Non-ct-based power distribution low voltage line end unbalanced voltage compensation method

Abstract

The application discloses a power electronic control technical field based on a low-voltage line terminal unbalanced voltage compensation method of power distribution without a CT, and comprises the following steps: acquiring the voltage amplitude of the line terminal three-phase; calculating the average value of the three-phase voltage amplitude, comparing each phase voltage amplitude with the average value of the three-phase voltage amplitude, and obtaining the voltage deviation value of each phase; generating the active power compensation value of each phase through a PI algorithm according to the voltage deviation value of each phase, and then executing the active power compensation of each phase through an AC / DC energy storage conversion module; calculating the deviation value of the average value of the three-phase voltage and the voltage line reference voltage, generating the three-phase reactive power compensation value through a PI algorithm, and executing the three-phase reactive power compensation through an AC / DC energy storage conversion module and an intelligent reactance. The application can realize the regulation of three-phase voltage without installing a CT, and solves the problems of overvoltage, low voltage and three-phase voltage imbalance of a low-voltage line.

Description

Technical Field

[0001] This invention relates to a method for compensating unbalanced voltage at the end of a low-voltage distribution line without a current transformer (CT), and belongs to the field of power electronic control technology. Background Technology

[0002] Distribution networks are characterized by long lines, thin wire diameters, and unbalanced three-phase loads, making them prone to three-phase voltage imbalances and excessively high or low voltage at the terminals, resulting in voltage quality that fails to meet operational standards. This problem is exacerbated by the large-scale integration of distributed photovoltaic (PV) systems into low-voltage lines. Furthermore, the high penetration of distributed PV systems into the distribution network leads to significant backfeeding of PV power onto low-voltage lines, causing voltage spikes at the terminals. In severe cases, this can cause PV inverters to disconnect from the grid and burn out electrical equipment, severely hindering the integration of distributed PV systems.

[0003] Existing methods for addressing three-phase imbalance at the end of voltage lines require measuring three-phase voltage and current, and employing distributed energy storage or SVG (Static Var Generator) systems. These methods involve high-cost regulating equipment with limited capacity, and also require the installation of current transformers (CTs), making them difficult to implement and promote in field projects. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for unbalanced voltage compensation at the end of a low-voltage distribution line without a current transformer (CT). This method can achieve three-phase voltage regulation without the need for a CT and solve the problems of overvoltage, undervoltage, and three-phase voltage imbalance in low-voltage lines.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0006] In a first aspect, the present invention provides a method for unbalanced voltage compensation at the end of a low-voltage distribution line without a current transformer (CT), which is executed by a comprehensive regulating device installed at the end of the voltage line, comprising:

[0007] Obtain the voltage amplitude of the three phases at the end of the line;

[0008] Calculate the average value of the three-phase voltage amplitude, and compare the voltage amplitude of each phase with the average value of the three-phase voltage amplitude to obtain the voltage deviation value of each phase;

[0009] Based on the voltage deviation of each phase, the active power compensation value of each phase is generated by the PI algorithm, and then the active power compensation of each phase is performed by the AC / DC energy storage conversion module.

[0010] The deviation between the average three-phase voltage and the reference voltage of the voltage line is calculated. The three-phase reactive power compensation value is generated by the PI algorithm, and the three-phase reactive power compensation is performed by the AC / DC energy storage conversion module and the intelligent reactor.

[0011] Furthermore, the integrated regulation device includes an AC / DC energy storage conversion module and a smart reactor, wherein the AC / DC energy storage conversion module is capable of three-phase decoupled active and reactive bidirectional regulation, and the smart reactor is capable of three-phase phase-by-phase absorption of inductive reactive power.

[0012] Furthermore, the formula for calculating the average amplitude of the three-phase voltage is as follows:

[0013]

[0014] in, The average value of the three-phase voltage amplitude, V A V B V C These are the voltage amplitudes for phases A, B, and C, respectively.

[0015] Furthermore, by comparing the voltage of each phase with the average value of the three-phase voltage... By comparison, the voltage deviation values ​​of each phase are obtained, and the specific formula is as follows:

[0016]

[0017]

[0018]

[0019] Where, ΔV A ΔV B ΔV C These are the voltage deviation values ​​for each phase.

[0020] Furthermore, the calculation formula for the active power compensation value of each phase is as follows:

[0021] ΔP A =p1·ΔV A

[0022] ΔP B =p1·ΔV B

[0023] ΔP C =p1·ΔV C

[0024] Wherein, ΔP A ΔP B ΔP C These are the compensation values ​​for the three-phase active power, and p1 is the parameter of the PI algorithm.

[0025] Furthermore, the deviation between the average three-phase voltage and the reference voltage of the voltage line is calculated using the following formula:

[0026]

[0027] Where, ΔV set V represents the deviation between the average value of the three-phase average voltage and the reference voltage of the voltage line. set This is the reference voltage for the voltage circuit.

[0028] Furthermore, the calculation formula for the three-phase reactive power compensation value is as follows:

[0029] ΔQ set =p2·ΔV set

[0030] Where, ΔQ set p1 represents the three-phase reactive power compensation value, and p2 represents the parameters of the PI algorithm.

[0031] Secondly, the present invention provides a voltage imbalance compensation system at the end of a low-voltage distribution line without current transformers (CTs), comprising:

[0032] Voltage amplitude acquisition module: used to acquire the voltage amplitude of the three phases at the end of the line;

[0033] Deviation calculation module: used to calculate the average value of the three-phase voltage amplitude, and compare the voltage amplitude of each phase with the average value of the three-phase voltage amplitude to obtain the voltage deviation value of each phase;

[0034] Active power compensation module: It is used to generate active power compensation values ​​for each phase based on the voltage deviation values ​​of each phase through the PI algorithm, and then perform active power compensation for each phase through the AC / DC energy storage conversion module.

[0035] Reactive power compensation module: It is used to calculate the deviation between the average three-phase voltage and the reference voltage of the voltage line, generate three-phase reactive power compensation value through PI algorithm, and perform three-phase reactive power compensation through AC / DC energy storage conversion module and intelligent reactor.

[0036] Thirdly, the present invention provides a voltage compensation device for unbalanced voltage at the end of a low-voltage distribution line without a current transformer (CT), including a processor and a storage medium.

[0037] The storage medium is used to store instructions;

[0038] The processor is configured to operate according to the instructions to perform the steps of the method according to any of the foregoing.

[0039] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of any of the methods described above.

[0040] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0041] This invention provides a method for compensating unbalanced voltage at the end of a low-voltage distribution line without a current transformer (CT). This method, without the installation of a CT, utilizes an AC / DC energy storage conversion module and intelligent reactor in the integrated regulation equipment at the end of the line to regulate three-phase voltage imbalance and address overvoltage and undervoltage issues that commonly occur at the line end. It achieves dynamic regulation of the three-phase unbalanced voltage in low-voltage lines, is simple and quick, highly operable, effectively improves the voltage qualification rate of low-voltage lines, and is conducive to promoting the integration of distributed photovoltaic (PV) systems into voltage lines, thus promoting the development of distributed PV. Attached Figure Description

[0042] Figure 1 This is a flowchart of the unbalanced voltage compensation method at the end of a low-voltage distribution line based on CT-free operation, provided in Embodiment 1 of the present invention. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0044] Example 1:

[0045] This embodiment provides a method for compensating unbalanced voltage at the end of a low-voltage distribution line without a current transformer (CT). A comprehensive regulating device, including an AC / DC energy storage conversion module and a smart reactor, is installed at the end of the voltage line to regulate the three-phase unbalanced voltage. The specific regulating method includes:

[0046] 1) The voltage amplitude of the three phases at the end of the line is obtained through the integrated adjustment equipment. In this embodiment, the voltage amplitude of the three phases of the line is measured by the voltage transformer (PT). It is not necessary to obtain the current amplitude of the three phases, that is, it is not necessary to install a CT device.

[0047] 2) Calculate the average value of the three-phase voltage amplitude, and compare the voltage amplitude of each phase with the average value of the three-phase voltage amplitude to obtain the voltage deviation value of each phase;

[0048] 3) Based on the voltage deviation of each phase, the active power compensation value of each phase is generated by the PI algorithm, and the active power compensation of each phase is executed by the AC / DC energy storage conversion module.

[0049] 4) Calculate the deviation between the average three-phase voltage and the reference voltage of the voltage line, generate the three-phase reactive power compensation value through the PI algorithm, and perform three-phase reactive power compensation through the AC / DC energy storage conversion module and intelligent reactor.

[0050] The execution device of the above scheme is a comprehensive adjustment device, which has the following characteristics:

[0051] The integrated regulation equipment includes an AC / DC energy storage conversion module and intelligent reactors. The AC / DC energy storage conversion module can perform bidirectional regulation of active and reactive power in three phases with decoupled operation; the intelligent reactors can absorb inductive reactive power in three phases. The integrated regulation equipment is typically installed at the end of low-voltage lines to regulate three-phase active and reactive power, thereby achieving three-phase unbalanced voltage regulation.

[0052] The integrated regulation equipment needs to measure the voltage amplitude of the three phases of the low-voltage line, but does not need to measure the current amplitude of the three phases, thus eliminating the need to install a CT device, making it easier to install and deploy on site.

[0053] The calculation method for the average amplitude of three-phase voltages involves the following steps:

[0054]

[0055] in, The average value of the three-phase voltage amplitude, V A V B V C These are the voltage amplitudes for phases A, B, and C, respectively.

[0056] By comparing the voltage of each phase with the average value of the three-phase voltage By comparison, the deviation values ​​of each phase voltage are obtained, and the specific formula is as follows:

[0057]

[0058]

[0059]

[0060] Where, ΔV A ΔV B ΔV C These are the voltage deviation values ​​for each phase.

[0061] The calculation method for active power compensation values ​​in each phase is characterized by:

[0062] Based on the obtained voltage deviation values ​​of each phase, the active power compensation values ​​of each phase are generated through the PI algorithm.

[0063] ΔP A =p1·ΔV A

[0064] ΔP B =p1·ΔV B

[0065] ΔP C =p1·ΔV C

[0066] Where, ΔP A ΔP B ΔP C These are the compensation values ​​for the three-phase active power, and p1 is the parameter of the PI algorithm, which is generally extracted and set according to the actual situation such as line parameters and load conditions.

[0067] After calculating the active power compensation value of the three phases, the AC / DC energy storage conversion module can be used to compensate the three-phase power, realize the adjustment of active power between the three phases, and thus adjust the three-phase unbalanced voltage.

[0068] The method for calculating the deviation between the average three-phase voltage and the reference voltage of the voltage line is characterized by:

[0069]

[0070] Where ΔV set It is the three-phase average voltage With reference voltage V set The deviation value. If ΔV set A positive value indicates that the terminal voltage is too high and needs to be reduced; if ΔV set A negative value indicates that the terminal voltage is too low and needs to be boosted.

[0071] The calculation method for three-phase reactive power compensation values ​​is characterized by:

[0072] After obtaining the three-phase average voltage With reference voltage V set Deviation value ΔV set Based on this, the active power compensation values ​​for each phase are generated using the PI algorithm:

[0073] ΔQ set =p2·ΔV set

[0074] Where, ΔQ set p1 is the three-phase reactive power compensation value, and p2 is the parameter of the PI algorithm, which is generally extracted and set according to the actual situation such as line parameters and load conditions.

[0075] After calculating the three-phase reactive power compensation value, the AC / DC energy storage conversion module and intelligent reactor can be used to compensate for the three-phase reactive power, thereby increasing or decreasing the terminal voltage.

[0076] Example 2:

[0077] The unbalanced voltage compensation system at the end of a low-voltage distribution line without a current transformer (CT) can realize the unbalanced voltage compensation method at the end of a low-voltage distribution line without a CT as described in Example 1, including:

[0078] Voltage amplitude acquisition module: used to acquire the voltage amplitude of the three phases at the end of the line;

[0079] Deviation calculation module: used to calculate the average value of the three-phase voltage amplitude, and compare the voltage amplitude of each phase with the average value of the three-phase voltage amplitude to obtain the voltage deviation value of each phase;

[0080] Active power compensation module: It is used to generate active power compensation values ​​for each phase based on the voltage deviation values ​​of each phase through the PI algorithm, and then perform active power compensation for each phase through the AC / DC energy storage conversion module.

[0081] Reactive power compensation module: It is used to calculate the deviation between the average three-phase voltage and the reference voltage of the voltage line, generate three-phase reactive power compensation value through PI algorithm, and perform three-phase reactive power compensation through AC / DC energy storage conversion module and intelligent reactor.

[0082] Example 3:

[0083] This invention also provides a CT-free low-voltage distribution line end unbalanced voltage compensation device, which can realize the CT-free low-voltage distribution line end unbalanced voltage compensation method described in Embodiment 1, including a processor and a storage medium;

[0084] The storage medium is used to store instructions;

[0085] The processor is configured to operate according to the instructions to perform the steps of the following method:

[0086] Obtain the voltage amplitude of the three phases at the end of the line;

[0087] Calculate the average value of the three-phase voltage amplitude, and compare the voltage amplitude of each phase with the average value of the three-phase voltage amplitude to obtain the voltage deviation value of each phase;

[0088] Based on the voltage deviation of each phase, the active power compensation value of each phase is generated by the PI algorithm, and then the active power compensation of each phase is performed by the AC / DC energy storage conversion module.

[0089] The deviation between the average three-phase voltage and the reference voltage of the voltage line is calculated. The three-phase reactive power compensation value is generated by the PI algorithm, and the three-phase reactive power compensation is performed by the AC / DC energy storage conversion module and the intelligent reactor.

[0090] Example 4:

[0091] This invention also provides a computer-readable storage medium that can implement the unbalanced voltage compensation method at the end of a low-voltage distribution line without current transformers (CTs) as described in Embodiment 1. The medium stores a computer program that, when executed by a processor, performs the steps of the following method:

[0092] Obtain the voltage amplitude of the three phases at the end of the line;

[0093] Calculate the average value of the three-phase voltage amplitude, and compare the voltage amplitude of each phase with the average value of the three-phase voltage amplitude to obtain the voltage deviation value of each phase;

[0094] Based on the voltage deviation of each phase, the active power compensation value of each phase is generated by the PI algorithm, and then the active power compensation of each phase is performed by the AC / DC energy storage conversion module.

[0095] The deviation between the average three-phase voltage and the reference voltage of the voltage line is calculated. The three-phase reactive power compensation value is generated by the PI algorithm, and the three-phase reactive power compensation is performed by the AC / DC energy storage conversion module and the intelligent reactor.

[0096] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0097] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0098] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0099] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0100] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for compensating unbalanced voltage at the end of a low-voltage distribution line without current transformers (CTs), characterized in that... Performed by a comprehensive regulating device installed at the end of the voltage line, the comprehensive regulating device does not need to obtain the current amplitude of the three phases, including: Obtain the voltage amplitude of the three phases at the end of the line; Calculate the average value of the three-phase voltage amplitude, and compare the voltage amplitude of each phase with the average value of the three-phase voltage amplitude to obtain the voltage deviation value of each phase; The formula for calculating the average amplitude of the three-phase voltage is as follows: ， in, This is the average value of the three-phase voltage amplitude. , , These are the voltage amplitudes of phases A, B, and C, respectively. The specific formula for obtaining the voltage deviation values ​​of each phase is as follows: ， ， ， in, , , These are the voltage deviation values ​​for each phase; Based on the voltage deviation of each phase, the active power compensation value of each phase is generated by the PI algorithm, and then the active power compensation of each phase is performed by the AC / DC energy storage conversion module. The calculation formula for the active power compensation value of each phase is as follows: ， ， ， in, , , These are the compensation values ​​for the three-phase active power, These are the parameters for the PI algorithm; The deviation between the average three-phase voltage and the reference voltage of the voltage line is calculated. The three-phase reactive power compensation value is generated by the PI algorithm, and the three-phase reactive power compensation is performed by the AC / DC energy storage conversion module and the intelligent reactor. The deviation between the average three-phase voltage and the reference voltage of the voltage line is calculated using the following formula: ， in, This represents the deviation between the average value of the three-phase average voltage and the reference voltage of the voltage line. This is the reference voltage for the voltage line; The formula for calculating the three-phase reactive power compensation value is as follows: ， in, This is the three-phase reactive power compensation value. These are the parameters for the PI algorithm.

2. The method for compensating unbalanced voltage at the end of a low-voltage distribution line without a current transformer (CT) according to claim 1, characterized in that, The integrated regulation equipment includes an AC / DC energy storage conversion module and a smart reactor. The AC / DC energy storage conversion module is capable of bidirectional regulation of active and reactive power in three phases with decoupled configuration, and the smart reactor is capable of absorbing inductive reactive power in three phases.

3. A CT-free unbalanced voltage compensation system for the end of a low-voltage distribution line based on the method described in claim 1, characterized in that, include: Voltage amplitude acquisition module: used to acquire the voltage amplitude of the three phases at the end of the line; Deviation calculation module: used to calculate the average value of the three-phase voltage amplitude, and compare the voltage amplitude of each phase with the average value of the three-phase voltage amplitude to obtain the voltage deviation value of each phase; Active power compensation module: It is used to generate active power compensation values ​​for each phase based on the voltage deviation values ​​of each phase through the PI algorithm, and then perform active power compensation for each phase through the AC / DC energy storage conversion module. Reactive power compensation module: It is used to calculate the deviation between the average three-phase voltage and the reference voltage of the voltage line, generate three-phase reactive power compensation value through PI algorithm, and perform three-phase reactive power compensation through AC / DC energy storage conversion module and intelligent reactor.

4. A voltage imbalance compensation device for the end of a low-voltage distribution line without a current transformer (CT), characterized in that, Including processor and storage media; The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1 to 2.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method according to any one of claims 1 to 2.

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