WO2011040656A1

WO2011040656A1 - System and method for operating a microgrid

Info

Publication number: WO2011040656A1
Application number: PCT/KR2009/005619
Authority: WO
Inventors: 이학주; 채우규; 추철민; 김주용
Original assignee: 한국전력공사
Priority date: 2009-09-29
Filing date: 2009-09-30
Publication date: 2011-04-07
Also published as: KR101045326B1; KR20110034888A

Abstract

The present invention relates to a system and method for operating a microgrid configured with a plurality of distributed power supplies, in which the power to be generated by each distributed power supply is determined to maximize earnings from the operation of the microgrid, in consideration of power and thermal load constraints and power transaction rates. A system for operating a microgrid according to one embodiment of the present invention comprises: a microgrid system unit, including at least one distributed power supply, and supplying electric power to a load of the microgrid; a distributed power supply generation planning system unit, for generating a distributed power supply generation plan for optimizing earnings, by calculating optimum output conditions of the distributed power supply; and an energy management system unit for controlling the distributed power supply in accordance with the generated distributed power supply generation plan. Efficient and economical operation of the microgrid is made possible according to the present invention.

Description

Microgrid Operating System and Methods

The present invention provides a microgrid operating system for determining the amount of generation of each distributed power source to maximize the profits of the microgrid operation in consideration of the power and thermal load constraints and the power transaction fee in the microgrid composed of a plurality of distributed power supplies. It is about a method.

Recently, due to the regulations, etc. related to the oil prices and the environment, despite the economy by excessive initial investment in the development of relying on fossil fuels so many restrictions on existing generator is relatively low, and domain for the conservation of the CO ₂ reduction Global efforts are increasing to expand and disseminate renewable energy such as solar and wind power.

In addition, the initial investment cost and operating cost of distributed power generation have been gradually lowered compared to the unit price with the existing generator. For this reason, the construction of microgrids with distributed power supplies is emerging as a competitive new issue.

In the early 2000s, microgrid, a small power supply system consisting of distributed power and load, was introduced to expand and distribute distributed power sources including renewable energy. The development of related technologies is progressing actively.

Microgrid is a small power supply system consisting of multiple distributed power supplies and energy storage devices, which can be defined as a cluster of power and loads, and is a new power supply system that can supply power and heat simultaneously.

The microgrid operates in conjunction with the upper system, but should be able to operate independently when a fault occurs in the upper system. That is, the microgrid can be classified into i) linked operation mode that can be operated in connection with higher system and ii) independent operation mode that operates separately from higher system using STS.

Currently, the generation cost of distributed power generation is higher than that of existing grid generators, and the demand for power or heat varies, and storage devices such as storage devices exist, so there is no suggestion for optimal operation and economic operation of these various distributed power generation. have.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and the distributed power source selected by the user using the distributed power equipment information and the related information such as the weather information and the load pattern is composed of the micro grid, and for 24 hours for the plurality of distributed power sources. It is to provide a microgrid operating system and methodology that will determine the optimal development plan for the project to maximize revenue.

In addition, the present invention obtains the optimum solution of the objective function that maximizes the sum of the power and heat supply price supplied to the load by the distributed power source constituting the microgrid and the power price sold in the upper system to maximize the profit. It is to provide an operating system and method of the grid.

In addition, an object of the present invention is to effectively participate and expand the micro grid in the power market based on this.

According to one aspect of the invention, a microgrid operating system is provided.

The microgrid operating system according to an embodiment of the present invention includes a microgrid system unit for supplying power to the load of the microgrid, including at least one distributed power source, and calculates an output optimized condition of the distributed power source to optimize the distribution of profits. And a microgrid operating system including a distributed power generation planning system section for establishing a power generation plan and an energy management system section for controlling the distributed power generation according to the established distributed power generation plan.

According to another aspect of the present invention, a method of operating a microgrid is provided.

In accordance with another aspect of the present invention, there is provided a method of operating a microgrid, the method comprising: reading at least one of distributed power supply device information, load, power rate, weather, and environment information; and configuring at least one of the microgrids using the information. Calculating an optimum condition capable of maximizing profit according to an operation method by turning on / off one distributed power supply and performing a profit maximization operation of the distributed power supply by controlling an output amount to the distributed power supply according to the calculated optimal condition Includes microgrid operating methods.

The present invention obtains the optimal condition of distributed power output by considering the power and heat constraints, the operation mode of the independent operation of the microgrid and the linked system of the upper system, and provides the information to the microgrid operating system to provide the information to the microgrid operating system. Economical operation is possible.

In addition, the present invention is a system capable of maximizing profits according to the microgrid operation method by enabling the power trading with the commercial system of the power company by using the price information on the power transaction, it is possible to expand and expand the microgrid by inducing market participation voluntarily Do.

In addition, the implemented system can be configured simply by the user selects only the components for the design of the microgrid, it is possible to provide a user convenience and the microgrid considering the power and thermal load constraints Economical driving strategies can be verified in advance.

In addition, the present invention can be linked to the power market price, it is possible to analyze the development of the microgrid business model by using it as a preliminary analysis of the operating strategy of the microgrid.

1 to 4 are diagrams for explaining the configuration of a microgrid operating system according to an embodiment of the present invention.

5 and 6 are views for explaining a microgrid operating method for generating a maximum profit in a microgrid consisting of a plurality of distributed power supply according to an embodiment of the present invention.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, the microgrid operating system includes a microgrid system unit 100 including a plurality of distributed power supplies and power converters, and a distributed power generation plan that calculates an optimal output condition of a distributed power supply by maximizing revenue. The system unit 200 includes an upper system linking unit 300 connected to a main grid, which is an upper system, and an energy management system unit 400 for controlling and managing distributed power according to an optimized distributed power generation plan.

The microgrid system unit 100 supplies power to the load 161 in the microgrid.

As shown in FIG. 2, the microgrid system unit 100 includes a plurality of

distributed power sources

101, 102, 103, 104, 111, 112,

power converters

131, 141, 142, and 151 and an energy storage device ( 121).

Referring to FIG. 2, the solid line represents a normal distribution line, the dotted line represents a communication line, and the thick bar line represents a heat transfer path.

The microgrid system unit 100 is a boiler 101, cogeneration generator 102, fuel cell 103, microturbine 104 and power converter 131, solar power generation 112 capable of direct control of the output And a distributed power source of the power converter 142, the wind power generator 111, and the power converter 141.

In addition, the micro grid system unit 100 may further include an energy storage device 121 and a power converter 151, and may supply power to the load inside the microgrid by an internal system.

As shown in FIG. 3, the distributed power generation planning system unit 200 uses a distributed power supply device information related database 201, a load and power bill database 202, a weather and environmental information related database 203, and a dynamic planning method. It is composed of a plurality of distributed power generation planning unit 211 used.

The distributed power generation planning system unit 200 inputs load patterns, electric charges, wind speeds, solar radiation, temperature, and the like recorded in various DBs 201 to 203 into the distributed power generation planning unit 211. The distributed power generation planning unit 211 calculates the distributed power optimum output 221 and transmits it to the energy management system 400 to maximize the profit of the distributed power.

On the other hand, the upper system linkage unit 300 links the microgrid system unit 100 and the distribution system that is the upper system.

The upper system linkage unit 300 may trade power with the upper grid with the micro grid system unit 100 when the amount of generation of distributed power is greater than the microgrid load.

The upper system linkage unit 300 is connected to the upper system 301 through the microgrid system unit 100 and a static transfer switch (STS) 303. In addition, when a failure of the upper system occurs, the STS 303 separates the upper system 301 and performs independent operation.

The energy management system unit 400 is connected to the microgrid system unit 100 through a communication network for efficient energy management.

The energy management system 400 commands the output amount to the distributed power supply of the microgrid system unit 100 by reflecting the result of the distributed power generation planning system unit 200 and performs profit maximization operation of the distributed power supply through the control.

The following describes the objective function for economical operation of microgrids.

The distributed power generation plan system unit 200 calculates an optimal condition that can maximize profits according to a driving method by turning on / off a plurality of distributed powers constituting the micro grid for 24 hours.

First, the income from the operation of the microgrid is expressed as the sum of heat, power supplied to the microgrid's load, and power traded with the upper system, and is represented by Equation (1).

[Revision 16.10.2009 under Rule 26]

Where k is the time period, Rk is the gross income at k, and P^e _k, P^h _k,P^e _{k, sell} Represents the power and heat supply at k and the power sold at higher system, respectively. Also, ρ^e _k, ρ^h _k,ρ^e _{k, sell} Is expressed as power unit price, thermal unit price and electric power unit price.

On the other hand, the total cost of the microgrid is the sum of distributed power generation costs, start-up and shutdown costs, power purchase costs from the upper system, and storage life reduction costs, and is represented by Equation 2.

Here, the generation cost of the distributed power source can be expressed as follows.

Where i is the distributed power supply, P _{k, i} is the output of the distributed power supply i and is represented by [kW], and c _{G, i} (P _{k, i} ) is the power generation cost of the power P _{k, i} .

The start and stop costs of the distributed power supply are represented by the following equation.

Here, S and T are the start and stop costs per hour of the distributed power supply, and c ^fix _i is the fixed cost per hour of the distributed power supply i.

u _{k, i} is the operating state of the generator in time interval k. When u _{k, i} = 0, it is off, and u _{k, i} = 1 is on.

x _{k, i} is a state variable representing on or off accumulated time of distributed power source i in time interval k.

The power purchase cost C _kbuy from upper system in k is

P ^e _kbuy and ρ ^e _kbuy are the amount of electricity purchased from the upper system in k and the unit cost.

The lifespan shortening cost of the storage device 121 is expressed by Equation 4.

Where Crep _bat is the replacement cost of the storage bank, N _bat is the number of storage devices in the bank, Q _lifetime is the unit _lifetime of one storage device, and η _rt is the storage efficiency.

The lifespan of the storage device 121 is represented by Equation 5 below.

f i: number of failed cycles

d i: discharge rate [%]

q max: Maximum capacity of the storage device [kWh]

V nom: Rated voltage of the storage device.

As a result, the profit of the microgrid is expressed as in Equation 6 below.

Where N is the total number of distributed sources.

In the present invention, the objective function is to realize the maximum profit by turning on / off a plurality of distributed power sources constituting the microgrid for 24 hours, as shown in Equation (7).

The following are the constraints on distributed power supply operation and shutdown status, state change, output and load, storage device discharge condition, power converter capacity and transmission capacity to find the optimal solution of the objective function to maximize profit of microgrid. will be.

First, the control variables u _{k, i} of the generator designate the operation state as 1 and the stop state as 0 as a constraint on the minimum starting and stopping time of distributed power.

Second, in the present invention, the constraint on the state change is represented by Equation (9).

Third, the constraint on the output is expressed as follows.

Fourth, load and heat constraints are expressed as follows.

Fifth, the charge and discharge constraints of the storage device are shown as follows.

Sixth, the constraint on the capacity of the power converter for the distributed power source is expressed as follows.

Seventh, constraints on transmission capacity are as follows.

5 and 6 are diagrams for explaining a microgrid operating method for generating a maximum profit in a microgrid composed of a plurality of distributed power sources according to an embodiment of the present invention.

The microgrid operating method applied to the present invention is a method of determining the output of a distributed power source for generating maximum profit through valuation of microgrid operation for each time slot.

In step S510, the distributed power generation planning system unit 200 loads necessary information such as load and climate data from a database.

In step S520, the distributed power generation planning system unit 200 selects the type and capacity of distributed power, the operation mode of the independent operation and grid connection, storage device, power conversion device, etc. Microgrids are constructed by entering distributed power data or importing data in file form.

In step S530, the distributed power generation planning system unit 200 is a new generation of renewable energy, such as wind power generation 111, photovoltaic power generation 112, for the economic operation of the micro grid, the power generation cost is relatively low, so the capacity and climate Considering such constraints, the maximum output is reduced to reduce the load inside the microgrid.

In operation S540, the distributed power generation planning system unit 200 defines an initial operating state of at least one generator except for renewable energy.

In step S550, the distributed power generation planning system unit 200 designates i = 0 to 23 and first sets Stage i = 23 to simulate 24 hours a day, and then, i _{i = 1} , which is the total revenue after the point in time _i. Set to 0. Here, i starts from 23 to use the backward method.

In step S560, the distributed power generation planning system unit 200 sets j, which is a variable representing the current state of the generator including the energy storage device, to state 1.

In step S570, the distributed power generation planning system unit 200 sets k, which is a parameter representing a trimming state of a generator including an energy storage device, to obtain an optimal point of the next state in the current state.

In operation S580, the distributed power generation planning system unit 200 determines whether the state of the generator including at least one energy storage device except for renewable energy is changed.

In step S590, the distributed power generation planning system unit 200 sets J _i = g (xi, ui) + J _{i + 1} if the state of the generator including the energy storage device is unchanged as a result of the determination. Where J _i is an index representing the maximum benefit accumulated from the last time i to N (where N is the final stage) at time i, where g (xi, ui) is the profit function. It is the profit generated by the state variable xi representing the state of the generator including the energy storage at time i and the variable ui controlling the generator on and off at time i.

For example, initially i = 23, so J₂₃ (state 1) = g (x₂₃, u₂₃) + J₂₄egoJ₂₃ (state 1) changes all possible states, and when looking for a state in which an optimal revenue is generated, it is possible to know the optimal state for 23 time points from 24 time points.

In step S600, the distributed power generation planning system unit 200 determines whether Ji> Ji_optimal.

In step S610, the distributed power generation plan system unit 200 sets Ji_optimal = Ji and Optimal next state = k since Ji yields a greater profit than Ji_optimal that was previously detected when Ji> Ji_optimal.

In step S620, the distributed power generation planning system unit 200 performs calculation on the state k of each generator and energy storage device, and returns to k = k + 1 when no calculation of all possible states is performed.

In step S630, the distributed power generation planning system unit 200 calculates the optimization by feedback to j = j + 1 for all the states in which the generator (except renewable energy) and storage device state j at time i is specified. Exit when all operations are complete.

In step S640, the distributed power generation planning system unit 200 detects that the maximum of Ji_optimal is changed while changing the state of each generator and energy storage device to the first stay of i = 0.

The distributed power generation plan system unit 200 will be described in more detail with reference to FIG. 7. For example, the distributed power generation plan system unit 200 returns from the stage 23 to the stage 0 using a backward stage calculation method, and all the states (state 1 to state n). ) To determine the best state of cumulative revenue from the final stage.

In step S650, the distributed power generation planning system unit 200, i.e., the point where the objective function is minimum for the states j and k is determined by determining the control variable u and the control variable for the total 24 hours is finally determined. Becomes Finally, we enter the initial state and output the best possible conditions for profit.

An embodiment of the present invention may include a computer readable medium including program instructions for performing various computer-implemented operations. The computer readable medium may include a program command, a local data file, a local data structure, etc. alone or in combination. The media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art to which the present invention pertains without departing from the spirit and scope of the present invention as set forth in the claims below It will be appreciated that modifications and variations can be made.

Claims

In the microgrid operating system,

A microgrid system unit for supplying power to the load of the microgrid, including at least one distributed power supply;

A distributed power generation planning system unit configured to calculate an optimized output condition of the distributed power generation and establish a revenue optimized distributed power generation plan; And

Microgrid operating system including an energy management system for controlling the distributed power source in accordance with the established distributed power generation plan.
The method of claim 1,

And an upper system linking unit that connects the micro grid with a main grid that is a higher system to trade power with the upper system.
The method of claim 1,

The distributed power source includes a microgrid including at least one distributed power source among at least one power source of a boiler, a cogeneration generator, a fuel cell, and a microturbine, at least one renewable energy source of solar power and wind power, and an energy storage device. Operating system.
The method of claim 3,

The distributed power generation planning system unit

The renewable energy source of the distributed power source is set to the maximum output in consideration of constraints including capacity and climate, and calculates the optimum conditions for output of the power generation source and the storage device.
The method of claim 1,

The distributed power generation plan system unit

A database storing at least one of distributed power supply device information, load, power rate, weather and environmental information; And

And a distributed power generation planner configured to select an optimum output of the distributed power supplies and transmit them to the energy management system to maximize the profit of the microgrid using the information stored in the database.
The method of claim 5,

The optimum output of the distributed power supply micro-grid operating system, characterized in that to calculate the optimum conditions that can maximize the profit according to the operating method by turning on or off at least one distributed power constituting the micro grid.
The method of claim 5,

The energy management system unit micro-grid operating system characterized in that for performing the maximum operation of the distributed power supply by controlling the output amount to the distributed power source in accordance with the selected distributed power optimum output.
In the microgrid operating method,

Reading at least one of distributed power supply device information, load, power rate, weather and environmental information;

Calculating an optimal condition capable of maximizing profit according to a driving method by turning on / off at least one distributed power supply constituting the microgrid using the information; And

And performing profit maximization operation of the distributed power supply by controlling the output amount to the distributed power supply according to the calculated optimal condition.
The method of claim 8,

Using the information to calculate at least one distributed power source constituting the micro grid on and off to calculate the optimum conditions that can maximize the profit according to the operating method

Setting a plurality of stages corresponding to time;

Calculating an optimal cumulative revenue generated by transitioning each state of the plurality of distributed power supplies corresponding to each stage;

And calculating an optimum condition of the distributed power supply that is capable of maximum profit among the cumulative revenues calculated corresponding to the stages.
The method of claim 9,

The calculating of the optimal cumulative revenue corresponding to each stage is a microgrid operating method, characterized in that for calculating the cumulative revenue by a backward method (transition) from the final stage to the first stage.
The method of claim 8,

The distributed power source may include a microgrid including at least one distributed power source among at least one power source among a boiler, a cogeneration generator, a fuel cell, and a microturbine, at least one renewable energy source among photovoltaic power generation and wind power generation, and an energy storage device. Operating method.
The method of claim 11,

Using the information to calculate at least one distributed power source constituting the micro grid on and off to calculate the optimum conditions that can maximize the profit according to the operating method

Setting the renewable energy source of the distributed power supply to a maximum output in consideration of constraints including capacity and climate; And

Comprising a step of calculating the optimum conditions that can maximize the return according to the operating method by turning on and off the power source and the storage device.
The method of claim 12,

The storage device is a microgrid operating method, characterized in that to derive an optimal condition in conjunction with the power market price in a specific time period.
The method of claim 12,

The power generation source is a microgrid operating method, characterized in that for deriving the optimum conditions according to at least one of the minimum operating time, the minimum stop time and the power generation cost.
In a recording medium having a program recorded thereon for implementing a method of operating a microgrid,

Reading at least one of distributed power supply device information, load, power rate, weather and environmental information;

Calculating an optimal condition capable of maximizing profit according to a driving method by turning on / off at least one distributed power supply constituting the microgrid using the information; And

And recording a program for implementing a method of operating a microgrid according to the calculated optimum condition, the method comprising maximizing a profit of a distributed power supply by controlling an output amount to the distributed power supply.