KR102594004B1 - Microgrid system - Google Patents

Abstract

The present invention includes a data collection step of collecting data on distributed power; A grid connection point status confirmation step of checking the grid connection point status using the data collected through the data collection step; A distributed power supply capacity calculation step of calculating the supply capacity of the distributed power after going through the system connection point status checking step; A scenario determination start step of determining an expected scenario after going through the distributed power supply capacity calculation step; A power generation facility command value determination step of determining a command value of the power generation facility after going through the scenario determination start step; And a power generation facility command value output step of outputting the power generation facility as a command value after going through the power generation facility command value determination step.

Description

Microgrid system{MICROGRID SYSTEM}

The present invention relates to a microgrid system, and more specifically, to a microgrid system, a small-scale power system capable of energy self-sufficiency that supplies power to loads with sufficient power generation through the distribution of a large number of distributed power sources.

Microgrid is a small-scale power system that can maintain continuous power supply to loads only with distributed power within the microgrid by deliberately separating it from the main grid in the event of a serious accident such as a ground fault, short circuit, or large-scale generator failure. A microgrid is composed of distributed power sources, energy storage devices, and loads, and since renewable energy sources within the microgrid have severe output fluctuations, a stable power supply strategy is necessary for the operation of the microgrid.

Distributed power control methods include frequency/voltage control mode (F/V control mode), constant power mode, and droop control mode based on the same principle as the control of existing thermal power generation.

Frequency/voltage control mode is a method of controlling output while maintaining the set frequency and voltage constant. It is suitable when a single distributed power source in the system is operated and must have the ability to satisfy the total demand of the microgrid internal load. do.

The constant output mode is a method of controlling the output to a constant value specified by the microgrid energy management system regardless of the frequency and voltage of the system. In microgrids, micro gas turbines or fuel cells used for combined heat and power generation are mainly used. It is a control method. The droop control mode is a method of controlling on the same principle as the governor of existing thermal power generation by giving a slope of the active power and reactive power values in response to frequency and voltage fluctuations.

When two or more controllable power sources are connected, the droop control mode can automatically determine the load sharing ratio of each power source according to the droop slope in response to load changes, preventing the 'hunting effect' and providing stable distributed power. Operation is possible.

Droop control mode can be divided into feeder flow control mode and unit power control mode depending on the control position. The current control mode is a method of controlling the current of the line in front of the distributed power source with respect to frequency and voltage fluctuations, and the output control mode is a method of controlling the output of the distributed power source with respect to frequency and voltage fluctuations.

Renewable energy sources and active loads within the microgrid are characterized by severe fluctuations and large prediction errors. In addition, a stable operation plan is needed when converting to grid-connected operation and independent operation. Previously, energy storage devices that have faster output dynamics and can charge and discharge than other distributed power sources were installed at the connection points between the main system and the microgrid, and the energy storage devices participate in frequency adjustment and voltage adjustment through droop control.

When the tidal current control mode at the connection point is changed to independent operation, the frequency changes due to the droop coefficient, and if there is no separate frequency recovery function, the changed frequency can be kept constant regardless of the change in load. This can improve power quality by minimizing frequency fluctuations in response to frequent load fluctuations of renewable energy. However, when load fluctuations exceed the maximum output of the energy storage device when connected to the grid, there is a problem with the absence of a control source responsible for supply and demand balance.

In addition, the output control mode at the connection point has a problem in that the utilization of the energy storage device is reduced when connected to the grid.

Republic of Korea Patent No. 10-1277317 (2013.06.24)

Therefore, the present invention was created to solve the above problems, and the problem to be solved by the present invention is to control and manage a plurality of power sources using IT-related technology as a collection of a large number of small-scale distributed power sources and loads. It provides a grid system.

However, the technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly apparent to those skilled in the art from the description below. It will be understandable.

The present invention was created to improve the problems of the prior art as described above, and includes a data collection step of collecting data on distributed power; A grid connection point status confirmation step of checking the grid connection point status using the data collected through the data collection step; A distributed power supply capacity calculation step of calculating the supply capacity of the distributed power after going through the system connection point status checking step; A scenario determination start step of determining an expected scenario after going through the distributed power supply capacity calculation step; A power generation facility command value determination step of determining a command value of the power generation facility after going through the scenario determination start step; and a power generation facility command value output step of outputting the power generation facility as a command value after going through the power generation facility command value determination step.

Additionally, in one embodiment, the expected scenario may be any one of scenario 1, scenario 2, scenario 3, scenario 4, scenario 5, scenario 6, scenario 7, and scenario 8, respectively.

Additionally, in one embodiment, Scenario 1 includes a first step of determining whether the power system is normal; A second step of switching to a grid-connected mode when the power system is normal according to the judgment of the first step; A third step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the second step; A fourth step of determining whether supply remains even if the remaining electricity is absorbed by an energy storage device when the uncontrollable power supply capacity exceeds the microgrid demand according to the judgment of the third step; And a fifth step of selling the electricity if there is still supply even after absorbing the remaining electricity by the energy storage device according to the judgment of the fourth step.

Additionally, in one embodiment, scenario 2 includes a first step of determining whether the power system is normal; A second step of switching to a grid-connected mode when the power system is normal according to the judgment of the first step; A third step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the second step; A fourth step of determining whether supply remains even if the remaining electricity is absorbed by an energy storage device when the uncontrollable power supply capacity exceeds the microgrid demand according to the judgment of the third step; and a 5-2 step of maintaining supply and demand balance through charging if the energy storage device can absorb all of the remaining electricity according to the judgment of the 4th step.

Additionally, in one embodiment, scenario 3 includes a first step of determining whether the power system is normal; A second step of switching to a grid-connected mode when the power system is normal according to the judgment of the first step; A third step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the second step; Step 4-2 of determining whether the supply capacity of controllable power generation facilities is sufficient when the microgrid demand exceeds the uncontrollable power supply capacity according to the judgment in the third step; and a 5-3 step of maintaining supply and demand balance through power generation and discharge when the supply capacity of the controllable power generation equipment is sufficient according to the judgment of the 4-2 step.

Additionally, in one embodiment, scenario 4 includes a first step of determining whether the power system is normal; A second step of switching to a grid-connected mode when the power system is normal according to the judgment of the first step; A third step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the second step; Step 4-2 of determining whether the supply capacity of controllable power generation facilities is sufficient when the microgrid demand exceeds the uncontrollable power supply capacity according to the judgment in the third step; and a 5-4 step of purchasing electricity when the supply capacity of the controllable power generation equipment is insufficient according to the judgment of the 4-2 step.

Additionally, in one embodiment, scenario 5 includes a first step of determining whether the power system is normal; A 2-2 step of switching to an independent mode when the power system is abnormal according to the determination of the first step; A 3-2 step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the 2-2 step; A 4-3 step of determining whether supply remains even if the remaining electricity is absorbed by an energy storage device when the uncontrollable power supply capacity exceeds the microgrid demand according to the judgment of the 3-2 step; And a 5-5 step of blocking the supply if there is still supply even after absorbing the remaining electricity into the energy storage device according to the judgment of the 4-3 step.

Additionally, in one embodiment, scenario 6 includes a first step of determining whether the power system is normal; A 2-2 step of switching to an independent mode when the power system is abnormal according to the determination of the first step; A 3-2 step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the 2-2 step; A 4-3 step of determining whether supply remains even if the remaining electricity is absorbed by an energy storage device when the uncontrollable power supply capacity exceeds the microgrid demand according to the judgment of the 3-2 step; and a 5-6 step of maintaining supply and demand balance through charging if the energy storage device can absorb all of the remaining electricity according to the judgment of the 4-3 step.

Additionally, in one embodiment, scenario 7 includes a first step of determining whether the power system is normal; A 2-2 step of switching to an independent mode when the power system is abnormal according to the determination of the first step; A 3-2 step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the 2-2 step; A 4-4 step of determining whether the supply capacity of controllable power generation facilities is sufficient when the microgrid demand exceeds the uncontrollable power supply capacity according to the judgment of the 3-2 step; and a 5-7 step of maintaining supply and demand balance through power generation and discharge when the supply capacity of the controllable power generation equipment is sufficient according to the judgment of the 4-4 step.

Additionally, in one embodiment, scenario 8 includes a first step of determining whether the power system is normal; A 2-2 step of switching to an independent mode when the power system is abnormal according to the determination of the first step; A 3-2 step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the 2-2 step; A 4-4 step of determining whether the supply capacity of controllable power generation facilities is sufficient when the microgrid demand exceeds the uncontrollable power supply capacity according to the judgment of the 3-2 step; And a 5-8 step of cutting off the load when the supply capacity of the controllable power generation equipment is insufficient according to the judgment of the 4-4 step.

According to one embodiment of the present invention, the electricity produced and the electricity consumed are kept as equal as possible, and when a power grid disturbance occurs, the PCC (Point of Common Coupling) is separated to independently operate the microgrid. It can be operated.

However, the effects that can be obtained from the present invention are not limited to the effects mentioned above, and other effects not mentioned above will be clearly understood by those skilled in the art from the description below. You will be able to.

The following drawings attached to this specification illustrate preferred embodiments of the present invention, and serve to further understand the technical idea of the present invention together with the detailed description of the invention described later. Therefore, the present invention includes the matters described in such drawings. It should not be interpreted as limited to only .
Figure 1 is a conceptual diagram of a microgrid system according to an embodiment of the present invention.
Figure 2 is a flowchart showing the overall processing process of the microgrid system.
Figure 3 is a flowchart showing the overall operation scenario of the microgrid system.
Figure 4 is a flowchart showing the process of determining the distributed power command value in Scenario 1.
Figure 5 is a flowchart showing the process of determining distributed power command values for scenarios 2 and 6.
Figure 6 is a flowchart showing the process of determining distributed power command values for scenarios 3 and 7.
Figure 7 is a flowchart showing the process of determining the distributed power command value for scenario 4.
Figure 8 is a flowchart showing the process of determining the distributed power command value for scenario 5.
Figure 9 is a flowchart showing the process of determining the distributed power command value for scenario 8.
Figure 10 is a graph showing the determination of controllable power supply ability.
Figure 11 is a graph showing determining the supply capacity of a controllable energy storage system (ESS).

Below, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, since the description of the present invention is only an example for structural and functional explanation, the scope of the present invention should not be construed as limited by the examples described in the text. In other words, since the embodiments can be modified in various ways and can take various forms, the scope of rights of the present invention should be understood to include equivalents that can realize the technical idea. In addition, the purpose or effect presented in the present invention does not mean that a specific embodiment must include all or only such effects, so the scope of the present invention should not be understood as limited thereby.

The meaning of terms described in the present invention should be understood as follows.

Terms such as “first” and “second” are used to distinguish one component from another component, and the scope of rights should not be limited by these terms. For example, a first component may be named a second component, and similarly, the second component may also be named a first component. When a component is referred to as being “connected” to another component, it should be understood that it may be directly connected to the other component, but that other components may also exist in between. On the other hand, when a component is referred to as being “directly connected” to another component, it should be understood that there are no other components in between. Meanwhile, other expressions that describe the relationship between components, such as "between" and "immediately between" or "neighboring" and "directly neighboring" should be interpreted similarly.

Singular expressions should be understood to include plural expressions, unless the context clearly indicates otherwise, and terms such as “comprise” or “have” refer to the specified features, numbers, steps, operations, components, parts, or them. It is intended to specify the existence of a combination, and should be understood as not excluding in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

All terms used herein, unless otherwise defined, have the same meaning as commonly understood by a person of ordinary skill in the field to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as consistent with the meaning they have in the context of the related technology, and cannot be interpreted as having an ideal or excessively formal meaning unless clearly defined in the present invention.

Figure 1 is a conceptual diagram of a microgrid system according to an embodiment of the present invention.

Figure 1 shows the overall concept of the microgrid (MG) system (1). Non-Dispatchable DER (100) refers to uncontrollable distributed power sources such as solar power and wind power, and here, DER is an abbreviation for Distributed Energy Resources. refers to small-scale power generation facilities, Dispatchable Generator (200) refers to controllable power sources such as fuel cells and cogeneration generators, Dispatchable ESS (300) refers to energy storage devices such as BESS and electric vehicles (V2G), and Load (400) ) refers to loads from buildings, factories, electric vehicle chargers, etc.

Continuing, PCC (10) is an abbreviation for Point of Common Coupling and means grid connection point (common connection point), and Grid (20) means power system (KEPCO).

Non-Dispatchable DER (100), Dispatchable Generator (200) connected to PCC (10) and Grid (20), Non-Dispatchable DER (100), Dispatchable Generator (200) connected to Dispatchable ESS (300) and Load (400), respectively. It may include a control unit 500 that manages (200), Dispatchable ESS (300), and Load (400) and controls its operation.

Figure 2 is a flowchart showing the overall processing process of the microgrid system, and Figure 3 is a flowchart showing the overall operation scenario of the microgrid system.

As shown in Figures 2 and 3, the present invention includes a data collection step (S100), a grid connection point status check step (S200), a distributed power supply capacity calculation step (S300), a scenario judgment start step (S400), It may include a power generation facility command value determination step (S500) and a power generation facility command value output step (S600).

The data collection step (S100) is a step of collecting data about distributed power. Specifically, distributed generation is a small-scale power generation facility that uses new and renewable energy resources such as solar power or wind power to simplify and increase the efficiency of distribution facilities in inter-regional or intra-regional transmission networks.

The grid connection point status checking step (S200) is a step of checking the grid connection point status using the data of distributed power collected through the data collection step (S100).

The supply capacity calculation step of distributed power (S300) is a step of calculating the supply capacity of distributed power after going through the system connection point status check step (S200).

The scenario judgment start step (S400) is a step where the expected scenario is judged after going through the distributed power supply capacity calculation step (S300). In the scenario judgment start step (S400), the expected scenarios are scenario 1 (#1), scenario 2 (#2), scenario 3 (#3), scenario 4 (#4), scenario 5 (#5), and scenario 6 ( #6), scenario 7 (#7), and scenario 8 (#8).

Scenario 1 (#1) may include the first step (S410), the second step (S420), the third step (S430), the fourth step (S440), and the fifth step (S451).

The first step (S410) is a step of determining whether the power system is normal.

The second step (S420) is a step of switching to the grid-connected mode when the power system is normal as determined in the first step (S410).

The third step (S430) is a step to determine whether the uncontrollable power supply capacity exceeds the microgrid (MG) demand after going through the second step (S420).

The fourth step (S440) determines whether supply remains even if the remaining electricity is absorbed by the energy storage system (ESS) when the uncontrollable power supply capacity exceeds the microgrid (MG) demand according to the judgment of the third step (S430). This is the step to judge.

The fifth step (S451) is a step in which electricity is sold if there is still supply even after the remaining electricity is absorbed by the energy storage system (ESS) according to the judgment in the fourth step (S440).

Specifically, scenario 1 (#1) uses uncontrollable supply power to charge the energy storage system (ESS) as much as possible and sell the remaining electricity.

Scenario 2 (#2) may include the first step (S410), the second step (S420), the third step (S430), the fourth step (S440), and the 5-2 step (S452).

The first step (S410) is a step to determine whether the power system is normal.

The second step (S420) is a step of switching to the grid-connected mode when the power system is normal as determined in the first step (S410).

The third step (S430) is a step to determine whether the uncontrollable power supply capacity exceeds the microgrid (MG) demand after going through the second step (S420).

The fourth step (S440) determines whether supply remains even if the remaining electricity is absorbed by the energy storage system (ESS) when the uncontrollable power supply capacity exceeds the microgrid (MG) demand according to the judgment of the third step (S430). This is the step to judge.

Step 5-2 (S452) is a step of maintaining supply and demand balance through charging if all remaining electricity can be absorbed by the energy storage system (ESS) according to the judgment of step 4 (S440).

Scenario 3 (#3) may include the first step (S410), the second step (S420), the third step (S430), the 4-2 step (S442), and the 5-3 step (S453). there is.

The first step (S410) is a step of determining whether the power system is normal.

The second step (S420) is a step of switching to the grid-connected mode when the power system is normal as determined in the first step (S410).

The third step (S430) is a step to determine whether the uncontrollable power supply capacity exceeds the microgrid (MG) demand after going through the second step (S420).

The 4-2 step (S442) determines whether the supply capacity of the controllable power generation equipment (DER) is sufficient when the microgrid (MG) demand exceeds the uncontrollable power supply capacity as determined in the third step (S430). It's a step. Specifically, in the 4-2 step (S442), when the microgrid (MG) demand exceeds the uncontrollable power supply capacity according to the judgment in the 3rd step (S430), the supply capacity of the controllable power generation equipment (DER) is determined. This is the stage to determine whether it is sufficient to cover the set microgrid (MG) demand.

Step 5-3 (S453) is a step of maintaining supply and demand balance through power generation and discharge when the supply capacity of controllable power generation equipment (DER) is sufficient as determined in step 4-2 (S442). Specifically, scenario 3 (#3) can maintain supply and demand balance through power generation and energy storage system (ESS) discharge.

Scenario 4 (#4) may include the first step (S410), the second step (S420), the third step (S430), the 4-2 step (S442), and the 5-4 step (S454). there is.

The first step (S410) is a step to determine whether the power system is normal.

The second step (S420) is a step of switching to the grid-connected mode when the power system is normal as determined in the first step (S410).

The third step (S430) is a step to determine whether the uncontrollable power supply capacity exceeds the microgrid (MG) demand after going through the second step (S420).

The 4-2 step (S442) determines whether the supply capacity of the controllable power generation equipment (DER) is sufficient when the microgrid (MG) demand exceeds the uncontrollable power supply capacity as determined in the third step (S430). It's a step.

Step 5-3 (S453) is a step of purchasing electricity when the supply capacity of controllable power generation equipment (DER) is insufficient according to the judgment in step 4-2 (S442).

Specifically, in scenario 4 (#4), SOC can be secured by discharging the power source as much as possible, putting the ESS on standby, and charging only during times when electricity purchase costs are low.

Scenario 5 (#5) includes step 1 (S410), step 2-2 (S422), step 3-2 (S432), step 4-3 (S444), and step 5-5 (S455). It can be done including.

The first step (S410) is a step to determine whether the power system is normal.

The 2-2 step (S422) is a step of switching to the independent mode when the power system is abnormal as determined in the first step (S410).

The 3-2 step (S432) is a step to determine whether the uncontrollable power supply capacity exceeds the microgrid (MG) demand after going through the 2-2 step (S422).

Step 4-3 (S444) If the uncontrollable power supply capacity exceeds the microgrid (MG) demand according to the judgment in step 3-2 (S432), the remaining electricity can be supplied even if the remaining electricity is absorbed by the energy storage system (ESS). This is the step to determine whether this remains.

The 5-5 step (S455) is a step of blocking the supply if there is still supply even after the energy storage system (ESS) absorbs the remaining electricity according to the judgment in the 4-3 step (S444).

Specifically, in scenario 5 (#5), overpower generation can be resolved by turning off the power.

Scenario 6 (#6) includes step 1 (S410), step 2-2 (S422), step 3-2 (S432), step 4-3 (S444), and step 5-6 (S456). It can be done including.

The first step (S410) is a step of determining whether the power system is normal.

The 2-2 step (S422) is a step of switching to the independent mode when the power system is abnormal as determined in the first step (S410).

The 3-2 step (S432) is a step to determine whether the uncontrollable power supply capacity exceeds the microgrid (MG) demand after going through the 2-2 step (S422).

Step 4-3 (S444) If the uncontrollable power supply capacity exceeds the microgrid (MG) demand according to the judgment in step 3-2 (S432), even if all remaining electricity is absorbed by the energy storage system (ESS), This is the stage to determine whether there is any supply remaining.

The 5-6 step (S456) is a step to maintain supply and demand balance through charging if the energy storage system (ESS) can absorb all the remaining electricity according to the judgment of the 4-3 step (S444).

Scenario 7 (#7) includes step 1 (S410), step 2-2 (S422), step 3-2 (S432), step 4-4 (S446), and step 5-7 (S457). It can be done including.

The first step (S410) is a step of determining whether the power system is normal.

The 2-2 step (S422) is a step of switching to the independent mode when the power system is abnormal as determined in the first step (S410).

The 3-2 step (S432) is a step to determine whether the uncontrollable power supply capacity exceeds the microgrid (MG) demand after going through the 2-2 step (S422).

Step 4-4 (S446) If the microgrid (MG) demand exceeds the uncontrollable power supply capacity according to the judgment in step 3-2 (S432), it is determined whether the supply capacity of controllable power generation equipment (DER) is sufficient. This is the judgment stage. Specifically, step 4-4 (S446) determines the supply capacity of controllable power generation equipment (DER) when the demand for microgrid (MG) exceeds the uncontrollable power supply capacity as determined in step 3-2 (S432). This is the stage to determine whether it is sufficient to cover the preset microgrid (MG) demand.

Step 5-7 (S457) is a step of maintaining supply and demand balance through power generation and discharge when the supply capacity of controllable power generation equipment (DER) is sufficient as determined in step 4-4 (S446).

Scenario 8 (#8) includes step 1 (S410), step 2-2 (S422), step 3-2 (S432), step 4-4 (S446), and step 5-8 (S458). It can be done including.

The first step (S410) is a step to determine whether the power system is normal.

The 2-2 step (S422) is a step of switching to the independent mode when the power system is abnormal as determined in the first step (S410).

The 3-2 step (S432) is a step to determine whether the uncontrollable power supply capacity exceeds the microgrid (MG) demand after going through the 2-2 step (S422).

Step 4-4 (S446) If the microgrid (MG) demand exceeds the uncontrollable power supply capacity according to the judgment in step 3-2 (S432), it is determined whether the supply capacity of controllable power generation equipment (DER) is sufficient. This is the judgment stage.

Step 5-8 (S458) is a step of cutting off the load when the supply capacity of the controllable power generation equipment (DER) is insufficient according to the judgment in step 4-4 (S446).

Specifically, scenario 8 (#8) can maintain supply and demand balance through load shedding.

The power generation facility command value determination step (S500) is a step in which the command value of the power generation facility is determined after going through the scenario judgment start step (S400). In the power generation facility command value determination step (S500), the command value of distributed power can be determined based on real-time measurement data of components to maintain supply and demand balance. Specifically, an example of command value determination is to calculate the entire load excluding the highest priority load, compare the load with the entire supply capacity, and then cut off the load if the load is less than the supply capacity.

The power generation facility command value output step (S600) is a step in which the power generation facility command value is output after going through the power generation facility command value determination step (S500).

Figure 4 is a flow chart showing the process of determining the distributed power command value of Scenario 1, Figure 5 is a flow chart showing the process of judging the distributed power command value of Scenario 2 and 6, and Figure 6 is a flow chart showing the distributed power command value of Scenario 3 and 7. It is a flowchart showing the process of determining, Figure 7 is a flowchart showing the process of determining the distributed power command value of Scenario 4, Figure 8 is a flowchart showing the process of determining the distributed power command value of Scenario 5, and Figure 9 is a flowchart showing the process of determining the distributed power command value of Scenario 8. This is a flowchart showing the process of determining distributed power command values.

As shown in FIGS. 4 to 9, each figure shows the distributed power command value determination process for specific scenarios 1 to 8.

Referring to FIG. 4, the distributed power command value determination process of scenario 1 (#1) determines the command value of the controllable power source (n=1) (S10) and calculates the minimum output of the nth controllable power source (S11). . At this time, minimum output = current output - output ramp down. Next, set the command value of the nth controllable power source as the minimum output (S12), determine whether n = N (S13), and if n = N, determine the command value of the controllable energy storage device (ESS) (m = 1) (S14), charge the command value of the mth energy storage device (ESS) to the maximum (S15), determine whether m = M (S16), and if m = M, the judgment is terminated.

Again, if n = N, recalculate the minimum output of the nth controllable power source by setting n = n + 1 (S11), and if m = M, store the mth energy by setting m = m + 1. Charge the command value of the device (ESS) to maximum again (S15).

Referring to Figure 5, the distributed power command value judgment process for scenarios 2 (#2) and 6 (#6) calculates the difference between supply and demand (S20) and determines the command value of controllable power (n = 1). (S21), calculate the minimum output of the nth controllable power source (S22). At this time, minimum output = current output - output ramp down. Next, set the command value of the nth controllable power source as the minimum output (S23), determine whether n = N (S24), and if n = N, prioritize the command value of the controllable energy storage system (ESS). At this time, m = 1, the order m of the energy storage device (ESS) is equal to the priority, and the difference between supply and demand is distributed to the mth energy storage device (ESS) (S26). Determine whether there is a difference left to distribute (S27), distribute the command value if there is a difference left to distribute, subtract the distributed command value from the difference between supply and demand (S28), and if there is no difference left to distribute, set the command value to 0. Then (S282), it is determined whether m = M (S29), and if m = M, the judgment is terminated.

Again, if n = N, recalculate the minimum output of the nth controllable power source by setting n = n + 1 (S22), and if m = M, store the mth energy by setting m = m + 1. The difference between supply and demand is redistributed to the device (ESS) (S26).

Referring to Figure 6, the distributed power command value judgment process for scenarios 3 (#3) and 7 (#7) calculates the difference between demand and supply (S30), determines the command value of controllable power (n = 1), and (S31), at this time, n = 1, the order of power n is the same as the priority, and it is determined whether there is a difference left to be distributed (S32). If there is a difference left to be distributed, the command value is distributed, and distribution is made based on the difference between supply and demand. Subtract one command value (S33), and if there is a difference left to distribute, set the command value to the minimum output (S332). Determine whether n = N (S34), and if n = N, determine the command value of the controllable energy storage device (ESS) (m = 1) (S35). If n = N, n = n + 1. Then, it is determined whether there is any difference left to be redistributed (S32).

Next, the difference between supply and demand is distributed to the mth energy storage device (ESS) (S36), and it is determined whether there is a difference left to be distributed (S37). If there is a difference left to be distributed, the command value is distributed, and the supply and demand Subtract the distributed command value from the difference (S38), and if there is no difference left to distribute, the command value is set to 0 (S382).

Next, determine whether m = M (S39), and if m = M, the judgment is terminated. If m = M, m = m + 1 to determine the difference between supply and demand for the mth energy storage system (ESS). Redistribute (S36).

Referring to FIG. 7, the distributed power command value determination process of scenario 4 (#4) determines the command value of the controllable power source (n = 1) (S40) and calculates the minimum output of the nth controllable power source, at this time, Minimum output = current output - Ramp Down (output reduction rate) (S41).

Next, set the command value of the nth controllable power supply as the supply capacity (S42), determine whether n = N (S43), and if n = N, determine the command value of the controllable energy storage system (ESS) (m = 1)(S44), if n = N, set n = n + 1 and calculate the minimum output of the nth controllable power source again.

Next, economical driving is performed considering TOU (S45). Here, TOU is a time-based rate plan, meaning a rate plan that varies by time, and it is determined whether m = M (S46). If m = M, the judgment is terminated. , if m = M, m = m + 1 and sent back to the step of economical operation (S45) considering TOU.

Referring to FIG. 8, the distributed power command value judgment process of scenario 5 (#5) determines the cutoff of uncontrollable power (S50), where k = 1, the order of power, and k is equal to the supply cutoff priority. , update the sum of the uncontrollable supply of the microgrid (MG) excluding the supply capacity of the kth uncontrollable power (S51), and determine whether the uncontrollable power supply capacity exceeds the demand of the microgrid (MG) (S52) , if the uncontrollable power supply capacity exceeds the microgrid (MG) demand, it is determined whether the ESS of the microgrid (MG) can absorb all the remaining electricity (S53), and if absorption is possible, the kth power source is added to the block list. It is added (S54), and the command value is determined using supply and demand balance (charging) logic (Scenario 2) (S55).

If the uncontrollable power supply capacity does not exceed the microgrid (MG) demand, it is determined whether the controllable distributed power supply capacity is sufficient (S532), and if the controllable distributed power supply capacity is sufficient, the kth power is added to the block list. Add (S542), and determine the command value using supply and demand balance (power generation) logic (Scenario 3) (S552). If n = N, the kth power source is excluded from the blocking list, and the sum of the uncontrollable supplies is restored (S5322).

Next, if the ESS of the microgrid (MG) can absorb all the remaining electricity, add the kth power source to the blocking list (S56), determine whether k = K (S57), and control if k = K. It is sent back to the step (S51) of updating the sum of the uncontrollable supply of the microgrid (MG) excluding the impossible power supply capacity.

If k = K, start cutting off the controllable power (S58) and decide to cut off the controllable power (S59). At this time, n = 1, the order of power n is the same as the priority of supply blocking, and the nth controllable power supply is started. Update the sum of the uncontrollable supply of the microgrid (MG) excluding the uncontrollable power area (S591).

Next, it is determined whether the supply capacity of the controllable DER is sufficient (S592), and if the controllable DER can supply the MG demand, the nth power is added to the blocking list (S593), and the command value is set using the supply and demand balance (generation) logic. Decide (Scenario 3) (S594).

Determine whether the supply capacity of the controllable DER is sufficient (S592), and if the microgrid (MG) cannot supply, exclude the nth power from the blocking list (S5922), and determine whether n = N (S5923), n = N, over-generation cannot be blocked (S5924), and if n = N, the sum of the uncontrollable supply of the microgrid (MG) excluding the uncontrollable area of the controllable power is updated again (S591). .

Referring to FIG. 9, the distributed power command value judgment process of scenario 8 (#8) determines blocking of the load (S80), where l = 1, the order of the load l is the same as the blocking priority, and the lth load Update the sum of microgrid (MG) demand excluding electricity (S81).

Next, it is determined whether the sum of the uncontrollable power supply capacity and the controllable power supply capacity exceeds the microgrid (MG) demand (S82), and the sum of the uncontrollable power supply capacity and the controllable power supply capacity is determined to be the microgrid (MG). ) If the demand exceeds, it is determined whether the microgrid (MG) demand exceeds the controllable power supply capacity (S83), and if the microgrid (MG) demand exceeds the controllable power supply capacity, the lth power source is selected. It is added to the blocking list (S84), and the command value is determined using supply and demand balance (power generation) logic (Scenario 3) (S85).

Additionally, when the sum of uncontrollable power supply capacity and controllable power supply capacity does not exceed microgrid (MG) demand. The lth power source is added to the blocking list (S822), and it is determined whether l = L (S824). If l = L, the supply shortage cannot be resolved (S852).

If the microgrid (MG) demand does not exceed the controllable power supply capacity, the lth power is excluded from the blocking list, the sum of the microgrid (MG) demand is restored (S832), and it is determined whether l = L. (S824), if l = L, it is impossible to resolve the supply shortage (S852).

If l = L, the sum of the microgrid (MG) demand excluding the l th load power is sent back to the updating step (S81).

Figure 10 is a graph showing the determination of controllable power supply ability.

With reference to FIG. 10, each formula applied to the graph is listed below.

The minimum generated power of a controllable generator can be expressed by Equation 1 below.

- Formula 1

(This means, respectively, the minimum controllable generated power of the nth controllable generator = the current output of the nth controllable generator - the reduction rate of the nth controllable generator.)

The minimum generated power constraint can be expressed in Equation 2 below.

- 수식 2

- Formula 2

(This means that the minimum controllable generated power of the nth controllable generator is

It means greater than or equal to the minimum generated power of the nth controllable generator.)

The maximum controllable generated power can be expressed by Equation 3 below.

-Formula 3

(This means, respectively, the maximum controllable generated power of the nth controllable generator = the current output of the nth controllable generator + the evaporation rate of the nth controllable generator.)

The maximum generated power constraint can be expressed in Equation 4 below.

- 수식 4

- Formula 4

(This means that the minimum controllable generated power of the nth controllable generator is less than or equal to the rated output (or generator capacity) of the nth controllable generator.)

The unusable supply capacity of a controllable generator can be expressed by Equation 5 below.

- 수식 5

- Formula 5

(This means, respectively, that the unavailable supply capacity of the nth controllable generator is equal to the minimum controllable generation power of the nth controllable generator.)

The available supply capacity of a controllable generator can be expressed in Equation 6 below.

- 수식 6

- Equation 6

Figure 11 is a graph showing determining the supply capacity of a controllable energy storage system (ESS).

With reference to FIG. 11, each formula applied to the graph is listed below.

The state of charge (SOC) that can be discharged can be expressed by Equation 7 below.

- Formula 7

(This means, respectively, the dischargeable SoC of the mth controllable ESS = the current SoC of the mth controllable ESS + the minimum SOC of the mth controllable ESS.)

The ESS output that can be discharged can be expressed by Equation 8 below.

- 수식 8

- Formula 8

(This is, respectively, the dischargeable output of the mth controllable ESS = the dischargeable SoC of the mth controllable ESS / 100 * the battery discharge efficiency of the mth controllable ESS * the PCS discharge efficiency of the mth controllable ESS * the mth controllable ESS) This refers to the battery capacity of the ESS [kWh].)

The upper limit of ESS output that can be discharged can be expressed by Equation 9 below.

- Equation 9

(This means that the dischargeable output of the mth controllable ESS is less than or equal to the PCS discharge rated output (maximum discharge power) of the mth controllable ESS.)

The rechargeable SOC can be expressed by Equation 10 below.

- Equation 10

(This means, respectively, the dischargeable SoC of the mth controllable ESS = the maximum SOC of the mth controllable ESS - the current SoC of the mth controllable ESS.)

The rechargeable ESS output can be expressed by Equation 11 below.

- Equation 11

(This is, respectively, dischargeable output of the mth controllable ESS = chargeable SoC of the mth controllable ESS/100 * battery capacity of the mth controllable ESS [kWh] * (battery charging efficiency of the mth controllable ESS * m This refers to the PCS charging efficiency of the second controllable ESS.)

The rechargeable ESS output can be expressed by Equation 12 below.

- Equation 12

(This means that the charging output of the mth controllable ESS is less than or equal to the PCS charging rated output (maximum charging power) of the mth controllable ESS, respectively.)

In addition, the supply capacity of uncontrollable distributed power of the microgrid (MG) according to an embodiment of the present invention can be expressed by Equation 13 below.

- 수식 13

- Equation 13

(This means the supply capacity of uncontrollable distributed power = current output.)

The uncontrollable supply of the entire MG can be expressed by Equation 14 below.

-Formula 14

(This means the sum of the unusable supply capacity of the controllable power + the sum of the supply capacity of the uncontrollable distributed power, respectively.)

The controllable supply capacity of the entire MG can be expressed by Equation 15 below.

-Formula 15

(This means the sum of the available supply capacity of the controllable power + the sum of the dischargeable power of the controllable ESS, respectively.)

The controllable charging of the entire MG can be expressed by Equation 16 below.

- Equation 16

(This means the sum of the chargeable power of the controllable ESS.)

The sum of demand across MGs can be expressed in Equation 17 below.

- 수식 17

- Equation 17

(This means the sum of the power of the load.)

A detailed description of preferred embodiments of the invention disclosed above is provided to enable any person skilled in the art to make or practice the invention. Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and changes can be made to the present invention without departing from the scope of the present invention. For example, a person skilled in the art may use each configuration described in the above-described embodiments by combining them with each other. Accordingly, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The present invention may be embodied in other specific forms without departing from the spirit and essential features of the present invention. Accordingly, the above detailed description should not be construed as restrictive in all respects and should be considered illustrative. The scope of the present invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are included in the scope of the present invention. The present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. In addition, claims that do not have an explicit reference relationship in the patent claims can be combined to form an embodiment or included as a new claim through amendment after filing.

1: Microgrid system
10:PCC
20: Grid
100: Non-Dispatchable DER
200: Dispatchable Generator
300: Dispatchable ESS
400 : Load
500: Control unit

Claims (10)

A data collection step of collecting data on distributed power;
A system connection point status confirmation step of checking the system connection point status using the data collected through the data collection step;
A distributed power supply capacity calculation step of calculating the distributed power supply capacity after going through the system connection point status checking step;
A scenario determination start step of determining an expected scenario after going through the distributed power supply capacity calculation step;
A power generation facility command value determination step of determining a command value of the power generation facility after going through the scenario determination start step; and
A power generation facility command value output step of outputting the power generation facility as a command value after going through the power generation facility command value determination step,
At the beginning of the scenario judgment,
The expected scenarios are any one of scenario 1, scenario 2, scenario 3, scenario 4, scenario 5, scenario 6, scenario 7, and scenario 8, respectively,
In scenario 1 above,
The first step is to determine whether the power system is normal;
A second step of switching to a grid-connected mode when the power system is normal according to the determination of the first step;
A third step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the second step;
A fourth step of determining whether supply remains even if the remaining electricity is absorbed by an energy storage device when the uncontrollable power supply capacity exceeds the microgrid demand according to the judgment of the third step; and
A fifth step of selling electricity if there is still supply even after all remaining electricity is absorbed by the energy storage device according to the judgment of the fourth step,
The distributed power command value judgment process in scenario 1 above is,
Determine the command value of the controllable power source (n = 1), calculate the minimum output of the nth controllable power source, set the command value of the nth controllable power source as the minimum output, determine if n = N, and determine if n = N. In this case, the command value of the controllable energy storage device is determined (m = 1), the command value of the mth energy storage device is charged to the maximum, and it is determined whether m = M. If m = M, the judgment is terminated,
If n = N, recalculate the minimum output of the nth controllable power source by setting n = n + 1, and if m = M, recalculate the command value of the mth energy storage device by setting m = m + 1. A microgrid system characterized by maximum charging.

Hereinafter, minimum output = current output - output ramp down.
delete delete In claim 1,
In scenario 2 above,
A first step of determining whether the power system is normal;
A second step of switching to a grid-connected mode when the power system is normal according to the judgment of the first step;
A third step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the second step;
A fourth step of determining whether supply remains even if the remaining electricity is absorbed by an energy storage device when the uncontrollable power supply capacity exceeds the microgrid demand according to the judgment of the third step; and
A microgrid system comprising a 5-2 step of maintaining supply and demand balance through charging when all remaining electricity can be absorbed by the energy storage device according to the determination of the 4th step.
In claim 1,
In scenario 3 above,
A first step of determining whether the power system is normal;
A second step of switching to a grid-connected mode when the power system is normal according to the judgment of the first step;
A third step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the second step;
Step 4-2 of determining whether the supply capacity of controllable power generation facilities is sufficient when the microgrid demand exceeds the uncontrollable power supply capacity according to the judgment in the third step; and
A microgrid system comprising a 5-3 step of maintaining supply and demand balance through power generation and discharge when the supply capacity of the controllable power generation facilities is sufficient according to the judgment of the 4-2 step.
In claim 4,
In scenario 4 above,
A first step of determining whether the power system is normal;
A second step of switching to a grid-connected mode when the power system is normal according to the judgment of the first step;
A third step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the second step;
Step 4-2 of determining whether the supply capacity of controllable power generation facilities is sufficient when the microgrid demand exceeds the uncontrollable power supply capacity according to the judgment in the third step; and
A microgrid system comprising a 5-4 step of purchasing electricity when the supply capacity of controllable power generation facilities is insufficient according to the determination of the 4-2 step.
In claim 1,
In scenario 5 above,
A first step of determining whether the power system is normal;
A 2-2 step of switching to an independent mode when the power system is abnormal according to the determination of the first step;
A 3-2 step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the 2-2 step;
A 4-3 step of determining whether supply remains even if the remaining electricity is absorbed by an energy storage device when the uncontrollable power supply capacity exceeds the microgrid demand according to the judgment of the 3-2 step; and
A microgrid system comprising a 5-5 step of blocking the supply if there is still supply even after absorbing the remaining electricity by the energy storage device according to the determination of the 4-3 step.
In claim 7,
In scenario 6 above,
A first step of determining whether the power system is normal;
A 2-2 step of switching to an independent mode when the power system is abnormal according to the determination of the first step;
A 3-2 step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the 2-2 step;
A 4-3 step of determining whether supply remains even if the remaining electricity is absorbed by an energy storage device when the uncontrollable power supply capacity exceeds the microgrid demand according to the judgment of the 3-2 step; and
A microgrid system comprising a 5-6 step of maintaining supply and demand balance through charging when all remaining electricity can be absorbed by the energy storage device according to the judgment of the 4-3 step.
In claim 6,
In scenario 7 above,
A first step of determining whether the power system is normal;
A 2-2 step of switching to an independent mode when the power system is abnormal according to the determination of the first step;
A 3-2 step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the 2-2 step;
A 4-4 step of determining whether the supply capacity of controllable power generation facilities is sufficient when the microgrid demand exceeds the uncontrollable power supply capacity according to the judgment of the 3-2 step; and
A microgrid system comprising a 5-7 step of maintaining supply and demand balance through power generation and discharge when the supply capacity of the controllable power generation equipment is sufficient according to the judgment of the 4-4 step.
In claim 6,
In scenario 8 above,
A first step of determining whether the power system is normal;
A 2-2 step of switching to an independent mode when the power system is abnormal according to the determination of the first step;
A 3-2 step of determining whether the uncontrollable power supply capacity exceeds the microgrid demand after going through the 2-2 step;
A 4-4 step of determining whether the supply capacity of controllable power generation facilities is sufficient when the microgrid demand exceeds the uncontrollable power supply capacity according to the judgment of the 3-2 step; and
A microgrid system comprising a step 5-8 of cutting off the load when the supply capacity of controllable power generation facilities is insufficient according to the determination of step 4-4.

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