A reactive power compensation control method and system for distributed power supply for self-generation and self-use

Abstract

The present invention belongs to the technical field of electric power control, and discloses a reactive power compensation control system for self-generated and self-used distributed power sources, comprising a power generation meter, an online meter, a control device and a reactive power compensation device, wherein one end of the control unit is connected to the power generation meter, and the other end is connected to the online meter, the power generation meter is used to collect the generated current of the distributed power source, the online meter is used to collect the grid-connected current, and the control device is used to obtain the threshold parameters based on the generated current of the distributed power source and the grid-connected current data, perform logical judgment on the threshold parameters, and start the corresponding control strategy, thereby solving the problem of control device failure or frequent switching during the peak power generation period of the self-generated and self-used distributed power users, and providing stability of the reactive power compensation control system.

Description

Technical Field

[0001] The present invention relates to the field of power control technology, and in particular to a reactive power compensation control method and system for a self-generated and self-used distributed power source. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Distributed power generation is an important aspect of renewable energy application. The grid-connected power generation of distributed power sources changes the power flow direction of the distribution network, affecting the reactive power balance on the spot. The centralized layout of distributed power sources causes the reverse current to increase, which can easily cause line overload. The existing control system is unstable, especially during the peak period of photovoltaic power generation. Part of the active power on the user side is provided by the distributed power source, and the active current between the grid side and the user side is reduced. The phase angle control method can easily cause the reactive compensation control device to fail or frequently switch on and off, and the reactive compensation device cannot work normally. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a reactive power compensation control method and system for self-generated and self-used distributed power sources, which enable threshold parameters of different control strategies; control parameters for controlling the number of reactive compensation devices put into operation and removed under different strategies. In the process of self-generated and self-used distributed power sources connected to the grid for power generation, the present invention judges the power generation state of the distributed power sources on the user side, judges the operating conditions of the power consumption equipment on the user side, and calculates the amount of reactive power that needs to be compensated according to different strategies based on the different operating conditions of the power generation equipment and the power consumption equipment, and controls the switching of the reactive compensation devices. This can solve the problem of failure or frequent switching of control devices of users of self-generated and self-used distributed power sources during peak power generation periods, and improve the stability of the reactive compensation control system.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides a reactive power compensation control system for a self-generated and self-used distributed power source, comprising a power generation meter, an online meter, a control device and a reactive power compensation device, wherein one end of the control unit is connected to the power generation meter, and the other end is connected to the online meter, the power generation meter is used to collect the power generation current of the distributed power source, the online meter is used to collect the grid-connected current, and the control device is used to obtain the threshold parameters based on the distributed power generation current and the grid-connected current data, perform logical judgment on the threshold parameters, and start the corresponding control strategy.

[0007] Furthermore, the control device is also used to calculate control parameters based on the distributed power generation current and grid-connected current data, and control the number of reactive compensation devices put into operation and removed under the corresponding strategy according to the control parameters.

[0008] Furthermore, the reactive power compensation device includes a plurality of switching circuits, the switching circuits include a plurality of AC contactors, and the control device is used to control the switching of the capacitor device in the primary circuit through the AC contactors according to a control strategy.

[0009] Furthermore, the control strategy includes a current ratio control method and a phase difference control method.

[0010] A first aspect of the present invention provides a reactive power compensation control method for a self-generated and self-used distributed power source, comprising: acquiring power generation data of the distributed power source and grid-connected side data;

[0011] The threshold parameters are obtained according to the distributed generation data and the grid-connected data;

[0012] Make logical judgments on the threshold parameters and start the corresponding control strategy.

[0013] Furthermore, the calculation process of the threshold parameter includes:

[0014] A first threshold function and a second threshold function are obtained according to the distributed power generation data and the grid-connected side data, and the first threshold function and the second threshold function are subjected to logical judgment to obtain a threshold parameter.

[0015] Furthermore, performing a logical judgment on the threshold parameter and starting a corresponding control strategy includes: performing a logical judgment on the threshold parameter, if the threshold parameter is 1, starting a current ratio control method, and if the threshold parameter is 0, starting a phase difference control method.

[0016] Furthermore, the current ratio control method is:

[0017] According to the transformer capacity, calculate the maximum power consumption current of the user-side electrical equipment;

[0018] The control parameters are calculated by combining the maximum power consumption current of the user-side power equipment, the distributed power generation data and the grid-connected side data. The number of reactive compensation devices put into operation and removed under the corresponding strategy is controlled according to the control parameters.

[0019] Furthermore, the phase difference control method is: using a mutual inductor to sample voltage and current, and performing reactive compensation by calculating the phase difference.

[0020] Furthermore, controlling the number of reactive compensation devices put into operation and cut off under the corresponding strategy according to the control parameter includes: comparing the control parameter with a first threshold value, if the control parameter is greater than the first threshold value, switching on the first reactive compensation device; if the control parameter is greater than the second threshold value, switching on the second reactive compensation device; if the control parameter is greater than the third threshold value, switching on the third reactive compensation device.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention determines the power generation state of the distributed power supply at the user side, determines the operation state of the power consumption equipment at the user side, and starts different control strategies according to the different operation states of the power generation equipment and the power consumption equipment.

[0023] 2. During the process of self-generated and self-used distributed power sources connected to the grid, the present invention determines the power generation status of the distributed power sources on the user side, determines the operating conditions of the power consumption equipment on the user side, and calculates the amount of reactive power that needs to be compensated according to different strategies based on the different operating conditions of the power generation equipment and the power consumption equipment, and controls the switching of the reactive power compensation device, thereby solving the problem of control device failure or frequent switching during peak power generation periods for users of self-generated and self-used distributed power sources, and providing stability for the reactive power compensation control system.

[0024] 3. The present invention can reduce the damage to components of the reactive power compensation device, provide its use, and improve the power factor on the user side through reasonable reactive power compensation, thereby reducing the user's electricity expenses.

[0025] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings in the specification, which constitute a part of the present application, are used to provide further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0027] Figure 1 This is a schematic diagram of the overall structure of reactive power compensation control for self-generation and self-use distributed power sources according to Embodiment 1 of the present invention;

[0028] Figure 2 This is a schematic diagram of a switching circuit in Example 1 of the present invention;

[0029] Figure 3 This is a flow chart of the control method of Embodiment 2 of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0032] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0033] Example 1

[0034] In this embodiment, a self-generated and self-used distributed power supply reactive power compensation control system is disclosed, such as Figure 1 As shown, it includes a power generation meter, an online meter, a control device and multiple reactive power compensation devices, one end of the control device is connected to the power generation meter, and the other end is connected to the online meter, the power generation meter is used to collect the distributed power generation current data, the online meter is used to collect the grid-connected side current data, the control device is used to receive the distributed power generation current data and the grid-connected side current data to calculate the threshold parameters, the control device is used to obtain the threshold parameters according to the distributed power generation current and the grid-connected side current data, perform logical judgment on the threshold parameters, and start the corresponding control strategy.

[0035] The control device comprises a logic judgment unit therein, and the logic judgment unit is used to perform logic judgment on the threshold parameters.

[0036] Furthermore, the control strategy includes a current ratio control method and a phase difference control method.

[0037] Furthermore, the control device is also used to calculate control parameters based on the distributed power generation current and grid-connected current data, and control the number of reactive compensation devices put into operation and removed under the corresponding strategy according to the control parameters.

[0038] Furthermore, the reactive power compensation device includes a plurality of switching circuits, and the control device is used to calculate the amount of reactive power that needs to be compensated according to a control strategy, thereby controlling the switching of the switching circuits.

[0039] The switching of the control switching circuit can control the switching of the reactive compensation switch KM according to two control strategies: current ratio and phase angle, or it can be switched to a manual control button through SA.

[0040] like Figure 2 As shown, manual control or automatic control is selected through the conversion switch, and the switching of the capacitor equipment in the primary circuit is controlled by the AC contactor relays KM1, KM2, and KM3. The switching status of the capacitor equipment can be displayed by the indicator lights HL1, HL2, and HL3.

[0041] Example 2

[0042] In this embodiment, a reactive power compensation control method for a self-generated and self-used distributed power source is disclosed, such as Figure 3 As shown, the following steps are included:

[0043] S1: Obtain the distributed power generation current I1, the grid-connected current I2, and the maximum power generation current I of the distributed power generation max1 ; Among them, I1 is the sum of the three-phase current of the generator, and I2 is the sum of the three-phase current of the grid meter.

[0044] S2: Based on the distributed power generation current I1, the grid-connected current I2 and the distributed power generation maximum power generation current I max1 Calculate a first threshold function Y1 and a second threshold function Y2, and obtain a threshold parameter according to the threshold functions Y1 and Y2;

[0045] Specifically, the first threshold function is:

[0046] Y1=I1 / I MAX1 -0.05;

[0047] The second threshold function is:

[0048] Y2=(I1-I2) / I1-0.95;

[0049] The first threshold function and the second threshold function are logically judged to obtain the threshold parameter:

[0050] A third threshold function is obtained according to the first threshold function and the second threshold function, wherein the third threshold function is: y1=if(Y1>0,1,0), y2=if(Y2>0,1,0);

[0051] The specific meaning is:

[0052] If the distributed power generation current I1 is greater than 0.05 times the maximum power generation current I max1 , it is determined that the distributed power generation device is in working state, and the value of the first threshold function (i.e., the working flag function of the photovoltaic power generation device) y1 is 1, otherwise it is 0; if the grid-connected current I2 is less than 0.05 times the distributed power generation current I1, it is determined that the power load of the motor or other device is large, and the value of the second threshold function (i.e., the large load flag function of the power device) y2 is 1, otherwise it is 0.

[0053] The reference current direction is taken from the power generation side to the grid side. The actual current direction is taken as positive if it is consistent with the reference current direction, otherwise it is taken as negative.

[0054] Threshold parameter Y=y1*y2, if Y is 1, the current ratio control method is started, if Y is 0, the phase difference control method is started.

[0055] The current ratio control method comprises:

[0056] (1) According to the transformer capacity, calculate the maximum current I of the user-side electrical equipment max2 ; The maximum power generation is not greater than the transformer capacity;

[0057] (2) Based on the distributed power generation current I1, the grid-connected current I2 and the current I max2 The control parameter K is calculated; where K = (I1-I2) / I max2 .

[0058] (3) Based on the comparison between the control parameter and the first threshold value, if the control parameter is greater than 1 / 4 of the first threshold value, KM1 is closed and the first reactive compensation device is switched on; if the control parameter is greater than 1 / 2 of the second threshold value, KM2 is closed and the second reactive compensation device is switched on; if the control parameter is greater than 3 / 4 of the third threshold value, KM3 is closed and the third reactive compensation device is switched on.

[0059] The phase difference control method is: use the mutual inductor to sample the voltage and current, calculate the phase difference and perform reactive power compensation.

[0060] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage and optical storage, etc.) containing computer-usable program code.

[0061] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0062] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0063] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0064] A person skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0065] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A reactive power compensation control method for self-generated and self-used distributed power sources, characterized in that: Obtain distributed power generation data and grid-connected data; The threshold parameter Y is obtained according to the distributed power generation data and the grid-connected data; the calculation process of the threshold parameter Y includes: obtaining a first threshold function Y1 and a second threshold function Y2 according to the distributed power generation data and the grid-connected data, and obtaining the threshold parameter by performing logical judgment on the first threshold function Y1 and the second threshold function Y2; The first threshold function is: Y1 = I1 / I max1 -0.05; The second threshold function is: Y2 = (I1-I2) / I1-0.95; Among them, I1 is the distributed power generation current, I2 is the grid-connected current, I max1 is the maximum power generation current of the distributed power source; A third threshold function is obtained according to the first threshold function Y1 and the second threshold function Y2, wherein the third threshold function is: y1=if(Y1>0,1,0), y2=if(Y2>0,1,0); The threshold parameter Y=y1*y2; Perform logical judgment on the threshold parameter Y and start the corresponding control strategy; if the threshold parameter is 1, the current ratio control method is started, and if the threshold parameter is 0, the phase difference control method is started; The current ratio control method is: According to the transformer capacity, calculate the maximum power consumption current of the user-side electrical equipment; The control parameters are calculated by combining the maximum power consumption current of the user-side power equipment, the power generation data of the distributed power source and the grid-connected side data, and the number of reactive compensation devices put into operation and removed under the corresponding strategy is controlled according to the control parameters; the number of reactive compensation devices put into operation and removed under the corresponding strategy according to the control parameters includes: comparing the control parameter with a first threshold value, if the control parameter is greater than the first threshold value, switching on the first reactive compensation device; if the control parameter is greater than the second threshold value, switching on the second reactive compensation device; if the control parameter is greater than the third threshold value, switching on the third reactive compensation device; The phase difference control method is: using a mutual inductor to sample voltage and current, and performing reactive power compensation by calculating the phase difference.

2. A system adopting the reactive power compensation control method of distributed power sources for self-generation and self-use according to claim 1, comprising a power generation meter, an online meter, a control device and a reactive power compensation device, wherein one end of the control device is connected to the power generation meter, and the other end is connected to the online meter, the power generation meter is used to collect the power generation current of the distributed power source, the online meter is used to collect the grid-connected current, and the control device is used to obtain the threshold parameters based on the distributed power generation current and the grid-connected current data, perform logical judgment on the threshold parameters, and start the corresponding control strategy.

3. The system according to claim 2, characterized in that The control device is also used to calculate control parameters based on the distributed power generation current and grid-connected current data, and control the number of reactive compensation devices put into operation and removed under the corresponding strategy according to the control parameters.

4. The system according to claim 2, characterized in that The reactive power compensation device comprises a plurality of switching circuits, the switching circuits comprise a plurality of AC contactors, and the control device is used for controlling the switching of the capacitor device in the primary circuit through the AC contactors according to a control strategy.

5. The system according to claim 2, characterized in that The control strategy includes a current ratio control method and a phase difference control method.

Images