JP2009142042A - Switch control system, automatic metering system, and current value monitoring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To safely open and close a switch without spending time and effort, without newly arranging current sensors, and by grasping a load current of a wiring system. <P>SOLUTION: The automatic metering system includes a collection server SV for collecting metering data, and a large number of terminal stations A, B, C... which are communicatively connected to the collection server SV, and connected with power meters 24 and the switches 25. Each terminal station includes a switch control part 221, and the switch control part 221 controls the switch 25 so as to be brought into an open state from a closed state when it is determined that a load current value of the siring system is not higher than a prescribed threshold. The maximum value of a current present value which is estimated on the basis of a degree of an increase in a count value of the power meter 24 is used as the load current value used for this determination. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a switch control system that performs switching control of a switch installed in a power distribution system, an automatic meter reading system having this switch control function, and a current value monitoring method.

  Usually, a switch for interrupting or connecting the two systems is installed between the lead-in line from the commercial power transmission system and the indoor wiring system of the power consumer. The switch is opened and closed when an electric power customer moves, and is operated when special circumstances such as unpaid power charges occur. In order to ensure safety, the switch has a current capacity that can be opened (turned off). In the case of power supply interruption due to the special circumstances, it is often necessary for the power consumer to turn off in the state of actually using the power. The switch is turned off while checking the power usage status.

  In recent years, a communication terminal has been installed at each power consumer, and these are connected so as to be able to communicate with a collection server owned by a power company, and automatic meter reading is performed to periodically collect power meter reading data at each power consumer The system is partly operated. Then, the communication terminal station is provided with a function for controlling the opening / closing operation of the switch. For example, when the special circumstances occur, a control signal for turning off the switch from the collection server side is sent to the corresponding communication terminal station. It is also possible to transmit and remotely execute a disconnection operation.

  Thus, even when the switch is remotely turned off, it is necessary to confirm the power usage status of the power consumer by some means. One of the means is to remotely monitor the load current value by attaching a current sensor such as CT (current transformer) to the indoor wiring system of each power consumer and obtaining the output value of the current sensor through the terminal station. This is a possible method (for example, Patent Document 1). However, this method requires the installation of a new device called a current sensor, which leads to an increase in the cost of the terminal unit. In addition, the watt hour meter and the switch are often installed in a limited space, and there are cases where it is difficult to secure the installation space for the current sensor.

As another means, there is a method in which a telephone operator or the like is contacted by a telephone from the electric power company side, and after confirming the current power usage state directly, the switch is remotely turned off. According to this method, the installation of current sensors can be omitted, but it takes time to individually contact an electric power consumer who has a special situation. For electric power companies having a huge number of power consumers, such a labor is a work amount that cannot be overlooked.
JP 2004-229400 A

  The present invention has been made in view of the above-described problems, and it is possible to grasp the load current of the wiring system without taking time and installing a new current sensor and to open and close the switch safely. It is an object to provide a device control system, an automatic meter reading system having this switch control function, and a current value monitoring method.

  A switch control system according to one aspect of the present invention is connected to a wiring system that supplies power to a load, and includes a watt-hour meter that measures power usage in the wiring system, and the wiring system as a power transmission system. A switch that cuts off or connects to the switch, and a switch control unit that controls the switching operation of the switch. A value is output at a predetermined interval, and when the load control value of the wiring system is determined to be equal to or less than a predetermined threshold, the switch control unit opens the switch from closed to open. The control is performed to move to a state, and the current current value estimated based on the increase degree of the output count value is used as the load current value used for the determination. ).

  According to this configuration, the load current value is estimated based on the degree of increase in the count value of the watt-hour meter installed in the wiring system. Generally, the electricity distribution system is equipped with a watt-hour meter. Therefore, without installing new current sensors, the existing equipment is used to automatically switch the switch from closed to open while ensuring safety. Can be switched to.

  In the above configuration, it is desirable that the switch control unit estimates the maximum value of the current current value from the measurement interval and resolution of the watt-hour meter, and uses the maximum value as the current current value for determination. (Claim 2).

  In the watt-hour meter, it is conceivable to continuously measure the integrated value of the power consumption, but it is desirable to measure at a predetermined interval in order to suppress the data amount. In addition, the count value of the watt-hour meter has a resolution limit. For this reason, a certain width is generated depending on the measurement interval and the resolution in the condition that the count value may increase. Therefore, the minimum and maximum current values are estimated according to this width, and the maximum value is used for the determination, so that the switch can be opened and closed on the safe side.

  In any one of the configurations described above, the switch control unit further includes remote control means for giving a control signal for requesting execution of the switching operation, and the switch control unit is given a control signal from the remote control means In this case, it is desirable to perform the determination using the current current value obtained immediately before (claim 3).

  According to this configuration, the opening / closing operation of the switch can be performed remotely and safely. In addition, when an automatic meter reading system for a watt hour meter is introduced, the load current value can be monitored and changed by simply changing the algorithm for obtaining meter reading data from the watt hour meter without adding new hardware. It becomes possible to perform switching control of the switch.

  In this case, the switch control unit is predetermined when a predetermined time or more has passed from the most recent time point at which the current current value is obtained based on the increase in the count value to the time point when the control signal is given. It is desirable to perform the determination by using the measured value (claim 4).

  According to this configuration, it is possible to avoid a situation in which the load current value continues to be determined to have exceeded the threshold and the switch cannot be opened.

  An automatic meter-reading system according to another aspect of the present invention includes an aggregation device that collects meter-reading data of power usage, and a plurality of terminal units that are communicably connected to the aggregation device. A communication device that performs communication with the aggregation device, a watt-hour meter that is connected to a wiring system that feeds power to a load and measures the amount of power used in the wiring system, and the wiring system is a power transmission system And a switch controller for controlling the switching operation of the switch. The watt hour meter counts an integrated value of power consumption with a predetermined resolution, and A value is output at a predetermined interval, and the communication device transmits the count value as the meter reading data to the aggregation device at a predetermined communication timing, and the aggregation device A control unit for supplying a control signal for requesting execution of the switching operation to the switch control unit of the terminal unit, wherein the switch control unit has a load current value of the wiring system having a predetermined threshold value. Control to operate the switch from a closed state to an open state when it is determined that the load current value used for the determination is based on an increase degree of the output count value. When the estimated current current value is used and the control signal is given from the aggregation device, the current current value obtained immediately before is used to perform the determination. Claim 5).

  According to this configuration, the current configuration of the automatic meter reading system with a switch control function is used as it is, the load current value is monitored from the count value of the watt-hour meter, and the switch is shut off at an appropriate time. can do.

  A current value monitoring method according to still another aspect of the present invention is connected to a wiring system that feeds power to a load, measures power usage in the wiring system, and calculates an integrated value of power usage. A method of monitoring a load current value of the wiring system by using a watt hour meter that counts at a predetermined resolution and outputs the count value at a predetermined interval, and includes an increment of the output count value The center value of the load current value is estimated from the timing difference between the first measurement timing at which the increase in the count value is recognized this time and the second measurement timing at which the increase in the count value is previously recognized, and the measurement interval And a maximum condition and a minimum condition that can cause an increase in the count value between the second measurement timing and the first measurement timing. And estimating the minimum and maximum values of the load current value according to the condition (claim 6).

  According to this method, the load current value of the wiring system can be monitored based on the degree of increase of the count value by the watt-hour meter without using a current sensor or the like. Moreover, since the minimum value and the maximum value of the load current value are estimated from the measurement interval and resolution of the watt-hour meter, it can be applied to various types of control in consideration of safety.

  According to the present invention, it is possible to grasp a load current of a wiring system without opening a telephone contact with an electric power consumer, and to open and close a switch from a remote place without newly installing a current sensor. be able to. Therefore, the switch can be opened and closed safely with a predetermined current capacity or less, and the space and cost for installing the current sensors can be saved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing an overall configuration of an automatic meter reading system (switch control system) according to an embodiment of the present invention. This automatic meter-reading system automatically collects meter-reading data of power consumption from a large number of power consumers, and includes a collection server SV and a gateway GW (aggregation device) and a large number of terminal stations A, B, C. It consists of ...

  Terminal stations A, B, C,... Are wireless communication terminal stations that are capable of wireless communication with the gateway GW and other terminal stations. Is periodically transmitted to the gateway GW. In this embodiment, each terminal station A, B, C... Performs wireless communication in a PHS (Personal Handyphone System) transceiver mode. Further, the terminal stations A, B, C... Are network-connected in a tree shape having a plurality of hierarchies.

  The collection server SV is installed at, for example, a business office of an electric power company, and collects the meter reading data from each terminal in order to calculate the electric power charge of each electric power consumer. The collection server SV is network-connected to other business servers, management servers, control servers, etc. (not shown), and operates in cooperation with other businesses. The collection server SV holds a route table indicating how the gateway GW and the terminal stations A, B, C... Are arranged, and the gateway GW, the terminal stations A, B, C. Data communication with each of them is possible.

  The gateway GW is connected to the collection server SV via a network such as an in-house optical fiber network, and the PHS wireless communication network configured by the terminal stations A, B, C... Is connected to the collection server SV. A device that interconnects an optical fiber communication network. According to the route table, the terminal stations A and H are arranged in the lower layer of one gateway GW, the terminal stations B and C are arranged in the lower layer of the terminal station A, and the lower stations of the terminal stations B and C are respectively in the lower layer. The terminal stations D and E and the terminal stations F and G are arranged so that a tree-like PHS wireless communication network is formed.

  As described above, the meter reading data is periodically transmitted from the terminal stations A, B, C... Toward the collection server SV. On the other hand, from the collection server SV toward the terminal stations A, B, C..., The switch 25 (FIG. 3) is opened and closed in addition to the request signal for the meter reading data not received. The requested opening / closing control data is transmitted.

  FIG. 2 is a time chart showing a data transmission / reception state between the collection server SV (gateway GW) and the terminal stations A, B, C, D, E, F, and G constituting one tree. When the collection server SV receives meter reading data, the terminal stations D and E in the lowermost layer respectively transmit their meter reading data to the terminal station B in the middle layer when a predetermined transmission timing arrives. Similarly, the terminal stations F and G in the lowermost layer transmit their own meter reading data to the terminal station C. Next, the terminal station B transmits its own meter reading data and the meter reading data of the terminal stations D and E received earlier to the terminal station A in the upper layer. Similarly, the terminal station C transmits its own meter reading data and the meter reading data of the terminal stations F and G received earlier to the terminal station A in the upper layer. Thereafter, the terminal station A transmits its own meter reading data and the meter reading data of the terminal stations B to G previously received to the collection server SV via the gateway GW.

  On the other hand, when the control data is transmitted from the collection server SV, the data is transmitted through the reverse route at the time of reception. For example, when the opening / closing control data is transmitted from the collection server SV to the terminal station E, a wireless communication path that sequentially passes through the gateway GW, the terminal station A, and the terminal station B is used.

  In this way, a large number of terminal stations A, B, C... Are connected to a network in the form of a tree having a plurality of hierarchies, and data transmission is performed in a so-called bucket relay system, thereby collecting server SV (gateway GW). Therefore, data can be collected in a shorter time than when polling each terminal individually. Data transmission does not have to be fixed in such a bucket relay type, and if necessary, the hierarchy can be skipped and wireless communication can be performed between the terminal stations, or directly between the gateway GW and the lower-layer terminal station. Wireless communication may be performed, or direct wireless communication may be performed with a terminal station belonging to another gateway GW.

  Next, the functional configuration of the collection server SV and one terminal station A will be described based on the block diagram shown in FIG. The collection server SV functionally includes a transmission / reception unit 11, a control unit 12, and a data storage unit 13. Further, the terminal station A includes a transmission / reception unit 21, a control unit 22, and a backup memory 23. The terminal station A includes a watt-hour meter 24 that measures the amount of power used by a power consumer in which the terminal station A is disposed, and an open / close that switches ON / OFF of power supply from the commercial power transmission system to the power consumer. As the terminal unit UT combined with the device 25, it is arranged in the electric power consumer. The same applies to the other terminal stations B, C.

  The transmission / reception unit 11 is a functional unit that performs data communication with a number of terminal stations A, B, C,... Via the gateway GW. While the transmission / reception unit 11 receives the meter reading data of the watt-hour meter 24 periodically transmitted from the terminal stations A, B, C..., For the terminal stations A, B, C. Control data such as a request signal for backup meter reading data and an open / close control signal for the switch 25 are transmitted.

  The control unit 12 includes a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores a control program, a RAM (Random Access Memory) that is used as a work area of the CPU, and the CPU executes the control program. This controls the operation of each part of the collection server SV. The control unit 12 controls transmission / reception processing of the transmission / reception unit 11 and storage processing in the data storage unit 13.

  Further, the control unit 12 functionally includes a switch remote control unit 121 (remote control means) that generates the switching control signal. The switch remote control unit 121 controls the switch 25 to operate from the closed (on) to the open (off) state to shut off the indoor wiring system of the power consumer from the commercial power transmission system (hereinafter referred to as “off control”). ) Signal and control for operating the switch 25 from the open (off) to the closed (on) state to connect the indoor wiring system of the power consumer to the commercial power transmission system (hereinafter referred to as “on control”). ) Generate a signal.

  Here, the turn-off control signal is transmitted to a terminal station of the power consumer when, for example, the power consumer moves out or a reason for stopping the power supply based on special circumstances occurs. On the other hand, an incoming control signal is transmitted to the terminal station of the said electric power consumer, for example, when the transfer of an electric power consumer or the reason for a power supply stop is eliminated. These turn-off control signals and turn-on control signals are generated and transmitted at a timing when an instruction is given from a management server (not shown) or the like interconnected to the collection server SV.

  The data storage part 13 memorize | stores the meter-reading data periodically transmitted from each terminal station A, B, C ..., and received by the transmission / reception part 11. FIG. FIG. 4 is a data configuration diagram showing an example of the meter reading data. The meter reading data includes “instrument ID”, “meter reading date and time”, “instruction value”, and “data flag”. “Instrument ID” is a unique ID number assigned to the electricity meter 24 for each power consumer. The “meter reading date and time” is time data indicating the date and time when the meter reading data is acquired. The “instruction value” is an integrated value (count value) of the power usage amount counted by the watt-hour meter 24. The “data flag” is data indicating information such as whether or not the instruction value is properly read in a flag format. Such meter reading data is transmitted from each terminal station A, B, C... To the collection server SV every predetermined meter reading cycle, for example, every 30 minutes.

  The transmitting / receiving unit 21 of the terminal station A is a functional unit for performing wireless data communication with the upper gateway GW or the lower terminals B and C. The transmitting / receiving unit 21 transmits the meter reading data of the watt-hour meter 24 and its own meter reading data periodically transmitted from the terminal stations B, C... To the collection server SV at every predetermined transmission timing. On the other hand, control data transmitted from the collection server SV is received.

  The control unit 22 controls each part of the terminal station A, reads the meter reading data of the watt-hour meter 24 periodically at a predetermined meter reading cycle, sends the meter reading data to the collection server SV, and the meter reading. A process for storing data in the backup memory 23 is controlled.

  Furthermore, the control unit 22 functionally includes a switch control unit 221 that performs control to open and close the switch 25. The switch control unit 221 performs the above-described “turn-off control” or “turn-on control” when the switch control signal is given from the collection server SV side. Whether or not the value is equal to or less than a predetermined threshold is determined based on the meter reading data of the watt-hour meter 24 without using current sensors, and then “off control” is performed. This will be described in detail later.

  The backup memory 23 is a memory that records meter reading data read from the watt-hour meter 24 for backup. In order to prevent the memory from being over, the control unit 22 may be provided with a routine for automatically erasing the data in the backup memory 23 when a predetermined period (for example, one month) has elapsed since the meter reading time.

  The watt-hour meter 24 is connected to an indoor wiring system that supplies power to an electric power load held by a power consumer, and measures the amount of power used in the indoor wiring system. The watt hour meter 24 counts the integrated value of the power consumption with a predetermined resolution, and outputs the count value with a predetermined interval. This count value is read as a meter reading value, for example, every 30 minutes for transmission to the collection server SV, and in this embodiment is read at intervals of about 3 to 360 seconds for monitoring the load current value.

  The switch 25 cuts off or connects the indoor wiring system of the power consumer from the commercial power transmission system in accordance with the “OFF control” or “ON control”. Generally, a rated current capacity capable of safely performing a “off” operation is determined for a switch. And if “OFF control” is performed in a state where current exceeding the rated current capacity is flowing, the safety guard is activated and the “OFF” operation is not actually performed or the switch breaks down. Arise. Therefore, it is important to know the load current value when performing the “off control”.

  Next, details of the switch control unit 221 will be described with reference to FIGS. FIG. 5 is a time chart showing a remote control sequence of the switch. Here, an example is shown in which the switch 25 of the terminal station B is remotely controlled from the collection server SV via the gateway GW and the terminal station A.

  The switch control request (open / close control signal) issued from the collection server SV is received by the terminal station B through the gateway GW and the terminal station A sequentially. In the terminal station B, meter reading is performed in combination with the switch ID control process, the switch state check process, the current current value check process, the switch control process such as the switch control, and the like (based on the flowcharts of FIGS. 9 and 10). Details will be described later). When the switch control is finished, a switch control response notifying that the processing is completed is issued from the terminal station B, and is received by the collection server SV via the terminal station A and the gateway GW.

  The switch control unit 221 monitors the load current value of the indoor wiring system based on the meter reading value of the watt-hour meter 24 so as to be able to cope with the switch control request of “OFF control” whenever it is given. FIG. 6 is a timing chart for schematically explaining such current value monitoring and switch control methods.

  The watt-hour meter 24 counts the integrated value of the amount of power used by the power consumer with a predetermined resolution (for example, 0.01 kWh). The count value is read by the switch control unit 221 as a meter reading value for monitoring the load current value at meter reading timings t0, t1, t2,... At intervals of n seconds. The switch control unit 221 calculates a current current value based on the increase degree of the meter reading value (count value), and estimates a load current value.

As shown in FIG. 6, it is assumed that an increase in the meter reading value is recognized at the meter reading timing t1 (second measurement timing). Subsequently, it is assumed that an increase in the meter reading value is recognized again at the meter reading timing t4 (first measurement timing). The time when the meter reading value increase is recognized is the current current value calculation timing. Here, when the increment of the meter reading value at the meter reading timing t4 is p and the number of meter reading cycles is k, the current meter value increment p and the elapsed time from the previous meter value increment recognition to the current meter value increment recognition. Based on (k × n), the current current value is calculated at the meter reading timing t4 based on a calculation formula based on the following formula (1) (described in detail later).
P (kWh) = E (V) × I (A) × t (seconds) ÷ 3600 ÷ 1000 (1)

  When a switch control request of “cut control” is given from the collection server SV side at the meter reading timing t6, the switch control unit 221 uses the current value at the meter reading timing t4 obtained immediately before, It is determined whether or not the load current value is equal to or less than a predetermined threshold that can cause the switch 25 to perform the “off” operation. And when it is below a threshold value, the switch control part 221 performs "OFF control" with respect to the switch 25, and when the threshold value is exceeded, it holds "OFF control". At this time, the current current value is calculated with a maximum error in the safe direction. The details of the current current value calculation formula will be exemplified below.

It is assumed that the indoor wiring system of the electric power consumer is a single-phase two-wire system (line voltage = 100V) and a power factor 100% line. In this case, the current value I can be expressed as follows from the above equation (1).
P (kWh) = E (V) × I (A) × t (seconds) ÷ 3600 ÷ 1000
I (A) = P (kWh) ÷ E (V) ÷ t (seconds) × 3600 × 1000 (2)

When the resolution of the watt-hour meter 24 is 0.01 kWh, the current value I in the equation (2) can be expressed by using the meter reading increase p.
I (A) = (p × 0.01) ÷ E ÷ t × 3600 × 1000
= P ÷ E ÷ t × 36000
Since the voltage E = 100V,
I (A) = p ÷ t × 360 (3)

As described above, when the meter reading interval is n seconds and the time required for the meter reading to increase by p is k × n, the current value I is represented by the following equation (4) from the equation (3).
I (A) = 360 × p ÷ (k × n) (4)

  The current value obtained by the above equation (4) can be said to be the center value of the load current value estimated from the previous time based on the increment p of the current meter reading value (count value). In the present embodiment, this does not stop. As described below, the maximum condition and the minimum condition that can cause the count value of the watt hour meter 24 to increase are obtained from the meter reading interval and the resolution of the watt hour meter 24, and according to these conditions. Estimate the minimum and maximum load current values. And it is determined whether it is below the said threshold value using the load current value estimated from the maximum value.

  First, as the meter reading interval is n seconds, there is a certain range of possibility that the count value of the watt-hour meter 24 actually increases by p is measured as the increment p of the meter reading value. FIG. 7 is a timing chart for explaining the range of the possibility.

  Now, it is assumed that an increase in the meter reading value is recognized at the meter reading timing t12, and subsequently, an increase in the meter reading value is recognized by p at the meter reading timing t16. In this case, based on the meter reading value purely, the current current value I is obtained by the above equation (4) using the meter reading timing t12 as a reference time for calculating the elapsed time. However, as shown in FIG. 7, there is a range from the minimum condition of [Case 1] to the maximum condition of [Case 2] as an increase mode of the count value of the watt-hour meter 24 recognized as the increment p of the meter reading value. There is.

Case 1 shows a mode in which the count value increases at the time when the minute time Δt1 has elapsed from the meter reading timing t11, and the increment p is generated in the count value at the time immediately before the meter reading timing t16 by the minute time Δt4. . On the other hand, Case 2 shows a mode in which the count value increases at the time immediately before the meter reading timing t12 by the minute time Δt2, and the increment p is generated in the count value at the time when the minute time Δt3 has passed from the meter reading timing t15. ing. In both cases 1 and 2, the increment p is recognized as the meter reading value at meter reading timings t12 and t16. However, in case 1, the meter reading cycle number k≈5, and in case 2, k≈3. Specifically, the current current value I _{min in} case 1 and the current current value I _{max in} case 2 can be expressed as follows from equation (4).
I _min (A) = 360 × p ÷ ((k + 1) × n) (5)
I _max (A) = 360 × p ÷ ((k−1) × n) (6)

Therefore, the possibility value I _x1 of the current current value when the increment p is recognized as the meter reading value is expressed by the following equation (7) from the above equations (5) and (6).
I _x1 (A) = 360 × p ÷ ((k + 1) × n) to 360 × p ÷ ((k−1) × n)
... (7)
If n = 3 seconds,
I _x1 (A) = 120 × p ÷ (k + 1) to 120 × p ÷ (k−1)
It is. However, the above is the case where k ≧ 2 and an increase in p occurs.

When an increase of p occurs when k = 1, the actual power consumption has a certain width due to the resolution of the watt-hour meter 24. FIG. 8 is a graph for explaining the width. As indicated by R ₀ in the figure, the count value of the watt-hour meter 24 rises stepwise according to the resolution. However, there is a maximum condition R ₁ and a minimum condition R _{2 as} the possibility of the power consumption that causes an increase in p at the meter reading timings t22 to t23.

That is, Max condition _{R 1} is slightly exceeded the count value p1 at needle timing t22, the power consumption falls below the count value p3 to (= p1 + 2) just at the meter reading timing t23, when the energy meter 24 is to measure It is. On the other hand, minimum condition _{R 2} is the count value in the meter reading timing t22 p2 (= p1 + 1) to below slightly, the power consumption exceeds the count value p2 slightly in meter reading timing t23, when the energy meter 24 is to measure is there. Therefore, even if the p increase in occurs, the actual amount of power consumed in the Max condition _{R 1} ≒ p + 1, the minimum condition _{R 2} ≒ p-1, and the substantially of (p-1) ~ (p + 1) Will have a width.

Therefore, when k = 1, the current current value I _min of the minimum condition R ₂ and the current current value I _{max of the maximum} condition R ₁ can be expressed as follows from the equation (4).
I _min (A) = 360 × (p−1) ÷ (1 × n) (8)
I _max (A) = 360 × (p + 1) ÷ (1 × n) (9)
Therefore, the possibility value I _x2 of the current current value when the increment p is recognized as the meter reading value when k = 1 is as shown in the following equation (10) from the above equations (8) and (9). It becomes.
I _x2 (A) = 360 × (p−1) ÷ (1 × n) to 360 × (p + 1) ÷ (1 × n)
... (10)
If n = 3 seconds,
I _x2 (A) = 120 × (p−1) to 120 × (p + 1)
It is.

As described above, the current current value obtained from the meter reading value of the watt-hour meter 24 can be considered to have the width of the formula (7) or the formula (10). In consideration of the above, it is desirable to determine whether or not to execute the “off control” of the switch 24 using the maximum value represented by the expression (6) or (9). Therefore, the switch control unit 221 determines the current value when n = 3 seconds.
I (A) = 120 × p ÷ (k−1) where k ≧ 2
I (A) = 120 × (p + 1) where k = 1
This is calculated by the following formula, and this is treated as the load current value of the indoor wiring system to determine whether or not the switch 24 is to be “turned off”.

  Table 1 shows an example of calculating the current value of the single-phase two-wire (line voltage = 100 V) line obtained by the calculation method as described above. The “maximum value” in the table is the current value used by the switch control unit 221.

Further, when the indoor wiring system is a single-phase two-wire line having a line voltage of 200 V and a power factor of 100%, the above equations (7) and (10) are as follows.
I _x1 (A) = 180 × p ÷ ((k + 1) × n) to 180 × p ÷ ((k−1) × n)
I _x2 (A) = 180 × (p−1) ÷ (1 × n) to 180 × (p + 1) ÷ (1 × n)
If n = 3 seconds, these equations are
I _x1 (A) = 60 × p ÷ (k + 1) to 60 × p ÷ (k−1)
I _x2 (A) = 60 × (p−1) to 60 × (p + 1)
It becomes.

  Table 2 shows an example of calculating the current value of the single-phase two-wire (line voltage = 200 V) line. Similarly, the “maximum value” in the table is the current value used by the switch control unit 221.

In addition, formulas for calculating current values in wiring systems of other line formats can be derived in the same manner. In the case of a single-phase three-wire system, a line voltage of 100 V, an unbalance rate of 40%, and a power factor of 100%, current current values I _x3 and I _x4 can be calculated by the following equations.
I _x3 (A) = 120 × p ÷ (k−1) ÷ 2 × 1.2 where k ≧ 2, n = 3
I _x4 (A) = 120 × (p + 1) ÷ 2 × 1.2 where k = 1, n = 3

In the case of a three-phase three-wire system, a line voltage of 200 V, an unbalance rate of 30%, and a power factor of 90%, the current current values I _x5 and I _x6 can be calculated by the following equations.
I _x5 (A) = (60 ÷ √3) × p ÷ (k−1) ÷ 0.9 × 1.15 where k ≧ 2, n = 3
I _x6 (A) = (60 ÷ √3) × (p + 1) ÷ 0.9 × 1.15 where k = 1, n = 3

  Note that the switch control unit 221 determines the elapsed time from the most recent time point at which the current current value is obtained based on the increase in the meter reading value to the time point when the control signal is given, in the example of FIG. 6, the detection timings t4 to t6. When a predetermined time or more has elapsed, a predetermined value is used as the current current value to determine whether or not to execute “off control”. This is for avoiding the inconvenience that the load current value continues to be determined to have exceeded the threshold and the “switching control” of the switch 25 cannot be performed. In this case, the elapsed time and the current current value may be appropriately determined according to the line type and the line voltage. For example, after recognizing the previous meter reading increase, a new meter reading increase is recognized after 360 seconds. If not, the switch controller 221 can be processed by an algorithm that sets the current current value to 1A.

  Next, the operation of the switch control process by the switch control unit 221 will be described with reference to FIGS. 9 and 10. FIG. 9 is a flowchart showing the processing operation of “OFF control”. When the transmission / reception unit 21 receives a switch control request (see FIG. 5) for “OFF control” from the collection server SV, the switch control unit 221 confirms the instrument ID included in the request signal (step S1). Then, it is confirmed whether or not they match (step S2). The meter ID is an ID assigned to the watt hour meter 24 of each terminal station as described above, and using this ID, it is confirmed whether it is a switch control request for its own terminal station.

  If the instrument IDs match (YES in step S2), the switch control unit 221 checks the current state of the switch 25 (step S3). If the instrument IDs do not match (NO in step S2), the process ends.

  When the current state of the switch 25 is “ON” (YES in step S4), the switch controller 221 determines the current current obtained from the meter reading for current value monitoring and the calculation formula described in detail above. The maximum value is extracted (confirmed) as an estimated value of the load current value of the indoor wiring system (step S5). On the other hand, when it is already in the “off” state, the control is in the same direction, so the process skips to step S11.

  Next, the switch control unit 221 determines whether or not the current current value is equal to or less than a predetermined threshold (step S6). The threshold value is a load current value at which the switch 25 can be “turned off” without difficulty, and is naturally a current value that is equal to or less than the rated current capacity of the switch 25. If the current value exceeds this threshold (NO in step S6), the execution of “OFF control” is reserved and skips to step S11. Or it is good also as a loop which returns to step S5 and confirms an electric current present value.

  When the current current value is less than or equal to the threshold value, the switch control unit 221 executes “off control” for the switch 25 (step S7). Subsequently, the switch control unit 221 starts counting a predetermined waiting time (for example, 100 ms) for waiting for stable operation of the switch 25 (step S8), and checks the state of the switch 25 when the waiting time has expired. (Step S9). When the switch 25 is changed to the “OFF” state (YES in step S10), the meter reading in step S11 is performed, and then the process ends. If it is not changed to the “OFF” state (NO in step S10), the process returns to step S7 to retry. The meter reading in step S11 is for confirming the meter reading value of the watt-hour meter 24 at the time of switch control.

  Next, FIG. 10 is a flowchart showing the processing operation of “input control”. When the transmission / reception unit 21 receives the “on control” switch control request from the collection server SV, the switch control unit 221 confirms the meter ID included in the request signal (step S21). Then, it is confirmed whether or not they match (step S22). When the meter IDs match (YES in step S22), the switch control unit 221 confirms the current state of the switch 25 (step S23), and further, the meter reading value of the watt-hour meter 24 immediately before the switch control. Is confirmed (step S24). If the instrument IDs do not match (NO in step S22), the process ends.

  When the current state of the switch 25 is “OFF” (YES in step S25), the switch controller 221 executes “ON control” (step S26). On the other hand, when it is already in the “ON” state, the control is in the same direction, so the processing is finished as it is.

  Thereafter, the switch control unit 221 starts counting a predetermined waiting time (for example, 100 ms) for waiting for the stabilization of the operation of the switch 25 (step S27), and checks the state of the switch 25 when the waiting time has expired. (Step S28). When the switch 25 is changed to the “ON” state (YES in step S29), the process is terminated. If it has not changed to the “ON” state (NO in step S29), the process returns to step S26 to retry.

  According to the automatic meter reading system according to the present embodiment described above, it does not take time and effort to make a telephone contact with a power consumer having the terminal stations A, B, C. Without newly installing, the terminal unit UT of the power consumer can grasp the load current of its own wiring system and can open and close the switch 25 by a control signal given from a remote place. Therefore, the switch 25 can be safely opened and closed with a predetermined current capacity or less, and the space and cost for installing the current sensors can be saved.

  As mentioned above, although embodiment was described about this invention, this invention is not limited to this, For example, the deformation | transformation embodiment as shown below can be taken.

[1] In the above embodiment, an example in which the aggregation device includes the collection server SV and the gateway GW has been described. This is an example of an aggregation device, and may be an aggregation device including a plurality of servers, an aggregation device that does not use the gateway GW, and the like. Further, although the PHS method is exemplified as the wireless communication method between the terminal stations, other wireless communication methods can be adopted. For example, the present invention can be applied to a server and a client configuring a wireless LAN. Furthermore, a wired communication method may be employed instead of the wireless communication method.

[2] In the above embodiment, an example is shown in which the terminal stations A, B, C,... Instead, each terminal station A, B, C... May be individually connected to the collection server SV.

[3] In the above-described embodiment, an example in which it is determined whether or not to execute “off control” using the maximum value of the current current value assumed from the measurement interval and resolution of the watt-hour meter 24 has been described. However, it is not always necessary to adopt the maximum value. For example, the maximum value of 90% or 80% may be adopted, or the maximum value of 110% may be adopted in consideration of further safety. good.

It is a mimetic diagram showing the whole automatic metering system (switch control system) composition concerning an embodiment of the present invention. It is a time chart which shows the transmission / reception state of data between a collection server and a terminal station. It is a block diagram which shows the function structure of a collection server and one terminal station. It is a data block diagram of the meter-reading data transmitted from a terminal station. It is a time chart which shows the remote control sequence of a switch. It is a timing chart for demonstrating roughly the method of electric current value monitoring and switch control. It is a timing chart for explaining the maximum value and the minimum value of the current current value. It is a graph for demonstrating the maximum value and minimum value of an electric current present value. It is a flowchart which shows the processing operation of "OFF control". It is a flowchart which shows the processing operation of "input control".

Explanation of symbols

SV collection server (aggregation device)
GW gateway (aggregation device)
A, B, C... Terminal station 11 Transmission / reception unit 12 Control unit 121 Switch remote control unit (remote control means)
DESCRIPTION OF SYMBOLS 13 Data memory | storage part 21 Transmission / reception part 22 Control part 221 Switch control part 23 Backup memory 24 Electricity meter 25 Switch

Claims (6)

A watt-hour meter connected to a wiring system for supplying power to the load and measuring the power consumption in the wiring system;
A switch for interrupting or connecting the wiring system to the power transmission system;
A switch control unit for controlling the opening and closing operation of the switch,
The watt-hour meter counts an integrated value of power consumption with a predetermined resolution, and outputs the count value at a predetermined interval.
The switch control unit performs control to operate the switch from a closed state to an open state when it is determined that a load current value of the wiring system is equal to or less than a predetermined threshold value. A switch control system using a current current value estimated based on an increase degree of the output count value as a load current value used for the switch.   The switch control unit estimates a maximum value of the current current value from a measurement interval and resolution of the watt-hour meter, and uses the maximum value as the current current value for determination. The switch control system according to 1. Remote control means for giving a control signal for requesting execution of the opening / closing operation to the switch control unit,
3. The switch according to claim 1, wherein when the control signal is given from the remote control unit, the switch control unit performs the determination using the current current value obtained immediately before. The switch control system described.   The switch control unit determines a predetermined value when a predetermined time or more has passed from the most recent time when the current current value is obtained based on the increase in the count value to the time when the control signal is given. The switch control system according to claim 3, wherein the determination is performed by using the switch. An aggregation device that collects meter-reading data of power usage, and a plurality of terminal units connected to be able to communicate with the aggregation device;
The terminal units are respectively
A communication device that performs communication with the aggregation device, a watt-hour meter that is connected to a wiring system that supplies power to a load and measures the amount of power used in the wiring system, and the wiring system is connected to a power transmission system A switch to be cut off or connected, and a switch control unit for controlling the switching operation of the switch,
The watt-hour meter counts an integrated value of power consumption with a predetermined resolution, and outputs the count value at a predetermined interval.
The communication device transmits the count value as the meter reading data to the aggregation device at a predetermined communication timing,
The aggregation device includes a control unit that provides a control signal for requesting execution of the switching operation to the switch control unit of the terminal unit,
The switch control unit performs control to operate the switch from a closed state to an open state when it is determined that a load current value of the wiring system is equal to or less than a predetermined threshold value. As the load current value to be used, the current value estimated based on the increase degree of the output count value is used, and when the control signal is given from the aggregation device, the current value obtained immediately before is calculated. An automatic meter reading system with a switch control function, wherein the determination is performed using a current value. It is connected to a wiring system that supplies power to the load, and measures the amount of power used in the wiring system. The integrated value of the power usage is counted with a predetermined resolution, and the count value is calculated over a predetermined interval. A method of monitoring the load current value of the wiring system using a watt-hour meter to be placed and output,
The load current value is calculated from the output increment of the count value and the timing difference between the first measurement timing when the count value increase is recognized this time and the second measurement timing when the count value increase is recognized last time. Estimate the center value,
From the measurement interval and resolution, a maximum condition and a minimum condition that can cause an increase in the count value between the second measurement timing and the first measurement timing are obtained, and the minimum value of the load current value is determined according to these conditions. Estimate the maximum value,
The current value monitoring method characterized by the above-mentioned.

Images