A line reactive power control method based on distributed power group control and group modulation

Abstract

The present invention demonstrates a method for reactive power management of a line based on group control and group modulation of distributed power sources, comprising a terminal device, a distributed power source, a photovoltaic inverter, and a line. The line is provided with a number of photovoltaic sites. The terminal device is provided with a zeroing time T0, a repetition time T1, and a target value S of the line power factor. The present invention divides all distributed power sources under the line into a sub-cluster for unified scheduling, aggregates the reactive output and adjustable reactive power of each photovoltaic site, and performs unified scheduling by the present invention. By adjusting the reactive output of the photovoltaics, the reactive power balance management purpose of the line is achieved.

Description

Technical field

[0001] The present invention discloses a line reactive power management method based on distributed power supply group control and group modulation, belonging to the technical field of line reactive power management methods. [Background Technology]

[0002] While the large-scale use of clean energy effectively improves energy efficiency and the ecological environment, while each distributed power source enhances microgrid control capabilities, its operational safety must also be considered. For example, rapid voltage fluctuations, such as frequency or amplitude, can damage relays, indicator lights, and other equipment over time, while low voltage can render circuit breakers unreliable. To address this, a normal operating voltage range can be set, or self-coordination between the distributed power source and the energy storage system can be implemented to mitigate safety issues.

[0003] At present, there are many studies on the optimization strategies within microgrids, but there are fewer studies on the scheduling optimization between microgrids. Energy sharing among multiple microgrids effectively promotes the utilization rate of clean energy and improves the absorption of renewable energy such as photovoltaics. Zhao Huiru and others from North China Electric Power University took energy sharing among multiple communities as the research object, conducted energy interaction through internal protocols, and proposed a distributed blue-robust optimization scheduling model for a multi-community photovoltaic storage system. They also took into account energy sharing among communities and joint demand response to optimize the overall benefits. Invention CN202110675292.9 proposes a distributed photovoltaic group scheduling and control system and method, which enables photovoltaic elements to provide active and reactive power, effectively reducing line losses.

[0004] Although invention CN202110675292.9 can control the active and reactive power of photovoltaics, during the operation of the photovoltaic system, under the condition of overall safety of the power grid, intervention in the active power of photovoltaics should be minimized, and the active power of photovoltaics can only be adjusted downward, which cannot achieve the purpose of controlling the reactive power balance of the line. [Summary of the invention]

[0005] The technical problem to be solved by the present invention is to provide a line reactive power management method based on distributed power supply group control and group modulation, which can achieve reactive power balance optimization of the line.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for controlling reactive power of a line based on group control and group modulation of distributed power sources includes a terminal device, a distributed power source, a photovoltaic inverter, and a line. The line is provided with a plurality of photovoltaic sites. The terminal device is provided with a zeroing time T0, a repetition time T1, and a target value S of the line power factor. The steps of the method for controlling reactive power of the line are as follows:

[0008] S1. The terminal device reads the current system time t. When tT0, the terminal device sends a zero remote adjustment instruction to the distributed power source to set the photovoltaic reactive power adjustable value of all lines to zero;

[0009] S2. The terminal device reads the power factor COS and duration T of the current line. S , when COS< target value S and T S If the value is greater than 60 seconds, continue to execute the following steps; otherwise, return to step S1;

[0010] S3, the terminal device calculates the photovoltaic reactive power adjustment amount α according to the current power factor COS and the target value S;

[0011] S4. The terminal device reads the photovoltaic reactive adjustable value β of the line, and compares the photovoltaic reactive adjustable value α with the photovoltaic reactive adjustable value β. After the comparison is completed, the terminal device sends a reactive remote adjustment instruction. When β ≥ 120% α, the photovoltaic reactive adjustable value is α; when β < 120% α, the photovoltaic reactive adjustable value is 80% β.

[0012] S5. The terminal device distributes reactive power remote regulation instructions according to the regulation margin of each photovoltaic site, distributes the photovoltaic reactive power regulation amount according to the reactive power adjustable ratio of each photovoltaic site, and sends the allocated reactive power remote regulation instructions to the photovoltaic inverter;

[0013] S6. After the reactive power remote adjustment instruction is sent, the terminal device waits for a repetition time of T1 seconds and then executes S1 again.

[0014] The beneficial effects of the present invention are:

[0015] The terminal device described in the present invention calculates the photovoltaic reactive adjustment α through the power factor COS and the target value of the current line, and reads the photovoltaic reactive adjustable amount β of the line. By comparing the photovoltaic reactive adjustment α with the photovoltaic reactive adjustable amount β, the photovoltaic reactive adjustment amount is finally determined. Since the construction capacity of each photovoltaic site is different, the terminal device described in the present invention distributes reactive remote adjustment instructions according to the adjustment margin of each photovoltaic site, and distributes the photovoltaic reactive adjustment amount according to the reactive adjustable ratio of each photovoltaic site. The allocated reactive remote adjustment instructions are issued to the photovoltaic inverter. The present invention divides all distributed power sources under the line into a sub-cluster for unified scheduling, summarizes the reactive output and adjustment margin of each photovoltaic site, and performs unified scheduling by the present invention. By adjusting the photovoltaic reactive output, the purpose of reactive balance management of the line is achieved.

[0016] As an advantage, the terminal device reads the current system time t, reactive power adjustable quantity β, power factor COS and its duration T every 15 seconds. S .

[0017] As an advantage, the terminal device is provided with a transition value and a progressive amount, the transition value is less than the target value S, the power factor COS in S2 is compared with the transition value, and when the COS is less than the transition value and T S >60 seconds, continue to execute S3; when the COS is greater than the transition value, the transition value is added to the progressive amount to form a new transition value, and re-execute S2 until the transition value is equal to the target value S.

[0018] Preferably, the calculation formula of the power factor COS is as follows:

[0019] COS=P / (P 2 +Q 2 ) 0.5

[0020] Where P represents the active power of the line, and Q represents the reactive power of the line.

[0021] Preferably, the terminal device in S1 detects whether reverse power transmission occurs, and when reverse power transmission occurs, sets the photovoltaic reactive power adjustable value of the line to zero.

[0022] Preferably, the target value S ranges from 0.95 to 0.99.

[0023] Preferably, the repetition time T1=120.

[0024] Preferably, the zeroing time T0 is 17:30.

[0025] Other features and advantages of the present invention will be disclosed in detail in the following specific embodiments and drawings.

Brief Description of the Drawings

[0026] The present invention will be further described below with reference to the accompanying drawings:

[0027] Figure 1 Flowchart of an embodiment of the present invention. [Specific implementation method]

[0028] The following is an explanation and description of the technical solutions of the embodiments of the present invention in conjunction with the drawings of the embodiments of the present invention. However, the following embodiments are only preferred embodiments of the present invention and are not exhaustive. Based on the embodiments in the implementation manner, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention 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 therefore should not be understood as limiting the present invention.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified with "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless expressly limited otherwise.

[0031] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0032] Example 1:

[0033] like Figure 1 As shown, this embodiment shows a line reactive power control method based on distributed power group control and group modulation, including a terminal device, a distributed power source, a photovoltaic inverter and a line. The line is provided with a plurality of photovoltaic sites. The terminal device is provided with a zeroing time T0, a repetition time T1 and a target value S of the line power factor. The steps of the line reactive power control method are as follows:

[0034] The terminal device reads the current system time t, reactive power adjustable value β, power factor COS and its duration T every 15 seconds. s At tT0, the terminal device sends a zero remote adjustment command to the distributed power source, setting the photovoltaic reactive power adjustable value of all lines to zero, and waits for the terminal device to read the system time again. In this embodiment, the zeroing time T0 is 17:30; the terminal device detects whether reverse power transmission occurs. If reverse power transmission occurs, the photovoltaic reactive power adjustable value of the line is set to zero, and waits for the terminal device to read the system time again;

[0035] The terminal device compares the power factor COS with the target value S. When the power factor is greater than the target value, that is, COS>S, and its duration is T s If the time is >60 seconds, continue to perform the following steps, otherwise wait for the terminal device to read the system time t, reactive power adjustable value β, power factor COS and its duration T again. s ;

[0036] In this embodiment, since the power factor cannot be directly adjusted to the target value S, a transition value and a progressive amount are provided in the terminal device. The transition value is less than the target value S. The terminal device compares the power factor COS with the transition value. When the COS is less than the transition value and T S >60 seconds, continue to execute the subsequent steps; when the COS is greater than the transition value, the transition value is added to the progressive amount to form a new transition value, and the power factor COS is compared with the new transition value again until the transition value is equal to the target value S. For example: the target value is set to 0.99, the transition value is set to 0.95, and the progressive amount is set to 0.01. First, the power factor COS is compared with the transition value. When COS>0.95, the transition value is added to the progressive amount to form a new transition value of 0.96. The power factor COS is compared with the new transition value until the transition value is equal to the target value. In this embodiment, the range of the target value S is 0.95-0.99, and the optimal value of the target value S is 0.99.

[0037] The terminal device calculates the photovoltaic reactive power adjustment amount α based on the current power factor COS and the target value S. The terminal device compares the photovoltaic reactive power adjustment amount α with the photovoltaic reactive power adjustable amount β. After the comparison is completed, the terminal device sends a reactive power remote adjustment instruction. When β ≥ 120% α, that is, the line has sufficient reactive power adjustable amount, the photovoltaic reactive power adjustment amount is α; when β < 120% α, that is, the line reactive power adjustable amount is insufficient, the photovoltaic reactive power adjustment amount is 80% β. The calculation formula of the power factor COS in this embodiment is as follows:

[0038] COS=P / (P 2 +Q 2 ) 0.5

[0039] The terminal device distributes reactive remote adjustment instructions according to the adjustment margin of each photovoltaic site, distributes the photovoltaic reactive adjustment amount according to the reactive adjustable ratio of each photovoltaic site, and sends the allocated reactive remote adjustment instructions to the photovoltaic inverter. After the reactive remote adjustment instructions are sent, the terminal device waits for a repetition time of T1 seconds. In this embodiment, the repetition time T1 is 120 seconds. The terminal device re-reads the current system time t, reactive adjustable amount β, power factor COS and its duration T s .

[0040] The terminal device described in this embodiment calculates the photovoltaic reactive adjustment α through the power factor COS of the current line and the target value. The terminal device reads the photovoltaic reactive adjustable amount β of the line, and finally determines the photovoltaic reactive adjustment amount by comparing the photovoltaic reactive adjustment α with the photovoltaic reactive adjustable amount β. Since the construction capacity of each photovoltaic site is different, the terminal device described in this embodiment distributes reactive remote adjustment instructions according to the adjustment margin of each photovoltaic site, distributes the photovoltaic reactive adjustment amount according to the reactive adjustable ratio of each photovoltaic site, and issues the allocated reactive remote adjustment instructions to the photovoltaic inverter. This embodiment divides all distributed power sources under the line into a sub-cluster for unified scheduling, summarizes the reactive output and adjustment margin of each photovoltaic site, and performs unified scheduling by this embodiment. By adjusting the photovoltaic reactive output, the reactive balance management purpose of the line is achieved.

[0041] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art will understand that the present invention includes, but is not limited to, the contents described in the drawings and the above specific embodiments. Any modifications that do not deviate from the functional and structural principles of the present invention are intended to be included within the scope of the claims.

Claims

1. A method for controlling reactive power of a line based on group control and group modulation of distributed power sources, characterized by: The system includes a terminal device, a distributed power source, a photovoltaic inverter, and a line. The line is provided with a plurality of photovoltaic sites. The terminal device is provided with a zeroing time T0, a repetition time T1, and a target value S of the line power factor. The steps of the line reactive power control method are as follows: S1. The terminal device reads the current system time t. When t=T0, the terminal device sends a zero remote adjustment instruction to the distributed power source to set the photovoltaic reactive power adjustable value of all lines to zero; S2. The terminal device reads the power factor COS and duration T of the current line. S , when COS< target value S and T S If the value is greater than 60 seconds, continue to execute the following steps; otherwise, return to step S1; S3, the terminal device calculates the photovoltaic reactive power adjustment amount α according to the current power factor COS and the target value S; S4. The terminal device reads the photovoltaic reactive adjustable value β of the line, and compares the photovoltaic reactive adjustable value α with the photovoltaic reactive adjustable value β. After the comparison is completed, the terminal device sends a reactive remote adjustment instruction. When β ≥ 120% α, the photovoltaic reactive adjustable value is α; when β < 120% α, the photovoltaic reactive adjustable value is 80% β. S5. The terminal device distributes reactive power remote adjustment instructions according to the reactive power adjustable amount of each photovoltaic site, distributes the photovoltaic reactive power adjustment amount according to the reactive power adjustable ratio of each photovoltaic site, and sends the allocated reactive power remote adjustment instructions to the photovoltaic inverter; S6. After the reactive power remote adjustment instruction is sent, the terminal device waits for a repetition time of T1 seconds and then re-executes S2.

2. The method for controlling reactive power of a line based on group control and group modulation of distributed power sources according to claim 1, characterized in that: The terminal device reads the current system time t, reactive power adjustable value β, power factor COS and its duration T every 15 seconds. S .

3. The method for controlling reactive power of a line based on group control and group modulation of distributed power sources according to claim 1, characterized in that: The terminal device is provided with a transition value and a progressive amount, the transition value is less than the target value S, the power factor COS in S2 is compared with the transition value, and when the COS is less than the transition value and T S >60 seconds, continue to execute S3; when the COS is greater than the transition value, the transition value is added to the progressive amount to form a new transition value, and re-execute S2 until the transition value is equal to the target value S.

4. The method for controlling reactive power of a line based on group control and group modulation of distributed power sources according to claim 1, characterized in that: The calculation formula of the power factor COS is as follows: COS=P / (P 2 +Q 2 ) 0.5 Where P represents the active power of the line, and Q represents the reactive power of the line.

5. The method for controlling reactive power of a line based on group control and group modulation of distributed power sources according to claim 1, characterized in that: The terminal device in S1 detects whether reverse power transmission occurs. When reverse power transmission occurs, the photovoltaic reactive power adjustable amount of the line is set to zero.

6. The method for controlling reactive power of a line based on group control and group modulation of distributed power sources according to claim 1, characterized in that: The target value S ranges from 0.95 to 0.

99.

7. The method for controlling reactive power of a line based on group control and group modulation of distributed power sources according to claim 1, characterized in that: The repetition time T1=120.

8. The method for controlling reactive power of a line based on group control and group modulation of distributed power sources according to claim 1, characterized in that: The zero-setting time T0 is 17:30.

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