A charge-discharge control method of an energy storage device

Abstract

The application discloses a kind of energy storage device's charge-discharge control method, for preventing the problem of power reverse on-grid and transformer overload in microgrid, microgrid includes, energy storage device and control module, when the working mode of energy storage converter is discharge mode, control module judges whether the mains power value is greater than the preset mains power anti-flow threshold value, if not, then control module controls energy storage converter to reduce discharge power;When the working mode of energy storage converter is charging mode, control module judges whether the mains power value is less than the preset transformer maximum load value, if not, then control module controls energy storage converter to reduce charging power.The technical scheme provided by the application can effectively avoid the occurrence of energy storage device power reverse on-grid or user transformer overload operation without affecting the cyclic charge-discharge operation of energy storage device in microgrid, and the working process is simple and clear.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electric power, in particular to a charge-discharge control method of an energy storage device. BACKGROUND

[0002] As an important support of "Internet+" smart energy and a technical means of friendly interaction with the large power grid, the micro-grid can improve the safety and reliability of the power system, promote the access and local consumption of clean energy, improve the energy utilization efficiency, play an important role in energy saving and emission reduction, and be conducive to the construction of a conservation-oriented society.

[0003] However, the energy storage device in the micro-grid may encounter the following problems during operation of charge and discharge:

[0004] (1) When the energy storage device is discharging, if the total power consumption of the user is less than the discharging power of the energy storage device, the electric energy of the energy storage device will flow back to the upper grid connected to the user;

[0005] (2) When the energy storage device is charging, if the charging power of the energy storage device is too high, resulting in too high total power consumption of the user, it may cause the transformer of the user to overload and even trip, affecting the efficiency, service life of the transformer and the safety of the user's power consumption.

[0006] At present, the mainstream energy storage device on the market generally sets the charge and discharge power of the energy storage device for each period in advance to realize the cyclic charge and discharge operation (for example, set the energy storage device to charge from 0:00 to 8:00, the charging power is 100kW; set the energy storage device to discharge from 8:00 to 12:00, the discharging power is 200kW; set the energy storage device to charge from 12:00 to 17:00, the charging power is 160kW), and the energy storage charge and discharge control method for preventing reverse flow and transformer overload is not designed in the micro-grid. In this mode, the energy storage device will not adjust the charge and discharge power in real time according to the power consumption of the user, so it is easy to cause the electric energy of the energy storage device to flow back to the grid or the user's transformer to overload.

[0007] In addition, in the prior art, the minimum chargeable power and the maximum dischargeable power of the energy storage device in each power consumption period are determined in advance according to the historical power consumption data and the future power consumption plan of the user, and then the charge and discharge power of the energy storage device in each power consumption period is set. However, this scheme has the following problems:

[0008] 1. Large workload: a large amount of historical power consumption data of the user needs to be counted;

[0009] 2. Poor timeliness: when the user's power consumption changes unpredictably, the operating parameters of the energy storage device cannot be adjusted in advance. SUMMARY

[0010] In view of the above, it is necessary to provide a charge and discharge control method of an energy storage device, which can adjust the charge and discharge power of the energy storage device according to the power consumption of a user during the operation of the energy storage device, so as to avoid the situation that the energy of the energy storage device is reversely fed to the grid or the user transformer is overloaded. The technical scheme provided by the present application is as follows:

[0011] The present application provides a charge and discharge control method of an energy storage device, which is used for preventing the problems of reverse feeding of energy to the grid and overload of transformer in a micro-grid, and the micro-grid comprises:

[0012] a commercial power supply;

[0013] an energy storage device comprising an energy storage battery and an energy storage converter cooperating with the energy storage battery, the energy storage converter having a charge mode and a discharge mode, in the charge mode, the energy storage converter can control the energy storage battery to be charged, and in the discharge mode, the energy storage converter can control the energy storage battery to be discharged;

[0014] a control module connected with the commercial power supply and the energy storage device respectively, the control module being used for acquiring the state of charge of the energy storage battery, the working mode and working power of the energy storage converter, and the commercial power value of the commercial power supply in real time, and controlling the energy storage device to be charged or discharged;

[0015] The charge and discharge control method comprises: when the working mode of the energy storage converter is the discharge mode, the control module judges whether the commercial power value is greater than a preset commercial power anti-flow threshold value, if not, the control module controls the energy storage converter to reduce the discharge power; when the working mode of the energy storage converter is the charge mode, the control module judges whether the commercial power value is less than a preset transformer maximum load value, if not, the control module controls the energy storage converter to reduce the charge power.

[0016] Further, when the working mode of the energy storage converter is the discharge mode, if the commercial power value is greater than the commercial power anti-flow threshold value, the control module compares the current discharge power of the energy storage converter with the maximum discharge power of the energy storage battery, if the current discharge power of the energy storage converter is less than the maximum discharge power of the energy storage battery, the control module controls the energy storage converter to increase the discharge power.

[0017] Further, when the operation mode of the energy storage converter is the charging mode, if the utility power value is less than the transformer maximum load value, the control module compares the current charging power of the energy storage converter with the maximum charging power of the energy storage converter, and if the current charging power of the energy storage converter is less than the maximum charging power of the energy storage battery, the control module controls the energy storage converter to increase the charging power.

[0018] Further, before the control module judges whether the utility power value is greater than the preset utility power anti-reverse flow threshold value, it further comprises:

[0019] The control module compares the state of charge of the energy storage battery with the preset energy storage battery discharge depth, and if the state of charge of the energy storage battery is less than the energy storage battery discharge depth, the control module controls the energy storage converter to shut down; if the state of charge of the energy storage battery is greater than the energy storage battery discharge depth, the control module judges whether the utility power value is greater than the utility power anti-reverse flow threshold value.

[0020] Further, before the control module judges whether the utility power value is less than the preset transformer maximum load value, it further comprises:

[0021] The control module compares the state of charge of the energy storage battery with the preset energy storage battery discharge depth, and if the state of charge of the energy storage battery is less than the energy storage battery discharge depth, the control module controls the energy storage converter to shut down; if the state of charge of the energy storage battery is greater than the energy storage battery discharge depth, the control module judges whether the utility power value is greater than the utility power anti-reverse flow threshold value.

[0022] Further, the charging and discharging control method further comprises:

[0023] When the energy storage converter is in the shutdown state, the control module judges whether the state of charge of the energy storage battery is greater than the energy storage battery discharge depth, and if yes, the control module controls the energy storage device to discharge; if no, the control module controls the energy storage device to charge.

[0024] Further, before the control module controls the energy storage device to discharge, it further comprises:

[0025] Comparing whether the utility power value is greater than the utility power anti-reverse flow threshold value, if the utility power value is greater than the utility power anti-reverse flow threshold value, the control module controls the energy storage converter to start and switch to the discharging mode.

[0026] Further, before the control module controls the energy storage device to charge, it further comprises:

[0027] comparing the utility power value with the transformer maximum load value, if the utility power value is less than the transformer maximum load value, the control module controls the energy storage converter to start and switch to the charging mode.

[0028] Further, the discharging power of the energy storage converter is obtained by the following formula:

[0029] P o = P' o * I o

[0030] In the formula, P o is the discharging power of the energy storage converter, P' o is the maximum discharging power of the energy storage battery, I o is the discharging power growth coefficient of the energy storage battery.

[0031] Further, the charging power of the energy storage converter is obtained by the following formula:

[0032] P i = P' i * I i

[0033] In the formula, P i is the charging power of the energy storage converter, P' i is the maximum charging power of the energy storage battery, I i is the charging power growth coefficient of the energy storage battery.

[0034] The present application has the following advantages:

[0035] a) without affecting the cyclic charging and discharging operation of the energy storage device in the micro-grid, the occurrence of the reverse power transmission of the energy storage device or the overloading operation of the user transformer can be effectively avoided;

[0036] b) without collecting a large amount of historical data of users, only a small number of rated parameters need to be set, and the system will not be invalid due to the change of the power consumption situation;

[0037] c) the working process is simple, the flow is clear, and the operation is convenient. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0039] Figure 1A structural schematic diagram of a micro-grid provided by an embodiment of the present application is shown in the figure;

[0040] Figure 2 A flowchart of a charge-discharge control method of an energy storage device provided by an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0041] In order to make the personnel in the technical field better understand the present application scheme, more clearly understand the purpose, technical scheme and advantages of the present application, the technical scheme in the embodiment of the present application is described clearly and completely in the following combined with specific embodiments and referring to the drawings. It should be noted that the implementation mode not shown or described in the drawings is the form known by the ordinary skilled in the art. In addition, although this article can provide an example of the parameter containing a specific value, it should be understood that the parameter does not need to be exactly equal to the corresponding value, but can be approximately equal to the corresponding value within the acceptable error tolerance or design constraint. Obviously, the described embodiment is only an embodiment of part of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by the ordinary skilled in the art without creative labor should belong to the scope of protection of the present application. In addition, the terms "include" and "have" in the specification and claims of the present application and any modification thereof are intended to cover non-exclusive inclusion, for example, the process, method, device, product or equipment containing a series of steps or units does not have to be limited to the clearly listed steps or units, but can include other steps or units not clearly listed or inherent to these processes, methods, products or equipment.

[0042] In an embodiment of the present application, a charge-discharge control method of an energy storage device is provided, which is used to prevent the problems of reverse power flow and transformer overload in a micro-grid, as shown in the figure. Figure 1 As shown in the figure, the micro-grid includes a commercial power supply, an energy storage device and a control module. The energy storage device is a general term for all devices used to realize charge and discharge of energy storage batteries in an energy storage system.

[0043] The energy storage device includes an energy storage battery and an energy storage converter (PCS) matched with the energy storage battery. The energy storage converter is a converter connected between the battery system and the grid (and / or load) in the electrochemical energy storage system to realize bidirectional conversion of electric energy. The energy storage converter has a charging mode and a discharging mode. In the charging mode, the energy storage converter controls the charging of the energy storage battery, and in the discharging mode, the energy storage converter controls the discharging of the energy storage battery.

[0044] The control module is connected with the mains power supply and the energy storage device respectively, and is used for acquiring the state of charge of the energy storage battery, the working mode and working power of the energy storage converter, and the mains power value of the mains power supply in real time, and controlling the energy storage device to charge or discharge.

[0045] As shown in Figure 2 The charging and discharging control method of the energy storage device includes that the control module judges the working state of the energy storage converter:

[0046] (1) When the working mode of the energy storage converter is the discharging mode, the control module judges whether the mains power value is greater than a preset mains power anti-flow threshold value:

[0047] (1) When the working mode of the energy storage converter is the discharging mode, the control module judges whether the mains power value is greater than a preset mains power anti-flow threshold value:

[0048] If not, that is, the mains power value is less than the mains power anti-flow threshold value, which means that the energy storage device has the risk of reverse grid connection, the control module controls the energy storage converter to reduce the discharging power.

[0049] If yes, that is, the mains power value is greater than the mains power anti-flow threshold value, the control module compares the current discharging power of the energy storage converter with the maximum discharging power of the energy storage battery, and if the current discharging power of the energy storage converter is less than the maximum discharging power of the energy storage battery, the control module controls the energy storage converter to increase the discharging power.

[0050] In an embodiment of the present application, as shown in Figure 2 Before the control module judges whether the mains power value is greater than the preset mains power anti-flow threshold value, the control module further compares the state of charge of the energy storage battery with a preset energy storage battery discharging depth:

[0051] If the state of charge of the energy storage battery is less than the energy storage battery discharging depth, the control module controls the energy storage converter to shut down.

[0052] If the state of charge of the energy storage battery is greater than the energy storage battery discharging depth, the control module judges whether the mains power value is greater than the mains power anti-flow threshold value.

[0053] (2) When the working mode of the energy storage converter is the charging mode, the control module judges whether the power value of the commercial power is less than the preset transformer maximum load value,

[0054] If not, that is, the power value of the commercial power is greater than the transformer maximum load value, which means that the transformer has an overload problem, the control module controls the energy storage converter to reduce the charging power;

[0055] If yes, that is, the power value of the commercial power is less than the transformer maximum load value, the control module compares the current charging power of the energy storage converter with the maximum charging power of the energy storage converter, and if the current charging power of the energy storage converter is less than the maximum charging power of the energy storage battery, the control module controls the energy storage converter to increase the charging power.

[0056] In an embodiment of the present application, as shown in Figure 2 Before the control module judges whether the power value of the commercial power is less than the preset transformer maximum load value, the control module further compares the state of charge of the energy storage battery with the preset energy storage battery charging depth, and if the state of charge of the energy storage battery is greater than the energy storage battery charging depth, the control module controls the energy storage converter to shut down; if the state of charge of the energy storage battery is less than the energy storage battery charging depth, the control module judges whether the power value of the commercial power is less than the preset transformer maximum load value.

[0057] (2) When the energy storage converter is in the shutdown state, the control module judges whether the state of charge of the energy storage battery is greater than the energy storage battery discharge depth:

[0058] If yes, that is, the state of charge of the energy storage battery is greater than the energy storage battery discharge depth, the control module controls the energy storage device to discharge;

[0059] If not, that is, the state of charge of the energy storage battery is less than the energy storage battery discharge depth, the control module controls the energy storage device to charge.

[0060] In an embodiment of the present application, as shown in Figure 2 Before the control module controls the energy storage device to discharge, the control module further compares whether the power value of the commercial power is greater than the commercial power anti-backflow threshold value:

[0061] If the power value of the commercial power is greater than the commercial power anti-backflow threshold value, the control module controls the energy storage converter to start and switch to the discharge mode.

[0062] In an embodiment of the present application, as shown in Figure 2As shown, before the control module controls the energy storage device to charge, it also compares whether the mains power value is less than the transformer's maximum load value:

[0063] If the mains power value is less than the transformer's maximum load value, the control module controls the energy storage converter to start up and switch to charging mode.

[0064] It should be noted that comparing the mains power and the mains power reverse current protection threshold, especially when the mains power is less than or equal to the mains power reverse current protection threshold, indicates that once the energy storage battery discharges, it may reverse to the grid, so the energy storage battery should not be discharged.

[0065] The depth of charge of the energy storage battery is the maximum state of charge (SOC) that the battery can reach during charging. If the state of charge of the energy storage battery is less than the preset depth of charge, it means that the energy storage battery has the ability to be charged and can be controlled to charge. Otherwise, it means that the energy storage battery can no longer be charged.

[0066] The depth of discharge of the energy storage battery is the minimum state of charge (SOC) that the battery can reach during discharge. If the state of charge of the energy storage battery is greater than the preset depth of discharge, it means that the energy storage battery has the ability to discharge and can be controlled to discharge. Otherwise, it means that the energy storage battery can no longer discharge.

[0067] In one embodiment of the present invention, a method for calculating the charging power of the energy storage converter is provided, which is obtained through the following formula:

[0068] P i =P′ i ×I i

[0069] In the formula, P i P′ is the charging power of the energy storage converter. i I is the maximum charging power of the energy storage battery. i The charging power growth factor of the energy storage battery.

[0070] It should be noted that in scenarios where the user's power consumption is normal, the user's power consumption is too low but the photovoltaic device is still generating electricity or the energy storage device is still discharging, or the user's power consumption is too high but the energy storage device is still charging, the charging power of the energy storage converter needs to be adjusted. The specific values ​​may be different or equal, and this does not limit the scope of protection of the present invention.

[0071] In one embodiment of the present invention, a method for calculating the discharge power of the energy storage converter is provided, which is obtained through the following formula:

[0072] P o =P′o ×I o

[0073] In the formula, P o The discharge power of the energy storage converter, P' o The maximum discharge power of the energy storage battery, I o The discharge power growth coefficient of the energy storage battery.

[0074] It should be noted that in the scenarios where the user power is normal, the user power is too low but the photovoltaic device is still generating power or the energy storage device is still discharging, or the user power is too high but the energy storage device is still charging, the discharge power of the energy storage converter needs to be adjusted, and the specific values can be different or equal, which does not limit the protection scope of the present application.

[0075] In an embodiment of the present application, a charge and discharge control system of an energy storage device is provided, which operates based on the charge and discharge control method of the energy storage device described in the above embodiment.

[0076] In an embodiment of the present application, a charge and discharge control system of an energy storage device is provided, and the related configuration parameters are shown in Table 1:

[0077] Table 1. Configuration parameter table

[0078]

[0079] Specifically, the present embodiment includes the following processes and steps:

[0080] 1. Collect user power consumption period information, energy storage device and transformer rated parameters.

[0081] 2. In the configuration table, enter the collected information as the judgment conditions of each process when the system runs.

[0082] 3. In the configuration table, input the battery charge power growth coefficient and the battery discharge power growth coefficient. These two parameters are the key parameters for the operation of the system, which specify the specific values of the adjustment of the charge and discharge power of the energy storage device in the scenarios where the user power is normal, the user power is too low but the energy storage device is still discharging, or the user power is too high but the energy storage device is still charging. Through these two parameters, the system realizes the automatic adjustment of the charge and discharge power without manual operation during the cyclic charge and discharge operation of the energy storage device.

[0083] 4. In the configuration table, input the transformer highest load rate and the city power anti-backflow threshold. These two parameters are also the key parameters for the operation of the system, which specify when the strategy needs to adjust the charge and discharge power of the energy storage device and the direction of the adjustment (increase or decrease).

[0084] 5. The micro-grid adjusts the charge-discharge power of the energy storage device according to the output instruction.

[0085] The idea of the charge-discharge control system embodiment is the same as the working process of the charge-discharge control method in the above embodiment, and the entire content of the charge-discharge control method embodiment is incorporated herein by reference.

[0086] The present application focuses on improving the existing scheme in the micro-grid, which does not design the energy storage circulating charge-discharge strategy to prevent reverse flow and transformer overload, resulting in that the energy storage device cannot adjust the charge-discharge power in real time according to the user's power consumption, and thus the problem of reverse power flow of the energy storage device or overload operation of the user transformer is prone to occur. The present application provides a charge-discharge control method of an energy storage device which can prevent reverse flow and transformer overload, and does not need frequent manual operation, but only needs to set the operating conditions in advance to automatically operate. After operation, it does not affect the circulating charge-discharge operation of the energy storage device in the micro-grid, and can effectively avoid the occurrence of reverse power flow of the energy storage device or overload operation of the user transformer.

[0087] The above is only the preferred embodiment of the present application, and does not limit the patent scope, and any equivalent structure or equivalent flow conversion using the content of the specification and drawings, direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A charge and discharge control method of an energy storage device, characterized by, A method for preventing power reverse flow and transformer overload in a micro-grid, the micro-grid comprising: a utility power supply; a storage device comprising a storage battery and a storage converter cooperating with the storage battery, the storage converter having a charging mode and a discharging mode, in the charging mode, the storage converter is capable of controlling the storage battery to charge, in the discharging mode, the storage converter is capable of controlling the storage battery to discharge; a control module connected with the utility power supply and the storage device respectively, the control module is used to acquire the state of charge of the storage battery, the working mode and working power of the storage converter, and the utility power value of the utility power supply in real time, and control the storage device to charge or discharge; the charging and discharging control method comprises: configuring a configuration table of the charging and discharging control system of the storage device, collecting user power consumption period information, storage device and transformer rated parameters and inputting the configuration table; setting the storage battery operating conditions and the utility conditions in the configuration table, the storage battery operating conditions include the battery charging power growth coefficient and the battery discharging power growth coefficient, and the utility conditions include the transformer maximum load rate, the transformer maximum load and the utility power anti-flow threshold value; the charging and discharging control method further comprises determining the storage battery operating conditions: the storage battery charging power growth coefficient and the storage battery discharging power growth coefficient are selected from 1%, 2%, 4%, 5%, 10%, 20%, 25% and 50%; determining the utility conditions: the transformer maximum load rate <100-(storage battery rated charging power*storage battery charging power growth coefficient) / utility transformer rated power*100, the transformer maximum load value is automatically calculated and generated, and the utility power anti-flow threshold value > storage battery rated discharging power*storage battery discharging power growth coefficient / 100, the unit of the transformer maximum load rate is %, and the unit of the utility power anti-flow threshold value is kW; when the working mode of the storage converter is the discharging mode, the control module judges whether the utility power value is greater than the preset utility power anti-flow threshold value, if not, the control module controls the storage converter to reduce the discharging power; when the working mode of the storage converter is the charging mode, the control module judges whether the utility power value is less than the preset transformer maximum load value, if not, the control module controls the storage converter to reduce the charging power.

2. The charge and discharge control method of an energy storage device according to claim 1, wherein when the working mode of the storage converter is the discharging mode, if the utility power value is greater than the utility power anti-flow threshold value, the control module compares the current discharging power of the storage converter with the maximum discharging power of the storage battery, if the current discharging power of the storage converter is less than the maximum discharging power of the storage battery, the control module controls the storage converter to increase the discharging power.

3. The charge and discharge control method of an energy storage device according to claim 1, wherein When the working mode of the energy storage converter is the charging mode, if the mains power value is less than the transformer maximum load value, the control module compares the current charging power of the energy storage converter with the maximum charging power of the energy storage converter, and if the current charging power of the energy storage converter is less than the maximum charging power of the energy storage battery, the control module controls the energy storage converter to increase the charging power.

4. The charge and discharge control method of an energy storage device according to claim 1, wherein Before the control module judges whether the mains power value is greater than the preset mains power anti-reverse flow threshold, the method further comprises: The control module compares the state of charge of the energy storage battery with the preset energy storage battery discharge depth, and if the state of charge of the energy storage battery is less than the energy storage battery discharge depth, the control module controls the energy storage converter to shut down; if the state of charge of the energy storage battery is greater than the energy storage battery discharge depth, the control module judges whether the mains power value is greater than the mains power anti-reverse flow threshold.

5. The charge and discharge control method of an energy storage device according to claim 1, wherein Before the control module judges whether the mains power value is less than the preset transformer maximum load value, the method further comprises: The control module compares the state of charge of the energy storage battery with the preset energy storage battery discharge depth, and if the state of charge of the energy storage battery is less than the energy storage battery discharge depth, the control module controls the energy storage converter to shut down; if the state of charge of the energy storage battery is greater than the energy storage battery discharge depth, the control module judges whether the mains power value is greater than the mains power anti-reverse flow threshold.

6. The charge and discharge control method of an energy storage device according to claim 1, wherein The charging and discharging control method further comprises: When the energy storage converter is in the shutdown state, the control module judges whether the state of charge of the energy storage battery is greater than the energy storage battery discharge depth, and if yes, the control module controls the energy storage device to discharge; and if no, the control module controls the energy storage device to charge.

7. The charge and discharge control method of an energy storage device according to claim 6, wherein Before the control module controls the energy storage device to discharge, the method further comprises: comparing whether the mains power value is greater than the mains power anti-reverse flow threshold, and if the mains power value is greater than the mains power anti-reverse flow threshold, the control module controls the energy storage converter to start and switch to the discharging mode.

8. The charge and discharge control method of an energy storage device according to claim 1, wherein Before the control module controls the energy storage device to charge, the method further comprises: comparing whether the mains power value is less than the transformer maximum load value, and if the mains power value is less than the transformer maximum load value, the control module controls the energy storage converter to start and switch to the charging mode.

9. The charge and discharge control method of an energy storage device according to claim 2, wherein The discharging power of the energy storage converter is obtained by the following formula: P o = P' o x I o where P o the discharge power of the energy storage inverter, P' o the maximum discharge power of the energy storage battery, I o a discharge power growth coefficient of the energy storage battery.

10. The charge and discharge control method of an energy storage device according to claim 3, wherein The charging power of the energy storage converter is obtained by the following formula: P i = P' i x I i In the formula, P i is the charging power of the energy storage converter, P' i is the maximum charging power of the energy storage battery, I i is the charging power growth coefficient of the energy storage battery.

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