JP2015023653A - Power conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conditioner that can detect an individual operation of a system with higher accuracy than before when a data collection time is short.SOLUTION: The power conditioner includes: a sensor circuit 8 for detecting a system voltage that is a voltage converted from DC power to AC power and output to a system; a first zero crossing detection section 9 for detecting a positive zero crossing of the system voltage detected by the sensor circuit 8; a first period detection section 11 for detecting a first period of the system voltage from a detection interval of the positive zero crossing; a second zero crossing detection section 10 for detecting a negative zero crossing of the system voltage detected by the sensor circuit 8; a second period detection section 12 for detecting a second period of the system voltage from a detection interval of the negative zero crossing; and a system evaluation section 14 for acquiring information on the first period and information on the second period in order of detection and evaluating a state of the system by means of a plurality of pieces of period information in detecting an anomaly in the system.

Description

  The present invention relates to a power conditioner.

  Conventionally, there is known a power conditioner that detects an abnormality of itself and an AC power supply system and performs system stop and system disconnection operation. For example, in Patent Document 1 below, a power condition in which a detection function for controlling an output current based on target frequency data obtained by adding a frequency bias to a system frequency and detecting a single operation from a change in frequency that appears when a single operation occurs is incorporated. The technology about na is disclosed. In Patent Document 2 below, the zero point of the system voltage is detected, the period until the zero point after N / 2 cycles is counted, and the count number is compared with the count number during the immediately preceding N / 2 cycle, A technique for detecting a system abnormality that determines a system abnormality when the difference exceeds a set value is disclosed.

Japanese Patent No. 3424443 JP-A-6-284560

  However, according to the conventional technique (Patent Document 1), the power conditioner can detect an isolated operation based on a lot of data, but in the future, a large number of photovoltaic power generation systems will be connected to the grid. When this is done, it is required to detect isolated operation at high speed. The detection time limit is 200 ms or less, and 200 ms corresponds to a system cycle of 10 cycles in an area with a system frequency of 50 Hz. Therefore, it is necessary to detect the isolated operation from the frequency data of less than 10 cycles, but there is a problem that the isolated operation may be erroneously detected when the number of data is small.

  Further, according to the above-described conventional technique (Patent Document 2), the power conditioner may be able to detect at a high speed in 1/2 cycle if N = 1, but even-order harmonic distortion is present in the system. In the case where the length of the cycle is different between the positive half cycle and the negative half cycle of the system, there is a problem that every other cycle may fluctuate and erroneous detection may occur.

  The present invention has been made in view of the above, and it is an object of the present invention to obtain a power conditioner capable of detecting an isolated operation with higher accuracy than before when the data collection time is short.

  In order to solve the above-described problems and achieve the object, the present invention provides a sensor for detecting a system voltage, which is a voltage converted from DC power to AC power and output to the system side, and the sensor detects the sensor A first period obtaining means for detecting a positive zero cross of the system voltage and detecting a first period of the system voltage from a detection interval of the positive zero cross; and a negative zero cross of the system voltage detected by the sensor. A second period acquisition means for detecting and detecting a second period of the system voltage from the detection interval of the negative zero cross, and acquiring the information of the first period and the information of the second period in the order of detection; System evaluation means for evaluating the state of the system using information of a plurality of periods and detecting an abnormality of the system.

  According to the present invention, when the data collection time is short, there is an effect that the isolated operation can be detected with higher accuracy than in the past.

FIG. 1 is a diagram illustrating a configuration example of a photovoltaic power generation system. FIG. 2 is a diagram illustrating a configuration example of the power conditioner according to the first embodiment. FIG. 3 is a diagram illustrating a detection example of a cycle of the system voltage in the power conditioner according to the first embodiment. FIG. 4 is a diagram illustrating an approximate line when the AC power system is normal. FIG. 5 is a diagram showing an approximate straight line in the case of showing an isolated operation state. FIG. 6 is a diagram illustrating a detection example of the period of the system voltage in the power conditioner of the second embodiment. FIG. 7 is a diagram illustrating an example of detection of the period of the system voltage when the hysteresis characteristic is provided. FIG. 8 is a diagram illustrating a configuration example of the power conditioner according to the third embodiment. FIG. 9 is a diagram illustrating a detection example of the period of the system voltage in the power conditioner of the third embodiment. FIG. 10 is a diagram illustrating a configuration example of the power conditioner according to the fourth embodiment.

  Embodiments of a power conditioner according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
First, the outline | summary of the solar energy power generation system carrying the power conditioner of this Embodiment is demonstrated. FIG. 1 is a diagram illustrating a configuration example of a photovoltaic power generation system. The solar power generation system includes a solar cell module 1, a connection box 2, a power conditioner 3, a distribution board 4, a load 5, and an AC power system 6.

  In FIG. 1, the output of DC power generated by a plurality of solar cell modules 1 is collected in the connection box 2 and then input to the power conditioner 3. The power conditioner 3 converts the input DC power into AC power and outputs it. This AC power output is supplied to a load 5 such as an electric device inside or outside the house via the distribution board 4 and is connected (connected) to the AC power system 6 so that it cannot be consumed by the load 5. When surplus power is generated, the power is reversed. When the AC power system 6 is in a power failure or the like, the power conditioner 3 outputs AC power from an AC output outlet (not shown) provided in the power conditioner 3 by performing a self-sustaining operation.

  Next, the configuration and operation of the power conditioner 3 according to the present embodiment will be described. FIG. 2 is a diagram illustrating a configuration example of the power conditioner according to the present embodiment. The power conditioner 3 includes a power conversion unit 7, a sensor circuit 8, a first zero cross detection unit 9, a second zero cross detection unit 10, a first cycle detection unit 11, and a second cycle detection unit. 12, a periodic data switching unit 13, and a system evaluation unit 14. The system evaluation unit 14 includes a periodic data string generation unit 15, an inclination detection unit 16, and an isolated operation determination unit 17.

  In FIG. 2, when the DC power from the solar cell module 1 is input via the connection box 2, the power conditioner 3 is converted into AC power by the power conversion unit 7 and output to the AC power system 6 side.

  The power conversion unit 7 outputs AC power by superimposing reactive power having a magnitude corresponding to the frequency deviation. Here, when the AC power system 6 is healthy, the frequency of the system voltage, which is AC power output to the AC power system 6 side, does not change even if the power conditioner 3 outputs reactive power. On the other hand, when the AC power system 6 is disconnected, only the power conditioner 3 is in a state of supplying power to the load 5 (see FIG. 1) not shown in FIG. Such a state is called an isolated operation, and it is necessary to detect the state and stop the power conditioner 3 from an appropriate operational viewpoint. In the single operation state, the frequency of the system voltage changes according to the reactive power output from the power conversion unit 7, and the power conversion unit 7 further outputs reactive power according to the deviation due to the frequency change. Thus, in the single operation state, the power conversion unit 7 outputs reactive power so that positive feedback is applied to the frequency deviation.

  The sensor circuit 8 receives a system voltage that is a voltage output from the power converter 7 to the AC power system 6 side, converts the voltage level, and then converts the voltage level into a digital signal by an AD converter.

  Based on the digital signal from the sensor circuit 8, the first zero-cross detector 9 detects a timing (positive zero-cross) that crosses zero when the system voltage changes from minus to plus.

  Based on the digital signal from the sensor circuit 8, the second zero-cross detector 10 detects the timing (negative zero-cross) that crosses zero when the system voltage changes from positive to negative.

  The first cycle detection unit 11 is a time between timings detected by the first zero-cross detection unit 9, that is, a cycle of the system voltage between two timings when the system voltage is switched from minus to plus (first Cycle).

  The second cycle detection unit 12 is a time between timings detected by the second zero cross detection unit 10, that is, a cycle of the system voltage between the two timings when the system voltage is switched from positive to negative (second cycle). Cycle).

  The cycle data switching unit 13 alternately switches and outputs the cycle data measured by the first cycle detection unit 11 and the second cycle detection unit 12 to the system evaluation unit 14 every time the cycle data is updated.

  In the system evaluation unit 14, the periodic data string generation unit 15 generates a periodic data string that is updated every half cycle of the system voltage from the period data input from the period data switching unit 13. Note that the half cycle of the system voltage is the same length every time the cycle data is measured when the system voltage is a normal sine wave, but every time the cycle data is measured when the frequency of the system voltage changes. May have different lengths.

  The inclination detection unit 16 detects an inclination indicating a change in the period of the system voltage based on the periodic data string generated by the periodic data string generation unit 15.

  The isolated operation determination unit 17 evaluates the state of the AC power system 6 from the change (inclination) of the system voltage cycle detected by the inclination detection unit 16, and determines whether or not the power conditioner 3 is in the isolated operation state. .

  Subsequently, detection of the cycle of the system voltage and determination of the independent operation in the power conditioner 3 according to the present embodiment will be described in detail.

  FIG. 3 is a diagram illustrating a detection example of the cycle of the system voltage in the power conditioner according to the present embodiment. The first zero-cross detection unit 9 and the second zero-cross detection unit 10 receive the system voltage signal converted by the sensor circuit 8.

  The first zero cross detection unit 9 detects the timing (positive zero cross) at which the system voltage switches from negative to positive, and outputs the information to the first cycle detection unit 11. Every time the first cycle detector 11 inputs the information of the positive zero cross detected by the first zero cross detector 9, the detection interval of the positive zero cross based on the previously input information and the information input this time. Period data Ta1, Ta2, and Ta3, which are the first period of

  The second zero cross detector 10 detects the timing (negative zero cross) at which the system voltage switches from positive to negative, and outputs the information to the second cycle detector 12. Every time the second cycle detection unit 12 inputs the information of the negative zero cross detected by the second zero cross detection unit 10, the detection interval of the negative zero cross based on the previously input information and the information input this time Period data Tb1, Tb2, and Tb3, which are the second period of

  The cycle data switching unit 13 updates data on the cycle data Ta1, Ta2, Ta3 output from the first cycle detection unit 11 and the cycle data Tb1, Tb2, Tb3 output from the second cycle detection unit 12. Each time it is switched, it is switched to output to the periodic data string generator 15. In the example of FIG. 3, the periodic data switching unit 13 outputs periodic data in the order of Ta1, Tb1, Ta2, Tb2, Ta3, and Tb3.

  The periodic data string generation unit 15 generates periodic data strings Ta1, Tb1, Ta2, Tb2, Ta3, and Tb3 that are switched every half cycle of the system voltage, and outputs them to the inclination detection unit 16.

  The inclination detection unit 16 calculates an approximate line using several continuous data pieces of the obtained periodic data sequence, and obtains an inclination of the approximate line indicating a change in the period data. Here, the approximate straight lines when the AC power system 6 is normal and when the AC power system 6 is in an isolated state will be described.

  FIG. 4 is a diagram illustrating an approximate line when the AC power system is normal. When the AC power system 6 is normal, each period data has the same length as shown in FIG. Further, the period from the detection of the first period to the detection of the second period and the period from the detection of the second period to the detection of the first period, that is, in the period data switching unit 13 The interval of the period data acquired from the first period detector 11 and the second period detector 12 is constant. In this case, as shown in FIG. 4, the approximate straight line is horizontal and the inclination is “0”. The inclination detection unit 16 outputs information on the inclination value (“0”) at this time to the isolated operation determination unit 17.

  FIG. 5 is a diagram showing an approximate straight line in the case of showing an isolated operation state. In an isolated operation state, that is, when the AC power system 6 is in an abnormal state, the power conversion unit 7 outputs reactive power because positive feedback is applied to the frequency deviation as described above. The frequency of the grid voltage changes. Here, when the frequency of the system voltage changes in the direction of increasing, the first cycle detected by the first cycle detector 11 and the second cycle detected by the second cycle detector 12 are detected. Every time it changes in the direction that the period becomes longer. The approximate straight line at this time has an inclination shown in FIG. 5, and the inclination detecting unit 16 obtains the inclination of the approximate straight line and outputs information on the inclination value at this time to the isolated operation determining unit 17.

  The isolated operation determination unit 17 determines that the vehicle is in the isolated operation state when a predetermined time elapses when the inclination value acquired from the inclination detection unit 16 exceeds the specified value and the inclination value exceeds the specified value. For example, the isolated operation determination unit 17 determines that the AC power system 6 is in a normal state and is not in the isolated operation state when the information of the slope value (“0”) of the approximate straight line illustrated in FIG. 4 is acquired. On the other hand, when the independent operation determination unit 17 acquires the information of the slope value of the approximate straight line illustrated in FIG. 5, the slope value exceeds the specified value and the slope value exceeds the specified value for a predetermined time. When the time has elapsed, the state of the AC power system 6 is abnormal, and is determined to be an independent operation state. When it is determined that the vehicle is in the isolated operation state, the isolated operation determination unit 17 performs control to stop the power conversion unit 7.

  As described above, since the cycle data is updated every half cycle, the system evaluation unit 14 can obtain a sufficient number of data strings as the cycle data even if the detection time period is shortened. 14, since an approximate straight line with few errors can be obtained, it is possible to reduce the probability of erroneous detection and to detect an isolated operation.

  Each period data is updated every half period, but the value of the period data is a value of one period of the system voltage. Therefore, the system evaluation unit 14 is affected even when the system voltage includes even-order harmonic distortion and the length of the cycle differs between the positive half cycle and the negative half cycle of the system voltage. There is nothing.

  As described above, in the present embodiment, the power conditioner can obtain a sufficient number of periodic data even in a short detection time period, and includes an even-order harmonic distortion and a positive half of the system voltage. Even when the period is different between the period and the negative half period, period data that does not fluctuate every other period can be obtained. As a result, even when the data collection time is short, there is an effect that the state of the AC power system can be evaluated without malfunction and the isolated operation can be detected at high speed.

  In the present embodiment, the first zero-cross detector 9 and the first cycle detector 11 are used to acquire and output the first cycle, and the second zero-cross detector 10 and the second cycle detector. Although the second period is acquired and output using the unit 12, the present invention is not limited to this. The first zero-cross detection unit 9 and the first cycle detection unit 11 are configured as one configuration to acquire and output the first cycle, and the second zero-cross detection unit 10 and the second cycle detection unit 12 are configured as one configuration. As a result, the second period may be acquired and output.

Embodiment 2. FIG.
In the present embodiment, the difference from Embodiment 1 will be described in the case where a comparator is used for the sensor circuit 8.

  FIG. 6 is a diagram illustrating a detection example of the cycle of the system voltage in the power conditioner of the present embodiment. Here, the sensor circuit unit 8 is configured by a circuit such as a comparator that converts a voltage sensor signal into a rectangular wave signal that switches between positive and negative. Other configurations are the same as those of the first embodiment (see FIG. 2).

  In FIG. 6, the sensor circuit unit 8 compares the voltage signal with the 0 level, and outputs a high level signal when the voltage signal is higher than 0 and a low level signal when the voltage signal is lower than 0.

  Note that the comparator of the sensor circuit unit 8 may have hysteresis characteristics. FIG. 7 is a diagram illustrating an example of detection of the period of the system voltage when the hysteresis characteristic is provided. High level judgment and low level judgment are set to different levels. As a result, malfunctions are reduced even when noise is superimposed on the voltage signal near the 0 level.

  The first zero cross detection unit 9 detects the rising edge of the rectangular wave signal output from the sensor circuit unit 8, and outputs timing information at that time to the first cycle detection unit 11. Whenever the timing information detected by the first zero-cross detection unit 9 is input, the first cycle detection unit 11 obtains cycle data Ta1, Ta2, Ta3 based on the previously input information and the information input this time. Output.

  The second zero cross detection unit 10 detects the falling edge of the rectangular wave signal output from the sensor circuit unit 8, and outputs timing information to the second cycle detection unit 12. Every time the timing information detected by the second zero cross detector 10 is input, the second cycle detector 12 obtains cycle data Tb1, Tb2, Tb3 based on the previously input information and the information input this time. Output. Subsequent operations are the same as those in the first embodiment.

  As described above, in the present embodiment, in the power conditioner, the determination of zero crossing is determined by switching of the rectangular wave signal converted by the comparator, and the period data is also measured by detecting the edge of the rectangular wave signal. It was decided to measure the time. Thereby, in addition to the effect of Embodiment 1, there exists an effect that a software processing burden can be reduced.

Embodiment 3 FIG.
In the present embodiment, a configuration that does not use the periodic data switching unit 13 will be described with respect to portions that are different from the first embodiment.

  FIG. 8 is a diagram illustrating a configuration example of the power conditioner according to the present embodiment. The power conditioner 3 a includes a power conversion unit 7, a sensor circuit 8, a high level period measurement unit 18, a low level period measurement unit 19, a periodic data generation unit 20, and a system evaluation unit 14.

  In FIG. 8, the sensor circuit unit 8 compares the voltage signal with the 0 level, and outputs a high level signal when the voltage signal is higher than 0 and a low level signal when the voltage signal is lower than 0. The sensor circuit unit 8 outputs high level and low level signals to the high level period measurement unit 18 and the low level period measurement unit 19. The high level period measurement unit 18 outputs information on the high level period to the cycle data generation unit 20. The low level period measurement unit 19 outputs low level period information to the periodic data generation unit 20. The period data generation unit 19 generates period data and outputs the period data to the period data string generation unit 15.

  FIG. 9 is a diagram illustrating a detection example of the period of the system voltage in the power conditioner of the present embodiment. The high level period measurement unit 18 detects a high level in the rectangular wave signal output from the sensor circuit unit 8, and specifically measures a period (ta1, ta2, ta3) in which the high level continues. The high level period measurement unit 18 outputs the measurement value of the period during which the high level has continued until the rectangular wave signal has become the low level to the periodic data generation unit 20, and when the rectangular wave signal has become the high level again. The measurement period is newly measured from 0.

  The low level period measurement unit 19 detects a low level in the rectangular wave signal output from the sensor circuit unit 8, and specifically measures a period (tb1, tb2, tb3) in which the low level continues. The low level period measurement unit 19 outputs the measurement value of the period during which the low level has continued until the rectangular wave signal becomes high level to the periodic data generation unit 20, and when the rectangular wave signal becomes low level again. The measurement period is newly measured from 0.

  The period data generation unit 20 acquires the output value acquired this time (for example, tb1 of the low level duration) and the output acquired last time every time the output values of the high level period measurement unit 18 and the low level period measurement unit 19 are acquired. The period data (Ta1) is generated by adding the value (for example, ta1 of the high level duration), and the generated period data is output to the period data string generation unit 15. Subsequent operations are the same as those in the first embodiment.

  As described above, in the present embodiment, in the power conditioner, the period measurement is performed by measuring the time of each of the high level and low level of the rectangular wave signal, and adding the measured high level and low level periods. It was decided to generate periodic data. Thus, in addition to the effect of the first embodiment, there is an effect that the configuration can be simplified because the data switching process is not necessary.

Embodiment 4 FIG.
In the present embodiment, the isolated operation state is determined using the change in the slope of the approximate straight line. A different part from Embodiment 1 is demonstrated.

  FIG. 10 is a diagram illustrating a configuration example of the power conditioner according to the present embodiment. The power conditioner 3b is different from the first embodiment (see FIG. 2) in that a system evaluation unit 14a is provided instead of the system evaluation unit 14. The system evaluation unit 14a includes a periodic data string generation unit 15, an inclination detection unit 16, an inclination change detection unit 21, and an isolated operation determination unit 17a.

  As described above, the inclination detection unit 16 obtains the inclination of the approximate straight line of the periodic data string for each half period in which the periodic data is updated. The inclination detection unit 16 outputs information on the inclination value of the approximate straight line to the inclination change detection unit 21.

  The inclination change detection unit 21 detects a change in inclination, for example, by comparing information on the inclination value acquired this time with information on the inclination value acquired last time. As described above, when the AC power system 6 is in a single operation state due to an abnormal state or the like, positive feedback is applied to the magnitude of reactive power to be output in the power conversion unit 7, and the change in the cycle gradually increases. The fact that the change in inclination is large in the inclination change detection unit 21 indicates that positive feedback is applied in the power conversion unit 7 and the change in the period is gradually increasing. The inclination change detection unit 21 outputs information on the detected change value of the inclination to the isolated operation determination unit 17a.

  The isolated operation determination unit 17a acquires the information on the inclination value output from the inclination detection unit 16 and the information on the inclination change value output from the inclination change detection unit 21, and the inclination value is within a specified value. When the state in which the change value of the inclination exceeds the specified value and the change value of the inclination exceeds the specified value has elapsed for a predetermined time, the state of the AC power system 6 is abnormal, and is determined to be the single operation state. The islanding operation determination unit 17a performs control to stop the power conversion unit 7 when it is determined as the islanding operation state. As in the first embodiment, the isolated operation determination unit 17a performs the isolated operation when a predetermined time elapses when the inclination value acquired from the inclination detection unit 16 exceeds the specified value and the inclination value exceeds the specified value. Judged as a state.

  As described above, in the present embodiment, the power conditioner can detect the change in frequency due to the reactive power output by the power conditioner itself by detecting the slope of the change in the period. Thereby, in addition to the effect of Embodiment 1, there exists an effect that an isolated operation state can be detected with fewer erroneous detections.

  In the present embodiment, the isolated operation determination unit 17a uses the information on the inclination value output from the inclination detection unit 16 and the information on the change value of the inclination output from the inclination change detection unit 21 in the isolated operation state. However, the present invention is not limited to this. For example, the isolated operation determination unit 17a may determine the isolated operation state using only the information on the change value of the inclination output from the inclination change detection unit 21. In this case, the determination process in the isolated operation determination unit 17a can be simplified as compared with the case of determination using two pieces of information.

  As described above, the power conditioner according to the present invention is useful when converting DC power into AC power, and is particularly suitable when connecting to a system.

  DESCRIPTION OF SYMBOLS 1 Solar cell module, 2 Junction box, 3, 3a, 3b Power conditioner, 4 Distribution board, 5 Load, 6 AC power system, 7 Power conversion part, 8 Sensor circuit, 9 1st zero cross detection part, 10 1st 2 zero cross detection units, 11 first cycle detection unit, 12 second cycle detection unit, 13 cycle data switching unit, 14, 14a system evaluation unit, 15 cycle data string generation unit, 16 slope detection unit, 17, 17a Isolated operation determination unit, 18 High level period measurement unit, 19 Low level period measurement unit, 20 Period data generation unit, 21 Inclination change detection unit.

Claims (9)

A sensor that detects a system voltage, which is a voltage converted from DC power to AC power and output to the system side;
First period obtaining means for detecting a positive zero cross of the system voltage detected by the sensor and detecting a first period of the system voltage from a detection interval of the positive zero cross;
Second period acquisition means for detecting a negative zero cross of the system voltage detected by the sensor and detecting a second period of the system voltage from a detection interval of the negative zero cross;
System evaluation means for acquiring the information of the first period and the information of the second period in the order of detection, evaluating the state of the system using information of a plurality of periods and detecting an abnormality of the system;
A power conditioner comprising: The system evaluation means is
Inclination detection means for detecting the inclination of the change in the period of the system obtained continuously,
When a state where the inclination detected by the inclination detecting unit is larger than a specified state continues for a predetermined time, it is determined that the system is abnormal.
The power conditioner according to claim 1. The system evaluation means is
Inclination detection means for detecting the inclination of the change in the period of the system obtained continuously, and inclination change detection means for detecting the change in the inclination detected by the inclination detection unit,
When the inclination detected by the inclination detection means is within a specified range, and the state in which the change in inclination detected by the inclination change detection means is larger than the specified state continues for a predetermined time, it is determined that the system is abnormal
The power conditioner according to claim 1. The first period acquisition means
First zero cross detection means for detecting a positive zero cross of the system voltage detected by the sensor;
First period detecting means for detecting a first period of the system voltage from a detection interval of the positive zero cross detected by the first zero cross detecting means;
With
The second period acquisition means is
Second zero cross detection means for detecting a negative zero cross of the system voltage detected by the sensor;
Second period detecting means for detecting a second period of the system voltage from the detection interval of the negative zero cross detected by the second zero cross detecting means;
The power conditioner according to claim 1, 2, or 3. The sensor inputs the system voltage, generates a digital signal data string by A / D conversion after voltage level conversion,
The first zero-cross detection unit and the second zero-cross detection unit detect a zero-cross by calculation from the data string.
The power conditioner according to claim 4. The sensor comprises a comparator that compares the system voltage with a constant voltage.
The power conditioner as described in any one of Claims 1-4 characterized by the above-mentioned. A sensor that converts the system voltage converted from DC power to AC power and output to the system side into a rectangular wave signal that switches between positive and negative in comparison with a constant voltage;
High level period measuring means for measuring a period during which a high level of the rectangular wave signal from the sensor continues,
Low level period measuring means for measuring a period during which the low level of the rectangular wave signal from the sensor continues,
Each time the information of the high level period measured by the high level period measuring means and the information of the low level period measured by the low level period measuring means are acquired, the information of two consecutive periods is added to obtain the information. Periodic data generating means for generating information on the cycle of the system voltage;
System evaluation means for acquiring information on the cycle, evaluating a state of the system using information on a plurality of cycles, and detecting an abnormality of the system;
A power conditioner comprising: The system evaluation means is
Inclination detection means for detecting the inclination of the change in the period of the system obtained continuously,
When a state where the inclination detected by the inclination detecting unit is larger than a specified state continues for a predetermined time, it is determined that the system is abnormal.
The power conditioner according to claim 7. The system evaluation means is
Inclination detection means for detecting the inclination of the change in the period of the system obtained continuously, and inclination change detection means for detecting the change in the inclination detected by the inclination detection unit,
When the inclination detected by the inclination detection means is within a specified range, and the state in which the change in inclination detected by the inclination change detection means is larger than the specified state continues for a predetermined time, it is determined that the system is abnormal
The power conditioner according to claim 7.

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