JP4542464B2 - Grid interconnection system - Google Patents

Description

  The present invention relates to a grid interconnection system that includes an overcurrent alarm device that outputs an overcurrent alarm when a current exceeding a set value flows, and that interconnects a single-phase three-wire commercial power source and an external power source. It is.

  In recent years, an overcurrent alarm device that outputs an overcurrent alarm before a current limiter or a main breaker trips due to an overcurrent is disposed in a residential distribution board. (For example, refer to Patent Document 1).

  This overcurrent alarm device has current transformers interposed between two voltage electrodes of a main breaker interposed in a wiring path from a single-phase three-wire commercial power source consisting of two voltage electrodes and one neutral electrode, An alarm is issued when the current value measured by each current transformer exceeds the set value.

There is a grid interconnection system that links a single-phase three-wire commercial power source and an external power source using a residential distribution board equipped with this overcurrent alarm.
JP 2002-10470 A

  Here, in a grid-connected system that links a single-phase three-wire commercial power source and an external power source, current flows from an external power source different from the single-phase three-wire commercial power source to each load. When the load connected between the voltage electrode and the neutral electrode is unbalanced, the current flowing through the neutral electrode may be larger than the current flowing through each voltage electrode. In this case, when the current flowing through the neutral electrode exceeds the rated current of the main breaker, there is a problem that the main breaker trips before the overcurrent alarm is output by the overcurrent alarm.

  The present invention has been made in view of the above-described reasons, and its object is to provide an overcurrent alarm before the main breaker trips even in an unbalanced state where the load balance is lost in the single-phase three-wire wiring path. It is to provide a grid interconnection system that reliably outputs power.

  The invention of claim 1 includes a current limiter having a primary side connected to a single-phase three-wire commercial power source composed of two voltage poles and one neutral pole, and each pole on the secondary side of the current limiter. A primary breaker connected to the primary side and a primary side connected to an external power source, and a secondary side connected to each pole on the secondary side of the main breaker to connect the external power source to a single-phase three-wire commercial power source Between the interconnection breaker, one or more branch breakers having a primary side connected to any voltage pole and neutral pole between the main breaker and the interconnection breaker, and between the current limiter and the branch breaker Two current transformers that measure the current flowing through each voltage electrode, and an overcurrent alarm that outputs an overcurrent alarm based on each current value measured by the two current transformers, Calculates the vector sum of instantaneous currents flowing through each voltage pole, and the vector sum is determined from the rated current of the current limiter. An overcurrent alarm is output when the value is above, and when the vector sum is less than the first reference value, the phase difference of the current flowing through each voltage electrode is measured, and the phase difference exceeds 90 degrees and is less than 270 degrees In this case, the sum of the effective currents flowing through the respective voltage electrodes is calculated, and an overcurrent alarm is output when the sum of the effective currents exceeds a second reference value determined from the rated current of the main breaker. To do.

  According to the present invention, the current limiter trips the overcurrent alarm at the time of load balancing by calculating whether the overcurrent alarm should be output by calculating the vector sum of the instantaneous current flowing through each voltage pole. Can output before. Further, when the phase difference of the current flowing through each voltage electrode exceeds 90 degrees and is 270 degrees or less, it is determined whether or not an overcurrent alarm should be output by calculating the sum of the effective currents flowing through each voltage electrode. Thus, even when the current flowing through the neutral pole is larger than the current flowing through each voltage pole as in the case of an unbalanced load balance, an overcurrent alarm can be output before the main breaker trips.

  The invention of claim 2 includes a main circuit breaker in which a primary side is connected to a single-phase three-wire commercial power source composed of two voltage electrodes and a neutral electrode, and a primary circuit is connected to an external power source. On the secondary side, connect the secondary side to each pole and connect the external power source to the single-phase three-wire commercial power supply, and any voltage pole between the main breaker and the connected breaker Measured with one or more branch breakers with primary side connected to the active pole, two current transformers that measure the current flowing through each voltage pole between the main breaker and the branch breaker, and two current transformers An overcurrent alarm that outputs an overcurrent alarm based on each of the current values, and the overcurrent alarm measures the phase difference of the current flowing through each voltage pole, and the phase difference exceeds 90 degrees and is 270. The sum of the effective currents that flow through each voltage electrode when the degree is less than or equal to the degree, and the sum of the effective currents flows through each voltage electrode An overcurrent alarm is output when the current is larger than the active current and the reference value determined from the rated current of the main breaker is exceeded, and when the phase difference is 90 degrees or less, or when the phase difference exceeds 270 degrees, Alternatively, when the phase difference exceeds 90 degrees and is 270 degrees or less, and the sum of the effective currents is equal to or less than the effective current flowing through one of the voltage electrodes, the larger effective current among the effective currents flowing through the voltage electrodes is An overcurrent alarm is output when the value exceeds a reference value determined from the rated current of the main breaker.

  According to the present invention, when the phase difference between the currents flowing through the voltage electrodes exceeds 90 degrees and is equal to or less than 270 degrees, whether or not an overcurrent alarm should be output by calculating the sum of the effective currents flowing through the voltage electrodes Thus, even when the current flowing through the neutral pole is larger than the current flowing through each voltage pole as in the unbalanced state where the load balance is lost, an overcurrent alarm can be output before the main breaker trips. In addition, by comparing the larger of the effective currents flowing through each voltage pole with the reference value to determine whether or not to output an overcurrent alarm, the overcurrent is detected before the main breaker trips even during load balancing. An alarm can be output.

  As described above, according to the present invention, it is possible to reliably output an overcurrent alarm before the main breaker trips even in the unbalanced state where the load balance is lost in the single-phase three-wire wiring path. effective.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
As shown in FIGS. 1 and 2, the grid interconnection system according to the present embodiment includes a single-phase three-wire commercial power supply AC including two voltage electrodes L1 and L2 and one neutral electrode N, and a built-in fuel. It is composed of a residential distribution board A that connects a fuel cell unit B that converts DC power generated by a battery into alternating current power and outputs it. In the residential distribution board A, a current limiter 1, A main breaker 2, an interconnection breaker 3, a plurality of branch breakers 4, two current transformers 5a and 5b, and an overcurrent alarm 6 are arranged. The fuel cell unit B also generates thermal energy when power is generated, and a hot water storage unit D (see FIG. 2) that generates hot water using this thermal energy is installed.

  First, the current limiter 1 connects the voltage poles L1 and L2 and the neutral pole N from the single-phase three-wire commercial power supply AC to the primary side, and connects the primary side of the main breaker 2 to the secondary side. The overcurrent detection element is provided only in the two voltage poles L1 and L2, and the vector sum of the currents I1 and I2 flowing through the voltage poles L1 and L2 is the rated current of the current limiter 1 (50 A in this embodiment). When it becomes above, it trips and cuts off the electric circuit.

  The main breaker 2 connects each pole from the secondary side of the current limiter 1 to the primary side, connects the interconnection breaker 3 and the branch breaker 4 to the secondary side, and an overcurrent detection element is connected to each pole. When the current (line current) flowing through each pole between the primary side and the secondary side becomes equal to or higher than the rated current (50 A in the present embodiment) of the main breaker 2, it trips and cuts off the electric circuit.

  The interconnection breaker 3 connects the output from the fuel cell unit B to the primary side, connects the secondary side to each pole on the secondary side of the main breaker 2, and supplies fuel to the single-phase three-wire commercial power supply AC. Battery unit B is linked.

  The branch breaker 4 is a secondary side of the main breaker 2 and the interconnection breaker 3, the voltage pole L1 or L2 and the neutral pole N are connected to the primary side, and the load Z is connected to the secondary side. When the current flowing through each pole between the secondary side and the secondary side becomes equal to or higher than the rated current of the branch breaker 4, it trips and interrupts the electric circuit. In the present embodiment, the load Z1 is connected between the voltage electrode L1 and the neutral electrode N, and the load Z2 is connected between the voltage electrode L2 and the neutral electrode N via the branch breaker 4.

  The current transformer 5a is inserted through the wiring line of the voltage pole L1 on the secondary side of the current limiter 1, and the current transformer 5b is inserted through the wiring line of the voltage electrode L2 on the secondary side of the current limiter 1. The currents I1 and I2 flowing through the voltage electrodes L1 and L2 are measured from the single-phase three-wire commercial power supply AC, and the instantaneous value is output.

  The overcurrent alarm device 6 outputs an overcurrent alarm based on the current measurement values from the current transformers 5a and 5b. As shown in FIG. 3, the circuit configuration includes a current detector 61, a current limiter presence / absence. A setting unit 62, a rated current setting unit 63 (sensitivity current setting unit), a display unit 64, an audio output unit 65, a control unit 66, and the like are provided.

  The current detector 61 includes a pair of IV converters 61a that convert the current signals detected by the current transformers 5a and 5b through which the voltage electrodes L1 and L2 are inserted into voltage signals, and the pair of IV converters 61a. The output signals of the pair of amplifiers 61b and the adder 61c for adding the output signals of the pair of amplifiers 61b are respectively added to the voltage poles L1 and L2 through the current transformers 5a and 5b. The instantaneous current is individually detected, and the adder 61c detects the vector sum of both instantaneous currents of the voltage electrodes L1 and L2.

  The current limiter presence / absence setting unit 62 is configured by a changeover switch or the like, and is for setting the presence / absence of the current limiter 1. In this embodiment, the current limiter is set to “present”.

  The rated current setting unit 63 is constituted by, for example, a volume switch, and is for setting the rated current of the current limiter 1 and the rated current of the main breaker 2. In the present embodiment, the rated current of the current limiter 1 is set to 50A, and the rated current of the main breaker 2 is set to 50A.

  The display unit 64 is configured by an LED or the like, and the audio output unit 65 is configured by an amplifier, a built-in speaker, or the like, and outputs an overcurrent alarm based on the lighting of the LED and the audio from the speaker according to an instruction from the control unit 66. is there.

  The control unit 66 is configured by an IC including a CPU, for example, and performs processing such as control of the overcurrent alarm device 6 in general. For example, the presence / absence of the current limiter 1 set by the current limiter presence / absence setting unit 62 A process of reading (loading) information, a process of reading the rated current values of the current limiter 1 and the main breaker 2 set by the rated current setting unit 63, and further setting conditions for the read presence information and rated current value Below, according to the detection result by the electric current detection part 61, processes, such as an overcurrent alarm output by the display part 64 and the audio | voice output part 65, are performed.

  Further, as shown in FIG. 2, the current measurement values of the current transformers 7a and 7b inserted through the wiring paths of the voltage electrodes L1 and L2 on the secondary side of the current limiter 1 are transmitted to the fuel cell unit B, The fuel cell unit B may perform backflow prevention control.

  Then, the single-phase three-wire commercial power supply AC and the fuel cell unit B are connected to supply power to the loads Z1 and Z2, and the operation at the time of equilibrium of the loads Z1 and Z2 will be described with reference to FIG. The operation at the time of unbalance will be described below with reference to FIG. Note that the electric power supply from the fuel cell unit B at both equilibrium and unbalance is as follows: fuel cell unit B → linkage breaker 3 → voltage electrode L1 → branch breaker 4, load Z1 → branch breaker 4, load Z2 → voltage electrode L2. → Current breaker 3 → Current 5A flows through path K1 of fuel cell unit B. At this time, no current flows through the neutral electrode of the fuel cell unit B.

  First, a path K2 shown in FIG. 4 shows a current path from the single-phase three-wire commercial power supply AC when the loads Z1 and Z2 are balanced, and the single-phase three-wire commercial power supply AC → voltage pole L1 → current limiter. 1 → main circuit breaker 2 → branch breaker 4, load Z1 → branch breaker 4, load Z2 → voltage pole L2 → main circuit breaker 2 → current limiter 1 → current 30A flows through the path K2 of the single-phase three-wire commercial power supply AC, A load current of 5 A (path K1) +30 A (path K2) = 35 A flows through the loads Z1 and Z2. Here, the currents I1 and I2 flowing through the voltage electrodes L1 and L2 from the single-phase three-wire commercial power supply AC are both 30A, and the current IN flowing through the neutral electrode N is 0A. The currents I1 and I2 have the same phase, and the vector sum I3 of the currents I1 and I2 is 30A + 30A = 60A, which exceeds the rated current 50A of the current limiter 1.

  When the loads Z1 and Z2 are unbalanced, as shown in FIG. 5, the single-phase three-wire commercial power supply AC → voltage pole L1 → current limiter 1 → main breaker 2 → branch breaker 4, load Z1 → neutral Pole N → Master breaker 2 → Current limiter 1 → Single-phase three-wire commercial power supply AC current 45A flows along path K3, and single-phase three-wire commercial power supply AC → Voltage pole L2 → Current limiter 1 → Master breaker 2 → branch breaker 4, load Z2 → neutral pole N → main circuit breaker 2 → current limiter 1 → current 5A flows through path K4 of single-phase three-wire commercial power supply AC, and load Z1 has 5A (path K1) A load current of +45 A (path K3) = 50 A flows, and 5 A (path K1) -5 A (path K4) = 0 A flows through the load Z2, so that no load current flows. Here, the current I1 flowing through the voltage electrode L1 from the single-phase three-wire commercial power supply AC is 45A, and the current I2 flowing through the voltage electrode L2 is 5A. At this time, there is a phase difference between the currents I1 and I2. Yes. Further, the current IN flowing through the neutral pole N is the sum of the currents I1 and I2, and is 45A + 5A = 50A, which is larger than the currents I1 and I2, and is at the same level as the rated current 50A of the main breaker 2.

  Therefore, in order to output an overcurrent alarm with the overcurrent alarm device 6 before the main current breaker 2 and the main breaker 2 are tripped as described above, the overcurrent alarm device of this embodiment is used. 6 performs output control of the overcurrent alarm shown in the flowchart of FIG.

  First, the instantaneous values of the currents I1 and I2 flowing through the voltage electrodes L1 and L2 are measured by the current transformers 5a and 5b (step S1), and the vector sum I3 of the instantaneous values of the currents I1 and I2 is calculated (step S2). Then, it is determined whether or not the vector sum I3 is greater than or equal to the rated current (50 A) of the current limiter 1 (step S3). If the vector sum I3 is greater than or equal to the rated current of the current limiter 1, an overcurrent alarm is output (step S4). Note that the value to be compared with the vector sum I3 in step S3 may be a reference value determined from the rated current of the current limiter 1.

  If the vector sum I3 is less than the rated current of the current limiter 1, the phase difference between the currents I1 and I2 is measured (step S5), and it is determined whether or not the phase difference exceeds 90 degrees and is 270 degrees or less. (Step S6). When the phase difference exceeds 90 degrees and is 270 degrees or less, it is determined that the load is in an unbalanced state, and the effective currents I1e and I2e of the currents I1 and I2 are calculated (step S7). Is determined to be greater than or equal to the rated current of the main breaker 2 (step S8). If the effective current sum INe is equal to or greater than the rated current of the main breaker 2, an overcurrent alarm is output (step S9). ). In addition, the value compared with the sum of effective currents INe in step S8 should just be a reference value determined from the rated current of the main breaker 2.

  If the phase difference exceeds 90 degrees and is not less than 270 degrees in step S6, or if the effective current sum INe is less than the rated current of the main breaker 2 in step S8, the process returns to step S1 and the above operation is repeated.

  That is, for the current limiter 1, by calculating the vector sum I3 of the instantaneous values of the currents I1 and I2 and determining whether or not an overcurrent alarm should be output, the current limiter 1 An overcurrent alarm can be output before tripping.

  For the main breaker 2, when the phase difference between the currents I1 and I2 exceeds 90 degrees and is 270 degrees or less, the sum INe of the effective currents I1e and I2e of the currents I1 and I2 is calculated to generate an overcurrent alarm. By determining whether or not to output, even when the current IN flowing through the neutral pole N is larger than the currents I1 and I2 as in an unbalanced state in which the load balance is lost, it is excessive before the main breaker 2 trips. A current alarm can be output.

  Therefore, the overcurrent alarm device 6 can reliably output an overcurrent alarm before the current limiter 1 and the main breaker 2 are tripped both when the load is balanced and unbalanced.

(Embodiment 2)
As shown in FIG. 7, the grid interconnection system of the present embodiment is obtained by deleting the current limiter 1 from the residential distribution board A of the first embodiment, and the current limiter presence / absence setting unit of the overcurrent alarm device 6. 62 is set to Current Limiter: None. The current transformers 5a and 5b measure currents I1 and I2 flowing through the voltage electrodes L1 and L2 between the main breaker 2 and the branch breaker 4. Other configurations are the same as those of the first embodiment, and a description thereof is omitted.

  Since the overcurrent alarm 6 outputs an overcurrent alarm before the main breaker 2 that is energized with a current higher than the rated current trips, the overcurrent alarm 6 of the present embodiment is an overcurrent alarm shown in the flowchart of FIG. Performs output control of current alarm.

  First, the instantaneous values of the currents I1 and I2 flowing through the voltage electrodes L1 and L2 are measured by the current transformers 5a and 5b (step S11), and the phase difference between the currents I1 and I2 is measured (step S12). Is greater than 90 degrees and less than 270 degrees (step S13). When the phase difference exceeds 90 degrees and is 270 degrees or less, it is determined that the load is in an unbalanced state, and the effective currents I1e and I2e of the currents I1 and I2 are calculated (step S14). It is determined whether or not the sum INe is greater than the effective current I1e and greater than the effective current I2e (step S15). If the sum of the effective currents INe is larger than the effective currents I1e and I2e, it is determined whether or not the sum of the effective currents INe is greater than or equal to the rated current of the main breaker 2 (step S16), and the sum of the effective currents INe is determined. If it is equal to or higher than the rated current, an overcurrent alarm is output (step S17). In addition, the value compared with the sum INe of effective currents at step S16 should just be a reference value determined from the rated current of the main breaker 2.

  If the phase difference is 90 degrees or less in step S13, or if the phase difference exceeds 270 degrees, or if the sum of effective currents INe is less than or equal to effective current I1e or I2e in step S15, the load is in an equilibrium state. First, it is determined whether or not the effective current I1e is larger than the effective current I2e (step S18). If the effective current I1e is larger than the effective current I2e, it is determined whether or not the effective current I1e is equal to or higher than the rated current of the main breaker 2 (step S19). A current alarm is output (step S20).

  If the effective current I2e is larger than the effective current I1e, it is determined whether or not the effective current I2e is equal to or higher than the rated current of the main breaker 2 (step S21). If the effective current I2e is equal to or higher than the rated current of the main breaker 2 An overcurrent alarm is output (step S22). In addition, the value compared with the sum of effective currents INe in steps S19 and S21 may be a reference value determined from the rated current of the main breaker 2.

  If the effective current sum INe is less than the rated current of the main breaker 2 in step S16, if the effective current I1e is less than the rated current of the main breaker 2 in step S19, the effective current I2e is rated for the main breaker 2 in step S21. If the current is less than the current, the process returns to step S1 and the above operation is repeated.

  That is, when the phase difference between the currents I1 and I2 exceeds 90 degrees and is 270 degrees or less, it is determined whether or not an overcurrent alarm should be output by calculating the sum INe of the effective currents I1e and I2e of the currents I1 and I2. Thus, even when the current IN flowing through the neutral pole N is larger than the currents I1 and I2 as in the case of unbalance where the load balance is lost, an overcurrent alarm can be output before the main breaker 2 trips.

  Further, when the load is balanced, it is determined whether or not an overcurrent alarm should be output by comparing any of the effective currents I1e and I2e with the rated current of the main breaker 2, and the main breaker 2 is determined even when the load is balanced. An overcurrent alarm can be output before the trip.

  Therefore, the overcurrent alarm device 6 can reliably output an overcurrent alarm before the main breaker 2 trips both when the load is balanced and unbalanced.

It is a block diagram of the grid connection system of Embodiment 1 of this invention. It is a schematic block diagram of a grid connection system same as the above. It is a block diagram of an overcurrent alarm device same as the above. It is a figure which shows the electric current path at the time of load balance same as the above. It is a figure which shows the electric current path at the time of load unbalance same as the above. It is a flowchart figure which shows the output control of an overcurrent warning same as the above. It is a block diagram of the grid connection system of Embodiment 2 of this invention. It is a flowchart figure which shows the output control of an overcurrent warning same as the above.

Explanation of symbols

AC Single-phase three-wire commercial power supply L1, L2 Voltage pole N Neutral pole B Fuel cell unit A Residential distribution board 1 Current limiter 2 Master breaker 3 Interconnection breaker 4 Branch breaker 5a, 5b Current transformer 6 Overcurrent alarm Z1, Z2 load

Claims (2)

A current limiter with the primary side connected to a single-phase three-wire commercial power source consisting of two voltage poles and one neutral pole, and a main with the primary side connected to each pole on the secondary side of the current limiter A breaker, a primary breaker connected to an external power supply, a secondary breaker connected to each pole on the secondary side of the main breaker, and an external power supply connected to a single-phase three-wire commercial power supply, and a main breaker Current flowing through each voltage electrode between the current limiter and the branch breaker, and one or a plurality of branch breakers in which the primary side is connected to one of the voltage and neutral electrodes between Two current transformers to be measured, and an overcurrent alarm device that outputs an overcurrent alarm based on each current value measured by the two current transformers,
The overcurrent alarm calculates a vector sum of instantaneous currents flowing through the respective voltage electrodes, and outputs an overcurrent alarm when the vector sum exceeds a first reference value determined from the rated current of the current limiter, When the vector sum is less than the first reference value, the phase difference of the current flowing through each voltage electrode is measured, and when the phase difference exceeds 90 degrees and is 270 degrees or less, the sum of the effective currents flowing through each voltage electrode is calculated. An overcurrent alarm is output when the sum of the effective currents is equal to or greater than a second reference value determined from the rated current of the main breaker. Main breaker with primary side connected to single-phase three-wire commercial power source consisting of two voltage poles and one neutral pole, and primary side to external power source with primary side connected to each pole on secondary side of main breaker Connect the secondary side and connect the external power source to the single-phase three-wire commercial power source, and the primary side to either the voltage pole or neutral pole between the main breaker and the connected breaker Based on one or more branch breakers connected to each other, two current transformers for measuring the current flowing through each voltage pole between the main breaker and the branch breaker, and each current value measured by the two current transformers With an overcurrent alarm that outputs an overcurrent alarm,
The overcurrent alarm measures the phase difference of the current flowing through each voltage electrode, and calculates the sum of the effective currents flowing through each voltage electrode when the phase difference exceeds 90 degrees and is 270 degrees or less. An overcurrent alarm is output when the sum of the currents is greater than the effective current flowing through each voltage electrode and exceeds a reference value determined from the rated current of the main breaker, and when the phase difference is 90 degrees or less, or When the phase difference exceeds 270 degrees, or when the phase difference exceeds 90 degrees and is 270 degrees or less, and the sum of the effective currents is equal to or less than the effective current flowing through one of the voltage electrodes, the effective current flowing through each voltage electrode A grid interconnection system that outputs an overcurrent alarm when the larger effective current out of the current exceeds a reference value determined from the rated current of the main breaker.

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