A method for frequency support collaborative control of a unit group in a shaguo barren new energy base

Abstract

The application discloses a kind of unit group frequency support collaborative control methods of Shaoguo barren new energy base, it is related to frequency control technical field, for solving the problem of power injection fluctuation increase in new energy base frequency support process, by calling geographic coordinate distribution data of the unit to be detected, assesses geographic gradient characteristics, generates unit grading start timing in combination with grid-connected point frequency real-time value, reads communication round trip delay, dynamically plans trigger time, obtains grading trigger time table, issues frequency support instruction according to time table, detects power transmission of collection line and calculates power rising rate, determines wavefront propagation smoothness, collects grid-connected point three-phase voltage unbalance degree, whether to execute correction to unit grading start timing is judged according to wavefront propagation smoothness and three-phase voltage unbalance degree, update unit grading start timing after executing correction, realize the smooth wavefront propagation injection of base overall output.

Description

Technical Field

[0001] This invention relates to the field of frequency control technology, and more specifically, to a method for frequency support and coordinated control of a generator group at the Shagohuang New Energy Base. Background Technology

[0002] With the large-scale construction of new energy bases, large-scale centralized energy bases composed of multiple new energy generating units have been formed in desert, Gobi, and arid regions. Because these bases typically cover a wide area, have a large number of generating units, and a wide spatial distribution, multiple units within the base need to work together to support the frequency when the power grid experiences frequency disturbances, in order to quickly improve the frequency stability at the grid connection point. Current frequency support methods for new energy bases usually involve synchronously adjusting multiple generating units according to unified control commands, responding to changes in the power grid frequency by adjusting the active power output of the units.

[0003] The existing technology has the following shortcomings: Currently, the existing frequency support method based on unified command synchronous triggering is difficult to match the actual response characteristics of each unit. It is easy to cause the output adjustment process of multiple units to overlap in time and space, resulting in local sudden changes in the power change process of the collection line. This leads to increased power injection fluctuations, unstable grid connection voltage status, and reduced overall coordinated regulation capability during the frequency support process of the new energy base. Therefore, a coordinated control method for unit group frequency support of the Shagohuang new energy base is proposed.

[0004] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] To overcome the aforementioned deficiencies in the prior art, embodiments of the present invention provide a unit group frequency support collaborative control method for the Shagohuang New Energy Base. This method addresses the problems mentioned in the background art by employing a hierarchical startup strategy based on unit spatial gradient perception, a trigger timing optimization method that integrates communication response differences, and an adaptive correction control method that combines power propagation characteristics and voltage state feedback.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for coordinated frequency support control of a generator group at the Shagohuang New Energy Base, comprising the following steps: Step S1: Retrieve the geographic coordinate distribution data of each unit to be inspected, evaluate the geographic gradient distribution characteristics of the units to be inspected based on the geographic coordinate distribution data, collect the real-time frequency values ​​of the grid connection points, and generate the unit-level start-up sequence in combination with the geographic gradient distribution characteristics. Step S2: Read the communication round-trip delay of the unit under test, integrate the unit's hierarchical start-up sequence with the communication round-trip delay to perform dynamic programming on the trigger time of the unit under test, and obtain the hierarchical trigger time table of the unit under test after performing dynamic programming; Step S3: Issue frequency support commands to the units under test according to the graded triggering timetable. When issuing frequency support commands, detect the power transmission volume of the collection line and calculate the power rise rate. Determine the wavefront propagation smoothness of the collection line through the power rise rate. Step S4: Collect the three-phase voltage imbalance at the grid connection point, and determine whether to correct the unit-level startup sequence by combining the wavefront propagation smoothness and the three-phase voltage imbalance. After correction, update the unit-level startup sequence.

[0007] In a preferred embodiment, in step S1, the latitude and longitude coordinates of each unit to be inspected are read, and the latitude and longitude coordinates of each unit to be inspected are combined into geographic coordinate distribution data. Convert the latitude and longitude coordinates to a Cartesian coordinate system to obtain the Cartesian coordinates of the unit under test; Project the plane rectangular coordinates of each unit under inspection onto the dominant direction, which is either east-west or north-south. Identify the spatial span of each unit under inspection along the dominant direction and the average geographical interval between units to obtain the geographical gradient distribution characteristics. The distance between the projected coordinates of the farthest unit under inspection along the dominant direction and the projected coordinates of the nearest unit under inspection along the dominant direction is taken as the spatial span; the average geographical interval between units is the spatial span divided by the number of intervals between units under inspection.

[0008] In a preferred embodiment, in step S1, the frequency deviation is obtained by subtracting the real-time frequency value from the rated frequency and taking the absolute value. When the frequency deviation exceeds the preset frequency deviation threshold, the wavefront propagation mechanism is activated. Conversely, the wavefront propagation mechanism is not activated; When the wavefront propagation mechanism is activated, the units to be inspected are sorted from upstream to downstream according to their geographical location, and the sorting direction is along the dominant direction from the end closest to the booster station to the end furthest from the booster station. The unit-level start-up sequence includes the reference trigger time of each unit under test and the reference trigger interval between adjacent units; The reference trigger interval is calculated based on the frequency deviation and the average geographical interval between units, and the reference trigger time of each unit under inspection is obtained through the reference trigger interval.

[0009] In a preferred embodiment, in step S2, a test frame is sent to each unit controller under test, and each unit controller under test immediately returns a response frame after receiving the test frame, and the time when the test frame is sent and the time when the response frame is received are recorded. The round-trip time is obtained by subtracting the time of receiving the response frame from the time of sending the test frame.

[0010] In a preferred embodiment, in step S2, the reference trigger time of each unit under test is read from the unit-level startup sequence, and dynamic programming is performed on the trigger time of each unit under test in combination with the communication round-trip delay: Divide the round-trip communication delay by 2 to obtain the one-way transmission delay. Use the one-way transmission delay as a lead time to compensate for the reference trigger time and calculate the actual command transmission time of each unit under inspection. Arrange the actual command sending times of each unit to be inspected in order of unit number to generate a graded triggering time table.

[0011] In a preferred embodiment, in step S3, frequency support commands are sequentially sent to each unit under test according to the actual command sending time of the unit under test in the hierarchical triggering timetable. During the issuance of frequency support commands, the power transmission volume of each collection line power transmitter is continuously collected, and the power transmission volume of each collection line is differentiated over time to calculate the power rise rate.

[0012] In a preferred embodiment, in step S3, the maximum value of the power rise rate of each collection line is identified over the entire sampling period, and the maximum value is recorded as the power rise peak of the collection line. The sampling period begins when the first unit under test receives the frequency support command and ends when all units under test complete the output adjustment. Calculate the standard deviation of the power rise rate of each collection line to obtain the time series standard deviation; The peak power rise and timing standard deviation of each collection line are used as inputs to calculate the wavefront propagation smoothness.

[0013] In a preferred embodiment, in step S4, the instantaneous value of the three-phase voltage at the grid connection point is collected, and the effective value of the instantaneous value of the three-phase voltage is calculated to obtain the effective value of the three-phase voltage. The positive and negative sequence components of the three-phase voltage are calculated based on the effective value of the three-phase voltage using the symmetrical component method. The amplitude ratio of the negative sequence component to the positive sequence component is used as the three-phase voltage unbalance.

[0014] In a preferred embodiment, in step S4, the wavefront propagation smoothness is compared with a preset smoothness threshold, and the three-phase voltage imbalance is compared with a preset imbalance threshold. When the wavefront propagation smoothness is greater than the preset smoothness threshold or the three-phase voltage imbalance is greater than the preset imbalance threshold, a correction is performed: the current reference trigger interval is read from the unit's phased start-up sequence, and the reference trigger interval is multiplied by a relaxation factor to obtain the corrected reference trigger interval. When the wavefront propagation smoothness is not greater than the preset smoothness threshold and the three-phase voltage imbalance is not greater than the preset imbalance threshold, it is determined to perform correction: multiply the reference trigger interval by the tightening coefficient to obtain the corrected reference trigger interval. Otherwise, it is determined that no correction will be performed; The corrected reference trigger interval is written into the unit-level startup timing sequence, and the reference trigger time of each unit under test is recalculated to obtain the corrected unit-level startup timing sequence.

[0015] The technical effects and advantages of this invention are as follows: This invention retrieves the geographical coordinate distribution data of the generator under test, assesses the geographical gradient distribution characteristics based on the geographical coordinate distribution data, collects the real-time frequency value of the grid connection point, generates a tiered startup sequence for the generator unit based on the geographical gradient distribution characteristics, reads the communication round-trip delay of the generator unit under test, integrates the tiered startup sequence of the generator unit with the communication round-trip delay to perform dynamic programming on the triggering time, obtains a tiered triggering timetable, issues frequency support commands to the generator unit under test according to the tiered triggering timetable, detects the power transmission volume of the collection line and calculates the power rise rate, determines the wavefront propagation smoothness of the collection line through the power rise rate, collects the three-phase voltage imbalance of the grid connection point, and determines whether to modify the tiered startup sequence of the generator unit by combining the wavefront propagation smoothness and the three-phase voltage imbalance. After modification, the tiered startup sequence of the generator unit is updated, realizing smooth wavefront propagation injection of the base's overall output, and improving the engineering reliability of the base's participation in grid frequency regulation. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the implementation of a unit group frequency support and coordinated control method for the Shagohuang New Energy Base according to the present invention.

[0017] Figure 2 This is a schematic diagram illustrating the steps of a unit group frequency support and coordinated control method for a new energy base in Shagohuang, according to the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This invention retrieves the geographical coordinate distribution data of the unit under test, evaluates the geographical gradient distribution characteristics based on the geographical coordinate distribution data, collects the real-time frequency value of the grid connection point, generates a unit-level startup sequence based on the geographical gradient distribution characteristics, reads the communication round-trip delay of the unit under test, integrates the unit-level startup sequence and communication round-trip delay to perform dynamic programming on the triggering time, obtains a graded triggering timetable, issues frequency support commands to the unit under test according to the graded triggering timetable, detects the power transmission volume of the collection line and calculates the power rise rate, determines the wavefront propagation smoothness of the collection line through the power rise rate, collects the three-phase voltage imbalance of the grid connection point, and determines whether to modify the unit-level startup sequence based on the wavefront propagation smoothness and the three-phase voltage imbalance. After modification, the unit-level startup sequence is updated to achieve smooth wavefront propagation injection of the overall power output of the base.

[0020] Example 1, as Figures 1 to 2 As shown, a method for coordinated frequency support control of a generator group at the Shagohuang New Energy Base includes the following steps: Step S1: Retrieve the geographic coordinate distribution data of each unit to be inspected, evaluate the geographic gradient distribution characteristics of the units to be inspected based on the geographic coordinate distribution data, collect the real-time frequency values ​​of the grid connection points, and generate the unit-level start-up sequence in combination with the geographic gradient distribution characteristics. Step S2: Read the communication round-trip delay of the unit under test, integrate the unit's hierarchical start-up sequence with the communication round-trip delay to perform dynamic programming on the trigger time of the unit under test, and obtain the hierarchical trigger time table of the unit under test after performing dynamic programming; Step S3: Issue frequency support commands to the units under test according to the graded triggering timetable. When issuing frequency support commands, detect the power transmission volume of the collection line and calculate the power rise rate. Determine the wavefront propagation smoothness of the collection line through the power rise rate. Step S4: Collect the three-phase voltage imbalance at the grid connection point, and determine whether to correct the unit-level startup sequence by combining the wavefront propagation smoothness and the three-phase voltage imbalance. After correction, update the unit-level startup sequence.

[0021] The specific implementation is as follows: In step S1, the unit location query interface of the geographic information system is accessed through the data bus to read the latitude and longitude coordinates of each unit to be inspected, and the latitude and longitude coordinates of each unit to be inspected are combined into geographic coordinate distribution data.

[0022] A Geographic Information System (GIS) is a system that stores the spatial location information of all units at the Shagohuang New Energy Base, including the geographic coordinates of energy storage units, wind turbines, and photovoltaic units. Latitude and longitude coordinates are expressed in degrees.

[0023] The latitude and longitude coordinates are converted into a plane rectangular coordinate system to obtain the plane rectangular coordinates of the unit under test. The conversion adopts the Gauss-Kruger projection method, which is suitable for coordinate projection of large-span areas. The projection error does not exceed 10 meters at the scale of the Shagohuang base.

[0024] The plane rectangular coordinates of each unit under inspection are projected onto the dominant direction, which is either east-west or north-south. The spatial span of each unit under inspection along the dominant direction and the average geographical interval between units are identified to obtain the geographical gradient distribution characteristics.

[0025] The spatial span is the distance between the farthest unit under inspection and the nearest unit under inspection in the dominant direction. That is, the distance between the projected coordinates of the farthest unit under inspection along the dominant direction and the projected coordinates of the nearest unit under inspection along the dominant direction is used as the spatial span. The larger the spatial span, the more dispersed the units under inspection are.

[0026] The average geographical spacing between units is the spatial span divided by the number of units to be inspected. The average geographical spacing between units reflects the average distribution density of the units to be inspected along the dominant direction; the larger the average geographical spacing, the sparser the distribution of the units to be inspected.

[0027] Calculate the coordinate span of each unit under inspection in the east-west and north-south directions. When the east-west span is greater than the north-south span, the dominant direction is east-west; when the north-south span is greater than the east-west span, the dominant direction is north-south.

[0028] Access the frequency monitoring device at the booster station and grid connection point to collect real-time frequency values.

[0029] The frequency monitoring device at the substation grid connection point uses phase-locked loop technology to measure the grid frequency with a measurement accuracy of ±0.01Hz and a sampling frequency of 100Hz. The real-time frequency value is based on a rated reference of 50Hz, and the degree of deviation from the rated reference reflects the fluctuation state of the grid frequency.

[0030] The frequency deviation is obtained by subtracting the real-time frequency from the rated frequency and taking the absolute value. The larger the frequency deviation, the more severe the deviation of the power grid frequency from the rated value, and the more urgent the need for frequency support.

[0031] The frequency deviation is compared with the preset frequency deviation threshold to determine whether to activate the wavefront propagation mechanism. When the frequency deviation exceeds the preset frequency deviation threshold, it indicates that the power grid frequency is seriously deviated and frequency support needs to be activated, and the wavefront propagation mechanism needs to be initiated. When the frequency deviation is less than or equal to the preset frequency deviation threshold, the power grid frequency is within the normal range and the wavefront propagation mechanism is not activated.

[0032] The preset frequency deviation threshold is set according to the grid dispatch requirements. This threshold is determined based on grid stability constraints. In this embodiment, the preset frequency deviation threshold is 0.2Hz.

[0033] When the wavefront propagation mechanism is activated, the units to be inspected are sorted from upstream to downstream according to their geographical location, with the sorting direction following the dominant direction from the end closest to the booster station to the end furthest from the booster station. The units to be inspected are numbered 1, 2, ..., N, with unit number 1 located closest to the booster station and unit number N located furthest from the booster station.

[0034] By combining geographical gradient distribution characteristics and frequency deviation, a tiered startup sequence for each unit is generated. The tiered startup sequence includes the reference trigger time for each unit under inspection and the reference trigger interval between adjacent units.

[0035] The baseline trigger interval is calculated based on the frequency deviation and the average geographical interval between units: ,in, The reference trigger interval is k, where k is the timing coefficient. This is the frequency deviation. This represents the average geographical interval between generating units.

[0036] The timing coefficient is set based on the matching relationship between geographical span and frequency response speed. A larger frequency deviation requires a faster response and a shorter trigger interval; conversely, a larger geographical span necessitates a reduction in the timing coefficient to avoid excessively long total response time. In this embodiment, the geographical span of the Shagohuang base is 50km, and the timing coefficient is set to 0.02. .

[0037] The reference trigger times for each unit under inspection increase sequentially according to its number, and the calculation formula is as follows: ,in, Let i be the reference trigger time corresponding to the i-th unit, where i is the unit number and its value ranges from 1 to N.

[0038] The reference trigger time corresponding to the unit under inspection numbered 1 is 0, indicating that it is triggered first. The reference trigger times of subsequent units are sequentially increased by the reference trigger interval, forming a wavefront propagation timing sequence from upstream to downstream.

[0039] The unit-level startup sequence is stored in tabular form, with columns including unit number, geographic coordinates, and reference trigger time.

[0040] The tiered startup sequence of the generating units is used to avoid excessive instantaneous power surges caused by all the units under test responding to frequency support commands at the same time, which could lead to sudden changes in the current of the collection line or three-phase voltage imbalance. By staggering the triggering times of each unit under test from upstream to downstream according to its geographical location, the overall output of the base is injected into the grid in a smooth wavefront propagation pattern, which reduces the impact of instantaneous power injection on grid stability while meeting the grid frequency support response speed requirements.

[0041] In step S2, test frames are sent to the controllers of each unit under test through the communication network management module. The frame length of the test frame is 64 bytes, and the frame length value is based on the minimum frame length standard of Ethernet.

[0042] Upon receiving the test frame, each controller of the unit under test immediately returns a response frame. The response frames have the same frame length to maintain measurement symmetry. The system receives the response frames returned by each controller and records the time of test frame transmission and response frame reception.

[0043] The round-trip time (RTT) is obtained by subtracting the time the response frame is received from the time the test frame is sent. The larger the RTT, the higher the transmission delay of the unit's communication link.

[0044] The reference trigger time of each unit under test is read from the unit-level startup sequence. The reference trigger time reflects the time sequence supported by the response frequency of each unit under ideal conditions. Dynamic programming is performed on the trigger time of each unit under test in combination with the communication round-trip delay.

[0045] The dynamic programming adopts a feedforward compensation strategy. The reason for choosing this strategy is that the Shagohuang New Energy Base covers an area of ​​hundreds of square kilometers, the geographical locations of the units to be tested are highly dispersed, and the difference in communication link length between near-end units and remote units can be tens of kilometers, resulting in a difference in communication round-trip delay of hundreds of milliseconds.

[0046] The feedforward compensation strategy predicts the communication delay of each unit and adjusts the triggering time in advance before the command is sent, ensuring that the actual response time of all units meets the wavefront propagation requirements of the reference triggering time after deducting their respective communication delays.

[0047] Dividing the round-trip communication delay by 2 yields the one-way transmission delay, which reflects the time required for the command to be transmitted to the controller of the unit under test.

[0048] Using the one-way transmission delay as a lead time to compensate for the baseline trigger time, the actual command transmission time of each unit under inspection is calculated: ,in, The actual time the instruction was sent. This refers to the reference trigger time corresponding to the i-th unit, read from the unit-level startup timing sequence. For communication round-trip delay, This refers to the one-way transmission delay.

[0049] The greater the round-trip time delay, the longer the one-way transmission delay, the earlier the actual command is sent, and the greater the deviation between the actual command sending time and the reference trigger time. By sending commands in advance, the communication link transmission delay is compensated for, ensuring that the time when the command arrives at the controller of the unit under test is aligned with the reference trigger time.

[0050] Arrange the actual command sending times of each unit to be inspected in order of unit number to generate a graded triggering time table.

[0051] The tiered triggering timetable is stored in tabular form. The table columns include unit number, baseline triggering time, communication round-trip time, and actual command transmission time. The tiered triggering timetable records the sequence of actual command transmission times for each unit under inspection, providing a timing basis for the accurate issuance of subsequent frequency support commands.

[0052] It should be noted that the transmission of test frames and the reception of response frames are performed before the frequency support response is initiated. This measurement process is triggered immediately after the grid connection point frequency deviates from the rated value. The measurement result of communication round-trip delay remains valid within one control cycle, with a control cycle length of 10 seconds. This value is derived from the statistical characteristics of the communication network status at the Shagohuang base: within 10 seconds, the communication link topology and load status are basically stable, and the fluctuation of communication round-trip delay does not exceed 5% of the measured value.

[0053] In step S3, according to the graded triggering timetable, frequency support instructions are sequentially issued to each unit under inspection; at each actual instruction sending time, a frequency support instruction is sent to the controller of the unit under inspection with the corresponding unit number. The frequency support instruction includes two fields: target output increment and response time window.

[0054] After receiving the command, the controller of each unit under test analyzes the target output increment and controls the corresponding unit under test to increase its output by adjusting the converter output power. The response time window is used to constrain the time limit for the unit to complete the output adjustment. This time limit is set differently according to the unit type. For example, the response time window of the energy storage unit is 200ms, the response time window of the wind turbine unit is 2s, and the response time window of the photovoltaic unit is dynamically adjusted according to the current irradiance.

[0055] During the command issuance period, the power transmission volume of each collection line power transmitter is continuously collected. The collection lines of the Shagohuang New Energy Base adopt a hierarchical collection topology, with each collection line connecting several units under test. The collection line power transmitters are installed on the low-voltage side of the step-up transformer of the collection line to measure the real-time power on the collection line.

[0056] The sampling interval for power transmission is set to 100ms. This value is chosen because: a sampling interval that is too large will result in the loss of power fluctuation details, while a sampling interval that is too small will result in increased sampling noise interference. A sampling interval of 100ms can balance the requirements for fluctuation capture accuracy and noise suppression. Power transmission data is read from the power transmitters of each collection line through a real-time data acquisition interface and stored as time-series data.

[0057] The power rise rate is calculated by differentiating the power transmission of each collection line over time. The power rise rate reflects how quickly the power transmission of the collection line changes, and it is calculated using the finite difference method. ,in, Let j be the power rise rate, j be the collection line number, and t be the time. To collect the power transmission amount of line j at time t, To gather line j at time Power transmission amount, The sampling interval is 0.1s.

[0058] The faster the power transfer increases, the greater the increase in power transfer per unit time, and the greater the rate of power increase.

[0059] The maximum power rise rate of each aggregation line is identified throughout the entire sampling period, and this maximum value is recorded as the peak power rise of that aggregation line. The sampling period begins when the first unit under test receives the frequency support command and ends when all units under test complete their output adjustment. The higher the peak power rise, the faster the power transmission of the aggregation line increases at a given moment, indicating that multiple units are responding simultaneously or that a single unit's response amplitude is too large at that moment.

[0060] Calculate the standard deviation corresponding to the power rise rate of each collection line to obtain the time series standard deviation, which represents the degree of fluctuation of the power rise rate on the time axis.

[0061] The larger the time series standard deviation, the greater the deviation of the power rise rate from the average value at different times, and the more drastic the fluctuation of the power rise rate. The smaller the time series standard deviation, the more uniform the power rise rate is distributed on the time axis, and the smoother the fluctuation.

[0062] Using the peak value and time series standard deviation of each collection line as input, the wavefront propagation smoothness is calculated: Where S is the wavefront propagation smoothness, and These are the weighting coefficients. This means averaging over all convergence lines. To collect the peak power rise of line j, Let be the time series standard deviation of line j.

[0063] The weighting coefficients are set based on the following: the peak power rise reflects the peak impact of power rise, while the time series standard deviation reflects the continuous fluctuation of power rise. The two have different mechanisms of impact on the quality of grid frequency support. An excessively high peak power rise can cause sudden changes in the current of the collecting line, triggering protection actions. An excessively large time series standard deviation can cause the power injection to exhibit a sawtooth pattern, affecting frequency stability.

[0064] Through regression analysis of historical operational data from the Shagohuang base, the peak value influence weight was set to 0.6, and the time series standard deviation influence weight was set to 0.4, i.e., α was set to 0.6 and β to 0.4. The smaller the wavefront propagation smoothness, the smoother the power rise; the larger the wavefront propagation smoothness, the more likely there is a step or oscillation in the power transmission of the collection line.

[0065] Wavefront propagation smoothness reflects the gradual degree of power input from the base into the power grid.

[0066] In step S4, the voltage transformer at the step-up substation grid connection point is accessed to collect the instantaneous values ​​of the three-phase voltage.

[0067] The voltage transformer at the substation grid connection point is installed on the 10kV bus, with a sampling frequency of 10kHz and a voltage measurement accuracy of ±0.2%.

[0068] The effective values ​​of the three-phase voltages are obtained by calculating the effective values ​​of the instantaneous three-phase voltages. These correspond to the effective voltage values ​​of phases A, B, and C, respectively.

[0069] The positive and negative sequence components of three-phase voltage are calculated using the symmetrical component method. The symmetrical component method decomposes the unbalanced three-phase voltage into positive sequence, negative sequence, and zero sequence components. The positive sequence component reflects the degree of balance of the three-phase voltage, while the negative sequence component reflects the degree of imbalance of the three-phase voltage.

[0070] The formula for calculating the negative-order component is: The formula for calculating the positive sequence component is: ;in, This represents the negative sequence component of the three-phase voltage. Let be the positive sequence component of the three-phase voltage, and 'a' be a complex operator. , indicating a phase rotation of 120 degrees.

[0071] The ratio of the magnitudes of the negative-sequence component to the positive-sequence component is used as the three-phase voltage unbalance, and its calculation formula is as follows: ,in, This represents the three-phase voltage imbalance, expressed as a percentage.

[0072] The greater the three-phase voltage imbalance, the more severe the deviation of the three-phase voltage from the symmetrical state. The generating units at the Shagohuang New Energy Base are scattered, and each unit is connected to the booster station through different collection lines. If multiple units respond to frequency support simultaneously in a short period of time, the uneven power injection into each phase will lead to three-phase voltage asymmetry.

[0073] Compare the wavefront propagation smoothness with a preset smoothness threshold, and compare the three-phase voltage imbalance with a preset imbalance threshold: When the wavefront propagation smoothness is greater than the preset smoothness threshold or the three-phase voltage imbalance is greater than the preset imbalance threshold, a correction is determined to be performed.

[0074] Read the current reference trigger interval from the unit-level startup timing sequence. The corrected reference trigger interval is obtained by multiplying the reference trigger interval by the relaxation factor.

[0075] The relaxation factor is set based on the degree of exceedance of wavefront propagation smoothness and three-phase voltage imbalance. The higher the degree of exceedance, the larger the trigger interval needs to be, and the larger the relaxation factor value should be. In this embodiment, the relaxation factor is set to 1.2. When the wavefront propagation smoothness is not greater than the preset smoothness threshold and the three-phase voltage imbalance is not greater than the preset imbalance threshold, it is determined that the wavefront propagation is smooth and the three-phase voltage is balanced. Correction is then performed. The current trigger interval setting is reasonable and has margin space. The trigger interval can be tightened to improve the response speed. The correction method is to multiply the reference trigger interval by the tightening coefficient to obtain the corrected reference trigger interval. The tightening factor is set based on the margin space of wavefront propagation smoothness and three-phase voltage imbalance. The larger the margin, the greater the space that the trigger interval can be reduced, and the smaller the value of the tightening factor.

[0076] In this embodiment, the tightening coefficient is set to 0.9. This value ensures that the trigger interval after tightening will not be too small, which would cause the wavefront propagation smoothness or three-phase voltage imbalance to exceed the standard during the next frequency support response. Tightening the trigger interval can shorten the total response time, accelerate the overall frequency support response speed of the base station, and improve the timeliness of response to grid frequency fluctuations.

[0077] It should be added that the preset smoothness threshold is set according to the grid access standard. This threshold reflects the grid side's requirements for power injection smoothness. In this embodiment, it is set to 15MW / s (if the power transmission volume is in MW) or 15000kW / s (if the power transmission volume is in kW). The preset imbalance threshold is set according to the national standard GB / T 15543-2025 "Power Quality Three-Phase Voltage Imbalance". This standard stipulates that the three-phase voltage imbalance should not exceed 2% when the power system's point of common coupling is operating normally. In this embodiment, it is set to 2%.

[0078] After the correction is performed, the corrected reference trigger interval is written into the unit-level startup sequence, and the reference trigger time of each unit under inspection is recalculated.

[0079] The revised formula for calculating the baseline trigger time is as follows: in, The corrected reference trigger time, where i is the unit number. This is the corrected baseline time interval.

[0080] The corrected unit-level startup sequence is stored in the local database for use in the next frequency support response. The corrected unit-level startup sequence will be invoked when the frequency deviation is detected to be greater than the preset frequency deviation threshold, serving as the input parameter for dynamic programming in step S2.

[0081] It should be noted that the correction of the unit-level startup timing adopts an incremental update strategy. Each correction only adjusts the baseline trigger interval without recalculating the geographic gradient distribution characteristics and timing coefficients. This strategy can maintain the stability of the correction and avoid introducing GIS data reading delays during the correction process. If the wavefront propagation smoothness and three-phase voltage imbalance continue to exceed the standard after three consecutive frequency support responses, the process returns to step S1 to re-execute the geographic gradient distribution characteristic identification and unit-level startup timing generation, eliminating timing mismatches caused by GIS data updates or unit topology changes.

[0082] Finally, it should be noted that in this paper, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0083] Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0084] In this document, the singular forms “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that terms such as “comprising / including” or “having” specify the presence of the stated features, integrals, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, integrals, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0085] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0086] The above description of the disclosed embodiments will enable those skilled in the art to make or use various modifications to these embodiments. It will be readily apparent to those skilled in the art that the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for coordinated control of frequency support of a unit group in a Shaguo Huang new energy base, characterized in that: Includes the following steps: Step S1: Retrieve the geographic coordinate distribution data of each unit to be inspected, evaluate the geographic gradient distribution characteristics of the units to be inspected based on the geographic coordinate distribution data, collect the real-time frequency values ​​of the grid connection points, and generate the unit-level start-up sequence in combination with the geographic gradient distribution characteristics. Step S2: Read the communication round-trip delay of the unit under test, integrate the unit's hierarchical start-up sequence with the communication round-trip delay to perform dynamic programming on the trigger time of the unit under test, and obtain the hierarchical trigger time table of the unit under test after performing dynamic programming; Step S3: Issue frequency support commands to the units under test according to the graded triggering timetable. When issuing frequency support commands, detect the power transmission volume of the collection line and calculate the power rise rate. Determine the wavefront propagation smoothness of the collection line through the power rise rate. Step S4: Collect the three-phase voltage imbalance at the grid connection point, and determine whether to correct the unit-level startup sequence by combining the wavefront propagation smoothness and the three-phase voltage imbalance. After correction, update the unit-level startup sequence.

2. The method for frequency support and coordinated control of a generator group in a desert renewable energy base according to claim 1, characterized in that: In step S1, the latitude and longitude coordinates of each unit under inspection are read, and the latitude and longitude coordinates of each unit under inspection are combined into geographical coordinate distribution data. Convert the latitude and longitude coordinates to a Cartesian coordinate system to obtain the Cartesian coordinates of the unit under test; Project the plane rectangular coordinates of each unit under inspection onto the dominant direction, which is either east-west or north-south. Identify the spatial span of each unit under inspection along the dominant direction and the average geographical interval between units to obtain the geographical gradient distribution characteristics. The distance between the projected coordinates of the farthest unit under inspection along the dominant direction and the projected coordinates of the nearest unit under inspection along the dominant direction is taken as the spatial span; the average geographical interval between units is the spatial span divided by the number of intervals between units under inspection.

3. The method for frequency support and coordinated control of a generator group in a desert renewable energy base according to claim 2, characterized in that: In step S1, the frequency deviation is obtained by subtracting the real-time frequency from the rated frequency and taking the absolute value. When the frequency deviation exceeds the preset frequency deviation threshold, the wavefront propagation mechanism is activated. Conversely, the wavefront propagation mechanism is not activated; When the wavefront propagation mechanism is activated, the units to be inspected are sorted from upstream to downstream according to their geographical location, and the sorting direction is along the dominant direction from the end closest to the booster station to the end furthest from the booster station. The unit-level start-up sequence includes the reference trigger time of each unit under test and the reference trigger interval between adjacent units; The reference trigger interval is calculated based on the frequency deviation and the average geographical interval between units, and the reference trigger time of each unit under inspection is obtained through the reference trigger interval.

4. The method for frequency support and coordinated control of a generator group in a desert renewable energy base according to claim 1, characterized in that: In step S2, a test frame is sent to the controller of each unit under test. After receiving the test frame, each controller of the unit under test immediately returns a response frame. The time when the test frame is sent and the time when the response frame is received are recorded. The round-trip time is obtained by subtracting the time of receiving the response frame from the time of sending the test frame.

5. The method for frequency support and coordinated control of a generator group in a desert renewable energy base according to claim 4, characterized in that: In step S2, the reference trigger time of each unit under test is read from the unit-level startup sequence, and dynamic programming is performed on the trigger time of each unit under test in combination with the communication round-trip delay: Divide the round-trip communication delay by 2 to obtain the one-way transmission delay. Use the one-way transmission delay as a lead time to compensate for the reference trigger time and calculate the actual command transmission time of each unit under inspection. Arrange the actual command sending times of each unit to be inspected in order of unit number to generate a graded triggering time table.

6. The method for frequency support and coordinated control of a generator group in a desert renewable energy base according to claim 1, characterized in that: In step S3, frequency support commands are sequentially sent to each unit under test according to the actual command sending time of the unit under test in the graded triggering time table. During the issuance of frequency support commands, the power transmission volume of each collection line power transmitter is continuously collected, and the power transmission volume of each collection line is differentiated over time to calculate the power rise rate.

7. The method for frequency support and coordinated control of a generator group in a desert renewable energy base according to claim 6, characterized in that: In step S3, the maximum value of the power rise rate of each collection line is identified during the entire sampling period, and the maximum value is recorded as the power rise peak of the collection line. The sampling period begins when the first unit under test receives the frequency support command and ends when all units under test complete the output adjustment. Calculate the standard deviation of the power rise rate of each collection line to obtain the time series standard deviation; The peak power rise and timing standard deviation of each collection line are used as inputs to calculate the wavefront propagation smoothness.

8. The method for frequency support and coordinated control of a generator group in a desert renewable energy base according to claim 7, characterized in that: In step S4, the instantaneous values ​​of the three-phase voltage at the grid connection point are collected, and the effective values ​​of the three-phase voltage are calculated to obtain the effective values ​​of the three-phase voltage. The positive and negative sequence components of the three-phase voltage are calculated based on the effective value of the three-phase voltage using the symmetrical component method. The amplitude ratio of the negative sequence component to the positive sequence component is used as the three-phase voltage unbalance.

9. The method for frequency support and coordinated control of a generator group in a desert renewable energy base according to claim 1, characterized in that: In step S4, the wavefront propagation smoothness is compared with a preset smoothness threshold, and the three-phase voltage imbalance is compared with a preset imbalance threshold. When the wavefront propagation smoothness is greater than the preset smoothness threshold or the three-phase voltage imbalance is greater than the preset imbalance threshold, a correction is performed: the current reference trigger interval is read from the unit's phased start-up sequence, and the reference trigger interval is multiplied by a relaxation factor to obtain the corrected reference trigger interval. When the wavefront propagation smoothness is not greater than the preset smoothness threshold and the three-phase voltage imbalance is not greater than the preset imbalance threshold, it is determined to perform correction: multiply the reference trigger interval by the tightening coefficient to obtain the corrected reference trigger interval. Otherwise, it is determined that no correction will be performed; The corrected reference trigger interval is written into the unit-level startup timing sequence, and the reference trigger time of each unit under test is recalculated to obtain the corrected unit-level startup timing sequence.

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