JP4948316B2 - limiter - Google Patents

Description

  The present invention relates to a limiter that provides a cutoff set value in accordance with a tidal current direction.

  2. Description of the Related Art Conventionally, there is known a limiter that is disposed on the primary side of a main circuit breaker in a residential switchboard and that cuts off power reception when a current value exceeds a certain value. This limiter is installed by an electric power company based on an electricity bill, and prevents the use of more than contracted power by cutting off the circuit when the power is used above a certain level. One configuration of a conventional limiter will be described with reference to FIG. Limiter 101 is arranged between commercial power supply 121 and main breaker 122. The limiter 101 includes a pair of contacts 104 and a tripping unit 105 that forcibly opens the contacts 104 in each phase of the electric circuit connected to the commercial power supply 121. The tripping unit 105 includes an electromagnet that is wound by a coil connected to the electric path of both voltage phases 131 in the opposite direction and operates by an electromagnetic force based on a vector sum of currents of both voltage phases 131. When the vector sum of the currents exceeds the rated current corresponding to the contract power, the electromagnet operates to interrupt the circuit.

  Further, in recent years, with the spread of private power generation devices such as solar power generation, when the generated power exceeds the power used, it is possible to sell power from ordinary households to power companies, and current flows in the power selling direction.

  A conventional limiter provided with such a private power generator will be described with reference to FIG. Here, one structure of the switchboard 100 provided with the limiter 101 is shown. The switchboard 100 includes a limiter 101 connected to an external commercial power supply 121, a main breaker 122 connected to the limiter 101 for turning on / off the main circuit, a branch breaker 123 for turning on / off a branch circuit branched from the main circuit, and a solar cell. Side linkage breaker 124. The solar cell side linkage breaker 124 is connected to the DC / AC converter 125, and is connected to the photovoltaic power generator 126 via the DC / AC converter 125. The electric power generated by the solar power generation device 126 is converted into alternating current by the DC / AC converter 125 and supplied to the branch circuit to which the load is connected via the solar cell side linkage breaker 124. When the power generated by the solar power generation device 126 is larger than the power used, the surplus power is sold to the power company via the limiter 101, but the current flowing in the power selling direction is not limited. Contracts are common and can be sold without restrictions.

  However, in the above-described conventional limiter, it is not possible to set individual cutoff setting values in the power purchase direction and the power sale direction, so that the circuit is interrupted by the current value regardless of the power flow direction. For this reason, when the current value on the power selling side exceeds the cut-off current value provided in the power purchase direction, there is a possibility that the cut-off current may be cut off although it is not necessary to cut off.

In addition, a current detection means is provided for each voltage phase to obtain a vector sum of currents, and when the vector sum is equal to or greater than the cutoff current and a delay time corresponding to the cutoff current is exceeded, a limiter that shuts off the circuit is provided. It is known (see, for example, Patent Document 1). However, the limiter disclosed in Patent Document 1 cannot have separate cutoff setting values in the power purchase direction and the power sale direction, and causes the same problem as the conventional limiter described above.
JP-A-8-227649

  The present invention has been made to solve the above-described conventional problems, and can arbitrarily set the cutoff setting value of the circuit cutoff operation at the time of selling power, and can prevent unnecessary circuit cutoff. The purpose is to provide a limiter.

  In order to achieve the above object, the invention according to claim 1 comprises current detection means for detecting a vector sum of voltage phase currents, wherein the current detection is performed in a limiter that shuts off a circuit when the vector sum exceeds a cutoff set value. The means detects a current value and a power flow direction of either a power purchase direction or a power sale direction with respect to a current supply source, and the cutoff setting value can be set separately according to the detected power flow direction. is there.

  According to a second aspect of the present invention, in the limiter according to the first aspect, the cutoff setting value is not set for the power selling direction.

  According to a third aspect of the present invention, in the limiter according to the first or second aspect, the current detection unit includes a voltage detection unit that detects the voltage of the voltage phase, and the voltage detected by the voltage detection unit The tidal direction is determined based on the phase difference from the vector sum.

  According to a fourth aspect of the present invention, in the limiter according to any one of the first to third aspects, the current detection means is detected by a current detection element that detects the voltage phase current, and the current detection element. And a determination processing unit for determining whether to perform circuit interruption based on the vector sum of the currents, the flow direction, and the interruption setting value.

  According to a fifth aspect of the present invention, in the limiter according to any one of the first to fourth aspects of the present invention, the limiter has a setting switch for setting the cutoff setting value in the power selling direction.

  A sixth aspect of the present invention is the limiter according to any one of the first to fifth aspects, further comprising a direction display unit that indicates a tidal current direction.

  A seventh aspect of the present invention is the limiter according to any one of the fourth to sixth aspects, wherein the determination processing unit includes an electric energy calculating unit, and displays the electric energy calculated by the electric energy calculating unit. Or communicate with the outside.

  According to the first aspect of the present invention, since the cutoff set value can be arbitrarily set according to the power flow direction of the power purchase direction and the power sale direction, it is possible to prevent the circuit from being interrupted unnecessarily during power sale. be able to.

  According to the second aspect of the present invention, since there is no cutoff setting value in the power selling direction, it is possible to prevent unnecessary cutoff during power selling.

  According to the third aspect of the present invention, the flow direction is determined based on the phase difference between the voltage and the current, so that the flow direction can be determined reliably.

  According to the invention of claim 4, since it is determined whether or not the trip signal is output by the determination processing section, the interruption condition can be set finely.

  According to the invention of claim 5, since the cutoff setting value in the power selling direction can be easily changed, one limiter is used for different power generation systems such as a solar power generation device and a gas power generation device that cannot sell power. can do.

  According to the sixth aspect of the present invention, since the tidal current direction can be seen and the execution of power sale can be understood, the effect of the power generation device can be easily recognized.

  According to the seventh aspect of the present invention, since the limiter calculates the amount of electric power by sharing the function of the current detection unit, the power calculation function can be added at a low cost.

(First embodiment)
A limiter according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of a limiter according to the present embodiment. The limiter 1 is connected to a commercial power source 21 by a single-phase three-wire system. The limiter 1 includes a main breaker 22, a branch breaker 23, a solar cell side linkage breaker 24, a DC / AC converter 25, and a solar power generation device. 26 are connected in order. The limiter 1 includes an electric circuit 3 composed of a voltage phase 31 and a neutral phase 32, a contact 4 provided on the electric circuit 3, a trip circuit 5 that trips the contact 4, a trip signal, and a trip circuit 5. And a current detection unit 6 (current detection means) for pulling the contact 4 off.

  The current detection unit 6 includes a current transformer (CURRENT TRANSFORMER, hereinafter abbreviated as CT) 61 that is arranged in the voltage phase 31 and detects a current, a power supply circuit 62 that obtains power from the output of CT61 (current detection element), and CT61. A current detection circuit 63 that detects a current value based on the output of the voltage, a voltage detection circuit 64 (voltage detection unit) that detects the voltage V of the voltage phase 31, and a determination processing unit 65 that outputs a trip signal. . The determination processing unit 65 calculates the vector sum of the currents I 1 and I 2 of the two voltage phases 31 from the current detected by the current detection circuit 63, the current vector sum, and the voltage V detected by the voltage detection circuit 64. Based on the above, it is determined whether the current flowing through the electric circuit 3 is in the power purchase direction or the power sale direction with respect to the current supply source. Then, the determination processing unit 65 determines that the vector sum of the currents exceeds the cutoff setting value determined according to the power flow direction, and the exceeded state becomes longer than the time delay characteristic time determined according to the cutoff setting value. Outputs a trip signal.

  In the limiter 1 configured as described above, a method of determining the tidal current direction performed by the determination processing unit 65 will be described with reference to FIG. FIG. 2 shows the waveform of the vector sum of the voltage and current of the voltage phase 31. The solid line A is the voltage, the dotted line B is the current in the power purchase direction, and the alternate long and short dash line C is the current in the power selling direction. Although the voltage and current of the commercial power supply have substantially the same phase, the power generated by the photovoltaic power generation device 26 is phase-controlled with respect to the voltage of the commercial power supply by the DC / AC converter 25 and has a power factor of 1. It is converted into an alternating current whose phase is opposite to that of the voltage. Therefore, the phase of the power purchase current and the voltage is substantially the same, but the phase of the power sale current and the voltage is reversed. Since the phase of the power purchase current and the power sale current is different, the flow direction can be determined from the current and voltage phase difference of the voltage phase 31 in which the power purchase current and the power sale current flow together. If the value of the electric power obtained by multiplying the voltage and the current is positive, the power is purchased. If the value is negative, the power is sold.

  FIG. 3 shows a flow of operation of the limiter 1. First, the determination processing unit 65 measures the currents I1 and I2 and the voltage V of the voltage phase 31. This measurement is performed, for example, every 1 ms (abbreviated as steps S1 and S1, and so on). The vector sum I is calculated from the currents I1 and I2, and the power P is calculated from the current value of the vector sum I and the voltage V (S2). Subsequently, the integration of the square value of the current value of the vector sum I and the integration of the power P are performed (S3). Then, S1 to S3 are repeated until the number of data reaches the number of data in a predetermined period such as one power cycle (S4). Subsequently, the flow direction is determined from the integrated value of the power P (S5). Subsequently, the cutoff set value corresponding to the power flow direction is compared with the current effective value of the vector sum I (S6). When the current effective value exceeds the cutoff setting value, the time over which it exceeds is counted (S7), and the time when the current effective value exceeds the cutoff setting value is compared with the time delay characteristic time (S8). . When the time delay characteristic time is exceeded, the determination processing unit 65 outputs a trip signal and trips the contact 4 (S9).

  As described above, according to the limiter 1 of the present embodiment, the cutoff setting value can be arbitrarily set according to the power flow direction and the power flow direction, so that the circuit is interrupted unnecessarily during power sale. Can be prevented. In addition, by not setting the cutoff setting value in the power sale direction, unnecessary cutoff at the time of selling power can be prevented. Further, since the flow direction is determined based on the phase difference between the voltage and current, the flow direction can be determined reliably. Further, since it is determined whether or not the trip signal is output by the determination processing unit 65, the blocking condition can be set in detail.

  In addition, when installed in a power generator that cannot sell power, such as gas power generation, by setting the cutoff setting value in the power selling direction to 0, it is possible to prevent power selling.

(Second Embodiment)
A limiter according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 4 shows the configuration of the limiter in this embodiment. In addition to the configuration of the limiter 1 of the first embodiment, the limiter 1 includes a setting switch 66 that sets a cutoff setting value in the power selling direction. The setting switch 66 is a dip switch, for example. With this setting switch 66, the cutoff setting value in the power selling direction can be easily set. For this reason, the single limiter 1 can be used for different power generation systems such as a solar power generation device and a gas power generation device.

(Third embodiment)
A limiter according to a third embodiment of the present invention will be described with reference to the drawings. FIG. 5 shows the structure of the limiter in this embodiment. In addition to the configuration of the limiter 1 of the first embodiment, the limiter 1 includes a direction display unit 67 that indicates a tidal current direction. The direction display part 67 is comprised by LED, for example, and the judgment process part 65 lights the direction display part 67 according to a tidal direction. Since the display of the tidal current direction by the direction display unit 67 indicates that power is being sold, the effect of the power generation apparatus can be easily recognized.

(Fourth embodiment)
A limiter according to a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 6 shows the structure of the limiter in this embodiment. The limiter 1 displays the amount of power. Unlike the limiter 1 of the first embodiment, the limiter 1 includes a voltage detection circuit 64 that detects the voltages of both voltage phases 31, and the determination processing unit 65 includes a current detected by the current detection circuit 63, a voltage A power amount calculation circuit 68 (power amount calculation unit) that calculates the amount of power based on the voltage detected by the detection circuit 64 is provided. The limiter 1 further includes a power amount display unit 69 that displays the calculated power amount, and a communication interface 70 that outputs the power amount to the outside. The determination processing unit 65 calculates the power amount and displays it on the power amount display unit 69, and communicates with the outside via the communication interface 70 and displays it.

  As described above, the limiter 1 calculates the amount of power by sharing the function of the current detection unit 6, so that the power calculation function can be added at low cost. Since the calculated amount of power is displayed on the limiter 1 and is output to the outside and displayed, it becomes easy to understand the usage state of the power. Also, a power information calculation function such as power factor and voltage abnormality can be easily added, and the power information can be communicated to the power company and used for management by the power company.

  In addition, this invention is not restricted to the structure of the said various embodiment, A various deformation | transformation is possible in the range which does not change the meaning of invention. For example, the tidal current direction may be detected by using a disk-type detection device used in a mechanical wattmeter and based on the rotation direction of the disk. In addition, the main breaker may be provided with a function of detecting the tidal current direction.

The block diagram of the limiter which concerns on the 1st Embodiment of this invention. The figure which shows the waveform of the voltage in the voltage phase of the limiter, and an electric current. The flowchart of the operation | movement of the limiter. The block diagram of the limiter which concerns on the 2nd Embodiment of this invention. The block diagram of the limiter which concerns on the 3rd Embodiment of this invention. The block diagram of the limiter which concerns on the 4th Embodiment of this invention. The block diagram of the conventional limiter. The block diagram of the switchboard which arrange | positioned the conventional limiter.

Explanation of symbols

1 Limiter 31 Voltage phase 6 Current detection unit (current detection means)
61 CT (current detection element)
64 Voltage detection circuit (voltage detection unit)
65 Judgment processing unit 66 Setting switch 67 Direction display unit 68 Electric energy calculation circuit (electric energy calculation unit)

Claims (7)

In a limiter that includes current detection means for detecting a vector sum of currents in a voltage phase, and that shuts down a circuit when the vector sum exceeds a cutoff setting value,
The current detection means detects a current value and a current flow direction of a power supply direction or a power sale direction with respect to a current supply source,
The limiter, wherein the cutoff set value can be set separately according to the detected flow direction.   The limiter according to claim 1, wherein the cutoff setting value is not set for a power selling direction. The current detection means includes a voltage detection unit that detects a voltage of the voltage phase,
3. The limiter according to claim 1, wherein the flow direction is determined based on a phase difference between the voltage detected by the voltage detection unit and the vector sum. 4. The current detection means includes
A current detection element for detecting a current of the voltage phase;
2. A determination processing unit that determines whether or not to perform circuit interruption based on a vector sum of currents detected by the current detection element, a flow direction, and the interruption setting value. The limiter according to any one of claims 3 to 4.   The limiter according to any one of claims 1 to 4, further comprising a setting switch for setting a cutoff setting value in the power selling direction.   The limiter according to any one of claims 1 to 5, further comprising a direction display unit that indicates a tidal current direction.   The said judgment process part is provided with an electric energy calculating part, The electric energy calculated by the said electric energy calculating part is displayed, or it communicates outside. The limiter described.

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