A dynamic load monitoring method and device for a flexible power distribution network and a storage medium

Abstract

The application relates to the technical field of flexible power distribution networks, and discloses a dynamic load monitoring method and device of a flexible power distribution network and a storage medium. The method collects voltage and current data of an alternating current power grid power distribution network, extracts a plurality of continuous data in a set detection time length, calculates a voltage fluctuation trend according to the voltage data, obtains a first calculation value in combination with a set voltage reference trend, and obtains a second calculation value according to current data. The absolute value of the first calculation value and the second calculation value is used to calculate a comprehensive absolute value, and according to different reference ranges of the comprehensive absolute value, the energy storage or power quality treatment mode of a direct current power distribution module is activated respectively, the direct current power distribution module is connected to the power distribution network to realize alternating current and direct current collaborative power supply, and when the energy storage capacity of the direct current power distribution module is sufficient, the alternating current power grid is cut out to realize single power supply. The method can adapt to dynamic load working conditions and improve the stability of power supply of the power distribution network.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flexible power distribution networks, in particular to a dynamic load monitoring method, device and storage medium for a flexible power distribution network. BACKGROUND

[0002] At present, solar energy and battery energy storage technology has entered the mature application stage and has been widely popularized in a wide range. Solar photovoltaic panels are widely used in residential rooftops, industrial and commercial parks and large ground power stations due to their high photoelectric conversion efficiency. Chemical energy storage batteries play an important role in distributed energy storage, standby power supply and other scenarios due to their stable charging and discharging performance. Both are important components of renewable energy.

[0003] The output power of the solar power generation system and the output power of the battery energy storage are both direct current. When they are directly connected to the public power grid which mainly uses alternating current, a series of power quality problems will be caused. There are essential differences in waveform characteristics, frequency and phase between direct current and alternating current. Harmonic pollution, voltage fluctuation and frequency deviation may occur during the process of connecting to the grid, which leads to the decline of the stability of the power grid. Therefore, most direct current power systems currently need to be used separately through independent lines or special equipment.

[0004] In the prior art, the switching between direct current and alternating current usually depends on fixed conditions set by the user in advance, such as time threshold and the like. This static control mode cannot adapt to the dynamic load conditions. When the power load suddenly increases or decreases, the fixed switching logic may cause power supply interruption, voltage sudden change and the like. Especially at the end of the power grid, such as remote areas and distributed microgrids, due to large line loss and more frequent load fluctuation, the stability, reliability and power supply quality of the power are still obviously short, and it is urgent to improve them through a more intelligent scheduling mode. SUMMARY

[0005] In order to adapt to the dynamic load conditions, the present application provides a dynamic load monitoring method, device and storage medium for a flexible power distribution network.

[0006] In the first aspect, the present application provides a dynamic load monitoring method for a flexible power distribution network, which adopts the following technical scheme:

[0007] A dynamic load monitoring method for a flexible power distribution network, comprising the following steps:

[0008] Collecting voltage data and current data of the power distribution network supplied by the alternating current power grid;

[0009] In a set detection time, extracting a plurality of and continuous voltage data and current data;

[0010] According to the voltage data, a voltage fluctuation trend is calculated, and according to the voltage fluctuation trend and a set voltage reference trend, a first calculation value is calculated;

[0011] According to the current data, a current fluctuation trend is calculated, and according to the current fluctuation trend and a set current reference trend, a second calculation value is calculated;

[0012] According to absolute values of the first calculation value and the second calculation value, a comprehensive absolute value is calculated;

[0013] If the comprehensive absolute value is located in a set first reference range, a direct current power distribution module is activated, and the direct current power distribution module is in an energy storage mode or a power quality treatment mode;

[0014] If the comprehensive absolute value is located in a set second reference range, the direct current power distribution module is connected to a power distribution network, the power distribution network is powered by an alternating current power grid and the direct current power distribution module, and the direct current power distribution module is in a power supply mode or a power quality treatment mode;

[0015] If the comprehensive absolute value is located in a set third reference range, and an energy storage capacity of the direct current power distribution module is greater than a set reference capacity, the alternating current power grid is cut out of the power distribution network, the power distribution network is powered by the direct current power distribution module, and the direct current power distribution module is in the power supply mode.

[0016] The value in the first reference range is less than the value in the second reference range, and the value in the second reference range is less than the value in the third reference range.

[0017] By using the above technical solution, by collecting voltage and current data of the power distribution network in real time, analyzing the fluctuation trend and calculating the comprehensive absolute value, and according to different reference ranges of the comprehensive absolute value, different working modes of the direct current power distribution module and the coordinated power supply mode with the alternating current power grid are dynamically activated, which can adapt to dynamically changing load conditions.

[0018] Optionally, the step of calculating the voltage fluctuation trend according to the voltage data and calculating the first calculation value according to the voltage fluctuation trend and the set voltage reference trend further includes the following sub-steps:

[0019] The voltage data is filtered by a sliding filtering algorithm, and then voltage average data is calculated;

[0020] The difference between each voltage data and the voltage average data is calculated as a voltage fluctuation difference;

[0021] A voltage fluctuation straight line is fitted according to each voltage fluctuation difference;

[0022] calculate a latest voltage fluctuation trend based on the voltage fluctuation straight line;

[0023] The voltage reference trend is set as a ratio of a set power reference value to a set voltage.

[0024] The voltage fluctuation trend is divided by the voltage reference trend to obtain a first calculation value.

[0025] By adopting the above technical solution, the voltage data is processed by a sliding filter algorithm and average data is calculated, a fluctuation straight line is fitted by combining the fluctuation difference value to obtain a latest voltage fluctuation trend, and the voltage reference trend is set as a ratio of a power reference value to a voltage, and a first calculation value is obtained by the ratio of the two, which can more accurately quantify the voltage fluctuation characteristics and improve the accuracy of voltage fluctuation trend analysis.

[0026] Optionally, the step of calculating a current fluctuation trend according to the current data and calculating a second calculation value according to the current fluctuation trend and a set current reference trend comprises the following sub-steps:

[0027] The current data is filtered by a weighted average algorithm, and the closer the time point is, the greater the weight of the corresponding current data is; and then current average data is calculated;

[0028] The difference between each current data and the current average data is calculated as a current fluctuation difference value;

[0029] A current fluctuation curve is fitted according to each current fluctuation difference value;

[0030] A latest current fluctuation trend is calculated based on the current fluctuation curve;

[0031] The current reference trend is set as a ratio of a set power reference value to a set current.

[0032] The current fluctuation trend is divided by the current reference trend to obtain a second calculation value.

[0033] By adopting the above technical solution, the current data is filtered by a time weighted average, giving recent data a higher weight to enhance the timeliness, a latest current fluctuation trend is obtained by fitting a curve according to the fluctuation difference value, and the current reference trend is set as a ratio of a power reference value to a current, and a second calculation value is obtained by the ratio of the two, which can more sensitively capture the dynamic change characteristics of the current and improve the timeliness and accuracy of current fluctuation trend analysis.

[0034] Optionally, the method further comprises the following steps:

[0035] The detection time length is adjusted according to the comprehensive absolute value, that is, the greater the comprehensive absolute value, the longer the detection time length, and the smaller the comprehensive absolute value, the shorter the detection time length.

[0036] By adopting the above technical solution, when the power distribution network fluctuates sharply, the detection time length is extended to obtain more comprehensive data to accurately determine the trend, and when the fluctuation is gentle, the detection time length is shortened to improve the response speed.

[0037] Optionally, the step of supplying power to the direct current power distribution module further comprises the following steps:

[0038] The alternating current power grid is controlled to supply power to the energy storage unit in the direct current power distribution module at a first power;

[0039] The solar power of the solar unit in the direct current power distribution module is obtained, and if the solar power is greater than a set predetermined power, the solar unit is controlled to supply power to the energy storage unit at a second power;

[0040] The first power is adjusted according to the comprehensive absolute value in a reverse correlation manner;

[0041] The second power is adjusted according to the ratio of the solar power to the predetermined power in a positive correlation manner.

[0042] By adopting the above technical solution, when the power distribution network fluctuates sharply, the power supply power of the power grid is reduced, and the dependence on the unstable power grid is reduced; when the fluctuation is gentle, the power supply power of the power grid is increased, and the stability of the power grid is fully utilized, so that the efficiency of the energy storage is ensured, and the power supply pressure of the power grid during the fluctuation period is reduced. By obtaining the real-time power of the solar unit, solar power supply is started only when the real-time power is greater than the set predetermined power, and the second power is adjusted according to the ratio of the solar power to the predetermined power in a positive correlation manner, so that clean energy is maximized when the solar resource is sufficient, the renewable energy consumption rate is improved, and the power supply scale is reasonably controlled when the resource is limited to avoid energy waste.

[0043] Optionally, the step of supplying power to the direct current power distribution module further comprises the following steps:

[0044] The alternating current power grid and the direct current power distribution module are connected by using a power router;

[0045] The direct current power distribution module is connected to multiple alternating current power grids through the power router;

[0046] The multiple alternating current power grids are interlocked, and the power router does not supply power to multiple alternating current power grids at the same time;

[0047] When the power router supplies power to a single alternating current power grid, the power router is in a power supply mode or a power quality management mode.

[0048] When multiple alternating current power grids are connected, the power router is in an electric energy quality management mode.

[0049] By adopting the technical solutions described above, flexible connection of alternating current power grids and direct current power distribution modules and orderly management of multiple alternating current power grids can be achieved, power supply conflicts can be avoided, electric energy quality can be effectively managed through operation of the power router in different modes, and stability and reliability of common power supply of the power distribution grid can be improved.

[0050] Optionally, the step of the power distribution grid being commonly powered by the direct current power distribution module further includes the following steps:

[0051] Real-time acquisition of residual electric energy and output power in the energy storage unit in the direct current power distribution module;

[0052] Calculation of output time according to the residual electric energy and the output power;

[0053] If the output time is shorter than the set minimum time, the alternating current power grid is powered alone for the power distribution grid, and the direct current power distribution module is cut out of the power distribution grid.

[0054] By adopting the technical solutions described above, real-time acquisition of residual electric energy and output power in the energy storage unit in the direct current power distribution module and calculation of output time, timely switching of the alternating current power grid for single power supply and cutting out of the direct current power distribution module when the output time is shorter than the set minimum time, can effectively avoid power supply interruption problems caused by insufficient electric energy of the energy storage unit in the direct current power distribution module.

[0055] Optionally, the step of calculating the comprehensive absolute value according to the absolute value of the first calculation value and the absolute value of the second calculation value further includes the following steps:

[0056] The absolute value of the first calculation value and the absolute value of the second calculation value are calculated into a comprehensive absolute value by using a weighted average algorithm;

[0057] The first weight value of the absolute value of the first calculation value is adjusted according to the voltage stability demand level of the power distribution grid, and the higher the voltage stability demand level, the greater the first weight value;

[0058] The second weight value of the absolute value of the second calculation value is adjusted according to the current stability demand level of the power distribution grid, and the higher the current stability demand level, the greater the second weight value.

[0059] By adopting the above technical solutions, the weighted average algorithm is adopted to calculate the comprehensive absolute value, and the first and second weights are adjusted according to the voltage and current stability requirement level of the power distribution network, the first weight is increased when the voltage stability requirement is higher, and the second weight is increased when the current stability requirement is higher. In this way, the calculation of the comprehensive absolute value is more in line with the actual operation requirements of the power distribution network, which highlights the weight of the key parameters in the scheduling decision and realizes differentiated consideration of the influence of voltage and current fluctuations.

[0060] In a second aspect, the application provides a dynamic load monitoring device for a flexible power distribution network, which adopts the following technical solutions:

[0061] A dynamic load monitoring device for a flexible power distribution network, comprising a processor, wherein the processor executes the steps of the dynamic load monitoring method for a flexible power distribution network according to any one of the above.

[0062] In a third aspect, the application provides a storage medium, which adopts the following technical solutions:

[0063] A storage medium, wherein the storage medium stores a program, and the program is executed by a processor to implement the steps of the dynamic load monitoring method for a flexible power distribution network according to any one of the above.

[0064] In summary, the application includes at least one of the following beneficial technical effects: by accurately quantifying the voltage and current fluctuation trend and dynamically adjusting the weight, the scheduling decision is more in line with the actual operation requirements of the power distribution network, and the self-adaptability to dynamic load conditions is improved; by flexibly adjusting the detection time, power supply power and multi-energy collaborative power supply mechanism, while ensuring power supply stability, renewable energy such as solar energy is maximized, and energy utilization efficiency is improved; with the help of the power router, the multi-grid orderly management and power quality management in different modes are realized, combined with the energy storage unit power warning mechanism in the direct current power distribution module, the power supply conflict and interruption problem is effectively avoided, and the reliability, stability and flexible adjustment capability of the power distribution network are significantly enhanced. BRIEF DESCRIPTION OF DRAWINGS

[0065] Figure 1 is a step diagram of a dynamic load monitoring method for a flexible power distribution network.

[0066] Figure 2 is a step diagram of calculating the first calculation value.

[0067] Figure 3 is a step diagram of calculating the second calculation value.

[0068] Figure 4 is a circuit topology diagram of an AC-DC hybrid power distribution network or a multi-terminal flexible interconnected power distribution system. DETAILED DESCRIPTION

[0069] Embodiments of the present application are described below in the detailed description and illustrated in the accompanying drawings.

[0070] In the description of the present specification, the description referring to the terms "certain embodiments", "one embodiment", "some embodiments", "illustrative embodiments", "example", "specific example" or "some examples" means that the particular feature, structure, material or characteristic being described in connection with the embodiment or example is included in at least one embodiment or example of the present application. The illustrative representations of the above terms in the present specification do not necessarily refer to the same embodiment or example. Moreover, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0071] The embodiments of the present application disclose a dynamic load monitoring method of a flexible power distribution network, referring to Figure 1 , comprising the following steps:

[0072] Collecting voltage data and current data of the power distribution network powered by the alternating current power grid; collecting the voltage data and the current data in real time when the alternating current power grid powers the power distribution network through the voltage sensor and the current sensor deployed at the key nodes of the power distribution network. The sampling frequency of the voltage sensor is set to 50 Hz, and the instantaneous value of each phase voltage can be accurately obtained, with the unit being V; the sampling frequency of the current sensor is set to 50 Hz, and the instantaneous value of the current of the corresponding line is collected synchronously, with the unit being A. The collected data is transmitted to the database of the dispatching control center through the industrial Ethernet.

[0073] Extracting a plurality of and continuous voltage data and current data in a set detection duration; setting the initial detection duration to 10 seconds, and extracting 100 continuous voltage data and 100 continuous current data from the database in the duration, because the sampling frequency is 50 Hz, 10 seconds can collect 500 data, and 100 continuous data are selected here to balance the calculation amount and the accuracy.

[0074] Referring to Figure 2, the voltage fluctuation trend is calculated according to the voltage data, and a first calculation value is calculated according to the voltage fluctuation trend and a set voltage reference trend. The extracted 100 voltage data are filtered by using a sliding filter algorithm: the sliding window size is set to 5, that is, the filtered value of each data point is the average value of itself and the two data points before and after it, so as to eliminate high-frequency noise interference. The arithmetic average value of the 100 filtered voltage data is calculated to obtain voltage average data Uavg. The difference between each voltage data Ui and Uavg, that is, the voltage fluctuation difference ΔUi = Ui-Uavg, is calculated. The 100 ΔUi are linearly fitted by using the least square method to obtain a voltage fluctuation straight line ΔU = k1xt+b1, wherein t is a time sequence, k1 is a slope, and the slope k1 of the straight line is the latest voltage fluctuation trend. The voltage reference trend is set: the ratio of the rated power reference value Pref (such as 100 kW) of the power distribution network to the rated voltage Uref (such as 220 V) is taken, that is, the voltage reference trend Kv = Pref / Uref≈454.55A. The first calculation value S1 = voltage fluctuation trend k1 / voltage reference trend Kv is used to quantify the deviation of the voltage fluctuation from the reference benchmark.

[0075] With reference to Figure 3 , the current fluctuation trend is calculated according to the current data, and a second calculation value is calculated according to the current fluctuation trend and a set current reference trend. The extracted 100 current data are filtered by using a weighted average algorithm: the data closer in time are given higher weights, such as the weight of the 100th data (the latest data) is 0.02, the weight of the 99th data is 0.0198, and the weights decrease in turn, and the total sum of the weights is 1, so as to enhance the sensitivity to the recent current change. The weighted average value of the 100 weighted filtered current data is calculated to obtain current average data Iavg. The difference between each current data Ii and Iavg, that is, the current fluctuation difference ΔIi = Ii-Iavg, is calculated. The 100 ΔIi are curve-fitted by using a polynomial fitting (such as a quadratic polynomial) to obtain a current fluctuation curve ΔI = at2+bt+c, and the latest current fluctuation trend k2 is obtained by calculating the derivative of the curve at the latest time point, that is, the tangent slope. The current reference trend is set: the ratio of the rated power reference value Pref (100 kW) to the rated current Iref is taken, such as 454.55 A, which is calculated from Pref = UrefxIref, that is, the current reference trend Ki = Pref / Iref = 220 V. The second calculation value S2 = current fluctuation trend k2 / current reference trend Ki is used to quantify the deviation of the current fluctuation from the reference benchmark.

[0076] The comprehensive absolute value S is calculated using a weighted average algorithm based on the absolute values ​​of the first and second calculated values. This comprehensive absolute value reflects the overall fluctuation of voltage and current. The formula is: S = w1 × |S1| + w2 × |S2|, where w1 is the weight of the absolute value of the first calculated value, w2 is the weight of the absolute value of the second calculated value, and w1 + w2 = 1. The weight adjustment rules are as follows: w1 is adjusted according to the voltage stability requirement level of the distribution network; the higher the requirement level, such as in scenarios with precision instrument loads, the larger w1 should be, with a value of 0.6-0.8. Similarly, w2 is adjusted according to the current stability requirement level; the higher the requirement level, such as in scenarios with motor loads, the larger w2 should be, with a value of 0.6-0.8.

[0077] If the overall absolute value is within the set first reference range, the DC distribution module is activated, and power is supplied to the DC distribution module through the AC grid. The DC distribution module is in energy storage mode or power quality management mode. The first reference range is set to [0, 0.5). When S∈[0, 0.5), it indicates that the voltage and current fluctuations of the distribution network are small, and the AC grid power supply is stable. At this time, the DC distribution module is activated, and power is supplied to it from the AC grid.

[0078] If the energy storage unit of the DC power distribution module is below 80% of its rated capacity, it enters energy storage mode, converting AC power into DC power and storing it in the energy storage unit, such as a lithium battery pack.

[0079] If slight harmonics or voltage deviations are detected in the distribution network, the power quality management mode is activated simultaneously to suppress harmonics and stabilize the voltage through the active filter within the module.

[0080] If the overall absolute value is within the set second reference range, the DC distribution module is connected to the distribution network. The distribution network is jointly powered by the AC grid and the DC distribution module, and the DC distribution module is in either power supply mode or power quality management mode. The second reference range is set to [0.5, 1.0). When S∈[0.5, 1.0), it indicates that the distribution network fluctuation is moderate and the AC grid's power supply capacity is reduced. At this time, the DC distribution module is connected to the distribution network to provide power in coordination with the AC grid.

[0081] The DC power distribution module enters the power supply mode and converts the DC power of the energy storage unit into AC power through the inverter to supplement the power supply gap of the AC power grid, for example, to handle 20%-50% of the load power.

[0082] If the harmonic distortion rate is detected to exceed 5% or the voltage fluctuation exceeds ±5%, the power quality management mode will be activated simultaneously to improve power quality through dynamic reactive power compensation and other means.

[0083] If the integrated absolute value is within a set third reference range and the energy storage capacity of the DC power distribution module is greater than a set reference capacity, the AC power grid is cut out of the power distribution grid, the power distribution grid is powered by the DC power distribution module, and the DC power distribution module is in a power supply mode. The third reference range is set to [1.0, +∞), and the reference capacity is 50% of the rated capacity. When S≥1.0 and the energy storage capacity≥50%, it indicates that the power distribution grid fluctuates violently, and there may be a risk of failure in the AC power grid. At this time, the AC power grid is cut out of the power distribution grid by the circuit breaker, and the DC power distribution module is powered alone:

[0084] The DC power distribution module enters the full-load power supply mode, inverts the DC power of the energy storage unit into AC power meeting the requirements of the power distribution grid, and ensures continuous power supply for the load;

[0085] At the same time, the state of the AC power grid is continuously monitored, and when it returns to stability, i.e., S<0.5 and the fluctuation lasts for more than 30 seconds, the AC power grid is reconnected.

[0086] Through the above technical solution, the working mode of the DC power distribution module and the coordination mode with the AC power grid can be dynamically adjusted according to the real-time fluctuation state of the power distribution grid and the differentiated demand for voltage and current stability of the actual load, precise adaptive scheduling of dynamic load working conditions is realized, and the power supply stability, reliability and power quality of the power distribution grid are significantly improved.

[0087] By dynamically adjusting the detection time, the data integrity is ensured when the power distribution grid fluctuates violently, and the response speed is improved when the fluctuation is smooth. The specific method includes the following steps:

[0088] The initial detection time is set to 10 seconds as a reference value, and the adjustment of the detection time T is positively correlated with the integrated absolute value S, and the specific rules are as follows:

[0089] When S<0.3, the fluctuation is extremely smooth, and the detection time is shortened to 5 seconds;

[0090] When 0.3≤S<0.7, the fluctuation is moderate, and the detection time remains 10 seconds;

[0091] When 0.7≤S<1.0, the fluctuation is relatively violent, and the detection time is extended to 15 seconds;

[0092] When S≥1.0, the fluctuation is violent, and the detection time is extended to 20 seconds.

[0093] Among them, the adjustment range is positively correlated with the change range of S, for example, when S increases from 0.2 to 0.8, the detection time increases linearly from 5 seconds to 15 seconds.

[0094] The scheduling system reads the current S value and matches the corresponding detection time immediately after each S value calculation is completed.

[0095] If S = 0.25 < 0.3 in a calculation, the detection duration of the next round of data collection is automatically adjusted to 5 seconds, only the last 50 continuous voltage / current data are extracted, and the sampling frequency is 50 Hz. 5 seconds correspond to 250 data, and the last 50 data are taken to ensure continuity;

[0096] If S = 0.8 ∈ [0.7, 1.0), the detection duration is adjusted to 15 seconds, and the last 150 continuous data are extracted.

[0097] The adjusted detection duration is maintained until the next S value calculation is completed. If the new S value falls into other intervals, it is re-adjusted according to the new rules.

[0098] When S decreases from 1.1 to 0.6, the detection duration gradually decreases from 20 seconds to 10 seconds, avoiding data collection confusion caused by frequent switching.

[0099] Through the above dynamic adjustment, when the power distribution network fluctuates violently, the detection duration is extended to accumulate more data samples, making the fluctuation trend analysis more stable; when the fluctuation is gentle, the detection duration is shortened to speed up the data update frequency, making the dispatching decision respond to subtle changes faster, thereby achieving an optimal balance between data integrity and decision timeliness.

[0100] The step of supplying power to the direct current power distribution module further includes the following steps:

[0101] The alternating current power grid supplies power to the energy storage unit in the direct current power distribution module at a first power; the alternating current power grid transmits power to the energy storage unit in the direct current power distribution module through an AC / DC converter; the energy storage unit, such as a lithium iron phosphate battery pack, has a rated capacity of 50 kWh, and the initial first power P1 is set to 10 kW. During the power supply process, the converter monitors the output current and voltage in real time to ensure that the power is stable within the set value ± 5%. For example, when it is detected that the output power deviates from P1 by more than 5%, the PID adjustment algorithm is used to dynamically correct the firing angle to quickly return the power to the set value.

[0102] The solar power of the solar unit in the direct current power distribution module is obtained, and if the solar power is greater than a predetermined power, the solar unit supplies power to the energy storage unit at a second power. The solar unit in the direct current power distribution module is equipped with a power sensor, and the solar unit is composed of multiple monocrystalline silicon photovoltaic panels, with a maximum output power of 15 kW. Real-time solar power Ps is collected every 100 ms. The predetermined power P0 is set to 5 kW, which is the minimum threshold of available solar resources. If Ps > P0, the DC / DC converter of the solar unit is activated to allow it to supply power to the energy storage unit; if Ps ≤ P0, the converter is turned off to prevent the solar unit from running in an inefficient state.

[0103] The first power is adjusted according to the comprehensive absolute value inverse correlation regulation; the adjustment of the first power P1 is inversely correlated with the comprehensive absolute value S, and the adjustment formula is: P1=P1base×(1-k×S); wherein, P1base is a reference power 10kW, and k is an adjustment coefficient, and the value is 0.5.

[0104] For example: when S=0.2 (gentle fluctuation), P1=10×(1-0.5×0.2)=9kW, the power supply of the power grid is increased to utilize its stability;

[0105] When S=0.8 (more severe fluctuation), P1=10×(1-0.5×0.8)=6kW, the power supply of the power grid is reduced to reduce the dependence on the unstable power grid;

[0106] When S≥1.0, the lower limit of P1 is set to 3kW to ensure the basic charging demand of the energy storage unit.

[0107] The second power is adjusted according to the ratio of solar power to predetermined power positive correlation; the adjustment of the second power P2 of the solar unit is positively correlated with the ratio K, wherein K=Ps / P0; the adjustment formula is: P2=min(Ps, P2max)×K; wherein, P2max is the maximum allowable power supply of the solar unit, such as 10kW, to avoid overload.

[0108] For example: when Ps=6kW (K=1.2), P2=6×1.2=7.2kW, which does not exceed P2max, and is calculated according to the calculated value;

[0109] When Ps=12kW (K=2.4), P2=min(12, 10)×2.4=10×2.4=24kW, which exceeds P2max, and is calculated according to the upper limit of 10kW to get 24kW;

[0110] When Ps=5.5kW (K=1.1), P2=5.5×1.1=6.05kW, which realizes reasonable power supply when resources are limited.

[0111] The total charging power Ptotal of the energy storage unit is P1+P2, and needs to meet Ptotal≤the maximum allowable charging power of the energy storage unit, such as 20kW. If P1+P2>20kW, P1 is reduced first (proportionally reduced), for example, when P1=9kW and P2=12kW, the total power 21kW exceeds the upper limit, P1 is reduced to 8kW, and Ptotal=20kW, to ensure safe charging of the energy storage unit.

[0112] Through the above steps, the power supply pressure of the power grid can be reduced when the power grid fluctuates violently, and the clean energy can be maximized when the solar energy resources are sufficient, realizing the flexibility and efficiency of multi-energy collaborative power supply.

[0113] The step of the power distribution network being powered by the AC power grid and the DC power distribution module together further comprises the following steps:

[0114] The power router with AC / DC conversion and routing functions is adopted, such as an intelligent interconnected device based on power electronic conversion technology, the AC side interface of which is connected to the main AC power grid, 10kV / 380V; and the DC side interface is connected to the DC power distribution module, ±375V DC bus.

[0115] The DC power distribution module is connected to the standby AC power grid through the expansion interface of the power router, forming a multi-grid access architecture of "1 main + 2 standby". Each AC access link is configured with an independent intelligent circuit breaker with a breaking time ≤50ms, which is used for link on-off control and fault isolation.

[0116] The interlocking logic is implanted in the control system of the power router: when any one of the AC power grids, such as the main power grid, supplies power to the DC power distribution module through the power router, the access circuit breakers of the remaining AC power grids (standby 1 and standby 2) are forced to be in the open state; if it is necessary to switch the power grid, the current link circuit breaker needs to be disconnected first, and then the target link circuit breaker is closed after confirming that there is no current, and the switching time is ≤100ms. For example, when the main power grid supplies power, the circuit breakers of standby 1 and standby 2 are opened to avoid voltage difference conflicts or circulating current risks caused by parallel power supply of multiple power grids.

[0117] When the power router only supplies power for a single AC power grid (such as the main power grid), the operation mode is automatically switched according to the state of the power distribution network:

[0118] Power supply mode: if the voltage deviation of the power distribution network is ≤±2% and the harmonic distortion rate is ≤3%, the router operates in power priority mode, the DC side output voltage is controlled to be stable at ±375V±1% through the PID regulation algorithm, which meets the power supply requirements of the DC power distribution module, such as charging the energy storage unit or supplying power to the DC load, at this time, the power transmission efficiency is prior to the power quality regulation.

[0119] Power quality management mode: if the AC side voltage fluctuation is detected to be >±5% or the harmonic distortion rate is >5%, the router automatically activates the management function, compensates the harmonic current through the built-in active power filter APF, the compensation rate is ≥95%, and dynamically adjusts the reactive power through the static var generator (SVG), the response time is ≤20ms, so that the AC side power quality index returns to the qualified range, and then switches back to the power supply mode.

[0120] When performing grid switching operation, such as connecting to standby power grid due to main power grid failure, the transition circuit breaker of two AC power grids needs to be closed for a short time to form a temporary connection of multiple power grids. At this time, the power router is forced to lock in the power quality treatment mode: suspend power transmission function, and only start voltage sag compensation, frequency deviation correction and other treatment modules until the grid switching is completed and the transition circuit breaker is disconnected. Then, according to the single power grid power supply state, it is switched to the corresponding mode. For example, when the main power grid is temporarily connected with the standby 1 power grid, the router preferentially compensates for the voltage difference of both sides ≤5V to avoid impact current during switching process.

[0121] Through the above steps, the power router not only realizes flexible networking of multiple AC power grids and DC power distribution modules, but also prevents power supply conflicts through interlocking mechanism. At the same time, it dynamically switches the operation mode according to the grid state, ensuring power transmission while accurately treating power quality problems.

[0122] In the step of power distribution grid being powered by DC power distribution modules, the following steps are further included:

[0123] The energy storage unit of the DC power distribution module, such as a lithium battery pack with a capacity of 100kWh, is equipped with an electric quantity sensor and a power transmitter to collect real-time residual energy SOC and output power Pout. Among them, SOC is obtained by integrating current and open circuit voltage calibration through battery management system BMS, with a measurement accuracy of ±2%; Pout is collected by a Hall sensor with a sampling frequency of 1kHz, and data is uploaded to the dispatching system every 100ms. For example, at a certain moment, it is monitored that SOC=30%, i.e. residual energy 30kWh, Pout=15kW.

[0124] The calculation formula of output time T is: T=(SOC×E_rated) / Pout; where E_rated is the rated capacity of the energy storage unit (100kWh). Taking the above data as an example, T=(30%×100kWh) / 15kW=2 hours, i.e. the energy storage can maintain power supply for 2 hours under the current output power. If Pout changes dynamically, such as increasing to 20kW, then T is updated in real time to 30kWh / 20kW=1.5 hours, ensuring the timeliness of time calculation.

[0125] According to the continuous power supply demand of important loads of the power distribution grid, the minimum time threshold T_min=1 hour is set, which can be adjusted according to the load level, such as 2 hours for key scenarios such as hospitals. When the real-time calculated T is less than T_min, the power supply switching mechanism is triggered: the dispatching system sends opening and closing commands to the main circuit breaker (AC side) of the power distribution grid and the outlet circuit breaker of the DC power distribution module, among which the DC side circuit breaker is opened first with a disconnection time of ≤50ms, and the AC side circuit breaker is closed later with a closing time of ≤100ms, realizing uninterrupted switching. For example, when T decreases to 0.8 hours, which is less than 1 hour, the switching operation is immediately performed.

[0126] After the DC power distribution module is cut off, it automatically enters standby mode: stop outputting power to the power distribution network, start internal self-checking, such as battery cell voltage uniformity, cooling system state, while maintaining communication with the dispatching system, real-time uploading of SOC and fault information. If the subsequent SOC rises above 80% and the power distribution network demand allows, it can be reconnected to the power distribution network through remote instructions; if battery failure is detected, such as single cell voltage deviation > 5%, an alarm is issued and locked until manual maintenance is completed.

[0127] Through the above steps, real-time monitoring and dynamic calculation ensure accurate prediction of the power supply capacity of the energy storage unit in the DC power distribution module, and the threshold triggering mechanism and fast switching logic quickly switch to the AC power grid when the energy storage is insufficient, fundamentally avoiding power supply interruption due to depleted energy storage, while the state management after cutting off ensures the safety of the DC power distribution module.

[0128] Reference Figure 4 The circuit topology of the AC-DC hybrid power distribution network or multi-terminal flexible interconnected power distribution system is to realize the energy interaction between AC1, AC2 and DC, as well as the flexible interconnection between AC power grids and power quality management.

[0129] AC side:

[0130] C1, AC2: represents two independent AC power sources, such as different substations, distributed power sources, which can provide power for the power distribution network, and can also be backup or cooperative power supply for each other.

[0131] The bus tie switch can be closed to realize AC1, AC2 parallel power supply, enhance system redundancy; when fault occurs, it can be opened to isolate and avoid fault propagation, and ensure independent operation of single-sided power grid.

[0132] Core power conversion unit in dashed box:

[0133] The dashed box is the key module to realize AC-DC conversion and power regulation, including:

[0134] SIT, series transformer / inductor:

[0135] Series connected to the AC line, used to adjust the line voltage, current phase, realize reactive power compensation, power flow control, such as compensating for the lack of reactive power on the AC side, optimizing power quality; it can also flexibly regulate the power distribution between AC1 and AC2.

[0136] In cooperation with the back-end power module, it realizes the energy interaction between AC and DC sides, and plays the role of electrical isolation and voltage matching.

[0137] Access switch: two-way access switch controls the on-off of AC1, AC2 and power conversion unit, used for switching control, such as maintenance, fault isolation, to ensure flexible networking and safe operation of the system.

[0138] PCM, power conversion module, containing power electronic devices:

[0139] Usually is a rectifier / inverter device, such as IGBT composed of inverter, connected to the DC side DC, can rectify AC side power to DC, charge or power supply, or convert DC side power to AC to feed into the grid, such as DC side energy storage, new energy power generation access.

[0140] With fast power regulation capability, responding to power demand and voltage fluctuation of the grid, dynamically compensating active / reactive power.

[0141] SCM, synchronous control module / auxiliary power module:

[0142] Auxiliary PCM works together to fine-tune power flow, such as cooperating with PCM to achieve DC side voltage stability and AC side power quality optimization, and to suppress harmonics and voltage sag.

[0143] Can participate in system synchronous control to ensure frequency and phase matching during AC side and DC side power interaction.

[0144] CRM, control and protection module:

[0145] Collect real-time parameters such as voltage, current, power, etc., based on preset strategies such as voltage limit and overcurrent protection, control PCM and SCM power conversion behavior to ensure device and system safety.

[0146] Realize fault diagnosis and protection action, such as quickly cutting off power module when overcurrent occurs, isolating faults, and communicating with upper-level dispatching, uploading status and receiving control instructions.

[0147] DC side:

[0148] Represents the DC bus / DC power supply area, can access DC load (such as data center, electric vehicle charging pile), DC energy storage (battery, super capacitor), DC new energy (photovoltaic, wind power after rectification).

[0149] Through PCM and SCM, interact with AC side to realize AC / DC hybrid power supply, improve the ability of power distribution network to absorb multiple energy sources and power supply flexibility.

[0150] The AC power grid is fused with the DC side energy (energy storage, new energy), realizing bidirectional flow of electric energy, coping with distributed energy access, multi-element load demand, such as AC fault, the DC side continuously supplies power through inversion. With the regulation and control ability of SIT, PCM and SCM, reactive power compensation, harmonic suppression, voltage sag governance, improvement of AC side power quality, adaptation to sensitive load of power quality, such as precision manufacturing and electronic equipment. Replacing traditional hard connection, through power electronic module flexible regulation and control of power between AC1 and AC2, solving the problem of large switching impact of traditional bus tie switch and difficult power flow regulation, suitable for urban distribution network partition interconnection and different voltage level power grid cooperation.

[0151] The embodiment of the present application also discloses a dynamic load monitoring device of a flexible power distribution network, comprising a processor, wherein the steps of the dynamic load monitoring method of the flexible power distribution network according to any one of the above are executed in the processor.

[0152] The embodiment of the present application also discloses a storage medium, wherein a program is stored in the storage medium, and the program is executed by a processor to realize the steps of the dynamic load monitoring method of the flexible power distribution network according to any one of the above.

[0153] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A method for dynamic load monitoring of a flexible power distribution network, characterized in that, The method comprises the following steps: Collecting voltage data and current data of an alternating current power supply distribution network; Extracting a plurality of and continuous voltage data and current data within a set detection time; Calculating a voltage fluctuation trend according to the voltage data, and calculating a first calculation value according to the voltage fluctuation trend and a set voltage reference trend; Calculating a current fluctuation trend according to the current data, and calculating a second calculation value according to the current fluctuation trend and a set current reference trend; Calculating a comprehensive absolute value according to the absolute value of the first calculation value and the absolute value of the second calculation value; If the comprehensive absolute value is within a set first reference range, activating a direct current distribution module, supplying power to the direct current distribution module through an alternating current power supply, and the direct current distribution module is in an energy storage mode or a power quality treatment mode; If the comprehensive absolute value is within a set second reference range, connecting the direct current distribution module to the distribution network, and the distribution network is supplied by the alternating current power supply and the direct current distribution module, and the direct current distribution module is in a power supply mode or a power quality treatment mode; If the comprehensive absolute value is within a set third reference range, and the energy storage capacity of the direct current distribution module is greater than a set reference capacity, cutting out the alternating current power supply from the distribution network, and the distribution network is supplied by the direct current distribution module, and the direct current distribution module is in a power supply mode; The value within the first reference range < the value within the second reference range < the value within the third reference range; The step of calculating a voltage fluctuation trend according to the voltage data, and calculating a first calculation value according to the voltage fluctuation trend and a set voltage reference trend further comprises the following sub-steps: Filtering a plurality of voltage data through a sliding filter algorithm, and then calculating voltage average data; Calculating the difference between each voltage data and the voltage average data as a voltage fluctuation difference value; Fitting a voltage fluctuation straight line according to each voltage fluctuation difference value; Calculating the latest voltage fluctuation trend based on the voltage fluctuation straight line; The voltage reference trend is set as the ratio of a set power reference value to a set voltage; The first calculation value is obtained by dividing the voltage fluctuation trend by the voltage reference trend; The step of calculating a current fluctuation trend according to the current data, and calculating a second calculation value according to the current fluctuation trend and a set current reference trend further comprises the following sub-steps: Filtering a plurality of current data through a weighted average algorithm, and the closer the time point of the collected current data, the greater the weight value of the corresponding current data; then calculating current average data; Calculating the difference between each current data and the current average data as a current fluctuation difference value; Fitting a current fluctuation curve according to each current fluctuation difference value; Calculating the latest current fluctuation trend based on the current fluctuation curve; The current reference trend is set as the ratio of a set power reference value to a set current; The second calculation value is obtained by dividing the current fluctuation trend by the current reference trend; The detection time length is adjusted according to the comprehensive absolute value, that is, the greater the comprehensive absolute value, the longer the detection time length, and the smaller the comprehensive absolute value, the shorter the detection time length. The step of supplying power to the direct current power distribution module further comprises the following steps: The alternating current power grid supplies power to the energy storage unit in the direct current power distribution module at a first power; The solar power of the solar unit in the direct current power distribution module is obtained, and if the solar power is greater than a predetermined power, the solar unit supplies power to the energy storage unit at a second power; The first power is adjusted according to the comprehensive absolute value; The second power is adjusted according to the ratio of the solar power to the predetermined power; The step of calculating the comprehensive absolute value according to the absolute value of the first calculation value and the absolute value of the second calculation value further comprises the following steps: The absolute value of the first calculation value and the absolute value of the second calculation value are calculated into a comprehensive absolute value by using a weighted average algorithm; The first weight value of the absolute value of the first calculation value is adjusted according to the voltage stability demand level of the power distribution grid, and the higher the voltage stability demand level, the greater the first weight value; The second weight value of the absolute value of the second calculation value is adjusted according to the current stability demand level of the power distribution grid, and the higher the current stability demand level, the greater the second weight value.

2. The method of claim 1, wherein, The step of supplying power to the power distribution grid by the direct current power distribution module further comprises the following steps: The power router is used to connect the alternating current power grid and the direct current power distribution module; The direct current power distribution module is connected to multiple alternating current power grids through the power router; The multiple alternating current power grids are interlocked, and the power router does not supply power to multiple alternating current power grids at the same time; When the power router supplies power to a single alternating current power grid, the power router is in a power supply mode or a power quality management mode; When multiple alternating current power grids are connected, the power router is in a power quality management mode.

3. The method of claim 1, wherein, The step of supplying power to the power distribution grid by the direct current power distribution module further comprises the following steps: The remaining energy and output power in the energy storage unit in the direct current power distribution module are obtained in real time; The output time is calculated according to the remaining energy and output power; If the output time is shorter than the set minimum time, the alternating current power grid is used to supply power to the power distribution grid alone, and the direct current power distribution module is cut out of the power distribution grid.

4. A dynamic load monitoring device for a flexible power distribution network, characterized by The processor executes the steps of the dynamic load monitoring method of the flexible power distribution grid according to any one of claims 1-3.

5. A storage medium, characterized by The storage medium stores a program, and the program is executed by the processor to realize the steps of the dynamic load monitoring method of the flexible power distribution grid according to any one of claims 1-3.

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