JP2005168213A - Excessive current suppressing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excessive current suppressing device capable of sufficiently suppressing excessive current even if operation delay time changes. <P>SOLUTION: In an excitation start signal generating means 23, an excitation start signal is generated by a zero-cross signal output from a voltage detection means 21 and the operation delay time of the delay time information to temperature operation recorded by a recording means 29 to be output to an electromagnetic switch excitation means 24, wherein an electromagnetic switch 16 starts to be excited. In an operation delay time detection means 30 of the electromagnetic switch, when the current shown by the current signal output from a current detection means 28 is larger than a threshold value, the operation delay time of the delay time information to temperature operation recorded by the recording means 29 is updated to be used for subsequent system linkages. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power generation system that supplies electric power obtained from a DC power supply to an electric power system, and more particularly to an overcurrent suppressing device that suppresses an overcurrent flowing from the electric power system when starting interconnection of electric power.

Conventionally, various forms have been considered as a power generation system that supplies power obtained from a DC power source to a power system.
FIG. 5 is a diagram illustrating an example of a conventional power generation system.
In the power generation system 50 shown in FIG. 5, DC power generated from a DC power source 51 such as a solar cell or a fuel cell is boosted by a DC-DC converter 52, and then the boosted DC power is converted into AC power by an inverter 53. The power converted into AC power is freed of harmonics by the output sine filter 54 and supplied to the power system 56 via the electromagnetic switch 55 as sine AC power.

  In the power generation system 50, since the operation of the inverter 53 is started after the electromagnetic switch 55 is closed, and the output of the inverter 53 is supplied to the power system 56, the electromagnetic switch 55 before the contact is closed. No charge is accumulated in the capacitor 57 of the output sine filter 54. Therefore, a charging current may flow from the power system 56 to the capacitor 57 of the output sine filter 54 via the electromagnetic switch 55 at the timing when the electromagnetic switch 55 is closed.

  And if the power switch 55 is closed when the voltage of the power system 56 is large, a large current (hereinafter referred to as overcurrent) may flow into the power generation system 50, and the components constituting the power generation system 50, For example, there is a problem that the capacitor 57 or the like is damaged or the life of the capacitor 57 or the like is reduced.

Moreover, since an overcurrent flows from the electric power system 56, the voltage of the electric circuit connected to the electric power generation system 50 is temporarily reduced, and thus adversely affects other electric power generation systems and electric devices connected to the electric circuit. There is a problem that there is a possibility.
Therefore, as shown in FIG. 5, in the power generation system 50, the electromagnetic switching is actually performed from the previously measured excitation of the electromagnetic switch 55 (excitation of the excitation coil constituting the on / off switch of the electromagnetic switch 55). Operation delay time information 58 indicating operation delay time until the device 55 is closed, voltage detection means 59 for detecting an output voltage of the power system 56 and outputting a zero cross signal when the output voltage of the power system 56 becomes zero, From the zero-cross signal and the operation delay time information 58, the timing for causing the electromagnetic switch 55 to close the contact when the output voltage of the power system 56 is close to zero is obtained, and the excitation start signal for starting the excitation of the electromagnetic switch 55 is output. A signal generation unit 60 and an electromagnetic switch excitation unit 61 for starting excitation of the electromagnetic switch 55 by an excitation start signal, and the output voltage of the power system 56 is The electromagnetic switch 55 at the timing to be near it has been proposed to be the contacts closed. (For example, see Patent Document 1)
Thus, since the electromagnetic switch 55 can be closed when the output voltage of the electric power system 56 is near zero, the overcurrent flowing from the electric power system 56 can be suppressed when the electromagnetic switch 55 is closed. Can do.
JP2003-134670 (Pages 3-4, Fig. 1)

  However, since the operation delay time of the electromagnetic switch 55 changes depending on various usage environments in the power generation system 50, the electromagnetic switch 55 is closed by using the operation delay time measured in advance as described above. In the configuration for obtaining the timing to perform, there is a possibility that a sufficient effect for suppressing the overcurrent cannot be obtained.

  Accordingly, an object of the present invention is to provide an overcurrent suppressing device that can sufficiently suppress an overcurrent even when the operation delay time changes.

In order to solve the above problems, the present invention adopts the following configuration.
That is, the overcurrent suppressing device according to the present invention is a power generation system in which power obtained from a DC power supply outputs AC power via an electromagnetic switch and supplies the power system to the power system. An overcurrent suppressing device for suppressing an overcurrent flowing from the voltage detection means for detecting an output voltage of the power system and outputting a zero cross signal when the output voltage becomes zero; and an environment for using the power generation system. Accordingly, the operation delay time estimating means for estimating the operation delay time from the start of excitation of the electromagnetic switch to the contact closing circuit, the zero cross signal output from the voltage detecting means and the operation delay time estimating means are estimated. Excitation start signal generating means for outputting an excitation start signal representing excitation start timing of the electromagnetic switch based on the operation delay time; and based on the excitation start signal. Te, characterized in that it comprises an electromagnetic switch excitation means for starting excitation of the electromagnetic switch.

  As described above, the operation delay time is estimated according to the use environment in the power generation system, and the excitation start signal is generated based on the estimated operation delay time and the zero-cross signal. Even if it changes, when the output voltage of the power system becomes zero, the electromagnetic switch can be closed. Thereby, even if the operation delay time changes, an overcurrent flowing from the current system to the DC power supply side can be suppressed.

Further, the operation delay time estimation means of the overcurrent suppressing device includes temperature detection means for detecting the temperature in the power generation system, and estimates the operation delay time according to the temperature detected by the temperature detection means. You may comprise as follows.
As a result, even if the temperature in the power generation system changes and the operation delay time changes, the electromagnetic switch can be closed when the output voltage of the power system becomes zero. The overcurrent flowing through can be suppressed.

  The operation delay time estimating means of the overcurrent suppressing device includes a recording means for recording operation delay time information indicating the operation delay time, and the power when the electromagnetic switch is closed according to the excitation start signal. Current detection means for detecting a current flowing from the system to the power generation system, and configured to update the operation delay time in the operation delay time information according to the current detected by the current detection means. .

As a result, even if the operation delay time changes due to aging in the power generation system, the electromagnetic switch can be closed when the output voltage of the power system becomes zero. Current can be suppressed.
Further, the operation delay time estimating means of the overcurrent suppressing device includes a recording means for recording temperature-related operation delay time information indicating a temperature dependence relationship of the operation delay time from the start of excitation to the contact closing in the electromagnetic switch; Temperature detection means for detecting the temperature in the power generation system, and current detection means for detecting a current flowing from the power system to the power generation system when the electromagnetic switch is closed according to the excitation start signal, Estimating the operation delay time corresponding to the temperature detected by the temperature detection means using the temperature operation delay time information for the temperature, and when the current detected by the current detection means is greater than a threshold value, The operation delay time in the temperature operation delay time information may be updated.

  As a result, even if the operation delay time changes due to temperature changes in the power generation system or changes over time in the power generation system, the electromagnetic switch can be closed when the output voltage of the power system becomes zero. Overcurrent flowing from the power source to the DC power source side can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, even if an operation delay time changes according to the use environment in an electric power generation system, an electromagnetic switch can be closed at the timing when the output voltage of an electric power system becomes zero. Thereby, even if the operation delay time changes, an overcurrent flowing from the current system can be suppressed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating an overcurrent suppressing device according to an embodiment of the present invention.
As shown in FIG. 1, a power generation system 10 is boosted by a DC power source 11 such as a solar cell or a fuel cell, a DC-DC converter 12 that boosts DC power generated by the DC power source 11, and a DC-DC converter 12. An inverter 13 that converts DC power into AC power, and an output sine filter 15 that supplies harmonics contained in the AC power converted by the inverter 13 to the power system 14 that outputs AC power as sinusoidal AC power. And an electromagnetic switch 16 provided between the power system 14 and the output sine filter 15 and an overcurrent suppressing device 17.

Further, the output sine filter 15 is an integration circuit including a capacitor 18 and a reactor 19, for example.
The electromagnetic switch 16 is, for example, a circuit that closes the contact when the exciting coil 20 is excited and electrically connects the electric circuit on the power generation system 10 side and the electric circuit on the power system 14 side.

  The overcurrent suppressing device 17 detects the output voltage of the power system 14 and outputs a zero cross signal when the output voltage of the power system 14 becomes zero. The operation delay time estimation means 22 that estimates the operation delay time that the electromagnetic switch 16 takes until the contact is closed, and the zero-cross signal output from the voltage detection means 21 and the operation delay time estimated by the operation delay time estimation means 22 On the basis of the excitation start signal generating means 23 for outputting an excitation start signal for starting the excitation of the electromagnetic switch 16, and on the basis of the excitation start signal output from the excitation start signal generating means 23, the electromagnetic switch And an electromagnetic switch excitation means 24 for starting 16 excitations.

  The operation delay time estimation means 22 includes a temperature detection means 26 for detecting the temperature in the vicinity of the electromagnetic switch 16 based on the voltage of the thermistor 25 provided in the vicinity of the electromagnetic switch 16, the output sine filter 15 and the electromagnetic switch. The current flowing from the power system 14 to the power generation system 10 side when the electromagnetic switch 16 is closed based on the voltage of the shunt resistor 27 provided between the switch 16 and the reactor of the output sine filter 15 from the power system 14. Current detecting means 28 for detecting a charging current (reverse current) flowing through the output current 19 and outputting a current signal indicating the detected current, and a temperature operation delay with respect to temperature indicating the temperature dependence of the operation delay time measured in advance. The recording means 29 for recording time information and the current indicated by the current signal output from the current detection means 28 are compared with a threshold value, and the current is larger than the threshold value. , And an electromagnetic switch operation delay time detecting means 30 for updating the operation delay time at versus temperature operation delay time information recorded in the recording unit 29. The place where the temperature detection means 26 detects the temperature is not limited to the vicinity of the electromagnetic switch 16. The current detection means 28 is configured to detect a current flowing from the power system 14 to the power generation system 10 based on an output of a CT (Current Transformer) provided between the output sine filter 15 and the electromagnetic switch 16. May be.

Next, the operation of the overcurrent suppressing device 17 will be described.
The excitation start signal generation means 23 of the overcurrent suppressing device 17 receives the zero-cross signal output from the voltage detection means 21 and the temperature operation delay time recorded by the recording means 29 when a grid connection start command is input from the outside. Based on the information operation delay time, an excitation start signal is generated and output to the electromagnetic switch excitation means 24. Then, the electromagnetic switch excitation means 24 starts exciting the electromagnetic switch 16.

  Further, the electromagnetic switch operation delay time detection means 30 is an operation delay in the temperature operation delay time information recorded in the recording means 29 when the current indicated by the current signal output from the current detection means 28 is larger than the threshold value. Update time. Then, the temperature operation delay time information updated by the electromagnetic switch operation delay time detection means 30 is used at the time of grid connection after the next time.

FIG. 2 is a diagram illustrating the temperature dependency of the operation delay time. Note that the vertical axis of the graph shown in FIG. 2 indicates the operation delay time, and the horizontal axis indicates the temperature.
For example, when the temperature detected by the temperature detecting means 26 is −25 ° C., the excitation start signal generating means 23 uses the 15 ms operation delay time corresponding to the detected temperature −25 ° C. to start the excitation. Generate a signal. Further, when the temperature detected by the temperature detecting means 26 is 55 ° C., an excitation start signal is generated using an operation delay time of 17 ms corresponding to the detected temperature 55 ° C.

  The electromagnetic switch operation delay time detection means 30 is, for example, the excitation of the electromagnetic switch 16 measured when the current indicated by the current signal output from the current detection means 28 exceeds a threshold value. The operation delay time 16 ms required from the start until the electromagnetic switch 16 closes the contact is set as the operation delay time corresponding to the temperature −25 ° C. detected by the temperature detection means 26 when the current is exceeded. That is, when the current indicated by the current signal exceeds the threshold value, the electromagnetic switch operation delay time detection unit 30 exceeds the threshold value of the operation delay time 15 ms corresponding to the temperature −25 ° C. detected by the temperature detection unit 26. The counter is updated to the operation delay time 16 ms counted by the counter.

If the temperature detected by the temperature detecting means 26 is not in the temperature operation delay time information, it is detected by linear interpolation or the like using the known temperature operation delay time information before and after the detected temperature. An operation delay time corresponding to a certain temperature may be estimated.
FIG. 3 is a diagram for explaining the update of the operation delay time. FIG. 3A shows the relationship between the output voltage of the power system 14 and the operation delay time x, and FIG. 3B shows the current detection. FIG. 3C shows the relationship between the current detected by the means 28 and the threshold, FIG. 3C shows the timing signal for the counter in the electromagnetic switch operation delay time detection means 30, and FIG. 3D shows that the operation delay time is appropriate. The relationship between the output voltage of the electric power system 14 and the operation delay time when judged is shown.

  For example, consider a case where the frequency of the output power of the power system 14 is 50 Hz, the temperature detected by the temperature detection means 26 is −25 ° C., and the operation delay time corresponding to the detected temperature −25 ° C. is 15 ms. In such a case, as shown in FIG. 3A, one cycle of the output voltage of the power system 14 is 20 ms. Further, the excitation start signal generating means 23 obtains an operation delay time of 15 ms from the detected temperature of −25 ° C. based on the temperature operation delay time information, and the output voltage of the power system 14 is 20 ms per cycle and the operation delay time is 15 ms. And 5 ms after the timing when the output voltage of the power system 14 becomes zero (zero cross point), the excitation start signal is output.

  However, as shown in FIG. 3B, when the electromagnetic switch 16 is closed and the current detected by the current detecting means 28 exceeds the threshold value, that is, the operation delay time 15 ms corresponding to the temperature of −25 ° C. is not sufficient. When it is determined to be appropriate, the electromagnetic switch operation delay time detecting means 30 takes 16 ms (FIG. 3 (c)) from the excitation start signal output of the excitation start signal generating means 23 to the current detection of the current detecting means 28. ) The delay in operation corresponding to a temperature of −25 ° C. is obtained by subtracting the free-run timer value of 10 ms at the turn-on time of the counter output signal from the free-run timer value of 26 ms at the turn-off time of the counter output signal shown in FIG. Time.

  Then, in the grid connection after the next time, as shown in FIG. 3D, when the detected temperature is −25 ° C., the excitation start signal generator 23 uses the updated operation delay time 16 ms. An excitation start signal is output 4 ms after the zero cross point of the output voltage of the power system 14. Thereby, when the output voltage of the electric power system 14 is zero, the electromagnetic switch 16 can be closed.

Next, the operation of the electromagnetic switch operation delay time detection means 30 will be described.
FIG. 4 is a flowchart showing the operation of the electromagnetic switch operation delay time detection means 30.
First, in step S1, the electromagnetic switch operation delay time detection means 30 confirms whether the flag is 1 or 0. When the flag is 1, it indicates that the operation delay time is being monitored, and when the flag is 0, it indicates that the operation delay time is not being monitored.

  Next, when it is confirmed in step S1 that the flag is 0 (step S1 is N (No)), in step S2, the electromagnetic switch operation delay time detection means 30 instructs the electromagnetic switch 16 to start excitation. It is confirmed whether or not is an ON state change. That is, for example, in step S <b> 2, the electromagnetic switch operation delay time detection unit 30 confirms whether or not the excitation start signal is output from the excitation start signal generation unit 23.

Next, when it is confirmed in step S2 that the change is not ON (step S2 is N), the electromagnetic switch operation delay time detecting means 30 exits the operation delay time update process.
Further, when it is confirmed in step S2 that the change is ON (step S2 is Y (Yes)), the electromagnetic switch operation delay time detecting means 30 sets the flag to 1 in step S3, and step In S4, the value (Tis) of a free-run timer provided in the CPU or the like constituting the overcurrent suppressing device 17 is stored. For example, the free-run timer value 10 ms in FIG. It should be noted that the free-run timer value stored in step S4 is not updated in the subsequent update processing until a series of operation delay time detection operations are completed.

  Next, the electromagnetic switch 16 is closed based on the temperature operation delay time information, and when the electromagnetic switch operation delay time detection means 30 receives the current signal output from the current detection means 28 in step S5, Similar to step S4, the value of the free-run timer is stored. For example, the free run timer value 26 ms in FIG. 3C is stored.

In step S6, the electromagnetic switch operation delay time detecting means 30 determines whether or not the absolute value (| Iac |) of the current indicated by the current signal is larger than the absolute value (threshold value) (| Ij |) of the specified value. Confirm.
In step S6, when it is confirmed that the absolute value of the current indicated by the current signal is larger than the absolute value of the specified value (step S6 is Y), in step S7, the electromagnetic switch operation delay time detection means 30 The free run timer value stored in step S4 is subtracted from the free run timer value stored in step S5, and the difference value (Tid) is calculated as a new operation delay time. For example, the free run timer value 10 ms is subtracted from the free run timer value 26 ms in FIG. 3C, and the difference value 16 ms is set as a new operation delay time.

Next, in step S8, the electromagnetic switch operation delay time detecting means 30 stores the temperature (Temp) detected by the temperature detecting means 26.
In step S9, the electromagnetic switch operation delay time detecting means 30 updates the operation delay time of the temperature-operation delay time information corresponding to the temperature stored in step S8 to the operation delay time calculated in step S7.

In step S10, the electromagnetic switch operation delay time detection means 30 sets the flag to 0 and ends the update process.
In Step S1, when it is confirmed that the flag is 1 (Y in Step S1), the electromagnetic switch operation delay time detecting means 30 performs the update process from Step S5.

  In step S6, when it is confirmed that the absolute value of the current indicated by the current signal is not larger than the absolute value of the specified value (step S6 is N), in step S11, the electromagnetic switch operation delay time detection means 30 Then, the free-run timer value stored in step S4 is subtracted from the free-run timer value stored in step S5, and the difference value (Top) is calculated as the elapsed time.

In step S12, the electromagnetic switch operation delay time detecting means 30 confirms whether or not the elapsed time calculated in step S11 is longer than the operation guarantee time (Tc: time that the operation is not delayed as a product). To do.
In step S12, when it is confirmed that the elapsed time is longer than the operation guarantee time (step S12 is Y), the electromagnetic switch operation delay time detection means 30 performs the update process from step S10.

In Step S12, when it is confirmed that the elapsed time is not longer than the operation guarantee time (N in Step S12), the electromagnetic switch operation delay time detection unit 30 ends the update process.
In the above embodiment, the electromagnetic switch operation delay time detection means 30 is configured to update the operation delay time in the temperature operation delay time information, but the electromagnetic switch operation delay time detection means 30 depends on the temperature. It is also possible to update the non-operation delay time and generate the excitation start signal from the operation delay time not dependent on the temperature and the zero cross signal.

In the above embodiment, the operation delay time is updated when the absolute value (| Iac |) of the current indicated by the current signal is larger than the absolute value (threshold value) (| Ij |) of the specified value. Regardless, you may always update.
In the above embodiment, the current detection means 28 is used to output a current signal to the electromagnetic switch operation delay time detection means 30, but the present invention is not limited to this configuration. For example, it is only necessary to know the exact time when the electromagnetic switch 16 is closed without detecting the current itself. In this case, step S6 may be skipped and the process proceeds from step S5 to step S7.

  As described above, the overcurrent suppressing device 17 always monitors whether or not the recorded operation delay time is appropriate when the contact of the electromagnetic switch 16 is closed. Since the delay time is updated, the delay time is estimated every time, and the output voltage of the power system 14 is changed even if the operation delay time changes due to the use environment such as the temperature change in the power generation system 10 or the secular change in the power generation system 10. When is zero, the electromagnetic switch 16 can be closed. Thereby, even if the operation delay time changes, the overcurrent flowing from the current system 14 to the power generation system 10 can be suppressed.

The overcurrent suppressing device 17 can be applied to all power generation systems connected to the power system 14 by the electromagnetic switch 16 regardless of the type of the DC power supply 11.
Further, the overcurrent suppressing device 17 can suppress the overcurrent flowing from the power system 14 in the power generation system having a large temperature change near the electromagnetic switch 16.

It is a figure which shows the overcurrent suppression apparatus of embodiment of this invention. It is a figure which shows the temperature dependence relationship of an operation delay time. It is a figure for demonstrating the update of operation | movement delay time. It is a flowchart which shows operation | movement of an electromagnetic switch operation delay time detection means. It is a figure which shows the conventional electric power generation system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electric power generation system 11 DC power supply 12 DC-DC converter 13 Inverter 14 Power system 15 Output sine filter 16 Electromagnetic switch 17 Overcurrent control device 18 Capacitor 19 Reactor 20 Excitation coil 21 Voltage detection means 22 Operation delay time estimation means 23 Excitation start Signal generation means 24 Electromagnetic switch excitation means 25 Thermistor 26 Temperature detection means 27 Shunt resistance 28 Current detection means 29 Recording means 30 Electromagnetic switch operation delay time detection means

Claims (4)

In a power generation system that outputs AC power obtained from a DC power supply via an electromagnetic switch and supplies the power to an electric power system, an overcurrent suppressing device that suppresses an overcurrent flowing from the electric power system when starting power interconnection Because
Voltage detection means for detecting an output voltage of the power system and outputting a zero cross signal when the output voltage becomes zero;
Depending on the usage environment of the power generation system, an operation delay time estimation means for estimating an operation delay time required from the start of excitation of the electromagnetic switch to contact closing;
Excitation start signal generating means for outputting an excitation start signal representing the excitation start timing of the electromagnetic switch based on the zero cross signal output from the voltage detection means and the operation delay time estimated by the operation delay time estimation means. When,
Electromagnetic switch excitation means for starting excitation of the electromagnetic switch based on the excitation start signal;
An overcurrent suppressing device comprising: The overcurrent suppressing device according to claim 1,
The operation delay time estimation means includes a temperature detection means for detecting a temperature in the power generation system,
The overcurrent suppressing device, wherein the operation delay time is estimated according to a temperature detected by the temperature detecting means. The overcurrent suppressing device according to claim 1,
The operation delay time estimation means includes recording means for recording operation delay time information indicating the operation delay time,
Current detection means for detecting a current flowing from the power system to the power generation system when the electromagnetic switch is closed according to the excitation start signal;
With
An overcurrent suppressing device that updates an operation delay time in the operation delay time information according to a current detected by the current detection means. The overcurrent suppressing device according to claim 1,
The operation delay time estimation means is a recording means for recording temperature-related operation delay time information indicating a temperature dependency relationship of the operation delay time from the start of excitation to the contact closing in the electromagnetic switch;
Temperature detecting means for detecting the temperature in the power generation system;
Current detection means for detecting a current flowing from the power system to the power generation system when the electromagnetic switch is closed according to the excitation start signal;
With
Estimating the operation delay time corresponding to the temperature detected by the temperature detection means using the temperature operation delay time information for the temperature, and when the current detected by the current detection means is greater than a threshold value, An overcurrent suppressing device that updates an operation delay time in temperature operation delay time information.

Images