Island microgrid management system and energy management method thereof

Abstract

This invention discloses an islanded microgrid management system and its energy management method. The energy management method includes collecting and setting the output power of small-power generators within a preset time period based on historical data; setting a setpoint range; and controlling the islanded microgrid system to execute power adjustment commands based on the relationship between the actual output power of the power supply equipment and the power required by the electrical load, as well as the relationship between the state of charge value of the energy storage system and the setpoint range. The power adjustment commands include controlling the charging of the energy storage system, controlling the discharging of the energy storage system, controlling the disconnection of the power supply equipment, and controlling the disconnection of the power supply equipment from the load. This invention solves the power quality problems caused by power fluctuations, load changes, and system disturbances of microgrid renewable energy generators, and achieves reasonable allocation of the capacity of distributed power sources in the islanded microgrid, ensuring the stable operation of important loads.

Description

Technical Field

[0001] This invention relates to the field of islanded microgrid systems, and more particularly to an islanded microgrid management system and its energy management method. Background Technology

[0002] With the global energy situation becoming increasingly severe, the use of microgrids has received more and more attention.

[0003] Microgrid systems offer flexible operation modes, typically functioning both grid-connected (exchanging power with the external grid) and off-grid as completely independent island systems. However, for microgrids in specific scenarios, such as isolated islands, remote ranches, and border outposts—areas without large-scale grid coverage—they must operate autonomously. For these isolated microgrid systems, the lack of a large grid and the inability to accurately predict weather changes present significant challenges in ensuring reliable power supply and stable system operation. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an islanded microgrid management system and its energy management method, addressing at least one deficiency in the existing technology.

[0005] The technical solution adopted by this invention to solve its technical problem is: constructing an energy management method for an islanded microgrid system, the islanded microgrid system including energy supply equipment and energy storage system; the energy supply equipment includes low-power power units, new energy units and fuel oil units; wherein, the energy management method includes the following steps:

[0006] Collect and, based on historical data, set the output power of the low-power power unit within a preset time period;

[0007] Set the setpoint range;

[0008] Based on the relationship between the actual output power of the energy supply equipment and the power required by the electrical load, and the relationship between the state of charge value of the energy storage system and the set value range, the islanded microgrid system is controlled to execute power adjustment commands.

[0009] The power adjustment command includes one of controlling the energy storage system to charge, controlling the energy storage system to discharge, controlling the disconnection of the power supply equipment, and controlling the disconnection of the power supply equipment from the load.

[0010] Preferably, the step of collecting and setting the output of the low-power power unit within a preset time period based on historical data includes the following steps:

[0011] Collect the historical data, which includes historical system communication data, historical weather data, and historical load information;

[0012] Based on the historical data, predict the output of new energy units and the operation of all loads during the preset time period;

[0013] Based on the power output of the new energy units and the operating status of all loads during the preset time period, the power output of the low-power power units is set during the preset time period.

[0014] Preferably, controlling the islanded microgrid system to execute power adjustment commands based on the relationship between the actual output power of the energy supply equipment and the power required by the electrical load, and the relationship between the state of charge value of the energy storage system and the set value range, includes the following steps:

[0015] Based on the relationship between the actual output power of the power supply equipment and the power required by the electrical load, it is determined whether the islanded microgrid system is in an abnormal state. The abnormal state includes the system overfrequency state and the system underfrequency state. If yes, the next step is executed according to the abnormal state. If no, it is determined again whether the islanded microgrid system is in an abnormal state after a preset time.

[0016] When the isolated microgrid system is in the overfrequency state, the energy storage system is controlled to store energy or gradually disconnect the power supply equipment based on the relationship between the state of charge value of the energy storage system and the set value range.

[0017] When the isolated microgrid system is in a low-frequency state, the energy storage system is controlled to release energy or disconnect the electrical load based on the relationship between the state of charge value of the energy storage system and the set value range.

[0018] Preferably, when the islanded microgrid system is in an overfrequency state, controlling the energy storage system to store energy or gradually disconnect the power supply equipment based on the relationship between the state of charge value of the energy storage system and the set value range includes the following steps:

[0019] When the isolated microgrid system is in the over-frequency state, it is determined whether the state of charge of the energy storage system is lower than the maximum value in the set value range;

[0020] If yes, the energy storage system is controlled to enter charging mode; otherwise, the power supply devices are gradually disconnected according to a preset sequence.

[0021] Preferably, when the islanded microgrid system is in a low-frequency state, controlling the energy storage system to release energy or disconnect the load based on the relationship between the state of charge value of the energy storage system and the set value range includes the following steps:

[0022] When the isolated microgrid system is in the low-frequency state of the system, it is determined whether the state of charge of the energy storage system exceeds the minimum setting value in the setting value range;

[0023] If yes, the energy storage system is controlled to enter the discharge mode; otherwise, the power loads are cut off step by step according to the preset priority.

[0024] Preferably, after controlling the islanded microgrid system to execute the power adjustment command, the method further includes the following steps:

[0025] Based on the operation and shutdown status of the power supply equipment, the islanded microgrid system is controlled to enter the corresponding operating mode; the operating mode includes normal operation mode, general accident operation mode and emergency accident operation mode.

[0026] Preferably, the normal operating mode is the Hengyuan New Diesel Storage Mode;

[0027] The Hengyuan New Diesel Energy Storage Mode includes controlling the low-power power unit as the main power source and controlling the new energy unit as the auxiliary power source; the energy storage system and the fuel unit are used for peak shaving and valley filling.

[0028] Preferably, the general accident operation mode includes new diesel storage mode and source diesel storage mode;

[0029] The new diesel-storage mode includes controlling the islanded microgrid system to disconnect from the load with the lowest preset priority; controlling the new energy generator unit as the main power source and the energy storage system for peak shaving and valley filling; and controlling the diesel generator unit as the backup power source.

[0030] The source-diesel-storage mode includes controlling the disconnection of the islanded microgrid system from the load with the lowest preset priority; controlling the low-power generator unit as the main power source and the energy storage system for peak shaving and valley filling; and the fuel oil generator unit as the backup power source.

[0031] Preferably, the emergency operation mode is the diesel storage mode;

[0032] The diesel-storage mode includes controlling the fuel unit as the main power source to meet the preset priority of operating at the highest load, while the energy storage system serves as a transitional power source.

[0033] Preferably, the general accident operation mode includes new diesel storage mode and source diesel storage mode;

[0034] The step of controlling the islanded microgrid system to enter the corresponding operating mode based on the operation and shutdown status of the power supply equipment includes the following steps:

[0035] Determine whether the low-power power unit or all of the new energy units have exited operation. If yes, proceed to the next step; otherwise, enter the normal operation mode.

[0036] Determine whether the low-power units and all the new energy units have been taken out of operation. If yes, then enter the emergency operation mode; otherwise, proceed to the next step.

[0037] Determine the operation status of the low-power power unit or all the new energy units. If the low-power power unit is out of operation, execute the new diesel storage mode. If all the new energy units are out of operation, execute the source diesel storage mode.

[0038] Preferably, the method further includes the following steps:

[0039] After the islanded microgrid system executes a power adjustment command, the setting range is adjusted according to the power adjustment command.

[0040] Preferably, the preset order is to prioritize cutting off new energy generating units with low rated power and / or the lowest predicted output in the next time period based on the output of the new energy generating units in the next time period adjacent to the preset time period and / or the rated output power of the new energy generating units.

[0041] Preferably, the preset priority is to classify the load according to the power supply priority.

[0042] Preferably, the step of collecting and setting the output of the low-power power unit within a preset time period based on historical data includes the following steps:

[0043] Collect the historical data, which includes historical system communication data, historical weather data, and historical load information;

[0044] Based on the historical data, predict the output of new energy units and the operation of all loads during the preset time period;

[0045] The output power of the new energy units is adjusted during the preset time period;

[0046] Based on the adjusted output power of the new energy units and the operating status of all loads within the preset time period, the output power of the low-power power unit is set within the preset time period.

[0047] Preferably, the step of correcting the output of the new energy generating units during the preset time period includes the following steps:

[0048] Collect and set confidence levels as stratification criteria based on the characteristic data of the output of the new energy units;

[0049] Based on the confidence level, the upper bound e of the confidence interval for the power output prediction error of the new energy unit is obtained. + (x%) and lower bound e - (x%);

[0050] The first predicted output power that the new energy unit can generate within a first time period is obtained, as well as the first actual output power that actually reaches the first time period in the future; the first time period is the previous time period adjacent to the preset time period.

[0051] A first prediction error value is obtained based on the first predicted force and the first actual force.

[0052] Based on the first prediction error value and the upper bound e + (x%) and the lower bound e - By relating (x%) to obtain the error correction amount;

[0053] Based on the power output of the new energy generator units during the preset time period, and combined with the error correction amount, the power output of the new energy generator units after correction during the preset time period is obtained.

[0054] Preferably, the low-power power supply unit is used to output low-power power; the low-power power supply is used to maintain base load operation and has the characteristic of not being able to frequently and quickly adjust power.

[0055] Preferably, the relationship between the actual output power of the power supply equipment and the power required by the electrical load is as follows:

[0056] The difference between the actual output power of the power supply equipment and the power required by the electrical load is determined based on whether it is greater than a first preset threshold or less than a second preset threshold.

[0057] The present invention also constructs an islanded microgrid management system, including an islanded microgrid system, wherein the islanded microgrid system includes energy supply equipment and an energy storage system; the energy supply equipment includes new energy generator units and fuel oil generator units, and the energy supply equipment further includes low-power power supply units; the low-power power supply units are used to output low-power power; the low-power power supply units are used to maintain base load operation and have the characteristic of not being able to frequently and quickly adjust power.

[0058] The isolated microgrid management system also includes an energy management system for managing the power generation operation of the power supply equipment, the energy management system comprising:

[0059] The data acquisition module is used to collect historical data.

[0060] The prediction module is used to predict the output of new energy units and the operating status of all loads within a preset time period based on historical data.

[0061] The calculation module is used to calculate the output of the low-power power unit within the preset time period based on the output of the new energy unit and the operation of all loads within the preset time period.

[0062] The storage module is used to store data within the corresponding setpoint range;

[0063] The control module is used to output power adjustment commands to the islanded microgrid system.

[0064] The implementation of this invention has the following beneficial effects: The energy management method of this invention is based on an islanded microgrid system containing low-power power sources. It formulates energy management and real-time power control based on the power generation characteristics of low-power power sources. When the actual output power of the power supply equipment cannot meet the power required by the power load or exceeds the power required by the power load, it combines the state of charge of the energy storage system and rationally configures the output power by controlling the charging and discharging of the energy storage system or by reducing the load and disconnecting the generator. This solves the power quality problems caused by power fluctuations, load changes and system disturbances of the microgrid's new energy units, realizes the rational configuration of the capacity of each distributed power source in the islanded microgrid, and ensures the stable operation of important loads.

[0065] This invention relates to an islanded microgrid management system. By utilizing the power characteristics of low-power sources, it ensures the normal operation of the base load within the island, addresses the issues of intermittency and large fluctuations in power generation from renewable energy sources such as wind and solar, and constructs a sound microgrid. At the same time, it also establishes an energy management system to formulate energy management and real-time power control based on the power generation characteristics of low-power sources, thereby achieving system stability. Attached Figure Description

[0066] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0067] Figure 1 This is a flowchart of some embodiments of the energy management method for an islanded microgrid system of the present invention;

[0068] Figure 2 This is a flowchart of step S30 of the energy management method for an islanded microgrid system of the present invention in some embodiments;

[0069] Figure 3 This is a flowchart of step S40 of the energy management method for an islanded microgrid system of the present invention in some embodiments. Detailed Implementation

[0070] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0071] It should be noted that the flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0072] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0073] This invention constructs an energy management method applicable to islanded microgrid systems, which provide operating power to multiple loads. The method includes power supply equipment and an energy storage system; the power supply equipment includes low-power generators, renewable energy generators, and fuel-fired generators. In some embodiments, the loads include commercial, hospital, hotel, and oil extraction loads.

[0074] like Figures 1-2 As shown, the energy management method of the present invention may include, in some embodiments, the following:

[0075] S10: Collect and set the output power of the low-power power unit within a preset time period based on historical data;

[0076] S20: Set the setting value range;

[0077] S30: Based on the actual output power of the power supply equipment and the relationship between the state of charge value of the energy storage system and the set value range, control the islanded microgrid system to execute power adjustment commands;

[0078] Power adjustment commands include controlling the charging of the energy storage system, controlling the discharging of the energy storage system, controlling the reduction of the output power of the power supply equipment, and controlling the disconnection of the power supply equipment from the load.

[0079] Understandably, this invention maintains base load operation by setting up a low-power power supply. The characteristic of this low-power power supply is that it cannot frequently and quickly adjust power; its power adjustment response is on the order of minutes, resulting in poor system response. However, in the development of isolated microgrid systems, low-power power supplies are a crucial component in addressing intermittent renewable energy generation such as wind and solar power and in building a "sound" microgrid. Its power characteristics in maintaining base load operation can provide voltage and frequency references for isolated microgrid systems. In some embodiments, the low-power power supply unit is a unit with a power output below 50MW.

[0080] This energy management method is based on the requirements of power safety and reliability for isolated islands. It sets up a low-power power source to maintain the base load operation. For microgrids containing low-power power sources, it formulates energy management system control strategies based on factors such as the importance level of the island's power load, power source type, and external environment to achieve safe and efficient operation of the island microgrid system.

[0081] In some embodiments, step S10 includes the following steps:

[0082] S11: Collect historical data, including historical system communication data, historical weather data, and historical load information;

[0083] S12: Based on historical data, predict the output of new energy units and the operation of all loads within a preset time period;

[0084] S13: Based on the output power of the new energy units and the operating status of all loads within the preset time period, set the output power of the low-power power units within the preset time period.

[0085] Understandably, historical data refers to data prior to a preset time period, including historical system communication data, historical weather data, and historical load information. In some embodiments, historical system communication data includes communication information of the islanded microgrid system, including unit fault information, unit maintenance information, and unit operation information, etc.; historical weather data includes data such as wind speed, illuminance, and cloud cover; historical load information includes the operating status information and operating power of multiple loads, with operating status information including operating status and shutdown status, and operating power can be rated power operation or reduced power operation.

[0086] The preset time period can be understood as a period of time in the future. In this embodiment, the length of the preset time period is one hour. Of course, the length of the time period can be set according to the actual situation, and no specific limitation is made here.

[0087] In some embodiments, in step S10, the output of low-power power units within multiple preset time periods can be set according to historical data and a preset rule. The preset rule can be to predict the output of new energy units and the operating status of all loads in the next preset time period from the beginning of each preset time period. This can be understood as the multiple preset time periods being consecutive time periods; by predicting the output of low-power power units in advance for each preset time period, the stable operation of the baseload is ensured within the preset time period.

[0088] In some embodiments, the historical data collected by the SCADA acquisition device can be used to predict the output of new energy units and the operation of all loads in the future, thereby setting the output of low-power power units in advance for that future period.

[0089] Understandably, in the islanded operation mode of a microgrid, high-energy-consuming loads place high demands on the microgrid's frequency and voltage, requiring the system to output high-quality power to ensure the stable operation of critical load equipment. Under normal system conditions, the power supply to the loads is mainly provided by low-power generator units and renewable energy units. By predicting the output points of low-power generator units and renewable energy units during preset time periods, the safe and stable operation of the loads during those preset time periods can be ensured.

[0090] It should be noted that SCADA (Supervisory Control And Data Acquisition) equipment refers to data acquisition and monitoring control systems.

[0091] In some embodiments, between step S12 and step S13, a correction step for correcting the output power of the new energy unit is further included:

[0092] S14: Collect and set the confidence level as a stratification standard based on the characteristic data of the output of new energy units;

[0093] S15: Based on the confidence level, obtain the upper bound e of the confidence interval for the prediction error of the new energy unit output. + (x%) and lower bound e - (x%);

[0094] S16: Obtain the first predicted output power that the new energy unit can generate within the first time period, and the first actual output power that is actually achieved within the first time period; the first time period is the previous time period adjacent to the preset time period.

[0095] S17: Obtain the first prediction error value based on the first predicted force and the first actual force;

[0096] S18: Based on the first prediction error value and the upper bound e + (x%) and lower bound e - By relating (x%) to obtain the error correction amount;

[0097] S19: Based on the output of the new energy units during the preset time period, and combined with the error correction amount, obtain the corrected output of the new energy units during the preset time period.

[0098] Understandably, this invention selects a confidence level as a stratification standard based on the characteristic data of the power output of new energy units, and obtains the upper bound e of the confidence interval of the prediction error of the power output of new energy units corresponding to that confidence level. + (x%) and lower bound e - (x%), based on the confidence interval of this predicted value, the error is stratified.

[0099] It should be noted that obtaining the upper bound e of the confidence interval... + (x%) and lower bound e - The (x%) method can be found in relevant technologies and will not be elaborated here. Furthermore, the output confidence level is defined as the probability that the output will not exceed x% of the rated installed capacity within the sampling period. It reflects the likelihood of the output reaching a specific level and can be used to reflect the approximate range of the output. In some embodiments, the confidence level is 95%.

[0100] When the error value is within a small confidence interval, it indicates that the error is small, and this error layer is called a small error layer; when the error value is outside the confidence interval, it indicates that the error is large, and this error layer is called a large error layer. Thus, the error stratification structure analyzed using the numerical characteristics of the prediction error can be obtained.

[0101] Let the first time period be point n, and let P be the predicted output of the new energy generating units corresponding to the first time period. n The actual output power is P Rn Then the prediction error at point n is e n =P Rn -P n Error compensation principles applicable to both day-ahead and intraday forecasts:

[0102] When e n >e + When (x%), the error correction amount is +e n ;

[0103] When e n <e - When (x%), the error correction amount is -e n ;

[0104] When e - (x%)≤e n ≤e + When (x%), the error correction is 0;

[0105] The output of the new energy unit after adjustment within the preset time period is PA. n+1 =P n+1 ±e n .

[0106] Among them, P n+1 To predict the output of new energy generating units during a preset time period.

[0107] Understandably, due to the inherent randomness and intermittency of renewable energy units, such as wind and solar power output, the prediction results for wind / solar power output have relatively large errors. This inevitably has adverse effects on various aspects of dispatching and control, security and defense within isolated microgrids. To address the above problems, this invention uses a mathematical model to analyze the physical and statistical factors affecting the prediction error. It corrects the prediction error based on the actual output of the renewable energy units at the previous moment, and then predicts and analyzes the output of the renewable energy units at the next moment. By compensating for the error in the predicted output of the renewable energy units, the error correction is completed.

[0108] This invention can obtain the output power of a modified new energy power unit based on the predicted power value of the modified new energy power unit; similarly, this invention can set the output power of a low-power power unit within a preset time period based on the output power of the modified new energy power unit.

[0109] In this embodiment, step S13 is changed to:

[0110] S13: Based on the adjusted output of the new energy units and the operating status of all loads within the preset time period, set the output of the low-power power units within the preset time period.

[0111] In step S20, the setting range is used to determine the state of charge (SOC) of the energy storage system in the islanded microgrid system. The setting range includes a maximum setting value and a minimum setting value; the maximum setting value is the upper limit of the SOC of the energy storage system, and the minimum setting value is the lower limit of the SOC of the energy storage system. If the SOC of the energy storage system is not within the setting range when an anomaly occurs in the islanded microgrid system, it is necessary to control the islanded microgrid system to execute a power adjustment command to ensure stability. In some embodiments, the setting range can be set by referring to and based on the system's past operating data.

[0112] In islanded microgrid operation, high-energy-consuming loads place high demands on the microgrid's frequency and voltage, requiring the system to output high power quality to ensure the stable operation of critical load equipment. Under normal system conditions, the power supply to the loads is mainly provided by low-power generator units and renewable energy units. Among them, the low-power generator units that maintain base load operation can serve as the main control micro-power source of the energy management system, operating in VF mode to provide system voltage and frequency references, while subordinate distributed micro-power sources operate in PQ mode, such as power generated from renewable energy sources.

[0113] In step S10, the output power prediction of the low-power power unit is set to ensure that the base load can operate stably within a preset time period. Although the low-power power unit can basically ensure stable operation, there are still some small fluctuations; at the same time, the unstable and intermittent characteristics of new energy sources can also cause changes in the transient stability of the system.

[0114] Step S30 is used to adjust power control through energy storage charging and discharging management when the islanded microgrid system is abnormal. When the system adjustment range exceeds the energy storage adjustment capacity, the stability of the islanded microgrid is restored through further low-frequency load shedding and over-frequency generator tripping management.

[0115] In some embodiments, step S30 includes the following steps:

[0116] S31: Based on the relationship between the actual output power of the power supply equipment and the power required by the electrical load, determine whether the islanded microgrid system is in an abnormal state. Abnormal states include system overfrequency state and system underfrequency state. If yes, proceed to the next step according to the abnormal state. If no, determine whether the islanded microgrid system is in an abnormal state again after a preset time.

[0117] S32: When the islanded microgrid system is in a system overfrequency state, according to the relationship between the state of charge value of the energy storage system and the set value range, control the energy storage system to store energy or gradually disconnect the power supply equipment.

[0118] S33: When the islanded microgrid system is in a low-frequency state, the energy storage system is controlled to release energy or disconnect the load based on the relationship between the state of charge value of the energy storage system and the set value range.

[0119] In some embodiments, step S32 includes the following steps:

[0120] S32-1: When the isolated microgrid system is in a system overfrequency state, determine whether the state of charge of the energy storage system is lower than the maximum value in the setting range based on the relationship between the state of charge value of the energy storage system and the setting range.

[0121] S32-2: If yes, control the energy storage system to enter charging mode; if not, gradually reduce the output power of the new energy unit according to the preset sequence.

[0122] In some embodiments, step S33 includes the following steps:

[0123] S33-1: When the isolated microgrid system is in a low-frequency state, determine whether the state of charge of the energy storage system exceeds the minimum setting value in the setting value range based on the relationship between the state of charge value of the energy storage system and the setting value range.

[0124] S33-2: If yes, control the energy storage system to enter the discharge mode; if not, cut off the load step by step according to the preset priority.

[0125] Understandably, in step S31, determining whether the islanded microgrid system is in an abnormal state can be based on the relationship between the actual output power of the power supply equipment during the preset time period and the power required by the electrical load; the aforementioned electrical load refers to the load among multiple loads that needs to be powered on and operated during the preset time period.

[0126] When the output power of an isolated microgrid system exceeds the power required by the load, the system frequency increases, potentially leading to overfrequency phenomena. To maintain system power balance, energy storage systems need to be charged. These energy storage systems can enter charging mode to store excess electricity; when the state of charge (SOC) of the energy storage system exceeds the upper limit... max When the maximum setpoint is reached, in order to ensure system stability, instructions are issued to the islanded microgrid system to gradually disconnect the power supply equipment. In some embodiments, disconnecting the power supply equipment means gradually reducing the output power of the renewable energy units until the output power of the renewable energy units is reduced to zero.

[0127] In some embodiments, power supply equipment is gradually disconnected according to a preset sequence. This preset sequence is determined based on the output of the renewable energy units in the next time period adjacent to the preset time period and / or the rated output power of the renewable energy units. For example, if some renewable energy units have low rated power generation and / or are predicted to have low output in the next time period, these renewable energy units are disconnected first.

[0128] When the electricity load increases or the output of new energy units decreases, a power deficit occurs in the system, causing a drop in system frequency. In severe cases, this can lead to low-frequency phenomena. To maintain system power balance, the energy storage system needs to discharge. The energy storage system can enter discharge mode, and the discharge capacity depends on the system power deficit. When the State of Charge (SOC) exceeds the lower limit SOC... min When the minimum setpoint is reached, a load shedding command is issued to the islanded microgrid system. Non-critical loads are shelved sequentially according to a preset priority, i.e., the connection between the power supply equipment and the electrical load is disconnected. In some embodiments, the preset priority is based on load classification according to power supply priority, dividing the load into primary, secondary, and tertiary loads. Primary loads are the most important loads. The load priority determines the order in which the islanded microgrid system automatically shelves loads when system fluctuations occur. In this embodiment, the base loads are primary and secondary loads.

[0129] In some embodiments, the severity of the frequency increase or power deficit in the system can be determined based on a set threshold. When the power difference between the output power of the islanded microgrid system and the power required by the electrical load is not within the preset threshold range, it can be determined that the system is low-frequency or high-frequency.

[0130] If no abnormal state is detected in the islanded microgrid system during step S30, step S30 is repeated after a preset time to determine again whether the islanded microgrid system is in an abnormal state. This allows for continuous monitoring of the power status of the islanded microgrid system, ensuring system stability. The preset time can be set according to actual conditions and is not specifically limited here.

[0131] In some embodiments, such as Figure 3 As shown, after step S30, step S40 is also included, which specifically includes:

[0132] S40: Control the islanded microgrid system to enter the corresponding operating mode according to the operation and shutdown status of the power supply equipment; the operating modes include normal operation mode, general accident operation mode and emergency accident operation mode.

[0133] In some embodiments, step S40 includes the following steps:

[0134] S41: Determine whether the low-power power unit or all new energy units have been taken out of operation. If yes, proceed to step S42; otherwise, enter normal operation mode.

[0135] S42: Determine whether all low-power units and all new energy units have been taken out of operation. If yes, enter the emergency operation mode; otherwise, proceed to step S43.

[0136] S43: Determine the operation and shutdown status of low-power power units or all new energy units. If the low-power power units are shut down, execute the new diesel-storage mode. If all new energy units are shut down, execute the source diesel-storage mode.

[0137] Understandably, step S40 categorizes the possible fault conditions and equipment status of the islanded microgrid and sets up three operating modes. Based on the power supply and equipment status, it autonomously determines / changes the operating mode, schedules the power supply under this operating mode and performs load switching, quickly locates faults, achieves efficient self-healing of the system, and helps operation and dispatch personnel quickly grasp the operating status of the microgrid system.

[0138] In normal operation, the islanded microgrid system is powered by small-power generators as the main power source, supplemented by renewable energy generators, and energy storage systems and fuel-fired generators are used for peak shaving and valley filling to ensure stable grid operation.

[0139] In some embodiments, the normal operating mode can be the Hengyuan New Diesel Storage Mode. The Hengyuan New Diesel Storage Mode includes controlling a small-power generator unit as the main power source and a new energy generator unit as an auxiliary power source; the energy storage system and the fuel oil generator unit are used for peak shaving and valley filling.

[0140] In this embodiment, if the state of charge of the energy storage system is SOC > SOC max Low-power power units maintain base load operation, while renewable energy units operate at limited power. At this time, the energy storage system is in a discharging state, and the load's operating power is provided by the discharge of low-power power units, renewable energy units, and the energy storage system. Its operating power P L =P 源 +P 新 +P 储 .

[0141] If the energy storage system is at SOC m in<SOC<SOC max The low-power generator units maintain base load operation, ensuring power generation as much as possible while renewable energy units operate at limited power. At this time, the energy storage system is in a charging state, and the load's operating power is provided by the low-power generator units and renewable energy units, with an operating power P. L +P 储 =P 源 +P 新 .

[0142] If the state of charge of the energy storage system is SOC < SOC min The low-power power units maintain base load operation, while the renewable energy units operate at maximum power. At this time, the energy storage system is in a charging state, and the load's operating power is provided by the low-power power units and the renewable energy units, with an operating power P. L +P 储 =P 源 +P 新max .

[0143] In a typical emergency operation mode, the islanded microgrid system is powered by low-power generators or renewable energy generators, while the energy storage system is still used for peak shaving and valley filling to stabilize the system, and the fuel-fired generators serve as backups. Some loads are cut off according to a preset priority. In this embodiment, the cut-off of some loads refers to the cut-off of some tertiary loads.

[0144] In some embodiments, the general emergency operation mode includes a new diesel-storage mode and a source diesel-storage mode. The new diesel-storage mode includes controlling the islanded microgrid system to disconnect from the load with the lowest preset priority; controlling the renewable energy unit as the main power source, with the energy storage system used for peak shaving and valley filling; and using the diesel-powered unit as a backup power source. The source diesel-storage mode includes controlling the islanded microgrid system to disconnect from the load with the lowest preset priority; controlling the low-power unit as the main power source, with the energy storage system used for peak shaving and valley filling; and using the diesel-powered unit as a backup power source.

[0145] In some embodiments, the new diesel-storage mode involves controlling the islanded microgrid system to disconnect tertiary loads to supply power to other higher-priority loads. The renewable energy generators serve as the main power source, while the energy storage system regulates system frequency and voltage, smoothing out fluctuations in wind turbine output.

[0146] In this embodiment, if the state of charge (SOC) of the energy storage system is greater than the state of charge (SOC) of the energy storage system... max At this time, the new energy generating units operate at limited power; the energy storage system is in a discharging state, and the load's operating power is provided by the discharge of the fuel oil generating units, new energy generating units, and the energy storage system, with its operating power P. L =P 柴 +P 新 +P 储 .

[0147] If the energy storage system's state of charge (SOC) min <SOC<SOC max When renewable energy units operate at limited power, efforts should be made to ensure their power generation. At this time, the energy storage system is in a charging state, and the load's operating power is provided by the fuel-fired power unit and the renewable energy unit, with an operating power P. L +P 储 =P 柴 +P 新 .

[0148] If the state of charge (SOC) of the energy storage system is less than SOC min The new energy generating units operate at maximum power; at this time, the energy storage system is in a charging state, and the working power of the load is provided by the fuel oil generating units and the new energy generating units, with a working power P. L +P 储 =P 柴 +P 新max .

[0149] In some embodiments, the source-diesel-storage mode controls the islanded microgrid system to cut off tertiary loads to supply power to other higher priority loads; small power generators serve as the main power source to provide voltage and frequency references for the system, and the energy storage system is used to regulate the system frequency and voltage and smooth out fluctuations in wind turbine output; the fuel oil generators serve as backup power sources.

[0150] In the emergency operation mode, if the low-power power units and new energy units cannot supply power, the islanded microgrid system will be powered by the energy storage system and the oil-fired power units. Among them, the oil-fired power units serve as the main power source of the system, ensuring the power supply of the primary load, while the energy storage system serves as a transitional power source, allowing time margin for the start-up of the oil-fired power units.

[0151] In some embodiments, the emergency operation mode is diesel-storage mode; diesel-storage mode includes controlling the fuel oil generator as the main power source to meet the preset priority highest load operation, and the energy storage system as a transitional power source.

[0152] In this embodiment, the fuel-powered generator set capacity meets the preset operating time for the primary load, and the energy storage system serves as a transitional power source. Understandably, this preset time is determined based on the primary load capacity and demand, specifying the operating time of the fuel-powered generator set. In this embodiment, the diesel engine capacity meets the system's primary load operating time for 7 hours.

[0153] In summary, this invention establishes four modes and three operating methods based on different operating conditions and unit states of isolated microgrid systems: Source-New-Diesel-Storage Mode (small power source, new energy unit, fuel oil unit, and energy storage can all operate – normal operation mode), New-Diesel-Storage Mode (new energy unit, fuel oil unit, and energy storage operate normally – general accident operation mode), Source-Diesel-Storage Mode (small power source, fuel oil unit, and energy storage operate normally – general accident operation mode), and Diesel-Storage Mode (fuel oil unit and energy storage operate normally – emergency accident operation mode). By implementing zoned management of the isolated microgrid system's operating status, making comprehensive decisions based on collected system information, and finally switching operating modes, the operation of the isolated microgrid system's power supply is controlled. In some embodiments, the fuel oil unit is a diesel engine.

[0154] In some embodiments, step S40 further includes a detection step for detecting isolated microgrid system equipment, which is performed before step S41, and specifically includes:

[0155] S41-0: Detect and determine whether the operating status of the isolated microgrid system meets the preset requirements; if it does, execute step S41; if not, issue a shutdown command to the isolated microgrid system.

[0156] In some embodiments, the operating status of an isolated microgrid system includes the startup status of new energy units, the power distribution status of equipment, the startup status of each subsystem, the operating status of battery power, etc.

[0157] Understandably, determining whether the startup status of a new energy unit meets preset requirements can be done by judging whether the outside wind speed has reached the wind speed condition for the wind turbine to start; determining whether the power distribution status of the equipment meets preset requirements can be done by judging whether the power distribution status of the equipment is complete; determining whether the startup status of each subsystem meets preset requirements can be done by judging whether each subsystem meets the startup conditions; and determining whether the battery power level meets preset requirements can be done by judging whether the battery power level meets the operating conditions.

[0158] In some embodiments, if a subsystem cannot be put into operation due to a fault or maintenance, it will issue an alarm or fault signal. After receiving the signal, the energy management system will issue a system shutdown order, and the unit will stop operating.

[0159] In some embodiments, the energy management method further includes an adjustment step for adjusting the setpoint range. This adjustment step is S50, which can be performed after step S30. Step S50 specifically involves:

[0160] S50: After executing the power adjustment command for the control islanded microgrid system, adjust the setting range according to the power adjustment command.

[0161] Understandably, for low-frequency or over-frequency phenomena in microgrids that exceed the stability control of energy storage, the setting range is set / adjusted through load shedding and generator tripping stability control measures. The setting / adjustment of the setting value depends on the network architecture of the entire islanded microgrid.

[0162] The order of low-frequency load shedding depends on the granularity of load classification. The finer the load classification, the smaller the frequency protection setting difference, which is more beneficial for the energy management system to control the power stability of the microgrid. In some embodiments, according to the load classification in this embodiment, the minimum setting value corresponding to the first round of low-frequency load shedding can be set to 49.4Hz, the minimum setting value corresponding to the second round of low-frequency load shedding can be adjusted to 49.3Hz, the minimum setting value corresponding to the third round of low-frequency load shedding can be adjusted to 49.2Hz, and the minimum setting value corresponding to the fourth round of low-frequency load shedding can be adjusted to 49.1Hz. The load shedding in each round is determined according to the power supply priority until the system tends to stabilize.

[0163] Overload tripping can be configured based on the output of the renewable energy units in the next time period adjacent to a preset time period and / or the rated output power of the renewable energy units. For example, if some renewable energy units have low rated power generation and / or are predicted to have low output in the next time period, the output power of these renewable energy units will be reduced first; according to this tripping sequence, the maximum setting value in the setting range is adjusted. In some embodiments, the maximum setting value corresponding to the first round of overload tripping is 50.6Hz, the maximum setting value corresponding to the second round of overload tripping is 50.7Hz, the maximum setting value corresponding to the third round of overload tripping is 50.8Hz, and the maximum setting value corresponding to the fourth round of overload tripping is 50.9Hz, until the system tends to stabilize.

[0164] This invention also constructs an islanded microgrid management system, which includes an islanded microgrid system and an energy management system. The islanded microgrid system includes energy supply equipment and an energy storage system. The energy supply equipment includes low-power generator units, renewable energy generator units, and fuel-fired generator units. This energy management system uses low-power generators as the basic point for production planning, achieving coordinated power control and managing the power generation of the energy supply equipment.

[0165] The energy management system includes:

[0166] The acquisition module is used to collect historical data; in some embodiments, the acquisition module is a SCADA acquisition device.

[0167] The prediction module, connected to the acquisition module, is used to predict the output of new energy units and the operating status of all loads within a preset time period based on historical data.

[0168] The calculation module, connected to the prediction module, is used to calculate the output of the low-power power unit within the corresponding preset time period based on the output of the new energy unit and the operation of all loads within the preset time period.

[0169] The storage module is used to store data within the corresponding set value range, system calculation and operation data, system operation history data, etc.

[0170] The control module connects to the islanded microgrid system and is used to output power adjustment commands to the islanded microgrid system.

[0171] In some embodiments, the control module can also control the islanded microgrid system to enter a corresponding operating mode based on the operation and shutdown status of the power supply equipment.

[0172] In some embodiments, the energy management system further includes a judgment module for judging whether the islanded microgrid system is in an abnormal state, or whether it is in a system overfrequency state or a system underfrequency state.

[0173] In some embodiments, the judgment module can also determine the relationship between the state of charge of the energy storage system and the set value range.

[0174] In some embodiments, the judgment module can also determine the operation and shutdown status of low-power power units or all new energy units.

[0175] In some embodiments, the energy management system further includes an adjustment module, which is connected to the control module and the storage module respectively. The adjustment module is used to receive and adjust the setting range according to the power adjustment command issued by the storage module after executing the power adjustment command of the control islanded microgrid system, and store the adjusted setting range data into the storage module.

[0176] In some embodiments, the energy management system further includes a correction module, which is connected to the prediction module and the calculation module respectively; the correction module is used to correct the predicted output of the new energy units.

[0177] This invention is based on the characteristics of islanded microgrids, which include maintaining the base load and ensuring sufficient power supply for the system by using low-power sources that are not suitable for frequent adjustments. It fills the gap in the research on special power source strategies in domestic energy management systems, solves the power quality problems caused by the fluctuation of low-power sources to the microgrid, realizes the rational allocation of the capacity of each distributed power source in the microgrid, gives full play to the advantages of renewable energy, improves power quality, realizes the development and utilization of green and clean energy in islanded areas, and reduces unnecessary economic costs.

[0178] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. An energy management method for an islanded microgrid system, characterized in that, The isolated microgrid system includes energy supply equipment and an energy storage system; the energy supply equipment includes low-power generator units, new energy generator units, and fuel-fired generator units; the low-power generator units are used to output low-power power; the low-power power supplies are used to maintain base load operation and have the characteristic of not being able to frequently and rapidly adjust power, and the power regulation response capability of the low-power power supplies is on the order of minutes; wherein, the energy management method includes the following steps: Collect and, based on historical data, set the output power of the low-power power unit within a preset time period; Set the setpoint range; Based on the relationship between the actual output power of the energy supply equipment and the power required by the electrical load, and the relationship between the state of charge value of the energy storage system and the set value range, the islanded microgrid system is controlled to execute power adjustment commands. The power adjustment command includes one of controlling the energy storage system to charge, controlling the energy storage system to discharge, controlling the disconnection of the power supply equipment, and controlling the disconnection of the power supply equipment from the load; The step of collecting and setting the output of the low-power power unit within a preset time period based on historical data includes the following steps: Collect the historical data, which includes historical system communication data, historical weather data, and historical load information; Based on the historical data, predict the output of new energy units and the operation of all loads during the preset time period; The output power of the new energy units is adjusted during the preset time period; Based on the adjusted output power of the new energy units and the operating status of all loads during the preset time period, the output power of the low-power power unit is set within the preset time period. The step of correcting the output of the new energy units during the preset time period includes the following steps: Collect and set confidence levels as stratification criteria based on the characteristic data of the output of the new energy units; Based on the confidence level, the upper bound e of the confidence interval for the power output prediction error of the new energy unit is obtained. + (x%) and lower bound e - (x%); The first predicted output power that the new energy unit can generate within a first time period is obtained, as well as the first actual output power that actually reaches the first time period in the future; the first time period is the previous time period adjacent to the preset time period. A first prediction error value is obtained based on the first predicted force and the first actual force. Based on the first prediction error value and the upper bound e + (x%) and the lower bound e - By relating (x%) to obtain the error correction amount; Based on the output power of the new energy generator units during the preset time period, and combined with the error correction amount, the corrected output power of the new energy generator units during the preset time period is obtained. The output power of the new energy unit after correction during the preset time period is expressed as follows: PA n+1 =P n+1 ±e n Among them, P n+1 To predict the power output of renewable energy generating units within a preset time period; n represents the first time period, and the predicted power output of renewable energy generating units for the corresponding time period is P. n The actual output power is P Rn The prediction error value is e n ; When e n >e + When (x%), the error correction amount is +e n ; When e n <e - When (x%), the error correction amount is -e n ; When e - (x%)≤e n ≤e + When (x%), the error correction is 0.

2. The energy management method according to claim 1, characterized in that, The process of collecting and setting the output of the low-power power unit within a preset time period based on historical data includes the following steps: Collect the historical data, which includes historical system communication data, historical weather data, and historical load information; Based on the historical data, predict the output of new energy units and the operation of all loads during the preset time period; Based on the power output of the new energy units and the operating status of all loads during the preset time period, the power output of the low-power power units is set during the preset time period.

3. The energy management method according to claim 1, characterized in that, The step of controlling the islanded microgrid system to execute power adjustment commands based on the relationship between the actual output power of the energy supply equipment and the power required by the electrical load, and the relationship between the state of charge value of the energy storage system and the set value range, includes the following steps: Based on the relationship between the actual output power of the power supply equipment and the power required by the electrical load, it is determined whether the islanded microgrid system is in an abnormal state. The abnormal state includes the system overfrequency state and the system underfrequency state. If yes, the next step is executed according to the abnormal state. If no, it is determined again whether the islanded microgrid system is in an abnormal state after a preset time. When the isolated microgrid system is in the overfrequency state, the energy storage system is controlled to store energy or gradually disconnect the power supply equipment based on the relationship between the state of charge value of the energy storage system and the set value range. When the isolated microgrid system is in a low-frequency state, the energy storage system is controlled to release energy or disconnect the electrical load based on the relationship between the state of charge value of the energy storage system and the set value range.

4. The energy management method according to claim 3, characterized in that, When the isolated microgrid system is in an overfrequency state, based on the relationship between the state of charge value of the energy storage system and the set value range, controlling the energy storage system to store energy or gradually disconnecting the power supply equipment includes the following steps: When the isolated microgrid system is in the over-frequency state, it is determined whether the state of charge of the energy storage system is lower than the maximum value in the set value range; If yes, the energy storage system is controlled to enter charging mode; otherwise, the power supply devices are gradually disconnected according to a preset sequence.

5. The energy management method according to claim 3, characterized in that, When the isolated microgrid system is in a low-frequency state, controlling the energy storage system to release energy or disconnect the load based on the relationship between the state of charge value of the energy storage system and the set value range includes the following steps: When the isolated microgrid system is in the low-frequency state of the system, it is determined whether the state of charge of the energy storage system exceeds the minimum setting value in the setting value range; If yes, the energy storage system is controlled to enter the discharge mode; otherwise, the power loads are cut off step by step according to the preset priority.

6. The energy management method according to claim 1, characterized in that, After controlling the islanded microgrid system to execute the power regulation command, the following steps are also included: Based on the operation and shutdown status of the power supply equipment, the islanded microgrid system is controlled to enter the corresponding operating mode; the operating mode includes normal operation mode, general accident operation mode and emergency accident operation mode.

7. The energy management method according to claim 6, characterized in that, The normal operating mode is the Hengyuan New Diesel Storage Mode; The Hengyuan New Diesel Energy Storage Mode includes controlling the low-power power unit as the main power source and controlling the new energy unit as the auxiliary power source; the energy storage system and the fuel unit are used for peak shaving and valley filling.

8. The energy management method according to claim 6, characterized in that, The general accident operation modes include new diesel storage mode and source diesel storage mode; The new diesel-storage mode includes controlling the islanded microgrid system to disconnect from the load with the lowest preset priority; controlling the new energy generator unit as the main power source and the energy storage system for peak shaving and valley filling; and controlling the diesel generator unit as the backup power source. The source-diesel-storage mode includes controlling the disconnection of the islanded microgrid system from the load with the lowest preset priority; controlling the low-power generator unit as the main power source and the energy storage system for peak shaving and valley filling; and the fuel oil generator unit as the backup power source.

9. The energy management method according to claim 6, characterized in that, The emergency operation mode is diesel storage mode; The diesel-storage mode includes controlling the fuel unit as the main power source to meet the preset priority of operating at the highest load, while the energy storage system serves as a transitional power source.

10. The energy management method according to claim 6, characterized in that, The general accident operation modes include new diesel storage mode and source diesel storage mode; The step of controlling the islanded microgrid system to enter the corresponding operating mode based on the operation and shutdown status of the power supply equipment includes the following steps: Determine whether the low-power power unit or all of the new energy units have exited operation. If yes, proceed to the next step; otherwise, enter the normal operation mode. Determine whether the low-power units and all the new energy units have been taken out of operation. If yes, then enter the emergency operation mode; otherwise, proceed to the next step. Determine the operation status of the low-power power unit or all the new energy units. If the low-power power unit is out of operation, execute the new diesel storage mode. If all the new energy units are out of operation, execute the source diesel storage mode.

11. The energy management method according to claim 1, characterized in that, It also includes the following steps: After the islanded microgrid system executes a power adjustment command, the setting range is adjusted according to the power adjustment command.

12. The energy management method according to claim 4, characterized in that, The preset order is based on the output power of the new energy units in the next time period adjacent to the preset time period and / or the rated output power of the new energy units, prioritizing the shutdown of new energy units with low rated power generation and / or the lowest predicted output power in the next time period.

13. The energy management method according to claim 5, characterized in that, The preset priority is used to classify loads according to power supply priority.

14. The energy management method according to claim 1, characterized in that, The relationship between the actual output power of the energy supply equipment and the power required by the electrical load is as follows: The difference between the actual output power of the power supply equipment and the power required by the electrical load is determined based on whether it falls within a preset threshold range.

15. An islanded microgrid management system, comprising an islanded microgrid system, the islanded microgrid system including energy supply equipment and an energy storage system; the energy supply equipment including new energy generator units and oil-fired generator units, characterized in that, The power supply equipment also includes a low-power power supply unit; the low-power power supply unit is used to output low-power power; the low-power power supply is used to maintain base load operation and has the characteristic of not being able to frequently and quickly adjust power, and the power adjustment response capability of the low-power power supply is on the order of minutes; The isolated microgrid management system also includes an energy management system for managing the power generation operation of the power supply equipment, the energy management system comprising: The data acquisition module is used to collect historical data, including historical system communication data, historical weather data, and historical load information. The prediction module is used to predict the output of new energy units and the operating status of all loads within a preset time period based on historical data. The correction module is used to correct the predicted output of the new energy units; The calculation module is used to calculate the output of the low-power power unit within the preset time period based on the corrected output of the new energy unit and the operating status of all loads within the preset time period. The storage module is used to store data within the corresponding setpoint range; The control module is used to output power adjustment commands to the islanded microgrid system; The step of adjusting the output of the new energy generating units during the preset time period includes: Collect and set confidence levels as stratification criteria based on the characteristic data of the output of the new energy units; Based on the confidence level, the upper bound e of the confidence interval for the power output prediction error of the new energy unit is obtained. + (x%) and lower bound e - (x%); The first predicted output power that the new energy unit can generate within a first time period is obtained, as well as the first actual output power that actually reaches the first time period in the future; the first time period is the previous time period adjacent to the preset time period. A first prediction error value is obtained based on the first predicted force and the first actual force. Based on the first prediction error value and the upper bound e + (x%) and the lower bound e - By relating (x%) to obtain the error correction amount; Based on the output power of the new energy generator units during the preset time period, and combined with the error correction amount, the corrected output power of the new energy generator units during the preset time period is obtained. The output power of the new energy unit after correction during the preset time period is expressed as follows: PA n+1 =P n+1 ±e n Among them, P n+1 To predict the power output of renewable energy generating units within a preset time period; n represents the first time period, and the predicted power output of renewable energy generating units for the corresponding time period is P. n The actual output power is P Rn The prediction error value is e n ; When e n >e + When (x%), the error correction amount is +e n ; When e n <e - When (x%), the error correction amount is -e n ; When e - (x%)≤e n ≤e + When (x%), the error correction is 0.

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