KR101561640B1 - Micro converter device using power deviation handling of needless high-voltage DC-DC converter and control method thereof - Google Patents

Micro converter device using power deviation handling of needless high-voltage DC-DC converter and control method thereof Download PDF

Info

Publication number
KR101561640B1
KR101561640B1 KR1020140054590A KR20140054590A KR101561640B1 KR 101561640 B1 KR101561640 B1 KR 101561640B1 KR 1020140054590 A KR1020140054590 A KR 1020140054590A KR 20140054590 A KR20140054590 A KR 20140054590A KR 101561640 B1 KR101561640 B1 KR 101561640B1
Authority
KR
South Korea
Prior art keywords
module
duty
current
string
voltage
Prior art date
Application number
KR1020140054590A
Other languages
Korean (ko)
Inventor
조경호
김정렬
조창익
손석민
Original Assignee
(주)알티에스에너지
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by (주)알티에스에너지 filed Critical (주)알티에스에너지
Priority to KR1020140054590A priority Critical patent/KR101561640B1/en
Application granted granted Critical
Publication of KR101561640B1 publication Critical patent/KR101561640B1/en

Links

Images

Classifications

    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05FSYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/66Regulating electric power
    • G05F1/67Regulating electric power to the maximum power available from a generator, e.g. from solar cell
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00Conversion of dc power input into dc power output
    • H02M3/02Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02SGENERATION OF ELECTRIC POWER BY CONVERSION OF INFRA-RED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S40/00Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
    • H02S40/30Electrical components
    • H02S40/36Electrical components characterised by special electrical interconnection means between two or more PV modules, e.g. electrical module-to-module connection
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/50Photovoltaic [PV] energy
    • Y02E10/56Power conversion electric or electronic aspects
    • Y02E10/58Maximum power point tracking [MPPT] systems

Abstract

The present invention relates to a power deviation handling-type micro converter in a duty direct control method by a pattern search, which does not require a high voltage DC-DC converter that is needed to perform an MPPT in a micro converter having a power deviation handling structure for a photovoltaic module. The present invention may include: multiple photovoltaic modules; a string control means which directly measures power of the last solar module among the multiple solar modules, measures the power of the rest of the photovoltaic modules through a module controller, and calculates pulse width modulation duty values of each module controller by using a pattern search algorithm based on the obtained power values; and a module controller which controls output power of the photovoltaic modules by using the pulse width modulation duty values generated by the string control means. Therefore, the present invention does not require a high voltage DC-DC converter.

Description

[0001] The present invention relates to a power converter, and more particularly, to a power converter that does not require a high-voltage DC-DC converter.

The present invention relates to a power converter processing type micro converter that does not require a high-voltage DC-DC converter, and more particularly, to a micro converter of a power deviation processing type for a photovoltaic module, To a power deviation processing type micro-converter of a duty direct control type by eliminating a high-voltage DC-DC converter necessary for performing the follow-up (MPPT).

Generally, a photovoltaic power generation system is a system that converts pollution-free and indefinite solar energy directly into electrical energy, and has recently attracted attention as a renewable energy.

The photovoltaic power generation system is equipped with a photovoltaic module (PV module), and the maximum power point tracking (MPPT) is performed in the central inverter in order to increase the solar power generation efficiency. There are thousands of solar modules connected to a single inverter. Because the output voltage and current of one solar module is small, the voltage is increased in string units until it is connected to the inverter, and the strings are connected in parallel And the current is increased.

In this case, since the internal solar modules are connected in series, the characteristic of one module is lowered, and when the current is lower than that of other modules in the vicinity, the entire string flows based on the current value of the module. Also, in the structure in which a plurality of strings are connected in parallel, when the optimum value of the string voltage is different due to a mismatch between strings, the inverter is forced to apply one voltage, so that each string deviates from the optimum point. These phenomena are inevitable as long as the maximum power point tracking is performed in the central inverter.

Here, the characteristics of a specific module inside the string are inevitably degraded due to various characteristics such as shadows, dust, leaves, and degradation between modules.

In recent years, a micro converter has been commercialized to perform maximum power point tracking in units of modules, and it has been compensated to some extent that the characteristics of a specific module are reduced by installing the micro converter. However, this method has a disadvantage that system cost is increased because a micro converter for MPPT is installed per module. In addition, when the solar radiation is good and the module is uniform, the devices installed per module consume energy rather than energy.

On the other hand, as shown in FIG. 1, the current-voltage and power-voltage characteristic curves of the solar module are changed as the solar radiation amount of the sunlight changes.

Therefore, when the shadow is partially shaded inside the string, the current value of the shadow photovoltaic module is decreased according to the characteristic curve, and the current of the entire string is determined based on the lowest current value. In addition, three submodules are usually connected in series inside the solar module, and when one of the submodules is shadowed, the current of the entire solar module is reduced.

FIG. 2 is a block diagram of a P & O type power deviation-type microconverter device proposed in the related art to solve all the problems in the solar power generation system.

2, the P & O type power deviation type micro-converter device includes a solar module 11, a junction box 12, a micro-converter 13, a high-voltage DC / DC converter 14, And a string controller 15,

The string controller 15 of the power deviation microcomputer configured as described above receives 100% of the output power of the photovoltaic module, adjusts the respective PV voltages so as to become the maximum power point state, and outputs the power to the string. At this time, the string controller 15 consumes 2 to 3% of its own energy due to the high voltage DC / DC converter 14. [

Therefore, the power deviation type micro converter system only processes the power deviation between the solar modules, so that when there is no mismatch between the modules, the micro converter 13 does not operate and power is transferred to the original connection structure, do. Only when a mismatch between modules occurs, the microconverter 13 intervenes under the control of the string controller 15, so that the overall power conversion efficiency is greatly improved as compared with the cascade method.

In particular, there is a string controller 15 in a string, which calculates the output of each module from the voltage and current values received from each module in the string and traces the maximum power point in P & O manner therefrom. At this time, the voltage applied to the entire string should be maintained at a value selected by the maximum power point algorithm. However, since the maximum power point tracking operation is performed, there must be a high voltage DC / DC converter 14 controlled by the string controller 15.

In contrast to the conventional cascade type solar cell module, the output of the solar cell module is still connected in series, and the microcomputer 23 is connected in parallel with the solar cell module. This allows the solar module's output to behave as if there is no microconverter under high sunlight conditions where there is no mismatch between the solar modules, while the microconverter treats only the differences when there is a difference in production power between modules, Problems of the method are improved.

For example, if all the PVs in a string are transmitting the best power under the same conditions, and the currents are equal to each other, the microconverter enters a shutdown mode without power processing, thereby minimizing the insertion loss of the device.

Also, when there is a difference in the power output between the modules in the string, the micro converters construct a new current path and process it. This requires a micro-converter to be installed between the module and the module, thus complicating the installation method and wiring. Also, there is a problem that the DC / DC converter of the string controller for finding the maximum power point of the PVs has a loss of 2 ~ 3%.

Meanwhile, another conventional technology for a photovoltaic device using a micro converter is disclosed in the following Patent Document 1: Korean Patent Registration No. 10-1245827 (published on March 20, 2013).

In order to improve the energy efficiency and the cost reduction in the solar power generation system field, the above-mentioned Patent Document 1 has a micro inverter converter in each solar module (PV module), and in the micro inverter converter, / Respond to situation factors, perform power / environmental monitoring.

Korean Registered Patent Registration No. 10-1245827 (Announced on March 20, 2013)

However, the above conventional techniques are applied not only to a micro-converter, but also to a miniature power generation system as a micro-inverter structure, and can not be applied to a large power generation system.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a duty control system for a solar module in which a high voltage DC-DC converter required to perform a conventional maximum power point tracking (MPPT) such as P & And a power deviation processing type micro-converter device which does not require a high-voltage DC-DC converter capable of following a maximum power point.

Another object of the present invention is to provide a power deviation correction type microprocessor which does not require a high-voltage DC-DC converter capable of improving the disadvantage of directly controlling the duty of each module at the time of calculating the maximum power point, And to provide a converter device.

According to an aspect of the present invention, there is provided a power converter micro-converter device that does not require a high-voltage DC-DC converter according to the present invention includes a plurality of solar modules; The power of the solar module connected to the last of the plurality of solar modules is directly measured and the power of the solar modules other than the last connected solar module is acquired through the module controller of the module, A string control means for controlling each module controller by calculating a pulse width modulation duty value of each module controller using a pattern search algorithm based on power values; And a module controller for controlling the output power of the solar module according to the pulse width modulation duty value generated in the string control unit.

The module controller may include N-1 pieces of the number of the solar modules N in total, and the number of the string control units may be one per string unit.

Wherein the string control means comprises: a module voltage / current detector for detecting a voltage and a current of the lastly connected solar module; And a string current detector for measuring the string current.

The string control means determines the pattern search algorithm based on the voltage and current values detected by the module voltage / current detector, the string current value detected by the string current detector, and the power calculated from the voltage and current values of the remaining solar modules. And a string controller for controlling each module controller by calculating a pulse width modulation duty value of each module controller by using the controller.

Wherein the string controller communicates with the module controller to receive voltage and current measurements of the solar module and to transmit control data for controlling the solar module to the module controller; A maximum power point calculating unit for calculating a maximum power point using a pattern search algorithm based on the voltage and current values of the photovoltaic module received through the communication module and the voltage / current and string current of the photovoltaic module directly measured; And a duty controller for adjusting a voltage of the solar module by transmitting a duty cycle control signal to the module controller according to a maximum power point calculated by the maximum power point calculating unit.

Wherein the module controller comprises: an inductor for current deviation compensation; First and second switches provided at one end of the inductor to set a current path; A duty controller for transmitting the voltage and current measurement values of the connected solar modules to the string control means and for controlling the duty cycle of the first and second switches based on the duty cycle control data transmitted from the string control means; And a driver for driving the first and second switches to the on or off state under the control of the duty controller.

The first and second switches may be MOSFETs, and the first and second switches operate in opposite directions.

According to the present invention, the high voltage DC-DC converter required for performing the maximum power point tracking (MPPT) in the micro converter of the power deviation processing structure for the photovoltaic module is removed, , Simplifying the device implementation while reducing the system implementation cost.

In addition, according to the present invention, the voltage and current of the solar module connected to the end of the string unit are directly measured by the string control means, thereby reducing the error and calculation amount when calculating the maximum power point.

According to the present invention, the duty of each module is directly controlled by the string controller when calculating the maximum power point, thereby improving the disadvantage of fixing the string voltage as intended.

FIG. 1 is a current-voltage and power-voltage characteristic curve diagram of a general solar module in the case of a change in irradiation dose,
2 is a configuration diagram of a P & O type power deviation-type microconverter device applied to a conventional photovoltaic power generation system.
3 is a configuration diagram of a power deviation processing type micro-converter device which does not require a high-voltage DC-DC converter according to a preferred embodiment of the present invention,
FIG. 4 is a block diagram of an embodiment of the string controller of FIG. 3,
FIG. 5A is a flowchart of a maximum power point follow-up procedure of the P & O scheme applied to the present invention, FIG. 5B is a flowchart of a maximum power point follow-
6 is an illustration of an internal table for measurement of a GPS pattern search method applied to the present invention,
7 is an illustration of an internal table for measurement of the MGPS pattern search method applied to the present invention,
8A and 8B are simulation results of the maximum power point tracking when four solar modules are provided.

Hereinafter, a power deviation processing type micro-converter device that does not require a high-voltage DC-DC converter according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram of a power deviation processing type micro-converter device which does not require a high-voltage DC-DC converter according to a preferred embodiment of the present invention.

As shown in FIG. 3, the power deviation processing type micro-converter device that does not require a high-voltage DC-DC converter according to the present invention includes a plurality of solar modules 111 to 113, module controllers 121 to 122, (130).

The number of the module controllers 121 to 122 is N-1 in relation to the total number of the plurality of solar modules 111 to 113 (N), and the number of the string control means 130 is one per string unit. In the present invention, only three solar modules are shown for the sake of convenience, but the present invention is not limited thereto, and the number thereof may be increased or decreased according to the string unit configuration. The module controllers 121 to 122 correspond to the solar modules one-to-one, but only the last solar module constituting the strings is connected to the string control unit 130 instead of the module controller. In addition, since the internal structure and operation of each of the plurality of solar modules are the same and the internal structure and operation of the plurality of module controllers are the same, Only the last solar module 113 will be described, and only the first module controller 121 will be described.

The string control means 130 directly measures the power of the last connected solar module 113 and the power of the remaining solar modules other than the last connected solar module is supplied to the module controller 121 of the corresponding module, And calculates the PWM duty value of each module controller 121 using the pattern search algorithm based on the obtained power values to control each module controller 121. [

Here, the string control means 130 includes a module voltage / current detector 132 for detecting the voltage and current of the lastly connected solar module 113; A string current detector 131 for measuring the string current I tot ; A pattern search algorithm based on the voltage and current values detected by the module voltage / current detector 132, the string current values detected by the string current detector 131, and the voltages and currents of the remaining solar modules, And a string controller 133 for controlling the respective module controllers 121 by calculating a duty cycle of the pulse width modulation of the controller 121.

The string controller 133 communicates with the module controller 121 to receive the voltage and current measurement values of the solar module 111 and controls the module controller 121 to control the solar module 111 A communication module 133a for transmitting control data; A maximum power calculating unit for calculating a maximum power point using the pattern search algorithm based on the voltage and current values of the photovoltaic module received through the communication module 133a and the current and string current of the photovoltaic module 113 directly measured, A point calculating unit 133b; And a duty controller 133c that adjusts the voltage of the solar module 111 by transmitting a duty cycle control signal to the module controller 121 according to the maximum power point calculated by the maximum power point calculator 133b .

In addition, the module controller 121 controls the output power of the solar module 111 according to the pulse width modulation duty value generated in the string control unit 130.

The module controller 121 includes an inductor 121a for current deviation compensation; First and second switches 121b and 121c provided at one end of the inductor 121a to set a current path; Transmits the voltage and current measurement values of the connected solar module 111 to the string control means 130 and controls the first and second switches < RTI ID = 0.0 > 121b) a duty controller 121e for controlling the duty cycle of 121c; And a driver 121d for driving the first and second switches 121b and 121c to the on or off state under the control of the duty controller 121e.

Here, the first and second switches 121b and 121c are preferably MOSFETs, and the first and second switches 121b and 121c operate in opposite directions.

The operation of the power deviation-type microconverter device which does not require the high-voltage DC-DC converter according to the present invention will be described in detail.

The power deviation processing type microconverter device which does not require the high voltage DC-DC converter according to the present invention is connected to only the last solar module 113, rather than inputting the voltage across the string of high voltage in the string control means 130. This structure does not require a high-voltage DC / DC converter.

First, the duty controller 121e of the module controller 121 measures the voltage and current of a solar module 111, which is not shown in the drawing, and transmits the measured voltage and current to the string control unit 130 through an internal communication module . At this time, the communication module is preferably implemented as a wireless communication module. In addition, the module controller 121 transmits the measured values and the corresponding ID numbers of the corresponding solar modules 111 together when transmitting the measured voltage and current values of the solar module 111 to the string controller 130 It is desirable to distinguish the solar modules. Here, the string controller 130 can recognize the voltage and current of the solar module, which are easily measured voltage and current measured values, by assigning the unique IDs to the solar modules.

The communication module 133a of the string controller 133 in the string control means 130 receives the voltage and current measurement values of the respective solar modules sent out from the module controllers 121 and 122 and supplies them to the duty controller 133c, . The duty controller 133c converts the input voltage and current measurement values into a corresponding digital voltage and current value, stores the converted voltage and current value in the internal memory, and transmits it to the maximum power point calculating unit 133b.

In addition, the module current detector 132 of the string control unit 130 directly measures the module voltage and current of the solar module 113 connected at the end of the string, and transmits it to the duty controller 133c. (131) detects the current of the entire string and transfers it to the duty controller (133c). The duty controller 133c converts the voltage and current values of the last photovoltaic module 113 and the string current values thus transferred into digital current values and stores them in the internal memory and transmits the digital current values to the maximum power calculator 133b do.

At this time, the duty controller 133c calculates the current flowing in the inductor provided in each module controller based on the current flowing in the string and the module current value transmitted from each module controller, using [Equation 1] below.

Figure 112014043177001-pat00001

Figure 112014043177001-pat00002

Figure 112014043177001-pat00003

Figure 112014043177001-pat00004

When an overcurrent flows from the inductor to the specific inductor, the duty controller 133c calculates the maximum power point for adjusting the voltage of the solar module through the maximum power point calculating unit 133b.

According to this control, the maximum power point calculator 133b follows the maximum power point using a pattern search algorithm instead of the P & O algorithm used for tracking the maximum power point.

5A illustrates a process of following a maximum power point using the P & O algorithm.

When the new reference voltage is determined, the P & O algorithm determines the duty of each module controller, sends it wirelessly to each module controller, calculates the power by wirelessly receiving the new voltage and current values of the solar module, As the calculated power increases or decreases, a cycle for determining a new reference voltage is repeated infinitely. Therefore, this method may take a long time to follow the maximum power point. Also, because of the need to control the string voltage, a high voltage DC / DC converter was needed inside the string controller.

FIG. 5B shows a process of following a maximum power point using a pattern search algorithm.

The pattern search algorithm directly controls the duty value of each module controller. After the duty values are wirelessly transmitted to each module controller, the voltage and current values are received wirelessly from each module to calculate power, The previous power value is compared and a new duty vector is calculated according to the result. This will be described in detail as follows.

The duty vector and the mesh size are defined as shown in [Equation 2] below.

Figure 112014043177001-pat00005

A single poll (Poll) means 2 (N-1) attempts as shown in the following Equation (3).

Figure 112014043177001-pat00006

Figure 112014043177001-pat00007

Figure 112014043177001-pat00008

Figure 112014043177001-pat00009

Here, 2 (N-1) pattern vectors are defined as shown in [Equation 4] below.

Figure 112014043177001-pat00010

Figure 112014043177001-pat00011

Figure 112014043177001-pat00012

Figure 112014043177001-pat00013

Figure 112014043177001-pat00014

Figure 112014043177001-pat00015

Figure 112014043177001-pat00016

Figure 112014043177001-pat00017

We use two types of GPS (Generalized Pattern Search) or MGPS (Modified Generalized Pattern Search) to determine the next pole. First, the GPS finds the maximum value among the output values (P tot, k ) of the string stage calculated in each trial and the peak value of the previous pole, and then uses the duty vector at that time as a new reference. FIG. 7 shows an example of the internal table configuration for this purpose.

MGPS calculates the voltage values when the maximum power of 2 (N-1) trials is produced for each voltage, not the trial, which is the maximum power of the string stage, among the trials, and then calculates the duty from these voltages And a new duty vector is obtained. FIG. 8 shows an example of the internal table configuration for this purpose. At this time, an algorithm of a mixture of GPS and MGPS is possible. In other words, when starting a new pole, a trial that maximizes the output after comparing both GPS and MGPS is set as a reference point of a new pole.

The new mesh size of the new poll determines whether to multiply the previous value by the amount of power measured between each pole. If there is no duty vector in the pole that produced a higher power than the previous pole's maximum, the pole is said to fail and the new mesh's new mesh size is 1/4 of its previous value. In this case, instead of attempting to reach 2 (N-1), if the value is larger than the maximum power value of the previous poles in the middle, it is possible to deal with the polling success and prepare the next pole. In addition, after the duty is calculated, the duty can be prevented from deviating from a certain range by setting an upper limit and a lower limit to the duty value, thereby preventing sudden change in inductor current.

FIGS. 8A and 8B show the result of simulation when four solar modules are provided. FIG. 8A shows voltage and current, and FIG. 8B shows power and duty values. From this, it can be seen that the system stably finds the maximum power point after several dozen attempts.

The following maximum power point is transmitted to the duty controller 133c. The duty controller 133c extracts currents flowing in the inductors of the respective modules according to Equation 1 using the current values and the string current values of the modules when the voltage and current measurement values for the respective solar modules are input And determines whether or not the photovoltaic module is in the shut-down mode based on the determination. The condition in shut-down mode here is that all solar modules have the same current value due to the same environmental conditions, ie the inductor current of all module controllers is close to zero, in which case all module controllers are shut down And observes the voltage and current value of each module continuously, and when the current fluctuates, it returns to the normal mode.

As a result of the determination, in the shut-down mode, operation control data (shut-down data) of the module controller is generated and transmitted to the module controller 121 via the communication module 133a. At this time, the operation control data is transmitted to substantially all the module controllers.

The duty controller 121e in the module controller 121 receives and analyzes the operation control data. As a result of the analysis, if the operation control data is the shut-down data, the driving of the driver 121d is turned off, only the communication module and the voltage / current sensor module for communicating with the string control means 130 operate, The element operates in a shut-down state. When the driving of the driver 121d is turned off, the first and second switches 121b and 121c connected to the driver 121d are also turned off, and the operation is not performed. That is, if the solar module is in a normal state, the operation of the module controller is operated in a shut-down mode, minimizing the insertion loss.

The duty controller 133c searches the voltage and current values measured by the respective solar modules and, when a power output difference occurs between the solar modules, the duty controller 133c compares the maximum value calculated by the maximum power point calculator 133b And generates a duty cycle for voltage adjustment of each solar module based on the power point. Here, since the duty cycle generation uses the MGPS scheme, a detailed description thereof will be omitted.

When a duty cycle corresponding to the difference in output power between the solar modules is generated, the duty cycle is transmitted to the module controller 121 through the communication module 133a.

The duty controller 121e of the module controller 121 drives the driver 121d in accordance with the received duty cycle to drive the first and second switches 121b and 121c, . At this time, the two switches at one end of the inductor operate opposite to each other in normal operation.

The operation of these switches and the inductor changes the output path of the power line output from each solar module. As the output power path is changed, the voltage of the solar module is adjusted optimally and compensation is performed according to the output power deviation of the solar module.

As described above, according to the present invention, the voltage and current of the solar module connected at the end of the string unit are directly measured by the string control means, thereby reducing the error and calculation amount when calculating the maximum power point.

On the other hand, when the mismatch between the photovoltaic modules occurs seriously or the mismatching modules are consecutively present, an overcurrent flows to the inductors of the module controller at the boundary with the module which is not the main one. As a countermeasure against this, in the present invention, a method called soft start is used at the time of initial startup. That is, regardless of the status of the solar module, the first and second switches of the module controller are not unconditionally started with d = 0.5 as an initial value, but initially all the module controllers are switched off and the duty of each module controller is set to Turn on sequentially. At this time, the change of the total amount of power before and after the duty of the module controller is measured, and when the change is negative, that is, when the duty decreases, the duty is turned off. On the other hand, if the total power amount is increased, it is set as it is, and it is confirmed that there is a module controller in which an overcurrent flows due to the duty of the module controller being turned on. If there is an overcurrent inductor, the inductor current is checked bidirectionally from the adjacent module centered on the inductor, the duty of the module controller having the inductor current close to 0 is turned off, and the current of the inductor, Or less. If the current of the inductor through which the overcurrent flows has fallen below the reference value, then the duty of the module controller to which the inductor close to 0 belongs turns off. This operation is repeated until the overcurrent falls below the reference point.

In the normal operation, the string control means periodically checks the overcurrent of the inductor. If there is a module in which the current of the inductor flows above the reference, the string control means turns on the inductor current The duty of the module controller having the inductor current close to 0 is turned off, and it is confirmed whether or not the current of the inductor in which the overcurrent has flowed falls below the reference value. If the current of the inductor does not fall below the reference value, the duty of the module controller to which the inductor close to zero belongs is turned off. This operation is repeated until the overcurrent falls below the reference point.

Although the present invention has been described in detail with reference to the above embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the present invention.

The present invention is applied to a photovoltaic device. In particular, it is effectively applied to a technique of measuring the power of a solar module directly in a string controller to adjust the voltage of the solar module, and calculating a maximum power point using the pattern search algorithm based on the power.

110 ... Solar modules
120 ... Junction box
130 ... Micro converter
131 ... Module controller
132, 133 ... driver
140 ... String controller
141 ... Communication module
142 ... The maximum power point calculation unit
143 ... Duty controller
150 ... Bidirectional DC-DC converter

Claims (13)

  1. A plurality of solar modules;
    The power of the solar module connected to the last of the plurality of solar modules is directly measured and the power of the solar modules other than the last connected solar module is acquired through the module controller, A string control means for controlling each module controller by calculating a pulse width modulation duty value of each module controller using a pattern search algorithm as a basis; And
    And a module controller for controlling the output power of the solar module in accordance with the pulse width modulation duty value generated by the string control unit, wherein the high voltage DC-DC converter is not required.
  2. The high-voltage DC-DC converter according to claim 1, wherein the module controller comprises N-1 pieces of the number of the solar modules (N) in total, and the string control unit comprises one string unit A power deviation processing type micro-converter device which does not need to be used.
  3. 2. The apparatus of claim 1, wherein the string control means comprises: a module voltage / current detector for detecting voltage and current of the last connected solar module; And a string current detector for measuring a string current, wherein the high-voltage DC-DC converter is not required.
  4. The string control device according to claim 3, wherein the string control means is configured to calculate a string current value detected by the string current detector, a voltage and a current value detected by the module voltage / current detector, and a power calculated from voltage and current values of the remaining solar module And a string controller for controlling each module controller by calculating a pulse width modulation duty value of each module controller using a pattern search algorithm. .
  5. 5. The system of claim 4, wherein the string controller comprises: a communication module for communicating with the module controller to receive voltage and current measurements of the solar module and to transmit control data for controlling the solar module to the module controller; A maximum power point calculating unit for calculating a maximum power point using a pattern search algorithm based on the voltage and current values of the photovoltaic module received through the communication module and the voltage / current and string current of the photovoltaic module directly measured; And a duty controller for adjusting a voltage of the solar module by transmitting a duty cycle control signal to the module controller according to a maximum power point calculated by the maximum power point calculating unit. Power deviation processing type micro converter device.
  6. The module of claim 1, wherein the module controller comprises: an inductor for current deviation compensation; First and second switches provided at one end of the inductor to set a current path; A duty controller for transmitting the voltage and current measurement values of the connected solar modules to the string control means and for controlling the duty cycle of the first and second switches based on the duty cycle control data transmitted from the string control means; And a driver for driving the first and second switches to an on or off state under the control of the duty controller.
  7. 2. The method of claim 1, wherein the string control means performs both a GPS (Generalized Pattern Search) and a MGPS (Modified Generalized Pattern Search) when starting a new poll, Pole DC-DC converter, wherein a high-voltage DC-DC converter is not required.
  8. 2. The apparatus of claim 1, wherein the string control means obtains voltage values when the maximum power is produced, and then calculates a duty from the voltages to obtain a new duty vector. The high voltage DC- Displacement type microconverter device.
  9. 9. The method of claim 8, wherein the string control means sets the new mesh size of the new poll to 1/4 of its previous value if there is no duty vector in the poll that produced a power higher than the maximum of the previous poll, And when a value greater than the maximum power value of the previous pole is found during the search, the duty is calculated by successively processing the corresponding pole, thereby eliminating the need for a high-voltage DC-DC converter.
  10. The high-voltage DC-DC converter according to claim 9, wherein the string control unit calculates a duty and then sets an upper limit and a lower limit to the duty value so that the duty does not deviate out of a certain range to prevent a sudden change in inductor current. A power deviation processing type micro-converter device which does not need to be used.
  11. 2. The method of claim 1, wherein the string control means turns off the first and second switches of the module controller at the start of the startup regardless of the status of the solar module, sequentially turns on the duty of each module controller, Wherein the duty ratio of the power converter is measured by measuring a change in the total power amount before and after the operation of the microcomputer is performed, and when the amount of power is decreased, the duty is turned off and the current duty is maintained when the power amount is increased. .
  12. The string control unit according to claim 11, wherein the string control unit checks whether there is a module controller in which an overcurrent flows in the inductor with the current duty maintained, and if there is an inductor in which an overcurrent occurs, And the duty of the module controller is controlled by checking the current and turning off the duty of the module controller having the inductor current close to zero.
  13. The string control device according to claim 11, wherein the string control means periodically checks an overcurrent of the inductor during normal operation so that if there is a module in which the current of the inductor flows above the reference, the inductor current flows in both directions away from the adjacent module Wherein the duty of the module controller is controlled in such a manner that the duty of the module controller having the inductor current close to zero is turned off, thereby controlling the duty of the module controller.


KR1020140054590A 2014-05-08 2014-05-08 Micro converter device using power deviation handling of needless high-voltage DC-DC converter and control method thereof KR101561640B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR1020140054590A KR101561640B1 (en) 2014-05-08 2014-05-08 Micro converter device using power deviation handling of needless high-voltage DC-DC converter and control method thereof

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR1020140054590A KR101561640B1 (en) 2014-05-08 2014-05-08 Micro converter device using power deviation handling of needless high-voltage DC-DC converter and control method thereof
PCT/KR2015/004584 WO2015170903A1 (en) 2014-05-08 2015-05-08 Micro-converter device for photovoltaic energy generation source

Publications (1)

Publication Number Publication Date
KR101561640B1 true KR101561640B1 (en) 2015-10-30

Family

ID=54392700

Family Applications (1)

Application Number Title Priority Date Filing Date
KR1020140054590A KR101561640B1 (en) 2014-05-08 2014-05-08 Micro converter device using power deviation handling of needless high-voltage DC-DC converter and control method thereof

Country Status (2)

Country Link
KR (1) KR101561640B1 (en)
WO (1) WO2015170903A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100308662A1 (en) 2007-10-15 2010-12-09 Ampt, Llc High Efficiency Remotely Controllable Solar Energy System
KR101135386B1 (en) 2011-12-23 2012-04-12 (주)케이디티 Photovoltaic power generation system perform the maximum power point tracking about the unit group
US20130026840A1 (en) 2011-07-28 2013-01-31 Tigo Energy, Inc. Systems and Methods to Reduce the Number and Cost of Management Units of Distributed Power Generators
KR101386528B1 (en) 2013-02-19 2014-04-17 한서대학교 산학협력단 Photovoltaic power generation system using multistage switches and driving method therefor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100308662A1 (en) 2007-10-15 2010-12-09 Ampt, Llc High Efficiency Remotely Controllable Solar Energy System
US20130026840A1 (en) 2011-07-28 2013-01-31 Tigo Energy, Inc. Systems and Methods to Reduce the Number and Cost of Management Units of Distributed Power Generators
KR101135386B1 (en) 2011-12-23 2012-04-12 (주)케이디티 Photovoltaic power generation system perform the maximum power point tracking about the unit group
KR101386528B1 (en) 2013-02-19 2014-04-17 한서대학교 산학협력단 Photovoltaic power generation system using multistage switches and driving method therefor

Also Published As

Publication number Publication date
WO2015170903A1 (en) 2015-11-12

Similar Documents

Publication Publication Date Title
US20170373590A1 (en) Distributed Power Harvesting Systems Using DC Power Sources
US9612608B2 (en) Maximum power point tracker bypass
US9698599B2 (en) Switching circuits for extracting power from an electric power source and associated methods
US9214810B2 (en) Method of operation and device for controlling an energy installation having photovoltaic modules
US9281685B2 (en) Power harvesting circuit and method for serially coupled DC power sources
US9373964B2 (en) Optimized control of a power converter in response to load conditions
US20150364918A1 (en) System and method of optimizing load current in a string of solar panels
US9106105B2 (en) Regulation of inverter DC input voltage in photovoltaic arrays
US20180054066A1 (en) Device and Method for Global Maximum Power Point Tracking
US20190081482A1 (en) Systems and methods to balance solar panels in a multi-panel system
US10312692B2 (en) Systems and methods to reduce the number and cost of management units of distributed power generators
US8618456B2 (en) Inverter for a three-phase AC photovoltaic system
US20160285272A1 (en) Enhanced system and method for string balancing
EP2549635B1 (en) Distributed power harvesting systems using DC power sources
US8829715B2 (en) Switching coordination of distributed dc-dc converters for highly efficient photovoltaic power plants
AU2011200794B2 (en) System and method for a single stage power conversion system
TWI494734B (en) Method and system for providing maximum power point tracking in an energy generating system
US20170085093A1 (en) System and method for low-cost, high-efficiency solar panel power feed
CN102067437B (en) Method and system for selecting between centralized and distributed maximum power point tracking in an energy generating system
US9018800B2 (en) High efficiency wide load range buck/boost/bridge photovoltaic micro-converter
US9442504B2 (en) Methods and apparatus for adaptive operation of solar power systems
US9287712B2 (en) Photovoltaic power plant
US9847646B2 (en) Systems and methods to combine strings of solar panels
US8810068B2 (en) System and method for over-voltage protection of a photovoltaic system with distributed maximum power point tracking
US8472222B2 (en) Method for operating an inverter, and inverter

Legal Events

Date Code Title Description
GRNT Written decision to grant
FPAY Annual fee payment

Payment date: 20181015

Year of fee payment: 4

FPAY Annual fee payment

Payment date: 20191014

Year of fee payment: 5