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

Abstract

An embodiment of the present invention relates to a configuration method and device for a grid-connected inverter at a new energy plant. The method comprises the steps of: collecting port AC voltages of a plurality of the grid-connected inverters; sorting and classifying the collected port AC voltages according to preset rules; and power-configuring the plurality of grid-connected inverters based on the sorting and classification results. The technical solution provided by the embodiment of the present invention, by sorting and classifying the port AC voltages of the inverters and power-configuring the inverters based on the classification results, takes into account the functional capacity of the grid-connected inverters and energy storage systems of the new energy plant, with the goal of controlling each node to operate at a higher voltage as much as possible, adjusts the voltage at each point based on the active power output and equipment capacity, optimizes and comprehensively determines the reactive output requirements of the new energy inverters and energy storage systems, and determines the configuration requirements and reactive capacity of the SVG, thereby achieving the highest voltage operation, reducing the operating current, and reducing the loss of the collector line.

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 grid-connected inverter of a new energy plant. Background Art

[0002] Currently, natural regulation is mostly used to control the current within new energy plants and stations. That is, the new energy power is output according to 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 situation of the plant and station.

[0003] The above principles form a natural flow within the new energy plant, but the losses within the plant are not strictly controlled, resulting in low efficiency of the new energy plant and unable to be improved. 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 through the voltage feedback control of the inverter, comprehensively considering the active power output and equipment capacity to adjust the voltage at each point, thereby achieving the highest voltage operation.

[0005] To achieve the above object, according to a first aspect of the present invention, a method for configuring grid-connected inverters of a new energy plant is provided, wherein the new energy plant includes multiple grid-connected inverters, and the outputs of the multiple grid-connected inverters are connected to an AC system. The method comprises the following steps:

[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] Power configuration is performed on multiple grid-connected inverters 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 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 this 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 AC voltage at the port of the nth grid-connected inverter.

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

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

[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] Where, ΔS n Indicates the capacity margin of the corresponding grid-connected inverter.

[0032] Furthermore, the first preset condition includes:

[0033]

[0034] Where 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. The new energy plant includes multiple grid-connected inverters, and the outputs of the multiple grid-connected inverters are connected to an AC system. The device includes:

[0038] An acquisition module, configured to acquire the port AC voltages of a plurality of the grid-connected inverters;

[0039] A classification module, configured to sort and classify 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 the sorting and classification.

[0041] In summary, an embodiment of the present invention provides a configuration method and device for a grid-connected inverter for a new energy plant. The method includes the following steps: 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 power-configuring the multiple grid-connected inverters based on the sorting and classification results. The technical solution provided by an embodiment of the present invention, by sorting and classifying the port AC voltages of the inverters and power-configuring the inverters based on the classification results, takes into account the functional capacity of the grid-connected inverters and energy storage systems of the new energy plant, with the goal of controlling each node to operate at a higher voltage as much as possible, comprehensively adjusts the voltage at each point based on the active power output and equipment capacity, optimizes and comprehensively determines the reactive output requirements of the new energy inverters and energy storage systems, and determines the configuration requirements and reactive capacity of the SVG, thereby achieving the highest voltage operation, reducing the operating current, and reducing the loss of the collection line. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a control block diagram of the existing technology that adjusts voltage by outputting reactive power at a constant level;

[0043] Figure 2 This is a control block diagram of the existing technology for regulating AC voltage by outputting constant reactive power;

[0044] Figure 3 This is a schematic diagram of the new energy plant topology 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] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be 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 merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts 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 have the usual meanings understood by people with ordinary skills in the field to which the present invention belongs. The "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 "comprising" 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] Currently, natural regulation is often used to control the flow within renewable energy plants. This involves outputting renewable energy power based on the active power output of the inverter and zero reactive power output. SVG is used to adjust the voltage at the point of common coupling (PCC), and the energy storage system charges and discharges according to the actual active power output of the renewable energy plant. However, this regulation method creates a natural flow within the renewable energy plant, but does not strictly control losses within the plant, resulting in low efficiency and preventing improvements.

[0049] Figure 1 The control block diagram of the prior art for regulating voltage by outputting reactive power in a constant manner is shown in FIG. Figure 1 As shown in the figure, the existing new energy control mainly focuses on active power control and reactive power control, and adjusts the system DC voltage by constant reactive power output. In order to make voltage conditions more flexible, there is also a regulation method that targets AC voltage. Figure 2 The control block diagram of the prior art for regulating AC voltage by constant reactive power output is shown in FIG. However, AC voltage is greatly affected by the AC system and is closely related to the AC system power distribution. Therefore, it is difficult to achieve the purpose of regulating AC voltage simply through self-control.

[0050] Based on the existing technology, the embodiments of the present invention are based on the basic principles of power electronic inverters and design AC voltage closed-loop control for each inverter, so as to control the AC voltage at each point as high as possible, thereby reducing the output current and the loss of the internal collector line, thereby achieving 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 for a new energy plant. Figure 3 The topology 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 multiple grid-connected inverters are connected to the AC system. The PCC point of the new energy plant is the common connection point, which usually refers to the load connection point of more than one user in the power system. Figure 4 FIG. 1 shows a flow chart of a configuration method for a grid-connected inverter of a new energy plant 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. Collect the port AC voltages of multiple grid-connected inverters. This can be done by setting a voltage transformer at the inverter port. In this embodiment of the present invention, all grid-connected inverters in the new energy plant are set to constant 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, thereby ensuring the stable operation of the AC system and maximizing the operating voltage of the AC system. The target value of the constant 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: Sort and classify the collected multiple port AC voltages according to preset rules. In this embodiment of the present invention, the collected port AC voltages are sorted and classified according to the following rules based on their voltage values:

[0055] If U acn ≥U acM , then the AC voltage of the port is set to the first type 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 this 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 AC voltage at the port 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-class voltage, reduce the active power of the grid-connected inverter corresponding to the port AC voltage 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, reduce the active power of the grid-connected inverter corresponding to the port AC voltage 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. Search for a grid-connected inverter with the largest capacity margin in the third voltage category, that is, search for a grid-connected inverter corresponding to the largest value of the following expression:

[0068]

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

[0070] ​The system then determines 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 system continues searching for the next grid-connected inverter with the largest capacity margin until the second preset condition is met. Through these steps, the output active power of the new energy plant can be maintained constant.

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

[0072]

[0073] Where 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 denoted by the reactive power capacity. However, in actual AC systems, due to limited reactive power capacity and the influence of DC power flow control, the control value may not be achieved, resulting in low voltage and, in extreme cases, high voltage. The technical solution of the embodiments of the present invention releases some of the reactive power of the inverter through reasonable active power distribution, thereby achieving the purpose of voltage regulation.

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

[0078] An acquisition module, configured to acquire the port AC voltages of a plurality of the grid-connected inverters;

[0079] A classification module, configured to sort and classify 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 embodiment of the present invention, and its repeated description will be omitted here.

[0082] In summary, embodiments of the present invention relate to a configuration method and device for a grid-connected inverter at a new energy power plant. The method comprises the steps of: collecting port AC voltages of a plurality of the grid-connected inverters; sorting and classifying the collected port AC voltages according to preset rules; and power-configuring the plurality of grid-connected inverters based on the sorting and classification results. The technical solution provided by embodiments of the present invention, by sorting and classifying the port AC voltages of the inverters and power-configuring the inverters based on the classification results, takes into account the functional capacity of the grid-connected inverters and energy storage systems of the new energy power plant, 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 inverters and energy storage systems, and determining the configuration requirements and reactive capacity 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 merely exemplary and is not intended to imply that the scope of the present invention (including the claims) is limited to these examples; under the thinking 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 variations of 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 merely 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 appended to the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A configuration method for a grid-connected inverter for a new energy plant, characterized in that: The new energy plant includes a plurality of grid-connected inverters, the outputs of which are connected to an AC system. The method includes the following steps: Collecting the port AC voltage of the plurality of grid-connected inverters; the plurality of grid-connected inverters adopt constant AC voltage control, and the target value of the constant AC voltage control is: in, Indicates the target value of constant AC voltage control, Indicates the rated voltage of the AC system. Indicates the maximum operating voltage of the AC system. Indicates constant voltage coefficient; The collected multiple port AC voltages are sorted and classified according to preset rules, including: , then the AC voltage of the port is set to the first type voltage; like , then the AC voltage of the port is set to the second type of voltage; like , then the AC voltage of this port is set to the third type voltage; like , then the AC voltage of the port is set to the fourth category voltage; like , then the AC voltage of the port is set to Category V voltage; in, Indicates the The AC voltage at the ports of each grid-connected inverter; Power configuration is performed on multiple grid-connected inverters based on the results of the sorting and classification, including: if the port AC voltage is a first-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 inductive reactive output of the inverter and reduce the AC voltage; 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 output of the inverter and increase the AC voltage.

2. The method according to claim 1, characterized in that The step power value is determined according to the following formula: in, Indicates the step power value corresponding to the grid-connected inverter. Indicates the active power currently output by the grid-connected inverter. Indicates the capacity of the grid-connected inverter. Indicates the short-circuit capacity of the AC system, Indicates the reactive power currently output by the grid-connected inverter.

3. The method according to claim 2, characterized in that Power configuration of multiple grid-connected inverters is performed based on the sorting and classification results, and also includes: Searching for a grid-connected inverter with the largest capacity margin in the third voltage category; Determining whether the capacity margin of the grid-connected inverter meets a first preset condition; If the condition is satisfied, the step power 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.

4. The method according to claim 3, characterized in that The capacity margin is expressed using the following formula: in, Indicates the capacity margin of the corresponding grid-connected inverter.

5. The method according to claim 4, characterized in that The first preset condition includes: in, Indicates the total number of grid-connected inverters in the system.

6. The method according to claim 5, characterized in that The second preset condition includes: 。 7. A configuration device using the configuration method of a new energy plant grid-connected inverter according to any one of claims 1 to 6, characterized in that: The new energy plant station includes multiple grid-connected inverters, the outputs of which are connected to an AC system. The device includes: An acquisition module, configured to acquire the port AC voltages of a plurality of the grid-connected inverters; A classification module, configured to sort and classify 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 the sorting and classification.

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