Station power supply system and power dispatching system

Abstract

The invention provides a station power supply system and a power dispatching system, and is applied to the technical field of power dispatching. The station power supply system comprises an alternating current-direct current converter, a shunt, a direct current busbar, a bidirectional direct current-direct current converter, a first battery, a second battery and an air switch. Wherein the alternating current input end of the alternating current-direct current converter is used for being connected with a power grid, the direct current output end of the alternating current-direct current converter is connected with the direct current busbar, the first battery is connected with the direct current busbar through the shunt, one end of the air switch is connected with the direct current busbar, and the other end of the air switch is used for being connected with a load. And one end of the bidirectional DC-DC converter is connected with the other end of the DC busbar or the air switch, and the other end of the bidirectional DC-DC converter is connected with the second battery. The bidirectional DC-DC converter is used for controlling charging and discharging of the second battery. Therefore, the charging and discharging statistics of the first battery is not influenced, and the battery management of the first battery can be prevented from being influenced.

Description

Technical Field

[0001] This application relates to the field of power dispatching technology, and in particular to a site power supply system and a power dispatching system. Background Technology

[0002] With the introduction of green energy and low-carbon goals, the demand for unstable new energy sources to access the grid is increasing. Traditional regulation equipment and capabilities alone cannot meet the grid regulation requirements and pose a significant risk to grid security. Therefore, more and more manufacturers are using virtual power plant (VPP) technology to find more adjustable load devices on the demand side of electricity consumption. By adjusting the adjustable loads according to the real-time demand of the grid, the regulation effect of traditional power plants can be achieved.

[0003] However, for site power supply systems equipped with DC-DC cascaded energy storage consisting of lithium batteries and bidirectional DC-DC converters, such as communication sites, energy storage power stations, and charging stations, which are under unified jurisdiction and have stable loads, it is often necessary to add energy storage batteries to participate in power auxiliary regulation services. However, existing DC-DC cascaded energy storage systems typically connect to the site power supply system through the battery ports of the existing energy storage batteries, causing the charging and discharging process of the DC-DC cascaded energy storage system to affect the battery management of the original energy storage batteries. Therefore, a solution is needed to address these issues. Summary of the Invention

[0004] This application provides a site power supply system and a power dispatching system to avoid affecting the battery management of the original energy storage batteries in the site power supply system during the charging and discharging process of DC tandem energy storage.

[0005] To achieve the above objectives, the embodiments of this application provide the following technical solutions.

[0006] In a first aspect, embodiments of this application provide a site power supply system, which includes an AC-DC converter, a shunt, a DC bus, a bidirectional DC-DC converter, a first battery, a second battery, and an air switch. The AC input terminal of the AC-DC converter is connected to the power grid, and the DC output terminal of the AC-DC converter is connected to the DC bus. The first battery is connected to the DC bus via the shunt. One end of the air switch is connected to the DC bus, and the other end of the air switch is used to connect to a load. One end of the bidirectional DC-DC converter is connected to either the DC bus or the other end of the air switch, and the other end of the bidirectional DC-DC converter is connected to the second battery. The bidirectional DC-DC converter is used to control the charging and discharging of the second battery.

[0007] In existing site power supply systems equipped with DC-DC battery storage, the bidirectional DC-DC converter and the existing energy storage batteries of the site power supply system are connected to the DC bus via a shunt through the same battery port. The shunt is used to perform charge and discharge statistics for both the DC-DC battery storage and the existing energy storage batteries of the site power supply system. Without DC-DC battery storage, when the shunt's statistics determine that the existing energy storage batteries of the site power supply system are relatively full, the DC output voltage of the AC-DC converter is a float charge voltage, which is a charging voltage set to compensate for battery self-discharge. Conversely, when the shunt's statistics determine that the existing energy storage batteries of the site power supply system are too low in charge or the charging current is too high, the DC output voltage of the AC-DC converter automatically switches from a float charge voltage to an equalizing charge voltage.

[0008] However, when the bidirectional DC-DC converter and the existing energy storage battery of the site power supply system are connected to the DC bus via the same battery port through a shunt, the shunt will also monitor the charging and discharging of the DC stacked energy storage. If the remaining charge or charging current of the DC stacked energy storage meets the condition for converting the float charge voltage to the equalization charge voltage, but the existing energy storage battery of the site power supply system still has sufficient charge, the AC-DC converter will still output the equalization charge voltage to the existing energy storage battery of the site power supply system, thus affecting the battery management of the existing energy storage battery of the site power supply system.

[0009] The site power supply system provided in this application embodiment only requires the shunt to perform charge and discharge statistics on the existing energy storage batteries in the site power supply system, while the DC stacked energy storage is connected to the DC bus as an adjustable load. Based on this, it is possible to prevent the charging and discharging of the second battery from affecting the charging and discharging of the first battery, thereby avoiding battery management problems for the first battery.

[0010] In one embodiment, the bidirectional DC-DC converter is used to control the discharge of the second battery when the power grid load is greater than or equal to a first power load threshold, and to control the charging of the second battery when the power grid load is less than or equal to a second power load threshold.

[0011] In this way, the bidirectional DC-DC converter can control the charging and discharging of the second battery according to the power load of the power grid, thereby making fuller use of the power of the power grid.

[0012] In one embodiment, the bidirectional DC-DC converter is further configured to: control the second battery to discharge when the grid electricity price is greater than or equal to a first electricity price threshold, and control the second battery to charge when the grid electricity price is less than or equal to a second electricity price threshold. The first electricity price threshold is greater than the second electricity price threshold.

[0013] In this way, the bidirectional DC-DC converter can control the discharge of the second battery when electricity prices are high, so as to supply power to the load through the second battery. Furthermore, the bidirectional DC-DC converter can control the charging of the second battery when electricity prices are low. Based on this, electricity costs can be reduced.

[0014] In one embodiment, the above-mentioned site power supply system further includes a control device, which is used to send an indication power to a bidirectional DC-DC converter, and the bidirectional DC-DC converter is also used to control the charging and discharging of the second battery according to the indication power sent by the control device.

[0015] In this way, the bidirectional DC-DC converter can control the charging and discharging of the second battery according to the power indication sent by the control device, so that the output power of the second battery is more in line with the power demand of the load.

[0016] In one embodiment, the indicated power includes the charging indicated power, which is the minimum power among the DC charging power of the AC-DC converter and the safe charging power calibrated by the second battery.

[0017] By charging the second battery according to the minimum power between the DC charging power of the AC-DC converter and the rated safe charging power of the second battery, the charging of the second battery can be made safer.

[0018] In one embodiment, the indicated power includes a discharge indicated power, which is determined based on the product of a calibrated discharge power threshold and the conversion efficiency of the AC-DC converter.

[0019] In this way, the discharge indication power of the second battery takes into account the effect of the AC-DC converter's conversion efficiency, thus effectively shortening the AC-DC converter's response time and improving the power response accuracy.

[0020] In one implementation, at the same depth of discharge, the second battery has a greater number of cycles than the first battery.

[0021] Because high-cycle batteries have a higher number of cycles than low-cycle batteries, they have a longer cycle life. Therefore, after multiple active charge-discharge cycles, high-cycle and low-cycle batteries have similar cycle counts, thus improving the consistency of energy storage batteries and reducing the aging rate of low-cycle batteries.

[0022] In one embodiment, during the discharge of the second battery, the voltage at the end of the bidirectional DC-DC converter connected to the DC bus is greater than the output voltage of the AC-DC converter.

[0023] In this way, the second battery can independently supply power to the load during the discharge process, and the AC-DC converter does not need to supply power to the load, thereby reducing the load on the power grid.

[0024] In one embodiment, one end of the bidirectional DC-DC converter is connected to the DC bus via a fuse. Therefore, when the current between the bidirectional DC-DC converter and the DC bus is too large, the DC current can be removed, preventing any impact on electrical safety.

[0025] Secondly, a power dispatching system is provided, comprising a power dispatching center and a site power supply system as described in any of the possible embodiments of the first aspect. The site power supply system is used to control the charging and discharging of a second battery according to dispatching signals sent by the power dispatching center.

[0026] Regarding the technical principles and beneficial effects of the second aspect mentioned above, please refer to the relevant description of the first aspect mentioned above, which will not be repeated here. Attached Figure Description

[0027] Figure 1 A schematic diagram of a power dispatching system provided in an embodiment of this application;

[0028] Figure 2 Another schematic diagram of the power dispatching system provided in the embodiments of this application;

[0029] Figure 3 A schematic diagram of the equalization charging voltage to float charging voltage conversion of the site power supply system provided in the embodiments of this application;

[0030] Figure 4 Another schematic diagram of the equalization charging voltage to float charging voltage conversion of the site power supply system provided in the embodiments of this application;

[0031] Figure 5 Another schematic diagram of the power dispatching system provided in the embodiments of this application;

[0032] Figure 6 This is another schematic diagram of a power dispatching system provided in an embodiment of this application. Detailed Implementation

[0033] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0034] It should be noted that the terms "in one embodiment" or "exemplary" in this application are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "in one embodiment" or "exemplary" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "in one embodiment" or "exemplary" is intended to present the relevant concepts in a specific manner.

[0035] The following is a brief introduction to the relevant terms that may be involved in this application.

[0036] Valley filling: Valley filling refers to the control process of increasing the power load when the power grid load is low, so as to ensure the economic efficiency and stability of the power grid operation.

[0037] Peak shaving: Peak shaving refers to the control process of reducing the power load when the power grid load is high, so as to ensure the economic efficiency and stability of the power grid operation.

[0038] Virtual powerplant (VPP): A virtual powerplant is a special type of power plant that participates in the electricity market and grid operation through a power coordination and management system. It uses advanced communication technologies and software systems to aggregate and coordinate distributed energy resources (DERs), such as distributed generators (DG), energy storage systems, controllable loads, and electric vehicles. For example, a virtual powerplant can generate "surplus" electricity by reducing the electricity demand of adjustable load terminals or devices. This involves finding more adjustable load devices on the demand side and adjusting these loads according to the real-time demand of the grid to achieve the effect of a physical power plant.

[0039] Cycle count: The cycle count represents the total number of all and partial discharge cycles throughout the battery's lifespan. Since battery capacity decreases with use, the cycle count can be used to represent the battery's cycle life. The number of cycles is related to the depth of discharge; at the same depth of discharge, a higher cycle count results in a longer cycle life, while a lower cycle count results in a shorter cycle life.

[0040] Float charge voltage: The float charge voltage is the voltage used to maintain a fully charged battery. It is typically low, only slightly greater than or equal to the battery's self-discharge rate. When the battery is not in use, the float charge voltage compensates for the battery's self-discharge by providing a small current, preventing the battery from losing power due to self-discharge and thus maintaining the battery's full charge. This voltage is usually maintained within a relatively stable range to prevent the battery from being overcharged or over-discharged.

[0041] Equalizing voltage: Equalizing voltage is a higher voltage applied before the battery is fully charged. Its purpose is to charge quickly so that the battery is fully charged as soon as possible.

[0042] DC-DC cascaded energy storage: DC-DC cascaded energy storage refers to adding a DC energy storage unit to the existing power supply system. This unit includes a bidirectional DC-DC converter and a storage battery. DC-DC cascaded energy storage can provide a stable DC power supply when the grid voltage fluctuates, ensuring the stable operation of the power supply system. In addition, DC-DC cascaded energy storage can also provide emergency power during grid faults, ensuring continuous power supply to the power supply system.

[0043] The present application will now be described in detail with reference to the accompanying drawings and embodiments:

[0044] In recent years, with the development of photovoltaic and wind power, the demand for unstable new energy sources to be connected to the grid has increased. Traditional regulation equipment and capacity alone cannot meet the dynamically changing power demand. Therefore, manufacturers use virtual power plant (VPP) technology to find more adjustable load equipment on the demand side of electricity consumption, and adjust the adjustable load according to the real-time demand of the grid to achieve the effect of an actual power plant.

[0045] like Figure 1 As shown, an existing power dispatching system 100 typically includes a power dispatching center 110, a power grid 120, multiple substation power supply systems 130, and loads 140. The power dispatching center 110 sends dispatching signals to each substation power supply system 130 to control the substation power supply systems 130 to convert the AC power from the power grid into DC power to supply power to the loads 140. Figure 2As shown. The site power supply system 130 includes a control device 131, an AC-DC converter 132, a DC bus 133, a bidirectional DC-DC converter 134, a shunt 135, a first battery 136, a second battery 137, and an air switch 138. The AC input terminal of the AC-DC converter 132 is connected to the power grid 120, and the DC output terminal of the AC-DC converter 132 is connected to the DC bus 133. One end of the first battery 136 and one end of the bidirectional DC-DC converter 134 are connected to one end of the shunt 135, the other end of the shunt 135 is connected to the DC bus 133, and the other end of the bidirectional DC-DC converter 134 is connected to the second battery 137. One end of the air switch 138 is connected to the DC bus 133, and the other end of the air switch 138 is used to connect to the load 140. The first battery 136 is used as a backup power source to supply power to the load when the power grid fails. The shunt 135 can perform charge and discharge statistics on the first battery 136 and the second battery 137. The control device 131 can control the bidirectional DC-DC converter 134 to perform charge and discharge control on the second battery 137 by voltage regulation according to the dispatch signal of the power dispatch center, so that the voltage output by the bidirectional DC-DC converter 134 is greater than or less than the voltage of the DC bus 133, thereby realizing the use and stop control of the power grid 120.

[0046] When a DC-DC battery is configured, if the shunt converter's statistics determine that the first battery 136 is nearly fully charged (e.g., reaching 90%), the voltage output from the DC output terminal of the AC-DC converter automatically switches from the equalization charge voltage to the float charge voltage. Conversely, if the shunt converter's statistics determine that the first battery 136's charge is too low or the charging current is too high, the voltage output from the DC output terminal of the AC-DC converter automatically switches from the float charge voltage to the equalization charge voltage.

[0047] Based on the same technical principle, when the site power supply system 130 is configured with DC supercharging, the shunt 135 can perform discharge statistics on the second battery 137. Specifically, when the remaining state of charge (SOC) of the second battery 137 is less than a set charge threshold, the output voltage of the AC-DC converter 132 will switch from a float charge voltage to an equalization charge voltage to maintain the battery's backup power capability. Furthermore, when the shunt 135 is tracking the battery's charging process, if the charging current of the second battery 137 exceeds a set charging current threshold, the output voltage of the AC-DC converter 132 will also switch from a float charge voltage to an equalization charge voltage to maintain the battery's backup power capability.

[0048] However, in actual power dispatching, because the original energy storage battery of the site power supply system 130 and the bidirectional DC-DC converter 134 are connected to the same battery interface of the DC bus 133 as another energy storage battery, the charging and discharging process of the second battery will also affect the charging and discharging statistics of the first battery 136, resulting in battery management problems in the site power supply system.

[0049] In one example, such as Figure 3 As shown, when the site power supply system 130 is configured with a DC-DC stack consisting of a bidirectional DC-DC converter 134 and a second battery 137, at time T1 during the discharge process of the second battery 137 controlled by the bidirectional DC-DC converter 134, the bidirectional DC-DC converter 134 increases the voltage at the end connected to the DC bus 133 to V1, making this voltage V1 greater than the voltage V0 output by the AC-DC converter 132 (at this time, V0 is the float charge voltage), thereby supplying power to the load 140 through the second battery 137. However, at time T2 after time T1, the remaining charge SOC1 of the second battery 137 is less than or equal to the charge threshold SOC. ref When (SOC1≤SOC) ref The AC-DC converter 132 will also automatically convert the output voltage V0 to the equalization charging voltage V2, resulting in the first battery 136 charging at the equalization charging voltage V2. After repeated cycles, this will affect the charge and discharge statistics of the first battery 136, leading to battery management problems for the first battery 136. In addition, after time T2, the second battery 137 is still discharging but cannot effectively carry the load.

[0050] In one example, such as Figure 4 As shown, at time T1 during the process of the bidirectional DC-DC converter 134 controlling the charging of the second battery 137, the bidirectional DC-DC converter 134 reduces the voltage V3 at one end connected to the DC bus 133, making this voltage V3 less than the voltage V0 output by the AC-DC converter 132. However, at time T2 after time T1, the charging current I1 of the second battery 137 is greater than the charging current threshold I. ref When (I1>I) ref The AC-DC converter 132 will also automatically convert the output voltage V0 to the equalization charging voltage V2, resulting in the charging voltage of the first battery 136 being the equalization charging voltage V2. After repeated cycles, this will also affect the charging and discharging statistics of the first battery 136, thus causing battery management problems of the first battery 136.

[0051] To solve the above problems, such as Figure 5As shown in the figure, this application embodiment provides a site power supply system 130, which includes an AC-DC converter 132, a DC bus 133, a bidirectional DC-DC converter 134, a shunt 135, a first battery 136, a second battery 137, and an air switch 138. The AC input terminal of the AC-DC converter 132 is connected to the power grid 120, and the DC output terminal of the AC-DC converter 132 is connected to the DC bus 133. The first battery 136 is connected to the DC bus 133 via the shunt 135. One end of the air switch 138 is connected to the DC bus 133, and the other end of the air switch 138 is used to connect to a load 140. One end of the bidirectional DC-DC converter 134 is connected to the other end of the air switch 138, and the other end of the bidirectional DC-DC converter 134 is connected to the second battery 137. The bidirectional DC-DC converter 134 is used to control the charging and discharging of the second battery 137. The bidirectional DC-DC converter 134 is used to increase the voltage at the end connected to the DC bus 133 during the discharge of the second battery 137, and to decrease the voltage at the end connected to the DC bus 133 during the charging of the second battery 137.

[0052] During the discharge of the second battery 137, the voltage at the end of the bidirectional DC-DC converter 134 connected to the DC bus 133 is greater than or equal to the voltage of the DC bus 133, allowing the second battery 137 to supply power to the load 140. During the charging of the second battery 137, the voltage at the end of the bidirectional DC-DC converter 134 connected to the DC bus 133 is less than the voltage of the DC bus 133, allowing the second battery 137 to be charged using the power output from the AC-DC converter 132.

[0053] In the above implementation, the first battery 136 is directly connected to the DC bus 133 via a shunt 135, which is used to perform charge and discharge statistics on the first battery 136. The second battery 137 is connected to the DC bus 133 via a bidirectional DC-DC converter 134. Therefore, when the bidirectional DC-DC converter 134 controls the charging and discharging of the second battery 137, it can be connected to the DC bus 133 as an adjustable load without affecting the charge and discharge statistics of the first battery 136, thus avoiding battery management issues for the first battery 136.

[0054] In the embodiments of this application, the number of first batteries 136 and second batteries 137 in the site power supply system 130 is not specifically limited. For example, the site power supply system 130 includes multiple first batteries 136 and one second battery 137, or the site power supply system 130 includes one first battery 136 and multiple second batteries 137, or the site power supply system 130 includes multiple first batteries 136 and multiple second batteries 137.

[0055] Based on the site power supply system 130 provided in this application embodiment, when the power grid 120 is online, the power grid 120 directly supplies power to the load through the AC-DC converter 132, without needing to supply power through the second battery 137 or the first battery 136. However, during the operation of the power grid 120, the power load of the power grid 120 will change. When the power load of the power grid 120 is low, there is a large margin in the power grid, resulting in wasted power. When the power load of the power grid 120 is high, the output power of the AC-DC converter 132 will be unstable, making it impossible for the output power of the AC-DC converter 132 to fully meet the power demand of the load 140.

[0056] In one embodiment, the bidirectional DC-DC converter 134 can control the charging and discharging of the second battery 137 according to the electrical load of the power grid 120. Specifically, the bidirectional DC-DC converter 134 can control the second battery 137 to discharge when the electrical load of the power grid 120 is greater than or equal to a first electrical load threshold, and control the second battery 137 to charge when the electrical load of the power grid 120 is less than or equal to a second electrical load threshold. The second electrical load threshold is less than the first electrical load threshold.

[0057] For example, the first power load threshold is selectively set to 90% of the maximum grid load, and the second power load threshold is selectively set to 60% of the maximum grid load. The bidirectional DC-DC converter 134 can control the second battery 137 to discharge when the power load of the grid 120 exceeds 90% of the maximum grid load, thereby supplying power to the load 140 through the second battery 137. Furthermore, the bidirectional DC-DC converter 134 can control the second battery 137 to charge when the power load of the grid 120 is less than 60% of the maximum grid load.

[0058] In this way, the bidirectional DC-DC converter 134 can control the charging and discharging of the second battery 137 according to the power load of the power grid 120 by peak shaving and valley filling. Based on this, it can reduce the power load of the power grid 120 when the power load is too large, and can also make full use of the power of the power grid 120.

[0059] It should be understood that the above-mentioned setting method of the first power load threshold and the second power load threshold is only an example provided by the embodiments of this application, and the specific values ​​of the first power load threshold and the second power load threshold can be adjusted according to actual needs.

[0060] In one embodiment, considering that the electricity price of the power grid typically varies according to seasons, electricity consumption periods, etc., the bidirectional DC-DC converter 134 can also control the second battery 137 to discharge when the electricity price of the power grid 120 is greater than or equal to a first electricity price threshold, and control the second battery 137 to charge when the electricity price of the power grid 120 is less than or equal to a second electricity price threshold. The first electricity price threshold is greater than the second electricity price threshold.

[0061] For example, the first electricity price threshold is the electricity price corresponding to the peak electricity consumption period. The second electricity price threshold is the electricity price during the off-peak electricity consumption period. The bidirectional DC-DC converter 132 controls the second battery 137 to discharge when the electricity price of the grid 120 is greater than or equal to the electricity price corresponding to the peak electricity consumption period, and controls the second battery 137 to charge when the electricity price of the grid 120 is less than or equal to the electricity price during the off-peak electricity consumption period.

[0062] In this way, the bidirectional DC-DC converter 132 can control the charging and discharging of the second battery 137 according to the real-time electricity price of the grid 120, thereby reducing electricity costs while maintaining the backup power capacity of the second battery 137.

[0063] It should be understood that the aforementioned first and second electricity price thresholds can also be adaptively adjusted based on factors that affect electricity prices, such as electricity consumption and the nature of electricity consumption (e.g., commercial and residential electricity consumption).

[0064] In one embodiment, the second battery 137 is an auxiliary power supply battery, such as a lithium battery, and the first battery 136 is a backup power battery, such as a lead-acid battery. Specifically, at the same depth of discharge, the second battery 137 has a greater cycle life than the first battery 136.

[0065] Based on this, the cycle life of the second battery 137 is greater than that of the first battery 136, so that the number of cycles of the second battery 137 after multiple active charge and discharge cycles is similar to that of the first battery 136, thereby improving the consistency between the second battery 137 and the first battery 136 and reducing the aging rate of the first battery 136.

[0066] During the process of the bidirectional DC-DC converter 134 controlling the discharge of the second battery 137 to supply power to the load, if the voltage at the end of the bidirectional DC-DC converter 134 connected to the DC bus 133 is equal to the output voltage of the AC-DC converter 132, the AC-DC converter 132 still needs to carry part of the load, thereby increasing the power load of the power grid 120.

[0067] In one embodiment, based on the site power supply system 130 provided in this application embodiment, when the bidirectional DC-DC converter 134 controls the second battery 137 to discharge, the voltage at one end of the bidirectional DC-DC converter 134 connected to the DC bus 133 is greater than the output voltage of the AC-DC converter 132.

[0068] In this manner, when the voltage at the end of the bidirectional DC-DC converter 134 connected to the DC bus 133 is greater than the output voltage of the AC-DC converter 132, the output voltage of the AC-DC converter 132 cannot effectively carry the load. Based on this, the power load on the grid can be reduced.

[0069] In one embodiment, the AC-DC converter 132 can automatically convert the output voltage from the float charge voltage of the first battery 136 to the equalization charge voltage when the remaining charge of the first battery 136 is less than or equal to a charge threshold. Alternatively, the AC-DC converter 132 can automatically convert the output voltage from the float charge voltage of the first battery 136 to the equalization charge voltage when the charging current of the first battery 136 is greater than a charging current threshold.

[0070] In one embodiment, the preset power level is selectively set to 30% of the total power of the first battery 136. Specifically, when the remaining power of the first battery 136 is less than or equal to 30% of its total power, the AC-DC converter 132 converts the output voltage from the float charge voltage of the first battery 136 to the equalization charge voltage.

[0071] In one embodiment, the preset charging current is selectively set to 0.1C. Here, C represents the rated capacity of the first battery. When the charging current of the first battery 136 is greater than or equal to 0.1C, the AC-DC converter 132 converts the output voltage from the float charge voltage of the first battery 136 to the equalization charge voltage.

[0072] It should be understood that the above-mentioned preset power and preset charging current are an exemplary implementation provided by the embodiments of this application. In specific implementation, the above-mentioned preset power and preset charging current can also be adjusted according to the actual equalization charging logic of the first battery 136.

[0073] In one embodiment, it is still as follows Figure 5 As shown, the site power supply system 130 also includes a control device 131. The control device 131 is communicatively connected to the power dispatch center 110. The control device 131 is used to send an indicated power to the bidirectional DC-DC converter 134. The bidirectional DC-DC converter 134 is used to control the charging and discharging of the second battery 137 according to the indicated power.

[0074] In one embodiment, the control device 131 is further configured to communicate with a power dispatch center. The control device 131 is also capable of sending an indicated power to the bidirectional DC-DC converter 134 in response to a dispatch signal sent by the power dispatch center. The bidirectional DC-DC converter 134 is capable of controlling the charging and discharging power of the second battery 137 according to the indicated power. The indicated power includes both a discharging indicated power and a charging indicated power.

[0075] In one embodiment, the control device 131 can determine the discharge power of the bidirectional DC-DC converter 134 when controlling the second battery 137 to discharge based on the product of a calibrated discharge power threshold and the conversion efficiency of the AC-DC converter. The calibrated discharge power threshold is determined based on the power deficit of the grid 120 and the maximum discharge power of the second battery 137. For example, if the power deficit of the grid 120 is 5 kW, the maximum discharge power of the second battery 137 is 6 kW, and the conversion efficiency of the AC-DC converter is 90%, then the calibrated discharge power threshold is 5 kW, and the discharge power of the bidirectional DC-DC converter 134 when controlling the second battery 137 to discharge is 4.5 kW. This is equivalent to drawing 5 kW less power from the grid on the AC side, thus completing power dispatch.

[0076] In one embodiment, when the maximum discharge power of the second battery 137 is less than the power deficit of the power grid 120, the discharge power of the second battery 137 during discharge is the maximum discharge power of the second battery 137.

[0077] In one embodiment, the control device 131 determines the charging indication power of the second battery 137 based on the minimum power between the DC charging power of the AC-DC converter 132 and the calibrated safe charging power of the second battery 137. Then, the bidirectional DC-DC converter 134 controls the charging of the second battery 137 according to the charging indication power, thereby ensuring that the charging process of the second battery 137 does not affect system safety.

[0078] The DC charging power of the AC-DC converter 132 refers to the power that the AC-DC converter 132 can output under the system architecture. The magnitude of the above charging power needs to meet the requirements of the charging indication power, but cannot exceed the remaining output power of the AC-DC converter 132 and the safe charging power of the second battery 137, so as to ensure that the power dispatching process will not affect the system safety.

[0079] For example, if the DC charging power of the AC-DC converter 132 is 6 kW and the rated safe charging power of the second battery 137 is 5 kW, then the charging indication power is 5 kW. If the DC charging power of the AC-DC converter 132 is 4 kW and the rated safe charging power of the second battery 137 is 5 kW, then the charging indication power is 4 kW.

[0080] Furthermore, when the charging voltage of the second battery 137 is less than the output voltage of the AC-DC converter 132, the AC-DC converter 132 can supply power to the load and charge the first battery 136 and the second battery 137. In this case, the control device 131 can determine the DC charging power of the AC-DC converter 132 based on the maximum charging power of the second battery 137 and the fixed power demand of the load. It is understood that the magnitude of the DC charging power of the AC-DC converter 132 represents the adjustable power that the site power supply system 130 can increase in response to grid absorption under the power dispatching system architecture.

[0081] In one embodiment, such as Figure 6 As shown, the site power supply system 130 provided in this embodiment includes an AC-DC converter 132, a DC bus 133, a bidirectional DC-DC converter 134, a shunt 135, a first battery 136, a second battery 137, and an air switch 138. The AC input terminal of the AC-DC converter 132 is connected to the power grid 120, and the DC output terminal of the AC-DC converter 132 is connected to the DC bus 133. The first battery 136 is connected to the DC bus 133 via the shunt 135. One end of the air switch 138 is connected to the DC bus 133, and the other end of the air switch 138 is used to connect to a load 140. One end of the bidirectional DC-DC converter 134 is connected to the DC bus 133, and the other end of the bidirectional DC-DC converter 134 is connected to the second battery 137. The bidirectional DC-DC converter 134 is used to control the charging and discharging of the second battery 137. The bidirectional DC-DC converter 134 is used to increase the voltage at the end connected to the DC bus 133 during the discharge of the second battery 137, and to decrease the voltage at the end connected to the DC bus 133 during the charging of the second battery 137.

[0082] pass Figure 6 In the site power supply system 130, when one end of the bidirectional DC-DC converter 134 is connected to the DC bus 133, the bidirectional DC-DC converter 134 can also refer to Figure 5 The technical principles for controlling the charging and discharging of the second battery 137 described in the corresponding part are not repeated here in the embodiments of this application.

[0083] In one embodiment, it is still as follows Figure 6 As shown, one end of the bidirectional DC-DC converter 134 is connected to the DC bus 133 via a fuse 139. The fuse 139 can promptly remove the DC cascade formed by the bidirectional DC-DC converter 134 and the second battery 137 when the current between the DC bus 133 and the bidirectional DC-DC converter 134 is too large, thereby ensuring the power supply safety of the site power supply system 130.

[0084] In summary, this application provides a site power supply system, a control method for the site power supply system, and a power dispatching system, applicable to the field of power dispatching technology. The site power supply system includes an AC-DC converter, a shunt, a DC bus, a bidirectional DC-DC converter, a first battery, a second battery, and an air switch. The AC input of the AC-DC converter is connected to the power grid, and the DC output is connected to the DC bus. The first battery is connected to the DC bus via the shunt. One end of the air switch is connected to the DC bus, and the other end is connected to a load. One end of the bidirectional DC-DC converter is connected to either the DC bus or the other end of the air switch, and the other end is connected to the second battery. The bidirectional DC-DC converter is used to control the charging and discharging of the second battery. Through this method, the DC storage stack composed of the bidirectional DC-DC converter and the second battery can be directly charged and discharged as an adjustable load through the DC bus or the air switch, without affecting the charging and discharging statistics of the first battery, thus avoiding battery management problems for the first battery.

[0085] In the several embodiments provided in this application, each functional module can be integrated into one device, or each module can exist physically separately, or two or more modules can be integrated into one device.

[0086] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A site power supply system, characterized in that, The site power supply system includes an AC-DC converter, a shunt, a DC bus, a bidirectional DC-DC converter, a first battery, a second battery, and an air switch; The AC input terminal of the AC-DC converter is used to connect to the power grid, the DC output terminal of the AC-DC converter is connected to the DC bus, the first battery is connected to the DC bus through the shunt, one end of the air switch is connected to the DC bus, and the other end of the air switch is used to connect to the load. One end of the bidirectional DC-DC converter is connected to the DC bus or the other end of the air switch, and the other end of the bidirectional DC-DC converter is connected to the second battery; The bidirectional DC-DC converter is used to control the charging and discharging of the second battery.

2. The site power supply system according to claim 1, characterized in that, The bidirectional DC-DC converter is used for: When the power load of the power grid is greater than or equal to a first power load threshold, the second battery is controlled to discharge; and when the power load of the power grid is less than or equal to a second power load threshold, the second battery is controlled to charge. The second power load threshold is less than the first power load threshold.

3. The site power supply system according to claim 1 or 2, characterized in that, The bidirectional DC-DC converter is also used for: When the electricity price of the power grid is greater than or equal to a first electricity price threshold, the second battery is controlled to discharge; and when the electricity price of the power grid is less than or equal to a second electricity price threshold, the second battery is controlled to charge. The first electricity price threshold is greater than the second electricity price threshold.

4. The site power supply system according to any one of claims 1-3, characterized in that, The site power supply system further includes: a control device, the control device being configured to send an indication power to the bidirectional DC-DC converter, the bidirectional DC-DC converter also being configured to: The second battery is controlled to charge and discharge according to the power indication sent by the control device.

5. The site power supply system according to claim 4, characterized in that, The indicated power includes the charging indicated power, which is the minimum power among the DC charging power of the AC-DC converter and the safe charging power calibrated by the second battery.

6. The site power supply system according to claim 4 or 5, characterized in that, The indicated power includes the discharge indicated power, which is determined based on the product of a calibrated discharge power threshold and the conversion efficiency of the AC-DC converter.

7. The site power supply system according to any one of claims 1-6, characterized in that, At the same depth of discharge, the second battery has a greater number of cycles than the first battery.

8. The site power supply system according to any one of claims 1-5, characterized in that, During the discharge process of the second battery, the voltage at the end of the bidirectional DC-DC converter connected to the DC bus is greater than the output voltage of the AC-DC converter.

9. The site power supply system according to any one of claims 1-8, characterized in that, One end of the bidirectional DC-DC converter is connected to the DC bus via a fuse.

10. A power dispatching system, characterized in that, The power dispatching system includes a power dispatching center and a site power supply system as described in any one of claims 1-9, wherein the site power supply system is used to control the charging and discharging of the second battery according to the dispatching signal sent by the power dispatching center.

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