JP7288422B2 - Power monitoring system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a power monitoring system, and more particularly to a technique for notifying an improvement effect of energy saving by balanced load connection.

The power monitoring system acquires the energy data of the required parts of the user. The accumulated data is used for finding energy saving points. One of the energy-saving methods is the balanced arrangement of the connected loads. When installed with a balanced load, in the case of a single-phase three-wire system, current does not flow in the N phase, so wiring loss in the N phase can be reduced. The wiring loss that can be reduced is calculated from the type of wiring in the user's environment, the wire diameter, the distance, and the power consumption of each phase.

Patent Document 1 discloses a line current management system for a single-phase three-wire wattmeter equipped with a line current monitoring function. a third line current detector; first and third line voltage detectors for detecting a line voltage between the wires; and a load supplied from the line current detector output and the line voltage detector output. and a host computer connected to the power amount calculation unit via a network. When an abnormal value of the line current is detected, the abnormal value data is transmitted to the host computer via the network." (see abstract).

JP-A-2005-233879

The type of wiring, wire diameter, and distance all vary depending on the user's environment. Wiring resistance values are necessary for calculating wiring loss and for calculating the energy-saving effect of balanced load connection. As mentioned above, the wiring type, wire diameter, and distance all differ depending on the user's environment, so the wiring resistance value is unknown. In addition to the wiring resistance value, instantaneous value data such as power and current in each wiring (each phase) is also required. Instantaneous value data requires values at the same time, and if there is a time delay, it cannot be calculated correctly. In addition, it is necessary to examine the details of the power monitoring system data in order to investigate load imbalance conditions. As described above, it takes a long time to find an unbalanced portion where energy can be saved, and the effect of reducing the wiring loss by improving the unbalanced state cannot be calculated with a simple operation.

Patent Literature 1 discloses a line current monitoring system for a single-phase three-wire watt-hour meter, which has a line current monitoring function that prevents measurement of electric energy in an unbalanced state and monitors an unbalanced state of a load. However, no consideration is given to notification of the effect of reducing wiring loss by improving the unbalanced state.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power monitoring system that calculates and displays a wiring loss value (energy-saving effect) that can be reduced without obtaining information on the type, diameter, and distance of wiring in the user's environment. do.

In order to solve the above problems, the power monitoring system of the present invention has a function of acquiring instantaneous data of voltage and current at the same time, a display function that enables an intuitive image of an unbalanced state of the load, and a wiring function. It has a function to display the wiring loss and the wiring loss value that can be reduced without information on the type, wire diameter, and distance.

To give an example of the "power monitoring system" of the present invention,
A power supply side measurement unit that measures the power supply side of the power wiring, a load side measurement unit that measures the load side of the power wiring, and measurement signals are input from the power supply side measurement unit and the load side measurement unit. , and a power monitoring device for monitoring power, wherein the power monitoring device measures the phase-to-phase voltage and the line current of each phase measured by the measurement unit on the power supply side, and the measurement on the load side. A line resistance calculation unit that calculates line resistance from the interphase voltage measured by the unit, and the current line of each phase from the line current of each phase measured by the measurement unit on the power supply side and the line resistance obtained by the line resistance calculation unit It comprises a current line loss computing unit for obtaining the loss and the total line loss, and a display unit for displaying the current line loss of each phase and the total line loss.

According to the present invention, it is possible to calculate and display a wiring loss value (energy-saving effect) that can be reduced even if information on the type of wiring, wire diameter, and distance in the user's environment cannot be obtained.

Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

1 is a schematic configuration diagram of a power monitoring system according to an embodiment of the present invention; FIG. It is a figure which shows the outline|summary of the communication processing of a power monitoring system. 1 is an example of a graph of load balance; FIG. FIG. 11 is another example of a graph of load balance; FIG. FIG. 11 is another example of a graph of load balance; FIG. It is a schematic diagram of the measurement of the power monitoring system. 1 is a block configuration diagram of a power monitoring system of Example 1; FIG. It is an example of the screen which displays the reduction effect of wiring loss. FIG. 11 is a block configuration diagram of a power monitoring system of Example 2;

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In addition, in each drawing for explaining the embodiments, the same components are given the same names and symbols as much as possible, and the repeated description thereof is omitted.

FIG. 1 shows a schematic configuration of a power monitoring system according to Embodiment 1 of the present invention. The embodiment of the present invention is an example showing the wiring loss in the power wiring 100 for supplying power from the power receiving board to the power distribution board shown in FIG. 1 and the energy saving effect after improvement.

In the power monitoring system, personal computer 101 serves as a master and acquires data from measuring units 102 and 103 . The personal computer 101 and the measurement units 102 and 103 are connected by a multi-drop system via a communication line 104 of RS-485. Although RS-485 is used here, any multidrop method may be used. The measurement units 102 and 103 are installed on the power supply side sending side and the load side entrance side of the location where the wiring loss is to be measured. Here, the measurement unit 102 on the power supply side measures the outlet 105 of the power receiving panel, and the measurement unit 103 on the load side measures the inlet 106 of the switchboard. The measurement units 102 and 103 measure voltage, current, power, energy, power factor, etc. An outline of communication processing will be described with reference to FIG. According to a communication command from the personal computer 101, each measurement unit 102, 103 performs a predetermined internal operation or replies to a request.
First, the personal computer 101 broadcasts a request to the measurement units 102 and 103 to internally hold the current measured values (S1). Since each measurement unit is connected in a multi-drop manner, it will receive requests to be held at the same time without any time delay. After receiving, each of the measurement units 102 and 103 holds the current measured value, so the held measured value is the measured value at the same instant (same time) without time delay.

Next, the personal computer 101 sends a command to sequentially acquire the measured values held by the measuring units 102 and 103 (S2, S4). Each measuring unit 102, 103 returns the measured value it holds only when it receives a request (S3, S5). The measured values that the PC acquires from each unit are the measured values at the same instant (at the same time) regardless of the order in which they are acquired.

Inside the personal computer, the voltage, current, power, electric energy, power factor, etc. of each measurement unit are stored in memory along with the time. Graph creation processing and arithmetic processing are performed on the saved data.

FIG. 3 shows the graph creation process. It is created for the past one day and is updated each time new data is obtained. Here, one day is used, but the span is not limited to this, and the span may be long or short. In the graph, the horizontal axis is the time axis and the vertical axis is the current value. The horizontal axis and the vertical axis may be interchanged. The time indicates the time the personal computer held the data. The current displays the result of the following calculation using the values of the measurement units 102 and 103 in FIG.
Current value=R-phase current of measurement unit 102-T-phase current of measurement unit 102 The R-phase current and the T-phase current may be interchanged. Also, the phase current of the measurement unit 103 may be used. Although current is used here, electric power may be used. From this graph, the balanced state of the load can be visually recognized. The ideal state of the graph is the state where the graph is zero. In the graph of FIG. 3, plus and minus are touched, but since there are many touches in the plus direction, it can be seen that there are many loads connected between RN.

Since the graph in FIG. 4 swings only in the positive direction, it can be seen that many loads are connected between RN. If there is a large amount of swing in either direction as shown in FIGS. 3 and 4, the imbalance can be improved.

In the graph of FIG. 5, since both are touched to the same degree, improving the R phase will increase the load on the T phase, and the imbalance cannot be improved. By looking at this graph display, it is possible to quickly judge whether improvement can be made.

Arithmetic processing of the personal computer 101 operating as a power monitoring device will be described with reference to FIG. The personal computer 101 obtains and displays the current wiring loss and the wiring loss after improvement.

To obtain the current wiring loss, the RN voltage V1R-N measured by the power supply side measurement unit 102, the TN voltage V1T-N, the line currents IR, IN, and IT measured by the load side measurement unit 103 RN voltage V2R-N and TN voltage V2T-N are used. To obtain the wiring loss, the value of the wiring resistance R is required, but since the length, wire diameter, and wire type of the wiring are unknown, it can be easily obtained from each measured value. When current flows through line resistance R, a voltage drop occurs. When the R-phase line current IR and the N-phase line current IN flow through the line resistance R, a voltage drop occurs and the voltage V1R-N becomes the voltage V2R-N. When this is made into a formula, it becomes the following.
V1R-N(V) - V2R-N(V) = IR(A) x R(Ω) + IN(A) x R(Ω)
Summarizing this formula with the line resistance R gives the following.
R(Ω)＝(V1R-N(V)－V2R-N(V))÷(IR(A)＋IN(A)) …（1）
With this formula, the line resistance R can be obtained regardless of the length, wire diameter, and wire type of the wire. From the obtained line resistance R, the current line loss of all phases can be obtained by the following formula.
Line loss Wr (W) = (IR x IR x R) + (IN x IN x R) + (IT x IT x R) … (2)
In the above formula, IR x IR x R = R-phase line loss, IN x IN x R = N-phase line loss, and IT x IT x R = T-phase line loss.

Next, improve the load connection and find the line loss when balanced. The current load power Wa is the sum of the load power between RN and the load power between TN. Expressed as a formula, it is as follows.
Wa(W) = R-phase load power + T-phase load power = (V1R-N x IR x power factor) + (V1T-N x IT x power factor) (3)
Here, the power factor can be obtained from the phase difference between voltage and current.
When the loads are balanced, the load balance between RNs and between TNs will match. Therefore, the power between RN and TN is as follows.
RN load power = TN load power = Wa/2 (4)
When the line current IR0 at this time is obtained, the following formula is obtained. Here, the power factor Φ is a value measured by the measurement unit 102 on the power supply side.
IR0＝(Wa÷2)÷(V1R-N×power factorΦ) …（5）
From the line current IR0 obtained by Equation 5 and the line resistance R obtained by Equation 1, the line loss under balanced load can be obtained. R-phase line loss = T-phase line loss, and N-phase is 0 because no current flows.
Line loss Wr0(W) at balanced load = ((5) x (5) x (1)) x 2
= IR0 x IR0 x R x 2 (6)
By calculating the following equation from the current line loss Wr and the line loss Wr0 under balanced load, the wiring loss that can be improved can be calculated.
Line loss that can be improved = Formula 2-Formula 6
＝Wr(W)－Wr0(W) …(7)
FIG. 7 shows a block configuration diagram of the power monitoring system of the first embodiment. The power monitoring system comprises a power supply side measuring unit 102, a load side measuring unit 103, and a power monitoring device 200 such as a personal computer that monitors power based on the signals measured by both measuring units 102 and 103. there is

A measurement unit 102 on the power supply side measures voltage, current, and the like on the power supply side of the power wiring 100 . The load-side measurement unit 103 measures the voltage, current, and the like on the load side of the power wiring 100 .

In the power monitoring device 200, an input unit 201 inputs measurement signals such as voltage and current measured by the measurement unit 102 on the power supply side and the measurement unit 103 on the load side.
In the line resistance calculation unit 202, using the RN voltage V1R-N measured by the power supply side measurement unit 102, the line currents IR and IN, and the RN voltage V2R-N measured by the load side measurement unit 103, Based on the formula 1, the line resistance R is calculated. Note that the TN voltage V1T-N, the line currents IT and IN, and the TN voltage V2T-N measured by the load-side measurement unit 103 may be used to calculate the line resistance R.
In the current line loss calculation unit 203, the R phase, N phase and T Find the current line loss for the phase. The display unit 208 displays the obtained current line losses of the R-phase, N-phase and T-phase and the total line loss.

The current load power calculation unit 204 calculates the current current based on Equation 3 from the RN voltage V1R-N, the TN voltage V1T-N, and the line currents IR and IT measured by the measurement unit 102 on the power supply side. Calculate the full load power Wa. Note that the RN voltage V2R-N, the TN voltage V2T-N, and the line currents IR and IT measured by the measurement unit 103 on the load side may be used to calculate the current full-load power Wa. Although there is a difference in the line loss, it can be ignored because the line loss is small compared to the load power.
In the balanced line current calculator 205, the current full-load power Wa obtained by the current load power calculator 204 and the RN voltage V1R-N, which is the line-to-line voltage, are used to calculate the balanced load Calculate the line current IR0 (= IT0) at
In the balanced line loss calculation unit 206, from the line resistance R obtained by the line resistance calculation unit 202 and the line current IR0 (=IT0) at the balanced load obtained by the line current calculation unit 205 at equilibrium, Equation 6 is obtained. Based on , the R-phase, N-phase, and T-phase line losses and total line loss Wr0 under balanced load are calculated. At this time, R-phase line loss=T-phase line loss, and N-phase line loss is zero. The obtained R-phase, N-phase, and T-phase line losses and total line loss Wr0 under balanced load are displayed on the display unit 208. FIG.
In the improved line loss calculator 207, from the current line loss Wr obtained by the current line loss calculator 203 and the balanced load line loss Wr0 obtained by the balanced line loss calculator 206, Equation 7 is obtained: Based on , the line loss that can be improved is obtained. The display unit 208 displays the obtained line loss that can be improved.

FIG. 8 shows an example of display of the calculated result. The screen of FIG. 8 displays the current wiring loss value and total value for each phase, the wiring loss value and total value for each phase after improvement as a balanced load, and the improved value for a balanced load. In the example shown, the current R-phase loss is 4,665 W, N-phase loss is 746 W, T-phase loss is 1,679 W, and the total wiring loss is 7,090 W. If this is improved to a balanced load, the R-phase loss is 2,985W, the N-phase loss is 0W, the T-phase loss is 2,985W, and the total wiring loss is 5,970W. An improvement of 1,120 W is expected by balancing the load. As a result, it is possible to grasp the current state of the wiring loss and to visually recognize how much improvement can be expected by balancing the load. With this screen, the user can easily judge the magnitude of the wiring loss improvement effect.

The power monitoring device 200 can be realized by the CPU of a personal computer (computer) loading a predetermined program onto the memory, and by executing the predetermined program loaded onto the memory by the CPU. This predetermined program may be input from a storage device or from a network via a communication device and loaded onto the memory.

According to this embodiment, by providing the line resistance calculation unit and the current line loss calculation unit, even if information on the type, wire diameter, and distance of the wiring in the user's environment cannot be obtained, can be obtained and displayed. In addition, by equipping the current load power calculator, the line current calculator at equilibrium, and the line loss calculator at equilibrium, the wiring loss value (energy saving effect) that can be reduced by connecting the load to the balanced load is calculated and displayed. can do.

FIG. 9 shows a block configuration diagram of a power monitoring system according to a second embodiment of the present invention. The difference from the first embodiment is that the load power calculation unit 204 is provided in the measurement unit 102 on the power supply side or the measurement unit 103 on the load side.

For example, in the load power calculation unit 204 of the measurement unit 102 on the power supply side, the current current Calculate the full load power Wa.

The input unit 201 of the power monitoring device 200 receives the load power Wa in addition to the line-to-line voltage (phase-to-phase voltage) and the line current of each phase from the measurement unit 102 on the power supply side. Then, the balanced load line current IR0 (=IT0) is calculated based on the equation (5) in the balanced line current calculator 205 . Other configurations of the power monitoring device 200 are the same as those of the first embodiment.

In this embodiment, as in the first embodiment, even if information on the type of wiring, wire diameter, and distance in the user's environment cannot be obtained, it is possible to obtain and display the line loss of each phase and the entire wiring. can. Also, the wiring loss value (energy-saving effect) that can be reduced by connecting the load to the balanced load can be obtained and displayed.

100 Power wiring 101 Personal computer 102 Power supply side measurement unit 103 Load side measurement unit 104 RS-485 communication line 105 Transmission side measurement point 106 Entrance side measurement point 200 Power monitoring device 201 Input Section 202 Line resistance calculation section 203 Current line loss calculation section 204 Current load power calculation section 205 Balanced line current calculation section 206 Balanced line loss calculation section 207 Improved line loss calculation section 208 display

Claims (8)

A power supply side measurement unit that measures the power supply side of the power wiring, a load side measurement unit that measures the load side of the power wiring, and measurement signals are input from the power supply side measurement unit and the load side measurement unit. , and a power monitoring device that performs power monitoring, wherein
The power monitoring device
A line resistance calculation unit that calculates a line resistance from the interphase voltage and the line current of each phase measured by the measurement unit on the power supply side and the interphase voltage measured by the measurement unit on the load side;
a current line loss calculation unit that obtains the current line loss of each phase and the total line loss from the line current of each phase measured by the measurement unit on the power supply side and the line resistance obtained by the line resistance calculation unit;
a display for displaying the current line loss of each phase and the total line loss;
A power monitoring system comprising: The power monitoring system of claim 1, wherein
The power monitoring device further comprises:
a current load power calculation unit that calculates the current load power from the phase-to-phase voltage and the line current of each phase measured by the power supply side measurement unit or the load side measurement unit;
a balanced line current calculation unit that obtains a line current under balanced load from the current load power and the phase-to-phase voltage measured by the power supply side measurement unit or the load side measurement unit;
A balanced line loss calculator that obtains the line loss of each phase and the total line loss under balanced load;
an improved line loss calculation unit that obtains a line loss that can be improved from the current total line loss and the total line loss at equilibrium;
with
The power monitoring system, wherein the display unit displays the line loss that can be improved. The power monitoring system of claim 1, wherein
The measurement unit on the power supply side or the measurement unit on the load side includes a current load power calculation unit that calculates the current load power from the phase-to-phase voltage and the line current of each phase,
The power monitoring device further comprises:
a balanced line current calculation unit that obtains a line current under balanced load from the current load power and the phase-to-phase voltage measured by the power supply side measurement unit or the load side measurement unit;
A balanced line loss calculator that obtains the line loss of each phase and the total line loss under balanced load;
an improved line loss calculation unit that obtains a line loss that can be improved from the current total line loss and the total line loss at equilibrium;
with
The power monitoring system, wherein the display unit displays the line loss that can be improved. In the power monitoring system according to claim 2 or 3,
The power monitoring system, wherein the display unit further displays the line loss of each phase and the total line loss under balanced load. In the power monitoring system according to any one of claims 1 to 4,
A power monitoring system, wherein the measurement unit on the power supply side and the measurement unit on the load side maintain simultaneity of measured values by broadcast communication from a power monitoring device. In the power monitoring system of claim 5,
A power monitoring system, wherein the power supply side measurement unit and the load side measurement unit are connected to the power monitoring device by a multi-drop method. In the power monitoring system according to any one of claims 1 to 6,
The power monitoring system, wherein the power wiring is single-phase three-wire wiring. In the power monitoring system of claim 7,
The power monitoring system, wherein the display unit graphically displays a difference between an R-phase line current and a T-phase line current.

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