A method, device and system for preventing reverse flow and overloading of a light storage power station

Abstract

The application relates to a light storage power station anti-reverse flow and anti-overload method, device and system, which comprises the following steps: obtaining a first power generation period, a second power generation period and photovoltaic output power based on meteorological data, local time period electricity price schemes and a preset intensity; predicting load power and storage energy allowed charging power; controlling the power grid to charge the storage energy device in the first power generation period, controlling the photovoltaic power generation device and the power grid to charge the storage energy device in the second power generation period; comparing an anti-reverse flow power threshold value and power grid output power, adjusting photovoltaic output power and storage energy output power; setting a maximum demand limit value, a demand control margin value and a power reduction margin value, and adjusting the storage energy allowed charging power of the storage energy device. The application effectively guarantees that the light storage power station prevents reverse flow and overload under the condition that the electric energy of the photovoltaic power generation device is fully utilized, reduces the operation cost of the power station, and guarantees stable circulation of the power station electric energy.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of light storage, in particular to a light storage power station anti-reverse flow and anti-overload method, device and system. BACKGROUND

[0002] The light storage power station is a facility combining photovoltaic power generation and energy storage system, which is widely used in factories with high power demand. The photovoltaic power generation device converts solar energy into electric energy during the day, and the electric energy is first supplied to the factory for power consumption. The excess electric energy is stored in the energy storage device. At night or during the period when the power grid price is high, the energy storage device releases electric energy to supply the factory for power consumption, effectively reducing the cost of power consumption of the factory.

[0003] During the operation of the light storage power station, the photovoltaic output electric energy is prone to be excessive, resulting in reverse flow to the power grid, and the charging power of the energy storage system is excessive, resulting in overload of the total power of the enterprise. In the prior art, the photovoltaic power generation power is reduced in real time according to the detected photovoltaic power generation device and power grid power data to prevent reverse flow, and the maximum demand control technology is used to prevent overload, but in this way, the energy of the photovoltaic power generation device cannot be fully utilized, resulting in waste of resources, and the maximum demand control technology only simply compares the power grid power data and the maximum demand value, and reduces the charging power of the energy storage device in real time, without reserving a suitable device response time and tolerance value, resulting in unstable demand control and easy occurrence of the phenomenon of exceeding the maximum demand. SUMMARY

[0004] The application provides a light storage power station anti-reverse flow and anti-overload method, device and system.

[0005] The light storage power station anti-reverse flow and anti-overload method, device and system provided by the application adopt the following technical scheme:

[0006] A light storage power station anti-reverse flow and anti-overload method comprises the following steps:

[0007] S1: acquiring meteorological data, local time-of-day electricity price scheme and preset intensity, obtaining a first power generation period, a second power generation period and photovoltaic output power according to the meteorological data and the local time-of-day electricity price scheme;

[0008] S2: acquiring user historical data, and predicting load power and energy storage allowed charging power in the next 24 hours according to the user historical data;

[0009] S3: controlling the power grid to charge the energy storage device with the energy storage allowed charging power in the first power generation period, and controlling the photovoltaic power generation device and the power grid to charge the energy storage device with the sum of the photovoltaic output power and the power grid output power not greater than the energy storage allowed charging power in the second power generation period in the order of priority of the photovoltaic power generation device;

[0010] S4: preset a maximum demand limit value according to the user's last month electricity consumption, set a demand control margin value and a power reduction margin value, and adjust the energy storage allowed charging power according to the maximum demand limit value, the demand control margin value and the power reduction margin value;

[0011] S5: after the energy storage device is fully charged, control at least one of the photovoltaic power generation device, the energy storage device and the power grid to output power to the load, set an anti-reverse load control mode, the anti-reverse load control mode includes setting an anti-reverse flow power threshold and a power increase threshold, when the photovoltaic output power and the energy storage output power are less than the load power, purchase power from the power grid to carry the load, and obtain the power grid output power on the main electric meter, compare the power grid output power and the anti-reverse flow power threshold, when the power grid output power is less than the anti-reverse flow power threshold, preferentially reduce the energy storage output power, and then reduce the photovoltaic output power, until the power grid output power exceeds the power increase threshold.

[0012] Preferably, the meteorological data is the light intensity data within the next 24 hours; the local time-of-use electricity price scheme is the distribution scheme of peak electricity period and valley electricity period within the next 24 hours; the first power generation period is the period in which the light intensity is less than a preset intensity in the valley electricity period; the second power generation period is the period in which the light intensity is greater than a preset intensity in the valley electricity period; and the photovoltaic output power is the average power generation of the photovoltaic power generation device per hour in the second power generation period.

[0013] Preferably, in the order of the photovoltaic power generation device preferentially generating power, controlling the photovoltaic power generation device and the power grid to charge the energy storage device in the second power generation period with the sum of the photovoltaic output power and the power grid output power not greater than the energy storage allowed charging power includes:

[0014] when the difference between the photovoltaic output power and the load power is greater than 0 kW and less than the energy storage allowed charging power, controlling the photovoltaic power generation device and the power grid to charge the energy storage device in the second power generation period with the sum of the photovoltaic output power and the power grid output power not greater than the energy storage allowed charging power;

[0015] when the difference between the photovoltaic output power and the load power is greater than or equal to the energy storage allowed charging power, controlling the photovoltaic power generation device to charge the energy storage device with the energy storage allowed charging power, and the power grid output power is 0 kW.

[0016] Preferably, S4: preset a maximum demand limit value according to the user's last month electricity consumption, set a demand control margin value and a power reduction margin value, and adjust the energy storage allowed charging power according to the maximum demand limit value, the demand control margin value and the power reduction margin value includes:

[0017] S41: preset the initial maximum demand limit value according to the user's last month situation;

[0018] S42: when the sum of the load power and the energy storage allowed charging power is greater than the difference between the maximum demand limit value and the demand control margin value, reduce the energy storage allowed charging power until the sum of the load power and the energy storage allowed charging power is less than or equal to the difference between the maximum demand limit value and the demand control margin value;

[0019] S43: when the load power is greater than or equal to the difference between the maximum demand limit value and the demand control margin value, adjust the energy storage allowed charging power to 0 kW;

[0020] S44: when the load power is less than the difference between the maximum demand limit value and the demand control margin value and the power reduction margin value in turn, adjust the energy storage allowed charging power to meet the condition that the sum of the load power and the energy storage allowed charging power is less than or equal to the difference between the maximum demand limit value and the demand control margin value.

[0021] Preferably, S5: after the energy storage device is fully charged, control at least one of the photovoltaic power generation device, the energy storage device and the power grid to output power to the load, set an anti-reverse load control mode, the anti-reverse load control mode includes setting an anti-reverse flow power threshold and a power increase threshold, when the photovoltaic output power and the energy storage output power are less than the load power, purchase power from the power grid to load, and obtain the power grid output power on the main electric meter, and compare the power grid output power and the anti-reverse flow power threshold, including:

[0022] Obtain the output power of each phase of the three-phase power of the power grid on the main electric meter connected with the main transformer, and compare the anti-reverse flow power threshold and the output power of each phase one by one, when the output power of any one phase of the three-phase power of the power grid is less than the anti-reverse flow power threshold, then preferentially reduce the energy storage output power, and then reduce the photovoltaic output power, until the output power of each phase of the power grid exceeds the power increase threshold.

[0023] Preferably, S5: after the energy storage device is fully charged, control at least one of the photovoltaic power generation device, the energy storage device and the power grid to output power to the load, set an anti-reverse load control mode, the anti-reverse load control mode includes setting an anti-reverse flow power threshold and a power increase threshold, when the photovoltaic output power and the energy storage output power are less than the load power, purchase power from the power grid to load, and obtain the power grid output power on the main electric meter, and compare the power grid output power and the anti-reverse flow power threshold, including:

[0024] Obtaining the total output power of the power grid on the main electric meter connected to the main transformer, and comparing the anti-backflow power threshold value with the total output power of the power grid, when the total output power of the power grid is less than the anti-backflow power threshold value, then the energy storage output power is reduced first, and then the photovoltaic output power is reduced, until the total output power of the power grid exceeds the power increase threshold value.

[0025] A photovoltaic and energy storage power station anti-backflow and anti-overload device for any of the above photovoltaic and energy storage power station anti-backflow and anti-overload methods, comprising:

[0026] A first prediction module for obtaining meteorological data and local time-of-use electricity price scheme, and obtaining a first power generation time period, a second power generation time period and photovoltaic output power according to the meteorological data and the local time-of-use electricity price scheme;

[0027] A second prediction module for obtaining user historical data, and predicting load power and energy storage allowed charging power according to the user historical data;

[0028] A central processing module connected to the first prediction module and the second prediction module;

[0029] A first control module connected to the central processing module, for controlling the power grid to charge the energy storage device with the energy storage allowed charging power in the first power generation time period, and controlling the photovoltaic power generation device and the power grid to charge the energy storage device with the sum of photovoltaic output power and power grid output power not greater than the energy storage allowed charging power in the second power generation time period in the order of the photovoltaic power generation device giving priority to power generation;

[0030] A second control module for presetting a maximum demand limit value according to user last month electricity consumption, setting a demand control margin value and a power reduction margin value, and adjusting the energy storage allowed charging power according to the maximum demand limit value, the demand control margin value and the power reduction margin value;

[0031] A third control module for controlling at least one of the photovoltaic power generation device, the energy storage device and the power grid to output electric energy to the load after the energy storage device is fully charged, setting an anti-backflow load carrying control mode, the anti-backflow load carrying control mode comprising setting an anti-backflow power threshold value and a power increase threshold value, when the photovoltaic output power and the energy storage output power are less than the load power, purchasing electricity from the power grid to carry the load, and obtaining the power grid output power on the main electric meter, comparing the power grid output power with the anti-backflow power threshold value, when the power grid output power is less than the anti-backflow power threshold value, reducing the energy storage output power first, and then reducing the photovoltaic output power, until the power grid output power exceeds the power increase threshold value.

[0032] The anti-reverse flow and anti-overload system of the light storage power station comprises the anti-reverse flow and anti-overload device, and further comprises a photovoltaic power generation device, a power grid, a load, an energy storage device, a bus, a main transformer, a sub-transformer, a main electric meter and a sub-electric meter.

[0033] In summary, the present application comprises at least one of the following beneficial technical effects:

[0034] The present application predicts the first power generation period, the second power generation period and the photovoltaic output power, and based on the first power generation period, the second power generation period and the photovoltaic output power, fully utilizes the electric energy of the photovoltaic power generation device, charges the energy storage device with load at a low purchase cost, and ensures that the energy storage device is fully charged, which is beneficial to subsequent energy storage device power generation with load. By monitoring the power grid output power and comparing with the anti-reverse flow power threshold, the output power of the energy storage device and the photovoltaic power generation device is adjusted in real time to ensure that there is no reverse flow to the power grid. By setting the maximum demand limit value, the demand control margin value and the power reduction margin value, the charging power of the energy storage is adjusted in real time to ensure that the photovoltaic power generation device and the power grid do not easily appear overload phenomenon in the process of charging the energy storage device under the condition of anti-reverse flow. The present application effectively ensures that the light storage power station fully utilizes the electric energy of the photovoltaic power generation device under the condition of anti-reverse flow and anti-overload, reduces the cost of power station operation, and ensures the stability, compliance and circulation of the power station electric energy self-generation and self-use. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a schematic diagram of the overall structure of the anti-reverse flow and anti-overload system of the light storage power station in the preferred embodiment of the present application.

[0036] Figure 2 is a flowchart of the anti-reverse flow and anti-overload method of the light storage power station in the preferred embodiment of the present application.

[0037] Figure 3 is a flowchart of the specific execution method of step S5 in the preferred embodiment of the present application.

[0038] Figure 4 is a schematic diagram of the overall structure of the anti-reverse flow and anti-overload device of the light storage power station in the preferred embodiment of the present application.

[0039] Reference signs: 10, photovoltaic power generation device; 101, photovoltaic array; 102, photovoltaic inverter; 20, power grid; 30, load; 40, energy storage device; 50, bus; 60, main transformer; 70, sub-transformer; 80, main electric meter; 90, sub-electric meter; 110, first prediction module; 120, second prediction module; 130, central processing module; 140, first control module; 150, second control module; 160, third control module. DETAILED DESCRIPTION

[0040] The present application will be further described in detail below with reference to the accompanying drawings.

[0041] The application provides a light storage power station anti-reverse flow and anti-overload method, device and system. In order to facilitate understanding of the light storage power station anti-reverse flow and anti-overload method provided by the embodiment of the application, first, the application of the light storage power station anti-reverse flow and anti-overload system is described.

[0042] Embodiment 1

[0043] A light storage power station anti-reverse flow and anti-overload system, referring to Figure 1 The system comprises a photovoltaic power generation device 10, a power grid 20, a load 30, an energy storage device 40, a bus 50, a main transformer 60, N sub transformers 70, a main electric meter 80, a sub electric meter 90 and a light storage power station anti-reverse flow and anti-overload device. The light storage power station anti-reverse flow and anti-overload device is used to execute the light storage power station anti-reverse flow and anti-overload method provided by any embodiment of the application. The light storage power station anti-reverse flow and anti-overload method is explained in subsequent embodiments.

[0044] The power grid 20 is connected to the bus 50 through the main transformer 60. The N sub transformers 70 are connected in parallel along the length direction of the bus 50 and are connected to the bus 50. The N sub transformers 70 are located on the low-voltage side of the main transformer 60. The photovoltaic power generation device 10 comprises a photovoltaic array 101 and a photovoltaic inverter 102. The output end of the photovoltaic inverter 102 is connected to the first sub transformer 70. The energy storage device 40 is connected to the Nth sub transformer 70. The number of the load 30 is the same as the number of the sub transformer 70, both of which are N. The N loads 30 are connected to the N sub transformers 70 one by one.

[0045] Specifically, the first sub-transformer 70 is located at the head end of the busbar 50, the first load 30 is connected to the first sub-transformer 70, and the photovoltaic inverter 102 is connected to the first sub-transformer 70 through the first parallel flow point, N sub-transformers 70 are arranged along the head end to the tail end of the busbar, the Nth sub-transformer 70 is close to the tail end of the busbar 50, the Nth load 30 is connected to the Nth sub-transformer 70, and the energy storage device 40 is connected to the Nth sub-transformer 70 through the second parallel flow point, the main electric meter 80 is connected between the main transformer 60 and the busbar 50, and the number of sub-electric meters 90 is N+2, wherein the first sub-electric meter 90 is connected between the first parallel flow point and the first sub-transformer 70, the second sub-electric meter 90 is connected between the first sub-electric meter 90 and the photovoltaic inverter 102, the third sub-electric meter 90 to the Nth sub-electric meter 90 are connected one by one with the second sub-transformer 70 to the N-1th sub-transformer 70, the N+1th sub-electric meter 90 is connected between the Nth sub-transformer 70 and the second parallel flow point, and the N+2th sub-electric meter 90 is connected between the Nth sub-electric meter 90 and the energy storage device 40, the first sub-electric meter 90 is used to detect the power of the electric energy of the photovoltaic power generation device 10 flowing to the busbar 50 after the electric energy is output to the load 30 connected to the same sub-electric meter 90, the second sub-electric meter 90 is used to detect the photovoltaic output power of the photovoltaic power generation device 10, the third sub-electric meter 90 to the Nth sub-electric meter 90 are respectively used to detect the power of the corresponding load 30 when the load 30 connected to the same sub-electric meter 90 is driven, the N+1th sub-electric meter 90 is used to detect the total power flowing to the load 30 and the energy storage device 40 connected to the same sub-electric meter 90 in the case of charging the energy storage device 40, and the N+2th sub-electric meter 90 is used to detect the energy storage charging power, in the case of discharging the energy storage device 40, if the output power of the energy storage device is sufficient to drive the load 30 connected to the same sub-electric meter 90, the N+1th sub-electric meter 90 is used to detect the power of the electric energy flowing to the busbar 50 after the energy storage device 40 drives the load 30 connected to the same sub-electric meter 90, if the output power of the energy storage device is insufficient to drive the load 30 connected to the same sub-electric meter 90, the N+1th sub-electric meter 90 is used to detect the power lacking for driving the load 30, and the N+2th sub-electric meter 90 is used to detect the output power of the energy storage device 40 in this state.

[0046] The anti-reverse flow and anti-overload device of the light storage power station is connected to the photovoltaic inverter 102, used to control the photovoltaic output power and prevent the occurrence of reverse flow, and is connected to the energy storage device 40, used to control the energy storage allowed charging power of the energy storage device 40 through the EMS of the energy storage device 40, and prevent the occurrence of overload.

[0047] Example 2

[0048] A method for preventing backflow and overload in a photovoltaic-storage power station is disclosed in the following embodiments, which will specifically illustrate the method for preventing backflow and overload executed by the anti-backflow and overload device in the photovoltaic-storage power station.

[0049] like Figure 1 and 2 As shown, the method for preventing backflow and overload includes:

[0050] S1. Obtain meteorological data, local electricity price schemes for each time period, and preset intensity. Based on the meteorological data and local electricity price schemes for each time period, obtain the first power generation period, the second power generation period, and the photovoltaic output power.

[0051] Specifically, the meteorological data is the solar intensity data facing the photovoltaic array 101 in the next 24 hours. The local electricity price scheme for each time period is the distribution scheme of peak and off-peak electricity periods in the next 24 hours. The off-peak electricity period refers to the period when the electricity price of the power grid 20 is the lowest relative to other periods, and the peak electricity period refers to the period when the electricity price is higher than the off-peak electricity price. The electricity price scheme for each time period is different in each region. Therefore, the electricity price scheme for each time period mentioned in this application is the scheme specified in the region where the application site of the photovoltaic energy storage power station anti-reverse current and anti-overload method, device and system provided in this application is located.

[0052] The first power generation period is the period during off-peak hours when the light intensity is less than the preset intensity. The second power generation period is the period during off-peak hours when the light intensity is greater than the preset intensity. The photovoltaic output power is the average power generation of the photovoltaic power generation device 10 per hour during the second power generation period. Specifically, the preset intensity is the preset light intensity, which is greater than 0 Lux. Since the light intensity at night is not necessarily equal to 0 Lux, but is very low compared to the light intensity after sunrise, it can be ignored. Therefore, a preset intensity is set to indicate that the output power of the photovoltaic power generation device 10 can be ignored during the period when the light intensity is lower than the preset intensity.

[0053] S2. Obtain user historical data and predict the load power and allowable charging power of energy storage for the next 24 hours based on the user historical data.

[0054] Specifically, the user's historical data includes the energy storage installed capacity and the historical load power data of N loads 30 in the past 24 hours. The allowable charging power of energy storage required to fully charge the energy storage installed capacity during the first and second power generation periods is calculated, and the load power of the next 24 hours is referenced from the load power of the past 24 hours.

[0055] S3. Control the grid 20 to charge the energy storage device 40 with the allowed charging power of the energy storage device during the first power generation period, and control the photovoltaic power generation device 10 and the grid 20 to charge the energy storage device 40 with the sum of the photovoltaic output power and the grid output power not exceeding the allowed charging power of the energy storage device during the second power generation period, in the order of priority power generation of the photovoltaic power generation device 10.

[0056] Specifically, during the first power generation period, the power output of the photovoltaic power generation device 10 is less than the preset power, so the load 30 is driven by the grid 20. While carrying the load, the grid 20 charges the energy storage device 40 with the power allowed for energy storage charging. At the moment the first power generation period ends, the grid 20 stops charging the energy storage device 40, and the energy storage device 40 is in a standby state of neither charging nor discharging. During the second power generation period, the order of priority power generation for the photovoltaic power generation device 10 is switched. A time period is reserved between the first and second power generation periods for the energy storage device 40 to switch from the charging state to the standby state and from the standby state to the power generation state. Priority power generation of the photovoltaic power generation device 10 means that the photovoltaic power generation device 10 is given priority in carrying the load and the excess electrical energy after being carried is transferred to the energy storage device 40. If the photovoltaic output power of device 10 is insufficient to charge energy storage device 40 at the allowed charging power, i.e., the difference between photovoltaic output power and load power is greater than 0 kW and less than the allowed charging power, then electricity is purchased from grid 20 to fill the missing power. During the second power generation period, photovoltaic power generation device 10 and grid 20 are controlled to charge energy storage device 40 with the sum of photovoltaic output power and grid output power not exceeding the allowed charging power. When the difference between photovoltaic output power and load power is greater than or equal to the allowed charging power, photovoltaic power generation device 10 is controlled to charge energy storage device 40 at the allowed charging power, and grid output power is 0 kW. In this way, the electrical energy of photovoltaic power generation device 10 can be fully utilized to fully charge energy storage device 40 at a lower electricity purchase cost than existing technologies.

[0057] S4. Based on the user's electricity consumption in the previous month, preset the maximum demand limit, and set the demand control margin and power reduction margin. Adjust the allowable charging power of the energy storage device 40 according to the maximum demand limit, demand control margin and power reduction margin.

[0058] like Figure 3 As shown, specifically, including:

[0059] S41. Preset the initial maximum demand limit based on the user's situation last month.

[0060] The maximum demand limit is the sum of the demand of the load 30 and the energy storage device 40 under charging conditions. Since the load 30 will change with time according to the demand of the plant area where the method of this application is applied, the maximum demand limit is a dynamic value calculated by the slip-type maximum demand calculation method. It is calculated once every 15 minutes, and the value calculated each time is compared with the previous value, and the larger value is taken as the maximum demand limit.

[0061] S42. When the sum of the load power and the allowable charging power of the energy storage is greater than the difference between the maximum demand limit and the demand control margin, reduce the allowable charging power of the energy storage until the sum of the load power and the allowable charging power of the energy storage is less than or equal to the difference between the maximum demand limit and the demand control margin.

[0062] S43. When the load power is greater than or equal to the difference between the maximum demand limit and the demand control margin, adjust the allowable charging power of the energy storage to 0kW and put it in standby mode.

[0063] S44. When the load power is less than the difference between the maximum demand limit and the demand control margin and the power reduction margin, adjust the allowable charging power of the energy storage so that the sum of the load power and the allowable charging power of the energy storage is less than or equal to the difference between the maximum demand limit and the demand control margin.

[0064] In this way, setting a demand control margin value allows for fluctuations in load power and allowable charging power of energy storage, providing sufficient response time for demand control. Setting a power reduction margin value prevents frequent activation of demand control when the total power fluctuates around the demand control critical point.

[0065] S5. After the energy storage device is fully charged, set the anti-reverse load control mode and control at least one of the photovoltaic power generation device 10, energy storage device 40 and grid 20 to output electrical energy to drive the load 30. Set the anti-reverse power threshold and the power increase threshold. When the photovoltaic output power and the energy storage output power are less than the load power, purchase electricity from the grid to drive the load and obtain the grid output power on the main meter 80. Compare the grid output power with the anti-reverse power threshold. When the grid output power is less than the anti-reverse power threshold, reduce the energy storage output power first, then reduce the photovoltaic output power, until the grid output power exceeds the power increase threshold.

[0066] Specifically, the anti-reverse current power threshold is a preset grid output power used to prevent the reverse flow of electrical energy from the photovoltaic power generation device 10 and the energy storage device 40 to the grid 20, that is, to ensure that the grid 20 always outputs power greater than the anti-reverse current power threshold. Since the photovoltaic output power, energy storage output power, and load power will vary, when the sum of the photovoltaic output power, energy storage output power, and anti-reverse current power threshold is greater than or equal to the load power, the grid output power collected by the main meter 80 is equal to or less than the anti-reverse current power threshold, indicating that the photovoltaic power generation device 10 and the energy storage device 40... If the output power is too high and reverse current is about to flow back to the grid (20), the energy storage output power will be reduced first, followed by the photovoltaic output power. Since the energy storage device (40) needs to be recharged after discharging, the energy storage output power will be reduced first to save energy. If the energy storage output power is 0 and the grid output power is still less than the anti-reverse current power threshold, the photovoltaic output power will be reduced further until the grid output power exceeds the power escalation threshold. The power escalation threshold is a preset value and is greater than the anti-reverse current power threshold to prevent reverse current from flowing back to the grid when the grid output power is below the anti-reverse current power threshold. The power tolerance set by frequently activating anti-reverse current control when the power fluctuates is as follows: For example, the anti-reverse current power control threshold is set to 20kW, and the power increase threshold is set to 25kW. When the grid output power is less than 20kW, the anti-reverse current mechanism is triggered, reducing the output power of photovoltaic (PV) and / or energy storage until the grid output power is greater than 20kW. The load power and PV output power will fluctuate due to changes in user usage and sunlight intensity. If the load power increases by 3kW, making the grid output power 23kW, the PV and energy storage output power will not be adjusted since the grid output power is between the anti-reverse current power threshold and the power increase threshold. If the load power increases to more than 5kW, making the grid output power greater than the power increase threshold, the PV and / or energy storage output power will be increased to keep the grid output power within a range greater than the anti-reverse current power threshold. The setting of the power increase threshold provides a tolerance when the grid output power fluctuates around the anti-reverse current power threshold. When the grid output power increases, the frequency of adjustment of PV and energy storage output power is reduced, thereby reducing the calculated energy consumption.

[0067] The reverse current protection load control mode is either single-phase power reverse current protection control mode or total power reverse current protection control mode. The choice of mode depends on the user's needs. In the single-phase power reverse current protection control mode, the grid output power refers to the output power of each phase of the three-phase power grid 20. In this mode, the reverse current protection power threshold and the output power of each phase are compared one-to-one. The reverse current protection power threshold is the preset minimum output power of each phase of the grid 20, and the boost power threshold is the preset output power of each phase of the grid 20. When the output power of each phase of the three-phase power grid 20 is less than the reverse current protection power threshold, the energy storage output power is preferentially reduced. The output power is reduced, and then the photovoltaic output power is reduced until the output power of each phase of the three-phase power of the grid 20 exceeds the power increase threshold. In the total power anti-reverse control mode, the grid output power refers to the total output power of the three-phase grid 20. In this mode, the anti-reverse power threshold and the total output power of the grid are compared. The anti-reverse power threshold is the minimum value of the sum of preset output powers, and the power increase threshold is the total preset value. When the total output power of the grid 20 is less than the anti-reverse power threshold, the energy storage output power is reduced first, and then the photovoltaic output power is reduced until the total output power of the grid exceeds the power increase threshold.

[0068] Example 3

[0069] This application also provides a reverse current and overload protection device for a photovoltaic-storage power station, used to perform the above-mentioned reverse current and overload protection method for a photovoltaic-storage power station, including:

[0070] The first forecasting module 110 is connected to a meteorological data platform and to the central processing module 130. It is used to acquire meteorological data and local electricity price schemes for different time periods, and to obtain the first power generation period, the second power generation period, and the photovoltaic output power based on the meteorological data and local electricity price schemes for different time periods.

[0071] The second prediction module 120 is connected to the N+2nd sub-meter 90 and to the central processing module 130. It is used to acquire user historical data and predict load power and allowable charging power of energy storage based on the user historical data.

[0072] The central processing module 130 receives and processes data from the first prediction module 110 and the second prediction module 120, and is connected to a first control module 140, a second control module 150, and a third control module 160. The first control module 140 is connected to the power grid 20, the photovoltaic power generation device 10, and the energy storage device 40. It controls the power grid 20 to charge the energy storage device 40 during the first power generation period at the allowed charging power of the energy storage device, prioritizing the photovoltaic power generation device 10. During the second power generation period, it controls the photovoltaic power generation device 10 and the power grid 20 to charge the energy storage device 40 such that the sum of the photovoltaic output power and the grid output power does not exceed the allowed charging power of the energy storage device. The second control module 150 is connected to the energy storage device 40 and the main meter 80. It presets a maximum demand limit based on the user's electricity consumption from the previous month, and sets a demand control margin and a power reduction margin. The allowable charging power of the energy storage device 40 is adjusted by the quantity limit value, demand control margin value, and power reduction margin value. The third control module 160 is connected to the main meter 80, the grid 20, the photovoltaic inverter 102, and the energy storage device 40. It is used to obtain the grid output power of the main meter 80 and control at least one of the photovoltaic power generation device 10, the energy storage device 40, and the grid 20 to output electrical energy to the load 30. It sets an anti-reverse load control mode, which includes setting an anti-reverse current power threshold and a power increase threshold. When the photovoltaic output power and the energy storage output power are less than the load power, the load is carried by purchasing electricity from the grid 20 and obtaining the grid output power on the main meter 80. The grid output power is compared with the anti-reverse current power threshold. When the grid output power is less than the anti-reverse current power threshold, the energy storage output power is reduced first, and then the photovoltaic output power is reduced until the grid output power exceeds the power increase threshold.

[0073] This application predicts the first and second power generation periods and the photovoltaic output power. Based on these parameters, it fully utilizes the electrical energy of the photovoltaic power generation device 10 to charge the energy storage device 40 while it is under load, ensuring that the energy storage device 40 is fully charged. This facilitates subsequent power generation by the energy storage device 40. By comparing the grid output power and the anti-reverse current power threshold, the output power of the energy storage device 40 and the photovoltaic power generation device 10 is adjusted in real time to prevent reverse current from flowing back to the grid 20. By setting the maximum demand limit, demand control margin, and power reduction margin, the allowable charging power of the energy storage is adjusted in real time. This ensures that, under anti-reverse current conditions, the photovoltaic power generation device 10 and the grid 20 are less likely to experience overload during the charging process of the energy storage device 40. This effectively ensures that the photovoltaic power station can fully utilize the electrical energy of the photovoltaic power generation device 10 while preventing reverse current and overload, reducing the operating cost of the power station and ensuring the stability of the power station for self-consumption.

[0074] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for preventing reverse current and overload in a photovoltaic-storage power station, characterized in that, include: S1: Obtain meteorological data, local electricity price schemes for each time period, and preset intensity; based on the meteorological data and the local electricity price schemes for each time period, obtain the first power generation period, the second power generation period, and the photovoltaic output power, wherein the preset intensity is a preset light intensity and is greater than 0 Lux; S2: Obtain user historical data and predict the load power and allowable charging power of energy storage for the next 24 hours based on the user historical data; S3: Control the power grid (20) to charge the energy storage device (40) with the energy storage allowable charging power during the first power generation period, and control the photovoltaic power generation device (10) and the power grid (20) to charge the energy storage device (40) with the sum of photovoltaic output power and power grid output power not greater than the energy storage allowable charging power during the second power generation period, in the order of priority power generation of photovoltaic power generation device (10). S4: Based on the user's electricity consumption data from the previous month, a maximum demand limit is preset, and a demand control margin and a power reduction margin are set. The allowable charging power of the energy storage is adjusted according to the maximum demand limit, the demand control margin, and the power reduction margin, including: S41: Based on the user's situation last month, the initial maximum demand limit is preset. The maximum demand limit is the sum of the demand under the condition of load and energy storage device charging. It is calculated every 15 minutes. The value calculated each time is compared with the previous value, and the larger value is taken as the maximum demand limit. S42: When the sum of the load power and the allowable charging power of the energy storage is greater than the difference between the maximum demand limit and the demand control margin, reduce the allowable charging power of the energy storage until the sum of the load power and the allowable charging power of the energy storage is less than or equal to the difference between the maximum demand limit and the demand control margin. S43: When the load power is greater than or equal to the difference between the maximum demand limit and the demand control margin, adjust the allowable charging power of the energy storage to 0kW and put it in standby mode. S44: When the load power is less than the difference between the maximum demand limit and the demand control margin and the power reduction margin, adjust the allowable charging power of the energy storage so that the sum of the load power and the allowable charging power of the energy storage is less than or equal to the difference between the maximum demand limit and the demand control margin. S5: After the energy storage device (40) is fully charged, control at least one of the photovoltaic power generation device (10), the energy storage device (40) and the power grid (20) to output electrical energy to the load (30), and set the anti-reverse load control mode. The anti-reverse load control mode includes setting the anti-reverse power threshold and the power increase threshold. When the output power of the photovoltaic and the output power of the energy storage are less than the load power, purchase electricity from the power grid (20) to carry the load, and obtain the power grid output power on the main meter (80). Compare the power grid output power with the anti-reverse power threshold. When the power grid output power is less than the anti-reverse power threshold, reduce the output power of the energy storage first, and then reduce the output power of the photovoltaic until the power grid output power exceeds the power increase threshold. The power increase threshold is a preset value. The power increase threshold is greater than the anti-reverse power threshold. When the power grid output power fluctuates around the anti-reverse power threshold, the power increase threshold is used to prevent frequent activation of the anti-reverse control and reduce the energy consumption of calculation.

2. The method for preventing reverse current and overload in a photovoltaic-storage power station according to claim 1, characterized in that, The meteorological data refers to the light intensity data for the next 24 hours. The local electricity pricing scheme for each time period is a distribution scheme for peak and off-peak electricity periods within the next 24 hours; The first power generation period is the period during which the solar irradiance is less than a preset intensity during the off-peak electricity period; The second power generation period is the period during which the light intensity is greater than a preset intensity during the off-peak electricity period; The photovoltaic output power is the average power generation of the photovoltaic power generation device (10) per hour during the second power generation period.

3. The method for preventing reverse current and overload in a photovoltaic-storage power station according to claim 1, characterized in that, Controlling the photovoltaic power generation device (10) and the power grid (20) to charge the energy storage device (40) during the second power generation period, with the sum of the photovoltaic output power and the power grid output power not exceeding the allowed charging power of the energy storage device, in accordance with the priority order of power generation of the photovoltaic power generation device (10), includes: When the difference between the photovoltaic output power and the load power is greater than 0kW and less than the allowable charging power of the energy storage, the photovoltaic power generation device (10) and the power grid (20) are controlled to charge the energy storage device (40) during the second power generation period with the sum of the photovoltaic output power and the power grid output power not exceeding the allowable charging power of the energy storage. When the difference between the photovoltaic output power and the load power is greater than or equal to the energy storage allowable charging power, the photovoltaic power generation device (10) is controlled to charge the energy storage device (40) with the energy storage allowable charging power, and the grid output power is 0kW.

4. The method for preventing reverse current and overload in a photovoltaic-storage power station according to claim 1, characterized in that, S5: After the energy storage device (40) is fully charged, control at least one of the photovoltaic power generation device (10), the energy storage device (40), and the power grid (20) to output electrical energy to the load (30), set an anti-reverse load control mode, the anti-reverse load control mode includes setting an anti-reverse current power threshold and a power increase threshold, when the photovoltaic output power and the energy storage output power are less than the load power, purchase electricity from the power grid (20) to carry the load, and obtain the power grid output power on the main meter (80), compare the power grid output power with the anti-reverse current power threshold including: The output power of each phase of the three-phase power of the power grid (20) on the main meter (80) connected to the main transformer (60) is obtained, and the anti-reverse current power threshold and the output power of each phase are compared one by one. When the output power of any phase of the three-phase power of the power grid (20) is less than the anti-reverse current power threshold, the energy storage output power is reduced first, and then the photovoltaic output power is reduced until the output power of each phase of the power grid (20) exceeds the power increase threshold.

5. The method for preventing reverse current and overload in a photovoltaic-storage power station according to claim 1, characterized in that, S5: After the energy storage device (40) is fully charged, control at least one of the photovoltaic power generation device (10), the energy storage device (40), and the power grid (20) to output electrical energy to the load (30), set an anti-reverse load control mode, the anti-reverse load control mode includes setting an anti-reverse current power threshold and a power increase threshold, when the photovoltaic output power and the energy storage output power are less than the load power, purchase electricity from the power grid (20) to carry the load, and obtain the power grid output power on the main meter (80), compare the power grid output power with the anti-reverse current power threshold including: The total output power of the power grid (20) on the main meter (80) connected to the main transformer (60) is obtained, and the anti-reverse power threshold and the total output power of the power grid (20) are compared accordingly. When the total output power of the power grid (20) is less than the anti-reverse power threshold, the energy storage output power is reduced first, and then the photovoltaic output power is reduced until the total output power of the power grid (20) exceeds the power increase threshold.

6. A reverse current and overload protection device for a photovoltaic-storage power station, characterized in that, The method for preventing reverse current and overload in a photovoltaic-storage power station according to any one of claims 1 to 5 includes: The first prediction module (110) is used to acquire meteorological data and local electricity price schemes for each time period, and to obtain the first power generation period, the second power generation period, and the photovoltaic output power based on the meteorological data and the local electricity price schemes for each time period; The second prediction module (120) is used to acquire user historical data and predict load power and allowable charging power of energy storage based on the user historical data. A central processing module (130) is connected to the first prediction module (110) and the second prediction module (120); The first control module (140) is connected to the central processing module (130) and is used to control the power grid (20) to charge the energy storage device (40) with the energy storage allowable charging power during the first power generation period, and to control the photovoltaic power generation device (10) and the power grid (20) to charge the energy storage device (40) with the sum of photovoltaic output power and power grid output power not exceeding the energy storage allowable charging power during the second power generation period, in the order of priority power generation of the photovoltaic power generation device (10). The second control module (150) presets the maximum demand limit based on the user's electricity consumption in the previous month, and sets the demand control margin and power reduction margin. It adjusts the allowable charging power of the energy storage based on the maximum demand limit, the demand control margin and the power reduction margin. The third control module (160), after the energy storage device (40) is fully charged, controls at least one of the photovoltaic power generation device (10), the energy storage device (40) and the power grid (20) to output electrical energy to the load (30), and sets an anti-reverse load control mode. The anti-reverse load control mode includes setting an anti-reverse current power threshold and an increase power threshold. When the output power of the photovoltaic and the output power of the energy storage are less than the load power, the module purchases electricity from the power grid (20) to carry the load and obtains the power grid output power on the main meter (80). The module compares the power grid output power with the anti-reverse current power threshold. When the power grid output power is less than the anti-reverse current power threshold, the module prioritizes reducing the output power of the energy storage and then reduces the output power of the photovoltaic until the power grid output power exceeds the increase power threshold.

7. A reverse current and overload protection system for a photovoltaic-storage power station, characterized in that, The photovoltaic power station anti-reverse current and anti-overload device according to claim 6 also includes a photovoltaic power generation device (10), a power grid (20), a load (30), an energy storage device (40), a bus (50), a main transformer (60), a sub-transformer (70), a main meter (80), and a sub-meter (90).

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