PH12014000071B1 - Independent operation detection apparatus and independent operation detection method - Google Patents
Independent operation detection apparatus and independent operation detection method Download PDFInfo
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- PH12014000071B1 PH12014000071B1 PH12014000071A PH12014000071A PH12014000071B1 PH 12014000071 B1 PH12014000071 B1 PH 12014000071B1 PH 12014000071 A PH12014000071 A PH 12014000071A PH 12014000071 A PH12014000071 A PH 12014000071A PH 12014000071 B1 PH12014000071 B1 PH 12014000071B1
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- 238000002347 injection Methods 0.000 claims abstract description 14
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- 238000005303 weighing Methods 0.000 claims 1
- 238000000034 method Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000010276 construction Methods 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
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Abstract
An independent operation detection apparatus that detects an independent operation, includes: a reactive power injection unit; a power change period detection unit; a power change period storage unit; an average power change period calculation unit; a power change period prediction unit that predicts the next power change period; a deviation calculation unit that calculates a deviation; and an active independent operation determination unit that determines whether the dispersed power source is the independent operation or not.
Description
/ ] oo . & ~ Ce
INDEPENDENT OPERATION DETECTION AppaRATvg 0 h—— or | o
OPERATION DETECTTON METHOD <2 £ co - “ey, TL 21 Sa
BACKGROUND N
3 : I REGED Lo " 1. Technical Field | . CG
The present invention relatef to an independent = operation detection apparatus that detects an independent - operation of a dispersed power source which is operated by | = being interconnected with a commercial power source system = and an independent operation detection method. - 2. Description of Related Art I
In recent years, a power source apparatus that ov supplies power of a dispersed power source such as a solar o cell and a fuel cell to an AC load by being interconnected ~ with a commercial power source system has been used. In order © to efficiently supply power of the dispersed power source Ge and power of the commercial power SOULTe system to the AC xs) load, a power conditioner is connected between the dispersed w power source and the commercial power source system. o
The power conditioner is an apparatus for oy converting power which 1s generated so as to be capable of - . being used as commercial power when utilizing the solar cell z or the fuelcell. The power conditioner supplies surplus power to the commercial power source system if power which is generated is greater than required power of the AC load, and, in contrast, receives, a power shortage from the commercial power source systemif powerwhichisgeneratedinthedispersed - power source is lesser than required power of the AC load. 30° The power conditioner compensates only power which is consumed anddoes not supply power tothe commercial power source system. . Since the power conditioner is connected to the _ B commercial power source system and capable of supplying power = which is generated in the dispersed power source to the - commercial power source system, power 1s supplied from the — side of thedispersedpower source tothe side of the commercial - power source system, if the power conditioner does not rapidly detect power failure when the power failure occurs in the : commercial power source system due to accident or a construction. a ’ Thus, the power conditioner has an independent | o operation detection apparatus for detecting that the e dispersed power source is operated independently when the power failure occurs in the commercial power source system. | on
For example, the independent operation detection apparatus ” of the related art is disclosed in the following Japanese O
Patent No. 4073387. : : : ~ ! | The independent operation detection apparatus @ disclosed in Japanese Patent No. 4073387 includes two be functions of an active detection function and a passive a) detection function. For example, the active detection ou function is a function for externally applying a disturbance o : factor such as frequency, reactive power fluctuationor active Re power fluctuation to AC power which is currently output, and . o for detecting an independent operation, based on the disturbance factor which is externally applied. The passive detection function is a function for detecting the independent operation, based on various elements of AC power which is “currently output, for example, elements such as an output current or a system voltage.
The independent operation detection apparatus : 30 disclosed in Japanese Patent No. 4073387 determines that the dispersed power source is the independent operation if the independent operation is detected in at least any one of the : - 2 — oo active detection function and the passive detection function. o
In the independent operation detection apparatus =O of the above related art, the independent operation of the = dispersed power source is determined by whether or not the RS frequency fluctuation of AC power which is currently output fos exceeds a reference value. However, it is necessary todetect = the independent operation as accurately as possible and also = as rapidly as possible. However, even in the independent . operation detection apparatus of the above related art, there . | o is still room for improvement at these points. iy
SUMMARY o
An object of the invention is to provide an : = - 15 independent operation detection apparatus that can detect N an independent operation further accurately and rapidly, and ® an independent operation detection method. Cs
An independent operation detection apparatus for = achieving the object of the invention is an independent - operation detection apparatus that detects an independent . operation of a dispersed power source which is operated by i being interconnected with a commercial power source system o and includes: a reactive power injection unit; a power change . - period detection unit, a power change period storage unit; an average power change period calculationunit; a power change period prediction unit; a deviation calculation unit; and an active independent operation determination unit. oo The reactive power injection unit injects reactive power. into the commercial power source system. The power change period detection unit detects the power change periods : © ofthecommercial power sourcesystem. Thepowerchangeperiod. : storage unit stores the power change periods which are detected.
s
The average power change period calculation unit calculates on an average of the power change periods of previous m times. .
The power change period prediction unit predicts the next . py power change period from the power change periods of previous 5 n times. The deviation calculation unit calculates the a deviation of the average of the power change periods which - arepredicted andthe power change periodswhichare calculated. -
The active independent operation determination unit Ca determines that the dispersed power source is the independent i operation if the deviation exceeds the threshold by comparing o the deviationwhich is calculated toapredetermined threshold ow in advance, and determines that the dispersed power source = . is not the independent operation if the deviation does not > exceed the threshold. .
In addition, an independent operation detection ol method for achieving the object of the invention is an = independent operation detection method for detecting an ie independent operation of a dispersed power source which is @ operated by being interconnected with a commercial power source system, which includes: injecting reactive power; _ + detecting power change periods; storing the power change oy periods; calculating an average power change period; o predicting the power change periods; calculating adeviation; - and determining an active independent operation. oT In the step of injecting the reactive power, the reactive power is injected into the commercial power source system. In the step of detecting the power change period, - the power change periods of the commercial power source system are detected. Tn the step of storing the power change periods, the power change periods which are detected are stored. In the step of calculating the average power change period, an average of the power change periods of previous m times is _—
calculated. Inthestepotpredictingthepowerchangeperiod,. N the next power change period is predicted fromthe power change " periods of previous n times. In the step of calculating the = deviation, the deviation of the average of the power change Ra periods which are predicted and the power change periods which po are calculated is calculated. In the step of determining the active independent operation, it is determined that the ~ dispersed power source is the independent operation if the ~ deviation exceeds the threshold by comparing the deviation - which is calculated to a predetermined threshold in advance, o and it is determined that the dispersed POET source is not the independent operation if the deviation does not exceed - the threshold. | a
According to the independent operation detection - apparatus and the independent operation detection method of the invention having the above configuration, it is possible - to detect the independent operation of the dispersed power source further accurately and rapidly by predicting the next x power change period from the previous power change periods and by determining the independent operation of the dispersed - power source using the power change periods which are predicted. | : | » : : ww . . . : : Joa
| oo
FIG. 1 is a block diagram of a power conditioner including an independent operation detection apparatus according to the invention.
FIG. 2 is a block diagram of the independent operation detection apparatus of FIG. 1. :
FIG. 3 is an operation flowchart of a reactive power “injection unit, a power change period detection unit and a power change period storage unit illustrated in FIG. 2. bo
FIG. 4 1s an operation flowchart of an average power = change period calculation unit, ‘a power change period o prediction unit, a deviation calculation unit, a deviation - storage unit and an active independent operation ) determination unit illustrated in FIG. 2. o
FIG. 5 is a subroutine flowchart of a positive pattern - detection processing of FIG. 4. =
FIG. 6 is a subroutine flowchart of a negative pattern Gl detection processing of FIG. 4. . =
FIG. 7 is an operation flowchart of an average power = : change period calculation section, a power change period - prediction unit, a frequency change rate calculation unit > and a passive independent operation determination unit of -
FIG. 2. | | oo -
FIG. 8 is a view for describing an operation of an active = detection function of the independent operation detection o apparatus of FIG. 1. iT
FIG. 9 is a view illustrating thresholds of a positive iw pattern and a negative pattern stored in a threshold storage . unit of FIG. 1. oo | CL
FIG. 10 is aview for describing an operation of a passive o detection function of the independent operation detection w apparatus of FIG. 1.
Next, an independent operationdetection apparatus and an independent operation detection method according to theinventionwillbedescribedwithreferencetothedrawings. [Configuration of Power Conditioner]
FIG. 1 is a block diagram of a power conditioner :
ot - | v including the independent operation detection apparatus da according to the invention. The independent operation N detection apparatus detects independent operation of a | = dispersed power source which is operated by being a interconnected with a commercial power source system. pe
A power conditioner 10 is connected to a dispersed = power source 20 and a commercial power source system 30. The = dispersed power source 20 is, for example, a DC power source _ capable of supplying DC power such as a solar cell panel and or a fuel cell. The commercial power source system 30 is a o. commercial power source of 50 Hz or 60 Hz connected to a power . . plant. The power conditioner 10 has two functions of an - independent operation function for supplying DC power to a load (not illustrated) by converting DC power from the rr dispersed power source 20 to AC power and an interconnecting - operation function for supplying surplus power of the load - : to the commercial power source system by converting DC power - fromthe dispersed power source 20 to AC power and for supplying Ir
DC power to the load by converting DC power from the dispersed “ power source 20 to AC power, and for supplying a power shortage - in the load from the commercial power source system. | @
To In order to exert the independent operation | « function and the interconnecting operation function, the | - power conditioner 10 has a DC/DC converter 12 for boosting an output voltage of the dispersed power source 20 and a DC/AC inverter 14 for converting the boosted voltage toanACvoltage. ~The DC/AC inverter 14 is connected to the commercial power source system 30 through an interconnecting relay 16.
The power conditioner 10 performs the independent operation depending on a power generation condition of the dispersed power source 20 or performs the independent operation depending on a power transmission condition of the ro commercial power source system 30. The power conditioner 10 - has an independent operation detection apparatus 100 and o rapidly recognizes the interconnecting operation and the = independent operation, and cuts off the interconnecting relay - 16 if the independent operation is detected. For example, o whenpower failure occurs due to construction in the commercial - power source system 30, the independent operation detection = apparatus 100 rapidly detects the power failure, the = oo ‘independent operation detection apparatus 100 cuts off the or interconnecting relay 16 and blocks connection between the ™
DC/AC inverter 14 and the commercial power source system 30 so that the power is not supplied from the dispersed power = source 20 to the commercial power source system 30. v ~ [Configuration of Independent Operation DetectionApparatus] =
FIG. 2 is a block diagram of the independent ~ operation detection apparatus of FIG. 1. The independent = operation detection apparatus 100 has a reactive power o injection unit 110, a power change period detection unit 120, Cm : a power:change period storage unit 125, an average power change v periodcalculationunit 130, a power change period prediction o unit 140, adeviationcalculationunit 150, a threshold storage oy unit 155, a deviation storage unit 160, an active independent o - operation determination unit 165, a frequency change rate - calculation unit 170 and a passive independent operation determination unit 180.
In order to rapidly detect the power failure of the commercial power source system 30, the reactive power injection unit 110 injects the reactive power into the + commercial power source system 30. The injection of the oo reactive power uses a technique which is typically performed.
The power change period detection unit 120 detects . bothperiodsof arisingperiodof the voltage of the commercial — 8g —
bo ; power source system 30 and a falling period of the voltage I thereof, individually, and detects a power change period of " the commercial power source system30. Inthisspecification, = the power change period 1s detected by the voltage change Fe of the commercial power source system 30. In a case of a be three-phase AC current, the power change periodmaybe detected “ by voltage change of a one-phase andmay be detected by voltage “ change of a two-phase in the three-phase. ~
The power change period storage unit 125 stores - the power change period which is detected in the power change 0 period detection unit 120. The rising period of the voltage of the commercial power source system 30 and the falling period - of the voltage thereof in the power change period are stored > in chronological order, respectively. -
The average power change period calculation unit ” 130 takes out m power change periods stored in the power change = period storage unit 125 in chronological order and calculates i. an average of power change periods of previous m times. oT
Detailed operation of the average power change period - © 20 calculation unit 130 will be described below. | -
The power change period prediction unit 140 takes - : out n power change periods stored in the power change period : v storage unit 125 in chronological order and the power change w period of a specific time in the power change periods of oo previous n times is weighed, and the next power change period is predicted by calculating an average of the power change = periods of n times after being weighed. Detailed operation of thepower changeperiodpredictionunit 140willbe described below. : : The deviation calculation unit 150 calculates a deviation of an average of the power change periods predicted in the power change period prediction unit 140 and an average
Ful of the power change periods calculated in the average power change period calculation unit 130. Detailed operation of 0 the deviation calculation unit 150 will be described below. ar
The threshold storage unit 155 stores a plurality . of thresholds corresponding to a plurality of deviations or calculated in the deviation calculation unit 150, wh respectively. AsillustratedinFIG. 9, thethresholdstorage = unit 155 stores the plurality of thresholds corresponding - tothepluralityofdeviationsby separating into the threshold = : 10 of a positive pattern which is used when the deviation . calculated in the deviation calculation unit 150 is positive and the threshold of a negative pattern which is used when thedeviationisnegative, separately. Sizesoftheplurality x of thresholds corresponding to the plurality of deviations, - individually, are different individually and absolute values : of the sizes of the plurality of thresholds corresponding - to the plurality of deviations, respectively, are small as o the threshold corresponding to the previous deviation. =
Furthermore, the threshold storage unit 155 stores the > - threshold (frequency change rate and times) for comparing - the frequency change rates calculated in the frequency change I rate calculationunit 170 in the passive independent operation determination unit 180. | | ow
The deviation storage unit 160 stores the plurality of deviations calculated in the deviation calculation unit 150 in chronological order.
The active independent operation determination unit 165 determines that the dispersed power source 20 is the independent operation if the deviation thereof exceeds the threshold by comparing the deviation calculated in the deviation calculation unit 150 to a predetermined threshold in advance stored in the threshold storage unit 155, and p, determines that the dispersed power source 20 is not the . independent operation if thedeviation thereof doesnot exceed te the threshold. Further, the active independent operation ho determination unit 165 determines that the dispersed power od 5. source 20 is the independent operation if all of a plurality = of deviations exceed a plurality of thresholds corresponding - thereto, respectively, by comparing the plurality of - deviations stored in the deviation storage unit 160 in & chronological order of the plurality of thresholds 2 - 10 corresponding to the plurality of deviations stored in the o threshold storage unit 155, respectively, and determines that 1 the dispersed power source 20 is not the independent operation if even one of the plurality of deviations does not exceed @ the threshold corresponding to the deviation thereof. ~
Further, the active independent operation determination unit = 165 determines right and wrong of the independent operation = of the dispersed power source 20 using the threshold of the i. positive pattern stored in the threshold storage unit 155 oo when the deviation calculated in the deviation calculation unit 150 is positive, and determines right and wrong of the - independent operation of the dispersed power source 20 using oo the threshold of the negative pattern stored in the threshold ow . storageunit 155when thedeviation calculated inthe deviation = calculation unit 150 is negative.
The frequency change rate calculation unit 170 : calculates the frequency change rate from the average of the power change period calculated in the average power change period calculation unit 130 and the next power change period predicted in the power change period prediction unit 140.
Moreover, the frequency change rate calculation unit 170 calculates the frequency change rate with respect to each of power change periods using the power change periodpredicted
C— 11 —
in the power change period prediction unit 140. y
The passive independent operation determination = unit 180 determines that the dispersed power source 20 is o the independent operation if the frequency change rate - calculatedwhenever the next power change period is calculated which is predicted in the power change period prediction unit o 140 continuously exceeds the threshold stored inthe threshold co storage unit 155 in the plurality of times and if directions - ® of the plurality of times of frequency changes are the same : = © 10 as each other, and determines that the dispersed power source - 20 1s not the independent operation if the frequency change or rate calculated whenever the next power change period is = calculated does not continuously exceed the threshold in the v plurality of times or if the directions of the plurality times oo of frequency changes are not the same as each other. Further, - the passive independent operation determination unit 180 & determines right and wrong of the independent operation of 0 the dispersed power source 20 using the frequency change rates I calculated, individually, with respect to the power change v ~~ 20 periods predicted in the power change period prediction unit - 140. | - [Operation of Independent Operation Detection Apparatus]
To . Above 1s the schematic configuration of the = independent operation detection apparatus 100. Next, the operation of the independent operation detection apparatus © 100 will be described with reference to FIGS. 3 to 8. The operation of the independent operation detection apparatus : 100 described below is the same as a procedure of an independent operation detection method according to the invention. : 30 < Active Detection Function >
FIG. 3 is an operation flowchart of the reactive power injection unit 110, the power change period detection
. ce = unit 120 and the power change period storage unit 125. .
The reactive power injection unit 110 injects the = reactive power toward the commercial power source system 30 (step S100). The injection of the reactive power is performed N as the following procedure. First, a difference between a moving average of the power change periods, for example, | - between 80 msec before 200 msec and a moving average of the : - power change periods from present time to 40 msec detected & in the power change period detection unit 120 is obtained. 0
Next, an injection amount of the reactive power is calculated o ~ depending on the size of the frequency deviation and the i : injection amount of the calculated reactive power is injected = toward the commercial power source system 30 while changing ” oo a current phase so as tomaintain a constant effective power. o
The power change period detection unit 120 detects ~ power change periods Ta and Tb of the commercial power source = system 30 (step S110). As illustrated in FIG. 8, the power Ci changeperioddetectionunit 120detectsaperiod fromavoltage £ rising from zero cross of the commercial power source system ~ 30 to the voltage rising from the next zero cross as the power " change period of a Ta system. Then, the power change period or! detection unit 120 detects a period from a voltage falling o . from zero cross of the commercial power source system 30 to N the voltage falling from the next zero cross as the power change period of a Tb system. That is, the power change period detection unit 120 detects the power change period of the : Ta system and the power change period of the Tb system, : individually. : :
The power change period storage unit 125 stores theperiodsof the Tasystemandthe Tbsystemwhicharedetected (step S120). The power change period storage unit 125 stores the power change period of the Ta system and the power change bud o period of the Tb system which are detected in the power change period detection unit 120, in chronological order, . individually. Ce
FIG. 4 is an operation flowchart of the average = power change period calculation unit 130, the power change on period prediction unit 140, the deviation calculation unit - 150, the deviation storage unit 160 and the active independent & operation determination unit 165. x :
The average power change period calculation unit - 130 calculates an average period of m power change periods Ge until a certain time (step $200). In the embodiment, m is seven. The average power change period calculation unit 130 _ takes out the power change periods of the Ta system and the = power change periods of the Tb system which are stored in - the power change period storage unit 125, separately. ”
Specifically, as illustrated in FIG. 8, for the Ta system, ft data of power change periods of seven times before 200 msec i. (corresponding to the power change periods of ten times at = 50 Hz) from present time, that is, seven power change periods “ of Ta(N-10), Ta(N-11), .., Ta(N-15) and Ta(N-16) are taken " out. At the same time, for the Tb system, seven power change periods of Tb (N-10), Tb(N-11), .., Tb(N-15) and Tb (N-16) are wo taken out. = ’ Next, the average power change period calculation oo unit 130 calculates an average Taave of the power change periods : oo of the Ta system by calculating [Ta(N-10)+Ta (N-11)+..+Ta (N-15)+Ta(N-16)]/7 for the Ta system.
At the same time, the average power change period calculation unit 130 calculates anaverage Thave of the power change periods of the Tb system by calculating [Tb (N-10)+Tb (N-11)+.+Tb(N-15)+Tb(N-16) 1/7 for the Tb system.
Moreover, in the above example, the average of the power change fo periods isobtainedusingall of the seven power change periods, o but in order to improve reliability, the average of the power = change periods may be calculated using the remaining five EN power change periods except two of the maximum and the minimum o power change periods out of the seven. | *
The power change period prediction unit 140 - calculates a predicted period from n power change periods - before the present time (step S210). In the embodiment, n & is five. The power change period prediction unit 140 takes 3 out the power change periods of the Ta system and the power o change periods of the Tb system which are stored in the power LO "change period storage unit 125, separately. Specifically, ~ as illustrated in FIG. 8, for the Ta system, data of power o
CL change periods of five times from the present time, that is, - five power change periods of Ta(N), Ta(N-1), Ta(N-2), Ta (N-3) i = and Ta (N-4) are takenout. At the sametime, for the Tb system, - five power change periods of Tb (N), Tb (N-1), Tb (N-2), Tb (N-3) - and Tb (N-4) are taken out. ey - Next, the power change period prediction unit 140 calculates the predicted period of the power change by the following calculation. Specifically, the predicted period a
Ta (N+1) of the Ta system is calculated by computing the predicted period | =
Ta (N+1)=Ta (N)+[{Ta (N)-Ta(N-1) }+2x{Ta (N-1)-Ta (N-2) }+2x{Ta (N-2)-Ta(N-3) }+{Ta (N-3)-Ta (N-4) } 1/6.
Bh The predicted period Th (N+1) of the Tb system is - calculated by computing the predicted period
Tb (N+1)=Tb(N) + [{Tb (N) -Tb (N-1) }+2x{Tb (N-1) -Tb (N-2) } +2x{Tb (N-2)~Tb (N-3) } +{Tb (N-3) Tb (N-4) }1/6. oo
The above computation is performed with reference to a quartic equation of Runge-Kutta and is weighed to a specific power change period, and predicts the future power y change period from the previous power change period by a Co differential equation. + ) The deviation calculation unit 150 calculates the deviation between the average period and the predicted period - (step $220). | | oo | *
Specifically, for the Ta system, since the average - of the power change periods is Taave and the predicted period - ‘is Ta(N+1l), adeviationdiffTa(N) is calculated by computing, & diffTa (N)=Taave-Ta (N+1). a
Furthermore, for the Tb system, since the average o of the power change periods is Tbhave and the predicted period = is Th (N+1), a deviation diffTb(N) is calculated by computing, BN dif£Tb (N) =Tbave-Tb (N+1) . >
ThedeviationdiffTa(N) andthedeviationdiffTb (N) - have positive or negative values.
The deviation calculation unit 150 stores the o : deviation diffTa(N) and the deviation diffTb(N) obtained in - step S220 in the deviation storage unit 160 in chronological = order (step.S230). : iw | “The deviation calculation unit 150 determines o whether the deviation diffTa(N) and the deviation diffTb(N) ~ which are calculated in step S220 are positive or negative » (step S240). : = oT If the deviation diffTa(N) and the deviation diffTb(N) are positive (step S240: YES), the active independent operation determination unit 165 carries out the positive pattern detection processing of step S250 and if the deviation diffTa(N) and the deviation diffTb(N) are negative (step S240: NO), carries out the negative pattern : 30 detectionprocessingofstepS260. Moreover, ifthedeviation diffTa (N) ispositiveandthedeviationdiffTb(N) isnegative, the positive pattern detection processing of step S250 is —~ 16 — oo carried out for the deviation diffTa(N) and Lhe negalive ow pattern detection processing of step S260 is carried out for + the deviation diffTb(N). If the deviation diffTa(N) is » negative and the deviation diffTh(N) is positive, the negative o pattern detection processing of step $260 is carried out for the deviation diffTa(N) and the positive pattern detection o processing of step S250 is carried out for the deviation - dif fTh (N) . | oo
FIG. 5 is a sub-routine flowchart of the positive ro pattern detection processing of FIG. 4. Further, FIG. 6 is » a sub-routine flowchart of the negative pattern detection or processing of FIG. 4. } If the deviation diffTa(N) and the deviation > diffTb(N) are positive, the active independent operation —- determination unit 165 takes out p deviations before the - present time fromthe deviation storage unit 160, and compares = the p deviations which are taken out to the thresholds stored in the threshold storage unit 155 (step S250-1). In the - embodiment, p is five. ©
Specifically, as illustrated in FIG. 8, the active o independent operation determination unit 165 takes out, for oo "the Ta system, diffTa(N), diffTa(N-1), diffTa(N-2), © 4iffTa (N-3) and diffTa (N-4), and, for the Tb system, dif£Th (N), o diffTb (N-1), diffTb(N-2), diffTb(N-3) and diffTb(N-4), - respectively, from the deviation storage unit 160.
Next, the active independent operation determination unit 165 takes out thresholds of the positive oo . patternas illustrated in FIG. 9, Thp(N), Thp (N-1), Thp(N-2),
Thp (N-3) and Thp(N-4), which are stored in the threshold storageunit 155, and compares themtodiffTa (N), diffTa(N-1), diffTa(N-2), diffTa(N-3) and diffTa(N-4), and, diffTh (N), : diffTb(N-1), diffTb(N-2), diffTb(N-3) and diffTb (N-4) which :
are taken out from the deviation storage unit 160. 0
Specifically, for the Ta .system, a magnitude te relation is compared between the threshold Thp(N) and the : deviation diffTa(N), and a magnitude relation is compared o between the threshold Thp (N-1) and the deviation diffTa (N-1). * .
Similarly, a magnitude relation is compared between the o threshold Thp (N-2) and the deviation diffTa (N-2}, between - the threshold Thp (N-3) and the deviation diffTa(N-3), and - between the threshold Thp (N-4) and the deviationdiffTa (N-4). a
Furthermore, for the Tb system, a magnitude 0 relation is compared between the threshold Thp(N) and the Pt deviation diffTb (N), and a magnitude relation is compared _ between the threshold Thp (N-1) and the deviationdiffTb(N-1). >
Similarly, a magnitude relation is compared between the - threshold Thp(N-2) and the deviation diffTb(N-2), between - the threshold Thp(N-3) and the deviation diffTb(N-3), and =” between the threshold Thp (N-4) and the deviation diffTb (N-4). i.
The active independent operation determination I unit 165 determines whether or not each of all deviations w which are compared is greater than each threshold + corresponding thereto, respectively, (step 5250-2) . -
If all deviations which are compared are greater = than the thresholds (step S250-2: YES), the active independent = operation determination unit 165 determines that power failure occurs in the commercial power source system 30 and : the dispersed power source 20 is the independent operation so that the interconnecting relay 16 is cut off and the oo commercial power source system 30 is blocked (step S250-3).
In contrast, if even one of the deviations which are compared is not greater than the threshold (step $250-2: NO), it is determined that the dispersed power source 20 is not the independent operation and the connection of the : _ 15 — .
Fo} interconnecting relay 16 is maintained (step $250-4). os
If the deviation diffTa(N) and the deviation oh diffTb(N) are negative, the active independent operation : determination unit 165 takes out p deviations before the - present time fromthe deviation storage unit 160, and compares " the p deviations which are taken out to the thresholds stored - in the threshold storage unit 155 (step S260-1). .
Specifically, as illustrated in FIG. 8, the active independent operation determination unit 165 takes out, for si the Ta system, diffTa(N), diffTa(N-1), diffTa(N-2), oo diffTa(N-3) anddiffTa (N-4), and, for the Tb system, diffTb(N), diffTb (N-1), diffTb(N-2), diffTb(N-3) and diffTb(N-4), respectively, from the deviation storage unit 160. & . Next, the active independent operation - determination unit 165 takes out thresholds of the negative - pattern as illustrated in FIG. 9, Thn(N), Thn(N-1), Thn (N-2), =
Thn(N-3) and Thn(N-4), which are stored in the threshold storageunit 155, and compares themtodiffTa(N), diffTa(N-1), 5 © diffTa(N-2), diffTa(N-3) and diffTa(N-4), and, diffTb(N), 7 diffTb(N-1), diffTb(N-2), diffTb(N-3).and diffTb(N-4) which . ~ are taken out from the deviation storage unit 160. | —
Specifically, for the Ta system, a magnitude . w relation is compared between the threshold Thn (N) and the’ = deviation diffTa(N), and a magnitude relation is compared between the threshold Thn (N-1) and the deviation diffTa (N-1). ‘Similarly, a magnitude relation is compared between the : threshold Thn(N-2) and the deviation diffTa (N-2), between "the threshold Thn(N-3) and the deviation diffTa(N-3), and between the threshold Thn (N-4) and the deviation diffTa (N-4).
Furthermore, for the Tb system, a magnitude oo relation is compared between the threshold Thn(N) and the deviation diffTb(N), and a magnitude relation is compared : i between the threshold Thn (N-1) and the deviation diffTb (N-1) . Ny
Similarly, a magnitude relation is compared between the +i threshold Thn(N-2) and the deviation diffTb(N-2), between the threshold Thn(N-3) and the deviation diffTb(N-3), and - between the threshold Thn (N-4) and the deviation diffTh (N-4) . Fe
The active independent operation determination i. unit 165 determines whether or not each of all deviations z which are compared is smaller than each of thresholds corresponding thereto, respectively, (step 5260-2). is
If all deviations which are compared are smaller - than the thresholds (step $260-2: YES), the active independent da operation determination unit 165 determines that power B failure occurs in the commercial power source system 30 and = i} the dispersed power source 20 is the independent operation i so that the interconnecting relay 16 is cut of f and the ™ commercial power source system 30 is blocked. Further, agate = of the DC/AC inverter 14 (see FIG. 1) is blocked. That is, = a switching signal is not applied to the gate of the inverter = 14 (step S260-3). In contrast, if even one of the deviations. wo which are compared is not smaller than the threshold (step - 5260-2: NO), it is determined that the dispersed power source 20 is not the independent operation and the connection of © theinterconnectingrelayléismaintained. Further, thegate = of the DC/AC inverter 14 (see FIG. 1) is not blocked and is - switched as usual (step S260-4).
As described above, in the active detection function, the reactive power is forcedly injected in the commercial power source system 30 and the power failure of the commercial power source system 30 is detected, and the independent operation of the dispersed power source 20 is detected by fluctuation of voltage change of the commercial power source by the injection of the reactive power. | :
oo < Passive Detection Function > | s
FIG. 7 1s an operation flowchart of the average i power change period calculation unit 130, the power change . period prediction unit 140, the frequency change rate o calculation unit 170 and the passive independent operation Ee determination unit 180.
The average power change period calculation unit - 130 calculates an average period of g power change periods o. before the present time (step S300). In the embodiment, q a is twenty five. The average power change period calculation o unit 130 takes out the power change periods of the Ta system MT and the power change periods of the Tb system which are stored in the power change period storage unit 125, separately. >
Specifically, as illustrated in FIG. 10, for the Ta system, - data of power change periods of twenty five times from present - time, Ta (N), Ta(N-1), .., Ta (N-23) and Ta (N-24) are taken out. -
At the same time, for the Tb system, twenty five power change = : periods of Tb (N), Tb(N-1),.., Tb (N-23) and Tb (N-24) are taken Co oo out. . ow
Next, the average power change period calculation - unit 130 calculates an average Taave of the power change periods | or of the Ta system by calculating | w [Ta (N)+Ta (N-1)+.+Ta (N-23)+Ta(N-24)]/25 for the Ta system. oT
At the same time, the average power change period calculation - unit 130 calculates anaverage Thave of the power change periods + of the Tb system by calculating - [Tb (N)+Tb (N=1)+..+Tb (N-23) +Tb (N-24) ] /25 for the Tb system.
The power change period prediction unit 140 calculates the predicted period from q power change periods before the present time (step S310). The calculation of the predicted period is the same as step S210 of FIG. 4 except that only the number of power change periods is different.
: The frequency change rate calculation unit 170 " calculates the frequency change rate from the average period : and the predicted period (step $320). The frequency change jy rate is obtained with respect to the Ta system and the Tb ~ system, respectively. The frequency change rate of the Ta system is calculated by computing the frequency change rate
A=(the average period-the predicted period)/the average - : period. The frequency change rate B of the Tb system is | - calculated in the same manner. | ak | The passive independent operation determination 8 unit 180 compares each of the frequency change rate A and @ the frequency change rate B of the Ta system and the Tb system which are calculated in the frequency change rate calculation on unit 170 to the threshold stored in the threshold storage —- unit 155 (step $330). The threshold storage unit 155 stores a plurality of thresholds of 0.2%, 0.3%, 0.4% and 0.5%. The pi threshold which is used in the comparison is selected by a i, selection switch. In the embodiment, 0.3% is selected. =
Therefore, each of the frequency change rate Aand the frequency HL change rate B of the Ta system and the Tb system is compared - with the threshold in terms of whether or not each of them ~ oo is greater than 0.3%. :
If each of the frequency change rate A and the - frequency change rate B is greater than 0.3% of the threshold (step S330: YES), the passive independent operation © determination unit 180 proceeds the processing to the next step. The fact that the frequency change rate is large means possibility of the power failure inthe commercial power source system 30 ishigh. Incontrast, if eachof the frequency change rate A and the frequency change rate B is not greater than 0.3% of the threshold (step S330: NO), it is determined that there is no independent operation and then the gate of the
DC/AC inverter 14 (see FIG. 1) is not blocked and is switched 8 as usual (step S360). +
TT ~ If each of the thresholds of the frequency change no rate A and the frequency change rate B is greater than 0.3% Ve of the threshold (step S330: YES), the passive independent - operation determination unit 180 determines whether or not - the frequency change rate A and the frequency change rate -
B reach r times stored in the threshold storage unit 155 while - maintaining the same change direction (a positive or negative 5 sign) of the frequency change rate A and the frequency change o rate B (step S340). If the frequency change rate A and the 4 frequency change rate B, which exceed the threshold and have on the same change direction, continue in r times (step $340:
YES), it is determined that the power failure occurs in the commercial power source system 30 and the dispersed power oO source 20 is the independent operation so that the - interconnecting relay 16 is cut off and the commercial power Ea ~~ source system 30 is blocked. Further, the gate of the DC/AC = inverter 14 (see FIG. 1) is blocked. That is, the switching - signal is not applied to the gate of the inverter 14 (step Pe? .S350). In contrast, if the frequency change rate A and the = frequency change rate B, which exceed the threshold and have o the same change direction, do not continue in r times, it " is determined that the dispersed power source 20 is the independent operation and the connection of the being ) interconnected relay 16 is maintained. Further, the gate of the DC/AC inverter 14 (see FIG. 1) isnotblockedand is switched as usual (step S360). A reason for ensuring whether the frequency change rate exceeding the threshold exceeds the certain number of times is to remove noise and to prevent determination of uncertain independent operation. However, if a plurality of the number of times is set, the detection timing of the independent operation is late. Therefore, the ol number of times stored in the threshold storage unit 155 is & set to be the number of times which satisfies the reliability n of the detection and the speed of the detection. o
As described above, in order to detect the + independent operation, the frequency of the commercial power o source system 1s measured and the frequency change of the - very short time is detected. It is determined that whether o. the previous frequency is in an increasing trend or in a. oo decreasing trend and it is determined that there is the oo 9 .. independent operation when the frequency is in the increasing oy trend or the decreasing trend by comparing the average of theprevious frequency change tothe latest average. However, - : in the invention described above, the independent operation - is determined by comparing the average of the previous - frequency change to the future frequency change after one - cycle. Therefore, the detection time of the independent o operation is shortened. Further, since the independent = operation is detected by comparing the deviation of the HL frequency to the threshold, detection accuracy of the independent operation is improved. -Furthermore, since the ~ independent operation is detected by using two functions of > ~~ the active detection function and the passive detection ~ function, it is possible to reliably perform the detection - of the independent operation.
Claims (12)
1. An independent operation detection apparatus that . detects an independent operation of a dispersed power source which is operated by being interconnected with a commercial power source system, comprising: a reactive power injection unit that injects reactive power into the commercial power source system; a power change period detection unit that detects power change periods of the commercial power source system; a power change period storage unit that stores the power change periods which are detected; an average power change period calculation unit that calculates an average of the power change periods of > previous m times; a power change period prediction unit that predicts " the next power change period from the power change " periods of previous n times; - a deviation calculation unit that calculates a _ deviation of the power change periods which are predicted 0 Cm -~--and--the-—average -of the power--change periods—which" are =~ eT calculated; and - an active independent operation determination unit 0 that determines that the dispersed power source 1s the independent operation if the deviation exceeds the = threshold by comparing the deviation which is calculated to a predetermined threshold in advance, and determines . that the dispersed power source 1s not the independent operation if the deviation does not exceed the threshold.
2. The independent operation detection apparatus as claimed in claim 1, further comprising:
a deviation storage unit that stores a plurality of : deviations in chronological order, which are calculated = in the deviation calculation unit; and Te X a threshold storage unit that stores a plurality of I thresholds corresponding to the plurality of deviations, respectively, a wherein the active independent operation determination unit determines that the dispersed power source is the independent operation if all of the plurality of deviations exceed the plurality of thresholds corresponding to each other by comparing the plurality of deviations stored in chronological order to the plurality of thresholds corresponding to the deviations, respectively, and determines that the dispersed power source is not the independent operation - if even one of the plurality of deviations does not oo exceed the thresholds corresponding to the deviations.
-
3. The independent operation detection apparatus as - claimed in claim 2, wherein ~ the threshold storage unit stores a plurality of | 5 CL mmmthre sh oldcorr esp onding: fo th e-plurality- SE dev fat Fong -— rs C- respectively, by separating the plurality of thresholds ~ into the thresholds of the a positive pattern which are Co used if the deviations which are calculated in the o : deviation calculation unit are positive and the i A thresholds of a negative pattern which are used if the . deviations are negative, and the active independent operation determination unit determines right and wrong of the independent operation by using of the thresholds of the positive pattern if the deviations which are calculated in the deviation calculation unit are positive, and determines right and wrong of the independent operation. by using the.
thresholds of the negative pattern if the deviation which. = are calculated are negative. | Co
:
4. The independent operation detection apparatus as Ea claimed in claim 2, wherein sizes of the plurality of thresholds corresponding to the plurality of deviations, respectively, are different individually.
5. The independent operation detection apparatus as claimed in claim 4, wherein absolute values of the sizes of the plurality of thresholds corresponding to the plurality of deviations, respectively, are as small as the thresholds B corresponding to the previous deviations. | on
-
6. The independent operation detection apparatus as claimed in claiml, wherein = ~ the power change period prediction unit weighs the ~ power change period of a specific time in the power oo change periods of previous n times and predicts the next SW «+ wen -~—power-~change=—-period- “by “calculating ANT TAve rAgETIOE the er—— power change periods of n times after weighing. ©
-
7. The independent operation detection apparatus as ~ claimed: in claim 1, further comprising: ) a frequency change rate calculation unit that calculates the frequency change rate from the average of the power change periods calculated in the average power change period calculation unit and the next power change period predicted in the power change period prediction unit, and a passive independent operation determination unit —-that determines that the dispersed power source is. the independent operation if a frequency change rate CL calculated whenever the next power change period is calculated continuously exceeds the thresholds in a E plurality of times and directions of a plurality of oo frequency changes are the same as each other, and EE determines that the dispersed power source is not the independent operation if the frequency change rate does not continuously exceed the thresholds in a plurality of times or the directions of the plurality of frequency changes are not the same as each other.
8. The independent operation detection apparatus as claimed in claim 1, wherein the power change period detection unit detects both BN periods of a rising period of a voltage of the commercial & power source system and a falling period of the voltage, — separately. N : os
9. The independent operation detection apparatus as claimed in claim 8, wherein = the power change period storage unit stores the ow i --e- rising--period-mof—the- voltage—of~ the -commercialrspower ==" =" ==" = source system and the falling period of the voltage, = individually, in chronological order. ou -
10. The independent operation detection apparatus as ) claimed in claim9, wherein . the average power change period calculation unit, the power change period prediction unit and the deviation calculation unit calculate an average of the power change periods, prediction of the next power change period and a deviation of the average of the power change periods with respect to each of the power change periods by using two power change periods which are detected individually from both periods of the rising period of the voltage of the - commercial power source system and the falling period of - S_ the voltage, and . To : the active independent operation determination unit determines right and wrong of the independent operation | oo by using the deviation which are calculated, individually, with respect to two power change periods.
11. The independent operation detection apparatus as claimed in claim 7, wherein the frequency change rate calculation unit calculates the frequency change rate with respect to each of power change periods by using the two power change periods, and } the passive independent operation determination unit - determines right and wrong of the independent operation — by using the frequency change rate which is calculated individually with respect to two power change periods. = ie
12. An independent operation detection method for = detecting an independent operation of a dispersed power Hu meee mmgouTCe which is ~operated DY SBELIG it Er COREE EE itha== eer commercial power source system, comprising: - injecting a reactive power into the commercial power » source system; : detecting power change periods of the commercial : power source system; o storing the power change periods which are detected; calculating an average of the power change periods of previous m times; predicting the next power change period from the power change periods of previous n times;
] calculating a deviation of the power change periods. which are predicted and the average of the power change: AE periods which are calculated; and [ : : determining that the dispersed power source is the independent operation if the deviation exceeds the oo threshold by comparing the deviation which is calculated to a predetermined threshold in advance, and determining that the dispersed power source 1s not the independent } operation if the deviation does not exceed the threshold.
os . ho pr 0b mR st we en
1. ps : Lo
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| JP2013039241A JP6047425B2 (en) | 2013-02-28 | 2013-02-28 | Isolated operation detection device and isolated operation detection method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP6421512B2 (en) * | 2014-09-19 | 2018-11-14 | 株式会社デンソー | Power converter |
| CN104655895A (en) * | 2014-12-01 | 2015-05-27 | 国网上海市电力公司 | Micro-current inquiry power supply energy-saving protection system for watt-hour meter |
| JP6421981B2 (en) * | 2015-03-10 | 2018-11-14 | パナソニックＩｐマネジメント株式会社 | Isolated operation detection device and detection method |
| JP6160790B1 (en) * | 2017-03-10 | 2017-07-12 | 富士電機株式会社 | Detection device, power conditioner, detection method, and detection program |
| KR102577911B1 (en) | 2018-11-16 | 2023-09-14 | 상라오 징코 솔라 테크놀러지 디벨롭먼트 컴퍼니, 리미티드 | Power converting apparatus, photovoltaic module, and photovoltaic system including the same |
| CN112019015B (en) * | 2019-05-31 | 2021-11-12 | 广东美的制冷设备有限公司 | Drive control method, device, household appliance and computer readable storage medium |
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| JP4645735B2 (en) * | 2008-12-15 | 2011-03-09 | オムロン株式会社 | Isolated operation detection method, isolated operation detection device, and program |
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| CN104022525A (en) | 2014-09-03 |
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