JP3587909B2 - Protection device for grid-connected power generator - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a grid-connected power generation apparatus according to a home-use small-scale power generation system that links a private power generation system with a commercial power supply by using a grid protection device and an inverter or a grid protection function built-in inverter. It relates to a protection device.
[0002]
[Prior art]
Conventionally, in grid-connected private power generation facilities (not self-sustained operation), in order to ensure the safety of workers (prevent electric shock), the operation of the private power generation facilities should be stopped in the event of a power outage according to the technical guidelines on interconnection. An operation detection function is required, and it is stipulated that one of the passive system and the active system recognized as currently effective is used in combination as a means for detecting the independent operation.
[0003]
However, according to the conventional third-order harmonic voltage distortion sudden increase detection method of the isolated operation function and the passive method adopted in the conventional system interconnection protection device and the inverter with a built-in system interconnection protection function, the third harmonic generated at the time of a power failure is considered. It is determined whether or not the operation is the single operation (whether or not there is a power failure) based on the magnitude (peak value or effective value) of the wave voltage.
[0004]
In other words, the threshold value of the third harmonic voltage can be set in the system interconnection protection device or the inverter with a built-in system interconnection protection function, and the magnitude of the third harmonic voltage generated for some reason ( If the peak value or the effective value) exceeds the threshold value, it is determined that a power failure has occurred, and if it is less than the threshold value, it is determined that the power failure has not occurred.
[0005]
[Problems to be solved by the invention]
However, as a practical matter, at each inverter installation site, (1) the capacity of the columnar transformer, (2) the line impedance from the columnar transformer to the inverter, (3) the house where the inverter is installed and the surrounding houses supplied with power from the same columnar transformer. Due to the load impedance and the like, the magnitude and waveform of the third harmonic voltage generated at the time of a power failure and at other times (instantaneous voltage drop, instantaneous power failure, phase jump, etc.) are significantly different spatially and temporally.
[0006]
Therefore, if a specific value of the third harmonic voltage (standard value of the technical guideline, etc.) is set for the judgment at the time of the power failure, for example, if the set value is too small, the power failure may occur erroneously even though it is not a power failure. Judgment is made, and the inverter is stopped unnecessarily, or conversely, if the set value is too large, it cannot be detected even though it is actually stopped, and the inverter continues to operate independently.
[0007]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is an object of the present invention to update a criterion of power failure / non-power failure by a third harmonic voltage for system interconnection protection to a more accurate one. An object of the present invention is to provide a protection device for a grid-connected power generation device that can perform the above-described steps.
[0008]
[Means for Solving the Problems]
The present invention has the following configuration to solve the above problems.
The invention according to claim 1 is a protection device for a grid-connected power generator that detects an isolated operation of the power generator for private use by a third harmonic voltage distortion rapid increase detection method in order to protect the grid connection between the power generator for private use and the commercial power supply. Monitoring means for monitoring the sudden increase in the third harmonic voltage distortion, islanding operation detecting means for judging islanding from the monitored sharply increasing third harmonic voltage distortion, and judging that the islanding detecting means is islanding. Memory means for storing the time axis waveform of the third harmonic voltage at the time of the single operation by applying feedback, and learning the time axis waveform of the stored third harmonic voltage, and generating the third order voltage generated thereafter. the criteria for the isolated operation for harmonic voltage waveform patterns possess the isolated operation determination reference learning means for setting one after another, the isolated operation determination reference learning means, the time axis of the third harmonic voltage Classifying the pattern shape voltage by the shape-peak value or the like, a protective device to that system Mitsururen system power generating device, characterized in that to continue to set the threshold criteria for each pattern.
[0009]
In the invention according to claim 2, the islanding operation criterion learning means classifies the time axis waveform voltage of the third harmonic voltage into patterns according to shapes, peak values, and the like, and sets a criterion threshold for each pattern. The protection device for a grid-connected power generation device according to claim 1, wherein the protection device is a protection device.
[0010]
Here, instead of fixing the threshold value uniquely for the third harmonic voltage generated at the time of the power failure, the third harmonic at the time of the power failure is designed to cope with the spatial and temporal fluctuations in the installation place and surrounding conditions. It is necessary to recognize the generation pattern of the wave voltage.
Therefore, in the present invention, the time axis waveform of the third harmonic voltage generated at the time of the power failure is sequentially stored in the memory, classified into patterns based on, for example, its shape and peak value, and a threshold value is set for each pattern.
[0011]
FIG. 1 is an example of a time axis waveform of a third harmonic voltage generated at the time of a power failure. This example is characterized in that the local maximum value of the third harmonic voltage appears in two places. In the pattern recognition according to the present invention, for example, the time axis position where the two local maximum values appear, the two local maximum values , The maximum third harmonic voltage value, etc. are used as pattern recognition. Thereafter, when a similar third harmonic voltage waveform pattern occurs, it is determined that a power failure has occurred.
[0012]
Incidentally, the third harmonic voltage represents a third component of harmonic voltage distortion {a frequency three times the fundamental frequency (60 Hz in Kansai)}.
In general, when a voltage waveform is taken, ideally, a completely sinusoidal wave is ideally used, but actually, there is some distortion. The distorted voltage waveform is formed by superimposing a fundamental wave and a harmonic (second, third,...). For example, as shown in FIG.
[0013]
At the time of a power failure, voltage distortion is generated by an inverter, a transformer, an inductance, a load, and the like. Particularly, since a sharp increase in the third harmonic component is remarkable, it is used as a factor for detecting islanding operation.
However, the generation pattern and mechanism of the third harmonic voltage distortion have not yet been elucidated.
[0014]
FIG. 2 is an explanatory diagram of a circuit configuration according to the present invention.
The filter circuit 10 extracts the third harmonic voltage component included in the voltage of the system 12 (system voltage). When the value (peak value or effective value) of the third harmonic voltage exceeds the reference, Then, a trigger signal is sent from the voltage detection circuit 14 to the A / D conversion circuit 16, and the waveform of the third harmonic voltage is stored in the primary memory 18.
[0015]
The system voltage is monitored by other interconnection protection functions (overvoltage, undervoltage, frequency increase, frequency decrease) and the system voltage abnormality detection circuit 20 of an independent operation detection active type, and an actual power failure occurs The presence or absence can be determined by these system voltage abnormality detection circuits 20 with a slight time difference. Each sends a trigger signal to the primary memory 18 in response to a power failure and non-power failure, the waveform of the third harmonic voltage main memory 1 (power failure) 22 _1, a main memory 2 (non-power failure) 22 ₂ is stored in.
[0016]
In the passive operation method (third-harmonic voltage distortion sharp increase detection method) according to the present invention, a power outage / non-power outage determination criterion (for example, a threshold value) is determined by the power outage and non-power outage third harmonic voltage stored in the main memory. However, it is possible to update to a more accurate one.
[0017]
Therefore, for example, at the installation location of the inverter, it is assumed that the criterion (threshold) of the third harmonic voltage is set to a small value (easy to determine the power outage) at the time of installation, in view of safety. Even if an erroneous judgment is made, the criterion is updated one after another by the learning function of the main memory, the erroneous judgment of the power failure is eliminated, and the disconnection and gate blocks from the inverter system are reduced unnecessarily.
[0018]
Conversely, even if the criterion (threshold) is set to a large value at the time of installation (it is difficult to determine a power failure), initially, even if the criterion cannot detect a power failure (actually, other protection functions). Then, the criterion (threshold) is successively updated to a small value by the learning function of the main memory, and the non-detection of the power failure is eliminated.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 4 shows an example of a circuit configuration (interconnection type protection function) of a system protection function (corresponding to a protection device) built-in type reverse conversion device (inverter) 24 according to the present embodiment.
[0020]
The inverter 24 is roughly divided into an inverter main circuit section 26 and a protection function circuit section 28.
The inverter main circuit section 26 is for converting a power supply from a private generator (for example, a solar cell) into a commercial frequency voltage and inputting the commercial frequency voltage to the grid 12 for interconnection.
[0021]
The protection function circuit unit 28 includes an interconnection protection function (overvoltage (OVR), undervoltage (UVR), frequency increase (OFR), frequency decrease (UFR)) circuit 30a, an islanding detection active system circuit 30b, and It has a system voltage abnormality detection circuit 30 including the passive operation detection circuit 30c according to the present invention. In this case, the islanding detection passive system circuit 30c includes a sensor unit including a filter circuit and a voltage detection circuit, and a control unit including other components.
In the other configurations, the same reference numerals are given to the same portions as those in the circuit configuration of FIG. 2 and description thereof is omitted.
[0022]
When the system voltage abnormality detection circuit 30 detects an abnormality in the system voltage, the inverter 24 sends a gate block signal or an interconnecting relay release signal to the inverter main circuit 26 to stop the output of the inverter main circuit 26. .
[0023]
The detection of the abnormal voltage in the protection function circuit unit 28 is performed according to the flowchart of FIG. In this flowchart, each step is abbreviated as S1.
The third harmonic voltage generated in the system is extracted from the voltage of the system 12 by the filter circuit 10 (S1).
[0024]
Then, it is determined whether or not a sudden increase in the third harmonic voltage occurs (S2). If it occurs (S2: yes), a trigger signal is sent from the voltage detection circuit 14 to the A / D conversion circuit 16 (S3). ) The third harmonic voltage waveform is temporarily stored in the primary memory 18 (S4).
[0025]
Incidentally, the voltage value can be determined that the power failure in the main memory (1) 22 ₁ (or waveform), also a main memory (2) 22 ₂ voltage value can be determined that the non-power failure (or waveform) is accumulated. (Originally inverter installed only set values in the main memory (1) 22 ₁ is stored.)
[0026]
A pattern analysis of the voltage waveform stored in the primary memory 18 is performed (S5). A power failure is determined for one of the analyzed waveform patterns (for example, TIPE1 to TAIPE3) after S6. In FIG. 5, the value of the third harmonic voltage is X1.
[0027]
In S6, for example, in the waveform of TIPE2, if the value X1 of the third harmonic voltage stored in primary memory 18 is a main memory (1) 22 ₁ criterion value a1 or more (X1 ≧ a1), It is determined that a power failure has occurred, and a gate block signal is transmitted (S61).
Meanwhile, the value X1 of the third harmonic voltage stored in primary memory 18 if main memory (2) 22 ₂ criteria values b1 below (X1 ≦ b1), it is determined that the non-power failure.
[0028]
Furthermore, between the primary memory 18 the value X1 of the housing has been the third harmonic voltage main memory (1) 22 ₁ criterion value a1 and the main memory (2) 22 ₂ criteria values b1 (B1 <X1 <a1), it is once determined that a power failure has occurred, which is subsequently verified by another protection function (S7), and if the determination is correct (S7: yes), it is stored in the primary memory. the value X1 of been third harmonic voltage is stored in the main memory (1) 22 _1, and becomes a new value of the criterion a1 (a1 = X1) (S8).
On the other hand, incorrect value X1 is main memory of the third harmonic voltage stored in the primary memory 18 when was determined (2) 22 ₂ value of the stored new criteria to b1 (b1 = X1) (S9).
[0029]
Further, in the S6, the value X1 of the third harmonic voltage stored in the primary memory 18 determines that power failure is the main memory (1) 22 ₁ value a1 or more, other protection functions step by this (S10). In this case, if the determination is incorrect (S10: no), for example, the waveform is analyzed (S11), and if it is a new waveform pattern (S12: yes), the process ends. On the other hand, if not a new waveform pattern (S12: no), the main memory (1) 22 ₁ of the value a1 criteria 10% greater (a1 = a1 × 1.1) to (S13).
[0030]
Furthermore, it said although third harmonic voltage value X1 stored in the primary memory 18 determines that the non-power failure becomes the main memory (2) 22 ₂ values b1 below, verifies chasing this (S14 ). For example, the waveform is analyzed (S15), and if it is a new waveform pattern (S16: yes), the process is terminated. On the other hand, if not a new waveform pattern (S16: no), the main memory (2) 22 down ₂ of the values b1 criteria 10% (b1 = b1 × 0.9) to (S17).
[0031]
By repeating the above procedure and updating the determination criteria values a1 and b1, that is, by learning, it is possible to realize highly accurate power failure / non-power failure determination.
[0032]
Note that the present invention is not limited to the above embodiment. For example, it is determined that the power failure in the S16, Otte when wrong is determined: in (S10 no), in addition to employing the procedure of S10 to S13, the main memory (1) when happened the same again 22 ₁ It is also possible to perform processing to increase the value a1 of the judgment criterion by 10%.
[0033]
【The invention's effect】
As described above, according to the present invention, the threshold value of the third harmonic voltage of the passive operation detection method (third harmonic voltage distortion sharp increase detection method) which is difficult to set depending on the electric environment at the installation location of the grid-connected power generation device However, with the learning function, it is possible to automatically change to a higher-precision one, and it is possible to minimize unnecessary inverter operation stop, which is difficult with the conventional passive system, and realize a system with high power generation efficiency It has an excellent effect that it is possible to cause
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an example of a time axis waveform of a third harmonic voltage.
FIG. 2 is an explanatory diagram of a circuit configuration example of the present invention.
FIG. 3 is an explanatory diagram of a waveform example of a third harmonic voltage.
FIG. 4 is an explanatory diagram showing an example of a circuit configuration (interconnection type protection function) of a system protection function (corresponding to a protection device) built-in reverse converter (inverter) according to the embodiment of the present invention.
FIG. 5 is a flowchart according to the embodiment.
[Explanation of symbols]
Reference Signs List 10 filter circuit 12 system 14 voltage detection circuit 16 A / D conversion circuit 18 primary memory 22 ₁ main memory (1) (for power failure detection)
22 ₂ Main memory (2) (for non-power failure detection)
24 Inverting device 26 Inverter main circuit unit 28 Protection function circuit unit 30 System voltage abnormality detection circuit 30c Islanding detection passive system circuit

Claims (1)

Third harmonic voltage distortion in a protection device for a grid-connected power generator that detects the isolated operation of a private power generator using the third harmonic voltage distortion rapid increase detection method to protect the grid connection between the private power generator and the commercial power supply Monitoring means for monitoring the rapid increase, islanding operation detecting means for judging islanding from the monitored sudden increase in the third harmonic voltage distortion, and applying feedback when the islanding detecting means judges that islanding is being performed; Memory means for storing a time axis waveform of the third harmonic voltage during the single operation; learning a time axis waveform of the stored third harmonic voltage; possess the isolated operation determination reference learning means for setting one after the other criteria of driving, the isolated operation determination reference learning means, third harmonic shape-wave time axis waveform voltage of the voltage Classifying the pattern by a value such as protection devices to that system Mitsururen system power generating device, characterized in that to continue to set the threshold criteria for each pattern.

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