KR100941401B1 - Real-time switching method on a reserve power supply condition for an auto-switching apparatus based on a real-time power flow - Google Patents

Abstract

PURPOSE: A real-time switching method of a real-time power flow based automatic switching device is provided to control a load by supplying the reserve power in an outage of a power supply device. CONSTITUTION: A real-time use power of an overall load is summed(S10). The sum of the real-time use power of the overall load is compared with the reserve power contract capacity(S14). If the sum of the real-time use power of the overall load is larger than the reserve power contract capacity, the reserve power contract capacity is compared with the valve obtained by subtracting the real-time use power of the load with the lowest priority from the sum of the real-time use power of the overall load(S16). If the valve obtained by subtracting the real-time use power of the load with the lowest priority from the sum of the real-time use power of the overall load is larger than the reserve power contract capacity, a first trip command is provided to the circuit breaker of the load(S20).

Description

Real-time switching method on a reserve power supply condition for an auto-switching apparatus based on a real-time power flow}

The present invention relates to a real-time power flow-based automatic switching device, and more specifically, to control the load in the reserve power supply state to maintain the reserve power reserve capacity or reserve power capacity smaller than the regular power contract capacity or the regular power equipment capacity It relates to a real-time transfer method.

Buildings and factories require water distribution facilities to receive power, and the water distribution facilities include breakers, switchgear, and transformers.

Water distribution equipment needs technology to switch in consideration of load power for effective operation.In this regard, Korea Utility Model Registration No. 20-332957 (Name: Automatic Load Switching Device for Load Power) and Korea Utility Model Registration No. 20-381066 (Name: digital switchgear switch control) has been disclosed.

Korea Utility Model Registration No. 20-332957 discloses a technology that automatically supplies power to the load by automatically switching the load power to the emergency generator power supply when commercial power is not supplied by a power failure, and Korea Utility Model Registration No. 20-381066 Disclosed is a technique for integrating and controlling various circuit breakers necessary for a switchgear.

In general, power supply requires a constant power supply facility for supplying a constant power and a reserve power supply facility for receiving a reserve power to replace it.

The above-mentioned reserve power can be used in a situation such as repairing a facility for supplying continuous power or failure or inspection in which the regular power is not normally supplied. The breaker is activated.

The reserve power contract capacity or reserve power supply equipment is required to be 100% of the constant power contract capacity or the constant power supply equipment. In this case, the constant power contract capacity and the reserve power contract capacity or the capacity of the constant power supply equipment and the reserve power supply equipment. Since each is the same, it is not necessary to adjust the switching timing by examining the power currents. That is, since the capacity necessary to supply the reserve power is sufficient, the transfer can be easily performed without the need to examine the power current at the time of the transfer.

However, when the preliminary power supply facility is installed at the same level as the regular power supply facility as in the general method as described above, the initial facility cost for securing the reserve power capacity is required as the regular power supply facility. Therefore, the cost burden on the equipment installed for power supply is high.

In addition, when the backup power supply facility is designed to have the same capacity as the regular power supply facility, the backup power supply facility can be operated at no load while the regular power supply facility is in operation. Therefore, power loss may occur when the preliminary power supply facility is operated at no load. In this case, problems of social perspective (eg, green energy policy) can be caused.

In addition, the power user should contract for a power supply a reserve power contract capacity of the same capacity as the regular power contract capacity. Therefore, there is a problem that the power user must spend excessively on the reserve power contract capacity.

In order to solve the above problems, the real-time power is supplied to the reserve power supply capacity or reserve power while supplying the reserve power to the reserve power supply capacity having a capacity smaller than the regular power contract capacity or a capacity smaller than the regular power supply equipment. It is desirable to present a way to effectively control the load in case of exceeding the plant capacity.

In order to solve the above-mentioned problems, the present invention provides a real-time power flow-based automatic that can effectively supply the reserve power with a reserve power contract capacity of less than the regular power contract capacity when the supply of the reserve power is required by the power failure of the constant power supply facility. It is an object of the present invention to provide a real-time switching method applied to a standby power supply state of a switching device.

The real-time switching method applied to the preliminary power supply state of the real-time power current-based automatic switching device according to the present invention, the first step of summing the total real-time power used for the load; A second step of determining whether the sum of the total real-time power used for the loads is greater than the reserve power capacity; A third step of determining whether a value obtained by subtracting the real-time power usage for the load having the lowest priority from the sum of the total real-time power usage is greater than the reserve power capacity if the sum of the real-time power usage is greater than the reserve power capacity; ; A fourth step of immediately generating a first trip command to the circuit breaker of the currently selected load when a value obtained by subtracting the real time power usage for the load having the lowest priority from the sum of the total real time power usage is greater than the reserve power contract capacity; If the sum of the real-time power consumption minus the real-time power usage for the load having the lowest priority is less than or equal to the reserve power contract capacity, the difference between the reserve power contract capacity and the real-time power usage by the loads currently turned on A fifth step of generating a blocking time by applying a predetermined cumulative integration time and generating the second trip command at the blocking time; A sixth step of substituting a value obtained by subtracting a real-time power usage for the currently selected load from the real-time power usage for the entire load as the real-time power usage for the current total load; After the second trip command is generated, it is determined whether a value obtained by subtracting the real-time power usage for the subordinate load from the real-time power usage for the current total load is greater than the reserve power contract capacity, and according to the fourth step to the above. A seventh step of selectively performing the sixth step; And an eighth step of sequentially performing the seventh step on subordinate loads.

The blocking time in the fifth step,

Where t is the interruption time, S is the reserve power contract capacity, P is the total real-time power usage, M is the preset cumulative integration time, and L1 is the lowest load with the lowest priority. This is the real time power usage for.

In the seventh and eighth steps, the blocking time is

Where t is the cutoff time, S is the reserve power contract capacity, P1 is the total real-time power usage excluding the previously selected loads, M is the preset cumulative integration time, and L2 is the Real time power consumption.

On the other hand, in the fifth step, the seventh step and the eighth step, the interruption time is an accumulated value of the difference between the real-time power used and the reserve power contract capacity until the interruption time and the cumulative accumulation preset from the interruption time. By time, the integrated value of the difference between the reserve power capacity and the real-time power consumption may be determined to be the same.

In addition, the reserve power contracted capacity may be set to 40% to 60% of the regular power contracted capacity, preferably, the reserve power contracted capacity may be set to 50% of the regular power contracted capacity.

According to the present invention, the regular power supply facility can normally supply the reserve power with a capacity smaller than the reserve power contract capacity in response to a power failure, or the reserve power supply facility can be designed and operated with a smaller capacity than the regular power supply facility. Can be.

In addition, the present invention can smoothly supply power with a reserve power contract capacity smaller than the regular power contract capacity by applying a real-time switching algorithm in synchronization with the switching to replace the constant power supply to the reserve power from the non-important load.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments are provided to those skilled in the art to fully understand the present invention, and may be modified in various forms, and the scope of the present invention is limited to the embodiments described below. It doesn't happen. Like numbers refer to like elements in the figures.

In the present invention, the constant power contract capacity refers to the constant power of the maximum capacity that can be used under the contract, and the reserve power contract capacity refers to the reserve power of the maximum capacity that can be used under the contract, and the constant supply equipment refers to a facility that supplies the constant power. In other words, the capacity of the regular supply equipment refers to the maximum power capacity that can be supplied to the supply equipment at all times, and the provision of supply equipment refers to the equipment to supply the reserve power. The reserve current capacity refers to the flow of active and reactive power according to the power demand. In the present invention, the real-time power is cumulatively accumulated according to the real-time power current calculation.

Further, the reserve power contracting capacity set in the embodiment of the present invention may be set to 40% to 60% of the regular power contracting capacity, preferably, the reserve power contracting capacity may be set to 50% of the regular power contracting capacity. have.

In addition, the equipment capacity of the reserve power supply equipment set in the embodiment of the present invention may be set to 40% to 60% of the equipment capacity of the constant power supply equipment, preferably the equipment capacity of the reserve power supply equipment is always power It can be set to 50% of the installed capacity of the supply equipment.

1 is a circuit diagram illustrating an embodiment of a real-time power current-based automatic switching device according to the present invention.

Referring to FIG. 1, the continuous power supply facility 10 and the reserve power supply facility 12 are connected to an automatic load switchgear 20, and the automatic load switchgear 20 is a constant power supply facility 10 or a reserve. It is connected to any one of the power supply facilities 12 to supply power to the loads LD1, LD2 ... LDn. Here, in the embodiment, the preliminary power supply facility 12 is equipped with 50% of the capacity of the regular power supply facility 10 as an example. According to the embodiment, the reserve power contract capacity is also set to 50% of the regular power contract capacity according to the capacity of the reserve power supply facility 12.

The automatic load switching circuit 20 supplies power to each of the loads LD1, LD2 ... LDn in common through the circuit breakers Tr1, Tr2 ... Trn, and each circuit breaker (Tr1, Tr2 ... Trn). ) Is configured one-to-one at the leading end of each of the loads LD1, LD2 ... LDn.

In case of power failure due to failure or check in the power supply facility 10 at all times, the real-time power current-based automatic switching device according to the present invention is connected to the automatic load switching switch 20 to receive power from the preliminary power supply facility (12) The state is transferred.

In addition, the real-time power flow-based automatic switching device according to the present invention is provided with a load switching device 30 when the automatic load switching switch 20 is switched to supply the reserve power load switching device 30 in synchronization with this And to control the operation.

The load switching device 30 controls the switching of the breakers Tr1, Tr2 ... Trn, and has a configuration for collecting real-time power consumption information from each load.

The load switching device 30 previously stores the importance information for each load and controls the operation according to the amount of real-time power used in the state where the automatic load switching switch 20 is switched.

More specifically, if the real-time power consumption is less than the reserve power contracted capacity, the load switching device 30 is operated below the reserve power contracted capacity by maintaining the switching state until the return to normal power without interrupting the load.

On the contrary, when the real-time power consumption exceeds the reserve power contract capacity, the load switching device 30 drives the real-time transfer algorithm so that the cumulative accumulation amount by the real-time power current calculation does not exceed the reserve power contract capacity. Operate below the reserve power capacity by breaking the circuit breaker sequentially.

In this case, the cumulative accumulation amount refers to a value obtained by dividing real-time usage by a cumulative time for a predetermined period, and real-time power consumption P is a usage power sum of the total load usage as shown in Equation 1 below.

Where Ln is the individual real-time power consumption of the loads LD1, LD2 ... LDn, and the importance of the load is defined in the order of LD1 <LD2 ... <LDn.

The above-described real-time switching algorithm will be described later with reference to FIG. 2.

The automatic load switchgear 20 provides a signal TS having a transfer signal / SEL due to the power failure of the power supply facility 10 and information corresponding to that of the automatic load switchgear 20 has been switched. The SEL and the signal TS are logically multiplied by the AND gate 22 to be provided to the load switching device 30, and the load switching device 30 is an output signal of the AND gate 22. Real-time transfer algorithm is performed by detecting that power is being supplied.

As described above, when the transfer is performed in the automatic load transfer switch 20 and the / SEL and the facility internal signal TS, which are information on the transfer, are transferred to the load transfer device 30, the load transfer device 30 first performs initialization. The real-time power P (P = L1 + L2 ... Ln) of the total load is added (S10).

If the automatic load transfer switch 20 is opened and closed (S12), it is determined whether the real-time power P is greater than the reserve power contracted power S (S14).

If the real-time power used P is less than the reserve power contracted capacity S, the load switching device 30 does not take any action.

If the real-time power used P is greater than the reserve power contracted capacity S, the load switching device 30 proceeds with the subsequent procedure for controlling the load.

First, a cutoff time for a trip command for switching the load LD1 having the least importance is calculated. In order to calculate the interruption time of the load LD1, the relationship between the real time power P of the full load minus the real time power L1 of the load LD1 and the reserve power contract capacity S is determined.

If the value obtained by subtracting the real time power L1 of the load LD1 from the real time power consumption P of the full load is still greater than the reserve power contracted capacity S, the interruption time t = 0 is set and an immediate trip command is provided (S18). The connected breaker Tr1 is opened to cut off the power to the load LD1.

If the value obtained by subtracting the real-time power L1 of the load LD1 from the real-time power consumption P of the full load is less than or equal to the reserve power contracted capacity S, the breaking time t is set according to Equation 2 below, and the trip command is In operation S20, the breaker Tr1 is opened at the time when the trip command is provided to cut off the power supplied to the load LD1.

Here, M is a preset cumulative integration time, can be set by the experimental value, 15 minutes can be applied for the embodiment.

The above-described blocking time t is for adjusting the cumulative accumulation amount used during the cumulative integration time to the reserve power contract capacity.

That is, if the value of subtracting the real time power L1 of the load LD1 from the real time power P of the full load is still greater than the reserve power contracted capacity S, set the breaking time t = 0 and immediately determine the trip command of the load LD2 having the next lowest importance. do.

If the value obtained by subtracting the real time power L1 of the load LD1 from the real time power P of the full load is less than the reserve power contracted capacity S, the current real time power is maintained from t = 0 to the cutoff time t. Shut off LD1. Then, the real-time used power P becomes an integrated value from t time until the load L1 consumes power and from t time to 15 minutes when the load L1 does not consume power equal to the reserve power contracted capacity S.

That is, as shown in FIG. 3, the real-time power P may be changed based on the cutoff time t, and the hatched portions on both sides of the t are the same as the integrated values.

If power is not supplied to the load LD1 according to the trip commands of steps S18 and S20 described above, the real time power is replaced by P1 = P-L1. (S22) Here, P1 is the real time use of the entire load excluding the interrupted load LD1. Power.

Thereafter, it is determined whether the real-time used power P1 by the loads which are not interrupted at present is larger than the reserve power contracted capacity S (S24).

If the real time power P1 is less than the reserve power contracted capacity S, the load switching device 30 does not take any action.

If real-time power P1 is greater than the reserve power contract capacity S, the load switching device 30 proceeds to the lower procedure for controlling the load.

First, a cutoff time for a trip command for switching the load LD2 of low importance is calculated. In order to calculate the interruption time of the load LD2, it is determined the relationship between the real time power P1 of the current full load minus the real time power L2 of the load LD2 and the reserve power contract capacity S. (S26)

If the real time power P1 of the current load minus the real time power L2 of the load LD2 is still greater than the reserve power contracted capacity S, the breaking time t = 0 is set and an immediate trip command is provided. (S28) Then, the load LD2 The breaker Tr2 connected to it opens, breaking the power to the load LD2.

If the value obtained by subtracting the real-time power L1 of the load LD2 from the real-time power consumption P1 of the full load is less than or equal to the reserve power contracted capacity S, the breaking time t is set according to Equation 3 below. In operation S30, the breaker Tr2 is opened at the time when the trip command is provided, and the power supplied to the load LD2 is cut off.

If power is not supplied to the load LD2 according to the trip commands of steps S28 and S30 described above, the real time power is replaced by P2 = P1-L2. (S32) Here, P2 is the total load excluding the interrupted loads LD1 and L2. Real time power consumption.

As described above, the subsequent process is performed to sequentially generate trip commands in order of loads of low importance until the real-time power of the current full load satisfies the condition below the reserve power contract capacity S. (S34)

Meanwhile, FIG. 4 is an embodiment of the present invention in which the reserve power supply facility capacity is smaller than the regular power supply facility capacity in 2 to 3 banks, and is a circuit breaker switching circuit for operating within an overload operation limit of the real-time power current calculation-based water distribution facility. .

4 has a bank including loads LD1 to LD3 and a bank including loads LD4 to LD6.

In the embodiment of Figure 2 NT1, NT2 is a constant transformer and ST is a pre-transformer. 52S1 is a breaker installed at the inlet end side of the constant transformer NT1, 52S2 is a breaker installed at the inlet end side of the constant transformer NT2, and 52SP is a breaker installed at the inlet end side of the preliminary transformer ST. And, 52P1 is a circuit breaker installed on the supply side of the constant transformer NT1, 52P2 is a circuit breaker installed on the supply side of the constant transformer NT2, 52SS is a circuit breaker installed on the supply side of the pre-transformer ST.

A circuit breaker 52T1 and a circuit breaker 52T2 are connected in parallel to a supply terminal of the breaker 52SS, and an input terminal of the breakers R1, R2, and R3 connected to the loads LD1, LD2, and LD3 forming a bank is respectively connected to the supply terminal of the breaker 52T1. Commonly connected, the supply terminal of the circuit breaker 52T2 is commonly connected to the circuit breakers R4, R5, and R36 which are connected to the loads LD4, LD5, and LD6 which form another bank.

In addition, load LD1 to LD6 corresponding to each of the circuit breakers R1 to R6 are independently connected.

The embodiment of FIG. 4 illustrates that the load switching device 40 is configured in one bank to explain the switching of the load, and the load switching device 40 is based on the apparent power of each load, i.e., the real-time working power. It is configured to output the trip commands Tr1 to Tr3 for switching the breakers R1 to R3 for the loads LD1 to LD3 of the corresponding bank while collecting the information LVA1, KVA2, KVA3.

Here, the circuit breakers 52P1, 52T1, 52SP, and 52SS correspond to the switchgear which selects any one of the constant transformer NT1 and the preliminary transformer ST to supply the normal power or the reserve power to the loads LD1 to LD3 through the breakers R1 to R3 in common. do. This switchgear can be understood as a configuration corresponding to the automatic load switching switch of FIG.

In addition, the load switching device 40 may use the switching information of the breakers included in the switchgear as the information for determining that the switchgear supplies the reserve power, and the switchgear determines that the switchgear supplies the reserve power. As the information, the transfer signal / SEL by the power failure of the constant voltage transformer may be further used.

 In the above-described configuration, when the constant voltage transformer NT1 is out of power, the load switching device 40 compares the capacity of the preliminary transformer ST with the sum of the reserve power contract capacities of the loads LD1 to LD3.

If the capacity of the pre-transformer ST is equal to or greater than the sum of the reserve power contract capacities of the constant-transformer NT1, the breakers 52SP, 52SS, and 52T1 are closed to load the pre-power using the pre-transformer ST to the constant-transformer NT1. It supplies to LD1 thru LD3.

Then, if the capacity of the pre-transformer ST is less than the preliminary power contract capacity of the loads LD1 to LD3 dependent on the constant transformer NT1, the breakers 52SP, 52SS, and 52T1 are closed to load the preliminary power using the pre-transformer ST to the constant transformer NT1. The overload operation algorithm is driven while being supplied to LD1 to LD3 so as to be within the overload operation limit of the preliminary transformer ST by real-time power current operation.

The above-described overload operation algorithm will be described later with reference to FIG. 5, and the overload operation algorithm is operated with reference to the overload coefficient table of Table 1 below.

Driving time Overload Factor: K No load (K1) 100% load (K3) 5 minutes 2.0 1.4 30 minutes 1.5 1.2 1 hours 1.31 1.11 2 hours 1.21 1.1 4 hours 1.15 1.05 8 hours 1.08 1.01

Meanwhile, an overload driving algorithm applied to the embodiment of FIG. 4 will be described with reference to FIG. 5.

Each circuit breaker included in the switchgear provides information determined to supply the reserve power, and the information determined to supply the reserve power is provided to the load switching device 40 in the same manner as in the embodiment of FIG. The load switching device 40 detects the state of supplying the reserve power as information determined to supply the reserve power. For reference, a gate configuration for providing information determined to supply spare power to the load switching device 40 has been omitted.

As described above, when each breaker included in the switchgear is switched to a state for supplying spare power, the load switching device 40 executes an overload operation algorithm until returning to supplying constant power.

The load switching device 40 performs an overload operation algorithm that determines the overload operation state based on the apparent power of the loads, and generates trip commands sequentially from the load having low importance.

To this end, the load switching device 40 performs an initialization step (S50) for obtaining the sum A (A = AL1 + AL2 + AL3) of the apparent powers for the entire load, and if the breakers of the switchgear are switched (S52), It is determined whether the installed capacity T 'of the preliminary transformer ST is equal to or less than the sum A of the apparent powers for all the loads (S54).

Here, the actual capacity T 'of the pre-transformer ST may be defined by Equation 4 below.

Here, T is the installed capacity of the pre-transformer ST (KVA), KVA is a unit for displaying the apparent power.

As described above, the actual capacity T 'of the preliminary transformer ST may vary according to environmental factors.

If the actual capacity T 'of the preliminary transformer ST in step S54 is greater than the sum of the apparent powers for the entire load, the load switching device 40 does not take any action.

Alternatively, in step S54, if the actual capacity T 'of the preliminary transformer ST is equal to or less than the sum of the apparent powers for all the loads, the breaking time t is calculated and a trip command for the load LD1 having the least importance is executed.

The interruption time t for the trip command for the load LD1 may be calculated as shown in Equation 5 below.

Where K1 is the overload factor for the no load of the load LD1.

The overload has a capacity margin of 1% of the capacity when the ambient temperature drops to 1 ℃ based on 30 ℃, and a 1% capacity of the capacity when the temperature rise relative to the winding temperature is 1 ℃ below the standard value. The overload coefficients (K) for each load can be divided into one for no load (K1) and one for 100% load (K3), and the overload coefficients for no load K1 and 100% load depending on the load condition. The overload factor K3 has a difference. The overload coefficient K may be prepared as a lockup table according to the experimental value as shown in Table 1, and the overload coefficient K1 for no load forms a curve between t-K1 as shown in FIG. 6 and the overload coefficient K3 for 100% load is A curve between t-K3 is formed as shown in FIG. 7.

On the other hand, the interruption time t for the trip command for the load LD1 may be calculated by the above Equation 5, and the trip command is performed at the calculated interruption time (S56).

When the trip command is executed, since the load LD1 is in the interrupted state, the sum A of the total apparent powers is replaced by A1 excluding the interrupted load LD1 (S58).

Thereafter, if the actual capacity of the preliminary transformer T 'is greater than the sum of the apparent powers of the current loads A1 at the breaking time for the first selected load LD1, the load switching device 40 does not take any action.

However, if the actual capacity of the preliminary transformer T 'is less than or equal to the sum of the apparent powers for the current loads A1 at the cutoff time for the first selected load LD1 (S60), then the trip command for the subordinate load LD2 is calculated at the arithmetic cutoff time t. (S62)

The interruption time for performing the trip command for the subordinate load LD2 may be calculated as in Equation 6.

Where K3 is the overload factor for 100% load of the load LD2.

The overload coefficient for no load is applied to the load LD1 to calculate the breaking time, and applying the overload coefficient for 100% load to the load LD2 means that the load LD1 is applied to the pre-transformer ST at the time of calculating the breaking time for the load LD1. This is because the load LD2 is driven by the pre-transformer ST at the time point before the driving and the break time for the load LD2 is calculated.

 As described above, when the trip command for the subordinate load LD2 is the trip command, since the load LD2 is in the interrupted state, the sum A1 of the total apparent powers is replaced by A2 excluding the blocked loads LD1 and LD2 (S64).

Subsequently, the sequential trip command is executed for the less important load until the actual pre-transformer capacity satisfies a condition that is greater than the sum of the total apparent powers of the currently operating loads (S66).

Here, the cutoff time for the trip command may be calculated by the method of Equation 6 described above.

As described above, the present invention can supply the reserve power with a reserve power contract capacity of a smaller capacity than the regular power contract capacity when switched to supply the reserve power by the power outage of the power supply.

In addition, the present invention can supply the reserve power to a reserve power supply of a smaller capacity than the regular power supply facilities.

In addition, the present invention can smoothly supply the reserve power with a reserve power contract capacity smaller than the regular power contract capacity by cutting off the non-critical load by applying the power current-based real-time switching algorithm.

In addition, the present invention can apply the power current-based overload operation algorithm to cut off the non-critical load to supply the reserve power within the overload operation limit.

As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various deformation | transformation by a person of ordinary skill in the art within the scope of the technical idea of this invention is carried out. This is possible.

1 is a circuit diagram showing an embodiment of a real-time power current-based automatic switching device according to the present invention.

2 is a circuit diagram illustrating an embodiment in accordance with the present invention applied to multiple banks.

3 is a graph representing the amount of integration against the blocking time.

Figure 4 is a flow chart showing a real-time switching algorithm of the real-time power current-based automatic switching device according to the present invention.

5 is a flowchart illustrating an overload operation algorithm of a real-time power current-based automatic switching device according to the present invention.

6 is a K1-t curve showing the overload coefficient of the no-load state of Table 1

7 is a K3-t curve showing the overload coefficient of the overload condition of Table 1

Claims (7)

In the real-time switching method of the real-time power current-based automatic switching device for controlling the backup power supply by switching the circuit breaker of each load by the load switching device in the state of supplying the reserve power to a level lower than the normal power, A first step of summing up the total real-time power used for the loads; A second step of determining whether a sum of the total real-time used power for the loads is greater than a reserve power contract capacity; A third step of determining whether a value obtained by subtracting the real-time power usage for the load having the lowest priority from the sum of the total real-time power usage is greater than the reserve power capacity if the sum of the real-time power usage is greater than the reserve power capacity; ; A fourth step of immediately generating a first trip command to the circuit breaker of the currently selected load when a value obtained by subtracting the real time power usage for the load having the lowest priority from the sum of the total real time power usage is greater than the reserve power contract capacity; If the sum of the real-time power consumption minus the real-time power usage for the load having the lowest priority is less than or equal to the reserve power contract capacity, the difference between the reserve power contract capacity and the real-time power usage by the loads currently turned on A fifth step of generating a breaking time by applying a predetermined cumulative integration time and generating a second trip command to the breaker of the load currently selected at the breaking time; A sixth step of substituting a value obtained by subtracting a real-time power usage for the currently selected load from the real-time power usage for the entire load as the real-time power usage for the current total load; After the second trip command is generated, it is determined whether a value obtained by subtracting the real-time power usage for the subordinate load from the real-time power usage for the current total load is greater than the reserve power contract capacity, and according to the fourth step to the above. A seventh step of selectively performing the sixth step; And And an eighth step of sequentially performing the seventh step with respect to subordinate loads. The method of claim 1, wherein the blocking time in the fifth step,

T is the interruption time, S is the reserve power contract capacity, P is the total real-time power usage, M is the preset cumulative integration time, and L1 is the real-time use for the lowest load with the lowest priority. Real-time switching method of real-time power current based automatic switching device which is electric power. The method of claim 1, wherein the blocking time in the seventh and eighth steps,

T is the cut-off time, S is the reserve power contract capacity, P1 is the total real-time power usage excluding the previously selected loads, M is the preset cumulative integration time, and L2 is the real-time power usage for the subordinate loads. Real-time switching method of automatic real time power switching system based on real time. The method of claim 2 or 3, The M is a real-time switching method of the real-time power current-based automatic switching device is set to 15 minutes. The method of claim 1, wherein in the fifth step, the seventh step and the eighth step, the interruption time is determined from an integrated value of the difference between the real-time used power and the reserve power contract capacity until the interruption time and the interruption time. The real-time switching method of the real-time power current-based automatic switching device is determined so that the integrated value of the difference between the reserve power capacity and the real-time power used by the predetermined cumulative integration time. The method of claim 1, The reserve power contracting capacity is a real-time switching method of the real-time power current flow based automatic switching device is set to 40% to 60% of the regular power contract capacity. The method of claim 6, The real-time power switching method of the real-time power current-based automatic switching device is set to 50% of the regular power contract capacity.

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