WO2025236262A1 - Electric power system, energy storage system, and operation method - Google Patents

Abstract

An electric power system, an energy storage system, and an operation method. The energy storage system is coupled to a mains supply of the electric power system by means of a power supply bus, and the electric power system comprises a plurality of uninterruptible power supplies coupled to the power supply bus. The energy storage system comprises a power adjustment device, a battery module, a direct-current conversion device, and a first controller; and the direct-current conversion device is correspondingly coupled to a plurality of direct-current buses of the uninterruptible power supplies by means of a plurality of external lines. The first controller controls the power adjustment device to convert alternating-current power on the power supply bus into first direct-current power so as to charge the battery module. When the mains supply fails, the first controller controls the direct-current conversion device to convert the first direct-current power into second direct-current power, and supply the second direct-current power to the direct-current buses respectively by means of the external lines.

Description

Power systems, energy storage systems and their operation methods Technical Field

This disclosure relates to a power system, an energy storage system, and a method of operating the same, particularly a power system, an energy storage system, and a method of operating the same, which share a battery.

Background Technology

Global energy demand continues to grow. With population growth and economic development, the increased energy demand places higher demands on energy supply systems. Energy storage systems can store excess electricity from renewable energy sources and release it when needed. For users, energy storage is also used to regulate and control electricity consumption to overcome voltage drop and provide savings on electricity costs through power regulation and control strategies.

When the client's mains power is interrupted or abnormal, the energy storage system can effectively provide the power required by the grid to maintain power supply stability. Meanwhile, critical loads in the system are usually equipped with uninterruptible power supplies (UPS) to avoid power supply disruptions to equipment and loads caused by sudden grid conditions. Specifically, the current user power system architecture is shown in Figure 1. The energy storage system 300 is connected to the power supply bus AC_Bus to regulate the charging and discharging of battery module 2 to stabilize the AC power Pac on the power supply bus AC_Bus. On the other hand, the uninterruptible power supply UPS_S includes a cabinet 400 and multiple uninterruptible power devices UPS_1 to UPS_n. The cabinet 400 includes accommodating spaces C1 to Cn for each of the UPS_1 to UPS_n devices. Furthermore, the accommodating spaces C1 to Cn also include battery cabinets Cb_1 to Cb_n, and the battery cabinets Cb_1 to Cb_n respectively accommodate the batteries B1 to Bn of the UPS_1 to UPS_n devices.

When the mains power is operating normally, the user's critical loads Lc_1 to Lc_n are connected by the uninterruptible power supply (UPS_S). If the mains power 200 is interrupted or malfunctions, the critical loads Lc_1 to Lc_n will be powered by the converted power from batteries B1 to Bn of the UPS_1 to UPS_n. Furthermore, if the mains power 200 is interrupted or malfunctions, the energy storage system 300 provides AC power Pac to the power supply bus AC_Bus through the discharge of battery module 2 to power the non-critical load Ln.

In the current architecture shown in Figure 1, the overall customer power consumption involves two independently operating battery systems (i.e., batteries B1-Bn and battery module 2), located in the energy storage system 300 and the uninterruptible power supply (UPS_S) respectively. These two systems maintain power on different paths. The energy storage system 300 primarily adjusts and maintains the AC power Pac of the power supply bus AC_Bus through the charging and discharging of battery module 2. Conversely, the uninterruptible power supply... The UPS_S power system primarily adjusts and maintains the output power Po_1 to Po_n to critical loads Lc_1 to Lc_n by charging and discharging batteries B1 to Bn. However, the battery system (i.e., batteries B1 to Bn and battery module 2) is expensive and requires regular replacement, resulting in relatively high equipment and maintenance costs for the current system.

Therefore, how to design a power system, an energy storage system, and its operation method so that the energy storage system and the uninterruptible power supply system can share battery modules as a shared support resource is a major research topic that the inventors of this case intend to study.

It is worth mentioning that the background content described in Figure 1 is generally used to indicate the prior art disclosed herein and its context. The inventor's work described in the background portion of Figure 1 should not be expressed or implied as refuting the prior art disclosed herein, nor is it suitable as prior art at the time of application.

Summary of the Invention

To address the aforementioned problems, this disclosure provides an energy storage system to overcome the limitations of existing technologies. Therefore, the energy storage system disclosed herein is coupled to the mains power of a power system via a power supply bus, and the power system includes multiple uninterruptible power supplies (UPS) coupled to the power supply bus. The energy storage system includes a power regulating device, a battery module, a DC-DC converter, and a first controller, with the power regulating device coupled to the power supply bus and the battery module. One end of the DC-DC converter is coupled to the battery module, and the other end is connected to multiple DC buses of the UPS via multiple external lines. The first controller is coupled to the power regulating device and the DC-DC converter, and when the mains power is operating normally, the first controller controls the power regulating device to convert the AC power on the power supply bus into first DC power to charge the battery module. When the mains power fails, the first controller controls the DC-DC converter to convert the first DC power into second DC power, and provides the second DC power to the DC buses via external lines.

To address the aforementioned problems, this disclosure provides a power system to overcome the limitations of existing technologies. Therefore, the power system disclosed herein is coupled to mains power and includes a power supply bus, multiple uninterruptible power supplies (UPS) devices, and an energy storage system. The power supply bus receives AC power from the mains. The UPS devices are coupled to the power supply bus and can be coupled to multiple critical loads to correspondingly convert AC power into multiple output powers to supply power to the critical loads. The energy storage system is coupled to the power supply bus and the UPS devices, and includes a power conditioning device, a battery module, a DC-DC converter, and a first controller. The power conditioning device is coupled to the power supply bus, and the battery module is coupled to the power conditioning device. One end of the DC-DC converter is coupled to the battery module, and the other end is coupled to multiple DC buses of the UPS via multiple external lines. The first controller… The controller is coupled to the power regulation device and the DC-DC converter. When the mains power is operating normally, the first controller controls the power regulation device to convert AC power into DC power to charge the battery module. When the mains power fails, the first controller controls the DC-DC converter to convert the DC power into DC power and provides the DC power to the DC bus through external lines. The uninterruptible power supply provides multiple output powers according to the corresponding DC power.

To address the aforementioned problems, this disclosure provides an operating method for an energy storage system to overcome the limitations of existing technologies. Therefore, the energy storage system disclosed herein is coupled to the mains power of a power system via a power supply bus, and the power system includes multiple uninterruptible power supplies (UPS) coupled to the power supply bus. The operating method of the energy storage system includes the following steps: (a) detecting whether the mains power has failed. (b) controlling a DC-DC converter to convert the first DC power provided by the battery module into a second DC power based on the mains power failure, so as to provide the second DC power to the DC bus of the UPS via multiple external lines. (c) determining whether the mains power failure is due to a mains power interruption or a mains power anomaly. (d) controlling a power regulating device to convert the first DC power into AC power based on the mains power interruption, so as to provide the AC power to the power supply bus. (e) controlling a power regulating device to convert the first DC power into a first compensation power based on the mains power anomaly, so as to provide the first compensation power to the power supply bus to compensate for the AC power provided by the mains power.

The main purpose and effect of this disclosure is to use the shared battery module as a shared resource to support both the energy storage system and the uninterruptible power supply (UPS). This is achieved by coupling one end of a DC-DC converter to the battery module and the other end to an external UPS via an external line. In this way, the first controller can fully utilize the DC power supplied to the battery module, and the continuous switching of the UPS effectively improves the efficiency of the energy storage system and significantly reduces electricity costs, thereby reducing equipment problems and battery maintenance costs.

To gain a deeper understanding of the techniques, means, and effects employed in achieving the intended purpose of this disclosure, please refer to the following detailed description and accompanying drawings. It is believed that the purpose, features, and characteristics of this disclosure can be understood in a thorough and specific manner from these drawings. However, the drawings are provided for reference and illustration only and are not intended to limit this disclosure.

Attached Figure Description

Figure 1 is a circuit block diagram of a power system in the prior art;

Figure 2 is a circuit block diagram of the power system disclosed herein;

Figure 3A is a detailed circuit block diagram of the first embodiment of the power system disclosed herein;

Figure 3B is a detailed circuit block diagram of the second embodiment of the power system disclosed herein;

Figure 4 is a schematic diagram of the external wiring of this disclosure; and

Figure 5 is a flowchart of the operation method of the energy storage system disclosed herein.

Explanation of icon numbers
100: Power System
AC_Bus: Power supply bus
Br: Circuit breaker
UPS_S: Uninterruptible Power Supply System
UPS_1～UPS_n: Uninterruptible power supply
DC_Bus_1～DC_Bus_n: DC bus
B1～Bn: Battery
20: AC/DC converter
22: DC/AC converter
24: Second controller
SW: Bypass switch
200: Mains power
300: Energy Storage System
1: Power regulation device
2: Battery Module
26: Battery
3: DC-DC converter
4: First Controller
Te_1～Te_n: External lines
L1: Power line
L2: Communication line
D1～Dn: Unidirectional conduction components
400: Server Rack
C1～Cn: Compartment space
Cb_1～Cb_n: Battery cabinet
Pac: Alternating Current
Lc_1～Lc_n: Critical load
Po_1～Po_n: Output power
Pdc1: First DC power
Pdc2: Second DC power supply
Pc1: First Compensation Power
Pc2: Second Compensation Power

Detailed Implementation

The technical content and detailed description of this disclosure are explained below in conjunction with the accompanying drawings:

Please refer to Figure 2 for a circuit block diagram of the power system disclosed herein. Power system 100 is coupled to mains power 200 to receive AC power Pac supplied by mains power 200. Power system 100 includes a power supply bus AC_Bus, multiple uninterruptible power supplies (UPS_1 to UPS_n), and an energy storage system 300. The power supply bus AC_Bus receives AC power Pac from mains power 200. UPS_1 to UPS_n are coupled to the power supply bus AC_Bus, and UPS_1 to UPS_n can be coupled to multiple critical loads Lc_1 to Lc_n to correspondingly convert the AC power Pac into multiple output powers Po_1 to Po_n to power the critical loads Lc_1 to Lc_n. That is, the number of UPS_1 to UPS_n can be greater than or equal to the number of critical loads Lc_1 to Lc_n. Furthermore, the term "correspondence" can be interpreted as follows: when the output terminals of uninterruptible power supplies (UPS_1 to UPS_n) are coupled to critical loads Lc_1 to Lc_n (assuming UPS_1), UPS_1 with a critical load Lc_1 can convert AC power Pac into output power Po_1 to provide output power Po_1 to the critical load Lc_1. Under this condition, if none of the UPS_n-1 to UPS_n are coupled to critical loads Lc_n-1 to Lc_n, then UPS_n-1 to UPS_n do not need to provide output power Po_n-1 to Po_n, and so on.

The energy storage system 300 is coupled to the power supply bus AC_Bus and each uninterruptible power supply (UPS_1~UPS_n), and the energy storage system 300 includes a power conditioning system 1, a battery module 2, a DC-DC converter 3, and a first controller 4. The power conditioning system 1 (PCS) is coupled to the power supply bus AC_Bus, and the battery module 2 is coupled to the power conditioning system 1. One end of the DC-DC converter 3 is coupled to the battery module 2 and the power conditioning system 4. The other end of the DC-DC converter 3 is coupled to multiple DC buses DC_Bus_1 to DC_Bus_n of the uninterruptible power supplies UPS_1 to UPS_n via multiple external lines Te_1 to Te_n. That is, each uninterruptible power supply UPS_1 to UPS_n has a DC bus DC_Bus_1 to DC_Bus_n, and the DC-DC converter 3 is coupled to each DC bus DC_Bus_1 to DC_Bus_n via each external line Te_1 to Te_n.

The first controller 4 is coupled to the power regulating device 1 and the DC-DC converter 3 to control the power conversion of the battery module 2. Specifically, the first controller 4 can control the power regulating device 1 to convert AC power Pac into a first DC power Pdc1, so as to charge the battery module 2 through the first DC power Pdc1. The first controller 4 can also control the DC-DC converter 3 to convert the first DC power Pdc1 into a second DC power Pdc2, so as to provide the second DC power Pdc2 to each DC bus DC_Bus_1 to DC_Bus_n through external lines Te_1 to Te_n. It is worth mentioning that, in one embodiment, the term "electricity" mentioned in this disclosure can refer to voltage, current, or power, and unless otherwise specified, it mainly refers to power. The relationship between voltage and current can be inferred from the term "electricity" and basic electrical principles, and will not be elaborated here.

Furthermore, the uninterruptible power supplies (UPS_1 to UPS_n) can be considered as a single uninterruptible power system (UPS_S). Generally, the UPS_S can accommodate the UPS_1 to UPS_n through the storage spaces C1 to Cn in the cabinet 400. However, in the prior art, each storage space C1 to Cn must also include battery cabinets Cb_1 to Cb_n to accommodate batteries B1 to Bn (as shown in Figure 1) for the power conversion application of the UPS_1 to UPS_n. Therefore, the UPS_S requires a large configuration space and has a high configuration cost.

On the other hand, in existing technologies, the energy storage system 300 is mainly used for power regulation on the power supply bus AC_Bus. When there is AC power Pac on the power supply bus AC_Bus, the AC power Pac is used for energy storage, and when there is no AC power Pac on the power supply bus AC_Bus, the energy is released to the power supply bus AC_Bus. Therefore, in the entire power system 100, the energy storage system 300 is an independent system separate from the uninterruptible power supply system UPS_S, and performs power regulation based on the status of the power supply bus AC_Bus. Furthermore, its internal power conversion operations are unrelated to the power conversion operations within the uninterruptible power supply system UPS_S. That is, in existing technologies, the energy storage system 300 uses a separate cabinet to couple to the power supply bus AC_Bus, and apart from coupling to the power supply bus AC_Bus, there are no other power-related lines coupled to other systems.

Therefore, in the architecture described above, the overall client-side power consumption will involve two independently operating battery systems, one in the energy storage system 300 and the other in the uninterruptible power supply system UPS_S. However, due to the high cost of battery equipment and the need for... Regular replacement leads to relatively high equipment and maintenance costs. Therefore, the main purpose and effect of this disclosure is to provide a common battery-based solution that can be used in both the energy storage system 300 and the uninterruptible power supply (UPS)_S. In this architecture, the battery module 2 is designed as a shared resource between the energy storage system 300 and the UPS_S, charging and discharging according to the possible scenarios of mains power. This not only improves the utilization efficiency of the battery module 2 but also significantly reduces equipment and maintenance costs, achieving the goal of high efficiency and low cost.

Specifically, this disclosure uses the shared battery module 2 as a shared resource to support the energy storage system 300 and the uninterruptible power supply (UPS)_S. This is achieved by coupling one end of the DC-DC converter 3 to the battery module 2, and the other end to the external UPS_S via external lines Te_1 to Te_n. In this way, the first controller 4 can fully utilize the first DC power Pdc1 of the battery module 2, and through the uninterrupted switching of the UPS_S, the efficiency of the energy storage system 300 can be effectively improved, and electricity costs can be significantly reduced, thereby effectively reducing equipment problems and battery maintenance costs.

Therefore, in summary, the main feature of this invention is that when the mains power 200 fails, the first controller 4 can control the DC-DC converter 3 to convert the first DC power Pdc1 into the second DC power Pdc2, and supply the second DC power Pdc2 to the DC buses DC_Bus_1 to DC_Bus_n of the uninterruptible power supplies UPS_1 to UPS_n through external lines Te_1 to Te_n. The uninterruptible power supplies UPS_1 to UPS_n then convert the second DC power Pdc2 into output power Po_1 to Po_n based on whether the downstream is coupled to critical loads Lc_1 to Lc_n, to supply power to the coupled critical loads Lc_1 to Lc_n. In this way, the uninterruptible power supplies UPS_1 to UPS_n do not require additional batteries B1 to Bn (as shown in Figure 1), allowing the entire uninterruptible power supply system UPS_S to save space in the battery cabinets Cb_1 to Cb_n, or allowing the space in the battery cabinets Cb_1 to Cb_n to be used for other applications. In this way, equipment and maintenance costs can be significantly reduced, achieving the goal of high efficiency and low cost.

Furthermore, the power system 100 may also include a non-critical load Ln, which is coupled to the power supply bus AC_Bus. The power regulating device 1 can be a bidirectional power converter with an isolation transformer (not shown). Thus, the power regulating device 1 can bidirectionally convert AC power Pac and a first DC power Pdc1 to meet the power supply requirements of the power system 100. Moreover, the isolation transformer can electrically isolate the input and output terminals of the power regulating device 1, thereby isolating the power regulation at the power supply bus AC_Bus terminal from the power regulation at the battery module 2 terminal, preventing an anomaly at one terminal from affecting the other.

On the other hand, a circuit breaker Br is also included between the power supply bus AC_Bus and the mains power 200, the uninterruptible power supply devices UPS_1 to UPS_n, and the energy storage system 300. The circuit breaker Br is mainly based on the voltage and current flowing through it. It can automatically perform circuit breaking or short circuit operations, and can also be controlled by, for example, but not limited to, the first controller 4 or uninterruptible power supply devices UPS_1 to UPS_n to force circuit breaking, so as to temporarily shut down circuits that do not require power supply to avoid additional power consumption.

Please refer to Figure 3A, which is a detailed circuit block diagram of the first embodiment of the power system disclosed herein, and also refer to Figure 2. In Figure 3A, each uninterruptible power supply (UPS_1 to UPS_n) includes an AC/DC converter 20, a DC/AC converter 22, and a second controller 24, and the AC/DC converter 20 is coupled to the power supply bus AC_Bus. One end of the DC/AC converter 22 is coupled to the AC/DC converter 20 through its own DC bus DC_Bus_1 to DC_Bus_n, and when a critical load Lc_1 to Lc_n (assuming it is critical load Lc_1) is coupled to this UPS_1 to UPS_n (assuming it is UPS_1), the critical load Lc_1 is coupled to the other end of the DC/AC converter 22 of the UPS_1 (i.e., the corresponding coupling relationship). The second controller 24 is coupled to the AC/DC converter 20 and the DC/AC converter 22 to control the power conversion between the AC/DC converter 20 and the DC/AC converter 22.

Furthermore, the second controller 24 can control the AC/DC converter 20 to convert AC power Pac into second DC power Pdc2, and supply the second DC power Pdc2 to the DC/AC converter 22 via DC buses DC_Bus_1 to DC_Bus_n. The second controller 24 can also control the DC/AC converter 22 to convert the second DC power Pdc2 into output power Po_1 to Po_n, so as to supply the output power Po_1 to Po_n to the critical loads Lc_1 to Lc_n. Therefore, when the mains power 200 is available (representing that the AC power Pac is normal), the second controller 24 can control the AC/DC converter 20 to convert AC power Pac into second DC power Pdc2, and control the DC/AC converter 22 to convert the second DC power Pdc2 into output power Po_1 to Po_n, so as to supply the output power Po_1 to Po_n to the critical loads Lc_1 to Lc_n.

Conversely, when the mains power 200 fails (representing an abnormality in the AC power Pac), the second controller 24 can disable the AC/DC converter 20 and control the DC/AC converter 22 to convert the second DC power Pdc2 provided by the DC converter 3 into output power Po_1 to Po_n, so as to uninterruptibly power the critical loads Lc_1 to Lc_n. In the conventional technology shown in Figure 1, when the mains power 200 fails, the second DC power Pdc2 is supplied by the batteries B1 to Bn inside the uninterruptible power supply devices UPS_1 to UPS_n, or the energy storage system 300 first feeds AC power Pac to the power supply bus AC_Bus, and then the uninterruptible power supply devices UPS_1 to UPS_n convert the AC power Pac provided by the energy storage system 300.

Please refer to Figure 3B for a detailed circuit block diagram of the second embodiment of the power system disclosed herein, and also refer to Figures 2 to 3A. The difference between Figure 3B and Figure 3A is that each uninterruptible power supply (UPS_1) to UPS_n further includes... Bypass switch SW. One end of bypass switch SW is coupled to AC/DC converter 20 and power supply bus AC_Bus, and the other end of bypass switch SW is coupled to the output terminal of DC/AC converter 22. Furthermore, when mains power 200 is available (representing normal AC power Pac), the second controller 24 can first control AC/DC converter 20 to convert AC power Pac to second DC power Pdc2, and then control DC/AC converter 22 to convert second DC power Pdc2 to output power Po_1 to Po_n. After confirming that the above operations are normal, the second controller 24 can control bypass switch SW to conduct, causing uninterruptible power supplies UPS_1 to UPS_n to enter energy-saving mode. Specifically, when the bypass switch SW is turned on, the AC power Pac can be directly supplied to the critical loads Lc_1 to Lc_n as output power Po_1 to Po_n, and the AC/DC converter 20 and the DC/AC converter 22 can enter modes such as, but not limited to, disabled or hibernation, without performing power conversion operations, so that they consume virtually no power (i.e., energy-saving mode).

It is worth mentioning that, in one embodiment, the operation of Figure 3B when the mains power 200 fails is similar to that of Figure 3A, and will not be described again here. On the other hand, in Figure 3B, regardless of whether the mains power 200 is available or not, the AC/DC converter 20 only operates when it initially receives AC power Pac when the mains power 200 is available, to verify whether the AC/DC converter 20 is functioning correctly, and it operates almost non-existently during other periods. Therefore, if the uninterruptible power supplies UPS_1 to UPS_n can eliminate this verification of the AC/DC converter 20's functionality, then the uninterruptible power supplies UPS_1 to UPS_n disclosed herein can omit the AC/DC converter 20 (indicated by dashed boxes under the specific conditions described above), thereby significantly reducing circuit costs.

In Figures 3A and 3B, the energy storage system 300 also includes multiple unidirectional conducting components D1 to Dn. These unidirectional conducting components D1 to Dn can be, for example but not limited to, directional electronic components such as diodes and thyristors. The unidirectional conducting components D1 to Dn are connected in series with external lines Te_1 to Te_n, and the number of unidirectional conducting components D1 to Dn can be equal to the number of external lines Te_1 to Te_n. The direction of the unidirectional conducting components D1 to Dn from the DC-DC converter 3 to the uninterruptible power supply (UPS_1 to UPS_n) is forward, preventing power from the DC-DC bus (DC_Bus_1 to DC_Bus_n) from being supplied to the DC-DC converter 3 via external lines Te_1 to Te_n.

Specifically, since typical uninterruptible power supplies (UPS_1 to UPS_n) include batteries B1 to Bn (as shown in Figure 1), when UPS_1 to UPS_n need to charge batteries B1 to Bn, UPS_1 to UPS_n will charge batteries B1 to Bn respectively using current from DC_Bus_1 to DC_Bus_n. However, the energy storage system 300 disclosed herein uses a power regulating device 1 to convert a first DC power Pdc1 to charge the battery module 2, and the energy storage system 300 and the uninterruptible power supply... UPS_1 to UPS_n are also independent devices. Therefore, unidirectional conduction components D1 to Dn can be connected in series on the external lines Te_1 to Te_n to prevent the second DC power Pdc2 on the DC bus DC_Bus_1 to DC_Bus_n from flowing back to the DC converter 3.

In detail, this disclosure allows a shared battery module 2 to be coupled to multiple uninterruptible power supplies (UPS_1 to UPS_n) of the energy storage system 300 and the uninterruptible power supply (UPS_S) via a DC-DC converter 3. Since the battery module 2 of the energy storage system 300 operates at a high DC voltage (e.g., but not limited to 900V to 1000V), and the DC voltage of its shared battery module 2 falls under the high DC voltage application of the battery module 2, while the uninterruptible power supplies (UPS_1 to UPS_n) operate at a low DC voltage (e.g., but not limited to 400V to 600V), the battery module 2 can be designed to couple to multiple uninterruptible power supplies (UPS_1 to UPS_n), and is protected against reverse current flow via unidirectional conduction components D1 to Dn.

In this embodiment, diodes are preferred for the unidirectional conduction components D1 to Dn. This is because diodes do not require a controller to provide control signals for driving, thus achieving a simple implementation without the need for complex control circuitry. Furthermore, in some circuit architectures (such as, but not limited to, Flyback converters), the output of the DC-DC converter 3 is typically connected in series with a circuit breaker (not shown) to prevent non-compliant output power from being supplied to downstream loads. Therefore, if a circuit breaker is already present at the output of the DC-DC converter 3, the unidirectional conduction components D1 to Dn can be omitted to save on circuit costs.

Referring to Figures 3A and 3B, when the mains power 200 is available, it can supply power to the non-critical load Ln via the power supply bus AC_Bus. When the mains power 200 fails, further operations can be performed based on the cause of the failure. Specifically, the most likely causes of the mains power 200 failure are a power outage or an abnormality in the AC power supply Pac (e.g., but not limited to, non-compliant AC voltage or frequency). Therefore, when the mains power 200 fails, the first controller 4 can determine whether the failure is due to a mains power interruption or an abnormality by detecting the power supply bus AC_Bus, and then perform corresponding operations. The status of the mains power 200 can be detected not only by the first controller 4, but also by other controllers such as, but not limited to, the system controller of the power system 100 (not shown), before being supplied to the first controller 4; therefore, it is not limited to detection by the first controller 4 alone. Therefore, when the mains power 200 fails, in addition to controlling the DC-DC converter 3 in the manner described in Figures 3A and 3B, the first controller 4 can also control the power regulating device 1 according to the mains power interruption and abnormal mains power conditions.

Specifically, when the mains power 200 fails (a mains power interruption), the first controller 4 controls the power regulating device 1 to convert the first DC power Pdc1 into AC power Pac to supply power to the non-critical load Ln. Optionally, when the mains power 200 fails (a mains power interruption), the first controller 4 can temporarily turn off the circuit breaker Br coupled to the non-critical load Ln to temporarily stop supplying power to the non-critical load Ln. In this way, the power consumption of the battery module 2 can be saved, and the time that the uninterruptible power supply devices UPS_1 to UPS_n supply power to the critical loads Lc_1 to Lc_n can be extended.

On the other hand, when the mains power 200 fails, it indicates an abnormal mains power condition, meaning that although there is AC power Pac, the supplied AC power Pac is non-compliant. Therefore, the first controller 4 can detect which parameter of the AC power Pac on the current power supply bus AC_Bus is non-compliant (e.g., but not limited to voltage, current, virtual power, harmonics, etc.). Then, the first controller 4 controls the power regulating device 1 to convert the first DC power Pdc1 into the first compensation power Pc1, so as to provide the first compensation power Pc1 to the power supply bus AC_Bus and compensate the non-compliant AC power Pac to the compliant AC power Pac, avoiding the risk of non-critical load Ln failing due to the non-compliant AC power Pac being supplied to it.

Similarly, since non-critical loads Ln generally do not have very high requirements for the quality of the input source, if the failure of the mains power 200 is due to an abnormal mains power condition, and the non-critical load Ln does not have high requirements for the quality of the input source, the first controller 4 does not need to control the power regulating device 1 to convert the first DC power Pdc1 to the first compensated power Pc1, so that the uncompensated AC power Pac can still supply power to the non-critical load Ln. In this way, the power consumption of the battery module 2 can be saved, and the time for the uninterruptible power supply devices UPS_1 to UPS_n to supply power to the critical loads Lc_1 to Lc_n can be extended. On the other hand, in order to maintain the continuous operation of the critical loads Lc_1 to Lc_n, the first controller 4 still controls the DC-DC converter 3 to convert the first DC power Pdc1 to the second DC power Pdc2.

The aforementioned energy storage system 300 can supply power to the non-critical load Ln or provide first compensation power Pc1 to compensate for the AC power Pac under the condition that the AC power Pac fails, and assuming that the battery capacity of the battery module 2 remains above a certain capacity threshold (e.g., but not limited to above 80% battery capacity). However, when the battery capacity of the battery module 2 is insufficient, the first controller 4 can disable the power regulation device 1 to suspend the supply of power to the non-critical load Ln or the compensation for the AC power Pac, so as to avoid excessive battery capacity consumption that would prevent the uninterruptible power supply devices UPS_1 to UPS_n from extending the time they supply power to the critical loads Lc_1 to Lc_n.

Similarly, when the mains power supply 200 is available, the energy storage system 300 can also perform compensation operations on the AC power Pac to improve the power quality of the AC power Pac. Specifically, when the mains power supply 200 is available, the first... The controller 4 can determine whether the battery capacity of the battery module 2 is higher than a first capacity threshold (e.g., but not limited to, above 80% of the battery capacity), and based on the battery capacity being higher than the first capacity threshold, control the power regulation device 1 to convert the first DC power Pdc1 into the second compensation power Pc2 to provide the second compensation power Pc2 to the power supply bus AC_Bus. The operation of providing the second compensation power Pc2 can adopt a droop control (frequency-real power, voltage-virtual power) operation mode for FP and VQ. By measuring the voltage amplitude and frequency of the distributed power source output, the corresponding reference active and reactive power are calculated to compensate for the AC power Pac, further improving the power quality of the AC power Pac, thereby stabilizing and improving the working efficiency of the non-critical load Ln.

Conversely, when the first controller 4 determines that the battery capacity is lower than the first capacity threshold, the first controller 4 can stop providing the second compensation power Pc2, and instead control the power regulating device 1 to reverse the AC power Pac to convert the first DC power Pdc1 to charge the battery module 2 and improve its range. In addition, since the mains power 200 is still available, the AC power Pac can be directly supplied to the uninterruptible power supply (UPS_1~UPS_n) without the need for the energy storage system 300 to provide supplementary power (the situation where the energy storage system 300 can provide supplementary power will be further described later to avoid confusion, and will not be repeated here). Therefore, the first controller 4 can temporarily disable the DC-DC converter 3 so that the energy storage system 300 can store energy and temporarily stop providing power to the outside world.

The first compensation power Pc1 is used to compensate for non-compliant AC power Pac, while the second compensation power Pc2 further improves the quality of compliant AC power Pac. Therefore, the power consumed by the power regulating device 1 when converting the first compensation power Pc1 is generally greater than that when converting the second compensation power Pc2. Furthermore, although the specific capacity threshold and the first capacity threshold are illustrated using 80% battery capacity as an example, these thresholds can be adjusted according to actual needs; they can be the same or different thresholds.

Referring again to Figures 3A and 3B, the power system 100 disclosed herein may further include a peak shaving and valley filling operation mode. Specifically, the peak shaving and valley filling operation mode mainly controls the energy storage and release of battery module 2 according to time-of-use pricing, peak and off-peak periods, etc., and uses the charging and discharging of energy storage system 300 to achieve peak and off-peak power shifting. Therefore, during peak electricity consumption periods or when electricity prices are high, and when the battery capacity of battery module 2 is still sufficient, power system 100 can reduce the AC power Pac obtained from mains power 200, and use battery capacity as the main power source to achieve the effect of saving electricity costs or AC power Pac consumption. Conversely, during non-peak electricity consumption periods or when electricity prices are low, it can maximize the use of battery module 2. It can obtain power from the AC power Pac and quickly replenish the battery capacity to extend the backup power supply time in the event of a mains power failure.

Furthermore, the first controller 4 can set specific time periods based on conditions such as, but not limited to, peak electricity consumption periods or higher electricity prices. During these specific time periods, the first controller 4 can determine whether the battery capacity of the battery module 2 is higher than a second capacity threshold (e.g., but not limited to, above 50% battery capacity). When the first controller 4 determines that the battery capacity is higher than the second capacity threshold during a specific time period, it indicates that the battery capacity is sufficient. Therefore, the first controller 4 controls the DC-DC converter 3 to convert the first DC power Pdc1 into the second DC power Pdc2 to reduce the AC power Pac obtained from the mains power 200. On the other hand, the operation of the energy storage system 300 to feed or compensate the power supply bus AC_Bus can be selectively performed according to the settings of the first controller 4. Its operation is as described above and will not be repeated here.

Conversely, when the first controller 4 determines that the battery capacity is lower than the second capacity threshold during a specific period, it indicates that the battery capacity is insufficient and may not be able to support the backup power supply for a sufficient period of time in the event of an emergency. Therefore, the first controller 4 disables the DC-DC converter 3 and can choose whether to use the power regulation device 1 to convert AC power Pac to charge the battery module 2, or temporarily maintain the battery capacity at the second capacity threshold (which can be set by the user).

Specifically, during a specific period, when the battery capacity of battery module 2 exceeds the second capacity threshold, the power system 100 can choose to have the energy storage system 300 supply power solely to critical loads Lc_1 to Lc_n and/or non-critical load Ln, without drawing AC power Pac at all. Alternatively, the power system 100 can choose to have the energy storage system 300 and the power outage devices UPS_1 to UPS_n operate together to supply power to critical loads Lc_1 to Lc_n, and have the energy storage system 300 and the AC power Pac supply power to non-critical load Ln together. This facilitates adjustment of the AC power Pac consumed by the power system 100, preventing the AC power Pac consumed by the power system 100 from exceeding a preset upper limit during a specific period.

On the other hand, during periods other than peak electricity consumption or when electricity prices are low (i.e., non-specific periods), the power system 100 can obtain power from the AC power Pac as much as possible and quickly replenish the battery capacity. Therefore, the first controller 4 disables the DC-DC converter 3 and controls the power regulating device 1 to switch the AC power Pac to charge the battery module 2, thereby extending the backup power supply time of the energy storage system 300. In short, regardless of whether a specific period is set, the power supply, charging, and power compensation operations of the energy storage system 300 are all determined and controlled accordingly by the first controller 4, which can be inferred from the content described above and will not be repeated here. Furthermore, although the second capacity threshold mentioned above uses 50% battery capacity as an illustrative example, the second capacity threshold can be adjusted according to actual needs, and may even be different from the first capacity threshold. The values are adjusted accordingly, which will not be elaborated here. Since it is necessary to minimize the reliance on AC power from the mains during peak electricity consumption periods or periods with higher electricity prices, the second capacity threshold is generally set lower than the first capacity threshold, but this is not a limitation.

Please refer again to Figures 3A and 3B. Battery module 2 also includes multiple batteries 26, which can be connected in series or parallel to form battery module 2. First controller 4 can detect parameters such as voltage, current, and available capacity of each battery 26 in battery module 2 through, for example, but not limited to, a battery management system (not shown), and regulate each battery 26 according to its parameters and the power demand of power regulation device 1 and DC-DC converter 3. When the available capacity of a battery 26 is insufficient (e.g., but not limited to below a low charge threshold), first controller 4 can individually disable this battery 26 through the battery management system, causing the disabled battery 26 to wait for the power regulation device 1 to schedule its charging time. After first controller 4 aggregates the available capacity of all batteries 26, it can calculate the total battery capacity of battery module 2 and regulate it based on the difference between the battery capacity and a specific capacity threshold, a first capacity threshold, or a second capacity threshold.

Please refer to Figure 4 for a schematic diagram of the external wiring disclosed herein, and also refer to Figures 2 to 3B. In Figure 4, the external wiring Te_1 to Te_n includes not only the power line L1 used for power transmission, but also the communication line L2 used for communication. The communication line L2 is coupled to the first controller 4 and the second controller 24, and the first controller 4 and the second controller 24 transmit information to each other through the communication line L2, so that they can know, for example, but not limited to, parameters detected by the first DC power Pdc1, the second DC power Pdc2, and specific time periods, the preset parameters of each controller, and the operating status of their respective internal devices. In this way, the cooperation between the energy storage system 300 and the uninterruptible power supply system UPS_S can be more compatible, thereby further improving the operating efficiency of the power system 100.

Specifically, in the conventional operation of uninterruptible power supplies (UPS_1 to UPS_n) for backup power, the UPS_1 to UPS_n do not change their own operating mode based on commands (or information) from the energy storage system 300. However, when the external lines Te_1 to Te_n include the communication line L2, enabling the first controller 4 and the second controller 24 to communicate with each other, the second controller 24 can control the AC/DC converter 20 and the DC/AC converter 22 accordingly based on the current operation of the energy storage system 300, in order to cooperate with the current operation of the energy storage system 300. For example, in the conventional UPS_1 to UPS_n, the second controller 24 only controls the AC/DC converter 20, the DC/AC converter 22, and the bypass switch SW to supply power to the critical loads Lc_1 to Lc_n based on whether the mains power 200 is available, without any connection to peak shaving and valley filling operation.

However, this disclosure states that when the mains power 200 is available, and during a specific period, if the battery capacity of battery module 2 is higher than the second capacity threshold and can supply power externally, the first controller 4 can control the DC-DC converter 3 to convert the first DC power Pdc1 into the second DC power Pdc2. At this time, if the external lines Te_1 to Te_n include a communication line L2, allowing the first controller 4 and the second controller 24 to communicate with each other, the second controller 24 can learn through the communication line L2 that the DC-DC converter 3 is providing the second DC power Pdc2, and whether the second DC power Pdc2 can meet the operational needs of the critical loads Lc_1 to Lc_n. Therefore, the second controller 24 can disable the AC/DC converter 20, and even turn off the bypass switch SW, to save power consumption of the uninterruptible power supplies UPS_1 to UPS_n.

It is worth mentioning that, in one embodiment, the external lines Te_1 to Te_n may only include the power line L1 and exclude the communication line L2. The second controller 24 can detect whether the external lines Te_1 to Te_n provide the second DC power Pdc2, and specific time periods can be preset in the second controller 24 so that the communication line L2 is not required, thus achieving the effect of saving power consumption of the uninterruptible power supply UPS_1 to UPS_n. In addition, if the power system 100 does not have peak shaving and valley filling operations (i.e., no specific time period is set), the external lines Te_1 to Te_n may also only include the power line L1 and simply transmit power.

Therefore, in summary, considering the normal operation of the mains power 200 or potential accident scenarios, the operation method of the energy storage system shown in Figure 5 can be summarized through the operations that the energy storage system 300 can perform. Specifically, in the steps of Figure 5, steps (S100) and (S200) are performed first to detect whether the mains power has failed. Furthermore, after the mains power 200 fails, steps (S120) and (S220) are performed to control the DC-DC converter 3 to convert the first DC power Pdc1 into the second DC power Pdc2 according to the failure of the mains power 200, and the second DC power Pdc2 is provided to the DC buses DC_Bus_1 to DC_Bus_n of the uninterruptible power supplies UPS_1 to UPS_n through multiple external lines Te_1 to Te_n respectively.

Furthermore, in step (S100), it is determined whether a mains power interruption has occurred. If a mains power interruption occurs, the system switches to battery module power supply (S120). At this time, the first controller 4 controls the DC-DC converter 3 to convert the first DC power Pdc1 into the second DC power Pdc2. After step (S120), a black start is performed to provide AC power to the power supply bus (S140). At this time, the first controller 4 controls the power regulating device 1 to convert the first DC power Pdc1 into AC power Pac, so as to provide the AC power Pac to the power supply bus AC_Bus. Finally, the system detects that the mains power is valid and switches to energy-saving mode (S300). When the mains power 200 is detected to be restored to valid (representing that the AC power Pac is normal), the second controller 24 can first control the AC/DC converter 20 to convert the AC power Pac into the second DC power Pdc2, and control the DC power Pac to be converted into the second DC power Pdc2. The AC/DC converter 22 converts the second DC power Pdc2 into output power Po_1 to Po_n. After confirming that the above operation is normal, the second controller 24 can control the bypass switch SW to turn on, so that the uninterruptible power supply (UPS_1 to UPS_n) enters the energy-saving mode. Alternatively, if the AC/DC converter 20 is omitted from the UPS_1 to UPS_n, the second controller 24 can directly control the bypass switch SW to turn on, so that the UPS_1 to UPS_n enters the energy-saving mode. After step (S300), the process can return to step (S100) to continuously monitor the status of the mains power 200.

Similarly, in step (S200), it is determined whether a mains power abnormality has occurred. If a mains power abnormality occurs, the system switches to battery module power supply (S220). After step (S220), first compensation power is provided to the power supply bus (S240). At this time, the first controller 4 controls the power adjustment device 1 to convert the first DC power Pdc1 into the first compensation power Pc1, and provides the first compensation power Pc1 to the power supply bus AC_Bus to compensate the non-compliant AC power Pac to the compliant AC power Pac, avoiding the risk of non-critical load Ln failing due to the non-compliant AC power Pac being provided to the non-critical load Ln. After step (S240), when the mains power 200 is restored to a valid state, the system proceeds to step (S300) and returns to step (S100) to continuously monitor the status of the mains power 200. The order of judgment in steps (S100) and (S200) can be interchanged without affecting the operation of the energy storage system 300.

On the other hand, after steps (S100) and (S200), indicating that the mains power 200 is effective, the process proceeds to step (S400) to determine whether the battery capacity of the battery module is higher than the first capacity threshold. When the battery capacity of the battery module 2 is lower than the first capacity threshold, the uninterruptible power supply (UPS) enters energy-saving mode, and the power regulator charges the battery module (S600). When the first controller 4 determines that the battery capacity is lower than the first capacity threshold, the first controller 4 can control the power regulator 1 to convert the AC power Pac into the first DC power Pdc1 to charge the battery module 2 and improve the battery module 2's endurance. In addition, since the mains power 200 is still effective, the AC power Pac can be directly supplied to the uninterruptible power supply UPS_1 to UPS_n without the need for the energy storage system 300 to provide additional power, and the uninterruptible power supply UPS_1 to UPS_n can turn on the bypass switch SW to enter energy-saving mode.

Conversely, when the battery capacity of battery module 2 is higher than the first capacity threshold, a second compensation power is provided to the power supply bus (S420). At this time, the first controller 4 can control the power regulating device 1 to convert the first DC power Pdc1 into the second compensation power Pc2 to provide the second compensation power Pc2 to the power supply bus AC_Bus. Then, peak shaving and valley filling operations are performed (S440). At this time, the first controller 4 controls the DC conversion device 3 to convert the first DC power Pdc1 into the second DC power Pdc2 during a specific period of time to reduce the AC power Pac obtained from the mains power 200.

After step (S440), it is determined whether any batteries in the battery module are disabled (S460). Since the available capacity of each battery 26 in battery module 2 is not the same, during step (S440) when the battery capacity of battery module 2 is consumed to power critical loads Lc_1 to Lc_n and/or non-critical loads Ln, some batteries 26 may become disabled due to insufficient available capacity (i.e., below the low power threshold). Therefore, the first controller 4 determines whether any batteries 26 are disabled. If no batteries 26 are disabled, the process returns to step (S100) to continuously monitor the status of the mains power 200. Conversely, if any batteries 26 are disabled, the battery capacity of the entire battery module is calculated based on the available capacity of the remaining batteries (S480). Furthermore, the power regulating device is charged according to the scheduling (S500). When the available capacity of a battery 26 is insufficient (e.g., but not limited to below the low charge threshold), the first controller 4 can individually disable this battery 26 through the battery management system, causing the disabled battery 26 to wait for the first controller 4 to schedule the power regulation device 1 to charge it when it is available. Furthermore, after step (S500), the process can return to step (S100) to continuously monitor the status of the mains power 200.

Based on the above architecture and system context, this disclosure presents a design and operation mode that utilizes a shared battery in both the energy storage system 300 and the uninterruptible power supply (UPS)_S. Compared to the existing two independently operating battery modules in the energy storage system 300 and batteries B1-Bn in the UPS_S, this disclosure offers significant cost benefits and optimizes user power consumption efficiency and reduces costs. The shared battery plays a dual role in the energy storage system 300, maximizing the utilization efficiency of the battery module 2 while significantly reducing equipment and maintenance costs, achieving an optimal balance between economy and efficiency. This not only ensures the stable operation of the client power system 100 but also lays a solid foundation for the future development of smart energy systems. Notably, in one embodiment, detailed operating methods not shown in Figure 5 can be found in Figures 2-3B, which already provide detailed operational descriptions. Therefore, those skilled in the art can reasonably deduce feasible operating methods for the energy storage system, in addition to the preferred embodiment shown in Figure 5 of this disclosure, based on the detailed operating methods in Figures 2-3B.

However, the above description is only a detailed description and accompanying drawings of preferred embodiments of this disclosure. The features of this disclosure are not limited thereto and are not intended to limit this disclosure. The entire scope of this disclosure should be determined by the following claims. All embodiments that conform to the spirit of the claims of this disclosure and similar variations thereof should be included in the scope of this disclosure. Any variations or modifications that can be easily conceived by those skilled in the art in the field of this disclosure are covered by the following patent scope.

Claims (18)

An energy storage system is coupled to the mains power of a power system via a power supply bus, and the power system includes multiple uninterruptible power supplies (UPS) coupled to the power supply bus. The energy storage system includes: Power regulation device, coupled to the power supply bus; The battery module is coupled to the power regulation device; A DC-DC converter, one end of which is coupled to the battery module, and the other end of which is coupled to multiple DC buses of the multiple uninterruptible power supplies via multiple external lines; and A first controller is coupled to the power regulation device and the DC-DC conversion device. When the mains power is operating normally, the first controller controls the power regulation device to convert the AC power on the power supply bus into a first DC power to charge the battery module. When the mains power fails, the first controller controls the DC-DC converter to convert the first DC power into a second DC power, and provides the second DC power to the multiple DC buses through the multiple external lines. According to the energy storage system of claim 1, the power system further includes non-critical loads, and the non-critical loads are coupled to the power supply bus; when the mains power fails, the first controller determines whether the mains power failure is a mains power interruption or a mains power abnormality, and controls the power regulation device accordingly based on the mains power interruption or the mains power abnormality. According to the energy storage system of claim 2, when the mains power failure is a mains power interruption condition, the first controller controls the power regulation device to convert the first DC power into the AC power to supply power to the non-critical load. According to the energy storage system of claim 2, when the mains power failure is due to an abnormal mains power condition, the first controller controls the power regulation device to convert the first DC power into first compensation power to provide the first compensation power to the power supply bus to compensate for the AC power provided by the mains power. According to the energy storage system of claim 1, when the mains power is available, the first controller determines whether the battery capacity of the battery module is higher than a first capacity threshold, and controls the power regulation device to convert the first DC power into second compensation power based on the battery capacity being higher than the first capacity threshold, so as to provide the second compensation power to the power supply bus to compensate for the AC power provided by the mains power. According to the energy storage system of claim 5, when the first controller determines that the battery capacity is lower than the first capacity threshold, the first controller disables the DC-DC converter and controls the power regulation device to convert the AC power into the first DC power. According to the energy storage system of claim 5, wherein the first controller sets a specific time period, and during the specific time period, the first controller controls the DC-DC converter to convert the first DC power into the second DC power based on the battery capacity being higher than a second capacity threshold. According to claim 5, the energy storage system, wherein the battery module comprises: Multiple batteries are connected in series or in parallel to form the battery module; The first controller detects multiple available capacities of the plurality of batteries and calculates the battery capacity of the battery module based on the multiple available capacities. The energy storage system according to claim 1 further includes: Multiple unidirectional conduction components are connected in series with the multiple external lines, respectively; The direction of the plurality of unidirectional conduction components from the DC conversion device to the plurality of uninterruptible power devices is forward. An electric power system coupled to mains power, the electric power system comprising: The power supply busbar receives AC power from the mains power supply; Multiple uninterruptible power supplies (UPS) are coupled to the power supply bus and can be coupled to multiple critical loads to correspondingly convert the AC power into multiple output powers to power the multiple critical loads; and An energy storage system, coupled to the power supply bus and the plurality of uninterruptible power supplies (UPS), and comprising: Power regulation device, coupled to the power supply bus; The battery module is coupled to the power regulation device; A DC-DC converter, one end of which is coupled to the battery module, and the other end of which is coupled to multiple DC buses of the multiple uninterruptible power supplies via multiple external lines; and A first controller is coupled to the power regulation device and the DC-DC conversion device. When the mains power is operating normally, the first controller controls the power regulation device to convert the AC power into a first DC power to charge the battery module. When the mains power fails, the first controller controls the DC-DC converter to convert the first DC power into a second DC power, and provides the second DC power to the multiple DC buses through the multiple external lines. The multiple uninterruptible power supplies provide multiple output powers according to the second DC power. According to claim 10, the power system wherein the plurality of uninterruptible power supplies (UPS) each comprises: AC/DC converter, coupled to the power supply bus; A DC/AC converter is coupled to the AC/DC converter via a DC bus among the plurality of DC buses, and correspondingly coupled to the critical loads of the plurality of critical loads; and The second controller is coupled to the AC/DC converter and the DC/AC converter. When the mains power fails, the second controller disables the AC/DC converter and controls the DC/AC converter to convert the second DC power into output power from the plurality of output power sources. According to claim 11, the power system further comprises: The bypass switch has one end coupled to the AC/DC converter and the power supply bus, and the other end coupled to the output terminal of the DC/AC converter. According to the power system of claim 12, when the mains power is available, the second controller controls the bypass switch to be turned on so as to use the AC power as the output power. According to the power system of claim 12, wherein the second controller communicates with the first controller to know the first DC power and a specific time period set by the first controller; when the mains power is available and the DC-DC converter provides the second DC power during the specific time period, the second controller disables the AC/DC converter or turns off the bypass switch. An operation method for an energy storage system, wherein the energy storage system is coupled to the mains power of a power system via a power supply bus, and the power system includes multiple uninterruptible power supplies (UPS) coupled to the power supply bus, and the operation method of the energy storage system includes the following steps: Detect whether the mains power is faulty; In response to the mains power failure, the DC-DC converter is controlled to convert the first DC power provided by the battery module into a second DC power, so that the second DC power is provided to the multiple DC buses of the multiple uninterruptible power supplies through multiple external lines. The mains power failure is determined to be either a mains power outage or a mains power malfunction. Based on the fact that the mains power failure is a mains power interruption, the control power regulation device converts the first DC power into AC power to supply the AC power to the power supply bus; and Since the mains power failure is considered an abnormal mains power condition, the power regulation device is controlled to convert the first DC power into first compensation power to provide the first compensation power to the power supply bus and compensate for the AC power provided by the mains power. The method of operating the energy storage system according to claim 15 further includes the following steps: Based on the availability of mains power, determine whether the battery capacity of the battery module is higher than the first capacity threshold. Based on the battery capacity being higher than the first capacity threshold, the power regulation device is controlled to convert the first DC power into second compensation power, so as to provide the second compensation power to the power supply bus to compensate for the AC power provided by the mains power; and The DC-DC converter is disabled when the battery capacity is lower than the first capacity threshold, and the power regulation device is controlled to convert the AC power into the first DC power. The method of operating the energy storage system according to claim 16 further includes the following steps: Set a specific time period; and During the specific time period, the DC-DC converter is controlled to convert the first DC power into the second DC power based on the battery capacity being higher than the second capacity threshold. The method of operating the energy storage system according to claim 16 further includes the following steps: Determine whether at least one of the multiple batteries in the battery module is disabled; When at least one battery is disabled, the battery capacity of the battery module is calculated based on the available capacity of the remaining batteries; The power regulating device is controlled to charge the at least one battery according to the schedule.