JP6730172B2 - Power system - Google Patents

Description

The present invention relates to an electric power system capable of detecting that the electric power supplied from an electric power system is in an insufficient state at a power receiving end.

In recent years, connecting power supply equipment such as solar power generation equipment to load equipment at the consumer's house, covering the load with the power of the power supply equipment, and connecting the power supply equipment and the power grid (commercial power grid), When the electric power generated by the electric power supply equipment is less than the electric power consumed by the load equipment, the grid interconnection is performed to receive the insufficient electric power from the electric power grid.

Under such a grid connection, if the power supply from the power grid side is stopped due to a warning power failure of the power grid, etc., all load equipment connected to the power supply equipment, including load equipment at the customer's home It will be an independent operation that supplies the electric power of only with electric power supply facilities. In isolated operation, there is a risk that the power supply facility may be overloaded and that a reverse power flow (reverse charging) from the power supply facility to the power system side may cause electric shock or damage to consumer equipment. In order to avoid such isolated operation and reverse charging, an insufficient power relay (UPR) that detects that the power supply from the power grid is insufficient at the power receiving end and disconnects the power supply equipment from the power grid Can be used (for example, Patent Document 1).

JP-A-6-141471

As a power supply facility such as a solar power generation facility or a fuel cell, what is connected to an R phase and a T phase in a single-phase three-wire system 100/200V is currently used. In the system interconnection described above, in the power supply facility connected to the R phase and the T phase in the single-phase three-wire system 100/200V, the current values of the R phase and the T phase, which are voltage lines, and the interphases for the N phase, respectively. Obtain the voltage value, obtain the received power from the current value, the inter-phase voltage value, and the power factor based on the phase of the current and voltage, and the power supply from the power system is insufficient at the receiving end (the received power is less than the specified value) It is conceivable to determine whether or not

Further, in the future, when energy-saving equipment becomes widespread and the power demand on the premises decreases, it is not always necessary to connect the R phase and the T phase in the single-phase three-wire system 100/200V. It is conceivable to install a small output power supply facility connected to only the R and N phases, or the T and N phases corresponding to one of /200V. However, in such a small output power supply facility, the inter-phase voltage value of the connected interconnection phase can be detected, but the inter-phase voltage value of the non-connected interconnection phase cannot be detected. Therefore, the product of the R-phase current value, the T-phase current value, the interphase voltage value, and the power factor cannot be obtained, and it becomes impossible to determine the insufficient power.

In view of such a problem, the present invention is a power system capable of appropriately detecting a power shortage even in a power supply facility that is connected only to a single-phase three-wire R-phase or T-phase and an N-phase. Is intended to provide.

In order to solve the above problems, a power system of the present invention includes a power supply facility connected to one of voltage lines of a single-phase three-wire system that is a service line from a power system and a neutral line. A first ammeter for measuring a current value flowing through a voltage line connected to the power supply facility, and a voltmeter for measuring an interphase voltage value for a neutral line of the voltage line connected to the power supply facility , A second ammeter that measures the current value flowing in the voltage line that is not connected to the power supply facility, the current value measured by the first ammeter and the interphase voltage value measured by the voltmeter, and its power factor And a value obtained by multiplying the current value measured by the second ammeter and a value obtained by multiplying a predetermined assumed value and a predetermined assumed power factor by a power derivation unit that derives the received power, and the received power. And a power shortage determining unit that determines whether or not power shortage has occurred at the power receiving end.

The power deriving unit derives the assumed power factor by regarding the phase of the interphase voltage that is not connected to the power supply equipment as the phase that is the inverted phase of the interphase voltage related to the voltage line that is connected to the power supply equipment. May be.

The power derivation unit may use, as an assumed value, one of a specified minimum voltage value and a specified maximum voltage value that can be taken as the interphase voltage value according to the power flow direction of the voltage line that is not connected to the power supply facility.

The power derivation unit may set the assumed power factor to 0 or 1 depending on the power flow direction of the voltage line that is not connected to the power supply facility.

Equipped with a power meter that is connected to the power grid and can measure the interphase voltage value for the neutral line of the voltage line that is not connected to the power supply equipment, and the power derivation unit uses the interphase voltage value measured by the power meter as the expected value. May be

The power derivation unit statistically processes the interphase voltage value measured by the power meter and statistically derives the actually measured minimum voltage value and actually measured maximum voltage value according to the power flow direction of the voltage line that is not connected to the power supply equipment. Any of the voltage values may be the assumed value.

ADVANTAGE OF THE INVENTION According to this invention, even if it is the electric power supply equipment connected only to the R phase or T phase of a single phase 3-wire type, and N phase, it becomes possible to detect an insufficient electric power appropriately.

It is explanatory drawing which showed the connection relation of the electric power system in 1st Embodiment. It is an explanatory view for explaining a subject of the 2nd power supply equipment. It is explanatory drawing which showed the connection relation of the electric power system in 2nd Embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the invention unless otherwise specified. In this specification and the drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to omit redundant description, and elements not directly related to the present invention are omitted. To do.

(First embodiment: power system 100)
FIG. 1 is an explanatory diagram showing a connection relationship of the power system 100 according to the first embodiment. In FIG. 1, the movement of power is indicated by a solid line and the signal including information is indicated by a dashed arrow. The power system 100 is supplied with electricity (commercial power) from the power grid 14 through the service line 12. The electric power system 100 is configured on a consumer unit basis, and the range is not limited to houses and the like as long as it is a general electric facility (consumer of low-voltage power reception), hospitals, factories, hotels, leisure facilities, and commerce. It may be a building unit such as a facility or an apartment house or a part of the building.

The power system 100 also includes a power meter 112, a distribution board 114, a first power supply facility 116, a first individual circuit breaker 118, a second power supply facility (power supply facility) 120, and a second individual power supply facility. The circuit breaker 122 and the ammeter 124 are included.

The electric power meter (electric energy meter) 112 is connected to the electric power system 14 via the service line 12 and measures a current value (consumption and power sale) flowing between the service line 12 and the power system 100.

The distribution board 114 is connected to the electric power meter 112, and has a service breaker (service breaker) 114a that indicates a contracted capacity, an earth leakage breaker (leakage breaker) 114b that shuts off the supply of electricity in response to detection of electric leakage, and a plurality of Each of the branch circuits 130 has a wiring breaker (safety breaker) 114c that cuts off the supply of electricity when the allowable current value (for example, 20 A) is exceeded. Although the service breaker 114a is described as the configuration of the distribution board 114 here, the service breaker 114a itself may not be installed, and may be provided in the power meter 112.

The first power supply equipment 116 is connected to the R-phase and T-phase on the secondary side of the earth leakage breaker 114b through a first individual breaker 118 that prevents overcurrent and earth leakage, and converts other energy into electric energy. The electricity is converted to generate electricity, and the electricity thus generated is given priority over the power system 14 and supplied to the load facility 16 that consumes electrical energy. Examples of the power supply equipment such as the first power supply equipment 116 and the second power supply equipment 120 described later include, for example, a solar power generator, a wind power generator, a hydroelectric power generator, a geothermal power generator, a solar thermal power generator, an atmospheric thermal power generator. Renewable energy power generation equipment such as fuel cell, internal combustion power generation, and storage battery can be used. Hereinafter, the R phase and the T phase of the single-phase three-wire system 100/200V are referred to as the single-phase three-wire system 200V, and the R-phase and the N-phase or the T-phase and the N-phase are referred to as the single-phase three-wire system 100V.

The second electric power supply facility 120 is provided with an R-phase and an N-phase or a T-phase and an N-phase among the plurality of branch circuits 130 in the distribution board 114 via the second individual circuit breaker 122 that prevents overcurrent. Connected to any of. Then, the second power supply facility 120 converts other energy into electric energy in the power generation unit G to generate electricity, and like the first power supply facility 116, gives priority to the generated electricity over the power system 14. The load equipment 16 is supplied.

In addition, the second power supply facility 120 is configured to include a voltmeter 120a, a disconnecting section 120b, and a control unit 120c. The voltmeter 120a is composed of, for example, an instrument transformer (VT), and transmits the interphase voltage value of the voltage line (R phase or T phase) to the N phase (neutral line) to the control unit 120c. Here, the example in which the voltmeter 120a is formed integrally with the second power supply equipment 120 has been described, but it may be provided as a separate body. The disconnecting unit 120b shuts off the power supply (output) from the power generation unit G. The control unit 120c is composed of a semiconductor integrated circuit including a central processing unit (CPU), a ROM in which programs and the like are stored, a RAM as a work area, and the like, and controls the entire second power supply facility 120. Here, an example in which the control unit 120c is formed integrally with the second power supply facility 120 has been described, but it may be provided as a separate body.

The ammeter 124 is composed of, for example, a current transformer (CT), and inserts (clamps) the R-phase and T-phase wires, which are voltage lines, into each of the penetrating bodies (iron core, core) in which the primary windings are arranged. , The respective current values are converted into measured values and transmitted to the second power supply equipment 120. In addition, here, although an example in which the ammeter 124 is attached to the secondary side of the service breaker 114a and the primary side of the earth leakage breaker 114b will be described, the load equipment 16, the first power supply equipment 116, Further, it may be arranged at any position on the power system 14 side of the second power supply facility 120.

By the way, as the power supply equipment, as in the case of the above-described first power supply equipment 116, it is common to connect and use a single-phase three-wire type 200V. In this case, an interconnecting circuit breaker (200V) is provided in parallel with the wiring circuit breaker 114c, and the first power supply facility 116 is connected to the interconnecting circuit breaker via the first individual circuit breaker 118. It is necessary to connect the first power supply equipment 116 from the primary side of the earth leakage breaker 114b through a separate individual breaker (200V).

However, in the future, when energy-saving equipment becomes widespread and the power demand of the power system 100 decreases, it is not always necessary to connect to the single-phase three-wire system 200V. Connected to only single-phase 3-wire system 100V (R phase and N phase, or T phase and N phase) consisting of either R phase or T phase which is a power line of 200V and N phase which is a neutral line The second power supply facility 120 of small output is installed.

If the single-phase three-wire system 100V can be operated in this way, the second power supply facility 120 can be connected to the outdoor outlet by using the existing branch circuit 130 as shown in FIG. 1 without interposing an interconnection breaker or the like. It becomes possible to do. With such a configuration, it is possible to effectively use the existing premises wiring, reduce the construction cost, and simplify the wiring in the power system 100.

However, when connecting the second power supply equipment 120 to the single-phase three-wire system 100V, the following problems occur. For example, under the system interconnection of the power system 14 and the second power supply facility 120, if the power system 14 is unwarned due to a system side short-circuit accident or the like and the power supply from the power system 14 side is stopped, the user It becomes an independent operation in which the power of all the load facilities 16 connected to the second power supply facility 120 including the load facility 16 of the house is covered by only the second power supply facility 120. In the islanding operation, the second power supply facility 120 may be overloaded, or shortage of power from the second power supply facility 120 to the power system 14 side may cause electric shock or damage to consumer equipment. Occurs. Therefore, in order to avoid islanding or reverse charging, it is detected that the power supplied from the power system 14 is insufficient at the power receiving end, and at least the second power supply facility 120 is disconnected from the power system 14. There must be.

At this time, in the case of the first power supply equipment 116, the interphase voltage values for the R-phase and T-phase current values and the N-phase, which are voltage lines, are obtained, and the current value, the interphase voltage value, the current, and the voltage are calculated. It is possible to obtain the received power from the power factor based on the phase of and to determine whether or not the power supplied from the power system 14 (received power) is insufficient at the power receiving end. However, the second power supply facility 120 can detect the interphase voltage value of the interconnected single-phase three-wire system 100V, but cannot detect the interphase voltage value of the other non-interconnected single-phase three-wire system 100V. .. Therefore, the product of the current value, the interphase voltage value, and the power factor of both the R-phase and the T-phase cannot be obtained, and the power shortage cannot be determined.

FIG. 2 is an explanatory diagram for explaining the problem of the second power supply equipment 120. As shown in FIG. 2A, consider a case where only the first power supply equipment 116 is connected. In this case, of the two ammeters 124, the R-phase ammeter (first ammeter) 124a measures the R-phase current value I _R and the T-phase ammeter (second ammeter) 124b measures the current value I _T. was measured, voltmeter 116a of the first power supply system 116 will measure the phase-to-phase voltage value _{V R} for N phase of R-phase, voltmeter 116b measures the phase voltage _{V T} for N phase of T-phase.

Then, for each phase (R phase, T phase), the product of the current value, the interphase voltage value, and the power factor (I _R ×V _R ×cos θ _R , I _T ×V _T ×cos θ _T ) is calculated, and the sum thereof is obtained. The insufficient power can be detected by whether or not (I _R ×V _R ×cos θ _R +I _T ×V _T ×cos θ _T ) is less than or equal to a predetermined value.

However, as in FIG. 2 (b), when connecting the second power supply system 120, although detectable interphase voltage V _R for N phase of R-phase is interconnection phase, a non-interconnection phase T The interphase voltage value V _T for the N phase of the phases cannot be detected.

Therefore, in the present embodiment, the second power supply equipment 120 is substantially equal to the first power supply equipment 116 by assuming the interphase voltage value of the other single-phase three-wire system 100V that cannot be measured. Appropriately detect insufficient power under the conditions. Hereinafter, the determination mode will be described in detail with reference to FIG.

Here, the load facility 16, the second power supply facility 120, and the first power supply facility 116 are located downstream of the R-phase ammeter 124a and the T-phase ammeter 124b as viewed from the power system 14. Therefore, by estimating the lacking information, the power flow including all the load equipment 16, the second power supply equipment 120, and the first power supply equipment 116 at the positions of the R-phase ammeter 124a and the T-phase ammeter 124b. It is possible to estimate the mode (direction of power flow and received power).

The control unit 120c in the second power supply facility 120 also functions as the power derivation unit 140 and the power shortage determination unit 142 by operating the program.

The power deriving unit 140 acquires the current value I _R of the R phase, which is the interconnection phase, from the R phase ammeter 124 a, and obtains the current value I _T of the T phase, which is the non-interconnection phase, from the T phase ammeter 124 b. acquired from voltmeter 120a, obtains the phase voltage V _R for N phase of R-phase is interconnection phase. Further, the power factor cos θ _R is derived based on the phase of the R-phase current and the interphase voltage that are the interconnected phases. Then, the power derivation unit 140 refers to the predetermined assumed value V _TA and the assumed power factor cos θ _TA of the interphase voltage value for the T phase and the N phase, and derives the received power converted into the single-phase three-wire system 100/200V. .. Specifically, the power derivation unit 140 obtains the power (I _R ×V _R ×cos θ _R ) related to the R phase and the assumed power (I _T ×V _TA ×cos θ _TA ) related to the T phase, and the sum (I _R × and _{V R × cosθ R + I T} × V TA × cosθ TA) to derive the reception power of the single-phase three-wire 100 / 200V.

The power shortage determination unit 142 determines whether power shortage has occurred based on the received power of the single-phase three-wire system 100/200V derived by the power derivation unit 140. Specifically, the power shortage determination unit 142 determines that power shortage has occurred if the received power is less than or equal to a positive predetermined value. Then, the power shortage determination unit 142 cuts off the power supply from the second power supply facility 120 through the disconnecting unit 120b (sets the output to 0) based on the occurrence of the power shortage. Therefore, the power shortage determination unit 142 functions as a power shortage relay (UPR).

In addition, here, although the disconnecting section 120b is described as an example in which it is integrally formed with the second power supply equipment 120, it may be provided as a separate body. Further, here, an example is given in which the power supply is cut off or the output is set to 0, but the output may be reduced.

With such a configuration, even with the second power supply equipment 120 that is connected only to the single-phase three-wire system 100V, the received power of the single-phase three-wire system 100/200V can be obtained, and the second power supply equipment 120 It becomes possible to appropriately detect the power shortage.

By the way, according to the Electricity Business Law, the interphase voltage value of the electric power supplied from the electric power company is determined to be within the range of 101V±6V. Therefore, the inter-phase voltage value V _T of the _T phase with respect to the N phase fluctuates only within the range of 95 V (specified minimum voltage value) to 107 V (specified maximum voltage value). Therefore, a possible range as a phase voltage value, further, in consideration of the voltage drop of the drop line 12 (e.g. 2V), select the assumed value V _TA of interphase voltage values for N phase of T-phase as described above for example 101V can do.

Further, in such an electric power system 100, since the loads of the R phase and the T phase are often close to uniform, the assumed value V _TA of the interphase voltage value for the N phase of the T phase is, for example, the interconnection phase. the interphase voltage value V _R for N phase of R-phase, may be diverted as it is. In addition, since the R phase and the T phase are 180 degrees out of phase with each other, the assumed power factor cos θ _TA is, for example, the phase of the interphase voltage with respect to the N phase of the T phase which is the non-connected phase, and the R phase which is the connected phase. The assumed power factor cos θ _TA may be determined by regarding the phase of the interphase voltage with respect to the N phase of (1) as the inverted phase (180 degrees different).

In addition, the power derivation unit 140 may determine the assumed value V _TA and the assumed power factor cos θ _TA according to the power flow direction of the T-phase power that is the other of the voltage lines. Here, the interphase voltage for the N phase of the interconnected phase and the current of the T phase that is the non-interconnected phase are measured, so that the phase of the interphase voltage and the phase of the current are not used for disconnection. The flow direction of the T phase, which is the system phase, can be derived. For example, it is assumed that the T-phase is reverse power flow (direction different from the one-dot chain line arrow in FIG. 2). At this time, the inter-phase voltage value V _T of the _T phase with respect to the N phase may fluctuate in the range from the specified minimum voltage value (95 V) to the specified maximum voltage value (107 V), so that the power related to the T phase is (current value I _T It will vary in the range of (specified minimum voltage value) to (current value _IT × specified maximum voltage value).

Here, in order to make a strict (safety) determination of the power shortage, it is assumed that the power shortage occurs at the maximum power that can be assumed in the T phase. That is, the electric power of the T phase is defined as (current value _IT ×specified maximum voltage value). Therefore, the power derivation unit 140 sets the specified maximum voltage value as the assumed value V _TA when the T-phase is reverse power flow. Further, in order to make a strict (safety) determination of the power shortage, the assumed power factor cos θ _TA may be regarded as 1 so that the T-phase power becomes maximum.

Similarly, when the T-phase is forward power flow (direction equal to the one-dot chain line arrow in FIG. 2), the power derivation unit 140 determines the minimum power that can be assumed in the T-phase so as to strictly determine (on the safe side) the forward power flow. It is assumed that the forward power flow only occurs. That is, the electric power of the T phase is set to (current value _IT ×specified minimum voltage value). Therefore, the power derivation unit 140 sets the specified minimum voltage value as the assumed value V _TA when the T-phase is forward power flow. Further, in order to make a strict (safety) determination of the power shortage, the assumed power factor cos θ _TA may be regarded as a predetermined value (for example, 0) and calculated so that the power of the T phase is minimized.

With this configuration, it is possible to obtain the received power on the safest side when the second power supply equipment 120 connected only to the single-phase three-wire system 100V is converted into the single-phase three-wire system 100/200V. It becomes possible to detect the power shortage of the power supply equipment 120 more reliably and appropriately.

Further, here, as illustrated in FIG. 2B, the example in which the second power supply facility 120 is connected to the single-phase three-wire system 100V on the R-phase side has been described, but as illustrated in FIG. In addition, when the second power supply facility 120 is connected to the single-phase three-wire system 100V on the T phase side, the insufficient power can be detected by the same calculation.

That is, the power deriving unit 140 acquires the R-phase current value I _R from the R-phase ammeter (second ammeter) 124a, and acquires the T-phase current value I _T from the T-phase ammeter (first ammeter) 124b. And the inter-phase voltage value V _T for the N phase of the T phase is acquired from the voltmeter 120a. Further, the power factor cos θ _T is derived based on the current of the T-phase which is the interconnection phase and the phase of the interphase voltage. Then, the power derivation unit 140 refers to the predetermined assumed value V _RA and the assumed power factor cos θ _RA of the interphase voltage value for the R phase and the N phase, and derives the received power converted into the single-phase three-wire system 100/200V. .. Specifically, the power deriving unit 140, the assumptions about R-phase power _{(I R × V RA × cosθ} RA), obtains the power _{(I T × V T × cosθ} T) for T-phase, the sum _{(I R} X V _RA x cos θ _RA + I _T x V _T x cos θ _T ) is derived to obtain single-phase three-wire 100/200 V received power.

Then, the power shortage determination unit 142 determines that power shortage has occurred if the received power of the single-phase three-wire 100/200 V derived by the power derivation unit 140 is equal to or less than a positive predetermined value, and through the disconnection unit 120b. The power supply from the second power supply facility 120 is shut off or the output is reduced.

With such a configuration as well, it is possible to obtain the received power on the safest side when the second power supply facility 120 connected only to the single-phase three-wire system 100V is converted into the single-phase three-wire system 100/200V. (2) It becomes possible to detect the power shortage of the power supply equipment 120 more reliably and appropriately.

(Second embodiment: power system 200)
FIG. 3 is an explanatory diagram showing a connection relationship of the power system 200 according to the second embodiment. In the electric power system 200, the process of the electric power deriving unit 240 is different from that of the first embodiment, but other components are substantially the same as those of the first embodiment.

In the second embodiment, the power derivation unit 240 does not fixedly select the assumed value, acquires information about the interphase voltage value from any device of the power system 200, and based on the information, sets the assumed value at any time. decide. For example, in the example of FIG. 3, the power deriving unit 240 determines that the interphase voltage value in the power meter 112, specifically, the interphase voltage of a phase (non-interconnection phase) different from the interconnection phase of the second power supply facility 120. Obtain the value and use the interphase voltage value as the assumed value.

With such a configuration, the value close to the original interphase voltage value is used as the assumed value, and the received power can be obtained more accurately, so that the shortage of power in the second power supply facility 120 can be detected more appropriately.

However, depending on the update frequency of the interphase voltage value of the power meter 112, a value different from the original interphase voltage value will be referred to. For example, when the power meter 112 is updated only once in several tens of seconds, the interphase voltage value to be referred to may be the interphase voltage value of several tens of seconds ago. Therefore, the power derivation unit 240 may accumulate the inter-phase voltage value in the power meter 112 and statistically process it to determine the assumed value.

For example, the power derivation unit 240 accumulates the inter-phase voltage value for the past arbitrary period (year, month, week, day, time, etc.) in the power meter 112, and the minimum voltage value during that period (measured minimum voltage value). And the maximum voltage value (measured maximum voltage value). Here, since the inter-phase voltage value V _T of the _T phase with respect to the N phase fluctuates in the range from the actually measured minimum voltage value to the actually measured maximum voltage value, the power related to the T phase is (current value I _T ×measured minimum voltage value). X power factor) to (current value _IT x actually measured maximum voltage value x power factor).

Here, when the T-phase is reverse power flow (direction different from the alternate long and short dash line arrow in FIG. 2), the power derivation unit 240 sets the measured maximum voltage value on the safe side as the assumed value V _TA . In addition, when the T-phase current value _IT is forward power flow (direction equal to the one-dot chain line arrow in FIG. 2), the power derivation unit 240 sets the measured minimum voltage value on the safe side as the assumed value _VTA. ..

With this configuration, it is possible to obtain the received power on the safest side when the second power supply equipment 120 connected only to the single-phase three-wire system 100V is converted into the single-phase three-wire system 100/200V. It becomes possible to detect the power shortage of the power supply equipment 120 more reliably and appropriately.

The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such embodiments. It is obvious to those skilled in the art that various changes or modifications can be conceived within the scope described in the claims, and naturally, they also belong to the technical scope of the present invention. Understood.

For example, in the above-described embodiment, the example in which the power meter 112 transmits the interphase voltage value to the control unit 120c has been described, but when the power meter 112 is a smart meter, the function thereof is, for example, HEMS. It may be transmitted from the power meter 112 to the control unit 120c through (Home Energy Management System).

Further, in the above-described embodiment, an example in which interphase voltage values for an arbitrary period in the past are accumulated and a minimum voltage value (actually measured minimum voltage value) and a maximum voltage value (actually measured maximum voltage value) between them are obtained is given. Although described, the effective minimum voltage value (measured minimum voltage value) and maximum voltage value (measured maximum voltage value) may be obtained from statistically derived statistical deviations, for example.

Further, in the above-described embodiment, when the power shortage determination unit 142 determines that power shortage has occurred, an example will be described in which the power supply from the second power supply facility 120 is cut off or the output is reduced through the disconnecting unit 120b. However, the target for shutting down or lowering the output is not limited to the second power supply equipment 120, and in addition to or in place of the second power supply equipment 120, various power supply equipment managed by a consumer can be used.

INDUSTRIAL APPLICATION This invention can be utilized for the electric power system which can detect that the electric power supplied from an electric power system is in a shortage state at the receiving end.

14 power system 16 load facility 100, 200 power system 114 distribution board 120 second power supply facility (power supply facility)
120a Voltmeter 120c Control unit 124a R-phase ammeter (first ammeter, second ammeter)
124b T-phase ammeter (second ammeter, first ammeter)
140, 240 Power derivation unit 142 Insufficient power determination unit

Claims (6)

A power supply facility connected to one of the voltage lines of the single-phase three-wire system that is a service line from the power system and a neutral line;
A first ammeter for measuring a current value flowing in a voltage line connected to the power supply facility;
A voltmeter that measures a phase-to-phase voltage value with respect to a neutral line of a voltage line that is connected to the power supply facility,
A second ammeter for measuring a current value flowing in a voltage line not connected to the power supply facility;
A value obtained by multiplying the current value measured by the first ammeter, the interphase voltage value measured by the voltmeter, and its power factor, the current value measured by the second ammeter, and a predetermined assumed value. And a value obtained by multiplying a predetermined assumed power factor by a power derivation unit that derives received power,
Based on the received power, a power shortage determination unit that determines whether power shortage occurs at the power receiving end,
Power system comprising. The power derivation unit regards the phase of the interphase voltage that is not interconnected with the power supply facility as a phase obtained by inverting the phase of the interphase voltage related to the voltage line that is interconnected with the power supply facility, and the assumed force. The power system of claim 1, wherein the rate is derived. The power derivation unit sets the assumed value to one of a specified minimum voltage value and a specified maximum voltage value that can be taken as an interphase voltage value, according to the power flow direction of a voltage line that is not connected to the power supply facility. The electric power system according to Item 1 or 2. The power system according to claim 3, wherein the power derivation unit sets the assumed power factor to 0 or 1 according to the power flow direction of the voltage line that is not connected to the power supply facility. A power meter that is connected to the power system and is capable of measuring an interphase voltage value with respect to a neutral line of a voltage line that is not connected to the power supply facility,
The power system according to claim 1, wherein the power deriving unit sets the inter-phase voltage value measured by the power meter as the assumed value. The power derivation unit statistically processes the inter-phase voltage value measured by the power meter, and according to the power flow direction of the voltage line that is not connected to the power supply equipment, the statistically derived measured minimum voltage value. The power system according to claim 5, wherein any one of the maximum voltage value and the actually measured maximum voltage value is set as the assumed value.

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