A multi-energy complementary energy storage system and method based on smart grid

Abstract

This invention relates to the field of smart grid technology and discloses a multi-energy complementary energy storage system and method based on a smart grid. It is applicable to power distribution scenarios including an AC common coupling point bus, electrochemical energy storage, thermal storage devices, hydrogen production devices, and fuel cells. The system obtains three-phase voltage samples, three-phase current samples, and grid frequency through a common coupling point measurement unit. An energy management system forms a synchronous observation window at the common coupling point to obtain frequency deviation, dimensionless active power, and voltage deviation. A loop presence indicator and strength index are generated through dual-projection processing. When a loop exists, dynamic dead-zone processing, reverse holding processing, and ramp-up shaping processing are applied to the base target power based on the strength index. After grid connection safety verification, the multi-energy storage unit is controlled to reduce reverse switching between charging and discharging and maintain grid connection constraints.

Description

Technical Field

[0001] This invention belongs to the field of smart grid technology, specifically relating to a multi-energy complementary energy storage system and method based on smart grid. Background Technology

[0002] The park's microgrid and user-side distribution system are typically connected to the upper-level distribution network at the AC common coupling point. Field equipment includes photovoltaic inverters, wind power converters, conventional loads, controllable loads, electrochemical energy storage, thermal storage devices, hydrogen production units, hydrogen storage units, fuel cells, meters, protection devices, and energy management systems. On the operation side, the system generally relies on the voltage, current, frequency, grid connection point switching power, equipment state of charge, temperature, and alarm levels at the common coupling point to calculate renewable energy output, load demand, and available energy storage power according to the dispatch cycle.

[0003] In conventional implementations, the energy management system typically issues charge / discharge commands based on net power, fixed dead zone, fixed ramp rate, and equipment priority, which are then executed by the converter, battery management system, hydrogen production controller, thermal storage controller, and fuel cell controller. This process is suitable for handling relatively stable source-load deviations and is also easy to coordinate with equipment ratings, state of charge, start-up and shutdown times, and grid connection protection.

[0004] When photovoltaic, wind power, and load alternate within a short period of time, the active power, voltage, and grid frequency at the common coupling point may continuously fluctuate within a single dispatch window. If the energy storage direction is still switched only based on the net power exceeding the threshold at a single moment, electrochemical energy storage, hydrogen production devices, and fuel cells may receive continuous commands in the opposite direction, and the thermal storage side and hydrogen energy side will also frequently adjust the absorbed power or output power according to the equipment priority.

[0005] Engineering sites typically already have the conditions for sampling three-phase voltage, three-phase current, and grid frequency. The challenge lies in how to enable the energy management system to use time-series data within the same observation window to determine whether there are back-and-forth changes in the operation of the common coupling point without adding new dedicated acquisition hardware. Under the premise of prioritizing safety verification, the system-level target power should be buffered, maintained, and speed-limited to provide more stable control input for downstream multi-energy storage devices. Summary of the Invention

[0006] The present invention aims to provide a multi-energy complementary energy storage system and method based on smart grids, which solves the technical problems mentioned in the background art.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution.

[0008] A multi-energy complementary energy storage method based on smart grids, applied to smart grids containing AC common point coupling bus and multi-energy storage units, includes: The three-phase voltage sampling, three-phase current sampling, and grid frequency of the AC common coupling point bus are obtained, and a synchronous observation window for the common coupling point is formed. Based on the three-phase voltage sampling, the three-phase current sampling, and the grid frequency, the frequency deviation, the dimensionless active power, and the voltage deviation are obtained. The time-ordered samples within the synchronous observation window of the same common coupling point are projected onto the dimensionless plane of frequency deviation and active power, and the plane of frequency deviation and voltage deviation, respectively. Based on the directional area determination results, directional consistency, degree of closure, and number of times the frequency zero line is crossed by the two projections, a structural presence marker is generated to characterize whether the dual-projection co-directional return loop structure of the common coupling point exists, and the structural strength is determined by the area balance and degree of closure. The directional area determination results are used to characterize whether the two projections form non-degenerate closed areas respectively, and the structural presence marker and the structural strength constitute the dual-projection co-directional return loop feature of the common coupling point. The basic target power is determined based on the total power of renewable energy and the total load power. When the structure indicates that the common coupling point double-projection unidirectional foldback loop structure exists, the basic target power is dynamically processed for dead zone, reverse holding, and ramping shaping based on the structure strength to form command power. After performing grid-connection safety verification on the commanded power, the multi-energy storage unit is controlled to operate.

[0009] Compared with the prior art, the present invention has the following substantial features and significant progress: This invention utilizes existing measurement channels on the AC common coupling point bus to collect three-phase voltage samples, three-phase current samples, and grid frequency. A synchronous observation window for the common coupling point is formed within the energy management system, and loop presence indicators and strength indices are obtained through dual-projection processing. Under the premise of prioritizing grid connection safety verification, dynamic dead-zone, reverse hold, and ramp-up shaping are applied to the base target power. This processing reduces reverse switching of charge and discharge during short-term alternating fluctuations in source and load in electrochemical energy storage, thermal storage devices, hydrogen production devices, and fuel cells, mitigating the impact of active power fluctuations at the grid connection point on voltage and frequency. Simultaneously, it does not require additional dedicated sensors and retains equipment-level power allocation, operating limits, and local protection logic. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the system architecture and control mechanism of the multi-energy complementary energy storage system and method based on smart grid of the present invention. Detailed Implementation

[0011] The following description is provided in conjunction with the accompanying drawings. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the invention; those skilled in the art can make equivalent substitutions or combinations for the specific implementations.

[0012] This embodiment is applicable to smart grids containing AC common coupling point bus 100 and multi-energy storage unit 140, especially to park-level smart grids, user-side power distribution systems, AC power distribution scenarios containing distributed photovoltaic and wind power generation, and multi-energy complementary energy storage scenarios containing electrochemical energy storage 141, thermal storage device 142, hydrogen production device 143, hydrogen storage device 144 and fuel cell 145.

[0013] This implementation method focuses on the control based on the three-phase voltage sampling quantity 300, three-phase current sampling quantity 301, and grid frequency 302 already available at the AC common coupling point bus 100.

[0014] like Figure 1 As shown, the AC common coupling point bus 100 serves as the power exchange boundary between the local smart grid and the upstream AC distribution network 110. The renewable energy generation unit 120, load unit 130, and multi-energy storage unit 140 are all connected to the AC common coupling point bus 100. The common coupling point measurement unit 150 obtains three-phase voltage sampling data 300, three-phase current sampling data 301, and grid frequency 302 from the AC common coupling point bus 100, and sends them to the energy management system 160 through the measurement data stream 200.

[0015] The energy management system 160 establishes a common coupling point synchronous observation window 320 based on the measurement data stream 200, and determines the frequency deviation 303, the dimensionless active power 304, and the voltage deviation 305 within the common coupling point synchronous observation window 320. Subsequently, the energy management system 160 obtains the first projected oriented area 306 and the second projected oriented area 307 through dual projection processing, and the return loop determination module 164 determines the structural presence indicator 311 and structural strength 312 by combining the directional consistency 308, the degree of closure 309, and the number of times the frequency zero line crosses 310.

[0016] In this embodiment, the common coupling point double-projection unidirectional loop feature is composed of a structural presence marker 311 and a structural strength 312. The structural presence marker 311 is used to characterize the existence of the common coupling point double-projection unidirectional loop structure, and the structural strength 312 is determined by the area uniformity and closure degree 309. When the structural presence marker 311 indicates the existence of the common coupling point double-projection unidirectional loop structure, the energy management system 160 performs dynamic dead zone processing, reverse holding processing, and ramp-up shaping processing on the basic target power 313 based on the structural strength 312 to form the commanded power 314.

[0017] The purpose of this implementation is not to replace existing grid-connected protection, nor to change the energy conservation relationship of the basic charging direction or the basic discharging direction. Rather, when short-term alternating fluctuations of source and load occur at the AC common coupling point bus 100 and form a closed reciprocating dynamic, the command power 314 received by the multi-energy storage unit 140 is made more stable, reducing the frequent reverse switching between charging and discharging, and ensuring that grid-connected safety verification always takes precedence over power shaping results.

[0018] The system of this embodiment includes an AC common coupling point bus 100, an upstream AC distribution network 110, a renewable energy generation unit 120, a load unit 130, a multi-energy storage unit 140, a common coupling point measurement unit 150, an energy management system 160, and an equipment control unit 170. The above components are... Figure 1 A complete control link is formed through the power connection line, measurement data stream 200, command power data stream 210, device-level command power data stream 220 and safety verification feedback data stream 230.

[0019] The AC common coupling point bus 100 is used to connect the local smart grid and the upstream AC distribution network 110, and serves as the boundary for common coupling point operation data acquisition and grid connection point AC power control. The renewable energy generation unit 120 may include photovoltaic power generation equipment, wind power generation equipment, or a combination thereof; the load unit 130 may include conventional loads and controllable loads; and the multi-energy storage unit 140 may include at least one of electrochemical energy storage 141, thermal storage device 142, hydrogen production device 143, hydrogen storage device 144, and fuel cell 145.

[0020] The common coupling point measurement unit 150 is used to obtain the three-phase voltage sample quantity 300, the three-phase current sample quantity 301, and the grid frequency 302. The common coupling point measurement unit 150 can be implemented by an existing voltage transformer, current transformer, power quality meter, protection measurement device, or synchronous measurement device at the AC common coupling point bus 100, as long as it can provide the three-phase voltage sample quantity 300, the three-phase current sample quantity 301, and the grid frequency 302 corresponding to the same sampling time.

[0021] The refresh cycle of the measurement data stream 200 is denoted as The refresh cycle of the instruction power data stream 210 is denoted as In one implementation, The time interval between adjacent synchronous sampling points within the 320-degree synchronous observation window of the common coupling point shall not exceed this interval. Not greater than the fixed observation window length Each synchronous sampling point output by the common coupling point measurement unit 150 includes a timestamp, three-phase voltage sampling quantity 300, three-phase current sampling quantity 301, and grid frequency 302; the energy management system 160 verifies the continuity of the timestamp, data integrity, and range status.

[0022] If the measured data stream 200 continuously exceeds If the data is not refreshed, or if any synchronous sampling point lacks at least one of the following: three-phase voltage sampling quantity 300, three-phase current sampling quantity 301, and grid frequency 302, the energy management system 160 marks that synchronous sampling point as an invalid sample. If the equipment control unit 170 continuously exceeds... If no instruction response is received, the energy management system 160 will set the available charging power or available discharging power of the corresponding device to zero, while retaining the priority constraints of the grid connection safety verification module 167.

[0023] The energy management system 160 includes a common coupling point synchronous observation window generation module 161, a deviation determination module 162, a dual projection processing module 163, a loop reversal determination module 164, a basic target power formation module 165, a power shaping module 166, a grid connection safety verification module 167, and a command power output module 168. These modules can be deployed in the same industrial computer, edge controller, programmable logic controller, or server, or they can be conventionally distributed between the station control system and the local controller.

[0024] The common coupling point synchronous observation window generation module 161 receives the measurement data stream 200 and forms a common coupling point synchronous observation window 320; the deviation determination module 162 obtains the frequency deviation 303, the dimensionless active power 304, and the voltage deviation 305 based on the common coupling point synchronous observation window 320; the dual projection processing module 163 obtains the first projected directed area 306 and the second projected directed area 307 based on the frequency deviation 303, the dimensionless active power 304, and the voltage deviation 305; the loop determination module 164 obtains the structure existence mark 311 and the structure strength 312 based on the first projected directed area 306, the second projected directed area 307, the directional consistency 308, the degree of closure 309, and the number of times the frequency zero line crosses 310.

[0025] The basic target power forming module 165 forms a basic target power 313 based on the total renewable energy power 316 and the total load power 317; the power shaping module 166 performs dynamic dead zone processing, reverse holding processing and ramp shaping processing on the basic target power 313 based on the structural existence indicator 311 and structural strength 312; the grid connection safety verification module 167 performs grid connection safety verification on the command power 314; and the command power output module 168 outputs the verified command power 314 to the equipment control unit 170 through the command power data stream 210.

[0026] The equipment control unit 170 generates equipment-level command power 315 based on the command power 314, and controls the operation of electrochemical energy storage 141, thermal storage device 142, hydrogen production device 143, hydrogen storage device 144, and fuel cell 145 respectively through the equipment-level command power data stream 220. The equipment control unit 170 may include at least one of a converter controller, battery management system, thermal storage controller, hydrogen production controller, and fuel cell controller, and each controller executes the equipment-level command power 315 according to its local protection logic.

[0027] Within one control cycle, the common coupling point synchronous observation window generation module 161 obtains the three-phase voltage sample 300, the three-phase current sample 301, and the grid frequency 302 from the common coupling point measurement unit 150, and caches multiple synchronous sampling points within the fixed observation window in chronological order to form the common coupling point synchronous observation window 320. Each synchronous sampling point includes the three-phase voltage sample 300, the three-phase current sample 301, and the grid frequency 302 corresponding to the same sampling time.

[0028] The fixed observation window length is denoted as The number of synchronous sampling points is denoted as The number of synchronous discrete samples used for periodic averaging within each synchronous sampling point is denoted as . Fixed observation window length Number of synchronous sampling points and the number of synchronous discrete samples It can be determined by the on-site scheduling cycle, sampling frequency, and data refresh frequency of the common coupling point measurement unit 150.

[0029] In one implementation, the observation window length is fixed. Pick Instant The time limit is 1 second, and not less than two scheduling cycles of the energy management system (160); the number of synchronous sampling points Not less than The number of synchronous discrete samples Not less than one fundamental frequency period The number of synchronous discrete samples. If the sampling frequency of the common coupling point measurement unit 150 is high, the number of synchronous discrete samples will increase. All synchronous discrete samples within one fundamental frequency period can be taken; if the sampling frequency is low, then at least each synchronous sampling point must cover one complete fundamental frequency period.

[0030]

[0031]

[0032]

[0033] in, This indicates the length of a fixed observation window, in seconds. Indicates the number of simultaneous sampling points; This indicates the number of synchronous discrete samples. The energy management system 160 synchronously records the number of valid samples when forming a synchronous observation window 320 at a common coupling point. And calculate the proportion of valid samples. .

[0034]

[0035] in, Indicates the proportion of valid samples. This indicates the number of synchronous sampling points within the common coupling point synchronous observation window 320 that simultaneously have three-phase voltage sampling quantity 300, three-phase current sampling quantity 301, and grid frequency 302. If or The energy management system 160 does not calculate the first projected oriented area 306 and the second projected oriented area 307, and sets the structure existence flag 311 to a non-existent state.

[0036] For the Within the first synchronous sampling point A synchronous discrete sample, the sum of the three-phase instantaneous power is denoted as . It is obtained from the three-phase voltage sampling quantity 300 and the three-phase current sampling quantity 301 according to the instantaneous power correspondence.

[0037]

[0038] in, , and They represent the first Within the first synchronous sampling point The three-phase voltage sampling quantity of each synchronous discrete sample is 300. , and They represent the first Within the first synchronous sampling point The number of three-phase current samples for each synchronous discrete sample is 301. This represents the sum of the three-phase instantaneous power corresponding to the same synchronous discrete sample.

[0039] Active power is denoted as It is obtained by periodic averaging based on the instantaneous power correspondence between the three-phase voltage sample quantity 300 and the three-phase current sample quantity 301 within the same synchronous sampling point.

[0040]

[0041] in, Indicates the first The active power corresponding to each synchronous sampling point This represents the number of synchronous discrete samples. This represents the sum of the three-phase instantaneous power.

[0042] The sum of the squares of voltages is denoted as It is obtained based on the three-phase voltage sampling quantity of 300 from the same synchronous discrete sample.

[0043]

[0044] in, Indicates the first Within the first synchronous sampling point The sum of squares of voltages from a synchronous discrete sample. The effective voltage value is denoted as... It is obtained by periodic averaging based on the amplitude square average relationship of the three-phase voltage sampling quantity 300 within the same synchronous sampling point.

[0045]

[0046] in, Indicates the first The effective voltage value corresponding to each synchronous sampling point Represents the sum of squares of voltages. This indicates the number of synchronous discrete samples. The effective voltage value is used to subsequently determine the voltage deviation 305 and to characterize the voltage operating status at the common coupling point in grid connection safety verification.

[0047] When the common coupling point measurement unit 150 experiences short-term communication anomalies or data quality marking anomalies, the energy management system 160 may discard the abnormal samples in the current common coupling point synchronous observation window 320, or adopt a fixed power, shutdown strategy, or local equipment protection limit according to the existing protection strategy, without generating the common coupling point dual-projection unidirectional loop feature based on the abnormal samples.

[0048] The deviation determination module 162 takes the grid frequency 302, active power, and effective voltage values ​​within the common coupling point synchronous observation window 320 as inputs to obtain the frequency deviation 303, the dimensionless active power 304, and the voltage deviation 305, respectively. The purpose of this step is to convert the state variables of the common coupling point in systems with different voltage levels and capacities to a comparable dimensionless scale.

[0049] Frequency deviation of 303 is denoted as The rated frequency is denoted as , No. The grid frequency 302 corresponding to each synchronous sampling point is denoted as . The frequency deviation of 303 is determined by the following formula.

[0050]

[0051] in, This indicates a frequency deviation of 303. Indicates the first The power grid frequency corresponding to each synchronous sampling point is 302. This indicates the rated frequency. Frequency deviation 303 is used to characterize the degree of deviation of the power grid frequency 302 from the rated frequency.

[0052] The average active power of the observation window is denoted as It consists of the active power of all synchronously sampled points within the synchronous observation window 320 of the common coupling point. The average is obtained.

[0053]

[0054] in, This represents the average active power within the observation window. Indicates the number of simultaneous sampling points. Indicates the first The active power corresponding to each synchronous sampling point. The average active power of the observation window is used as the center value of the dimensionless active power quantity 304, so that the dimensionless active power quantity 304 reflects the relative power flow changes within the synchronous observation window 320 of the common coupling point.

[0055] The dimensionless quantity of active power is 304. The system reference power is denoted as The positive number of zero power is denoted as Zero-power positive value protection It has power dimensions to prevent the system reference power from being measured. It is zero or abnormally close to zero. The dimensionless active power 304 is determined by the following formula.

[0056]

[0057] in, 304 represents the dimensionless quantity of active power. Indicates active power. This represents the average active power within the observation window. Indicates the system reference power. Indicates a positive zero-power protection value. System reference power. The rated switching power corresponding to the AC common coupling point bus 100 is used first; if no rated switching power is configured, the active power corresponding to the rated capacity of the upstream transformer of the AC common coupling point bus 100 is used; if neither of the above two is configured, the larger of the rated power of the renewable energy generation unit 120 and the multi-energy storage unit 140 is used as the system reference power. Zero-power positive value protection Pick of to times.

[0058] Voltage deviation of 305 is denoted as The rated voltage is denoted as The effective value of the voltage is denoted as The voltage deviation of 305 is determined by the following formula.

[0059]

[0060] in, This indicates a voltage deviation of 305. Indicates the effective value of the voltage. This indicates the rated voltage. The voltage deviation of 305 is used to characterize the degree of deviation of the operating voltage at the AC common coupling point bus 100 from the rated voltage.

[0061] In this embodiment, the frequency deviation 303, the dimensionless active power 304, and the voltage deviation 305 are all derived from the three-phase voltage sampling quantity 300, the three-phase current sampling quantity 301, and the grid frequency 302, which do not exceed the existing measurement capabilities of the common coupling point measurement unit 150.

[0062] The dual-projection processing module 163 projects the time-ordered samples within the synchronous observation window 320 of the same common coupling point onto the planes of frequency deviation 303 and dimensionless active power 304, and frequency deviation 303 and voltage deviation 305, respectively. Both projections use the same set of time-ordered samples, thus sharing the same temporal order basis.

[0063] To calculate the directed area of ​​the closed trajectory, the dual-projection processing module 163 connects the last synchronous sampling point within the common coupling point synchronous observation window 320 with the first synchronous sampling point, thereby forming the first closed trajectory and the second closed trajectory. The relationship between the closed trajectories is expressed by the following formula.

[0064]

[0065] in, , and These represent the extensions used for calculating the closed trajectory. , and These represent the frequency deviation 303, the dimensionless active power 304, and the voltage deviation 305 corresponding to the first synchronous sampling point within the synchronous observation window 320 of the common coupling point, respectively.

[0066] The first closed trajectory lies in the plane of frequency deviation 303 and dimensionless active power 304, and the first projected directed area 306 is denoted as... .

[0067]

[0068] in, The first projected oriented area is 306. and This indicates a frequency deviation of 303. and The dimensionless active power quantity 304 is represented. The first projected directional area 306 is used to characterize the area scale and time direction of the closed reciprocating relationship formed by the frequency deviation 303 and the dimensionless active power quantity 304 within the synchronous observation window 320 at the common coupling point.

[0069] The second closed trajectory lies in the plane of frequency deviation 303 and voltage deviation 305, and the second projected directed area 307 is denoted as... .

[0070]

[0071] in, The second projected oriented area is 307. and This indicates a frequency deviation of 303. and The voltage deviation 305 is represented. The second projected oriented area 307 is used to characterize the area scale and time direction of the closed reciprocating relationship formed by the frequency deviation 303 and the voltage deviation 305 within the synchronous observation window 320 at the common coupling point.

[0072] The directed area determination result is used to characterize whether the two projections form non-degenerate closed areas respectively. The non-degenerate closed area refers to the first projection's directed area 306 reaching the first area threshold and the second projection's directed area 307 reaching the second area threshold, thereby avoiding the accidental small area caused by measurement noise, approximately linear fluctuations, or a single load step being mistakenly identified as a common coupling point in the dual-projection unidirectional foldback structure.

[0073] The loop determination module 164 determines whether a double-projection loop structure with the same direction exists at the common coupling point based on the first projected oriented area 306, the second projected oriented area 307, directional consistency 308, degree of closure 309, and the number of times the frequency zero line is crossed 310. This determination allows the energy management system 160 to consider not only the area size, but also the time direction, the degree of proximity between the beginning and end, and the round-trip characteristics of the frequency deviation 303.

[0074] The three-dimensional state trajectory difference component is determined by the frequency deviation 303, the dimensionless active power 304, and the voltage deviation 305 of adjacent synchronous sampling points.

[0075]

[0076]

[0077]

[0078] in, This represents the adjacent difference components of a frequency deviation of 303. This represents the adjacent difference components of the dimensionless active power quantity 304. This represents the adjacent difference components of the voltage deviation of 305.

[0079] The total path length of the three-dimensional state trajectory is denoted as The distance between the first and last ends is denoted as A closure degree of 309 is denoted as .

[0080]

[0081]

[0082]

[0083] in, This represents the total path length of the three-dimensional state trajectory. Indicates the distance between the beginning and end. This indicates a degree of closure of 309. This represents a positive number in the zero-prevention path. It is a dimensionless path quantity, with a value of to This is only used to prevent the total path length of the three-dimensional state trajectory. The value is zero. The smaller the degree of closure 309, the closer the end state of the synchronous observation window 320 at the common coupling point is to the initial state, and the more reliable the dual-projection unidirectional foldback loop structure at the common coupling point is.

[0084] The frequency zero line crossing number 310 is recorded as It is used to indicate the number of times the frequency deviation 303 crosses the zero line within the synchronous observation window 320 at the common coupling point.

[0085] To avoid repeated counting due to measurement resolution near the zero line caused by frequency deviation 303, the energy management system 160 sets a frequency zero-crossing detection dead zone. Frequency zero-crossing detection dead zone It is a dimensionless quantity, measured by the frequency resolution of the common coupling point measurement unit 150. and rated frequency Sure.

[0086]

[0087] in, This indicates the dead zone for determining the zero-crossing frequency. This indicates the frequency resolution of the common coupling point measurement unit 150 outputting the mains frequency of 302. Indicates the rated frequency. When At this time, the synchronous sampling point does not form a new zero-line crossing event on its own; multiple synchronous sampling points that are continuously in the frequency zero-crossing judgment dead zone are treated as a zero-crossing transition segment. Only when the frequency deviation 303 before and after the transition segment has opposite signs, the frequency zero-line crossing number 310 increases by one.

[0088]

[0089] in, This indicates that the frequency zero line crossed 310 times. This is an indicator function that takes one when the condition is true and zero when the condition is false. If the frequency zero line crosses the line 310 at least twice, it indicates that the frequency deviation 303 undergoes a round-trip change within the synchronous observation window 320 at the common coupling point, rather than a unidirectional drift.

[0090] Directional consistency 308 is denoted as It is used to indicate whether the first projected oriented area 306 and the second projected oriented area 307 are in the same direction.

[0091]

[0092] in, Indicates directional consistency 308. The first projected oriented area is 306. The second projection has a oriented area of ​​307. When the directional consistency 308 is one, it indicates that the two projections have a consistent time direction.

[0093] Area uniformity is denoted as It is used to characterize the degree of balance between the first projected directional area 306 and the second projected directional area 307.

[0094]

[0095]

[0096]

[0097] in, This represents the minimum projected area. Represents the sum of the projected areas. Indicates a positive number for the area of ​​zero protection. Indicates area uniformity. Prevents zero area from being a positive number. It is a dimensionless area quantity, with a value of to This is only used to prevent the sum of the projected areas from being zero. The closer the area uniformity is to one, the more it indicates that both projections have comparable non-degenerate areas, thus avoiding the false triggering of the structure presence flag 311 when one of the projections is approximately a straight line.

[0098] The loop determination module 164 generates a structure presence marker 311 and a structure strength 312 based on the first projected directional area 306, the second projected directional area 307, the directional consistency 308, the degree of closure 309, and the number of times the frequency zero line crosses 310. The structure presence marker 311 and the structure strength 312 constitute a common coupling point double-projection unidirectional loop feature.

[0099] The first area criterion is denoted as The second area criterion is denoted as The closure criterion is denoted as The criterion for reversal is recorded as follows: The first area threshold is denoted as The second area threshold is denoted as The closure threshold is denoted as .

[0100]

[0101]

[0102]

[0103]

[0104] in, This indicates the first area criterion. This indicates the second area criterion. This indicates the closure criterion. Indicates the criterion for reversal. Indicates the first area threshold. This represents the second area threshold. Indicates the threshold of closure. This indicates the number of times the neutral wire crosses the frequency range is 310. The first area threshold, the second area threshold, and the closure degree threshold can be determined based on operating procedures, equipment ratings, historical operating data, or on-site commissioning.

[0105] First area threshold Second area threshold and closure threshold Calibrate the system using historical operating data or on-site debugging data before it is put into operation. The calibration data includes no less than [number missing]. A normal observation window in which no short-term alternation of source load occurred. Not less than The energy management system 160 calculates the first projected oriented area 306, the second projected oriented area 307, and the degree of closure 309 for each normal observation window, and obtains reference values ​​for the first projected noise area, the second projected noise area, and the degree of closure.

[0106]

[0107]

[0108]

[0109]

[0110] in, Indicates the area of ​​the first projected noise. This represents the area of ​​the second projected noise. Indicates the first The first projected oriented area of ​​a normal observation window is 306. Indicates the first The second projected oriented area of ​​a normal observation window is 307. This represents the first area threshold magnification factor. This represents the second area threshold magnification factor. The first area threshold magnification factor... Second area threshold magnification factor Pick to .

[0111] Closure threshold Pick to When there are confirmed short-term alternating fluctuations of source loads on site, a value that satisfies the closure criterion for the confirmed samples but does not satisfy the closure criterion for the normal observation window is selected as the closure degree threshold. When there are no confirmed samples at the scene, the closure threshold Pick And after commissioning, use no less than the nearest A normal observation window is used to verify false triggering situations.

[0112] The structure exists as 311. It is determined by the first projected directional area 306, the second projected directional area 307, the directional consistency 308, the degree of closure 309, and the number of times the frequency zero line crosses 310.

[0113]

[0114] in, The structure is indicated by flag 311. This indicates the first area criterion. This indicates the second area criterion. This indicates the closure criterion. Indicates the criterion for reversal. Indicates directional consistency 308. When the structure has a flag 311 of one, it is assumed that a common coupling point double-projection unidirectional foldback structure exists.

[0115] Structural strength 312 is denoted as It is determined by the area uniformity and the degree of closure 309.

[0116]

[0117] in, This indicates a structural strength of 312. The structure is indicated by flag 311. Indicates area uniformity. This indicates a degree of closure of 309. This indicates the threshold for the degree of closure. The larger the structural strength 312, the more obvious the double-projection unidirectional foldback structure at the common coupling point, and the stronger the dynamic dead zone processing, reverse holding processing, and ramp-up shaping processing of the power shaping module 166 for the basic target power 313.

[0118] The value of structural strength 312 is jointly limited by structural presence indicator 311, area uniformity, and closure degree 309. Due to area uniformity... The value is located in to ,and The value is located in to The range of values ​​for structural strength 312 is: to When the structural presence flag 311 is in a non-existent state, the structural strength 312 is... When the two projected areas are equal and their degree of closure is close to 309. At that time, the structural strength 312 is close to .

[0119]

[0120] The characteristic of the common coupling point double-projection unidirectional loop can be expressed as: .

[0121]

[0122] in, This indicates the characteristic of a double-projection, same-direction loop at the common coupling point. The structure is indicated by flag 311. This indicates a structural strength of 312. This representation is similar to... Figure 1 The output of the mid-loop determination module 164 to the power shaping module 166 corresponds to the link with the structure presence flag 311 and the structure strength 312.

[0123] The basic target power generation module 165 generates a basic target power 313 based on the total renewable energy power 316 and the total load power 317. The total renewable energy power 316 can be obtained by summing the output power of photovoltaic power generation equipment, wind power generation equipment or combinations thereof in the renewable energy power generation unit 120, and the total load power 317 can be obtained by summing the power consumption of conventional loads and controllable loads in the load unit 130.

[0124] Net power is denoted as The total renewable energy power of 316 is recorded as The total load power of 317 is denoted as .

[0125]

[0126] in, Indicates the first Net power consumption per control cycle The total power of renewable energy is 316. This indicates a total load power of 317. When the net power is greater than zero, it indicates that there is a power surplus that can be used for charging or energy conversion of the multi-energy storage unit 140; when the net power is less than zero, it indicates that there is a power deficit that needs to be discharged by the multi-energy storage unit 140 or supplemented by the upstream AC distribution network 110.

[0127] The basic target power of 313 is denoted as It can be determined by net power, planned exchange power bias, available charging power of equipment, available discharging power of equipment, and fixed dead zone. If the common coupling point already has planned exchange power, the basic target power forming module 165 can add the planned exchange power as an bias to the net power calculation, so that the multi-energy storage unit 140 can bear the difference between the actual exchange power and the planned exchange power.

[0128] The symbol for the base target power 313 is used to indicate the system-level charging direction or the system-level discharging direction. The structural presence symbol 311 and structural strength 312 do not change the energy conservation relationship corresponding to the base target power 313, but are only used by the subsequent power shaping module 166 to perform dynamic dead zone processing, reverse holding processing and ramp-up shaping processing on the base target power 313.

[0129] During the formation of the basic target power 313, the energy management system 160 can also extract the available charging power and available discharging power of the multi-energy storage unit 140. When the equipment is in a fault, maintenance, over-temperature, over-charged state, or communication interruption state, the available charging power or available discharging power corresponding to the equipment is set to zero.

[0130] When the structural presence marker 311 indicates the existence of a common coupling point double-projection unidirectional loop structure, the power shaping module 166 performs dynamic dead-zone processing, reverse holding processing, and ramp shaping processing on the basic target power 313 based on the structural strength 312 to form the command power 314. If the structural presence marker 311 does not indicate the existence of a common coupling point double-projection unidirectional loop structure, the power shaping module 166 can form the command power 314 according to a fixed dead zone, a fixed ramp rate, and conventional target power limiting rules.

[0131] The basic dead zone is denoted as Dynamic dead zone is denoted as The non-negative proportionality coefficient is denoted as The dynamic dead zone is determined by the following formula.

[0132] Basic dead zone Based on system reference power The proportion is determined, and the basic dead zone proportion is denoted as... .

[0133]

[0134] in, Indicates the basic dead zone. Indicates the basic dead zone ratio. Indicates the system's reference power. Base dead zone ratio. Pick to Non-negative proportionality coefficient Pick to and make dynamic dead zone No more than the system reference power of times; if the calculated dynamic dead zone If the limit is exceeded, the power shaping module 166 performs dynamic dead-time processing according to the limit.

[0135]

[0136] in, Indicates the dynamic dead zone. Indicates the basic dead zone. This represents a non-negative proportionality coefficient. Indicates the first The structural strength corresponding to each control cycle is 312. This represents the system's reference power. The greater the structural strength 312, the larger the dynamic dead zone, thus preventing the immediate triggering of the command power 314 in the opposite direction when the base target power 313 slightly crosses zero power.

[0137] The target power after the dead zone is denoted as Dynamic dead-time handling is performed using the following formula.

[0138]

[0139]

[0140] in, Indicates the target power after the dead zone. This indicates a base target power of 313. This indicates a dynamic dead zone. Dynamic dead zone processing is used to suppress small, recurring out-of-range behavior near zero power, reducing the probability that the electrochemical energy storage 141, hydrogen production device 143, and fuel cell 145 will receive consecutive opposite commands.

[0141] The reverse hold duration is denoted as The basic retention time is recorded as The retention coefficient is denoted as The duration of the reverse hold is determined by the following formula.

[0142] Basic retention time Take one to three scheduling cycles, and maintain the coefficient. Pick to Reverse hold duration No more than the fixed observation window length Twice; if the calculated reverse hold time If the limit is exceeded, reverse holding processing will be performed according to the limit. If the grid connection safety verification module 167 determines that the voltage, frequency, line capacity, transformer capacity, converter capacity, or equipment protection status does not meet the grid connection safety constraints, the reverse holding processing will be canceled immediately.

[0143]

[0144] in, Indicates the duration of reverse hold. Indicates the duration of basic retention. Indicates the retention coefficient. This indicates a structural strength of 312. This indicates the length of the fixed observation window. When the basic target power 313 is to switch in the opposite direction of charging and discharging relative to the command power 314 of the previous cycle, the power shaping module 166 first transitions the command power 314 of the previous cycle to zero power within the reverse holding time, and then forms the command power 314 according to the shaping ramp rate.

[0145] The fixed gradient is denoted as The rate of change in the plastic surgery slope is recorded as The scaling factor for the slope is denoted as The shaping slope rate is determined by the following formula.

[0146] Fixed gradient Determined jointly by the allowable power change rate of the equipment and the grid-connected operation procedures, it shall not exceed the sum of the allowable power change rates of all available equipment in the multi-energy storage unit 140. (Climbing scaling factor) Pick to The lower limit of the slope ratio Pick to By climbing the lower limit ratio Limitation, reshaping ramp rate Not less than 312 for any structural strength .

[0147]

[0148] in, This indicates the rate of change in the plastic surgery slope. Indicates a fixed gradient. Indicates the scaling factor for the hill climb. This indicates a structural strength of 312. This indicates the lower limit of the ramp rate. Lower limit of the ramp rate It is a dimensionless quantity, and its value is [value]. to Used to ensure the climbing rate of the shaping process. The rate of change is always non-negative. The larger the structural strength 312, the smaller the shaping ramp rate, so as to reduce the superimposed effect of the change in command power 314 on the existing reciprocating dynamic at the AC common coupling point bus 100.

[0149] The sampling period is denoted as The instruction power of the previous cycle, 314, is denoted as The climbing limit boundaries are respectively denoted as and .

[0150]

[0151]

[0152]

[0153] in, Indicates the lower boundary of the climbing limit. Indicates the upper boundary of the climbing limit. This indicates a command power of 314. Indicates the target power after the dead zone. This indicates the rate of change in the plastic surgery slope. Indicates the sampling period. This represents a conventional limiting function that restricts the target power after the dead zone to between the lower and upper limits of the ramp limiting.

[0154] Dynamic dead zone processing, reverse hold processing, and ramp shaping processing all apply to the system-level basic target power 313, without changing the local protection execution logic of the device control unit 170 for the device-level command power 315, nor overriding the safety verification results of the grid-connected safety verification module 167.

[0155] The grid connection safety verification module 167 performs grid connection safety verification on the command power 314. The grid connection safety verification includes verifying the grid connection point switching power, the common coupling point voltage operating status characterized by the effective voltage value, the grid frequency 302, the line capacity, the transformer capacity, the converter capacity, and the equipment protection status.

[0156] When the grid connection safety verification passes, the command power output module 168 outputs command power 314 to the device control unit 170 through the command power data stream 210. When the grid connection safety verification fails, the grid connection safety verification module 167 cancels the reverse holding process and forms a command power 314 that meets the grid connection safety constraints by proportionally reducing the command power 314.

[0157] Safety verification feedback data stream 230 is fed back from grid connection safety verification module 167 to power shaping module 166, used to indicate the adjustment command power 314 when the grid connection safety verification fails. This feedback link is connected to... Figure 1 The dotted feedback arrows in the text are consistent, indicating that grid connection safety verification takes precedence over instruction issuance.

[0158] When the commanded power 314 is reduced proportionally, the energy management system 160 can determine the reduction ratio based on the grid connection point's exchange power margin, line capacity margin, transformer capacity margin, converter capacity margin, and equipment protection status. Determining the reduction ratio is a routine grid connection safety constraint process, the purpose of which is to ensure that the commanded power 314 output to the equipment control unit 170 does not cause the AC common coupling point bus 100, grid frequency 302, lines, transformers, converters, or equipment protection status to exceed limits.

[0159] In one implementation, the grid connection safety verification module 167 first calculates the expected grid connection point switching power based on the current command power 314. And read the upper limit of the switching power of the grid connection point. Line capacity corresponds to the upper limit of power. Transformer capacity corresponds to the upper limit of power. Power limit corresponding to converter capacity The grid connection safety verification module 167 calculates the reduction ratio of the switching power at the grid connection point, the reduction ratio of the line capacity, the reduction ratio of the transformer capacity, and the reduction ratio of the converter capacity.

[0160] Expected grid connection switching power The positive value represents the power absorbed by the AC common coupling point bus 100 from the upstream AC distribution network 110. The positive value represents the power absorbed by the multi-energy storage unit 140 from the AC common coupling point bus 100, and the negative value represents the power output from the multi-energy storage unit 140 to the AC common coupling point bus 100. The planned exchange power is denoted as... Its positive value is based on the power absorbed from the upstream AC distribution network 110; when no planned exchange power is configured, Set to zero. The expected switching power at the grid connection point is determined by the following formula.

[0161]

[0162] in, This indicates the expected switching power at the grid connection point. This indicates a total load power of 317. The total power of renewable energy is 316. This indicates a command power of 314. This indicates the planned exchange power. According to this symbol convention, when the command power 314 is in the charging direction, the expected grid connection point exchange power is increased; when the command power 314 is in the discharging direction, the expected grid connection point exchange power is decreased.

[0163]

[0164]

[0165]

[0166]

[0167]

[0168]

[0169] in, Indicates the reduction ratio of the switching power at the grid connection point. This indicates the percentage reduction in line capacity. Indicates the reduction ratio of transformer capacity. This indicates the percentage reduction in converter capacity. Indicates the safe reduction ratio. This indicates the command power 314 that meets the grid connection safety constraints. If the common coupling point voltage operating state or grid frequency 302 is not within the allowable operating range, or the equipment protection status is activated, the grid connection safety verification module 167 will reduce the safety ratio. Set as And set the command power 314 that meets the grid connection safety constraints to zero power.

[0170] Grid connection safety verification module 167 formed The estimated switching power at the grid connection point was then recalculated. If the recalculation result still does not meet the grid connection safety constraints, the proportional reduction process is repeated, up to a maximum of three times. If the grid connection safety constraints are still not met after three recalculations, the command power output module 168 outputs a zero-power command, and the equipment control unit 170 maintains or deactivates the multi-energy storage unit 140 according to the local protection logic.

[0171] When the operating status of the common coupling point voltage, the grid frequency 302, or the equipment protection status reaches the emergency limit, the energy management system 160 can immediately set the commanded power 314 to zero, or reduce the load, shut down, or switch to the upstream AC distribution network 110 for power supply according to the equipment's local protection logic. This process does not depend on the existence of the common coupling point dual-projection unidirectional foldback characteristic.

[0172] The multi-energy storage unit 140 includes at least one of electrochemical energy storage 141, thermal storage device 142, hydrogen production device 143, hydrogen storage device 144, and fuel cell 145. The energy management system 160 determines the available charging power and available discharging power of the multi-energy storage unit 140 based on the state of charge, thermal storage state, hydrogen storage state, temperature, alarm status, and rated power.

[0173] The available charging power and available discharging power of the electrochemical energy storage 141 can be determined based on the state of charge, temperature, alarm status, converter capacity, and rated power; the available charging power of the thermal storage device 142 can be determined based on the thermal storage status, temperature, and rated power; the available charging power of the hydrogen production device 143 can be determined based on the hydrogen storage status, the rated power of the hydrogen production device 143, and the operating status; the hydrogen storage status of the hydrogen storage device 144 is used to constrain the operation of the hydrogen production device 143 and the fuel cell 145; the available discharging power of the fuel cell 145 can be determined based on the hydrogen storage status, temperature, alarm status, and rated power.

[0174] In one embodiment, the available charging power and available discharging power of the electrochemical energy storage 141 are truncated to upper and lower limits based on the state of charge and rated power, respectively. The state of charge of the electrochemical energy storage 141 is denoted as... The upper limit of the state of charge is denoted as The state of charge limit is denoted as The rated power of the electrochemical energy storage 141 is denoted as The rated energy of the electrochemical energy storage 141 is denoted as The temperature-constrained power of the electrochemical energy storage 141 is denoted as .

[0175]

[0176]

[0177] in, This indicates the available charging power of the electrochemical energy storage 141. This indicates the available discharge power of the electrochemical energy storage 141. If the electrochemical energy storage 141 is in an alarm state or communication interruption state, then... and Set all values ​​to zero.

[0178] The equivalent electrical energy corresponding to the heat storage state of the heat storage device 142 is denoted as: The equivalent electrical energy corresponding to the upper limit of thermal storage state is denoted as The rated power of the heat storage device 142 is denoted as The temperature constraint power of the heat storage device 142 is denoted as Equivalent electrical energy and equivalent electrical energy All of these are electrical energy values ​​converted to the AC common coupling point bus 100 side based on the fixed conversion efficiency of the thermal storage device 142. Divide by sampling period The absorbable electrical power on the AC common coupling point bus 100 side is then obtained. The available charging power of the thermal storage device 142 is determined by the following formula.

[0179]

[0180] The rated power of the hydrogen production unit 143 is denoted as The equivalent electrical energy corresponding to the hydrogen storage state of hydrogen storage device 144 is denoted as: The upper limit of hydrogen storage state corresponds to the equivalent electrical energy denoted as: The temperature constraint power of hydrogen production unit 143 is denoted as Equivalent electrical energy and equivalent electrical energy All of these figures are calculated based on the fixed conversion efficiency of the hydrogen production unit 143, the hydrogen storage unit 144, and the fuel cell 145, and are converted to the electrical energy output at the AC common coupling point bus 100. Divide by sampling period The electrical power that can be absorbed by the hydrogen production unit 143 is then obtained. Divide by sampling period The electrical power output of fuel cell 145 is then obtained. The available charging power of hydrogen production unit 143 is determined by the following formula.

[0181]

[0182] The rated power of fuel cell 145 is denoted as The temperature-constrained power of fuel cell 145 is denoted as The available discharge power of fuel cell 145 is determined by the following formula.

[0183]

[0184] in, This indicates the available charging power of the heat storage device 142. This indicates the available charging power of the hydrogen production unit 143. This indicates the available discharge power of fuel cell 145. If the heat storage device 142, hydrogen production device 143, hydrogen storage device 144, or fuel cell 145 is in an alarm state, temperature exceeding the limit, or communication interruption state, the corresponding available charging power or available discharge power is set to zero.

[0185] The equipment control unit 170 allocates the commanded power 314 as equipment-level commanded power 315 according to a fixed priority. In this embodiment, the fixed priority in the charging direction is, in order, electrochemical energy storage 141, thermal storage device 142, and hydrogen production device 143; the fixed priority in the discharging direction is, in order, electrochemical energy storage 141 and fuel cell 145. The hydrogen storage device 144 does not directly receive electrical power commands; its hydrogen storage state is used to constrain the available charging power of the hydrogen production device 143 and the available discharging power of the fuel cell 145. This fixed priority remains unchanged under the same operating strategy.

[0186] When the commanded power 314 is in the charging direction, the equipment control unit 170 first allocates the commanded power 314 to the electrochemical energy storage 141, allocates the remaining portion exceeding the available charging power of the electrochemical energy storage 141 to the heat storage device 142, and then allocates the remaining portion exceeding the available charging power of the heat storage device 142 to the hydrogen production device 143.

[0187]

[0188]

[0189]

[0190] When the commanded power 314 is in the discharge direction, the device control unit 170 first allocates the commanded power 314 to the electrochemical energy storage 141, and the remaining part exceeding the available discharge power of the electrochemical energy storage 141 is allocated to the fuel cell 145.

[0191]

[0192]

[0193] in, This indicates the device-level command power of 315 allocated to the electrochemical energy storage 141. This indicates that the equipment-level command power of 315 is allocated to the thermal storage device 142. This indicates that the equipment-level command power of 315 is allocated to the hydrogen production unit 143. This represents the device-level commanded power of 315 allocated to fuel cell 145. (The formula...) This is used to truncate the remaining power to zero when the remaining power factor is rounded or when the upstream device has fully absorbed the commanded power 314. If the available charging power or available discharging power of a device is zero, the device control unit 170 skips that device and processes the remaining devices according to a fixed priority.

[0194] When the command power 314 indicates charging or absorbing electrical power, the equipment control unit 170 can prioritize controlling the electrochemical energy storage 141 to absorb electrical power, and control the heat storage device 142 or the hydrogen production device 143 to absorb electrical power after the electrochemical energy storage 141 reaches the available charging power limit; when the command power 314 indicates discharging or outputting electrical power, the equipment control unit 170 can prioritize controlling the electrochemical energy storage 141 to output electrical power, and control the fuel cell 145 to output electrical power after the electrochemical energy storage 141 reaches the available discharge power limit.

[0195] The equipment control unit 170 controls the multi-energy storage unit 140 to perform charging, discharging, or energy conversion operations according to the equipment-level command power 315. The electrochemical energy storage 141 absorbs or releases electrical power through the converter; the thermal storage device 142 converts electrical energy into heat energy or bears the heat load; the hydrogen production device 143 converts electrical energy into hydrogen energy; the hydrogen storage device 144 stores hydrogen energy; and the fuel cell 145 converts hydrogen energy into electrical energy and outputs power to the AC common coupling point bus 100 through the grid-connected converter.

[0196] When any device is in a state of failure, maintenance, overheating, overcharge, overheating, overheating, overheating, or communication interruption, the energy management system 160 sets the available charging power or available discharging power of the corresponding device to zero, and the device control unit 170 allocates the remaining command power 314 to other available devices according to a fixed priority.

[0197] For example, at the start of a complete control cycle, the common coupling point measurement unit 150 obtains three-phase voltage samples 300, three-phase current samples 301, and grid frequency 302 from the AC common coupling point bus 100, and sends the measurement data stream 200 to the energy management system 160. The common coupling point synchronization observation window generation module 161 caches the synchronization sampling points within the most recent fixed observation window as the common coupling point synchronization observation window 320.

[0198] Subsequently, the deviation determination module 162 calculates the active power and voltage RMS value based on the three-phase voltage sampling quantity 300 and the three-phase current sampling quantity 301, and obtains the frequency deviation 303, the dimensionless active power 304 and the voltage deviation 305 based on the grid frequency 302, the rated frequency, the average active power of the observation window, the system reference power and the rated voltage.

[0199] The dual-projection processing module 163 projects the simultaneously ordered samples within the synchronous observation window 320 of the common coupling point onto the plane of frequency deviation 303 and dimensionless active power 304 to form a first closed trajectory and obtains a first projected directional area 306; at the same time, it projects the simultaneously ordered samples onto the plane of frequency deviation 303 and voltage deviation 305 to form a second closed trajectory and obtains a second projected directional area 307.

[0200] The loop determination module 164 further calculates the directional consistency 308, the degree of closure 309, the number of times the frequency zero line crosses 310, and the area balance. Based on whether the first projected directional area 306 reaches the first area threshold, whether the second projected directional area 307 reaches the second area threshold, whether the directional consistency 308 meets the requirements, whether the degree of closure 309 meets the degree of closure threshold, and whether the number of times the frequency zero line crosses 310 is not less than two, it determines the structural presence mark 311 and the structural strength 312.

[0201] Meanwhile, the basic target power formation module 165 forms a basic target power 313 based on the total renewable energy power 316 corresponding to the renewable energy power generation unit 120 and the total load power 317 corresponding to the load unit 130. After the basic target power 313 enters the power shaping module 166, if the structure existence flag 311 indicates that the common coupling point double projection unidirectional return loop structure exists, the power shaping module 166 performs dynamic dead zone processing, reverse holding processing, and ramp shaping processing according to the structural strength 312 to form the command power 314.

[0202] The grid connection safety verification module 167 performs grid connection safety verification on the command power 314. If the grid connection safety verification passes, the command power output module 168 sends the command power 314 to the device control unit 170 through the command power data stream 210; if the grid connection safety verification fails, the grid connection safety verification module 167 constrains the power shaping module 166 to cancel the reverse holding process and proportionally reduce the command power 314 through the safety verification feedback data stream 230.

[0203] After receiving the command power 314, the equipment control unit 170 allocates the command power 314 as equipment-level command power 315 according to the available capacity determined by the state of charge, thermal storage, hydrogen storage, temperature, alarm status and rated power, and controls the operation of electrochemical energy storage 141, thermal storage device 142, hydrogen production device 143, hydrogen storage device 144 and fuel cell 145 respectively.

[0204] In this complete workflow, the dual-projection unidirectional loop feature of the common coupling point only affects the system-level power shaping link between the basic target power 313 and the command power 314. It does not change the direct acquisition parameters of the common coupling point measurement unit 150, does not change the source of the total renewable energy power 316 and the total load power 317, does not change the local protection logic of the equipment control unit 170, and does not cover the safety verification results of the grid connection safety verification module 167.

[0205] As an optional implementation, under normal steady-state conditions, the total renewable energy power 316 and the total load power 317 change relatively slowly, and the grid frequency 302 and the effective voltage value at the AC common coupling point bus 100 remain within the allowable range. The frequency deviation 303, the dimensionless active power 304, and the voltage deviation 305 within the common coupling point synchronous observation window 320 do not form a significant closed-loop dynamic, the first projected directional area 306 or the second projected directional area 307 does not reach the corresponding area threshold, or the frequency zero line crossings 310 are less than twice.

[0206] Under this operating condition, the structural presence marker 311 does not indicate the existence of a dual-projection unidirectional foldback structure at the common coupling point. The power shaping module 166 processes the basic target power 313 according to the basic dead zone, fixed ramp rate, and conventional amplitude limiting rules to form the command power 314. The equipment control unit 170 generates the equipment-level command power 315 based on the command power 314, and the multi-energy storage unit 140 performs charging, discharging, or energy conversion operations according to a fixed priority.

[0207] As an optional implementation, under the characteristic triggering condition, the photovoltaic power generation equipment, wind power generation equipment, and load unit 130 fluctuate alternately within a short period of time, causing the active power, grid frequency 302, and effective voltage value at the AC common coupling point bus 100 to continuously cycle within a fixed observation window. The time-ordered samples within the common coupling point synchronous observation window 320 form a first closed trajectory in the plane of frequency deviation 303 and the dimensionless active power quantity 304, and a second closed trajectory in the plane of frequency deviation 303 and the voltage deviation 305.

[0208] When the first projected directional area 306 reaches the first area threshold, the second projected directional area 307 reaches the second area threshold, the first closed trajectory and the second closed trajectory satisfy the direction consistency 308, the degree of closure of the three-dimensional state trajectory 309 satisfies the degree of closure threshold and the number of times the frequency zero line crosses is not less than twice, the return loop determination module 164 generates a structure existence flag 311 indicating the existence of the double-projected unidirectional return loop structure at the common coupling point, and determines the structural strength 312 based on the area balance and degree of closure 309.

[0209] Under this operating condition, the base target power 313 may repeatedly switch between charging and discharging directions. The power shaping module 166 increases the dynamic dead zone based on the structural strength 312, determines the reverse holding time based on the structural strength 312, and decreases the shaping ramp rate based on the structural strength 312. When the base target power 313 is about to switch in the reverse charging / discharging direction relative to the commanded power 314 of the previous cycle, the power shaping module 166 first transitions the commanded power 314 of the previous cycle to zero power within the reverse holding time, and then forms the commanded power 314 based on the shaping ramp rate.

[0210] As an optional implementation, even if the structure has a mark 311 indicating that the common coupling point double projection foldback structure exists, the grid connection safety verification module 167 will still prioritize checking the grid connection point switching power, common coupling point voltage operating status, grid frequency 302, line capacity, transformer capacity, converter capacity and equipment protection status when the grid connection safety verification fails.

[0211] When the grid connection point switching power exceeds the constraint, the voltage operating state of the common coupling point represented by the effective voltage value exceeds the limit, the grid frequency 302 exceeds the limit, the line capacity is insufficient, the transformer capacity is insufficient, the converter capacity is insufficient, or the equipment protection status is abnormal, the grid connection safety verification module 167 cancels the reverse holding process and forms the command power 314 that meets the grid connection safety constraints by proportionally reducing the command power 314.

[0212] Under this operating condition, the safety verification feedback data stream 230 causes the power shaping module 166 to yield to the safety verification result of the grid-connected safety verification module 167, and the equipment control unit 170 only receives the verified command power 314. If a device is in an alarm state or local protection state, the equipment control unit 170 sets the device-level command power 315 corresponding to that device to zero and allocates the remaining command power 314 to other available devices according to a fixed priority.

[0213] As an optional implementation, when some energy storage devices are unavailable, such as when the state of charge of electrochemical energy storage 141 reaches its upper limit, the thermal storage state of thermal storage device 142 reaches its upper limit, the hydrogen production device 143 is under maintenance, the hydrogen storage state of hydrogen storage device 144 reaches its upper limit, or the fuel cell 145 is in an alarm state, the energy management system 160 re-determines the available charging power and available discharging power based on the state of charge, thermal storage state, hydrogen storage state, temperature, alarm state, and rated power.

[0214] When the commanded power 314 needs to charge or absorb power, the device control unit 170 allocates the device-level commanded power 315 only within the available device range; when the commanded power 314 needs to discharge or output power, the device control unit 170 similarly allocates the device-level commanded power 315 only within the available device range. The common coupling point dual-projection unidirectional foldback feature is still only used for system-level power shaping and does not replace the device availability constraint.

[0215] This embodiment can also be implemented using a computer-readable storage medium. The computer-readable storage medium stores a computer program, which, when executed by a processor, causes the processor to perform the aforementioned multi-energy complementary energy storage method based on a smart grid. The processor can be located in an energy management system 160, an edge controller, an industrial computer, a programmable logic controller, or a server.

[0216] When the computer program is executed by the processor, the processor can acquire the three-phase voltage sampling quantity 300, the three-phase current sampling quantity 301, and the grid frequency 302 of the AC common coupling point bus 100, form a common coupling point synchronous observation window 320, obtain the frequency deviation 303, the dimensionless quantity of active power 304, and the voltage deviation 305, perform dual projection processing, generate the structural existence mark 311 and the structural strength 312, form the basic target power 313, and perform dynamic dead zone processing, reverse holding processing, and ramp shaping processing on the basic target power 313 based on the structural strength 312.

[0217] When the computer program is executed by the processor, the processor can also perform grid-connected safety verification on the instruction power 314. After the grid-connected safety verification is passed, the control device control unit 170 generates device-level instruction power 315 according to the instruction power 314, thereby controlling the multi-energy storage unit 140 to perform charging, discharging or energy conversion operation.

[0218] The embodiments of this example have been described above. However, this example is not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms based on the guidance of this example, and all of them are within the protection scope of this example.

Claims

1. A multi-energy complementary energy storage method based on smart grids, applied to a smart grid containing an AC common coupling point bus and multi-energy storage units, characterized in that, include: The three-phase voltage sampling, three-phase current sampling, and grid frequency of the AC common coupling point bus are obtained, and a synchronous observation window for the common coupling point is formed. Based on the three-phase voltage sampling, the three-phase current sampling, and the grid frequency, the frequency deviation, the dimensionless active power, and the voltage deviation are obtained. The time-ordered samples within the synchronous observation window of the same common coupling point are projected onto the dimensionless plane of frequency deviation and active power, and the plane of frequency deviation and voltage deviation, respectively. Based on the directional area determination results, directional consistency, degree of closure, and number of times the frequency zero line is crossed by the two projections, a structural presence marker is generated to characterize whether the dual-projection co-directional return loop structure of the common coupling point exists, and the structural strength is determined by the area balance and degree of closure. The directional area determination results are used to characterize whether the two projections form non-degenerate closed areas respectively, and the structural presence marker and the structural strength constitute the dual-projection co-directional return loop feature of the common coupling point. The basic target power is determined based on the total power of renewable energy and the total load power. When the structure indicates that the common coupling point double-projection unidirectional foldback loop structure exists, the basic target power is subjected to dynamic dead zone processing, reverse holding processing, and ramp-up shaping processing based on the structural strength to form command power. After performing grid-connection safety verification on the commanded power, the multi-energy storage unit is controlled to operate.

2. The multi-energy complementary energy storage method based on a smart grid according to claim 1, characterized in that, The common coupling point synchronous observation window consists of multiple synchronous sampling points within a fixed observation time window. Each synchronous sampling point includes the three-phase voltage sample, the three-phase current sample, and the grid frequency corresponding to the same sampling time. The active power is obtained by periodically averaging the instantaneous power correspondence between the three-phase voltage sample and the three-phase current sample within the same synchronous sampling point. The effective voltage value is obtained by periodically averaging the amplitude squared average relationship of the three-phase voltage sample within the same synchronous sampling point.

3. The multi-energy complementary energy storage method based on a smart grid according to claim 1, characterized in that, The characteristics of the dual-projection unidirectional loop at the common coupling point include: The frequency deviation is determined by the rated frequency, the dimensionless active power is determined by the average active power of the observation window and the system reference power, and the voltage deviation is determined by the rated voltage. The time-ordered samples are projected onto the plane of frequency deviation and dimensionless active power to form a first closed trajectory and obtain the first projected directional area. The ordered samples at the same time are projected onto the frequency deviation and voltage deviation plane to form a second closed trajectory, and the second projected directional area is obtained.

4. The multi-energy complementary energy storage method based on a smart grid according to claim 3, characterized in that, The conditions for determining the existence of the aforementioned common coupling point double-projection unidirectional foldback loop structure include: The first projected directional area reaches a first area threshold, the second projected directional area reaches a second area threshold, the first closed trajectory and the second closed trajectory satisfy the direction consistency, the degree of closure of the three-dimensional state trajectory satisfies the degree of closure threshold, and the frequency zero line crosses at least twice.

5. A multi-energy complementary energy storage method based on a smart grid according to claim 4, characterized in that, The structural presence marker in the common coupling point double-projection unidirectional loop feature is determined jointly based on the first projected oriented area, the second projected oriented area, the directional consistency, the degree of closure, and the number of times the frequency zero line crosses; the structural strength in the common coupling point double-projection unidirectional loop feature is determined jointly based on the area balance and the degree of closure, wherein the area balance is used to characterize the degree of balance between the first projected oriented area and the second projected oriented area.

6. The multi-energy complementary energy storage method based on a smart grid according to claim 1, characterized in that, The dynamic dead zone processing, reverse holding processing, and slope shaping processing of the basic target power based on the structural strength include: The dynamic dead zone is increased based on the structural strength, the reverse holding time is determined based on the structural strength, and the shaping ramp rate is decreased based on the structural strength. When the basic target power is to switch the charging and discharging direction in reverse relative to the command power of the previous cycle, the command power of the previous cycle is first transitioned to zero power during the reverse holding time, and then the command power is formed according to the shaping ramp rate.

7. A multi-energy complementary energy storage method based on a smart grid according to claim 6, characterized in that, The grid connection safety verification includes verifying the grid connection point switching power, the common coupling point voltage operating status characterized by the effective voltage value, the grid frequency, line capacity, transformer capacity, converter capacity, and equipment protection status. When the grid connection safety verification fails, the reverse hold process is canceled, and the command power that satisfies the grid connection safety constraints is formed by proportionally reducing the command power.

8. A multi-energy complementary energy storage method based on a smart grid according to claim 1, characterized in that, The multi-energy storage unit includes at least one of electrochemical energy storage, thermal storage device, hydrogen production device, hydrogen storage device, and fuel cell; the energy management system determines the available charging power and available discharging power of the multi-energy storage unit based on the state of charge, thermal storage state, hydrogen storage state, temperature, alarm status, and rated power, and allocates the command power as device-level command power according to a fixed priority, and the device control unit controls the operation of the multi-energy storage unit according to the device-level command power.

9. A multi-energy complementary energy storage system based on a smart grid, characterized in that, It includes an AC common coupling point bus, renewable energy generation units, load units, multi-energy storage units, common coupling point measurement units, energy management systems, and equipment control units; The renewable energy generation unit, the load unit, and the multi-energy storage unit are all connected to the AC common coupling point bus. The common coupling point measurement unit is used to obtain three-phase voltage sampling, three-phase current sampling, and grid frequency; The energy management system is used to obtain the total power of renewable energy and the total power of the load, establish a synchronous observation window for the common coupling point, obtain frequency deviation, dimensionless active power and voltage deviation based on the three-phase voltage sampling, three-phase current sampling and grid frequency, determine the characteristics of the common coupling point double projection unidirectional loop composed of structural presence mark and structural strength through double projection processing, form the basic target power, perform dynamic dead zone processing, reverse holding processing and ramp shaping processing according to the structural strength, and output command power to the equipment control unit; The structure presence marker is used to characterize the existence of the common coupling point double-projection unidirectional foldback ring structure, and the structural strength is determined by the area balance and the degree of closure; the equipment control unit is used to control the multi-energy storage unit to charge, discharge or convert energy according to the command power.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, the processor performs a multi-energy complementary energy storage method based on a smart grid as described in any one of claims 1 to 8.

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