KR102167279B1 - Method for controlling of energy storage system for stabilizing output power of solar power generation system - Google Patents

Abstract

The present invention relates to an output stabilization system and a method for solving the phenomenon that the output power of the solar power generation changes from time to time according to the weather conditions, causing an unreasonable effect on the system. In particular, by controlling the operation of an energy storage system (ESS) It relates to a method of controlling the output of the solar power system to stabilize. According to an embodiment of the present invention, it is possible to stabilize the output of new and renewable energy in consideration of the remaining capacity of the battery in the new and renewable energy storage system, and by performing additional control to minimize the cost required for the energy storage system, economically There is an effect that can reduce the cost.

Description

Energy storage system control method for stabilizing the output of solar power generation system {METHOD FOR CONTROLLING OF ENERGY STORAGE SYSTEM FOR STABILIZING OUTPUT POWER OF SOLAR POWER GENERATION SYSTEM}

The present invention relates to an output stabilization system and a method for solving the phenomenon that the output power of the solar power generation changes from time to time according to the weather conditions, causing an unreasonable effect on the system. In particular, by controlling the operation of an energy storage system (ESS) It relates to a method of controlling the output of the solar power system to stabilize.

As problems such as environmental destruction and resource depletion are problems, interest in systems that store power and efficiently utilize the stored power is increasing. In addition, the importance of renewable energy such as solar power is increasing. In particular, since renewable energy uses infinitely supplied natural resources such as solar power, wind power, and tidal power, and does not cause pollution in the power generation process, research on its utilization is actively underway.

In general, a new renewable energy system is a system that researches and develops new energy sources to solve problems such as energy shortage and environmental pollution, and converts and uses existing fossil energy, or includes sunlight, water, geothermal heat, and biological organisms. Its characteristics are energy that converts and uses renewable energy and future energy sources for a sustainable energy supply system. Such renewable energy systems include wind power generation systems and solar power generation systems.

Conventionally, a power plant generating renewable energy has a problem that greatly affects system reliability due to a large output variability due to the intermittent nature of renewable energy. Therefore, many studies are being conducted on a method of controlling the fluctuation of the output of a power plant that generates renewable energy by using an energy storage system (ESS) to store renewable energy, but the synthetic output is unstable compared to the system condition. And there is a problem that the capacity of the energy storage system is too large.

Globally, investment in expanding and disseminating new and renewable energy such as wind power and solar power is concentrated, but power generation by renewable energy sources with intermittent power generation characteristics is difficult to predict and stable operation of the connected system due to severe output fluctuation characteristics. Will have a great influence on Renewable energy generation power cannot predict a change in the power generation output, and its size is also changed from time to time, and if it is connected to the power system as it is, the quality of the system power is deteriorated. Therefore, the stability of the power system may be adversely affected, and in the worst case, a situation in which the power supply must be stopped may occur.

Conventionally, the use of a bi-directional converter causes a delay in switching between charging and discharging, which causes a problem in instantaneous real-time control. In addition, the control of charging and discharging does not control the amount of charging or discharging power of the PCS (Power Conversion System), but is converted to charging or discharging to manage the power of renewable energy generation. There is a limit.

Accordingly, there is a need for a technology capable of ensuring stable supply and power quality of power generation output with severe output fluctuations while using the power produced by the renewable energy generation device as efficiently as possible.

The present invention has been devised to solve the above-described problem, and an output stabilization system and method thereof for solving the phenomenon that the output power of photovoltaic power generation fluctuates at any time according to the weather condition, thereby causing a strain on the system.

In addition, the present invention is to provide a method of controlling the operation of the energy storage system (ESS) so that the output of the solar power generation system is stabilized.

In addition, the present invention is a device for increasing the reliability of new and renewable energy and its operation by keeping the fluctuation rate below a certain control value and not affecting the system power when the fluctuation of the power generated by the solar power plant is more than a certain value. I want to provide a way.

According to an aspect of the present invention, a system for stabilizing a renewable energy generation output by being connected between a renewable energy generation device and a power system, wherein the power energy supplied from the renewable energy generation device is charged or stored power energy An energy storage system (ESS) for discharging in the direction of the power system; And an energy management system (EMS) for controlling power energy generated by the renewable energy generation device to be transmitted to the power system within a predetermined range of output fluctuation rate.

According to an embodiment of the present invention, there is an effect of stabilizing the output of new and renewable energy in consideration of the remaining capacity of the battery in the renewable energy storage system.

In addition, according to an embodiment of the present invention, there is an effect of economically reducing cost by performing additional control to minimize the cost required for the energy storage system.

1 is a view for explaining an output stabilization system of a photovoltaic power generation system according to a first embodiment of the present invention.
2 is a view for explaining an output stabilization system of the solar power generation system according to the second embodiment of the present invention.
3 is a graph showing the relationship between the expected power generation amount and actual power generation amount for solar power generation.

Since the present invention can apply various transformations and have various embodiments, specific embodiments are illustrated in the drawings and will be described in detail in the detailed description. However, this is not intended to limit the present invention to a specific embodiment, it is to be understood to include all conversions, equivalents, and substitutes included in the spirit and scope of the present invention.

In describing the present invention, when it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted. In addition, numbers (eg, first, second, etc.) used in the description of the present specification are merely identification symbols for distinguishing one component from another component.

In addition, throughout the specification, when one component is referred to as "connected" or "connected" to another component, the one component may be directly connected or directly connected to the other component, but specially It should be understood that as long as there is no opposing substrate, it may be connected or may be connected via another component in the middle. In addition, throughout the specification, when a certain part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated. In addition, terms such as "unit" and "module" described in the specification mean a unit that processes at least one function or operation, which means that it can be implemented as one or more hardware or software, or a combination of hardware and software. .

The present invention is a system for stabilizing a renewable energy generation output by being connected between a renewable energy generation device and a power system, charging power energy supplied from the renewable energy generation device or storing power energy in the power system An energy storage system (ESS) that discharges in the direction; And an energy management system (EMS) for controlling power energy generated by the renewable energy generation device to be transmitted to the power system within a predetermined range of output fluctuation rate.

In this specification, as a renewable energy generation method, mainly solar power generation will be described, but the output stabilization method to be described below is applied in the same or similar manner to other renewable energy generation methods such as wind power, tidal power, and geothermal heat. Of course you can.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Here, FIG. 1 is a view for explaining an output stabilization system of a solar power generation system according to a first embodiment of the present invention, and FIG. 2 is a diagram illustrating an output stabilization system of a solar power generation system according to a second embodiment of the present invention. It is a diagram for explanation, and FIG. 3 is a graph showing a relationship between an expected power generation amount and an actual power generation amount for solar power generation.

First, referring to Figure 1, the output stabilization system of the solar power generation system according to the first embodiment of the present invention, as a photovoltaic device, the photovoltaic power generation module 100; DC-DC converter 110 for a power generation device for converting to have maximum power by performing MPPT (Maximum Power Point Tracking) control on the DC energy generated from the photovoltaic power generation module 100; It includes an inverter 120 for a power generation device that converts DC energy output from the DC-DC converter 110 into AC energy.

In addition, the output stabilization system of the solar power generation system according to the first embodiment of the present invention, as an energy storage system (ESS), the battery 200 for charging or discharging power energy; A battery management system (BMS) 240 that checks the state of charge of the battery 200 and controls a charging or discharging operation; An AC-DC converter for ESS converting AC energy supplied from the inverter 120 for power generation into DC energy; It includes an ESS inverter 220 for converting DC energy discharged from the battery into AC energy.

That is, the output stabilization system of the first embodiment is implemented in an AC (Alternative Current) link method.

At this time, the energy management system 300 controls the charging operation by the AC-DC converter for ESS to be executed when the solar power generation voltage is equal to or higher than the preset reference power generation voltage based on a preset daily estimated power generation amount, and When the photovoltaic power generation voltage is less than the reference power generation voltage, the discharge operation by the ESS inverter 220 is controlled to be executed.

In addition, at this time, the energy management system (EMS) 300 measures the cumulative power generation amount during each preset time period output from the power generation device inverter 120, and measures the cumulative power generation amount measured value during this time period and the time immediately preceding it. When a difference occurs between the measured values of the cumulative power generation amount of the period, the combined output of the output of the power generation device inverter 120 and the output of the ESS inverter 220 is the same as the cumulative power generation amount of the immediately preceding time period, or It can be controlled to have a value within the range of the predetermined output variation rate.

For example, when the cumulative power generation amount for every 10 seconds is measured by EMS in the power generation device inverter 120 and a difference from the measured value occurs for the preceding 10 seconds, the output of the power generation device inverter 120 and the ESS inverter 220 It can be controlled so that the combined output that synthesizes the output becomes the same as the power amount of the previous 10 seconds or increases by 1%, which is a predetermined output change rate. However, after 13:00, it can be controlled to be equal to or 1% decrease from the amount of power 10 seconds before.

Next, referring to Figure 2, the output stabilization system of the solar power generation system according to the second embodiment of the present invention, as a photovoltaic device, the solar power module 100; It includes a DC-DC converter 110 for a power generation device for converting to have the maximum power by performing MPPT (Maximum Power Point Tracking) control on the DC energy generated from the photovoltaic module 100.

In addition, the output stabilization system of the solar power generation system according to the second embodiment of the present invention, as an energy storage system (ESS), the battery 200 for charging or discharging power energy; A battery management system (BMS) that checks the state of charge of the battery 200 and controls a charging or discharging operation; For ESS that converts DC energy supplied from the DC-DC converter 110 for a power generation device into DC energy conforming to the standard of the battery 200 for charging operation or converts DC energy according to the discharging operation of the battery 200 DC-DC converter 210; It includes an ESS inverter 250 for converting direct current energy into alternating current energy for transmission in the direction of the power system 400.

That is, the output stabilization system of the second embodiment is implemented in a DC (Direct Current) link method in which the DC-DC converter 110 for the power generation device and the DC-DC converter 210 for ESS are directly connected.

Accordingly, the energy management system (EMS) 300 controls the DC-DC converter 110 and the ESS DC-DC converter 210 for power generation devices connected by the DC link method to operate in parallel, Based on the expected amount of power generation, the output fluctuation rate per minute of the synthesized output obtained by synthesizing the output of the DC-DC converter 110 for the power generation device and the output of the DC-DC converter 210 for the ESS has a value within the predetermined output fluctuation range Can be controlled.

For example, the energy management system (EMS) 300 may control the power generation to be transmitted to the power system 400 at an output fluctuation rate of 1% or less per minute based on the estimated daily generation amount set by the equipment operator. At this time, solar power is charged with the battery through the ESS DC-DC converter 210. While charging the battery 200, the power system 400 is charged with a constant power through the ESS inverter 250. ) Can be supplied with power.

According to this, solar power generated randomly (that is, in a state in which it is difficult to predict the actual amount of power generated in real time by solar power generation) in a manner in which solar power and battery power are operated in parallel is compensated in real time through battery power. By doing so, it is possible to constantly supply the composite output within the set output variation rate range.

As the output stabilization system in the above description, the DC link connection method may be modified as follows.

For example, according to the third embodiment of the present invention, the energy management system (ESS) 300 is used to convert all of the DC energy output through the DC-DC converter 110 for the power generation device to the ESS DC- By controlling to be input to the DC converter 210, all the power energy generated by the solar power module 100 may be charged to the battery 200.

At this time, the energy management system (ESS) 300 provides a reference transmission power to continuously supply constant power energy to the power system 400 at every preset time period based on the current remaining amount of the battery and the expected daily generation amount. The discharge operation through the ESS inverter 250 may be controlled so that the calculated battery discharge amount required to achieve the calculated and calculated reference power transmission power is calculated and the calculated battery discharge amount is achieved.

Here, the daily expected power generation amount may be predicted by a time period-specific forecast power generation trend curve (see FIG. 3) taking into account the expected weather condition for the day. In this case, as the predicted weather conditions, the predicted amount of sunlight for each time period, the expected amount of sunlight, the expected temperature, the predicted humidity, the expected amount of clouds, and the range of shades in the solar power module generated according to the expected amount of sunlight may be considered. The above-described curve of the expected power generation amount for each time period may be derived as a simulated result in consideration of the above-described various weather conditions.

In addition, the reference transmission power is a value obtained by summing a first unit power amount obtained by dividing the current remaining amount of the battery by each preset time period, and a second unit power amount obtained by dividing the daily estimated power generation amount by each preset time period. Can be calculated.

In this case, the energy management system (EMS) 300, when a difference occurs between the actual amount of power generated by the photovoltaic module 100 at each preset time period and the second unit amount of power, stabilizes the output. The following controls can be performed.

If the actual power generation amount has a value smaller than the second unit power amount, the reference transmission power can be made to have a value within a predetermined output change rate range by reducing the previously set second unit power amount by a predetermined change rate. have.

On the other hand, if the actual generation amount has a larger value than the second unit amount of power, the reference transmission power is made to have a value within a predetermined range of output fluctuation rate by increasing the previously set amount of second unit power by a predetermined change rate. I can.

The above has been described with reference to the embodiments of the present invention, but those of ordinary skill in the relevant technical field variously modify the present invention within the scope not departing from the spirit and scope of the present invention described in the following claims. And it will be easily understood that it can be changed.

Claims (7)

As a system for stabilizing the output of renewable energy generation by being connected between the renewable energy generation device and the power system,
An energy storage system (ESS) for charging power energy supplied from the renewable energy generation device or discharging stored power energy toward the power system; And
Including an energy management system (EMS) for controlling the power energy generated by the renewable energy generation device to be transmitted to the power system within a predetermined output variation rate range,
The renewable energy generation device, a new renewable energy generation module; Including a DC-DC converter for a power generation device for converting to have maximum power by performing MPPT (Maximum Power Point Tracking) control on the DC energy generated from the renewable energy power generation module,
The energy storage system includes: a battery for charging or discharging power energy; A battery management system (BMS) that checks the state of charge of the battery and controls a charging or discharging operation; DC-DC converter for ESS converting DC energy supplied from the DC-DC converter for power generation into DC energy conforming to the standard of the battery or converting DC energy according to the discharge operation of the battery for charging operation; For transmission in the direction of the power system, including an ESS inverter for converting DC energy into AC energy,
The DC-DC converter for the power generation device and the DC-DC converter for the ESS are connected by a DC (Direct Current) link method,
The energy management system,
The DC-DC converter for the power generation device and the DC-DC converter for ESS connected by the DC link method are controlled to be operated in parallel, so that the output of the DC-DC converter for the power generation device and the The output fluctuation rate per minute of the synthesized output obtained by synthesizing the output of the ESS DC-DC converter has a value within the predetermined output fluctuation range,
By controlling all of the DC energy output through the DC-DC converter for the power generation device to be input to the ESS DC-DC converter, all the power energy generated by the renewable energy power generation module is charged with the battery,
Based on the current remaining amount of the battery and the estimated daily power generation, a battery required to calculate the reference transmission power to continuously supply constant power energy to the power system at every preset time period, and to achieve the calculated reference transmission power Controls the discharge operation through the ESS inverter so that the calculated amount of battery discharge is achieved by calculating the amount of discharge,
The daily expected power generation is predicted by a time-specific projected power generation trend curve taking into account the expected environmental conditions for the day,
The energy management system,
The reference transmission power is calculated as a sum of a first unit power amount obtained by dividing the current remaining amount of the battery by each preset time period and a second unit power amount obtained by dividing the daily estimated power generation amount by each preset time period, and ,
When a difference occurs between the actual power generation amount produced by the renewable energy generation module at every preset time period and the second unit power amount,
If the actual amount of power generation has a value smaller than that of the second unit amount of power, by reducing the previously set amount of the second unit amount of power by a predetermined change rate, the reference transmitted power has a value within a predetermined range of output change rate,
When the actual power generation amount has a value larger than the second unit power amount, the reference transmission power is configured to have a value within a predetermined output change rate range by increasing the previously set second unit power amount by a predetermined change rate. That, the output stabilization system of renewable energy generation.
delete delete delete delete delete delete

Images