KR102285029B1 - Method for operating industrial complex microgrid based on dc using single soc section, program for the same - Google Patents

Abstract

The present invention relates to a microgrid operating method, and more particularly, to a DC-based industrial complex microgrid operating method and program using a single SoC section. A DC-based industrial complex microgrid operation method using a single SoC section according to a preferred embodiment of the present invention includes the steps of: determining, by the EMS, a section to which the SoC of the ESS belongs; And if it is determined that the SoC of the ESS is greater than the lower limit and less than the upper limit, the EMS is expressed by the following equation
[Equation]
PCS*=Load*Gain
here,
PCS*: calibrated PCS yield
Load: Current load
Gain: A value selected by the designer among values between 0.1 and 1
and determining the output amount of the PCS according to the

Description

DC-based industrial complex microgrid operation method using single SoC section and its program

The present invention relates to a microgrid operating method, and more particularly, to a DC-based industrial complex microgrid operating method and program using a single SoC section.

Micro Grid is similar to Smart Grid in that information technology is applied to the power grid to control the amount of power generation, and it requires functions such as generation and consumption forecasting, but its application scale is smaller than that of the smart grid. The difference is that large-scale power transmission facilities are not required because it is relatively small and the location of the power generation source and consumer (power consuming subject) is close.

The US Department of Energy (DOE) defines a micro grid as follows.

It is a group of 'consumers' and 'Distributed Energy Resources (DERs)' interconnected within a clearly defined electrical range, and is a controllable entity with respect to the system, and can be connected and independent from the system.

In other words, a microgrid connects consumers with distributed energy resources (DER) such as wind and solar power through a localized power grid. ) is possible, and if necessary, it is a power grid that can be operated in conjunction with the grid (on-grid).

However, simply connecting consumers and DERs is not enough to configure and operate a microgrid. In the case of wind power generation or solar power generation, this is because the amount of power generation varies according to wind speed or sunlight. and very difficult to manage.

In particular, since microgrids have a small range of power grids, they are more affected by the instability of power quality from renewable power sources. In addition, in order to secure power quality and stability of supply, most microgrids include an Energy Storage System (ESS).

At this time, the ESS contributes to the power quality and stability of the microgrid by storing power when the power supply is oversupply and supplying the stored power to consumers when the demand increases.

1. Korea Patent Publication No. 10-1212343 (Announcement date: 2012.12.13.) 2. Korean Patent Application Laid-Open No. 10-2018-0046174 (published date: 2018.05.08.)

An object of the present invention is to provide stability to power supply and demand within a microgrid.

Further objects and advantages of the present invention will be set forth below and will be learned by way of example of the present invention. Further, the objects and advantages of the present invention may be realized by means and combinations indicated in the claims.

A DC-based industrial complex microgrid operating method using a single SoC section according to a preferred embodiment of the present invention includes the steps of: determining, by the EMS, a section to which the SoC of the ESS belongs; And if it is determined that the SoC of the ESS is greater than the lower limit and less than the upper limit, the EMS is expressed by the following equation

[Equation]

PCS*=Load*Gain

here,

PCS*: calibrated PCS yield

Load: Current load

Gain: A value selected by the designer among values between 0.1 and 1

and determining the output amount of the PCS according to the

Here, when the corrected output amount of the PCS exceeds the rated capacity of the PCS, the rated capacity of the PCS may be regarded as the corrected output amount of the PCS.

The method may further include, when it is determined that the current output amount of the PV converter exceeds the energetic output of the PV converter, limiting the current output amount of the PV converter to the energetic output of the PV converter.

In addition, if it is determined that the SoC of the ESS is less than the lower limit, the EMS is

[Equation]

PCS*=Load*Gain

here,

PCS*: calibrated PCS yield

Load: Current load

Gain: A value selected by the designer among values between 0.1 and 1

It may further include the step of determining the output amount of the PCS according to the

Also, when the corrected output amount of the PCS exceeds the rated capacity of the PCS, the rated capacity of the PCS may be regarded as the corrected output amount of the PCS.

In addition, when it is determined that the current output amount of the PV converter exceeds the energetic output of the PV converter, the method may further include limiting the current output amount of the PV converter to the energetic output of the PV converter.

In addition, the EMS can charge the ESS using all of the output of the PV converter.

Also, the EMS may charge the ESS until the SoC of the ESS reaches a median value of the SoC of the ESS.

In addition, if it is determined that the SoC of the ESS exceeds the upper limit, the EMS is

[Equation]

PCS*=Load*Gain

here,

PCS*: calibrated PCS yield

Load: Current load

Gain: A value selected by the designer among values between 0.1 and 1

It may include the step of determining the output amount of the PCS according to the

Also, when the corrected output amount of the PCS exceeds the rated capacity of the PCS, the rated capacity of the PCS may be regarded as the corrected output amount of the PCS.

In addition, when it is determined that the current output amount of the PV converter exceeds the energetic output of the PV converter, the method may further include limiting the current output amount of the PV converter to the energetic output of the PV converter.

In addition, the EMS may supply all of the output of the ESS to the load.

Also, the EMS may discharge the ESS until the SoC of the ESS reaches a median value of the SoC of the ESS.

In addition, the lower limit of the SoC of the ESS may be 30%.

In addition, the upper limit of the SoC of the ESS may be 70%.

Also, the median value of the SoC of the ESS may be a median value between the upper limit of the SoC of the ESS and the lower limit of the SoC of the ESS.

In addition, the present invention can further provide a DC-based industrial complex microgrid operation program using a single SoC section stored in a medium for performing the DC-based industrial complex microgrid operating method using the single SoC section.

In addition, the present invention can further provide a server system in which the DC-based industrial complex microgrid operation program using the single SoC section is stored and the DC-based industrial complex microgrid operation program using the single SoC section can be transmitted through a communication network. .

In addition, the present invention further provides an EMS system that stores a DC-based industrial complex microgrid operation program using the single SoC section, and operates a real-time microgrid by a DC-based industrial complex microgrid operation program using a single SoC section. can

The present invention can stably supply power to the load using the resources of the microgrid by adjusting the power supply in the microgrid according to the SoC of the ESS.

1 is a schematic diagram of an industrial complex microgrid system to which the present invention is applied.
2 is a flowchart of a microgrid operating method in a single microgrid EMS.
3 is a graph showing a result of applying the algorithm of FIG. 2 to a demonstration site.
4 is a table in which the results of FIG. 3 are numerically summarized.

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed content may be thorough and complete, and the spirit of the present invention may be sufficiently conveyed to those skilled in the art.

Accordingly, the present invention may have various modifications and may have various embodiments, and should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

Meanwhile, in the description of the present invention, if it is determined that a detailed description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

The terms first, second, etc. may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component.

and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

Terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present invention, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, component, part, or a combination thereof described in the specification exists, but one or more other features It is to be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present invention. does not

The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. It should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that there is.

Hereinafter, a microgrid operating method according to a preferred embodiment of the present invention will be described with reference to the accompanying FIGS. 1 to 4 . Hereinafter, in order to clarify the gist of the present invention, descriptions of previously known matters will be omitted or simplified.

Referring to FIG. 1 , the industrial complex microgrid may include a plurality of microgrids. At least one of the plurality of microgrids may be a main microgrid, and the rest may be a sub microgrid. 1 shows that reference numeral “10” denotes a main microgrid, and reference numeral 20-1, 20-2, 20-3, 20-4, 20-5, hereinafter collectively referred to as “20” denotes a sub-microgrid. exemplify the case

The sub microgrid may be divided into unit groups (eg, peak cut type group, base load reduction group, etc.) according to the type of operation. The peak cut group may be a group adopting the peak cut operation method in sub microgrid operation, and the base load reduction group may be a group adopting the load control method. The peak cut operation method may be a method of concentrating power generated in the sub microgrid during the peak time to the peak cut. The load control method may be a method of reducing the load in the sub-microgrid by controlling the load with low importance in consideration of the electricity rate and the load situation.

In the main microgrid and the sub microgrid, a power distribution network may be formed as a lower DC network (2).

In addition, a power distribution network may be formed as an intermediate DC network 3 between unit groups of the sub microgrid.

And, between the main microgrid and the sub microgrid unit group, a power distribution network may be formed as the upper DC network 4 .

Each of the main and sub microgrids may be connected to a utility grid (eg, a distribution network operated by Korea Electric Power Corporation, UG) through the AC network 1 . The main and sub microgrids may be grid-connected. That is, the main and sub microgrids can selectively use the power generated internally and the power provided by the utility grid. When power is directly traded between microgrids between the upper, middle, and upper DC networks (2, 3, 4), a circuit breaker for variably generating a flow path of DC power may be installed. Through the on/off operation of the breaker, an electrical closed loop is formed between the ESSs of the microgrid, which is the party to the power transaction, and power can be transmitted from the selling side to the purchasing side by the potential difference between the ESSs. In this case, the ESS on the side selling power may have a higher potential than the ESS on the side purchasing power. That is, since the power transaction is performed using DC power, the power transaction can be easily performed in one direction. In this case, power transaction between sub-microgrids can be made through the mediation of the main ESS. Specifically, the microgrid that wants to sell power charges the power it wants to sell to the main ESS, and the microgrid that purchases power can receive power from the main ESS. When power transmission and reception of the sub microgrid are simultaneously performed during power transaction, power can be transmitted and received through a closed route via the seller's sub ESS, the main ESS, and the buyer's ESS. The reserve capacity of the main ESS can be an important factor for stable electricity trading.

The sub microgrid 20 includes a photovoltaic power generation 21, a PV converter 22, a PV Converter, a sub ESS 23, a Sub Energy Storage System, an ESS converter 24, an ESS Converter, a load 25, It may include a PCS (26, Power Conditioning System) and a sub EMS (27, Energy Management System).

The PV converter 22 may convert the power output from the photovoltaic power generation to DC/DC and supply it to the lower DC network 2 as a reference DC voltage level. The reference DC voltage level may be, for example, 830 [Vdc]. The reference DC voltage level is the same in the upper, middle and lower DC networks. However, as will be described later, the subject that generates the reference DC voltage level may be different depending on the operation mode. In the standalone mode, the main ESS of the main microgrid and the sub ESS of the sub microgrid can generate the reference DC voltage of the lower DC network 2 in each microgrid. In contrast, only the main ESS of the main microgrid can generate all of the reference DC voltages of the upper, middle, and lower DC networks (2, 3, 4) in the linked mode.

The ESS converter 24 may charge the sub ESS 23 by DC/DC conversion of DC power supplied by the PV converter 22 to the lower DC network 2 . Conversely, the ESS converter 24 may convert the power charged in the ESS 23 to DC/DC and discharge it to the lower DC network 2 at a reference DC voltage level.

The PCS 26 may DC/AC convert power supplied through the lower DC network 2 and supply it to the load 25 .

The load 25 may be a machine used in an industrial complex.

AMI (Advanced Meter Infrastructure) installed in the lower DC network 2 inside the sub microgrid 20 can measure the amount of power received and transmitted through the lower DC network 2 . Here, the power transmission amount may be the amount of electricity that the sub microgrid sells to other sub microgrids or the main microgrid through the DC network, and the amount of power received is the amount the sub microgrid purchases from other sub microgrids or the main microgrid through the DC network. It may be one amount of power. The AMI (Advanced Meter Infrastructure) installed in the AC network 1 inside the sub microgrid 20 can measure the amount of electricity received by the sub microgrid from the utility grid.

The sub EMS 27 may be in charge of overall operation of the sub microgrid. In this case, the sub-microgrid may operate the sub-microgrid based on the measured value or the predicted value. The sub EMS 27 may control the operation of the PV converter 22 , the sub ESS 23 , and the PCS 26 .

Hereinafter, a description will be given of a method in which the sub EMS 27 operates the sub microgrid. In order to clarify the gist of the present invention, an operation operation based on the SoC (State of Charge) of the sub ESS 23 among various operation methods of the sub EMS 27 will be described.

Referring to FIG. 2 , first, the sub EMS 27 may operate the sub microgrid in an independent mode (S1). In this case, the sub microgrid 20 may be linked only to the utility grid UG and may not perform a link operation with other sub microgrids and the main microgrid.

Then, the sub EMS 27 may perform an initial operation sequence (S2). In this case, the sub EMS 27 may drive the PV converter 22 , the sub ESS 23 , the ESS converter 24 , and the PCS 26 in a preset order.

Then, the sub EMS 27 can check the SoC of the sub ESS 23 (S3).

Then, the sub EMS 27 may determine whether the SoC of the sub ESS 23 exceeds 30% (S4).

If it is determined in S4 that the SoC of the sub ESS 23 exceeds 30%, the sub EMS 27 may determine whether the SoC of the sub ESS 23 is "30% < SoC < 70%" ( S5).

If it is determined in S5 that the SoC of the sub ESS 23 is “30% < SoC < 70%”, the sub EMS 27 may calculate the corrected output amount PCS* of the PCS ( S6 ). In this case, the output amount of the corrected PCS may be calculated according to the following equation.

[Equation]

PCS*=Load*Gain

here,

PCS*: calibrated PCS yield

Load: Current load

Gain: A value selected by the designer among values between 0.1 and 1

If the load fluctuation is very severe, the PCS may become overloaded when the PCS performs the load-following operation. And, in response to the occurrence of overload or unintentional reverse power transmission, the sub EMS 27 may stop the operation of the PSC 26 . In other words, the PCS power supply may not be stable in a microgrid with severe load fluctuations.

Accordingly, the present invention can alleviate the load fluctuation by multiplying the current load by a constant less than 1. Accordingly, it may be possible to stably supply power to the PCS 26 despite a sudden load change. The gain can be appropriately selected by the designer in consideration of the load variation of the microgrid site.

Using the corrected PCS output amount PCS* calculated in step S6, the sub EMS 27 may control the PCS 26 so that the PCS 26 outputs the corrected PCS output amount PCS*.

At this time, if the corrected output amount (PCS*) of the PCS exceeds the rated capacity (PCS_cap) of the PCS, PCS_cap may be regarded as the corrected output amount (PCS*) of the PCS (S7).

In addition, when the sub ESM 27 determines that the current output amount PV of the PV converter 22 exceeds the energetic output Conv_cap of the PV converter 22 , the current output PV of the PV converter 22 ) can be limited to the energy output (Conv_cap) of the PV converter 22 (S8). Through this, it is possible to prevent overload of the PV converter 22 and simultaneously allow the PV converter 22 to output stably.

If it is determined in S4 that the SoC of the sub EMS 27 is less than 30%, the sub EMS 27 may calculate the corrected output amount PCS* of the PCS (S9). In this case, the output amount of the corrected PCS may be calculated according to the following equation. The gain can be appropriately selected by the designer in consideration of the load variation of the microgrid site.

[Equation]

PCS*=Load*Gain

here,

PCS*: calibrated PCS yield

Load: Current load

Gain: A value selected by the designer among values between 0.1 and 1

Using the corrected PCS output amount PCS* calculated in step S9, the sub EMS 27 may control the PCS 26 so that the PCS 26 outputs the corrected PCS output amount PCS*.

At this time, if the corrected output amount (PCS*) of the PCS exceeds the rated capacity (PCS_cap) of the PCS, PCS_cap may be regarded as the corrected output amount (PCS*) of the PCS ( S10 ).

In addition, when the sub EMS 27 determines that the current output amount PV of the PV converter 22 exceeds the energetic output Conv_cap of the PV converter 22 , the current output PV of the PV converter 22 ) can be limited to the energy output (Conv_cap) of the PV converter 22 (S11).

In addition, the sub EMS 27 may charge the sub ESS 23 using all of the outputs of the PV converter 22 (S12). In S12, Conv* may be an output amount of the ESS converter 24 to the lower DC network 2 . If Conv* is positive, it means discharging of the sub ESS 23 , and if Conv* is negative, it means charging of the sub ESS 23 . Therefore, by setting PCS* (corrected PCS output amount) to “0” in the formula for calculating Conv* during charging, all of the output PV of the PV converter 22 can be used as the charging power of the sub ESS 23 . .

The sub EMS 27 may repeat S9 to S12 until the SoC of the sub ESS 23 exceeds 50% (S13).

If it is determined that the SoC of the sub ESS 23 exceeds 70% (S14), the sub EMS 27 may calculate the corrected output amount PCS* of the PCS (S15). In this case, the output amount of the corrected PCS may be calculated according to the following equation. The gain can be appropriately selected by the designer in consideration of the load variation of the microgrid site.

[Equation]

PCS*=Load*Gain

here,

PCS*: calibrated PCS yield

Load: Current load

Gain: A value selected by the designer among values between 0.1 and 1

Using the corrected PCS output amount (PCS*) calculated in step S15 , the sub EMS 27 may control the PCS 26 so that the PCS 26 outputs the corrected PCS output amount (PCS*).

At this time, if the corrected output amount (PCS*) of the PCS exceeds the rated capacity (PCS_cap) of the PCS, PCS_cap may be regarded as the corrected output amount (PCS*) of the PCS (S16).

In addition, when the sub EMS 27 determines that the current output amount PV of the PV converter 22 exceeds the energetic output Conv_cap of the PV converter 22 , the current output PV of the PV converter 22 ) can be limited to the energetic output (Conv_cap) of the PV converter 22 (S17).

Then, the sub EMS 27 can discharge the sub ESS 23 by supplying all of the output of the ESS converter 24 to the load (S18). In S18, Conv* may be an output amount of the ESS converter 24 to the lower DC network 2 . If Conv* is a positive number, it means discharging of the sub ESS 23 , and when Conv* is a negative number, it means charging of the sub ESS 23 . Therefore, by setting PV (current output amount of PV converter 22) to “0” in the formula for calculating Conv* during discharge, all of the corrected PCS output (PCS*) can be converted to the output (Conv*) of the PV converter. there is.

The sub EMS 27 may repeat S15 to S18 until the SoC of the sub ESS 23 becomes less than 50% (S19).

As described above, by controlling the SoC of the sub ESS 23 so that the sub ESS 23 is between 30 and 70 % as much as possible, an overheating accident of the sub ESS due to over-discharge/over-charge/ frequent charging/discharging of the sub ESS can be prevented. and the lifespan of the sub ESS may be extended.

Above, 30% is only an example, and the lower limit SoC of the sub ESS can be optimally selected for the site by the designer. And, 70% is only an example, and the upper limit SoC of the sub ESS can be optimally selected by the designer for the site. The above 50% is merely an example, and may be selected as an intermediate value between the upper limit SoC and the lower limit SoC of the sub ESS by a designer.

The main microgrid 10 includes a solar power generation 11, a PV converter 12, a PV Converter, a main ESS 13, a Sub Energy Storage System, an ESS converter 14, an ESS Converter, a load 15, Load, It may include a PCS (16, Power Conditioning System), a main EMS (17, Energy Management System), and a cogeneration generator (18, CHP).

The PV converter 12 may convert the power output from the solar power generation to DC/DC and supply it to the lower DC network 2 at a reference DC voltage level. The reference DC voltage level may be, for example, 830 [Vdc]. The reference DC voltage level is the same in the upper, middle and lower DC networks. However, as will be described later, the subject that generates the reference DC voltage level may be different depending on the operation mode.

The ESS converter 14 may charge the main ESS 13 by DC/DC conversion of DC power supplied by the PV converter 12 to the lower DC network 2 . Conversely, the ESS converter 14 may convert the power charged in the main ESS 13 to DC/DC and discharge it to the lower DC network 2 at a reference DC voltage level.

The PCS 16 may convert the power supplied through the lower DC network 2 to DC/AC and supply it to the load 15 .

The load 15 may be a machine used in an industrial complex.

The AMI (Advanced Meter Infrastructure) installed in the AC network 1 inside the main microgrid 10 can measure the amount of electricity received by the main microgrid from the utility grid.

The main EMS 17 may be in charge of the overall operation of the main microgrid. In this case, the main microgrid may operate the main microgrid based on the measured value or the predicted value. The main EMS 17 may control the operation of the PV converter 12 , the main ESS 13 , and the PCS 16 .

The cogeneration generator 18 is for securing the reserve power of the main microgrid, and may be operated under the control of the main EMS 17 .

Hereinafter, a method in which the main EMS 17 operates the main microgrid will be described. In order to clarify the gist of the present invention, an operation operation based on the SoC (State of Charge) of the main ESS 13 among various operation methods of the main EMS 17 will be described. Since the operation of the main EMS in the independent mode coincides with the operation of the sub EMS, the operation of the main EMS in the independent mode will be described with reference to FIG. 2 again.

Referring to FIG. 2 , first, the main EMS 17 may operate the main microgrid in an independent mode (S1). In this case, the main microgrid 10 may be linked only to the utility grid (UG) and may not perform a linked operation with the sub microgrid.

Then, the main EMS 17 may perform an initial operation sequence (S2). In this case, the main EMS 17 may drive the PV converter 12 , the sub ESS 13 , the ESS converter 14 , and the PCS 16 in a preset order.

Then, the main EMS 17 may check the SoC of the main ESS 13 (S3).

Then, the main EMS 17 may determine whether the SoC of the main ESS 13 exceeds 30% (S4).

If it is determined in S4 that the SoC of the main ESS 13 exceeds 30%, the main EMS 17 may determine whether the SoC of the main ESS 13 is "30% < SoC < 70%" ( S5).

If it is determined in S5 that the SoC of the main ESS 13 is "30% < SoC < 70%", the main EMS 17 may calculate the corrected output amount PCS* of the PCS (S6). In this case, the output amount of the corrected PCS may be calculated according to the following equation. The gain can be appropriately selected by the designer in consideration of the load variation of the microgrid site.

[Equation]

PCS*=Load*Gain

here,

PCS*: calibrated PCS yield

Load: Current load

Gain: A value selected by the designer among values between 0.1 and 1

If the load fluctuation is very severe, the PCS may become overloaded when the PCS performs the load-following operation. And, in response to the occurrence of overload or unintentional reverse power transmission, the main EMS 17 may stop the operation of the PSC 16 . In other words, the PCS power supply may not be stable in a microgrid with severe load fluctuations.

Accordingly, the present invention can alleviate the load fluctuation by multiplying the current load by a constant less than 1. Accordingly, it may be possible to stably supply power to the PCS 16 despite a sudden load fluctuation.

By using the corrected PCS output amount (PCS*) calculated in step S6, the main EMS 17 may control the PCS 16 so that the PCS 16 outputs the corrected PCS output amount (PCS*).

At this time, if the corrected output amount (PCS*) of the PCS exceeds the rated capacity (PCS_cap) of the PCS, PCS_cap may be regarded as the corrected output amount (PCS*) of the PCS (S7).

In addition, if the main ESM 17 determines that the current output amount PV of the PV converter 12 exceeds the energetic output Conv_cap of the PV converter 12, the current output amount PV of the PV converter 12 can be limited to the energy output (Conv_cap) of the PV converter 12 (S8). Through this, it is possible to prevent an overload of the PV converter 12 and simultaneously allow the PV converter 12 to stably output.

If it is determined that the SoC of the main EMS 17 is less than 30% in S4, the main EMS 17 may calculate the corrected output amount PCS* of the PCS (S9). In this case, the output amount of the corrected PCS may be calculated according to the following equation. The gain can be appropriately selected by the designer in consideration of the load variation of the microgrid site.

[Equation]

PCS*=Load*Gain

here,

PCS*: calibrated PCS yield

Load: Current load

Gain: A value selected by the designer among values between 0.1 and 1

Using the corrected PCS output amount (PCS*) calculated in step S9, the main EMS 17 may control the PCS 16 so that the PCS 16 outputs the corrected PCS output amount (PCS*).

At this time, if the corrected output amount (PCS*) of the PCS exceeds the rated capacity (PCS_cap) of the PCS, PCS_cap may be regarded as the corrected output amount (PCS*) of the PCS ( S10 ).

In addition, when the main EMS 17 determines that the current output amount PV of the PV converter 12 exceeds the energetic output Conv_cap of the PV converter 12, the current output PV of the PV converter 12 can be limited to the energy output (Conv_cap) of the PV converter 12 (S11).

In addition, the main EMS 17 may charge the main ESS 13 using all of the outputs of the PV converter 12 (S12). In S12, Conv* may be an output amount of the ESS converter 14 to the lower DC network 2 . If Conv* is positive, it means discharging of the main ESS 13 , and if Conv* is negative, it means charging of the main ESS 13 . Therefore, by setting PCS* (corrected PCS output amount) to “0” in the formula for calculating Conv* during charging, all of the output PV of the PV converter 12 can be used as the charging power of the main ESS 13 . .

The main EMS 17 may repeat S9 to S12 until the SoC of the main ESS 13 exceeds 50% (S13).

When it is determined that the SoC of the main ESS 13 exceeds 70% (S14), the main EMS 17 may calculate the corrected output amount PCS* of the PCS (S15). In this case, the output amount of the corrected PCS may be calculated according to the following equation. The gain can be appropriately selected by the designer in consideration of the load variation of the microgrid site.

[Equation]

PCS*=Load*Gain

here,

PCS*: calibrated PCS yield

Load: Current load

Gain: A value selected by the designer among values between 0.1 and 1

Using the corrected PCS output amount (PCS*) calculated in step S15 , the main EMS 17 may control the PCS 16 so that the PCS 16 outputs the corrected PCS output amount (PCS*).

At this time, if the corrected output amount (PCS*) of the PCS exceeds the rated capacity (PCS_cap) of the PCS, PCS_cap may be regarded as the corrected output amount (PCS*) of the PCS (S16).

In addition, when the main EMS 17 determines that the current output amount PV of the PV converter 12 exceeds the energetic output Conv_cap of the PV converter 12, the current output PV of the PV converter 12 can be limited to the energetic output (Conv_cap) of the PV converter 12 (S17).

Then, the sub EMS 17 can discharge the main ESS 13 by supplying all of the output of the ESS converter 14 to the load (S18). In S18, Conv* may be an output amount of the ESS converter 14 to the lower DC network 2 . If Conv* is positive, it means discharging of the main ESS 13 , and if Conv* is negative, it means charging of the main ESS 13 . Therefore, by setting PV (current output amount of PV converter 12) to “0” in the formula for calculating Conv* during discharge, all of the corrected PCS output (PCS*) can be converted to the PV converter output (Conv*). there is.

The main EMS 17 may repeat S15 to S18 until the SoC of the main ESS 13 becomes less than 50% (S19).

As above, by controlling the SoC of the main ESS 13 so that the main ESS 13 is between 30 and 70% as much as possible, the overheating accident of the sub ESS due to overdischarge/overcharge/frequent charging/discharging of the main ESS can be prevented. and the lifespan of the sub ESS may be extended.

Above, 30% is only an example, and the lower limit SoC of the main ESS can be optimally selected for the site by the designer. And, 70% is only an example, and the upper limit SoC of the main ESS can be optimally selected for the site by the designer. The above 50% is only an example, and may be selected as an intermediate value between the upper limit SoC and the lower limit SoC of the main ESS by a designer. The upper limit Soc/lower limit SoC of the main ESS and the sub ESS may be different or the same. The upper limit Soc/lower limit SoC of the ESS of each of the plurality of microgrids may be different or the same. At this time, an appropriate upper limit Soc/lower limit SoC may be determined according to which product or type of ESS is used.

In addition, the DC-based industrial complex microgrid operating method using a single SoC section according to an embodiment of the present invention is substantially performed by a computer system in which a DC-based industrial complex microgrid operating program using a single SoC section is installed.

That is, the present invention may be provided in the form of an EMS system in which a DC-based industrial complex microgrid operation program using the single SoC section is stored.

In addition, the DC-based industrial complex microgrid operating program using the single SoC section is stored in a server system, and the computer system downloads and installs the DC-based industrial complex microgrid operating program using the single SoC section from the server system. After that, microgrid operation can be performed.

In addition, the DC-based industrial complex microgrid operation program using the single SoC section may be separately stored and provided in a recording medium, and the recording medium may be specially designed and configured for the present invention or common knowledge in the computer software field. It may be known and usable by a vibrator, for example, a magnetic medium such as a hard disk, a floppy disk, and a magnetic tape, an optical recording medium such as a CD, a DVD, and a magneto-optical recording medium capable of both magnetic and optical recording , ROM, RAM, flash memory, etc. may be a hardware device specially configured to store and execute program instructions alone or in combination.

In addition, the DC-based industrial complex microgrid operation program using the single SoC section may be a program composed of a program command, a local data file, a local data structure, etc. alone or in combination, and not only a machine code such as generated by a compiler , may be a program written in high-level language code that can be executed by a computer using an interpreter or the like.

Referring to FIG. 3 , a demonstration site was configured for a total of four factories. That is, four microgrids were configured, and each microgrid was operated according to the algorithm of FIG. 2 . In FIG. 3 , the green bar graph means the usage of utility grid power for each time period of the day, and the blue curve means the average utility grid power usage for each time zone. It can be clearly seen that the utility grid's power usage is low during the heavy loads from 9 am to 6 pm. And, referring to FIG. 4 , in the case of Factory 2 with a large load, it can be seen that the reduction in power consumption of the utility grid is very large.

UG: Utility Grid
1: AC network
2: Sub-DC network
3: Medium DC network
4: Upper DC network
10: main microgrid
11: Solar power
12: PV converter
13: Main ESS
14: ESS converter
15: load
16: PCS
17: Main EMS
18: cogeneration generator
20: sub microgrid
21: solar power
22: PV converter
23: Sub ESS
24: ESS converter
25: load
26: PCS
27: sub EMS

Claims (19)

In the method of operating an industrial complex microgrid comprising a plurality of microgrids equipped with photovoltaic power generation, PV converter, ESS, ESS converter, load, PCS and EMS,
determining, by the EMS, a section to which the SoC of the ESS belongs; and
determining, by the EMS, the output amount of the PCS corrected according to Equation 1 below, if it is determined that the SoC of the ESS is greater than the lower limit and less than the upper limit in the step of the EMS determining the section to which the SoC of the ESS belongs;
[Equation 1]
PCS*=Load*Gain
here,
PCS*: calibrated PCS yield
Load: Current load
Gain: A value selected by the designer among values between 0.1 and 1
when the output amount of the corrected PCS calculated by Equation 1 exceeds the rated capacity of the PCS, considering the rated capacity of the PCS as the output amount of the corrected PCS calculated by Equation 1;
determining, by the EMS, the output amount of the corrected PCS according to Equation 2 below, if it is determined that the SoC of the ESS is less than the lower limit in the step of the EMS determining the section to which the SoC of the ESS belongs;
[Equation 2]
PCS*=Load*Gain
here,
PCS*: calibrated PCS yield
Load: Current load
Gain: A value selected by the designer among values between 0.1 and 1
when the output amount of the corrected PCS calculated by Equation 2 exceeds the rated capacity of the PCS, considering the rated capacity of the PCS as the output amount of the corrected PCS calculated by Equation 2;
when the SoC of the ESS is less than the lower limit, charging the ESS by the EMS using all of the output of the PV converter until the SoC of the ESS reaches a median value of the SoC of the ESS;
determining, by the EMS, an output amount of the corrected PCS according to Equation 3 below, if it is determined that the SoC of the ESS exceeds the upper limit in the step of the EMS determining the section to which the SoC of the ESS belongs;
[Equation 3]
PCS*=Load*Gain
here,
PCS*: calibrated PCS yield
Load: Current load
Gain: A value selected by the designer among values between 0.1 and 1
when the output amount of the corrected PCS calculated by Equation 3 exceeds the rated capacity of the PCS, considering the rated capacity of the PCS as the output amount of the corrected PCS calculated by Equation 3;
When the SoC of the ESS exceeds the upper limit, the EMS sets the discharge amount of the ESS as the output amount of the corrected PCS calculated by Equation 3 until the SoC of the ESS reaches the intermediate value of the ESS. discharging the ESS;
including,
each of the plurality of microgrids is associated with a utility grid,
A distribution network is formed as a lower DC network inside each of the plurality of microgrids,
The PV converter converts the power output by the solar power generation to DC/DC and supplies it to the lower DC network at a reference DC voltage level,
The ESS converter charges the ESS by converting DC power supplied by the PV converter to the lower DC network to DC/DC, and the ESS converter converts the power charged in the ESS to DC/DC to a reference DC voltage level. Discharge to the lower DC network,
The PCS is a DC-based industrial complex microgrid operating method using a single SoC section, characterized in that the DC/AC converts the power supplied through the lower DC network and supplies it to the load.
delete The method of claim 1,
DC-based industrial complex using a single SoC section, further comprising the step of limiting the current output amount of the PV converter to the energetic output of the PV converter when it is determined that the current output amount of the PV converter exceeds the energetic output of the PV converter How to operate a microgrid.
delete delete delete delete delete delete delete delete delete delete The method of claim 1,
DC-based industrial complex microgrid operating method using a single SoC section, characterized in that the lower limit of the SoC of the ESS is 30%.
The method of claim 1,
DC-based industrial complex microgrid operating method using a single SoC section, characterized in that the upper limit of the SoC of the ESS is 70%.
The method of claim 1,
The median value of the SoC of the ESS is a DC-based industrial complex microgrid operating method using a single SoC section, characterized in that it is a median value of the upper limit of the SoC of the ESS and the lower limit of the SoC of the ESS.
A single SoC section stored in a medium for performing the DC-based industrial complex microgrid operating method using the single SoC section of any one of claims 1, 3, 14, 15 and 16 in combination with a computer DC-based industrial complex microgrid operation program using
A server system capable of storing the DC-based industrial complex microgrid operation program using the single SoC section of claim 17 and transmitting the DC-based industrial complex microgrid operating program using the single SoC section through a communication network.
An EMS system that stores the DC-based industrial complex microgrid operation program using the single SoC section of claim 17 and operates the real-time microgrid by the DC-based industrial complex microgrid operation program using the single SoC section.

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