JP5773191B2 - Detection apparatus and method, and program - Google Patents

Description

  The present invention relates to a detection apparatus and method, and a program, and more particularly, to a detection apparatus and method suitable for use in detecting a power state of a facility including a private power generation apparatus, and a program.

  In recent years, with the widespread use of solar power generation systems and the start of a system for purchasing surplus power from solar power generation systems, the generation power and sales power (surplus power) of solar power generation systems and purchases from commercial power sources are also available in ordinary households. There is a growing need to know about power and household power consumption.

  Conventionally, surplus power from a private power generation device such as a solar power generation system is supplied to the commercial power supply side, and the power is sold (hereinafter referred to as a power sale state), or power is supplied from the commercial power supply. Has been proposed (see Patent Documents 1 to 3, for example). In the inventions described in Patent Documents 1 to 3, the voltage and current of the power system on the commercial power supply side are measured, the power is calculated from the measured voltage and current, and the power is calculated based on the calculated sign (positive or negative) of the power. The power flow direction is detected, and it is determined whether the power purchase state or the power sale state.

JP 2004-279321 A JP 2004-297959 A Japanese Patent Laid-Open No. 11-225440

  By the way, in order to measure the voltage of the power system on the commercial power supply side (hereinafter referred to as a commercial power system) in a general home, it is necessary to insert a dedicated measuring instrument directly into the commercial power system.

  However, such measuring instruments are highly demanded for safety and reliability, and are expensive to manufacture. In addition, installation work for measuring instruments is required, and power outages occur during the work. Furthermore, the installation work requires a qualification more than a second-class electrician and cannot be carried out by ordinary people. Therefore, it takes time and cost, and it has not been possible to introduce equipment for easily detecting the state of power in the home.

  The present invention has been made in view of such a situation, and makes it possible to detect a power state easily and at low cost.

  The detection device according to the first aspect of the present invention includes a first power system from a commercial power source, a second power system from a power generation unit that supplies power of the same frequency as the commercial power source, and a commercial power source and a power generation unit. In the detection device for detecting the power state of the third power system that receives the supply of the first power, the first power system from the connection point of the first power system, the second power system, and the third power system A first current transformer that measures the first current on the side, a second current transformer that measures the second current on the second power system side from the connection point, and the power of the first power system The detection means for detecting the flow direction, the phase difference between the voltage and current of the second power system, and the phase difference between the voltage and current of the third power system are set to predetermined values, and the first current is measured. Value, the measured value of the second current, and the power flow direction of the first power system. Te, and a calculation means for calculating a third current of the third power system.

  In the detection apparatus according to the first aspect of the present invention, a first power system from a commercial power supply, a second power system from a power generation means for supplying power of the same frequency as the commercial power supply, and a commercial power supply and power generation means The first current is measured on the first power system side from the connection point of the third power system that receives the supply of power from the second power system, and the second current is measured on the second power system side from the connection point. The power flow direction of the first power system is detected, the phase difference between the voltage and current of the second power system, and the phase difference between the voltage and current of the third power system are set to predetermined values. The third current of the third power system is calculated based on the measured value of the current, the measured value of the second current, and the power flow direction of the first power system.

  Therefore, it is possible to measure the power state, particularly the load current, easily and at low cost.

  This detection means and calculation means are constituted by, for example, an analog multiplication circuit, an integration circuit, a digital arithmetic circuit, a microcomputer, or various processors.

  When the power flow direction of the first power system is a direction in which power is supplied from the commercial power supply, the calculating means is configured to set the phase difference of the second power system and the phase difference of the third power system. Is used to calculate the third current so that the value obtained by subtracting the measured value of the second current from the third current becomes the measured value of the first current, and the power flow direction of the first power system is the commercial power supply 3 is subtracted from the measured value of the second current using the set value of the phase difference of the second power system and the set value of the phase difference of the third power system. The third current can be calculated so that the measured value becomes the measured value of the first current.

  This makes it possible to accurately measure the load current regardless of whether the power is being purchased or sold.

  The calculation means includes a first power obtained from a measured value of the second current, a third current, a set value of the phase difference of the second power system, and a set value of the phase difference of the third power system. The third current can be calculated based on an equation obtained from the fact that the sum of squares of the active current and reactive current of the system is equal to the square of the measured value of the first current.

  This makes it possible to calculate the load current with a simple equation.

  When the calculation of the third current value is an imaginary number, the calculation means reduces at least one of the setting value of the phase difference of the second power system and the setting value of the phase difference of the third power system. The third current can be recalculated.

  This makes it possible to calculate the load current more reliably.

  This calculating means is based on the measured value of the second current, the calculated value of the third current, the set value of the phase difference of the second power system, and the set value of the phase difference of the third power system, The active current of the first power system can be calculated, and the active power of the first power system can be calculated based on the set value of the voltage of the first power system and the calculated value of the active current.

  Thereby, the electric power sold by the private power generator and the purchased electric power from the commercial power source can be measured easily and at low cost.

  The calculating means calculates the active power of the third power system based on the set value of the voltage of the third power system, the calculated value of the third current, and the set value of the phase difference of the third power system. It can be calculated.

  Thereby, the load power can be measured easily and at low cost.

  The detection means calculates a determination value based on a multiplication value of the measurement value of the first current and the measurement value of the second current, and detects the power flow direction of the first power system based on the determination value. Can be.

  Thereby, it becomes possible to detect the power flow direction on the commercial power source side easily and at low cost.

  The detection method according to the first aspect of the present invention includes a first power system from a commercial power source, a second power system from a power generation unit that supplies power of the same frequency as the commercial power source, and a commercial power source and a power generation unit. The detection device for detecting the power state of the third power system that receives the power of the first power system is connected to the first power system from the connection points of the first power system, the second power system, and the third power system. Measuring the first current with a first current transformer on the side and measuring the second current with a second current transformer on the second power system side from the connection point; and the first power system A detection step for detecting a power flow direction, a phase difference between the voltage and current of the second power system, and a phase difference between the voltage and current of the third power system are set to predetermined values, The measured current value, the measured second current value, and the power of the first power system. Based on the flow direction, and a calculating step of calculating a third current of the third power system.

  In the detection method according to the first aspect of the present invention, a first power system from a commercial power supply, a second power system from a power generation means for supplying power of the same frequency as the commercial power supply, and a commercial power supply and power generation means The first current is measured on the first power system side from the connection point of the third power system that receives the supply of power from the second power system, and the second current is measured on the second power system side from the connection point. The power flow direction of the first power system is detected, the phase difference between the voltage and current of the second power system, and the phase difference between the voltage and current of the third power system are set to predetermined values. The third current of the third power system is calculated based on the measured value of the current, the measured value of the second current, and the power flow direction of the first power system.

  Therefore, it is possible to measure the power state, particularly the load current, easily and at low cost.

  This detection step and calculation step are executed by, for example, an analog multiplication circuit, an integration circuit, a digital arithmetic circuit, a microcomputer, or various processors.

  The detection device according to the second aspect of the present invention includes a detection unit that detects a flow direction of a first power system from a commercial power source, and a second power system from a power generation unit that supplies power having the same frequency as the commercial power source. And the phase difference between the voltage and current of the third power system that receives supply of power from the commercial power source and the power generation means are set to predetermined values, and the first power system, The measured value of the first current measured by the first current transformer on the first power system side from the connection point of the third power system, and on the second power system side from the connection point Calculating means for calculating a third current of the third power system based on a measured value of the second current measured by the second current transformer and a power flow direction of the power of the first power system; Is provided.

  In the detection device according to the second aspect of the present invention, the flow direction of the first power system from the commercial power source is detected, and the voltage of the second power system from the power generation means for supplying power of the same frequency as the commercial power source is detected. And the phase difference between the current and the voltage of the third power system that receives the supply of power from the commercial power source and the power generation means are set to predetermined values, and the first power system and the second power The measured value of the first current measured by the first current transformer on the first power system side from the connection point of the system and the third power system, the second measured value on the second power system side from the connection point The third current of the third power system is calculated based on the measured value of the second current measured by the current transformer and the power flow direction of the first power system.

  Therefore, it is possible to measure the power state, particularly the load current, easily and at low cost.

  This detection means and calculation means are constituted by, for example, an analog multiplication circuit, an integration circuit, a digital arithmetic circuit, a microcomputer, or various processors.

  According to the detection method of the second aspect of the present invention, the detection device for detecting the state of power supplies a detection step for detecting the flow direction of the first power system from the commercial power supply, and supplies power at the same frequency as the commercial power supply. The phase difference between the voltage and current of the second power system from the power generation means to be set, and the phase difference between the voltage and current of the third power system that receives the supply of power from the commercial power source and the power generation means are set to predetermined values. The measured value of the first current measured by the first current transformer on the first power system side from the connection point of the first power system, the second power system, and the third power system, Based on the measured value of the second current measured by the second current transformer on the second power system side from the connection point and the power flow direction of the first power system, And calculating a third current.

  In the detection method according to the second aspect of the present invention, the flow direction of the first power system from the commercial power source is detected, and the voltage of the second power system from the power generation means for supplying power of the same frequency as the commercial power source is detected. And the phase difference between the current and the voltage of the third power system that receives the supply of power from the commercial power source and the power generation means are set to predetermined values, and the first power system and the second power The measured value of the first current measured by the first current transformer on the first power system side from the connection point of the system and the third power system, the second measured value on the second power system side from the connection point The third current of the third power system is calculated based on the measured value of the second current measured by the current transformer and the power flow direction of the first power system.

  Therefore, it is possible to measure the power state, particularly the load current, easily and at low cost.

  This detection step and calculation step are executed by, for example, an analog multiplication circuit, an integration circuit, a digital arithmetic circuit, a microcomputer, or various processors.

  A program according to a second aspect of the present invention includes a detection step for detecting a flow direction of a first power system from a commercial power source, and a second power system from a power generation means for supplying power having the same frequency as that of the commercial power source. The phase difference between the voltage and current, and the voltage and current phase difference of the third power system that receives the supply of power from the commercial power source and the power generation means are set to predetermined values, and the first power system, The measured value of the first current measured by the first current transformer on the first power system side from the connection point of the power system and the third power system, the second measured from the connection point on the second power system side A calculation step for calculating a third current of the third power system based on a measured value of the second current measured by the current transformer of 2 and a power flow direction of the power of the first power system; Causes the computer to execute the processing that includes it.

  In the computer that executes the program according to the second aspect of the present invention, the second power from the power generation means that detects the power flow direction of the first power system from the commercial power supply and supplies the power of the same frequency as the commercial power supply. The phase difference between the voltage and current of the system and the voltage and current phase difference of the third power system that receives power supply from the commercial power source and the power generation means are set to predetermined values, and the first power system, The measured value of the first current measured by the first current transformer on the first power system side from the connection point of the second power system and the third power system, the second power system side from the connection point , The third current of the third power system is calculated based on the measured value of the second current measured by the second current transformer and the power flow direction of the first power system.

  Therefore, it is possible to measure the power state, particularly the load current, easily and at low cost.

  According to the first aspect or the second aspect of the present invention, the state of power can be detected easily and at low cost.

It is a block diagram which shows 1st Embodiment of the electric power monitoring system to which this invention is applied. It is a figure which shows the example of the installation position of a current transformer. It is a flowchart for demonstrating a power monitoring process. It is a graph which shows the example of the phase difference of the voltage and electric current by load. It is a graph which shows the other example of the phase difference of the voltage and electric current by load. It is a figure for demonstrating the calculation method of a judgment value. It is a figure for demonstrating the calculation method of a judgment value. It is a graph which shows the example of the waveform of an electric current when a capacitive load is connected. It is a figure for demonstrating the calculation method of a judgment value. It is a figure for demonstrating the calculation method of purchased electric power, selling electric power, and load electric power. It is a figure for demonstrating the calculation method of purchased electric power, selling electric power, and load electric power. It is a block diagram which shows 2nd Embodiment of the electric power monitoring system to which this invention is applied. It is a flowchart for demonstrating a power monitoring process. It is a graph which shows the calculation conditions of a judgment value. It is a graph which shows the calculation conditions of a judgment value. It is a graph which shows the example of calculation of a judgment value. It is a figure which shows the example of the installation method of the current transformer in the case of a single phase 3 wire system. It is a block diagram which shows the structural example of a computer.

Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described. The description will be given in the following order.
1. First Embodiment 2. FIG. Second Embodiment 3. FIG. Modified example

<1. First Embodiment>
A first embodiment of the present invention will be described with reference to FIGS.

[Configuration example of power monitoring system]
FIG. 1 is a block diagram illustrating a configuration example of a power monitoring system 101 that is a first embodiment of a power monitoring system to which the present invention is applied. FIG. 2 is a diagram illustrating current transformers 111p and 111c of the power monitoring system 101. The example of the installation position of is shown.

  In the following, the left side of the dotted line in FIG. 2 is the home of the home where the power monitoring system 101 and the solar power generation system 151 are provided. Hereinafter, the power system from the solar power generation system 151 to the connection point C is referred to as a generated power system, the power system from the commercial power supply 152 to the connection point C is referred to as a commercial power system, and the connection from the connection point C to the load 153 The power system is referred to as a load power system. Hereinafter, it is assumed that each power system is configured by a single-phase two-wire system in the house.

  Further, hereinafter, the voltage of the generated power system (= the output voltage of the photovoltaic power generation system 151) (hereinafter referred to as the generated voltage) and the current (hereinafter referred to as the generated current) are represented by vp and ip, respectively, and the arrow Ap1 The direction is the positive direction. Further, hereinafter, the effective value of the generated voltage vp (hereinafter referred to as the generated voltage effective value) and the effective value of the generated current ip (hereinafter referred to as the generated current effective value) are represented by Vp and Ip, respectively. Further, hereinafter, the phase of the generated voltage vp is represented by φpv, the phase of the generated current ip is represented by φpi, and the phase difference between the generated voltage vp and the generated current ip is represented by Δφp. Hereinafter, the power of the generated power system (hereinafter referred to as generated power) and the power factor (hereinafter referred to as power generation rate) are represented by Pp and PFp (= cos Δφp), respectively.

  Further, hereinafter, the voltage of the commercial power system (= the output voltage of the commercial power supply 152) (hereinafter referred to as the commercial voltage) and the current (hereinafter referred to as the commercial current) are represented by vc and ic, respectively, and the direction of the arrow Ac1 is indicated. The direction is positive. Hereinafter, the effective value of the commercial voltage vc (hereinafter referred to as a commercial voltage effective value) and the effective value of the commercial current ic (hereinafter referred to as a commercial current effective value) are represented by Vc and Ic, respectively. Further, hereinafter, the phase of the commercial voltage vc is represented by φcv, the phase of the commercial current ic is represented by φci, and the phase difference between the commercial voltage vc and the commercial current ic is represented by Δφc. Further, hereinafter, the power (hereinafter referred to as “commercial power”) and the power factor (hereinafter referred to as “commercial power factor”) of the commercial power system are represented by Pc and PFc (= cos Δφc), respectively.

  Furthermore, hereinafter, the voltage (hereinafter referred to as load voltage) and current (hereinafter referred to as load current) of the load power system are represented by vd and id, respectively, and the direction of the arrow Ad is defined as a positive direction. Also, hereinafter, the effective value of the load voltage vd (hereinafter referred to as the load voltage effective value) and the effective value of the load current id (hereinafter referred to as the load current effective value) are represented by Vd and Id, respectively. Further, hereinafter, the phase of the load voltage vd is represented by φdv, the phase of the load current id is represented by φdi, and the phase difference between the load voltage vd and the load current id is represented by Δφd. Hereinafter, the power of the load power system (hereinafter referred to as load power) and the power factor (hereinafter referred to as load power factor) are respectively represented by Pd and PFd (= cos Δφd).

  The generated power system, the commercial power system, and the load power system are connected to each other through the connection point C and have the same potential. Therefore, power generation voltage vp = commercial voltage vc = load voltage vd, power generation voltage effective value Vp = commercial voltage effective value Vc = load voltage effective value Vd, and phase φpv = phase φcv = phase φdv. The connection point C corresponds to, for example, a domestic distribution board.

  The power monitoring system 101 is a system that detects and monitors the state of power in the house. As will be described later, the power monitoring system 101 detects the flow direction of the commercial power Pc (hereinafter referred to as the commercial power flow direction) based on the generated current ip and the commercial current ic, and indicates whether the power is being purchased or sold. It is determined which one. In addition, the power monitoring system 101 measures the generated power Pp of the solar power generation system 151 and the surplus power of the solar power generation system 151 and the sales power Pcs supplied from the solar power generation system 151 to the commercial power system. To do. Further, the power monitoring system 101 includes purchased power Pcb supplied from the commercial power supply 152 to the commercial power grid, and load power supplied from the photovoltaic power generation system 151 and the commercial power supply 152 to the load power system and consumed by the load 153. Pd is measured.

  The photovoltaic power generation system 151 is configured to include a solar cell module 161 and a PV (Photo Voltatic) controller 162.

  The solar cell module 161 generates DC power by solar power generation and supplies the generated DC power to the PV controller 162.

  The PV controller 162 converts the DC power from the solar cell module 161 into AC power having substantially the same voltage and frequency as the commercial power supply 152, and synchronizes the phase of the converted AC power voltage with the voltage phase of the commercial power supply 152. Let Then, the PV controller 162 outputs the AC power (generated power Pp).

  The load 153 includes various electric devices such as electric appliances such as a refrigerator.

  Here, the configuration of the power monitoring system 101 will be described in more detail.

  The power monitoring system 101 is configured to include a current transformer 111p, a current transformer 111c, and a detection device 112. In addition, the detection device 112 is configured to include a measurement unit 121p, a measurement unit 121c, a calculation unit 122, a display unit 123, and a communication unit 124.

  The current transformer 111p is installed in the wiring between the photovoltaic power generation system 151 and the connection point C, and measures the generated current ip. More precisely, the current transformer 111p converts the generated current ip (primary current) into a current isp (secondary current) and supplies it to the measuring unit 121p. Hereinafter, it is assumed that the current transformer 111p is installed in the direction in which the current isp flows in the direction of the arrow Ap2 when the generated current ip flows in the direction of the arrow Ap1.

  The measuring unit 121p converts the current isp into the voltage vsp by the built-in resistor Rp. The voltage vsp has a positive value when the generated current ip flows in the direction of the arrow Ap1, and the current isp flows in the direction of the arrow Ap2, the generated current ip flows in the opposite direction to the arrow Ap1, and the current isp changes with the arrow Ap2. Negative value when flowing in the opposite direction. That is, the phase of the generated current ip when the direction of the arrow Ap1 is positive matches the phase of the voltage vsp.

  In addition, the measurement unit 121p supplies a signal indicating the voltage vsp (hereinafter referred to as a signal vsp) to the calculation unit 122.

  The current transformer 111c is installed in the home wiring between the commercial power source 152 and the connection point C, and measures the commercial current ic. More precisely, the current transformer 111c converts the commercial current ic (primary current) into a current isc (secondary current) and supplies it to the measuring unit 121c. Hereinafter, it is assumed that the current transformer 111c is installed in the direction in which the current isc flows in the direction of the arrow Ac2 when the commercial current ic flows in the direction of the arrow Ac1.

  The measuring unit 121c converts the current isc into the voltage vsc by the built-in resistor Rc. The voltage vsc takes a positive value when the commercial current ic flows in the direction of the arrow Ac1, the current isc flows in the direction of the arrow Ac2, the commercial current ic flows in the direction opposite to the arrow Ac1, and the current isc Negative value when flowing in the opposite direction. That is, the phase of the commercial current ic when the direction of the arrow Ac1 is positive matches the phase of the voltage vsc.

  When the commercial power Pc is supplied in the direction of the arrow Ac1, the difference (= phase difference Δφc) between the phase of the commercial voltage vc and the phase of the voltage vsc (= phase of the commercial current ic) is the load Even if the power factor of 153 and the phase synchronization error of the PV controller 162 are taken into consideration, the power factor is within ± π / 2. Conversely, when the commercial power Pc is in the power selling state supplied in the opposite direction to the arrow Ac1, the difference (= phase difference Δφc) between the phase of the commercial voltage vc and the phase of the voltage vsc (= phase of the commercial current ic) is , -Π to -π / 2, or π / 2 to π. As will be described later, it has been empirically found that the power factor of a general household load is cos (π / 6) or more.

  In addition, the measurement unit 121c supplies a signal indicating the voltage vsc (hereinafter referred to as a signal vsc) to the calculation unit 122.

  The calculation unit 122 is configured by, for example, a microcomputer and includes a conversion unit 131, a determination value calculation unit 132, a tidal direction detection unit 133, and a power calculation unit 134.

  The converter 131 converts the value of the voltage vsp indicated by the signal vsp into the value of the generated current ip based on the known current transformer ratio of the current transformer 111p and the resistance value of the resistor Rp, and the converted value is a determination value. The calculation unit 132 and the power calculation unit 134 are notified. Further, the converter 131 converts the value of the voltage vsc indicated by the signal vsc into the value of the commercial current ic based on the known current transformer ratio of the current transformer 111c and the resistance value of the resistor Rc, and converts the converted value to The determination value calculation unit 132 and the power calculation unit 134 are notified.

  As will be described later, the determination value calculation unit 132 calculates a determination value used for detection of the commercial power flow direction based on the measurement value of the generated current ip and the measurement value of the commercial current ic. The determination value calculation unit 132 notifies the tidal direction detection unit 133 of the calculated determination value.

  As will be described later, the power flow direction detection unit 133 detects the commercial power flow direction based on the determination value calculated by the determination value calculation unit 132 and notifies the power calculation unit 134 of the detected result.

  As will be described later, the power calculation unit 134 generates the generated power Pp, the sales power Pcs, the purchased power Pcb, based on the measured value of the generated current ip, the measured value of the commercial current ic, and the detection result of the commercial power flow direction. And load electric power Pd is calculated. The power calculation unit 134 notifies the display unit 123 and the communication unit 124 of the calculated result.

  The display unit 123 includes, for example, a display device such as an LCD (Liquid Crystal Display), a light emitting device such as an LED (Light Emitting Diode), and the like, and displays the power state of each unit.

  The communication unit 124 includes various communication devices, and transmits power state information indicating the power state of each unit to an external device. Note that an arbitrary method can be adopted as a communication method of the communication unit 124 regardless of wired or wireless.

[Power monitoring processing]
Next, the power monitoring process executed by the power monitoring system 101 will be described with reference to the flowchart of FIG. This process starts when the power monitoring system 101 is turned on, and ends when the power is turned off, for example.

  In step S1, the power monitoring system 101 measures current. Specifically, the current transformer 111p converts the generated current ip into a current isp and supplies it to the measuring unit 121p. The measurement unit 121p converts the current isp into the voltage vsp and supplies the signal vsp indicating the voltage vsp to the conversion unit 131. Moreover, the current transformer 111c converts the commercial current ic into the current isc and supplies it to the measuring unit 121c. The measurement unit 121c converts the current isc into the voltage vsc and supplies the signal vsc indicating the voltage vsc to the conversion unit 131.

  The conversion unit 131 converts the value of the voltage vsp indicated by the signal vsp into the value of the generated current ip, and notifies the determination value calculation unit 132 and the power calculation unit 134 of the converted value. In addition, the converter 131 converts the value of the voltage vsc indicated by the signal vsc into the value of the commercial current ic, and notifies the determination value calculator 132 and the power calculator 134 of the converted value.

  In step S <b> 2, the determination value calculation unit 132 calculates a determination value and notifies the tidal direction detection unit 133 of the calculated determination value.

  In step S <b> 3, the power flow direction detection unit 133 detects the power flow direction on the commercial side based on the determination value, and notifies the power calculation unit 134 of the detected power flow direction.

  Here, with reference to FIG. 4 thru | or FIG. 9, the specific example of the calculation method of the determination value in the process of step S2 and S3 and the detection method of a commercial power flow direction is demonstrated.

  For example, when the measurement of the generated current ip and the commercial current ic is continuously performed by an analog circuit or the like, for example, the determination value D1 obtained by the following equation (1) is used.

  The time T indicates the time of one cycle of the power of the commercial power source 152 (= 1 / frequency of the commercial power source 152).

  The determination value D1 is a value obtained by integrating the product of the instantaneous value of the generated current ip and the instantaneous value of the commercial current ic at approximately the same time for one period. Therefore, when the phase difference φpi−φci between the generated current ip and the commercial current ic satisfies | φpi−φci | ≦ π / 2, the determination value D1 ≧ 0, and satisfies π / 2 <| φpi−φci | ≦ π. In this case, the determination value D1 <0.

  As described above, it has been empirically known that the power factor of a general household load is cos (π / 6) or more. Therefore, the phase difference between the voltage waveform and the current waveform is π / 6 or less.

  For example, FIG. 4 is a graph showing a result of applying an AC voltage of 100 V to a fluorescent lamp and measuring a current with a current transformer. In FIG. 4, the horizontal axis indicates time, and the vertical axis indicates voltage and current. A waveform 201 indicates a voltage waveform, a waveform 202 indicates a current waveform when a current transformer is attached in a direction in which the current value is positive when the voltage and current are in phase, and a waveform 203 indicates the voltage and current The waveform of the current when the current transformer is attached in the direction in which the current value becomes positive when the current is in reverse phase is shown. In this case, the phase difference between the voltage applied to the fluorescent lamp and the current flowing through the fluorescent lamp is about 11.5 degrees (<π / 6).

  FIG. 5 is a graph showing the results of measuring the current with a current transformer attached in a direction in which the current value becomes positive when an AC voltage of 100 V is applied to another load and the voltage and current are in phase. is there. In FIG. 5, the horizontal axis indicates time, and the vertical axis indicates voltage and current. A waveform 211 indicates a voltage waveform, a waveform 212 indicates a current waveform when the load is a microwave oven, and a waveform 213 indicates a current waveform when the load is a personal computer and a display. Also in this example, the phase difference between the voltage and the current is smaller than π / 6.

  Accordingly, it can be assumed that the phase difference between the generated voltage vp and the generated current ip is within ± π / 6. Further, it can be assumed that the phase difference between the commercial voltage vc and the commercial current ic is within ± π / 6 in the power purchase state and within the range of π ± π / 6 in the power sale state. Accordingly, in the power purchase state, it can be assumed that | φpi−φci | ≦ π / 3 and that the determination value D1 ≧ 0. On the other hand, in the case of the power sale state, it can be assumed that 2π / 3 ≦ | φpi−φci | ≦ π and that the determination value D1 <0.

  Therefore, the commercial power flow direction can be detected based on the determination value D1. That is, when determination value D1 ≧ 0, it is determined that the commercial power Pc is in a power purchase state supplied in the direction of arrow Ac1, and when determination value D1 <0, commercial power Pc is supplied in the direction of arrow Ac1. It can be determined that the power is being sold.

  Further, for example, when the measurement of the generated current ip and the commercial current ic is performed discretely by a digital arithmetic circuit or the like as shown in FIG. 6, the determination value D2 obtained by the following equation (2) is used. .

  FIG. 6 shows an example of waveforms of the generated current ip and the commercial current ic in the power sale state, the horizontal axis shows time, and the vertical axis shows the current value. Moreover, the circle mark and square mark of FIG. 6 have shown the sampling point. In order to make the figure easy to understand, only a part of the sampling points is shown in FIG.

  Further, k in Expression (2) indicates the number of sampling points of the generated current ip and the commercial current ic, and m indicates the number of samplings per cycle. Further, ip [k] indicates the sampling value of the generated current ip at the kth sampling point, and ic [k] indicates the sampling value of the commercial current ic at the kth sampling point.

  The determination value D2 is a value obtained by integrating a multiplication value of the sampling value of the generated current ip and the commercial current ic at substantially the same time for one cycle. Therefore, similarly to the determination value D1, the determination value D2 ≧ 0 when | φpi−φci | ≦ π / 2, and the determination value D2 <0 when π / 2 <| φpi−φci | ≦ π.

  Therefore, as in the case of using the determination value D1, it can be determined that the power purchase state is obtained when the determination value D2 ≧ 0, and the power sale state can be determined when the determination value D2 <0.

  For example, as shown in FIG. 7, when the value of the generated current ip at time tmax when the generated current ip reaches a positive peak is ip (tmax) and the value of the commercial current ic is ic (tmax), The determination value D3 obtained by Expression (3) may be used.

  D3 = ip (tmax) × ic (tmax) (3)

  In this case, as in the case of using the determination value D1, it can be determined that the power purchase state is obtained when the determination value D3 ≧ 0, and the power sale state can be determined when the determination value D3 <0. .

  Similarly, using the value ip (tmin) of the generated current ip at the time tmin when the generated current ip reaches a negative peak and the value ic (tmin) of the commercial current ic, a determination value D4 obtained by the following equation (4) is obtained. You may make it use.

  D4 = ip (tmin) × ic (tmin) (4)

  Also in this case, as in the case of using the determination value D3, when the determination value D4 ≧ 0, it is determined that the power is being purchased, and when the determination value D4 <0, it is determined that the power is being sold. .

  FIG. 8 shows an example of waveforms of the generated current ip and the commercial current ic in the power sale state when the load 153 is mainly a capacitive load (capacitor load). The horizontal axis indicates time, and the vertical axis indicates current.

  As shown in this figure, when the load 153 is mainly a capacitive load, the generated current ip has a pulse-like waveform in which a short peak appears for a short time. In this case, the integrated value of the generated current ip and the commercial current ic at the time when the generated current ip peaks is larger than the determination value D1 or the determination value D2 obtained by integrating the multiplied value of the generated current ip and the commercial current ic for one period. There are cases where the detection accuracy of the commercial power flow direction becomes higher when a certain determination value D3 or determination value D4 is used.

  In addition, when the generated current ip and the commercial current ic cannot be measured simultaneously because the sampling interval is short, for example, the determination value is calculated using the generated current ip and the commercial current ic measured in different periods. Also good.

  For example, when measurement of the generated current ip and the commercial current ic is continuously performed, the determination value D5 obtained by the following equation (5) is used.

  Note that n in Equation (5) is a natural number.

  The determination value D5 is a value obtained by integrating the product of the instantaneous value of the generated current ip and the instantaneous value of the commercial current ic delayed by n cycles for one cycle. Therefore, similarly to the case where the determination value D1 is used, when the determination value D5 ≧ 0, it can be determined that the power is being purchased, and when the determination value D5 <0, it can be determined that the power is being sold.

  For example, when the measurement of the generated current ip and the commercial current ic is performed discretely, the determination value D6 obtained by the following equation (6) is used.

  As shown in FIG. 9, the determination value D <b> 6 is a value obtained by integrating a multiplication value of the sampling value of the generated current ip and the sampling value of the commercial current ic delayed by n cycles for one cycle. Therefore, similarly to the case where the determination value D1 is used, when the determination value D6 ≧ 0, it can be determined that the power is being purchased, and when the determination value D6 <0, it can be determined that the power is being sold.

  Returning to FIG. 3, in step S <b> 4, the power calculation unit 134 calculates the power of each unit, that is, the generated power Pp, the purchased power Pcb, the sold power Pcs, and the load power Pd.

  Here, an example of a method for calculating the power of each unit will be described.

  In the power purchase state, the generated power Pp, the purchased power Pcb, the sold power Pcs, and the load power Pd are expressed by the following equations (7) to (10).

Pp = Vp × Ip × PFp (7)
Pcb = Vc × Ic × PFc (8)
Pcs = 0 (9)
Pd = Vd × Id × PFd (10)

  On the other hand, in the power sale state, the calculation formulas for the purchased power Pcb and the sold power Pcs are reversed, and the following formulas (11) and (12) are obtained.

Pcb = 0 (11)
Pcs = Vc × Ic × PFc (12)

  Here, the generated current effective value Ip and the commercial current effective value Ic can be calculated based on the measured value of the generated current ip and the measured value of the commercial current ic, respectively.

  Further, the output voltage of the photovoltaic power generation system 151 is controlled so as to be within a predetermined fluctuation range. Therefore, even if the generated voltage effective value Vp is a constant, the error is predicted to be small. Therefore, the generated voltage effective value Vp can be set to a predetermined constant based on the nominal value of the output voltage of the photovoltaic power generation system 151, for example.

  Furthermore, since the commercial voltage effective value Vc and the load voltage effective value Vd are equal to the generated voltage effective value Vp, they can be set to constants having the same value as the generated voltage effective value Vp.

  In addition, the power factor of the photovoltaic power generation system 151 is within a predetermined fluctuation range (for example, 12.5% to 100% of the rated load) in order to receive certification such as JET (Japan Electrical Safety & Environment Technology Laboratories). Within a range of 95% or more). Therefore, even if the power generation rate PFp and the phase difference Δφp are constants, the error is predicted to be small. Therefore, the power generation rate PFp and the phase difference Δφp can be set to predetermined constants based on, for example, experimental results, actual measurement results, theoretical equations, or the like.

  Furthermore, it has been empirically found that the power factor of a general household load is also a predetermined value or more as described above. Accordingly, the load power factor PFd and the phase difference Δφd are also expected to have a small error even if they are constants, similarly to the power generation rate PFp and the phase difference Δφp. Therefore, the load power factor PFd and the phase difference Δφd can be set to predetermined constants based on, for example, experimental results, actual measurement results, theoretical equations, or the like.

  On the other hand, the commercial power factor PFc varies greatly and cannot be a constant. Also, the load current effective value Id is unknown because the load current id is not measured.

  As described above, all the values on the right side of the above-described equation (7) are known, and the generated power Pp can be calculated.

  On the other hand, the commercial power factor PFc is unknown on the right side of the equations (8) and (12), and the effective load current value Id is unknown on the right side of the equation (10).

  Here, instead of the commercial power factor PFc, an effective value Irc (hereinafter referred to as a commercial effective current effective value Irc) of an effective current of the commercial power system is used to calculate purchased power according to the following equations (13) and (14). It is also possible to obtain Pcb or sales power Pcs.

Pcb = Vc × Irc (13)
Pcs = Vc × Irc (14)

  Therefore, if the commercial effective current effective value Irc is known, the purchased power Pcb or the sales power Pcs can be obtained, and if the load current effective value Id is known, the load power Pd can be obtained.

  Here, a method for calculating the commercial effective current effective value Irc and the load current effective value Id will be described with reference to FIG.

  Hereinafter, the effective value of the reactive current of the commercial power system is referred to as a commercial reactive current effective value Imc. Hereinafter, the apparent power of the generated power system is referred to as apparent generated power Pap, the apparent power of the commercial power system is referred to as apparent commercial power Pac, and the apparent power of the load power system is referred to as apparent load power Pad.

  FIG. 10 is a diagram illustrating a relationship among the generated current effective value Ip, the commercial current effective value Ic, and the load current effective value Id. In addition, the horizontal axis of FIG. 10 shows the effective current, and the vertical axis shows the reactive current.

  Further, the vector Ip, the vector Ic, and the vector Id are vectors representing the generated current effective value Ip, the commercial current effective value Ic, and the load current effective value Id, respectively. Since the load current effective value Id and the phase difference Δφc of the commercial power system are known, the magnitude and inclination of the vector Ip, the magnitude of the vector Ic, and the inclination of the vector Id are fixed.

  The dotted circle in FIG. 10 is a locus drawn by the end point or start point of the vector Ic by changing the phase difference Δφc of the commercial power system when the origin of the coordinate system in the figure is the start point or end point of the vector Ic. Is shown.

  In the power purchase state, the apparent load power Pad = apparent generated power Pap + apparent commercial power Pac. Here, since the values and phases of the generated voltage vp, the commercial voltage vc, and the load voltage vd are equal, the relationship among the vectors representing the generated current effective value Ip, the commercial current effective value Ic, and the load current effective value Id is: As indicated by the dotted line in FIG. 10, vector Id = vector Ip + vector Ic.

  On the other hand, in the power sale state, the apparent generated power Pap = apparent commercial power Pac + apparent load power Pad, so the relationship between the generated current effective value Ip, the commercial current effective value Ic, and the vector representing the load current effective value Id is As indicated by the solid line in FIG. 10, vector Ip = vector Ic + vector Id.

  Therefore, the commercial reactive current effective value Imc and the commercial active current effective value Irc are calculated using the generated current effective value Ip, the load current effective value Id, the phase difference Δφp of the generated power system, and the phase difference Δφd of the load power system, It is represented by the following formulas (15) and (16).

Imc = Id · sin Δφd + Ip · sin Δφp (15)
Irc = Id · cos Δφd−Ip · cos Δφp (16)

  Further, since the square sum of the commercial reactive current effective value Imc and the commercial active current effective value Irc is equal to the square of the commercial current effective value Ic, the following equation (17) is established.

Ic ² = Imc ² + Irc ² (17)

  Then, Expression (18), which is a quadratic equation regarding the load current effective value Id, is derived from Expressions (15) to (17).

Id ² −2Ip · cos (Δφd + Δφp) × Id + (Ip ² −Ic ² ) = 0
... (18)

Here, assuming that b = −Ip · cos (Δφd + Δφp) and c = (Ip ² −Ic ² ), the effective load current value Id is obtained from the equation (18) as the following equation (19).

  In the power purchase state, by solving the equation (18), in FIG. 10, while fixing the phase difference Δφp of the generated power system and the phase difference Δφd of the load power system and varying the phase difference Δφc of the commercial power system, Vector Ic = vector Id−vector Id magnitude (= load current effective value Id) is obtained. That is, the value obtained by subtracting the measured value of the generated current effective value Ip from the load current effective value Id using the set value of the phase difference Δφp of the generated power system and the set value of the phase difference Δφd of the load power system is the commercial current effective value. The load current effective value Id is calculated so as to be a measured value of Ic.

  On the other hand, in the power selling state, by solving the equation (18), the phase difference Δφp of the generated power system and the phase difference Δφd of the load power system are fixed and the phase difference Δφc of the commercial power system is varied in FIG. Accordingly, the magnitude of the vector Id (= the load current effective value Id), where the vector Ic = vector Ip−vector Id, is obtained. That is, the value obtained by subtracting the load current effective value Id from the measured value of the generated current effective value Ip using the set value of the phase difference Δφp of the generated power system and the set value of the phase difference Δφd of the load power system is the commercial current effective value. The load current effective value Id is calculated so as to be a measured value of Ic.

  As described above, the load current effective value Id is obtained based on the generated current effective value Ip, the commercial current effective value Ic, the generated power system phase difference Δφp, the commercial power system phase difference Δφc, and the commercial power flow direction. Can do. The generated current effective value Ip and the commercial current effective value Ic are measured values obtained from the measured value of the generated current ip and the measured value of the commercial current ic, respectively, and the phase difference Δφp of the generated power system and the phase difference of the commercial power system Δφc is a set value (constant).

  Then, using the calculated load current effective value Id, the load power Pd is calculated by the above-described equation (10).

  Further, the calculated load current effective value Id, together with the measured value of the generated current effective value Ip, the set value of the phase difference Δφp of the generated power system, and the set value of the phase difference Δφd of the load power system, ), The commercial effective current effective value Irc is calculated.

  Then, using the calculated commercial effective current effective value Irc, in the power purchase state, the purchased power Pcb is calculated by the equation (13), and in the power sale state, the sold power Pcs is calculated by the equation (14). Is done.

  Then, the power calculation unit 134 notifies the display unit 123 and the communication unit 124 of the calculated power value of each unit.

  Note that the solution of the equation (18) may be an imaginary solution. This may occur when at least one of the phase difference Δφp of the generated power system and the phase difference Δφd of the load power system is smaller than the set value.

  Specifically, the maximum value of the generated current effective value Ip that can be plotted under the conditions of FIG. 10 is when the vector Ip touches the dotted circle, as shown in FIG.

  Therefore, as shown by the dotted line in FIG. 11, when the actual phase difference Δφp ′ of the generated power system is smaller than the set value Δφp, the actual generated current effective value Ip ′ may exceed the range that can be plotted. . When the actual generated current effective value Ip ′ exceeds the range that can be drawn, the solution of the equation (18) is an imaginary solution.

  In order to solve this, in FIG. 11, at least one of the set value of the phase difference Δφp of the generated power system and the set value of the phase difference Δφd of the load power system so that the actual generated current effective value Ip ′ can be plotted. One can be made smaller.

  For example, when the phase difference Δφp = 11.5 degrees (power generation rate PFp = 98%) and the phase difference Δφd = 20.0 degrees (load power factor PFd = 94%), the phase difference Δφp = 0 degrees. (Power generation rate PFp = 100%), phase difference Δφd = 8.1 degrees (load power factor PFd = 99%), and the solution of equation (18) may be recalculated.

  Note that it is expected that the frequency of occurrence of a state where the equation (18) is an imaginary solution is small. Therefore, for example, it is considered that an error generated in order to avoid an imaginary solution has a small influence on the integrated value of power of each unit in a predetermined time unit (for example, one day unit).

  Returning to FIG. 3, in step S5, the display unit 123 displays the power state of each unit. For example, the display unit 123 displays the calculated generated power Pp, sold power Pcs, purchased power Pcb, and load power Pd using numerical values or a time-series graph. In addition, for example, the display unit 123 displays on the screen whether characters are in a power purchase state or a power sale state with characters, symbols, icons, etc., or lights, blinks, changes in color, etc. by LEDs. It is indicated by.

  Thereby, the user can grasp | ascertain the state of the electric power of each part in a household.

  In step S6, the communication unit 124 notifies the power state of each unit. Specifically, the communication unit 124 includes the calculated generated power Pp, the sold power Pcs, the purchased power Pcb, the load power Pd, and the power including the power purchase state or the power sale state. Send status information to an external device.

  For example, an external device that is a transmission destination accumulates received information or analyzes a power usage state based on the received information.

  Further, the measurement values of the generated current ip and the commercial current ic may be included in the power state information. Further, it is not always necessary to transmit all the information described above. For example, the information to be transmitted may be selected according to the necessity of the transmission destination device.

  Further, the transmission of the power state information is not necessarily performed every time in the loop process of the power monitoring process, and is performed at a predetermined timing, for example, every predetermined period or when the amount of information stored exceeds a predetermined amount. What should I do? Alternatively, the power status information may be transmitted in response to a request from an external device.

  Thereafter, the process returns to step S1, and the processes after step S1 are executed.

  As described above, without installing a voltage measuring device in the power system, only the current transformers 111p and 111c are installed in the power system, and only the generated current ip and the commercial current ic are measured. Can be detected. Further, the generated power Pp, the sold power Pcs, the purchased power Pcb, and the load power Pd can be measured almost accurately regardless of fluctuations in the commercial power factor PFc (phase difference Δφc).

  Therefore, the power monitoring system 101 can be installed safely and uninterrupted, making it easy to install the power monitoring system 101 and reducing the necessary cost. As a result, it is possible to detect the power state easily and at low cost. Furthermore, the safety and reliability of the entire power monitoring system 101 can be improved by omitting a voltage measuring device that requires high safety and reliability.

<2. Second Embodiment>
Next, a second embodiment of the present invention will be described with reference to FIGS.

  In the second embodiment, compared with the first embodiment, the phase difference between the generated current ip and the commercial current ic is detected, and the commercial power flow direction is detected based on the phase difference. Or calculating the power of each part.

[Configuration example of power monitoring system]
FIG. 12 is a block diagram showing a configuration example of a power monitoring system 301 that is the second embodiment of the power monitoring system to which the present invention is applied. In the figure, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and description of parts having the same processing will be omitted because it will be repeated.

  The power monitoring system 301 is different from the power monitoring system 101 in that a detection device 311 is provided instead of the detection device 112. The detection device 311 is different from the detection device 112 in that a calculation unit 321 is provided instead of the calculation unit 122. Further, the calculation unit 321 is different from the calculation unit 122 in that a determination value calculation unit 331, a commercial power state detection unit 332, instead of the determination value calculation unit 132, the tidal direction detection unit 133, and the power calculation unit 134, And the point from which the electric power calculation part 333 is provided differs.

  The determination value calculation unit 331 acquires the measurement value of the generated current ip and the measurement value of the commercial current ic from the conversion unit 131. As will be described later, the determination value calculation unit 331 calculates a determination value used for detecting the phase difference between the generated current ip and the commercial current ic based on the measured value of the generated current ip and the measured value of the commercial current ic. The determination value calculation unit 331 supplies the calculated determination value to the commercial power state detection unit 332.

  As will be described later, the commercial power state detection unit 332 determines the phase difference between the generated current ip and the commercial current ic, the phase difference Δφc of the commercial power system, the commercial power factor based on the determination value calculated by the determination value calculation unit 331. PFc and commercial power flow direction are detected. The commercial power state detection unit 332 notifies the power calculation unit 333 of the detection result.

  The power calculation unit 333 acquires the measurement value of the generated current ip and the measurement value of the commercial current ic from the conversion unit 131. As will be described later, the power calculation unit 333 generates the generated power Pp, based on the measurement value of the generated current ip, the measurement value of the commercial current ic, the detection result of the commercial power factor PFc, and the detection result of the commercial power flow direction. Sales electric power Pcs, purchased electric power Pcb, and load electric power Pd are calculated. The power calculation unit 333 notifies the display unit 123 and the communication unit 124 of the calculated result.

[Second Embodiment of Power Monitoring Process]
Next, the power monitoring process executed by the power monitoring system 301 will be described with reference to the flowchart of FIG.

  In step S101, the generated current ip and the commercial current ic are measured as in the process of step S1 of FIG.

  In step S <b> 102, the determination value calculation unit 331 calculates a determination value and notifies the commercial power state detection unit 332 of the calculated determination value.

  In step S <b> 103, the commercial power state detection unit 332 detects a commercial power state based on the determination value, and notifies the power calculation unit 333 of the detected state.

  Here, a specific example of a determination value calculation method and a commercial power state detection method in the processes of steps S102 and S103 will be described.

  For example, when the measurement of the generated current ip and the commercial current ic is continuously performed by an analog circuit or the like, the determination value calculation unit 331 sets the angle θ in Expression (20) to a predetermined value within the range of 0 ≦ θ <2π. The determination value D7 (θ) at each angle θ is calculated while shifting at intervals.

  The determination value D7 (θ) is equal to the value calculated by shifting the phase φci of the measurement value of the commercial current ic by the angle θ from the determination value D1 of the above-described equation (1). Then, by calculating the determination value D7 (θ) while shifting the angle θ, the determination value D7 (θ) in each phase is calculated while moving the phase φci of the measurement value of the commercial current ic.

  Therefore, when the angle θ matches the phase difference φpi−φci between the generated current ip and the commercial current ic, it is estimated that the determination value D7 (θ) is maximized.

  Therefore, the commercial power state detection unit 332 generates the angle θ at which the determination value D7 (θ) is maximum (= the amount of movement of the phase φci of the measured value of the generated current ip at which the determination value D7 (θ) is maximum) The phase difference between the current ip and the commercial current ic is detected as φpi−φci.

  When the generated current ip and the commercial current ic cannot be measured at the same time because the sampling interval is short, for example, the determination value D8 (θ) of the following equation (21) is used instead of the determination value D7 (θ). Thus, the phase difference φpi−φci between the generated current ip and the commercial current ic may be obtained.

  The determination value D8 (θ) is equal to the value calculated by shifting the phase φci of the measured value of the commercial current ic by the angle θ from the determination value D5 of the above-described equation (5).

  For example, when the measurement of the generated current ip and the commercial current ic is performed discretely by a digital arithmetic circuit or the like, the determination value calculation unit 331 sets the variable j in Expression (22) to a range of 0 ≦ j ≦ m. The determination value D9 (j) is calculated while incrementing one by one.

  The determination value D9 (j) is equal to a value calculated by shifting the phase φci of the sampling value of the commercial current ic by the angle θ = 2πj / m from the determination value D2 of the above equation (2). Then, by calculating the determination value D9 (j) while incrementing the variable j by one, the determination value D9 (j) at each phase is calculated while moving the phase φci of the sampling value of the commercial current ic. .

  Therefore, when the angle θ = 2πj / m coincides with the phase difference φpi−φci between the generated current ip and the commercial current ic, it is estimated that the determination value D9 (j) is maximized.

  Therefore, the commercial power state detection unit 332 detects the angle θ (= 2πj / m) corresponding to the variable j having the maximum determination value D9 (j) as the phase difference φpi−φci between the generated current ip and the commercial current ic. To do.

  FIG. 16 shows an example of the result of calculating the determination value D9 (j) of Expression (22) under the conditions shown in FIGS. In FIG. 14 and FIG. 16, the unit of the angle is shown in degrees instead of radians.

  FIG. 14 shows an example of the relationship between the generated power system, the commercial power system, and the apparent power of the load power system. The horizontal axis in FIG. 14 represents reactive power, and the vertical axis represents active power.

  FIG. 15 shows an example of a time-series transition of the generated current ip, the commercial current ic, the load current id, and the generated voltage vp (= commercial voltage vc = load voltage vd). In FIG. 15, the horizontal axis indicates time, and the vertical axis indicates voltage or current. Each waveform of the generated current ip, the commercial current ic, the load current id, and the generated voltage vp is substantially a sine wave.

  14 and 15, the phase φpi of the generated current ip advances 8 degrees with respect to the phase φpv of the generated voltage vp, the power generation rate PFp becomes 99%, and the commercial current ic with respect to the phase φcv of the commercial voltage vc In this example, the phase φci is delayed by 40 degrees and the commercial power factor PFc is 77%.

  Therefore, as shown in FIG. 14, the angle between the vector representing the apparent power of the generated power system and the vector representing the apparent power of the commercial power system is 48 degrees. Further, since the phase of the generated voltage vp and the commercial voltage vc are equal, the phase difference between the generated current ip and the commercial current ic is 48 degrees.

  Then, as shown in FIG. 16, when the angle θ (= 2πj / m) is 48 degrees, D9 (j) becomes the maximum.

  Thus, the phase difference φpi−φci between the generated current ip and the commercial current ic can be accurately detected using the determination value D9 (j).

  When the generated current ip and the commercial current ic cannot be measured at the same time because the sampling interval is short, for example, the determination value D10 (j) of the following equation (23) is used instead of the determination value D9 (j). Thus, the phase difference φpi−φci between the generated current ip and the commercial current ic may be obtained.

  Determination value D10 (j) is equal to the value calculated by shifting phase φci of the sampling value of commercial current ic by angle θ = 2πj / m from determination value D6 of equation (6) described above.

  Further, the commercial power state detection unit 332 detects the commercial power grid phase difference Δφc and the commercial power factor PFc. Specifically, as described above, the power generation rate PFp and the phase difference Δφp can be set to predetermined constants. Further, the value and phase of the generated voltage vp and the commercial voltage vc are equal. Therefore, the commercial power state detection unit 332 can calculate the phase difference Δφc of the commercial power system using the following equation (24).

  Δφc = Δφp + (φpi−φci) (24)

  Then, the commercial power state detection unit 332 calculates a commercial power factor PFc (= cos Δφc) based on the calculated phase difference Δφc.

  Further, the commercial power state detection unit 332 detects the commercial power flow direction based on the calculated phase difference Δφc. Specifically, when the calculated phase difference Δφc satisfies | Δφc | ≦ π / 2, the commercial power state detection unit 332 determines that the power is being purchased and sets π / 2 <| Δφc | ≦ π. If it satisfies, it is determined that the power is being sold.

  Then, the commercial power state detection unit 332 notifies the power calculation unit 333 of the commercial power factor PFc and the detection result of the power flow direction.

  In step S104, the power calculation unit 333 calculates the power of each unit.

  Specifically, in the power purchase state, the power calculation unit 333 calculates the generated power Pp, the purchased power Pcb, and the sold power Pcs by the following equations (25) to (27).

Pp = Vp × Ip × PFp (25)
Pcb = Vc × Ic × PFc (26)
Pcs = 0 (27)

  It should be noted that values similar to those in the power monitoring system 101 are used for the generated voltage effective value Vp, the commercial voltage effective value Vc, the generated current effective value Ip, the commercial current effective value Ic, and the power generation rate PFp. In addition, a value calculated by the commercial power state detection unit 332 is used as the commercial power factor PFc.

  Further, the power calculation unit 333 calculates the load power Pd by the following equation (28).

  Pd = Pp + Pcb (28)

  On the other hand, in the power selling state, the power calculating unit 333 calculates the generated power Pp, the purchased power Pcb, and the sold power Pcs by the following equations (29) to (31).

Pp = Vp × Ip × PFp (29)
Pcb = 0 (30)
Pcs = Vc × Ic × PFc (31)

  Expression (29) is the same expression as Expression (25), and the right side of Expression (31) is the same as the right side of Expression (26).

  In addition, the power calculation unit 333 calculates the load power Pd by the following equation (32).

  Pd = Pp−Pcs (32)

  Then, the power calculation unit 134 notifies the display unit 123 and the communication unit 124 of the calculated power value of each unit.

  The processing in steps S105 and S106 is the same as the processing in steps S5 and S6 in FIG. 3, and the description thereof will be omitted because it will be repeated.

  Thereafter, the process returns to step S101, and the processes after step S101 are executed.

  As described above, similarly to the power monitoring system 101, the current measuring devices ip and the commercial current ic are measured by installing only the current transformers 111p and 111c in the power system without installing the voltage measuring device in the power system. The commercial power flow direction can be detected just by doing. Further, the generated power Pp, the sold power Pcs, the purchased power Pcb, and the load power Pd can be measured almost accurately regardless of fluctuations in the commercial power factor PFc (phase difference Δφc).

<3. Modification>
In the above description, an example in which the present invention is applied to a single-phase two-wire power system has been shown. However, the present invention can also be applied to a single-phase three-wire power system.

  FIG. 17 shows an example of a current transformer installation method in the case of a single-phase three-wire system. As shown in this figure, two current transformers, current transformer 351 and current transformer 352, are connected between voltage line L1 and neutral line N (hereinafter referred to as L1 phase), and voltage line L2 And the neutral line N (hereinafter referred to as L2 phase).

  In the case of the single-phase three-wire system, when measurement of the generated current ip and the commercial current ic is performed discretely and serially, for example, the L1-phase generated current ip, the L1-phase commercial current ic, and the L2-phase generated power It is better to continuously measure the current of the same phase as in the order of the current ip, the L2 phase commercial current ic,.

  In the above description, when the determination values D1, D2, D5, D6, D7 (θ), D8 (θ), D9 (j), and D10 (j) are calculated, the generated current ip and the commercial current are calculated. Although an example in which the multiplication value of ic is integrated for one period has been shown, it may be integrated for n periods (where n is a natural number of 2 or more).

  Further, the above description shows an example in which the determination values D7 (θ), D8 (θ), D9 (j), and D10 (j) are calculated while moving the phase φci of the measured value of the commercial current ic. However, it may be calculated while moving the phase φpi of the measured value of the generated current ip.

  Furthermore, the installation direction of the current transformer 111p and the current transformer 111c is not limited to the above-described example, and can be set in an arbitrary direction. When only one of the current transformer 111p and the current transformer 111c is installed in the opposite direction to the above-described example, the determination result of the commercial power flow direction is opposite to the above-described example.

  In the above description, the determination value is calculated after converting the values of the voltage vsp and the voltage vsc into the values of the generated current ip and the commercial current ic. However, the determination is made using the voltage vsp and the voltage vsc as they are. A value may be calculated. In this case, basically, the generated current ip and the commercial current ic in the above-described formulas (1) to (6) and (20) to (23) need only be replaced with the voltage vsp and the voltage vsc.

  Further, the commercial power flow direction detection method of the first embodiment is used in the second embodiment, or the commercial power flow direction detection method of the second embodiment is used in the first embodiment. Or may be used.

  Further, for example, the commercial power flow direction may be determined based on the measured value of the generated current ip and the time zone.

  For example, when the measured value of the generated current ip is greater than or equal to a predetermined threshold, that is, when the amount of power generated by the solar power generation system 151 is large, it is determined that the power is being sold. When the power generation amount of the power generation system 151 is small, it may be determined that it is in a power purchase state. Note that this threshold value may be varied depending on the time zone. For example, the threshold value is set low during the daytime on weekdays when the home rate is low and the load power Pd is assumed to be low, and the threshold value is set during the daytime on holidays when the home rate is high and the load power Pd is high. You may make it set high.

  In addition, for example, in the time zone from sunset to sunrise when the solar power generation system 151 does not generate power, or in the case of cloudy weather or rainy weather, it may be determined that the power purchase state is unconditionally.

  Furthermore, in the above description, an example in which the power generation voltage vp is a constant is shown. However, for example, a measurement value of the power generation voltage vp may be acquired from the solar power generation system 151 and used for various calculations.

  In addition, in the embodiment of the present invention, in addition to solar power generation, any type of private power generation device such as wind power generation, diesel power generation, and fuel cell can be employed.

  Furthermore, the present invention can be applied to power systems of various facilities including private power generation devices such as buildings, factories, commercial facilities, and public facilities, in addition to general homes.

[Computer configuration example]
The series of processes of the detection device 112 and the detection device 311 described above can be executed by hardware or can be executed by software. When a series of processing is executed by software, a program constituting the software is installed in the computer. Here, the computer includes, for example, a general-purpose personal computer capable of executing various functions by installing various programs by installing a computer incorporated in dedicated hardware.

  FIG. 18 is a block diagram illustrating an example of a hardware configuration of a computer that executes the above-described series of processes using a program.

  In a computer, a CPU (Central Processing Unit) 401, a ROM (Read Only Memory) 402, and a RAM (Random Access Memory) 403 are connected to each other by a bus 404.

  An input / output interface 405 is further connected to the bus 404. An input unit 406, an output unit 407, a storage unit 408, a communication unit 409, and a drive 410 are connected to the input / output interface 405.

  The input unit 406 includes a keyboard, a mouse, a microphone, and the like. The output unit 407 includes a display, a speaker, and the like. The storage unit 408 includes a hard disk, a nonvolatile memory, and the like. The communication unit 409 includes a network interface. The drive 410 drives a removable medium 411 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory.

  In the computer configured as described above, the CPU 401 loads, for example, a program stored in the storage unit 408 to the RAM 403 via the input / output interface 405 and the bus 404 and executes the program, and the series described above. Is performed.

  The program executed by the computer (CPU 401) can be provided by being recorded on a removable medium 411 as a package medium, for example. The program can be provided via a wired or wireless transmission medium such as a local area network, the Internet, or digital satellite broadcasting.

  In the computer, the program can be installed in the storage unit 408 via the input / output interface 405 by attaching the removable medium 411 to the drive 410. The program can be received by the communication unit 409 via a wired or wireless transmission medium and installed in the storage unit 408. In addition, the program can be installed in the ROM 402 or the storage unit 408 in advance.

  The program executed by the computer may be a program that is processed in time series in the order described in this specification, or in parallel or at a necessary timing such as when a call is made. It may be a program for processing.

  Further, in the present specification, the term “system” means an overall apparatus composed of a plurality of apparatuses and means.

  Furthermore, the embodiments of the present invention are not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 101 Power monitoring system 111p, 111c Current transformer 112 Detection apparatus 121p, 121c Measurement part 122 Operation part 123 Display part 124 Communication part 131 Conversion part 132 Determination value calculation part 133 Tidal current direction detection part (detection means)
134 Power calculation unit (calculation means)
151 Solar power generation system (power generation means)
152 Commercial Power Supply 153 Load 162 PV Controller 301 Power Monitoring System 311 Detection Device 321 Calculation Unit 331 Determination Value Calculation Unit 332 Commercial Power State Detection Unit 333 Power Calculation Unit 351, 352 Current Transformer

Claims (11)

A first power system from a commercial power supply, a second power system from a power generation means for supplying power of the same frequency as the commercial power supply, and a third power supply supplied from the commercial power supply and the power generation means In the detection device for detecting the power state of the power system,
A first current transformer that measures a first current on the first power system side from a connection point of the first power system, the second power system, and the third power system;
A second current transformer for measuring a second current on the second power system side from the connection point;
Detecting means for detecting a power flow direction of the first power system;
The phase difference between the voltage and current of the second power system and the voltage and current phase difference of the third power system are set to predetermined values, the measured value of the first current, the second A detection apparatus comprising: a calculation unit that calculates a third current of the third power system based on a measured current value and a power flow direction of the first power system. When the power flow direction of the first power system is a direction in which power is supplied from the commercial power source, the calculating means is configured to set the phase difference set value of the second power system and the third power system. Calculating the third current so that a value obtained by subtracting the measured value of the second current from the third current using the set value of the phase difference becomes the measured value of the first current; When the flow direction of the first power system is a direction of supplying power to the commercial power supply, the set value of the phase difference of the second power system and the set value of the phase difference of the third power system The detection device according to claim 1, wherein the third current is calculated such that a value obtained by subtracting the third current from a measured value of the second current is a measured value of the first current. The calculation means is configured to determine the measured value of the second current, the third current, the set value of the phase difference of the second power system, and the set value of the phase difference of the third power system. The third current is calculated based on an equation obtained from the fact that the square sum of the effective current and reactive current of the first power system to be obtained is equal to the square of the measured value of the first current. The detection device according to claim 2. When the calculated value of the third current is an imaginary number, the calculating means includes at least one of the set value of the phase difference of the second power system and the set value of the phase difference of the third power system. The detection device according to claim 3, wherein one of the third currents is reduced and the third current is recalculated. The calculation means includes the measured value of the second current, the calculated value of the third current, the set value of the phase difference of the second power system, and the phase difference of the third power system. An active current of the first power system is calculated based on a set value, and an active power of the first power system is calculated based on a set value of the voltage of the first power system and a calculated value of the active current. The detection device according to claim 3. The calculation means is configured to output the third power based on a set value of the voltage of the third power system, a calculated value of the third current, and a set value of the phase difference of the third power system. The detection device according to claim 1, wherein active power of the system is calculated. The detection means calculates a determination value based on a multiplication value of the measurement value of the first current and the measurement value of the second current, and based on the determination value, the power of the first power system is calculated. The detection device according to any one of claims 1 to 5, which detects a tidal direction. A first power system from a commercial power supply, a second power system from a power generation means for supplying power of the same frequency as the commercial power supply, and a third power supply supplied from the commercial power supply and the power generation means A detection device that detects the power state of the power system,
Measuring a first current by a first current transformer on the first power system side from a connection point of the first power system, the second power system, and the third power system, A measurement step of measuring a second current by a second current transformer on the second power system side from a connection point;
A detection step of detecting a power flow direction of the first power system;
The phase difference between the voltage and current of the second power system and the voltage and current phase difference of the third power system are set to predetermined values, the measured value of the first current, the second And a calculating step of calculating a third current of the third power system based on a measured current value and a power flow direction of the first power system. Detecting means for detecting a flow direction of the first power system from the commercial power source;
The phase difference between the second power system voltage and current from the power generation means for supplying electric power having the same frequency as the commercial power source, and a third power system Ru supplied with electric power from the commercial power source and the power generating means The phase difference between the voltage and current is set to a predetermined value, and the first power system side of the first power system, the second power system, and the third power system is connected to the first power system. A measured value of a first current measured by a first current transformer, a measured value of a second current measured by a second current transformer on the second power system side from the connection point, and A detection device comprising: calculation means for calculating a third current of the third power system based on a power flow direction of the first power system. A detection device that detects the state of power,
A detection step of detecting a flow direction of the first power system from the commercial power source;
The phase difference between the second power system voltage and current from the power generation means for supplying electric power having the same frequency as the commercial power source, and a third power system Ru supplied with electric power from the commercial power source and the power generating means The phase difference between the voltage and current is set to a predetermined value, and the first power system side of the first power system, the second power system, and the third power system is connected to the first power system. A measured value of a first current measured by a first current transformer, a measured value of a second current measured by a second current transformer on the second power system side from the connection point, and And a calculating step of calculating a third current of the third power system based on a power flow direction of the first power system. A detection step of detecting a flow direction of the first power system from the commercial power source;
The phase difference between the second power system voltage and current from the power generation means for supplying electric power having the same frequency as the commercial power source, and a third power system Ru supplied with electric power from the commercial power source and the power generating means The phase difference between the voltage and current is set to a predetermined value, and the first power system side of the first power system, the second power system, and the third power system is connected to the first power system. A measured value of a first current measured by a first current transformer, a measured value of a second current measured by a second current transformer on the second power system side from the connection point, and A program for causing a computer to execute processing including a calculation step of calculating a third current of the third power system based on a power flow direction of the first power system.

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