JP2020112387A - Sensor abnormality detection device, distributed power supply unit, and sensor abnormality detection method - Google Patents

Abstract

To accurately determine whether an operation of a current sensor is normal or abnormal at a lower cost.SOLUTION: A sensor abnormality detection device comprises: a measurement circuit for periodically measuring an effective value or a current frequency of an AC current flowing in a cable based on an output of th sensor; a first determination circuit for making a determination regarding sensor abnormality during a first measurement time that is equal to or longer than at least one cycle of the AC current based on an output of the measurement circuit at every first measurement time; and a second determination circuit for determining whether the sensor is abnormal based on the determination result by the first determination circuit during a second measurement time that is longer than the first measurement time.SELECTED DRAWING: Figure 11

Description

The present invention relates to a sensor abnormality detection device, a distributed power supply unit, and a sensor abnormality determination method.

Distributed power supply units including fuel cells, solar power generators, storage batteries, etc. are becoming popular. The distributed power supply unit is connected to a power line (cable) from the grid to the load and supplies power to the load according to the power supplied from the grid to the load and the size of the load. Such a function of the distributed power supply unit can reduce transmission loss due to the grid. Further, by supplying electric power to the load from the distributed power supply unit when the electric power supply from the grid is reduced, the operation of the device corresponding to the load can be normally maintained. Since the convenience is improved by installing the distributed power supply units in this way, the number of installed distributed power supply units is increasing.

The generated power of such a distributed power supply unit increases, and surplus power is generated when the power consumption of the load is exceeded. This surplus power will flow backwards to the grid if nothing is done. However, in order to secure the power quality of the grid, such reverse power flow is often not recognized. Therefore, it is necessary to prevent reverse power flow.

For that reason, it is often practiced to provide a current sensor in the electrical path from the grid to the load. This current sensor monitors the current between the system and the load, and controls the distributed power supply unit so that reverse power flow does not occur.

As such a current sensor, a clamp type current sensor is often used. The clamp-type current sensor has a measurement line consisting of a winding.By mounting the winding so that the winding surrounds the electric path, the current generated in the measurement line by the mutual inductance between the alternating current flowing through the electric path and the measurement line. Is output. By knowing the magnitude of this current, the magnitude of the current flowing through the electric path can be known.

Such a clamp-type current sensor can measure the magnitude of the current flowing in the electric path simply by attaching it to the electric path by the clamp. Therefore, the current sensor can be easily installed and maintained. On the other hand, however, the clamp-type current sensor has a risk of falling out of the electric circuit, incomplete installation, and incorrect connection direction. When such a situation occurs, the current flowing through the electric line cannot be correctly detected. If the current cannot be detected correctly, there is an increased risk of reverse power flow. Therefore, it is necessary to immediately detect such problems and take appropriate measures.

A proposal for solving such a problem is made in Patent Document 1 described later. The distributed power supply unit disclosed in Patent Document 1 includes a distributed power supply, a first current sensor to be connected to a first voltage line, and a second current sensor to be connected to a second voltage line. And a determination unit. The determination unit supplies a plurality of power supplies for a predetermined time from the system power supply to the power loads connected to the first and second voltage lines between the planned connection positions of the first and second current sensors and the distributed power supply. Then, the presence or absence of the connection of the first and second current sensors, the connection position, and the correctness of the connection direction are determined based on the result.

JP, 2005-122819, A

However, in the technique disclosed in Patent Document 1, the internal power load of the distributed power supply unit is energized, and the presence or absence of the current sensor is determined based on the amount of change in the current measurement value by the current sensor before and after energization. Therefore, the distributed power supply unit must be provided with an internal power load and a switch. Since the distributed power supply unit has many parts, there is a problem that the cost becomes high.

Therefore, an object of the present invention is to provide a sensor abnormality detecting device, a distributed power supply unit, and a sensor abnormality determining method capable of highly accurately determining whether the operation of the current sensor is normal or abnormal at a lower cost.

A sensor abnormality detecting device according to a first aspect of the present invention is a sensor abnormality detecting device for detecting an abnormality of a sensor attached to an electric path through which an alternating current flows, and flows through the electric path based on an output of the sensor. Based on the output of the measurement circuit that periodically measures the effective value or current frequency of the alternating current and the output of the measurement circuit during a first measurement time that is at least one cycle of the alternating current, a first determination is made regarding sensor abnormality. A first determination circuit for each measurement time and a second determination time based on the determination result by the first determination circuit during a second measurement time longer than the first measurement time. And a determination circuit of.

A distributed power supply unit according to a second aspect of the present invention is a distributed power supply unit connected to a single-phase three-wire alternating current circuit, wherein the single-phase three-wire alternating current circuit includes a neutral wire, A first electric circuit and a second electric circuit are included, and a sensor that outputs a current according to the magnitude of the current flowing through the first electric circuit is attached to the first electric circuit. An electric power conversion device provided between the AC electric circuit, a sensor abnormality detection device that determines whether a sensor abnormality has occurred based on the output of the sensor, and a sensor abnormality detection device that detects the occurrence of a sensor abnormality. When not in use, the power converter controls the power converter based on the output of the sensor, and the sensor abnormality detection device controls the power conversion between the DC power supply and the AC power on the AC power line. In response to the detection of the, the abnormality processing circuit for executing the processing at the time of the sensor abnormality, and the sensor abnormality detection device, based on the output of the sensor, the effective value or current frequency of the alternating current flowing through the electric path. Based on the output of the measurement circuit that periodically measures and the first measurement time that is at least one cycle of the alternating current, a first abnormality determination is performed for each first measurement time. The presence/absence of a sensor abnormality is determined based on the determination result of the first determination circuit during the determination circuit and the second measurement time longer than the first measurement time, and the determination result is output to the control circuit and the abnormality processing circuit. A second determination circuit for

A sensor abnormality detecting method according to a third aspect of the present invention is a sensor abnormality detecting method for detecting an abnormality of a sensor mounted on an electric path through which an alternating current flows, and the electric current flows through the electric path based on an output of the sensor. Based on the output in the step of periodically measuring the effective value or the current frequency of the alternating current and in the step of measuring during the first measurement time that is at least one cycle of the alternating current, the first determination regarding the sensor abnormality is made. A second determination step for determining whether or not there is a sensor abnormality based on the determination result of the first determination step between the first determination step performed for each measurement time and the second measurement time longer than the first measurement time. And the steps of.

A sensor abnormality detecting method according to a fourth aspect of the present invention detects an abnormality of a sensor used together with a distributed power supply unit connected to a single-phase three-wire type AC electric circuit. The single-phase, three-wire type AC electric circuit includes a neutral wire, a first electric line, and a second electric line. A sensor that outputs a current according to the magnitude of the current flowing through the first electric path is attached to the first electric path. The distributed power supply unit is a DC power supply, a power conversion device provided between the DC power supply and the AC power line, and a sensor abnormality detection device that determines whether or not a sensor abnormality has occurred, based on the output of the sensor. , For controlling the power conversion device based on the output of the sensor and performing the power conversion between the DC power supply and the AC power on the AC power line when the sensor abnormality detection device does not detect the occurrence of the sensor abnormality. The control circuit includes a control circuit and an abnormality processing circuit for executing processing when the sensor abnormality is detected in response to the sensor abnormality detection device detecting the occurrence of the sensor abnormality. This sensor abnormality detection method includes a step of periodically measuring an effective value or a current frequency of an alternating current flowing through an electric path based on an output of a sensor, and a first measurement time of at least one cycle of the alternating current or more. Based on the output in the step of measuring, the first determination between the first determination step in which the determination regarding the sensor abnormality is performed every first measurement time and the second measurement time longer than the first measurement time. A second determination step of determining whether there is a sensor abnormality based on the determination result of the step and outputting the determination result to the control circuit and the abnormality processing circuit.

According to the present invention, it is possible to provide a sensor abnormality detection device, a distributed power supply unit, and a sensor abnormality determination method capable of highly accurately determining whether the operation of the current sensor is normal or abnormal at a lower cost.

Objects, configurations, and effects of the present invention will be apparent from the accompanying drawings and the following detailed description of the invention.

FIG. 1 is a schematic block diagram of a distributed power supply unit according to the first embodiment of the present invention. FIG. 2 is a schematic block diagram of the distributed power supply unit shown in FIG. FIG. 3 is a block diagram showing a hardware configuration of the control unit shown in FIG. FIG. 4 is a block diagram showing a state in which one of the CT sensors has dropped out in the distributed power supply unit. FIG. 5 is a graph showing an example of the output current of the CT sensor. FIG. 6 is a schematic diagram for explaining an example that can be considered as an abnormality detection method for a CT sensor in a distributed power supply unit. FIG. 7 is a schematic diagram for explaining the CT sensor abnormality detection method in the distributed power supply unit according to the first embodiment of the present invention. FIG. 8 is a flow chart showing a control structure of a program for implementing the first-stage abnormality detection method for the CT sensor according to the first embodiment of the present invention by a computer. FIG. 9 is a schematic block diagram for explaining the principle of erroneous detection of a CT sensor abnormality that may occur in the first embodiment of the present invention. FIG. 10 is a schematic block diagram for explaining the abnormality detection method for the CT sensor according to the first embodiment of the present invention. FIG. 11 is a flow chart showing a control structure of a program for implementing the second-stage abnormality detection method for the CT sensor according to the first embodiment of the present invention by a computer. FIG. 12 is a flow chart showing a control structure of a program for realizing the second-stage abnormality detection method for the CT sensor according to the second embodiment of the present invention by a computer.

In the following description and drawings, the same parts are designated by the same reference numerals. Therefore, detailed description thereof will not be repeated. Note that at least a part of the embodiments described below may be arbitrarily combined.

[Description of Embodiments of the Invention]
A sensor abnormality detecting device according to a first aspect of the present invention is a sensor abnormality detecting device for detecting an abnormality of a sensor attached to an electric path through which an alternating current flows, and flows through the electric path based on an output of the sensor. Based on the output of the measurement circuit that periodically measures the effective value or current frequency of the alternating current and the output of the measurement circuit during a first measurement time that is at least one cycle of the alternating current, a first determination is made regarding sensor abnormality. A first determination circuit for each measurement time and a second determination time based on the determination result by the first determination circuit during a second measurement time longer than the first measurement time. And a determination circuit of. The second measurement time is preferably 5 times or more and 100 times or less as long as the first measurement time.

The first determination circuit repeatedly determines whether or not there is a sensor abnormality in the basic block of the first measurement time. When the second measurement time is completed, the presence or absence of sensor abnormality is determined by the determination result by the first determination circuit during that time. Even if the current frequency of the output current of the sensor happens to fall within the normal range, it is limited to a very small number of basic blocks and does not affect the determination result of the second measurement time. Moreover, there is no extra component for that purpose, and the cost does not increase. As a result, it is possible to provide a sensor abnormality detection device that can determine whether the operation of the current sensor is normal or abnormal with high accuracy at a lower cost.

Preferably, the measurement circuit includes a circuit that periodically measures the effective value and frequency of the current output by the sensor.

The effective value of the current and the frequency are periodically measured, and based on the result, the determination regarding the sensor abnormality of the basic block is performed. By using both, the accuracy of the sensor abnormality determination becomes high.

More preferably, the first determination circuit is such that the difference between the current frequency of the current output from the circuit to be measured during the first measurement time and the reference frequency is a fixed value or more, and the output of the circuit to be measured is The determination during the first measurement time is performed in response to whether or not the condition that the effective value of the alternating current during the first measurement time is less than a certain value, which is calculated based on the above, is satisfied. A third determination circuit is included.

The third determination circuit determines that the sensor is abnormal only when two conditions are satisfied at the same time. The sensor abnormality can be detected with higher reliability than the case where the determination is made by only one of them.

More preferably, the second determination circuit determines whether or not the determination by the third determination circuit for each first measurement time accounts for a predetermined threshold value or more within the second measurement time. It includes a circuit for determining an abnormality of the sensor.

During the second measurement time, which is longer than the first measurement time, it is repeatedly determined whether or not a sensor abnormality is detected in the basic block. Since the sensor abnormality is determined only when the number of basic blocks in which the sensor abnormality is detected within the second measurement time occupies the ratio of the threshold value or more, it is erroneously determined that the sensor abnormality is caused by a local event. You can reduce the risk of being killed.

More preferably, the second determination circuit stores the latest determination result of the first determination circuit during the second measurement time and the storage circuit each time the first measurement time elapses. An abnormality determination circuit for determining the abnormality of the sensor is included according to whether the ratio of the determination result indicating that the sensor is abnormal among the stored determination results is equal to or more than a predetermined threshold value.

Each time the first measurement time ends, the ratio of the basic block in which the sensor abnormality is detected within the second measurement time immediately before that time is determined. Since it is determined whether or not there is a sensor abnormality at every first measurement time, the final sensor abnormality determination interval is the first measurement time, and when there is a sensor abnormality, the sensor abnormality is detected early. it can.

More preferably, the second determination circuit stores the latest determination result of the first determination circuit during the second measurement time and the storage circuit each time the second measurement time elapses. An abnormality determination circuit for determining the abnormality of the sensor is included according to whether the ratio of the determination result indicating that the sensor is abnormal among the stored determination results is equal to or more than a predetermined threshold value.

Each time the second measurement time ends, the ratio of the basic blocks in which the sensor abnormality is detected within the second measurement time is determined. Since it is determined whether or not there is a sensor abnormality every second measurement time that is longer than the first measurement time, the final sensor abnormality determination interval is the second measurement time, and the amount of calculation can be saved.

Preferably, the predetermined threshold value is 50% or more and 100% or less.

It is determined that the sensor abnormality is present only when it is determined that the sensor abnormality is present in 50% or more of the basic blocks in the second measurement time. The risk of erroneously determining that there is a sensor abnormality due to a local event can be reduced.

A distributed power supply unit according to a second aspect of the present invention is a distributed power supply unit connected to a single-phase three-wire alternating current circuit, wherein the single-phase three-wire alternating current circuit includes a neutral wire, A first electric circuit and a second electric circuit are included, and a sensor that outputs a current according to the magnitude of the current flowing through the first electric circuit is attached to the first electric circuit. An electric power conversion device provided between the AC electric circuit, a sensor abnormality detection device that determines whether a sensor abnormality has occurred based on the output of the sensor, and a sensor abnormality detection device that detects the occurrence of a sensor abnormality. When not in use, the power converter controls the power converter based on the output of the sensor, and the sensor abnormality detection device controls the power conversion between the DC power supply and the AC power on the AC power line. In response to the detection of the, the abnormality processing circuit for executing the processing at the time of the sensor abnormality, and the sensor abnormality detection device, based on the output of the sensor, the effective value or current frequency of the alternating current flowing through the electric path. Based on the output of the measurement circuit that periodically measures and the first measurement time that is at least one cycle of the alternating current, a first abnormality determination is performed for each first measurement time. The presence/absence of a sensor abnormality is determined based on the determination result of the first determination circuit during the determination circuit and the second measurement time longer than the first measurement time, and the determination result is output to the control circuit and the abnormality processing circuit. A second determination circuit for

The first determination circuit repeatedly determines whether or not there is a sensor abnormality in the basic block of the first measurement time. When the second measurement time is completed, the ratio of the basic blocks having the sensor abnormality in the basic blocks for which normality/abnormality is determined during that period is calculated, and the presence or absence of the sensor abnormality is determined based on the result. Even if the current frequency of the output current of the sensor happens to fall within the normal range, it is limited to a very small number of basic blocks and does not affect the determination result of the second measurement time. Moreover, there is no extra component for that purpose, and the cost does not increase. As a result, it is possible to provide a distributed power supply unit capable of highly accurately determining whether the operation of the current sensor is normal or abnormal at a lower cost.

Preferably, the sensor abnormality detection device further controls the power conversion device to change the output of the power conversion device by a predetermined amount in response to the determination by the second determination circuit that a sensor abnormality has occurred. An output control device, and a third determination circuit for determining whether or not a sensor abnormality really occurs in the sensor depending on whether or not the output of the measurement circuit changes in response to a change in the output by the output control device. including.

Even if the second determination circuit determines that a sensor abnormality has occurred, if the power consumption of the load and the power supplied from the power conversion device to the load happen to match, the sensor abnormality actually occurs. The output of the sensor may not be correctly measured by the measurement circuit even though the error has not occurred. At that time, if the output of the power converter is changed by a predetermined amount and the measurement circuit measures that the output of the sensor has changed accordingly, it can be determined that the sensor abnormality has not occurred. Conversely, if the sensor output does not change, it can be determined that a sensor abnormality has occurred. Since the occurrence of the sensor abnormality can be confirmed again, the risk of erroneously determining that the sensor abnormality has occurred can be reduced.

More preferably, the output control device controls the power conversion device to reduce the output of the power conversion device by a predetermined amount in response to the second determination circuit determining that the sensor abnormality has occurred. A third determining circuit includes a limiting device and determines whether the output of the measuring circuit is responsive to a change in the output of the output limiting device by an amount corresponding to a decrease in the output of the output limiting device. And a fourth determination circuit for determining whether or not a sensor abnormality has occurred.

When the power converter is connected to the grid, reverse power flow from the system in which the power converter is installed to the grid must be avoided. Under such conditions, increasing the output of the power converter increases the risk of reverse power flow. Therefore, when changing the output of the power converter, it is preferable to reduce the output. The risk of reverse power flow can be reduced.

More preferably, the output limiting device includes a limiter connected between the power conversion device and the AC electric circuit.

By simply limiting the output of the power conversion device by the limiter, it is possible to easily check whether or not a sensor abnormality has occurred using an existing device while preventing reverse power flow.

Preferably, the output limiting device includes a target value setting device that reduces the output of the power conversion device by increasing the power purchase target value by the power conversion device by a predetermined amount.

By setting a large power purchase target value, the output of the power conversion device can be indirectly reduced. By simply limiting the output of the power conversion device, it is possible to easily check whether or not a sensor abnormality has occurred using an existing device while preventing reverse power flow.

A sensor abnormality detecting method according to a third aspect of the present invention is a sensor abnormality detecting method for detecting an abnormality of a sensor mounted on an electric path through which an alternating current flows, and the electric current flows through the electric path based on an output of the sensor. Based on the output in the step of periodically measuring the effective value or the current frequency of the alternating current and in the step of measuring during the first measurement time that is at least one cycle of the alternating current, the first determination regarding the sensor abnormality is made. A second determination step for determining whether or not there is a sensor abnormality based on the determination result of the first determination step between the first determination step performed for each measurement time and the second measurement time longer than the first measurement time. And the steps of.

It is repeatedly determined in the first determination step whether or not there is a sensor abnormality for the first measurement time. When the second measurement time is completed, the ratio of the determination that there is a sensor abnormality in the normal/abnormal determination of the first measurement time during that period is calculated, and the presence or absence of the sensor abnormality is determined based on the result. Even if the current frequency of the output current of the sensor happens to fall within the normal range, it is limited to a very small number of determinations of the first measurement time among the determinations of the second measurement time. It does not affect the judgment result. Moreover, there is no extra component for that purpose, and the cost does not increase. As a result, it is possible to provide a sensor abnormality detection method capable of highly accurately determining whether the operation of the current sensor is normal or abnormal at a lower cost.

A sensor abnormality detecting method according to a fourth aspect of the present invention detects an abnormality of a sensor used together with a distributed power supply unit connected to a single-phase three-wire type AC electric circuit. The single-phase, three-wire type AC electric circuit includes a neutral wire, a first electric line, and a second electric line. A sensor that outputs a current according to the magnitude of the current flowing through the first electric path is attached to the first electric path. The distributed power supply unit is a DC power supply, a power conversion device provided between the DC power supply and the AC power line, and a sensor abnormality detection device that determines whether or not a sensor abnormality has occurred, based on the output of the sensor. , For controlling the power conversion device based on the output of the sensor and performing the power conversion between the DC power supply and the AC power on the AC power line when the sensor abnormality detection device does not detect the occurrence of the sensor abnormality. The control circuit includes a control circuit and an abnormality processing circuit for executing processing when the sensor abnormality is detected in response to the sensor abnormality detection device detecting the occurrence of the sensor abnormality. This sensor abnormality detection method includes a step of periodically measuring an effective value or a current frequency of an alternating current flowing through an electric path based on an output of a sensor, and a first measurement time of at least one cycle of the alternating current or more. Based on the output in the step of measuring, the first determination between the first determination step in which the determination regarding the sensor abnormality is performed every first measurement time and the second measurement time longer than the first measurement time. A second determination step of determining whether or not there is a sensor abnormality based on the determination result of the step and outputting the determination result to the control circuit and the abnormality processing circuit.

It is repeatedly determined in the first determination step whether or not there is a sensor abnormality for the first measurement time. When the second measurement time is completed, the ratio of the determination that there is a sensor abnormality in the normal/abnormal determination of the first measurement time during that period is calculated, and the presence or absence of the sensor abnormality is determined based on the result. Even if the current frequency of the output current of the sensor happens to fall within the normal range, it is limited to a very small number of the judgments during the second measurement time, and the judgment result of the second measurement time is not affected. Does not reach. Moreover, there is no extra component for that purpose, and the cost does not increase. As a result, it is possible to provide a sensor abnormality detection method capable of highly accurately determining whether the operation of the current sensor is normal or abnormal at a lower cost.

The sensor abnormality detection method further includes a step of controlling the power conversion device to change the output of the power conversion device by a predetermined amount in response to the determination that the sensor abnormality has occurred in the second determination step, And a third determination step of determining whether or not a sensor abnormality is truly occurring in the sensor depending on whether or not the measurement result in the measuring step changes in response to the change in the output.

When it is determined in the second determination step that the sensor abnormality has occurred, the output of the power conversion device is changed by a predetermined amount. Then, if the sensor is normal, its output increases or decreases according to this change amount. If the change is measured in the measuring step, it can be determined that the sensor abnormality has not occurred in the third determination step, and it can be determined that the sensor abnormality has occurred otherwise. Therefore, no extra parts are required and the cost does not increase. As a result, it is possible to provide a sensor abnormality detection method capable of highly accurately determining whether the operation of the current sensor is normal or abnormal at a lower cost.

[Details of the embodiment of the present invention]
[First Embodiment]
<Structure>
The embodiments described below are examples of a single-phase three-wire distributed power supply unit. In this example, a CT sensor is used as an example of the sensor.

Referring to FIG. 1, the distributed power supply system 50 includes a grid 60, loads 62, 64 and 66, which are supplied with electric power from the grid 60 via electric lines W, O and U, respectively, and electric lines U and W. Based on the outputs of the CT sensors 70 and 72, the two CT sensors 70 and 72 that are attached and detect the currents flowing through these electric paths U and W, respectively, and the outputs that are connected to the electric paths U, O, and W And a distributed power supply unit 68 for supplying power to the loads 62, 64 and 66 accordingly.

Referring to FIG. 2, the distributed power supply unit 68 includes a power supply unit 90, a DC-DC converter 92 for stepping down a DC current output by the power supply unit 90, and a DC current output by the DC-DC converter 92 as an AC current. And an inverter 94 for converting the inverter 94 to the electric path U and an electric path W and an electric path W, and a limiter 96 for limiting the output of the inverter 94 so as not to exceed a predetermined voltage. The distributed power supply unit 68 supplies, to these constituent elements, the power consumed by the power from the grid 60, which is insufficient with the power from the grid 60, of the load power consumption that changes momentarily based on the CT sensor currents from the CT sensors 70 and 72. The electric power is controlled so as to be covered by the output of the distributed power supply system 50 to improve the overall economic efficiency of the distributed power supply system 50.

In order to perform such output control, the distributed power supply unit 68 has a control unit 80 that receives the outputs of the CT sensors 70 and 72, and the control unit 80 controls the outputs of the CT sensor 70 and the CT sensor 72 based on the outputs. The system current from the system 60 is measured, and power is supplied from the power supply unit 90 of the distributed power supply unit 68, the DC-DC converter 92 and the inverter 94 to the loads 62, 64 and 66 based on the measured value. Although a storage battery is assumed as the power supply unit in this embodiment, the present invention can also be applied to a distributed power supply unit including, for example, a solar power generation device, a wind power generation device, and the like.

If the CT sensor 70 or 72 falls off the electric circuit or the measurement line of the CT sensor 70 or 72 is broken, the control unit 80 of the distributed power supply unit 68 cannot normally measure the system current. Then, the control unit 80 cannot normally perform power control. In this case, it is necessary to stop the protection of the distributed power supply unit 68. Therefore, a mechanism for determining whether the operations of the CT sensors 70 and 72 are normal or abnormal is necessary.

In the CT sensor, a reactive current flows when there is no load, and a combined current of an active current and a reactive current flows when there is a load. In this embodiment, the control unit 80 determines whether the operation of the CT sensors 70 and 72 is normal or abnormal based on such a property of the outputs of the CT sensors 70 and 72, and when it is determined that the operation is the distributed type. It has a function of stopping the operation of the power supply unit 68. In this embodiment, as will be described later, this determination is made in two stages to avoid erroneous determination of CT sensor abnormality.

In order to detect the operation abnormality of the CT sensor as described above, the control unit 80 has the following configuration. FIG. 3 shows the hardware configuration of the control unit 80. Referring to FIG. 3, the control unit 80 receives an input/output interface (hereinafter referred to as “I/F”) 100 that receives the CT sensor currents from the CT sensors 70 and 72 and performs AD conversion, and an input/output I/F 100. , A bus 102 serving as a path for transmitting and receiving signals between the components of the control unit 80, a CPU (Central Processing Unit) 104, a ROM (Read-Only Memory) 106, all of which are connected to the bus 102. The input/output I/F 108, the timer 110, the RAM (Random Access Memory) 112, and the input/output I/F 114 are connected to the input/output I/F 114, and the error code and the like are displayed in two-digit numbers under the control of the CPU 104. 7 segment display 116. The timer 110 is used to measure the time length of various sections described below. The 7-segment display 116 is also used to display error information when a sensor abnormality or the like is detected. The processing described below is realized by a program executed by the CPU 104 of the control unit 80. The programs are stored in, for example, the ROM 106, loaded into the RAM 112 at the time of execution, and executed by the CPU 104. These programs may be stored not only in the ROM 106 but also in a magnetic medium such as an optical storage medium or a hard disk, and may be written in the ROM 106.

Of these, the input/output I/F 100 is for receiving the sensor currents from the CT sensors 70 and 72 shown in FIG. The input/output I/F 108 is for transmitting a control signal from the CPU 104 to the power supply unit 90. When the operation of the CT sensor 70 or the CT sensor 72 is determined to be abnormal, the input/output I/F 114 sends a control signal to the 7-segment display 116 so as to display a code indicating the content when the operation is determined to be abnormal. It is for giving or for giving to the DC-DC converter 92, the inverter 94, and the limiter 96 shown in FIG.

FIG. 4 shows a state in which the CT sensor 72 has fallen off the electric path W in the distributed power supply system 50. In this case, the output from the CT sensor 72 does not reflect the current flowing through the electric path W as shown in FIG. 5, and is not effective. In order to avoid such a state, a method assumed for detecting that the CT sensor 72 is in such a situation will be described below.

With reference to FIG. 6, the control unit 80 repeats the determination target sections 130, 132, and 134 for 5 seconds with respect to the output from the CT sensor 72, and determines whether the conditions described below are satisfied in each section. When the condition is not satisfied, the CT sensor 72 is normal, and when the condition is satisfied, the CT sensor 72 is abnormal.

As a condition therefor, it is conceivable that the control unit 80 uses the effective value of the sensor current from the CT sensors 70 and 72 and the current frequency. Specifically, the operation of the CT sensor is determined to be abnormal when the following conditions are satisfied. That is, the condition that the effective value of the CT sensor current is less than the threshold value and the frequency of the CT sensor current is outside the predetermined range continues for a predetermined detection time period (this is set to be shorter than 5 seconds). When it does, it is determined that the operation of the CT sensor 72 is abnormal. Since the threshold value of the effective current value and the predetermined range of the current frequency at this time depend on the specifications of the system to which the CT sensor is connected, it is necessary to determine each time. The current frequency can be calculated by measuring the time between the zero cross points of the current and obtaining the reciprocal thereof.

However, if an attempt is made to determine an abnormality in the CT sensor under such conditions, an erroneous determination may occur. When an abnormality such as a drop occurs in the CT sensor, the output of the CT sensor is only reactive current. Therefore, it is unlikely that the effective current value will increase. However, when the current frequency is calculated by the reciprocal of the time between the zero cross points as described above, the result may happen to fall within the predetermined range described above. In such a case, it is erroneously determined that the CT sensor cannot be detected even though it is missing.

For example, referring to FIG. 5, when the CT sensor 72 is detached from the electric path W, the output current of the CT sensor 72 is not completely flat and has a random value. Then, as shown in FIG. 5, when the current frequency is calculated by the reciprocal of the time between the zero-cross points, it becomes, for example, 150 Hz, 80 Hz, or 60 Hz. Therefore, if this value happens to fall within a predetermined range, it will be erroneously determined that the CT sensor 72 has not fallen, although it has fallen.

In the first embodiment of the present invention, such a false detection is avoided by using the method described below.

Referring to FIG. 7, control unit 80 repeatedly performs the following processing at a predetermined interval (for example, every 5 seconds). That is, each of the 5 second determination target sections 150, 152, 154, etc. is divided into shorter basic blocks (for example, 0.1 second intervals). In FIG. 7, each of the determination target sections 150, 152, 154 and the like is vertically divided into strips, but each of these strips represents a basic block. For each of the basic blocks, when the condition that the effective value of the CT sensor current is less than the threshold value and the frequency of the CT sensor current is out of the predetermined range continues for 0.1 seconds, the CT sensor The operation of 72 is determined to be abnormal. If not, the basic block is determined to be normal. This is repeated for 5 seconds. There are 50 basic blocks in the judgment target section of 5 seconds. Of these basic blocks, if the number of basic blocks determined to be abnormal (for example, basic blocks 160, 162, 164, 166, and 168 hatched in FIG. 7) is more than half, that is, the basic blocks of the determination target section If the ratio of the basic blocks determined to be abnormal is 50% or more, it is determined that a sensor abnormality has occurred in the CT sensor 72 in that section, and processing is performed when the abnormality occurs. When the number of basic blocks determined to be abnormal in the determination target section is less than half, the section is determined to be normal, and it is determined that no sensor abnormality has occurred in the CT sensor 72. In this case, even if the current frequency happens to fall within the normal range, it is usually impossible for the number of such basic blocks to be more than half in the determination target section. As a result, it is possible to reduce the possibility that an erroneous determination will occur in the abnormality detection of the CT sensor as described above.

In the example shown in FIG. 7, the number of abnormal basic blocks in the determination target section 150 is 0. Therefore, the CT sensor is determined to be normal in the determination target section 150. In the determination target section 152, the number of abnormal basic blocks is only the basic blocks 160 and 162. Therefore, the CT sensor is determined to be normal even in the determination target section 152. On the other hand, in the determination target section 154, the abnormal basic blocks are the basic block 164, the plurality of basic blocks 166, and the basic block 168, and the number of these is half the number of basic blocks in the determination target section 154. It is over. In this case, it is determined that the CT sensor has an abnormality in the determination target section 154.

<Example of determination of threshold value for effective current value>
When F is the system voltage frequency (Hz), C is the system side capacitor capacity (F) of the distributed power supply unit, and V is the system voltage effective value (V), the reactive current (A) measured by the CT sensor is the following formula. Is calculated by

Reactive current = 2πFCV
In the case of single-phase three-wire system AC200V·50Hz and system side capacitor capacity=6.6 μF, reactive current=0.42A. The threshold value is 0.105 A with a margin of 75% of the value of the reactive current. That is, if the effective current value of the output of the CT sensor is larger than this threshold value, it is determined to be normal.

<Example of determining the frequency range of CT sensor current>
In this embodiment, ±5% (not including both ends) of the voltage frequency of the system is set as a normal range, and the other ranges are set as abnormal. That is, when the system voltage is 50 Hz, the CT sensor current frequency is 47.5 Hz or less or 52.5 Hz or more and is outside the range. When the system voltage is 60 Hz, the CT sensor current frequency is 57 Hz or less or 63 Hz or more and is out of the range.

Of course, this is an example, and both ends of the range may be included in the normal range. Further, since these values depend on the specifications of the system to which the CT sensor is connected, most of the values are other than the above values.

<Example of determination of judgment target section and basic block time length>
The measurement time of the basic block must be at least a time longer than the system voltage cycle. In this embodiment, as an example, 0.1 second is set as the measurement time limit of the basic block. Further, the judgment target section needs to have a length that includes a large number of basic blocks, and naturally, a time longer than the time of the basic block is selected. For example, the determination target section is longer than the measurement time period of the basic block, and it is desirable to be, for example, 5 times or more. As described above, if the measurement time limit of the basic block is 0.1 seconds, it is desirable that the determination target section is 0.5 seconds or more. In this embodiment, the determination target section is set to 5 seconds (50 times the measurement time period of the basic block) as described above. The length may be longer than this, but if it is too long, detection of the CT sensor falling off will be delayed, so about 5 seconds is appropriate. Even at the longest, it is desirable that the length of the determination target section is about 100 times the measurement time period of the basic block.

<Program structure>
In the present embodiment, the above-described abnormality determination of the CT sensor is realized by the CPU 104 of the control unit 80 executing a program having a control structure as described below. It should be noted that the following description is for the case where only the abnormality detection regarding the CT sensor 72 is performed. The CT sensor 70 can detect an abnormality independently of the CT sensor 72 by executing the same program.

Referring to FIG. 8, this program calculates the effective current value and the current frequency based on the step 180 of measuring the output current value of the CT sensor only a plurality of times at a predetermined sampling frequency and the sample measured in step 180. And a step 184 of branching the flow of control according to whether or not the effective current value calculated in step 182 is less than or equal to a certain value.

The program further determines, when the determination in step 184 is affirmative, whether or not the difference between the current frequency calculated in step 182 and the predetermined reference frequency is a certain value or more, and the control flow is determined according to the determination result. Step 186 for branching to step 186 and Step 188 for marking the basic block to be processed as an abnormal block when the determination in Step 186 is affirmative, and the processing target when the determination in Step 184 or Step 186 is negative. Step 190 of marking a basic block that has become a normal block.

The program further determines after step 188 and after step 190 whether or not the determination target section has elapsed, that is, whether 5 seconds have elapsed from the start of the processing of the determination target section, Step 192 of branching the flow of control according to the above, Step 194 of calculating the ratio of abnormal blocks in the judgment target section when the judgment of Step 192 is affirmative, and the ratio calculated in Step 194 is 50%. Whether or not the above is determined, and step 196 that branches the control flow according to the determination, and when the determination in step 196 is affirmative, it is determined that an abnormality has occurred in the CT sensor, indicating that an abnormality has occurred. A step 200 of setting a flag and terminating the process, and a step of deciding that the determination target section is normal as a whole when the determination in step 196 is negative, clearing the number of abnormal blocks and the like and terminating the process. 198 and. When the determination in step 192 is negative, the control is returned to step 180.

By executing the above processing, it is possible to make a tentative determination that an abnormality has occurred in the CT sensor. However, even if such a determination is made, if a certain condition is satisfied between the output of the distributed power supply unit 68 and the magnitude of the load, it is possible to erroneously determine that an abnormality has occurred even though the CT sensor has no abnormality. There is a nature. The erroneous determination will be described below.

Referring to FIG. 9, in distributed power supply system 50, load 230 of 1000 W is connected between electric line U and neutral line O, and load 232 of 500 W is connected between electric line W and neutral line O. Think if you have been. The total load is 1500W. In this example, it is assumed that in this case, the distributed power supply unit 68 is designed to supply 1000 W to the load. Since the output of the distributed power supply unit 68 cannot be controlled for each phase, the distributed power supply unit 68 supplies 500 W to the electric path U and 500 W to the electric path W. The load 230 of the electric path U is 1000 W, whereas the electric power supplied from the distributed power supply unit 68 to the electric path U is 500 W, which is insufficient by 500 W. Therefore, the shortage of 500 W will be purchased from the grid 60.

On the other hand, in the electric path W, the load 232 is 500 W, whereas the distributed power supply unit 68 supplies 500 W. As a result, the power purchased from the grid 60 becomes 0W. In this case, the condition for the CT sensor 72 to detect the sensor abnormality is satisfied, and it is erroneously determined that the CT sensor 72 has an abnormality even though the CT sensor 72 has no abnormality. I will end up. It is also necessary to prevent such a determination error.

Therefore, in this embodiment, in addition to the abnormality detection first stage determination process shown in FIG. 8, a second stage determination for preventing an error in the determination when the condition shown in FIG. 9 is established. Perform processing. The determination process of the second stage will be described below.

Referring to FIG. 10, when the situation as shown in FIG. 9 occurs, the output of distributed power supply unit 68 is changed. Although the output of the distributed power supply unit 68 may be increased or decreased, in this embodiment, if the output of the distributed power supply unit 68 is increased carelessly, there is a risk that reverse power flow to the grid 60 will occur. It is not preferable because it exists. Therefore, for example, the output of the distributed power supply unit 68 is reduced, and here, it is reduced by 100W. Then, theoretically, regarding the electric path U, 450 W is supplied from the distributed power supply unit 68 to the load 230, and 550 W for the shortage is purchased from the grid 60. On the other hand, regarding the electric path W, 450 W is supplied from the distributed power supply unit 68 to the load 232, and 50 W is insufficient. Therefore, power purchase of 50 W from the grid 60 occurs. In this case, if the CT sensor 72 is normal, the output of the CT sensor 72 should increase according to the current corresponding to 50 W. If no increase is found, it is determined that the CT sensor 72 has an abnormality. it can. FIG. 11 is a flowchart showing the control structure of the program for realizing the second-stage determination processing based on such an idea. Here, in order to reduce the output of the distributed power supply unit 68, a method of limiting the output of the distributed power supply unit 68 to a predetermined value by the limiter 96 shown in FIG. 2 is used in this embodiment.

Referring to FIG. 11, this program includes a step 250 of performing a first-stage determination process (FIG. 8) to determine whether or not an abnormality is detected, and repeating this processing until the abnormality is detected. The processing performed in step 250 is the same as that shown in FIG. 8, but if the processing is ended once when step 198 ends, step 250 in FIG. 11 can be realized as it is by the processing in FIG.

This program further includes the step 252 of limiting the maximum output of the distributed power supply unit 68 to 900 W by the limiter 96 shown in FIG. 2 when an abnormality is detected in the determination of step 250, and the output limitation by step 252. , Step 254 that waits for a predetermined time (for example, 0.1 seconds) until the output of the distributed power supply unit 68 stabilizes, and after the waiting in step 254 ends, the second stage abnormality detection processing is executed. 256 to branch the flow of control according to the result. In step 256, if the effective current value of the output of the CT sensor 72 is less than or equal to the threshold value, it is determined that the CT sensor 72 has an abnormality (determination=affirmative). If the condition is not satisfied, it is temporarily determined that no abnormality has occurred (determination = negative).

This program further includes a step 268 for determining whether the current of the electric circuit W to which the CT sensor 72 is attached is 50 W or more when the determination at step 256 is negative, and a positive determination for step 268. The output limit by the limiter 96 shown in FIG. 2 is returned to 1000 W, the control is returned to step 250, and the abnormality determination process of the CT sensor 72 is repeated from the beginning step 270.

This program further includes a step 258 of stopping the operation of the distributed power supply unit 68 when the determination of step 256 is affirmative, and a CT sensor drop monitoring by means completely different from the CT sensor abnormality detection processing described above. As a result of step 260 performing processing, it is determined whether or not the CT sensor 72 is normal as a result of step 260, and step 262 in which control is branched according to the determination result, and it is determined that the CT sensor is not normal in step 262. In response, in response to the fact that the CT sensor 72 is determined to be normal in step 264, which notifies that a sensor abnormality has occurred on the 7-segment display 116 or the like shown in FIG. , Step 266 of returning the output limit by the limiter 96 of FIG. 2 to 1000 W and returning the control to step 250.

In this second-stage determination processing, the output of the distributed power supply unit 68 is once reduced in step 252, and as a result, if the effective current value of the output current of the CT sensor 72 is less than or equal to the threshold value, the CT sensor 72 determines that It is determined to be abnormal at this point. However, if the effective current value of the output current of the CT sensor 72 is larger than the threshold value and the electric power of the electric path W represented by the value is 50 W or more, the CT sensor 72 is determined to be normal in step 268. Step 256 and step 268 are repeatedly executed until either of these two determination conditions is satisfied, and if either condition is satisfied, the CT sensor 72 is determined to be abnormal or normal.

<Operation>
In the distributed power supply unit 68 of the distributed power supply system 50 described above, the control unit 80 operates as follows. It should be noted that the following description relates only to the CT sensor 72, but the same processing is executed in parallel for the CT sensor 70 as well.

Referring to FIGS. 1 and 2, the CT sensors 70 and 72 input the CT sensor currents corresponding to the currents flowing in the electric path U and the electric path W, respectively, to the control unit 80. The control unit 80 normally consumes each load so that the purchased power does not exceed the target value and the output power from the distributed power supply unit 68 corresponds to this value and a preset target purchased power value. The DC-DC converter 92, the inverter 94, and the limiter 96 are adjusted so as to cover the shortage of electric power and prevent reverse power flow.

-First stage judgment-
Referring to FIG. 11, control unit 80 executes the process of step 250 when the power supply of distributed power supply unit 68 is turned on. Here, the process of step 250 is the same as that shown in FIG. 8, and differs from that shown in FIG. 8 only in that the execution is ended after step 198.

Here, first, the following processing is repeated for each basic block in the determination target section. Referring to FIG. 8, in step 180, the output current value of the CT sensor 72 is measured at a predetermined sampling frequency for the target basic block. Then, in step 182, the effective current value and the current frequency are calculated based on the sample measured in step 180. In the following step 184, if the effective current value calculated in step 182 is less than or equal to a fixed value, the control proceeds to step 186, and if not, to step 190.

When the determination in step 184 is affirmative, in step 186, it is determined whether or not the difference between the current frequency calculated in step 182 and the predetermined reference frequency is a certain value or more. If the determination is positive, control proceeds to step 188, otherwise control proceeds to step 190.

When the determination in step 184 is negative and the determination in step 186 is negative, the CT sensor 72 is considered to be normal in the basic block to be processed. Therefore, in step 190, the basic block to be processed is marked as normal. On the other hand, when the determinations at both step 184 and step 186 are affirmative, the target basic block is determined to be abnormal. Therefore, in step 188, the target basic block is marked as abnormal.

In any case, it is determined in step 192 whether the determination target section being processed has passed, that is, whether 5 seconds have passed since the processing of the determination target section was started. When the determination in step 192 is affirmative, the control proceeds to step 194, and the ratio of abnormal blocks in the determination target section is calculated. Whether or not the ratio calculated in step 194 is 50% or more is determined in step 196. If the determination is affirmative, it is determined in step 200 that an abnormality has occurred in this determination target section, and a flag indicating that an abnormality has occurred. Is set, and this processing ends.

When the determination in step 196 is negative, it is determined that the determination target section is normal as a whole, the number of abnormal blocks is cleared in step 198, the flag is reset, and this processing ends.

If the determination in step 192 is negative, it means that the processing for all basic blocks in the determination target section has not been completed. Therefore, the control returns to step 180, and the processing for the next basic block in the same determination target section is started.

-Second stage judgment-
Referring to FIG. 11, in step 250, it can be determined whether or not an abnormality is detected in the first-stage determination processing depending on whether or not the flag is set. If the flag is reset, it means that no abnormality has been detected, the control returns to step 250, and the processing of FIG. 11 is executed for the next determination target section. If the flag is set, control proceeds to step 252.

From step 252 onward, the determination process of the second stage is executed. That is, in step 252, the output limit value by the limiter 96 shown in FIG. 2 is reduced to 900W. Wait for 0.1 seconds until the output of the distributed power supply unit 68 stabilizes in step 254. In step 256, the second stage abnormality detection processing is performed. That is, in step 256, the output of the CT sensor 72 is sampled, and if the effective current value is equal to or less than the threshold value, it is determined that an abnormality has occurred in the CT sensor 72 (determination=affirmative). In this case, control proceeds to step 258. If the condition is not satisfied, it is temporarily determined that no abnormality has occurred, and the control proceeds to step 268.

When the determination in step 256 is negative, in step 268, it is determined whether or not the electric current of the electric circuit W to which the CT sensor 72 is attached is 50 W or more. When the determination in step 268 is affirmative, the CT sensor 72 is determined to be normal, and after the output limit by the limiter 96 shown in FIG. 2 is returned to 1000 W in step 270, the control is returned to step 250 to determine the abnormality of the CT sensor 72. The process is restarted from the beginning.

When the determination in step 256 is affirmative, the operation of the distributed power supply unit 68 is stopped in step 258. Then, in step 260, a CT sensor drop monitoring process is performed by means completely different from the CT sensor abnormality detection process of this embodiment. In step 262, as a result of step 260, it is determined whether or not the CT sensor 72 is normal. If it is determined that the CT sensor 72 is not normal, in step 264 the sensor abnormality is notified by the 7-segment display 116 or the like shown in FIG. 3 and the process is terminated. If the CT sensor 72 is determined to be normal in step 262, the output limit by the limiter 96 of FIG. 2 is returned to 1000 W, and control is returned to step 250. When the determination results of step 256 and step 268 are both negative, these two steps are repeatedly executed until the determination result of either step becomes affirmative.

As described above, according to this embodiment, the determination target section is divided into shorter basic blocks, and it is determined whether or not an abnormality has occurred in the CT sensor 72 for each basic block. Each block is marked as abnormal or normal, and when the determination target section ends, it is determined whether or not the ratio of abnormal blocks in the determination target section is a threshold value (for example, 50%) or more. If the ratio of abnormal blocks is greater than or equal to the threshold value, it is determined that the CT sensor 72 has an abnormality in the determination target section. Otherwise, it is determined that the determination target section is normal. By such a determination, it is possible to reduce the risk that the current frequency of the output current of the CT sensor 72 happens to fall within the normal range, and therefore the CT sensor 72 is determined to be normal despite the abnormality.

Further, when it is determined that the abnormality has occurred in the above-described first-stage determination, the output of the distributed power supply unit 68 is further changed (only the output can be reduced depending on restrictions), and as a result, the target It is checked whether or not the effective value of the current flowing in the electric circuit to which the CT sensor is attached changes. If the effective value increases, the CT sensor is considered to be normal. If the effective value does not increase, the CT sensor is determined to be abnormal. As a result, it is possible to avoid the problem that the output does not appear in the CT sensor because the load capacitance and the output of the distributed power supply unit 68 happen to coincide with each other, and the CT sensor is erroneously detected when an abnormality occurs.

It should be noted that the CT dropout monitoring process executed in step 260 of FIG. 11 may be any process as long as the dropout of CT can be reliably determined, for example, a process of manually confirming the dropout. Alternatively, a method of detecting the dropout of CT may be performed by a method completely different from this embodiment. For example, the abnormality determination of the CT sensor may be performed based on the change in power accompanying the forced charging of the distributed power supply unit 68 to the power supply unit 90.

In the above-described embodiment, no special hardware is required to detect a defect such as the CT sensor falling off or the CT sensor breaking. Therefore, it is possible to prevent the costs of the control unit 80 and the distributed power supply unit 68 from increasing.

[Second Embodiment]
In the first embodiment described above, when a tentative determination result that an abnormality has occurred is obtained in the abnormality detection of the first stage, as shown in step 252 of FIG. 11, the limit of the output power by the limiter 96 of FIG. 2 is limited. The price has been lowered. By such processing, the second stage abnormality detection can be performed. However, the invention is not limited to such an embodiment. For example, in the case of a system connected to system power like the distributed power supply unit 68, the power purchase target power value may be set. The distributed power supply unit 68 has a storage device that stores this value, and controls the output from the distributed power supply unit 68 so that the purchased power from the grid during normal operation does not exceed this target power value. There is.

That is, the distributed power supply unit 68 has a function of controlling the output of the distributed power supply unit 68 according to the target purchase power value. Therefore, instead of controlling the limiter 96 to limit the output of the distributed power supply unit 68 as in the first embodiment, it is conceivable to increase the target purchased power value of the distributed power supply unit 68. When the target purchased power value is increased, the output of the distributed power supply unit 68 decreases as a result of the above control. As a result, the purchased electric power flowing through the electric lines W and U increases. Therefore, it is possible to obtain the same effect as limiting the output of the distributed power supply unit 68 by using the limiter 96 as in the first embodiment.

FIG. 12 is a flowchart showing the control structure of a program executed by the control unit of the distributed power supply unit according to the second embodiment. The flowchart shown in FIG. 12 differs from the flowchart of the program executed in the first embodiment shown in FIG. 11 in that steps 300, 302, 304 and 306 are replaced with steps 252, 266 and 270, respectively. It is a point that includes.

In step 300, instead of limiting the output by the limiter 96 of FIG. 2, the target purchase power value stored in the distributed power supply unit is rewritten to a larger value (for example, 50 W→150 W). Since it is necessary to return the target purchased power value to the value before rewriting after that, it is necessary to save the value before rewriting. As a result of this processing, in step 254, by waiting for the same time as in the first embodiment, the output of the distributed power supply unit stabilizes at a reduced value. The rest is the same as in the first embodiment shown in FIG.

However, instead of restoring the output limitation by the limiter 96 in Steps 264 and 266 of FIG. 11, in the second embodiment, in Steps 302 and 304, before the rewriting, which is saved in Step 300, before rewriting. The target purchased power value is written back into the storage area of the target purchased power value of the distributed power supply unit. As a result, even in the distributed power supply unit including the distributed power supply unit according to the second embodiment, the same effect as that of the distributed power supply system 50 according to the first embodiment can be obtained.

In both the first and second embodiments, the control unit 80 digitally controls the distributed power supply system 50. However, the present invention is not limited to such digital control. The present invention can also be realized by analog circuit elements that realize the same functions as those of digital control technology.

In the above-described embodiment, the second stage determination of the sensor abnormality is performed every time the second determination target period ends. However, the invention is not limited to such an embodiment. If the determination result of the first stage for the predetermined number of basic blocks immediately before is stored, the immediately preceding predetermined number (second period) is determined each time the determination result of the first stage is completed, not in the second determination target period. The second-stage determination may be performed for the first-stage determination number having the same length as the determination target period of. In this case, the second-stage determination is performed not for each second determination target period but for each period in which the first determination is performed, which increases the required calculation amount. However, there is an effect that when an actual sensor abnormality occurs, it can be immediately detected without waiting for the second determination target period.

Further, in the above-described embodiment, as shown in step 250 of FIGS. 11 and 12, the second stage abnormality detection is performed after the first stage abnormality is detected. However, the present invention is not limited to such an embodiment. The processing of step 250 may be omitted and only the second stage abnormality detection may be performed. In that case, the programs shown in FIG. 11 and FIG. 12 may make the output of the distributed power supply unit unstable if they are left as they are. Therefore, it is desirable to make the determination at regular intervals. ..

The embodiment disclosed this time is merely an example, and the present invention is not limited to the embodiment described above. The scope of the present invention is shown by each claim of the claims after considering the description of the detailed description of the invention, and the meanings equivalent to the wording described therein and all modifications within the scope are Including.

50 distributed power supply system 60 system 62, 64, 66, 230, 232 load 68 distributed power supply unit 70, 72 CT sensor 80 controller 90 power supply unit 92 DC-DC converter 94 inverter 96 limiter 100, 108, 114 input/output I /F
102 bus 104 CPU
106 ROIM
110 timer 112 RAM
116 7-segment display 130, 132, 134, 150, 152, 154 Judgment target sections 180, 182, 184, 186, 188, 190, 192, 194, 196, 198, 200, 250, 252, 254, 256, 258 260, 262, 264, 268, 270, 300, 302, 304 Steps 160, 162, 164, 166, 168 Basic blocks

Claims (15)

A sensor abnormality detection device for detecting an abnormality of a sensor mounted on an electric circuit through which an alternating current flows,
A measuring circuit for measuring the output of the sensor,
A first determination circuit that makes a determination regarding a sensor abnormality of the sensor for each of the first measurement times based on an output of the measurement circuit during a first measurement time that is at least one cycle of the alternating current. ,
A sensor abnormality detection including a second determination circuit that determines the presence or absence of the sensor abnormality based on a determination result by the first determination circuit during a second measurement time that is longer than the first measurement time. apparatus. The sensor abnormality detection device according to claim 1, wherein the measurement circuit includes a circuit that periodically measures an effective value and a frequency of a current output from the sensor. The first determination circuit is configured such that a difference between a current frequency of the current output from the circuit to be measured and a reference frequency during the first measurement time is a certain value or more, and the output from the circuit to be measured. A third step of performing the determination during the first measurement time in response to whether or not a condition that an effective value of the current during the first measurement time is equal to or less than a constant value is satisfied. The sensor abnormality detecting device according to claim 2, further comprising: The second determination circuit determines whether or not the determination by the third determination circuit for each of the first measurement times occupies a predetermined threshold value or more within the second measurement time. The sensor abnormality detection device according to claim 3, further comprising a circuit for determining abnormality of the sensor. The second determination circuit is
A storage circuit that stores the latest determination result of the first determination circuit during the second measurement time;
Every time the first measurement time elapses, whether or not the ratio of the determination result indicating that the sensor is abnormal among the determination results stored in the storage circuit is equal to or more than a predetermined threshold value is determined. The sensor abnormality detection device according to claim 1, further comprising an abnormality determination circuit that determines an abnormality of the sensor. The second determination circuit is
A storage circuit that stores the latest determination result of the first determination circuit during the second measurement time;
Depending on whether or not the ratio of the determination result indicating that the sensor is abnormal among the determination results stored in the storage circuit is equal to or greater than a predetermined threshold value every time the second measurement time elapses. The sensor abnormality detection device according to claim 1, further comprising an abnormality determination circuit that determines an abnormality of the sensor. The sensor abnormality detection device according to any one of claims 4 to 6, wherein the predetermined threshold value is 50% or more and 100% or less. A distributed power supply system connected to a single-phase three-wire type AC electric circuit, wherein the single-phase three-wire type AC electric circuit includes a neutral wire, a first electric line and a second electric line, A sensor that outputs a current according to the magnitude of the current flowing through the first electric line is attached to the first electric line,
DC power supply,
A power conversion device provided between the DC power supply and the AC electric path,
Based on the output of the sensor, a sensor abnormality detection device for determining whether a sensor abnormality has occurred in the sensor,
When the sensor abnormality detection device does not detect the occurrence of a sensor abnormality, the power conversion device is controlled based on the output of the sensor, and power conversion is performed between the DC power supply and the AC power on the AC power path. A control circuit for performing
In response to the sensor abnormality detection device detects the occurrence of a sensor abnormality, including an abnormality processing circuit for performing the process at the time of sensor abnormality,
The sensor abnormality detection device,
A measurement circuit that periodically measures the effective value or current frequency of the current output by the sensor,
A first determination circuit that makes a determination regarding a sensor abnormality of the sensor for each of the first measurement times based on an output of the measurement circuit during a first measurement time that is at least one cycle of the alternating current. ,
The presence or absence of the sensor abnormality is determined based on the determination result by the first determination circuit during the second measurement time longer than the first measurement time, and the determination result is sent to the control circuit and the abnormality processing circuit. A distributed power supply system including a second determination circuit for outputting. The sensor abnormality detection device further includes
An output control device that controls the power conversion device to change the output of the power conversion device by a predetermined amount in response to the determination by the second determination circuit that a sensor abnormality has occurred,
In response to a change in the output by the output control device, a third judgment circuit for judging whether or not a sensor abnormality really occurs in the sensor depending on whether or not the output of the measurement circuit changes. 9. The distributed power system of claim 8 including. The output control device controls the power conversion device to decrease the output of the power conversion device by a predetermined amount in response to the determination by the second determination circuit that a sensor abnormality has occurred. Including the device,
The third determination circuit is responsive to a change in the output by the output limiting device to determine whether the output of the measuring circuit increases by an amount corresponding to the decrease in the output by the output limiting device. The distributed power supply system according to claim 9, further comprising a fourth determination circuit for determining whether or not the sensor abnormality has truly occurred. The distributed power supply system according to claim 10, wherein the output limiting device includes a limiter connected between the power conversion device and the alternating current circuit. 11. The distributed power supply system according to claim 10, wherein the output limiting device includes a target value setting device that reduces the output of the power conversion device by increasing the power purchase target value by the power conversion device by a predetermined amount. .. A sensor abnormality detection method for detecting an abnormality of a sensor mounted on an electric circuit through which an alternating current flows,
Periodically measuring the effective value or current frequency of the current output by the sensor,
A first determination step of performing a determination regarding a sensor abnormality of the sensor for each of the first measurement times based on the output in the measuring step during a first measurement time that is at least one cycle of the alternating current or more. When,
And a second step of determining the presence or absence of the sensor abnormality based on the determination result of the first determination step during a second measurement time longer than the first measurement time. .. A sensor abnormality detection method for detecting abnormality of a sensor used together with a distributed power supply system connected to a single-phase three-wire type AC electric circuit, wherein the single-phase three-wire type AC electric circuit is a neutral wire. , A first electric path and a second electric path, wherein the sensor is attached to the first electric path, the sensor outputting a current according to a magnitude of a current flowing through the first electric path.
The distributed power system,
DC power supply,
A power conversion device provided between the DC power supply and the AC electric path,
Based on the output of the sensor, a sensor abnormality detection device for determining whether a sensor abnormality has occurred in the sensor,
The power conversion device is controlled based on the output of the sensor, and when the sensor abnormality detection device does not detect the occurrence of a sensor abnormality, the power conversion is performed between the DC power supply and the AC power on the AC power line. A control circuit for performing
In response to the sensor abnormality detection device detects the occurrence of a sensor abnormality, including an abnormality processing circuit for performing the process at the time of sensor abnormality,
The method is
Periodically measuring the effective value or current frequency of the current output by the sensor,
A first determination step of performing a determination regarding a sensor abnormality of the sensor for each of the first measurement times based on the output in the measuring step during a first measurement time that is at least one cycle of the alternating current or more. When,
Based on the determination result of the first determination step during the second measurement time longer than the first measurement time, the presence or absence of the sensor abnormality is determined and the determination result is determined by the control circuit and the abnormality processing circuit. And a second determination step of outputting to the sensor abnormality detection method. The sensor abnormality detection method further controls the power conversion device to change the output of the power conversion device by a predetermined amount in response to the determination that the sensor abnormality has occurred in the second determination step. Steps,
A third determination step for determining whether or not a sensor abnormality is truly occurring in the sensor depending on whether or not the measurement result in the measuring step changes in response to the change in the output. Item 14. The sensor abnormality detection method according to Item 14.

Images