Control method and device for interconnection converter group of power grid

Abstract

The invention provides a control method and device for an interconnection converter group of a power grid. The implementation scheme of the control method for the interconnection converter group of the power grid comprises the following steps: obtaining efficiency values of a plurality of interconnection converters in the power grid under each load power; determining a target power distribution ratio of the plurality of interconnected converters based on the efficiency value of each load power of the plurality of interconnected converters, the target power distribution ratio being a ratio of the power of each interconnected converter to the total power; and determining respective target input power of the plurality of interconnected converters based on the target power distribution ratio of the plurality of interconnected converters.

Description

Technical Field

[0001] This application relates to the technical field of power grids, and in particular, to a control method and device for an interconnected converter group for a power grid, an electronic device, a storage medium, and a program product. Background Art

[0002] With the rapid development of technologies such as power electronics and renewable energy, people's requirements for power supply reliability have gradually increased, and the form of the distribution network has changed greatly. This is prominently manifested in that large-scale distributed power sources are connected to the distribution network in an AC or DC manner; the proportion of DC loads in the user-side demand has gradually increased; various energy storages are widely used in the distribution network to improve the regulation ability of the distribution network.

[0003] As a new form of distribution network, the large-scale access of distributed power sources, energy storages, and new DC loads such as DC charging piles in the AC-DC hybrid microgrid impacts the traditional power distribution method. However, the efficiency of the interconnected converters in the AC-DC hybrid microgrid is relatively low. Based on this, there is an urgent need for a control method for the interconnected converter group for the power grid, which is of great significance to the practical application of the AC-DC hybrid microgrid. Summary of the Invention

[0004] This application aims to solve at least one of the technical problems existing in the background art. To this end, an object of this application is to provide a control method and device for an interconnected converter group for a power grid, an electronic device, a storage medium, and a program product, so that the power distribution of multiple interconnected converters can meet the optimal total efficiency of the interconnected converter group and improve the operation efficiency of the interconnected converter group.

[0005] An embodiment of the first aspect of this application provides a control method for an interconnected converter group for a power grid. The interconnected converter group includes multiple interconnected converters that are electrically connected. The method includes: obtaining the efficiency values when each load power of the multiple interconnected converters in the power grid; determining the target power distribution ratio of the multiple interconnected converters based on the efficiency values when each load power of the multiple interconnected converters, where the target power distribution ratio is the ratio of the power of each interconnected converter to the total power; and determining the respective target input powers of the multiple interconnected converters based on the target power distribution ratio of the multiple interconnected converters.

[0006] In the technical solution of the embodiment of this application, by obtaining the efficiency values when each load power of the multiple interconnected converters in the power grid and taking the efficiency value of the interconnected converter group as the target, the ratio of the power of each interconnected converter to the total power is determined, so that the power distribution of the multiple interconnected converters can meet the optimal total efficiency of the interconnected converter group, thereby improving the operation efficiency of the interconnected converter group.

[0007] In some embodiments, determining the target power distribution ratio of multiple interconnected converters based on the efficiency values at their respective load powers includes: constructing an efficiency function of the interconnected converters based on the efficiency values at their respective load powers, where the independent variable of the efficiency function is the load power and the dependent variable is the efficiency value; constructing the total efficiency function of the interconnected converter group based on the respective efficiency functions of the multiple interconnected converters; and solving the total efficiency function based on preset constraint conditions to determine the target power distribution ratio of the multiple interconnected converters, where the target power distribution ratio satisfies the optimal total efficiency of the interconnected converter group. By constructing the efficiency function of the interconnected converters and constructing the total efficiency function of the interconnected converter group based on the respective efficiency functions of the multiple interconnected converters, and finally determining the target power distribution ratio of the multiple interconnected converters that satisfies the optimal total efficiency of the interconnected converter group, on the premise that the power distribution ratio of the multiple interconnected converters satisfies the optimal total efficiency of the interconnected converter group, the determined power distribution ratio of the multiple interconnected converters is more accurate, thereby further improving the operating efficiency of the interconnected converter group.

[0008] In some embodiments, the preset constraint conditions include that the total power of the interconnected converter group is the sum of the powers of the multiple interconnected converters, and the power of the interconnected converter is not greater than the rated power. When solving the total efficiency function of the interconnected converter group, taking the total power of the interconnected converter group being the sum of the powers of the multiple interconnected converters and the power of the interconnected converter not being greater than the rated power as constraint conditions, on the premise that the power distribution ratio of the multiple interconnected converters satisfies the optimal total efficiency of the interconnected converter group, the obtained target power distribution ratio of the multiple interconnected converters can not only ensure the normal operation of the power grid, but also ensure the normal operation of each interconnected converter.

[0009] In some embodiments, determining the target power distribution ratio of multiple interconnected converters based on the efficiency values at their respective load powers includes: calculating offline the target power distribution ratio of the multiple interconnected converters based on the efficiency values at their respective load powers. Calculating the target power distribution ratio of the multiple interconnected converters in an offline manner improves the speed of determining the target power distribution ratio of the multiple interconnected converters, thereby improving the control rate of the interconnected converter group.

[0010] In some embodiments, the method further includes: performing per-unit processing on the power of the interconnected converter. By performing per-unit processing on the power of the interconnected converter, the efficiency of determining the target power distribution ratio of the multiple interconnected converters can be improved, thereby improving the rate of determining the respective target input powers of the multiple interconnected converters, and further improving the control rate of the interconnected converter group.

[0011] In some embodiments, determining the respective target input powers of multiple interconnected converters based on the target power distribution ratios of the multiple interconnected converters includes: making a target power distribution ratio look-up table for the target power distribution ratios of the multiple interconnected converters; and looking up the respective target input powers of the multiple interconnected converters from the target power distribution ratio look-up table. By making the power distribution ratios obtained from offline optimization into a look-up table through real-time optimization and using the look-up table to look up the target input powers of each converter online, the control efficiency of the interconnected converter group can be further improved.

[0012] In some embodiments, based on the target power distribution ratios of multiple interconnected converters, a hysteresis control is adopted to construct an operating state adjustment function for the multiple interconnected converters. The independent variable of the operating state adjustment function is the total power of the interconnected converter group, and the dependent variable is the adjustment coefficient. Based on the operating state adjustment function, the respective load powers of the multiple interconnected converters are adjusted to the respective target input powers of the multiple interconnected converters. By obtaining the power distribution of the converters online, combining the power hysteresis control to construct an operating state adjustment function for the multiple interconnected converters, and adjusting the respective load powers of the interconnected converters to the respective target input powers of the multiple interconnected converters, the respective load powers of the interconnected converters can be adjusted in a timely manner. At the same time, the probability of frequent switching of the multiple interconnected converters can be reduced, making the operation of the power grid more stable.

[0013] An embodiment of the second aspect of the present application provides a control device for an interconnected converter group for a power grid, including: an acquisition module configured to acquire the efficiency values when the respective load powers of multiple interconnected converters in the power grid; a calculation module configured to determine the target power distribution ratios of the multiple interconnected converters based on the efficiency values when the respective load powers of the multiple interconnected converters, where the target power distribution ratio is the ratio of the power of each interconnected converter to the total power; and a determination module configured to determine the respective target input powers of the multiple interconnected converters based on the target power distribution ratios of the multiple interconnected converters.

[0014] In the technical solution of the embodiment of the present application, by acquiring the efficiency values when the respective load powers of multiple interconnected converters in the power grid and taking the efficiency value of the interconnected converter group as the target, the ratio of the power of each interconnected converter to the total power is determined, so that the power distribution of the multiple interconnected converters can satisfy that the total efficiency of the interconnected converter group is optimal, thereby improving the operating efficiency of the interconnected converter group.

[0015] In some embodiments, the calculation module includes: a first function construction unit configured to construct an efficiency function of the interconnected converter based on the efficiency values at various load powers of the interconnected converter, where the independent variable of the efficiency function is the load power and the dependent variable is the efficiency value; a second function construction unit configured to construct a total efficiency function of the interconnected converter group based on the respective efficiency functions of multiple interconnected converters; and a function solving unit configured to solve the total efficiency function based on preset constraint conditions to determine the target power distribution ratio of the multiple interconnected converters, where the target power distribution ratio satisfies that the total efficiency of the interconnected converter group is optimal.

[0016] In some embodiments, the preset constraint conditions include that the total power of the interconnected converter group is the sum of the powers of the multiple interconnected converters, and the power of the interconnected converter is not greater than the rated power.

[0017] In some embodiments, the calculation module includes: an offline calculation unit configured to offline calculate the target power distribution ratio of the multiple interconnected converters based on the efficiency values at various load powers of the interconnected converter.

[0018] In some embodiments, the control device for the interconnected converter group for the power grid further includes: a numerical processing module configured to perform per-unit processing on the power of the interconnected converter.

[0019] In some embodiments, the determination module includes: a tabulation unit configured to tabulate the target power distribution ratio of the multiple interconnected converters to form a target power distribution ratio lookup table; and a lookup unit configured to look up the respective target input powers of the multiple interconnected converters from the target power distribution ratio lookup table.

[0020] In some embodiments, the control device for the interconnected converter group for the power grid further includes: a function construction module configured to construct an operation state adjustment function of the multiple interconnected converters using hysteresis control based on the target power distribution ratio of the multiple interconnected converters, where the independent variable of the operation state adjustment function is the total power of the interconnected converter group and the dependent variable is the adjustment coefficient; and an adjustment module configured to adjust the respective load powers of the multiple interconnected converters to their respective target input powers based on the operation state adjustment function.

[0021] An embodiment of the third aspect of the present application provides an electronic device, including a memory and a processor, where the memory stores a computer program that can run on the processor, and the processor implements the method according to any one of the above when executing the program.

[0022] An embodiment of the fourth aspect of the present application provides a computer-readable storage medium, on which a computer program is stored, and the computer program implements the method according to any one of the above when executed by a processor.

[0023] An embodiment of the fifth aspect of the present application provides a computer program product, including computer-readable code, or a non-volatile computer-readable storage medium carrying the computer-readable code. When the computer-readable code runs on an electronic device, the processor in the electronic device executes the method of any one of the above.

[0024] The above description is only an overview of the technical solution of the present application. In order to be able to understand the technical means of the present application more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of the present application more obvious and understandable, the specific embodiments of the present application are specifically exemplified below. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In the drawings, unless otherwise specified, the same reference numerals throughout the multiple drawings represent the same or similar components or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0026] Figure 1 Shows the flow of a control method for an interconnected converter group for a power grid according to an embodiment of the present application Figure 1 ;

[0027] Figure 2 Shows a schematic diagram of a power grid according to an embodiment of the present application;

[0028] Figure 3 Shows the efficiency curve of an interconnected converter according to an embodiment of the present application;

[0029] Figure 4 Shows the flowchart of the process of determining the target power distribution ratio according to an embodiment of the present application;

[0030] Figure 5 Shows the flowchart of the process of determining the target power distribution ratio by using the exhaustive method according to an embodiment of the present application;

[0031] Figure 6 Shows the power distribution curve of an interconnected converter group according to an embodiment of the present application;

[0032] Figure 7 Shows the optimal efficiency curve of an interconnected converter group according to an embodiment of the present application;

[0033] Figure 8 Shows the flowchart of the process of determining the target input power according to an embodiment of the present application;

[0034] Figure 9 Shows the flow of a control method for an interconnected converter group for a power grid according to an embodiment of the present application Figure 2 ;

[0035] Figure 10 The structural block diagram of a control device for an interconnected converter group for a power grid according to an embodiment of the present application is shown.

[0036] Figure 11 The structural block diagram of a calculation module according to an embodiment of the present application is shown;

[0037] Figure 12 The structural block diagram of a determination module according to an embodiment of the present application is shown;

[0038] Figure 13 The flowchart of a control method for an interconnected converter group for a power grid according to an embodiment of the present application is shown Figure 3 ;

[0039] Figure 14 The simulation waveform of the DC bus voltage according to an embodiment of the present application is shown;

[0040] Figure 15 The schematic diagram of the theoretical values of the allocated power of three interconnected converters according to an embodiment of the present application is shown;

[0041] Figure 16 The actual simulation waveforms of three interconnected converters according to an embodiment of the present application are shown;

[0042] Figure 17 The efficiency simulation results of three interconnected converters in three operating modes according to an embodiment of the present application are shown. Detailed implementation manners

[0043] Hereinafter, embodiments of the technical solutions of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and thus are only examples and cannot be used to limit the protection scope of the present application.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above drawings are intended to cover non-exclusive inclusion.

[0045] In the description of the embodiments of the present application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present application, "a plurality" means more than two unless otherwise specifically defined.

[0046] References to "embodiments" in this specification mean that the particular features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0047] In the description of the embodiments of the present application, the term "and / or" is merely a description of the relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone. Additionally, the character " / " in this text generally indicates an "or" relationship between the associated objects before and after.

[0048] In the description of the embodiments of the present application, the term "plurality" refers to two or more (including two). Similarly, "multiple groups" refers to two or more groups (including two groups), and "multiple pieces" refers to two or more pieces (including two pieces).

[0049] In the description of the embodiments of the present application, the orientation or positional relationship indicated by technical terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the embodiments of the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the embodiments of the present application.

[0050] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can also be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0051] At present, traditional AC microgrids have the advantage of adapting to changes in different voltage levels, and the operation of generators is easy to maintain. They are the main power distribution network methods for current industry and life. With the continuous development of power electronics technology, the demand for energy storage devices and distributed power sources is increasing continuously, and the proportion of DC loads is increasing continuously. Due to its ability to improve the transmission efficiency, power quality, power supply reliability of the power system and the consumption capacity of renewable energy, DC microgrids have broad future prospects in residential electricity consumption and commercial power supply.

[0052] With the continuous development of the power network, the AC-DC hybrid microgrid, which combines the advantages of AC and DC microgrids, has gradually been effectively applied. During the application process of the AC-DC hybrid microgrid, it is usually necessary to realize the bidirectional power flow compensation between the AC system and the DC system through multiple interlinking converters (ILCs) connected in parallel between the AC system and the DC system, so that the AC system can transmit a certain amount of power to the DC system for compensation when there are energy fluctuations in the DC system through multiple interlinking converters, and the DC system can transmit a certain amount of power to the AC system for compensation when there are energy fluctuations in the AC system through multiple interlinking converters, to ensure the power coordination between the AC and DC systems under the AC-DC hybrid microgrid.

[0053] Based on the above considerations, in order to improve the operation efficiency of the interlinking converters, in the optimal control scheme of the AC-DC hybrid microgrid, multiple interlinking converters mostly operate in an equal power sharing mode, and this mode is suitable for application scenarios with stable load power. The operation efficiency of the interlinking converter depends on its load power. At different load powers, the efficiency of the interlinking converter varies greatly. Especially at low load operating points, the efficiency of the interlinking converter is much lower than the rated efficiency. Equal power sharing control is not suitable for the AC-DC hybrid microgrid, and a new operation control strategy needs to be proposed to improve its overall operation efficiency.

[0054] Based on this, the present application proposes a control method for a group of interlinking converters for a power grid. By obtaining the efficiency values of multiple interlinking converters in the power grid at each load power, and taking the efficiency value of the group of interlinking converters as the goal, the ratio of the power of each interlinking converter to the total power is determined, so that the power distribution of multiple interlinking converters can meet the optimal total efficiency of the group of interlinking converters, thereby improving the operation efficiency of the group of interlinking converters.

[0055] According to one aspect of the present application, a control method for a group of interlinking converters for a power grid is provided.

[0056] Figure 1 The flowchart of the control method 100 for a group of interlinking converters for a power grid according to an embodiment of the present application is shown Figure 1 . The group of interlinking converters includes multiple interlinking converters connected electrically, such asFigure 1 As shown in Figure 1 , the control method for the interconnected converter group in the power grid includes: Step S110, obtaining the efficiency values when each of the multiple interconnected converters in the power grid has a load power; Step S120, based on the efficiency values when each of the multiple interconnected converters has a load power, determining the target power distribution ratio of the multiple interconnected converters, where the target power distribution ratio is the ratio of the power of each interconnected converter to the total power; Step S130, based on the target power distribution ratio of the multiple interconnected converters, determining the respective target input powers of the multiple interconnected converters.

[0057] Exemplarily, Figure 2 A schematic diagram of the power grid according to an embodiment of the present application is shown. As Figure 2 shown, the power grid can be an AC-DC hybrid microgrid, and the AC-DC hybrid microgrid can include a DC system, an AC system, and interconnected converters. The AC system includes an AC load and an energy storage device, and the DC system includes a DC load, an energy storage device, and a distributed power source. The AC system is connected to the AC power grid, and the AC system and the DC system are coupled through an interconnected converter group, and the interconnected converter group can include multiple interconnected converters connected electrically. By paralleling multiple interconnected converters installed between the AC system and the DC system, bidirectional power flow compensation between the AC system and the DC system can be achieved, enabling the AC system to transfer a certain amount of power to the DC system for compensation when there is an energy fluctuation in the DC system through the multiple interconnected converters, and also enabling the DC system to transfer a certain amount of power to the AC system for compensation when there is an energy fluctuation in the AC system through the multiple interconnected converters, so as to ensure power coordination between the AC system and the DC system in the AC-DC hybrid microgrid.

[0058] In step S110, obtain the efficiency values when each of the multiple interconnected converters in the power grid has a load power.

[0059] In the example, the efficiency values when each of the multiple interconnected converters in step S110 has a load power can be obtained from the respective efficiency curves corresponding to the multiple interconnected converters. It can also be obtained from documents such as the instruction manual of the interconnected converter and the factory parameter table of the interconnected converter. The types of the multiple interconnected converters in the interconnected converter group can be the same or different. When the types of the multiple interconnected converters are the same, the efficiency values when each of the multiple interconnected converters has a load power are also the same.

[0060] In the example, the efficiency of each interconnected converter is:

[0061]

[0062] where η(P IN ) is the efficiency value of the interconnected converter when the input power of the interconnected converter is P IN , P IN is the input power of the interconnected converter, POUT is the output power of the interconnected converter, P loss is the power loss of the interconnected converter.

[0063] Exemplarily, Figure 3 shows the efficiency curve of the interconnected converter according to an embodiment of the present application. This efficiency curve can represent the curve of the efficiency of the interconnected converter changing with the load power of the interconnected converter. The load power of the efficiency curve of the interconnected converter is its horizontal axis, and the efficiency value is its vertical axis. As Figure 3 shown, when the load power of the interconnected converter is low, its efficiency is low. As the load power of the interconnected converter increases, the operating efficiency of the interconnected converter continuously improves until the highest point of efficiency. After the highest point of efficiency, the efficiency of the interconnected converter decreases as the load power increases.

[0064] Since the load power of the interconnected converter has a great influence on its efficiency, when multiple interconnected converters are operated in parallel, the power distribution of each interconnected converter can be optimized according to the AC-DC hybrid grid interaction power (the positive direction of the set power is the power transmitted from the AC system to the DC system) so as to achieve the optimal operating efficiency of the grid.

[0065] Step S120: The target power distribution ratio of multiple interconnected converters can be determined based on the efficiency values at the respective load powers of the multiple interconnected converters, where the target power distribution ratio is the ratio of the power of each interconnected converter to the total power.

[0066] In one example, an efficiency function of the interconnected converter can be constructed based on the efficiency values at the respective load powers of the interconnected converter, and a total efficiency function of the interconnected converter group can be constructed based on the respective efficiency functions of the multiple interconnected converters. Subsequently, the total efficiency function can be solved based on preset constraint conditions to determine the target power distribution ratio of the multiple interconnected converters, that is, the ratio of the power of each interconnected converter to the total power of the interconnected converter group.

[0067] In another example, the target power distribution ratio of multiple interconnected converters can be determined by a neural network that has been preset and trained. The specific process is to use the efficiency values at the respective load powers of the multiple interconnected converters as the input of the neural network, and the target power distribution ratio of the multiple interconnected converters is the output of the neural network. Based on the preset and trained neural network, the ratio of the power of each interconnected converter to the total power can be quickly obtained.

[0068] Step S130: The respective target input powers of the multiple interconnected converters can be determined based on the target power distribution ratio of the multiple interconnected converters.

[0069] In one example, the target power distribution ratios of multiple interconnected converters can be made into a target power distribution ratio look-up table, and the respective target power distribution ratios of the multiple interconnected converters can be found from the target power distribution ratio look-up table. Thus, the respective target input powers of the multiple interconnected converters can be determined according to the respective target power distribution ratios of the multiple interconnected converters.

[0070] In another example, based on the target power distribution ratios of multiple interconnected converters, the respective target input powers of the multiple interconnected converters can be calculated by means of online calculation.

[0071] According to the control method for an interconnected converter group for a power grid according to an embodiment of the present application, by obtaining the efficiency values when the multiple interconnected converters in the power grid have respective load powers, and taking the efficiency value of the interconnected converter group as the target, the ratio of the power of each interconnected converter to the total power is determined, so that the power distribution of the multiple interconnected converters can satisfy that the total efficiency of the interconnected converter group is optimal, thereby improving the operation efficiency of the interconnected converter group.

[0072] Figure 4 The flowchart showing the process of determining the target power distribution ratio according to an embodiment of the present application is as follows. Figure 4 As shown, the process of determining the target power distribution ratio may include: Step S410, based on the efficiency values when the interconnected converter has respective load powers, constructing an efficiency function of the interconnected converter, where the independent variable of the efficiency function is the load power and the dependent variable is the efficiency value; Step S420, based on the respective efficiency functions of the multiple interconnected converters, constructing a total efficiency function of the interconnected converter group; Step S430, solving the total efficiency function based on preset constraint conditions to determine the target power distribution ratios of the multiple interconnected converters, and the target power distribution ratios satisfy that the total efficiency of the interconnected converter group is optimal. This process of determining the target power distribution ratio may be, for example, combined with Figure 1 Step S120 shown as follows.

[0073] In step S410, based on the efficiency values when the interconnected converter has respective load powers, an efficiency function of the interconnected converter can be constructed, where the independent variable of the efficiency function is the load power and the dependent variable is the efficiency value.

[0074] In the example, the number of efficiency values obtained when the interconnected converter has respective load powers may be limited. In order to better determine the efficiency values when the interconnected converter has respective load powers, an efficiency function of the interconnected converter can be constructed based on the efficiency values when the interconnected converter has respective load powers.

[0075] Exemplarily, the efficiency values when the interconnected converter has respective load powers can be subjected to a piecewise linear numerical fitting method to obtain an efficiency function of the interconnected converter, and the efficiency function can be represented by a piecewise function. According to Figure 3For the efficiency curve of the interconnected converter shown, the efficiency function of the interconnected converter can be:

[0076]

[0077] Among them, η(P) is the efficiency value of the interconnected converter when the input power of the interconnected converter is P, and P is the load power of the interconnected converter.

[0078] In step S420, the total efficiency function of the interconnected converter group can be constructed based on the respective efficiency functions of multiple interconnected converters.

[0079] In the example, taking Figure 2 the power grid shown as an example, the interconnected converter group of the AC-DC hybrid microgrid includes multiple interconnected converters connected electrically. The total efficiency function of the multiple interconnected converters is:

[0080]

[0081] Among them, η T (P IN ) is the total efficiency of the power grid when the total input power of the multiple interconnected converters is P IN , P IN is the total input power of the multiple interconnected converters, P OUT is the total output power of the multiple interconnected converters, P IN,i is the input power of the i-th interconnected converter, and η i (P IN,i ) is the efficiency value of the interconnected converter when the input power of the i-th interconnected converter is P IN,i , and P OUT,i is the output power of the i-th interconnected converter.

[0082] Exemplarily, assuming that the multiple interconnected converters are of the same type, then the efficiency values at each load power of the multiple interconnected converters are the same, and η i (P IN,i ) = η(P IN,i ), i = 1, 2,..., n. Substituting into equation (1), the total efficiency function of the interconnected converter group is obtained as:

[0083]

[0084] Among them, η T (P IN,1 , P IN,2 ,..., P IN,n ) is the efficiency value of the multiple interconnected converters, η i (P IN,i ) is the efficiency value of the interconnected converter when the input power of the i-th interconnected converter is P IN,i , and PIN,i is the input power of the i-th interconnected converter.

[0085] In step S430, the total efficiency function can be solved based on preset constraint conditions to determine the target power distribution ratio of multiple interconnected converters, and the target power distribution ratio satisfies that the total efficiency of the interconnected converter group is optimal.

[0086] In the example, the preset constraint conditions may include that the total power of the interconnected converter group is the sum of the powers of multiple interconnected converters, and the power of the interconnected converter is not greater than the rated power.

[0087] In the example, to optimize the operation mode of multiple interconnected converters and make the total efficiency of the interconnected converter group optimal, an optimization objective function can be established:

[0088] g = max{η T (P IN,1 , P IN,2 ,..., P IN,n )} (5)

[0089] where η T (P IN,1 , P IN,2 ,..., P IN,n ) is the efficiency value of multiple interconnected converters, and g is the optimal value of the efficiency values of multiple interconnected converters.

[0090] In the example, taking three interconnected converters as an example, the power distribution ratio of a single interconnected converter can be 0 ≤ P Ni ≤ 1 / 3 (N = 1, 2, 3). The exhaustive method can be used to determine the target power distribution ratio of the three interconnected converters. Figure 5 shows a flowchart of the process of determining the target power distribution ratio using the exhaustive method according to an embodiment of the present application. As Figure 5 shown, P is the total power of the three interconnected converters, g is the optimal value of the efficiency values of the three interconnected converters, P 1i is the power distribution ratio of the first interconnected converter, P 2i is the power distribution ratio of the second interconnected converter, and P 3i is the power distribution ratio of the third interconnected converter. Initialize the load power of the three interconnected converters and the optimal value of the efficiency values of the three interconnected converters to 0, and calculate the optimal efficiency and its optimal power distribution ratio at each load power with a power resolution of 1‰ to obtain the power distribution ratios P 1i , P 2i and P 3i of the three interconnected converters when the total efficiency of the interconnected converter group is optimal, as well as the optimal value η i of the efficiency values of multiple interconnected converters.

[0091] Figure 6 The power distribution curve of the interconnected converter group according to an embodiment of the present application is shown. This power distribution curve can represent the curve of the load power of the interconnected converter varying with the load power of the interconnected converter group. The total load power P of the interconnected converter group is the horizontal axis, and the load power of each interconnected converter is the vertical axis. Figure 7 The optimal efficiency curve of the interconnected converter group according to an embodiment of the present application is shown. This efficiency curve can represent the curve of the efficiency of the interconnected converter group varying with the load power of the interconnected converter group. The total load power of the efficiency curve of the interconnected converter group is the horizontal axis, and the efficiency value of the interconnected converter group is the vertical axis.

[0092] As Figure 6 shown, when the 3 interconnected converters operate at full load, the load power is 1 p.u., and when a single interconnected converter operates at full load, P is 1 / 3 p.u. When the load power of the interconnected converter group is 0 ≤ P ≤ 0.313 p.u., only 1 interconnected converter participates in power transmission, and this interconnected converter is denoted as the first interconnected converter. When the load power of the interconnected converter group is 0.313 p.u. < P ≤ 0.525 p.u., 2 interconnected converters participate in power transmission, namely the first interconnected converter and the second interconnected converter; among them, when the load power of the interconnected converter group is 0.313 p.u. < P ≤ 0.334 p.u., the second interconnected converter operates at a constant power of 0.133 p.u., and the first interconnected converter increases as the load power of the interconnected converter group increases; when the load power of the interconnected converter group is 0.334 p.u. < P ≤ 0.525 p.u., the first interconnected converter and the second interconnected converter operate in a power equal-sharing manner, that is, the transmission power of each interconnected converter is P / 2. When the load power of the interconnected converter group is 0.525 p.u. < P ≤ 1 p.u., the first interconnected converter, the second interconnected converter, and the third interconnected converter all participate in power transmission; among them, when the load power of the interconnected converter group is 0.525 p.u. < P ≤ 0.6 p.u., the first interconnected converter and the second interconnected converter operate at a constant power of 0.2 p.u., and the third interconnected converter increases as the transmission power increases; when the load power of the interconnected converter group is 0.6 p.u. < P ≤ 1 p.u., the 3 interconnected converters operate in a power equal-sharing manner.

[0093] The process of determining the target power distribution ratio of multiple interconnected converters according to an embodiment of the present application constructs an efficiency function of the interconnected converters, constructs a total efficiency function of the interconnected converter group with the efficiency functions of the multiple interconnected converters respectively, and finally determines the target power distribution ratio of the multiple interconnected converters that satisfies the optimal total efficiency of the interconnected converter group. On the premise that the power distribution ratio of the multiple interconnected converters satisfies the optimal total efficiency of the interconnected converter group, the determined power distribution ratio of the multiple interconnected converters is more accurate, thereby further improving the operating efficiency of the interconnected converter group.

[0094] According to some embodiments, the preset constraint conditions may include that the total power of the interconnected converter group is the sum of the powers of the multiple interconnected converters, and the power of the interconnected converter is not greater than the rated power.

[0095] Exemplarily, the constraint conditions may be:

[0096]

[0097] wherein, P is the total power of the interconnected converter group, Pi is the operating power of the i-th interconnected converter, and P N is the rated power of a single interconnected converter.

[0098] According to an embodiment of the present application, when solving the total efficiency function of the interconnected converter group, taking the total power of the interconnected converter group as the sum of the powers of the multiple interconnected converters and the power of the interconnected converter not being greater than the rated power as constraint conditions, on the premise that the power distribution ratio of the multiple interconnected converters satisfies the optimal total efficiency of the interconnected converter group, the obtained target power distribution ratio of the multiple interconnected converters can not only ensure the normal operation of the power grid, but also ensure the normal operation of each interconnected converter.

[0099] According to some embodiments, the process of determining the target power distribution ratio may include: calculating the target power distribution ratio of the multiple interconnected converters offline based on the efficiency values at each load power of the interconnected converters. This process of determining the target power distribution ratio may be, for example, combined with Figure 1 the steps shown in S120.

[0100] In the example, since it takes a certain amount of time to calculate the target power distribution ratio of the multiple interconnected converters in the interconnected converter group, and online calculation will affect the control performance of the interconnected converter group. Therefore, the target power distribution ratio of the multiple interconnected converters can be calculated offline based on the efficiency values at each load power of the interconnected converters.

[0101] In the embodiment of the present application, the target power distribution ratio of the multiple interconnected converters is calculated in an offline manner, which improves the speed of determining the target power distribution ratio of the multiple interconnected converters, thereby improving the control rate of the interconnected converter group.

[0102] According to some embodiments, the method further includes: performing per-unit processing on the power of the interconnected converters.

[0103] In the example, the target input power of each of the multiple interconnected converters included in the interconnected converter group is obtained through the target power distribution ratio of the multiple interconnected converters in the interconnected converter group. The target power distribution ratio of the multiple interconnected converters is reflected as a ratio and does not require the specific power values of the multiple interconnected converters. Therefore, in order to simplify the process of determining the target power distribution ratio of the multiple interconnected converters, per-unit processing can be performed on the power of the interconnected converters.

[0104] In the example, performing per-unit processing on the power of the interconnected converters means setting the total power of the interconnected converter group to 1. Taking the example of 3 interconnected converters in parallel, when the 3 interconnected converters are operating at full load, the total power is 1 p.u., and when a single interconnected converter is operating at full load, P is 1 / 3 p.u.

[0105] In the embodiments of the present application, by performing per-unit processing on the power of the interconnected converters, the efficiency of determining the target power distribution ratio of the multiple interconnected converters can be improved, thereby increasing the rate of determining the target input power of each of the multiple interconnected converters, and further increasing the control rate of the interconnected converter group.

[0106] Figure 8 The flowchart showing the process of determining the target input power according to the embodiments of the present application is shown. As Figure 8 shown, the process of determining the target input power may include: step S810, making a target power distribution ratio lookup table for the target power distribution ratio of the multiple interconnected converters; step S820, looking up the target input power of each of the multiple interconnected converters from the target power distribution ratio lookup table. This process of determining the target input power may be, for example, combined with Figure 1 step S130 shown.

[0107] Step S810: The target power distribution ratio of the multiple interconnected converters can be made into a target power distribution ratio lookup table;

[0108] Exemplarily, the target power distribution ratio in the foregoing embodiments Figure 6 can be made into a target power distribution ratio lookup table as shown in the following table:

[0109]

[0110] Step S820: The target input power of each of the multiple interconnected converters can be looked up from the target power distribution ratio lookup table.

[0111] In the example, after the total power of the interconnected converter group is determined, the power distribution of Converter 1, Converter 2, and Converter 3 can be directly found from the above-mentioned target power distribution ratio look-up table. Based on the power distribution of Converter 1, Converter 2, and Converter 3, the target input power of Converter 1, Converter 2, and Converter 3 can be determined respectively.

[0112] In the embodiment of the present application, by making the power distribution ratio of offline optimization into a look-up table through real-time optimization and using the look-up table to online find the target input power of each converter, the control efficiency of the interconnected converter group can be further improved.

[0113] According to some embodiments, Figure 9 shows the flow of a control method for an interconnected converter group for a power grid according to an embodiment of the present application Figure 2 , as Figure 9 shown, the control method may further include: Step S910, based on the target power distribution ratio of multiple interconnected converters, using hysteresis control to construct an operating state adjustment function for the multiple interconnected converters, where the independent variable of the operating state adjustment function is the total power of the interconnected converter group, and the dependent variable is the adjustment coefficient; Step S920, based on the operating state adjustment function, adjust the respective load powers of the multiple interconnected converters to the respective target input powers of the multiple interconnected converters.

[0114] Step S910, based on the target power distribution ratio of multiple interconnected converters, using hysteresis control to construct an operating state adjustment function for the multiple interconnected converters, where the independent variable of the operating state adjustment function is the target input power, and the dependent variable is the adjustment coefficient.

[0115] In the example, taking the interconnected converter group including 3 interconnected converters as an example, from Figure 6From the system power distribution curve, when 3 interconnected converters operate at full load, the load power is 1 p.u., and when a single interconnected converter operates at full load, P is 1 / 3 p.u. When the load power of the interconnected converter group is 0 ≤ P ≤ 0.313 p.u., only 1 interconnected converter participates in power transmission, and this interconnected converter is denoted as Interconnected Converter One. When the load power of the interconnected converter group is 0.313 < P ≤ 0.525 p.u., 2 interconnected converters participate in power transmission, namely Interconnected Converter One and Interconnected Converter Two; among them, when the load power of the interconnected converter group is 0.313 < P ≤ 0.334 p.u., Interconnected Converter Two operates at a constant power of 0.133 p.u., and Interconnected Converter One increases as the load power of the interconnected converter group increases; when the load power of the interconnected converter group is 0.334 < P ≤ 0.525 p.u., Interconnected Converter One and Interconnected Converter Two operate in a power sharing mode, that is, the transmission power of each interconnected converter is P / 2. When the load power of the interconnected converter group is 0.525 < P ≤ 1 p.u., Interconnected Converter One, Interconnected Converter Two, and Interconnected Converter Three all participate in power transmission; among them, when the load power of the interconnected converter group is 0.525 < P ≤ 0.6 p.u., Interconnected Converter One and Interconnected Converter Two operate at a constant power of 0.2 p.u., and Interconnected Converter Three increases as the transmission power increases; when the load power of the interconnected converter group is 0.6 < P ≤ 1 p.u., the 3 interconnected converters operate in a power sharing mode.

[0116] To avoid frequent switching of the operating mode of the interconnected converter due to power fluctuations, power hysteresis control is introduced for the switching of the operating mode of the interconnected converter, and the hysteresis bandwidth H p is 0.01 p.u. A function for adjusting the operating state of multiple interconnected converters is constructed, and the operating state functions of the interconnected converters are shown in Equations (7) to (10) respectively.

[0117]

[0118]

[0119]

[0120]

[0121] Among them, S1 to S4 are adjustment coefficients, P is the total power of the interconnected converter group, and H p is the hysteresis bandwidth.

[0122] Step S920: Based on the operating state adjustment function, the respective load powers of multiple interconnected converters can be adjusted to the respective target input powers of the multiple interconnected converters.

[0123] As known from Equations (7) to (10), when S1 to S4 = 1, the interconnected converter switches its operating mode, and when S1 to S4 = 0, the operating modes of multiple interconnected converters remain unchanged.

[0124] Based on the operating state function of the interconnected converter, the respective load powers of multiple interconnected converters can be corrected as follows:

[0125]

[0126] where p2 is the load power of the second interconnected converter, p3 is the load power of the third interconnected converter, and P1 * 、P2 * 、P3 * respectively represent the corrected power distribution values of the first, second, and third interconnected converters.

[0127] Exemplarily, to ensure the safe operation of the power grid, the interconnected converter usually adopts constant DC voltage control. The active powers of three parallel interconnected converters are:

[0128]

[0129] where E d is the amplitude of the AC grid voltage; i d1 、i d2 、i d3 are the d-axis currents of the three interconnected converters respectively, and P1, P2, and P3 are the powers allocated to the three interconnected converters respectively.

[0130] Then the power distribution ratios of each interconnected converter are:

[0131]

[0132] where P1, P2, and P3 are the powers allocated to the three interconnected converters respectively, and i d1 、i d2 、i d3 are the d-axis currents of the three interconnected converters respectively.

[0133] According to the power distribution ratios of each interconnected converter, the d-axis current i K * of the i-th interconnected converter is:

[0134]

[0135] where i d * is the given value of the total current of the power grid, P i is the load power of the i-th interconnected converter, and P1, P2, and P3 are the powers allocated to the three interconnected converters respectively, and iK * is the d-axis current of the i-th interconnected converter.

[0136] Exemplarily, in the related art, a proportional integral controller (PI) can be used to adjust the respective load powers of multiple interconnected converters to their respective target input powers by means of a Sinusoidal Pulse Width Modulation (SPWM) modulation method.

[0137] In the embodiments of the present application, by obtaining the power distribution of the converters online and constructing an operating state adjustment function of multiple interconnected converters in combination with power hysteresis control, the respective load powers of the interconnected converters can be adjusted to their respective target input powers, which can timely adjust the respective load powers of the interconnected converters and at the same time reduce the probability of frequent switching of multiple interconnected converters, making the operation of the power grid more stable.

[0138] According to another aspect of the present application, a control device for an interconnected converter group for a power grid is also provided.

[0139] Figure 10 FIG. shows a structural block diagram of a control device 1000 for an interconnected converter group for a power grid according to an embodiment of the present application.

[0140] The interconnected converter group includes multiple interconnected converters electrically connected, as Figure 10 shown, the control device 1000 for the interconnected converter group for the power grid includes: an acquisition module 1010 configured to acquire the efficiency values when the load powers of multiple interconnected converters in the power grid; a calculation module 1020 configured to determine the target power distribution ratio of multiple interconnected converters based on the efficiency values when the load powers of multiple interconnected converters, where the target power distribution ratio is the ratio of the power of each interconnected converter to the total power; a determination module 1030 configured to determine the respective target input powers of multiple interconnected converters based on the target power distribution ratio of multiple interconnected converters.

[0141] Since the acquisition module 1010, the calculation module 1020, and the determination module 1030 in the control device 1000 for the interconnected converter group for the power grid can respectively correspond to steps 110, 120, and 130 as Figure 1 shown, details of each aspect thereof will not be elaborated here.

[0142] In addition, the control device for the interconnected converter group for the power grid and the modules included therein may further include further sub-units, which will be described below in combination with Figure 11 and Figure 12Further description.

[0143] According to an embodiment of the present application, by obtaining the efficiency values when each load power of multiple interconnected converters in the power grid, and taking the efficiency value of the interconnected converter group as the target, the ratio of the power of each interconnected converter to the total power is determined, so that the power distribution of multiple interconnected converters can satisfy the optimal total efficiency of the interconnected converter group, thereby improving the operation efficiency of the interconnected converter group.

[0144] Figure 11 The structural block diagram of the calculation module 1020 according to an embodiment of the present application is shown.

[0145] In one example, the calculation module 1020 may include: a first function construction unit 1021, configured to construct an efficiency function of the interconnected converter based on the efficiency values when each load power of the interconnected converter, where the independent variable of the efficiency function is the load power and the dependent variable is the efficiency value; a second function construction unit 1022, configured to construct a total efficiency function of the interconnected converter group based on the respective efficiency functions of multiple interconnected converters; a function solving unit 1023, configured to solve the total efficiency function based on preset constraint conditions to determine the target power distribution ratio of multiple interconnected converters, and the target power distribution ratio satisfies the optimal total efficiency of the interconnected converter group.

[0146] According to some embodiments, the preset constraint conditions include that the total power of the interconnected converter group is the sum of the powers of multiple interconnected converters, and the power of the interconnected converter is not greater than the rated power.

[0147] In one example, the calculation module 1020 may include: an offline calculation unit, configured to offline calculate the target power distribution ratio of multiple interconnected converters based on the efficiency values when each load power of the interconnected converter.

[0148] According to some embodiments of the present application, the control device for the interconnected converter group for the power grid further includes: a numerical processing module, configured to perform per-unit processing on the power of the interconnected converter.

[0149] Figure 12 The structural block diagram of the determination module 1030 according to an embodiment of the present application is shown.

[0150] In one example, the determination module 1030 may include: a tabulation unit 1031, configured to tabulate the target power distribution ratio of multiple interconnected converters to form a target power distribution ratio look-up table; a lookup unit 1032, configured to look up the respective target input powers of multiple interconnected converters from the target power distribution ratio look-up table.

[0151] According to some embodiments of the present application, the control device 1000 for an interconnected converter group of a power grid may further include: a function construction module 1040 configured to construct an operating state adjustment function of multiple interconnected converters by using hysteresis control based on the target power distribution ratio of the multiple interconnected converters, where the independent variable of the operating state adjustment function is the total power of the interconnected converter group and the dependent variable is the adjustment coefficient; and an adjustment module 1050 configured to adjust the respective load powers of the multiple interconnected converters to their respective target input powers based on the operating state adjustment function.

[0152] According to another aspect of the present application, there is also provided an electronic device including a memory and a processor, where the memory is used to store computer-executable instructions; and the processor is used to access the memory and execute the computer-executable instructions to perform the operations in the detection method in any one of the foregoing embodiments.

[0153] In one embodiment, the processor may be an integrated circuit chip with signal processing capabilities. During implementation, the steps of the foregoing method embodiments may be completed by the integrated logic circuit in the hardware of the processor or by instructions in software form. The foregoing processor may be a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods and steps disclosed in the embodiments of the present application. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of the present application may be directly embodied as being executed and completed by a hardware decoding processor, or by a combination of hardware and software modules in the decoding processor. The software module may be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. This storage medium is located in the memory, and the processor reads the information in the memory and combines its hardware to complete the steps of the foregoing method.

[0154] In one embodiment, the memory may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a Read-Only Memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically EPROM (EEPROM), or a flash memory. The volatile memory may be a Random Access Memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and Direct Rambus RAM (DRRAM). It should be noted that the memory of the systems and methods described herein is intended to include but not be limited to these and any other suitable types of memory.

[0155] According to another aspect of the present application, there is also provided a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the method of any one of the foregoing embodiments is implemented.

[0156] According to another aspect of the present application, there is also provided a computer program product, including computer-readable code, or a non-volatile computer-readable storage medium carrying the computer-readable code, and when the computer-readable code runs in an electronic device, the processor in the electronic device executes the method of any one of the foregoing embodiments.

[0157] It should be understood that although the steps in the flowcharts involved in the above embodiments are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication in this article, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same moment, but can be executed at different moments. The execution order of these steps or stages is not necessarily sequential, but can be executed alternately or in turn with at least a part of other steps or steps or stages in other steps.

[0158] According to an embodiment of the present application, the interconnected converter group in the power grid can be controlled by the following method.

[0159] Figure 13 The flow of the control method for the interconnected converter group for the power grid according to the embodiment of the present application is shown Figure 3 , as Figure 13 shown, the interconnected converter group includes 3 interconnected converters connected electrically.

[0160] First, the efficiency curve of the interconnected converter in the power grid can be obtained. The load power of the efficiency curve of the interconnected converter is its horizontal axis, and the efficiency value is its vertical axis.

[0161] Next, based on the efficiency values at each load power of the interconnected converter, the efficiency function of the interconnected converter can be constructed, and the total efficiency function of the interconnected converter group can be constructed based on the respective efficiency functions of the 3 interconnected converters. Subsequently, the power of the interconnected converter can be normalized, and based on the total power of the interconnected converter group being the sum of the powers of multiple interconnected converters, and the power of the interconnected converter not being greater than the rated power as a preset constraint condition, the target power distribution ratio of the 3 interconnected converters can be calculated offline, that is, the ratio of the power of each interconnected converter to the total power of the interconnected converter group. The target power distribution ratio satisfies the total efficiency of the interconnected converter group to be optimal.

[0162] After determining the ratio of the power of each interconnected converter to the total power of the interconnected converter group, based on the target power distribution ratio of multiple interconnected converters, hysteresis control is adopted to construct the operation state adjustment function of multiple interconnected converters. The independent variable of the operation state adjustment function is the total power P of the interconnected converter group, and the dependent variables are the adjustment coefficients S1, S2, S3, and S4.

[0163] Next, the target power distribution ratios of the three interconnected converters can be made into a target power distribution ratio look-up table; and the respective target power distribution ratios of the three interconnected converters can be found from the target power distribution ratio look-up table, so that the respective target input powers of the multiple interconnected converters can be determined according to the respective target power distribution ratios of the three interconnected converters.

[0164] Specifically, based on the operating state adjustment function, the d-axis total current can be output by the PI regulator in the outer voltage loop. According to the target power distribution ratios of the three interconnected converters, the current reference commands of each interconnected converter can be obtained. The inner current loop also uses a PI regulator and adopts the SPWM modulation method to adjust the respective load powers of the three interconnected converters to the respective target input powers P1, P2, and P3 of the three interconnected converters.

[0165] The control method for the interconnected converter group for the power grid in this application can be verified based on the electromagnetic transient simulation software (Power Systems Computer Aided Design, PSCAD). In the simulation, six working conditions can be set as shown in the following table:

[0166]

[0167] As shown in the above table. When t < 0.5 s (s), P = -0.5 p.u. (when P < 0, power is transmitted from the DC system to the AC system; conversely, when P > 0, power is transmitted from the AC system to the DC system); when 0.5 s < t < 1 s, P = -0.3 p.u.; when 1 s < t < 1.5 s, P = -0.7 p.u.; when 1.5 s < t < 2 s, P = 0.525 p.u.; when 2 s < t < 2.5 s, P = 0.323 p.u.; when 2.5 s < t < 3 s, P = 0.6 p.u.

[0168] Under the above working conditions, according to the self-adaptive power optimization control strategy shown in the above table, the outer loop is a constant DC bus voltage control, and the DC bus voltage is controlled at 1.0 p.u. to ensure the safe operation of the system. Figure 14 shows the simulation waveform of the DC bus voltage according to an embodiment of the present application, as Figure 14 shown, the simulation value of the DC bus voltage is the same as the actual value at 1.0 p.u. That is to say, the outer loop control strategy is effective.

[0169] Figure 15 shows a schematic diagram of the theoretical values of the distributed powers of the three interconnected converters according to an embodiment of the present application, Figure 16 shows the actual simulation waveforms of the three interconnected converters according to an embodiment of the present application. As Figure 15 and Figure 16As shown, the target input power of each of the three interconnected converters determined by the control method of the interconnected converter group for the power grid according to the above embodiments of the present application is the same as the target input power of each of the three interconnected converters calculated theoretically.

[0170] In addition, in order to verify the effectiveness of the control method of the interconnected converter group for the power grid according to the above embodiments of the present application, two common operating modes of the three interconnected converters and the control mode of the control method of the interconnected converter group for the power grid of the present application are defined as follows:

[0171] Mode 1: Power equalization mode, where the operating power is evenly distributed among the parallel converters.

[0172] Mode 2: Hierarchical switching mode, where the number of interconnected converters is switched in a hierarchical manner according to the load condition. When a new interconnected converter is put into operation, the interconnected converters that have already been put into operation are all operating at full load.

[0173] Mode 3: Optimal control mode, where, according to the load condition, the total efficiency of the interconnected converter group is optimized, and the power distribution of multiple interconnected converters is optimized online.

[0174] Under the above 6 working conditions, the operating efficiencies of the three interconnected converters using power optimization control (Yz), hierarchical control (Yf), and power equalization control (Yj) are simulated respectively. Figure 17 The efficiency simulation results of the three interconnected converters according to the embodiments of the present application in three operating modes are shown. As Figure 17 shown, under six different working conditions, the total efficiency of the interconnected converter group of the control method of the interconnected converter group for the power grid of the present application is the optimal.

[0175] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be covered by the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A control method for an interconnected converter group of a power grid, the interconnected converter group comprising a plurality of interconnected converters electrically connected, characterized in that, The method includes: Obtaining the efficiency values when the multi - interconnected converters in the power grid have respective load powers; Based on the efficiency values when the multi - interconnected converters have respective load powers, determining the target power distribution ratio of the multi - interconnected converters, where the target power distribution ratio is the ratio of the power of each interconnected converter to the total power; Based on the target power distribution ratio of the multi - interconnected converters, determining the respective target input powers of the multi - interconnected converters.

2. The method according to claim 1, characterized in that, The determining the target power distribution ratio of the multi - interconnected converters based on the efficiency values when the multi - interconnected converters have respective load powers includes: Based on the efficiency values when the interconnected converters have respective load powers, constructing an efficiency function of the interconnected converter, where the independent variable of the efficiency function is the load power and the dependent variable is the efficiency value; Based on the respective efficiency functions of the multi - interconnected converters, constructing a total efficiency function of the interconnected converter group; Solving the total efficiency function based on preset constraint conditions to determine the target power distribution ratio of the multi - interconnected converters, where the target power distribution ratio satisfies that the total efficiency of the interconnected converter group is optimal.

3. The method according to claim 2, wherein The preset constraint conditions include that the total power of the interconnected converter group is the sum of the powers of the multi - interconnected converters, and the power of the interconnected converter is not greater than the rated power.

4. The method according to claim 1, wherein The determining the target power distribution ratio of the multi - interconnected converters based on the efficiency values when the multi - interconnected converters have respective load powers includes: Based on the efficiency values when the interconnected converters have respective load powers, calculating the target power distribution ratio of the multi - interconnected converters offline.

5. The method according to any one of claims 1 to 4, characterized in that, The method further includes: Performing per - unit processing on the power of the interconnected converter.

6. The method according to any one of claims 1 to 5, characterized in that The determining the respective target input powers of the multi - interconnected converters based on the target power distribution ratio of the multi - interconnected converters includes: Making a target power distribution ratio look - up table for the target power distribution ratios of the multi - interconnected converters; Looking up the respective target input powers of the multi - interconnected converters from the target power distribution ratio look - up table.

7. The method according to any one of claims 1 to 6, characterized in that The method further includes: Based on the target power distribution ratio of the multi - interconnected converters, using hysteresis control to construct an operating state adjustment function of the multi - interconnected converters, where the independent variable of the operating state adjustment function is the total power of the interconnected converter group and the dependent variable is the adjustment coefficient; Based on the operating state adjustment function, adjusting the respective load powers of the multi - interconnected converters to the respective target input powers of the multi - interconnected converters.

8. A control device for an interconnected converter group of a power grid, the interconnected converter group comprising a plurality of interconnected converters electrically connected, characterized in that, The method includes: An acquisition module, configured to obtain the efficiency values when the multi - interconnected converters in the power grid have respective load powers; A calculation module, configured to determine the target power distribution ratio of the multi - interconnected converters based on the efficiency values when the multi - interconnected converters have respective load powers, where the target power distribution ratio is the ratio of the power of each interconnected converter to the total power; A determination module, configured to determine the respective target input powers of the multi - interconnected converters based on the target power distribution ratio of the multi - interconnected converters.

9. The device according to claim 1, characterized in that, The calculation module includes: The first function construction unit is configured to construct an efficiency function of the interconnected converter based on the efficiency values at various load powers of the interconnected converter, where the independent variable of the efficiency function is the load power and the dependent variable is the efficiency value; The second function construction unit is configured to construct a total efficiency function of the interconnected converter group based on the respective efficiency functions of the multiple interconnected converters; The function solving unit is configured to solve the total efficiency function based on preset constraint conditions to determine the target power distribution ratio of the multiple interconnected converters, and the target power distribution ratio satisfies that the total efficiency of the interconnected converter group is optimal.

10. The device according to claim 9, characterized in that, The preset constraint conditions include that the total power of the interconnected converter group is the sum of the powers of the multiple interconnected converters, and the power of the interconnected converter is not greater than the rated power.

11. The device according to claim 1, characterized in that, The calculation module includes: The offline calculation unit is configured to offline calculate the target power distribution ratio of the multiple interconnected converters based on the efficiency values at various load powers of the interconnected converter.

12. The method according to any one of claims 7 to 11, characterized in that, The device further includes: The numerical processing module is configured to perform per-unit conversion on the power of the interconnected converter.

13. The device according to any one of claims 7 to 12, characterized in that, The determination module includes: The tabulation unit is configured to create a target power distribution ratio look-up table for the target power distribution ratios of the multiple interconnected converters; The look-up unit is configured to look up the respective target input powers of the multiple interconnected converters from the target power distribution ratio look-up table.

14. The device according to any one of claims 7 to 13, characterized in that The device further includes: The function construction module is configured to construct an operating state adjustment function of the multiple interconnected converters by using hysteresis control based on the target power distribution ratios of the multiple interconnected converters, where the independent variable of the operating state adjustment function is the total power of the interconnected converter group and the dependent variable is the adjustment coefficient; The adjustment module is configured to adjust the respective load powers of the multiple interconnected converters to the respective target input powers of the multiple interconnected converters based on the operating state adjustment function.

15. An electronic device, comprising a memory and a processor, the memory storing a computer program that can run on the processor, wherein, When the processor executes the program, it implements the method according to any one of claims 1 to 7.

16. A computer-readable storage medium having a computer program stored thereon, wherein, When the computer program is executed by the processor, it implements the method according to any one of claims 1 to 7.

17. A computer program product, including computer-readable code, or a non-volatile computer-readable storage medium carrying the computer-readable code, when the computer-readable code runs in an electronic device, the processor in the electronic device executes the method according to any one of claims 1 to 7.

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