JP2001359242A - Power receiving and distributing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To calculate value of purchase power with high accuracy, without having to depend on the volume of the purchase power and keep the purchase power at a constant value. SOLUTION: A potential transformer 16 for instrument and a current transformer 18 for instrument are provided on a receiving circuit 14 for supplying the power of a distribution line 10 to a demand home bus bar 12, and the current transformer 18 for instrument is formed out of a circuit that can adjust current conversion ratio in multiple stages. Power in a power transformer 24 is calculated from the output voltage of the potential transformer 16 for instrument and the output voltage of the current transformer 18 for instrument, the output power of a non-utility generator 28 is controlled based on the calculated power value, and the calculated power and a predetermined power are compared by a current transformer controller 26. If the purchase power exceeds a preset power, 400/5A is selected for the current transformation ratio of the current transformer 18 for instrument. If the calculated power is equal to or less than the predetermined power, 50/5A is selected for the current conversion ratio of the current transformer 18 for instrument. Power value is calculated with high accuracy, even if the purchase power is low, thereby controlling the purchase power to an appropriate value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power receiving and distribution system, and more particularly, to a private power generator which operates a private power generator in parallel with a power purchase system connected to a distribution line, and partially supplies power to a load. The present invention relates to a power receiving and distributing system suitable for controlling the purchased electric power by paying the electric power to the electric machine.

[0002]

2. Description of the Related Art Conventionally, as a power receiving / distributing system, power from a distribution line is supplied to a bus within a customer via a power receiving line, and power generated by a private generator is supplied to a bus within the customer, and a voltage of the power receiving line is supplied. Is detected by the instrument transformer, the current of the power receiving line is detected by the instrument current transformer, and the power is calculated from the detected voltage of the instrument transformer and the detected current of the instrument current transformer. In some cases, the output power of a private generator is controlled so that the purchased power is constant. As a technique related to this kind of technique, for example, a technique described in Japanese Patent Application Laid-Open No. 2-95137 is known.

[0003]

In a conventional power receiving and distribution system, a detected voltage of an instrument transformer and a detected current of an instrument current transformer are input to a power converter in order to keep the purchased power constant. Then, the power is calculated by a power converter, the calculated power is converted to a current value and input to the private power generation facility, and based on the input current value, the output of the private generator is used so that the purchased power is constant. However, because the current transformer for the instrument is configured with a constant current ratio, when the purchased power is small and the current is small, the error of the current transformer for the instrument increases. Accompanying this, the error of the power converter becomes large, so that accurate power cannot be calculated, and the purchased power cannot be maintained at an appropriate value.

An object of the present invention is to provide a power receiving / distributing system and a power receiving / distributing system capable of calculating a value of purchased power with high accuracy and keeping the purchased power at an appropriate value regardless of the magnitude of the purchased power. Is to provide a control method.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a power receiving line for supplying power from a distribution line to a bus within a customer, and a transformer for an instrument for detecting a voltage of the power receiving line. A current transformer for detecting the current of the power receiving line, a power converter for calculating power from a detection voltage of the transformer for the instrument and a detection current of the current transformer for the instrument, and a power converter for the power converter. A power generator for supplying power to the customer's internal bus in accordance with the calculated power, wherein the current transformer for the meter constitutes a power receiving / distributing system configured so that a current ratio can be adjusted in multiple stages. is there.

In configuring the power receiving and distribution system, a current transformer control for comparing a calculated power of a power converter with a set power and adjusting a current ratio of the current transformer for the instrument according to a result of the comparison. A current transformer may be provided, and the current transformer for the instrument may be configured in such a manner that the current transformation ratio can be adjusted in multiple stages according to the output of the current transformer controller.

[0007] In configuring each of the power receiving and distribution systems, the following elements can be added.

(1) The current transformer for an instrument has a plurality of taps in a secondary winding, and the current transformer ratio is adjusted by selecting any one of the taps.

Further, the present invention provides a power receiving line for supplying power from a distribution line to a bus in a customer, an instrument transformer for detecting a voltage of the power receiving line, and a plurality of meters for detecting a current of the power receiving line. A current transformer, a power converter that calculates power from a detection voltage of the instrument transformer and a detection current of a specified instrument current transformer among the plurality of instrument current transformers, and a power converter A power generator for supplying power to the customer bus in accordance with the calculated power, and comparing the calculated power and the set power of the power converter, and according to the comparison result, any one of the instrument current transformers And a current transformer controller for designating the current transformer for power calculation as an instrument current transformer, wherein the plurality of instrument current transformers constitute a power receiving and distribution system in which the current transformer ratios are set to different values. Things.

Further, the present invention supplies power from a distribution line to a customer bus through a power receiving line, and supplies power generated by a private generator to the customer bus.
The voltage of the power receiving line is detected by an instrument transformer, and the current of the power receiving line is detected by an instrument current transformer configured such that a current transformer ratio can be adjusted in multiple stages. Calculating the power from the detected current of the instrument current transformer,
The calculated power is compared with the set power, and the current ratio of the current transformer for the instrument is adjusted in accordance with the comparison result. The present invention employs a power receiving and distribution system control method of calculating power from a detected voltage of a transformer and controlling output power of the private generator in accordance with the calculated power.

According to the above-mentioned means, since the current transformer for the instrument is configured so that the current ratio can be adjusted in multiple stages, the current transformer of the current transformer for the instrument can be changed according to the calculated power of the power converter. By adjusting, the accuracy of the current detected by the current transformer for the instrument can be improved even at a small current where the error increases in the current transformer for the large current transformer ratio. By calculating with high accuracy and controlling the output of the private generator based on the calculated power value, it is possible to keep the purchased power at an appropriate value.

[0012] When a plurality of current transformers having different current ratios are used as the current transformers for the instrument, a specified current transformer according to the power calculated by the power converter is used. By selecting, the accuracy of the current detected by the current transformer for the instrument can be improved even at a small current where the error becomes large in the current transformer with a large current transformation ratio, and the power value calculated by the power converter Is calculated with high accuracy, and the output of the private generator is controlled based on the calculated power value, so that the purchased power can be kept at an appropriate value.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a power receiving and distribution system according to an embodiment of the present invention. In FIG. 1, a power receiving line 14 that supplies power from the distribution line 10 to a bus 12 in a customer is connected to a three-phase AC (for example, 66 kV) distribution line 10 as a main circuit of a power purchase system. The power receiving line 14 is provided with an instrument transformer 16, an instrument current transformer 18, a circuit breaker 20, and a transformer 22. Then, electric power from the distribution line 10 is supplied to the customer's internal bus 12 via the circuit breaker 20 and the transformer 22.
The voltage of 6 kV is converted to 3.3 kV.

The instrument transformer 16 serves as voltage detecting means for detecting the voltage of the power receiving line 14 so as to convert the voltage of the power receiving line 14 in accordance with the transformation ratio and output, for example, a voltage of 110V. . The current transformer 18 for the instrument is configured as a current detection means for detecting the current of the power receiving line 14 so that the current transformation ratio can be adjusted in multiple stages. In the present embodiment, the tap is switched to change the current transformation ratio. , 400/5
A or 50 / 5A can be selected. That is, when a current ratio of 400/5 A is selected, when a current of 400 A flows through the power receiving line 14, a current of 5 A flows through the secondary side (secondary winding) of the current transformer for instrument 18, and a current of 50 A flows. When a current transformation ratio of / 5 A is selected, a current of 5 A flows on the secondary side of the instrument current transformation ratio 18 when a current of 50 A flows in the power receiving line 14. The current detected by the current transformer for instrument 18 is output to the power converter 24. The power converter 24 calculates the purchased power, which is the power supplied from the power receiving line 14 to the customer bus 12, by using a power value corresponding to the purchased power with the output voltage of the instrument transformer 16 and the instrument transformer. The output current of the current transformer 18 is calculated, and a signal corresponding to the calculated power value is output to the current transformer controller 26 and the private generator 28. In this case, the power converter 24 converts the calculated power value into a current value and outputs the current value to the current transformer controller 26 and the private generator 28, as shown in FIG.

The current transformer controller 26 selects a tap of the instrument current transformer 18 according to the calculated power (current value corresponding to the power value) of the power converter 24. In this case, in this embodiment, the purchased power value> 5.7 MW when the main circuit current value is 50 A is a boundary, and the purchased power value>
5.7 MW (main circuit current value> 50 A: current transformer for instrument 18)
Is 0.625 A and the calculated power of the power converter 24 is 118.9 W), the current conversion ratio is 400/5 A.
Is selected, and when the purchased power value ≦ 5.7 MW (main circuit current value ≦ 50 A), a tap having a current transformation ratio of 50/5 A is selected.

On the other hand, the private generator 28 is a power converter 2
The electric power is supplied to the customer bus 12 based on the current value corresponding to the electric power value calculated in step S4. In this case, when power is supplied to the customer bus 12 by performing a parallel operation with the power purchase system by the private power generator 28 which is a private power generator, in the present embodiment, as shown in FIG. The power is kept constant, the purchased power is reduced, and most of the load is borne by the private generator 28. When most of the load is borne by the power generated by the private generator 28 in the customer bus 12 as a load, unless the current transformer ratio of the current transformer 18 for the instrument is appropriately selected,
An error in the current transformer for instrument 18 appears as an error in the calculated power of the power converter 24, and this error cannot be ignored.

For example, when the purchased power is reduced while 400/5 A is selected as the current transformer ratio of the current transformer 18 for the instrument,
Although the power is actually being received from the power purchase system, the purchased power may be output from the power converter 24 as 0.

More specifically, when power from the distribution line 10 is supplied to the customer bus 12 via the power receiving line 14 and power generated by the private generator 28 is supplied to the customer bus 12. When power is being received at 460 kW from the power receiving line 14, which is a power purchasing system, the current value of the main circuit (power receiving line 14) is 4.02 A corresponding to 1% of the rated primary current (current = 460 kW / √). 3x66
kV = 4.02A). At this time, the current ratio of the current transformer for instrument 18 is selected to be 400/5 A, so that the current value on the secondary side of the current transformer for instrument 18 is 0.05 A (current = 5/400
× 4.02 = 0.05). And the power converter 24
Inputs a current value of 0.05 A from the current transformer for instrument 18, inputs a voltage value of 110 V from the transformer for instrument 16,
A power value of 9.53 W is calculated (power value = √3 × 0.0
5 × 110 = 9.53). In this case, the instrument current transformer 18
Is high, and when the current of the main circuit is 5% of the rated primary current of the current transformer 18 for the instrument, a ratio error of ± 3% is allowed. May calculate the power value as 9.24 W (-3%, output 4.15 mA). As shown in FIG. 2, when the output of the power converter 24 is 4 to 20 mA, ± 20 mA of 20 mA is output. Assuming that an error of 5% (± 0.1 mA) is allowed, the smaller the output, the greater the effect of the error. Therefore, the power converter 24 sets the power value to 4.05 mA (−0.1 mA).
mA). Further, due to errors of uncertain factors other than these, the output from the power converter 24 becomes 4.0 mA, and although the power is actually received from the power purchase system, from the characteristics shown in FIG. Power is 0
(Current value = point of 4.0 mA) may be output from power converter 24.

Therefore, in the present embodiment, in order to perform current measurement and power calculation with high accuracy, the power converter 24 compares the set power set in consideration of the characteristics of the system with the calculated power, According to the comparison result, the current transformer for instrument 1
8 is to be adjusted.

That is, when the main circuit current value is 50 A and the purchased power value is 5.7 MW, the purchased power value is 5.7 M
When the power exceeds W, a current conversion ratio of 400 / 5A is selected, and when the purchased power value is 5.7 MW or less, the current conversion ratio is 50 / 5A.
You are going to choose.

For example, when the purchased power is 10 MW,
400/5 A is selected as the current transformer ratio, and the power converter 24
, It is read that power of 208 W is purchased, and from the characteristics shown in FIG. 2, 4 mA + (20−4) × 20
8/1000 = 7.3 mA of current will be output.

On the other hand, when power is being received at 460 kW from the power purchase system, the main circuit current value is 4.02 A, and the current transformer ratio of the current transformer 18 for the instrument is switched to 50/5 A.
The secondary current value of the current transformer for instrument 18 becomes 0.4 A. As a result, the power converter 24 calculates the power value as 76.2 W from the current value of 0.4 A and the voltage value of 110 V (√3 × 0.4 × 110 = 76.2). In this case, FIG.
From the characteristics of 4 mA + (20−4) × 76.2 / 100
A current of 0 = 5.22 mA is output.

As described above, in the present embodiment, when the current ratio is large (400/5 A) and the current is small and the error of the current transformer 18 becomes large, the calculated power of the power converter 24 is small. When the purchased power is so small that the error is not negligible with respect to the value, 50/5 A is selected as the current transformer ratio of the current transformer for instrument 18, so that the accuracy of the current value measured by the current transformer 18 for instrument is used. And the accuracy of the power value calculated by the power converter 24 can be increased. By controlling the output of the private generator 28 based on this power value, the purchased power can be adjusted to an appropriate value. It is possible to keep.

In the above embodiment, the current transformer 1 for the instrument is used.
In the case of adjusting the current transformer ratio of 8 in multiple stages, it has been described that the tap of the secondary winding is switched to adjust the current transformer ratio.
A configuration in which a plurality of current transformers having different current ratios are provided as current transformers for the instrument, and one of the current transformers for the instrument is selected by the current transformer controller 26 based on the calculated power value of the power converter 24. Can also be adopted. That is, when the calculated power value exceeds the set value, the current transformer for the instrument having a large current transformation ratio is selected, and when the calculated power value is equal to or less than the set value, the current transformer for the instrument having a small current transformation ratio is selected.

[0025]

As described above, according to the present invention,
Since the current transformer for the instrument is configured so that the current ratio can be adjusted in multiple stages, by adjusting the current transformer of the current transformer for the instrument according to the calculated power of the power converter, the current transformer ratio is large. With the current transformer for the instrument, the accuracy of the current detected by the current transformer for the instrument can be improved even at a small current where the error increases, the power value calculated by the power converter is calculated with high accuracy, and the calculated power value By controlling the output of the private generator based on the power, it is possible to keep the purchased power at an appropriate value.

When a plurality of current transformers having different current transformer ratios are used as the current transformers for the instrument, a specified current transformer for the instrument is used in accordance with the power calculated by the power converter. By selecting, the accuracy of the current detected by the current transformer for the instrument can be improved even at a small current where the error becomes large in the current transformer with a large current transformation ratio, and the power value calculated by the power converter Is calculated with high accuracy, and the output of the private generator is controlled based on the calculated power value, so that the purchased power can be kept at an appropriate value.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a power receiving and distribution system according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a power value and a current value.

FIG. 3 is a characteristic diagram showing a relationship between purchased power and power generated by a private generator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Distribution line 12 Customer's bus 14 Power receiving line 16 Instrument transformer 18 Instrument current transformer 20 Circuit breaker 22 Transformer 24 Power converter 26 Current transformer controller 28 Private generator

Claims (5)

[Claims] 1. A power receiving line for supplying electric power from a distribution line to a bus in a customer, an instrument transformer for detecting a voltage of the power receiving line, an instrument current transformer for detecting a current of the power receiving line, A power converter for calculating power from the detected voltage of the instrument transformer and the detected current of the instrument current transformer; and a private power generator for supplying power to the customer bus in accordance with the calculated power of the power converter. A power receiving and distribution system comprising a current transformer, wherein the current transformer for the instrument is configured such that a current transformer ratio can be adjusted in multiple stages. 2. A power receiving line for supplying electric power from a distribution line to a bus in a customer, an instrument transformer for detecting a voltage of the power receiving line, an instrument current transformer for detecting a current of the power receiving line, A power converter for calculating power from the detected voltage of the instrument transformer and the detected current of the instrument current transformer; and a private power generator for supplying power to the customer bus in accordance with the calculated power of the power converter. And a current transformer controller that compares the calculated power and the set power of the power converter and adjusts the current transformer ratio of the current transformer for the instrument in accordance with the comparison result, wherein the current transformer for the instrument is provided. The power receiving and distribution system is configured such that a current transformer ratio can be adjusted in multiple stages according to an output of the current transformer controller. 3. The power distribution system according to claim 1, wherein the current transformer for an instrument has a plurality of taps in a secondary winding, and a current transformer ratio is adjusted by selecting one of the taps. system. 4. A power receiving line for supplying power from a distribution line to a bus in a customer, an instrument transformer for detecting a voltage of the power receiving line, and a plurality of current transformers for an instrument for detecting a current of the power receiving line. A power converter that calculates power from the detected voltage of the instrument transformer and a detected current of a specified instrument current transformer among the plurality of instrument current transformers; and a calculated power of the power converter. A power generator for supplying power to the customer's internal bus, and comparing the calculated power and the set power of the power converter with one of the instrument current transformers according to the comparison result. And a current transformer controller designated as an instrument current transformer of the above, wherein the plurality of instrument current transformers are set to have different current ratios. 5. A power supply from a distribution line is supplied to a bus within a customer via a power receiving line, and power generated by a private generator is supplied to the bus within the customer. A voltage of the power receiving line is measured by an instrument transformer. Detect and detect the current of the power receiving line by the current transformer for the instrument configured so that the current ratio can be adjusted in multiple stages, from the detected voltage of the instrument transformer and the detected current of the instrument current transformer. Calculating the power, comparing the calculated power with the set power, adjusting the current transformer ratio of the current transformer for the instrument according to the comparison result, and detecting the current transformer for the instrument with the adjusted current transformer ratio. A control method for a power receiving and distribution system that calculates power from a current and a detection voltage of the instrument transformer, and controls output power of the private generator in accordance with the calculated power.