KR101745419B1 - A solar power system with the bypass circuit for defective photovoltaic modules - Google Patents

Abstract

The present invention relates to a photovoltaic power generation system having a PV bad module bypass circuit for detecting a bad module for a PV module installed in a photovoltaic power generation so that the normal efficiency and operation of the photovoltaic power generation are continuously maintained, A plurality of PV modules connected to the solar cell array; A sensor module installed in each of the PV modules for detecting a current or a voltage of the PV module and bypassing the PV module; And receiving a detection value from the sensor module to obtain a probability distribution of detection values, and if the detection value of the sensor module is less than a predetermined range from the probability distribution, A configuration including a main control unit to be transmitted is prepared.
By determining the defective module by using the deviation of the voltage and the current of each PV module by the above-described PV system, even if the sunshine amount of the sunlight rapidly changes according to the state of the air such as the season, Can be detected more robustly.

Description

Technical Field The present invention relates to a photovoltaic power generation system having a photovoltaic power generation system and a defective photovoltaic module,

The present invention relates to a photovoltaic power generation system having a PV bad module bypass circuit for detecting a bad module for a PV module installed in a photovoltaic power generation so that normal efficiency and operation of the photovoltaic power generation are continuously performed.

The present invention also relates to a photovoltaic power generation system including a PV bad module bypass circuit for determining a relative difference between a deviation of each module and a deviation of a module using a standard deviation of a voltage and a current, will be.

Increased interest in and investment in renewable energy has led to the rapid development of the solar energy industry. In the last decades, the demand for renewable energy has increased significantly due to the disadvantages of fossil fuels and the greenhouse effect. Among various types of renewable energy sources, solar energy has become the most promising and attractive due to advances in power electronics technology. Photovoltaic (PV) power supplies are used in many applications today due to the advantages of no maintenance and no pollution.

Photovoltaic power generation system is a power generation facility that operates in a natural environment over a long period of time for 20 years or more, so it is necessary to maintain long-term reliability and avoid accident risk. In particular, if an abnormal condition occurs, if the measures are not taken immediately, there is a need to develop a technology capable of reducing the loss because the generation amount and the economic loss may occur.

However, due to the high initial cost and limited life span of the PV module, continuous management is required. However, it is practically impossible to manage each module in real time with limited human resources. Therefore, it is necessary to monitor each module in real time and to supervise and replace the defective module.

In order to solve the above problems, a solar power generation system capable of bypassing a defective module has been developed (Patent Documents 1 and 2). The prior art detects the amount of light or voltage in the solar cell modules and, if they are smaller than the reference value, determines that the module is a defective module and bypasses it.

However, solar power varies greatly depending on the amount of sunshine. In particular, the amount of sunlight fluctuates rapidly depending on the atmospheric conditions such as seasons, time zones, and clouds. If the reference value is set to a fixed value in a situation where the amount of sunshine fluctuates, there is a problem that the solar cell module is detected as being excessively excessive or too small.

Korean Registered Patent No. 10-1279554 (Registered on June 21, 2013) Japanese Patent Application Laid-Open No. 2000-174308 (published on June 23, 2000)

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a PV sensor unit for measuring the generated voltage, current, and temperature of a PV module and transmitting measured values to the main controller, And a main controller for collecting the voltage, current and temperature of each of the modules, judging the presence or absence of a bad module, and commanding the operation of the bypass relay in the PV sensor upon occurrence of a bad module. And to provide a photovoltaic power generation system.

It is also an object of the present invention to provide a photovoltaic power generation system having a PV bad module bypass circuit for determining a relative difference between deviations of different modules by using standard deviation of voltage and current, .

In order to achieve the above object, the present invention provides a photovoltaic power generation system having a PV bad module bypass circuit, comprising: a solar cell array comprising a plurality of PV modules connected in series; A sensor module installed in each of the PV modules for detecting a current or a voltage of the PV module and bypassing the PV module; And receiving a detection value from the sensor module to obtain a probability distribution of detection values, and if the detection value of the sensor module is less than a predetermined range from the probability distribution, And a main controller for transmitting the main controller.

Further, the present invention provides a photovoltaic generation system having a PV bad module bypass circuit, wherein the sensor module includes a relay to directly connect or bypass the output of the installed PV module with an adjacent PV module Bypass circuit; A detection circuit for detecting voltage and current of the PV module; A communication unit for communicating with the main controller; And a central processing unit (CPU) for controlling the direct connection or the bypass connection of the PV module by transmitting the detected values detected by the detection circuit to the main controller, receiving an instruction from the main controller, and controlling the relay of the bypass circuit And a control unit.

Further, the present invention provides a photovoltaic generation system having a PV bad module bypass circuit, wherein the main controller has a microprocessor and receives voltage and current of each PV module transmitted by the RS-485 communication with the sensor module And a program for determining whether or not each PV module is defective. The malfunctioning module determination program is executed by the microprocessor to perform a malfunctioning module detection and a detour operation.

Further, the present invention is a solar power generation system including a PV bad module bypass circuit, wherein the main controller obtains an average value and a standard deviation of voltage or current of each PV module, calculates a mean value and a standard deviation of the voltage or current of each PV module, Determining a PV module detected by a voltage or a current falling within the defective range as a defective module by obtaining a probability density function and finding a defective range having a predetermined value or less in a normal distribution curve represented by the probability density function; .

In addition, the present invention relates to a solar power generation system comprising a PV bad module bypass circuit, the main control groups voltage V _i of the PV module and the current I _i is the failure to enter the range of the voltage V _i of the PV module and the current I _i Is less than half the average value of m _v / 2 and m _c / 2, it is determined that the corresponding PV module is defective.

As described above, according to the photovoltaic generation system having the PV bad module bypass circuit according to the present invention, by monitoring each photovoltaic module (PV module) to detect and bypass the bad module, the monitoring and replacement Thereby enabling the solar power to be continuously operated with normal efficiency and operation.

Further, according to the photovoltaic generation system having the PV bad module bypass circuit according to the present invention, the bad module is determined by using the deviation of the voltage and the current of each PV module, Accordingly, even if the amount of sunshine changes rapidly, the defective module can be detected more robustly.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of the configuration of a photovoltaic generation system having a PV bad module bypass circuit according to an embodiment of the present invention; FIG.
2 is a block diagram of a configuration of a sensor module according to an embodiment of the present invention;
FIG. 3 is a view illustrating a connection structure of a bypass circuit of a sensor module according to an embodiment of the present invention. FIG.
4 is a block diagram of a main controller according to an embodiment of the present invention;
5 is a circuit configuration diagram of a sensor module according to an embodiment of the present invention.
6 is a temperature detection circuit diagram according to an embodiment of the present invention;
7 is a current detection circuit diagram according to an embodiment of the present invention.
8 is a voltage detection circuit diagram according to an embodiment of the present invention.
9 is a flowchart illustrating a method for determining whether a PV module is defective according to an exemplary embodiment of the present invention.
10 is a graph showing a normal distribution curve and a defective range for voltage and current, respectively, according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings.

In the description of the present invention, the same parts are denoted by the same reference numerals, and repetitive description thereof will be omitted.

First, the configuration of a photovoltaic power generation system having a PV bad module bypass circuit according to an embodiment of the present invention will be described with reference to FIG.

1, a photovoltaic power generation system for practicing the present invention includes a solar cell array 10 constituted by a PV module 11, a plurality of photovoltaic modules 10 installed in each PV module 11, A plurality of sensor modules 20 for sensing a faulty PV module 11 and for bypassing a faulty PV module 11 and a sensor module 20 for detecting a faulty module and controlling the bypass, (30). Further, the output of the solar cell array 10 is connected to a connection part or an inverter.

The solar cell array 10 is composed of a plurality of PV modules (solar cell modules) 11.

Each PV module 11 is composed of a plurality of solar cells (not shown) as in the conventional solar cell module. Each solar cell generates power by the photovoltaic effect when sunlight is applied, and each of the PV modules 11 composed of a plurality of solar cells merges and outputs power generated in the solar cells.

The PV module 11 is for generating electricity by condensing solar light incident from the outside, and silicon and a composite material are usually used mainly. Specifically, the PV module 11 uses a P-type semiconductor and an N-type semiconductor bonded together, and uses the photoelectric effect to generate electricity by receiving sunlight. Most of the PV modules 11 are formed 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 PV module 11 is referred to as a cell. Actually, the solar cell is rarely used as it is. This is because the voltage required from one cell is very small, about 0.5V, compared to several tens of V or several hundreds of V, which is necessary for practical use. Therefore, a plurality of unit solar cells can be connected in series or parallel . In addition, when the solar cell array 10 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 plurality of cells connected with a necessary unit capacity in a harsh environment.

Next, the sensor module 20 is installed in each of the PV modules 11, measures the voltage, current, and temperature of the corresponding PV module 11, and outputs the result of measurement to the bypass circuit 21 of the PV module 11 . That is, one sensor module 20 is associated with each PV module 11.

2, the sensor module 20 includes a bypass circuit 21 for bypassing the output of the corresponding PV module 11, a detection circuit 22 for measuring voltage, current, temperature, etc., a main controller 30, A communication unit 23 for communicating with the control unit 25, and a control unit 25 including a CPU.

The bypass circuit 21 is a circuit that is provided to correspond to each PV module 11 and is a circuit that directly connects or bypasses (bypasses) each PV module 11 to / from an adjacent PV module 11 in series. The bypass circuit 21 is controlled by the main controller 30 so that the direct connection or bypass connection is selectively controlled.

Preferably, the bypass circuit 21 is provided with a relay so that the flow of the current can be controlled by the control unit 25. [

Next, the detection circuit 22 is composed of circuits for detecting voltage, current, temperature, and the like. The voltage, current, temperature, and the like measured by the detection circuit 22 are transmitted to the main controller 30 and used to detect whether or not the PV module 11 is defective.

Next, the control unit 25 is provided with a CPU or the like to control the sensor module 20, and the communication unit 23 is a circuit that communicates with the main controller 30. [ The control unit 25 transmits the values measured by the detection circuit 22 to the main controller 30 through the communication unit 23 or determines whether the PV module 11 is detouring from the main controller 30 ).

That is, the control unit 25 transmits the values measured by the detection circuit 22 to the main controller 30, receives the command of the main control unit 30, and controls the relay of the bypass circuit 21, ).

Next, the main controller 30 receives (or fetches) the measured values from the sensor module 20, and judges whether each PV module 11 is defective by using the measured values. That is, the main controller 30 receives the voltage, current, and temperature measured by the sensor module 20. Then, a distribution for these values is obtained, and the PV module 11 deviating from the predetermined distribution range is detected as defective.

Further, the main controller 30 commands the sensor module 20 to bypass the PV module 11 determined to be defective. That is, the main controller 30 controls the bypass circuit 21 of the failed PV module 11 to bypass the PV module 11, thereby removing the PV module 11 from the series connection. Specifically, when it is determined that the PV module 11 is a bad module, the bypass path is formed such that the corresponding PV module is excluded from the connection of the plurality of PV modules 11 of the solar cell array. If it is determined that the PV module 11 is normally operating, an electrical connection path is formed in series with the adjacent solar cell modules.

That is, the main controller 30 controls the sensor module (not shown) so that each PV module 11 is electrically connected to the adjacent PV module 11 or a bypass path is provided so as not to be connected to the adjacent PV module 11, 20).

Next, the output from the solar cell array 10, that is, the direct current, is collected in a connection unit (not shown) and output to an inverter (not shown).

A connection unit (not shown) is provided for connecting a plurality of solar cell arrays 10 in series or in parallel. In addition, the connection panel is equipped with a DC power switch, an output terminal switch, a molded case circuit breaker (MCCB), a bus bar or a terminal block, and a safety switch such as a magnetic switch, a diode and a power fuse, Devices for delivery may be provided.

An inverter (not shown) integrates the DC power received from the solar cell array 10 as a parallel group into one DC power and converts it into AC power for use as commercial power. The AC power output from the inverter is supplied to the load of the consumer through the power system or water generators.

Next, a bypass method by the bypass circuit 21 of the solar cell array 10 according to an embodiment of the present invention will be described with reference to FIG.

As described above, the solar power generation system of FIG. 1 constitutes a plurality of bypass circuits 22 provided corresponding to a plurality of PV modules 11. If the main controller 30 determines that each PV module 11 is normal and supplies the accumulated power to the PV module 11 at the next stage if it is normal and bypasses the PV module 11 if the PV module 11 is abnormal, ). ≪ / RTI >

As shown in Fig. 3, the bypass circuit 21 operates as a kind of switch. As described above, the relay is operated under the control of the control unit 25, and the switch of the bypass circuit 21 is operated. On the other hand, the control signal of the control unit 25 is a signal driven by a command transmitted from the main controller 30. [ That is, the main controller 30 receives the voltage, current, and temperature measured by the sensor module 20, and determines whether or not each PV module 11 is defective based on these distributions.

Next, the configuration of the main controller 30 according to an embodiment of the present invention will be described in more detail with reference to FIG.

4, the main controller 30 includes a microprocessor and collects voltages, currents, and temperatures of the respective PV modules transmitted by the RS-485 communication with the sensor module 20, And a program for judging the presence or absence of the module. Then, the main controller 30 causes the microprocessor to perform the bad module determination program, and performs the bad module detection and the bypass operation.

In addition, the main controller 30 commands the operation of the bypass relay of the sensor module 20 upon occurrence of a bad module, generates an alarm to the outside, and allows the manager to take measures accordingly.

Next, a configuration of the sensor module 20 according to an embodiment of the present invention will be described with reference to Figs. 5 to 8. Fig.

The sensor module 20 monitors the temperature rise by attaching a sensor to the outside of the terminal box of the PV module and measures a voltage / current to secure a bypass through the relay when an abnormal situation occurs. 485 communication.

Detection time of the bypass circuit detects the sensor abnormal condition of the terminal box so that the operation time of the bypass relay is 0.5 seconds or less.

As shown in FIG. 5, one sensor module 20 is attached to the module terminal box for each PV module 11, and is used in connection with the existing PV terminal box. It is connected to main controller 30 through RS-485 communication and is connected with 4 lines of power (+, -) communication (D +, D-).

The operation of sub modules such as various sensors monitors the temperature, voltage and current of each PV module, activates the relay when an abnormal condition occurs, and transmits the result to the main controller (30). The set values of temperature and voltage / current are transmitted from the main controller 30 and stored and used.

Further, as shown in Fig. 6, the sensor module 20 or the detection circuit 22 includes a temperature detection circuit for detecting the temperature. When the temperature of the terminal box of the PV module is sensed by the semiconductor TMP-36 sensor, it is judged that the module is overheated and the relay is switched and connected through the bypass circuit.

Also, as shown in FIG. 7, preferably, the sensor module 20 detects the current with a DC current sensor (for example, using the ACS758LCB-050U). If the current of the individual PV module is measured and it is relatively small compared to other modules or the current does not flow, it is judged that the module is defective and the relay is connected and connected through the bypass circuit.

Further, as shown in Fig. 8, preferably, the sensor module 20 measures the voltage of the individual PV module 11. Fig. Thus, the main controller 30 judges that the module is defective when the voltage of the corresponding PV module is relatively small as compared with other modules. Thus, the relay is switched and connected through a bypass.

On the other hand, the controller 25 of the sensor module 20 normally scans each sensor (or detection circuit), communicates with the main controller 30, and lights the OPER_GRN lamp. The input of each sensor is monitored and compared with the alarm level input from the main controller 30 through the communication. When an abnormal condition occurs, the bypass relay is operated and the OPER_RED lamp is operated to display the alarm status. When the abnormal state is released, the relay is returned.

Next, a method for determining whether or not a PV module of the main controller 30 according to an embodiment of the present invention is defective will be described with reference to FIGS. 9 to 10. FIG.

As shown in FIG. 9, first, in the PV system, n is the number of the PV modules 11, V _{i is} the voltage read from the PV module i, and I _i is the current.

[Equation 1]

&Quot; (2) "

Here, m _v and m _c represent an average value of voltage and current, respectively.

Next, the average value of the module and the deviation of the measured voltage and current of each module are obtained.

&Quot; (3) "

&Quot; (4) "

Next, the standard deviation of voltage and current is obtained.

&Quot; (5) "

&Quot; (6) "

Next, when that according to a normal distribution ^{_{N (m v, σ v 2}} ), N (m c, σ c 2) the probability density function is expressed as the following mathematical expression.

&Quot; (7) "

&Quot; (8) "

FIG. 9 is a graph showing the normal distribution curves of Equations (7) and (8).

The probability of belonging to a colored portion (hereinafter referred to as " defective range ") in the normal distribution curve for voltage and current expressed in FIG. 10 is expressed by the following equation.

&Quot; (9) "

If the voltage V _i and the current I _i of the respective modules are less than half of the average value m _v / 2 and m _c / 2 in the defective range, respectively, the voltage and current are significantly lower .

If it is judged to be defective, an alarm message is sounded and the relay of the bypass circuit for the PV module Mod _i is switched so that the current flows to the bypass circuit. If this phenomenon occurs continuously for the module, it can be managed so that the solar power generation can be continuously and stably operated by replacing the corresponding module.

Although the invention made by the present inventors has been specifically described according to the above embodiments, the present invention is not limited to the above embodiments, and it goes without saying that the present invention can be modified in various ways without departing from the gist of the present invention.

10: solar cell array 11: PV module
20: Sensor module 21: Bypass circuit
22: Detection circuit 23:
25: control unit 30: main controller

Claims (5)

A photovoltaic power generation system comprising a PV bad module bypass circuit,
A solar cell array composed of a plurality of PV modules connected in series;
A sensor module installed in each of the PV modules for detecting a current or a voltage of the PV module and bypassing the PV module; And
Receiving a detection value from the sensor module to obtain a probability distribution of detection values, and transmitting a command to the sensor module to bypass the sensor module when the detection value of the sensor module is less than a predetermined range in the probability distribution Including mainframe,
Wherein the main controller obtains a mean value and a standard deviation of the voltage or current of the entire PV module, obtains a probability density function according to the normal distribution using the average value and the standard deviation, calculates a predetermined density distribution from the normal distribution curve represented by the probability density function, Value is obtained,
The main control groups than the voltage V _i and the current I _i, the voltage V _i and the current I _i, each of the average value half into the PV module at the same time, the poor range according to a normal distribution curve _{m v / 2, m c /} 2 of PV module If it is small, the PV module is judged to be defective,
The main controller determines that the voltage V _i and the current I _i of the PV module enter the defective range when the following expression (1) is satisfied,
The sensor module includes:
A bypass circuit that has a relay to directly connect or bypass the output of an installed PV module with an adjacent PV module;
A detection circuit for detecting voltage and current of the PV module;
A communication unit for communicating with the main controller; And
A controller for controlling the direct connection or the detour connection of the PV module by transmitting the detected values detected by the detection circuit to the main controller and receiving a command from the main controller and controlling the relay of the bypass circuit, Wherein the photovoltaic power generation system comprises a photovoltaic module bypass circuit.
[Equation 1]

Where m _v and m _c are the average values of the voltage and current of the entire PV module,
σ _v and σ _c are the standard deviation of the voltage and current of the entire PV module,
k is a constant greater than zero.
delete The method according to claim 1,
The main controller includes a microprocessor and a program for receiving voltage and current of each PV module transmitted by RS-485 communication with the sensor module and determining whether each PV module is defective, Wherein the program is executed by a microprocessor to perform a malfunctioning module detection and bypass operation.
delete delete

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