A transformer area energy storage multi-scenario adaptive operation control method

Abstract

The application discloses a kind of table area energy storage multi-scenario adaptive operation control method, belong to table area energy storage operation control technical field.This method responds table area power grid real-time operation data, extracts voltage fluctuation sequence and load switching timing, determines voltage weak period and load mutation node;When meeting the intervention trigger condition of energy storage, voltage weak period is used as time reference to generate power compensation slope curve, and the starting slope is corrected according to the load mutation node, to obtain the output control curve of energy storage;The cumulative discharge depth in voltage weak period is calculated and the termination amplitude is adjusted to obtain the final energy storage action curve, and the energy storage equipment is controlled to output power according to the curve.The method considers the timing characteristics of load mutation node and voltage weak period, and introduces cumulative discharge depth constraint, to improve the adaptability and discharge safety of table area energy storage multi-scenario operation.

Description

Technical Field

[0001] This invention relates to the field of transformer substation energy storage operation control technology, specifically a multi-scenario adaptive operation control method for transformer substation energy storage. Background Technology

[0002] In the operation of the distribution network, energy storage devices are used for voltage support and power fluctuation mitigation. Common control methods for distribution network energy storage mainly rely on voltage over-limit information or preset time periods for charge-discharge switching. When the distribution network voltage is detected to be lower than the set lower limit, the energy storage device starts active power output; when the voltage recovers to the allowable range, the energy storage device shuts down or reduces output according to a fixed curve. Some methods adjust the energy storage output based on load connection or disconnection events to mitigate short-term power surges caused by load switching. The above methods can achieve basic power compensation under a single voltage anomaly or a single load switching scenario. In actual distribution network operation, voltage weakness and load switching behavior do not occur independently. Voltage weakness periods and load abrupt change nodes may coincide on the time axis or may be offset from each other. Control curves generated based on voltage over-limit information usually adopt a fixed slope or symmetrical shape, failing to utilize the sequential relationship between the connection and disconnection times in the load switching sequence and the voltage weakness period to adjust the initial rate of change of power compensation. When a load change occurs before or after a period of voltage weakness, a power compensation ramp curve with a fixed initial slope is difficult to match the actual power surge timing. This can easily lead to insufficient or excessive compensation in the early stages of a period of voltage weakness, affecting the voltage stability control effect.

[0003] After generating and correcting the power compensation curve, existing methods rarely constrain the curve termination amplitude by incorporating the cumulative discharge depth of the energy storage device during periods of voltage weakness. During continuous operation across multiple scenarios or over extended periods, the energy storage device may over-discharge due to the cumulative discharge exceeding the allowable range, impacting the operational safety and lifespan of the energy storage system. Existing control methods struggle to adapt to operating scenarios where voltage weakness periods overlap or misalign with load abrupt changes on the time axis, making it difficult to simultaneously limit the cumulative discharge of the energy storage device during power compensation. Summary of the Invention

[0004] To address the shortcomings of existing transformer substation energy storage operation control methods, which fail to adequately integrate load switching timing and voltage-weak periods and lack cumulative discharge depth constraints, this invention provides a multi-scenario adaptive operation control method for transformer substation energy storage. By extracting voltage fluctuation sequences and load switching timing from real-time operation data, voltage-weak periods and load abrupt change nodes are identified. When the energy storage intervention triggering conditions are met, a power compensation ramp curve is generated. The initial slope is corrected based on the load abrupt change node, and the termination amplitude is adjusted based on the cumulative discharge depth to obtain the final energy storage action curve. The power output of the energy storage device is controlled according to the final energy storage action curve, making the energy storage output process adaptable to the multi-scenario operation status of the transformer substation.

[0005] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides a multi-scenario adaptive operation control method for energy storage in a distribution area, comprising: responding to real-time operation data of the distribution area power grid, extracting voltage fluctuation sequence and load switching sequence from the real-time operation data; determining the voltage weak period of the distribution area power grid based on the voltage fluctuation sequence, and determining the load mutation node of the distribution area power grid based on the load switching sequence; when the voltage weak period and the load mutation node meet preset energy storage intervention triggering conditions, generating a power compensation slope curve of the energy storage device with the voltage weak period as a time reference; correcting the initial slope of the power compensation slope curve based on the load mutation node to obtain an energy storage output control curve; calculating the cumulative discharge depth of the energy storage device during the voltage weak period using the energy storage output control curve as a constraint, and adjusting the termination amplitude of the energy storage output control curve based on the cumulative discharge depth to obtain a final energy storage action curve; and controlling the energy storage device to output power according to the final energy storage action curve. This control method integrates voltage fluctuation characteristics and load switching characteristics into the generation and correction process of energy storage output curves, enabling energy storage to adaptively adjust its power response process under different operating scenarios in different transformer areas. While improving voltage levels during periods of voltage weakness, it also constrains the depth of energy storage discharge, reducing the risk of over-discharge of energy storage devices.

[0006] Preferably, when extracting the voltage fluctuation sequence and load switching sequence from the real-time operating data, the instantaneous values ​​of multi-phase voltage within a continuous time window are extracted from the real-time operating data. These instantaneous values ​​are then decomposed into phase sequence to obtain the sequence of fundamental amplitude changes of each phase voltage over time, which serves as the voltage fluctuation sequence. The current on / off flags of each feeder port are parsed from the real-time operating data. The moment when the current on / off flag changes from closed to open is marked as the disconnection moment, and the moment when it changes from open to closed is marked as the connection moment. The disconnection moments and connection moments are arranged in chronological order to obtain the load switching sequence. This method enables the stable extraction of voltage fluctuation process and load switching time information from the real-time data of the transformer area, providing a basis for subsequent energy storage intervention judgment.

[0007] Preferably, when determining voltage-weak periods and load abrupt change points, the system identifies continuous time periods in the voltage fluctuation sequence where the voltage amplitude is below a preset voltage stability lower limit, and marks these continuous time periods as voltage-weak periods. It also identifies the time intervals between adjacent disconnection and connection times in the load switching sequence, pairs adjacent disconnection times with connection times whose time intervals are less than a preset switching interval threshold, and marks the paired disconnection and connection times together as the load abrupt change points. This allows for accurate identification of time intervals with persistently low voltage and periods of rapid load switching in the distribution network, improving the accuracy of energy storage intervention timing.

[0008] As a technical solution of the present invention, when generating the power compensation slope curve, it is determined whether there is an intersection between the voltage-weak period and the load mutation node on the time axis. If there is an intersection, it is determined that the energy storage intervention trigger condition is met. The starting time of the voltage-weak period is taken as the rising start time of the power compensation slope curve, and the ending time of the voltage-weak period is taken as the falling end time of the power compensation slope curve. A triangular slope curve is set between the rising start time and the falling end time, in which the power compensation value linearly increases from zero to a peak value and then linearly decreases back to zero, as the power compensation slope curve. By constructing a triangular slope curve with the voltage-weak period as the time reference, the energy storage output power rises and falls smoothly within the voltage-weak period, reducing the impact of power mutations on the power grid of the distribution area.

[0009] Furthermore, when correcting the initial slope of the power compensation ramp curve based on the load abrupt change node, the input time at the load abrupt change node is compared with the rising start time of the power compensation ramp curve. If the input time is earlier than the rising start time, the initial slope of the power compensation ramp curve at the rising start time is increased; if the input time is later than the rising start time, the initial slope of the power compensation ramp curve at the rising start time is decreased. Starting from the corrected initial slope, while keeping the peak value and termination time of the power compensation ramp curve unchanged, a new corrected ramp curve is generated as the energy storage output control curve. By directionally correcting the initial slope, the energy storage output can form a differentiated response based on the load change sequence before or after load input, adapting to different load switching scenarios.

[0010] Further, when calculating the cumulative discharge depth and adjusting the termination amplitude, the energy storage output control curve is integrated over time during the voltage-weak period to obtain the theoretical discharge capacity of the energy storage device during the voltage-weak period; the rated capacity of the energy storage device is obtained, and the theoretical discharge capacity is divided by the rated capacity to obtain the cumulative discharge depth; the cumulative discharge depth is compared with a preset upper limit of discharge depth. If the cumulative discharge depth is greater than the upper limit of discharge depth, the termination amplitude of the energy storage output control curve is reduced proportionally to the ratio of the upper limit of discharge depth to the cumulative discharge depth. If the cumulative discharge depth is not greater than the upper limit of discharge depth, the termination amplitude of the energy storage output control curve remains unchanged, and the adjusted curve is used as the final energy storage operation curve. Maintaining the initial slope and peak value of the energy storage output control curve while reducing the termination amplitude ensures that the energy storage device meets voltage support requirements while avoiding exceeding the allowable discharge depth, thus balancing voltage regulation effect and energy storage life.

[0011] Furthermore, when controlling the energy storage device to output power according to the final energy storage operation curve, the final energy storage operation curve is discretized into a power command sequence with equal time intervals. According to each power command value in the power command sequence, an active power setpoint is sequentially sent to the converter of the energy storage device. Simultaneously with sending each active power setpoint, the actual output power of the energy storage device is collected, and the instantaneous deviation between the actual output power and the active power setpoint is calculated. Based on the instantaneous deviation, a closed-loop correction is performed on the power command value for the next time interval, and the corrected power command value is used to control the output power of the energy storage device. This closed-loop correction improves the tracking accuracy of the energy storage converter on the final energy storage operation curve and reduces the deviation between the actual output power and the power command.

[0012] Preferably, when parsing the current on / off flag bits of each feeder port, the effective current value of each feeder port is read from the real-time operating data. Feeder ports with effective current values ​​greater than a preset conduction current threshold are determined to be in a closed state, and feeder ports with effective current values ​​less than or equal to the conduction current threshold are determined to be in an open state. The current on / off flag bit corresponding to the closed state is set as the first flag value, and the current on / off flag bit corresponding to the open state is set as the second flag value. The current on / off flag bits of each feeder port are sorted by time, and the moment when the current on / off flag bit jumps from the second flag value to the first flag value is the connection time, and the moment when the current on / off flag bit jumps from the first flag value to the second flag value is the disconnection time. Identifying load connection and disconnection by combining the effective current value and the flag bit jump can improve the accuracy of load switching timing extraction.

[0013] Furthermore, for the case where the input time is earlier than the rise-start time, increasing the initial slope, the time difference between the rise-start time and the input time is calculated, and a slope increment coefficient is determined based on the time difference. The original initial slope of the power compensation slope curve at the rise-start time is multiplied by the slope increment coefficient to obtain the increased initial slope. For the case where the input time is later than the rise-start time, decreasing the initial slope, the time difference between the input time and the rise-start time is calculated, and a slope decrement coefficient is determined based on the time difference. The original initial slope of the power compensation slope curve at the rise-start time is multiplied by the slope decrement coefficient to obtain the decreased initial slope. The initial slope is quantitatively adjusted based on the relative relationship between the load input time and the voltage weakness point, making the corrected energy storage output control curve more closely match the real-time requirements of load switching scenarios.

[0014] The technical effects and advantages provided by the present invention in the above technical solution are as follows: Voltage fluctuation sequences and load switching timing are extracted from real-time operational data. Voltage fluctuation sequences identify voltage-weak periods, and load switching timing identifies load abrupt change nodes. When there is a temporal overlap between voltage-weak periods and load abrupt change nodes, the start time of the voltage-weak period is used as the rise initiation time, and the end time as the fall end time, generating a power compensation slope curve. The initial slope of the power compensation slope curve is corrected based on the order of the load input and rise initiation times at the load abrupt change nodes: if the input time is earlier than the rise initiation time, a slope increment coefficient is determined based on the time difference, increasing the initial slope; if the input time is later than the rise initiation time, a slope decrement coefficient is determined based on the time difference, decreasing the initial slope. The corrected slope curve is then regenerated while maintaining the peak value and end time unchanged. This method introduces the timing information of load input or output behavior into the initial segment of the power compensation curve, dynamically matching the rate of change of energy storage output in the early stages of voltage-weak periods with the load abrupt change timing. Compared to power compensation methods with a fixed initial slope, methods that establish active power support quickly when the load is applied before the voltage-weak period, and reduce the initial power rise rate when the load is applied after the voltage-weak period, thus mitigating the risk of overcompensation and adapting to different timing relationships between load abrupt changes and voltage-weak periods. Based on the energy storage output control curve, the curve within the voltage-weak period is integrated over time to obtain the theoretical discharge capacity. The ratio of the theoretical discharge capacity to the rated capacity of the energy storage device is used as the cumulative discharge depth. The cumulative discharge depth is compared with a preset upper limit. When the cumulative discharge depth exceeds the upper limit, the termination amplitude of the energy storage output control curve is reduced proportionally to the ratio of the upper limit to the cumulative discharge depth, while the initial slope and peak value remain unchanged. When the cumulative discharge depth is not greater than the upper limit, the termination amplitude remains unchanged. The final energy storage operation curve obtained after adjustment is used to control the output power of the energy storage device. This method uses the cumulative discharge depth as a constraint condition for the termination amplitude of the power compensation curve, dynamically limiting the total discharge of the energy storage device during the voltage support process, avoiding excessive discharge caused by continuous multi-scenario operation or long-term voltage weakness, and taking into account the power compensation requirements and the operational safety and cycle life of the energy storage system. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0016] Figure 1 This is a flowchart of the adaptive operation control method for multi-scenario energy storage in the transformer substation. Figure 2 This is a flowchart of the method for generating energy storage output control curves; Figure 3 This is a schematic diagram showing the amplitude of the positive sequence voltage base wave, the load switching timing, and the voltage weak periods. Figure 4 This is a schematic diagram of the energy storage power compensation slope curve, output control curve, and the timing of load change nodes during periods of low voltage. Figure 5 This is a schematic curve illustrating the power output control and closed-loop correction of energy storage devices. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0018] See Figure 1 This invention provides a multi-scenario adaptive operation control method for energy storage in a distribution network, comprising: responding to real-time operation data of the distribution network, extracting voltage fluctuation sequence and load switching sequence from the real-time operation data; determining the voltage weak period of the distribution network based on the voltage fluctuation sequence, and determining the load mutation node of the distribution network based on the load switching sequence; when the voltage weak period and the load mutation node meet preset energy storage intervention triggering conditions, generating a power compensation slope curve of the energy storage device using the voltage weak period as a time reference; correcting the initial slope of the power compensation slope curve based on the load mutation node to obtain an energy storage output control curve; calculating the cumulative discharge depth of the energy storage device during the voltage weak period using the energy storage output control curve as a constraint, and adjusting the termination amplitude of the energy storage output control curve based on the cumulative discharge depth to obtain a final energy storage action curve; and controlling the energy storage device to output power according to the final energy storage action curve.

[0019] In practice, instantaneous multi-phase voltage values ​​within a continuous time window are extracted from the real-time operation data of the distribution network. The length of the continuous time window is determined based on the load variation cycle of the distribution network, and is set to 600 seconds. The instantaneous multi-phase voltage values ​​include the instantaneous voltage values ​​of phase A, phase B, and phase C. Real-time operation data is collected by the distribution network's intelligent fusion terminal, with a sampling frequency of 256 points per power frequency cycle. When performing phase sequence decomposition on the instantaneous multi-phase voltage values, an instantaneous symmetrical component transformation is used to transform the instantaneous voltage values ​​of phase A, phase B, and phase C into positive-sequence, negative-sequence, and zero-sequence voltage components, respectively. A sliding-window discrete Fourier transform is performed on the positive-sequence voltage components to extract the fundamental amplitude values. The positive-sequence fundamental amplitude values ​​corresponding to each sampling moment are arranged in chronological order to obtain the voltage fluctuation sequence.

[0020] In some embodiments, the effective current value of each feeder port is read from real-time operating data. The feeder port is the port connecting each branch line in the distribution network. Each feeder port is equipped with a current transformer, which collects the instantaneous current value of the feeder port. The distribution network's intelligent fusion terminal calculates the effective current value based on the instantaneous current value. The calculation period for the effective current value is the same as the sampling period of the continuous time window. The effective current value is compared with a preset conduction current threshold, which is set to 60% of the minimum operating current of the load connected to the feeder port. If the effective current value is greater than the conduction current threshold, the feeder port is determined to be in a closed state; if the effective current value is less than or equal to the conduction current threshold, the feeder port is determined to be in an open state. The current on / off flag corresponding to the closed state is set to a first flag value, which is 1. The current on / off flag corresponding to the open state is set to a second flag value, which is 0.

[0021] Optionally, the current on / off flag bits of each feeder port are sorted by time to form a current on / off flag bit time sequence. The moment when the current on / off flag bit in the current on / off flag bit time sequence jumps from the second flag value to the first flag value is detected and marked as the on-time. The moment when the current on / off flag bit in the current on / off flag bit time sequence jumps from the first flag value to the second flag value is detected and marked as the off-time. The off-time and on-time moments are arranged in chronological order to obtain the load switching sequence. The load switching sequence includes the off-time and on-time moments corresponding to each feeder port, and the moments in the load switching sequence are arranged in chronological order of occurrence.

[0022] In practice, the voltage fluctuation sequence is used to identify consecutive time periods where the voltage amplitude is lower than a preset lower voltage stability limit. The lower voltage stability limit is set to 90% of the rated phase voltage of the distribution network, based on the allowable voltage deviation of ±10% of the rated voltage. Each voltage amplitude in the voltage fluctuation sequence is arranged in chronological order of sampling time. Each voltage amplitude in the sequence is iterated and compared to the lower voltage stability limit. When a voltage amplitude is lower than the lower voltage stability limit, the sampling time corresponding to that amplitude is recorded as the low voltage start time; when the voltage amplitude recovers to be greater than or equal to the lower voltage stability limit, the sampling time corresponding to that amplitude is recorded as the low voltage end time. The consecutive time period between the low voltage start time and the low voltage end time is marked as a voltage-weak period. If there are multiple consecutive time periods in the voltage fluctuation sequence where the voltage amplitude is lower than the lower voltage stability limit, each of these consecutive time periods is marked as a voltage-weak period.

[0023] Optionally, a sliding window discrimination method is used when searching for continuous time periods where the voltage amplitude is lower than the voltage stability lower limit. The discrimination window length is set to 10 sampling periods. If all voltage amplitudes within a discrimination window are lower than the voltage stability lower limit, the discrimination window belongs to a voltage-weak period. Adjacent discrimination windows belonging to voltage-weak periods are merged to form a continuous time period.

[0024] In some embodiments, the time interval between adjacent cutoff and commissioning times is identified from the load switching sequence. The load switching sequence includes multiple cutoff times and multiple commissioning times, arranged in chronological order. Each element is read sequentially from the load switching sequence. When a cutoff time is read, the nearest commissioning time after the cutoff time is found, and the time difference between the cutoff time and the commissioning time is calculated. The formula for calculating the time difference is: ; in, Indicates the first The resection time and the first The time interval between each input moment, in seconds; Indicates the first Each resection moment, in seconds; Indicates the first Each input moment, in seconds; and This refers to the sequence number of adjacent cut-off and start-up times in the load switching sequence.

[0025] The time interval is compared with a preset switching interval threshold. The switching interval threshold is set to 5 seconds, based on the assumption that the duration of the voltage transient process in the transformer area caused by load switching does not exceed 5 seconds. If the time interval is less than the preset switching interval threshold, the corresponding adjacent cut-off time and commissioning time are paired, and the paired cut-off time and commissioning time are jointly marked as load mutation nodes. If the time interval is greater than or equal to the preset switching interval threshold, adjacent cut-off time and commissioning time are not paired. The above search and pairing process is performed for each cut-off time in the load switching sequence to obtain the set of load mutation nodes.

[0026] Optionally, the cut-off time and the turn-on time in a load mutation node can originate from the same feeder port or from different feeder ports. Adjacent cut-off and turn-on times from different feeder ports that are adjacent on the time axis and whose time interval is less than the switching interval threshold are considered a load mutation. A load mutation node contains two time identifiers: the cut-off time and the turn-on time.

[0027] See Figure 3 In the graph, the horizontal axis represents time in seconds, and the vertical axis represents the fundamental amplitude of the positive-sequence voltage in volts. The blue solid line curve represents the trend of the fundamental amplitude of the positive-sequence voltage over time. The black dashed line represents the lower limit of voltage stability, which is approximately 195 volts. The gray background area marks voltage-weak periods, i.e., the continuous time intervals in which the fundamental amplitude of the positive-sequence voltage is lower than the lower limit of voltage stability. The graph shows three main voltage-weak periods, located in the intervals of approximately 150–200 seconds, 350–380 seconds, and 500–530 seconds, respectively.

[0028] The green triangles mark the times when the load is switched on, the red inverted triangles mark the times when the load is switched off, and the purple pentagrams mark the load abrupt change nodes. During the voltage-weak period, the green switching on and red switching off times are relatively concentrated, and the load abrupt change nodes coincide with their time positions, reflecting the time overlap between the load switching sequence and the voltage-weak period, which is consistent with the time pairing characteristics of the load abrupt change nodes in the above embodiment.

[0029] Specifically, during the first voltage-weak period (approximately 150–200 seconds), the fundamental voltage amplitude was significantly lower than the lower voltage stability limit, and there were multiple load shedding and energizing operations. The load abrupt change point was marked at approximately 165 seconds, indicating that load switching triggered a voltage abrupt change at this point. During the second voltage-weak period (approximately 350–380 seconds), the voltage amplitude further decreased to around 180 volts, with alternating load shedding and energizing events, and the load abrupt change points were concentrated. During the third voltage-weak period (approximately 500–530 seconds), the voltage amplitude was also lower than the lower stability limit, with relatively concentrated load shedding and energizing events, and the load abrupt change points were clearly marked, indicating the impact of load abrupt changes on voltage fluctuations.

[0030] In specific implementation, please refer to Figure 2 The time ranges of voltage-weak periods and load surge nodes are obtained. The time range of a voltage-weak period consists of its start and end times. The time range of a load surge node consists of its cutoff and activation times. The method for determining whether the voltage-weak period and the load surge node intersect on the time axis is to compare the order of the start and end times of the voltage-weak period, the cutoff and activation times of the load surge node, and the activation times of the load surge node on the time axis. A voltage-weak period is a continuous time interval with a start and end time, and a load surge node is defined by its activation and cutoff times. The rule for determining whether the two time intervals intersect is: if the start time of the voltage-weak period is earlier than the end time of the corresponding time interval of the load surge node, and simultaneously, the start time of the corresponding time interval of the load surge node is earlier than the end time of the voltage-weak period, then the voltage-weak period and the load surge node intersect on the time axis. If the voltage-weak period and the load surge node intersect on the time axis, then the energy storage intervention triggering condition is met.

[0031] The above-mentioned judgment rules apply to both situations where the load surge node falls entirely within a voltage-weak period and situations where the load surge node and the voltage-weak period only partially overlap. As long as the two time intervals overlap for any period on the time axis, they are considered to have an intersection, ensuring that no cases where the load surge node and the voltage-weak period partially overlap are missed, and guaranteeing that all scenarios where energy storage intervention should be activated can be identified.

[0032] In some embodiments, the intersection of the voltage-weak period and the load surge node on the time axis can be represented by the load surge node falling within the voltage-weak period, or by the load surge node partially overlapping with the voltage-weak period. When there is an intersection, the power grid in the distribution area simultaneously experiences a load switching process during the voltage-weak period. Energy storage devices can perform power compensation during the voltage-weak period to cope with both low voltage and load surge operating scenarios.

[0033] Optionally, the start time of the voltage-weak period is used as the rising start time of the power compensation slope curve, and the end time of the voltage-weak period is used as the falling end time of the power compensation slope curve. A triangular slope curve is set between the rising start time and the falling end time, where the power compensation value linearly increases from zero to the peak value and then linearly decreases back to zero. This is used as the power compensation slope curve. The peak value of the power compensation slope curve is set to 80% of the rated power of the energy storage device. This is because the energy storage device needs to maintain a certain power margin during short-term power compensation to avoid excessively rapid temperature rise due to prolonged full-power operation. The rising duration of the power compensation slope curve is set to half the duration of the voltage-weak period, and the falling duration is set to the other half of the voltage-weak period. The original initial slope of the power compensation slope curve at the rising start time is obtained by dividing the peak value of the power compensation slope curve by the rising duration.

[0034] In practice, the connection time at the load abrupt change node is compared with the rising start time of the power compensation ramp curve. If the connection time at the load abrupt change node is earlier than the rising start time of the power compensation ramp curve, the time difference between the rising start time of the power compensation ramp curve and the connection time at the load abrupt change node is calculated, and the slope increment coefficient is determined based on the time difference. If the connection time at the load abrupt change node is later than the rising start time of the power compensation ramp curve, the time difference between the connection time at the load abrupt change node and the rising start time of the power compensation ramp curve is calculated, and the slope decrement coefficient is determined based on the time difference.

[0035] Optionally, the slope increment coefficient and slope decrement coefficient are obtained using the same slope adjustment calculation formula. The slope adjustment calculation formula is: ; in, This represents the slope adjustment coefficient, which is dimensionless. Indicates the start-up time of the power compensation ramp curve, in seconds; Indicates the moment of input in the load mutation node, in seconds; This represents the slope adjustment time constant, in seconds. The slope adjustment time constant is set to 10 seconds because the duration of voltage transients caused by load switching in the distribution network typically does not exceed 5 seconds. Setting the slope adjustment time constant to 10 seconds limits the slope adjustment coefficient to the range of 0.5 to 1.5. When the connection time at the load abrupt change node is earlier than the rising start time of the power compensation slope curve, A positive value indicates a slope adjustment coefficient greater than 1; this slope adjustment coefficient is the slope increment coefficient. When the connection time at the load abrupt change node is later than the rising start time of the power compensation ramp curve, If the value is negative, the slope adjustment coefficient is less than 1. The slope adjustment coefficient is the slope reduction coefficient. When the calculated value of the slope adjustment coefficient is less than 0.5, the slope adjustment coefficient is set to 0.5; when the calculated value of the slope adjustment coefficient is greater than 1.5, the slope adjustment coefficient is set to 1.5.

[0036] In practical implementation, if the connection time at the load abrupt change node is earlier than the rising start time of the power compensation slope curve, the original initial slope of the power compensation slope curve at the rising start time is multiplied by a slope increment coefficient to obtain an increased initial slope. The increased initial slope is greater than the original initial slope, causing the power increase rate of the power compensation slope curve at the rising start time to accelerate, allowing the energy storage device to respond to the load connection process earlier. If the connection time at the load abrupt change node is later than the rising start time of the power compensation slope curve, the original initial slope of the power compensation slope curve at the rising start time is multiplied by a slope reduction coefficient to obtain a decreased initial slope. The decreased initial slope is less than the original initial slope, causing the power increase rate of the power compensation slope curve at the rising start time to slow down, allowing the energy storage device to delay the power increase process to match the load connection time.

[0037] Optionally, starting with the corrected initial slope, the peak value and termination time of the power compensation slope curve are kept unchanged, and a new corrected slope curve is generated. The process of regenerating the corrected slope curve is as follows: at the start of the upward movement of the power compensation slope curve, the power compensation value increases linearly from zero according to the corrected initial slope; when the power compensation value reaches the peak value of the power compensation slope curve, the power compensation value remains unchanged at the peak value; before the end of the downward movement of the power compensation slope curve, the power compensation value decreases linearly from the peak value, so that the power compensation value decreases to zero exactly at the end of the downward movement of the power compensation slope curve. The regenerated corrected slope curve has the same peak value and the same end time of the downward movement as the original power compensation slope curve, but the duration of the upward movement is changed. The regenerated corrected slope curve serves as the energy storage output control curve.

[0038] See Figure 4 In the graph, the horizontal axis represents time in seconds, ranging from 0 to 600 seconds, and the vertical axis represents the active power setpoint in kilowatts. The dashed blue curve is the power compensation ramp curve, the solid red curve is the energy storage output control curve, and the green triangle marks indicate the activation time at load abrupt change nodes.

[0039] As shown in the figure, both the power compensation ramp curve and the energy storage output control curve exhibit a symmetrical triangular waveform. The power value starts to rise from 0 at approximately 150 seconds, rapidly increasing linearly to a peak of around 80 kW. After a very short peak duration, it quickly drops back to zero, ending at approximately 200 seconds. This time interval corresponds to the voltage-weak period of the power grid in the distribution area. The start and end times of the ramp curve's rise and fall correspond to the start and end times of this voltage-weak period, respectively. The peak value is set to 80% of the rated power of the energy storage device, meeting the power margin requirements of the energy storage device.

[0040] The green triangle marks the activation time at approximately 160 seconds, about 10 seconds earlier than the start of the power compensation ramp curve's ascent. The energy storage output control curve shows a slightly slower slope in the ascending phase compared to the power compensation ramp curve, indicating that the initial slope has been corrected based on the activation time at the load abrupt change node. Specifically, according to the slope adjustment calculation formula, since the activation time at the load abrupt change node is earlier than the start of the power compensation ramp curve's ascent, the slope adjustment coefficient is slightly greater than 1. This adjustment to the initial slope of the energy storage output control curve appropriately accelerates the power increase response speed to match the load activation process.

[0041] In addition, the energy storage output control curve remains smooth and continuous in both the rising segment before the peak and the falling segment after the peak, and the termination amplitude is consistent with the power compensation slope curve, indicating that the cumulative discharge depth has not exceeded the upper limit of discharge depth, and there is no need to reduce the termination amplitude.

[0042] In practical implementation, the energy storage output control curve is integrated over time during periods of voltage weakness to obtain the theoretical discharge capacity of the energy storage device during these periods. The energy storage output control curve is a power-time curve, with time on the horizontal axis and the active power setpoint of the energy storage device on the vertical axis. The time integration uses the trapezoidal numerical integration method, with the integration interval from the start to the end of the voltage weakness period. The integration step size is the same as the sampling period of the real-time operating data, set to 1 second. The theoretical discharge capacity is equal to the area enclosed by the energy storage output control curve and the time axis within the integration interval.

[0043] In some embodiments, the rated capacity of the energy storage device is obtained. The rated capacity is read from the battery management system parameters of the energy storage device, and the unit of rated capacity is kilowatt-hours. The cumulative depth of discharge is obtained by dividing the theoretical discharge capacity by the rated capacity. The formula for calculating the cumulative depth of discharge is: ; in, Indicates the cumulative depth of discharge, dimensionless; This represents the theoretical discharge capacity, expressed in kilowatt-hours. This indicates the rated capacity of the energy storage device, expressed in kilowatt-hours. The cumulative depth of discharge ranges from 0 to 1. A value of 0 indicates that the energy storage device is not discharging. A value of 1 indicates that the energy storage device is fully discharged.

[0044] Optionally, the cumulative discharge depth can be compared with a preset upper limit for discharge depth. The upper limit for discharge depth is set to 0.8, based on the correlation between the long-term operating life of energy storage devices and discharge depth; a discharge depth exceeding 0.8 will accelerate the aging of energy storage devices. If the cumulative discharge depth is greater than the upper limit, the termination amplitude of the energy storage output control curve is reduced proportionally to the ratio of the upper limit to the cumulative discharge depth. The proportional reduction factor is the ratio of the upper limit to the cumulative discharge depth. Keeping the initial slope and peak value of the energy storage output control curve unchanged, the termination amplitude of the energy storage output control curve is multiplied by the proportional reduction factor to obtain the adjusted termination amplitude. The termination amplitude of the energy storage output control curve refers to the power value corresponding to the termination time of the energy storage output control curve during a period of weak voltage. If the cumulative discharge depth is not greater than the upper limit for discharge depth, the termination amplitude of the energy storage output control curve remains unchanged.

[0045] It is understandable that the adjusted curve will be used as the final energy storage operation curve. In the final energy storage operation curve, the initial slope and peak value of the energy storage output control curve remain unchanged, and only the termination amplitude changes based on the comparison between the cumulative discharge depth and the upper limit of the discharge depth. The final energy storage operation curve is used for subsequent power output control of energy storage equipment.

[0046] In practical implementation, the final energy storage action curve is discretized into a sequence of power commands at equal time intervals. The final energy storage action curve is a time-continuous power curve, with time on the horizontal axis and the active power setpoint of the energy storage device on the vertical axis. The discretization time interval is set to 1 second, based on the fact that the active power regulation response time constant of the energy storage device's converter is less than 0.5 seconds, and a 1-second time interval ensures that the energy storage device can track the active power setpoint within each time interval. During the discretization process, starting from the beginning of the final energy storage action curve, an instantaneous power value on the curve is taken as a power command value every 1 second. Each power command value is arranged in chronological order to form a power command sequence. The power command sequence contains multiple power command values, with the unit of power command value being kilowatts.

[0047] Optionally, discretization can also employ the average power value over time intervals. Within each discretized time interval, the final energy storage action curve is integrated over time, and the integration result is divided by the length of the discretized time interval to obtain the average power value. This average power value is then used as the power command value for the corresponding time interval. Using the average power value over time intervals can reduce the energy deviation between the power command sequence and the final energy storage action curve.

[0048] In some embodiments, active power setpoints are sequentially sent to the converter of the energy storage device according to each power command value in the power command sequence. The converter of the energy storage device is a power conversion device between the energy storage device and the power grid. After receiving the active power setpoint, the converter adjusts the output power of the energy storage device so that the actual output power of the energy storage device tracks the active power setpoint. Within each discretized time interval, the converter executes one active power setpoint. The active power setpoint is transmitted from the smart converged terminal of the power grid to the converter controller of the energy storage device via a communication interface.

[0049] In practice, the actual output power of the energy storage device is collected simultaneously with the transmission of each active power setpoint. The actual output power of the energy storage device is collected by a power sensor on the AC side of the device, which captures the instantaneous value of the output power. The sampling frequency of the power sensor is the same as the sampling frequency of the real-time operating data. The sampling frequency of the power sensor is set to collect 10 instantaneous output power values ​​within each discretized time interval, and the arithmetic mean of these 10 instantaneous output power values ​​is taken as the actual output power within that time interval.

[0050] Optionally, the instantaneous deviation between the actual output power and the active power setpoint is calculated. The instantaneous deviation is calculated at the end of each discretized time interval. The instantaneous deviation equals the active power setpoint of the current discretized time interval minus the actual output power of the energy storage device in the current discretized time interval. A closed-loop correction is then performed on the power command value for the next time interval based on the instantaneous deviation. The formula for calculating the closed-loop correction is: ; in, Indicates the first The corrected power command value for each time interval, in kilowatts; Indicates the first The original power command value for each time interval, in kilowatts; Indicates the first The original power command value for each time interval, in kilowatts; Indicates the first The actual output power of the energy storage device collected within a time interval, in kilowatts; This represents the closed-loop correction proportional coefficient, which is dimensionless and ranges from 0.1 to 0.5. The closed-loop correction proportional coefficient is set to 0.3 because the ratio of the converter response time constant of the energy storage device to the discretization time interval is 0.5. Setting it to 0.3 can avoid power command oscillation caused by closed-loop correction, while ensuring that the actual output power of the energy storage device is close to the corrected power command value in the next time interval. This refers to the time interval number in the power command sequence. Take a positive integer.

[0051] In practical implementation, the modified power command value is used to control the output power of the energy storage device. The modified power command value is used as the first... The active power setpoint for each time interval is sent to the converter of the energy storage device. The converter adjusts the output power of the energy storage device according to the corrected active power setpoint. The process of sending the active power setpoint, collecting the actual output power, calculating the instantaneous deviation, and performing closed-loop correction on the power command value for the next time interval is repeated within each time interval.

[0052] See Figure 5 In the graph, the horizontal axis represents time in seconds, ranging from 0 to 600 seconds; the vertical axis represents the active power command value in kilowatts, ranging from -10 to 90 kilowatts. The solid blue line represents the final energy storage action curve, the dashed red line represents the power command sequence, the green dots represent the actual output power of the energy storage device, and the purple squares represent the corrected power command value.

[0053] As shown in the figure, the final energy storage action curve and power command sequence exhibit a significant power compensation peak between approximately 140 and 210 seconds, with a peak power of about 80 kW. This meets the design requirement in the aforementioned embodiment that the peak value of the power compensation ramp curve is set to 80% of the rated power of the energy storage device. The power compensation process presents a triangular ramp shape with a linear rise followed by a linear fall, where the rise and fall phases are roughly equal in length, each lasting approximately 35 seconds. This conforms to the requirement that the rise and fall durations of the power compensation ramp curve each account for half of the voltage weakness period.

[0054] Before the peak power compensation occurs, the power command sequence exhibits a zero-power or extremely low-power state, indicating that the energy storage device remains in standby mode outside of periods of low voltage. The power command sequence largely coincides with the final energy storage operation curve, demonstrating that the discretization process accurately reflects the changes in the continuous curve.

[0055] The corrected power command value (purple square) closely follows the trend of the power command sequence, with slight adjustments during the power increase phase, demonstrating the effect of closed-loop correction and ensuring that the power command more accurately matches actual demand. The actual output power (green dot) increases significantly during the power compensation phase, with its maximum value close to the peak value of the power command, indicating that the energy storage device can effectively track the control command. At the beginning and end of power compensation, the actual output power fluctuates little, indicating that the energy storage device maintains low power output during the non-compensation phase.

[0056] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for adaptive operation control of multi-scenario energy storage in transformer substations, characterized in that, The method includes: In response to the real-time operation data of the power grid in the distribution area, the voltage fluctuation sequence and load switching timing are extracted from the real-time operation data; Based on the voltage fluctuation sequence, the voltage weak periods of the distribution network are determined, and based on the load switching sequence, the load change nodes of the distribution network are determined. When the voltage-weak period and the load-sudden change node meet the preset energy storage intervention triggering conditions, the power compensation slope curve of the energy storage device is generated with the voltage-weak period as the time reference. The initial slope of the power compensation ramp curve is corrected based on the load abrupt change node to obtain the energy storage output regulation curve; Using the energy storage output control curve as a constraint, the cumulative discharge depth of the energy storage device during the voltage weak period is calculated, and the termination amplitude of the energy storage output control curve is adjusted according to the cumulative discharge depth to obtain the final energy storage operation curve. The energy storage device is controlled to output power according to the final energy storage operation curve.

2. The multi-scenario adaptive operation control method for transformer substation energy storage according to claim 1, characterized in that, The step of extracting the voltage fluctuation sequence and load switching timing from the real-time operating data includes: The instantaneous values ​​of multiphase voltage within a continuous time window are extracted from the real-time operating data. The instantaneous values ​​of multiphase voltage are decomposed into phase sequence to obtain the sequence of the fundamental amplitude of each phase voltage changing with time, which is used as the voltage fluctuation sequence. The current on / off flag bits of each feeder port are parsed from the real-time operating data. The moment when the current on / off flag bit switches from closed to open is marked as the cut-off moment, and the moment when it switches from open to closed is marked as the connection moment. The cut-off moments and the connection moments are arranged in chronological order to obtain the load switching sequence.

3. The multi-scenario adaptive operation control method for transformer substation energy storage according to claim 1, characterized in that, The steps of determining the voltage weak periods of the distribution network based on the voltage fluctuation sequence and determining the load abrupt change nodes of the distribution network based on the load switching sequence include: Find consecutive time periods in the voltage fluctuation sequence where the voltage amplitude is lower than a preset voltage stability lower limit, and mark the consecutive time periods as the voltage weak periods; Identify the time interval between adjacent cut-off and input times from the load switching timing, pair adjacent cut-off times with input times whose time interval is less than a preset switching interval threshold, and mark the paired cut-off times and input times together as the load mutation nodes.

4. The multi-scenario adaptive operation control method for transformer substation energy storage according to claim 1, characterized in that, The step of generating a power compensation ramp curve for the energy storage device, using the voltage-weak period as a time reference, when the preset energy storage intervention triggering conditions are met during the voltage-weak period and at the load-sudden change node, includes: Determine whether the voltage weakness period and the load change node have an intersection on the time axis. If there is an intersection, it is determined that the energy storage intervention trigger condition is met. The starting time of the voltage-weak period is taken as the rising start time of the power compensation slope curve, and the ending time of the voltage-weak period is taken as the falling end time of the power compensation slope curve. Between the rising start time and the falling end time, a triangular slope curve is set in which the power compensation value linearly increases from zero to the peak value and then linearly decreases to zero, which is used as the power compensation slope curve.

5. The multi-scenario adaptive operation control method for transformer substation energy storage according to claim 1, characterized in that, The step of correcting the initial slope of the power compensation ramp curve based on the load abrupt change node to obtain the energy storage output regulation curve includes: Compare the input time of the load mutation node with the rising start time of the power compensation ramp curve; If the input time is earlier than the rising start time, then the initial slope of the power compensation ramp curve at the rising start time is increased; If the input time is later than the rise start time, then the initial slope of the power compensation ramp curve at the rise start time is reduced; Starting with the corrected initial slope, while keeping the peak value and termination time of the power compensation slope curve unchanged, a new corrected slope curve is generated as the energy storage output control curve.

6. The multi-scenario adaptive operation control method for transformer substation energy storage according to claim 1, characterized in that, The step of calculating the cumulative discharge depth of the energy storage device during the voltage-weak period, using the energy storage output control curve as a constraint, and adjusting the termination amplitude of the energy storage output control curve according to the cumulative discharge depth to obtain the final energy storage operation curve includes: By integrating the energy storage output control curve over time during the voltage-weak period, the theoretical discharge capacity of the energy storage device during the voltage-weak period is obtained. Obtain the rated capacity of the energy storage device, divide the theoretical discharge capacity by the rated capacity, and obtain the cumulative discharge depth. The cumulative discharge depth is compared with a preset upper limit of discharge depth. If the cumulative discharge depth is greater than the upper limit of discharge depth, the termination amplitude of the energy storage output control curve is reduced proportionally to the ratio of the upper limit of discharge depth to the cumulative discharge depth. If the cumulative discharge depth is not greater than the upper limit of discharge depth, the termination amplitude of the energy storage output control curve remains unchanged, and the adjusted curve is used as the final energy storage action curve.

7. The multi-scenario adaptive operation control method for transformer substation energy storage according to claim 1, characterized in that, The step of controlling the energy storage device to output power according to the final energy storage operation curve includes: The final energy storage action curve is discretized into a power command sequence with equal time intervals; According to each power command value in the power command sequence, the active power setpoint is sent to the converter of the energy storage device in sequence; While sending each active power setpoint, the actual output power of the energy storage device is collected, the instantaneous deviation between the actual output power and the active power setpoint is calculated, and the power command value for the next time interval is corrected in a closed loop based on the instantaneous deviation, so as to control the output power of the energy storage device with the corrected power command value.

8. The multi-scenario adaptive operation control method for transformer substation energy storage according to claim 2, characterized in that, The step of parsing the current on / off flag bits of each feeder port from the real-time operating data includes: The effective current value of each feeder port is read from the real-time operation data. Feeder ports with effective current values ​​greater than a preset conduction current threshold are determined to be in a closed state, and feeder ports with effective current values ​​less than or equal to the conduction current threshold are determined to be in an open state. The current on / off flag position corresponding to the closed state is set as the first flag value, and the current on / off flag position corresponding to the open state is set as the second flag value; The current on / off flag bits of each feeder port are sorted by time. The moment when the current on / off flag bit jumps from the second flag value to the first flag value is the activation moment, and the moment when the current on / off flag bit jumps from the first flag value to the second flag value is the deactivation moment.

9. The multi-scenario adaptive operation control method for transformer substation energy storage according to claim 5, characterized in that, The step of increasing the initial slope of the power compensation ramp curve at the rising start time if the input time is earlier than the rising start time includes: Calculate the time difference between the start of the ascent and the start of the deployment, and determine the slope increment coefficient based on the time difference; Multiply the original initial slope of the power compensation ramp curve at the rising start time by the slope increment coefficient to obtain the increased initial slope; The step of reducing the initial slope of the power compensation ramp curve at the rising start time if the input time is later than the rising start time includes: Calculate the time difference between the input time and the upward start time, and determine the slope reduction coefficient based on the time difference; The reduced initial slope is obtained by multiplying the original initial slope of the power compensation ramp curve at the rising start time by the slope reduction coefficient.

10. The multi-scenario adaptive operation control method for transformer substation energy storage according to claim 6, characterized in that, When the termination amplitude of the energy storage output control curve is reduced proportionally to the ratio of the upper limit of the discharge depth to the cumulative discharge depth, the initial slope and peak value of the energy storage output control curve are kept unchanged.

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