Electric power monitoring system, and electric power monitoring method

Abstract

To achieve shortening the blackout time taken for installing devices for power measurement and monitoring at a plurality of sites.SOLUTION: An electric power monitoring system comprises: a first voltage sensor 10 and first current sensor 11; a first electric power detection unit 100 that obtains outputs of the respective sensors; a second current sensor 12; a second electric power detection unit 200 that inputs an output of the second current sensor 12, and operates with time information being in synchronization with the first electric power detection unit 100; a voltage estimation unit that estimates a voltage at an installation site of the second electric power detection unit 200 from the outputs of the respective electric power detection units 100 and 200; and a data analysis accumulation unit 2 that includes an electric power calculator calculating an electric power at a site where the second electric power detection unit is to be installed based on an output of the voltage estimation unit. The electric power detection units 100 and 200 perform processing in synchronization with times that the units have respectively.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power monitoring system and a power monitoring method. [Background technology]

[0002] Amid concerns about rising electricity rates due to rising fuel prices, there is a need to visualize how much electricity is being consumed by each piece of equipment and device in a building containing multiple pieces of equipment. However, power measurement requires measuring voltage and current, and to ensure work safety, adding a power measurement point requires opening the upper breaker in the installation area and putting the lower system into a power outage. This poses a problem: adding power measurement points within a building is not easy. Furthermore, to avoid affecting ongoing business operations within the building, work is often scheduled outside of business days. In such cases, additional costs are incurred for work on holidays and public holidays, as well as daily allowances for those present at the work, making it difficult to add more measurement points.

[0003] Patent Document 1 describes a technology for detecting the power consumption of multiple devices in a building by using a single voltage measurement point, installing multiple current sensors, and aggregating the voltage measurement information and the current measurement information from the multiple current sensors into a single measurement unit to calculate the power consumption of each device. The technology described in Patent Document 1 is intended for use in an ordinary house. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4881467 Summary of the Invention [Problem to be solved by the invention]

[0005] In buildings such as medium-sized or larger office buildings and commercial buildings housing multiple tenants, the power receiving point is often a high-voltage system such as 6.6 kV, and the equipment consuming power is often low-voltage equipment with different voltage classes such as 100 V, 200 V, and 400 V. Voltage conversion when multiple voltages are required is achieved using a transformer installed in the building. In this case, the point where voltage is measured and the point where power is measured are in different voltage classes, and power measurement cannot be performed using the method disclosed in Patent Document 1, which is designed for an ordinary house.

[0006] Furthermore, in the case of large office buildings or commercial buildings, it is expected that measurement points will be installed in distant locations, and wiring work will be required to lay the output signal lines of multiple current sensors to the power measurement unit, resulting in further increases in costs.

[0007] In view of these points, the present invention aims to provide a power monitoring system and a power monitoring method that can shorten the power outage time required to install devices for power measurement and monitoring at multiple locations. [Means for solving the problem]

[0008] In order to solve the above problems, for example, the configurations described in the claims are adopted. The present application includes multiple means for solving the above-mentioned problems. One example is a power monitoring system that detects power at multiple locations within the same building, comprising: a first voltage sensor and a first current sensor that detect the voltage and current at a point where a first power detection target device is connected downstream; a first power detection unit that inputs the output signal of the first voltage sensor and the output signal of the first current sensor; a second current sensor that detects the current at a point where a second power detection target device is connected downstream; a second power detection unit that inputs the output signal of the second current sensor and operates in synchronization with the first power detection unit in terms of time information; a voltage estimator that estimates the voltage at the installation location of the second power detection unit from the output of the first power detection unit and the output of the second power detection unit; and a power calculator that calculates the power at the installation location of the second power detection unit based on the output of the voltage estimator. Here, the first power detection unit and the second power detection unit have a function of synchronizing the time held by each unit. The second power detection unit then performs rotational coordinate conversion of the output of the second current sensor using a reference sine wave calculated based on the time held by the unit, and transmits the conversion result to the first power detection unit. The first power detection unit performs rotational coordinate transformation on the outputs of the first voltage sensor and the first current sensor, and transmits the rotational coordinate transformed values ​​and the current transformation results calculated by the second power detection unit to the data analysis and storage unit. The data analysis and storage unit estimates the voltage coordinate transformation value at the point where the second power detection unit measures the current based on the input voltage and current and circuit diagram information including impedance information within the building. [Effects of the Invention]

[0009] According to the present invention, when power measurement points in a low-voltage circuit are increased, there is no need to install additional voltage sensors, and power measurement and monitoring at multiple points can be easily performed. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a configuration diagram showing an example of a power monitoring system according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a configuration diagram showing an example of a first power detection unit of the power monitoring system according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a configuration diagram showing an example of a second power detection unit of the power monitoring system according to the first embodiment of the present invention. [Figure 4] FIG. 2 is a configuration diagram showing an example of a data analysis and accumulation unit of the power monitoring system according to the first embodiment of the present invention. [Figure 5] FIG. 2 is a configuration diagram showing an example of a voltage estimator of the power monitoring system according to the first embodiment of the present invention. [Figure 6] FIG. 3 is a diagram showing an example of impedance map information handled by the power monitoring system according to the first embodiment of the present invention. [Figure 7] FIG. 2 is a diagram illustrating an example of the operation of the power monitoring system according to the first embodiment of the present invention. [Figure 8] FIG. 10 is a configuration diagram showing an example of a power monitoring system according to a second embodiment of the present invention. [Figure 9] FIG. 10 is a configuration diagram showing an example of a GPS receiver of a power monitoring system according to a second embodiment of the present invention. [Figure 10] FIG. 10 is a configuration diagram showing an example of a first power detection unit of a power monitoring system according to a second embodiment of the present invention. [Figure 11] FIG. 10 is a configuration diagram showing an example of a second power detection unit of a power monitoring system according to a second embodiment of the present invention. [Figure 12] FIG. 10 is a diagram illustrating an example of synchronization processing according to a second embodiment of the present invention. [Figure 13] FIG. 10 is a configuration diagram showing an example of a power monitoring system according to a third embodiment of the present invention. [Figure 14] FIG. 10 is a configuration diagram showing an example of a first power detection unit of a power monitoring system according to a third embodiment of the present invention. [Figure 15] FIG. 10 is a configuration diagram showing an example of a data analysis and accumulation unit of a power monitoring system according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] <First embodiment> A power monitoring system and a power monitoring method according to a first embodiment of the present invention will be described below with reference to FIGS.

[0012] [Overall configuration of the power monitoring system] FIG. 1 shows the overall configuration of a power monitoring system according to this embodiment. Loads 50, 51, and 52 in building 500 receive power from a power system (not shown) via a circuit breaker 20 that connects to the power grid within the building, and transformers 31, 32, and 33. The main loads in building 500 are load 50 and load 51, which are low-voltage loads with nominal voltages of 420 V and 220 V, respectively. Load 52 is a collection of devices with low power consumption, such as lighting and outlet loads. The power monitoring system 1 of this embodiment detects the power of the main loads, loads 50 and 51, using a smaller number of voltage detection means than the number of measurement points.

[0013] The power monitoring system 1 is composed of a first power detection unit 100, a second power detection unit 200, a three-phase voltage detector 10, a three-phase current detector 11, a three-phase current detector 12, a data analysis and storage unit 2, a user interface 3, and a PTP switching hub 80. The first power detection unit 100 is installed near the load 50 . The second power detection unit 200 is installed near the load 51 . The three-phase voltage detector 10 detects the voltage (three-phase power) of the wiring that supplies AC power to the load 50 (first voltage detection process). The three-phase current detector 11 measures the current flowing into the load 50 (first current detection process). The three-phase current detector 12 measures the current flowing into the load 51 (second current detection process). The user interface 3 displays the power monitoring results and the like using an application program installed on the computer terminal. The PTP switching hub 80 is connected to a first power detection unit 100 and a second power detection unit 200 .

[0014] In addition, the first power detection unit 100 and the second power detection unit 200 are provided with wireless communication antennas 41 and 42, respectively, and wireless communication between the first power detection unit 100 and the second power detection unit 200 can be performed.

[0015] [Configuration of the first power detection unit] FIG. 2 shows an example of a data processing configuration of the first power detection unit 100. As shown in FIG. The first power detection unit 100 includes a digital signal processor, and an arithmetic unit within this processor realizes the arithmetic functions described below. The power detection unit 100 detects three-phase voltages insulated from the power lines using a three-phase voltage detector 10. The output of the three-phase voltage detector 10 is converted by an amplifier circuit 101 into U-phase and W-phase voltage signals based on the V-phase, and the outputs are output to AD converters 102 and 103, respectively.

[0016] The AD converters 102 and 103 convert the voltage input from the amplifier circuit 101 into a digital signal, and output a V-phase reference U-phase voltage conversion value v uv_1 , W-phase voltage conversion value v based on V-phase wv_1 is input to the phase voltage calculator 104. The phase voltage calculator 104 calculates the phase voltage value v excluding the zero-phase voltage according to the following equation: u_1 , v v_1 , v w_1 Calculate.

[0017]

number

[0018] The U-phase voltage calculation value v, which is the output of the phase voltage calculator 104, u_1 , V phase voltage calculation value v v_1 , W phase voltage calculation value v w_1 is input to the α-β converter 105, which converts the α component v alp_1 , β component v bet_1 is calculated.

[0019]

number

[0020] The α-β converter 105 outputs the output to the dq converter 106 . The three-phase current detector 11 is composed of clamp-type current sensors 11u, 11v, and 11w provided on each phase of the power line. These clamp-type current sensors 11u, 11v, and 11w are current sensors that can detect the current flowing through the power lines by clamping them, and can be installed without removing the insulation coating of the power lines, allowing them to be installed in a live state.

[0021] The outputs of the clamp-type current sensors 11u, 11v, and 11w are output to AD converters 121, 122, and 123, respectively. The AD converters 121, 122, and 123 convert the outputs of the clamp-type current sensors 11u, 11v, and 11w into digital signals to generate phase current detection values ​​i u_1 , i v_1 , i w_1 The phase current detection value i u_1 , i v_1 , i w_1 is input to the α-β converter 124. The α-β converter 124 converts the phase current detection value into a two-phase quantity, the current α component i alp_1 , i bet_1 The α-β converter 124 outputs the output to the dq converter 125.

[0022] The timer 112 is a timer that determines the time of the power detection unit 100, and the time information that is the output of the timer 112 is output to the sine wave table 113. The sine wave table 113 calculates a phase θ1 (=2πf0t1) based on the input time information t1 [s] and the nominal frequency f0 [Hz] of the AC system, and outputs reference sine waves cos θ1 and sin θ1 that correspond to the calculated phase to the dq converters 106 and 125. In other words, the sine wave table 113 functions as a reference sine wave generator (first reference sine wave generator). The dq converter (first rotating coordinate converter) 106 uses the reference sine waves cosθ1 and sinθ1 to calculate the α-β component v of the voltage according to the following equation: alp_1 , v bet_1 is rotated and the output is v d_1 , v q_1 are output to low-pass filters (first low-pass filters) 107 and 108, respectively.

[0023]

number

[0024] Similarly, the dq converter (second rotating coordinate converter) 125 uses the reference sine waves cosθ1 and sinθ1 to convert the α-β component i of the current into alp_1 , i bet_1 is rotated and the output is i d_1 , i q_1 are output to low-pass filters (second low-pass filters) 126 and 127, respectively. The low-pass filters 107, 108, 126, and 127 perform digital filtering on the input signal, respectively, with low-pass filter characteristics that allow only low-frequency components below a predetermined frequency to pass. dfil_1 , the output v of the low-pass filter 108 qfil_1 , the output of the low-pass filter 126 i dfil_1 and the output of low-pass filter 127 i qfil_1 is output to the PQ calculator 128 and the serial communication interface 132.

[0025] The PQ calculator 128 calculates the complex voltage vector v1(v dfil_1 +jv qfil_1 ), complex current vector i1(i dfili_1 +ji qfil_1 ), the active power and reactive power flowing into the load 50 are calculated according to the following formula (first power detection process). Here, the coefficient 3 / 2 is multiplied because the dq converted values ​​are values ​​corresponding to the amplitudes, not the effective values ​​of the voltage and current, and because the power to be calculated is the power consumption for three phases, so the power is three times the power value calculated from the phase voltage effective values ​​and phase current effective values.

[0026]

number

[0027] The outputs P1 and Q1 of the PQ calculator 128 are output to the serial communication interface 132, respectively. The power detection unit 100 is connected to the wireless communication antenna 41 via the wireless communication interface 131, and detects the current active component i of the load 51 transmitted from the power detection unit 200 (described later). dfil_2 , inactive ingredient i qfil_2 and outputs them to the serial communication interface (first interface) 132. The signal v dfil_1 , v qfil_1 , i dfil_1 , i qfil_1 , i dfil_2 , i qfil_2 is output to the data analysis and storage unit 2 via serial communication.

[0028] Here, we will explain time synchronization, which is one of the features of this embodiment. The power detection unit 100 is connected to the PTP switching hub 80 via a PTP switching hub interface 111. The power detection unit 200 is similarly connected to the PTP switching hub 80 via an interface. PTP stands for Precision Time Protocol, and is a network time synchronization standard that achieves highly accurate time synchronization in microsecond units. The power detection units 100 and 200 achieve time synchronization by transmitting time information from the power detection unit 100 to the power detection unit 200 via the PTP switching hub 80.

[0029] The timer 112 outputs time information t1[s] synchronized with the power detection unit 200 to the sine wave table 113 as described above, thereby making it possible to calculate reference sine waves cosθ1 and sinθ1 that are in phase with the power detection unit 200. The calculations in the power detection unit 100 are realized by discrete-time calculations in a signal processor such as a DSP. From the viewpoint of phase information synchronization, it is desirable that the period of the discrete-time calculations be sufficiently short compared to one cycle of the power system. Since power measuring instruments generally use instruments with a detection error of less than 1%, it is desirable that the phase error due to the calculation start timing of the discrete-time calculations be less than 1%. For example, in the 50 Hz band, it is desirable that the calculation period be less than 1 / 100 of the nominal power supply period of 20 ms, i.e., less than 200 μs.

[0030] [Configuration of the second power detection unit] FIG. 3 shows the configuration of the second power detection unit 200. As shown in FIG. The second power detection unit 200, like the first power detection unit 100, receives the output signal of the three-phase current detector 12 as input, performs coordinate conversion on the detected current value flowing into the load 51 using reference sine waves cosθ2 and sinθ2 generated within the signal processor, and transmits the output to the power detection unit 100 via wireless communication.

[0031] Specifically, as shown in FIG. 3, the current flowing into the load 51 is detected by three clamp-type current sensors 12u, 12v, and 12w that constitute the three-phase current detector 12, and the outputs are converted into digital signals by AD converters 221, 222, and 223, respectively, to produce current detection values ​​i u_2 , i v_2 , i w_2 get. Current detection value i u_2 , i v_2 , i w_2 is input to the α-β converter 224 and is subjected to α-β conversion using the conversion matrix shown in [Equation 2]. The output value i alp_2 , i bet_2 is output to the dq converter 225.

[0032] The timer 202 is connected to the PTP switching hub 80 described above via the PTP switching hub interface 201, thereby making it possible to calculate time t2 synchronized with the timer 112 in the first power detection unit 100. This time t2 is output to the sine wave table 203, which calculates a phase θ2 (=2πf0t2) based on the input time information t2 [s] and the nominal frequency f0 [Hz] of the AC system, and outputs reference sine waves cos θ2 and sin θ2 corresponding to this phase θ2 to the dq converter 225. In other words, the sine wave table 203 functions as a reference sine wave oscillator (second reference sine wave generator). With this configuration, the first power detection unit 100 and the second power detection unit 200 have reference sine waves that are substantially in phase with each other.

[0033] The dq converter (third rotational coordinate converter) 225 converts i alp_2 , i bet_2 is rotated and the output i d_2 , i q_2 are output to the low-pass filters 226 and 227.

[0034]

number

[0035] The low-pass filters 226 and 227 perform digital filtering with low-pass filter characteristics on the input signals, and the output i dfil_2 , i qfil_2 is output to the wireless communication interface 228.

[0036] With the above configuration, the d-axis component v of the receiving voltage of the load 50, which has been coordinate-transformed with approximately the same phase, dfil_1 , q-axis component v qfil_1、 Input current d-axis component i of load 50 dfil_1 , q-axis component i qfil_1 , the input current d-axis component i of the load 51 dfil_2 , q-axis component i qfil_2 can be obtained. The d-axis and q-axis components of these voltages and currents, as well as the active power P1 and reactive power Q1 consumed by the load 50 calculated by the first power detection unit 100, are output to the data analysis and storage unit 2 via serial communication.

[0037] Here, the advantage of the second power detection unit 200 performing rotational coordinate transformation on the three-phase currents obtained by the three-phase current sensor 12, applying a low-pass filter to the converted data, and transmitting the data to the power detection unit 100 will be described. The load current is not necessarily sinusoidal. For example, in the case of a load that converts AC power to DC power using diode rectification, the current flowing from the power grid contains not only the fundamental wave component but also harmonic components such as fifth and seventh order. If the detected instantaneous value of the current is transmitted from the power detection unit 200, the fundamental wave current will be large due to the harmonics, and the transmitted value will be sampled at a different timing, making it impossible to accurately transmit the fundamental wave component contained in the load current. If a filter operation is performed to remove harmonic components while leaving the AC components as they are, the harmonic components may be reduced, but the phase of the fundamental wave component will be shifted.

[0038] By performing rotational coordinate transformation, the input current of the load 51, which is an AC current, can be converted into a DC current, and by applying a low-pass filter to this value, the harmonic components that are mixed in can be reduced. In addition, even if there is a delay or a retry in communication between the first power detection unit 100 and the second power detection unit 200, no phase shift occurs in the fundamental wave detection information of the current flowing into the load 51. As described above, by using the configuration of this embodiment, fundamental wave component information of the load current can be accurately transmitted to the first power detection unit 100 with high precision.

[0039] [Data Analysis and Storage Unit Configuration] FIG. 4 shows the configuration of the data analysis and storage unit 2. The data analysis and storage unit 2 receives each data transmitted from the first power detection unit 100 via the serial communication interface 21. The voltage data (v dfil_1 , v qfil_1 ), current data (id fil_1 , i qfil_1 , i dfil_2 , i qfil_2 ) is output to the voltage estimator 23, which is one of the features of this embodiment. The voltage estimator 23 uses the impedance map data Z_map_data input via the impedance map input interface 22, and performs vector operations and low-pass filter operations (to be described later) on the voltage data and current data to derive the d-axis component v of the receiving voltage of the load 51. dfil_2_est , v qfil_2_est is calculated and output to the PQ calculator 24. This calculation makes it possible to estimate the input voltage value of the load 51 without the need to install an additional voltage sensor.

[0040] The PQ calculator 24 (second power detection process) is a power calculator that calculates the current data i in addition to the output of the voltage estimator 23. dfil_2 , i qfil_2 is used as an input, and the active power P2 and reactive power Q2 consumed by the load 51 are calculated according to the following equations.

[0041]

number

[0042] The powers P1, Q1, and PQ calculated by the first power detection unit 100 and the powers P2 and Q2 calculated by the calculator 24 are output to the recording device 25 and stored together with time information managed by the timer 27 in the data analysis and storage unit 2. Here, the time of the timer 27 does not need to be synchronized with high precision as in the power detection units 100 and 200. The recording device 25 is connected to the user interface 3 via the user interface port 26, and the desired power measurement data can be displayed by operating the user interface 3.

[0043] [Configuration of voltage estimator] FIG. 5 shows the configuration of the computing unit of the voltage estimator 23. The voltage estimator 23 includes a group of computing units 310, 320, 330, 340, and 350. The computing unit group 310 calculates the voltage drop that occurs in the transformer 30 and in the wiring from the transformer 30 to the load 50 due to the load current flowing into the load 50 . The computing unit group 320 estimates the primary side voltage of the transformer 30 from the voltage drop calculation value obtained by the computing unit group 310 and the voltage detection value in the vicinity of the load 50 . The computing unit group 330 estimates the secondary voltage of the transformer 31 when there is no load from the estimated value of the transformer primary voltage. The computing unit group 340 calculates the voltage drop that occurs in the transformer 31 due to the load 51 and in the wiring from the transformer 31 to the load 51 . The group of arithmetic units 350 calculates the input voltage of the load 51 from the outputs of the groups of arithmetic units 330 and 340 .

[0044] The computing unit group 310 calculates in advance the sum R1 [Ω] of the resistance value of the wiring from the secondary terminal of the transformer 30 to the load 50 and the secondary-side converted value of the winding resistance of the transformer 30, which are included in the impedance map data Z_map_data, and the sum X1 [Ω] of the reactance of the wiring from the secondary terminal of the transformer 30 to the load 50 and the secondary-side converted value of the reactance due to leakage of the transformer 30. Then, these sums R1 and X1 and the current component i dfil_1 , i qfil_1 5, multipliers 311, 312, 313, and 314 and adder-subtractors 315 and 316 perform vector calculations to calculate the voltage drop due to the current flowing into the load 50.

[0045] The group of calculators 320 calculates the voltage drop obtained by the adder / subtractor 315 and 316 and the voltage detection value v in the vicinity of the load 50. dfil_1 , v qfil_1 are combined by adder-subtractors 321 and 322 to calculate a secondary converted value of the primary voltage of transformer 30. Then, calculator group 320 calculates a voltage ratio V1TR1 / V2TR1 from the primary rated voltage V1TR1 [V] and secondary rated voltage V2TR1 [V] of transformer 30 included in the impedance map data Z_map_data, and multipliers 323 and 324 convert the secondary converted value of the primary voltage of transformer 30 into a primary voltage. Furthermore, the phases of the primary side voltage and the secondary side voltage may differ depending on the winding structure of the transformer 30. The computing unit group 320 derives in advance the phase φ1 by which the primary side voltage leads the secondary side voltage from the winding configuration information included in the impedance map data Z_map_data, and performs a phase correction calculation on the complex plane using the phase corrector 325, and outputs the result to the computing unit group 330.

[0046] The computing unit group 330 derives in advance a phase φ2 by which the secondary side voltage leads the primary side voltage of the transformer 31 from winding structure information of the transformer 31 included in the impedance map data Z_map_data. The computing unit group 330 then performs a phase correction calculation on the complex plane using a phase corrector 331 on the primary side voltage of the transformer 30 calculated by the computing unit group 320, and outputs the output to a multiplier 332. The computing unit group 330 calculates a voltage ratio V2TR2 / V1TR2 from the primary side rated voltage V1TR2 [V] and secondary side rated voltage V2TR2 [V] of the transformer 31 included in the impedance map data Z_map_data, multiplies the voltage ratio V2TR2 / V1TR2 by the output of the phase corrector 331, and calculates the secondary side output voltage of the transformer 31 when there is no current flowing to the load 51.

[0047] The computing unit group 340 calculates in advance the sum R2 [Ω] of the resistance value of the wiring from the secondary terminal of the transformer 31 to the load 51 and the secondary-side converted value of the winding resistance of the transformer 31, which are included in the impedance map data Z_map_data, and the sum X2 [Ω] of the reactance of the wiring from the secondary terminal of the transformer 31 to the load 51 and the secondary-side converted value of the reactance due to leakage of the transformer 31. Then, the computing unit group 340 calculates the sum R2 of the secondary-side converted values ​​of the winding resistance, the sum X2 of the secondary-side converted values ​​of the reactance, and the current component i dfil_2 , i qfil_2 5 performs vector calculations to calculate the voltage drop due to the current flowing into the load 51. The calculated voltage drop value is output to the group of calculators 350.

[0048] The computing unit group 350 adds the output of the computing unit group 330 and the output of the computing unit group 340 using adder-subtractors 351 and 352, respectively, to obtain the d-axis component v of the input voltage estimate value of the load 51. dfil_2_est , q-axis component v qfil_2_est Calculate.

[0049] [Example of impedance map data] FIG. 6 shows a specific example of the impedance map data Z_map_data. As shown in FIG. 6, the impedance map data Z_map_data includes the rated voltage, rated capacity, and self-capacity-based percent impedance value (%R, %X) of each transformer 31, 32, 33, and the rated capacity and percent impedance value of the cable that is the wiring. In this embodiment, it is assumed that the power consumption of load 52 supplied by transformer 33 is smaller than that of loads 50 and 51, and that the voltage drop caused by load 52 in the common bus bar to which the primary sides of transformers 31, 32, and 33 are connected can be ignored.

[0050] 7 shows the power measurement values ​​and the analysis results of the load power estimated by the power monitoring system 1 of this embodiment when loads 50, 51, and 52 are operating at rated power as an initial condition in the power grid in building 500 shown in FIG. 6 and load 51 stops operating at time 0.05 seconds. The graph in FIG. 7A shows the active power P1 and reactive power Q1 of load 50. The graph in FIG. 7B shows the active power P2 and reactive power Q2 of load 51. The graph in FIG. 7C shows the active power P3 and reactive power Q3 of load 52.

[0051] 7A, the solid lines indicate the active power P1_m [kW] and reactive power Q1_m [kvar] that actually flow into the load 50, and the dashed lines indicate the active power P1_c [kW] and reactive power Q1_c [kvar] calculated by the power detection unit. It can be seen that in a steady state, the power detection unit 100 of this embodiment can accurately calculate the actual active power and reactive power.

[0052] The graph in Figure 7B shows the active power P2_m [kW] and reactive power Q2_m [kvar] that actually flow into load 51, as well as the active power P2_c [kW] and reactive power Q2_c [kvar] estimated by power monitoring system 1. It can be seen that in steady state, the estimated values ​​match well with the actual active power and reactive power. At 0.05 [s], when load 51 stops operating, there is a delay in the digital filter, and a transient difference is seen between the actual active power and reactive power and the estimated values, but this deviation is resolved within about 0.01 [s], confirming that the estimation is satisfactory from the perspective of power monitoring.

[0053] The graph in FIG. 7C shows the active power P3 and reactive power Q3 consumed by the load 52, which is smaller than the loads 50 and 51.

[0054] In this embodiment, information about the current flowing into the load 51 is wirelessly transmitted from the second power detection unit 200 to the first power detection unit 100, but the same effect can be achieved even if communication is via a wire. Furthermore, in this embodiment, the example in which only the load 51 is added as an object to be measured for power consumption has been shown, but the same effect can be achieved even if a plurality of loads or power measurement points are added for measurement. Furthermore, although in this embodiment, the three-phase current detectors 11 and 12 each include three current sensors, the same effect can be achieved by installing current sensors only in the U and W phases, for example, and calculating the V-phase current component by the calculator on each power detection unit 100 and 200, assuming that the zero-phase component included in the V-phase current load current is zero.

[0055] [Effects of the first embodiment] According to the first embodiment, when a power measurement point equipped with a voltage detector is already installed, it is possible to add a power measurement point without installing an additional voltage sensor. Furthermore, by using a clamp-type current sensor as the current sensor for the additional power measurement point, it is possible to add a measurement point without causing a power outage in the downstream system to which the load is connected, as long as the power detection is low voltage. Furthermore, since this power monitoring system is equipped with a vector calculation function that uses impedance map data containing information on the transformer winding configuration, it is possible to estimate the voltage at the additional power detection point even in a building equipped with multiple transformers.

[0056] <Second embodiment> Next, a power monitoring system and a power monitoring method according to a second embodiment of the present invention will be described with reference to Figures 8 to 12. In Figures 8 to 12, the same elements as those in Figures 1 to 7 described in the first embodiment will be assigned the same reference numerals, and duplicated explanations will be omitted.

[0057] [Overall configuration of the power monitoring system] The difference between the first and second embodiments is that the first power detection unit 100 and the second power detection unit 200 obtain reference sine waves with approximately the same phase by time synchronization using a 1PPS signal, which is a time reference signal from the GPS (Global Positioning System), rather than time synchronization via a PTP switching hub 80. GPS is a system that receives positioning satellite signals to determine a location, and transmits a 1PPS signal, which is a time reference signal, from the satellite.

[0058] The 1PPS signal is a pulse signal output every second synchronized with UTC, a time series managed by the U.S. Naval Observatory, and its error is at most a few tens of nanoseconds. Therefore, by using the 1PPS signal in the power monitoring system of this embodiment, it is possible to detect power without a voltage sensor at an additional power measurement point located in a different location within the same building, without the need for long-distance communication lines or special hubs. The configuration of this embodiment will be described in detail below.

[0059] FIG. 8 shows an overall configuration diagram of a power monitoring system 1a according to this embodiment. As in the first embodiment, in order to detect the power of the loads 50 and 51, the outputs of the three-phase voltage detector 10 and the three-phase current detector 11 are input to a first power detection unit 100, and the output of the three-phase current detector 12 is input to a second power detection unit 200.

[0060] The first power detection unit 100 and the second power detection unit 200 each receive a 1PPT signal output from the GPS antenna sets 61 and 62. The first power detection unit 100 and the second power detection unit 200 then generate reference sine waves with approximately the same phase using counters whose timing is corrected by the 1PPT signal. Other configurations of the first power detection unit 100 and the second power detection unit 200 are the same as those of the first power detection unit 100 and the second power detection unit 200 described in the first embodiment.

[0061] [Configuration for generating a reference sine wave] The following describes a configuration in which the power detection unit generates a time-synchronized count value using the 1PPS signal output from the GPS antenna set 61, 62, and a configuration in which the output of this counter is used to generate a reference sine wave with approximately the same phase. 9 shows the configuration of the GPS antenna set 61. The GPS antenna set 61 is made up of a GPS antenna 61a and a GPS module 61b. The GPS antenna 61a receives GPS signals and outputs the signals to the GPS module 61b. The GPS module 61b controls its own oscillator at the precise time determined by GPS positioning, generates a 1PPS signal, which is a time pulse that becomes active every second, and outputs this 1PPS signal to the first power detection unit 100. The GPS module that generates the 1PPS signal using a GPS antenna is a known configuration, and a detailed description thereof will be omitted. Similarly, the GPS antenna set 62 shown in FIG. 8 also generates a 1PPS signal and outputs the 1PPS signal to the second power detection unit 200 .

[0062] Next, a method for generating a reference sine wave using a 1PPS signal and its configuration will be described with reference to FIGS. FIG. 10 shows the configuration of the first power detection unit 100. As shown in FIG. The difference from the power detection unit 100 in the first embodiment is that the input of the sine wave table 113 is a counter 142 instead of the timer 112 (FIG. 2). That is, the 1PPS signal, which is the output signal of the GPS antenna set 61, is input to the counter 142 via the GPS interface 141 as a reset signal.

[0063] Counter 142 is an up-counter that increments every calculation cycle and resets the count value at a counter upper limit value N0 corresponding to one second. Counter 142 also has a reset function, and resets the counter value upon detecting an edge where the 1PPS signal output from GPS interface 141 changes from L level to H level. This makes it possible to configure an up-counter with a one-second cycle even if there are slight fluctuations in the clock within first power detection unit 100 or the period of the interrupt signal that controls the calculation cycle.

[0064] An image of the count value of the counter 142 and the 1PPS signal is shown in FIG. The upper part of the graph in FIG. 12 shows the count value CNT of the counter 142, and the lower part shows the 1PPS signal. time t i At [s], the count value is 0, and the edge detection timing of the 1PPS signal from L to H is synchronized. The counter 142 continues counting up until N0, after which the counter value is reset and counting up again.

[0065] time t i At +1.0 [s], an L→H edge is detected in the 1PPS signal. Based on this edge detection, counter 142 resets its count value. Note that the counter value indicated by the dashed line in Figure 12 indicates the counter value when counter 142 does not have this reset function. Counter 142 divides the count value by counter upper limit value N0 and outputs the normalized value to sine wave table 113. This allows time information in units of seconds to be input from counter 142 to the sine wave table, making it possible to generate a reference sine wave synchronized with the GPS time information.

[0066] 12 shows a configuration in which the count value of counter 142 is reset, but the counter upper limit value N0 may be corrected based on the count value at the reset timing. This correction reduces the phase jump of the reference sine waves cos θ1 and sin θ1 that occurs when the counter is reset by the 1PPS signal, enabling more accurate power detection.

[0067] Similarly, the second power detection unit 200 can also generate a reference sine wave synchronized with the GPS time information. FIG. 11 shows the configuration of the second power detection unit 200. As shown in FIG. Similar to the first power detection unit 100, the second power detection unit 200 inputs the 1PPS signal from the GPS antenna set 62 to a counter 242 via a GPS interface 241. Similar to the counter 142, the counter 242 counts up highly accurately in one-second cycles by inputting the 1PPS signal as a reset signal, and outputs a value obtained by normalizing the count value with an upper count limit as time information to a sine wave table 243. This enables the sine wave table 243 to generate reference sine waves cos θ2 and sin θ2 synchronized with the GPS time information.

[0068] [Effects of the second embodiment] With the above-described configuration, the power detection units 100 and 200 included in the power monitoring system of this embodiment can generate reference sine waves with approximately the same phase. Therefore, as in the first embodiment, even when a power measurement point equipped with a voltage detector is already present, additional power measurement points can be added without installing additional voltage sensors. Furthermore, in this embodiment, by using clamp-type current sensors for the current sensors at the additional power measurement points, low-voltage power detection can be performed without causing a power outage in the downstream system to which the load is connected. Furthermore, in this embodiment, the power monitoring system also includes a vector calculation function using impedance map data containing information on the transformer winding configuration, enabling voltage estimation at additional power detection points even in buildings equipped with multiple transformers.

[0069] Furthermore, in this embodiment, instead of time synchronization via the PTP switching hub 80 used in the first embodiment, a reference sine wave with approximately the same phase is obtained by time synchronization using a 1PPS signal from GPS, which makes it possible to detect power without a voltage sensor at an additional power measurement point located far away within the same building, without the need to lay long-distance communication lines or a special hub.

[0070] <Third embodiment> Next, a power monitoring system and a power monitoring method according to a third embodiment of the present invention will be described with reference to Figures 13 to 15. In Figures 13 to 15, the same elements as those in Figures 1 to 12 described in the first and second embodiments are given the same reference numerals, and duplicated explanations will be omitted.

[0071] [Overall configuration of the power monitoring system] The difference between this embodiment and the second embodiment is that the data analysis and storage unit is located outside the building 500. Therefore, unlike the second embodiment, this embodiment has a structure in which data is transmitted from the power detection units 100, 200 to the external data analysis and storage unit 2 via a network (Internet), and a power monitoring result report calculated by the data analysis and storage unit 2 is sent to the manager terminal 900 in the building 500 via the network. With this configuration, it is no longer necessary to install a data analysis and storage unit inside the building, and therefore it is possible to efficiently provide voltage sensorless power monitoring services at the additional power detection points shown in Examples 1 and 2 to multiple buildings.

[0072] 13 shows an overall configuration diagram of a power monitoring system 1b according to this embodiment. As in the first and second embodiments, in power monitoring system 1b, the outputs of three-phase voltage detector 10 and three-phase current detector 11 are input to a first power detection unit 100, and the output of three-phase current detector 12 is input to a second power detection unit 200, in order to detect the power of loads 50 and 51.

[0073] The power monitoring system 1b is composed of a three-phase voltage detector 10 and a three-phase current detector 11, as well as a first power detection unit 100, a second power detection unit 200, a data analysis and storage unit 2, a user interface 3, and a network 1000. The network 1000 uses, for example, the Internet communication network. Use of the Internet communication network is just one example, and the network 1000 may also be a public communication network shared with other users.

[0074] The first power detection unit 100 transmits ID data for identifying the building 500, and the detected or received voltage, current, and power information within the building 500, via a network 1000 to a data analysis and accumulation unit 2 provided in another building outside the building 500. The data analysis and accumulation unit 2 has a function of analyzing power based on the data received from the first power detection unit 100, and periodically reporting the results to an administrator terminal 900 in the building 500 via the network 1000.

[0075] [Configuration of the first power detection unit] FIG. 14 shows the configuration of the first power detection unit 100 of this embodiment. The first power detection unit 100 of this embodiment differs from the first power detection unit 100 of the second embodiment (FIG. 10) in that it newly includes an ID recording memory 133 that stores ID information for identifying the building 500, and this ID information and voltage, current, and power information are output via a network connection interface 132 rather than a serial communication interface. The data output from the network connection interface 132 is transmitted to the data analysis and storage unit 2 via a network 1000. The network connection interface 132 encrypts the transmission data and outputs the data to the network 1000.

[0076] [Data Analysis and Storage Unit Configuration] 15 shows the configuration of the data analysis and storage unit 2. The difference between the data analysis and storage unit 2 of the first and second embodiments is that the data analysis and storage unit 2 of this embodiment includes a network connection interface 21a, an impedance map data storage 28, and a power consumption calculation unit 29.

[0077] The network connection interface 21 a receives the data transmitted from the first power detection unit 100 . The impedance map data storage 28 extracts impedance map data of the building 500 using the ID information included in the data received via the network connection interface 21a as input. The power consumption calculation unit 29 links the ID information with the power monitoring results of the building 500 stored in the recording device 25, and reports the power monitoring results to the manager terminal 900 of the building 500 via the network 1000 at predetermined intervals. This executes the power monitoring report service. The network connection interface 21a decrypts the received data and transmits the data to the voltage estimator 23, PQ calculator 24, impedance map data storage 28, and power consumption calculator 29, respectively, as shown in FIG.

[0078] [Effects of the third embodiment] According to this embodiment, voltage estimation for a specific building becomes possible by providing impedance map data storage 28. Furthermore, power consumption calculation unit 29 extracts power monitoring results linked to building ID information from data stored in recording device 25 and transmits the results to manager terminal 900 of building 500 via a network, making it possible to provide power monitoring services without installing data analysis and storage unit 2 inside building 500. Furthermore, because high-speed processing is not required for information processing in the data analysis and storage unit 2, power monitoring services for multiple buildings can be realized with a single set of data analysis and storage unit and user interface 3. This reduces the amount of hardware required, and makes it possible to provide efficient services for multiple buildings.

[0079] As described above, according to this embodiment, as in the first and second embodiments, when a power measurement point equipped with a voltage detector is already installed, additional power measurement points can be added without installing additional voltage sensors. Furthermore, by using clamp-type current sensors for the additional power measurement points, low-voltage power detection can be achieved without causing a power outage in the downstream system to which the load is connected. Furthermore, the power monitoring system includes a vector calculation function using impedance map data containing information on the transformer winding configuration, enabling voltage estimation at additional power measurement points even in buildings equipped with multiple transformers. Furthermore, since the data analysis and storage unit 2 and its user interface 3 can be installed outside the building 500, the voltage sensorless power monitoring service at additional power measurement points shown in the first and second embodiments can be efficiently provided to multiple buildings.

[0080] <Modification> The embodiment examples described so far have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. In addition, in the configuration diagrams described in each embodiment, only control lines and information lines that are considered necessary for explanation are shown, and not all control lines and information lines in the product are necessarily shown. In reality, it can be considered that almost all components are interconnected. [Explanation of symbols]

[0081] 1, 1a, 1b...Power monitoring system, 2...Data analysis and storage unit, 3...User interface, 10...Three-phase voltage detector, 11, 12...Three-phase current detector, 11u, 11v, 11w, 12u, 12v, 12w...Clamp-type current sensor, 20...Circuit breaker, 21...Serial communication interface, 21a...Network connection interface, 22...Impedance map input interface, 23...Voltage estimator, 24...PQ calculator, 25...Recording device, 26...User interface port, 27...Timer, 28...Impedance map data storage, 29...Power consumption calculator, 30, 31, 32, 33...Transformer, 41...Wireless communication antenna, 50, 51, 52...Load, 61, 62...GPS antenna set, 61a...GPS antenna, 61b...GPS module, 80...PTP switching hub, 100...first power detection unit, 101...amplifier circuit, 102, 103...AD converter, 104...phase voltage calculator, 105...α-β converter, 106...dq converter, 107, 108...low-pass filter, 111...PTP switching hub interface, 112...timer, 113...sine wave table, 121...AD converter, 124...α-β converter, 125...dq converter, 126, 127...low-pass filter, 128...PQ calculator, 131...wireless communication interface, 132...serial communication interface, 132...network connection interface, 133...ID recording memory, 141...GPS interface, 142...counter, 200...second power detection unit, 201...PTP switching hub interface, 202...timer, 203...sine wave table, 221...AD converter, 224...α-β converter, 225...dq converter, 226, 227...low-pass filter, 228...wireless communication interface, 235...phase corrector, 241...GPS interface, 242...counter, 243...sine wave table, 310...computing unit group, 311 to 314...multiplier, 315, 316...adder / subtractor, 320...computing unit group, 321, 322...adder / subtractor, 323, 324...multiplier, 325...phase corrector, 330...computing unit group, 331...phase corrector, 332,333... multiplier, 340... computing unit group, 341 to 344... multiplier, 345, 346... adder / subtractor, 350... computing unit group, 351, 352... adder / subtractor, 500... building, 900... administrator terminal, 1000... network,

Claims

1. A power monitoring system that detects power at multiple locations in the same building, a first voltage sensor and a first current sensor for detecting a voltage and a current at a point where a first power detection target device is connected downstream; a first power detection unit that receives the output signal of the first voltage sensor and the output signal of the first current sensor; a second current sensor that detects a current at a point where a second power detection target device is connected downstream; a second power detection unit that receives an output signal from the second current sensor and operates in synchronization with time information of the first power detection unit; a voltage estimator that estimates a voltage at an installation point of the second power detection unit from an output of the first power detection unit and an output of the second power detection unit; a data analysis and storage unit including a power calculator that calculates power at a location where the second power detection unit is installed based on an output of the voltage estimator; the first power detection unit and the second power detection unit have a function of synchronizing the times of the respective units; the second power detection unit performs rotational coordinate transformation of the output of the second current sensor using a reference sine wave calculated based on a time held by the second power detection unit, and transmits the transformation result to the first power detection unit; the first power detection unit performs rotational coordinate transformation on the outputs of the first voltage sensor and the first current sensor, and transmits the rotational coordinate transformed value and the current transformation result calculated by the second power detection unit to the data analysis and storage unit; The data analysis and storage unit estimates a voltage coordinate transformation value at a point where the second power detection unit measures the current based on the input voltage and current and circuit diagram information including impedance information within the building. Power monitoring system.

2. The first power detection unit a first rotational coordinate converter that performs rotational coordinate conversion of the AC voltage detected by the first voltage sensor based on a first reference sine wave that is the calculated reference sine wave and an output of the first voltage sensor; a first low-pass filter that performs a digital filter operation having low-pass characteristics on the value converted by the first rotational coordinate converter; a second rotational coordinate converter that performs rotational coordinate conversion of the AC current detected by the first current sensor based on the first reference sine wave and the output of the first current sensor; a second low-pass filter that performs a digital filter operation having low-pass characteristics on the value transformed by the second rotational coordinate converter; a first interface for transmitting the output of the second low-pass filter to the data analysis and storage unit; The second power detection unit a second reference sine wave generator that generates a reference sine wave calculated based on time information synchronized with the time of the first power detection unit; a third rotational coordinate converter that performs rotational coordinate conversion of the AC current detected by the second current sensor based on a second reference sine wave that is an output of the second reference sine wave and an output of the second current sensor; a third low-pass filter that performs a digital filter operation having low-pass characteristics on the value converted by the third rotational coordinate converter; a second interface for transmitting the output of the third low-pass filter to the first power detection unit. The power monitoring system according to claim 1 .

3. The first power detection unit and the second power detection unit are connected to a common switching hub, and time information is synchronized when each power detection unit generates a reference sine wave by time synchronization via the switching hub. The power monitoring system according to claim 1 .

4. The time information is synchronized within 200 μsec. The power monitoring system according to claim 3 .

5. the first power detection unit and the second power detection unit each include a positioning satellite signal receiving unit that receives a positioning satellite signal and obtains time information included in the received signal; Each power detection unit generates a reference sine wave based on the time information obtained by the positioning satellite signal receiving unit. The power monitoring system according to claim 1 .

6. the data analysis and storage unit is installed in a building different from a building in which the first power detection unit and the second power detection unit are installed; The information including the rotation coordinate transformation values ​​of the voltage and current calculated by the first power detection unit and the second power detection unit is transmitted to the data analysis and storage unit via a network; The data analysis and storage unit estimates voltage based on the data received via the network, thereby calculating power at the installation location of the second power detection unit, and transmits information including the calculated power via the network to an administrator terminal of the building in which the first power detection unit and the second power detection unit are installed. The power monitoring system according to claim 1 .

7. Executes a power monitoring and reporting service by transmitting information including power to the administrator terminal. The power monitoring system according to claim 6 .

8. The second current sensor is a clamp-type current sensor. The power monitoring system according to any one of claims 1 to 7.

9. A power monitoring method for detecting power at multiple locations in the same building, comprising: a first voltage detection process for detecting a voltage and a current at a point where a first power detection target device is connected downstream; a first current detection process for detecting a current at the point; a first power detection process for detecting power using a voltage detection signal obtained by the first voltage detection process and a current detection signal obtained by the first current detection process as inputs; a second current detection process for detecting a current at a point where a second power detection target device is connected downstream; a second power detection process that receives a current detection signal from the second current detection process, and detects power by operating in synchronization with time information of the first power detection process; a data analysis process of estimating a voltage at a point where the second power detection process is performed from the detected power by the first power detection process and the detected power by the second power detection process, and calculating the power at the point where the second power detection process is performed based on the estimated power, performing time synchronization between the first power detection process and the second power detection process; In the second power detection process, an output of the second current detection process is subjected to a rotational coordinate transformation using a reference sine wave calculated based on the time obtained by the time synchronization, and the transformation result is transmitted to the first power detection process; In the first power detection process, outputs of the first voltage detection process and the first current detection process are subjected to rotational coordinate transformation, and the values ​​obtained by the rotational coordinate transformation and the current transformation result calculated in the second power detection process are transmitted to the data analysis process; In the data analysis process, a voltage coordinate transformation value of a point where a current is measured by the second power detection process is estimated based on the input voltage and current and circuit diagram information including impedance information in the building. Power monitoring method.

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