JP2015032947A - Automatic meter reading system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve power line communication using a PLC modem between a power meter and a HEMS server and to improve a yield of meter reading data by reducing communication failures at a meter reading system side.SOLUTION: An automatic meter reading system 1 comprises: a PLC modem 11 connected with a meter reading server 7 that collects meter reading data from power meters 12a-12d; PLC modems 13a-13d for communicating with the PLC modem 11 via a power line 5; a PLC modem 18 connected with a HEMS server 17; and PLC modems 14a-14d for communicating with the PLC modem 18 via the power line 5. An OFDM subcarrier group used for communication between the PLC modem 11 and the PLC modems 13a-13d is set in a frequency range of f-f, and an OFDM subcarrier group used for communication between the PLC modem 18 and the PLC modem 14a is set in a frequency range of f-f. The frequency fis higher than the frequency f, and the frequency fis equal to or higher than the frequency f.

Description

  The present invention relates to a power usage metering system using PLC (Power Line Communication).

  In recent years, in electric power companies, introduction of an automatic meter-reading system that collects the amount of power used by each consumer from a remote location is being advanced (see, for example, Patent Document 1).

  In the automatic meter reading system, a master PLC modem (hereinafter referred to as a master meter PLC modem for meter reading) is attached to a utility pole or the like, and a slave PLC modem for transmitting meter reading data to the master PLC modem (hereinafter referred to as a slave meter slave meter). A PLC modem) is built into each consumer's power meter. Since these PLC modems use a power line connecting a power pole and a power meter as a communication path, there is no need to newly lay a communication line, which is very advantageous in terms of introduction cost.

  On the other hand, interest in power saving is increasing from an ecological point of view, and an increasing number of homes are introducing HEMS (Home Energy Management System) that realizes optimal energy management using IT (for example, Patent Document 2).

  In HEMS, a HEMS server as a central control device is used. The HEMS server automatically controls the home appliances such as air conditioners while monitoring the operating status and power consumption. According to HEMS, energy supply and demand can be visualized, and electricity can be automatically controlled to save electricity while maintaining the comfort of life.

JP 2011-223063 A JP 2011-254229 A

  In HEMS, there is a demand for acquiring power amount data from a power meter in order to grasp the total power consumption in the home. However, since the electric power meter and the automatic meter reading system are operated under the control of the electric power company and the HEMS is a closed system in each home, mutual cooperation is difficult.

  Therefore, a method in which a HEMS slave PLC modem is installed in the power meter, the HEMS master PLC modem is connected to the HEMS server, and the HEMS server communicates with the power meter regardless of the automatic meter reading system is being studied. . In this case, when a transmission request for power amount data is transmitted from the HEMS server to the power meter via the master-slave device PLC modem, the procedure is previously performed so that the power meter transmits the power amount data to the HEMS server. Just set it up. According to this method, it is possible to use power amount data on the HEMS side.

  However, when the power meter transmits power amount data to the HEMS server via the HEMS slave PLC modem and the HEMS master PLC modem, the transmission signal of the HEMS slave PLC modem is connected to the same power line. There is a problem in that it reaches the PLC modem of the other customer's meter reading. At this time, if another meter-reading slave device PLC modem is communicating with the meter-reading master device PLC modem, there is a possibility that signals interfere with each other, resulting in a communication failure. An automatic meter reading system is required to reliably collect meter reading data with an extremely high yield. To that end, it is necessary to thoroughly eliminate the cause of communication failure.

  Therefore, an object of the present invention is to realize power line communication using a PLC modem between a power meter and a HEMS server, while suppressing a communication failure between a master unit and a slave unit PLC modem on the meter reading system side. An object of the present invention is to provide an automatic meter reading system capable of increasing the yield.

  In order to solve the above-mentioned problems, an automatic meter reading system according to the present invention includes a plurality of power meters that measure power consumption of a power consumer, and a first power amount data collected from each of the plurality of power meters. A first PLC modem connected to the first server, and a plurality of first modems connected to each of the plurality of power meters and communicating with the first PLC modem via a power line. 2 PLC modems, a second server for managing power in customer premises, a third PLC modem connected to the second server, and the second server among the plurality of power meters And a fourth PLC modem that communicates with the third PLC modem via the power line, the first PLC modem, and the second PLC modem. PLC The subcarrier group used for the first communication by the OFDM modulation scheme with the dem is set within the range of the first frequency to the second frequency, and the third PLC modem and the fourth PLC modem The subcarrier group used for the second communication by the OFDM modulation scheme is set within the range of the third frequency to the fourth frequency, and the third frequency is higher than the first frequency, and the fourth frequency Is greater than or equal to the second frequency.

  According to the present invention, since the OFDM subcarrier group used for the second communication on the HEMS side uses only the high frequency side band among the predetermined frequency bands usable for the power line communication, the signal on the transmission path The amount of attenuation can be increased. That is, since the signal level of the subcarrier group when reaching the first and second PLC modems on the meter reading side system side becomes very small, communication on the HEMS side is prevented from interfering with communication on the meter reading system side. be able to. Therefore, while realizing the power line communication using the PLC modem between the first power meter and the second server, the communication error between the first and second PLC modems on the meter reading system side is suppressed and the yield of meter reading data is obtained. Can be increased.

  In the present invention, the second frequency is preferably the same as the fourth frequency. According to this, since OFDM subcarriers are arranged in the entire frequency band that can be used for power line communication, highly reliable power line communication on the meter-reading system side can be realized.

  In the present invention, the second frequency is preferably lower than the fourth frequency, and more preferably lower than the third frequency. When the second frequency is lower than at least the fourth frequency, it is possible to prevent communication on the meter reading system side from interfering with communication on the HEMS side. Therefore, the reliability of communication on the HEMS side can be improved.

  In the present invention, it is preferable that the first frequency is 10 kHz and the fourth frequency is 450 kHz. According to this, it is possible to realize power line communication in accordance with the regulations of the Radio Law in the meter reading system and HEMS.

  In the present invention, the third frequency is preferably higher than 230 kHz. According to this, the OFDM subcarrier group used for the power line communication on the HEMS side can be reliably arranged on the high frequency side, and communication interference on the meter reading system side can be sufficiently prevented.

  In the present invention, the second frequency is preferably 450 kHz. According to this, since OFDM subcarriers are arranged in the entire frequency band that can be used in communication on the meter reading system side, highly reliable power line communication can be realized on the meter reading system side.

  In the present invention, the second frequency is preferably lower than 230 kHz. According to this, the OFDM subcarrier group used for the power line communication on the meter-reading system side can be reliably arranged on the low frequency side, and communication interference on the HEMS side can be reliably prevented.

  The automatic meter reading system according to the present invention further includes a first low-pass filter provided at an input stage of the second PLC modem connected to the power line, and the first low-pass filter has a frequency equal to or higher than the third frequency. It is preferable to remove the signal component. Furthermore, the automatic meter reading system according to the present invention further includes a second low-pass filter provided at an input stage of the first PLC modem connected to the power line, and the second low-pass filter includes the third frequency filter. It is preferable to remove the above signal components. According to this configuration, since the OFDM subcarrier group used in the power line communication on the HEMS side can be removed in advance, the influence of the communication on the HEMS side on the communication on the meter reading system side can be greatly reduced.

  According to the present invention, while realizing power line communication using a PLC modem between a power meter and a HEMS server, a communication failure between a master unit and a slave unit PLC modem on the meter-reading system side is suppressed, and the yield of meter-reading data is increased. It is possible to provide an automatic meter-reading system capable of increasing the speed.

FIG. 1 is a schematic diagram showing a configuration of an automatic meter reading system according to a preferred embodiment of the present invention. FIG. 2 is a block diagram functionally showing the configuration of the PLC modem. FIG. 3 is a conceptual diagram showing an example of the frequency arrangement of OFDM subcarrier groups, where (a) is a subcarrier group used for communication on the meter reading system side, and (b) is a subcarrier group used for communication on the HEMS side. Each is shown. FIG. 4 is a conceptual diagram showing another example of the frequency arrangement of OFDM subcarrier groups, where (a) is a subcarrier group used for communication on the meter reading system side, and (b) is a subcarrier used for communication on the HEMS side. Each group is shown. FIG. 5 is a schematic diagram showing a configuration of an automatic meter reading system according to another preferred embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing a configuration of an automatic meter reading system according to a preferred embodiment of the present invention.

  As shown in FIG. 1, the automatic meter reading system 1 according to the present embodiment is for measuring the amount of power used in each of the doors 10 a to 10 d of the apartment house 10, for example. PLC modem 11 (first PLC modem), meter-reading cordless handset PLC modems 13a-13d (second PLC modem) and HEMS cordless handset PLC modems 14a-14d built in the power meters 12a-12d of each house (Fourth PLC modem), a HEMS server 17 installed in a home where HEMS is introduced, and a HEMS master PLC modem 18 (third PLC modem) for realizing power line communication in the HEMS server 17 I have.

  The electric power supplied from the substation 3 is supplied to the consumer electronics devices 9a to 9d of the respective consumers a to d via the pole transformer 4, the power lead-in wire 5a, the power meters 12a to 12d, and the breakers 16a to 16d. . One communication terminal of the meter-reading master device PLC modem 11 is connected to the meter-reading server 7 (first server) via the optical network 6, for example, and the other communication terminal is connected to the power lead-in line 5a.

  One communication terminal of the meter-reading slave PLC modems 13a to 13d in the power meters 12a to 12d is connected to the controllers 15a to 15d of the corresponding power meters 12a to 12d, respectively, and the other communication terminal is the power lead-in wire 5a. It is connected to the. Similarly, the HEMS handset PLC modems 14a to 14d have one communication terminal connected to the controller 15a to 15d of the corresponding power meter 12a to 12d, and the other communication terminal connected to the power lead-in line 5a. ing.

  In addition, when each cordless handset PLC modem is built in the power meters 12a to 12d, the controllers 15a to 15b are positioned as power meters in a narrow sense with respect to those PLC modems, and the meter reading cordless handset PLC modems 13a to 13d and HEMS The slave unit PLC modems 14a to 14b are connected to a power meter in a narrow sense, and the operation of the controllers 15a to 15d can be considered to be equivalent to the operation of the power meters 12a to 12d.

  In this embodiment, the consumer a has introduced HEMS, and the HEMS server (second server) 17 is installed only in the customer a's home. The HEMS server 17 is connected to individual home appliances 9a in the home via a short-range wireless network 8 such as ZigBee (registered trademark). One communication terminal of the HEMS main unit PLC modem 18 is connected to the HEMS server 17, and the other communication terminal is connected to the power line 5b in the house. In many cases, the HEMS server 17 and the HEMS master PLC modem 18 are installed near a distribution board (not shown).

  FIG. 2 is a block diagram functionally showing the configuration of the PLC modem (power line modem). The PLC modem 20 is a general-purpose one that can be used as the meter-reading master device PLC modem 11, meter-reading slave device PLC modems 13a to 13d, HEMS slave device PLC modems 14a to 14d, and HEMS master device PLC modem 18. It is.

  As shown in FIG. 2, the PLC modem 20 includes a control unit 21, a memory 22, an interface (I / F) 23, a communication unit 24, a modulation unit 25, a transmission unit 26, a demodulation unit 27, a reception unit 28, and a multiplexer 29. Have.

  The control unit 21 acquires various types of information from the host device and controls each unit of the PLC modem 20 based on the acquired information. The host device here refers to the meter-reading server 7 for the meter-reading master device PLC modem 11, and the HEMS server 17, the meter-reading slave device PLC modem 13 a and the HEMS slave device PLC modem for the HEMS master-device PLC modem 18. If it is 14a, it is the controller 15a of the electric power meter 12a.

  The memory 22 is a storage unit that stores data input from the host device in accordance with an instruction from the control unit 21. Various information including setting information is recorded in the memory 22.

  The interface unit 23 is an interface with a higher-level device, receives higher-layer data from the higher-level device, and outputs it to the communication unit 24. Also, the upper layer data is received from the communication unit 24 and is output to the upper device.

  The communication unit 24 is a functional unit that processes transmission / reception signals including a header, and is configured by, for example, a DSP (Digital Signal Processor). Specifically, the upper layer data to be transmitted is received from the interface unit 23, a header including pilot data, a destination MAC address, and the like, and redundant data for error correction are added, and the modulation unit is transmitted as transmission data. 25. In addition, receiving data including a header and higher layer data is input from the demodulator 27, and processing and error correction processing corresponding to the header in the received data are performed, and higher layer data is output to the interface unit 23.

  The modulation unit 25 selects one modulation method from the OFDM modulation method and the phase modulation method in accordance with an instruction from the control unit 21. Then, using one selected modulation method, the carrier signal is modulated based on the transmission data, a predetermined preamble including a known synchronization signal corresponding to the modulation method is added, and the radio wave law enforcement regulations (carrier output) ), The amplitude of the signal is controlled in accordance with the communication method used for the modulation process, and then output to the transmitter 26.

  The transmission unit 26 has a function of converting the signal input from the modulation unit 25 into a signal that can be transmitted to the power line, and then transmitting the signal to the power line. Specifically, the digital signal input from the modulation unit 25 is converted into an analog signal, an unnecessary frequency band component is removed using a bandpass filter, and the multiplexer 29 is further amplified by a predetermined amplification factor. To the power line.

  The receiving unit 28 has a function of receiving a signal arriving on the power line, converting it to a digital signal, and outputting the digital signal to the demodulating unit 27. Specifically, unnecessary high and low frequency components are removed from the signal received through the multiplexer 29 using a band pass filter, further amplified with a predetermined amplification factor, sampled and converted into a digital signal, and demodulator 27.

  The demodulator 27 has a function of demodulating the digital signal input from the receiver 28 using an OFDM modulation scheme and a phase modulation scheme. The demodulator 27 outputs a signal obtained by demodulation to the communication unit 24. The demodulator 27 has a synchronization detection function for detecting a known synchronization signal from the signal input from the receiver 28. The synchronization signal detected here is an OFDM modulation system synchronization signal or a phase modulation system synchronization signal, and the demodulation unit 27 determines a modulation system to be used for demodulation from the detected synchronization signal.

  In the automatic meter reading system, power line communication in a low frequency band of 10 kHz to 450 kHz is used. Among the modulation schemes used in this power line communication, the OFDM (Orthogonal Frequency Division Multiplexing) modulation scheme uses the full band of 10 kHz to 450 kHz and can perform adaptive modulation for each subcarrier. Although it has an advantage that it can realize relatively high-speed and highly reliable communication, the total output value of all subcarriers is limited to 100 mW or less in the Radio Law Enforcement Rules. Further, in the phase modulation method (including phase amplitude modulation method) using 115 kHz or 132 kHz, the carrier wave output is limited to 350 mW or less. The phase modulation method can only communicate at a lower speed than the OFDM modulation method, but is effective for communication in a noisy environment and communication with a distant place. Furthermore, the carrier wave output is limited to 10 mW or less in the spread spectrum method of 200 kHz to 450 KHz, and the carrier wave output is limited to 30 mW or less in the spread spectrum method of 10 kHz to 200 kHz.

  Thus, although the maximum level of the carrier wave output is defined in the power line communication, the meter reading system side usually performs communication at the maximum level for reliable communication. On the other hand, in order to prevent signal interference with the meter reading system side on the HEMS side, it is preferable to output the transmission signal at a lower output level than the transmission signal on the meter reading system side. Is possible. As will be described later, in the communication on the HEMS side, OFDM subcarriers are allocated only to the high frequency side band among the frequency bands that can be used for power line communication, whereby the communication on the HEMS side gives the communication on the meter reading system side. This is because the influence can be reduced.

  In the configuration of FIG. 1, the automatic meter reading method by the electric power company is the same as the conventional one. That is, meter reading data (first power amount data) of each door is measured by the power meters 12a to 12d, transmitted to the meter reading master unit PLC modem 11 via the meter reading slave unit PLC modems 13a to 13d, and further to the optical network. 6 to the meter reading server 7 via The power amount data may be transmitted in response to a request from the meter-reading server 7, or the power meters 12a to 12d may spontaneously transmit at a predetermined timing. Thereby, meter reading data of each house is automatically collected.

  Next, a method for acquiring power amount data by the HEMS server 17 will be described.

  The HEMS server 17 can communicate with the power meter 12a (first power meter) via the HEMS master device PLC modem 18 and the HEMS slave device PLC modem 14a. When the HEMS server 17 transmits a transmission request for the power amount data to the power meter 12a, the power meter 12a returns the power amount data (second power amount data) to the HEMS server 17. However, the power amount data transmitted from the HEMS handset PLC modem 14a is not limited to the power meter 12a, but the power meters of other consumers b to d connected to the same power line 5 (5a, 5b). 12b-12d will be reached. Therefore, if the meter-reading server 7 is communicating with any one of the power meters 12a-12d via the meter-reading master PLC modem 11 and the meter-reading slave PLC modems 13a-13d, the signal interferes and communicates. As described above, it becomes an obstacle. Therefore, in this embodiment, the following measures are taken to suppress such interference.

  FIG. 3 is a conceptual diagram showing an example of the frequency arrangement of OFDM subcarrier groups, where (a) is a subcarrier group used for communication on the meter reading system side, and (b) is a subcarrier group used for communication on the HEMS side. Each is shown.

As shown in FIG. 3A, the subcarrier group used for communication (first communication) between the meter-reading master device PLC modem 11 and the meter-reading slave device PLC modems 13a to 13d has the first frequency f _1. = 10 kHz or more and the second frequency f ₂ = 450 kHz or less. That is, on the meter-reading system side, communication using the full band of 10 to 450 kHz that is permitted in power line communication is performed. In the present embodiment, the bandwidth Bw of each subcarrier = 16.6 kHz and the number of subcarriers N1 = 53.

On the other hand, as shown in FIG. 3B, the subcarrier group used for communication (second communication) between the HEMS master device PLC modem 18 and the HEMS slave device PLC modem 14a is, for example, the third frequency f. ₃ = 275.6 kHz or more and the fourth frequency f ₄ = 450 kHz or less is set. That is, the third frequency f ₃ is set to a frequency higher than the first frequency f _1, the fourth frequency f ₄ is set to the same frequency as the second frequency f _2. The third frequency _{f 3} may be a frequency higher than the first frequency _{f 1} but is preferably higher than 230 kHz. According to this, the OFDM subcarrier group used for the power line communication on the HEMS side can be reliably arranged on the high frequency side, and the interference to the communication on the meter reading system side can be sufficiently prevented.

  The PLC modem on the meter-reading system side employs the OFDM modulation method, and its subcarriers exist over the entire band of 10 kHz to 450 kHz. Therefore, communication can be performed even if some subcarriers are missing and cannot be received. That is, communication is possible in most cases even if 50% or more of the subcarriers do not reach. On the other hand, a signal having a high frequency has a property that it does not reach far compared with a signal having a low frequency. Therefore, in the present embodiment, by using only the high frequency side subcarrier for the communication on the HEMS side, it is intentionally attenuated in the distance so as to reduce the interference with the communication on the meter reading system side.

  Since the transmission signal of the HEMS main unit PLC modem 18 is attenuated when passing through the breaker 16a in the house, even if subcarriers are transmitted using the entire frequency band of 10 kHz to 450 kHz, they are adjacent. Interference with other slave PLC modems hardly occurs. Therefore, in the communication on the HEMS side, at least the HEMS slave PLC modem 14a may adopt the frequency arrangement of the subcarrier group shown in FIG.

  As described above, in the present embodiment, the subcarrier group used for communication on the HEMS side uses only the high frequency side band among the frequency bands of 10 to 450 kHz that can be used for power line communication. It can suppress that communication obstructs communication on the meter-reading system side. Therefore, it is possible to realize an automatic meter reading system in which the yield of meter reading data on the meter reading system side is increased while realizing power line communication using a PLC modem between the power meter and the HEMS server.

  FIG. 4 is a conceptual diagram showing another example of the frequency arrangement of OFDM subcarrier groups, where (a) is a subcarrier group used for communication on the meter reading system side, and (b) is a subcarrier used for communication on the HEMS side. Each group is shown.

As shown in FIG. 4, the frequency arrangement of the OFDM subcarrier group is characterized in that the subcarrier group used for communication on the meter-reading system side is a low-frequency band among the 10 to 450 kHz frequency bands that can be used for power line communication. It is in the point where it is arranged only. Therefore, as shown in FIG. 4A, the subcarrier group used for communication (first communication) between the meter-reading master device PLC modem 11 and the meter-reading slave device PLC modems 13a to 13d is, for example, the first The frequency f ₁ = 10 kHz or more and the second frequency f ₂ = 134.5 kHz or less is set. In the present embodiment, the bandwidth Bw of each subcarrier is 16.6 kHz.

On the other hand, as shown in FIG. 4B, a subcarrier group used for communication (second communication) between the HEMS master PLC modem 18 and the HEMS slave PLC modem 14a is, for example, a third frequency f. ₃ = 325.4 kHz or more and the fourth frequency f4 = 450 kHz or less. That is, the third frequency f ₃ is set to a frequency higher than the second frequency f _2. The second frequency _{f 2} is preferably lower than 230 kHz. According to this, the OFDM subcarrier group used for the power line communication on the meter-reading system side can be reliably arranged on the low frequency side, and communication interference on the HEMS side can be reliably prevented.

  The HEMS slave PLC modem 14a in the power meter 12a uses only the high frequency side of the frequency band of 10 to 450 kHz usable for power line communication when communicating with the HEMS master PLC modem 18. Further, since the communication on the meter reading system side uses only the low frequency side of 10 to 450 kHz, it is possible to suppress interference that causes a failure in the communication on the meter reading system side even during the communication on the HEMS side.

    As described above, in the present embodiment, the subcarrier group used for the communication on the HEMS side uses only the high frequency side of the frequency band of 10 to 450 kHz that can be used for power line communication. Since the subcarrier group used for the communication uses only the low frequency side band in the frequency band of 10 to 450 kHz, it is possible to suppress the transmission signal on the HEMS side from interfering with the communication on the meter reading system side. Therefore, it is possible to realize an automatic meter reading system in which the yield of meter reading data on the meter reading system side is increased while improving the reliability of power line communication using a PLC modem between the power meter and the HEMS server.

  FIG. 5 is a schematic diagram showing a configuration of an automatic meter reading system according to another preferred embodiment of the present invention.

  As shown in FIG. 5, the automatic meter reading system 30 according to the present embodiment is characterized in that a low-pass filter 31a is provided at the input stage of the meter-reading slave devices PLC modems 13a to 13d. Furthermore, a low-pass filter 31b is also provided at the input stage of the meter-reading master device PLC modem 11. These low-pass filters 31b and 31b have filter characteristics for removing the frequency band of the subcarrier on the HEMS side. Other configurations are the same as those of the automatic meter reading system 1 shown in FIG. Although the illustrated low-pass filters 31a and 31b are external to the PLC modem, they may be built in the PLC modem. According to this configuration, since the subcarrier group arranged on the high frequency side used in the power line communication on the HEMS side can be removed in advance, the communication on the HEMS side can be changed to the communication on the meter reading system side with a simple configuration. It is possible to reliably suppress the influence.

  The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention, and it goes without saying that these are also included in the present invention. Yes.

  For example, in the above-described embodiment, the meter-reading slave device PLC modems 13a to 13d and the HEMS slave device PLC modems 14a to 14d are built in the power meters 12a to 12d. It may be an external type. The power meters 12a to 12d incorporate two PLC modems, a meter reading slave unit PLC modems 13a to 13d and a HEMS slave unit PLC modems 14a to 14d, respectively. You may use both. In this case as well, the timing at which the slave PLC modem communicates with the HEMS master PLC modem should not overlap with the timing at which the slave PLC modem communicates with the meter-reading master PLC modem.

  In the above embodiment, for convenience of explanation, only the consumer a introduces HEMS, and the HEMS server (second server) 17 is installed only in the customer a's home. It goes without saying that the persons b to d may introduce HEMS.

DESCRIPTION OF SYMBOLS 1 Automatic meter-reading system 2 Electric pole 3 Substation 4 Pole transformer 5a, 5b Power line 6 Optical network 7 Meter-reading server 8 Short-range wireless network 9a-9d Home appliance 10 Apartment house 10a-10d Electric power consumer's door 11 PLC for meter-reading PLC Modem 12a-12d Electric power meter 13a-13d Slave meter PLC modem (second PLC modem)
14a to 14d HEMS slave PLC modems 15a to 15d Controllers 16a to 16d Breaker 17 HEMS server 18 HEMS master PLC modem 20 PLC modem 21 Controller 22 Memory 23 Interface unit 24 Communication unit 25 Modulator 26 Transmitter 27 Demodulator 28 Receiver 29 Multiplexer

Claims (10)

Multiple power meters to measure consumer power usage,
A first server for collecting first power amount data from each of the plurality of power meters;
A first PLC modem connected to the first server;
A plurality of second PLC modems connected to each of the plurality of power meters and communicating with the first PLC modem via a power line;
A second server for managing the power in the customer's home;
A third PLC modem connected to the second server;
A fourth PLC modem connected to a first power meter of a consumer who introduces the second server among the plurality of power meters, and communicating with the third PLC modem via the power line; With
The subcarrier group used for the first communication by the OFDM modulation scheme between the first PLC modem and the second PLC modem is set within a range from the first frequency to the second frequency,
The subcarrier group used for the second communication by the OFDM modulation scheme between the third PLC modem and the fourth PLC modem is set within the range of the third frequency to the fourth frequency,
The third frequency is higher than the first frequency;
The automatic meter reading system, wherein the fourth frequency is equal to or higher than the second frequency.   The automatic meter reading system according to claim 1, wherein the second frequency is the same as the fourth frequency.   The automatic meter reading system according to claim 1, wherein the second frequency is lower than the fourth frequency.   The automatic meter reading system according to claim 3, wherein the second frequency is lower than the third frequency.   The automatic meter reading system according to claim 1, wherein the first frequency is 10 kHz and the fourth frequency is 450 kHz.   The automatic meter reading system according to claim 5, wherein the third frequency is higher than 230 kHz.   The automatic meter reading system according to claim 6, wherein the second frequency is 450 kHz.   The automatic meter reading system according to claim 5 or 6, wherein the second frequency is lower than 230 kHz.   The apparatus further comprises a first low-pass filter provided at an input stage of the second PLC modem connected to the power line, and the first low-pass filter removes a signal component of the third frequency or higher. 3. The automatic meter reading system according to 3.   The apparatus further comprises a second low-pass filter provided at an input stage of the first PLC modem connected to the power line, and the second low-pass filter removes a signal component of the third frequency or higher. The automatic meter-reading system as described in any one of 3 or 9.

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