KR101712944B1 - Apparatus and method for charge and discharge scheduling in energy storage device - Google Patents

Abstract

The present invention relates to an apparatus and method for charge and discharge scheduling of an energy storage device, and a charging / discharging scheduling method of an energy storage device connected to a power network and supplying power to a load side, By establishing a charge-discharge scheduling plan that takes into account changes in electricity rates according to time series, load pattern data, and internal chemical characteristics of energy storage devices under conditions where the allowable limit output is set and the power drawn from the grid has a value within the set range, It is possible to operate the grid in a planned and stable manner with minimal cost.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for scheduling charging and discharging of an energy storage device,

The present invention relates to an apparatus and method for charge / discharge scheduling of an energy storage device, and more particularly, to a system and method for scheduling charging / discharging of an energy storage device, in consideration of cost of a power network, load profile data, And more particularly, to an apparatus and method for charging / discharging an energy storage device capable of optimizing operating costs.

Energy storage devices are gaining importance as a key component in next generation power supply networks such as distributed power and smart grid environment. Recently, research on new and renewable energy such as solar power, solar heat, wind power, and bio has progressed actively But also as a device for storing renewable energy. The energy storage device is a secondary battery that can be charged and discharged many times, but since its lifetime is determined, it is necessary to schedule charging and discharging efficiently in accordance with the usage environment and purpose.

Energy storage devices are mainly used in data center and electric car fields. Data centers require a tremendous amount of power to maintain constant temperature and humidity, and must be prepared for emergency power outages. Thus, a power management system that can supply power independently for emergency power outages is being used while supplementing the enormous amount of power consumed for cooling electronic equipment through the energy storage device. In this case, as long as the energy storage device stores sufficient energy, it is possible to achieve the purpose of using the energy storage device. In the field of electric vehicles, rapid charging is essential due to the characteristics of a moving means such as an automobile, and an energy storage device is used for supplying electric power stably to an electric vehicle. In this regard, the energy storage device mainly includes an invention relating to a charging method and a charger hardware capable of efficiently charging in a short time, and an invention for reliably measuring the state of charge (SOC) remaining in the energy storage device ought.

In addition, in the field of supplying electric power required for an industrial or household consuming entity connected to a power grid, the energy storage device is supplementarily used depending on the difference characteristic of the electric power charge by time to schedule its charge and discharge. However, it has limitations in that it can not consider the internal chemical characteristics of the energy storage device in terms of the operation cost of supplying electric power in connection with the power network, which ultimately leads to a burden on the consumers because the energy storage device is not cost- The problem may arise.

In addition, when energy storage devices are used in a distributed power supply utilizing renewable energy, the energy storage device's internal chemical characteristics are reflected, and the charge / discharge scheduling of the energy storage device Is required.

Korean Patent Publication No. 10-2013-0074046, open

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a charging / discharging scheduling apparatus for an energy storage device, In order to solve the problem that the power supply can not be supplied at the minimum cost because the internal chemical characteristics and the demand reaction signal of the energy storage device are not taken into account in the cost of the power supply, And to overcome the drawback that there is no consideration for the set maximum permissible power output.

According to an aspect of the present invention, there is provided a charging / discharging scheduling method of an energy storage device connected to a grid in accordance with an embodiment of the present invention to supply power to a load, Receiving cost information, time-series load profile data, maximum grid-load power constraint of the power network, and chemical characteristic information of the energy storage device; Determining a minimum storage capacity of the energy storage device using the input load profile data and the maximum allowable power output of the power network; And a charging / discharging path, which means a variation of an energy state of the energy storage device over time, so that an operating expense (OPEX) of the power network is minimized based on the determined minimum storage capacity and cost information of the power network Step.

In the charging / discharging scheduling method of an energy storage device according to an embodiment, the step of determining the minimum storage capacity of the energy storage device may include extracting a time period exceeding a maximum allowable limit output of the power grid from the input load profile data ; And estimating a minimum storage capacity to be supplemented from the energy storage by calculating an output of the excess power network corresponding to the time interval region.

In the charging / discharging scheduling method of the energy storage device according to an embodiment, the minimum storage capacity of the energy storage device is determined by dividing a region exceeding the maximum allowable limit output of the power grid in the load profile data, As shown in FIG.

In the charging / discharging scheduling method of an energy storage device according to an embodiment, the minimum storage capacity should be retained in the energy storage device at the beginning of the extracted time interval, and the output of the energy storage device is stored in the extracted time interval Lt; RTI ID = 0.0 > least < / RTI >

In a charge / discharge scheduling method of an energy storage device according to an embodiment, when a power is purchased from a power grid, a first cost is calculated by multiplying a purchased power amount by a purchase unit price, and when a power is sold to a power grid, And a sum of the first cost and the second cost according to the change of the time can be set as the operating cost of the power network.

In the charging / discharging scheduling method of an energy storage device according to an embodiment, the step of generating the charging / discharging path may include a step of generating a charging / discharging path based on the determined minimum storage capacity and cost information of a power grid necessary for supplying a required amount of power from a specific point- Setting an operating cost of the power network; And determining a charging and discharging path of the energy storage device over time using a dynamic programming algorithm such that the operating cost of the set power network is minimized.

In the charging / discharging scheduling method of an energy storage device according to an embodiment, the cost information of the power network is an hourly usage charge and a sales charge for a certain period.

In the charging / discharging scheduling method of an energy storage device according to an embodiment, the load profile data is statistical prediction data reflecting application characteristics of applications constituting the load side.

In the charging / discharging scheduling method of an energy storage device according to an embodiment, the rate of change of energy stored in the energy storage device per hour is estimated based on chemical characteristic information of the energy storage device, And may include at least one of a discharge depth (DoD), a replacement cost of the energy storage device itself, a cycle life, a use range, a maximum power amount, or a current rate (C-rate).

The present invention also provides a computer-readable recording medium having recorded thereon a program for causing a computer to execute charging / discharging scheduling methods of the energy storage device described above.

According to an aspect of the present invention, there is provided an apparatus for charging / discharging an energy storage device connected to a grid in accordance with an embodiment of the present invention to supply power to a load, An input unit receiving cost information, time-series load profile data, maximum grid-load power constraint of the power network, and chemical characteristic information of the energy storage device; And at least one processor to determine a minimum storage capacity of the energy storage device using the input load profile data and a maximum allowable limit output of the power network, and determine a minimum storage capacity of the energy storage device and a cost And a processor for executing a command to generate a charge / discharge path, which means a variation of an energy state of the energy storage device over time, so that an operating expense (OPEX) of the power network is minimized based on the information.

In the charging / discharging scheduling apparatus for an energy storage apparatus according to an embodiment, the processing unit may extract a time interval exceeding a maximum allowable limit output of the power grid from the input load profile data, And calculates an output of the power grid to estimate the minimum storage capacity to be replenished from the energy storage device.

In the charging / discharging scheduling apparatus for an energy storage device according to an embodiment, the minimum storage capacity of the energy storage device is set such that a region exceeding a maximum allowable limit output of the power grid in the load profile data for the extracted time period is divided into a time axis As shown in FIG.

In the charging / discharging scheduling apparatus for an energy storage device according to an embodiment, the minimum storage capacity should be held in the energy storage device at the beginning of the extracted time interval, and the output of the energy storage device is stored in the extracted time interval Lt; RTI ID = 0.0 > least < / RTI >

In the charging / discharging scheduling apparatus for an energy storage device according to an embodiment, the processing unit may calculate a first cost by multiplying a purchased power amount by a purchased unit price when power is purchased from a power grid, And the sum of the first cost and the second cost according to the change of the time can be set as the operating cost of the power network.

In the charging / discharging scheduling apparatus for an energy storage apparatus according to an embodiment, the processing unit may calculate an operating cost of the power grid based on the determined minimum storage capacity and the cost information of the power grid required to supply the required amount of power from the specific point- And determine a charging / discharging path of the energy storage device over time by using a dynamic programming algorithm so that the operating cost of the set power network is minimized.

In the charging / discharging scheduling apparatus for an energy storage device according to an embodiment, the control unit may control charge / discharge of the energy storage device according to the charge / discharge path generated in a time-series manner.

According to the embodiments of the present invention, when the maximum allowable limit output is set in the power network, the change in the electric bill according to the time series, the load pattern data, It is possible to establish a charging and discharging scheduling plan that enables the minimum operating cost in consideration of the internal chemical characteristics of the energy storage device, Not only the power can be supplied, but also the stability and reliability of the entire power network can be improved by appropriately limiting the amount of power drawn from the power network.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a diagram showing an overview of a power network, an energy storage device and a system to which a load is connected.
FIG. 2 is a block diagram illustrating an apparatus for charging and discharging an energy storage device according to an embodiment of the present invention and devices for interacting therewith. Referring to FIG.
3 is a diagram illustrating a process of deriving a charging / discharging path by optimizing charging / discharging scheduling apparatus of an energy storage apparatus according to an embodiment of the present invention, taking into account external conditions and internal conditions.
4 is a block diagram illustrating internal components of the charge / discharge scheduling apparatus for an energy storage device according to an embodiment of the present invention.
5 is a flowchart illustrating a charging / discharging scheduling method of an energy storage device according to an embodiment of the present invention.
6 is a diagram for explaining a process of calculating an interval in which a load demand output exceeds a power grid limit in a charging / discharging scheduling method adopted by embodiments of the present invention.
FIG. 7 is a diagram for explaining a process of determining a charge state of an energy storage device according to a charge / discharge scheduling method adopted in embodiments of the present invention.
FIG. 8 is a pseudo-code illustrating the charging / discharging scheduling algorithm employed by the embodiments of the present invention.

Prior to the description of the concrete contents of the present invention, for the sake of understanding, the outline of the solution of the problem to be solved by the present invention or the core of the technical idea is first given.

를 파라미터로 하는 함수로 정의하자. 전력망의 전력을

, 부하 측의 필요한 전력을

, 에너지 저장 장치의 출력 전력을

라고 정의하면, 이들의 관계는 수학식 1과 같이 수식화할 수 있다. FIG. 1 shows a general outline of a power network, an energy storage device, and a system to which a load is connected. Arrows indicated by dashed lines denote flow directions of energy, which is power, and can be defined as functions of time. The relationship between the supply of power to the load side through the grid and the energy storage

As a parameter. Power grid

, The required power on the load side

, The output power of the energy storage device

, These relations can be expressed by Equation (1).

In the case of using an energy storage device auxiliary to the power network in order to supply necessary power to the conventional load side in the situation as shown in FIG. 1, charging and discharging of the energy storage device are generally determined according to the time period charge of the power network.

However, when the energy storage device is manufactured as a secondary battery, the number of cycles of charging / discharging, that is, the number of cycles is determined. Depending on the type of energy storage device and the depth of discharge (DoD) It is different. Also, when the energy state of an energy storage device is expressed as a finite number of states, the cost of each energy state change is not the same, and the constant number of states does not increase the cost constantly. This is because the energy storage device is a chemical battery made of lithium ion or the like. Because of the intrinsic chemistry of these energy storage devices, charging and discharging scheduling of energy storage devices that take into account only the cost of the power network itself, without considering the cost of the energy storage device itself, does not guarantee effective use of the energy storage device.

Accordingly, embodiments of the present invention propose a charging / discharging scheduling apparatus for an energy storage device that considers costs due to internal chemical characteristics of an energy storage device for an energy storage device connected to a power network and supplying power to a load side. In particular, embodiments of the present invention together with these considerations have considered the maximum permissible power output condition of the power grid. Accordingly, in the charging / discharging scheduling process of the energy storage device adopted in the embodiments of the present invention, the conditions of the power charge pattern, the load pattern, the maximum permissible limit power of the power network, Given.

2 is a block diagram illustrating a charge and discharge scheduling apparatus 10 and an apparatus for interacting therewith of a power network 20, an energy storage apparatus 30 and a load 40 according to an embodiment of the present invention. , The solid line represents the flow of energy which is electric power, and the dotted line represents the flow of data (information).

The power grid 20 may be a power station, a power transmission tower, or the like, which generally supplies electric power. The energy storage device 30 is a storage device that stores excess power generated at a power plant and temporarily transmits power when the power is insufficient. There are batteries to store electricity and related devices to manage the battery efficiently. Battery-powered energy storage devices use lithium ion and sodium sulfate. Recently, energy storage devices for storing new and renewable energy have been increasing. The load 40 means a subject that consumes power. Household or industrial facilities can be the main consumers of electricity, and the specific requirements such as required power and voltage may vary depending on the type and time of each consumer.

The data flow of the dotted line is based on the charge / discharge scheduling device 10 of the energy storage device 30 from the power network 20 to the power network, cost information from the energy storage device 30 to the data sheet, And outputs charge profile data (load profile data) from the charge storage device 40 to the energy storage device 30 in a charge-and-discharge path of the cost-effective energy storage device. A solid line of energy flows between the power grid 20 and the energy storage device 30 in a bidirectional manner while the power grid 20 and the energy storage device 30 are connected in parallel to supply energy to the load side 40, . When the energy storage device 30 is used as a part of the distributed power supply, it is possible to return the surplus energy of the energy storage device 30 to the power supply network 20 and the representation thereof is transferred from the energy storage device 30 to the power supply network 20 The arrow of FIG.

3 is a diagram illustrating a process of deriving a charging / discharging path by performing optimization of a charging / discharging scheduling apparatus of an energy storage apparatus according to an embodiment of the present invention, taking into account external conditions and influences of internal conditions, And the dotted line indicates the flow of data (information).

The charge / discharge scheduling apparatus 10 can establish an optimal charge / discharge scheduling plan through an algorithm whose internal constraints and operating costs are minimized. In this process, the charge / discharge scheduling apparatus 10 receives various external constraints from the outside. These external constraints may include a power grid-load power constraint, a load profile, a demand response event signal, or a power charge. In particular, the embodiments of the present invention essentially receive the maximum permissible output power condition of the power grid as a power grid-load power constraint and reflect it in charge-discharge scheduling planning.

The charge / discharge controller 50 receives the charge / discharge scheduling plan established through the charge / discharge scheduling device 10, and controls charge / discharge of the energy storage device. The charge / discharge controller 50 may be implemented as a single control system integrated with the charge / discharge scheduling device 10, or may be implemented as a physically separated device depending on the implementation.

FIG. 4 is a block diagram illustrating internal components of a charge and discharge scheduling apparatus for an energy storage apparatus according to an embodiment of the present invention. The charge and discharge scheduling apparatus 10 of the energy storage apparatus includes an input unit 11 and a processing unit 12 ). The charging / discharging scheduling apparatus 10 may control the charging / discharging process of the energy storage device 30 according to the charging / discharging path generated in a time-series manner by a control unit 50 inside or outside the charging / discharging scheduling apparatus 10 As shown in FIG.

Hereinafter, the components of FIG. 4 together with the flowchart of FIG. 5 illustrating a charging / discharging scheduling method of an energy storage device according to an embodiment of the present invention will be described. FIG. 4 and FIG. 5 are diagrams showing a charging / discharging scheduling process of the energy storage device, focusing on the connection relationship between physical hardware and the device diagram and time sequence, respectively. Share functions.

In step S510, the charging / discharging scheduling apparatus 10 of the energy storage device receives the cost information of the power network, the load profile data, the maximum grid-load power constraints and chemical characteristics of the energy storage device.

로 입력받을 수 있다.The input unit 11 receives information on the cost of the power grid 20 from the power grid 20 and receives the data sheet from the energy storage device 30 and receives the load profile data from the load 40 side. First, the cost information of the power grid 20 can be a usage fee per hour for a certain period. Since the power required at the side of the load 40 varies with time, it is possible to charge and operate the system in a flexible manner. A certain period is usually 24 hours a day, and the time can be divided into sections, so that the rates can be determined differently by day, night, and night. There are many different types of plans that show the same hourly usage rates, and the most commonly used TOU (Time Of Use), CPP (Critical Peak Pricing), and RTP (Real-Time Pricing) won / kWh). The input unit 11 inputs these various types of plan to a price / unit price function

.

로 입력받을 수 있다.The cost information for the power network 20 includes the sales fee when the surplus energy of the energy storage device 30 is again sent back to the power grid 20 in the case of using the energy storage device 30 as a part of the distributed power supply, May be included in the information. These sales charges are also related to the price / unit price function

.

The data sheet is created when a specific energy storage device is manufactured, and records the information of the energy storage device itself, including its characteristics as a chemical cell. Specifically, the data sheet contains values for discharge depth, replacement cost of the energy storage unit itself, cycle life, maximum output and discharge rate. For example, the discharge depth is 100%, the replacement cost of the energy storage device is 1 million Yuan, the cycle life is 1,000 times based on the discharge depth of 100%, the maximum power is 70 kW, and the maximum discharge rate is 1 Once the device is manufactured, the values are listed in its datasheet. (Vertical axis) according to the number of cycles (horizontal axis) with the discharge depth as a parameter with respect to the cycle life.

로 정의될 수 있다. 부하 프로파일 데이터는 과거의 사용을 기록한 자료가 될 수 있으며, 일반적으로 부하 프로파일 데이터는 최근 3일, 5일, 10일 동안의 시간에 따른 전력 사용량에 대하여 평균값을 취해 활용한다. 전력 사용량은 계절 및 날씨에 영향을 많이 받아서 수요량이 달라진다. 즉, 여름철 땡볕 더위가 이어지는 경우 냉방으로 인해 전력 소모가 급증하는 것이 그 예이다. 그렇기 때문에 특정 시점부터 목표 시점까지와 온도가 비슷한 과거의 데이터를 활용하여 부하 프로파일 데이터를 산출할 수도 있다. The load profile data is a function representing the amount of power over time

. ≪ / RTI > The load profile data can be a record of past usage, and the load profile data is generally taken as an average value of the power usage over the last three days, five days, and ten days. Power consumption is affected by season and weather, so demand varies. That is, when the summer heat is followed by the heat, the power consumption is rapidly increasing due to cooling. Therefore, it is possible to calculate load profile data using past data whose temperature is similar to that of a specific point in time.

Also, the load profile data may be different depending on whether the consumer on the side of the load 40 is the household power consumption consuming body or the industrial power consumption consuming body. In the case of home use, power consumption is mainly performed in the morning, evening, and night, and in the case of industrial use, power consumption is generally performed in the daytime from morning to afternoon. Therefore, knowing how much power is needed is predictive of the future, and load profile data can be statistical predictive data that reflects the application characteristics of the applications that make up the load side. Therefore, the input unit 11 can receive the load profile data in the form of a graph indicating the amount of power on the horizontal axis and time on the vertical axis.

Further, the rate of change per unit time of the energy stored in the energy storage device 30 is estimated based on the chemical property information of the energy storage device 30, and the chemical property information of the energy storage device 30 is a Depth of Discharge And a current rate (C-rate) of the energy storage device itself, DoD, a replacement cost of the energy storage device itself, a cycle life, a usage range, a maximum output amount or a discharge rate.

The definition of the variables used in the charging / discharging scheduling algorithm described below is as shown in Table 1 below. The charging / discharging scheduling is achieved by the processing unit 12 having at least one processor performing a set of instructions can do. It is a matter of course that memory can be utilized as the space required for the operation during the execution of this instruction set.

 variable  Variable Description

Electricity / Purchase Fee

Distributed power sales fee

Load profile

Energy storage (battery) charge status

Power grid (Power)

Maximum allowable limit / constraint output of the power grid

Output power of energy storage device

Maximum capacity of the energy storage device

Unit time

Energy state unit

The number of energy states of an energy storage device

,

를 만족하는 시간 인덱스(time index)와 에너지 인덱스(energy index)를 각각 k, n으로 정의하며, 에너지 저장 장치의 에너지 상태는 유한한 숫자의 상태(state)를 가진다고 가정한다.

,

K and n are defined as a time index and an energy index satisfying the following equation, respectively, and it is assumed that the energy state of the energy storage device has a finite number of states.

In step S520, the charging / discharging scheduling apparatus 10 of the energy storage device determines the minimum storage capacity of the energy storage device using the load profile data input through step S510 and the maximum allowable limit output of the power network. In this process, the processing unit 12 extracts a time period exceeding the maximum allowable limit output of the power network from the input load profile data, calculates an output of the over-power network corresponding to the time period region, And estimates the minimum storage capacity to be replenished from the apparatus.

Here, the minimum storage capacity of the energy storage device may be calculated by integrating, over the extracted time period, an area exceeding the maximum allowable limit output of the power grid from the load profile data along the time axis. Referring to FIG. 6, in the charge / discharge scheduling method adopted in the embodiments of the present invention, a process of calculating a period in which a load demand output exceeds a power grid limit is illustrated.

는 i번째 피크 컷(peak cut, 부하 프로파일이 전력망의 한계치를 넘지 않는 조건)이 시작되는 시점을 나타내고,

는 i번째 피크 컷이 종료되는 시점을 나타낸다. 따라서, 음영으로 표시된

는 부하 프로파일에서 전력망의 한계치(

)를 초과하는 영역을 나타내고, 이러한 영역은 곧

시점에 에너지 저장 장치에 미리 보유되어 있어야 하는 최소 용량을 의미함을 알 수 있다.6,

Represents the time at which the i-th peak cut (peak cut, a condition in which the load profile does not exceed the power grid limit) starts,

Represents the end of the i-th peak cut. Therefore,

Is the limit of the grid in the load profile

), And this region is immediately

It means the minimum capacity that should be held in advance in the energy storage device at the time of the start of the operation.

)이 다음의 수학식 2와 같이 산출된다.Now, during the time the peak cut is performed, the output of the minimum energy storage device

) Is calculated by the following equation (2).

로서 정의 및 산출된다. 이러한 과정에서 다음의 두 가지 조건이 수반된다.The difference between the load profile and the maximum allowable power output of the grid is the minimum battery output required at time index k

. The following two conditions accompany this process.

에서 에너지 저장 장치가 보유해야 할 최소 보유(Reserve) 용량,

이상의 조건을 피크 컷이 시작되는 시점인

에 만족시켜야 한다.The amount of energy charged to the energy storage device is

The minimum reserve capacity that an energy storage device should have,

The above conditions are set at the time when the peak cut is started

.

) 이상의 값을 가져야 하는 조건 또한 만족시켜야 한다.The output of the energy storage device also has a minimum energy storage output (< RTI ID = 0.0 >

) Must also be satisfied.

That is, the minimum storage capacity should be held in the energy storage device at the beginning of the extracted time interval, and the output of the energy storage device should be maintained at least at least the minimum storage capacity during the extracted time interval .

In step S530, the charging / discharging scheduling apparatus 10 of the energy storage apparatus determines whether the operating expense (OPEX) of the power grid is minimized based on the minimum storage capacity determined through step S520 and the cost information of the power grid A charging / discharging path which means a variation of an energy state of the energy storage device with time is generated.

To this end, the processing unit 12 calculates a first cost by multiplying the amount of purchased power by the purchased unit price, and when the power is sold to the power network, the processing unit 12 multiplies the amount of sold power by the selling unit price, And the sum of the first cost and the second cost according to the change of the time can be set as the operating cost of the power network. In addition, the processing unit 12 sets the operating cost of the power network on the basis of the determined minimum storage capacity and the cost information of the power network necessary for supplying the necessary amount of power from the specific point of time to the target point of time, It is possible to determine the charge / discharge path of the energy storage device over time using a dynamic programming algorithm.

That is, the processing unit 12 estimates the required amount of power according to the time from the load profile data to the target point. The amount of power required up to the target point is estimated based on the load profile data, which is statistical prediction data reflecting application characteristics of the application constituting the side of the load 40 received by the input unit 11. The charging and discharging path of the energy storage device 30 for supplying power to the load 40 as much as the required amount of electric power is generated so that the charging / Means the variation of the energy state of the storage device 30.

에 대하여 동적 프로그래밍(Dynamic Programming) 알고리즘을 적용하여 시간에 따른 에너지 저장 장치(30)의 충방전 경로를 생성할 수 있다. 동적 프로그래밍 알고리즘은 벨만 방정식(Bellman equation)과 같은 최단 경로 찾는 알고리즘이 될 수 있다. 본 발명에 따른 실시예들은 벨만 방정식을 이용하고 있지만, 플로이드-워셜 알고리즘(Floyd-Warshall) 등과 같은 다른 알고리즘을 이용할 수 있을 것이다. Which is defined as the minimum sum of the cost of the power grid 20 and the cost of the energy storage device 30 for supplying the necessary amount of power E from the specific time point k to the target time point,

It is possible to generate a charge / discharge path of the energy storage device 30 over time by applying a dynamic programming algorithm to the energy storage device 30. Dynamic programming algorithms can be shortest path finding algorithms such as the Bellman equation. While the embodiments of the present invention utilize the Bellman equation, other algorithms such as the Floyd-Warshall algorithm may be used.

에 따른 에너지 변화가 일어날 때에 발생하는 비용(cost), 즉 전이 비용(Transition Cost)

은 다음과 같이 결정된다.More specifically, in a sufficiently small time unit

(Ie, transition cost) that occurs when an energy change occurs due to a change in energy,

Is determined as follows.

일 때, 1) Reflection of Equation 3:

when,

을 만족 못하는 경우에는 전이 비용의 값을 무한대로 할당해, 최소 비용(Least Cost) 충방전 경로 재구성 시 선택되지 않게 설정한다. 그 이외의 경우에는

의 범위에 따라 각각 전력가격 및 분산전원의 가격으로 운영 비용(Operating Expenditure, OPEX)이 결정된다.The condition of equation (3)

The value of the transition cost is set to be infinite so that it is not selected when the minimum cost (charge / discharge path) is reconstructed. Otherwise,

The operating expense (OPEX) is determined by the price of the power and the price of the distributed power, respectively.

2) Reflection of Equation 4:

를 만족하지 못하는 경우에는 전이 비용의 값을 무한대로 할당하고 그 외의 경우에는 수학식 3을 반영한 경우와 동일하게 할당한다.The condition of equation (4)

The value of the transition cost is assigned to the infinite value, and in other cases, the value is assigned in the same way as in the case of reflecting the equation (3).

FIG. 7 is a diagram for explaining a process of determining the charge state of the energy storage device according to the charging / discharging scheduling method adopted by the embodiments of the present invention. The method for minimizing the operating cost according to the maximum allowable value constraint of the power network I am suggesting. Referring to FIG. 7, it is shown how a preparation state of a state-of-charge (SOC) of the energy storage device should be prepared in advance for peak cut control in a time interval in which the output of the load pattern is larger than the limit of the power grid.

FIG. 8 is a pseudo-code illustrating the charging / discharging scheduling algorithm employed by the embodiments of the present invention.

은 초기 시점부터 에너지 저장 장치의 운영이 종료되는 시점 T까지의 최소 비용(minimum cost)을 나타내는 최소값 함수(minimum value function)이다. 앞서 도 1을 통해 설명한 바와 같이 본 발명의 실시예들이 전제하는 문제 상황에서 부하가 필요로 하는 전력량은 전력망에서 유입되는 전력과 에너지 저장 장치에서 공급하는 전력량의 합으로 수식화 가능하다. 에너지 저장 장치는

라는 특정한 최대용량을 가지고 있으며, 이때 에너지 저장 장치가 저장하고 있는 에너지의 시간당 변화율은 현재 출력되고 있는 출력 전력 P와 저장되어 있는 에너지 E에 대한 상태방정식

로 정의할 수 있다. 이는 에너지 저장 장치의 특성에 따라 다르므로 에너지 저장 장치 데이터 시트를 통해 도출할 수 있다. 또한 특정 시점 k에서 운영이 종료되는 T까지의 전력 요금의 합을 나타내는 값 함수(value function)는

와 같이 수식화될 수 있다.

Is a minimum value function that represents the minimum cost from the initial point of time until the operation of the energy storage device is terminated. As described above with reference to FIG. 1, the amount of power required by the load in a problem state assumed in the embodiments of the present invention can be expressed by the sum of the power supplied from the power network and the amount of power supplied from the energy storage device. The energy storage device

And the rate of change of the energy stored in the energy storage device per hour is calculated by the state equation for the output power P currently being output and the stored energy E

. It depends on the nature of the energy storage device and can be derived from the energy storage data sheet. Also, a value function that represents the sum of power charges from a particular time k to the end of operation t

As shown in FIG.

는 부하 측에 필요한 전력량,

는 전력망(20)으로부터 공급받거나 전력망(20)으로 판매되는 전력량,

는 시간당 전력량의 사용 요금,

는 시간당 전력량의 판매 요금을 나타낸다.8

The amount of power required on the load side,

The amount of power supplied from the power grid 20 or sold to the power grid 20,

Is the usage charge of electricity per hour,

Represents the selling price of electricity per hour.

There is a need to calculate the cost of the entire power supply by reflecting the demand response when the energy storage device 30 is used as a part of the distributed power supply. Demand response is designed to induce consumers to reduce electricity usage at times when wholesale electricity prices are high or when system reliability is at risk, and they define consumers as changing their power consumption patterns in response to incentives or changes in electricity rates over time . The embodiments of the present invention not only affect the charging and discharging of the energy storage device when the demand reaction signal is received by reflecting the usage factors of the distributed power supply but also the function of supplying the surplus power to the power grid 20 and reselling .

를 통해 반영되었다.Upon receipt of the demand response signal, power is supplied to the load side through the energy storage device 30, and surplus energy is resupplied to the power grid 20. [ Therefore, the function considering the cost of returning the surplus energy to the power grid 20 by reflecting the demand response signal is a function of the operating cost function

.

에서, 1_{조건}은 괄호 안의 조건이 참이면 1, 거짓이면 0 값을 반환한다.

의 경우는 부하(40) 측에서 요구하는 전력량이 에너지 저장 장치(30)가 공급가능한 전력 이상인 구간에서 산출되는 감가상각 비용을 의미하고,

의 경우에는 에너지 저장 장치(30)가 공급가능한 전력이 부하(40) 측에서 요구하는 전력보다 큰 구간에서 산출되는 감가상각 비용을 의미한다. 이때에는 공급 후 남는 전력을 분산전원 단가

로 전력망(20)에 되팔아서 경제적 이득을 얻을 수 있다. 이렇듯 각 단위 시간마다

의 조건에 따라 전력망 사용 요금

또는 분산전원의 사용 요금

를 선택적으로 취하여

가 계산된다. 이는 입력부(11)가 수요반응 신호(Demand Response Event Signal) 및 분산전원의 시간에 따른 요금을 입력받고, 처리부(12)가 상기 수요반응 신호를 수신하면 상기 에너지 저장 장치(30)의 감가상각 비용을 상기 분산전원의 시간에 따른 요금으로 대체할 수 있는 것을 의미한다. 처리부(12)가 수요반응 신호를 수신하면 상기 에너지 저장 장치(30)의 에너지 상태가 낮아지는 방전 경로를 우선 선택하도록 하기 위하여 분산전원의 사용 요금

을 책정한다. 이에 따라서 분산전원의 사용 요금이 높게 책정되면 수요반응에 적극 참여하게 되어 상기 에너지 저장 장치(30)로부터 부하(40) 측에 전력을 공급하는 방전이 일어나게 되는 것이다.8

1_ {condition} returns 1 if the condition in parentheses is true, 0 if it is false.

Refers to a depreciation cost calculated in a period in which the amount of power required by the load 40 is equal to or greater than the power that the energy storage device 30 can supply,

Refers to a depreciation cost calculated in a section where the power that can be supplied by the energy storage device 30 is larger than the power required by the load 40 side. At this time,

To the power grid 20 to obtain an economic gain. In this way,

The electricity use fee

Or the usage fee of distributed power

Lt; RTI ID = 0.0 >

Is calculated. This is because the input unit 11 receives the demand response signal and the charge according to the time of the distributed power supply and when the processing unit 12 receives the demand reaction signal, the depreciation cost of the energy storage device 30 Can be replaced with a charge according to time of the distributed power source. In order to select a discharge path in which the energy state of the energy storage device 30 is lowered when the processing unit 12 receives the demand reaction signal,

. Accordingly, if the charge of the distributed power source is set to be high, the electric power is supplied to the load 40 from the energy storage device 30 because the electric charge is actively involved in the demand reaction.

에 대하여 벨만 방정식을 이용하여 충방전 경로를 생성하기 위한 수식은 아래 수학식 5 및 수학식 6이 된다. On the other hand, dynamic programming algorithms can be shortest path finding algorithms such as the Bellman equation. While the embodiments of the present invention utilize the Bellman equation, other algorithms such as the Floyd-Warshall algorithm may be used. Operating cost function

The following equations (5) and (6) are used to form the charge / discharge path using the Bellman equation.

이 알려진 T 시점부터 거꾸로 연산이 진행된다.Equation (5) defines the cost minimization function using the Bellman equation, which is a function of the backward recursion

The operation proceeds from the known T point backwards.

는 특정 시점 k에서부터 운영이 종료되는 시점인 T까지의 사용 전력 요금의 합계를 뜻하므로 종료 시점인 T에서의

값이 0이 되는 것을 확인할 수 있다. 그 후 벨만 방정식을 통해

만큼의 시간축을 거쳐 진행될 때마다 거리 변수(distance vector)가 가장 짧은 경로(shortest path)를 통과하게 된다. 이렇게 순환적으로 구해진

를 수학식 6에 대입하여 전방순환(forward recursion) 방법을 통해 최적의 충방전 경로를 산출할 수 있다. 이러한 방식은 에너지 저장 장치(30)와 전력망(20)이 갖추어진 조건하에서 비용의 최소화를 통한 운영 알고리즘 구현에 적합한 방식이라고 할 수 있다. To explain the calculation process in more detail,

Is the sum of the electricity charges from the time k to the time T is terminated,

The value becomes zero. Then, through the Bellman equation

The distance vector is passed through the shortest path every time it passes through the time axis. In this way,

Can be substituted into Equation (6) to calculate an optimal charge / discharge path through a forward recursion method. This method is suitable for implementing an operating algorithm by minimizing the cost under the condition that the energy storage device 30 and the power network 20 are provided.

이 산출될 때까지 벨만 방정식을 수행한다. 운영 비용 함수는 전력망의 비용(Running cost)으로부터 구체화된다. 시간 지표(time index) k를 시작 시점 0부터 목표 시점 T까지 충분히 작은 시간단위

에 따른 에너지 변화가 일어날 때에 발생하는 비용을

에 따라 값을 계산하고, 벨만 방정식을 적용하여 운영 비용 함수를 계산하여 최종적으로 최적의 충방전 경로를 결정하게 된다.In summary, the algorithm of FIG. 8 is designed to minimize operating costs

And then performs the Bellman equation until it is calculated. The operating cost function is specified from the running cost of the grid. The time index k is a time unit that is sufficiently small from the starting point 0 to the target point T

The cost of energy change due to

And calculates the operating cost function by applying the Bellman equation to finally determine the optimum charge / discharge path.

According to the above-described embodiments, the maximum allowable limit output of the power grid can be arbitrarily set during the operation time when the energy storage device is operated, and the change in the electric bill according to the time series under the condition that the output from the power grid has a value within the set range , Load pattern data, and internal storage characteristics of the energy storage device. As a result, it is possible to operate the grid in a stable and planned manner from the viewpoint of the operator, and it is also possible to prevent the problem that the facility is overexposed in order to sufficiently cover the instantaneous peak power.

Meanwhile, the embodiments of the present invention can be embodied as computer readable codes on a computer readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored.

Examples of the computer-readable recording medium include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like. In addition, the computer-readable recording medium may be distributed over network-connected computer systems so that computer readable codes can be stored and executed in a distributed manner. In addition, functional programs, codes, and code segments for implementing the present invention can be easily deduced by programmers skilled in the art to which the present invention belongs.

As described above, the present invention has been described with reference to particular embodiments, such as specific constituent elements, and limited embodiments and drawings. However, it should be understood that the present invention is not limited to the above- And various modifications and changes may be made thereto by those skilled in the art to which the present invention pertains.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

10: charge / discharge scheduling device
11: Input unit
12:
20: Power grid
30: Energy storage device
40: Load
50:

Claims (17)

A charge / discharge scheduling method of an energy storage device connected to a grid (Grid) to supply power to a load (Load)
Cost information of the grid including the usage charge of the load side at the load side for a certain period and the surcharge of the surplus energy to the grid, time load profile data, maximum grid-load power of the grid constraint and chemical property information of the energy storage device;
Determining a minimum storage capacity of an energy storage device for supplementing a load exceeding the maximum tolerable output with time using the input load profile data and the maximum allowable limit output of the power network; And
Means a variation of the energy state of the energy storage device over time such that the operating expense (OPEX) of the power network due to purchase and sale of the power is minimized based on the determined minimum storage capacity and the cost information of the power network And generating a charging / discharging path. The method according to claim 1,
Wherein determining the minimum storage capacity of the energy storage device comprises:
Extracting a time interval exceeding a maximum allowable limit output of the power grid from the input load profile data; And
Calculating an output of the excess power network corresponding to the time interval region, and estimating a minimum storage capacity to be supplemented from the energy storage device. 3. The method of claim 2,
Wherein the minimum storage capacity of the energy storage device
And integrating a region exceeding a maximum allowable limit output of the power grid in the load profile data with respect to the extracted time interval along a time axis. 3. The method of claim 2,
Wherein the energy storage device holds the minimum storage capacity at the start of the extracted time interval,
And maintains the output of the energy storage device at least over the minimum storage capacity during the extracted time period. The method according to claim 1,
When the electric power is purchased from the electric power network, the first cost is calculated by multiplying the purchased electric power by the purchase unit price,
When selling electric power to the power grid, the second cost is calculated by multiplying the sales amount by the selling price,
Wherein the sum of the first cost and the second cost is set as an operating cost of the power network according to a change in time. The method according to claim 1,
Wherein the step of generating the charge /
Setting an operating cost of the power grid based on the determined minimum storage capacity and the cost information of the power grid required to supply the required power amount from the specific point of time to the target point; And
A dynamic minimization function defined as a minimum sum of a cost of the power network and a cost of the energy storage device as a factor of a required power amount up to the target time and the specific time point so that the operating cost of the power network is minimized, determining a charging / discharging path of the energy storage device with respect to time using a programming algorithm. delete The method according to claim 1,
Wherein the load profile data is statistical predictive data reflecting usage characteristics of an application constituting the load side. The method according to claim 1,
Wherein the rate of change of energy stored in the energy storage device over time is estimated based on chemical property information of the energy storage device,
The chemical characteristic information of the energy storage device may include at least one of a Depth of Discharge (DoD), a replacement cost of the energy storage device itself, a cycle life, a use range, a maximum output amount or a C- Wherein the charge / discharge scheduling method comprises: A computer-readable recording medium storing a program for causing a computer to execute the method according to any one of claims 1 to 6, 8, and 9. An apparatus for charging / discharging an energy storage device connected to a grid (Grid) to supply power to a load (Load)
Cost information of the grid including the usage charge of the load side at the load side for a certain period and the surcharge of the surplus energy to the grid, time load profile data, maximum grid-load power of the grid constraint and energy characteristic of the energy storage device; And
A minimum of an energy storage device for supplementing a load exceeding the maximum tolerable output with time using the input load profile data and the maximum permissible limit output of the power grid, Determining energy storage energy consumption over time to minimize operating expense (OPEX) of the power network due to purchase and sale of power based on the determined minimum storage capacity and cost information of the power network, And a processor for executing a command to generate a charge / discharge path indicating a variation in state. 12. The method of claim 11,
Wherein,
Extracting a time interval exceeding a maximum allowable limit output of the power grid from the input load profile data,
And estimates a minimum storage capacity to be supplemented from the energy storage device by calculating an output of the excess power network corresponding to the time interval region. 13. The method of claim 12,
Wherein the minimum storage capacity of the energy storage device
Wherein the charge / discharge scheduling device calculates the charge / discharge scheduling area by integrating an area exceeding a maximum allowable limit output of the power network from the load profile data with respect to the extracted time interval along a time axis. 13. The method of claim 12,
Wherein the energy storage device holds the minimum storage capacity at the start of the extracted time interval,
And maintains the output of the energy storage device at least above the minimum storage capacity during the extracted time period. 12. The method of claim 11,
Wherein,
When the electric power is purchased from the electric power network, the first cost is calculated by multiplying the purchased electric power by the purchase unit price,
When selling electric power to the power grid, the second cost is calculated by multiplying the sales amount by the selling price,
And sets the sum of the first cost and the second cost as the operating cost of the power network according to the change of the time. 12. The method of claim 11,
Wherein,
Setting the operating cost of the power network based on the determined minimum storage capacity and the cost information of the power network necessary for supplying the required amount of power from the specific point of time to the target point of time,
A dynamic minimization function defined as a minimum sum of a cost of the power network and a cost of the energy storage device as a factor of a required power amount up to the target time and the specific time point so that the operating cost of the power network is minimized, programming algorithm to determine charge / discharge paths of the energy storage device over time. 12. The method of claim 11,
And a controller for controlling charging and discharging of the energy storage device according to the charging / discharging path thermally generated in a time-series manner.

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