Optical storage charging station grid-connected three-phase imbalance OLTC split-phase adjustment method

Abstract

The invention relates to the technical field of intelligent scheduling and optimization analysis, in particular to an optical storage and charging station grid-connected three-phase imbalance OLTC split-phase adjustment method, which comprises the following steps of: performing real-time high-frequency acquisition on an optical storage and charging integrated power station to obtain real-time voltage of each phase in a three-phase system; carrying out data processing on the real-time operation data to obtain an abnormal quantity of a three-phase system of the optical storage and charging integrated power station; data analysis is carried out on the abnormal quantity of the three-phase system and the real-time voltage of each phase, and an OLTC split-phase adjustment mechanism is determined; and performing effect evaluation on the OLTC split-phase adjustment mechanism, and determining an optimization strategy of the OLTC split-phase adjustment mechanism. According to the invention, through a split-phase OLTC independent adjustment mechanism, single-phase voltage deviation compensation is realized, and the three-phase unbalance degree is suppressed. Through split-phase independent adjustment, the system can accurately compensate single-phase voltage deviation, the problem of insufficient compensation accuracy caused by a traditional three-phase overall adjustment strategy is avoided, and efficient and reliable technical support is provided for the three-phase imbalance problem of a novel power system.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent scheduling and optimization analysis, and specifically relates to a method for phase-separated regulation of OLTC for three-phase imbalance in grid-connected photovoltaic energy storage charging stations. Background Art

[0002] The current technical solutions for solving three-phase imbalance problems in the distribution network mainly include reactive power compensation devices, traditional three-phase integral regulation of OLTC, load balancing devices, and distributed power generation control strategies. Among them, reactive power compensation devices dynamically inject or absorb reactive current through power electronic devices, quickly adjust reactive power to compensate for voltage deviation, and are widely used in scenarios with large fluctuations in industrial loads.

[0003] In the prior art, for the demand of three-phase imbalance control after the integration of photovoltaic energy storage charging stations into the distribution network, the traditional technical solutions have the following defects:

[0004] 1. Insufficient dynamic response speed, unable to meet the requirements of high volatility scenarios: Reactive power compensation devices rely on power electronic devices for regulation. However, when the fast charging power of electric vehicles changes instantaneously or the photovoltaic output fluctuates on a second-by-second basis, there is a lag of 10 - 100 ms in the injection of reactive current, resulting in a decrease in the voltage fluctuation suppression effect.

[0005] 2. Lack of phase-separated independent regulation ability, exacerbating local imbalance problems: Traditional OLTC and load balancing devices only support the overall voltage boost, reduction, or load phase sequence switching of three phases. When single-phase charging piles are concentratedly connected or there are significant differences in the photovoltaic output between phases, they are unable to perform differential compensation on specific phases, resulting in the local three-phase imbalance degree exceeding the national standard limit. Summary of the Invention

[0006] The purpose of the present invention is to address the problems in the background art and propose a method for phase-separated regulation of OLTC for three-phase imbalance in grid-connected photovoltaic energy storage charging stations.

[0007] The technical solution of the present invention: A method for phase-separated regulation of OLTC for three-phase imbalance in grid-connected photovoltaic energy storage charging stations includes the following steps:

[0008] Perform real-time high-frequency acquisition on the integrated photovoltaic energy storage charging station to obtain the real-time voltage of each phase in the three-phase system;

[0009] Perform data processing on the real-time operation data to obtain the abnormal quantities of the three-phase system of the integrated photovoltaic energy storage charging station;

[0010] Perform data analysis on the abnormal quantities of the three-phase system and the real-time voltage of each phase respectively to determine the OLTC phase-separated regulation mechanism;

[0011] Evaluate the effect of the OLTC phase-separated regulation mechanism to determine the optimization strategy of the OLTC phase-separated regulation mechanism.

[0012] Preferably, the method for processing real-time operation data includes:

[0013] Analyze the real-time voltage by the symmetrical component method to determine the three-phase voltage unbalance degree, specifically including:

[0014] Obtain the three-phase voltages and label them respectively as , and ;

[0015] Solve for the effective values of the components using the transformation matrix, and the transformation matrix is as follows:

[0016] ;

[0017] In the formula, is the zero-sequence component; is the positive-sequence component; is the negative-sequence component; where , j represents the imaginary unit;

[0018] Perform magnitude operations on the zero-sequence component , the positive-sequence component and the negative-sequence component to obtain the effective values of the zero-sequence component , the positive-sequence component and the negative-sequence component respectively;

[0019] Calculate the negative-sequence unbalance degree F through the following formula and use it as the three-phase unbalance degree:

[0020] .

[0021] Preferably, the method for processing real-time operation data further includes:

[0022] Perform Fourier transform on each phase voltage, decompose the fundamental wave and each harmonic component, and calculate the single-phase distortion rate through the following single-phase distortion formula:

[0023] ;

[0024] In the formula, is the effective value of the fundamental wave voltage; is the effective value of the nth harmonic voltage, n is the sequence element number, n is a positive integer, n = [2,..., N], and N is the preset highest harmonic order; the classical value of the highest harmonic order N is 50;

[0025] Calculate the distortion rates of the three phases through the single-phase distortion formula to obtain , and respectively;

[0026] Determine the total distortion rate of the system, which is achieved through the following formula:

[0027] ;

[0028] In the formula, D1 is the first total distortion rate determined based on the maximum value method; D2 is the second total distortion rate determined based on the average value method;

[0029] Generally, the following formula is used to determine the abnormal amount Y of the three-phase system;

[0030] ;

[0031] In the formula, , and are weight coefficients.

[0032] Preferably, data analysis is performed on the abnormal amount of the three-phase system and the real-time voltage of each phase respectively, including the following methods:

[0033] Compare the data of the abnormal amount Y with the risk threshold. If the abnormal amount Y is less than the risk threshold, it is determined that the three-phase system is normal; if the abnormal amount Y is not less than the risk threshold, it is determined that the three-phase system is abnormal and a first abnormal label is generated;

[0034] Independently analyze the real-time phase voltage of each phase to determine whether the real-time phase voltage belongs to the preset rated range of the phase voltage; if the real-time phase voltage belongs to the rated range of the phase voltage, it is determined that the phase voltage is normal; if the real-time phase voltage does not belong to the rated range of the phase voltage, it is determined that the phase voltage is abnormal and a second abnormal label is generated.

[0035] Preferably, according to any abnormal label, OLTC phase-by-phase regulation is performed on the single-phase joint, including:

[0036] If the phase voltage is lower than the minimum value of the rated voltage range, control the tap of this phase to switch to the high-voltage gear; if the voltage is greater than the maximum value of the rated voltage range, switch to the low-voltage gear.

[0037] Preferably, according to the abnormal label, the regulation of the single-phase joint also includes:

[0038] Obtain the median value of the rated range of the phase voltage and use it as the standard value of the phase voltage. Calculate the phase voltage offset value through the following formula

[0039] ;

[0040] In the formula, is the real-time phase voltage, i ∈ (A, B, C); is the standard value of the phase voltage; is the rated range of the phase voltage;

[0041] Sort the phase voltage offset values P of the three-phase real-time voltage in descending order to obtain a priority sequence, and preferentially regulate the corresponding phase tap changer according to the sorting order of the priority sequence.

[0042] Preferably, evaluate the effect of the OLTC phase-splitting regulation mechanism. The method includes:

[0043] Evaluate the OLTC phase-splitting regulation mechanism under a single load fluctuation:

[0044] During a sudden change period, regulate the load on this phase according to a preset load change amount, obtain the phase voltage after the load sudden change and mark it as the starting voltage , obtain the phase voltage change value of this phase, and calculate the required regulated voltage based on the following formula : The preset load change amount makes the phase voltage offset value >0;

[0045] ;

[0046] In the formula, is the standard radius of the phase voltage; based on calculating the difference between the maximum value of the rated range of the phase voltage and the standard value of the phase voltage ;

[0047] Obtain the phase voltage on this phase during the standard regulation period after OLTC phase-splitting regulation and mark it as the ending voltage ;

[0048] Calculate the single-phase evaluation value of the OLTC phase-splitting regulation mechanism of a single phase through the following formula :

[0049] .

[0050] Preferably, based on the OLTC phase-splitting regulation mechanism under multiple load fluctuations, calculate the single-phase evaluation values of the OLTC phase-splitting regulation mechanisms of each phase according to the above formula 、 and ;

[0051] Evaluate the OLTC phase-splitting regulation mechanism under multiple load fluctuations through the following formula to obtain the three-phase evaluation value :

[0052] .

[0053] Preferably, the optimization strategy of the OLTC phase-splitting regulation mechanism is:

[0054] The three-phase evaluation value Compare with a preset evaluation threshold. If the three-phase evaluation value is not less than the evaluation threshold, there is no need to optimize the OLTC phase-separated regulation mechanism; if the three-phase evaluation value is less than the evaluation threshold, it is necessary to optimize the OLTC phase-separated regulation mechanism.

[0055] Compared with the prior art, the above technical solution of the present invention has the following beneficial technical effects:

[0056] (1) The present invention proposes a phase-separated independent regulation architecture, using an OLTC transformer with a phase-separated independent winding design. Each phase tap is equipped with an independent drive motor and an electronic switch, supporting independent adjustment of the single-phase tap position. Specifically, when the voltage of a certain phase is lower than the lower limit of the rated value, control the tap of this phase to switch to the high-voltage gear; when the voltage of a certain phase is higher than the upper limit, switch to the low-voltage gear. This phase-separated independent regulation architecture can accurately compensate for single-phase voltage deviation, avoid the problem of insufficient compensation accuracy caused by the traditional three-phase overall regulation strategy, and significantly improve the effect of three-phase unbalance governance.

[0057] (2) The present invention proposes a dynamic priority arbitration mechanism. Based on the real-time sorting of the voltage deviation amplitude, it preferentially adjusts the phase with the largest voltage deviation. At the same time, through mechanical interlock design, it avoids the risk of transient overvoltage caused by the simultaneous operation of the three-phase taps. This dynamic priority arbitration mechanism not only improves the regulation efficiency but also ensures the safety and stability of the regulation process, and is especially suitable for scenarios where single-phase charging piles are centrally connected or the inter-phase differences in photovoltaic power generation are significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 is a method block diagram proposed by the present invention;

[0059] Figure 2 is the overall flow chart proposed by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0060] As Figure 1 and Figure 2 shown, the OLTC phase-separated regulation method for grid-connected three-phase unbalance in a photovoltaic-storage charging station proposed by the present invention includes the following steps:

[0061] Perform real-time high-frequency acquisition on the photovoltaic-storage charging integrated station to obtain the real-time voltage of each phase in the three-phase system;

[0062] Perform data processing on the real-time operation data to obtain the abnormal quantity of the three-phase system of the photovoltaic-storage charging integrated station;

[0063] The method for performing data processing on the real-time operation data includes:

[0064] Analyze the real-time voltage by the symmetrical component method to determine the three-phase voltage unbalance degree, specifically including:

[0065] Obtain the three-phase voltages and label them respectively as 、 and ;

[0066] Solve for the effective values of the components using the transformation matrix. The transformation matrix is as follows:

[0067] ;

[0068] In the formula, is the zero-sequence component; is the positive-sequence component; is the negative-sequence component; where, , j represents the imaginary unit;

[0069] Perform magnitude operations on the zero-sequence component , the positive-sequence component and the negative-sequence component to obtain the effective values of the zero-sequence component , the positive-sequence component and the negative-sequence component ;

[0070] Calculate the negative-sequence unbalance degree F through the following formula and use it as the three-phase unbalance degree:

[0071] ;

[0072] Perform Fourier transform on each phase voltage to decompose the fundamental wave and each harmonic component, and calculate the single-phase distortion rate through the following single-phase distortion formula:

[0073] ;

[0074] In the formula, is the effective value of the fundamental wave voltage; is the effective value of the nth harmonic voltage, n is the sequence element number, n is a positive integer, n = [2,..., N], and N is the preset highest harmonic order;

[0075] Calculate the distortion rates of the three phases through the single-phase distortion formula to obtain 、 and ;

[0076] Determine the total distortion rate of the system through the following formula:

[0077] ;

[0078] Wherein, D1 is the first total distortion rate determined based on the maximum value method; D2 is the second total distortion rate determined based on the average value method;

[0079] The abnormal quantity Y of the three-phase system is determined by the following general formula;

[0080] ;

[0081] Wherein, , and are weighting coefficients;

[0082] Data analysis is respectively carried out on the abnormal quantity of the three-phase system and the real-time voltage of each phase to determine the OLTC phase-separated regulation mechanism;

[0083] Data analysis is respectively carried out on the abnormal quantity of the three-phase system and the real-time voltage of each phase, including the following methods:

[0084] The data of the abnormal quantity Y is compared with the risk threshold. If the abnormal quantity Y is less than the risk threshold, it is determined that the three-phase system is normal; if the abnormal quantity Y is not less than the risk threshold, it is determined that the three-phase system is abnormal and a first abnormal label is generated;

[0085] Independent analysis is carried out on the real-time phase voltage of each phase to determine whether the real-time phase voltage belongs to the preset rated range of the phase voltage; if the real-time phase voltage belongs to the rated range of the phase voltage, it is determined that the phase voltage is normal; if the real-time phase voltage does not belong to the rated range of the phase voltage, it is determined that the phase voltage is abnormal and a second abnormal label is generated;

[0086] According to any abnormal label, OLTC phase-separated regulation is carried out on the single-phase joint, including:

[0087] If the phase voltage is lower than the minimum value of the voltage rated range, control the tap of this phase to switch to the high voltage gear; if the voltage is greater than the maximum value of the voltage rated range, switch to the low voltage gear;

[0088] According to the abnormal label, the regulation of the single-phase joint also includes:

[0089] Obtain the median value of the rated range of the phase voltage and use it as the standard value of the phase voltage. Calculate the phase voltage offset value through the following formula

[0090] ;

[0091] Wherein, is the real-time phase voltage, i ∈ (A, B, C); is the standard value of the phase voltage; is the rated range of the phase voltage;

[0092] Sort the phase voltage offset values P of the three-phase real-time voltage in descending order to obtain a priority sequence, and preferentially regulate the corresponding phase tap changers according to the sorting order of the priority sequence;

[0093] Evaluate the effect of the OLTC phase-splitting regulation mechanism to determine the optimization strategy of the OLTC phase-splitting regulation mechanism;

[0094] Evaluate the effect of the OLTC phase-splitting regulation mechanism. The methods include:

[0095] Evaluate the OLTC phase-splitting regulation mechanism under a single load fluctuation:

[0096] During a sudden change period, regulate the load on this phase according to the preset load change amount, obtain the phase voltage after the load sudden change and mark it as the starting voltage , obtain the phase voltage change value of this phase, and calculate the required regulated voltage based on the following formula : The preset load change amount makes the phase voltage offset value >0;

[0097] ;

[0098] In the formula, is the standard radius of the phase voltage; based on the difference calculation between the maximum value of the rated range of the phase voltage and the standard value of the phase voltage ;

[0099] Obtain the phase voltage on this phase during the standard regulation period after OLTC phase-splitting regulation and mark it as the ending voltage ; It should be noted that the standard regulation period is calibrated based on big data testing, which indicates the average action time of the OLTC phase-splitting regulation mechanism;

[0100] Calculate the single-phase evaluation value of the single-phase OLTC phase-splitting regulation mechanism through the following formula :

[0101] ;

[0102] Based on the OLTC phase-splitting regulation mechanism under multiple load fluctuations, calculate the single-phase evaluation values of the OLTC phase-splitting regulation mechanisms of each phase according to the above formula 、 and ;

[0103] Evaluate the OLTC phase-splitting regulation mechanism under multiple load fluctuations through the following formula to obtain the three-phase evaluation value :

[0104] ;

[0105] The optimization strategy for the OLTC phase - splitting regulation mechanism is as follows:

[0106] Compare the three - phase evaluation value with a preset evaluation threshold. If the three - phase evaluation value is not less than the evaluation threshold, there is no need to optimize the OLTC phase - splitting regulation mechanism; if the three - phase evaluation value is less than the evaluation threshold, it is necessary to optimize the OLTC phase - splitting regulation mechanism.

[0107] The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited thereto. Within the scope of knowledge possessed by those skilled in the art to which it pertains, various changes can be made without departing from the gist of the present invention.

Claims

1. An OLTC phase-splitting adjustment method for three-phase unbalance of a photovoltaic charging station connected to the grid, characterized in that: The following steps are involved: Carry out real-time high-frequency data collection for the integrated photovoltaic storage and charging power station to obtain the real-time voltage of each phase in the three-phase system; Process the real-time operation data to obtain the abnormal quantity of the three-phase system of the photovoltaic storage and charging integrated power station; Analyze the abnormal quantity of the three-phase system and the real-time voltage of each phase to determine the OLTC phase regulation mechanism; Evaluate the effect of OLTC phase regulation mechanism and determine the optimization strategy of OLTC phase regulation mechanism.

2. The OLTC phase-splitting adjustment method for three-phase imbalance of the photovoltaic storage charging station grid-connected according to claim 1 is characterized in that: Methods for processing real-time operation data include: The real-time voltage is analyzed by the symmetrical component method to determine the three-phase voltage imbalance, including: Get the three-phase voltages and mark them as , and ; The transformation matrix is ​​used to solve the effective value of the component. The transformation matrix is ​​as follows: ； In the formula, is the zero-sequence component; is the positive sequence component; is the negative sequence component; among them, , j represents the imaginary unit; For zero sequence component , positive sequence component and negative sequence component Perform modulus length calculation to obtain the effective value of the zero-sequence component , positive sequence component and negative sequence component ; The negative sequence unbalance F is calculated by the following formula and used as the three-phase unbalance: 。 3. The OLTC phase-splitting adjustment method for three-phase imbalance of the photovoltaic storage charging station grid-connected according to claim 2 is characterized in that: The method for processing the real-time operation data also includes: Perform Fourier transform on each phase voltage to decompose the fundamental wave and each harmonic component, and calculate the single-phase distortion rate using the following single-phase distortion formula: ； In the formula, is the effective value of the fundamental voltage; is the effective value of the nth harmonic voltage, n is the sequence element number, n is a positive integer, n=[2, ..., N], N is the preset highest harmonic order; The three-phase distortion rate is calculated by the single-phase distortion formula, and the following are obtained: , and ; Determine the total distortion rate of the system, which is achieved through the following formula: ； Wherein, D1 is the first total distortion rate determined based on the maximum value method; D2 is the second total distortion rate determined based on the average value method; The following formula is generally used to determine the abnormal quantity Y of the three-phase system; ； In the formula, , and is the weight coefficient.

4. The OLTC phase-splitting adjustment method for three-phase imbalance of the photovoltaic energy storage charging station grid-connected according to claim 3 is characterized in that: The abnormal quantity of the three-phase system and the real-time voltage of each phase are analyzed separately, including the following methods: Compare the abnormal quantity Y with the risk threshold. If the abnormal quantity Y is less than the risk threshold, the three-phase system is considered normal. If the abnormal amount Y is not less than the risk threshold, the three-phase system is determined to be abnormal and a first abnormal label is generated; The real-time phase voltage of each phase is analyzed independently to determine whether the real-time phase voltage belongs to the preset phase voltage rated range; if the real-time phase voltage belongs to the phase voltage rated range, the phase voltage is determined to be normal; If the real-time phase voltage does not belong to the phase voltage rated range, the phase voltage is determined to be abnormal and a second abnormality tag is generated.

5. The OLTC phase-splitting adjustment method for three-phase imbalance of the photovoltaic energy storage charging station grid-connected according to claim 4 is characterized in that: Perform OLTC phase adjustment on the single-phase joint according to any abnormal tag, including: If the phase voltage is lower than the minimum value of the voltage rated range, the phase tap is controlled to switch to the high voltage position; if the voltage is greater than the maximum value of the voltage rated range, it is switched to the low voltage position.

6. The OLTC phase-splitting adjustment method for three-phase imbalance of the photovoltaic storage charging station grid-connected according to claim 5 is characterized in that: Adjust the single-phase joint according to the abnormal label, including: Get the median value of the phase voltage rated range and use it as the standard value of the phase voltage. Calculate the phase voltage offset value using the following formula ; In the formula, is the real-time phase voltage, i∈(A, B, C); is the standard value of phase voltage; is the rated range of phase voltage; The phase voltage offset values ​​P of the three-phase real-time voltage are sorted in descending order to obtain a priority sequence, and the corresponding phase taps are preferentially regulated according to the sorting order of the priority sequence.

7. The OLTC phase-splitting adjustment method for three-phase imbalance of the photovoltaic energy storage charging station grid-connected according to claim 6 is characterized in that: The effectiveness of the OLTC phase regulation mechanism is evaluated by: Evaluation of OLTC phase regulation mechanism under single load fluctuation: During a sudden change period, the load on the phase is regulated according to the preset load change amount, and the phase voltage after the load sudden change is obtained and marked as the starting voltage , obtain the phase voltage change value of the phase, and calculate the required regulation voltage based on the following formula :Preset load change makes the phase voltage offset value >0; ； In the formula, is the standard radius of phase voltage; based on the rated range of phase voltage The maximum value and phase voltage standard value The difference is calculated; Obtain the phase voltage on the phase during the standard regulation period after OLTC phase regulation and mark it as the end voltage ; The single-phase evaluation value of the single-phase OLTC phase regulation mechanism is calculated by the following formula: : 。 8. The OLTC phase-splitting adjustment method for three-phase imbalance of the photovoltaic energy storage charging station grid-connected according to claim 7 is characterized in that: Under the OLTC phase regulation mechanism based on multiple load fluctuations, the single-phase evaluation value of each phase OLTC phase regulation mechanism is calculated according to the above formula , and ; The OLTC phase regulation mechanism under multiple load fluctuations is evaluated by the following formula to obtain the three-phase evaluation value : 。 9. The OLTC phase-splitting adjustment method for three-phase imbalance of the photovoltaic energy storage charging station grid-connected according to claim 8 is characterized in that: The optimization strategy of OLTC phase regulation mechanism is: The three-phase evaluation value Compare with the preset evaluation threshold. If the three-phase evaluation value is not less than the evaluation threshold, there is no need to optimize the OLTC phase regulation mechanism; if the three-phase evaluation value If it is less than the evaluation threshold, the OLTC phase regulation mechanism needs to be optimized.

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