KR101277141B1 - Electric watt-hour meter and method for monitoring power distribution system - Google Patents

Abstract

PURPOSE: An electronic watt-hour meter and a method for monitoring a distribution system are provided to monitor temporal electric confusion and high resistance grounding fault of the distribution system when a relay does not operate because fault current duration time is short or the amplitude of a fault current is not enough high in the distribution system. CONSTITUTION: An electronic watt-hour meter(1) includes a receiving part(12), a first comparison part, and a determination part(14). The receiving part receives an operation state of a circuit breaker of a distribution system. The first comparison part generates the amplitude of the sum of one period about a difference between a prior period sample and a current period sample, and provides the current period wave fluctuation information and the sample waveform to the determination part if the current period waveform fluctuation information is larger than the waveform fluctuation pickup setting. The determination part determines a waveform fluctuation condition or a single phase waveform fluctuation condition from the operation state of the circuit breaker and the waveform fluctuation information received from the first comparison part. [Reference numerals] (10) Matching part; (11) A/D converter; (12) State receiving part; (13) Sample comparing part; (14) Determination part; (15) Current phase comparing part; (16) Communication part; (17) Storage part; (18) Display part; (19) RTC part; (300) Upper system

Description

ELECTRICAL WATT-HOUR METER AND METHOD FOR MONITORING POWER DISTRIBUTION SYSTEM}

The present invention relates to an electronic power meter and a distribution system monitoring method thereof.

1 is a diagram of a substation and a distribution system.

As shown in the figure, the distribution system 100 is a system for supplying electricity from the substation 200 to the customer, the processing supplies electricity using a pole, and the underground supplies electricity using an underground power outlet. . Among them, since the overhead distribution system is exposed to the outside, accidents occur in the distribution system 100 due to various causes such as insulation breakdown of the distributor, vehicle collision, wind contact, magpie house, and the like.

The accident of the power distribution system is a short circuit or ground fault, the fault current is generally a certain size or more, the protection relay 230 installed in the power distribution outlet of the substation 200 operates the breaker 220 to protect the system. .

However, due to the temporary contact of the distribution system 100, the fault current is eliminated before the operation time of the protection relay 230, or the impedance of the fault occurrence point is not high enough to generate a sufficient fault current so that the operation of the protection relay 230 is picked up. If the value is not reached, abnormality has occurred in the system 100, but the protective device does not operate, causing a situation that damages the distribution system 100 or a person.

In the case of temporary contact with the power distribution system 100, since the protective relay 230 does not operate, the operator does not detect the abnormality of the system, and thus often develops into an actual failure. In addition, in the case of high resistance ground fault, the fault current impedance is high, but the fault current is small, but it may damage the pedestrians passing through the corresponding area since the actual fault condition. Conventionally, in order to monitor the high resistance ground fault, it is time-consuming to find the cause of failure because it relies on the change of the current of the distribution system 100 or the power failure report of the customer in the upper system 300.

However, when the operation pickup value and the operation time of the protection relay 230 are reduced in order to respond to temporary fluctuations in the distribution system 100 or a high resistance ground fault, the circuit breaker 220 operates even in the case of a load variation in which a failure does not occur. Thus, there is a problem that can cause excessive power failure.

The technical problem to be solved by the present invention is an electronic power meter for monitoring the instantaneous mixing of the power distribution system and high resistance ground fault even when the protection relay does not operate due to short duration of the fault current or insufficient magnitude of the fault current in the distribution system. To provide a method for monitoring the distribution system.

In order to solve the above technical problem, the electronic electricity meter of the present invention, the receiving unit for receiving the operating state of the circuit breaker of the distribution system; Generates the magnitude (waveform fluctuation information) of one cycle for the difference between the full-cycle sample and the current-cycle sample, and determines the current-cycle waveform fluctuation information and the sample waveform when the current-cycle waveform fluctuation information is larger than the waveform fluctuation pickup setting. A first comparison unit to provide a wealth; And a determination unit for determining a waveform fluctuation situation or a single phase waveform fluctuation condition from the waveform fluctuation information received from the first comparator and the operation state of the circuit breaker.

In one embodiment of the present invention, the current phase, the current cycle fluctuation information, and the sample waveform are determined when the current phase difference is greater than the phase oscillation pickup setting by comparing the current cycle current phase with the current cycle current phase based on voltage. The apparatus may further include a second comparator provided as a negative part, and the determiner may determine a phase fluctuation expected from the current phase difference received from the second comparator and the operation state of the circuit breaker.

In one embodiment of the present invention, the first comparator may generate the waveform fluctuation information by the following RMS equation.

In this case, f (t) is the sample difference minus the full period sample from the current period sample, T may be a period.

In one embodiment of the present invention, the determination unit, if the current RMS of the current cycle is greater than the fault current pickup setting, and the breaker is closed, it can be determined as the waveform fluctuation situation.

In one embodiment of the present invention, the determination unit, the waveform shake information of the current cycle is larger than the waveform shake pickup setting, the breaker is closed, the waveform shake information of the current cycle is larger than the waveform shake information of the previous cycle, the inrush current If the current cycle current RMS is smaller than the fault current pickup setting and the waveform fluctuation information occurs in the single phase, it can be determined as the single phase waveform fluctuation situation.

In one embodiment of the present invention, the determination unit, the current phase difference is larger than the phase oscillation pickup setting, the breaker is closed, no inrush current occurs, the current cycle current RMS is smaller than the fault current pickup setting, the phase change is single phase In the case of, it can be determined as the phase fluctuation situation.

In one embodiment of the present invention, a matching unit for matching the applied voltage or current; And a converting unit converting the analog signal passing through the matching unit into digital data.

In one embodiment of the present invention, a storage unit for storing the information of the waveform shake situation, the single-phase waveform shake situation and the phase shake situation; And a communication unit configured to transmit information of the waveform fluctuation situation, the single phase waveform fluctuation condition, and the phase fluctuation condition to an upper system.

In one embodiment of the present invention, the waveform fluctuation situation, the single-phase waveform fluctuation state and the phase fluctuation situation may further include a display for displaying the information of the phase fluctuation situation to the user.

In one embodiment of the present invention, the storage unit for storing the information of the waveform shake situation and the single-phase waveform shake situation; And a communication unit configured to transmit information of the waveform fluctuation situation and the single phase waveform fluctuation condition to a higher level system.

In one embodiment of the present invention, a display unit for displaying the information of the waveform fluctuation situation and the single-phase waveform fluctuation situation to the user may be further included.

In addition, in order to solve the above technical problem, the distribution system monitoring method of the present invention comprises the steps of generating the amplitude of the sum of one cycle for the difference between the sample of the full cycle and the current cycle sample as the waveform fluctuation information; Comparing the current cycle current RMS with the fault current pickup setting; Confirming the operation of the breaker; And determining the waveform fluctuation situation.

In an embodiment of the present disclosure, the determining of the waveform fluctuation condition may be determined as the waveform fluctuation condition when the current cycle current RMS is greater than the fault current pickup setting and the breaker is closed.

In one embodiment of the present invention, if the waveform fluctuation information of the current period is larger than the waveform shake pickup setting, checking the operation of the breaker; Comparing the full period waveform fluctuation information with the current period waveform fluctuation information; Checking whether an inrush current has occurred; Comparing the current cycle current RMS with the fault current pickup setting; Confirming whether the waveform fluctuation information occurred in a single phase; And determining the single phase waveform fluctuation situation.

In one embodiment of the present invention, the determining of the single-phase waveform fluctuation state, the circuit breaker is closed, the full-cycle waveform fluctuation information is smaller than the current period waveform fluctuation information, the inrush current does not occur, the current cycle current RMS is When the wave current fluctuation information is smaller than the fault current pick-up setting and occurs in the single phase, it can be determined as the single phase wave shape fluctuation situation.

In an embodiment of the present invention, the method may further include storing fluctuation information and a sample waveform of the waveform fluctuation situation and transmitting the same to a higher system.

In an embodiment of the present invention, the method may further include storing fluctuation information and a sample waveform of the single-phase waveform fluctuation situation and transmitting the same to a higher system.

In one embodiment of the present invention, the method may further include storing the current sample as a full period sample for the next period.

In addition, in order to solve the technical problem as described above, the distribution system monitoring method of the present invention, comparing the current cycle current phase based on the voltage with the full cycle current phase, generating a current phase difference; When the current phase difference is greater than the set value, confirming the operation of the breaker; Checking whether an inrush current has occurred; Comparing the current cycle current RMS with the fault current pickup setting; Checking whether a phase change occurred in a single phase; And determining the phase fluctuation situation.

In one embodiment of the present invention, the step of determining the phase fluctuation condition is performed when the circuit breaker is closed, no inrush current occurs, the current cycle current RMS is larger than the fault current pickup setting, and the phase change occurs in a single phase. The phase fluctuation may be determined.

In an embodiment of the present invention, the method may further include storing a current phase, fluctuation information, and a sample waveform of the phase fluctuation situation and transmitting the same to a higher system.

In one embodiment of the present invention, the method may further include storing the current current phase as a full-cycle current phase.

In the present invention as described above, the magnitude of one cycle sum for the difference between the full-cycle sample and the current-cycle sample of the electricity meter is set for the fluctuation of the system in which the protection relay cannot operate due to a short or small failure duration. In the case of the above, it is determined that the magnitude or shape of the current has changed drastically, and the higher-level system judges the fluctuation of the system, thereby increasing the operating efficiency of the distribution system.

In addition, when the impedance of the ground fault occurrence point of the distribution line is high, the impedance of the ground line changes, which causes the current phase of the ground line to change abruptly. By anticipating a high resistance ground fault, it provides the waveform fluctuation and phase fluctuation generation information to the host system through communication, thereby quickly coping with the high resistance ground fault and increasing the operation efficiency of the distribution system.

Therefore, according to the present invention, there is an effect to reduce the damage applied to the distribution system or pedestrians.

1 is a diagram of a substation and a distribution system.
2 is a block diagram of an electronic power meter according to an embodiment of the present invention.
3A and 3B are exemplary views for explaining the difference between the previous period sample and the current period sample.
4 is a flowchart illustrating an embodiment of a distribution system monitoring method of the present invention.
5 is a flowchart illustrating another embodiment for explaining a distribution system monitoring method of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a configuration diagram of an electronic electricity meter according to an embodiment of the present invention, the electronic electricity meter 1 of the present invention is provided to the withdrawal end of the distribution system 100 as shown in FIG. Communicate

As shown in the figure, the electronic wattmeter 1 of the present invention includes a matching unit 10, an analog / digital (A / D) converter 11, a state receiving unit 12, a sample comparing unit (13), a determination unit 14, a current phase comparison unit 15, a communication unit 16, a storage unit 17, a display unit 18, and a real time counter (RTC) 19 . The sample comparator 13, the determiner 14, and the current phase comparator 15 may be collectively referred to as a controller 20.

The matching unit 10 matches the voltage and current signals input to the electronic wattmeter 1, and the A / D converter 11 converts the voltage and current signals matched by the matching unit 10 into digital data. .

The state receiving unit 12 receives an operating state of the breaker 220 or the protection relay 230 and provides them to the determination unit 14, respectively.

The sample comparison unit 13 generates the magnitude (waveform fluctuation information) of one cycle of the difference between the full cycle sample and the current cycle sample. When the waveform fluctuation information of the current cycle is larger than the pickup setting for the fluctuation information, In order to determine the waveform fluctuation status of the system, the waveform fluctuation information and the sample waveform are transmitted to the determination unit 14.

That is, the sample comparison unit 13 of the present invention substitutes the sample difference obtained by subtracting the full cycle sample from the current cycle sample into the following equation representing the root mean square (RMS), and calculates the shake information.

In this case, f (t) is a sample difference obtained by subtracting a full period sample from a current period sample, and T is a period.

3A and 3B are exemplary views for explaining the difference between the previous period sample and the current period sample. In general, when the distribution system does not have a large change, the sample difference between the full-cycle current waveform and the current-cycle current waveform is not large as shown in FIG. 3A, and the waveform fluctuation information calculated using Equation 1 is smaller than the waveform fluctuation pickup setting. Is output.

However, in the case of FIG. 3B, the sample difference between the full-cycle current waveform and the current-cycle current waveform is large, and the waveform fluctuation information calculated from Equation 1 is larger than the waveform fluctuation pick-up setting. The waveform fluctuation information is transmitted to the determination unit 14.

That is, the fluctuation situation of the system described in the present invention is a state in which the breaker 220 does not operate due to the fluctuation situation, and the magnitude of the fault current is small or the duration does not satisfy the operating conditions of the protection relay 230. Say.

In order to distinguish this, the determination unit 14 of the present invention is classified into a system fluctuation situation, a circuit breaker operation situation, a system failure situation, and an inrush current situation, and the upper system through the communication unit 16 only when the system fluctuation situation. To 300.

The current phase comparison unit 15 generates a current phase difference by comparing the full cycle current phase with the current cycle current phase on the basis of the voltage, and the phase fluctuation situation when the phase change is more than the phase fluctuation pickup setting only in one phase. The phase fluctuation information is transmitted to the determination unit 14 so as to be determined. In general, when the phase of the current input to the electricity meter changes, the three phases are collectively changed. In the case of phase fluctuations in which only a single phase changes in phase, a high resistance ground fault is expected and the phase fluctuation situation information is transmitted to an upper system. Is to provide information to make a comprehensive judgment.

The determination unit 14 inputs the wave form fluctuation information or the phase fluctuation information of the system provided by the sample comparator 13 and the current phase comparator 15 to the state in which the protection relay 230 is operated or the breaker is put in a normal system operation. It determines whether or not it has occurred in the opening process, and generates information for delivery to the host system.

The communication unit 16 transmits the information generated by the determination unit 14 to the upper system 300 through the network, and the storage unit 17 stores the information generated by the determination unit 14, while the power meter 1 Save the unique power information. The display unit 18 is disposed in front of the wattmeter 1 and may display power information of the wattmeter 1. In addition, the RTC unit 19 is responsible for managing the time of the electricity meter (1).

In the description of the present invention, a case in which the sample comparison unit 13, the determination unit 14 and the current phase comparison unit 15 are configured separately will be described, but is integrated as one component of the control unit 20. It will be apparent to those skilled in the art that the present invention may be operated.

That is, the sample comparison unit 13 generates waveform fluctuation information, and when the current cycle waveform fluctuation information is larger than the waveform fluctuation pickup setting, it is notified to the judging unit 14 to determine whether or not the judgment part 14 is in a waveform fluctuation situation. Although described as a determination, this may be performed by the control unit 20 integrally. In addition, the phase current comparison unit 15 generates a current phase difference, and when the current phase difference is larger than the phase swing pickup setting, it is notified to the determination unit 14 to determine whether the determination unit 14 is in a phase fluctuation situation. Although described, this may be performed by the control unit 20 integrally. This relationship is the same in the following description.

The present invention is for monitoring the instantaneous mixing of a distribution system with a short cycle of fault current and a high resistance ground fault where the magnitude of the fault current is insufficient. Hereinafter, the operation of the electricity meter of the present invention will be described.

4 is a flowchart illustrating an example of a distribution system monitoring method according to an embodiment of the present invention, wherein the determination unit 14 determines the distribution system using waveform fluctuation information using a difference of a sample generated by the sample comparing unit 13. This is to determine the waveform fluctuation situation.

As shown in the figure, the distribution system monitoring method of the electricity meter 1 of the present invention, the sample comparison unit 13 is the magnitude of the sum of one cycle of the sample difference of the full-cycle sample from the current cycle sample (RMS (Equation 1) ) Is generated as waveform shake information (S41).

At this time, the sample comparing unit 13 first compares the waveform shake pick-up setting for the current cycle with the waveform shake information (S42). As a result of the comparison in S42, when the waveform fluctuation information of the current cycle is not larger than the waveform fluctuation pickup setting, the determination unit 14 checks whether the fluctuation experience information is set (S51). If the fluctuation experience information is not set as a result of checking in S51, the current sample is stored as a full cycle sample for the next cycle and returned (S45).

As a result of checking in S51, when the fluctuation experience information is set, the judging section 14 compares the current cycle current RMS (the magnitude of one cycle sum of the current cycle samples) with the fault current pickup setting (S52). As a result of the comparison in S52, when the current cycle current RMS is larger than the fault current pickup setting, the current sample is stored as a full cycle sample for the next cycle and returned (S45). However, as a result of the comparison of S52, when the current cycle current RMS is not larger than the fault current pickup setting, the fluctuation experience information is released (S53), and the determination unit 14 receives the information input through the state receiving unit 12. In operation S54, it is checked whether the breaker 220 operates.

As a result of checking in S54, when the circuit breaker 220 is operated, that is, when the circuit breaker 220 cuts off the circuit, the current sample is stored as a full cycle sample for the next cycle and returned (S45). However, when the breaker 220 does not operate, that is, when the breaker 220 does not cut off the circuit, it is determined that the waveform is in a disturbance state (S55), and the current is transmitted through the communication unit 16. The fluctuation information of the period and the sample waveform are transmitted to the upper system 300. Thereafter, the current cycle samples are stored as full cycle samples for the next cycle and returned (S45). In this case, when it is determined that the waveform shake situation in S55, the waveform shake information and the sample waveform may be stored in the storage unit 17, and the display unit 18 may notify the user that the waveform shake situation has occurred (not shown). ).

As a result of the comparison in S42, when the waveform fluctuation information of the current cycle is larger than the waveform fluctuation pickup setting, it is checked whether or not the breaker 220 is operating by using the information input through the state receiver 12 (S43). . As a result of checking in S43, when the breaker 220 is operating, the current sample is stored as a full cycle sample for the next cycle and returned (S45). When the breaker 220 does not operate as a result of checking in S43, the waveform fluctuation information of the entire cycle and the waveform fluctuation information of the current cycle are compared (S46).

As a result of the comparison in S46, when the full period waveform fluctuation information is not smaller than the current period waveform fluctuation information, the current sample is stored as the full period sample for the next period and returned (S45). As a result of the comparison in S46, if the full period waveform fluctuation information is smaller than the current period waveform fluctuation information, it is checked whether the full period current RMS is zero (S47).

As a result of checking in S47, when the full cycle current RMS is 0, it is determined as the inrush current situation and the current sample is stored as the full cycle sample for the next cycle and returned (S45). As a result of checking in S47, when the full cycle current RMS is not 0, the current cycle current RMS is compared with the fault current pickup setting (S48).

As a result of the comparison in S48, when the current cycle current RMS is larger than the fault current pickup setting, the fluctuation experience information is set (S44), and the current sample is stored as a full cycle sample for the next cycle and returned (S45). However, as a result of the comparison in S48, when the current cycle current RMS is not larger than the fault current pickup setting, it is checked whether the waveform fluctuation information has occurred in a single phase (S49).

As a result of checking in S49, when the fluctuation information occurs in two-phase or three phases, the current sample is stored as a full-cycle sample for the next cycle and returned (S45). However, if the waveform fluctuation information occurs in a single phase as a result of checking in S49, it is expected to be a high resistance ground fault (S50), and the single phase waveform fluctuation information and the waveform are transmitted through the communication unit 16 to predict the high resistance ground fault. It provides the upper system 300 that the shaking information has occurred. In this case, when the single-phase waveform fluctuation information is determined in S50, the current phase, the waveform fluctuation information, and the sample waveform are stored in the storage unit 17, and the single phase waveform fluctuation information expected to be a high resistance ground fault to the user through the display unit 18. It can be informed that a has occurred (not shown).

Thereafter, the current sample is stored as a full cycle sample for the next cycle and returned (S45).

In the description of FIG. 4, each confirmation and comparison is described as being sequential, but the order of confirmation and comparison is not limited to the ones listed therein, and the order may be changed.

FIG. 5 is a flowchart illustrating another example of a distribution system monitoring method according to an embodiment of the present invention, wherein the determination unit 14 is predicted to have a high resistance ground by using a phase difference of the current generated by the current phase comparison unit 15. It shows judging phase fluctuation situation.

As shown in the figure, in the distribution system monitoring method of the electricity meter 1 of the present invention, the current phase comparison unit 15 compares the current cycle current phase on the basis of the voltage with the full cycle current phase, and compares the current phase difference. It generates (S61).

At this time, the current phase comparison unit 15 compares the current cycle current phase difference with the phase swing pickup setting for the current phase (S62). As a result of the comparison in S62, when the current phase difference of the current cycle is not larger than the phase swing pickup setting, the current current phase is stored as the full cycle current phase and returned (S68). As a result of the comparison of S62, when the current phase difference of the current cycle is larger than the phase swing pickup setting, the determination unit 14 checks whether or not the breaker 220 is operated by using the information input through the state receiving unit 12. (S63).

As a result of checking in S63, when the breaker 220 is operating, the current current phase is stored as the full cycle current phase and returned (S68). When the breaker 220 does not operate as a result of checking in S63, it is checked whether the full-cycle current RMS is 0 (S64).

As a result of checking in S64, when the full cycle current RMS is 0, it is determined as the inrush current situation, and the current current phase is stored as the full cycle current phase and returned (S68). As a result of checking in S64, when the full cycle current RMS is not 0, the current cycle current RMS is compared with the fault current pickup setting (S65).

As a result of the comparison in S65, when the current cycle current RMS is larger than the fault current pickup setting, the current current phase is stored as the full cycle current phase and returned (S68). However, as a result of the comparison of S65, when the current cycle current RMS is not larger than the fault current pickup setting, it is checked whether a phase change has occurred in a single phase (S66).

As a result of checking in S66, when a phase change occurs in an abnormal or three phase, the current current phase is stored as a full cycle current phase and returned (S68). However, if the phase change occurs in a single phase as a result of checking in S66, it is expected to be a high resistance ground (S67), and transmits the current phase, fluctuation information, and waveforms, which are phase fluctuation situation information, through the communication unit 16, thereby causing a high resistance ground fault. It provides to the upper system 300 that the expected phase fluctuation situation occurred. At this time, when it is determined that the phase fluctuation situation in S67, the current phase, fluctuation information and waveforms are stored in the storage unit 17, and the phase fluctuation situation expected to be a high resistance ground fault has occurred to the user through the display unit 18. May be informed (not shown).

Thereafter, the current current phase is stored as the full-cycle current phase and returned (S68).

In the description of FIG. 5, each confirmation and comparison is described as being sequential, but the order of confirmation and comparison is not limited to the ones listed therein, and the order may be changed.

As described above, according to one embodiment of the present invention, in a fluctuation situation of a system in which a protection relay cannot operate due to a short or small failure duration, one period for the difference between the full-cycle sample and the current-cycle sample of the electricity meter If the magnitude of the sum is more than the waveform shake pick-up setting, it is judged that the magnitude or shape of the current has changed drastically, and the waveform at that time is transmitted to the host system through communication to determine the system's waveform fluctuations, thereby operating the distribution system. The efficiency can be improved.

In addition, if the impedance of the ground fault occurrence point of the distribution line is high, the impedance of the ground line changes, which causes the current phase of the ground line to change abruptly. It is possible to increase the operation efficiency of the distribution system by providing the phase fluctuation generation information to the upper system through communication by determining the phase fluctuation situation expected by the ground fault.

Therefore, according to the present invention, damage to the distribution system or pedestrians can be reduced.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. Accordingly, the true scope of the present invention should be determined by the following claims.

1: electronic meter 220: breaker
230: protective relay 330: host system
10: matching unit 11: A / D conversion unit
12: Status receiver 13: Sample comparison
14: determination unit 15: current phase comparison unit
16: communication unit 17: storage unit
18: display unit 19: RTC unit
20: control unit

Claims (22)

Receiving unit for receiving the operating state of the circuit breaker of the distribution system;
Generates the magnitude (waveform fluctuation information) of one cycle for the difference between the full-cycle sample and the current-cycle sample, and determines the current-cycle waveform fluctuation information and the sample waveform when the current-cycle waveform fluctuation information is larger than the waveform fluctuation pickup setting. A first comparison unit to provide a wealth; And
And a determination unit for determining waveform fluctuation conditions or single phase waveform fluctuation conditions from the waveform fluctuation information received from the first comparator and the operation state of the circuit breaker.
The method of claim 1,
The second comparison unit which provides the current phase, the current cycle fluctuation information, and the sample waveform to the determination unit when the current phase difference is greater than the phase swing pickup setting by comparing the current cycle current phase with the current cycle current phase based on voltage. Including,
And the determination unit determines the phase fluctuation expected from the current phase difference received from the second comparing unit and the operation state of the circuit breaker.
The electronic watt-hour meter according to claim 1 or 2, wherein the first comparison unit generates the waveform fluctuation information by the following RMS equation.

(Where f (t) is the difference between the current cycle samples and the full cycle samples minus T is the period)
The method of claim 1 or 2, wherein the determination unit,
An electronic wattmeter for judging the waveform fluctuations when the current RMS of the current cycle is greater than the fault current pickup setting and the breaker is closed.
The method of claim 1 or 2, wherein the determination unit,
The waveform fluctuation information of the current cycle is larger than the waveform shake pickup setting, the breaker closes, the waveform fluctuation information of the current cycle is larger than the waveform fluctuation information of the previous cycle, no inrush current occurs, and the current cycle current RMS is the fault current pickup. An electronic power meter, which is smaller than the setting and judges the single-phase waveform fluctuation situation when the waveform fluctuation information occurs in a single phase.
3. The apparatus of claim 2,
If the current phase difference is larger than the phase swing pickup setting, the breaker closes, no inrush current occurs, the current cycle current RMS is smaller than the fault current pickup setting, and the phase change occurs in a single phase, Electronic meter.
The method according to claim 1 or 2,
Matching unit for matching the applied voltage or current; And
An electronic power meter further comprises a conversion unit for converting the analog signal passing through the matching unit into digital data.
The method of claim 2,
A storage unit which stores information of the waveform fluctuation situation, the single phase waveform fluctuation condition and the phase fluctuation condition; And
And a communication unit for transmitting the waveform fluctuation situation, the single phase waveform fluctuation situation, and the information of the phase fluctuation condition to an upper system.
The method of claim 2,
And a display unit which displays information of the waveform fluctuation situation, the single phase waveform fluctuation condition, and the phase fluctuation condition to a user.
The method of claim 1,
A storage unit which stores information of the waveform fluctuation conditions and the single phase waveform fluctuation conditions; And
And a communication unit for transmitting the waveform fluctuation situation and the single-phase waveform fluctuation situation information to an upper system.
The method of claim 1,
And a display unit for displaying the waveform fluctuation conditions and the single phase waveform fluctuation conditions to a user.
(a) generating, as waveform fluctuation information, the magnitude of the sum of one cycle for the difference between the full cycle sample and the current cycle sample;
(b) comparing the current cycle current RMS with the fault current pickup setting;
(c) confirming the operation of the breaker; And
(d) A distribution system monitoring method comprising the step of determining the waveform fluctuation situation.
The method of claim 12, wherein step (d)
The distribution system monitoring method which judges that it is the waveform fluctuation situation, when the current period current RMS is larger than the fault current pick-up setting, and the said breaker does not operate.
The method of claim 12,
(e) checking the operation of the circuit breaker between the steps (a) and (b) when the waveform fluctuation information of the current period is larger than the waveform fluctuation pickup setting;
(f) comparing the entire period waveform fluctuation information with the current period waveform fluctuation information;
(g) checking whether an inrush current has occurred;
(h) comparing the current cycle current RMS with the fault current pickup setting;
(i) confirming whether waveform fluctuation information occurred in a single phase; And
(j) A distribution system monitoring method further comprising the step of determining the single-phase waveform fluctuations.
The method of claim 14, wherein step (j),
The single-phase waveform when the breaker is closed, the full cycle waveform fluctuation information is smaller than the current cycle waveform fluctuation information, no inrush current is generated, the current cycle current RMS is smaller than the fault current pickup setting, and the waveform fluctuation information is generated in single phase. Distribution system monitoring method judged to be fluctuating.
The method of claim 12,
(k) after the step (d), further comprising the step of storing the fluctuation information and the sample waveform of the waveform fluctuation situation, and transmitting it to the host system.
15. The method of claim 14,
(l) after the step (j), further comprising the step of storing the fluctuation information and sample waveform of the single-phase waveform fluctuation situation, and transmitting it to the host system.
The method of claim 12,
(m) after step (d), further comprising the step of storing the current sample as a full cycle sample for the next cycle.
(a) comparing the current cycle current phase based on the voltage with the full cycle current phase to generate a current phase difference;
(b) checking the operation of the circuit breaker when the current phase difference is greater than the set value;
(c) checking whether an inrush current has occurred;
(d) comparing the current cycle current RMS with the fault current pickup setting;
(e) checking whether the phase change occurred in a single phase; And
(f) A distribution system monitoring method comprising determining a phase fluctuation situation.
The method of claim 19, wherein the step (f),
And the circuit breaker is closed, the inrush current is not generated, the current cycle current RMS is larger than the fault current pickup setting, and the phase shift condition is judged as the phase fluctuation condition.
21. The method of claim 20,
(g) after the step (f), further comprising the step of storing the current phase, the fluctuation information and the sample waveform of the phase fluctuation situation, and transmitting it to a higher system.
21. The method of claim 20,
(h) after the step (f), further comprising the step of storing the current current phase as the full-cycle current phase.

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