Configuration method and device for grid-connected inverter of new energy plant station

Abstract

The embodiment of the invention relates to a configuration method and device for grid-connected inverters of a new energy plant station. The method comprises the following steps: collecting port alternating voltage of a plurality of grid-connected inverters; sorting and classifying the acquired AC voltages of the plurality of ports according to a preset rule; and performing power configuration on the plurality of grid-connected inverters according to a sorting and classifying result. According to the technical scheme provided by the embodiment of the invention, the port alternating voltage of the inverter is sorted and classified, the power configuration is performed on the inverter according to the classification result, the active power capability of the grid-connected inverter and the energy storage system of the new energy plant station is considered, and each node is controlled to operate at a relatively high voltage as a target as much as possible; the voltage of each point is adjusted by integrating the active power output and the equipment capacity, the reactive power output requirements of the new energy inverter and the energy storage system are optimally and comprehensively determined, and the configuration requirements and the reactive power of the SVG are determined, so that the effects of operating at the highest voltage, reducing the operating current and reducing the loss of a current collection line are achieved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of power system power control, and in particular to a configuration method and device for a new energy plant grid-connected inverter. Background Art

[0002] At present, natural regulation is mostly used for the power flow inside new energy plants and stations. That is, the new energy power is output in a way that the active power that the new energy inverter can generate and the reactive power generated is zero. SVG is used to adjust the voltage at the PCC point, and the energy storage system is charged and discharged according to the actual active power of the plant and station.

[0003] The above principles form a natural flow within the new energy plants and stations, and the losses within the new energy plants and stations are not strictly controlled, resulting in low efficiency of the new energy plants and stations and the inability to improve. Summary of the invention

[0004] Based on the above situation of the prior art, the purpose of the embodiments of the present invention is to provide a configuration method and device for a new energy plant grid-connected inverter, taking into account the functional capabilities of the new energy plant grid-connected inverter and the energy storage system, and adjusting the voltage at each point through voltage feedback control of the inverter, comprehensively considering the active power output and equipment capacity, thereby achieving the highest voltage operation.

[0005] To achieve the above object, according to a first aspect of the present invention, a configuration method of a grid-connected inverter of a new energy plant is provided, wherein the new energy plant comprises a plurality of grid-connected inverters, and the outputs of the plurality of grid-connected inverters are connected to an AC system, and the method comprises the steps of:

[0006] Collecting the port AC voltages of the plurality of grid-connected inverters;

[0007] Sorting and classifying the collected multiple port AC voltages according to preset rules;

[0008] The power of multiple grid-connected inverters is configured according to the results of the sorting and classification.

[0009] Furthermore, the plurality of grid-connected inverters adopt constant AC voltage control, and the target value of the constant AC voltage control is:

[0010] U acref =U acN +k(U acM -U acN )

[0011] Among them, U acref Indicates the target value of constant AC voltage control, U acN Indicates the rated voltage of the AC system, U acM It represents the maximum operating voltage of the AC system, and k represents the constant voltage coefficient.

[0012] Furthermore, the collected multiple port AC voltages are sorted and classified according to preset rules, including:

[0013] If U acn ≥U acM , then the AC voltage of the port is set to the first type of voltage;

[0014] If U acref acn acM , then the AC voltage of the port is set to the second type of voltage;

[0015] If U acn =U acref , then the AC voltage of the port is set to the third type voltage;

[0016] If U acN acn acref , then the AC voltage of the port is set to the fourth category voltage;

[0017] If U acn ≤U acN , then the AC voltage of the port is set to Category V voltage;

[0018] Among them, u acn Indicates the port AC voltage of the nth grid-connected inverter.

[0019] Furthermore, power configuration is performed on multiple grid-connected inverters according to the sorting and classification results, including:

[0020] If the port AC voltage is the first type of voltage, the active power of the grid-connected inverter corresponding to the port AC voltage is reduced according to the corresponding step power value;

[0021] If the port AC voltage is a fifth category voltage, the active power of the grid-connected inverter corresponding to the port AC voltage is reduced according to the corresponding step power value.

[0022] Furthermore, the power step value is determined according to the following formula:

[0023]

[0024] Among them, DP n Indicates the power step value corresponding to the grid-connected inverter, P n Indicates the active power currently output by the grid-connected inverter, S n Indicates the capacity of the grid-connected inverter, S ac Indicates the short-circuit capacity of the AC system, Q n Indicates the reactive power currently output by the grid-connected inverter. ​​​​

[0025] Furthermore, power configuration is performed on a plurality of grid-connected inverters according to the results of the sorting and classification, and further includes:

[0026] Searching for a grid-connected inverter with the largest capacity margin in the third type of voltage;

[0027] Determining whether the capacity margin of the grid-connected inverter meets a first preset condition;

[0028] If the condition is satisfied, the power step value of the grid-connected inverter is increased; if the condition is not satisfied, the next grid-connected inverter with the largest capacity margin is searched for until the second preset condition is satisfied.

[0029] Furthermore, the capacity margin is expressed by the following formula:

[0030]

[0031] Among them, ΔS n Indicates the capacity margin of the grid-connected inverter.

[0032] Furthermore, the first preset condition includes:

[0033]

[0034] Wherein, N represents the total number of grid-connected inverters in the system.

[0035] Furthermore, the second preset condition includes:

[0036]

[0037] According to another aspect of the present invention, a configuration device for a grid-connected inverter of a new energy plant is provided, wherein the new energy plant includes a plurality of grid-connected inverters, and the outputs of the plurality of grid-connected inverters are connected to an AC system, and the device includes:

[0038] A collection module, used for collecting the port AC voltages of a plurality of the grid-connected inverters;

[0039] A classification module, used for sorting and classifying the collected multiple port AC voltages according to preset rules;

[0040] The power configuration module is used to perform power configuration on multiple grid-connected inverters according to the results of sorting and classification.

[0041] In summary, the embodiment of the present invention provides a configuration method and device for a grid-connected inverter of a new energy plant, the method comprising the steps of: collecting the port AC voltages of a plurality of the grid-connected inverters; sorting and classifying the collected multiple port AC voltages according to preset rules; and performing power configuration on the multiple grid-connected inverters according to the results of the sorting and classification. The technical solution provided by the embodiment of the present invention, by sorting and classifying the port AC voltages of the inverters, and performing power configuration on the inverters according to the classification results, takes into account the functional capabilities of the grid-connected inverters of the new energy plant and the energy storage system, with the goal of controlling each node to operate at a higher voltage as much as possible, comprehensively adjusting the voltage at each point based on the active power output and equipment capacity, optimizing and comprehensively determining the reactive output requirements of the new energy inverter and the energy storage system, and determining the configuration requirements and reactive capabilities of the SVG, thereby achieving the highest voltage operation, reducing the operating current, and reducing the loss of the collector line. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a control block diagram of the prior art for regulating voltage by means of constant output reactive power;

[0043] Figure 2 It is a control block diagram of the prior art for regulating AC voltage by means of constant output reactive power;

[0044] Figure 3 It is a schematic diagram of the topological structure of a new energy plant and inverter power configuration according to an embodiment of the present invention;

[0045] Figure 4 It is a flow chart of a configuration method of a new energy plant grid-connected inverter according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0047] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in one or more embodiments of the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in one or more embodiments of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0048] At present, natural regulation is mostly used in engineering for the flow inside new energy plants, that is, the new energy power is output in a way that the active power that the new energy inverter can generate and the reactive power generated is zero, and the voltage of the point of common coupling (hereinafter referred to as "PCC") is adjusted by SVG, and the energy storage system is charged and discharged according to the actual active power of the new energy plant. Based on the above regulation method, a natural flow is formed inside the new energy plant, and the loss inside the new energy plant is not strictly controlled, resulting in low efficiency of the new energy plant and unable to be improved.

[0049] Figure 1 The control block diagram of the prior art for regulating voltage by outputting reactive power constantly is shown in FIG. Figure 1 As shown in the figure, the existing new energy control is mainly based on active power control and reactive power control, and the system DC voltage is adjusted by constant reactive power output. In order to make the voltage condition more flexible, there is also an adjustment method that targets AC voltage. Figure 2 The control block diagram of the prior art for regulating AC voltage by outputting reactive power in a constant manner is shown in FIG. However, AC voltage is greatly affected by the AC system and is closely related to the power flow distribution of the AC system. It is difficult to achieve the purpose of regulating AC voltage simply by controlling itself.

[0050] Based on the existing technology, the embodiment of the present invention designs the AC voltage closed-loop control of each inverter based on the basic principle of power electronic inverter, and controls the AC voltage at each point at a high level as much as possible, thereby reducing the output current and reducing the loss of the internal collector line, so as to achieve high-efficiency operation of the new energy plant. The technical solution of the present invention is described in detail below with reference to the accompanying drawings. An embodiment of the present invention provides a configuration method for a grid-connected inverter of a new energy plant. Figure 3 The topology structure of the new energy plant and the schematic diagram of the inverter power configuration are shown in FIG. Figure 3As shown, the new energy plant includes multiple grid-connected inverters, such as inverter 1, inverter 2, inverter 3, ..., inverter n. The outputs of the multiple grid-connected inverters are connected to the AC system. The PCC point of the new energy plant is a public connection point, which usually refers to the load connection point of more than one user in the power system. Figure 4 FIG. 4 is a flow chart showing a configuration method of a new energy plant grid-connected inverter according to an embodiment of the present invention. Figure 4 As shown, the configuration method of the new energy plant grid-connected inverter provided by the embodiment of the present invention includes the following steps:

[0051] S202, collecting the port AC voltage of multiple grid-connected inverters, and the port AC voltage can be collected by setting a voltage transformer at the inverter port. In this embodiment of the present invention, all grid-connected inverters of the new energy plant are set to fixed AC voltage control, and the AC voltage control target value is set to the middle value between the rated AC voltage and the maximum AC voltage, so as to ensure the stable operation of the AC system and to increase the operating voltage of the AC system as much as possible. The target value of the fixed AC voltage control can be determined according to the following formula:

[0052] U acref =U acN +k(U acM -U acN )

[0053] Among them, U acref Indicates the target value of constant AC voltage control, U acN Indicates the rated voltage of the AC system, U acM represents the maximum operating voltage of the AC system, k represents the constant voltage coefficient, and in this embodiment, the value is 0.75.

[0054] S204, sorting and classifying the collected multiple port AC voltages according to preset rules. In this embodiment of the present invention, sorting and classifying are performed according to the voltage values ​​of the collected port AC voltages according to the following rules:

[0055] If U acn ≥U acM , then the AC voltage of the port is set to the first type of voltage;

[0056] If U acref acn acM , then the AC voltage of the port is set to the second type of voltage;

[0057] If U acn =U acref , then the AC voltage of the port is set to the third type voltage;

[0058] If U acN acn ​​​acref , then the AC voltage of the port is set to the fourth category voltage;

[0059] If U acn ≤U acN , then the AC voltage of the port is set to Category V voltage;

[0060] Among them, u acn Indicates the port AC voltage of the nth grid-connected inverter.

[0061] S206: Power configuration is performed on multiple grid-connected inverters according to the results of the sorting and classification. Figure 3 As shown, power configuration includes the following steps:

[0062] S2061. If the port AC voltage is a first type voltage, the active power of the grid-connected inverter corresponding to the port AC voltage is reduced according to the corresponding step power value to increase the inductive reactive power output of the inverter and reduce the AC voltage.

[0063] S2062: If the port AC voltage is a fifth category voltage, the active power of the grid-connected inverter corresponding to the port AC voltage is reduced according to the corresponding step power value to increase the capacitive reactive power output of the inverter and raise the AC voltage.

[0064] The power step value can be determined according to the following formula:

[0065]

[0066] Among them, DP n Indicates the power step value corresponding to the grid-connected inverter, P n Indicates the active power currently output by the grid-connected inverter, S n Indicates the capacity of the grid-connected inverter, S ac Indicates the short-circuit capacity of the AC system, Q n Indicates the reactive power currently output by the grid-connected inverter.

[0067] S2063. Find the grid-connected inverter with the largest capacity margin in the third type of voltage, that is, find the grid-connected inverter corresponding to the largest value of the following expression:

[0068]

[0069] Among them, ΔS n Indicates the capacity margin of the grid-connected inverter.

[0070] ​It is determined whether the capacity margin of the grid-connected inverter meets the first preset condition; if so, the power step value of the grid-connected inverter is increased; if not, the next grid-connected inverter with the largest capacity margin is continuously searched until the second preset condition is met. Through the above steps, the output active power of the new energy plant can be kept unchanged.

[0071] The first preset condition can be set as:

[0072]

[0073] Wherein, N represents the total number of grid-connected inverters in the system.

[0074] The second preset condition can be set as:

[0075]

[0076] The technical solution provided by the embodiment of the present invention regulates and controls the active power of the grid-connected inverter. acref The AC voltage control value is the AC voltage control value. However, in an actual AC system, due to the limited reactive capacity and the influence of DC power flow control, the control value may not be reached. Sometimes the voltage may be too low, and in extreme cases, the voltage may be too high. The technical solution of the embodiment of the present invention releases the reactive capacity of part of the inverter through reasonable active power distribution, thereby achieving the purpose of regulating the voltage.

[0077] An embodiment of the present invention further provides a configuration device for a grid-connected inverter of a new energy plant, wherein the new energy plant includes a plurality of grid-connected inverters, and the outputs of the plurality of grid-connected inverters are connected to an AC system, and the device includes:

[0078] A collection module, used for collecting the port AC voltages of a plurality of the grid-connected inverters;

[0079] A classification module, used for sorting and classifying the collected multiple port AC voltages according to preset rules;

[0080] The power configuration module is used to configure the power of multiple grid-connected inverters according to the results of sorting and classification.

[0081] Among them, the specific process of each module in the configuration device of the new energy plant grid-connected inverter to realize its function is the same as the steps of the configuration method of the new energy plant grid-connected inverter involved in the above-mentioned embodiment of the present invention, and its repeated description will be omitted here.

[0082] In summary, the embodiment of the present invention relates to a configuration method and device for a grid-connected inverter of a new energy plant, the method comprising the steps of: collecting the port AC voltages of a plurality of the grid-connected inverters; sorting and classifying the collected multiple port AC voltages according to preset rules; and performing power configuration on the multiple grid-connected inverters according to the results of the sorting and classification. The technical solution provided by the embodiment of the present invention, by sorting and classifying the port AC voltages of the inverters, and performing power configuration on the inverters according to the classification results, takes into account the functional capabilities of the grid-connected inverters of the new energy plant and the energy storage system, and aims to control each node to operate at a higher voltage as much as possible, adjusts the voltage of each point by comprehensively considering the active power output and equipment capacity, optimizes and comprehensively determines the reactive output requirements of the new energy inverter and the energy storage system, and determines the configuration requirements and reactive capabilities of the SVG, thereby achieving the highest voltage operation, reducing the operating current, and reducing the loss of the collector line.

[0083] It should be understood that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the present invention (including claims) is limited to these examples; under the idea of ​​the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of one or more embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity. The above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the scope of protection of the present invention. In addition, the claims attached to the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the attached claims, or the equivalent forms of such scope and boundaries.

Claims

1. A configuration method for a grid-connected inverter of a new energy plant, characterized in that: The new energy plant station includes a plurality of grid-connected inverters, and the outputs of the plurality of grid-connected inverters are connected to an AC system. The method includes the steps of: Collecting the port AC voltages of the plurality of grid-connected inverters; Sorting and classifying the collected multiple port AC voltages according to preset rules; The power of multiple grid-connected inverters is configured according to the results of the sorting and classification.

2. The method according to claim 1, characterized in that The plurality of grid-connected inverters adopt constant AC voltage control, and the target value of the constant AC voltage control is: IN acref =U acN +k(U acM -IN acN ) Among them, U acref Indicates the target value of constant AC voltage control, U acN Indicates the rated voltage of the AC system, U acM It represents the maximum operating voltage of the AC system, and k represents the constant voltage coefficient.

3. The method according to claim 2, characterized in that The collected multiple port AC voltages are sorted and classified according to preset rules, including: If U acn ≥U acM , then the AC voltage of the port is set to the first type of voltage; If U acref acn acM , then the AC voltage of the port is set to the second type of voltage;​​ If U acn =U acref , then the AC voltage of the port is set to the third type voltage; If U acN acn acref , then the AC voltage of the port is set to the fourth category voltage;​​ If U acn ≤U acN , then the AC voltage of the port is set to Category V voltage; Among them, u acn Indicates the port AC voltage of the nth grid-connected inverter.

4. The method according to claim 3, characterized in that According to the sorting and classification results, power configuration is performed for multiple grid-connected inverters, including: If the port AC voltage is the first type of voltage, the active power of the grid-connected inverter corresponding to the port AC voltage is reduced according to the corresponding step power value; If the port AC voltage is a fifth category voltage, the active power of the grid-connected inverter corresponding to the port AC voltage is reduced according to the corresponding step power value.

5. The method according to claim 4, characterized in that The power step value is determined according to the following formula: Among them, DP n Indicates the power step value corresponding to the grid-connected inverter, P n Indicates the active power currently output by the grid-connected inverter, S n Indicates the capacity of the grid-connected inverter, S ac Indicates the short-circuit capacity of the AC system, Q n Indicates the reactive power currently output by the grid-connected inverter.

6. The method according to claim 2, characterized in that The power configuration of multiple grid-connected inverters is performed according to the sorting and classification results, and also includes: Searching for a grid-connected inverter with the largest capacity margin in the third type of voltage; Determining whether the capacity margin of the grid-connected inverter meets a first preset condition; If the condition is satisfied, the power step value of the grid-connected inverter is increased; if the condition is not satisfied, the next grid-connected inverter with the largest capacity margin is searched for until the second preset condition is satisfied.

7. The method according to claim 6, characterized in that The capacity margin is expressed by the following formula: Among them, ΔS n Indicates the capacity margin of the grid-connected inverter.

8. The method according to claim 6, characterized in that The first preset condition includes: Wherein, N represents the total number of grid-connected inverters in the system.

9. The method according to claim 6, characterized in that The second preset condition includes:

10. A configuration device for a grid-connected inverter of a new energy plant, characterized in that: The new energy plant station includes a plurality of grid-connected inverters, the outputs of the plurality of grid-connected inverters are connected to an AC system, and the device includes: A collection module, used for collecting the port AC voltages of a plurality of the grid-connected inverters; A classification module, used for sorting and classifying the collected multiple port AC voltages according to preset rules; The power configuration module is used to perform power configuration on multiple grid-connected inverters according to the results of sorting and classification.

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