KR20200089056A - Energy storage system, power control device and power control method for energy cost reduction - Google Patents

Abstract

According to an embodiment of the present invention, provided are an energy storage system, a power control device and a power control method for energy cost reduction. According to one aspect of the present invention, the energy storage system, which is connected to a power grid supplying power to a load side, comprises: an energy storage device storing energy supplied from a power grid; a power conversion device transmitting power between the power grid and the energy storage device; and a power control device controlling the power transmission between the power grid and the energy storage device. The power control device generates a prediction profile which predicts power usage of a load, sets a target profile based on the prediction profile and the capacity of the energy storage device, and controls charge and discharge of the energy storage device in accordance with a determined charge and discharge profile based on a difference between the prediction profile and the target profile.

Description

Energy storage system, power control device and power control method to reduce energy cost{ENERGY STORAGE SYSTEM, POWER CONTROL DEVICE AND POWER CONTROL METHOD FOR ENERGY COST REDUCTION}

This embodiment relates to an energy storage system, a power control device, and a power control method. Specifically, this embodiment includes an energy storage device and a power control device and a power control method for controlling electric power charged and discharged by the energy storage device so as to reduce energy costs in an energy storage system connected to an electric power grid, and energy including the same It relates to a storage system.

With the development of the energy industry and national institutional changes, the introduction of new and renewable energy and the decentralization of the energy system, the introduction of energy storage systems including energy storage devices is gradually increasing.

Accordingly, there are increasing cases of introducing energy storage systems not only in factories or large-scale commercial facilities, but also in unit residential areas such as apartment complexes. This is also due to the increase in the introduction of new and renewable energy, but the role of the energy storage system stabilizes power supply and demand by supplying energy from the power grid and supplying it as a load due to changes in the energy price system such as hourly differential plans. And it is analyzed that it can also contribute to the reduction of power rates by adjusting the demand by time.

However, even if an energy storage system is introduced, the effect of reducing the power rate may not be significant by simply charging the energy storage device in the light load section and then discharging the power stored in the energy storage device in the maximum load section into the power grid. Therefore, there is a need to find an effective operation method to reduce the power charge by utilizing the energy storage system.

The present embodiment can provide an energy storage system capable of reducing energy costs, a power control device for controlling the energy storage system, and a power control method.

An aspect of the present embodiment for achieving the above object, an energy storage system connected to a power grid that supplies power to a load side, comprising: an energy storage device that stores energy supplied from the power grid; A power conversion device that transfers power between the power grid and the energy storage device; And a power control device that controls power transmission between the power grid and the energy storage device, wherein the power control device generates a prediction profile that predicts power consumption of the load, and the prediction profile and the energy storage device. It is an energy storage system, characterized in that a target profile is set based on the capacity of and the charge/discharge of the energy storage device is controlled according to a charge/discharge profile determined based on a difference between the prediction profile and the target profile.

In the energy storage system, the target profile may be determined by setting a maximum peak power as a target function in all sections including a light load section, a middle load section, and a maximum load section. Energy storage system, characterized in that.

In the energy storage system, the target profile may be determined by setting the sum of the basic rate constituting the power rate and the power rate as an objective function.

In the energy storage system, the charge/discharge profile may include discharge from the energy storage device to the power grid in an intermediate load section or a light load section.

In the energy storage system, the target profile may be set to generate a peak power greater than the maximum load section in the middle load or light load section.

In the energy storage system, the power control device detects the actual power supplied to the load, and when the detected actual power is largely different from the prediction profile, corrects the prediction profile in real time, and the modified prediction profile Accordingly, the target profile may be reset in real time.

In the energy storage system, the power control device may collect environmental data and load power consumption pattern information, and generate the prediction profile from the collected environmental data and load power consumption pattern information.

In the energy storage system, the environmental data may include weather data according to season, date, day of the week, and time.

Another aspect of the present invention, a power control method of an energy storage system connected to a power grid that includes an energy storage device and supplies power to a load side, comprising: collecting environmental data and load power consumption pattern information; Generating a prediction profile for power consumption from the environment data and the load power consumption pattern information; Setting a target profile based on the prediction profile; Determining a charge/discharge profile based on the prediction profile and the target profile; And controlling power charged and discharged by the energy storage device based on the charge/discharge profile.

In the power control method, setting the target profile may include setting a target function and optimizing the target function.

In the power control method, the target profile may be set in consideration of the capacity of the energy storage device.

In the power control method, the objective function may be set as the maximum peak power in all sections including the light load section, the middle load section, and the maximum load section.

In the power control method, the objective function may be set as a sum of a basic charge constituting a power charge and a power charge.

In the power control method, the charge/discharge profile may include discharge from the energy storage device to the power grid in an intermediate load section or a light load section.

In the power control method, the target profile may be set to generate a peak power greater than the maximum load section in the middle load or light load section.

Another aspect of the present invention, in a power control device for controlling an energy storage system connected to a power grid including an energy storage device and supplying power to a load side, a prediction for predicting the power consumption of the load Load profile prediction unit for generating a profile; A target profile setting unit for setting a target profile based on the prediction profile and the capacity of the energy storage device; And a power conversion device control unit for controlling charging and discharging of the energy storage device according to a charging and discharging profile determined based on a difference between the prediction profile and the target profile.

In the power control device, the target profile may be set through setting an objective function and optimizing the set objective function.

In the power control device, the objective function may be set as the maximum peak power in all sections including the light load section, the middle load section, and the maximum load section.

In the power control device, the objective function may be set as a sum of a basic charge constituting a power charge and a power charge.

In the power control device, the charge/discharge profile may include discharge from the energy storage device to the power grid in an intermediate load section or a light load section.

In the power control device, the target profile may be set to generate a peak power larger than the maximum load section in the middle load or light load section.

According to the present embodiment, it is possible to reduce energy costs by efficiently operating the charging and discharging of the energy storage device in the energy storage system that supplies power to the power grid using the energy storage device.

1 is a diagram showing a connection relationship between an energy storage system and a power grid and a load in this embodiment.
2 is a block diagram illustrating the configuration of an energy storage system according to the present embodiment.
3 is a block diagram illustrating a configuration of a power conversion device.
4 is a diagram schematically illustrating a circuit of a power conversion device.
5 is a block diagram schematically illustrating a power control device.
6 is a diagram illustrating a power consumption pattern of a load over time.
7 is a diagram illustrating a power control method according to a comparative example.
8 is a diagram schematically conceptually showing a peak portion of a power consumption pattern of a load.
9 is a diagram illustrating a case where the power control method of the comparative example is applied to the power consumption pattern of FIG. 8.
10 is a diagram illustrating a case where the power control method according to an embodiment of the present invention is applied to the power consumption pattern of FIG. 8.
11 is a diagram illustrating a case where the power control method according to an embodiment of the present invention is applied to the power consumption pattern of FIG. 8.
12 and 13 are views for examining the effects of the power control method in various situations.
14 is a diagram schematically illustrating a power control method according to an embodiment of the present invention.
15 is a block diagram illustrating the configuration of a power control device from a hardware perspective.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. It should be noted that in adding reference numerals to the components of each drawing, the same components have the same reference numerals as possible, even if they are displayed on different drawings. In addition, in describing the present invention, when it is determined that detailed descriptions of related well-known structures or functions may obscure the subject matter of the present invention, detailed descriptions thereof will be omitted.

In addition, in describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the component from other components, and the nature, order, or order of the component is not limited by the term. When a component is described as being "connected", "coupled" or "connected" to another component, that component may be directly connected to or connected to the other component, but another component between each component It should be understood that elements may be "connected", "coupled" or "connected".

1 is a diagram showing a connection relationship between an energy storage system and a power grid and a load in this embodiment.

Referring to FIG. 1, the energy storage system 100 may be connected to a power grid 10 that supplies power to a load 20. The power grid 10 may provide AC power to the load 20. The load 20 may be a factory, a commercial building, an apartment complex, or the like. The energy storage system 100 may be connected to the power grid 10 that supplies power to the load 20 to receive and store energy from the power grid 10 or to supply stored energy to the load 20.

2 is a block diagram illustrating the configuration of an energy storage system according to the present embodiment.

Referring to FIG. 2, the energy storage system 100 may include an energy storage device 110, a power conversion device 120, and a power control device 130.

The energy storage device 110 may store energy supplied from a power grid. For example, the energy storage device 110 may be a large-capacity battery, a secondary battery, or the like, but the embodiment is not limited thereto.

The power conversion device 120 may transfer power between the power grid and the energy storage device 110. Normally, since the power grid is alternating current and the energy storage device is direct current, the power conversion device 120 can convert the type (AC, direct current) and level of the voltage between the power grid and the energy storage device 110.

The power control device 130 may control power transmission between the power grid and the energy storage device 110 by controlling the power conversion device 120. For example, the power control device 130 may determine and control power charged from the power grid to the energy storage device 110 or power discharged from the energy storage device 110 to a load. Specifically, the power control device 130 generates a prediction profile predicting the power consumption of the load, sets a target profile based on the capacity of the prediction profile and the energy storage device 110, and the difference between the prediction profile and the target profile Charging and discharging of the energy storage device 110 may be controlled according to the charging and discharging profile determined based on the. A method of determining and controlling the charge/discharge power of the energy storage device 110 by the power control device 130 will be described in detail below.

3 is a block diagram illustrating a configuration of a power conversion device.

Referring to FIG. 3, the power converter 120 may include an AC circuit breaker 121, a filter capacitor 122, an inverter 123, a DC circuit breaker 124, and a control unit 125.

The AC circuit breaker 121 may be disposed between the power grid and the inverter 123 to perform a function of connecting or blocking the power grid and the inverter 123. The AC circuit breaker 121 may be a switch having a mechanical contact driven by a motor or a magnetic force.

The inverter 123 may include a plurality of switching elements, and may perform a function of converting and transferring power between a power grid and an energy storage device. The inverter 123 may use a pulse width modulation method for power conversion between the power grid and the energy storage device. The pulse width modulation method is a method of controlling power by adjusting an on/off time ratio of switching elements, and according to the pulse width modulation method, switching noise may be generated, so it is preferable to use a filter capacitor 122.

The DC circuit breaker 124 may be disposed between the energy storage device and the inverter 123 to perform a function of connecting or blocking the energy storage device and the inverter 123. The DC circuit breaker 124 may be a switch having a mechanical contact driven by a motor or a magnetic force.

The filter capacitor 122 may be connected to the AC side wiring of the inverter 123 to reduce switching noise generated during pulse width modulation of the inverter 123.

The control unit 125 may generate a signal for controlling a switching element (not shown) of the inverter 123. To this end, the controller 125 may control the inverter 123 to receive a command from the power control device and perform power conversion suitable for the command from the power control device. The command received by the control unit 125 from the power control device may include charge/discharge power information of the energy storage device. In addition, the control unit 125 may control the AC circuit breaker 121 and the DC circuit breaker 124 to turn on/off the operation of the power converter 120.

4 is a diagram schematically illustrating a circuit of a power conversion device.

Referring to FIG. 4, the power converter 120 includes an AC circuit breaker 121, a filter capacitor 122, an inverter 123, a DC circuit breaker 124, a control unit 125, a filter inductor 126, and a DC link capacitor It may include (127). In Figure 4, the power grid is illustrated as a three-phase AC voltage, and the energy storage device is illustrated as a DC voltage.

The AC circuit breaker 121 may be disposed between the power grid and the inverter 123 to perform a function of connecting or blocking the power grid and the inverter 123. The AC circuit breaker 121 may be a switch having a mechanical contact, and the mechanical contact may be driven by a magnetic field or may be driven by a motor.

Inverter 123 may include six switching elements to convert power between the energy storage device and the power grid. Each switching element may be provided with a plurality of switching elements in series and/or in parallel (not shown). In the case of a large-capacity power conversion device, a plurality of inverters 123 may be provided to operate in parallel. Each switching element of the inverter 123 performs on/off switching according to the control signal of the control unit 125, and it is possible to adjust the power transmitted between the energy storage device and the power grid by a pulse width modulation method.

The DC circuit breaker 124 may be disposed between the energy storage device and the inverter 123 to perform a function of connecting or blocking the energy storage device and the inverter 123. The DC circuit breaker 124 may be a switch having a mechanical contact, and the mechanical contact may be driven by a magnetic field or may be driven by a motor. In FIG. 4, the DC circuit breakers 124 are illustrated as being provided on two DC wirings, respectively, but may be provided on only one wiring.

The filter capacitor 122 is connected between the AC-side wirings of the inverter 123 to reduce switching noise generated during pulse width modulation of the inverter 123. In order to be connected to the three-phase system, the filter capacitor 122 may be connected to three capacitors in parallel between the lines of the three-phase power system, but is not limited thereto. Each capacitor may be provided with a plurality of capacitors in series and/or in parallel (not shown).

The filter inductor 126 may be connected to the AC-side wiring of the inverter 123 in series. The filter inductor 126 may reduce switching noise due to the switching operation of the inverter 123.

The DC link capacitor 127 may be connected between DC wires of the inverter 123 to stabilize the power supplied from the energy storage device and supply it to the inverter 123.

5 is a block diagram illustrating the configuration of a power control device.

Referring to FIG. 5, the power control device 130 may include a load profile prediction unit 131, a target profile setting unit 132, and a power conversion device control unit 133.

The load profile prediction unit 131 may generate a prediction profile that predicts power usage of the load. The load profile prediction unit 131 may collect environment data and load power consumption pattern information, and generate a prediction profile from the collected environment data and load power consumption pattern information. For example, the environment data may include weather data according to season, date, day, and time.

The target profile setting unit 132 may set the target profile based on the prediction profile generated by the load profile prediction unit 131 and the available capacity of the energy storage device (hereinafter simply referred to as'capacity'). Since the energy storage device has a limited capacity, the target profile needs to be set to effectively use the limited capacity of the energy storage device. To this end, the target profile can be determined by setting an appropriate objective function and optimizing the objective function.

For example, the target profile may be determined by setting the peak power in the entire section including the light load section, the middle load section, and the maximum load section as the objective function. Exemplarily, the target profile may be determined by setting the sum of the basic rate constituting the power rate and the power rate as the objective function. In this case, the target profile may be set to generate a peak power greater than the maximum load section in the middle load or light load section. The setting of the target profile will be described in detail below.

The power converter control unit 133 may control charging and discharging of the energy storage device according to the charging and discharging profile determined based on the difference between the prediction profile and the target profile. The charge/discharge profile may include discharge from the energy storage device to the power grid in the maximum load section, as well as discharge from the energy storage device to the power grid in the middle load section or the light load section.

The power control device 130 detects the actual power supplied to the load, and if the detected actual power is largely different from the prediction profile, the power control device 130 may modify the prediction profile in real time and reset the target profile according to the modified prediction profile. .

6 is a diagram illustrating a power consumption pattern of a load over time.

In FIG. 6, the X-axis is time and the Y-axis represents power consumption (kW) of the load over time. 24 hours a day can be divided into three sections (light load section, middle load section, maximum load section). Illustratively, the light load section is a section marked with'A' and may include 0 to 9 hours and 23 to 24 hours section, and the middle load section is a section marked with'B' from 10 to 12 hours, It can include the period from 16:00 to 20:00 and 22:00 to 23:00, and the maximum load section is the section marked with'C', which includes the section from 9 to 10, 12 to 16, and 20 to 22. Can. The division of the section according to the above time is only an example, and the present embodiment is not limited thereto.

The power consumption of the load may tend to increase in power consumption in the order of light load section, middle load section, and maximum load section. However, peaks may also occur temporarily in the light load section and/or the intermediate load section. Illustratively, peaks 602, 603, and 605 frequently occur in the maximum load section and may be large in size, but a significant level of peak 601 may also occur in the light load section. In particular, the peak 604 occurring in the mid-load section may occur at a greater level than some of the peaks 602 and 603 occurring in the full-load section, and often the peak 604 of the mid-load section is the maximum load section. It may be close to the maximum peak 605 that occurs. As such, peaks in the light load and/or middle load sections may occur at levels close to the maximum peaks occurring in the maximum load section. The present inventors recognize the fact that when operating an energy storage system without sufficiently considering such a situation, attempts to reduce the power rate using an energy storage device may recognize that the present embodiments may not be sufficiently effective. Was done.

7 is a view for explaining a power control method as a comparative example compared to the present embodiment. The power consumption pattern of the general load will have a complicated shape as illustrated in FIG. 6, but FIG. 7 simplifies and shows the power consumption pattern of the load for convenience of explanation. 7 assumes that peaks are generated once in each of the light load section, the middle load section, and the maximum load section, and the Y axis enlarges power consumption in the vicinity of the peak.

For example, it is assumed that a peak of P1 occurs at t1 in a light load section, a peak of P2 occurs at t2 in a middle load section, and a peak of P3 occurs in a maximum load section. At this time, the relationship of P1 <P2 <P3 can be established.

As a comparative example compared to the embodiment of the present invention, a method of charging the energy storage device in the light load section and discharging the energy storage device in the maximum load section may be considered. When the capacity of the energy storage device is We, the entire capacity of the energy storage device We is discharged at t3 in the maximum load section, and the amount of power Wec discharged in the maximum load section is equal to the capacity of the energy storage device We. It can be the same. That is, the entire capacity of the energy storage device We can be used to lower the peak of the maximum load section from P3 to P3a. In this case, the maximum peak in the entire section is changed from P3 to P3a and the maximum peak reduction amount (ΔPpk) can be calculated as (P3-P3a). The maximum peak reduction (ΔPpk) can be an important factor in determining power rates.

In the case of Figure 7, the capacity of the energy storage device (We) were all used to lower the peak P3 in the maximum load section, as a result, the maximum peak is P3a still higher than the peak P2 in the middle load section and the peak P1 in the light load section Due to its size, there may be no problem in terms of efficient use of the energy storage device.

However, assuming the case of FIG. 8, it can be seen that the method of the comparative example is not efficient in terms of efficient utilization of the energy storage device. 8 illustrates a case where the peak P2 in the middle load section does not differ significantly from the peak P3 in the maximum load section. When the method of the comparative example is applied to the case of FIG. 8, the same situation as in FIG. 9 may occur.

Referring to FIG. 9, when the entire capacity We of the energy storage device is used in the maximum load section and the peak P3 is lowered to P3a, the peak P2 in the middle load section may be higher than the peak P3a in the maximum load section. In this case, the maximum peak reduction amount (ΔPpk) becomes (P3-P2) instead of (P3-P3a), and thus the maximum peak reduction amount (ΔPpk) may be reduced compared to the case of FIG. 7. In the hourly differential plan, the power rate is greatly affected by the maximum peak reduction amount (△Ppk).If the maximum peak reduction amount (△Ppk) is reduced, the amount of reduction in the power rate decreases, and the effect of using the energy storage device can be halved. have.

As such, the method of the comparative example of simply charging the energy storage device in a light load section and discharging the energy storage device in a maximum load section is not efficient from the viewpoint of reducing power rates.

10 is a diagram illustrating a case where the power control method according to an embodiment of the present invention is applied to the power consumption pattern of FIG. 8.

In the power control method according to an embodiment of the present invention, the maximum peak power in the entire section including the light load section, the middle load section and the maximum load section is set as a target function and the target profile is set so that the maximum peak power is minimum. Can be set.

When the power control method according to the present embodiment is applied to the power consumption pattern (prediction profile) of FIG. 8, a target profile as shown in FIG. 10 may be set. That is, both the peak P3 of the maximum load section and the peak P2 of the intermediate load section can be lowered to the peak P3b. To this end, the capacity (We) of the energy storage device can be divided into discharge energy (Web) in the middle load section and discharge energy (Wec) in the maximum load section, and can minimize the maximum peak power in the entire section. . That is, when the peak in the middle load or light load section approaches the peak in the maximum load section, discharge from the energy storage device to the power grid may occur even in the middle load section or the light load section. According to the method of the present embodiment, the maximum peak reduction amount (ΔPpk) may be maximized, and thus it may be advantageous in comparison with the method of the comparative example in terms of power rates.

11 is a diagram illustrating a case where a power control method according to another embodiment of the present invention is applied to the power consumption pattern of FIG. 8.

In the power control method according to the present embodiment, the sum of the basic charge constituting the power charge and the power charge can be set as an objective function, and a target profile can be set such that this objective function is minimized.

When the power control method according to the present embodiment is applied to the power consumption pattern (prediction profile) of FIG. 8, a target profile as shown in FIG. 11 may be set. The capacity of the energy storage device We is similar to that of FIG. 10 in that it can be divided into discharge energy (Web) in the middle load section and discharge energy (Wec) in the maximum load section, but in the case of the present embodiment, the intermediate load The target peak P2a in the section may be set larger than the target peak P3c in the maximum load section. That is, in the power control method according to the present embodiment, the goal is not to minimize the maximum peak in the entire section, but the discharge energy in the middle load section (Web) and the discharge energy in the maximum load section (Wec) in order to minimize the power charge. By distributing, the target profile can be set so that the maximum peak P2a occurs in the middle load section.

Hereinafter, advantages of the present exemplary embodiments will be described by analyzing power rates according to the aforementioned power control method.

According to the differential rate plan for each time zone, the power rate EC may be determined as the sum of the basic rate BC and the power rate rate WC as shown in Equation 1 below. The basic charge (BC) is calculated as the product of the maximum peak power (Ppk; unit kW) and the basic rate (BR; unit won/kW), as shown in Equation 2, and the power rate charge (WC) is light load as shown in Equation 3. It is divided into section (A), middle load section (B) and maximum load section (C), and the power rate (Ra, Rb, Rc; unit of Won/kWh) for each section and the amount of power used for each section (Wa, Wb, Wc) ; Unit kWh).

[Equation 1]

Power Charges (EC) = Basic Charges (BC) + Power Charges (WC)

[Equation 2]

Base Rate (BC) = Maximum Peak Power (Ppk) · Base Rate (BR)

[Equation 3]

Power rate (WC) = WaRa + WbRb + WcRc

Here, Wa is the amount of power used in the light load section (A), Wb is the amount of power used in the intermediate load section (B), and Wc is the amount of power used in the maximum load section (C). Ra is the power rate in the light load section (A), Rb is the power rate in the middle load section (B), and Rc is the power rate in the maximum load section (C). In the hourly differential plan, in order to reduce the power consumption in the maximum load section, the power rate rate (Ra) in the maximum load section is the highest, then the power rate rate (Rb) in the middle load section is highest, and the power rate rate in the light load section (Ra) may be set to the lowest.

When the above Equations 1 to 3 are rearranged again, the power rate EC may be arranged as in Equation 4 below.

[Equation 4]

EC = Ppk·BR + (Wa·Ra + Wb·Rb + Wc·Rc)

In order to determine whether to use the energy storage device efficiently from the viewpoint of the power rate, the respective methods of FIGS. 9, 10 and 11 are used based on the power rate in the case of FIG. 8 (before using the energy storage device). Let's compare the difference in power rates in the case (after using the energy storage device).

First, in the case of FIG. 8 (before using the energy storage device), the power rate (EC8) and in the case of FIG. 9 (discharge at the maximum load section), the power rates (EC9) are as shown in Equations 5 and 6, respectively. Can be calculated.

[Equation 5]

EC8 = P3·BR + (Wa·Ra + Wb·Rb + Wc·Rc)

[Equation 6]

EC9 = P2BR + ((Wa+We)·Ra + Wb·Rb + (Wc-We)·Rc)

Here, We is the capacity of the energy storage device. 9, it is assumed that the entire capacity We of the energy storage device is discharged in the maximum load section. That is, in Equation 6, the energy storage device charges the entire capacity (We) of the energy storage device in the light load section (A) and discharges all of the energy in the maximum load section to lower the maximum peak in the maximum load section from P3 to P3a. It is the case. The difference in power rates in the case of FIGS. 8 and 9 may be calculated as shown in Equation 7 below.

[Equation 7]

EC8-EC9 = (P3-P2)BR + We·(Rc-Ra)

(EC8-EC9) calculated in Equation 7 may be understood as a reduced power rate when the energy storage device is used by the method illustrated in FIG. 9. That is, when the energy storage device is used only for the peak reduction in the maximum load section, the cost of charging the energy storage device in the light load section (We·Ra) occurs, but it is basic by the maximum peak reduction amount (△Ppk=P3-P2). Charges are reduced ((P3-P2)·BR), and power charge reduction (We·Rc) may occur due to reduced power consumption in the maximum load section. Since the power rate rate Rc in the maximum load section is larger than the power rate rate Ra in the light load section, the overall power rate may be reduced.

Next, as illustrated in FIG. 10, when the power rate (EC10) in the case of using a method of reducing the maximum peak power in all the sections including the intermediate load section is obtained, it can be calculated as in Equation 8 below.

[Equation 8]

EC10 = P3b·BR + ((Wa+We)·Ra + (Wb-Web)·Rb + (Wc-Wec)·Rc)

Here, We is the capacity of the energy storage device, Web is the amount of power discharged by the energy storage device in the intermediate load section B, and Wec is the amount of power discharged by the energy storage device in the maximum load section C. Therefore, the relationship of We = Web + Wec is established.

Equation (8) shows that the energy storage device charges the entire capacity (We) of the energy storage device in the light load section (A), and divides and discharges it in the middle load section and the maximum load section. When lowered to.

The difference between the power rates in the case of FIG. 8 (Equation 5) and the case of FIG. 10 (Equation 8) is obtained as shown in Equation 9 below.

[Equation 9]

EC8-EC10 = (P3-P3b)·BR-We·Ra + Web·Rb + Wec·Rc

If Equation 9 is modified using the relationship of We = Web + Wec, it can be expressed as Equation 10 below.

[Equation 10]

EC8-EC10 = (P3-P3b)·BR + We·(Rc-Ra)-Web·(Rc-Rb)

Referring to Equation (10), the'-Web·(Rc-Rb)' item is generated in the electricity rate item, which is relatively damaged in the electricity rate compared to the discharge in the maximum load section when discharge occurs in the middle load section. This item explains that (relatively, the cost reduction is reduced).

The method of FIG. 9 and the method of FIG. 10 are compared from the viewpoint of power rates through Equations 7 and 10.

In the case of the method of Figure 9, as can be seen through the equation (7), since the capacity of the energy storage device (We) was all input in the maximum load section, the difference in the power rate between the time of charging and discharging the energy storage device ( Rc -Ra) becomes the maximum, so it is the best in the electricity rate item, but since the peak in the mid-load section did not decrease, the decrease in the maximum peak (△Ppk) is not large as P3-P2, so it may not be desirable in the basic rate item. . That is, although the method illustrated in FIG. 9 is a method of optimizing the amount of electricity among the electricity rates, it is difficult to consider the optimization of the overall electricity rate. Particularly, the problem may be more prominent when a maximum peak is generated in the middle load section or the light load section, or when a larger peak occurs.

In the case of the method of FIG. 10, as can be seen through Equation (10), the maximum peak is lowered by distributing the capacity (We) of the energy storage device between the intermediate load section and the maximum load section. Due to this, the maximum peak reduction (△Ppk) is maximized to P3-P3b, so the reduction of the basic rate is the greatest, but due to the occurrence of discharge even in the middle load section, the amount of power is generated by the'-Web·(Rc-Rb)' item. The amount of cost savings in the rate can be reduced. That is, the method illustrated in FIG. 10 is a method of optimizing a basic rate among power rates, but may not be an optimization of the total power rate because the degree of reduction in the power rate is relatively reduced.

However, the method of FIG. 10 has a greater effect than the method of FIG. 9 when the peak of the middle load or light load section is close to or larger than the maximum peak of the maximum load section, and the peak of the middle load or light load section is maximum. When the difference is small compared to the maximum peak of the load section, it has an effect of reducing the power rate compared to the method of FIG. 9 in that it provides results similar to the method of FIG. 9. In particular, when the peak in the middle load section is large and its width (time) is short, the method of FIG. 10 may exhibit a better effect than the method of FIG. 9.

As described above, the method of FIG. 10 has an advantage in terms of power rates compared to the method of FIG. 9, but the method of FIG. 10 is a method of optimizing the basic rate, which is one of two items constituting the power rate, and has two objective functions. The method of FIG. 10 may not be an optimization of the total power rate in that the optimization of each item is often not the optimization of the entire objective function when it is composed of the sum of the items.

As described above, the power control method illustrated through FIG. 11 is a method of setting a sum of a basic rate constituting a power rate and a power rate as an objective function and setting a target profile so that this objective function is minimized.

When calculating the power rate for the case of Figure 11 is as shown in equation (11) below.

[Equation 11]

EC11 = P2a·BR + ((Wa+We)·Ra + (Wb-Web)·Rb + (Wc-Wec)·Rc)

When calculating the power rate gain in the case of FIG. 11, it is as shown in Equation 12 below.

[Equation 12]

EC8-EC11 = (P3-P2a)·BR + We·(Rc-Ra)-Web·(Rc-Rb)

Minimizing the power rate of Equation 11 can be understood as maximizing the power rate gain of Equation 12. Referring to Equation (12), as the discharge amount (Web) increases in the middle load section, the gain in terms of the electricity rate decreases, but the peak P2a in the middle load decreases, so the gain in the basic charge aspect may increase. In the method of this embodiment, considering the above two items, the discharge amount (Web, Wec) in each section can be set so that the total power charge is minimized. To this end, the sum of the basic charge constituting the power charge and the power charge can be set as the objective function and the discharge amount (Web, Wec) in each section can be determined from the viewpoint of minimizing the objective function.

Next, as shown in FIG. 8, when the peak power P2 in the middle load section does not differ significantly from the peak power P3 in the maximum load section, it is illustrated in FIG. 11 when the power rate is used as the objective function As described above, it will be described that the target profile can be set to generate the maximum peak in the middle load section.

First, with reference to FIG. 12, a case in which the width of the peak in the middle load section is relatively wide compared to the width of the peak in the maximum load section will be described. In this case, it may be desirable to input most of the capacity We of the energy storage device in the maximum load section. This is because even if a part of the capacity of the energy storage device We is input to the intermediate load section, the peak reduction amount of the intermediate load section is small because the peak width of the intermediate load section is wide. If the width of the peak in the middle load section is extremely wide, even if power is applied to the middle load section, the peak in the middle load section cannot be lowered, so there is no benefit from the basic charge, so the capacity (We) of all energy storage devices is reduced. It may be desirable to generate a gain from the electricity bill by putting it in the maximum load section.

Next, a case where the width of the peak in the middle load section is relatively narrow compared to the width of the peak in the maximum load section will be described with reference to FIG. 13. In this case, it may be desirable to inject some of the energy storage device capacity We into the intermediate load section so that the peak of the intermediate load section is the same as the peak P3e of the maximum load section. This is because the peak in the middle load section can be effectively reduced even with a small amount of power input, so the gain in the basic rate is greater than the loss in the power rate. However, it is not desirable to apply power to the intermediate load section so that the peak of the intermediate load section is lower than the peak P3e of the maximum load section. This is because, even if the peak in the middle load section is lower than the peak (P3e) in the maximum load section, only the damage in the electricity rate occurs without additional reduction in the basic charge.

When the peak width of the mid-load section is extremely wide, maintaining the peak power of the mid-load at P2 (not lowering the peak of the mid-load section) is most advantageous in terms of power rates (see FIG. 12), and the mid-load When the width of the peak of the section is extremely narrow, it may be most advantageous in terms of power rate to lower the peak power of the intermediate load equal to the peak of the peak load section (see FIG. 13 ). Therefore, it can be seen that when the width of the peak in the middle load section is a general degree, it may be most advantageous in terms of power rates to lower the peak in the middle load section to a certain extent, but to keep it higher than the peak in the maximum load section.

In this way, the optimization of the power rate is the midpoint (P2a) of the target peak power of the mid-load section P2 (if the peak is not reduced in the mid-load section) and P3b (if the maximum peak in the entire section is minimized) It can be achieved when set in (see Fig. 11). From another point of view, it can be understood that the optimization of the power rate can be achieved when the target peak power P2a in the middle load section is relatively larger than the target peak power P3c in the maximum load section. The difference between the target peak (P2a) in the middle load section and the target peak (P3c) in the maximum load section is the relative ratio of the width of the peak in the middle load section to the peak width in the maximum load section, the power rate and basic rate for each section, It may vary depending on the capacity (We) of the energy storage device.

Although the power control method of the present embodiment has been described through the simplified drawings and formulas, the actual target profile may be set through a more complicated calculation. For example, when a prediction profile predicting a power pattern of a load is generated, the capacity of the energy storage device is input according to the capacity We of the energy storage device and the shape of the prediction profile (number, size, width of peak power, etc.) That is, the target profile may be set while peaks to be discharged) of the energy storage device are determined. At this time, as described above, a method of lowering the maximum peak in the entire section (see FIG. 10) may be used, or a method of minimizing power charges (see FIG. 11) may be used. When using a method of minimizing the power rate, as described with reference to FIG. 11, the distribution of the amount of power input to each section may vary according to the relative width and size of the peak in each section. Accordingly, the maximum peak of the target profile may be set to occur in the middle load section or the light load section, not the maximum load section, while putting a portion of the capacity of the energy storage device in order to lower the peak in the middle load or light load section.

14 is a diagram schematically illustrating a power control method according to an embodiment of the present invention. The power control method of this embodiment may be performed by the above-described power control device.

In step S1401, the power control device may collect environmental data and load power consumption pattern information. The environmental data may include weather data according to season, date, day and time.

In step S1403, the power control device may generate a prediction profile for load power consumption from the collected environmental data and load power consumption pattern information. In this embodiment, since the power rate can be set as a target function in one way and a target profile can be generated for its optimization, the prediction profile may include enough information to calculate the power charge. For example, the prediction profile may include information on patterns (size and width, etc.) of peaks in a light load section, a middle load section, and a maximum load section, and information on the amount of power in each section.

In step S1405, the power control device may set the objective function. The objective function may be set as the maximum peak power in all sections including the light load section, the middle load section, and the maximum load section, or may be set as a sum of basic charges and power charges constituting the power charge.

In step S1407, the power control device may set a target profile based on the prediction profile. For example, the target profile may be set to optimize the objective function set in step S1405 in consideration of the capacity of the energy storage device. When the objective function is set as the sum of the basic fee constituting the electricity rate and the electricity rate, as described above, the target profile is set to generate a peak power greater than the maximum load section in the middle load or light load section, depending on the situation. Can be.

In step S1409, the power control device may determine the charge/discharge profile based on the prediction profile and the target profile. The charge/discharge profile may include discharge from the energy storage device to the power grid in the middle load section or the light load section.

In step S1411, the power control device may control power charged and discharged to the energy storage device based on the charge/discharge profile. To this end, the power control device may transmit information on charge/discharge power of the energy storage device to the power conversion device.

15 is a block diagram illustrating a configuration of a power control device from a hardware perspective. Referring to FIG. 15, the power control device 1530 may include an input unit 1531, a processor 1532, and a memory 1533. A program 1534 for operating the power control device may be stored in the memory 1533.

The input unit 1531 may be a means for receiving past power usage data of the load and past and present environmental data.

The memory 1533 may store a program 1534 that performs the above-described power control method.

The program 1534 can be driven through at least one processor 1532. The program 1534 may include instructions for performing the operations of the power control device 1530 described above. Illustratively, the program 1534 generates a prediction profile that predicts the power usage of the load, sets a target profile based on the prediction profile and the capacity of the energy storage device, and determines based on the difference between the prediction profile and the target profile It may include a command for controlling the charge and discharge of the energy storage device according to the charge and discharge profile.

Meanwhile, some of the embodiments of the present invention may be embodied as computer readable codes on a computer readable recording medium. The computer-readable recording medium may include any kind of recording device in which data readable by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tapes, floppy disks, optical data storage devices, etc., and also implemented in the form of carrier waves (for example, transmission via the Internet). Includes. In addition, the computer-readable recording medium can be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. And functional programs, codes, and code segments for implementing the present invention can be easily inferred by programmers in the technical field to which the present invention pertains.

The terms "comprise", "compose" or "have" as described above mean that the component can be inherent, unless otherwise stated, and do not exclude other components. It should be interpreted that it may further include other components. All terms, including technical or scientific terms, have the same meaning as generally understood by a person skilled in the art to which the present invention belongs, unless otherwise defined. Commonly used terms, such as predefined terms, should be interpreted as being consistent with the meaning of the context of the related art, and are not to be interpreted as ideal or excessively formal meanings unless explicitly defined in the present invention.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the claims below, and all technical spirits within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

Claims (21)

In the energy storage system connected to the power grid to supply power to the load (load) side,
An energy storage device that stores energy supplied from a power grid;
A power conversion device that transfers power between the power grid and the energy storage device; And
It includes; a power control device for controlling the power transfer between the power grid and the energy storage device;
The power control device generates a prediction profile predicting the power consumption of the load, sets a target profile based on the capacity of the prediction profile and the energy storage device, and based on a difference between the prediction profile and the target profile Energy storage system characterized in that for controlling the charge and discharge of the energy storage device according to the determined charge and discharge profile. The method according to claim 1,
The target profile is determined by setting the maximum peak power as a target function in all sections including the light load section, the middle load section and the maximum load section. The method according to claim 1,
The target profile is an energy storage system characterized in that it is determined by setting the sum of the basic charges and the amount of electricity charges constituting the electricity rate as an objective function. The method according to claim 3,
The charging and discharging profile is characterized in that it comprises a discharge from the energy storage device to the power grid in the middle load section or light load section. The method according to claim 4,
The target profile is an energy storage system characterized in that it is set to generate a peak power greater than the maximum load section in the middle load or light load section. The method according to claim 1,
The power control device detects the actual power supplied to the load, and if the detected actual power is largely different from the prediction profile, corrects the prediction profile in real time and real-time the target profile according to the modified prediction profile. Energy storage system, characterized in that to reset. The method according to claim 1,
The power control device collects environmental data and power consumption pattern information of the load, and the energy storage system, characterized in that for generating the prediction profile from the collected environmental data and power consumption pattern information of the load. The method according to claim 7,
The environment data is energy storage system, characterized in that it comprises weather data according to the season, date, day and time. A power control method of an energy storage system including an energy storage device and connected to a power grid supplying power to a load side,
Collecting environmental data and load power consumption pattern information;
Generating a prediction profile for power consumption from the environment data and the load power consumption pattern information;
Setting a target profile based on the prediction profile;
Determining a charge/discharge profile based on the prediction profile and the target profile;
Controlling power charged and discharged to an energy storage device based on the charge/discharge profile;
Power control method comprising a. The method according to claim 9,
The step of setting the target profile includes setting a target function and optimizing the target function. The method according to claim 9,
The target profile is a power control method characterized in that it is set in consideration of the capacity of the energy storage device. The method according to claim 10,
The objective function is a power control method characterized in that it is set to the maximum peak power in all sections including the light load section, the intermediate load section and the maximum load section. The method according to claim 10,
The objective function is a power control method characterized in that it is set to the sum of the basic charge constituting the power charge and the power charge. The method according to claim 13,
The charging/discharging profile includes a discharge from the energy storage device to the power grid in an intermediate load section or a light load section. The method according to claim 9,
The target profile is a power control method characterized in that it is set to generate a peak power greater than the maximum load section in the middle load or light load section. A power control device for controlling an energy storage system connected to a power grid that includes an energy storage device and supplies power to a load side,
A load profile prediction unit generating a prediction profile for predicting the power consumption of the load;
A target profile setting unit for setting a target profile based on the prediction profile and the capacity of the energy storage device; And
A power conversion device control unit controlling charging/discharging of the energy storage device according to a charging/discharging profile determined based on a difference between the prediction profile and the target profile;
Power control device comprising a. The method according to claim 16,
The target profile is a power control device, characterized in that is set by setting the target function and optimizing the set target function. The method according to claim 17,
The target function is a power control device characterized in that it is set to the maximum peak power in the entire section including the light load section, the intermediate load section and the maximum load section. The method according to claim 17,
The objective function is a power control device, characterized in that it is set as the sum of the basic charge constituting the power charge and the power charge. The method according to claim 16,
The charge/discharge profile comprises a discharge from the energy storage device to the power grid in an intermediate load section or a light load section. The method according to claim 16,
The target profile is a power control device characterized in that it is set to generate a peak power greater than the maximum load section in the middle load or light load section.

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