Energy storage power supply system, control method and application

Abstract

The invention relates to an energy storage power supply system, a control method and application, and belongs to the technical field of energy storage batteries. The energy storage power supply system comprises a power supply unit which comprises an energy storage converter and a plurality of battery bins, and the battery bins are connected with the direct current side of the energy storage converter in parallel; the alternating current sides of the energy storage converters of the plurality of power supply units are connected in parallel and then are connected with a load; the multiple power supply units are used for replacing a diesel generator for power supply, the resource utilization efficiency is higher, and pollution is small. In order to meet the requirement for high power of the load, a dynamic selection mode is adopted for the voltage source, when the load needs to be discharged every time, the SOC value of a battery bin of each power supply unit is used for determining the energy storage converter serving as the voltage source, it can be ensured that the voltage source can stably operate for a long time under load fluctuation, the system efficiency is high, and the system reliability is high. The energy storage converters of other power supply units are used as current sources.

Description

TECHNICAL FIELD

[0001] The application relates to an energy storage power supply system, a control method and application, and belongs to the technical field of energy storage batteries. BACKGROUND

[0002] In oilfield development, a traditional method is to use a high-power diesel generator to supply power to on-site oilfield development equipment, which is extremely low in energy utilization efficiency and seriously pollutes the environment.

[0003] The prior art has disclosed other technical solutions that can replace the pure use of a diesel generator for power supply. Chinese Patent Application No. 2025100571561 discloses a network electric drilling rig oil-electric hybrid linkage power supply system and a control method. The solution uses an electric network and a diesel generator to switch power supply. According to the power capacity gap, the number of diesel generator sets is selected to start and flexible power regulation is performed. The energy storage module is used to regulate the grid power and the reactive power, the smooth switching of the diesel generator set and the grid-side power supply is realized, the smooth output of the network electric drilling rig system power is realized, and the mutual impact of the grid-side power supply and the diesel generator set current is prevented. However, the solution still relies on the diesel generator set for power supply, and the energy utilization efficiency is limited and the pollution is large. SUMMARY

[0004] The purpose of the present application is to provide an energy storage power supply system, a control method and application, which completely replace the diesel generator for power supply by using multiple power supply units, has higher resource utilization efficiency and less pollution, and in order to meet the demand of high power of the load, the application adopts a dynamic selection method for the voltage source, and selects the energy storage converter of the power supply unit with the most stable SOC value as the voltage source each time, which can ensure that the voltage source remains stable for a long time under load fluctuation, and the system power supply efficiency is high.

[0005] In a first aspect, the application provides an energy storage power supply system, which comprises: a power supply unit, comprising an energy storage converter and a plurality of battery compartments, the plurality of battery compartments being connected in parallel with the direct current side of the energy storage converter; the power supply unit is provided with a plurality of power supply units, and the alternating current sides of the energy storage converters of the plurality of power supply units are connected in parallel and then connected to the load; a battery management system and an energy management system, each power supply unit being provided with a battery management system in communication connection with the battery compartment, and the energy management system being in communication connection with the battery management system and the energy storage converter; The battery management system is used for collecting the SOC value of the battery compartment of the corresponding power supply unit in real time and sending it to the energy management system. The energy management system is configured to, when discharging to the load is required, select, according to the received battery compartment SOC values of each power supply unit, a power supply unit with the minimum average change rate of the battery compartment SOC value in the previous discharge period, and send a voltage source instruction to the energy storage converter of the power supply unit to start discharging in the voltage source mode, while sending a current source instruction to the energy storage converters of other power supply units to follow discharging in the current source mode.

[0006] The present application uses multiple power supply units to replace diesel generators for power supply, has higher resource utilization efficiency and less pollution. In order to meet the high-power demand of the load, the present application adopts a dynamic selection mode for the voltage source, and uses the battery compartment SOC value of each power supply unit to determine the energy storage converter as the voltage source each time discharging to the load is required, while the energy storage converters of other power supply units follow discharging as the current source. The present application selects the energy storage converter of the power supply unit with the most stable SOC value change as the voltage source each time power supply is required, which can ensure that the voltage source remains stable for a long time under load fluctuation, has higher system power supply efficiency, can protect other power supply units to optimize system life, reduces the switching frequency of the voltage source, and improves the continuity of overall power supply.

[0007] Optionally, the battery management system is further configured to calibrate the battery compartment SOC value before collecting the battery compartment SOC value.

[0008] The present application can ensure that the data sent to the energy management system is real and reliable by calibrating the battery compartment SOC value, so as to ensure the rationality of the subsequent voltage source selection decision of the energy management system according to the battery compartment SOC value.

[0009] Optionally, the energy management system is configured to determine the average change rate of the battery compartment SOC value of the power supply unit in the discharge period in the following manner: calculate the SOC average value of the power supply unit according to all the battery compartment SOC values of the power supply unit; record the SOC average values at the starting time and the ending time for each time interval of the discharge period; calculate the SOC change rate of the power supply unit in the time interval according to the SOC average values at the starting time and the ending time and the time length of the time interval; and calculate the average value of the SOC change rates of all the time intervals in the discharge period as the average change rate of the battery compartment SOC value.

[0010] The application uses the average value of the SOC change rate of all time intervals in the discharge cycle as the average change rate of the battery compartment SOC value in the discharge cycle, and the average change rate of the battery compartment SOC value can effectively represent the power supply stability of the power supply unit, so as to accurately identify the power supply unit with better performance, so that the average change rate of the battery compartment SOC value in the previous discharge cycle is used as the basis for voltage source selection each time the load needs to be discharged, and the power supply reliability of the system can be ensured.

[0011] Optionally, if the battery compartment SOC values of all power supply units are 100%, the energy management system directly sends a voltage source instruction to the energy storage converter of the power supply unit with the specified number to start discharging in the voltage source mode, and sends a current source instruction to the energy storage converters of other power supply units to follow the discharging in the current source mode.

[0012] The application can skip the voltage source selection process when all battery compartments of all power supply units are fully charged, and the performance of each power supply unit is better, so that a voltage source instruction is directly sent to the energy storage converter of the power supply unit with the specified number to start discharging in the voltage source mode, and a current source instruction is sent to the energy storage converters of other power supply units to follow the discharging in the current source mode, thereby improving the response speed of the system power supply.

[0013] Optionally, the application further comprises: A disconnection circuit, and each battery compartment in each power supply unit is connected in parallel with the corresponding energy storage converter DC side through the disconnection circuit, and the disconnection circuit can control the on-off of the connection circuit of the battery compartment and the energy storage converter DC side.

[0014] The application can disconnect each battery compartment in the power supply unit from the corresponding energy storage converter DC side without affecting other parallel battery compartments. When a certain battery compartment fails or has low power or needs maintenance, it can be disconnected in time, and the entire power supply system does not need to be powered off and stopped, and the power supply continuity is strong.

[0015] Optionally, the disconnection circuit is in communication connection with the energy management system. The energy management system is used to determine the battery compartment with a SOC value lower than the preset SOC value as a target battery compartment when there is a battery compartment with a SOC value lower than the preset SOC value in the received battery compartment SOC values of each power supply unit, send a switch opening instruction to the disconnection circuit of the power supply unit to which the target battery compartment belongs, disconnect the connection circuit of the target battery compartment and the corresponding energy storage converter DC side, and send a cluster shortage operation instruction to the battery management system of the power supply unit, so that the battery management system controls the remaining battery compartments to operate in the cluster shortage mode. The battery management system is used for being communicatively connected with the spare battery compartment after the target battery compartment is replaced by the spare battery compartment, and sending a battery compartment ready signal to an energy management system after passing the power-on check of the spare battery compartment, the energy management system is used for sending a switch closing instruction to a breaking circuit after receiving the battery compartment ready signal, making the spare battery compartment communicate with a wiring circuit on a direct current side of a corresponding energy storage converter, and sending a whole cluster operation instruction to a battery management system of a power supply unit, so that the battery management system controls all battery compartments to operate in a whole cluster mode.

[0016] The application can replace the battery compartment in real time on the premise of uninterrupted power supply of the system based on the breaking circuit, can ensure the rapidness of high-power battery replacement, and also ensures the continuity of equipment power supply. Specifically, the battery compartment with a SOC value lower than a preset SOC value (the battery compartment has insufficient power, which may affect the overall power supply efficiency) is determined as a target battery compartment, a switch opening instruction is sent to the breaking circuit of the power supply unit to which the target battery compartment belongs, so that the target battery compartment is disconnected from the wiring circuit on the direct current side of the corresponding energy storage converter, and a lack cluster operation instruction is sent to the battery management system of the power supply unit, so that the battery management system controls the remaining battery compartments to operate in a lack cluster mode, so that the offline isolation of the battery compartment with low power is completed without affecting the normal discharge of the system. After the target battery compartment is replaced, the battery management system is communicatively connected with the replaced spare battery compartment and performs a power-on check on the spare battery compartment to ensure the safety of discharge, and sends a battery compartment ready signal to the energy management system after the power-on check passes, the energy management system sends a switch closing instruction to the breaking circuit after receiving the battery compartment ready signal, so that the spare battery compartment communicates with the wiring circuit on the direct current side of the corresponding energy storage converter, and sends a whole cluster operation instruction to the battery management system of the power supply unit, so that the battery management system controls all battery compartments to operate in a whole cluster mode.

[0017] Optionally, the energy management system is also used for sending a power sharing signal to each energy storage converter in a current source mode during discharge to the load, so that each energy storage converter in the current source mode shares the remaining load power after the energy storage converter in the voltage source mode starts discharging.

[0018] The application can complete the whole process of battery compartment replacement on the premise of uninterrupted power supply of the system by using the breaking circuit, and the SOC value of the battery compartment of each power supply unit can be maintained in a high state through real-time replacement of the battery compartment. Therefore, after the voltage source is determined according to the average change rate of the SOC value, the remaining load power after the energy storage converter in the voltage source mode starts discharging can be directly distributed to each energy storage converter in the current source mode during discharge to the load, without further adjusting the distribution strategy according to the actual power of the battery compartment, so that the control is simplified.

[0019] In a second aspect, the present application provides a control method of an energy storage power supply system, comprising: obtaining the SOC value of the battery compartment of each power supply unit; when discharging to the load is needed, selecting the power supply unit with the minimum average change rate of the SOC value of the battery compartment in the previous discharge period from each power supply unit according to the received SOC value of the battery compartment of each power supply unit; sending a voltage source instruction to the energy storage converter of the power supply unit to start discharging in voltage source mode, and sending a current source instruction to the energy storage converter of other power supply units to follow discharging in current source mode.

[0020] The energy storage power supply system of the present application can ensure that the voltage source remains stable for a long time under load fluctuations, has high system efficiency, can protect other power supply units to optimize system life, reduces the switching frequency of the voltage source, and improves the continuity of overall power supply.

[0021] Optionally, the determination method of the average change rate of the SOC value of the battery compartment of each power supply unit in the discharge period comprises: calculating the SOC average value of the power supply unit according to all the SOC values of the battery compartment of the power supply unit; for each time interval of the discharge period, recording the SOC average values at the start time and the end time; calculating the SOC change rate of the power supply unit in the time interval according to the SOC average values at the start time and the end time and the length of the time interval; calculating the average value of the SOC change rates of all time intervals in the discharge period as the average change rate of the SOC value of the battery compartment.

[0022] The present application uses the average value of the SOC change rates of all time intervals in the discharge period as the average change rate of the SOC value of the battery compartment in the discharge period, which can effectively represent the power supply stability of the power supply unit, accurately identify the power supply unit with better performance, and thus select the voltage source according to the average change rate of the SOC value of the battery compartment in the previous discharge period each time discharging to the load is needed, which can ensure the power supply reliability of the system.

[0023] In a third aspect, the present application provides an application of the energy storage power supply system, which is applied to oilfield development equipment.

[0024] The energy storage power supply system of the present application can completely replace diesel generators for power supply when applied to oilfield development equipment, has higher resource utilization efficiency and less pollution.

[0025] Compared with the prior art, the present application has the beneficial effects: The present application completely replaces the diesel generator for power supply by multiple power supply units, has higher resource utilization efficiency and less pollution, and in order to meet the high-power demand of the load, the present application adopts a dynamic selection mode for the voltage source, and each time the power supply selects the energy storage converter of the power supply unit with the most stable SOC value change as the voltage source, which can ensure that the voltage source remains stable for a long time under load fluctuation, and the system power supply efficiency is higher. Moreover, the present application uses a breaking circuit to complete the entire process of battery compartment replacement under the premise of uninterrupted power supply of the system, and through real-time replacement of the battery compartment, the SOC value of the battery compartment of each power supply unit can be kept in a higher state. Therefore, after the voltage source is determined according to the average change rate of the SOC value, when discharging to the load, the remaining load power after the energy storage converter of the voltage source mode starts discharging can be directly distributed to each energy storage converter in current source mode following the discharge, without further adjusting the distribution strategy according to the actual power of the battery compartment, thereby simplifying the control. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The present application provides a principle schematic diagram of an energy storage power supply system. Figure 2 The present application provides a control flowchart of an energy storage power supply system. DETAILED DESCRIPTION

[0027] It should be noted that: The technical solutions of the present application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific features of the embodiments and the specific features in the embodiments are detailed descriptions of the technical solutions of the present application, and are not limitations of the technical solutions of the present application. In the case of no conflict, the technical features in the embodiments and the specific features in the embodiments can be combined with each other.

[0028] The term "and / or", only describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / ", generally represents that the front and rear associated objects are in an "or" relationship.

[0029] In combination with Figure 1The embodiment provides a power storage and supply system, and the power storage and supply system is applied to oilfield development equipment in the embodiment, and the power storage and supply system comprises a power supply unit, a battery management system (BMS) and an energy management system (EMS). The power supply unit comprises a power storage converter and a plurality of battery compartments, and the plurality of battery compartments are connected in parallel with a direct current side of the power storage converter (PCS). The power supply unit is provided with a plurality of power supply units, and the alternating current sides of the power storage converters of the plurality of power supply units are connected in parallel and then connected to a load. Each power supply unit is provided with the battery management system which is in communication connection with the battery compartments, and the energy management system is in communication connection with the battery management system and the power storage converter.

[0030] In combination Figure 2 The battery management system is used for collecting the SOC values of the battery compartments of the corresponding power supply unit in real time and sending the SOC values to the energy management system. The energy management system is used for selecting the power supply unit with the minimum average change rate of the SOC values of the battery compartments in the previous discharge period from the power supply units according to the received SOC values of the battery compartments of the power supply units, sending a voltage source instruction to the power storage converter of the power supply unit to start discharging in the voltage source mode, and sending a current source instruction to the power storage converters of the other power supply units to follow discharging in the current source mode when discharging to the load is needed.

[0031] The embodiment uses a plurality of power supply units to replace a diesel generator to supply power, and resource utilization efficiency is higher and pollution is smaller. In order to meet the demand of high power of the load, the embodiment adopts a dynamic selection mode for the voltage source, and the power storage converter of each power supply unit is determined as the voltage source according to the SOC values of the battery compartments of the power supply units when discharging to the load is needed each time, and the power storage converters of the other power supply units are used as the current source to follow discharging. The power storage converter of the power supply unit with the most stable SOC value is selected as the voltage source each time, the voltage source can keep stable operation for a long time under load fluctuation, the system efficiency is higher, the other power supply units can be protected to optimize the system life, the switching frequency of the voltage source is reduced, and the continuity of overall power supply is improved.

[0032] The battery management system is also used for calibrating the battery compartment SOC value before collecting the battery compartment SOC value. The embodiment can ensure that the data sent to the energy management system is real and reliable, so as to ensure the rationality of the subsequent voltage source selection of the energy management system according to the battery compartment SOC value. If the battery compartment SOC values of all power supply units are 100%, the energy management system directly sends a voltage source instruction to the energy storage converter of the power supply unit with the specified number to start discharging in the voltage source mode, and sends a current source instruction to the energy storage converters of other power supply units to follow the discharging in the current source mode. The performance of each power supply unit is better when the battery compartments of all power supply units are fully charged, and at this time, the voltage source selection process can be skipped, and the voltage source instruction is directly sent to the energy storage converter of the power supply unit with the specified number to start discharging in the voltage source mode, and the current source instruction is sent to the energy storage converters of other power supply units to follow the discharging in the current source mode, thereby improving the response speed of the system power supply.

[0033] The determination method of the average change rate of the battery compartment SOC value of each power supply unit in the discharging period includes: calculating the SOC average value of the power supply unit according to all the received battery compartment SOC values; for each time interval of the discharging period, recording the SOC average values at the starting time and the ending time; calculating the SOC change rate of the power supply unit in the time interval according to the SOC average values at the starting time and the ending time and the time length of the time interval, and the calculation formula of the SOC change rate is: ; wherein Vsoc is the SOC change rate, SOC t1 is the SOC average value at the ending time t1, and SOC t0 is the SOC average value at the starting time t0.

[0034] The average value of the SOC change rates of all time intervals in the discharging period is calculated as the average change rate of the battery compartment SOC value.

[0035] As an example, a discharging period is set to 24h, the time length of the time interval t1-t0 is set to 1h, and the calculation formula of the average change rate of the battery compartment SOC value in the discharging period is: ; wherein Vsoc1, Vsoc2, …, are the SOC change rates of each hour of 24h.

[0036] The embodiment takes the average value of the SOC change rate of all time intervals in the discharge period as the average change rate of the battery compartment SOC value in the discharge period, and the average change rate of the battery compartment SOC value can effectively represent the power supply stability of the power supply unit, so as to accurately identify the power supply unit with better performance, thereby ensuring the power supply reliability of the system.

[0037] In addition, the energy storage power supply system of the embodiment further comprises a disconnecting circuit, and each battery compartment in each power supply unit is connected in parallel with the corresponding energy storage converter DC side through the disconnecting circuit. The disconnecting circuit can control the on-off of the wiring circuit of the battery compartment and the energy storage converter DC side. In the embodiment, each battery compartment in the power supply unit can be disconnected from the corresponding energy storage converter DC side without affecting other battery compartments in parallel. When a certain battery compartment fails or has low power or needs maintenance, it can be disconnected in time, and the entire power supply system does not need to be powered off and stopped, and the power supply continuity is strong.

[0038] The disconnecting circuit is in communication connection with the energy management system. When the received battery compartment SOC value includes a battery compartment with a SOC value lower than a preset SOC value, the energy management system determines the battery compartment with the SOC value lower than the preset SOC value as a target battery compartment, sends a switch opening instruction to the disconnecting circuit of the power supply unit to which the target battery compartment belongs, disconnects the wiring circuit of the target battery compartment and the corresponding energy storage converter DC side, and sends a cluster deficiency operation instruction to the battery management system of the power supply unit, so that the battery management system controls the remaining battery compartments to operate in a cluster deficiency mode. The battery management system is in communication connection with the backup battery compartment after the target battery compartment is replaced by the backup battery compartment, and sends a battery compartment ready signal to the energy management system after the backup battery compartment passes the power-on check. The energy management system sends a switch closing instruction to the disconnecting circuit after receiving the battery compartment ready signal, so that the wiring circuit of the backup battery compartment and the corresponding energy storage converter DC side are connected, and sends a cluster operation instruction to the battery management system of the power supply unit, so that the battery management system controls all battery compartments to operate in a cluster mode.

[0039] The embodiment is to maintain the high efficiency of the whole power supply system. Based on the set breaking circuit, the battery compartment replacement can be performed in real time under the premise of uninterrupted power supply of the system. Specifically, the battery compartment with a SOC value lower than a preset SOC value (for example, 95%) is determined as a target battery compartment. A switch opening instruction is sent to the breaking circuit of the power supply unit to which the target battery compartment belongs, so that the target battery compartment is disconnected from the wiring circuit on the DC side of the corresponding energy storage converter. At the same time, a cluster shortage operation instruction is sent to the battery management system of the power supply unit, so that the battery management system controls the remaining battery compartments to operate in a cluster shortage mode. Thus, the offline isolation of the low-power battery compartment is completed without affecting the normal discharge of the system. After the target battery compartment is replaced, the battery management system is in communication connection with the standby battery compartment after replacement and performs power-on inspection on the standby battery compartment to ensure the safety of discharge. After the power-on inspection is passed, the battery management system sends a battery compartment ready signal to the energy management system. After receiving the battery compartment ready signal, the energy management system sends a switch closing instruction to the breaking circuit, so that the standby battery compartment is connected to the wiring circuit on the DC side of the corresponding energy storage converter. At the same time, a cluster operation instruction is sent to the battery management system of the power supply unit, so that the battery management system controls all battery compartments to operate in a cluster mode.

[0040] The energy management system of the embodiment is also used to send a power sharing signal to each energy storage converter operating in a current source mode during discharge to the load, so that each energy storage converter operating in a current source mode shares the load power remaining after the energy storage converter operating in a voltage source mode starts discharging. The embodiment uses the breaking circuit to complete the whole process of battery compartment replacement under the premise of uninterrupted power supply of the system. Through real-time replacement of the battery compartment, the SOC value of each battery compartment of each power supply unit can be kept in a high state. Therefore, after the voltage source is determined according to the average change rate of the SOC value, the load power remaining after the energy storage converter operating in a voltage source mode starts discharging can be directly distributed to each energy storage converter operating in a current source mode during discharge to the load, without further adjusting the distribution strategy according to the actual power of the battery compartment, thereby simplifying the control.

[0041] In another specific embodiment, a control method of an energy storage system is provided, which is based on the energy storage power supply system and includes the following steps: The SOC value of each battery compartment of each power supply unit is obtained. When it is necessary to discharge to the load, the power supply unit with the minimum average change rate of the SOC value of the battery compartment in the previous discharge period is selected from each power supply unit according to the SOC value of the battery compartment of each power supply unit. A voltage source instruction is sent to the energy storage converter of the power supply unit, so that the energy storage converter starts discharging in a voltage source mode. At the same time, a current source instruction is sent to the energy storage converter of the other power supply unit, so that the energy storage converter follows the discharge in a current source mode.

[0042] The embodiment can ensure that the voltage source keeps stable operation for a long time under load fluctuation, has high system efficiency, can protect other power supply units to optimize system life, reduces the switching frequency of the voltage source, and improves the continuity of overall power supply.

[0043] Those skilled in the art will understand that embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) containing computer usable program code.

[0044] The present application is described with reference to flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as combinations of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus produce an apparatus that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 means for performing the function specified by one or more blocks

[0045] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to work in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including instruction means, which implements the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 means for performing the function specified by one or more blocks

[0046] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus, so that a series of operation steps are performed on the computer or other programmable data processing apparatus to produce a computer-implemented process, so that the instructions executed on the computer or other programmable data processing apparatus provide a process for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 means for performing the function specified by one or more blocks

[0047] The embodiments of the present application are described above with reference to the accompanying drawings, but the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are merely illustrative, but not restrictive, and a person of ordinary skill in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, and these all belong to the protection of the present application.

Claims

1. An energy storage power supply system, characterized by, The application relates to a power supply unit, a battery management system and an energy management system. The power supply unit comprises a storage converter and a plurality of battery compartments, and the plurality of battery compartments are connected in parallel with the direct-current side of the storage converter; a plurality of power supply units are arranged, and the alternating-current sides of the storage converters of the plurality of power supply units are connected in parallel and then connected to a load; Each power supply unit is provided with a battery management system in communication connection with the battery compartments, and the energy management system is in communication connection with the battery management system and the storage converter; The battery management system is used for collecting the SOC values of the battery compartments of the corresponding power supply unit in real time and sending the SOC values to the energy management system; When discharging to the load is needed, the energy management system selects the power supply unit with the minimum average change rate of the SOC values of the battery compartments in the previous discharging period from the power supply units according to the received SOC values of the battery compartments of the power supply units, sends a voltage source instruction to the storage converter of the power supply unit to make the storage converter start discharging in a voltage source mode, and sends a current source instruction to the storage converters of the other power supply units to make the storage converters follow discharging in a current source mode.

2. The energy storage power supply system of claim 1, wherein, The battery management system is also used for calibrating the SOC values of the battery compartments before collecting the SOC values.

3. The energy storage power supply system of claim 1, wherein, If the SOC values of the battery compartments of all the power supply units are 100%, the energy management system sends a voltage source instruction to the storage converter of the power supply unit with the specified number to make the storage converter start discharging in a voltage source mode, and sends a current source instruction to the storage converters of the other power supply units to make the storage converters follow discharging in a current source mode.

4. The energy storage power supply system of claim 1, wherein, The determination mode of the energy management system for the average change rate of the SOC values of the battery compartments of the power supply unit in the discharging period comprises the following steps: The SOC average value of the power supply unit is calculated according to all the SOC values of the battery compartments of the power supply unit; for each time interval of the discharging period, the SOC average values at the starting moment and the ending moment are recorded; the SOC change rate of the power supply unit in the time interval is calculated according to the SOC average values at the starting moment and the ending moment and the time length of the time interval; and the average value of the SOC change rates of all the time intervals in the discharging period is calculated as the average change rate of the SOC values of the battery compartments.

5. The energy storage power supply system of claim 1, wherein, The application further relates to a disconnection circuit. The battery compartments in each power supply unit are connected in parallel with the corresponding storage converter through the disconnection circuit, and the disconnection circuit can control the on-off of the wiring circuit of the battery compartments and the direct-current side of the storage converter.

6. The energy storage power supply system of claim 5, wherein, The disconnection circuit is in communication connection with the energy management system; When there is a battery compartment with an SOC value lower than a preset SOC value in the received SOC values of the battery compartments of the power supply units, the energy management system determines the battery compartment with the SOC value lower than the preset SOC value as a target battery compartment, sends a switch-off instruction to the disconnection circuit of the power supply unit to which the target battery compartment belongs, makes the wiring circuit of the target battery compartment and the direct-current side of the corresponding storage converter disconnected, and simultaneously sends a cluster-lacking operation instruction to the battery management system of the power supply unit, so that the battery management system controls the remaining battery compartments to operate in a cluster-lacking mode. The battery management system is configured to be communicatively connected with the backup battery compartment after the target battery compartment is replaced by the backup battery compartment, and send a battery compartment ready signal to an energy management system after the backup battery compartment passes a power-on check, the energy management system is configured to send a switch closing instruction to a disconnection circuit after receiving the battery compartment ready signal, so that the backup battery compartment is connected with a wiring circuit on the DC side of a corresponding energy storage converter, and send a whole cluster operation instruction to a battery management system of a power supply unit, so that the battery management system controls all battery compartments to operate in a whole cluster mode.

7. The energy storage power supply system of claim 6, wherein, The energy management system is also configured to send a power sharing signal to each energy storage converter operating in a current source mode when discharging to a load, so that each energy storage converter operating in the current source mode shares the remaining load power after the energy storage converter operating in a voltage source mode starts discharging.

8. A control method of the energy storage power supply system according to any one of claims 1 to 7, characterized by, The method comprises: obtaining the SOC values of the battery compartments of each power supply unit; when discharging to a load is needed, selecting a power supply unit with the smallest average change rate of the SOC values of the battery compartments in the previous discharge period from each power supply unit according to the SOC values of the battery compartments of each power supply unit; sending a voltage source instruction to the energy storage converter of the power supply unit to start discharging in a voltage source mode, and sending a current source instruction to the energy storage converters of other power supply units to follow discharging in a current source mode.

9. The control method of the energy storage power supply system according to claim 8, characterized by, The determination method of the average change rate of the SOC values of the battery compartments of each power supply unit in a discharge period comprises: calculating the average SOC value of the power supply unit according to the SOC values of all battery compartments of the power supply unit; for each time interval of the discharge period, recording the SOC average values at the starting time and the ending time; calculating the SOC change rate of the power supply unit in the time interval according to the SOC average values at the starting time and the ending time and the length of the time interval; calculating the average value of the SOC change rates of all time intervals in the discharge period as the average change rate of the SOC values of the battery compartments.

10. Application of the energy storage power supply system of any one of claims 1-7, wherein the energy storage power supply system is applied to oilfield development equipment.

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