Method for regulating and controlling water-optical storage micro-grid under weak communication condition

Abstract

The invention discloses a hydro-optical storage micro-grid regulation and control method under a weak communication condition. The method comprises the following steps that a hydroelectric generating set controller receives historical local load power data sent by a transformer area; predicting the load value of the day; a photovoltaic auxiliary test unit is installed on the periphery of a hydropower station, the maximum power of the auxiliary test unit under the current working condition is obtained, communication is established between the auxiliary test unit and the small hydropower station, and the maximum power is transmitted to a hydroelectric generating set controller; the hydroelectric generating set controller estimates the generating capacity of the photovoltaic power station in the transformer area based on the generating data of the auxiliary test unit; the small hydropower station calculates and updates the current generated power reference value of the small hydropower station according to the current estimated generating capacity of the photovoltaic power station and the predicted local load data; a micro-grid controller in a transformer area collects voltage, current, power and system frequency data of a micro-grid system, adjusts power balance of the micro-grid system through a centralized energy storage power station and a photovoltaic power station, records local load power data within one day, and transmits the data to a hydroelectric generating set controller.

Description

Technical Field

[0001] The present invention belongs to the field of water-photovoltaic-storage microgrid control, and in particular relates to a water-photovoltaic-storage microgrid control method under weak communication conditions. Background Art

[0002] my country's southeastern and southwestern mountainous areas are rich in hydropower resources, and small hydropower has broad prospects for development. Under the dual carbon goals, distributed photovoltaics have developed rapidly, and more and more distributed power sources such as photovoltaics and hydropower have been connected to the power grid through long-distance transmission lines. At the same time, due to the remote geographical location and complex terrain, the power grid in mountainous areas often has relatively poor power supply reliability due to long power supply lines and large power supply radius. When the upper power grid fails and loses power, the microgrid system relying on the sufficient local photovoltaic and hydropower resources is an effective guarantee for the reliability of power supply for mountain residents.

[0003] However, since small hydropower stations are usually located in remote mountainous areas far away from the load center, the communication conditions with the substation equipment are poor. In response to the communication problem, existing scholars have studied the control strategy of microgrids from the perspective of improving communication conditions and solving the problem of weak communication. For mountain power grids containing small hydropower, there is technology to establish communication between the hydropower controller, grid-connected switch, and dispatching EMS master station system, which can collect data such as the power of the hydropower units. The hydropower units can also receive instructions from the dispatching EMS system to adjust the start and stop of hydropower and adjust the hydropower output. This technology strictly relies on strong communication conditions and requires the establishment of communication lines in advance, which is relatively expensive.

[0004] There are also technologies for controlling small hydropower stations under weak communication conditions, proposing an emergency control strategy of centralized decision-making + local control to achieve the transition from grid-connected to isolated grid at the moment of failure, but it does not consider the stable operation of the microgrid system for a period of time after the isolated grid.

[0005] In the existing technology, for mountain power grids containing small hydropower, there is a technology to establish communication between the hydropower controller, grid-connected switch, and dispatching EMS master station system, which can collect data such as hydropower unit power. The hydropower unit can also receive instructions from the dispatching EMS system to adjust the hydropower start, stop, and adjust the hydropower output. This technology strictly relies on strong communication conditions and requires the establishment of communication lines in advance, which is relatively expensive.

[0006] There are also technologies for controlling small hydropower stations under weak communication conditions, proposing an emergency control strategy of centralized decision-making + local control to achieve the transition from grid-connected to isolated grid at the moment of failure, but it does not consider the stable operation of the microgrid system for a period of time after the isolated grid. Summary of the invention

[0007] In response to the above problems, the present invention proposes a method for controlling a hydro-solar-storage microgrid in mountainous areas under weak communication conditions, which not only reduces the initial investment cost of the microgrid, but also maintains the normal operation of the microgrid system after being off-grid, thereby ensuring the power supply reliability of local residents.

[0008] The present invention is achieved by at least one of the following technical solutions.

[0009] A method for controlling a water-solar-energy-storage microgrid under weak communication conditions comprises the following steps:

[0010] Step 1: The hydropower unit controller receives the historical local load power data sent from the substation; the load value of the day is predicted by processing the data;

[0011] Step 2: Install a photovoltaic auxiliary test unit in an area around the hydropower station that is not blocked by sunlight, obtain the maximum power of the auxiliary test unit under the current working conditions, and establish communication between the photovoltaic auxiliary test unit and the small hydropower station to transmit its maximum power to the hydropower unit controller;

[0012] Step 3: The hydropower unit controller estimates the power generation of the photovoltaic power station in the area based on the power generation data of the photovoltaic auxiliary test unit;

[0013] Step 4: The small hydropower station calculates and updates the current power generation reference value of the small hydropower unit based on the current estimated photovoltaic power generation and the predicted local load data;

[0014] Step 5: The microgrid controller in the substation collects the voltage, current and system frequency data of the current microgrid system, and the voltage, current and system frequency data are refreshed and recorded at intervals;

[0015] Step 6: Regulate the power balance of the microgrid system through the centralized energy storage power station and the photovoltaic power station to ensure the stable operation of the microgrid system;

[0016] Step 7: The microgrid controller in the substation collects the load power data of the current microgrid system, refreshes and records the power data at intervals, and transmits the recorded local load power data of the day to the hydropower unit controller.

[0017] Furthermore, in step 1, the load value of the day is predicted by processing the transmitted historical local load power data, including the following steps:

[0018] The first step is to fit the load waveform of the day according to the load waveforms in the previous seven days. The waveform of the day is most similar to the waveform of the past seventh day, so the waveform of the past seventh day accounts for the largest proportion of the predicted waveform of the day, and the waveforms of the remaining days have little similarity and a small proportion;

[0019] Step 2: Since the weather and temperature of the previous day are closest to those of the current day, the load amplitude of the previous day is used to correct the predicted load amplitude of the current day.

[0020] Furthermore, the photovoltaic auxiliary test unit adopts maximum power point tracking control to obtain the maximum power P of the photovoltaic auxiliary test unit at the current moment every 15 minutes. m (k) and transmit the data to the hydropower unit controller via optical fiber communication;

[0021] The subscript m represents the maximum power point of the photovoltaic auxiliary test unit, k represents the specific time, and the value of k is between [1-96].

[0022] Furthermore, the estimation process of step 3 is as follows: considering that the working conditions of the photovoltaic arrays in the same area are approximately the same, and the maximum power operating points of the single auxiliary test units are approximately the same, the approximate coefficient d(k) is taken, and the power of the photovoltaic power station in the area is estimated according to the number of units N of the photovoltaic power station in the area:

[0023] P pvmax (k)=d(k)*N*P m (k)

[0024] Among them, P pvmax (k) represents the power generation of the photovoltaic power station in the substation, k represents the specific time; d(k) is taken according to the specific time, and the value range is [0.85-1.15], P m (k) represents the maximum power of the photovoltaic auxiliary test unit at the current moment.

[0025] Furthermore, the current reference value of the generated power of the hydropower unit calculated in step 4 is:

[0026] P hdref (k) = P i (k)-P pvmax (k)

[0027] Among them, P hdref (k) is the reference value of the power generation of the small hydropower station at the kth moment, P i (k) is the load value predicted for the day, i refers to the day, k refers to the specific time, P pvmax (k) represents the power generation capacity of the photovoltaic power station in the area.

[0028] Furthermore, in step 4, the reference value of the power generation of the small hydropower station at the [1-96]th time point on the day is calculated, and the reference value criterion of the power generation of the small hydropower unit is updated as follows:

[0029] When |P hdref (k+1)-P hdref (k)|≤5% P hdref (k), P hdref (k) Assign a value to P hdref (k+1), that is, keep the reference value of the power generation of the small hydropower unit consistent with that of the previous moment;

[0030] When |P hdref (k + 1)-P hdref (k)| > 5% P hdref (k), then update the reference value of the power generation power of the small hydropower unit according to the calculation result of P hdref (k + 1);

[0031] Among them, P hdref (k + 1) is the reference value of the power generation power of the small hydropower station at the (k + 1)-th moment.

[0032] Furthermore, in step 5, the microgrid controller in the substation area collects the voltage, current and system frequency data of the current microgrid system at a sampling frequency of 1200 Hz, and the voltage, current and system frequency data are refreshed and recorded every 1 s.

[0033] Furthermore, in step 6, power balance adjustment is performed through the centralized energy storage power station and the photovoltaic power station, specifically including:

[0034] When 49.8 < f < 50.2 Hz, the microgrid system maintains the current operating state, where f represents the frequency of the microgrid system;

[0035] When f ≥ 50.2 Hz and df / dt > 0, adjust the operating state of the photovoltaic power station, adjust from the maximum power operation to the reduced power operation, and then the centralized energy storage power station is used as the balancing node for power balance adjustment;

[0036] When f ≥ 50.2 Hz and df / dt ≤ 0, the centralized energy storage power station is used as the balancing node for power balance adjustment;

[0037] When f ≤ 49.8 Hz and df / dt ≤ 0, first judge the current operating state of the photovoltaic. If it is in the reduced power operation, then switch to the maximum power operation, and then the centralized energy storage power station is used as the balancing node for power balance adjustment;

[0038] When f ≤ 49.8 Hz and df / dt > 0, the centralized energy storage power station is used as the balancing node for power balance adjustment.

[0039] Furthermore, in step 6, when performing power balance adjustment through the photovoltaic power station, the specific steps for adjusting the photovoltaic power station from the maximum power operation to the reduced power operation are:

[0040] Since the photovoltaic initially operates at the maximum power point, collect the current maximum power point voltage U m and record it. When it is necessary to adjust from the maximum power operation state to the reduced power operation, set the reference voltage of the photovoltaic controller to U ref as: U ref = U m -ΔU, where ΔU = Um / T, T is the constant voltage reduction coefficient, which is a positive integer.

[0041] Furthermore, in step 7, the microgrid controller in the substation collects power data of the current microgrid system at a sampling frequency of 1200 Hz, refreshes and records the power data every 15 minutes, and transmits the recorded local load power data of the day to the hydropower unit controller.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. The present invention can reduce the initial investment cost of microgrid communication in mountainous areas and ensure the stable operation of the microgrid system under weak communication with substation equipment.

[0044] 2. The present invention proposes a load forecasting method, which uses the load data of the past seven days to predict the load value of the day. These historical load data are transmitted through the existing communication network, which can be realized even under weak signal conditions. In extreme cases, such as natural disasters or communication system failures, emergency plans for manual data transmission can be used to ensure the effective delivery of data. The robustness of data transmission under limited communication conditions is enhanced, providing a reliable and efficient load forecasting tool for small hydropower units.

[0045] 3. The present invention estimates the output power of the local photovoltaic power station through the power generation data of the photovoltaic auxiliary test unit to adjust the power generation of the local small hydropower station, effectively alleviating the coordination problem of the water-photovoltaic-storage microgrid under weak or no communication conditions. Through reasonable regulation, when the main grid line is disconnected due to a fault, the microgrid system can be used to ensure power supply in time, ensuring the reliability of power supply to local residents. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a structural diagram of a water-photovoltaic-storage microgrid system in an embodiment;

[0047] Figure 2 This is a control flow chart of the water-photovoltaic-storage microgrid system of the embodiment;

[0048] Figure 3 Schematic diagram of the photovoltaic power station grid-connected control strategy of the embodiment. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0050] The microgrid system of this embodiment is composed of a small hydropower station, a photovoltaic power station, a centralized energy storage power station, a local load, a substation microgrid controller, a dummy load, etc. The structure diagram of the hydro-photovoltaic-storage microgrid system is shown in FIG. Figure 1 As shown. Considering that small hydropower stations are generally located in remote mountainous areas, there is no communication, communication delay, communication failure and other weak communication conditions between them and the microgrid controller in the substation, while other devices are close to the microgrid controller in the substation and are in strong communication conditions with the load side. In this embodiment, the problem of weak communication with the microgrid control device in the substation is considered, and a photovoltaic auxiliary test unit is installed on the roof of the small hydropower station or in the area without sunlight shielding around the small hydropower station to predict the power generation power of the local photovoltaic power station. Figure 2 Shown is the control flow chart of this embodiment.

[0051] A method for controlling a water-solar-energy-storage microgrid under weak communication conditions in this embodiment includes the following steps:

[0052] Step 1: The hydropower unit controller receives the local load power data of the past seven days sent from the substation; the load value of the day is predicted by processing the data of the previous seven days; considering the communication delay and obtaining complete load data within a day, when the communication conditions are poor, the data is allowed to be transmitted in batches when conditions permit, ensuring that the data will not be lost due to communication interruption. In extreme cases, such as natural disasters or communication system failures, emergency plans for manual data transmission are used to ensure that data can be delivered safely.

[0053] The hydropower unit controller uses STM32 as the main controller. The hydropower unit controller has the functions of communicating with the microgrid controller of the substation, regulating the hydropower output, and automatically starting and stopping according to the water level change. Considering the communication delay and obtaining complete load data within a day, when the communication conditions are poor, data is allowed to be transmitted in batches when conditions permit, ensuring that data will not be lost due to communication interruptions. In extreme cases, such as natural disasters or communication system failures, emergency plans for manual data transmission are used to ensure that data can be delivered safely.

[0054] The load data of the past seven days received by the hydropower unit controller is shown in Table 1 below. Considering the time limit of hydropower regulation and reducing the regulation frequency of small hydropower, there is one load point every 15 minutes, so there are 96 data points in 24 hours a day.

[0055] Table 1 Local load power data for the past seven days

[0056]

[0057] In the above table, P i-7 (k) represents the load data within the i-7th day, k represents the specific time. Since a load point is collected every 15 minutes, there are 96 data points in 24 hours a day, and the value of k is between [1-96]; Pi-6 (k) represents the load data within the first 6 days; P i-5 (k) represents the load data within the first 5 days; P i-4 (k) represents the load data within the i-4th day; P i-3 (k) represents the load data within the first 3 days; P i-2 (k) represents the load data within the i-2 days; P i-1 (k) represents the load data of day i-1.

[0058] The load value of the current day is predicted by processing the load data of the previous seven days. The prediction method is divided into two steps:

[0059] The first step is to fit the load waveform of the day based on the load waveforms of the previous seven days. The waveform of the day is most similar to the waveform of the seventh day in the past, so the waveform of the seventh day in the past accounts for the largest proportion of the waveform of the day, and the waveforms of the remaining days account for a slightly smaller proportion. The fitting method is as follows:

[0060]

[0061] Among them, P i,1 (k) represents the load data of the i-th day, i.e. the day after the first step of prediction; since the waveform of the past seventh day is most similar to the waveform of the day and accounts for the largest proportion of the waveform of the day, as an embodiment, the proportion is taken as 0.7, and the waveform similarities of the remaining days are relatively small, and the values ​​are all taken as 0.05.

[0062] Step 2: Since the weather and temperature of the previous day are closest to those of the current day, the load amplitude of the previous day is used to correct the load amplitude of the current day. The correction method is as follows:

[0063] when When , keep the prediction result of the first step unchanged, that is:

[0064] P i (k) = P i,1 (k)

[0065] P i (k) represents the final load data predicted on the i-th day;

[0066] when When , the prediction result of the first step is updated, and the updated final load data is:

[0067] Step 2: Install a photovoltaic auxiliary test unit on the roof of the small hydropower station or in an area around the small hydropower station that is not blocked by sunlight, set the photovoltaic auxiliary test unit to operate in the maximum power mode, and transmit the output power of the photovoltaic auxiliary test unit to the small hydropower unit controller through optical fiber communication every 15 minutes. Since the photovoltaic auxiliary test unit operates in the maximum power mode, the output power is the maximum power under the current working conditions.

[0068] As an embodiment, the photovoltaic auxiliary test unit includes multiple photovoltaic cells, obtains the maximum power of the auxiliary test unit under the current working conditions, and transmits the maximum power to the hydropower unit controller by establishing a communication connection between the photovoltaic auxiliary test unit and the small hydropower station.

[0069] Step 3: The hydropower unit controller estimates the power generation of the photovoltaic power station in the substation based on the power data of the auxiliary test unit. The estimation process is as follows: considering that the working conditions of the photovoltaic arrays in the same substation are approximately the same, the maximum power operating point of a single auxiliary test unit is approximately the same, and the approximate coefficient d(k) is taken. The power P of the photovoltaic power station in the substation is estimated based on the number of units N of the photovoltaic power station in the substation. pvmax (k) is:

[0070] P pvmax (k)=d(k)*N*P m (k)

[0071] Wherein, d(k) can be set according to the specific time. In this embodiment, the value range is [0.85-1.15];

[0072] P m (k) represents the output power of the photovoltaic auxiliary test unit, where m represents the maximum power point, k represents the specific time, and the value of k is between [1-96].

[0073] Step 4: Small hydropower station based on the current estimated photovoltaic power generation P pvmax (k) and the local load data P predicted in step 1 i (k) Update the current power generation reference value P of the small hydropower station hdref (k), the update formula is:

[0074] P hdref (k) = P i (k)-P pvmax (k)

[0075] Among them, P hdref (k) is the reference value of the power generation of the small hydropower station at the kth moment, and k refers to the specific moment.

[0076] However, considering the wear of the small hydropower unit caused by frequent regulation, the number of regulations should be reduced, and the reference value criterion for the power generation power of the small hydropower unit is updated to:

[0077] When |P hdref (k + 1)-P hdref (k)| ≤ 5% P hdref (k), assign P hdref (k) to P hdref (k + 1), that is, keep the reference value of the power generation power of the small hydropower unit consistent with the previous moment.

[0078] When |P hdref (k + 1)-P hdref (k)| > 5% P hdref (k), then update the reference value of the power generation power of the small hydropower unit according to the calculation result of P hdref (k + 1).

[0079] Among them, P hdref (k + 1) is the reference value of the power generation power of the small hydropower station at the (k + 1)-th moment.

[0080] Step 5: The microgrid controller in the substation area collects the voltage, current, and system frequency data of the current microgrid system at a sampling frequency of 1200 Hz, and the voltage, current, and system frequency data are refreshed and recorded every 1 s.

[0081] The microgrid controller in the substation area has relatively high performance requirements for the microgrid controller. Currently, the all-programmable system-on-chip ZYNQ of Xilinx Corporation is adopted. The microgrid controller is connected to the dispatching master station at the upper end and accesses devices such as the hydropower controller, photovoltaic controller, and energy storage controller at the lower end. By collecting the data (voltage, current, power, status, etc.) of the lower-end devices, the microgrid status perception is realized, and mode management, switching, and other controls are carried out according to the preset operation mode.

[0082] Step 6: Adjust the power balance of the microgrid system through the centralized energy storage power station and the photovoltaic power station to ensure the stable operation of the microgrid system.

[0083] The power balance adjustment is carried out through the centralized energy storage power station and the photovoltaic power station, specifically including:

[0084] When 49.8 < f < 50.2 Hz, the microgrid system maintains the current operating state. f is the system frequency.

[0085] When f ≥ 50.2 Hz and df / dt > 0, adjust the operating state of the photovoltaic power station from the maximum power operation to the reduced power operation, and then use the centralized energy storage power station as the balancing node to carry out power balance adjustment;

[0086] When f≥50.2Hz and df / dt≤0, the centralized energy storage power station acts as a balancing node to perform power balancing regulation.

[0087] When f≤49.8Hz and df / dt≤0, the current operating state of the photovoltaic is first determined. If it is in power reduction operation, it is switched to maximum power operation. Then the centralized energy storage power station is used as a balancing node to perform power balance adjustment.

[0088] When f≤49.8Hz and df / dt>0, the centralized energy storage power station acts as a balancing node to perform power balancing regulation.

[0089] The specific steps of adjusting the power balance of the photovoltaic power station from the maximum power operation to the reduced power operation are as follows:

[0090] Since the photovoltaic initialization is set to the maximum power operation state, the current working voltage collected is the maximum power point voltage U m And record, when it is necessary to adjust from the maximum power operation state to the reduced power operation state, switch the reference voltage signal of the voltage loop of the photovoltaic controller to U ref =U m -ΔU.

[0091] Where ΔU=U m / T, T is a constant voltage reduction coefficient, which is a positive integer. As an embodiment, T is taken as 20.

[0092] Photovoltaic system control block diagram Figure 3 The photovoltaic power station has two operating modes: maximum power control mode and power reduction control mode. The photovoltaic power station operating mode is switched according to the result of frequency and frequency change and the voltage reference signal is output. The grid-connected control signal is then output through the voltage loop-current loop-SPWM.

[0093] The weak communication situation with the microgrid controller in the substation mentioned in this embodiment specifically refers to: currently, small hydropower generally adopts 4G, carrier, LORA and other communication methods with long transmission delays. Currently, there are few optical fiber channels, and the communication signal is weak, which is prone to communication delays, communication interruptions and other phenomena. In this embodiment, weak communication can specifically refer to communication methods with long transmission delays such as 4G, carrier or LORA, and can also indicate that communication is blocked and data is transmitted completely manually in an emergency plan.

[0094] Step 7: The microgrid controller in the substation collects the load power data of the current microgrid system. The power data is refreshed and recorded every 15 minutes, and the recorded local load power data of the day is transmitted to the hydropower unit controller.

[0095] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for controlling a water-solar-storage microgrid under weak communication conditions, characterized in that: The steps include the following: Step 1: The hydropower unit controller receives the historical local load power data sent from the substation area; predicts the load value of the current day by processing the data. Step 2: Install a photovoltaic auxiliary test unit in an area without sunlight obstruction around the hydropower station, obtain the maximum power under the current working condition of the auxiliary test unit, and transmit its maximum power to the hydropower unit controller by establishing a communication link between the photovoltaic auxiliary test unit and the small hydropower station. Step 3: The hydropower unit controller estimates the power generation of the photovoltaic power station in the substation area based on the power generation data of the photovoltaic auxiliary test unit. Step 4: The small hydropower station calculates and updates the current power generation power reference value of the small hydropower unit according to the currently estimated photovoltaic power generation and the predicted local load data. Step 5: The microgrid controller in the substation area collects the voltage, current and system frequency data of the current microgrid system, and the voltage, current and system frequency data are refreshed and recorded at an interval time. Step 6: Adjust the power balance of the microgrid system through the centralized energy storage power station and the photovoltaic power station to ensure the stable operation of the microgrid system. Step 7: The microgrid controller in the substation area collects the load power data of the current microgrid system, refreshes and records the power data at an interval time, and transmits the recorded local load power data within the current day to the hydropower unit controller.

2. According to the method for controlling a water-solar-storage microgrid under weak communication conditions in claim 1, it is characterized in that: In Step 1, predicting the load value of the current day by processing the transmitted historical local load power data includes the following steps: The first step: Fit the load waveform of the current day according to the load waveforms in the previous seven days. Since the waveform of the current day is most similar to the waveform of the seventh day in the past, the waveform of the seventh day in the past accounts for the largest proportion in the predicted waveform of the current day, and the waveform similarities of the other days are small and the proportions are small. The second step: Since the weather and temperature of the day adjacent to the current day are closest to those of the current day, the load amplitude of the current day is predicted by correcting with the load amplitude of the previous day.

3. According to the method for controlling a water-solar-storage microgrid under weak communication conditions in claim 1, it is characterized in that: The photovoltaic auxiliary test unit adopts maximum power point tracking control, and obtains the maximum power P of the photovoltaic auxiliary test unit at the current moment every 15 minutes. m (k) and transmit the data to the hydropower unit controller via optical fiber communication; Where the subscript m represents the maximum power point of the photovoltaic auxiliary test unit, k represents a specific moment, and the value of k is between [1 - 96].

4. According to the method for controlling a water-solar-storage microgrid under weak communication conditions in claim 1, it is characterized in that: The estimation process of Step 3 is as follows: Considering that the working conditions of the photovoltaic arrays in the same substation area are approximately the same and the maximum power operating points of individual auxiliary test units are approximately the same, taking the approximation coefficient d(k), the power of the photovoltaic power station in the substation area is estimated according to the number of units N of the photovoltaic power station in the substation area as: P pvmax (k)=d(k)*N*P m (k) Among them, P pvmax (k) represents the power generation of the photovoltaic power station in the substation, k represents the specific time; d(k) is taken according to the specific time, and the value range is [0.85-1.15], P m (k) represents the maximum power of the photovoltaic auxiliary test unit at the current moment.

5. According to the method for controlling a water-solar-storage microgrid under weak communication conditions in claim 1, it is characterized in that: The calculation of the current power generation power reference value of the hydropower unit in Step 4 is: P hdref (k)=P i (k)-P pvmax (k) Among them, P hdref (k) is the reference value of the power generation of the small hydropower station at the kth moment, P i (k) is the load value predicted for the day, i refers to the day, k refers to the specific time, P pvmax (k) represents the power generation capacity of the photovoltaic power station in the area.

6. The method for controlling a water-solar-storage microgrid under weak communication conditions according to claim 1, characterized in that: In Step 4, calculating the power generation power reference value of the small hydropower station at the [1 - 96]th moment point of the current day, the criterion for updating the power generation power reference value of the small hydropower unit is: When |P hdref (k+1)-P hdref (k)|≤5%P hdref (k), P hdref (k) Assign a value to P hdref (k+1), that is, keep the reference value of the power generation of the small hydropower unit consistent with that of the previous moment; When |P hdref (k+1)-P hdref (k)|>5%P hdref (k), then according to P hdref The calculation result of (k+1) updates the reference value of power generation of small hydropower units; Among them, P hdref (k+1) is the reference value of the power generation of the small hydropower station at the k+1th moment.

7. The method for controlling a water-solar-storage microgrid under weak communication conditions according to claim 1, characterized in that: In Step 5, the microgrid controller in the substation area collects the voltage, current and system frequency data of the current microgrid system at a sampling frequency of 1200 Hz, and the voltage, current and system frequency data are refreshed and recorded every 1 s.

8. The method for controlling a water-solar-storage microgrid under weak communication conditions according to claim 1, characterized in that: In Step 6, the power balance adjustment is carried out through the centralized energy storage power station and the photovoltaic power station, specifically including: When 49.8 < f < 50.2 Hz, the microgrid system maintains its current operating state, where f represents the frequency of the microgrid system. When f≥50.2Hz and df / dt>0, the operation state of the photovoltaic power station is adjusted from maximum power operation to reduced power operation, and then the centralized energy storage power station is used as a balancing node to perform power balancing adjustment; When f≥50.2Hz and df / dt≤0, the centralized energy storage power station is used as the balancing node to perform power balancing adjustment; When f≤49.8Hz and df / dt≤0, the current operating state of the photovoltaic is first determined. If it is in power reduction operation, it is switched to maximum power operation. Then the centralized energy storage power station is used as a balancing node to perform power balance adjustment. When f≤49.8Hz and df / dt>0, the centralized energy storage power station acts as a balancing node to perform power balancing regulation.

9. The method for controlling a water-solar-storage microgrid under weak communication conditions according to claim 1, characterized in that: In step 6, the specific steps of adjusting the photovoltaic power station from maximum power operation to reduced power operation by performing power balance adjustment through the photovoltaic power station are as follows: Since the photovoltaic power plant initially operates at the maximum power point, the current maximum power point voltage U m And record, when it is necessary to adjust from the maximum power operation state to the reduced power operation state, set the reference voltage of the photovoltaic controller to U ref For: U ref =U m -ΔU, where ΔU = U m / T, T is the constant voltage reduction coefficient, which is a positive integer.

10. The method for controlling a water-solar-storage microgrid under weak communication conditions according to claim 1, characterized in that: In step 7, the microgrid controller in the substation collects the power data of the current microgrid system at a sampling frequency of 1200 Hz, refreshes and records the power data every 15 minutes, and transmits the recorded local load power data of the day to the hydropower unit controller.

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