JPH08221143A - Maximum electric power follow-up control method for solar light power generation system - Google Patents
Maximum electric power follow-up control method for solar light power generation systemInfo
- Publication number
- JPH08221143A JPH08221143A JP7025089A JP2508995A JPH08221143A JP H08221143 A JPH08221143 A JP H08221143A JP 7025089 A JP7025089 A JP 7025089A JP 2508995 A JP2508995 A JP 2508995A JP H08221143 A JPH08221143 A JP H08221143A
- Authority
- JP
- Japan
- Prior art keywords
- command value
- voltage
- output
- electric power
- value voltage
- Prior art date
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Classifications
-
- Y—GENERAL 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
Landscapes
- Supply And Distribution Of Alternating Current (AREA)
- Control Of Electrical Variables (AREA)
- Inverter Devices (AREA)
- Photovoltaic Devices (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は太陽光発電システムの最
大電力追随制御方法に関し、詳しくは、太陽光発電シス
テムを最大出力追随制御するに際して、低日射時におい
て太陽電池の出力が低下した場合での制御方法に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a maximum power tracking control method for a solar power generation system, and more specifically, in controlling the maximum power tracking of a solar power generation system, when the output of a solar cell is reduced during low solar radiation. Control method.
【0002】[0002]
【従来の技術】近年、石油代替エネルギーとして、無公
害、無尽蔵、かつ安全性に富んだ太陽光発電システムの
実用化が進められ、太陽電池及びインバータからなる分
散電源と電力系統とを連系した太陽光発電システムが注
目されている。2. Description of the Related Art In recent years, as a petroleum alternative energy, a solar power generation system, which is pollution-free, inexhaustible, and highly safe, has been put into practical use, and a distributed power source including a solar cell and an inverter and an electric power system are connected to each other. Photovoltaic power generation systems are attracting attention.
【0003】図6はその太陽光発電システム1の構成を
示す回路図であり、太陽電池2で発電された直流電力を
インバータ3により交流電力に変換した上で負荷に電力
を供給すると共に余剰の交流電力を系統電源4に送電す
る。尚、図中、5は前記インバータ3の制御回路で、イ
ンバータ3の出力電流Iinv や系統電圧Vs 及び系統電
流Is を取込んで制御回路5の指令信号に追随させ、P
I制御やPWM制御によりインバータ3を駆動する。FIG. 6 is a circuit diagram showing the configuration of the solar power generation system 1, in which the DC power generated by the solar cell 2 is converted into AC power by the inverter 3 and then the power is supplied to the load and excess power is supplied. AC power is transmitted to the system power supply 4. In the figure, 5 is a control circuit of the inverter 3, which takes in the output current Iinv, the system voltage Vs, and the system current Is of the inverter 3 and follows the command signal of the control circuit 5,
The inverter 3 is driven by I control or PWM control.
【0004】ところで、前記太陽電池2の出力は、図7
に示すように凸形状のP−V特性曲線を有し、太陽電池
2の出力電圧Vcellを上昇させると出力電力Pが暫時大
きくなって最大出力電圧Vpmaxで最大出力Pmax とな
り、その後、ある電圧Vx 以上になると出力電力Pが急
激に降下し、更に、出力電圧Vcellを上昇させて開放電
圧Vocで出力電力Pが零となる。By the way, the output of the solar cell 2 is shown in FIG.
When the output voltage Vcell of the solar cell 2 is increased, the output power P increases for a while and the maximum output voltage Vpmax reaches the maximum output Pmax, and then a certain voltage Vx. When the above is reached, the output power P drops sharply, and further, the output voltage Vcell is raised and the output power P becomes zero at the open circuit voltage Voc.
【0005】このため、太陽光発電システム1では、太
陽電池2の出力電力Pが常に最大となるようにインバー
タ3の出力を制御する最大電力追従制御方法が採用され
ているのが通常である。Therefore, the solar power generation system 1 usually employs a maximum power follow-up control method of controlling the output of the inverter 3 so that the output power P of the solar cell 2 is always maximized.
【0006】この太陽光発電システム1の最大電力追従
制御方法は、制御回路5の制御信号を得るための指令値
電圧を設定し、その指令値電圧を所定のステップ幅で逐
次変化させ、太陽電池2の今回の出力電力と前回の出力
電力とを比較して、その電力の増減によってその時点に
おける太陽電池2のP−V特性曲線上における動作領域
を判別し、その判別された動作領域に応じてインバータ
3を駆動する次回の指令値電圧を設定することにより、
太陽電池2の出力電力が常に最大となるように制御して
いる。This maximum power tracking control method of the solar power generation system 1 sets a command value voltage for obtaining a control signal of the control circuit 5, and sequentially changes the command value voltage by a predetermined step width to make a solar cell. The current output power of 2 is compared with the previous output power, and the operating area on the PV characteristic curve of the solar cell 2 at that time is determined by the increase or decrease of the power, and according to the determined operating area. By setting the next command value voltage to drive the inverter 3 by
The output power of the solar cell 2 is controlled to be always the maximum.
【0007】例えば、前回設定された指令値電圧を所定
のステップ幅だけ持ち上げた時に得られた太陽電池2の
出力電力が前回の出力電力と比較して大きい時は、太陽
電池2の動作点がP−V特性曲線の凸形状の左側にある
と判断し、次回の指令値電圧は今回の指令値電圧を更に
所定のステップ幅だけ持ち上げた電圧に設定し、逆に、
太陽電池2の出力電力が前回の出力電力と比較して小さ
い時は、太陽電池2の動作点がP−V特性曲線の凸形状
の右側にあると判断して、次回の指令値電圧は前回の指
令値電圧より更に所定のステップ幅だけ下げた電圧に設
定するようにしている。For example, when the output power of the solar cell 2 obtained when the previously set command value voltage is raised by a predetermined step width is larger than the previous output power, the operating point of the solar cell 2 is It is determined that it is on the left side of the convex shape of the PV characteristic curve, and the next command value voltage is set to a voltage obtained by further increasing the current command value voltage by a predetermined step width.
When the output power of the solar cell 2 is smaller than the output power of the previous time, it is determined that the operating point of the solar cell 2 is on the right side of the convex shape of the PV characteristic curve, and the next command value voltage is The command voltage is set to a voltage lower by a predetermined step width.
【0008】このような太陽光発電システム1の最大電
力追従制御方法は、太陽電池2のP−V特性曲線が凸形
状であり、太陽電池2の動作点がP−V特性曲線の頂点
の両側に位置する時はその頂点側へ移動するように制御
され、常に、太陽電池2の出力が最大となるようにイン
バータ3が駆動制御される。In such a maximum power tracking control method for the solar power generation system 1, the PV characteristic curve of the solar cell 2 has a convex shape, and the operating point of the solar cell 2 is on both sides of the apex of the PV characteristic curve. When it is located at, the inverter 3 is controlled so as to move to its apex side, and the inverter 3 is always drive-controlled so that the output of the solar cell 2 is maximized.
【0009】[0009]
【発明が解決しようとする課題】しかしながら、太陽電
池2のP−V特性曲線が凸形状であり、動作点がその頂
点に位置する時は指令値電圧を変化させてもその出力電
力が変化せず、同様に動作点が開放電圧Vocより大きい
領域に位置する時も、指令値電圧を変化させても出力電
力が変化しない。その結果、動作点が頂点に位置する場
合と開放電圧Vocより大きい領域に位置する場合とで、
両者は出力電力が変化しないという同一の現象となって
いた。However, when the PV characteristic curve of the solar cell 2 has a convex shape and the operating point is located at the apex thereof, the output power thereof does not change even if the command value voltage is changed. Similarly, when the operating point is located in a region larger than the open circuit voltage Voc, the output power does not change even if the command value voltage is changed. As a result, depending on whether the operating point is located at the apex or in the area larger than the open circuit voltage Voc,
Both had the same phenomenon that the output power did not change.
【0010】このように動作点が開放電圧Vocより大き
い領域に位置する場合が、その動作点が頂点に位置する
場合と同一であって判別できないと、太陽電池2が日射
条件の変化などで前記動作点が、P−V特性曲線の右側
の傾斜を急激に低下して開放電圧Vocに達した場合、指
令値電圧を変化しても太陽電池2の出力電力が変化せ
ず、動作点が開放電圧Voc側で固定され、出力電力が得
られない状態になることがあった。When the operating point is located in a region larger than the open-circuit voltage Voc as described above, it is the same as when the operating point is located at the apex and cannot be determined. When the operating point sharply decreases the slope on the right side of the PV characteristic curve and reaches the open circuit voltage Voc, the output power of the solar cell 2 does not change even if the command value voltage is changed, and the operating point is opened. There was a case where the voltage was fixed on the Voc side and output power could not be obtained.
【0011】また、太陽電池2の出力電力は気象状態に
より常に変化しており、太陽電池2の出力電力を前回の
出力電力と単に比較するだけの従来方法では動作点が常
に大きく移動して安定した出力電力が得られないという
問題があった。Further, the output power of the solar cell 2 is constantly changing depending on the weather condition, and in the conventional method in which the output power of the solar cell 2 is simply compared with the previous output power, the operating point is always greatly moved and stable. There was a problem that the output power could not be obtained.
【0012】更に、低日射時に太陽電池の出力電力が低
下することに伴い、その出力電力の計測値が小さくなっ
て最大電力追随制御の実行が困難となって、誤動作する
おそれもあった。Further, as the output power of the solar cell decreases during low solar radiation, the measured value of the output power becomes small and it becomes difficult to execute the maximum power follow-up control, which may cause malfunction.
【0013】そこで、本発明は上記問題点に鑑みて提案
されたもので、その目的とするところは、動作点がP−
V特性曲線の開放電圧側に固定されて出力電力が得られ
なかったり、日射条件の変化等により動作点が大きく変
動することを未然に防止し、更に、低日射時に太陽電池
の出力電力が低下しても、その後、日射量が増加すれば
適正な最大電力追随制御へ速やかに移行し得る太陽光発
電システムの最大電力追随制御方法を提供することにあ
る。Therefore, the present invention has been proposed in view of the above problems, and an object thereof is that the operating point is P-
It is fixed to the open-circuit voltage side of the V characteristic curve and output power cannot be obtained, and the operating point is prevented from fluctuating significantly due to changes in solar radiation conditions, and further, the output power of the solar cell drops during low solar radiation. Even then, it is an object of the present invention to provide a maximum power follow-up control method for a photovoltaic power generation system, which can promptly shift to an appropriate maximum power follow-up control if the amount of solar radiation increases.
【0014】[0014]
【課題を解決するための手段】上記目的を達成するため
の技術的手段として、本発明は、太陽電池に接続された
インバータの制御信号に所定のステップ幅で増減する指
令値電圧を付与し、前記太陽電池から得られた今回の出
力電力と、前回の出力電力に不感帯域を設定した所定の
設定電力を増減した値と比較し、その比較結果に基づい
て前記指令値電圧をステップ幅で増減させて次回の指令
値電圧を設定すると共に、出力電力が前記不感帯域内に
ある時には今回の指令値電圧をステップ幅で減少させて
次回の指令値電圧を設定し、太陽電池の出力が常に最大
となるようにインバータを駆動する太陽光発電システム
の最大電力追随制御方法において、低日射時に太陽電池
の出力電力が低下して所定の設定値以下となった場合、
前回の出力電力にかかわらず、インバータが駆動可能な
電圧を動作下限として前記太陽電池の出力電圧を低下さ
せ、前記インバータを継続的に駆動させるようにしたこ
とを特徴とする。As a technical means for achieving the above object, the present invention provides a control signal of an inverter connected to a solar cell with a command value voltage which increases or decreases in a predetermined step width, The output power of this time obtained from the solar cell is compared with a value obtained by increasing or decreasing a predetermined set power in which the dead band is set to the output power of the previous time, and the command value voltage is increased or decreased by the step width based on the comparison result. And set the next command value voltage, and when the output power is within the dead band, set the next command value voltage by decreasing the current command value voltage by a step width, and the output of the solar cell is always the maximum. In the maximum power tracking control method of the solar power generation system that drives the inverter so that, when the output power of the solar cell is reduced to a predetermined value or less during low solar radiation,
Regardless of the previous output power, the output voltage of the solar cell is lowered by setting the voltage at which the inverter can be driven as the operation lower limit, and the inverter is continuously driven.
【0015】[0015]
【作用】本発明方法では、太陽電池から得られた今回の
出力電力を、前回の出力電力に不感帯域を設定した所定
の設定電力を増減した値と比較するようにしたから、太
陽電池が日射条件等で僅かに変化しても動作点が大きく
変動することはない。また、出力電力が不感帯域内にあ
る時、指令値電圧を所定のステップ幅で減少させるよう
にしたから、動作点が開放電圧よりも大きい領域にあっ
ても、前記動作点がその領域に固定されることはない。In the method of the present invention, the current output power obtained from the solar cell is compared with the value obtained by increasing or decreasing the predetermined output power in which the dead band is set to the previous output power. The operating point does not change greatly even if the conditions slightly change. Also, when the output power is within the dead band, the command value voltage is reduced by a predetermined step width, so that even if the operating point is in a region larger than the open circuit voltage, the operating point is fixed in that region. There is no such thing.
【0016】また、本発明方法では、低日射時に太陽電
池の出力電力が低下することに伴い、その出力電力の計
測値が小さくなって最大電力追随制御の実行が困難にな
っても、前記出力電力が所定の設定値以下となった場合
には、太陽電池の出力電圧を低下させてインバータの駆
動可能な電圧を動作下限として確保するので、前記イン
バータを継続的に駆動させ、その後の日射量の増加に備
えて待機させ、その後、日射量が増加すれば適正な最大
電力追随制御を実行することができる。According to the method of the present invention, the output power of the solar cell is reduced during low solar radiation, and even if the measured value of the output power becomes small and the maximum power follow-up control becomes difficult, When the electric power becomes equal to or less than a predetermined set value, the output voltage of the solar cell is lowered to secure the driveable voltage of the inverter as the operation lower limit, so that the inverter is continuously driven and the amount of solar radiation after that. When the amount of solar radiation increases, an appropriate maximum power follow-up control can be executed.
【0017】[0017]
【実施例】本発明の実施例を図1乃至図5に示して以下
に説明する。Embodiments of the present invention will be described below with reference to FIGS.
【0018】図1は太陽光発電システム1を最大電力制
御するための指令信号を生成するフローチャート、図2
は前記指令信号を生成する指令信号生成部の構成要素を
示すブロック図を示し、まず、指令信号生成部6の構成
を以下に説明する。FIG. 1 is a flow chart for generating a command signal for controlling the maximum power of the solar power generation system 1, FIG.
Shows a block diagram showing constituent elements of a command signal generating section for generating the command signal. First, the structure of the command signal generating section 6 will be described below.
【0019】図2における計測部7は、太陽電池2の出
力回路に接続されてその出力電圧Vcell、出力電流Ice
llを計測する。演算部8は、計測部7で計測した出力電
圧Vcell、出力電流Icellから、太陽電池2の出力電力
P、つまり今回の出力電力Pnow を演算する。演算値記
憶部9は、演算部8で得られた出力電力Pnow を一時ス
トックして前回の出力電力Ppastとする。動作領域判別
部10は、前記出力電力Pnow により太陽電池2の動作
点がP−V特性曲線のどの領域にあるかを判別する。The measuring unit 7 in FIG. 2 is connected to the output circuit of the solar cell 2 and has its output voltage Vcell and output current Ice.
ll is measured. The calculation unit 8 calculates the output power P of the solar cell 2, that is, the current output power Pnow from the output voltage Vcell and the output current Icell measured by the measuring unit 7. The calculated value storage unit 9 temporarily stocks the output power Pnow obtained by the calculation unit 8 and uses it as the previous output power Ppast. The operating area determination unit 10 determines which area of the PV characteristic curve the operating point of the solar cell 2 is in based on the output power Pnow.
【0020】この場合、出力電力Pnow は、演算値記憶
部9で記憶された前回の出力電力Ppastに対して、不感
帯域を設定する所定の設定電力Phistを増減した値と比
較される。即ち、前記設定電力Phistを加味した前回の
出力電力Ppastより今回の出力電力Pnow が大きいか小
さいか或いは不感帯域内かに基づいて、太陽電池2の動
作点がP−V特性曲線の凸形状の左側又は右側に位置す
るか、或いは頂点又は開放電圧より大きい領域に位置す
るかが判断される。In this case, the output power Pnow is compared with a value obtained by increasing or decreasing a predetermined set power Phist for setting the dead band with respect to the previous output power Ppast stored in the calculated value storage unit 9. That is, the operating point of the solar cell 2 is the left side of the convex shape of the PV characteristic curve based on whether the current output power Pnow is larger or smaller than the previous output power Ppast in consideration of the set power Phist, or within the dead band. Alternatively, it is determined whether it is located on the right side, or is located in a region higher than the apex or the open circuit voltage.
【0021】例えば、図3のP−V特性曲線において、
前回設定された指令値電圧Vpastを所定のステップ幅V
stepだけ持ち上げた時、太陽電池2の出力電力Pnow
〔図中の出力電力P2 〕が前回の出力電力Ppast〔図中
の出力電力P1 〕から変化したとすると、今回の出力電
力Pnow 〔P2 〕は、前回の出力電力Ppast〔P1 〕に
設定電力Phistを加えたPpast〔P1 〕+Phistと比較
される。For example, in the PV characteristic curve of FIG.
The previously set command value voltage Vpast is set to a predetermined step width V
Output power Pnow of the solar cell 2 when only step is lifted
If [output power P 2 in the figure] changes from the previous output power Ppast [output power P 1 in the figure], the current output power Pnow [P 2 ] is the previous output power Ppast [P 1 ] Is compared with Ppast [P 1 ] + Phist which is obtained by adding the set power Phist.
【0022】今回の出力電力Pnow 〔P2 〕が、前回の
出力電力Ppast〔P1 〕に設定電力Phistを加えたPpa
st〔P1 〕+Phistより大きい場合、太陽電池2の出力
電力Pが増加していると判別され、動作点がP−V特性
曲線の頂点から左側にあると判別される。このように太
陽電池2の動作領域の判別に±Phistの設定電力を増減
した不感帯域を設けたことにより、太陽電池2の出力特
性が、図示するように日射条件の変動等により微妙な凹
凸状に変動しても、その変動が設定電力Phistの範囲内
であれば、動作領域の判別に影響を受けず、動作点が頻
繁に移動することなく安定した出力電力Pが得られる。The output power Pnow [P 2 ] of this time is Ppa obtained by adding the set power Phist to the output power Ppast [P 1 ] of the previous time.
When it is larger than st [P 1 ] + Phist, it is determined that the output power P of the solar cell 2 is increasing, and the operating point is determined to be on the left side from the apex of the PV characteristic curve. In this way, by providing the dead zone in which the set power of ± Phist is increased or decreased in the determination of the operation area of the solar cell 2, the output characteristics of the solar cell 2 are slightly uneven due to variations in solar radiation conditions as shown in the figure. Even if it fluctuates, if the fluctuation is within the range of the set power Phist, stable output power P is obtained without being affected by the discrimination of the operation region and the operating point does not frequently move.
【0023】また、図2における指令値電圧設定部11
は、上記判別結果に応じて指令値電圧Vset を設定す
る。即ち、P−V特性曲線の頂点から左側では、今回の
指令値電圧Vnow に、その指令値電圧Vnow と前回の指
令値電圧Vpastの差分(Vnow−Vpast)、つまりステ
ップ幅Vstepを加えたものを指令値電圧Vset とし、逆
に、P−V特性曲線の頂点から右側では、前回の指令値
電圧Vpastに、その指令値電圧Vpastと今回の指令値電
圧Vnow の差分(Vpast−Vnow )、つまりステップ幅
Vstepを加えたものを指令値電圧Vset とする。また、
P−V特性曲線の頂点或いは開放電圧より大きい領域で
は、今回の指令値電圧Vnow からステップ幅Vstepを減
じたものを指令値電圧Vset とする。尚、前記指令値電
圧Vset の設定時に使用した指令値電圧Vnow は、指令
値記憶部12に前回の指令値電圧Vpastとして置き換え
てデータ更新する。Further, the command value voltage setting section 11 in FIG.
Sets the command value voltage Vset according to the determination result. That is, on the left side of the apex of the PV characteristic curve, the difference between the command value voltage Vnow of this time and the previous command value voltage Vpast (Vnow-Vpast), that is, the step width Vstep is added to the command value voltage Vnow of this time. The command value voltage Vset is set, and conversely, on the right side of the apex of the PV characteristic curve, the difference (Vpast-Vnow) between the command value voltage Vpast and the command value voltage Vnow of this time, that is, the step, is added to the previous command value voltage Vpast. The command value voltage Vset is obtained by adding the width Vstep. Also,
In the peak of the PV characteristic curve or in a region larger than the open circuit voltage, the command value voltage Vnow minus the step width Vstep is set as the command value voltage Vset. The command value voltage Vnow used when the command value voltage Vset is set is replaced in the command value storage unit 12 as the previous command value voltage Vpast and the data is updated.
【0024】この指令値電圧設定部11では、動作領域
判別部10により出力電力Pnow が不感帯域内と判別さ
れた結果、動作点がP−V特性曲線の頂点或いは開放電
圧より大きい領域に位置すると判別された場合、前述し
たように指令値電圧Vset を今回の指令値電圧Vnow か
らステップ幅Vstepを減じて設定しているから、例え
ば、太陽電池2が日射条件の急激な変化により動作点が
P−V特性曲線の頂点の右側から急激に降下して開放電
圧より大きい領域に位置した場合でも、前記指令値電圧
Vset が開放電圧より小さい領域、つまりP−V特性曲
線の頂点の右側へ向けて移動していくため、動作点が固
定されることはない。In the command value voltage setting section 11, as a result of the output area Pnow being judged to be within the dead band by the operation area judging section 10, it is judged that the operating point is located at the peak of the PV characteristic curve or in the area larger than the open voltage. In this case, since the command value voltage Vset is set by subtracting the step width Vstep from the command value voltage Vnow of this time as described above, for example, the operating point of the solar cell 2 is P- due to a sudden change in the solar radiation condition. Even when the command value voltage Vset is lower than the open voltage, that is, to the right side of the apex of the PV characteristic curve, even when the command value voltage Vset is located in a region higher than the open voltage and suddenly drops from the right side of the apex of the V characteristic curve. Therefore, the operating point is not fixed.
【0025】また、図2における上下限領域判別部13
では、前記指令値電圧Vset が最下限値Vmin より小さ
い〔Vset <Vmin 〕か、或いは最上限値Vmax より大
きい〔Vset >Vmax 〕かを判別する。このように指令
値電圧Vset に上下限を設定すると、例えば、太陽電池
2を図3に示す所望の動作電圧V1 ,V2 間で動作させ
る場合、指令値電圧Vset を不必要に低い電圧から算出
することが防止でき、速やかに最大電力制御に移行する
ことができる。In addition, the upper and lower limit area determination unit 13 in FIG.
Then, it is determined whether the command value voltage Vset is smaller than the minimum lower limit value Vmin [Vset <Vmin] or larger than the maximum upper limit value Vmax [Vset> Vmax]. By setting the upper and lower limits to the command value voltage Vset in this way, for example, when the solar cell 2 is operated between the desired operating voltages V 1 and V 2 shown in FIG. 3, the command value voltage Vset is changed from an unnecessarily low voltage. The calculation can be prevented, and the maximum power control can be quickly performed.
【0026】上下限領域の指令値電圧設定部14では、
前述したように指令値電圧Vset が最下限値Vmin より
小さい場合、前回の指令値電圧Vpastにステップ幅Vst
epを加え、また、最上限値Vmax より大きい場合、前回
の指令値電圧Vpastからステップ幅Vstepを減じて指令
値電圧Vset として再設定する。また、指令値出力部1
5では、前記指令値電圧Vset を今回の指令値電圧Vno
w として制御回路5に付与して制御信号を生成する。In the command value voltage setting section 14 in the upper and lower limit regions,
As described above, when the command value voltage Vset is smaller than the lower limit value Vmin, the step width Vst is added to the previous command value voltage Vpast.
When ep is added and when it is larger than the maximum upper limit value Vmax, the step width Vstep is subtracted from the previous command value voltage Vpast and the command value voltage Vset is reset. Also, the command value output unit 1
In 5, the command value voltage Vset is set to the command value voltage Vno of this time.
It is given to the control circuit 5 as w to generate a control signal.
【0027】出力低下判別部16では、低日射時に太陽
電池2の出力電力が低下していることを判別する。つま
り低日射時、図4に示すP−V特性曲線において、まず
前記出力電力Pが低下し、ある程度まで低下すると開放
電圧Vocが低下するという特徴を有する。そこで、この
出力低下判別部16では、前記出力電力Pの低下に対し
て所定の設定値Pmin を設定する。一方、出力低下の指
令値電圧設定部17では、今回の指令値電圧Vnow から
ステップ幅Vstepを減じて指令値電圧Vset として再設
定すると共に、前記指令値電圧Vnow を前回の指令値電
圧Vpastに置き換えてデータ更新する。The output decrease determination unit 16 determines that the output power of the solar cell 2 is decreased during low solar radiation. That is, when the solar radiation is low, the P-V characteristic curve shown in FIG. 4 is characterized in that the output power P first decreases, and when it decreases to a certain extent, the open circuit voltage Voc decreases. Therefore, the output decrease determination unit 16 sets a predetermined set value Pmin for the decrease in the output power P. On the other hand, the output decrease command value voltage setting unit 17 subtracts the step width Vstep from the current command value voltage Vnow to reset it as the command value voltage Vset, and replaces the command value voltage Vnow with the previous command value voltage Vpast. And update the data.
【0028】初期値設定部18では、指令値電圧Vset
の初期電圧Vset0、指令値電圧Vset のステップ幅Vst
ep、不感帯域を設定する設定電力Phist、指令値電圧V
setの最下限値Vmin 及び最上限値Vmax 、出力低下時
での設定値Pmin 等を設定する。尚、これらの各構成要
素はコンピュータ19で制御されている。In the initial value setting section 18, the command value voltage Vset
Initial voltage Vset 0 , step width Vst of command value voltage Vset
ep, set power Phist for setting dead band, command value voltage V
The lower limit value Vmin and the upper limit value Vmax of the set, the set value Pmin when the output is reduced, etc. are set. Each of these constituent elements is controlled by the computer 19.
【0029】このような構成の指令信号生成部6は図1
に示すようなフローチャートに従い作動する。The command signal generator 6 having such a configuration is shown in FIG.
It operates according to the flowchart shown in.
【0030】図1において、ステップ101では、演算
値記憶部9の出力電力Ppast、指令値記憶部12の指令
値電圧Vpast及び指令値出力部15の指令値電圧Vnow
がそれぞれ初期設定される。ここで、指令値電圧Vnow
に設定される初期電圧Vset0はインバータ3の駆動開始
電圧であり、図3のP−V特性曲線上の適宜の電圧値が
選択される。In FIG. 1, in step 101, the output power Ppast of the calculated value storage unit 9, the command value voltage Vpast of the command value storage unit 12, and the command value voltage Vnow of the command value output unit 15.
Are initialized respectively. Here, the command value voltage Vnow
The initial voltage Vset 0 set to is the drive start voltage of the inverter 3, and an appropriate voltage value on the PV characteristic curve of FIG. 3 is selected.
【0031】ステップ102では、太陽電池2の出力電
圧Vcell、出力電流Icellが計測部7に取り込まれ、演
算部8で前記出力電圧Vcellと出力電流Icellとが乗算
〔Vcell×Icell〕されて、出力電力Pnow が算出され
る。In step 102, the output voltage Vcell and the output current Icell of the solar cell 2 are taken into the measuring section 7, and the output voltage Vcell and the output current Icell are multiplied [Vcell × Icell] in the calculating section 8 and output. The electric power Pnow is calculated.
【0032】ステップ103では、出力低下判別部16
により前記出力電力Pnow が、設定された所定の設定値
Pmin と比較され、低日射による出力低下の有無が判別
される。その結果、低日射により太陽電池2の出力電力
Pnow が低下して前記設定値Pmin より小さくなると、
出力低下の指令値電圧設定部17により、今回の指令値
電圧Vnow からステップ幅Vstepを減じて指令値電圧V
set として再設定すると共に、前記指令値電圧Vnow を
前回の指令値電圧Vpastに置き換えてデータ更新する。In step 103, the output reduction determination unit 16
Thus, the output power Pnow is compared with a predetermined set value Pmin that has been set, and it is determined whether or not the output has decreased due to low solar radiation. As a result, when the output power Pnow of the solar cell 2 decreases due to low solar radiation and becomes smaller than the set value Pmin,
The command value voltage setting unit 17 for output reduction subtracts the step width Vstep from the command value voltage Vnow of this time to obtain the command value voltage Vnow.
The data is updated by resetting as the set and replacing the command value voltage Vnow with the previous command value voltage Vpast.
【0033】このようにして前記指令値電圧Vset に基
づいて、後述のステップ105で太陽電池2の出力電圧
Vcellをインバータ3の駆動可能な電圧である最下限値
Vmin まで低下させ、その最下限値Vmin を維持するこ
とによりインバータ3の駆動可能な電圧を確保して、イ
ンバータ3を継続的に駆動する。尚、太陽電池1の出力
電力Pnow が前記設定値Pmin より大きければ、次のス
テップ104を実行する。In this way, based on the command value voltage Vset, the output voltage Vcell of the solar cell 2 is lowered to the lower limit value Vmin which is the voltage that can drive the inverter 3 in step 105 described later, and the lower limit value thereof is set. By maintaining Vmin, the drivable voltage of the inverter 3 is secured and the inverter 3 is continuously driven. If the output power Pnow of the solar cell 1 is larger than the set value Pmin, the next step 104 is executed.
【0034】ステップ104では、動作領域判別部10
により前記出力電力Pnow が前回の出力電力Ppastに設
定電力Phistを加味した値と比較され、P−V特性曲線
上での動作領域が判別される。その動作領域の判別後、
指令値電圧設定部11により、その動作領域に応じた指
令値電圧Vset を設定する。また、指令値電圧Vsetの
設定後、指令値電圧Vnow を指令値記憶部12で前回の
出力電力Vpastとして置き換えてデータ更新する。In step 104, the operation area discrimination unit 10
Thus, the output power Pnow is compared with a value obtained by adding the set power Phist to the previous output power Ppast, and the operating region on the PV characteristic curve is determined. After determining the operating area,
The command value voltage setting unit 11 sets the command value voltage Vset according to the operating region. After setting the command value voltage Vset, the command value voltage Vnow is replaced in the command value storage unit 12 as the previous output power Vpast, and the data is updated.
【0035】ステップ105では、上下限領域判別部1
3により前記指令値電圧Vset が最上下限値Vmin ,V
max と比較され、その上下限値Vmin ,Vmax を超える
指令値電圧Vset については、上下限領域の指令値電圧
設定部14で指令値電圧Vset が再設定される。In step 105, the upper and lower limit area discrimination unit 1
3, the command value voltage Vset is the upper and lower limit values Vmin, V
For the command value voltage Vset which is compared with max and exceeds the upper and lower limit values Vmin and Vmax, the command value voltage Vset is reset by the command value voltage setting unit 14 in the upper and lower limit regions.
【0036】ステップ106では、前記指令値電圧Vse
t を指令値出力部15に送出して今回の指令値電圧Vno
w に置き換えると共に、ステップ102で演算された出
力電力Pnow を演算値記憶部9に送出して前回の出力電
力Ppastに置き換えてデータ更新する。In step 106, the command value voltage Vse
t is sent to the command value output unit 15 to send the command value voltage Vno of this time.
The output power Pnow calculated in step 102 is sent to the calculated value storage unit 9 and replaced with the previous output power Ppast to update the data.
【0037】ステップ107では、指令値出力部15に
送出された指令値電圧Vset を今回の指令値電圧Vnow
として制御回路5の制御信号に付与しインバータ3を駆
動制御する。以下、ステップ102以降を繰返す。In step 107, the command value voltage Vset sent to the command value output section 15 is changed to the command value voltage Vnow of this time.
Is added to the control signal of the control circuit 5 to drive and control the inverter 3. Hereinafter, step 102 and subsequent steps are repeated.
【0038】以上のように太陽電池2の出力電力Pnow
を単に前回の出力電力Ppastと比較するだけでなく、前
回の出力電力Ppastに不感帯域を設定した所定の設定電
力Phistを増減した値と比較することにより、太陽電池
2の出力特性が気象状態等により若干変化しても動作点
が大きく移動せずに安定した出力が得られる。また、出
力電力が前記不感帯域内にあるとき、次回の指令値電圧
を今回の指令値電圧Vnow から所定のステップ幅Vstep
だけ減少させて設定することにより、動作点がP−V特
性曲線の開放電圧Vocより大きい領域に固定されること
はない。また、指令値電圧Vset に上下限を設け、早期
に所定の動作範囲の指令値電圧Vset を付与することに
より、システムの立上がりが早くなり、早期に最大電力
制御状態に到達できる。As described above, the output power Pnow of the solar cell 2
Is not only compared with the previous output power Ppast, but is also compared with a value obtained by increasing or decreasing a predetermined set power Phist in which the dead band is set to the previous output power Ppast, so that the output characteristics of the solar cell 2 are meteorological conditions, etc. As a result, a stable output can be obtained without a large movement of the operating point even if it changes slightly. When the output power is within the dead band, the next command value voltage is changed from the current command value voltage Vnow to a predetermined step width Vstep.
The operating point is not fixed to a region larger than the open circuit voltage Voc of the P-V characteristic curve by setting only by decreasing the value. Further, by setting the upper and lower limits of the command value voltage Vset and giving the command value voltage Vset in a predetermined operation range early, the system starts up quickly and the maximum power control state can be reached early.
【0039】尚、上記実施例では、図3に示すように単
調に増加減する凸形状のP−V特性曲線について説明し
たが、太陽電池2の設置条件等の諸条件により必ずしも
図3のような凸形状になるとは限らず、例えば、図5に
示すように出力電力Pf となる平坦な帯域が存在するP
−V特性曲線となる場合もある。このようなP−V特性
曲線の場合、従来方法では平坦な帯域で動作点が固定さ
れ最大出力Pmax が得られないことがあったが、本発明
方法では平坦な帯域で動作点が固定されることなく確実
に最大出力Pmax で駆動制御することができる。In the above embodiment, the PV characteristic curve having a convex shape that monotonously increases and decreases as shown in FIG. 3 has been described. However, it may not always be as shown in FIG. 3 depending on various conditions such as installation conditions of the solar cell 2. It does not always have a convex shape, and for example, as shown in FIG.
It may be a −V characteristic curve. In the case of such a P-V characteristic curve, the operating point was fixed in the flat band and the maximum output Pmax could not be obtained in the conventional method, but the operating point was fixed in the flat band in the method of the present invention. It is possible to reliably control the drive with the maximum output Pmax.
【0040】[0040]
【発明の効果】本発明方法によれば、低日射時に太陽電
池の出力電力が低下することに伴い、その出力電力の計
測値が小さくなって最大電力追随制御の実行が困難にな
っても、誤動作することなく、前記出力電力が所定の設
定値以下となった場合、太陽電池の出力電圧をインバー
タの駆動可能な電圧を動作下限として確保し前記インバ
ータを継続的に駆動させるので、その後、日射量が増加
すれば適正な最大電力追随制御を速やかに実行すること
ができ、信頼性の高い太陽光発電システムを提供でき
る。According to the method of the present invention, even if the measured value of the output power becomes small and the execution of the maximum power follow-up control becomes difficult as the output power of the solar cell decreases at the time of low solar radiation, If the output power becomes equal to or lower than a predetermined set value without malfunctioning, the output voltage of the solar cell is secured as the drive lower limit of the inverter and the inverter is continuously driven. If the amount increases, proper maximum power tracking control can be executed promptly, and a highly reliable solar power generation system can be provided.
【図1】本発明方法で最大電力追随制御の指令信号を作
成するフローチャートFIG. 1 is a flowchart for creating a command signal for maximum power tracking control by the method of the present invention.
【図2】本発明方法を実行する太陽光発電システムの指
令信号作成部の構成を示すブロック図FIG. 2 is a block diagram showing the configuration of a command signal generation unit of a photovoltaic power generation system that executes the method of the present invention.
【図3】本発明方法を説明するための太陽電池のP−V
特性曲線を示す波形図FIG. 3 is a PV of a solar cell for explaining the method of the present invention.
Waveform diagram showing the characteristic curve
【図4】低日射時での太陽電池の出力低下を説明するた
めのP−V特性曲線を示す波形図FIG. 4 is a waveform diagram showing a PV characteristic curve for explaining a decrease in output of the solar cell under low solar radiation.
【図5】太陽電池のP−V特性曲線の他例を示す波形図FIG. 5 is a waveform diagram showing another example of the PV characteristic curve of the solar cell.
【図6】太陽光発電システムの概略構成を示す回路図FIG. 6 is a circuit diagram showing a schematic configuration of a solar power generation system.
【図7】従来方法を説明するための太陽電池のP−V特
性曲線を示す波形図FIG. 7 is a waveform diagram showing a PV characteristic curve of a solar cell for explaining a conventional method.
1 太陽光発電システム 2 太陽電池 3 インバータ 4 系統電源 5 制御回路 P 出力電力 Vcell 出力電圧 Vpast 前回の指令値電圧 Vnow 今回の指令値電圧 Vset 指令値電圧 Ppast 前回の出力電力 Pnow 今回の出力電力 Phist 設定電力 Vstep ステップ幅 Pmin 設定値 1 Solar power generation system 2 Solar cell 3 Inverter 4 System power supply 5 Control circuit P Output power Vcell Output voltage Vpast Previous command value voltage Vnow Current command value voltage Vset Command value voltage Ppast Last output power Pnow Current output power Phist setting Electric power Vstep Step width Pmin Set value
Claims (1)
信号に所定のステップ幅で増減する指令値電圧を付与
し、前記太陽電池から得られた今回の出力電力と、前回
の出力電力に不感帯域を設定した所定の設定電力を増減
した値と比較し、その比較結果に基づいて前記指令値電
圧をステップ幅で増減させて次回の指令値電圧を設定す
ると共に、出力電力が前記不感帯域内にある時には今回
の指令値電圧をステップ幅で減少させて次回の指令値電
圧を設定し、太陽電池の出力が常に最大となるようにイ
ンバータを駆動する太陽光発電システムの最大電力追随
制御方法において、 低日射時に太陽電池の出力電力が低下して所定の設定値
以下となった場合、前回の出力電力にかかわらず、イン
バータが駆動可能な電圧を動作下限として前記太陽電池
の出力電圧を低下させ、前記インバータを継続的に駆動
させるようにしたことを特徴とする太陽光発電システム
の最大電力追随制御方法。1. A dead band for the current output power and the previous output power obtained from the solar cell by applying a command value voltage that increases or decreases with a predetermined step width to a control signal of an inverter connected to the solar cell. The predetermined set power that has been set is compared with the increased or decreased value, and based on the comparison result, the command value voltage is increased or decreased by a step width to set the next command value voltage, and the output power is within the dead band. Sometimes this command value voltage is reduced by a step width to set the next command value voltage, and in the maximum power tracking control method of the solar power generation system that drives the inverter so that the output of the solar cell is always maximized, When the output power of the solar cell decreases at the time of solar radiation and becomes less than a predetermined set value, regardless of the previous output power, the voltage that can be driven by the inverter is set as the lower limit of operation of the solar cell. Output voltage reduces the maximum power follow control method of a solar power generation system is characterized in that so as to continuously drive the inverter.
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JP7025089A JPH08221143A (en) | 1995-02-14 | 1995-02-14 | Maximum electric power follow-up control method for solar light power generation system |
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Application Number | Priority Date | Filing Date | Title |
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JP7025089A JPH08221143A (en) | 1995-02-14 | 1995-02-14 | Maximum electric power follow-up control method for solar light power generation system |
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Family
ID=12156201
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009170640A (en) * | 2008-01-16 | 2009-07-30 | Aisin Seiki Co Ltd | Photovoltaic power generator using dye-sensitized solar cell |
CN103019294A (en) * | 2011-09-28 | 2013-04-03 | 上海康威特吉能源技术有限公司 | Maximum power point tracking (MPPT) method of self-adaption disturbance frequency and step |
KR101286578B1 (en) * | 2013-01-23 | 2013-07-22 | 유한회사 주왕산업 | Solar power generation with energy storage capabilities connected unit |
KR101297833B1 (en) * | 2011-09-22 | 2013-08-26 | 카코뉴에너지 주식회사 | Solar energy generation system tracking adaptive maximum power point and its method |
WO2015016006A1 (en) * | 2013-07-30 | 2015-02-05 | 株式会社日立産機システム | System and method for controlling solar power generation system |
CN105807840A (en) * | 2016-03-05 | 2016-07-27 | 厦门科华恒盛股份有限公司 | Photovoltaic system maximum power point tracing method |
-
1995
- 1995-02-14 JP JP7025089A patent/JPH08221143A/en active Pending
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2009170640A (en) * | 2008-01-16 | 2009-07-30 | Aisin Seiki Co Ltd | Photovoltaic power generator using dye-sensitized solar cell |
KR101297833B1 (en) * | 2011-09-22 | 2013-08-26 | 카코뉴에너지 주식회사 | Solar energy generation system tracking adaptive maximum power point and its method |
CN103019294A (en) * | 2011-09-28 | 2013-04-03 | 上海康威特吉能源技术有限公司 | Maximum power point tracking (MPPT) method of self-adaption disturbance frequency and step |
KR101286578B1 (en) * | 2013-01-23 | 2013-07-22 | 유한회사 주왕산업 | Solar power generation with energy storage capabilities connected unit |
WO2015016006A1 (en) * | 2013-07-30 | 2015-02-05 | 株式会社日立産機システム | System and method for controlling solar power generation system |
CN105807840A (en) * | 2016-03-05 | 2016-07-27 | 厦门科华恒盛股份有限公司 | Photovoltaic system maximum power point tracing method |
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