JPH07322506A - Detection operation of single operation - Google Patents
Detection operation of single operationInfo
- Publication number
- JPH07322506A JPH07322506A JP6110657A JP11065794A JPH07322506A JP H07322506 A JPH07322506 A JP H07322506A JP 6110657 A JP6110657 A JP 6110657A JP 11065794 A JP11065794 A JP 11065794A JP H07322506 A JPH07322506 A JP H07322506A
- Authority
- JP
- Japan
- Prior art keywords
- detection
- isolated operation
- islanding
- inverter
- change
- Prior art date
- Legal status (The legal status 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 status listed.)
- Pending
Links
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
Landscapes
- Photovoltaic Devices (AREA)
- Supply And Distribution Of Alternating Current (AREA)
- Inverter Devices (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は、分散型電源の系統連系
システムにおける単独運転検出方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an isolated operation in a grid-connected system of distributed power sources.
【0002】[0002]
【従来の技術】近年、太陽電池や燃料電池などの数KW
程度の直流電源と、その出力を交流に変換するインバー
タとを備えた分散電源設備を商用電力系統と連系(接
続)し、系統に電力を逆潮流したり家電製品などの負荷
に給電する系統連系システムが実用化されている。2. Description of the Related Art In recent years, several kW for solar cells, fuel cells, etc.
A system that interconnects (connects) a distributed power supply facility that includes a DC power supply of a certain degree and an inverter that converts the output of the power supply to an AC, and reverses the flow of power to the grid and supplies power to loads such as home appliances. The interconnection system has been put to practical use.
【0003】系統連系システムでは、商用電力系統の保
全作業の安全を確保するため、商用電力系統の不測の停
電時及び作業停電時において、どの様な状態の場合に
も、特に直流電源と系統連系点より電力需要家側の負荷
が平衡しており最も停電を検出しづらい状態の場合に
も、直ちにインバータの動作を停止させるか、又は直ち
に開閉器を作動させて連系を解除することにより、イン
バータを商用電力系統から解列させる機能、すなわちイ
ンバータの単独運転を防止する機能が不可欠である。In the grid interconnection system, in order to ensure the safety of maintenance work of the commercial power system, no matter what state the commercial power system is subjected to unexpected power failure or work power failure, especially the DC power source and the system Even if the load on the power consumer side is balanced from the interconnection point and it is the most difficult to detect a power outage, immediately stop the operation of the inverter or immediately activate the switch to cancel the interconnection. Therefore, the function of disconnecting the inverter from the commercial power system, that is, the function of preventing independent operation of the inverter is essential.
【0004】そこで、単独運転検出方法として、受動的
方法と能動的方法とに分類される種々の方法が提案され
ている。ただし、実際には単独運転を確実に検出するた
め、受動的方法による検出と能動的方法による検出とが
並列的に実施され、少なくとも一方の方法により単独運
転を検出した場合に、直ちにインバータの解列が行われ
る。Therefore, various methods classified into a passive method and an active method have been proposed as the isolated operation detecting method. However, in practice, detection by the passive method and detection by the active method are carried out in parallel in order to reliably detect the islanding operation, and when the islanding operation is detected by at least one of the methods, the inverter solution is immediately detected. The columns are done.
【0005】一般に、電流制御方式のインバータを備え
た太陽光発電システムでは、受動的な検出方法として、
柱上トランスの励磁特性に起因した第3次高調波成分の
急激な増加を検出する3次高調波電圧歪急増検出方法が
用いられている。また、能動的な検出方法として、イン
バータの出力電力(有効電力)を数Hz程度の周波数の
周期で且つ適当な変動幅で変動させておき、それに応じ
た連系点状態(電圧、電流、又は周波数)の周期変動を
検出する有効電力変動方法が用いられている。Generally, in a solar power generation system equipped with a current control type inverter, a passive detection method is as follows.
A third harmonic voltage distortion rapid increase detection method is used which detects a rapid increase in the third harmonic component due to the excitation characteristics of the pole transformer. Further, as an active detection method, the output power (active power) of the inverter is fluctuated in a cycle of a frequency of about several Hz and with an appropriate fluctuation width, and the interconnection point state (voltage, current, or The active power fluctuation method that detects the periodic fluctuation of frequency) is used.
【0006】ところで、能動的な検出方法では、検出感
度に依存する所定値以上の変動幅でインバータ出力を積
極的に変動させる必要がある。例えば、従来の太陽光発
電システムでは、太陽電池の発電電力の10%程度の一
定変動幅で出力有効電力が変動するようにインバータ制
御が行われていた。By the way, in the active detection method, it is necessary to positively fluctuate the inverter output within a fluctuation width of a predetermined value or more depending on the detection sensitivity. For example, in a conventional photovoltaic power generation system, inverter control is performed so that the output active power fluctuates within a constant fluctuation range of about 10% of the power generated by the solar cell.
【0007】[0007]
【発明が解決しようとする課題】そのため、従来では、
単独運転検出のための出力変動により、太陽電池の動作
点が最適動作点から周期的に比較的に大きくずれるの
で、太陽電池の発電能力の有効利用の面で不利であると
いう問題があった。Therefore, in the prior art,
The operating point of the solar cell periodically deviates relatively greatly from the optimum operating point due to the output fluctuation for detecting the islanding operation, which is disadvantageous in terms of effective utilization of the power generation capacity of the solar cell.
【0008】なお、能動的検出に際して、単独運転時に
顕著となる連系点状態の変動を正帰還増幅で強調するこ
とにより、検出を容易化する手法が知られている。しか
し、その手法を用いた場合にも、検出の信頼性を確保す
る上でインバータ出力の変動幅を極端に小さくすること
はできない。In the active detection, there is known a method for facilitating the detection by emphasizing the change in the interconnection point state, which is remarkable in the isolated operation, by the positive feedback amplification. However, even when that method is used, the fluctuation range of the inverter output cannot be extremely reduced in order to secure the detection reliability.
【0009】本発明は、上述の問題に鑑みてなされたも
ので、検出の信頼性を確保しつつ、インバータ出力の変
動幅の低減を図り、直流発電能力の利用率を高めること
を目的としている。The present invention has been made in view of the above problems, and it is an object of the present invention to reduce the fluctuation range of the inverter output and increase the utilization rate of the DC power generation capacity while ensuring the reliability of detection. .
【0010】[0010]
【課題を解決するための手段】請求項1の発明に係る方
法は、上述の課題を解決するため、インバータの出力電
力を周期的に変動させておき、それにより単独運転時に
現れる一定周期の連系点状態変動を検出する能動的単独
運転検出と、単独運転への移行時に現れる連系点の特定
状態量の変化を検出する受動的単独運転検出とを、並列
的に行う単独運転検出方法であって、前記特定状態量が
予め設定した疑似単独運転基準値を越えるときには、前
記特定状態量が前記疑似単独運転基準値を越えないとき
に比べて、前記出力電力の変動幅を大きくするものであ
る。In order to solve the above-mentioned problems, the method according to the invention of claim 1 is such that the output power of the inverter is periodically changed, and thereby the continuous cycle of a constant cycle that appears during islanding operation. With the islanding detection method that performs active islanding detection that detects system point fluctuations and passive islanding detection that detects changes in the specific state quantity of the interconnection point that appears when switching to islanding operation in parallel. Therefore, when the specific state quantity exceeds a preset pseudo isolated operation reference value, the fluctuation range of the output power is made larger than when the specific state quantity does not exceed the pseudo isolated operation reference value. is there.
【0011】請求項2の発明に係る方法は、単独運転時
に現れる一定周期の連系点状態変動を検出する能動的単
独運転検出と、単独運転への移行時に現れる連系点電圧
の第3次高調波成分の急増を検出する受動的単独運転検
出とを、並列的に行う単独運転検出方法であって、前記
第3次高調波成分の変化量が予め設定した疑似単独運転
基準値を越えるときには、前記変化量が前記疑似単独運
転基準値を越えないときに比べて、前記出力電力の変動
幅を大きくするものである。According to the second aspect of the present invention, the active isolated operation detection for detecting a fixed period change in the connected point state occurring during the isolated operation and the third order of the connected point voltage appearing during the transition to the isolated operation. A method for detecting an islanding operation in parallel with a passive islanding detection for detecting a sudden increase in harmonic components, wherein the amount of change in the third harmonic component exceeds a preset pseudo islanding reference value. The fluctuation range of the output power is made larger than when the change amount does not exceed the pseudo isolated operation reference value.
【0012】[0012]
【作用】能動的単独運転検出におけるインバータの出力
電力の変動幅は、受動的単独運転検出における監視対象
である連系点の特定状態量(例えば連系点電圧に含まれ
る3次高調波成分の変化量又は絶対量)に応じて変更さ
れる。The fluctuation range of the output power of the inverter in the active islanding detection is determined by the specific state quantity of the interconnection point that is the monitoring target in the passive islanding detection (for example, the third harmonic component included in the interconnection point voltage. Change amount or absolute amount).
【0013】すなわち、図6に模式的に示すように、特
定状態量ΔVhvが疑似単独運転基準値Vth2を越え
る非平常状態の場合には、単独運転になった時点で確実
に検出することのできる顕著な連系点状態変動が生じる
ように、出力電力の変動幅wとして比較的に大きい値が
設定される。これに対して、特定状態量ΔVhvが疑似
単独運転基準値Vth2を越えない平常状態の場合(明
らかに単独運転ではない場合)には、非平常状態に比べ
て小さい値(零を含む)が変動幅wとして設定される。That is, as schematically shown in FIG. 6, when the specific state amount ΔVhv exceeds the pseudo isolated operation reference value Vth2 in an abnormal state, it can be reliably detected at the time of the isolated operation. A relatively large value is set as the fluctuation range w of the output power so that a noticeable fluctuation in the interconnection point state occurs. On the other hand, when the specific state amount ΔVhv does not exceed the pseudo independent operation reference value Vth2 in the normal state (when it is clearly not in the independent operation), a smaller value (including zero) is changed as compared with the abnormal state. It is set as the width w.
【0014】これにより、運転期間の大半を占める平常
状態の期間におけるインバータ出力の低下を最小限に抑
えることができ、直流発電電力の利用率を高めることが
できる。As a result, it is possible to minimize the reduction in the inverter output during the normal period, which occupies most of the operation period, and to increase the utilization rate of the DC power generation.
【0015】[0015]
【実施例】図1は本発明を適用した太陽光発電システム
1の回路構成を示すブロック図、図2はPWM制御部2
2の構成を機能的に示すブロック図、図3は3次高調波
抽出部40の構成を示すブロック図である。1 is a block diagram showing a circuit configuration of a photovoltaic power generation system 1 to which the present invention is applied, and FIG. 2 is a PWM control unit 2
2 is a block diagram functionally showing the configuration of FIG. 2, and FIG. 3 is a block diagram showing the configuration of the third-order harmonic extraction unit 40.
【0016】図1において、太陽光発電システム1は、
定格電圧が200V程度の太陽電池10と、電圧形電流
制御方式のインバータ20とから構成され、図示しない
配電盤や電力計などを介して商用電力系統2と連系され
ている。配電線3には各種の家電製品などの負荷Zが接
続されている。並列運転時において、連系点状態(例え
ば電圧振幅)は商用電力系統2によって規定され、イン
バータ20の出力電力変動に係わらずほぼ一定である。
しかし、単独運転時においては、連系点状態にインバー
タ20の出力電力変動の影響が顕著に現れる。In FIG. 1, the solar power generation system 1 is
It is composed of a solar cell 10 having a rated voltage of about 200 V and an inverter 20 of a voltage-type current control system, and is connected to a commercial power system 2 via a switchboard, a power meter, etc. not shown. A load Z such as various home appliances is connected to the distribution line 3. During parallel operation, the interconnection point state (for example, voltage amplitude) is defined by the commercial power system 2 and is substantially constant regardless of the output power fluctuation of the inverter 20.
However, in the isolated operation, the influence of the output power fluctuation of the inverter 20 remarkably appears in the interconnection point state.
【0017】インバータ20は、複数のスイッチング素
子からなるインバータ主回路21、PWM制御部22、
出力電流Ioを検出する変流器CT、出力電圧(連系点
の電圧)Voを検出する変圧器PT、マイクロコンピュ
ータ24、3次高調波抽出部40、及び系統保護用の遮
断器CBなどから構成されている。なお、PWM制御部
22及びマイクロコンピュータ24には、変圧器PTに
よって例えば1/30に降圧された出力電圧Voが入力
される。The inverter 20 includes an inverter main circuit 21 composed of a plurality of switching elements, a PWM control section 22,
From the current transformer CT which detects the output current Io, the transformer PT which detects the output voltage (voltage at the interconnection point) Vo, the microcomputer 24, the third harmonic extraction unit 40, the circuit breaker CB, etc. It is configured. The PWM control unit 22 and the microcomputer 24 are supplied with the output voltage Vo stepped down by, for example, 1/30 by the transformer PT.
【0018】PWM制御部22は、インバータ主回路2
1のスイッチング制御を担い、太陽電池10の出力電圧
(直流入力電圧)Viがマイクロコンピュータ24によ
って与えられる電圧指令値Vrefと一致するように、
出力電流Ioを調整する。The PWM control unit 22 includes the inverter main circuit 2
1 for controlling the switching so that the output voltage (DC input voltage) Vi of the solar cell 10 matches the voltage command value Vref given by the microcomputer 24.
Adjust the output current Io.
【0019】すなわち、PWM制御部22では、図2の
ように、比較部221によって電圧Viと電圧指令値V
refとの差を示す入力誤差信号Saが生成される。こ
のとき、電圧Viの検出には例えばアイソレーション増
幅器220が用いられる。乗算処理部223によって、
入力誤差信号Saとバンドパスフィルタ部222が抽出
した出力電圧Voの基本周波数成分Sbとの乗算が行わ
れ、制御目標値を示す電流指令値信号Siが生成され
る。電流指令値信号Siには、エラー増幅部224にお
いて出力電流Ioのフィードバック信号Scによる補正
及び適当な増幅が施される。補正後の電流指令値信号S
iに基づいて、パルス生成部225によって、スイッチ
ング素子の導通期間を規定するPWMパルスPwmが生
成される。そのPWMパルスPwmがゲート回路226
を介してドライバ回路227へ送られ、ドライバ回路2
27によってインバータ主回路21の制御信号であるス
イッチングパルスPswが生成される。That is, in the PWM control unit 22, as shown in FIG. 2, the comparison unit 221 controls the voltage Vi and the voltage command value V.
An input error signal Sa indicating the difference from ref is generated. At this time, for example, the isolation amplifier 220 is used to detect the voltage Vi. By the multiplication processing unit 223,
The input error signal Sa is multiplied by the fundamental frequency component Sb of the output voltage Vo extracted by the bandpass filter unit 222, and the current command value signal Si indicating the control target value is generated. The current command value signal Si is corrected and appropriately amplified by the feedback signal Sc of the output current Io in the error amplifier 224. Current command value signal S after correction
Based on i, the pulse generator 225 generates a PWM pulse Pwm that defines the conduction period of the switching element. The PWM pulse Pwm is the gate circuit 226.
To the driver circuit 227 via the driver circuit 2
A switching pulse Psw, which is a control signal for the inverter main circuit 21, is generated by 27.
【0020】マイクロコンピュータ24は、インバータ
20の全体制御を担い、上述の電圧指令値Vrefを適
当に設定してPWM制御部22に与えるとともに、3次
高調波抽出部40の出力信号Shvと連系点状態量であ
る出力電圧Voとを監視して単独運転状態を検出する。
なお、電圧指令値Vrefとして、通常は太陽電池10
の最適動作電圧の近辺の値が設定されるが、この電圧指
令値Vrefは、能動的単独運転検出のための変調処理
により、商用周波数と比べて十分に低い2Hz程度の周
波数の周期で変動する。そして、その変動幅は後述の受
動的検出処理により、連系点状態に応じて変更される。The microcomputer 24 is responsible for overall control of the inverter 20, appropriately sets the above-mentioned voltage command value Vref, and supplies it to the PWM control section 22, and also interconnects with the output signal Shv of the third harmonic extraction section 40. The isolated operation state is detected by monitoring the output voltage Vo which is the point state quantity.
In addition, as the voltage command value Vref, the solar cell 10 is normally used.
A value in the vicinity of the optimum operating voltage is set, but this voltage command value Vref fluctuates in a cycle of a frequency of about 2 Hz which is sufficiently lower than the commercial frequency due to the modulation processing for active islanding detection. . Then, the fluctuation range is changed according to the interconnection point state by a passive detection process described later.
【0021】3次高調波抽出部40は、図3のように、
入力レベル調整部41、適当にレベル調整された連系点
電圧Voから第3次高調波成分を抽出するバンドパスフ
ィルタ42、抽出された第3次高調波成分の全波整流を
行う絶対値回路43、及び第3次高調波成分の振幅に応
じた電圧レベルの高調波抽出信号Shvを出力する積分
回路44から構成されている。The third harmonic extraction unit 40, as shown in FIG.
An input level adjuster 41, a bandpass filter 42 for extracting a third harmonic component from the interconnection point voltage Vo whose level is adjusted appropriately, and an absolute value circuit for performing full-wave rectification of the extracted third harmonic component. 43 and an integrating circuit 44 that outputs the harmonic extraction signal Shv of a voltage level corresponding to the amplitude of the third harmonic component.
【0022】次に、マイクロコンピュータ24が実行す
る単独運転検出処理の内容を説明する。図4は単独運転
検出処理のフローチャート、図5は受動的検出処理のフ
ローチャートである。Next, the contents of the islanding operation detection process executed by the microcomputer 24 will be described. FIG. 4 is a flowchart of the islanding operation detection process, and FIG. 5 is a flowchart of the passive detection process.
【0023】単独運転検出処理は、受動的検出処理(#
1)と能動的検出処理(#2)とから構成されている。
能動的検出処理では、周波数解析などによって、電圧指
令値Vrefの変調に伴う連系点電圧Voの2Hzの変
動(ゆらぎ)を検出する。The islanding detection process is a passive detection process (#
1) and active detection processing (# 2).
In the active detection process, a 2 Hz fluctuation (fluctuation) in the interconnection point voltage Vo due to the modulation of the voltage command value Vref is detected by frequency analysis or the like.
【0024】図5の受動的検出処理において、マイクロ
コンピュータ24は、連系点における特定状態量として
アナログポートに入力された高調波抽出信号Shvを一
定周期(例えば10ms)でサンプリングし、それと並
行して複数回分(例えば5回分)のサンプリング値の平
均値を求め、その平均値を第3次高調波成分の測定値V
hvとして取り込む。つまり、50(=10×5)ms
の周期で第3次高調波成分を測定する(#11)。In the passive detection process of FIG. 5, the microcomputer 24 samples the harmonic extraction signal Shv input to the analog port as a specific state quantity at the interconnection point at a constant cycle (for example, 10 ms), and in parallel with it. Then, the average value of the sampling values for a plurality of times (for example, five times) is obtained, and the average value is used as the measured value V
Take in as hv. That is, 50 (= 10 × 5) ms
The third harmonic component is measured in the cycle of (# 11).
【0025】測定値Vhvを取り込む毎に、第3次高調
波成分の急増の有無の判定(差分判定)を行う(#1
2)。ここでの差分判定は、単位時間当たりの変化量Δ
Vhvとして、新たに取り込んだ測定値Vhvと差分基
準値Vbaseとの差を求め、変化量ΔVhvが所定の
第1閾値Vth1を越えるか否かを調べる処理である。
閾値Vth1としては、例えば商用電力系統2の基準電
圧が101V(実効値)の場合、連系点での電圧レベル
に換算して0.7〜1V程度の値が選定される。Every time the measured value Vhv is fetched, it is judged whether there is a sudden increase in the third harmonic component (difference judgment) (# 1).
2). The difference determination here is the change amount Δ per unit time.
As Vhv, the difference between the newly taken measured value Vhv and the difference reference value Vbase is obtained, and it is a process of checking whether or not the variation ΔVhv exceeds a predetermined first threshold value Vth1.
As the threshold value Vth1, for example, when the reference voltage of the commercial power system 2 is 101V (effective value), a value of about 0.7 to 1V is selected in conversion to the voltage level at the interconnection point.
【0026】変化量ΔVhvが第1閾値Vth1を越え
た場合には、まず、能動的単独運転検出を確実且つ迅速
なものにするため、真の単独運転のときに連系点電圧V
oが顕著に変動するように、電圧指令値Vrefの変動
幅として平常時に比べて十分に大きい値を設定する(#
13)。例えば、その時点の出力有効電力を20〜30
%程度の範囲で変動させるようにする。When the amount of change ΔVhv exceeds the first threshold value Vth1, first, in order to make active islanding detection reliable and quick, first, in order to ensure active islanding, the interconnection point voltage V is set during true islanding.
A value that is sufficiently larger than that in normal times is set as the fluctuation range of the voltage command value Vref so that o significantly changes (#
13). For example, the output active power at that time is 20 to 30
Change within the range of about%.
【0027】次に、連系解除をする必要のない瞬間的な
系統停電と他とを区別するための時限カウンタを更新
し、一定時間Tの計時を進める(#14)。この一定時
間Tは、例えば0.2〜0.3sであって、第3高調波
成分の測定周期である50msより十分に長く、且つ商
用電力系統2の運用で規定されている受動的停電検出の
反応時間(例えば0.5s)より短い時間である。Next, the time counter for distinguishing the momentary system power failure which does not need to be disconnected from the others is updated, and the fixed time T is counted (# 14). The fixed time T is, for example, 0.2 to 0.3 s, which is sufficiently longer than the measurement cycle of the third harmonic component of 50 ms, and is a passive power failure detection defined in the operation of the commercial power system 2. The reaction time is shorter than the reaction time (for example, 0.5 s).
【0028】時限カウンタを更新した後、一定時間Tの
計時中であれば、単独運転検出処理のメインルーチンへ
リターンする(#15)。これにより、結果的に第3次
高調波成分の測定及び差分判定が繰り返し実行される。
その際、変化量ΔVhvが後述の第2閾値Vth2以下
とならない限り、最初に第3次高調波成分の急増を検出
した時点の差分基準値Vbaseがそのまま用いられ
る。After updating the time limit counter, if the fixed time T is being measured, the process returns to the main routine of the isolated operation detection process (# 15). As a result, the measurement of the third harmonic component and the difference determination are consequently repeatedly executed.
At that time, unless the change amount ΔVhv becomes equal to or less than a second threshold value Vth2 described later, the difference reference value Vbase at the time when the sudden increase of the third harmonic component is first detected is used as it is.
【0029】時限カウンタによる計時が終了した場合
は、急増後の第3高調波成分の高レベル状態が一定時間
T以上にわたって持続した場合である。この場合に、マ
イクロコンピュータ24は、単独運転状態であると判断
し、直ちに運転停止処理を実行する(#15、16)。
運転停止処理では、ゲート回路226及び遮断器CBを
オフ状態とする制御信号Sf1,Sf2を出力し、イン
バータ主回路21の各スイッチング素子のゲートブロッ
クを行うとともに、インバータ20を商用電力系統2か
ら切り離す。この2重の安全策によりインバータ20の
単独運転が防止される。When the time counting by the time limit counter ends, the high level state of the third harmonic component after the rapid increase has continued for a certain period of time T or more. In this case, the microcomputer 24 determines that it is in the isolated operation state, and immediately executes the operation stop processing (# 15, 16).
In the operation stop processing, the control signals Sf1 and Sf2 for turning off the gate circuit 226 and the circuit breaker CB are output, the switching elements of the inverter main circuit 21 are gated blocked, and the inverter 20 is disconnected from the commercial power system 2. . This double safety measure prevents the inverter 20 from operating alone.
【0030】一方、上述のステップ12において変化量
ΔVhvが第1閾値Vth1を越えない場合には、続い
て変化量ΔVhvが第2閾値Vth2を越えるか否かを
チェックする(#17)。第2閾値Vth2は、第1閾
値Vth1より小さい値であり(Vth2<Vth
1)、明らかに並列運転中である平常状態と単独運転の
可能性がある非平常状態とを識別するための疑似単独運
転基準値として設定されている。On the other hand, if the amount of change ΔVhv does not exceed the first threshold value Vth1 in step 12 above, then it is checked whether or not the amount of change ΔVhv exceeds the second threshold value Vth2 (# 17). The second threshold value Vth2 is smaller than the first threshold value Vth1 (Vth2 <Vth
1), it is set as a pseudo independent operation reference value for distinguishing a normal state in which parallel operation is apparently performed and a non-normal state in which there is a possibility of independent operation.
【0031】変化量ΔVhvが第2閾値Vth2を越え
る場合は、ステップ#13と同様に電圧指令値Vref
の変動幅として平常時に比べて大きい値を設定してリタ
ーンする(#18)。つまり、この場合も、出力有効電
力を大きく変動させて能動的単独運転検出を強化する。When the change amount ΔVhv exceeds the second threshold value Vth2, the voltage command value Vref is obtained as in step # 13.
A larger value is set as the fluctuation range of the value than in normal times, and the process returns (# 18). That is, also in this case, the output active power is largely changed to enhance the active islanding detection.
【0032】これに対して、変化量ΔVhvが第2閾値
Vth2を越えない平常状態の場合には、出力有効電力
の積極的な変動を抑えて太陽電池10の発電能力の利用
率を高めるため、電圧指令値Vrefの変動幅として非
平常時に比べて小さい値を設定する(#19)。ここ
で、原理的には電圧指令値Vrefの変動幅を零として
もよい。ただし、安全の上で能動的検出処理で検出可能
な最低限の連系点状態変動が生じるように、電圧指令値
Vrefの変動幅を設定するのが望ましい。On the other hand, when the variation ΔVhv does not exceed the second threshold value Vth2 in a normal state, the active fluctuation of the output active power is suppressed and the utilization rate of the power generation capacity of the solar cell 10 is increased. As the fluctuation range of the voltage command value Vref, a value smaller than that in the non-normal state is set (# 19). Here, in principle, the fluctuation range of the voltage command value Vref may be zero. However, it is desirable to set the fluctuation range of the voltage command value Vref so that the minimum fluctuation of the interconnection point state that can be detected by the active detection process occurs for safety.
【0033】その後、次回の差分判定に備えて差分基準
値Vbaseの更新を行い、上述の時限カウンタを初期
化する(#20、21)。差分基準値Vbaseの更新
処理においては、今回の判定対象の測定値Vhvをその
まま差分基準値Vbaseとして設定するのではなく、
次回の差分基準値Vbaseとして、測定値Vhvと現
時点の差分基準値Vbaseとの荷重平均値を設定す
る。その際、現時点の差分基準値Vbaseの重み付け
を測定値Vhvよりも大きい値(例えば数倍程度)とす
ることにより、差分基準値Vbaseがノイズの無い理
想状態における第3高調波成分の値に近い値となり、次
回の検出で得られた測定値Vhvに対して適正な差分判
定を行うことができる。Thereafter, the difference reference value Vbase is updated in preparation for the next difference determination, and the time counter is initialized (# 20, 21). In the update process of the difference reference value Vbase, the measured value Vhv to be determined this time is not set as it is as the difference reference value Vbase, but
As the next difference reference value Vbase, the weighted average value of the measured value Vhv and the current difference reference value Vbase is set. At that time, the difference reference value Vbase is close to the value of the third harmonic component in an ideal state without noise by setting the weighting of the difference reference value Vbase at the present time to a value (for example, about several times) larger than the measured value Vhv. The value becomes the value, and an appropriate difference determination can be performed for the measured value Vhv obtained in the next detection.
【0034】以上の説明から明らかなように、本実施例
の太陽光発電システム1では、第3高調波成分の高レベ
ル状態が一時的であるか否かを判別するための一定時間
Tの計時中を含めて、変化量ΔVhvが第2閾値Vth
2を越える期間が非平常期間とされ、それ以外の平常期
間は出力有効電力の変動(つまり太陽電池10の動作点
の変動)が抑えられる。As is clear from the above description, in the solar power generation system 1 of this embodiment, the fixed time T for determining whether or not the high level state of the third harmonic component is temporary is measured. Including the inside, the change amount ΔVhv is the second threshold value Vth.
The period exceeding 2 is regarded as the non-normal period, and the fluctuation of the output active power (that is, the fluctuation of the operating point of the solar cell 10) is suppressed during the other normal periods.
【0035】上述の実施例によれば、一定時間Tにわた
って第3高調波成分の高レベル状態が持続したときに、
運転停止制御を行うようにしたので、瞬間的な第3高調
波成分の急増に呼応した無用の運転停止を避けることが
でき、太陽電池10の発電電力の損失を最小限に抑える
ことができる。According to the above-described embodiment, when the high level state of the third harmonic component continues for a certain time T,
Since the operation stop control is performed, it is possible to avoid an unnecessary operation stop in response to a sudden increase in the third harmonic component, and it is possible to minimize the loss of power generated by the solar cell 10.
【0036】上述の実施例において、連系点電圧Voの
特定周波数の変動を検出するための周波数解析などの機
能を、ディジタル信号プロセッサ(DSP)を用いて実
現してもよい。また、出力有効電力を変動させるための
回路構成、インバータ20の構成、及び単独運転検出処
理の内容については、種々の変更が可能である。In the above-mentioned embodiment, a function such as a frequency analysis for detecting a change in the specific frequency of the interconnection point voltage Vo may be realized by using a digital signal processor (DSP). Further, various changes can be made to the circuit configuration for changing the output active power, the configuration of the inverter 20, and the content of the islanding operation detection process.
【0037】上述の実施例において、第3高調波成分の
絶対値と基準値との比較による判定を、差分判定に代え
て又は併用する形で行うことによって、平常と非平常と
を区別してもよい。In the above-described embodiment, the judgment by comparing the absolute value of the third harmonic component with the reference value is performed instead of or in combination with the difference judgment, thereby distinguishing between normal and non-normal. Good.
【0038】上述の実施例においては、第3高調波成分
の急増の有無によって単独運転を検出する例を示した
が、連系点電圧の位相や周波数などを検出する他の受動
的単独運転検出手法を採用した場合にも、本発明を適用
することができる。また、燃料電池などの太陽電池以外
の直流電源を備えた分散電源設備の単独運転検出にも適
用することができる。In the above-mentioned embodiment, the example of detecting the islanding operation by the presence or absence of the rapid increase of the third harmonic component is shown. However, other passive islanding detection for detecting the phase or frequency of the interconnection point voltage is shown. The present invention can be applied even when the method is adopted. It can also be applied to islanding operation detection of distributed power equipment equipped with DC power supplies other than solar cells such as fuel cells.
【0039】[0039]
【発明の効果】本発明によれば、能動的単独運転検出の
信頼性を確保しつつ、平常時におけるインバータ出力の
変動幅の低減を図り、直流発電能力の利用率を高めるこ
とができる。According to the present invention, it is possible to reduce the fluctuation range of the inverter output during normal times and increase the utilization rate of the DC power generation capacity while ensuring the reliability of active islanding detection.
【図1】本発明を適用した太陽光発電システムの回路構
成を示すブロック図である。FIG. 1 is a block diagram showing a circuit configuration of a photovoltaic power generation system to which the present invention has been applied.
【図2】PWM制御部の構成を機能的に示すブロック図
である。FIG. 2 is a block diagram functionally showing a configuration of a PWM control unit.
【図3】3次高調波抽出部の構成を示すブロック図であ
る。FIG. 3 is a block diagram showing a configuration of a third harmonic extraction unit.
【図4】単独運転検出処理のフローチャートである。FIG. 4 is a flowchart of islanding operation detection processing.
【図5】受動的検出処理のフローチャートである。FIG. 5 is a flowchart of a passive detection process.
【図6】単独運転検出処理の内容を示す模式図である。FIG. 6 is a schematic diagram showing the content of islanding detection processing.
2 商用電力系統 20 インバータ ΔVhv 第3次高調波成分の変化量(特定状態量) Vth2 第2閾値(疑似単独運転基準値) w 出力電力の変動幅 2 Commercial power system 20 Inverter ΔVhv Change amount of third harmonic component (specific state amount) Vth2 Second threshold value (pseudo-isolation operation reference value) w Output power fluctuation range
Claims (2)
ておき、それにより単独運転時に現れる一定周期の連系
点状態変動を検出する能動的単独運転検出と、単独運転
への移行時に現れる連系点の特定状態量の変化を検出す
る受動的単独運転検出とを、並列的に行う単独運転検出
方法であって、 前記特定状態量が予め設定した疑似単独運転基準値を越
えるときには、前記特定状態量が前記疑似単独運転基準
値を越えないときに比べて、前記出力電力の変動幅を大
きくすることを特徴とする単独運転検出方法。Claim: What is claimed is: 1. An output power of an inverter is fluctuated periodically, whereby active islanding detection is performed to detect a fixed cycle variation in the interconnection point that appears during islanding. A passive islanding detection for detecting a change in a specific state quantity of a system point, which is an islanding detection method performed in parallel, wherein when the specific state quantity exceeds a preset pseudo islanding reference value, A method for detecting an isolated operation, characterized in that the fluctuation range of the output power is made larger than when the state quantity does not exceed the pseudo independent operation reference value.
ておき、それにより単独運転時に現れる一定周期の連系
点状態変動を検出する能動的単独運転検出と、単独運転
への移行時に現れる連系点電圧の第3次高調波成分の急
増を検出する受動的単独運転検出とを、並列的に行う単
独運転検出方法であって、 前記第3次高調波成分の変化量が予め設定した疑似単独
運転基準値を越えるときには、前記変化量が前記疑似単
独運転基準値を越えないときに比べて、前記出力電力の
変動幅を大きくすることを特徴とする単独運転検出方
法。2. An active isolated operation detection for periodically changing the output power of the inverter, thereby detecting a change in the interconnection point state with a constant cycle that appears during isolated operation, and a connection that appears when shifting to the isolated operation. What is claimed is: 1. An isolated operation detection method for performing a passive isolated operation detection for detecting a sudden increase in the third harmonic component of a system point voltage in parallel, wherein the variation amount of the third harmonic component is preset A method of detecting an isolated operation, wherein when the value exceeds the isolated operation reference value, the fluctuation range of the output power is made larger than when the change amount does not exceed the pseudo isolated operation reference value.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP6110657A JPH07322506A (en) | 1994-05-25 | 1994-05-25 | Detection operation of single operation |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP6110657A JPH07322506A (en) | 1994-05-25 | 1994-05-25 | Detection operation of single operation |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH07322506A true JPH07322506A (en) | 1995-12-08 |
Family
ID=14541202
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP6110657A Pending JPH07322506A (en) | 1994-05-25 | 1994-05-25 | Detection operation of single operation |
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Country | Link |
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JP (1) | JPH07322506A (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009044910A (en) * | 2007-08-10 | 2009-02-26 | Omron Corp | Method for detecting isolated operation, contrl device, device for detecting isolated operation, and distributed power supply system |
JP2010142081A (en) * | 2008-12-15 | 2010-06-24 | Omron Corp | Method and device for detection of individual operation, and program |
JP2014212631A (en) * | 2013-04-18 | 2014-11-13 | シャープ株式会社 | Inverter device |
JP2015220835A (en) * | 2014-05-16 | 2015-12-07 | シャープ株式会社 | Electric power conversion system |
JP2016086574A (en) * | 2014-10-28 | 2016-05-19 | 三菱電機株式会社 | Control apparatus for single operation detection, and single operation detection device |
-
1994
- 1994-05-25 JP JP6110657A patent/JPH07322506A/en active Pending
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009044910A (en) * | 2007-08-10 | 2009-02-26 | Omron Corp | Method for detecting isolated operation, contrl device, device for detecting isolated operation, and distributed power supply system |
JP2010142081A (en) * | 2008-12-15 | 2010-06-24 | Omron Corp | Method and device for detection of individual operation, and program |
JP2014212631A (en) * | 2013-04-18 | 2014-11-13 | シャープ株式会社 | Inverter device |
JP2015220835A (en) * | 2014-05-16 | 2015-12-07 | シャープ株式会社 | Electric power conversion system |
JP2016086574A (en) * | 2014-10-28 | 2016-05-19 | 三菱電機株式会社 | Control apparatus for single operation detection, and single operation detection device |
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