KR101964740B1 - control apparatus of grid connected PV and ESS - Google Patents

Abstract

The present invention relates to a control apparatus for grid-connected sunlight and ESS, configured to prevent receiving power through PCS control performance improvement and to shorten the battery charging time by minimizing the difference between a PV power generation amount and an ESS charge amount. The control apparatus for grid-connected sunlight and ESS comprises: a photovoltaic power generation unit which produces electrical energy from sunlight; a power conversion unit which converts the electrical energy produced by the photovoltaic power generation unit from an alternating current power and outputs the same; a load which receives and uses the alternating current power converted by the power conversion unit; a PCS which receives the alternating current power converted by the power conversion unit, converts the received alternating current power into direct current power, and outputs the converted direct current power; an ESS which receives and stores the direct current power converted by the PCS; a PV power meter which is formed at an output terminal of the power conversion unit and measures the power generated by the photovoltaic power generation unit; and a PMS which controls the charge amount of the ESS by commanding the PCS with an effective power value. The PCS receives an ESS charge amount, a PV power generation amount measured by the PV power meter, and an effective power command value of the PMS to control the charge amount of the ESS through calculation, and the PMS calculates the effective power command value based on the PV power generation amount measured by the PV power meter and transmits the calculated effective power command value to the PCS.

Description

Background of the Invention Field of the Invention [0001] The present invention relates to a control apparatus for grid-connected PV and ESS,

The present invention relates to a grid-connected solar and ESS controller, and more particularly, to a grid-connected solar light and ESS controller for preventing power reception, shortening the charging time of the battery, and facilitating troubleshooting.

Generally, an ESS (Energy Storage System) refers to a storage device that stores power generated at an electric power plant or irregularly produced renewable energy, and then transits when power is temporarily low.

Specifically, ESS is a system that stores electricity in an electric power system to supply energy when and where it is needed. In other words, it is a collection of systems that are integrated into one product, such as a conventional secondary battery.

The importance of ESS is emerging as an indispensable device to store unstable power generation energy in solar power generation, which is a rapidly growing new renewable energy, and to supply it to the power grid in a stable manner when necessary.

If there is no ESS, unstable power supply dependent on the sun can cause serious problems such as a sudden shutdown of the power system. Therefore, storage is becoming a very important field in this environment.

These ESSs are installed in electric power generation, transmission, distribution, and customer in electric power system. They are used for frequency regulation, generator output stabilization using new and renewable energy, peak shaving, load leveling, And power supply.

ESS is divided into physical energy storage and chemical energy storage depending on the storage method. Physical energy storage includes pumped storage, compressed air storage, and flywheel. Chemical storage includes lithium ion batteries, lead acid batteries, and Nas batteries.

FIG. 1 is a diagram illustrating a charging operation of an ESS in a conventional grid-connected solar and ESS control apparatus. FIG. 2 illustrates an operation when the power generation amount of the solar power generation unit is greatly reduced in FIG. Fig.

1 and 2, the apparatus for controlling grid-connected solar light and ESS according to the related art includes a solar power generating unit 10 for producing electric energy from sunlight, A load 30 which receives AC power converted from the power converting unit 20 and uses the AC power converted from the AC power supplied from the power converting unit 20, The PCS 40 receives the converted AC power from the PCS 20 and converts the AC power into a DC power and outputs the DC power. The ESS 50 receives and stores the DC power converted by the PCS 40, And a PV power meter 60 configured to measure an amount of power generated by the solar power generator 10.

The size of the charge and discharge amounts of the ESS 50 in the control system of the grid-connected solar and ESS according to the related art is determined according to a command value given from an external PMS (Power Management System).

However, when the ESS supplier and the PMS supplier are different, the communication speed is slow because the PCS and the PMS send and receive the charge amount and the discharge amount information as well as the PCS and the PMS through the serial communication.

Therefore, to cope with rapidly changing PV generation, the existing grid-connected PV and ESS control devices are charged with ESS through PCS with a difference of about 10% in PV generation.

However, when the PV power generation rate changes more rapidly than the given difference within the communication cycle between the PCS and the PMS, there is a problem that the power is supplied from the grid and the ESS is charged through the ESS to generate the power reception.

Also, because PV generation and ESS charge are different, all the PV power generation can not be used for ESS charging, resulting in battery charge time delay and financial damage to power producers. If the PV inverter supplier and the PCS supplier are the same, or if the PMS supplier and the PCS supplier are the same, there is room for problem solving through improvement of the communication speed between products, but if they are different, It is difficult to do.

In order to solve this problem, a problem solution method using an improved controller design is proposed by using the measurement information of the PV power meter 60 at the output terminal of the power conversion unit 20 used in the existing PV / ESS apparatus without adding hardware.

The PV power meter shown in FIGS. 1 and 2 is a meter installed together with the ESS for use in PMS. It receives the PV generation amount information from this instrument and sends the ESS charge amount command from PMS to PCS through serial communication. However, since the amount of information to be exchanged between the PMS and the PCS 40 is large, the information transmission interval is long.

SUMMARY OF THE INVENTION The present invention has been conceived in order to solve the above problems, and it is an object of the present invention to provide a method and system for rapidly changing the PV generation amount upon battery charging by rapidly following the charge amount command information and feedforward control, It is an object of the present invention to provide an apparatus for controlling grid-connected solar cells and ESSs, which can reduce the charging time by minimizing the difference between the PV power generation amount and the ESS charging amount.

In addition, since the PCS receives the ESS charge amount command from the PMS and the power measuring device, the PCS can detect the failure such as the product failure or the communication failure by utilizing the command, so that the system failure can be coped quickly and the system Another object of the present invention is to provide an apparatus for controlling solar-light and ESS.

According to another aspect of the present invention, there is provided an apparatus for controlling grid-connected solar and ESS, comprising: a solar power generator for generating electric energy from sunlight; A load for receiving and using the AC power converted by the power converting unit, a PCS for receiving and converting the AC power converted by the power converting unit to DC power and outputting the DC power, A PV power meter configured to measure a power generated from the solar power generation unit and configured at an output terminal of the power conversion unit; Wherein the PCS controls the ESS charge amount, the PV power generation measured from the PV power meter, and the PMS And the PMS controls the charge amount of the ESS through calculation and the PMS calculates the effective power command value based on the PV power measured from the PV power meter and transmits the command to the PCS .

The grid-connected solar and ESS controller according to the embodiment of the present invention has the following effects.

First, when the ESS battery is charged, the change of PV power generation is quickly followed by the rapid charge command information and feedforward control and reflected to the PCS control, thereby minimizing the difference between the PV power generation amount and the ESS charge amount, Can be shortened.

Second, since the PCS receives the ESS charge command from the PMS and the power meter, it is possible to detect the failure such as the product failure or the communication failure, so that the system failure can be minimized and the damage caused by the power loss can be minimized.

1 is a block diagram for explaining a charging operation of an ESS in a control apparatus for grid-connected solar light and an ESS according to a related art;
FIG. 2 is a diagram for explaining the operation when the power generation amount of the solar power generation unit is rapidly decreased in FIG. 1
FIG. 3 is a schematic view showing a system for controlling a grid-connected solar light and an ESS according to the present invention
Fig. 4 is a circuit diagram schematically showing the power conversion section of Fig. 3
FIG. 5 is a block diagram schematically showing the internal configuration of the PCS of FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the accompanying drawings, detailed description of well-known functions or constructions that may obscure the subject matter of the present invention will be omitted. It should be noted that the same constituent elements are denoted by the same reference numerals as possible throughout the drawings.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary meanings and the inventor is not limited to the meaning of the terms in order to describe his invention in the best way. It should be interpreted as meaning and concept consistent with the technical idea of the present invention. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention, and not all of the technical ideas of the present invention are described. Therefore, It is to be understood that equivalents and modifications are possible.

FIG. 3 is a schematic diagram of a system for controlling grid-connected solar light and an ESS according to the present invention, and FIG. 4 is a circuit diagram schematically showing the power converter of FIG.

As shown in FIG. 3, the apparatus for controlling grid-connected solar and ESS according to the present invention includes a solar power generation unit 110 for generating electric energy from solar light, A load 130 that receives AC power converted by the power converting unit 120 and uses the converted AC power from the power converting unit 120, A PCS 140 that receives the converted AC power and converts the converted AC power into a DC power and outputs the converted DC power, an ESS 150 that receives and stores the DC power converted by the PCS 140, A PV power meter 160 for measuring the power generated from the solar power generator 110 and a PMS controller 160 for controlling the charge amount of the ESS 150 by commanding the PCS 140 with an effective power value, 170), the PCS (140) comprising an ESS charge amount and the PV The PMS 170 receives the PV power generated by the power meter 160 and the active power command value of the PMS 170 to control the charged amount of the ESS 150, And transmits the calculated actual power command value to the PCS 140. The PCS 140 calculates the actual power command value based on the PV power generation amount measured by the PVS controller 140,

Here, the solar power generation unit 110 converts solar energy into electric energy in the state of a plurality of solar cells to generate DC power.

The solar cell collects sunlight incident from the outside to generate electricity, and usually silicon and a composite material are mainly used. Specifically, the solar cell uses a p-type semiconductor and an n-type semiconductor bonded together, and utilizes a photoelectric effect that generates electricity by receiving sunlight. Most of the solar cells are composed of large-area P-N junction diodes, and the electromotive force generated at the opposite ends of the P-N junction diode is connected to an external circuit.

The minimum unit of the solar cell is referred to as a cell. Actually, the solar cell is rarely used as it is. This is because the voltage from one cell is very small, about 0.5V, compared to several tens of volts or several hundreds of volts needed for practical use, so that a large number of unit solar arrays can be connected in series or parallel I am using it. In addition, when the solar cell is used outdoors, it is subjected to various harsh environments. Therefore, a plurality of cells are used as a package in order to protect a large number of cells connected with a necessary unit capacity in a harsh environment.

And a junction box for collecting voltages of the same polarity outputted from the solar cell at one connection point is provided at the rear end of the solar cell.

The power conversion unit 120 includes a plurality of switching devices 121 and a grid interconnect filter 122 as shown in FIG.

The plurality of switching elements 121 are switched on or off based on a PWM (Pulse Width Modulation) signal for controlling the power converter 120 so as to be inputted from the DC voltage Converts the DC voltage into an AC voltage.

The grid coupling filter 122 includes a power conversion device and a system side inductor (Li, Lg) and a filter capacitor (Cf). That is, the grid link filter 122 may be implemented as an LCL filter. Alternatively, the grid interconnect filter 122 may be implemented as an LC filter.

Here, the LCL filter may be represented by a power converter and a system side inductor (Li, Lg) and a filter capacitor (Cf). When the LCL filter is used, a resonance phenomenon occurs by L and C, and a resonance band is formed around a resonant frequency.

The PCS 140 converts the DC power generated by the solar power generation unit 110 into AC power through the power conversion unit 120, converts the DC power into DC power, and stores the DC power in the ESS 150. In addition, the PCS 140 converts the DC power stored in the ESS 150 into AC power and supplies the AC power to the load 130.

The storage information of the ESS 150 is information on the type of battery and the charging time that the capacity efficiency varies according to the magnitude of the electric power at charging / discharging. More specifically, the storage information of the ESS 145 indicates the load capacity, which is information on how much rectification is to be stored or the current charge amount.

The grid information of the load 130 indicates information on the amount of current used by the current load 130. FIG.

5 is a block diagram schematically showing the internal configuration of the PCS of FIG.

3 and 5, the PCS 140 includes a first computing unit 141 for computing and outputting the effective power command value of the PMS 170, the ESS charge amount, and the PV power generation amount, A PI controller 145 for receiving the result of the calculation through the PI controller 141 and compensating for the ESS charge amount to follow the ESS charge amount, a second operation unit for receiving and outputting the output value of the PI controller 145 and the PV generation amount information And a controller 148 for calculating and outputting the ESS charge amount based on the result calculated through the second calculator 147. [

On the other hand, a power generation variation amount calculation section 142 that receives the PV power generation measured by the PV power meter 160 of FIG. 3 and calculates a power generation variation amount, and a power generation variation amount calculation section 142 that receives the power generation variation amount calculated through the power generation variation calculation section 142 A first gain value output unit 144 for outputting a first gain value between the change amount accumulation unit 143 and the first calculation unit 141, And a second gain value output unit 146 for outputting a second gain value between the first calculation unit 142 and the second calculation unit 147.

Accordingly, the present invention rapidly transmits the measurement information of the PV power meter 160 to the PMS 170 and the PCS 140 through the additional communication line facility in a short period so as to convey the measured PV power from the PV power meter 160 , It is used for the voltage command value and feedforward control to output the ESS charge amount through the control unit 148, thereby preventing the reception power generated due to the abruptly varying PV power generation amount.

For example, after receiving the active power command value from the PMS 170 to the PCS 140, when the PV power generation amount becomes smaller than the effective power command value, the cumulative PV power generation variation accumulated in the power generation amount accumulation unit 143 is valid The control unit 148 can follow the change of the effective power command value in a shorter cycle by adding the power command value.

Here, if the PV power generation variation amount is used for feedforward control, it is possible to improve the response speed of the entire controller since it can affect the system prior to the PI controller 145. Accordingly, it is possible to improve various performances by using the weight values, i.e., the first and second gain values. In addition, since the active power command value received from the existing PMS is used together without using only the short-term effective power command value, the command value of the ESS charge amount can be duplicated, thereby improving the stability of the control system, Detection and so on.

In addition, since the measurement information of the PV power meter 160 is transmitted to the PCS 140 and the PMS 170 in a duplex manner, the present invention can secure the control response speed, Since the command is used in parallel, the charge amount command value can be duplicated, so that the stability of the system can be improved and the fault detection using the same can be facilitated.

Here, various performance improvements are possible depending on the command value and the method of processing the power meter information added for feedforward control.

The change amount accumulation unit 143 accumulating the power generation change amount calculated by the power generation change amount calculation unit 142 receives the effective power command value from the PMS 170 and before the next effective power command value is received, ) And the PCS 140 during the data communication period.

In addition, since the present invention can rapidly follow the change of the PV power generation amount during the battery charging of the ESS 150 through the quick charge command information and the feedforward control and reflect it to the control of the PCS 140, Minimizing the difference in ESS charge can shorten the charge time of the battery.

Meanwhile, the solar power generation unit 110 generates a difference between the actual power generation amount and the reference power generation amount depending on the temperature, the weather, the location of the installed area, the season, and the climate. That is, since the actual power generation pattern of the solar power generation unit 110 is different from day to day, the present invention measures it in the PV power meter 160, calculates the power generation change amount in the PCS 140, and accumulates the power generation amount to calculate the ESS charge amount .

For this, the PV change amount during the data communication period of the PMS 170 and the PCS 140 is calculated by the following equation (1). When expressed as an equation,

. We can improve various performance by using weight.

This makes it possible to prevent power reception because it has control capability to cope with rapidly changing PV power generation, and it is possible to improve the ESS charging speed by reducing difference between ESS charge amount and PV generation amount.

Embodiments of the present invention include computer readable media including program instructions for performing various computer implemented operations. The computer-readable medium may include program instructions, local data files, local data structures, etc., alone or in combination. The media may be those specially designed and constructed for the present invention or may be those known to those skilled in the computer software.

Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape, optical recording media such as CD-ROMs and DVDs, magneto-optical media such as floppy disks, and ROMs, And hardware devices specifically configured to store and execute the same program instructions. Examples of program instructions include high-level language code that can be executed by a computer using an interpreter, as well as machine accords such as those produced by a compiler.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Modification is possible. Accordingly, the spirit of the present invention should be understood only in accordance with the following claims, and all equivalents or equivalent variations thereof are included in the scope of the present invention.

110: solar power generation unit 120: power conversion unit
130: load 140: PCS
150: ESS 160: PV Power Meter
170: PMS

Claims (5)

A solar photovoltaic portion for producing electric energy from sunlight,
A power conversion unit for converting electric energy produced from the solar power generation unit from an AC power source and outputting the converted power;
A load for receiving and using the AC power converted by the power converting unit,
A PCS that receives the AC power converted by the power conversion unit and converts the converted AC power into a DC power and outputs the DC power,
An ESS for receiving and storing the DC power converted by the PCS,
A PV power meter configured to measure an electric power produced from the solar power generation unit and configured at an output terminal of the power conversion unit;
And a PMS for controlling the charge amount of the ESS by commanding the PCS with an effective power value,
The PCS receives the ESS charge amount, the PV generation amount measured from the PV power meter, and the PMS active power command value to control the charge amount of the ESS,
The PMS calculates the effective power command value based on the PV power measured from the PV power meter and transmits the command to the PCS,
The PCS includes a first computing unit for computing and outputting an effective power command value of the PMS, an ESS charge amount, and the PV power generation amount, a PI controller for receiving a result calculated through the first computing unit and compensating for the ESS charge amount, A second arithmetic unit for receiving and outputting the output value of the PI controller and the PV generation amount information, and a controller for calculating and outputting the ESS charge amount based on the result calculated through the second arithmetic unit And a controller for controlling the grid-connected solar and ESS. delete The power generation system according to claim 1, wherein the PCS includes a power generation variation amount calculation unit that receives the PV power generation amount and calculates a power generation variation amount, and a variation amount accumulation unit that receives and accumulates the power generation variation amount calculated through the power generation variation calculation unit Of grid-connected solar and ESS. 4. The power conversion apparatus according to claim 3, further comprising: a first gain value output unit for outputting a first gain value between the variation accumulation unit and the first calculation unit; and a second gain value output unit for outputting a second gain value between the power generation variation amount calculation unit and the second calculation unit. And a gain value output unit for outputting an output signal of the grid-connected solar and ESS. The power generation apparatus according to claim 3, wherein the change amount accumulation unit for accumulating the power generation variation amount calculated by the power generation variation amount calculation unit is a PV power generation unit for receiving the active power command value from the PMS and receiving the next active power command value during the data communication period of the PMS and the PCS. And the ESS is a value obtained by accumulating the amount of change.

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