JP4929054B2 - Earth return transportation system - Google Patents

Description

  The present invention relates to a ground return transportation system.

Conventionally, it has a transmitter that digitally encodes transmission information and a receiver that receives a digitally encoded (encoded) signal, and detects the high level and low level of the digitally encoded signal at the receiver side. Thus, a ground return transportation system that recognizes the content of transmission information is known. In this system, the digitally encoded signal is a single frequency signal such as 1477 Hz (see Patent Document 1).
Japanese Patent Laid-Open No. 9-8711

  In the conventional ground return transportation system described above, since noise is superimposed on a digitally encoded signal, the receiver includes a filter that extracts only a signal of a specific frequency (for example, 1477 Hz). For this reason, even if noise having a frequency different from the specific frequency is superimposed on the digitally encoded signal, the noise is removed, and so-called conveyance abnormality does not occur.

  However, in the conventional system, if noise of a specific frequency and its vicinity frequency is superimposed on the signal, it becomes impossible to determine the high level and low level of the signal on the receiver side, which may cause a carrier abnormality.

  Further, in the conventional system, even when a conveyance error occurs and information that should be transmitted to other devices (for example, a management center or an alarm device) cannot be transmitted, the receiver can determine the state. It will disappear.

  The present invention has been made in order to solve such a conventional problem, and an object of the present invention is to improve the reliability of conveyance communication and to determine the state of conveyance abnormality. To provide a transport system.

Earth return conveying system according to claim 1 of the present invention is to inject a transmit signal to transformer B species ground line, for receiving the transmission signal from between the ground phase and earth of the low-pressure side path of the transformer In the ground return carrier system, a first carrier wave of which amplitude is modulated with an n-bit data pulse composed of a first pulse train in which information is given to the presence or absence of a high-level pattern is detected. A frequency signal and a second carrier wave are amplitude- modulated by an n-bit inverted data pulse comprising a second pulse train in which information is given to the presence or absence of a low-level pattern by inverting the level of the first pulse train. Two frequency signals are synchronized with each other, and a high level equivalent region of the first frequency signal, a low level equivalent region, and a low level equivalent region of the second frequency signal, A transmitter that transmits a combined signal, each of which is superimposed on a corresponding region of the e-level, as a transmission signal; a second filter that receives the transmission signal and passes the first carrier; and a second filter that passes the second carrier The first frequency signal and the second frequency signal that respectively pass through the filter are demodulated separately, and the data pulse is based on either the first pulse train or the second pulse train obtained. And a receiver for generating

The ground return transportation system according to claim 2 of the present invention is the ground return transportation system according to claim 1 , wherein the transmitter is based on information output from an information output means such as a demand monitoring device or an insulation monitoring device. The data pulse is generated by converting the information into a predetermined format.

The earth return route transport system according to claim 3 of the present invention is the earth return route transfer system according to claim 1 or 2 , wherein the receiver passes through the first filter and the second filter, respectively. When the first frequency signal and the second frequency signal are demodulated separately, the first frequency signal and the second frequency signal are respectively envelope-detected.

The earth return route transport system according to claim 4 of the present invention is the earth return route transfer system according to any one of claims 1 to 3 , wherein the receiver includes the first frequency signal and the second frequency signal. When the signal is demodulated separately to determine the high / low level of the demodulated output, the threshold level for the determination is varied according to the difference between the high level and the low level.

The earth return route transport system according to claim 5 of the present invention is the earth return route transport system according to any one of claims 1 to 4 , wherein the receiver is obtained by demodulating the first frequency signal. The pulse train corresponding to the first pulse train and the pulse train corresponding to the second pulse train obtained by demodulating the second frequency signal are analyzed at a predetermined sampling period, and either one of the pulse trains is analyzed. When the header is confirmed, data collection is started in both the pulse train corresponding to the first pulse train and the pulse train corresponding to the second pulse train.

  As described above, according to the present invention, a transmission unit in which a transmission signal obtained by modulating a carrier wave with a digital signal is injected and transmitted to a B-type ground line to propagate the low-voltage side circuit of the transformer, and the low-voltage side circuit of the transformer Receiving the transmission signal from between the ground phase and the ground, and receiving the digital signal by demodulating the received signal, the transmission unit includes at least a frequency separated by a predetermined interval. Since the two carrier waves are respectively modulated with the digital signal to generate the transmission signal, and the reception unit is configured to demodulate the reception signal for each carrier wave, a signal obtained by modulating a certain carrier wave is There is a possibility that reception abnormality may occur due to noise at a specific frequency, but it is difficult to cause reception abnormality due to noise at a specific frequency for signals modulated by other carriers. Issue likely to be received successfully by the receiver.

  Embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a configuration diagram of a ground return transportation system according to a first embodiment of the present invention. As shown in FIG. 1, this earth return transportation system 1 is applied to a demand monitoring device, and includes a high-voltage path 10, a transformer T, a low-voltage path 20, a first ground line 31 and a second ground line. 32, a watt hour meter 40, a demand detector (transmitter) 50, a transformer 60, a receiver 70, and an alarm device 80.

  The high piezoelectric path 10 is fed with a high voltage (first voltage) such as 6600 V (volt), for example. The transformer T transforms the high voltage of the high piezoelectric path 10 into a voltage (second voltage) such as 100 V, which is lower than the high voltage.

  The low piezoelectric path 20 is supplied with a low voltage transformed by the transformer T. The low piezoelectric circuit 20 is a single-phase three-wire electric circuit, and includes a grounding electric circuit 21 and a non-grounding electric circuit 22. A load (not shown) is connected to the grounding electric circuit 21 and the non-grounding electric circuit 22 of the low piezoelectric circuit 20, and the voltage of the low piezoelectric circuit 20 is supplied to the load.

  The first ground line 31 and the second ground line 32 are electrically connected from the low piezoelectric path 20 to the ground. Specifically, the first ground line 31 and the second ground line 32 have one end connected to the ground electrical circuit 21 of the low piezoelectric path 20 and the other end connected to the ground. The watt hour meter 40 calculates the amount of power used by the load.

  The demand detector 50 monitors and controls the maximum demand power (demand). Electric charges paid by large consumers who contract with high-voltage power and commercial power are basic charges and electric energy charges. Of these, the basic charges are determined by the maximum demand power. The maximum demand power is measured by a transaction demand meter and an average value (average power) is calculated in units of 30 minutes, and the maximum value in one month is set as the maximum demand power (demand) of the month. Since the basic charge for one year is determined by the maximum power demand, the basic charge can be reduced by lowering the maximum power demand. Therefore, a demand detector 50 that monitors and controls demand is installed.

  Further, the demand detector 50 receives various information (specific information) transmitted from the watt-hour meter 40, converts the information into a digitally encoded frequency signal, and the frequency signal is passed through the transformer 60 to the first ground line. It is configured to be injected into 31 and transmitted to the grounding electric circuit 21 of the low piezoelectric circuit 20.

  The receiver 70 receives a frequency signal that has reached the second grounding line 32 from the grounding electrical path 21 of the low piezoelectric path 20. The receiver 70 analyzes the received frequency signal, recognizes the content of information transmitted from the demand detector 50, and performs output according to the content.

  The alarm device 80 performs an alarm operation or the like according to the output of the receiver 70. For example, the alarm device 80 issues a caution warning when the amount of power used approaches demand, and issues a warning alert when the amount of power used exceeds demand. The alarm operation may be performed by sound such as output sound, or may be performed visually such as lamp lighting.

  FIG. 2 is a detailed configuration diagram of the demand detector 50 of FIG. The demand detector 50 includes an input interface (I / F) unit 51, a first crystal oscillator 52a and a second crystal oscillator 52b, a CPU (Central Processing Unit) 53, a first modulation unit 54a and a second modulation unit 54b. And a synthesizing unit 55 and a power amplifying unit 56.

  The input interface unit 51 inputs 5-bit data transmitted from the watt-hour meter 40. The information from the watt-hour meter 40 is not limited to 5-bit data. Similarly, the input interface unit 51 is not limited to 5-bit data, and is configured to input data less than 5 bits or more than 5 bits. Also good.

  The first crystal oscillator 52a and the second crystal oscillator 52b generate clocks at predetermined intervals. The CPU 53 has a control program and control data for controlling the entire demand detector 50, and is configured to perform digital encoding according to the input 5-bit information content.

  The first modulation unit 54a converts the signal digitally encoded by the CPU 53 into a frequency signal corresponding to the clock generated by the first crystal oscillator 52a. Specifically, the first modulation unit 54a oscillates with the oscillation frequency of the first crystal oscillator 52a as a fundamental frequency, and divides the fundamental frequency to a carrier frequency around 1075 Hz (Hertz) by a predetermined division ratio. Thereafter, the first modulation unit 54 a is configured to generate a 1075 Hz frequency signal by superimposing the carrier frequency on the digitally encoded signal transmitted from the CPU 53. The frequency signal generated by the first modulation unit 54a is not limited to 1075 Hz, and may be another frequency.

  The second modulator 54b converts the signal digitally encoded by the CPU 53 into a frequency signal corresponding to the clock generated by the second crystal oscillator 52b. Specifically, the second modulator 54b oscillates with the oscillation frequency of the second crystal oscillator 52b as a fundamental frequency, and divides this fundamental frequency to a carrier frequency around 1770 Hz (Hertz) by a predetermined division ratio. After that, the second modulation unit 54b and the digitally encoded signal transmitted from the CPU 53 are superimposed on the carrier frequency to generate a frequency signal of 1770 Hz. The frequency signal generated by the second modulation unit 54b is not limited to 1770 Hz, and may be another frequency.

  The synthesizer 55 synthesizes the frequency signal generated by the first modulator 54a and the frequency signal generated by the second modulator 54b. The power amplifying unit 56 is a power amplifier that amplifies the power of the signal synthesized and output by the synthesizing unit 55.

  FIG. 3 is a detailed block diagram of the receiver 70 of FIG. The receiver 70 includes a receiving unit 71, an input unit 72, a first band pass filter 73 a and a second band pass filter 73 b, a demodulation unit 74, a CPU 75, and an output interface unit 76.

  The receiving unit 71 receives the frequency signal from the demand detector 50 that has been transported to the first ground line 31 and has reached the second ground line 32, and delivers it to the input unit 72. The input unit 72 is an amplifier for amplifying the frequency signal attenuated by passing through the low piezoelectric path 20.

  The first band pass filter 73a passes a signal having a frequency of about 1075 Hz and cuts a signal having another frequency. That is, the first band pass filter 73a passes the 1075 Hz frequency signal generated by the first modulation unit 54a, and cuts the noise of other frequencies and the 1770 Hz frequency signal modulated by the second modulation unit 54b. It is. Needless to say, when the frequency of the frequency signal generated by the first modulation unit 54a is changed, the first bandpass filter 73a changes the frequency to be passed according to the change.

  The second band pass filter 73b passes a signal having a frequency around 1770 Hz and cuts a signal having another frequency. That is, the second band pass filter 73b passes the 1770 Hz frequency signal generated by the second modulation unit 54b, and cuts the noise of other frequencies and the 1075 Hz frequency signal modulated by the first modulation unit 54a. It is. Needless to say, when the frequency of the frequency signal generated by the second modulation unit 54b is changed, the second bandpass filter 73b changes the frequency to be passed according to the change.

  The demodulator 74 removes the carrier carrier from the signals that have passed through the first bandpass filter 73a and the second bandpass filter 73b, and demodulates them into a digitally encoded signal. The CPU 75 has a control program and control data for controlling the entire receiver 70, and is configured to generate a 5-bit signal corresponding to the content of the digitally encoded signal. The output interface unit 76 performs output in accordance with a 5-bit signal generated by the CPU 75.

  FIG. 4 is a diagram for explaining digital encoding by the CPU 53 of FIG. In FIG. 4, digital encoding according to 23-bit data will be described as an example. When the CPU 53 receives 23-bit information from the watt-hour meter 40, the CPU 53 generates a digital signal as shown in FIG. That is, the CPU 53 first generates an H level signal for about 1 second. This H level signal becomes the header. Next, the CPU 53 generates an L level signal of about 0.25 seconds, and further, the CPU 53 generates an H level or L level signal of about 0.5 seconds according to the first bit information from the watt-hour meter 40. . Next, the CPU 53 outputs an L level signal of about 0.25 seconds, an H level or L level signal of about 0.5 seconds corresponding to the information of the second bit from the watt-hour meter 40, and about 0.25 seconds. The L level signal, the H level or L level signal of about 0.5 seconds corresponding to the third bit information from the watt-hour meter 40, and the L level signal of about 0.25 seconds are generated in this order.

  Thereafter, the CPU 53 generates an H level or L level signal of about 3.5 seconds and an L level signal of about 0.25 seconds in accordance with information on the 4th to 8th bits from the watt hour meter 40. . Then, the CPU 53 generates an H level or L level signal of about 10.25 seconds and an L level signal of about 0.25 seconds in accordance with the information of the 9th to 22nd bits from the watt hour meter 40. .

  Next, the CPU 53 generates an H level or L level signal of about 0.5 seconds, an L level signal of about 0.25 seconds, and an H level signal of about 1 second in accordance with the parity bit. The last H level signal is a header.

  Here, the 1st to 3rd bits are information indicating the relationship between the power consumption of the watt hour meter 40 and the demand, the 4th to 8th bits are information on demand measurement time, and the 9th to 22nd bits are predicted power. Value information.

  FIG. 5 is a diagram showing a state of digital encoding according to the power consumption, (a) shows a state of digital encoding when the amount of power used has room for demand, and (b) The state of digital encoding when the amount of power used approaches the demand is shown, and (c) shows the state of digital encoding when the amount of power used exceeds the demand.

  As shown in FIG. 5A, when the amount of power used is sufficient for demand, the CPU 53 of the demand detector 50 outputs a normal state signal. That is, the CPU 53 outputs an L level signal of about 0.25 seconds after the H level header, and further outputs an H level signal of about 0.5 seconds. Thereafter, the CPU 53 outputs an L level signal until reaching the fourth to eighth bit information.

  Further, as shown in FIG. 5B, when the amount of power used approaches the demand, the CPU 53 outputs a caution warning signal. That is, the CPU 53 outputs an L level signal of about 0.25 seconds after the H level header, and further outputs an H level signal of about 0.5 seconds. Thereafter, the CPU 53 outputs an L level signal of about 0.25 seconds, and further outputs an H level signal of about 0.5 seconds. An L level signal is output until the fourth to eighth bits of information are reached.

  Further, as shown in FIG. 5C, when the amount of power used exceeds the demand, the CPU 53 outputs a warning alarm signal. That is, the CPU 53 outputs an L level signal of about 0.25 seconds after the H level header, and further outputs an H level signal of about 0.5 seconds. Thereafter, the CPU 53 outputs an L level signal of about 0.25 seconds, and further outputs an H level signal of about 0.5 seconds. The CPU 53 outputs an L level signal for about 0.25 seconds, an H level signal for about 0.5 seconds, and an L level signal for about 0.25 seconds in this order. Thereafter, a signal corresponding to the information of the 4th to 8th bits is output.

  Each signal shown in FIGS. 5A to 5C is generated in real time according to a change in the amount of power used, and the demand detector 50 determines the amount of power used at that time. The signal is constantly transmitted continuously.

  6A and 6B are diagrams illustrating how the first modulation unit 54a and the second modulation unit 54b in FIG. 2 perform modulation. FIG. 6A illustrates a signal digitally encoded by the CPU 53, and FIG. 6B illustrates the carrier frequency. (C) shows the frequency signal after modulating the carrier frequency of (b) with the signal of (a). In FIG. 6, description will be made taking 5-bit data as an example.

  As shown in FIG. 6A, it is assumed that the CPU 53 outputs a header and a 5-bit H level signal. Further, it is assumed that the carrier frequency as shown in FIG. 5B is generated by the first crystal oscillator 52a and the second crystal oscillator 52b. At this time, the first modulation unit 54a and the second modulation unit 54b superimpose a carrier frequency on the header and the 5-bit H level signal to generate a frequency signal as shown in FIG.

  FIG. 7 is a diagram illustrating a state of demodulation by the demodulation unit 74 of FIG. 3, (a) shows the frequency signal 1, (b) shows a signal after demodulating the frequency signal 1, and (c) shows The frequency signal 2 is shown, (d) shows the signal after demodulating the frequency signal 2, (e) shows the frequency signal 3, and (f) shows the signal after demodulating the frequency signal 3. In FIG. 7, description will be made taking 5-bit data as an example.

  As shown in FIG. 7A, when a frequency signal 1 obtained by superimposing a carrier frequency on a header and a 5-bit H level signal is input, the demodulator 74 removes the carrier frequency, as shown in FIG. 7B. In addition, digital data consisting of a 5-bit H level signal is created.

  Further, as shown in FIG. 7B, when the frequency signal 2 obtained by superimposing the carrier frequency on the header, the 1-bit H level signal, and the 4-bit L level signal is input, the demodulator 74 removes the carrier frequency. As shown in FIG. 7 (d), digital data consisting of a 1-bit H level signal and a 4-bit L level signal is created.

  Further, as shown in FIG. 7E, when the frequency signal 3 obtained by superimposing the carrier frequency on the header, the 2-bit H level signal and the 3-bit L level signal is input, the demodulator 74 removes the carrier frequency. As shown in FIG. 7F, data in a digital format composed of a 2-bit H level signal and a 3-bit L level signal is created.

  Next, the operation of the ground return path transport system 1 according to the present embodiment will be described with reference to FIGS.

  First, the input interface unit 51 of the demand detector 50 inputs information from the watt-hour meter 40. Thereafter, the CPU 53 performs digital encoding according to the information input from the watt-hour meter 40.

  Next, the first modulation unit 54a and the second modulation unit 54b generate a frequency signal. At this time, the first modulation unit 54a generates a 1075 Hz frequency signal by superimposing a 1075 Hz carrier frequency on a signal digitally encoded by the CPU 53, for example. In addition, the second modulation unit 54b generates a 1770 Hz frequency signal by superimposing a 1770 Hz carrier frequency on a signal digitally encoded by the CPU 53, for example. Next, the synthesizer 55 synthesizes two frequency signals. Then, the power amplifier 56 amplifies the synthesized frequency signal.

  Next, the demand detector 50 injects the frequency signal amplified by the power amplifier 56 into the first ground line 31 through the transformer 60. As described above, the demand detector 50 injects a plurality of frequency signals into one piece of information transmitted from the watt-hour meter 40.

  Thereafter, the frequency signal injected into the first ground line 31 reaches the second ground line 32 via the ground electric circuit 21 of the low piezoelectric path 20 and is input to the receiving unit 71 of the receiver 70. Then, the frequency signal passes through the receiving unit 71 and reaches the input unit 72. The input unit 72 amplifies the frequency signal attenuated by passing through the low piezoelectric path 20, and passes the amplified frequency signal to the first and second band pass filters 73a and 73b.

  Next, the first band pass filter 73a passes only a signal having a frequency of about 1075 Hz, for example, and cuts a signal having another frequency. As a result, only a signal having a frequency of around 1075 Hz is extracted from the synthesized signal with superimposed noise. The second band pass filter 73b passes only a signal having a frequency around 1770 Hz, for example, and cuts a signal having another frequency. As a result, only a signal having a frequency of around 1770 Hz is extracted from the synthesized signal with superimposed noise.

  Thereafter, the demodulator 74 demodulates the frequency signal that has passed through the first bandpass filter 73a and the second bandpass filter 73b. At this time, the demodulator 74 removes the carrier frequency from the frequency signal. Then, the demodulation unit 74 transmits a signal from which the carrier frequency has been removed to the CPU 75. Next, the CPU 75 analyzes the signal from which the carrier frequency has been removed, reads the content of the information transmitted from the demand detector 50, and outputs a signal corresponding to the read content information via the output interface unit 76. To 80.

  As a result, the alarm device 80 enters a standby state or performs an alarm operation. For example, when a normal state signal is output from the demand detector 50, the alarm device 80 enters a standby state without performing an alarm operation. Further, when a warning alarm signal is output from the demand detector 50, the alarm device 80 performs an alarm operation indicating that the amount of power used is approaching demand, and when a warning alarm signal is output, the alarm device 80 An alarm operation is performed to indicate that the usage has exceeded demand.

  As described above, the earth return route transport system 1 according to the present embodiment is configured to transmit a plurality of frequency signals. Thereby, in the earth return path conveyance system 1 which concerns on this embodiment, the reliability of conveyance communication will be improved. That is, the reception abnormality in the receiver 70 is likely to be caused by noise having a frequency that is the same as or close to the frequency of the signal transmitted from the demand detector 50. For this reason, by injecting a plurality of frequency signals into the first ground line 31, there is a possibility that a certain frequency signal may be abnormally received due to noise of a specific frequency. It becomes difficult to become reception abnormality by noise. That is, by injecting a plurality of frequency signals into the first ground line 31, any one of the frequency signals is easily received normally by the receiver 70. For this reason, in the earth return path conveyance system 1 which concerns on this embodiment, the reliability of conveyance communication can be improved.

  FIG. 8 is a graph showing the noise resistance characteristics of the ground return route transport system 1 according to the present embodiment, and FIG. 9 is a diagram showing the reception result of the frequency signal. In the graph of FIG. 8, the vertical axis represents the noise tolerance, and the horizontal axis represents the noise frequency.

  As shown in FIG. 8, it can be seen that the frequency signal of 1075 Hz is vulnerable to noise of 1075 Hz. This is because if the 1075 Hz noise is superimposed, the first band pass filter 73a cannot remove the noise. Similarly, it can be seen that the frequency signal of 1770 Hz is weak to noise of 1770 Hz because noise cannot be removed by the second band pass filter 7ba when noise of 1770 Hz is superimposed.

  However, as shown in FIG. 8, a region where one frequency signal is vulnerable to noise (ie, a region where the tolerance is less than about 89 dB) is a region where the other frequency signal is resistant to noise (ie, a region where the tolerance is about 89 dB). It has become. For this reason, as shown in FIG. 9, the transport communication is good.

  That is, as shown in FIG. 8, for example, if the noise of about 975 Hz is 75 dB (point a), both frequency signals of 1075 Hz and 1770 Hz are received well as shown in FIG. The result is “good”. For example, when the noise at about 1400 Hz is 75 dB (point c), the communication result by the two frequencies is “good”.

  For example, when the noise of about 1100 Hz is 85 dB (point b), as shown in FIG. 9, the frequency signal of 1770 Hz is received well, although the frequency signal of 1075 Hz is not received well. For this reason, the communication result by the two frequencies is “good”. Further, for example, when the noise of about 1800 Hz is 85 dB (point d), as shown in FIG. 9, the 1770 Hz frequency signal is not received well, but the 1075 Hz frequency signal is received well. For this reason, the communication result by the two frequencies is “good”.

  FIG. 10 is a second graph showing the noise resistance characteristics of the ground return path transport system 1 according to the present embodiment. In the graph of FIG. 10, the vertical axis represents the noise tolerance, and the horizontal axis represents the noise frequency.

  As shown in FIG. 10, it is desirable that the frequency of the frequency signal transmitted by the demand detector 50 has a relationship as shown in FIG. Specifically, in the two frequency signals, in the correlation indicating the correlation between the noise frequency and the noise resistance of the frequency signal (that is, the correlation shown in FIG. 10), the noise resistance of each frequency signal is less than 89 dB. It is desirable that the overlapping portion of the noise frequency becomes less than 600 hertz. This is because the complexity of the circuit can be suppressed and the cost of the device can be reduced. That is, when the frequency difference is less than 600 Hz as described above, the frequency difference between the two frequency signals becomes small. Here, if the frequency difference is increased excessively, many parts with different ratings and types are used in the receiver 70, which may complicate the circuit and become an expensive device. However, since the frequency difference between the two frequency signals is small, the complexity of the circuit can be suppressed and the cost of the device can be reduced.

  Furthermore, two frequency signals have a correlation indicating the correlation between the frequency of noise and the noise tolerance of the frequency signal. With respect to a noise frequency at which the noise tolerance of one frequency signal is less than 80 decibels, the noise tolerance of the other frequency signal Is desirably 80 dB or more.

This is because noise resistance is at least 80 decibels and communication reliability can be improved.

  The receiver 70 has a function of determining whether information from the demand detector 50 is normally received based on the reception result of each frequency signal. Hereinafter, this function will be described.

  FIG. 11 is a diagram illustrating an example when it is determined whether or not information from the demand detector 50 has been normally received. FIG. 11A illustrates a first example, and FIG. 11B illustrates a second example. (C) shows a third example.

  As shown in FIG. 11A, for example, the receiver 70 receives and analyzes a frequency signal of 1075 Hz, and as a result, determines that the information is warning alarm information. In addition, as a result of receiving and analyzing the frequency signal of 1770 Hz, the receiver 70 determines that the information is information of a warning alarm as well. In this case, the CPU 75 of the receiver 70 determines that the information from the demand detector 50, that is, the warning alarm information has been normally received.

  As shown in FIG. 11B, it is assumed that the receiver 70 has received and analyzed a frequency signal of 1075 Hz, and as a result, has determined that the information is warning alert information. On the other hand, as a result of receiving and analyzing the frequency signal of 1770 Hz, the receiver 70 is unknown what information is the information. In this case, the receiver 70 determines that the warning alert information from the demand detector 50 is not normally received.

  After that, the frequency signal is transmitted again from the demand detector 50, and the receiver 70 receives the frequency signal of 1075 Hz and analyzes it, and as a result, determines that the information is information of a warning alarm. On the other hand, as a result of receiving and analyzing the frequency signal of 1770 Hz, the receiver 70 is unknown what information is the information. In this case, the CPU 75 of the receiver 70 cannot receive the 1770 Hz frequency signal due to noise. However, since the 1075 Hz frequency signal continuously indicates the warning alarm information, the warning alarm information is normal. Is determined to have been received.

  Further, as shown in FIG. 11C, it is assumed that the receiver 70 has received and analyzed the frequency signal of 1075 Hz, and as a result, has determined that the information is information of a warning alarm. On the other hand, as a result of receiving and analyzing the frequency signal of 1770 Hz, the receiver 70 is unknown what information is the information. In this case, the receiver 70 determines that the warning alert information from the demand detector 50 is not normally received.

  Thereafter, the frequency signal is transmitted again from the demand detector 50, and the receiver 70 receives and analyzes the frequency signal of 1075 Hz, and as a result, it is unknown what information the information is. On the other hand, as a result of receiving and analyzing a frequency signal of 1770 Hz, the receiver 70 determines that the information is warning alarm information. In this case, the CPU 75 of the receiver 70 is warned because the frequency signal of 1075 Hz indicates the warning alarm information at the first reception and the frequency signal of 1770 Hz indicates the warning alarm information at the second reception. Confirm that the alarm information has been received normally. Note that the case shown in FIG. 11C occurs when the noise frequency fluctuates for some reason.

  Thus, the receiver 70 determines whether or not the information has been normally received from the reception results of the two frequency signals. In addition, when the receiver 70 determines that the signal cannot be normally received, it is desirable to notify the fact of the conveyance abnormality, such as turning on a lamp or the like indicating the conveyance abnormality.

  In this way, according to the ground return transportation system 1 according to the first embodiment, the demand detector 50 injects a plurality of frequency signals for one piece of information. Here, the reception abnormality in the receiver 70 is likely to be caused by noise having a frequency that is the same as or close to the frequency of the signal transmitted from the demand detector 50. For this reason, by injecting a plurality of frequency signals into the first ground line 31, there is a possibility that a certain frequency signal may be abnormally received due to noise of a specific frequency. It is difficult for reception to be abnormal due to noise, and any frequency signal is likely to be normally received by the receiver 70.

  Further, the receiver 70 determines whether or not the information has been normally received based on the reception result of each frequency signal. Therefore, for example, when a certain frequency signal cannot be received but another frequency signal can be received, the receiver cannot receive only the certain frequency signal due to noise of a specific frequency, and the other frequency signal is not received. Since it can be determined that the indicated information can be normally received, it can be determined that there is no conveyance abnormality.

  The above point is that information is transmitted continuously and periodically accurately, and in the case of a device such as a demand detector that aggregates and uses a plurality of pieces of information, the information is stably and periodically transmitted. This is particularly effective in that transmission and reception are possible.

  Accordingly, it is possible to improve the reliability of the transport communication and determine the state of the transport abnormality.

  Further, according to the first embodiment, the overlapping portion of the noise frequency where the noise tolerance of each frequency signal is less than 89 decibels is less than 600 hertz. Thus, since the overlapping portion is less than 600 Hz, the frequency difference between the two frequency signals is small. Here, if the frequency difference is increased excessively, many parts with different ratings and types are used in the receiver 70, which may complicate the circuit and become an expensive device. However, in the first embodiment, since the frequency difference between the two frequency signals is reduced, the circuit complexity can be suppressed and the cost of the device can be reduced.

  Further, according to the first embodiment, for a noise frequency at which the noise tolerance of one frequency signal is less than 80 decibels, the noise tolerance of the other frequency signal is 80 decibels or more. For this reason, noise tolerance is at least 80 decibels for any frequency signal, and communication reliability can be improved.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. Although the structure of the earth return transportation system 2 which concerns on 2nd Embodiment is the same as that of 1st Embodiment (FIGS. 1-3), the processing content differs. Hereinafter, description of parts common to the first embodiment will be omitted, and differences will be described.

  FIG. 12 is a diagram showing processing of the demand detector 50 of the ground return transportation system 2 according to the second embodiment of the present invention. FIG. 12A is a first example of encoding of the CPU 53 according to the first embodiment. (B) shows the 2nd example of the encoding of CPU53 which concerns on 1st Embodiment, (c) has shown the synthetic | combination result of the synthetic | combination part 55 which concerns on 1st Embodiment. Further, (d) shows a first example of encoding of the CPU 53 according to the second embodiment, (e) shows a second example of encoding of the CPU 53 according to the second embodiment, and (f) shows The composition result of composition part 55 concerning a 2nd embodiment is shown. The synthesizer 55 synthesizes the frequency signal. In FIGS. 12C and 12F, the frequency signal is shown in digital form for easy understanding.

  In the first embodiment, for example, when the power consumption is sufficient for the demand, the demand detector 50 generates a header and one H level signal (FIGS. 12A and 12B). . The combining unit 55 of the demand detector 50 combines these two. For this reason, as shown in FIG. 12C, the voltage value of the header and the H level signal is doubled, and a power supply capable of outputting the doubled voltage is required.

  On the other hand, in the second embodiment, for example, when the amount of power used is more than the demand, the demand detector 50 generates a header and one H level signal (FIG. 12 (d)). However, on the other hand, the demand detector 50 generates a signal obtained by inverting the digitally encoded signal of FIG. 12D (FIG. 12E). That is, when one frequency signal is at a high level, the other frequency signal is at a low level. For this reason, as shown in FIG. 12 (f), when both frequency signals are synthesized, the voltage value is not doubled, and a power supply capable of outputting a doubled voltage is not required. Thereby, cost reduction can be aimed at.

  As described above, according to the ground return transportation system 2 according to the second embodiment, the reliability of the transportation communication can be improved and the state of the transportation abnormality can be determined similarly to the first embodiment. In addition, the complexity of the circuit can be suppressed and the cost of the device can be reduced. Further, communication reliability can be improved.

  Furthermore, according to the second embodiment, when one frequency signal of one information is at a high level, the other frequency signal is at a low level. Here, when one frequency signal is at a high level and the other frequency signal is at a high level, when both signals are synthesized and output, the voltage is doubled, and a power supply capable of outputting twice that voltage. Will be necessary. However, when one frequency signal is at a high level, the other frequency signal is at a low level. Therefore, even if both signals are combined and output, a power supply capable of outputting twice the voltage is not doubled. This is not necessary, and the cost can be reduced.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. As shown in FIG. 13, this earth return transportation system 101 is applied to an insulation monitoring device, and includes an insulation monitoring device (Igr detector) 140, a superimposing transformer 150, and a zero-phase current transformer (ZCT) 160. And a receiver 170 and an alarm device 180. Others are substantially the same as those in the first embodiment shown in FIG. 1, and therefore, by adding the reference numerals obtained by adding 100 to the reference numerals used in FIG.

  The insulation monitoring device (Igr detector) 140 is a general one. In other words, the superimposing transformer 150 superimposes the monitoring signal on the equipment via the first grounding line (B-type grounding line) 131, and the superposed monitoring signal is input from the first grounding line 131, and the first grounding line is connected from the entire equipment. The current flowing through 131 is detected by a zero-phase current transformer (ZCT) 160, and the current based on the monitoring signal contained therein is measured.

  In the case of the insulation monitoring device 140, not only the monitoring signal but also a current measurement result based on the insulation monitoring is injected into the first ground line (B-type ground line) 131 through the superimposing transformer 150. That is, the insulation monitoring device 140 outputs the current measurement result obtained by the insulation monitoring as a digital signal, while transmitting a transmission signal obtained by modulating two carrier waves having different frequencies with n-bit data pulses based on the output signal. In order to propagate the low voltage side electric circuit 120 of the transformer T, it functions as a transmitter that injects into the B type ground line (first ground line) 131 and transmits.

  That is, the insulation monitoring device 140 includes an Igr detector unit functioning as a general Igr detector and two carrier waves of frequencies A and B based on an output signal (current measurement result) from the Igr detector unit. The transmitter unit is configured to inject a transmission signal modulated by each bit data pulse into the first ground line (B-type ground line) 131 via the superimposing transformer 150.

  Here, the transmitter unit of the insulation monitoring device 140 will be described.

  The two carrier waves modulated by the transmitter unit with n-bit data pulses based on the output signal (current measurement result) from the Igr detector unit can ignore the influence of frequency noise superimposed on each other. Only set at least the frequency away. That is, as shown in FIG. 8 described in the first embodiment, even when noise is applied to the frequency A or B of one of the carriers, the other carrier is not affected by the frequency noise at all. It is set to a frequency B or A that is at least substantially unnecessary.

  Further, as shown in FIG. 14, the transmitter unit receives information on the first carrier A (see (a)) of the two carriers of frequencies A and B, with the presence or absence of a high-level pattern. A first frequency signal (see (c)) modulated with an n-bit data pulse consisting of one pulse train (see (b)) and a second carrier wave (see (d)) as shown in FIG. The first pulse train (see (b)) is level-inverted and modulated by an n-bit inverted data pulse consisting of a second pulse train (see (e)) in which information is given to the presence or absence of a low-level pattern. As shown in FIG. 16, the second frequency signal (see (f)) is synchronized with each other, and the high frequency equivalent region, the low level equivalent region of the first frequency signal (see (c)), Low level equivalent region of the second frequency signal (see (f)) Synthesized signal obtained by superimposing a high level corresponding regions respectively ((g) refer), and transmits a transmission signal.

  That is, in the case of this earth return transportation system 101, as in the case of the second embodiment, the region corresponding to the high level of the first frequency signal and the region corresponding to the low level of the second frequency signal are overlapped, and Since a composite signal obtained by superimposing the low-level equivalent region of the first frequency signal and the high-level equivalent region of the second frequency signal is transmitted as a transmission signal, the output voltage of the composite signal, and thus the output voltage of the transmission signal Does not increase from the output voltage in the case of the first frequency signal alone or the second frequency signal alone, and an increase in cost due to an increase in the output voltage can be avoided in advance.

  The receiver 170 receives the transmission signal as shown in FIG. 17, and passes through the first filter that passes the first carrier and the second filter that passes the second carrier as shown in FIG. The first frequency signal (see (a)) and the second frequency signal (see (b)) are demodulated separately, as shown in FIG. An n-bit data pulse is generated based on at least one of the second pulse trains (see (b)).

  The receiver 170 demodulates the first frequency signal and the second frequency signal separately when demodulating the first frequency signal and the second frequency signal that have passed through the first filter and the second filter, respectively. Each envelope is detected.

  Further, when the receiver 170 demodulates and envelopes the first frequency signal and the second frequency signal to determine the high / low level of the demodulated output, the difference between the high level and the low level is detected. The threshold level for discrimination is varied accordingly.

  Furthermore, as shown in FIG. 20, the receiver 170 demodulates the first frequency signal and detects a pulse train corresponding to the first pulse train obtained by envelope detection (see (a)), and the second When a pulse train (see (b)) corresponding to the second pulse train obtained by demodulating the frequency signal and detecting the envelope (see (b)) is analyzed at a predetermined sampling period, and the header is confirmed by any one of the pulse trains, Data collection is started in both the pulse train corresponding to the first pulse train and the pulse train corresponding to the second pulse train.

[Fourth Embodiment]
Next explained is the fourth embodiment of the invention. This ground return transport system 102 is for when more than two carriers are used. In this case, the transmitter divides a plurality of carrier waves into two, one frequency signal obtained by modulating one carrier wave of each set with an n-bit data pulse, and inverted data obtained by inverting the level of the n-bit data pulse. The other frequency signal obtained by modulating the other carrier wave with a pulse is synchronized with each other to be combined to form a combined signal, and the combined signal of each set is temporally arranged to generate a transmission signal.

  As shown in FIG. 21, for example, when using carrier waves of four different frequencies A, B, C, and D, the first frequency signal A obtained by modulating the first carrier wave with the data pulse and the level inversion of the data pulse are performed. The second frequency signal B obtained by modulating the second carrier wave with the inverted data pulse is combined with each other in synchronism with each other to obtain a combined signal A + B. Similarly, the third frequency signal C obtained by modulating the third carrier wave with the data pulse and the fourth frequency signal D obtained by modulating the fourth carrier wave with the inverted data pulse obtained by inverting the level of the data pulse are synchronized with each other. The combined signal C + D is superimposed. Then, the combined signal A + B and the combined signal C + D are arranged temporally to generate a transmission signal.

  When both the insulation monitoring device (Igr detector) 140 and the demand monitoring device 50 are used, the transmission of the demand monitoring device 50 is outside the two carriers used by the transmission unit of the insulation monitoring device (Igr detector) 140. It is preferable to set the frequencies of two carrier waves used by the unit.

  In this case, the ground return transportation system includes an insulation monitoring device 140 and a transmission signal for insulation monitoring obtained by modulating two carrier waves having different frequencies with n-bit data pulses based on an output signal of the insulation monitoring device 140. Insulation monitoring transmitter that injects and transmits to the B type ground line 131 of T, and the insulation monitoring transmission signal from the ground phase to the ground of the low-voltage side electric circuit of the transformer T, and receives this received signal into two carrier waves Demand monitoring is performed on two carriers whose frequencies are selected outside the both carriers used by the insulation monitoring receiver that demodulates and generates n-bit data pulses, the demand monitoring device 50, and the insulation monitoring transmitter. For demand monitoring, a demand monitoring transmission signal modulated by an m-bit data pulse based on the output signal of the device 50 is injected into the B-type ground line 31 of the transformer T and transmitted. Demand monitor that receives a transmission signal for demand monitoring from the ground and the ground phase of the low-voltage circuit of transformer T and the ground, and demodulates the received signal separately for each of the two carrier waves to generate an m-bit data pulse. And a receiving unit.

  As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to the above-described embodiments. Modifications may be made without departing from the spirit of the present invention, and the embodiments may be combined. It may be.

  For example, in the above embodiment, the demand detector 50 injects two frequency signals into the first ground line 31, but the present invention is not limited thereto, and three or more frequency signals may be injected.

  In the above embodiment, data of 5 bits or 23 bits is described as an example. However, the amount of information is not limited to 5 bits or 23 bits, and the number of bits may be changed as appropriate. Furthermore, in the above embodiment, the determination example of whether or not there is a conveyance abnormality is shown in FIG. 11, but the determination of the conveyance abnormality is not limited to the example shown in FIG. 11 and whether or not there is a conveyance abnormality under conditions other than the example shown in FIG. You may make it determine.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows 1st Embodiment of the earth return path conveyance system by this invention. It is a detailed block diagram of the demand detector of FIG. It is a detailed block diagram of the receiver of FIG. It is a figure explaining the digital encoding by CPU of FIG. It is a figure which shows the mode of the digital encoding according to electric power consumption, (a) shows a mode of digital encoding when used electric energy has a margin with respect to a demand, (b) shows the used electric energy for demand. FIG. 4C shows a state of digital encoding when the power consumption exceeds the demand. It is a figure which shows the mode of the modulation | alteration by the 1st modulation | alteration part and 2nd modulation | alteration part of FIG. 2, (a) shows the signal digitally encoded by CPU, (b) shows a carrier frequency, (c) is The frequency signal after modulating the signal of (a) is shown. It is a figure which shows the mode of a demodulation by the demodulation part of FIG. 3, (a) shows the frequency signal 1, (b) shows the signal after demodulating the frequency signal 1, (c) shows the frequency signal 2 , (D) shows the signal after demodulating the frequency signal 2, (e) shows the frequency signal 3, and (f) shows the signal after demodulating the frequency signal 3. It is a graph which shows the noise-proof characteristic of the earth return path conveyance system which concerns on this embodiment. It is a figure which shows the reception result of a frequency signal. It is a 2nd graph which shows the noise tolerance characteristic of the earth return path conveyance system which concerns on this embodiment. It is a figure which shows an example when determining whether the information from a demand detector was received normally, (a) shows a 1st example, (b) shows a 2nd example, (c ) Shows a third example. It is a figure which shows the process of the demand detector of 2nd Embodiment of the earth return transportation system by this invention, (a) shows the 1st example of encoding of CPU which concerns on 1st Embodiment, (b) The 2nd example of encoding of CPU which concerns on 1st Embodiment is shown, (c) shows the synthetic | combination result of the synthetic | combination part which concerns on 1st Embodiment, (d) is encoding of CPU which concerns on 2nd Embodiment. (E) shows a second example of encoding of the CPU according to the second embodiment, and (f) shows a synthesis result of the synthesis unit according to the second embodiment. It is a block diagram which shows 3rd Embodiment of the earth return path conveyance system by this invention. It is a figure which shows the transmitter side (a) 1st carrier wave, (b) 1st pulse train, (c) 1st frequency signal. It is a figure which shows the (d) 2nd carrier wave, (b) 1st pulse train, (e) 2nd pulse train, and (f) 2nd frequency signal by the side of a transmitter. It is a figure which shows the (c) 1st frequency signal, (f) 2nd frequency signal, and (g) synthetic | combination signal by the side of a transmitter. It is a figure which shows the transmission signal which the receiver side receives. It is a figure which shows the (a) 1st frequency signal which passed the 1st filter by the side of a receiver, and the (b) 2nd frequency signal which passed the 2nd filter. (A) First pulse train obtained by demodulating and detecting envelope on the receiver side, (b) Second pulse obtained by demodulating and detecting envelope of the second frequency signal It is a figure which shows a pulse train. It is explanatory drawing about the sampling of the pulse train corresponded to (a) 1st pulse train on the receiver side, and (b) 2nd pulse train. It is explanatory drawing which produces | generates a synthetic signal using four carrier waves from which frequencies mutually differ, and produces | generates a transmission signal.

Explanation of symbols

1, 2, 101, 102 Ground return transportation system 10, 110 High piezoelectric path 20, 120 Low piezoelectric path 21, 121 Grounding path 22, 122 Non-grounding path 31, 131 First grounding line 32, 132 Second grounding line 40 Energy meter 50 Demand detector (demand monitoring device)
51 Input Interface Unit 52a First Crystal Oscillator 52b Second Crystal Oscillator 53 CPU
54a First modulation unit 54b Second modulation unit 55 Combining unit 56 Power amplification unit 60 Transformer 70, 170 Receiver 71 Reception unit 72 Input unit 73a First bandpass filter 73b Second bandpass filter 74 Demodulation unit 75 CPU
76 Output interface unit 80, 180 Alarm 140 Insulation monitoring device (Igr detector)
150 Superimposed transformer 160 Zero-phase current transformer (ZCT)

Claims (5)

In a ground return transportation system that injects a transmission signal into a B-type ground line of a transformer and receives the transmission signal from between the ground phase of the low-voltage side electric circuit of the transformer and the ground.
A first frequency signal obtained by amplitude-modulating a first carrier wave of two carrier waves having different frequencies with an n-bit data pulse composed of a first pulse train in which information is given to the presence or absence of a high-level pattern; And a second frequency signal obtained by amplitude-modulating an n-bit inverted data pulse composed of a second pulse train in which information is given to the presence or absence of a low level pattern by inverting the level of the first pulse train. And a synthesized signal that is synchronized with each other and in which the region corresponding to the high level and the region corresponding to the low level of the first frequency signal and the region corresponding to the low level and the region corresponding to the low level of the second frequency signal are superimposed. A transmitter for transmitting as a transmission signal;
The first frequency signal and the second frequency signal that have received the transmission signal and passed through a first filter that passes the first carrier wave and a second filter that passes the second carrier wave, respectively. A receiver that demodulates and generates the data pulses based on either the first pulse train or the second pulse train obtained;
A ground return transportation system characterized by comprising: 2. The transmitter according to claim 1 , wherein the transmitter generates the data pulse by converting the information into a predetermined format based on information output from an information output unit such as a demand monitoring device or an insulation monitoring device. Earth return transportation system described. When the receiver demodulates the first frequency signal and the second frequency signal that have passed through the first filter and the second filter, respectively, the first frequency signal and the second frequency signal The ground return transportation system according to claim 1, wherein each of the frequency signals is detected by envelope detection . When the receiver demodulates the first frequency signal and the second frequency signal separately to determine the high / low level of the demodulated output, the determination is performed according to the difference between the high level and the low level. The ground return transportation system according to any one of claims 1 to 3, wherein a threshold level for the slab is variable . The receiver corresponds to a pulse train corresponding to the first pulse train obtained by demodulating the first frequency signal, and to the second pulse train obtained by demodulating the second frequency signal. The pulse train to be analyzed is analyzed at a predetermined sampling period, and when the header is confirmed in any one of the pulse trains, data is collected in both the pulse train corresponding to the first pulse train and the pulse train corresponding to the second pulse train. The ground return transportation system according to any one of claims 1 to 4, wherein the system is started.

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