WO2015163583A1

WO2015163583A1 - Photovoltaic system

Info

Publication number: WO2015163583A1
Application number: PCT/KR2015/002695
Authority: WO
Inventors: 김병철; 정채봉; 장성택; 김민석; 박연민
Original assignee: (주) 에이비엠그린텍
Priority date: 2014-04-22
Filing date: 2015-03-19
Publication date: 2015-10-29
Also published as: DE112015001945T5; KR101445711B1

Abstract

The present invention relates to a photovoltaic system and, more specifically, to a photovoltaic system capable of determining weather conditions and system fault through a pattern of values (string output values or sensed values of an environmental sensor) obtained by monitoring on-site conditions during photovoltaic power generation and switches to any one mode among a string type mode, a parallel type mode, and a sub-array type mode so as to induce optimum inverter efficiency for each condition.

Description

Solar power system

The present invention relates to a photovoltaic power generation system, and more particularly, string type mode by determining a weather situation and system failure through a pattern of a value of monitoring a photovoltaic power generation site (string output value or sensing value of an environmental sensor). The present invention relates to a photovoltaic power generation system capable of inducing an optimum inverter efficiency for each situation by switching to one of parallel mode and subarray mode.

In general, solar cells convert energy from sunlight into electrical energy and generate electricity using two types of semiconductors, a P-type semiconductor and an N-type semiconductor.

When light is emitted to the solar cell, electrons and holes are generated inside, and the generated charges move to the P pole and the N pole, and a potential difference is generated between the P pole and the N pole by this phenomenon.

At this time, when a load is connected to the anode of the solar cell, a current flows.

These solar cells are connected in series and parallel as necessary to make a structure that can withstand the natural environment and a certain external shock, where the solar cell is the minimum unit for generating electricity, the solar cell module is the minimum to produce electricity As a unit, a plurality of solar cells are connected in series and in parallel, and are generally used after being standardized.

Recently, due to the regulations, etc. related to the oil prices and the environment, despite the economy by excessive initial investment in the development of relying on fossil fuels so many restrictions on existing generator is relatively low, and domain for the conservation of the CO ₂ reduction Global efforts are increasing to expand and disseminate renewable energy such as solar and wind power.

In more detail with respect to the above-described photovoltaic power generation system, the solar cell module produces and converts the DC power to usable AC power, and various string configurations to induce maximum conversion efficiency according to the characteristics of the local environment. This is possible.

As technology trends and inverter cost drops, various attempts have been made to construct strings and multiple inverters to increase system efficiency and simplify circuits. As shown in FIG. 1, strings and multiple inverters suitable for photovoltaic power generation situations are shown in FIG. 1. The circuit composition method of is derived.

As shown in FIG. 1, a circuit configuration method of a string and an inverter suitable for the environment (weather) is divided into a centralized type, a subarray type, a parallel type, a string type configuration method, and each of the advantages is derived according to the configuration method. Although it is possible to provide the configuration method at the same time.

Therefore, it is necessary to review and introduce the most suitable configuration method according to the site situation in advance, and in any way, once the system is installed, there is a problem that additional time and cost are required for reconstruction.

In order to solve the above problem, the micro-inverter type circuit configuration method can be operated independently by connecting the micro-inverter directly to the solar cell module without string generation, and has high efficiency and freedom of configuration, but it is still economical due to the high cost of the micro-inverter. Difficult to secure problems arise.

Therefore, in the present invention, as a next generation photovoltaic technology that satisfies the system efficiency and economics simultaneously, the weather situation and system through the pattern of the monitoring value of the photovoltaic field (string output value or sensing value of the environmental sensor) It is proposed a technology that induces the maximum inverter efficiency in each situation by determining the failure and switching to one of the string mode, the parallel mode, and the sub-array mode.

The technical solution of the present invention is as follows.

It is intended to suggest a solution of the present invention for achieving the above object.

That is, the string unit 100 composed of a plurality of strings composed of a plurality of solar cell modules 110;

A first switch unit 200 including one or more switches 210a to 210n for electrically connecting or disconnecting each string according to an on / off signal of the mode variable control means;

The second switch unit 300 including one or more switches 310a to 310n to provide or cut off the generated power provided from each string according to the on / off signal of the mode variable control means. ;

An inverter unit 700 including a plurality of inverters for converting the generated power provided from the string unit into AC power and supplying the generated power to a power system or a load;

Calculate the standard deviation value and average value with the power value of each string calculated by monitoring the ammeter and voltmeter installed in each string of the string part, and designate it as the representative value of the current generation situation. Each of the first switch unit is configured to determine the optimum mode of the current photovoltaic field situation by comparing the standard deviation threshold value of the string power and the average threshold value of the string power for switching to any one of the subarray type modes. A mode variable control means (500) for varying modes by providing an on / off signal for each switch of the switch and providing an on / off signal for each switch constituting the second switch unit.

According to the above configuration, it is possible to solve the problems of the present invention.

The present invention has the following effects.

According to the photovoltaic power generation system of the present invention, by determining the weather conditions and system failure through the pattern of the value of monitoring the photovoltaic field (string output value or sensing value of the environmental sensor), string type mode, parallel mode, By switching to any one of the subarray type modes, the maximum inverter conversion efficiency for each situation is induced.

1 is a diagram illustrating the advantages of various string-inverter configurations.

2 is a schematic diagram of a mode variable operation of a photovoltaic system according to an embodiment of the present invention.

3 is an overall configuration diagram of a photovoltaic system according to an embodiment of the present invention.

Figure 4 is a block diagram of the mode variable control means of the photovoltaic system according to an embodiment of the present invention.

5 is a mode classification diagram according to the representative value of the photovoltaic power generation site situation of the photovoltaic system according to an embodiment of the present invention.

6 is an exemplary view showing a criterion parameter of the mode selection of the photovoltaic system according to an embodiment of the present invention.

7 is a switch connection diagram in the sub-array mode of the photovoltaic system according to an embodiment of the present invention, Figure 8 is a switch connection diagram in the string mode, Figure 9 is a parallel mode Switch connection diagram.

In the solar power system,

String unit 100 consisting of a plurality of strings consisting of a plurality of solar cell module 110;

Calculate the standard deviation value and average value with the power value of each string calculated by monitoring the ammeter and voltmeter installed in each string of the string part, and designate it as the representative value of the current generation situation. Each of the first switch unit is configured to determine the optimum mode of the current photovoltaic field situation by comparing the standard deviation threshold value of the string power and the average threshold value of the string power for switching to any one of the subarray type modes. And a mode variable control means 500 for varying modes by providing an on / off signal for each switch of the switch and providing an on / off signal for each switch constituting the second switch unit. Solar power system.

Hereinafter, with reference to the drawings, a preferred embodiment of the present invention will be described in detail.

However, the scope of the present invention is not limited to these embodiments, and the invention can be easily modified at a level of ordinary skill in the art, and if the technical ideas are the same, all of them belong to the scope of the present invention.

As shown in FIG. 2, the system of the present invention has a configuration in which the system is switched to an optimal mode according to a change in power generation amount due to environmental changes, and is operated by variably connecting a plurality of inverters.

This is carried out in the mode switching processing unit, thereby increasing the power generation efficiency, extending the life of the inverter, and exhibits the effect of immediate response to failures.

As shown in FIG. 7 to FIG. 9, for example, the string type is clear according to the weather conditions such as sunny weather, cloudy / rain, partial shadowing, solar cell module / inverter failure, etc. Controlled in parallel, the parallel type is a blurring / non-state with a low output string through intensive inverter control, the subarray type is a partial shaded state with a partial low output string through split inverter control, In the case of a solar cell module / inverter failure, control is performed to block the failed string and the inverter.

It is to increase the overall system operating efficiency by inducing the maximum inverter efficiency for each situation by switching to the optimal mode for various situations as described above.

As shown in FIG. 3, the photovoltaic power generation system includes a string unit 100 including a plurality of strings, a first switch unit 200, a second switch unit 300, a mode variable control means 500, and a plurality of string units. It is configured to include an inverter unit 700 configured as an inverter.

The string part 100 is composed of a plurality of strings (1 ~ n), consisting of a plurality of solar cell module 110, and is connected to each inverter part consisting of a plurality of inverters.

For example, the first string is connected to the first inverter and the second string is connected to the second inverter.

In this case, in the case of the present invention, the switch units are controlled on / off by the mode variable control means.

The first switch unit 200 is configured to include one or more switches (210a ~ 210n) for electrically connecting or disconnecting each string in accordance with the on / off signal of the mode variable control means.

That is, the connection or disconnection between one string and the other string is performed, and as shown in FIG. 3, the string units have a parallel connection configuration.

The second switch unit 300 includes one or more switches 310a to 310n to provide or cut off the generated power provided from each string according to the on / off signal of the mode variable control means to each inverter. Will be constructed.

That is, it is configured between the string part and the inverter part to perform power supply or interruption by turning on / off. As shown in FIG. 3, the string part and the inverter part have a series connection configuration.

The inverter unit 700 is composed of a plurality of inverters to convert the generated power provided from each string to AC power to supply to the power system or load.

At this time, through the mode variable control means 500, which is the core configuration of the present invention, the standard deviation value and the average value are calculated using the power values of each string calculated by monitoring the ammeter and the voltmeter installed in each string of the string part. The reference value is compared with the standard deviation threshold value of the string power and the average threshold value of the string power for switching to the representative value and one of the preset string type mode, parallel mode, and subarray mode.

Subsequently, the on / off signal is provided for each switch constituting the first switch unit by determining a mode suitable for the current generation situation of the photovoltaic system, and the on / off signal is provided for each switch constituting the second switch unit. To change the mode.

For example, while driving in the sub-array mode, when the weather is clear, the on / off control of the first switch unit and the second switch unit is performed to be changed to the string mode.

4 is a block diagram of the mode variable control means of the photovoltaic system according to an embodiment of the present invention.

As shown in FIG. 4, the mode variable control means 500 of the present invention includes a monitoring unit 510, a database unit 520, a current status determination unit 530, and a mode switching processing unit 540. .

The monitoring unit 510 calculates the standard deviation value and the average value using the power value of each string calculated by monitoring the ammeter and voltmeter installed in each string of the string part, and designates it as a representative value of the photovoltaic field situation. Will be stored in.

As described above, the mode classification diagram according to the representative value of each photovoltaic field situation is illustrated in FIG. 5. Referring to FIG. 5, the A mode is a mode for operating in a string type configuration (string output normal, sunny weather). This mode is defined as string type mode, and B mode refers to the mode of operation in parallel configuration (string output normal, weather blur), and this is defined as parallel mode, and C mode is subarray configuration (string output). Abnormal, shadow or string failure), and it is defined as subarray mode.

The mode variable control means determines the meteorological situation and system failure through the pattern of the monitoring value of the photovoltaic power generation site (string output value or sensing value of the environmental sensor) to switch to the optimum mode for each situation. The situation is divided into two modes.

At this time, if the standard deviation of the string power is high, it will be converted to C mode. If the standard deviation of the string power is low, it will be judged with the average value of the string power. If the average value is high, it will be converted to A mode. Will be.

The database unit 520 may include a standard deviation threshold value of string power, an average threshold value of string power, external environment information, and string power of a string mode, a parallel mode, and a subarray mode. The standard deviation value and the average value of the string power are stored.

At this time, the current situation determination unit 530 extracts the standard deviation value information from the database unit and compares the standard deviation threshold value information and the extracted standard deviation value information to determine the normal / abnormal string output, in case of abnormal string output Sub-array mode (C mode) is selected.

In the case of normal string output, the average value information is extracted from the database unit, and the average threshold information is compared with the average value information. If the average value information is higher than the average threshold value, the string type mode is selected. The mode switching processing unit is to provide the selected mode information.

Finally, when the mode provided by the current situation determination unit is a sub-array mode, the mode switching processing unit 540 is divided into an upper group and a lower group according to a string power situation, and each of them is configured as a string type mode or a parallel mode independently. In order to provide an on / off signal for each switch constituting the first switch unit and the second switch unit.

On the other hand, in the string mode, each inverter unit provides the ON signal for each switch constituting the first switch unit and the second switch unit to independently perform the MPPT control, and in the parallel mode, the string power is provided. According to the situation, the on / off signal is provided for each switch constituting the first switch unit and the second switch unit so as to be sequentially operated from the inverter unit having low usage.

Next, the functions of the above components will be described in detail.

The monitoring unit 510 is configured to include at least one module of the representative value designation module 511, the external environment information processing module 512.

The representative value designation module 511 obtains a power value of each string calculated by monitoring an ammeter and a voltmeter installed in each string of the string part, calculates a standard deviation value and an average value in real time, and represents the representative value of the photovoltaic generation site situation. To be specified.

For example, the first current situation representative value is designated as the string power standard deviation value, and the second current situation representative value is designated as the string power average value, thereby determining the power generation situation of the current string unit divided as shown in FIG. Is to select a mode.

The external environment information processing module 512 acquires a sensor value measured from an external environment sensor and stores the sensor value in a database unit.

The database unit 520 is configured to include at least one module of the standard deviation threshold value derivation module 521, the average threshold value derivation module 522, and the database module 523.

The standard deviation threshold value derivation module 521 obtains a string power standard deviation threshold value for determining whether the string output is normal through power conversion efficiency information of the string type, parallel mode, and subarray modes for each string power standard deviation value. Derivation,

The average threshold value deriving module 522 determines a string power average threshold value by determining the strength of the string output based on the power conversion efficiency information of the string type mode and the parallel mode for each string power average value.

At this time, the database module 523 is the string power standard deviation threshold value derived by the standard deviation threshold value extracting unit and the string power standard deviation threshold value derived from the mean threshold value extracting unit, external environment information, and string power standard. The average value of the deviation value and the string power is stored.

As shown in FIG. 6, a criterion for determining whether the string output is normal is a string power standard deviation threshold value, and a criterion for determining the strength of the string output is a string power average threshold value.

Therefore, in advance, the standard deviation threshold value derivation module determines a string power standard deviation threshold value to determine whether the string output is normal through system power conversion efficiency of each mode (A mode, B mode, and C mode) for each string power standard deviation value. Derived is stored in the database module.

In addition, in advance, the average threshold value deriving module determines the strength of the string output through the system power conversion efficiency of each mode (A mode and B mode) for each string power average to derive the string power average threshold value and store it in the database module. do.

In addition, the current situation determination unit 530 includes a standard deviation comparison determination module 531, an average comparison determination module 532, and a selection mode information providing module 533.

The standard deviation comparison determination module 531 extracts the standard deviation value information from the database unit, compares the standard deviation threshold value information with the standard deviation value information, and determines the normal / abnormal string output. Mode (C mode) is selected.

The average comparison determination module 532 extracts the average value information from the database unit in the case of the normal deviation output and compares the average value with the average threshold information when the average deviation information is higher than the average threshold value. Select type mode (A mode), and if low, select parallel mode (B mode).

In this case, the selection mode information providing module 533 acquires the mode information selected from any one of the standard deviation comparison determination module and the average comparison determination module to provide the selected mode information to the mode switching processor to perform the switching operation. will be.

In summary, the representative value calculated through monitoring is compared with the threshold set for each mode switching to determine the optimal mode of the current PV field situation.

Specifically, the normal / abnormal string output is judged by first comparing the string power standard deviation value with the threshold value, and in case of abnormality, the C mode is selected, and in the normal case, the string power average value is compared with the threshold value in the string output strength. Is to select A mode or B mode.

In mode A, the string output is normal and the weather is sunny. In mode B, the string output is normal and the weather is cloudy. In mode C, the string output is abnormal and shadow or string failure occurs. Will correspond.

The mode switching processing unit 540 includes a sub-array mode switching processing module 541, a string type switching processing module 542, and a parallel mode switching processing module 543.

That is, the sub-array mode switching processing module 541, as shown in Figure 7, when the mode provided by the current status determination unit is a sub-array mode (C mode) according to the string power situation according to the upper group and lower Each of the switches constituting the first switch unit and the second switch unit is provided with an on / off signal, respectively, so as to be divided into a group and independently configured in a string type mode or a parallel mode.

For example, the upper group is connected to the inverter unit # 1 to the string unit # 1 and # 2 to provide a 10 switch on signal, A switch on signal, B switch off signal, which is a parallel mode Will be driven.

In addition, the OFF signal is given to the 20 switch to divide the upper group and the lower group to perform the operation independently of each other.

In addition, each of the string units # 3 to # 6, which is a subgroup, is connected to the inverter units # 3 to # 6. For this purpose, 30, 40, and 50 switch off signals and C, D, E, and F switch on signals are provided. It is operated in string mode.

On the other hand, the string type switching processing module 542, as shown in Figure 8, each inverter unit independently performs MPPT control when the mode provided by the current status determination unit is a string type mode (A mode) The on-signal is provided to each switch constituting the first switch unit and the second switch unit.

For example, 10 to 50 switch-off signals and A to F switch-on signals are provided, and circuits are configured in a string type so that each inverter can independently perform MPPT control.

Meanwhile, as shown in FIG. 9, the parallel mode switching processing module 543 starts from the inverter unit having less usage in accordance with the string power situation when the current mode is provided in the parallel mode (B mode). The on / off signal is provided to each switch constituting the first switch unit and the second switch unit to be sequentially operated.

For example, 10 to 50 switch on signals, A to D switch on signals, and E to F switch off signals are provided.

The number of the string part and the inverter part shown in FIG. 7 to FIG. 9 are merely examples, and the number of the string part and the inverter part may be reduced or increased according to the site situation.

If it is configured as above, the string type mode is the most efficient when the weather is clear, the parallel mode is the most efficient when it is cloudy, and the sub-array mode is the most efficient when it is shadowed or broken. It is variably switched to the optimal mode.

As a result, when the above configuration and operation are performed, the optimum inverter conversion efficiency may be induced according to the weather situation and the fault condition through the variable mode construction and the situation-specific control.

Specifically, the inverter switching efficiency can be increased by changing to one of the string type mode, the parallel mode, and the sub-array mode through the control of the first switch unit and the second switch unit for each weather situation.

In addition, even if a failure occurs in any one of the inverter unit can provide an effect capable of generating power, it is possible to selectively drive the inverter unit in accordance with the cumulative power amount of the plurality of inverter units to limit unnecessary driving of the inverter unit accordingly The synergistic effect of extending the life of wealth can be derived.

As such, although an embodiment of a photovoltaic system to which the technical spirit of the present invention has been applied has been described, there may be various modified inventions having the same technical spirit, and this also belongs to the scope of the present invention.

The present invention is applicable to the industrial field related to the photovoltaic power generation system.

Claims

In the solar power system,

String unit 100 consisting of a plurality of strings consisting of a plurality of solar cell module 110;

A first switch unit 200 including one or more switches 210a to 210n for electrically connecting or disconnecting each string according to an on / off signal of the mode variable control means;

The second switch unit 300 including one or more switches 310a to 310n to provide or cut off the generated power provided from each string according to the on / off signal of the mode variable control means. ;

An inverter unit 700 including a plurality of inverters for converting the generated power provided from the string unit into AC power and supplying the generated power to a power system or a load;

Calculate the standard deviation value and average value with the power value of each string calculated by monitoring the ammeter and voltmeter installed in each string of the string part, and designate it as the representative value of the current generation situation. Each of the first switch unit is configured to determine the optimum mode of the current photovoltaic field situation by comparing the standard deviation threshold value of the string power and the average threshold value of the string power for switching to any one of the subarray type modes. And a mode variable control means 500 for varying modes by providing an on / off signal for each switch of the switch and providing an on / off signal for each switch constituting the second switch unit. Solar power system.
The method of claim 1,

The mode variable control means 500,

Monitoring unit for calculating the standard deviation value and the average value with the power value of each string calculated by monitoring the ammeter and voltmeter installed in each string of the string part, and designating it as the representative value of the photovoltaic field situation and storing it in the database part. 510),

The standard deviation threshold value of the string power and the average threshold value of the string power, the external environment information, the standard deviation value of the string power and the string power for switching to one of the string mode, the parallel mode, and the subarray mode. A database unit 520 storing an average value,

The standard deviation value information is extracted from the database unit, and the normal / abnormal string output is judged by comparing with the standard deviation threshold information. The subarray mode is selected in case of abnormal string output, and the database unit in case of normal string output. Determining the average value information from the current condition to compare the average threshold information with the average threshold value, if the average value is higher than the average threshold value, select the string type mode, and if the low value is the parallel mode, provide the selected mode information to the mode switching processor. 530,

When the mode provided by the current situation determination unit is a sub-array type mode, the first switch unit and the second switch unit may be divided into upper and lower groups according to a string power situation to independently configure a string type mode or a parallel mode mode. On / off signal is provided to each switch constituting the switch unit, and each switch constituting the first switch unit and the second switch unit so that each inverter unit can independently perform MPPT control in the string mode. In order to provide an on signal and an on / off signal for each switch constituting the first switch unit and the second switch unit in order to operate sequentially from the inverter unit with less usage in the parallel mode in the parallel mode. Photovoltaic power generation system comprising a mode switching processing unit (540).
The method of claim 2,

The monitoring unit 510,

A representative value designation module 511 for acquiring a power value of each string calculated by monitoring an ammeter and a voltmeter installed in each string of the string part, calculating a standard deviation value and an average value, and designating it as a representative value. At least one module of the external environmental information processing module (512) for acquiring a predetermined sensor value and storing it in a database unit.
The method of claim 2,

The database unit 520,

A standard deviation threshold derivation module 521 for deriving a string power standard deviation threshold for determining whether a string output is normal based on power conversion efficiency information of string-type mode, parallel mode, and sub-array mode for each string power standard deviation. ,

An average threshold value derivation module 522 for deriving a string power average threshold value by determining the strength of a string output based on power conversion efficiency information of string type and parallel modes for each string power average;

The string power standard deviation threshold value derived by the standard deviation threshold value extracting unit and the string power standard deviation threshold value derived from the mean threshold value extracting unit, external environment information, the standard deviation value of the string power, and the average value of the string power are stored. Photovoltaic system, characterized in that it comprises at least one module of the database module (523).
The method of claim 2,

The current situation determination unit 530,

A standard deviation comparison determination module 531 for extracting the standard deviation value information from the database unit and comparing the standard deviation threshold information with the standard deviation threshold information to determine a normal / abnormal string output to select a subarray type mode in the case of an abnormal string output;

As a result of the determination by the standard deviation comparison determination module, in the case of a normal string output, the average value information is extracted from the database unit and compared with the average threshold information. When the average value information is higher than the average threshold value, the string type mode is selected. Average comparison judging module 532 for selecting a model mode,

And a selection mode information providing module 533 for acquiring the selected mode information from any one of the standard deviation comparing module and the average comparing determining module to provide the selected mode information to the mode switching processor. Solar power system.
The method of claim 2,

The mode switching processing unit 540,

When the mode provided by the current status determination unit is a sub-array type mode, the first switch unit and the second switch may be divided into upper and lower groups according to the string power situation to independently configure the string mode or the parallel mode. A sub-array mode switching processing module 541 for providing an on / off signal for each switch constituting the unit,

A string for providing an on-signal for each switch constituting the first switch unit and the second switch unit so that each inverter unit can independently perform MPPT control when the mode provided in the current situation determination unit is a string type mode. Type mode switching processing module 542,

Parallel mode for providing on / off signals for each switch constituting the first switch unit and the second switch unit to be operated sequentially from the inverter unit with less usage when the mode provided in the current situation determination unit is a parallel mode. Photovoltaic power generation system comprising a mode switching processing module (543).
The method of claim 1,

The mode variable control means 500,

A photovoltaic power generation system characterized by increasing the inverter conversion efficiency by changing to any one of a string type mode, a parallel mode, and a sub-array mode by controlling the first switch unit and the second switch unit for each weather situation.