Range-extending type energy storage system and control method

Abstract

The invention discloses a range-extended energy storage system and a control method. The range-extended energy storage system comprises a generator set, a battery pack, an AC / DC charger, a high-voltage box, a DC bus, an AC / DC bidirectional converter, a grid-side AC bus, a load-side AC bus, an energy management system (EMS), a charging pile and a photovoltaic inverter. The EMS comprises a load classification module, an early warning value management module, a load data recording module, an electricity price judgment module, an electricity price recording module, a parameter configuration module and a communication module. The extended-range energy storage control method comprises the steps of judging whether power is cut off or not, executing an off-grid or grid-connected strategy, obtaining an electricity price, executing a corresponding strategy according to a valley time period, a peak time period and a normal time period during grid connection and the like. According to specific conditions of a construction site, electric power generated by a photovoltaic generator and an electric generator can be quickly and conveniently dispatched, range extension is flexibly carried out through the energy storage equipment, dynamic control is achieved, and the site electric power dispatching capacity is improved.

Description

Technical Field

[0001] The present invention relates to the technical fields of energy storage and power distribution, and particularly to an extended-range energy storage system and a control method therefor. Background Art

[0002] In traditional outdoor construction environments, there are often problems with unstable power supply. Especially in remote areas or during emergency rescue operations, sudden power outages may seriously affect the project progress. Currently, the common method is to use a generator set. However, the load power is not fixed. For example, when using a small-power welder, a large-power generator needs to be turned on, and frequent starts and stops result in the situation of "using a big horse to pull a small cart", with low power generation efficiency. At the same time, the generator generates a lot of noise and emits a lot of exhaust gas, polluting the environment.

[0003] In addition, in some construction sites, there are situations where the load power is large in the early stage and small in the later stage. According to the traditional method, the transformer will be configured according to the maximum load, and the working load rate of the transformer is low in the later stage, resulting in insufficient utilization of transformer resources. Summary of the Invention

[0004] In view of the above defects, the present invention provides an extended-range energy storage system and a control method therefor, which can quickly and conveniently dispatch the power generated by a photovoltaic system and a generator according to the specific situation of the construction site, and flexibly perform range extension through an energy storage device to achieve dynamic control and improve the on-site power distribution capacity.

[0005] To achieve the object of the present invention, the following technologies are proposed: An extended-range energy storage system includes a generator set, a battery pack, an AC / DC charger, a high-voltage box, a DC bus, an AC / DC bidirectional converter, a grid-side AC bus, a load-side AC bus, an EMS (Energy Management System), a charging pile, and a photovoltaic inverter; The generator set supplies power to the AC / DC charger, and the AC / DC charger supplies power to the DC bus; The battery pack and the high-voltage box supply power to each other bidirectionally, and the high-voltage box also supplies power to the DC bus; The AC / DC bidirectional converter and the DC bus supply power to each other bidirectionally. The AC / DC bidirectional converter is also connected to the load-side AC bus, and supplies power to the charging piles through the load-side AC bus and charges from the photovoltaic inverter. The number of charging piles is several; The extended-range energy storage system is connected to the power grid and is connected to photovoltaic modules during use. The AC / DC bidirectional converter and the power grid supply power to each other bidirectionally through the grid-side AC bus. The photovoltaic modules supply power to the photovoltaic inverter. The power grid is connected to a gateway watt-hour meter and several preset general loads. The gateway watt-hour meter is connected to a transformer, and the load-side AC bus is connected to several preset important loads; The EMS is connected to a generator set, an AC / DC charger, a high-voltage box, an AC / DC bidirectional converter, a charging pile, a photovoltaic inverter, and a gateway watt-hour meter via communication lines.

[0006] Furthermore, the EMS includes a load classification module, an early warning value management module, a load data recording module, a electricity price determination module, an electricity price recording module, a parameter configuration module, and a communication module; The load classification module is used to set loads other than the charging pile as general loads or important loads; The early warning value management module is used to manually configure or automatically calculate the early warning values of the gateway watt-hour meter; The load data recording module is used to record the load power in real time; The electricity price determination module is used to determine the current electricity price; The electricity price recording module is used to record and save the local electricity price table; The parameter configuration module is used to configure parameters during energy storage and power dispatching control; The communication module is used to communicate with the power company.

[0007] An extended-range energy storage control method adopted includes the steps of: S100: Determine whether the power grid is out of power. If so, execute S200; if not, execute S300; S200: Execute the off-grid control strategy and then end; S300: Obtain the current electricity price through the electricity price determination module, including: S310: Determine whether the communication module can communicate with the power company. If so, execute S320; if not, execute S340; S320: Obtain the latest electricity price table; S330: Update the local electricity price table in the electricity price recording module and then execute S350; S340: Read the local electricity price table and then execute S350; S350: Determine whether the local electricity price table is manually corrected. If so, first execute S360 and then execute S370; if not, directly execute S370; S360: Receive the manual correction operation and update the local electricity price table; S370: Output the current electricity price; S400: Determine whether the current electricity price < a, where the value of a is pre-configured through the parameter configuration module. If so, execute S500; if not, execute S600; S500: Execute the valley period control strategy and then end; S600: Determine whether the current electricity price ≥ b, where the value of b is pre-configured by the parameter configuration module. If yes, execute S700; if no, execute S800; S700: Execute the peak period control strategy and then end; S800: Execute the normal period control strategy and then end.

[0008] Furthermore, S500 includes: S510: Determine whether to perform dynamic capacity expansion. If yes, execute S520; if no, execute S540; S520: The battery pack discharges to the DC bus through the high-voltage box at the power difference between the real-time load power and the warning value; S530: The AC / DC bidirectional converter converts the direct current on the DC bus into alternating current and then executes S560; S540: Determine whether the real-time load power = warning value. If yes, execute S560; if not, execute S550; S550: The AC / DC bidirectional converter converts the alternating current from the power grid into direct current and then charges the battery pack through the high-voltage box at the power difference between the warning value and the real-time load power, and then executes S560; S560: Wait for a predetermined interval; S570: Determine whether the end time of the valley period is reached. If yes, end; if no, return to S510.

[0009] Furthermore, S700 includes: S710: Obtain the current maximum output power of the PV inverter and the real-time load power; S720: Determine whether the current maximum output power of the PV inverter > real-time load power. If yes, execute S730; if no, execute S750; S730: The PV inverter outputs to the load according to the real-time load power; S740: Determine whether the battery pack is full. If yes, the PV inverter charges the remaining available power to the battery pack and then executes S780; if no, the PV inverter reduces the output power to be consistent with the real-time load power and then executes S780; S750: The PV inverter outputs to the load at the current maximum output power; S760: Obtain the current maximum output power of the battery pack and calculate the current required power = real-time load power - current maximum output power of the PV inverter; S770: Determine whether the current maximum output power of the battery pack > the current required power. If so, the battery pack outputs power to the load according to the current required power, and then execute S780. If not, the battery pack outputs power to the load at the current maximum output power, and the remaining power required by the load is output by the power grid, and then execute S780; S780: Wait for a predetermined interval; S790: Determine whether the peak period end time has been reached. If so, end. If not, return to S710.

[0010] Furthermore, S800 includes: S810: Obtain the current maximum output power and real-time load power of the PV inverter; S820: Determine whether the current maximum output power of the PV inverter > the real-time load power. If so, execute S830. If not, execute S850; S830: The PV inverter outputs power to the load according to the real-time load power; S840: Determine whether the battery pack is full. If so, the PV inverter charges the battery pack with the remaining available power, and then execute S870. If not, the PV inverter reduces the output power to be consistent with the real-time load power, and then execute S870; S850: Obtain the current maximum output power of the battery pack, and calculate the current required power = real-time load power - current maximum output power of the PV inverter; S860: The power grid outputs the current required power to the load, and then execute S870; S870: Wait for a predetermined interval; S880: Determine whether the normal period end time has been reached. If so, end. If not, return to S810.

[0011] Furthermore, S200 includes: S210: General loads stop working, and the battery pack supplies power to important loads and charging piles; S220: Determine whether the battery pack power > the critical power c, and the value of c is pre-configured by the parameter configuration module. If so, execute S230. If not, the generator set starts to charge the battery pack, and then execute S270; S230: Determine whether the PV inverter can currently output power. If so, execute S240. If not, execute S270; S240: Obtain the current maximum output power and real-time load power of the PV inverter; S250: Determine whether the sum of the output power of the battery pack and the current maximum output power of the PV inverter > the sum of the power required by the critical load and the charging pile. If so, the PV inverter also supplies power to the critical load and the charging pile, and then execute S260. If not, directly execute S260; S260: The PV inverter charges the battery pack with the remaining available power, and then execute S270; S270: Wait for a predetermined interval; S280: Determine whether the system is reconnected to the power grid. If so, end. If not, return to S220.

[0012] Furthermore, the process of determining whether to perform dynamic expansion in S510 includes: S511: Determine whether the warning value is set manually. If so, the warning value management module receives the warning value set manually, and then execute S517. If not, execute S512; S512: Read the historical load power within the most recent time range t from the load data recording module. The value of t is pre-configured by the parameter configuration module; S513: Calculate the average load rate of the time range covered by it through the rated power of the transformer and the obtained historical load power; S514: Determine whether the average load rate > 70%. If so, set the warning value = max(historical load power) * 0.85 + 2 * the real-time load standard deviation, and then execute S517. If not, execute S515; S515: Determine whether the average load rate ≤ 50%. If so, set the warning value = max(historical load power) * 0.95 + 2 * the real-time load standard deviation, and then execute S517. If not, execute S516; S516: Set the warning value = max(historical load power) * 0.9 + 2 * the real-time load standard deviation, and then execute S517; S517: Read the real-time load power; S518: Determine whether the real-time load power > the warning value. If so, perform dynamic expansion. If not, do not perform dynamic expansion.

[0013] The beneficial effects of this technical solution are as follows: 1. Solved the problems of energy endurance of traditional energy storage systems used in construction environments in the past, and the multi-energy and multi-time-space complementary and coordinated control problems of multi-energy including generator sets and PV cells for commercial power, and the function of continuous power use with high power.

[0014] 2. Compared with using only generators, it reduces fuel consumption and carbon emissions. After combining energy storage, the benefits of generator sets are maximized.

[0015] 3. Automatically and flexibly switch different control strategies under different environments. When the power grid is off-grid, give priority to supplying power to the loads in urgent need of electricity, and give full play to the advantages of the generator set to continuously supply power, avoiding frequent start-stop, with high power generation efficiency. At the same time, make full use of photovoltaic power generation, and flexibly determine whether the battery pack supplies power or charges according to the battery pack power and the power required by the load. When the power grid is on-grid, adopt different control strategies. During the valley period, mainly supply power to the load through the power grid, and the power can be stored in the battery pack for use in other periods; during the peak period, give priority to photovoltaic power supply, and then switch to charging the battery pack, discharging the battery pack, or supplying power by the power grid simultaneously according to the load situation; during the normal period, still give priority to photovoltaic power supply, and switch the charging and discharging of the battery pack, but advance the priority of power grid power supply.

[0016] 4. When performing power distribution and control, it can either manually or set the warning value according to the rated power of the transformer to avoid the risk of overloading the load, and can also adjust the power of each power supply device inside the system according to the current load situation, including the generator set, the battery pack, and the photovoltaic inverter, to avoid reverse current in the gateway watt-hour meter.

[0017] 5. It can not only achieve peak shaving and valley filling, but also achieve dynamic capacity expansion. It has both the long endurance characteristics of traditional gasoline and diesel generators and the instant supply characteristics of lithium battery energy storage, making the functional advantages of the two complementary. In addition to being applied to construction sites, it can also be applied to industrial and commercial energy storage, charging stations, outdoor large-scale irrigation, drilling and other occasions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Shows the circuit schematic diagram of the extended-range energy storage system in the embodiment of the present application when it is working.

[0019] Figure 2 Shows the partial circuit schematic diagram of the extended-range energy storage system with multiple AC / DC bidirectional converters in the embodiment of the present application.

[0020] Figure 3 Shows the EMS structure diagram of the embodiment of the present application.

[0021] Figure 4 Shows the overall step flow chart of the extended-range energy storage control method in the embodiment of the present application.

[0022] Figure 5 Shows the flow chart of the off-grid control strategy in the embodiment of the present application.

[0023] Figure 6 Shows the flow chart of obtaining the current electricity price in the embodiment of the present application.

[0024] Figure 7 Shows the flow chart of the valley period control strategy in the embodiment of the present application.

[0025] Figure 8 It shows the flowchart for the embodiment of the present application to determine whether to perform the dynamic capacity expansion process.

[0026] Figure 9 It shows the flowchart of the peak period control strategy for the embodiment of the present application.

[0027] Figure 10 It shows the flowchart of the normal period control strategy for the embodiment of the present application. Detailed implementation manners

[0028] The present application will be further described below in conjunction with the accompanying drawings and embodiments.

[0029] As Figures 1 to 3 shown, a range extender energy storage system includes a generator set, a battery pack, an AC / DC charger, a high-voltage box, a DC bus, an AC / DC bidirectional converter, a grid-side AC bus, a load-side AC bus, an EMS (Energy Management System), a charging pile, and a photovoltaic inverter.

[0030] The generator set supplies power to the AC / DC charger, and the AC / DC charger supplies power to the DC bus. In this embodiment, the generator set uses multiple diesel generators.

[0031] The battery pack and the high-voltage box supply power to each other bidirectionally, and the high-voltage box also supplies power to the DC bus.

[0032] The AC / DC bidirectional converter and the DC bus supply power to each other bidirectionally. The AC / DC bidirectional converter is also connected to the load-side AC bus, and supplies power to the charging pile and charges from the photovoltaic inverter through the load-side AC bus. The number of charging piles is several. In this embodiment, the AC / DC bidirectional converter has a built-in STS (Static Transfer Switch) function and can automatically switch when the power grid is powered off and on; The range extender energy storage system is connected to the power grid, and is connected with photovoltaic modules during use. The AC / DC bidirectional converter and the power grid supply power to each other bidirectionally through the grid-side AC bus. The photovoltaic modules supply power to the photovoltaic inverter. The power grid is connected with a gateway watt-hour meter and several preset general loads. The gateway watt-hour meter is connected with a transformer, and the load-side AC bus is connected with several preset important loads; The EMS is connected to the generator set, the AC / DC charger, the high-voltage box, the AC / DC bidirectional converter, the charging pile, the photovoltaic inverter, and the gateway watt-hour meter through communication lines.

[0033] As Figure 3 shown, the EMS includes a load classification module, an early warning value management module, a load data recording module, a power price determination module, a power price recording module, a parameter configuration module, and a communication module.

[0034] The load classification module is used to set the loads other than the charging piles as general loads or important loads. In this embodiment, the construction control system, the tunnel power consumption system, and the safety management system are manually configured as important loads, and the lighting and air conditioning are manually configured as general loads. The warning value management module is used to manually configure or automatically calculate the warning values of the gateway watt-hour meters. The load data recording module is used to record the load power in real time. The electricity price determination module is used to determine the current electricity price. The electricity price recording module is used to record and save the local electricity price table. The parameter configuration module is used to configure the parameters during energy storage and power dispatching control. The communication module is used to communicate with the power company.

[0035] As another implementation method, the loads can also be automatically classified. The loads with high power stability, that is, the power fluctuation < 5%, or the loads that need to be quickly restored after power failure are classified as important loads. The loads with low power stability and power fluctuation ≥ 5%, or the loads that allow short-term power failure are classified as general loads.

[0036] Preferably, as Figure 2 shown, the number of AC / DC bidirectional converters is multiple. There is a contactor between at least one AC / DC bidirectional converter and the load-side AC bus. The contactor is also connected to the EMS through a communication line. By setting multiple AC / DC bidirectional converters, the system can still operate normally when some of them fail.

[0037] As Figures 4 to 10 shown, an extended-range energy storage control method using the above extended-range energy storage system is operated according to the following steps: S100: Determine whether the power grid is powered off. If so, execute S200; if not, execute S300; S200: Execute the off-grid control strategy, and then end; Specifically, as Figure 5 shown, S200 includes: S210: The general loads stop working, and the battery pack supplies power to the important loads and the charging piles; S220: Determine whether the battery pack power > the critical power c, and the c value is pre-configured through the parameter configuration module. If so, execute S230; if not, start the generator set to charge the battery pack, and then execute S270; S230: Determine whether the PV inverter can output power currently. If so, execute S240; if not, execute S270; S240: Obtain the current maximum output power and real-time load power of the PV inverter; S250: Determine whether the sum of the output power of the battery pack and the current maximum output power of the PV inverter > the sum of the power required by the critical load and the charging pile. If so, the PV inverter also supplies power to the critical load and the charging pile, and then execute S260. If not, directly execute S260; S260: The PV inverter charges the battery pack with the remaining available power, and then execute S270; S270: Wait for a predetermined interval; S280: Determine whether the system is reconnected to the grid. If so, end. If not, return to S220; S300: Obtain the current electricity price through the electricity price determination module, as Figure 6 shown, including: S310: Determine whether the communication module can communicate with the power company. If so, execute S320. If not, execute S340; S320: Obtain the latest electricity price list; S330: Update the local electricity price list in the electricity price record module, and then execute S350; S340: Read the local electricity price list, and then execute S350; S350: Determine whether the local electricity price list is manually corrected. If so, first execute S360 and then execute S370. If not, directly execute S370; S360: Receive the manual correction operation and update the local electricity price list; S370: Output the current electricity price; S400: Determine whether the current electricity price < a, and the value of a is pre-configured through the parameter configuration module. If so, execute S500. If not, execute S600; S500: Execute the valley period control strategy, and then end; Specifically, as Figure 7 shown, S500 includes: S510: Determine whether to execute dynamic expansion. If so, execute S520. If not, execute S540; More specifically, as Figure 8 shown, the process of S510 for determining whether to execute dynamic expansion includes: S511: Determine whether to manually set the warning value. If so, the warning value management module receives the manually set warning value, and then execute S517. If not, execute S512; S512: Read the historical load power within the recent time t range from the load data record module, and the value of t is pre-configured through the parameter configuration module; S513: Calculate the average load rate of the time range covered by it through the rated power of the transformer and the obtained historical load power; S514: Determine whether the average load rate > 70%. If so, set the warning value = max(historical load power) * 0.85 + real-time load standard deviation * 2, and then execute S517. If not, execute S515; S515: Determine whether the average load rate ≤ 50%. If so, set the warning value = max(historical load power) * 0.95 + real-time load standard deviation * 2, and then execute S517. If not, execute S516; S516: Set the warning value = max(historical load power) * 0.9 + real-time load standard deviation * 2, and then execute S517; S517: Read the real-time load power; S518: Determine whether the real-time load power > warning value. If so, perform dynamic capacity expansion. If not, do not perform dynamic capacity expansion; S520: The battery pack discharges to the DC bus through the high-voltage box according to the power difference between the real-time load power and the warning value; S530: The AC / DC bidirectional converter converts the DC power on the DC bus into AC power, and then executes S560; S540: Determine whether the real-time load power = warning value. If so, execute S560. If not, execute S550; S550: The AC / DC bidirectional converter converts the AC power from the power grid into DC power, and then charges the battery pack through the high-voltage box according to the power difference between the warning value and the real-time load power, and then executes S560; S560: Wait for a predetermined interval; S570: Determine whether the end time of the valley period is reached. If so, end. If not, return to S510; S600: Determine whether the current electricity price ≥ b, and the b value is pre-configured through the parameter configuration module. If so, execute S700. If not, execute S800; S700: Execute the peak period control strategy, and then end; Specifically, as Figure 9 shown, S700 includes: S710: Obtain the current maximum output power and real-time load power of the photovoltaic inverter; S720: Determine whether the current maximum output power of the photovoltaic inverter > real-time load power. If so, execute S730. If not, execute S750; S730: The photovoltaic inverter outputs to the load according to the real-time load power; S740: Determine whether the battery pack is fully charged. If so, the PV inverter charges the battery pack with the remaining available power and then executes S780. If not, the PV inverter reduces its output power to match the real-time load power and then executes S780; S750: The PV inverter outputs to the load at the current maximum output power level; S760: Obtain the current maximum output power of the battery pack and calculate the current required power = real-time load power - current maximum output power of the PV inverter; S770: Determine whether the current maximum output power of the battery pack > the current required power. If so, the battery pack outputs to the load at the current required power and then executes S780. If not, the battery pack outputs to the load at the current maximum output power, and the remaining power required by the load is output by the power grid, and then S780 is executed; S780: Wait for a predetermined interval; S790: Determine whether the peak period end time has been reached. If so, end. If not, return to S710; S800: Execute the normal period control strategy and then end; Specifically, as Figure 10 shown, S800 includes: S810: Obtain the current maximum output power of the PV inverter and the real-time load power; S820: Determine whether the current maximum output power of the PV inverter > the real-time load power. If so, execute S830. If not, execute S850; S830: The PV inverter outputs to the load at the real-time load power; S840: Determine whether the battery pack is fully charged. If so, the PV inverter charges the battery pack with the remaining available power and then executes S870. If not, the PV inverter reduces its output power to match the real-time load power and then executes S870; S850: Obtain the current maximum output power of the battery pack and calculate the current required power = real-time load power - current maximum output power of the PV inverter; S860: The power grid outputs the current required power to the load and then executes S870; S870: Wait for a predetermined interval; S880: Determine whether the normal period end time has been reached. If so, end. If not, return to S810.

[0038] The above are only some embodiments listed in this application and are not used to limit this application.

Claims

1. An extended-range energy storage system, characterized in that, It includes a generator set, a battery pack, an AC / DC charger, a high-voltage box, a DC bus, an AC / DC bidirectional converter, a grid-side AC bus, a load-side AC bus, an EMS (Energy Management System), a charging pile, and a PV inverter; The generator set supplies power to the AC / DC charger, and the AC / DC charger supplies power to the DC bus; There is two-way power supply between the battery pack and the high-voltage box, and the high-voltage box also supplies power to the DC bus; There is two-way power supply between the AC / DC bidirectional converter and the DC bus. The AC / DC bidirectional converter is also connected to the load-side AC bus and supplies power to the charging piles and charges from the PV inverter through the load-side AC bus. The number of charging piles is several; The range-extended energy storage system is connected to the power grid and is connected with PV modules during use. There is two-way power supply between the AC / DC bidirectional converter and the power grid through the grid-side AC bus. The PV modules supply power to the PV inverter. The power grid is connected with a gateway watt-hour meter and several preset general loads. The gateway watt-hour meter is connected with a transformer, and the load-side AC bus is connected with several preset important loads; The EMS is connected to the generator set, the AC / DC charger, the high-voltage box, the AC / DC bidirectional converter, the charging piles, the PV inverter, and the gateway watt-hour meter through communication lines.

2. The range extender energy storage system according to claim 1, characterized in that The EMS includes a load classification module, an alarm value management module, a load data recording module, a power price determination module, a power price recording module, a parameter configuration module, and a communication module; The load classification module is used to set the loads other than the charging piles as general loads or important loads; The alarm value management module is used to manually configure or automatically calculate the alarm value of the gateway watt-hour meter; The load data recording module is used to record the load power in real time; The power price determination module is used to determine the current power price; The power price recording module is used to record and save the local power price table; The parameter configuration module is used to configure parameters during energy storage and power dispatching control; The communication module is used to communicate with the power company.

3. The range-extended energy storage system according to claim 1, wherein, The number of AC / DC bidirectional converters is multiple. At least one AC / DC bidirectional converter is provided with a contactor between it and the load-side AC bus, and the contactor is also connected to the EMS through a communication line.

4. A range-extended energy storage control method, characterized in that, Adopt the range-extended energy storage system described in claim 2, including the steps: S100: Judge whether the power grid is powered off. If so, execute S200. If not, execute S300; S200: Execute the off-grid control strategy, and then end; S300: Obtain the current power price through the power price determination module, including: S310: Judge whether the communication module can communicate with the power company. If so, execute S320. If not, execute S340; S320: Obtain the latest power price table; S330: Update the local power price table in the power price recording module, and then execute S350; S340: Read the local power price table, and then execute S350; S350: Judge whether the local power price table is manually corrected. If so, execute S360 first and then S370. If not, directly execute S370; S360: Receive the manual correction operation and update the local power price table; S370: Output the current power price; S400: Determine whether the current electricity price < a, where the value of a is pre-configured by the parameter configuration module. If so, execute S500; if not, execute S600; S500: Execute the valley period control strategy and then end; S600: Determine whether the current electricity price ≥ b, where the value of b is pre-configured by the parameter configuration module. If so, execute S700; if not, execute S800; S700: Execute the peak period control strategy and then end; S800: Execute the normal period control strategy and then end.

5. The range-extended energy storage control method according to claim 4, wherein S500 includes: S510: Determine whether to perform dynamic capacity expansion. If so, execute S520; if not, execute S540; S520: The battery pack discharges to the DC bus through the high-voltage box at the power difference between the real-time load power and the warning value; S530: The AC / DC bidirectional converter converts the direct current on the DC bus into alternating current and then executes S560; S540: Determine whether the real-time load power = the warning value. If so, execute S560; if not, execute S550; S550: The AC / DC bidirectional converter converts the alternating current from the grid into direct current and then charges the battery pack through the high-voltage box at the power difference between the warning value and the real-time load power, and then executes S560; S560: Wait for a predetermined interval; S570: Determine whether the end time of the valley period is reached. If so, end; if not, return to S510.

6. The range-extended energy storage control method according to claim 4, wherein S700 includes: S710: Obtain the current maximum output power of the photovoltaic inverter and the real-time load power; S720: Determine whether the current maximum output power of the photovoltaic inverter > the real-time load power. If so, execute S730; if not, execute S750; S730: The photovoltaic inverter outputs to the load according to the real-time load power; S740: Determine whether the battery pack is full. If so, the photovoltaic inverter charges the remaining available power to the battery pack and then executes S780; if not, the photovoltaic inverter reduces the output power to be consistent with the real-time load power and then executes S780; S750: The photovoltaic inverter outputs to the load at the current maximum output power; S760: Obtain the current maximum output power of the battery pack and calculate the current remaining required power = real-time load power - current maximum output power of the photovoltaic inverter; S770: Determine whether the current maximum output power of the battery pack > the current remaining required power. If so, the battery pack outputs to the load according to the current remaining required power and then executes S780; if not, the battery pack outputs to the load at the current maximum output power, and the remaining power required by the load is output by the grid, and then execute S780; S780: Wait for a predetermined interval; S790: Determine whether the end time of the peak period is reached. If so, end; if not, return to S710.

7. The range-extended energy storage control method according to claim 4, wherein S800 includes: S810: Obtain the current maximum output power of the photovoltaic inverter and the real-time load power; S820: Determine whether the current maximum output power of the photovoltaic inverter > the real-time load power. If so, execute S830; if not, execute S850; S830: The photovoltaic inverter outputs to the load according to the real-time load power; S840: Determine whether the battery pack is fully charged. If so, the PV inverter charges the battery pack with the remaining available power and then executes S870. If not, the PV inverter reduces the output power to be consistent with the real-time load power and then executes S870; S850: Obtain the current maximum output power of the battery pack and calculate the current required power = real-time load power - the current maximum output power of the PV inverter; S860: The power grid outputs the current required power to the load and then executes S870; S870: Wait for a predetermined interval; S880: Determine whether the end time of the normal period has been reached. If so, end. If not, return to S810.

8. The range extender energy storage control method according to claim 4, characterized in that S200 includes: S210: General loads stop working, and the battery pack supplies power to critical loads and charging piles; S220: Determine whether the battery pack power > the critical power c, and the c value is pre-configured by the parameter configuration module. If so, execute S230. If not, the generator set starts to charge the battery pack and then executes S270; S230: Determine whether the PV inverter can currently output power. If so, execute S240. If not, execute S270; S240: Obtain the current maximum output power of the PV inverter and the real-time load power; S250: Determine whether the sum of the battery pack output power and the current maximum output power of the PV inverter > the sum of the power required by critical loads and charging piles. If so, the PV inverter also supplies power to critical loads and charging piles and then executes S260. If not, directly execute S260; S260: The PV inverter charges the battery pack with the remaining available power and then executes S270; S270: Wait for a predetermined interval; S280: Determine whether the system is restored to connection with the power grid. If so, end. If not, return to S220.

9. The range-extended energy storage control method according to claim 5, wherein The process of determining whether to perform dynamic expansion in S510 includes: S511: Determine whether the warning value is manually set. If so, the warning value management module receives the manually set warning value and then executes S517. If not, execute S512; S512: Read the historical load power within the recent time t range from the load data recording module, and the t value is pre-configured by the parameter configuration module; S513: Calculate the average load rate of the time range covered by the transformer rated power and the obtained historical load power; S514: Determine whether the average load rate > 70%. If so, set the warning value = max(historical load power) * 0.85 + 2 * the real-time load standard deviation and then execute S517. If not, execute S515; S515: Determine whether the average load rate ≤ 50%. If so, set the warning value = max(historical load power) * 0.95 + 2 * the real-time load standard deviation and then execute S517. If not, execute S516; S516: Set the warning value = max(historical load power) * 0.9 + 2 * the real-time load standard deviation and then execute S517; S517: Read the real-time load power; S518: Determine whether the real-time load power > the warning value. If so, perform dynamic expansion. If not, do not perform dynamic expansion.

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