Regulation and control system of grid-connected optical storage power station

Abstract

The invention discloses a regulation and control system of a grid-connected optical storage power station. The regulation and control system comprises a power curve prediction module, a power deviation calculation module and a charging and discharging adjustment module. The power curve prediction module is used for predicting a photovoltaic power curve and an energy storage power curve of the optical storage power station according to a predetermined strategy, and obtaining a power prediction curve of the optical storage power station according to the photovoltaic power curve and the energy storage power curve; the power deviation calculation module is used for calculating a power deviation value between the actual power curve of the optical storage power station and the power prediction curve of the optical storage power station; and the charge-discharge adjustment module is used for adjusting the charge-discharge process of the energy storage unit in the optical storage power station according to the power deviation value. According to the system, the influence of energy storage is considered, the deviation between the preliminarily predicted power curve and the actual power curve of the optical storage power station is reduced, and then the influence caused by the error of the actual photovoltaic power generation power is further reduced by using the adjustment function of the energy storage, so that the actual output of the optical storage power station is closer to the power prediction curve.

Description

Technical Field

[0001] The present invention belongs to the field of electric power technology, and in particular, relates to a control system for a grid-connected photovoltaic power station. Background Art

[0002] The daily output curve of a typical photovoltaic power station is small at the beginning and gradually rises; it tends to a maximum value in the middle period; and it gradually decreases at the end period until it stops generating electricity. In the middle period, due to the good solar energy resources, the photovoltaic output is large, which exceeds the load demand of the power grid. The power grid dispatching generally limits the photovoltaic power generation, thereby losing part of the power generation. In order to solve this part of the power loss, the photovoltaic power station is equipped with various types of energy storage systems. During the limited power generation period, the energy storage system stores the limited power generation, and releases the energy storage at the end of the photovoltaic power station discharge period. The energy storage system has various forms, and the charging and discharging characteristics of various energy storage are not the same, which provides the necessary conditions for adjusting the output response time of the photovoltaic power station. However, according to the current control method of the photovoltaic storage power station, the impact of the discharge of various energy storage systems on the power prediction system is not considered, that is, only the photovoltaic output curve is predicted. At the same time, due to the randomness of the weather conditions, the actual photovoltaic power generation will deviate from the predicted curve, which further leads to a large deviation between the actual output curve of the photovoltaic storage power station as a whole and the predicted curve. Summary of the invention

[0003] (I) Technical Problems to be Solved by the Present Invention

[0004] The technical problem solved by the present invention is: how to reduce the deviation between the actual output of a photovoltaic power station and a predicted curve.

[0005] (II) Technical solution adopted by the present invention

[0006] A control system for a grid-connected photovoltaic power station, the control system comprising a power curve prediction module, a power deviation calculation module and a charge and discharge adjustment module;

[0007] The power curve prediction module is used to predict the photovoltaic power curve and energy storage power curve of the photovoltaic power station according to a predetermined strategy, and to obtain the photovoltaic power station power prediction curve according to the photovoltaic power curve and the energy storage power curve, and the photovoltaic power station power prediction curve is used as the target power of the photovoltaic power station;

[0008] The power deviation calculation module is used to obtain the actual power curve of the photovoltaic power station and calculate the power deviation value between the actual power curve of the photovoltaic power station and the power prediction curve of the photovoltaic power station;

[0009] The charge and discharge adjustment module is used to adjust the charge and discharge process of the energy storage unit in the photovoltaic power station according to the power deviation value.

[0010] Preferably, the power curve prediction module includes an optical power prediction unit and an energy storage power prediction unit, wherein the optical power prediction unit is used to predict a photovoltaic power curve based on weather forecast data and photovoltaic power station parameters, and the energy storage power prediction unit is used to predict an energy storage power curve based on the photovoltaic power curve and status information of each energy storage unit in the photovoltaic power station.

[0011] Preferably, the optical power prediction unit is further used to perform smooth fitting on the photovoltaic power curve and the energy storage power curve to obtain a power prediction curve of the photovoltaic power station.

[0012] Preferably, the charge and discharge adjustment module includes a screening unit and a control unit, wherein the screening unit is used to screen out energy storage units that meet predetermined charge and discharge conditions from the photovoltaic power station as energy storage units to be adjusted, and the control unit is used to control the charge and discharge process of each energy storage unit to be adjusted according to the charge and discharge rate of each energy storage unit to be adjusted and the power deviation value.

[0013] Preferably, the screening unit is further used to select energy storage units whose state of charge values ​​are within a predetermined interval and whose temperature values ​​are within a predetermined range as energy storage units to be adjusted.

[0014] Preferably, the control unit is further used to set the charge and discharge weight coefficient of each of the energy storage units to be adjusted according to the power deviation value and the charge and discharge ratio of each of the energy storage units to be adjusted, and each of the energy storage units to be adjusted is charged and discharged according to the charge and discharge weight coefficient;

[0015] Among them, when the absolute value of the power deviation value is less than or equal to the first predetermined value, the charge and discharge weight coefficients of each of the energy storage units to be adjusted decrease as the charge and discharge rate increases; when the absolute value of the power deviation value is greater than the first predetermined value and the absolute value of the power deviation value is less than or equal to the second predetermined value, the charge and discharge weight coefficients of each of the energy storage units to be adjusted are equal, and the second predetermined value is greater than the first predetermined value; when the absolute value of the power deviation value is greater than the second predetermined value, the charge and discharge weight coefficients of each of the energy storage units to be adjusted increase as the charge and discharge rate increases.

[0016] Preferably, the control unit is also used to monitor the state of charge value of each of the energy storage units to be adjusted during the charging and discharging process, stop discharging the energy storage units to be adjusted whose state of charge value is less than the lower limit of the predetermined interval, and stop charging the energy storage units to be adjusted whose state of charge value is greater than the upper limit of the predetermined interval.

[0017] Preferably, the first predetermined value is 5% of the rated power of the photovoltaic power station, and the second predetermined value is 20% of the rated power of the photovoltaic power station; the lower limit of the predetermined interval is 10%, and the upper limit of the predetermined interval is 90%.

[0018] (III) Beneficial effects

[0019] The control system of a grid-connected photovoltaic power station disclosed in the present invention has the following technical effects compared with the prior art:

[0020] This method takes into account the impact of the energy storage system, reduces the deviation between the power curve obtained by the preliminary prediction and the actual power curve of the photovoltaic power station with energy storage, and then uses the adjustment function of the energy storage system to further reduce the impact of the error in the actual photovoltaic power generation power, so that the final actual output of the photovoltaic power station with energy storage is closer to the power prediction curve of the photovoltaic power station with energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a principle block diagram of a control system for a grid-connected photovoltaic power station according to Embodiment 1 of the present invention;

[0022] Figure 2 This is a data transmission schematic diagram of a control system of a grid-connected photovoltaic power station according to the first embodiment of the present invention; DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution 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 used to limit the present invention.

[0024] Before describing the various embodiments of the present application in detail, the technical concept of the present application is first briefly described: in the prior art, when predicting the power curve of a photovoltaic power station, only the photovoltaic power generation curve is considered, while the influence of the energy storage system is ignored. At the same time, due to the randomness of weather factors, there is also a certain deviation between the actual photovoltaic power generation and the predicted curve, which makes the actual output of the photovoltaic power station have a large error with the initial predicted curve. To this end, the present application provides a control system for a grid-connected photovoltaic power station, which first predicts the photovoltaic power curve and the energy storage power curve, then obtains the photovoltaic power station power prediction curve based on the two, then calculates the power deviation value between the actual power curve of the photovoltaic power station monitored in real time and the power prediction curve of the photovoltaic power station, and further adjusts the charging and discharging process of the energy storage unit according to the power deviation value to reduce the influence of the photovoltaic power generation power deviation. The control system takes into account the influence of the energy storage system, reduces the deviation between the power curve obtained by the preliminary prediction and the actual power curve of the photovoltaic power station, and then uses the adjustment function of the energy storage system to further reduce the influence caused by the error of the actual photovoltaic power generation, so that the actual output of the photovoltaic power station is closer to the power prediction curve of the photovoltaic power station.

[0025] Specifically, if Figure 1As shown, the control system of the grid-connected photovoltaic power station of the first embodiment includes a power curve prediction module 100, a power deviation calculation module 200 and a charge and discharge adjustment module 300. The power curve prediction module 100 is used to predict the photovoltaic power curve and the energy storage power curve of the photovoltaic power station according to a predetermined strategy, and to obtain the photovoltaic power station power prediction curve according to the photovoltaic power curve and the energy storage power curve, and the photovoltaic power station power prediction curve is used as the target power of the photovoltaic power station; the power deviation calculation module 200 is used to obtain the actual power curve of the photovoltaic power station and calculate the power deviation value between the actual power curve of the photovoltaic power station and the power prediction curve of the photovoltaic power station; the charge and discharge adjustment module 300 is used to adjust the charge and discharge process of the energy storage unit in the photovoltaic power station according to the power deviation value.

[0026] Specifically, the power curve prediction module 100 includes a light power prediction unit 101 and an energy storage power prediction unit 102. The light power prediction unit 101 predicts the photovoltaic power curve of the photovoltaic power station based on the weather forecast value and the photovoltaic power station parameters, and the energy storage power prediction unit 102 predicts the energy storage power curve based on the photovoltaic power curve and the status information of each energy storage unit in the photovoltaic power station. Figure 2 As shown, the optical power prediction unit 101 is an optical power prediction server, and the energy storage power prediction unit 102 is an optical storage EMS server. The photovoltaic power curve is predicted by the optical power prediction server based on the weather forecast value uploaded by the weather forecast system and the photovoltaic power station parameters uploaded by the optical storage EMS server. Then the optical power prediction server transmits the photovoltaic power curve to the optical storage EMS server through intra-station communication. The optical storage EMS server predicts the energy storage power curve based on the photovoltaic power curve and the collected state information of the energy storage unit, and transmits the energy storage power curve to the optical power prediction server. The state information of the energy storage unit includes the state of charge value (SOC value) of the energy storage unit, the temperature of the energy storage unit, whether the energy storage system is normally available, and other information. Exemplarily, the photovoltaic power curve and the energy storage power curve here are both the target output curves of the photovoltaic storage power station the next day. The prediction process of the photovoltaic power curve and the energy storage power curve can adopt some common methods in the art, such as multivariate linear regression algorithm, neural network algorithm, combined prediction method, etc., which are all well-known technologies in the art and will not be repeated here.

[0027] Furthermore, the optical power prediction unit also obtains the power prediction curve of the photovoltaic power station by smoothing the photovoltaic power curve and the energy storage power curve, and uses the power prediction curve of the photovoltaic power station as the next day's power target curve, which is uploaded to the scheduling system through the remote communication device. It should be noted that the photovoltaic power station generates electricity according to the next day's power target curve. In the actual process, since the charging and discharging process of the energy storage unit is set manually, the charging and discharging process of its energy storage unit can meet the target curve. However, due to the random errors of weather factors in actual situations, the actual photovoltaic power is either greater than the photovoltaic prediction curve or less than the photovoltaic prediction curve, that is, the power deviation value of the photovoltaic power station is mainly caused by the photovoltaic power deviation. Therefore, after obtaining the actual power curve of the photovoltaic power station, the power deviation calculation module 200 combines the power prediction curve of the photovoltaic power station to obtain the power deviation value.

[0028] Furthermore, the charge and discharge adjustment module 300 includes a screening unit 301 and a control unit 302, wherein the screening unit 301 is used to screen out energy storage units that meet predetermined charge and discharge conditions from the photovoltaic power station as energy storage units to be adjusted, and the control unit 302 is used to control the charge and discharge process of each of the energy storage units to be adjusted according to the charge and discharge rate of each of the energy storage units to be adjusted and the power deviation value.

[0029] Specifically, the predetermined charging and discharging conditions include the state of charge (SOC) value and temperature value of the energy storage unit. The screening unit 301 is also used to select the state of charge value within the predetermined interval and the temperature value within the predetermined range (-10℃ ～ 40℃, different types of energy storage units have certain differences) as the energy storage unit to be adjusted. When the state of charge value is less than the lower limit of the predetermined interval, it means that the energy storage unit cannot continue to participate in discharge; when the state of charge value is greater than the upper limit of the predetermined interval, the energy storage unit cannot continue to participate in charging, so these two types of energy storage units are excluded, and the energy storage units within the predetermined interval are used as energy storage units to be adjusted to participate in power regulation. Exemplarily, the lower limit of the predetermined interval is 10%, and the upper limit of the predetermined interval is 90%.

[0030] Furthermore, the control unit 302 is also used to set the charge and discharge weight coefficient of each energy storage unit to be adjusted according to the power deviation value and the charge and discharge ratio of each energy storage unit to be adjusted, and each of the energy storage units to be adjusted is charged and discharged according to the charge and discharge weight coefficient. Specifically, different types of energy storage units have different charge and discharge ratios, and the charge and discharge ratio represents the charge and discharge speed of the energy storage unit. The power deviation value is allocated to each energy storage unit to be adjusted, and the charge and discharge adjustment is performed. The charge and discharge weight coefficient represents the size of the allocation amount. The larger the charge and discharge weight coefficient, the larger the allocation amount.

[0031] Among them, different charging and discharging strategies are adopted according to different power deviation values. The first case: when the absolute value of the power deviation value is less than or equal to the first predetermined value, the charging and discharging weight coefficients of each of the energy storage units to be adjusted decrease as the charging and discharging ratio increases. In this case, the deviation between the actual output of the photovoltaic power station and the power prediction curve is small, and charging and discharging are mainly carried out through energy storage units with smaller charging and discharging ratios. The second case: when the absolute value of the power deviation value is greater than the first predetermined value and the absolute value of the power deviation value is less than or equal to the second predetermined value, the charging and discharging weight coefficients of each of the energy storage units to be adjusted are equal, and the second predetermined value is greater than the first predetermined value. In this case, the deviation between the actual output of the photovoltaic power station and the power prediction curve is within the normal range, and each energy storage unit is used for uniform charging and discharging. The third case: when the absolute value of the power deviation value is greater than the second predetermined value, the charging and discharging weight coefficients of each of the energy storage units to be adjusted increase as the charging and discharging ratio increases. In this case, the actual output of the photovoltaic power station deviates greatly from the power forecast curve, and the deviation is mainly adjusted in time by charging and discharging energy storage units with larger charging and discharging rates.

[0032] It should be noted that when the power deviation value is a negative value, it means that the actual power value of the photovoltaic power station is less than the predicted power value of the photovoltaic power station, and the energy storage unit needs to be used for discharge; when the power deviation value is a positive value, it means that the actual power value of the photovoltaic power station is greater than the predicted power value of the photovoltaic power station, and the energy storage unit needs to be used for charging. For example, the charging process is described accordingly when the power deviation value is a positive value, the first predetermined value is 5% of the rated power of the photovoltaic power station, and the second predetermined value is 20% of the rated power of the photovoltaic power station.

[0033] Let the power deviation value ΔP = KC, where K represents the inherent parameters of the photovoltaic power station, and C represents the charge and discharge ratio. K is set to different values ​​according to the configuration of the photovoltaic power station; according to different energy storage types, the charge and discharge ratios are C1 = 0.25, C2 = 0.5, C3 = 1, C4 = 2, C5 = 10...Cn respectively;

[0034] When ΔP<5% rated power, C=k1C1+k2C2+…+knCn, where k1+k2+…+kn=1, k is the charge and discharge weight coefficient of each type of energy storage system, and the value of k is inversely proportional to the charge and discharge rate of each type of energy storage unit, that is, the larger Cn is, the smaller the k value is;

[0035] When 5%<ΔP<20% rated power, C=k1C1+k2C2+…+knCn, where k1+k2+…+kn=1, k is the charge and discharge weight coefficient of each type of energy storage unit, and k is a constant;

[0036] When ΔP>20% rated power, C=k1C1+k2C2+…+knCn, where k1+k2+…+kn=1, k is the charge and discharge weight coefficient of each type of energy storage unit, and the value of k is proportional to the charge and discharge rate of each type of energy storage unit, that is, the larger Cn is, the larger the k value is.

[0037] Furthermore, the control unit 302 is also used to monitor the state of charge value of each of the energy storage units to be adjusted during the charging and discharging process, stop discharging the energy storage units to be adjusted whose state of charge value is less than the lower limit of the predetermined interval, and stop charging the energy storage units to be adjusted whose state of charge value is greater than the upper limit of the predetermined interval. That is, when the state of charge value of the energy storage unit to be adjusted is too small or too low during the charging and discharging process, it is not suitable to continue to participate in power regulation.

[0038] The specific implementation methods of the present invention are described in detail above. Although some embodiments have been shown and described, those skilled in the art should understand that these embodiments can be modified and improved without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents. These modifications and improvements should also be within the scope of protection of the present invention.

Claims

1. A control system for a grid-connected photovoltaic power station, characterized in that: The control system includes a power curve prediction module, a power deviation calculation module and a charge and discharge adjustment module; The power curve prediction module is used to predict the photovoltaic power curve and energy storage power curve of the photovoltaic power station according to a predetermined strategy, and to obtain the photovoltaic power station power prediction curve according to the photovoltaic power curve and the energy storage power curve, and the photovoltaic power station power prediction curve is used as the target power of the photovoltaic power station; The power deviation calculation module is used to obtain the actual power curve of the photovoltaic power station and calculate the power deviation value between the actual power curve of the photovoltaic power station and the power prediction curve of the photovoltaic power station; The charge and discharge adjustment module is used to adjust the charge and discharge process of the energy storage unit in the photovoltaic power station according to the power deviation value.

2. The control system of the grid-connected photovoltaic power station according to claim 1, characterized in that: The power curve prediction module includes a light power prediction unit and an energy storage power prediction unit, wherein the light power prediction unit is used to predict a photovoltaic power curve based on weather forecast data and photovoltaic power station parameters, and the energy storage power prediction unit is used to predict an energy storage power curve based on the photovoltaic power curve and status information of each energy storage unit in the photovoltaic power station.

3. The control system of the grid-connected photovoltaic power station according to claim 2, characterized in that: The optical power prediction unit is also used to smoothly fit the photovoltaic power curve and the energy storage power curve to obtain a power prediction curve of the photovoltaic power station.

4. The control system of the grid-connected photovoltaic power station according to claim 1, characterized in that: The charge and discharge adjustment module includes a screening unit and a control unit. The screening unit is used to screen out energy storage units that meet predetermined charge and discharge conditions from the photovoltaic power station as energy storage units to be adjusted. The control unit is used to control the charge and discharge process of each energy storage unit to be adjusted according to the charge and discharge rate of each energy storage unit to be adjusted and the power deviation value.

5. The control system of the grid-connected photovoltaic power station according to claim 4 is characterized in that: The screening unit is further configured to select energy storage units whose state of charge values ​​are within a predetermined interval and whose temperature values ​​are within a predetermined range as energy storage units to be adjusted.

6. The control system of the grid-connected photovoltaic power station according to claim 4, characterized in that: The control unit is further used to set the charge and discharge weight coefficient of each of the energy storage units to be adjusted according to the power deviation value and the charge and discharge ratio of each of the energy storage units to be adjusted, and each of the energy storage units to be adjusted is charged and discharged according to the charge and discharge weight coefficient; Among them, when the absolute value of the power deviation value is less than or equal to the first predetermined value, the charge and discharge weight coefficients of each of the energy storage units to be adjusted decrease as the charge and discharge rate increases; when the absolute value of the power deviation value is greater than the first predetermined value and the absolute value of the power deviation value is less than or equal to the second predetermined value, the charge and discharge weight coefficients of each of the energy storage units to be adjusted are equal, and the second predetermined value is greater than the first predetermined value; when the absolute value of the power deviation value is greater than the second predetermined value, the charge and discharge weight coefficients of each of the energy storage units to be adjusted increase as the charge and discharge rate increases.

7. The control system of the grid-connected photovoltaic power station according to claim 6, characterized in that: The control unit is also used to monitor the state of charge value of each of the energy storage units to be adjusted during the charging and discharging process, stop discharging the energy storage units to be adjusted whose state of charge values ​​are less than the lower limit of the predetermined interval, and stop charging the energy storage units to be adjusted whose state of charge values ​​are greater than the upper limit of the predetermined interval.

8. The control system of the grid-connected photovoltaic power station according to claim 6, characterized in that: The first predetermined value is 5% of the rated power of the photovoltaic power station, and the second predetermined value is 20% of the rated power of the photovoltaic power station; the lower limit of the predetermined interval is 10%, and the upper limit of the predetermined interval is 90%.

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