valve, including:

[0329] Acquiring recorded data of the HVDC Flexible converter valve and historical operating condition information corresponding to the recorded data;

[0330] The preset number of target bridge arm current values ​​are determined according to the historical operating condition information, the current operating condition information of the flexible DC converter valve and the recorded data.

[0331] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: determining the preset number of target bridge arm current values ​​based on the historical operating condition information, the current operating condition information of the flexible DC converter valve, and the recorded data, including:

[0332] Determining whether the historical operating condition information is consistent with the current operating condition information;

[0333] If they are consistent, determining the preset number of target bridge arm current values ​​from the recorded data;

[0334] If they are inconsistent, the first bridge arm current value corresponding to the historical operating condition information is calculated based on the recorded data, and the target bridge arm current value is obtained according to the first bridge arm current value and the second bridge arm current value in the recorded data.

[0335] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: obtaining the target bridge arm current value according to the first bridge arm current value and the second bridge arm current value in the recorded data, including:

[0336] If the current difference between the first bridge arm current value and the second bridge arm current value is less than a preset threshold, obtaining the target bridge arm current value according to the current operating condition information and the bridge arm current calculation method;

[0337] If the current difference between the first bridge arm current value and the second bridge arm current value is greater than or equal to the preset threshold, a correction coefficient is determined based on the current difference, and the target bridge arm current value is obtained based on the correction coefficient, the current operating condition information and the bridge arm current calculation method.

[0338] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: obtaining the target bridge arm current value according to the current operating condition information and the bridge arm current calculation method, including:

[0339] determining a DC current component of the bridge arm current according to the apparent power and the DC voltage at each sampling moment;

[0340] determining an AC current of each phase in the submodule according to the apparent power, the DC voltage, and the fundamental frequency;

[0341] The target bridge arm current value is determined according to the direct current component and the alternating current.

[0342] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: obtaining the loss of each component in the flexible DC converter valve according to the target bridge arm current value, including:

[0343] Determining the average on-state loss and switching loss of the IGBT according to the preset number of target bridge arm current values;

[0344] The average conduction loss and reverse recovery loss of the diode are determined according to the preset number of target bridge arm current values.

[0345] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: determining the average on-state loss and switching loss of the IGBT according to the preset number of target bridge arm current values, including:

[0346] Determining a first voltage corresponding to each target bridge arm current value according to an output characteristic curve of the IGBT, and determining an average on-state loss of the IGBT according to each target bridge arm current value and the corresponding first voltage;

[0347] According to the switching loss characteristic curve of the IGBT, the turn-on loss and turn-off loss corresponding to each target bridge arm current value are determined, and the turn-on loss and turn-off loss of the IGBT within the sampling period are determined according to the turn-on loss, the turn-off loss and the first switching number corresponding to each target bridge arm current value.

[0348] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: determining the average conduction loss and reverse recovery loss of the diode according to the preset number of target bridge arm current values, including:

[0349] Determining a second voltage corresponding to each target bridge arm current value according to an output characteristic curve of the diode, and determining an average conduction loss of the diode according to each target bridge arm current value and the corresponding second voltage;

[0350] According to the reverse loss characteristic curve of the diode, the reverse recovery loss corresponding to each target bridge arm current value is determined, and the reverse recovery loss of the diode is determined according to the reverse recovery loss corresponding to each target bridge arm current value and the second switching number.

[0351] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: according to the loss of each of the components, the loss of the half-bridge sub-module in the flexible DC converter valve is obtained, including:

[0352] Determining the average on-state loss of the half-bridge submodule in the flexible DC converter valve according to the average on-state loss of the IGBT and the average on-state loss of the diode;

[0353] The switching loss of the half-bridge sub-module is determined according to the switching loss of the IGBT and the reverse recovery loss of the diode.

[0354] In one embodiment, when the computer program is executed by the processor, the following steps are further implemented: determining the target loss of the flexible DC converter valve according to the loss of the half-bridge sub-module, including:

[0355] Determining the total loss of the half-bridge submodule according to the average on-state loss of the half-bridge submodule and the switching loss of the half-bridge submodule;

[0356] Determining the total loss of the full-bridge submodule according to the total loss of the half-bridge submodule;

[0357] determining an initial loss according to the total loss of the half-bridge submodule, the number of the half-bridge submodules, the total loss of the full-bridge submodule, and the number of the full-bridge submodules;

[0358] A target loss of the flexible DC converter valve is determined according to the initial loss and the fundamental frequency.

[0359] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0360] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory may include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processor involved in the various embodiments provided herein may be, but are not limited to, a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic unit, a data processing logic unit based on quantum computing, and the like.

[0361] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0362] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A method for determining loss, characterized in that: The method comprises: within a sampling period of a bridge arm current of the flexible DC converter valve, obtaining recorded data of the flexible DC converter valve and historical operating condition information corresponding to the recorded data, and determining whether the historical operating condition information is consistent with current operating condition information of the flexible DC converter valve; if they are consistent, determining a preset number of target bridge arm current values ​​from the recorded data; if they are inconsistent, calculating a first bridge arm current value corresponding to the historical operating condition information based on the recorded data, and obtaining the target bridge arm current value based on the first bridge arm current value and a second bridge arm current value in the recorded data; Obtaining the loss of each component in the flexible DC converter valve according to the target bridge arm current value; Obtaining the loss of the half-bridge submodule in the flexible DC converter valve according to the loss of each component; The target loss of the flexible DC converter valve is determined according to the loss of the half-bridge submodule.

2. The method according to claim 1, characterized in that The step of obtaining the target bridge arm current value according to the first bridge arm current value and the second bridge arm current value in the recorded data includes: If the current difference between the first bridge arm current value and the second bridge arm current value is less than a preset threshold, obtaining the target bridge arm current value according to the current operating condition information and the bridge arm current calculation method; If the current difference between the first bridge arm current value and the second bridge arm current value is greater than or equal to the preset threshold, a correction coefficient is determined based on the current difference, and the target bridge arm current value is obtained based on the correction coefficient, the current operating condition information and the bridge arm current calculation method.

3. The method according to claim 2, characterized in that The current operating condition information includes the apparent power, DC voltage, and fundamental frequency of each submodule in the flexible DC converter valve at each sampling moment; and obtaining the target bridge arm current value according to the current operating condition information and the bridge arm current calculation method includes: determining a DC current component of the bridge arm current according to the apparent power and the DC voltage at each sampling moment; determining an AC current of each phase in the submodule according to the apparent power, the DC voltage, and the fundamental frequency; The target bridge arm current value is determined according to the direct current component and the alternating current.

4. The method according to any one of claims 1 to 3, characterized in that The components in the flexible DC converter valve include an insulated gate bipolar transistor (IGBT) and a diode. The step of obtaining the loss of each component in the flexible DC converter valve according to the target bridge arm current value includes: Determining the average on-state loss and switching loss of the IGBT according to the preset number of target bridge arm current values; The average conduction loss and reverse recovery loss of the diode are determined according to the preset number of target bridge arm current values.

5. The method according to claim 4, characterized in that The switching loss includes turn-on loss and turn-off loss; and determining the average on-state loss and switching loss of the IGBT according to the preset number of target bridge arm current values ​​includes: Determining a first voltage corresponding to each target bridge arm current value according to an output characteristic curve of the IGBT, and determining an average on-state loss of the IGBT according to each target bridge arm current value and the corresponding first voltage; According to the switching loss curve of the IGBT, the turn-on loss and turn-off loss corresponding to each target bridge arm current value are determined, and the turn-on loss and turn-off loss of the IGBT within the sampling period are determined according to the turn-on loss, turn-off loss and the first switching number corresponding to each target bridge arm current value.

6. The method according to claim 4, characterized in that The determining, according to the preset number of target bridge arm current values, the average conduction loss and the reverse recovery loss of the diode includes: Determining a second voltage corresponding to each target bridge arm current value according to an output characteristic curve of the diode, and determining an average conduction loss of the diode according to each target bridge arm current value and the corresponding second voltage; According to the reverse loss characteristic curve of the diode, the reverse recovery loss corresponding to each target bridge arm current value is determined, and the reverse recovery loss of the diode is determined according to the reverse recovery loss corresponding to each target bridge arm current value and the second switching number.

7. The method according to claim 4, characterized in that The acquiring of the loss of the half-bridge submodule in the flexible DC converter valve according to the loss of each component includes: Determining the average on-state loss of the half-bridge submodule in the flexible DC converter valve according to the average on-state loss of the IGBT and the average on-state loss of the diode; The switching loss of the half-bridge sub-module is determined according to the switching loss of the IGBT and the reverse recovery loss of the diode.

8. The method according to claim 7, characterized in that Determining the target loss of the flexible DC converter valve according to the loss of the half-bridge submodule includes: Determining the total loss of the half-bridge submodule according to the average on-state loss of the half-bridge submodule and the switching loss of the half-bridge submodule; Determining the total loss of the full-bridge submodule according to the total loss of the half-bridge submodule; determining an initial loss according to the total loss of the half-bridge submodule, the number of the half-bridge submodules, the total loss of the full-bridge submodule, and the number of the full-bridge submodules; A target loss of the flexible DC converter valve is determined according to the initial loss and the fundamental frequency.

9. A loss determination device, characterized in that: The device comprises: a first acquisition module, configured to acquire, within a sampling period of a bridge arm current of the flexible DC converter valve, recorded data of the flexible DC converter valve and historical operating condition information corresponding to the recorded data, and determine whether the historical operating condition information is consistent with current operating condition information of the flexible DC converter valve; if they are consistent, determine a preset number of target bridge arm current values ​​from the recorded data; if they are inconsistent, calculate a first bridge arm current value corresponding to the historical operating condition information based on the recorded data, and acquire the target bridge arm current value based on the first bridge arm current value and a second bridge arm current value in the recorded data; a second acquisition module, configured to acquire the loss of each component in the flexible DC converter valve according to the target bridge arm current value; a third acquisition module, configured to acquire the loss of the half-bridge submodule in the flexible DC converter valve according to the loss of each component; A determination module is used to determine the target loss of the flexible DC converter valve according to the loss of the half-bridge sub-module.

10. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

12. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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