Power control device and method for controlling a DC-DC converter

Abstract

The power control device and method according to the embodiment of the present invention monitors the output power of the PCS to detect a voltage change in the DC link section, and compares the output power of the PCS with the rated power of the battery to control the output power of the battery, thereby preventing voltage fluctuations in the DC link section and providing stabilization of the energy storage system.

Description

Technical Field

[0001] This application claims the benefit of the filing dates of Korean Patent Application No. 10-2022-0116817, filed with the Korean Intellectual Property Office on September 16, 2022, and Korean Patent Application No. 10-2023-0122905, filed with the Korean Intellectual Property Office on September 15, 2023, and all of the contents disclosed in the documents of the Korean patent applications are incorporated herein.

[0002] The present invention relates to a power control device and method for controlling a DC-DC converter, and more specifically, to a power control device and method for controlling the output of a battery using a DC-DC converter for voltage stabilization of a DC link section.

Background Art

[0003] An energy storage system (ESS) is a system that links renewable energy, a battery storing power, and existing grid power. In recent years, with the spread of smart grids and renewable energy, and with the emphasis on the efficiency and stability of power grids, the demand for energy storage systems is increasing among general households for power supply and demand regulation and power quality improvement. Generally, the output and capacity of a household energy storage system vary depending on the purpose of use.

[0004] For example, a household energy storage system can be applied to a photovoltaic (PV) power generation system and include a battery section composed of a number of batteries, a battery management system (BMS) for battery management, a power conversion system (PCS), an energy management system (EMS), a DC-DC converter, and the like.

[0005] On the other hand, in a home energy storage system, if the load consumes more power than its rated capacity, the PCS (Power Conditioning System) can discharge to stabilize the load. This can cause temporary fluctuations in the DC link voltage, potentially generating ripple.

[0006] Generally, in home energy storage systems, if ripple occurs in the DC link, the ripple current is passed in the grid direction to stabilize the DC link.

[0007] However, in the event of a power outage that limits the use of the grid, home energy storage systems have the disadvantage of reduced power efficiency in delivering power to the load because they cannot channel ripple current towards the grid.

[0008] Furthermore, in the event of a power outage, if a user uses a load, a high peak voltage exceeding the appropriate range may temporarily occur in the DC link section. This has the disadvantage that the PCS and numerous batteries in conventional home energy storage systems will shut down to prevent failure due to overvoltage. [Overview of the project] [Problems that the invention aims to solve]

[0009] The objective of the present invention, in order to solve the above-mentioned problems, is to provide a power control device that controls a DC-DC converter.

[0010] Another objective of the present invention, in order to solve the problems described above, is to provide a power control method for controlling a DC-DC converter.

[0011] Another object of the present invention, in order to solve the problems described above, is to provide an energy storage system that includes a power control device for controlling a DC-DC converter. [Means for solving the problem]

[0012] A power control device according to one embodiment of the present invention for achieving the above objective, which is connected to a converter that performs DC-DC conversion between a battery and a power conversion system (PCS) and controls the output power of the battery, includes a memory and a processor that executes at least one instruction stored in the memory, wherein the at least one instruction includes the steps of an instruction to detect the voltage of a DC link between the input side of the PCS and the output side of the converter, and an instruction to control the output power of the battery based on the output power of the PCS due to the voltage change of the DC link.

[0013] Here, the instruction to control the output power of the battery may include an instruction to control the output power of the battery by controlling the current of the battery.

[0014] Furthermore, the instruction for controlling the output power of the battery may include an instruction to control the battery so that it outputs at a predefined peak power value if the output power of the PCS exceeds a predefined rated power value of the battery.

[0015] In this case, the instruction to control the output to be at the peak power value may further include an instruction to compare the difference between the output power of the PCS and the output power of the battery if the peak power output period of the battery is longer than or equal to a predefined first period, and an instruction to control the battery to output at its rated power if the difference is less than a predefined threshold.

[0016] On the other hand, the instruction to control the output to the peak power value may further include an instruction to compare the difference between the output power of the PCS and the output power of the battery if the peak power output period of the battery is longer than or equal to a predefined first period, and an instruction to gradually control the battery to output at its rated power if the difference is greater than or equal to a predefined threshold.

[0017] Here, the instruction to control the output to occur in stages may include an instruction to control the output to occur by gradually decreasing the threshold power amount over a previously set second period, based on the peak power of the battery.

[0018] Furthermore, the instruction to control the output in stages may further include an instruction to control the battery to output at rated power if the peak power output period exceeds a predefined second period.

[0019] A power control method for controlling the output power of a battery, connected to a converter that performs DC-DC conversion between a battery and a power conversion system (PCS) according to another embodiment of the present invention for achieving the above objective, includes the steps of detecting the voltage of a DC link between the input side of the PCS and the output side of the converter, and controlling the output power of the battery based on the output power of the PCS due to the voltage change of the DC link.

[0020] Here, the step of controlling the output power of the battery may include the step of controlling the current of the battery to control the output power of the battery.

[0021] Furthermore, the step of controlling the output power of the battery may include a step of controlling the battery so that it outputs at a predetermined peak power value if the output power of the PCS exceeds a predetermined rated power value of the battery.

[0022] In this case, the step of controlling the output to be at the peak power value may further include, if the peak power output period of the battery is longer than or equal to a predefined first period, the step of comparing the difference between the output power of the PCS and the output power of the battery, and if the difference is less than a predefined threshold, the step of controlling the battery to output at rated power.

[0023] On the one hand, the step of controlling to output at the peak power value may further include a step of comparing the difference between the output power of the PCS and the output power of the battery when the peak power output period of the battery is longer than a predefined first period, and a step of gradually controlling the battery to output at the rated power when the difference is greater than or equal to a predefined threshold value.

[0024] Here, the step of controlling to output gradually may include a step of controlling to output by gradually decreasing a threshold power amount during a predefined second period based on the peak power of the battery.

[0025] In addition, the step of controlling to output gradually may further include a step of controlling the battery to output at the rated power when the peak power output period exceeds a predefined second period.

[0026] An energy storage system according to another embodiment of the present invention for achieving the above object includes a battery rack, a plurality of converters that perform DC-DC conversion in conjunction with the battery rack, a power conversion system (PCS) connected to the DC-DC converter and a load, and a power control device connected to the DC-DC converter to control the operation of the DC-DC converter. The converter detects the voltage of the DC link section between the input side of the output power of the PCS and the output side of the converter by the power control device, and controls the output power of the battery based on the output power of the PCS due to the voltage change of the DC link section.

[0027] Here, the converter can control the output power of the battery by controlling the current of the battery by the power control device.

[0028] Further, when the output power of the PCS exceeds the pre-defined rated power value of the battery by the power control device, the converter can output the battery at the pre-defined peak power value.

[0029] At this time, when the peak power output period of the battery is longer than or equal to a pre-defined first period, if the difference between the output power of the PCS and the rated power of the battery is less than a pre-defined threshold, the power control device can control the battery to output at the rated power.

[0030] On the other hand, when the peak power output period of the battery is longer than or equal to a pre-defined first period, if the difference between the output power of the PCS and the rated power of the battery is greater than or equal to a pre-defined threshold, the power control device can gradually control the battery to output at the rated power.

[0031] Here, the converter can be controlled by the power control device to output the battery by gradually reducing the threshold power amount during a pre-set second period based on the peak power.

[0032] Further, when the peak power output period exceeds a pre-defined second period, the converter can be controlled by the power control device to output the battery at the rated power.

Advantages of the Invention

[0033] The power control device and method according to the embodiments of the present invention monitor the output power of the PCS, detect the voltage change in the DC link section, compare the output power of the PCS with the rated power of the battery, and control the output power of the battery, thereby preventing voltage fluctuations in the DC link section and providing stabilization of the energy storage system.

Brief Description of the Drawings

[0034] [Figure 1]This is a block diagram of an energy storage system to which the present invention can be applied. [Figure 2] This is a block diagram of an energy storage system in the event of a power outage. [Figure 3] This is a block diagram of a power control device according to an embodiment of the present invention. [Figure 4] This is a flowchart of a power control method according to an embodiment of the present invention. [Figure 5] This is a flowchart illustrating the step of controlling the output power of a battery in a power control method according to an embodiment of the present invention. [Figure 6] This is a flowchart illustrating a power control method according to one embodiment of the present invention. [Figure 7] Figure 6 shows a graph of the voltage change over time in the DC link section. [Figure 8] This is a flowchart illustrating a step in which the output power of a battery is controlled in stages, as part of a power control method according to an embodiment of the present invention. [Figure 9] Figure 8 shows the time-dependent power output control graph of the battery. [Figure 10] This is a block diagram illustrating a power control method according to another embodiment of the present invention. [Figure 11] Figure 10 shows a graph of the voltage change over time in the DC link section. [Modes for carrying out the invention]

[0035] The present invention can be modified in various ways and has many embodiments; therefore, specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this should be understood not as limiting the present invention to specific embodiments, but rather as including all modifications, equivalents, or substitutes that fall within the spirit and technical scope of the present invention. Similar reference numerals are used for similar components in the description of each drawing.

[0036] Terms such as First, Second, A, B, etc., may be used to describe various components, but the components should not be limited by such terms. The terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the First component may be named the Second component, and similarly, the Second component may be named the First component. The term "and / or" includes a combination of multiple related items or one of multiple related items.

[0037] When it is stated that one component is "combined" or "connected" to another component, it should be understood that this may mean that it is directly combined or connected to the other component, but that another component may exist in between. Conversely, when it is stated that one component is "directly combined" or "directly connected" to another component, it should be understood that there is no other component in between.

[0038] The terms used in this application are used solely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless they are clearly different in context. In this application, terms such as “includes” or “having” are intended to specify the presence of features, figures, steps, actions, components, parts, or combinations thereof as described in the specification, and should not be understood to preemptively exclude the presence or possibility of adding one or more other features, figures, steps, actions, components, parts, or combinations thereof.

[0039] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as those generally understood by a person of ordinary skill in the art to which this invention pertains. Terms as defined in commonly used dictionaries should be interpreted as having the meaning consistent with their meaning in the context of the relevant art, and not as ideal or overly formal unless explicitly defined herein.

[0040] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0041] Figure 1 is a block diagram of an energy storage system to which the present invention can be applied.

[0042] Referring to Figure 1, the smallest unit of a battery that plays a role in storing electricity in an energy storage system is usually a battery cell. A series / parallel combination of battery cells forms a battery pack, and a number of battery packs can be realized in the form of a battery rack. That is, a battery rack is a series / parallel combination of battery packs and can be the smallest unit of a battery system. Here, depending on the device or system in which the battery is used, a battery pack may also be called a battery module. For example, batteries #1, #2, ..., and #N shown in Figure 1 may be in the form of a battery pack or a battery rack.

[0043] In this case, each battery may be equipped with a Battery Management System (BMS) 100. The BMS 100 monitors the current, voltage, and temperature of each battery pack (or rack) under its control, calculates the Status of Charge (SOC) based on the monitoring results, and controls charging and discharging.

[0044] On the other hand, each battery system, which includes numerous batteries, peripheral circuits, and devices, can be equipped with a Battery System Controller (BSC). This allows the BSC200 to monitor and control the voltage, current, temperature, and circuit breakers within the battery system. The BSC200 also calculates the output of each DC-DC converter based on the monitored battery status information and transmits this information to the DC-DC converters.

[0045] Furthermore, a Power Conversion System (PCS) 400 provided for each battery system controls the charging and discharging of the battery by controlling the power supplied from an external source and the power supplied from the battery system to an external source, and may include a DC / AC inverter.

[0046] Furthermore, the output of the DC-DC converter 500 can be connected to the PCS400, which in turn can be connected to the grid 600 and load 700. The PCS400 typically operates in constant power mode. The Power Management System (PMS) 300 connected to the PCS400 is the highest-level controller that determines and controls the output of the PCS400 based on the monitoring and control results of the BMS100 or BSC200.

[0047] In the energy storage system shown in Figure 1, battery #1 is connected to DC-DC converter #1, battery #2 is connected to DC-DC converter #2, and battery #N is connected to DC-DC converter #N. The output of the DC-DC converter corresponding to each battery is connected to the PCS400 via a DC link.

[0048] The DC-DC converter 500 may be a bidirectional converter, and when conversion is performed from the battery to the load, the input of the DC-DC converter can be connected to the battery (battery cell, battery pack (module), or battery rack), and the output of the DC-DC converter can be connected to the load. Various types of converters can be used as examples of DC-DC converters, such as full-bridge converters, half-bridge converters, and flyback converters.

[0049] On the other hand, communication between BMS100, BSC200, PMS300, and PCS400 can be conducted using CAN (Controller Area Network) or Ethernet (shown as dotted lines in Figure 1).

[0050] In such energy storage systems, a central controller within the system typically calculates the output value of each battery at every moment and transmits the calculated value as a command to each battery (higher-level control). However, higher-level control is only possible if the system voltage of the energy storage system is maintained, that is, if lower-level control is performed first.

[0051] On the other hand, the DC link, which is the region between the DC-DC converter and the PCS, has a DC voltage, and the voltage of the DC link can usually be called the system voltage.

[0052] The voltage in the DC link section needs to be maintained at a constant level for the stability of the entire energy storage system.

[0053] Figure 2 is a block diagram of an energy storage system under power outage conditions.

[0054] Referring to Figure 2, the power control device according to an embodiment of the present invention can control the DC-DC converter 500 to maintain the voltage of the DC link, i.e., the system voltage, in a constant state, as described above.

[0055] Generally, when a load of 700 consumes power, the PCS400 can output power equal to the magnitude of the output reference (the power value that the PCS should output) calculated by the PMS300 in Figure 1. At this time, the DC voltage in the DC link section may fluctuate temporarily, generating a ripple voltage. As a result, the PCS400 controls the magnitude of the output power so that the magnitude of the ripple voltage in the DC link section remains within an appropriate range.

[0056] Furthermore, if the load 700 generates power consumption exceeding the rated value, the voltage in the DC link section may fluctuate. In this case, the PCS400 either receives additional power from the grid 600 or outputs power towards the grid 600 to control the ripple voltage in the DC link section so that it remains within an appropriate range.

[0057] However, in the event of a power outage, the use of Grid 600 will be restricted, meaning that PCS400 cannot receive power from Grid 600 and cannot channel ripple voltage towards Grid 600. Therefore, ripple voltage may reduce the power efficiency of the energy storage system.

[0058] Furthermore, in the event of a power outage, if the load is operated by the user without notification, a high peak voltage exceeding the appropriate range may temporarily occur in the DC link section. As a result, the PCS400 and battery 500 can shut down their operation through their respective protection circuits to prevent failure due to the peak voltage.

[0059] Therefore, the power control device according to the embodiment of the present invention uses a DC-DC converter 500 to control the output of the battery 110 separately from the output control of the PCS400. By causing the output power of the battery 110 to be output at peak power in the event of a power outage where the grid is not used, the control burden on the PCS400 can be reduced even when the load is operated without notification from the user.

[0060] Furthermore, the above-mentioned power control device can improve the efficiency of the energy storage system by preventing system shutdown due to excessive ripple voltage in the DC link section.

[0061] Figure 3 is a block diagram of a power control device according to an embodiment of the present invention.

[0062] Referring to Figure 3, the power control device according to an embodiment of the present invention can be provided as a component within the BCS200 in Figure 1, or as a separate, independent component.

[0063] According to the embodiment, the power control device can monitor the output power of the PCS400 and detect voltage changes in the DC link section due to the operation of the load 700.

[0064] Furthermore, the power control device can be connected to the DC-DC converter 500. This allows the power control device to control the DC-DC converter 500 so that the output power of the battery 110 is controlled in accordance with the voltage change of the DC link section.

[0065] On the other hand, the power control device may include memory M and a processor P.

[0066] According to the embodiment, memory M can consist of at least one of a volatile storage medium and a non-volatile storage medium. For example, memory M can consist of at least one of a read-only memory (ROM) and a random access memory (RAM).

[0067] Memory M may contain at least one instruction executed by processor P.

[0068] According to the embodiment, the at least one instruction includes the steps of: an instruction to detect the voltage of the DC link between the input side of the PCS and the output side of the converter; and an instruction to control the output power of the battery based on the output power of the PCS due to the voltage change of the DC link.

[0069] Here, the instruction to control the output power of the battery may include an instruction to control the output power of the battery by controlling the current of the battery.

[0070] Furthermore, the instruction for controlling the output power of the battery may include an instruction to control the battery so that it outputs at a predefined peak power value if the output power of the PCS exceeds a predefined rated power value of the battery.

[0071] In this case, the instruction to control the output to be at the peak power value may further include an instruction to compare the difference between the output power of the PCS and the output power of the battery if the peak power output period of the battery is longer than or equal to a predefined first period, and an instruction to control the battery to output at its rated power if the difference is less than a predefined threshold.

[0072] On the other hand, the instruction to control the output to the peak power value may further include an instruction to compare the difference between the output power of the PCS and the output power of the battery if the peak power output period of the battery is longer than or equal to a predefined first period, and an instruction to gradually control the battery to output at its rated power if the difference is greater than or equal to a predefined threshold.

[0073] Here, the instruction to control the output to occur in stages may include an instruction to control the output to occur by gradually decreasing the threshold power amount over a previously set second period, based on the peak power of the battery.

[0074] Furthermore, the instruction to control the output in stages may further include an instruction to control the battery to output at rated power if the peak power output period exceeds a predefined second period.

[0075] The following section will explain in detail the power control method based on the operation of the processor P of the power control device described above.

[0076] Figure 4 is a flowchart of a power control method according to an embodiment of the present invention.

[0077] Referring to Figure 4, the power control device according to an embodiment of the present invention can detect voltage changes in the DC link section (S1000). Here, the DC link section may be the region between the input side of the PCS400 and the output side of the DC-DC converter 500.

[0078] Voltage changes in the DC link section during a power outage can occur due to the output power of the battery 110 and the operating time of the load 700.

[0079] According to one embodiment, if the user temporarily operates the load 700 before the output power of the battery 110 decreases, a voltage change may occur in the DC link section.

[0080] According to another embodiment, if the user temporarily operates the load 700 after the output power of the battery 110 has decreased, a voltage change may occur in the DC link section.

[0081] As a result, the power control device can detect voltage changes in the DC link section by continuously monitoring the operating state of the load 700 and the output power of the battery 110.

[0082] In this case, the operating state of load 700 is controlled by user actions and is therefore difficult to predict in advance. On the other hand, PCS400 provides output power equal to the power consumption of load 700. Therefore, the power control device can monitor changes in the output power of PCS400 and detect changes in the operating state of load 700.

[0083] When a voltage change occurs in the DC link section, the power control device can compare the magnitude of the output power of the PCS400 and the output power of the battery 110. In other words, the power control device can compare the power consumption of the load 700 and the magnitude of the output power of the battery 110. Based on this, the power control device can use the DC-DC converter 500 to control the magnitude and speed of the output power of the battery 110 according to the comparison result (S5000). For example, the DC-DC converter 500 may be a bidirectional converter.

[0084] The method by which the power control device controls the magnitude and speed of the output power of the battery 110 through the DC-DC converter 500 will be described in more detail below.

[0085] Figure 5 is a flowchart illustrating the step of controlling the output power of a battery in a power control method according to an embodiment of the present invention.

[0086] Referring to Figure 5, the power control device according to an embodiment of the present invention can compare the output power of PCS400 with the output power of battery 110 (S5100).

[0087] According to one embodiment, when the output power value of the PCS400 is less than or equal to the output power value of the battery 110, it can be confirmed that the power consumption of the load 700 is reduced by user control. Therefore, the power control device can control the current amount of the DC-DC converter 500 (S5200) to rapidly reduce the output power of the battery 110 at a high speed relative to a predefined reference speed.

[0088] Figure 6 is a block diagram illustrating a power control method according to one embodiment of the present invention. Figure 7 is a graph showing the voltage change over time in the DC link section according to Figure 6.

[0089] Referring to Figures 6 and 7, if the power consumption of load 700 decreases, the output power of battery 110 becomes greater relative to the power consumption of load 700, which can cause a change in the voltage of the DC link section (section A in Figure 7).

[0090] Therefore, the power control device can rapidly reduce the output power of the battery 110 by using the DC-DC converter 500 to control the current flowing through the battery 110 at a high speed (section B in Figure 7). This stabilizes the voltage of the DC link section.

[0091] Referring again to Figure 5, in another embodiment, if the output power value of the PCS400 exceeds the output power value of the battery 110, the power control device can operate the DC-DC converter 500 to control the battery 110 to output at peak power in order to prepare for unexpected operation of the load 700 (S5300).

[0092] Generally, when the load 700 is powered on, it can temporarily consume peak power and then consume a predetermined rated power again. However, the timing of the load 700's operation is unpredictable. Therefore, the power control device according to an embodiment of the present invention can, when the output power of the battery 110 is lower than the output power of the PCS400, first control the battery 110 to operate at peak power for a predetermined period of time. Here, the peak power of the battery 110 may be the power provided by the battery 110 to support the output above the rated power that initially occurs temporarily when power is applied to the load 700. For example, the peak power may be 11 kW. However, because the load 700 is operated by user control, the power control device cannot predict the timing of the load's operation. Also, because the battery 110 has a limited charge capacity, it can only provide maximum peak power for a limited period of time.

[0093] In one embodiment, if the peak power output period of the battery 110 is less than a preset first period (P1) (S5400), the system returns to step S5100 and compares the output power of the PCS400 with the rated power of the battery 110 to continuously monitor the voltage change of the DC link section. For example, the first period (P1) may be 9.6 seconds.

[0094] On the other hand, in another embodiment, if the peak power output period of the battery 110 is equal to or greater than a preset first period (P1) (S5400), the power control device can compare the difference between the current output power of the PCS400 and the output power of the battery 110 with a preset threshold (S5500).

[0095] At this time, if the difference between the output power of PCS400 and the output power of battery 110 is less than a previously set threshold (S5500), the power control device can determine that PCS400 can provide stable power to load 700. As a result, the power control device can reduce the output power of battery 110 to its rated power through DC-DC converter 500 (S5600).

[0096] On the other hand, if the difference between the output power of PCS400 and the output power of battery 110 is greater than or equal to a previously set threshold (S5500), the power control device can determine that it is difficult to stably supply power to the load 700 with only the output power of PCS400. As a result, the power control device can reduce the control burden on PCS400 by gradually decreasing the output power rate of battery 110 using the DC-DC converter 500 (S5700).

[0097] Figure 8 is a flowchart illustrating the steps for controlling the output power of a battery in stages, which is part of a power control method according to an embodiment of the present invention. Figure 9 is a graph showing the control of the battery's output power over time, as shown in Figure 8.

[0098] Referring to Figures 8 and 9, if the difference between the output power of PCS400 and the output power of battery 110 is greater than or equal to a previously set threshold (S5500), the power control device can reduce the output power of battery 110 by a predefined threshold amount through the DC-DC converter 500 before outputting it (S5710). Here, the predefined threshold amount may be 100W.

[0099] Subsequently, the power control device can control the DC-DC converter 500 to maintain the output power of the battery 110 for a pre-set period (S5730). For example, the DC-DC converter 500 can maintain an output power state reduced by a threshold amount for 10ms.

[0100] In other words, the power control device, using the DC-DC converter 500, can gradually reduce the battery's output power by a predetermined threshold amount at predetermined intervals (using step logic).

[0101] Subsequently, the power control device can compare the peak power output period with a second period (P2) (S5750). Here, the second period (P2) may be the threshold period during which the battery's output power can be output at or above the rated power. For example, the second period (P2) may be 10 seconds.

[0102] According to one embodiment, when the peak power output period of the battery 110 is the second period (P2), the power control device can switch the output power of the battery 110 to the rated power (Max Continuous) using the DC-DC converter 500 (S5770). For example, the rated power of the battery 110 may be 7kW.

[0103] Here, the rated power can be preset to any one value within the rated power output range (see Figure 7(A)). In other words, the rated power output range can fall within the output power control range of the PCS400 for voltage stabilization of the DC link section. This allows the power control device to control the output power of the battery 110 by gradually reducing the threshold power through the DC-DC converter 500 until the second period (P2) is reached.

[0104] On the other hand, according to another embodiment, if the peak power output period of the battery 110 is the same as the second period (P2), the power control device can return to step S5100 and continuously monitor the voltage change of the DC link section by comparing the output power of the PCS400 with the output power of the battery.

[0105] Figure 10 is a block diagram illustrating a power control method according to another embodiment of the present invention. Figure 11 is a graph showing the voltage change over time in the DC link section according to Figure 10.

[0106] Referring to Figures 10 and 11, similar to step S5300 in Figure 5 described above, if the output power value of the battery 110 is smaller than the output power value of the PCS400, the power control device can control the DC-DC converter 500 to operate the battery 110 at peak power in preparation for unexpected operation of the load 700 by the user. Therefore, if the load 700 is operated by the user within the peak power output period of the battery 110, the battery 110 can stably supply power even to the temporary peak power consumption of the load 700.

[0107] On the other hand, the power control device can reduce the output speed to a speed lower than a predefined reference speed by gradually decreasing the output at peak power in preparation for the load 700 to be operated after the peak power output period of the battery 110. As a result, if the load 700 is operated within the second period (P2) after the peak power output period of the battery 110, the power control device can minimize voltage fluctuations in the DC link section (sections A and B in Figure 11) by ensuring that the output power of the battery 110 is output at or above the rated voltage.

[0108] The power control device and method according to embodiments of the present invention have been described above.

[0109] The power control device and method according to an embodiment of the present invention can prevent voltage fluctuations in the DC link section and stabilize the energy storage system by monitoring the output power of the PCS to detect voltage changes in the DC link section, comparing the output power of the PCS with the rated power of the battery, and controlling the output power of the battery.

[0110] The operation of the method according to an embodiment of the present invention can be embodied as a computer-readable program or code on a computer-readable recording medium. A computer-readable recording medium includes all types of recording devices that store data that can be read by a computer system. Furthermore, computer-readable recording media can be distributed across networked computer systems, allowing computer-readable programs or code to be stored and executed in a distributed manner.

[0111] Furthermore, computer-readable recording media can include hardware devices specially configured to store and execute program instructions, such as ROM, RAM, and flash memory. Program instructions can include not only machine code, such as that produced by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like.

[0112] Some aspects of the present invention have been described in the context of apparatus, but they can also be described by corresponding methods, where a block or apparatus corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method can be described by corresponding blocks or items or features of corresponding apparatus. Some or all of the method steps can be carried out by (or using) hardware devices such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important method steps can be carried out by such devices.

[0113] While preferred embodiments of the present invention have been described above with reference to the present invention, those skilled in the art will understand that the present invention can be modified and altered in various ways without departing from the spirit and scope of the invention as set forth in the following claims. [Explanation of symbols]

[0114] 100: BMS 200: BSC 300: PMS 400: PCS 500: DC-DC converter 600: Grid 700: Load M: Memory P: Processor

Claims

1. A power control device connected to a converter that performs DC-DC conversion between a battery and a power conversion system (PCS), which controls the output power of the battery, Memory and A processor that executes at least one instruction stored in the memory, The aforementioned at least one instruction, A command to detect the voltage of the DC link section between the input side of the PCS and the output side of the converter, and A power control device that includes a command to control the output power of the battery based on a comparison result between the output power of the PCS due to a voltage change in the DC link section and the output power of the battery.

2. The command to control the output power of the aforementioned battery is: The power control device according to claim 1, which includes an instruction to control the output power of the battery by controlling the current of the battery.

3. The command to control the output power of the aforementioned battery is: The power control device according to claim 1, which includes a command to control the battery so that it outputs at a predefined peak power value if the output power of the PCS exceeds the output power of the battery.

4. The instruction to control the output to be set to the aforementioned peak power value is: If the peak power output period of the battery is longer than or equal to a predefined first period, an instruction to compare the difference between the output power of the PCS and the output power of the battery, and The power control device according to claim 3, further comprising an instruction to control the battery so that it outputs at its rated power if the difference is less than a predefined threshold.

5. The instruction to control the output to be set to the aforementioned peak power value is: If the peak power output period of the battery is longer than or equal to a predefined first period, an instruction to compare the difference between the output power of the PCS and the output power of the battery, and The power control device according to claim 3, further comprising a command to control the battery in stages so that it outputs at its rated power if the difference is greater than or equal to a predefined threshold.

6. The instruction that controls the output to be generated in stages is: The power control device according to claim 5, which includes a command to control the output so that the threshold power amount is gradually reduced for a predetermined second period of time, based on the peak power of the battery.

7. The instruction that controls the output to be generated in stages is: The power control device according to claim 6, further comprising an instruction to control the battery to output at rated power if the peak power output period exceeds a predefined second period.

8. A power control method for a power control device connected to a converter that performs DC-DC conversion between a battery and a power conversion system (PCS) to control the output power of the battery, wherein A step of detecting the voltage of the DC link section between the input side of the PCS and the output side of the converter; and A power control method comprising the step of controlling the output power of the battery based on a comparison result between the output power of the PCS due to a voltage change in the DC link section and the output power of the battery.

9. The step of controlling the output power of the battery is: The power control method according to claim 8, further comprising the step of controlling the output power of the battery by controlling the current of the battery.

10. The step of controlling the output power of the battery is: The power control method according to claim 8, further comprising the step of controlling the battery so that it outputs at a predetermined peak power value if the output power of the PCS exceeds a predetermined rated power value of the battery.

11. The step of controlling the output to be set to the aforementioned peak power value is: If the peak power output period of the battery is longer than or equal to a first predetermined period, the step of comparing the difference between the output power of the PCS and the output power of the battery; and, The power control method according to claim 10, further comprising the step of controlling the battery to output at its rated power if the difference is less than a predefined threshold.

12. The step of controlling the output to be set to the aforementioned peak power value is: If the peak power output period of the battery is longer than or equal to a first predetermined period, the step of comparing the difference between the output power of the PCS and the output power of the battery; and, The power control method according to claim 10, further comprising the step of controlling the battery in stages so that it outputs at its rated power if the difference is greater than or equal to a predefined threshold.

13. The aforementioned step of controlling in stages is, The power control method according to claim 12, further comprising the step of controlling the output so that a threshold power amount is gradually reduced for a predetermined second period of time, based on the peak power of the battery.

14. The step of controlling the output to occur in stages is: The power control method according to claim 13, further comprising the step of controlling the battery to output at rated power if the peak power output period exceeds a second predetermined period.

15. Battery rack; A DC-DC converter that performs DC-DC conversion in conjunction with the aforementioned battery rack; The DC-DC converter and the power conversion system (PCS) connected to the load; and Includes a power control device connected to the DC-DC converter and controlling the operation of the DC-DC converter; The DC-DC converter is controlled by the power control device, An energy storage system that detects the voltage of the DC link between the input side of the output power of the PCS and the output side of the DC-DC converter, and controls the output power of the battery rack based on a comparison between the output power of the PCS due to the voltage change in the DC link and the output power of the battery rack.

16. The DC-DC converter is controlled by the power control device, The energy storage system according to claim 15, wherein the output power of the battery rack is controlled by controlling the current of the battery rack.

17. The DC-DC converter is controlled by the power control device, The energy storage system according to claim 15, wherein if the output power of the PCS exceeds a predefined rated power value of the battery rack, the battery rack outputs at a predefined peak power value.

18. The DC-DC converter is The energy storage system according to claim 17, wherein when the peak power output period of the battery rack is longer than or equal to a first predetermined period, if the difference between the output power of the PCS and the rated power of the battery rack is less than a predetermined threshold, the power control device controls the battery rack to output at its rated power.

19. The DC-DC converter is The energy storage system according to claim 17, wherein when the peak power output period of the battery rack is longer than or equal to a first predetermined period, if the difference between the output power of the PCS and the rated power of the battery rack is greater than or equal to a predetermined threshold, the power control device controls the battery rack in stages so that it outputs at its rated power.

20. The DC-DC converter is controlled by the power control device, The energy storage system according to claim 19, wherein the battery rack is controlled to output power by gradually decreasing the threshold power amount over a predetermined second period based on the peak power.

21. The DC-DC converter is controlled by the power control device, The energy storage system according to claim 20, wherein if the peak power output period exceeds a second predetermined period, the battery rack is controlled to output at rated power.

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