Light storage micro-grid control method and system based on load fluctuation

Abstract

The invention relates to the technical field of optical storage micro-grids, and discloses an optical storage micro-grid control method and system based on load fluctuation, and the method comprises the following steps: 1, collecting weather data and the SOC of an energy storage battery in a micro-grid system; collecting real-time operation data of the micro-grid system in real time, wherein the real-time operation data comprises load power, photovoltaic power generation power and real-time time; step 2, executing a corresponding control action for the microgrid system according to a preset judgment strategy; the preset judgment strategy and the corresponding control action comprise the following steps: judging the time period of the micro-grid system according to the real-time time ts; judging the weather type of the micro-grid system according to the weather data; and in combination with the time period, the weather type, the SOC and the real-time operation data, controlling the micro-grid system to switch the state of a corresponding component into standby, power generation, charging or discharging. According to the invention, the light storage income can be effectively improved while the stable work of the micro-grid system is maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic microgrid storage technology, and in particular to a photovoltaic microgrid storage control method and system based on load fluctuation. Background Art

[0002] A microgrid is a small power network that can operate independently or in connection with the main grid. When the main grid fails, the microgrid can switch to island mode to provide continuous power supply for important loads; under normal circumstances, it can be integrated into the main grid to achieve more efficient energy management. In recent years, with the rapid development of renewable energy technology and the widespread application of energy storage systems, photovoltaic storage microgrid projects have been widely deployed around the world. The control strategy of these projects is usually to adjust the output power or operation mode of the energy storage device based on the changes in the actual output power of photovoltaics to ensure system stability and maximize economic benefits. Through this dynamic adjustment, the microgrid can maintain a stable power supply under different weather conditions and optimize energy utilization when electricity prices fluctuate, thereby reducing operating costs.

[0003] However, although traditional control strategies can work effectively in most cases, they are not flexible and efficient enough under certain specific conditions. Especially when extreme weather conditions or sudden failures cause a sharp drop in photovoltaic output, traditional control systems often take measures to cut off some non-critical loads in order to ensure the stable operation of the microgrid system. Although this approach can avoid system crashes in the short term, it does not meet user needs and expectations in the long run. In fact, in many application scenarios, such as hospitals, data centers and other important facilities, even in the case of tight power supply, it is necessary to give priority to ensuring the continuous power supply of critical loads. Therefore, traditional control strategies have lost their meaning in this case. In addition, frequent load shedding will not only lead to user dissatisfaction, but may also cause safety issues. For example, in a medical environment, it may cause life support equipment to shut down, resulting in irreparable losses. At the same time, from an economic perspective, the indirect economic losses caused by service interruptions cannot be ignored.

[0004] Therefore, there is an urgent need for a more stable and economical microgrid control method that can cope with load fluctuation scenarios. Summary of the invention

[0005] The present invention aims to provide a method and system for controlling a photovoltaic-storage microgrid based on load fluctuations, which can effectively improve the photovoltaic-storage revenue while maintaining the stable operation of the microgrid system.

[0006] To achieve the above objectives, the present invention provides the following basic solutions.

[0007] Solution 1

[0008] A method for controlling a photovoltaic energy storage microgrid based on load fluctuations comprises the following steps:

[0009] Step 1: Collect weather data and the SOC of the energy storage battery in the microgrid system; and collect real-time operation data of the microgrid system in real time, the real-time operation data includes load power P load , Photovoltaic power generation power P pv and real time t s ;

[0010] Step 2: Execute corresponding control actions for the microgrid system according to the preset judgment strategy;

[0011] The preset judgment strategy and corresponding control action include: according to the real-time time t s Determine the time period of the microgrid system; determine the weather type of the microgrid system based on weather data; combine the time period, weather type, SOC and real-time operation data to control the microgrid system to switch the status of its corresponding components to standby, power generation, charging or discharging.

[0012] Furthermore, the components of the microgrid system include an energy storage device, distributed energy and a load; the energy storage battery is arranged in the energy storage device; and the distributed energy includes a photovoltaic system.

[0013] Furthermore, the time period includes a low-valley electricity price period and a non-valley electricity price period; the non-valley electricity price period includes a peak period, a peak period and a normal period.

[0014] Furthermore, the weather type includes a cloudy type and a non-cloudy type.

[0015] Furthermore, when the time period is a valley electricity price period and SOC>20%, the microgrid system is controlled to switch the state of the energy storage device to discharge until SOC≤20%; when the time period is a valley electricity price period and SOC≤20%, the energy storage device is controlled to stop discharging, and the microgrid system is switched to the mains power supply mode, and the state of the energy storage device is switched to charging after the microgrid system is stable.

[0016] Furthermore, when the period is not a low-peak electricity price period, and P pv >P load , and the weather type is non-cloudy, if SOC ≥ 80%, the microgrid system is controlled to switch the state of the photovoltaic system from MPPT power generation to constant power generation; if SOC < 80%, the photovoltaic system is controlled to maintain MPPT power generation, and the state of the energy storage device is controlled to switch to charging to absorb excess electric energy; the charging power of the energy storage device = P pv -P load .

[0017] Furthermore, when P pv <P load, and the weather type is non-cloudy, if the time period is a peak period or peak period, and SOC ≥ 80%, the microgrid system is controlled to switch the state of the energy storage device to discharge, and the discharge power = P load -P pv ; If the time period is a peak period or peak period, and SOC < 80%, the microgrid system is controlled to switch the state of the energy storage device to standby; if the time period is a normal period, the microgrid system is switched to the mains power supply mode, and after the microgrid system is stable, the state of the energy storage device is switched to charging, and the charging power = P load -P pv .

[0018] Furthermore, when the time period is not a low-peak electricity price period and the weather type is cloudy, the microgrid system is first controlled to switch the photovoltaic system to constant power generation; then the SOC value is determined. If SOC ≥ 80%, the power of the photovoltaic system is reduced so that 0.5P load =P pv , until SOC = 50%, then increase the power of the photovoltaic system so that P load =P pv , and at the same time change the control algorithm of the energy storage device to smooth the fluctuation of the photovoltaic system, and the power of the energy storage device = P load -P pv When the power value is positive, the energy storage device is in a charging state, and when the power value is negative, the energy storage device is in a discharging state.

[0019] Furthermore, if SOC < 80%, the power of the photovoltaic system is first reduced so that P load =P pv ; Then determine the time period of the microgrid system. If it is a peak period or a peak period, control the microgrid system to smooth the power through the city power; if it is a normal period, control the energy storage device to quickly charge to SOC = 50%, and then change the control algorithm of the energy storage device to smooth the fluctuation of the photovoltaic system.

[0020] Solution 2

[0021] A photovoltaic storage microgrid control system based on load fluctuation is used to execute a photovoltaic storage microgrid control method based on load fluctuation as described in Scheme 1; it includes a collection module and a control module; the collection module is used to collect weather data and the SOC of the energy storage battery in the microgrid system; and collects real-time operation data of the microgrid system in real time, the real-time operation data includes load power P load , Photovoltaic power generation power P pv and real time t s The control module is used to execute corresponding control actions for the microgrid system according to a preset judgment strategy.

[0022] The working principle and advantages of the present invention are:

[0023] The present invention provides a photovoltaic energy storage microgrid control method and system based on load fluctuation, which can effectively improve the photovoltaic energy storage income while maintaining the stable operation of the microgrid system. The key point is that - first, this solution specifically collects the real-time operation data of the microgrid system including the load power as a data reference. Compared with the traditional control algorithm, the traditional solution often achieves the stability of the microgrid system by smoothing the power fluctuations generated by photovoltaic power generation through energy storage or load removal. The biggest problem with this type of method is that it ignores the importance of the load. In the actual operation process, ensuring the power supply to the load is the top priority; this solution uses the load power as a reference for adjusting the output of each power generation unit of the microgrid system, which can give priority to the load power demand, can improve user satisfaction from the root, and reduce the indirect economic losses or safety risks caused by service interruptions.

[0024] Secondly, in the strategic operation of this solution, the photovoltaic control algorithm is changed to smooth out fluctuations through the supplement of AC power, which can reduce the number of charge and discharge times of the energy storage device, while ensuring system stability and helping to improve the economic benefits of the overall system.

[0025] Compared with traditional control algorithms, traditional solutions mainly use energy storage to smooth out the fluctuations of photovoltaic power and load. Therefore, energy storage will frequently perform charging and discharging actions, which will reduce the service life of the equipment and there is also the problem of being unable to ensure the stability of the system. In addition, in traditional solutions, energy storage mostly plays the role of smoothing power during the day, and photovoltaic power will only produce large energy fluctuations under specific weather conditions (cloudy), and other conditions are basically stable. At this time, energy storage does not generate any economic benefits. However, this solution does not have such problems. When the photovoltaic power is unstable, it is smoothed by supplementing the mains power, reducing the participation of energy storage devices. And when the photovoltaic power is stable, the energy storage is controlled to perform peak-valley arbitrage operation, shortening the system investment return cycle, which can effectively increase the overall benefits of the system.

[0026] In summary, this solution can not only better cope with various complex working conditions, but also significantly improve user experience, reduce unnecessary economic losses, and improve the economic benefits of the system, thereby achieving more efficient and reliable microgrid operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of a microgrid system layout of an embodiment of a photovoltaic energy storage microgrid control method and system based on load fluctuation of the present invention;

[0028] Figure 2 The present invention is a method flow chart of a method and system embodiment of a photovoltaic energy storage microgrid control method based on load fluctuation. DETAILED DESCRIPTION

[0029] The following is a further detailed description through specific implementation methods:

[0030] The embodiment is basically as shown in the attached Figure 2 As shown: A method for controlling a photovoltaic energy storage microgrid based on load fluctuations, comprising the following steps:

[0031] Step 1: Collect weather data and the SOC of the energy storage battery in the microgrid system; and collect real-time operation data of the microgrid system in real time, the real-time operation data includes load power P load , Photovoltaic power generation power P pv and real time t s .

[0032] like Figure 1 As shown, the components of the microgrid system include energy storage devices, distributed energy and loads; the energy storage battery is arranged in the energy storage device; the distributed energy includes a photovoltaic system (including photovoltaic panels, photovoltaic inverters and other components). The microgrid system is connected to the mains through a power distribution room and the like. The weather data includes cloud cover, sunshine hours, visibility, radiation intensity, temperature, humidity, wind speed, wind direction, precipitation type, etc.

[0033] In this embodiment, weather data can be obtained through public meteorological websites; the SOC of the energy storage battery is obtained through the battery management system of the energy storage device; in the microgrid system, a data acquisition component is also installed, and the real-time operation data of the microgrid system is obtained through the data acquisition component. The data acquisition component can adopt an existing SCADA system or other data acquisition modules.

[0034] Step 2: Execute corresponding control actions for the microgrid system according to the preset judgment strategy.

[0035] The preset judgment strategy and corresponding control action include: according to the real-time time t s Determine the time period of the microgrid system; determine the weather type of the microgrid system based on weather data; combine the time period, weather type, SOC and real-time operation data to control the microgrid system to switch the status of its corresponding components to standby, power generation, charging or discharging.

[0036] The time periods include valley electricity price periods and non-valley electricity price periods; the non-valley electricity price periods include peak periods, peak periods and normal periods. The weather types include cloudy types and non-cloudy types. Specifically, the peak period refers to the period of time in a day when the electricity demand is the highest and the electricity price is the highest; the peak period follows the peak period, and although the electricity demand in this period is lower than that in the peak period, it is still at a relatively high level, and the electricity price is slightly lower than that in the peak period; the electricity demand in normal periods is relatively stable, which is neither a peak nor a peak period, nor a valley period, and the electricity price is between the peak and valley periods. In this embodiment, the division of valley electricity price periods and non-valley electricity price periods can be set with reference to the electricity price pricing standards of the area where the microgrid system is located, such as setting 9:00 to 11:00 a.m. and 5:00 to 7:00 p.m. on weekdays as peak periods, etc.

[0037] When the period is a low-valley electricity price period and SOC>20%, the microgrid system is controlled to switch the state of the energy storage device to discharge until SOC≤20%; when the period is a low-valley electricity price period and SOC≤20%, the energy storage device is controlled to stop discharging, and the microgrid system is switched to the mains power supply mode, and the state of the energy storage device is switched to charging after the microgrid system is stable.

[0038] When the period is not a low-peak electricity price period, and P pv >P load , and the weather type is non-cloudy, if SOC ≥ 80%, the microgrid system is controlled to switch the state of the photovoltaic system from MPPT power generation to constant power generation; if SOC < 80%, the photovoltaic system is controlled to maintain MPPT power generation, and the state of the energy storage device is controlled to switch to charging to absorb excess electric energy; the charging power of the energy storage device = P pv -P load .

[0039] When P pv <P load , and the weather type is non-cloudy, if the time period is a peak period or a peak period, and SOC ≥ 80%, the microgrid system is controlled to switch the state of the energy storage device to discharge to achieve peak-valley arbitrage, and the discharge power = P load -P pv ; If the time period is a peak period or peak period, and SOC < 80%, the microgrid system is controlled to switch the state of the energy storage device to standby; if the time period is a normal period, the microgrid system is switched to the mains power supply mode, and after the microgrid system is stable, the state of the energy storage device is switched to charging, and the charging power = P load -P pv .

[0040] When the time period is not a low-peak electricity price period and the weather type is cloudy, the microgrid system is first controlled to switch the photovoltaic system to constant power generation; then the SOC value is determined. If SOC ≥ 80%, the power of the photovoltaic system is reduced so that 0.5P load =P pi , until SOC = 50%, then increase the power of the photovoltaic system so that P load =P pv At the same time, the control algorithm of the energy storage device is changed to smooth the fluctuation of the photovoltaic system. Specifically, the bus voltage of the microgrid system is detected. When the bus voltage fluctuates due to the fluctuation of photovoltaic power generation, the energy storage device is controlled to balance the voltage through charging and discharging. When the voltage is high, the energy storage device charges or absorbs reactive power, and when the voltage is low, the energy storage device discharges or releases reactive power. In this process, the power of the energy storage device = P load -P pv When the power value is positive, the energy storage device is in a charging state, and when the power value is negative, the energy storage device is in a discharging state.

[0041] If SOC < 80%, first reduce the power of the photovoltaic system so that P load =P pv ; Then determine the time period in which the microgrid system is located. If the time period is a peak period or a peak period, control the microgrid system to smooth the power through the mains; if the time period is a normal period, control the energy storage device to quickly charge to SOC = 50% (that is, switch the microgrid system to the mains power supply mode, and after the microgrid system is stable, switch the state of the energy storage device to charging until it is charged to SOC = 50%), and then change the control algorithm of the energy storage device to smooth the fluctuation of the photovoltaic system; specifically, detect the bus voltage of the microgrid system, when the fluctuation of photovoltaic power generation causes the bus voltage to fluctuate, control the energy storage device to balance the voltage through charging and discharging; when the voltage is high, the energy storage device charges or absorbs reactive power, and when the voltage is low, the energy storage device discharges or releases reactive power.

[0042] This embodiment also provides a photovoltaic energy storage microgrid control system based on load fluctuation, which is used to execute a photovoltaic energy storage microgrid control method based on load fluctuation as described above; it includes a collection module and a control module; the collection module is used to collect weather data and the SOC of the energy storage battery in the microgrid system; and collects real-time operation data of the microgrid system in real time, and the real-time operation data includes load power P load , Photovoltaic power generation power P pv and real time t s The control module is used to execute corresponding control actions for the microgrid system according to a preset judgment strategy.

[0043] The present embodiment provides a method and system for controlling a photovoltaic-storage microgrid based on load fluctuations, which can effectively improve photovoltaic-storage revenue and maximize photovoltaic-storage revenue while maintaining stable operation of the microgrid system.

[0044] The above is only an embodiment of the present invention. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field are aware of all the common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement the scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for the ordinary technicians in the relevant field to implement this application. It should be pointed out that for the technicians in this field, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A method for controlling a photovoltaic energy storage microgrid based on load fluctuation, characterized in that: The following steps are involved: Step 1, collecting weather data and the SOC of the energy storage battery in the microgrid system; And real-time collection of microgrid system real-time operation data, the real-time operation data includes load power P load , Photovoltaic power generation power P pv and real time t s ; Step 2: Execute corresponding control actions for the microgrid system according to the preset judgment strategy; The preset judgment strategy and corresponding control action include: according to the real-time time t s Determine the time period of the microgrid system; determine the weather type of the microgrid system based on weather data; combine the time period, weather type, SOC and real-time operation data to control the microgrid system to switch the status of its corresponding components to standby, power generation, charging or discharging.

2. A method for controlling a photovoltaic energy storage microgrid based on load fluctuation according to claim 1, characterized in that: The components of the microgrid system include an energy storage device, distributed energy and load; the energy storage battery is arranged in the energy storage device; and the distributed energy includes a photovoltaic system.

3. A method for controlling a photovoltaic energy storage microgrid based on load fluctuation according to claim 2, characterized in that: The time periods include off-peak electricity price periods and non-off-peak electricity price periods; the non-off-peak electricity price periods include peak periods, peak periods and normal periods.

4. The method for controlling a photovoltaic energy storage microgrid based on load fluctuation according to claim 3 is characterized in that: The weather type includes a cloudy type and a non-cloudy type.

5. The control method of a photovoltaic energy storage microgrid based on load fluctuation according to claim 3 is characterized in that: When the period is a low-valley electricity price period and SOC>20%, the microgrid system is controlled to switch the state of the energy storage device to discharge until SOC≤20%; when the period is a low-valley electricity price period and SOC≤20%, the energy storage device is controlled to stop discharging, and the microgrid system is switched to the mains power supply mode, and the state of the energy storage device is switched to charging after the microgrid system is stable.

6. A method for controlling a photovoltaic energy storage microgrid based on load fluctuation according to claim 4, characterized in that: When the period is not a low-peak electricity price period, and P pv >P load , and the weather type is non-cloudy, if SOC ≥ 80%, the microgrid system is controlled to switch the state of the photovoltaic system from MPPT power generation to constant power generation; if SOC < 80%, the photovoltaic system is controlled to maintain MPPT power generation, and the state of the energy storage device is controlled to switch to charging to absorb excess electric energy; the charging power of the energy storage device = P pv -P load .

7. The method for controlling a photovoltaic energy storage microgrid based on load fluctuation according to claim 4, characterized in that: When P pv <P load , and the weather type is non-cloudy, if the time period is a peak period or peak period, and SOC ≥ 80%, the microgrid system is controlled to switch the state of the energy storage device to discharge, and the discharge power = P load -P pv ; If the time period is a peak period or peak period, and SOC < 80%, the microgrid system is controlled to switch the state of the energy storage device to standby; if the time period is a normal period, the microgrid system is switched to the mains power supply mode, and after the microgrid system is stable, the state of the energy storage device is switched to charging, and the charging power = P load -P pv .

8. The method for controlling a photovoltaic energy storage microgrid based on load fluctuation according to claim 4 is characterized in that: When the time period is not a low-peak electricity price period and the weather type is cloudy, the microgrid system is first controlled to switch the photovoltaic system to constant power generation; then the SOC value is determined. If SOC ≥ 80%, the power of the photovoltaic system is reduced so that 0.5P load =P pv , until SOC = 50%, then increase the power of the photovoltaic system so that P load =P pv , and at the same time change the control algorithm of the energy storage device to smooth the fluctuation of the photovoltaic system, and the power of the energy storage device = P load -P pv When the power value is positive, the energy storage device is in a charging state, and when the power value is negative, the energy storage device is in a discharging state.

9. A method for controlling a photovoltaic energy storage microgrid based on load fluctuation according to claim 8, characterized in that: If SOC < 80%, first reduce the power of the photovoltaic system so that P load =P pv ; Then determine the time period of the microgrid system. If it is a peak period or a peak period, control the microgrid system to smooth the power through the city power; if it is a normal period, control the energy storage device to quickly charge to SOC = 50%, and then change the control algorithm of the energy storage device to smooth the fluctuation of the photovoltaic system.

10. A photovoltaic energy storage microgrid control system based on load fluctuation, characterized in that: Used to execute a method for controlling a photovoltaic energy storage microgrid based on load fluctuations as described in any one of claims 1 to 9; comprising a collection module and a control module; the collection module is used to collect weather data and the SOC of the energy storage battery in the microgrid system; and to collect real-time operation data of the microgrid system in real time, the real-time operation data including the load power P load , Photovoltaic power generation power P pv and real time t s ; The control module is used to execute corresponding control actions for the microgrid system according to a preset judgment strategy.

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