JPH1051958A - Control device for received power - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a control device for received power that reduces the minimum purchased power when interconnecting a private power generation facility and a commercial power supply system. A first power meter connected to a commercial power system via an instrument transformer and an instrument current transformer in an interconnected system operation system between a commercial power system and a private power generation facility; A second wattmeter connected in parallel with the first wattmeter and having a smaller rated current and a smaller measurement range than the first wattmeter, and a current value of the current transformer for the meter being rated for the second wattmeter. Switching means for outputting a different switching signal when the current is larger than when the current is smaller; and when the current value of the current transformer for the instrument is larger than the rated current of the second power meter, the second means based on the switching signal. Measuring the received power based on the output of the first power meter, and when the current value of the current transformer for the instrument is smaller than the rated current of the second power meter, the second power meter based on the switching signal Measuring means for measuring the received power based on the output of the The control device for the received power is constituted by the control device for controlling the self-generated power based on the received power measured by the means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of the amount of electric power received from a commercial power supply system when a private power generation facility (hereinafter also referred to as "self-generation") of a customer is operated in connection with a commercial power supply system. Related to the device.

[0002]

2. Description of the Related Art In the long history of Japan's electricity business, in recent years, it has been increasing that consumers have their own power generation equipment to supplement their own power consumption. Private power generation equipment is often operated in grid connection with a power company in order to use the equipment effectively. The grid-connected customers supply their own power consumption from their own power generation facilities, and the shortfall is adjusted with the power from the power company. There are two types of grid connection: "no reverse power flow", which does not allow surplus power from private power generation facilities to be sent to the power company, and "reverse power flow," which is conditionally permitted. It is designed to determine whether to perform system interconnection in the above method.
At present, most of the work is done without reverse power. A cogeneration (cogeneration) system is an example of this private power generation facility.

[0003]

In such an interconnection operation between a self-generated power source and a commercial power supply system, the customer determines the receiving voltage and the contracted power, and also determines "Yes" and "No" for the reverse power flow. Sign a power receiving contract. "No reverse power flow"
However, while consumers want to minimize the amount of power received from the commercial power system and reduce it to zero as much as possible, surplus power generated by the reduction of the load during operation, etc., has a reverse power flow to the commercial power system. Absent. Also, in the case of reverse power flow,
Although reverse power flow is recognized, the reverse power flow more than necessary is a disadvantage because the purchase price by the power company is low.

FIG. 10 is an electrical diagram of a conventional received power control system. In the figure, 1 is a commercial power supply, 2 is a disconnector, 3 is a circuit breaker, 4 is a private power generation facility including any control system such as a generator and a governor, 5 is an instrument transformer (PT), 6 is an instrument current transformer. A unit (CT), 7 is a wattmeter, and 8 is a control device that controls the governor of the power generation facility 4 based on the output from the wattmeter 7 to control the power generated by the generator.

[0005] Now, for example, the customer receives a receiving voltage of 6.6K.
V, contract power 500KW, self-generated power 300KW, and a power receiving contract with a power company under the condition of "no reverse power flow"
A wattmeter 7 with a rated current of 5 A (hereinafter referred to as [5 A input type]) is used, PT5 is 6600: 110 whose PT ratio is determined by the receiving voltage (60 times), and CT6 is CT It is assumed that a device having a ratio of 100: 5 (20 times) is installed.

In this case, the received power is one of the readings of the power meter 7.
It becomes 200 times. The error of the wattmeter 7 used in the power system of this scale is 2% in the ordinary class and 1% in the precision class, and the input power is 0 to 1000 W (compared to the commercial power supply side 0 to 1200 K).
The output of the 5A input type power meter 7 for W) is 4 to 20 mA.
Therefore, the received power per 1 mA output is 75 KW. The control device 8 receives the output of the wattmeter 7 and outputs an output increase command to the generator if the output current is equal to or greater than the set value A, and outputs an output decrease command if the output current is less than the set value B.
If it is between (B) (dead zone), it is determined that there is no command and the power generation equipment 4
To control the generator governor.

Now, considering the error of the 5A input type wattmeter 7 (normal class 2%), the maximum error is ± 24K.
W, and a total power of 45 KW in consideration of 15 KW set as a dead zone of the control operation in the control device 8 and a margin of 6 KW may cause reverse power flow in the commercial power supply system unless power is constantly received. Will be. That is, a minimum purchased power of 45 KW (9% of the contract power) is always required. The set value of the control device 8 in this case is (4
5KW / 75KW) × 1mA + 4mA = 4.6mA, and the dead zone is (15KW / 75KW) × 1mA = 0.2mA, so the set value A is 4.8mA and the set value B is 4.4m.
A. In the interconnection operation, it is desirable to make the minimum purchased power as small as possible.

As another conventional example, consider a case in which a power receiving contract is made under the condition of “with reverse power flow” where reverse power flow is permitted with the same receiving voltage, contract power, and private power generation as described above. As the power meter 7, a 5A input power meter capable of measuring 0 to ± 1000 W, which can also measure reverse power flow power, is used. PT ratio of PT5, CT ratio of CT6,
The error of the wattmeter 7 is assumed to be the same as in the above-described example. Input power of wattmeter 7 0 to ± 1000 W (commercial power side conversion 0 to ± 12 W
Since the output of the power meter 7 with respect to 00 KW) is 0 to ± 5 V, the received power per 1 V of output is 240 KW. Control device 8 receives the output of wattmeter 7 and outputs a command to increase the output of the generator if the output voltage is equal to or more than +0.2 V, for example.
If less than -0.2V, output decrease command is output, ± 0.2V
If there is no command, the governor of the generator of the power generation equipment 4 is controlled as no command.

Here, considering the error of the 5A input type wattmeter 7 (normal class 2%), the maximum error is ± 48 KW, and even if the minimum purchased power is controlled to be 0 KW, a 48 KW useless reverse flow occurs. Could be. Therefore, such minimum purchased power is always required, which is about 10% of the contracted power.

[0010] In any of the above cases, the constant contract power of about 10
% Of the minimum purchased power is required, and how to reduce this value is a problem in the conventional system interconnection. In addition, power that is not required to be received due to power generation by a self-generated power is received due to an error.

[0011] The present invention has been made in view of the above points, and a power receiving apparatus that reduces the minimum purchased power by reducing the measurement error of the received power when interconnecting the private power generation equipment and the commercial power system. An object is to provide a power control device.

[0012]

According to an aspect of the present invention, there is provided, in accordance with one aspect, a system for connecting a commercial power supply system to a private power generation system, comprising: A first wattmeter connected via a power transformer and an instrument current transformer, and a second wattmeter connected in parallel with the first wattmeter and having a smaller rated current and a smaller measurement range than the first wattmeter. A power meter, and switching means for outputting different switching signals when the current value of the current transformer for the instrument is larger or smaller than the rated current of the second power meter, and the current of the current transformer for the instrument. When the value is larger than the rated current of the second power meter, the received power is measured based on the output of the first power meter based on the switching signal, and the current value of the current transformer for the meter is the 2 is smaller than the rated current of the wattmeter based on the switching signal. The control device for the received power is constituted by a measuring means for measuring the received power based on the output of the second power meter, and a control device for controlling the self-generated power based on the received power measured by the measuring means. .

According to another aspect of the present invention, a wattmeter connected to a commercial power system via an instrument transformer and an instrument current transformer, and connected in parallel with the wattmeter and A pulse-type watt-hour meter having a rated current equal to the rated current of the wattmeter and outputting a number of pulses proportional to the measured integrated power amount;
A control unit for the received power is constituted by a measuring unit for measuring a time interval of the pulse output from the watt-hour meter, and a control unit for controlling the private power generation based on the time interval of the pulse measured by the measuring unit.

According to still another aspect of the present invention, there is provided a wattmeter connected to a commercial power supply system via an instrument transformer and an instrument current transformer for measuring received power and reverse power flow power; A first pulse-type watt-hour meter for receiving power measurement which is connected in parallel with the wattmeter and has a rated current equal to the rated current of the wattmeter and outputs a number of pulses proportional to the measured integrated power amount; A second pulse-type watt-hour meter for measuring tidal power, first and second measuring means for measuring time intervals of pulses output from the first and second watt-hour meters, respectively, The control device for the received power is constituted by the control device for controlling the self-generated power based on the time interval of the pulse measured by the second measuring means.

[0015] According to still another aspect of the present invention, the first power for measuring the received power and the reverse power flow connected to the commercial power supply system via the instrument transformer and the instrument current transformer. A second power meter connected to the first power meter in parallel with the first power meter and having a smaller rated current and a smaller measurement range than the first power meter, and a third power meter for measuring reverse power flow. Switching means for outputting different switching signals when the current value of the current transformer for the instrument is greater than or smaller than the rated current of the second and third power meters; and the current of the current transformer for the instrument. When the value is larger than the rated current of the second power meter, the received power is measured based on the output of the first power meter based on the switching signal, and the current value of the current transformer for the meter is the 2 is smaller than the rated current of the wattmeter based on the switching signal. A measuring unit that measures the received power based on the output of the second wattmeter or the output of the third wattmeter, and a control device that controls the self-generated power based on the received power measured by the measuring unit. Thus, the control device of the received power was configured.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is an electric system diagram of a first embodiment of a control apparatus for received power according to the present invention. In the figure, commercial power supply 1,
Since the disconnector 2, the circuit breaker 3, the private power generation equipment 4, the instrument transformer (PT) 5, the instrument current transformer (CT) 6, and the 5A input type wattmeter 7 are the same as those shown in FIG. Description is omitted.

In this embodiment, an input-type power meter having a rated current of 1 A (hereinafter referred to as a "1A-input power meter") is connected in parallel with an input-type power meter having a rated current of 5 A (hereinafter referred to as "5A-input-type power meter"). 10) is connected, 5A input type wattmeter 7
An ammeter 11 with a 5A contact output is connected between the power meter 10 and the 1A input power meter 10, and a switching signal S from the ammeter 11 is provided.
Contact 12 and bypass contact 1 that are turned on and off by
3 are connected. The control device 8a receives the signal from the switching contact 12, the signal from the 5A input type power meter 7, and the signal from the 1A input type power meter 10, and controls the governor of the private power generation facility 4 according to a sequence described later.

The 1A input type wattmeter 10 has an input power of 0 to 20.
Since the output with respect to 0 W (0 to 240 KW on the commercial power supply side) is 4 to 20 mA, the received power per 1 mA output is 15 KW, and the error is 2% in the normal class and 1% in the precision class.

The ammeter with a contact output having a rated current of 5 A (hereinafter referred to as "5A type ammeter with a contact output") 11 is turned on when the current value is 1 A or more, and stays at 0.9 A or less for, for example, 1 minute or more. When the switch is turned off, a switching signal S is output (shown by a broken line in FIG. 1). As shown in FIG. 2, an ammeter 11a, an a contact 11b, and a b contact 11c are provided.
, A one-minute timer 11d, a time limit a contact 11e, and a keep relay 11f having a set terminal and a reset terminal.
It is composed of The signal output from the keep relay 11f is the switching signal S.

FIG. 3 shows an example of a circuit configuration of the control device 8a.

A determination circuit 81 determines whether the output value from the 5A input type wattmeter 7 is equal to or greater than the set value A or less than the set value B. A determination circuit 84 sets the output value from the 1A input type wattmeter 10 similarly. Circuits for determining whether the value is equal to or greater than the value C or less than the set value D; 82, 83, 86, and 87 are AND circuits;
Is an OR circuit, and 85 is an inverting circuit.

Next, the operation of the control device having the above circuit configuration will be described.

A case where a power receiving contract is made under the same conditions as those of the conventional example described with reference to FIG. 10, that is, a power receiving voltage of 6.6 KV, a contract power of 500 kW, and a self-generated power of 300 kW will be described. Figure A shows the converted power on the commercial power side and the received power per 1 mA output.
Is the same as described above.

The judgment circuit 81 of the control device 8a always has 5A
The output from the input-type wattmeter 7 is input, and the judgment circuit 84
Always contains the output from the 1A input power meter 10.

Now, when the current value of the 5A type ammeter 11 with a contact output is 1 A or more, in FIG.
1b is turned on and an H level signal is supplied to the set terminal of the keep relay 11f, so that the keep relay 11f outputs a switch signal S to turn on, and the switch contact 12 is turned on. As a result, an H level signal is given to the control device 8a via the switching contact 12, so that the output of the judgment circuit 84 is cut off and only the output of the judgment circuit 81 is sent to the governor of the generator of the private power generation facility 4. Will be able to That is, if the output value of the 5A input type wattmeter 7 is equal to or greater than the set value A, the AND circuit 82 conducts, and an output increase command is output to the generator via the OR circuit 88. Is conducted, and an output reduction command is output to the generator via the OR circuit 89. On the other hand, when the output value of the 5A input type wattmeter 7 is within the range of the set values A and B, neither the output increase command nor the output decrease command of the generator is output from the determination circuit 81.

At this time, a 5A type ammeter 1 with a contact output is used.
Since the switching signal S from 1 also turns on the bypass contact 13, the current of 1 A or more flows bypassing the 1 A input type power meter 10, so that the power meter 10 is not affected.

However, when the current value of the ammeter 11 with the 5A type contact output becomes 0.9 A or less, the contact b in FIG. 2 is turned on and the timer 11d is started. Eventually, when the timer 11d measures one minute, the timer 11d
, The timed a contact 11e is turned on, an H level signal is given to the reset terminal of the keep relay 11f,
The switching signal S to be turned on until then is switched to a switching signal to be turned off. As a result, an L level signal is given to the control device 8a via the switching contact 12, so that the output of the judgment circuit 81 is cut off and only the output of the judgment circuit 84 is controlled by the governor of the generator of the private power generation equipment 4. Will be sent to That is, if the output value of the 1A input power meter 10 is equal to or greater than the set value C, the AND circuit 86 is turned on, and the OR circuit 88 is turned on.
, An output increase command is output to the generator. If the value is less than the set value D, the AND circuit 87 is turned on, and an output reduction command is output to the generator via the OR circuit 89. On the other hand, when the output value of the 1A input type wattmeter 10 is within the range of the set values C to D, neither the output increase command nor the output decrease command of the generator is output from the determination circuit 84.

Now, paying attention to the error of the 1A input type wattmeter 10, the error of the normal class 2% is ± 4.8 KW, which is 1/5 of the error of the wattmeter 7. Assuming that the dead zone of the control operation in the control device 8 is ± 3 KW and the margin is 1.2 KW, it is only necessary to receive 9 KW in total. That is, the minimum purchased power is 45 kW when only 5A input type wattmeter is used (9% of contract power)
To 9 KW (1.5 to 2% of contract power).

In this case, the set value of the judgment circuit 84 is (9
KW / 15 KW) × 1 mA + 4 mA = 4.6 mA, and the dead zone is (3 KW / 15 KW) × 1 mA = 0.2 mA.
A, the set value C is 4.8 mA, and the set value D is 4.
4 mA. At this time, the switching signal S from the 5A type ammeter 11 with contact output turns the bypass contact 13 off.

An object of the present invention is a case where control is performed so that the received power becomes as close to zero as possible. The received power in this case is within a range that can be measured by the 1A input type wattmeter 10. Therefore, the minimum purchased power is always 4
It is clear that the control of the present invention, which requires (9 KW ± 3 KW), is much smaller than the conventional 5 KW grid connection.

Next, as a second embodiment of the present invention, a description will be given of a control apparatus for received power when a power receiving contract is made under the condition of "with reverse power flow" in which reverse power flow is permitted.

The circuit configuration of this embodiment uses a wattmeter capable of measuring reverse power flow instead of the 5A input wattmeter 7 and 1A input wattmeter 10 of the first embodiment shown in FIG. Except for this point, the circuit configuration is exactly the same as that of FIG. That is, if the wattmeter used in this embodiment has the same contract conditions as the first embodiment except for the condition of the presence or absence of reverse power flow,
0 to ± 1000w (0 to ± 1200K on commercial power side conversion)
W) can be measured, and the output is 0 ± 5.
V, therefore the received power per output 1V is 240KW
And a power of 0 to ± 200 W (0 to ± 240 KW in terms of commercial power) can be measured, and the output is 0 to ± 5 V, and thus the received power per output 1 V is 48 KW. Is a 1A input type power meter.
In each case, the error is 2% in the normal class and 1% in the precision class, and the maximum errors are ± 48 KW and ± 9.6 KW in the normal class, respectively.

A 5A type ammeter with a contact output is connected between the 5A input type wattmeter and the 1A input type wattmeter.
For example, when the voltage of A or less continues for 1 minute or more, a switching signal to turn off is output, and the switching signal controls the generator output based on the output of the 5A input type power meter, or outputs the signal to the output of the 1A input type power meter. It is determined whether to control the generator output based on this. The control sequence is the same as that described with reference to FIG.

In this embodiment, since the output values of the 5A input power meter and the 1A input power meter are 0 to ± 5V,
The control of the received power by the controller outputs a command to increase the output of the generator if the output value from these wattmeters is equal to or greater than the set value E or G, and outputs a command to decrease the output if the output value is F or H. If it is within the set values EF or GH, no output control command is issued.

In the case of this embodiment, the error is ± 9.6 KW for the 1A input type wattmeter. As in the case of the first embodiment, the received power is within the range that can be measured by the 1A input type wattmeter. Therefore, in this embodiment, the minimum purchased power required to avoid unnecessary reverse power flow is 9.6 kW. (2 of contract power
%), Which can be reduced from 48 KW (about 10% of the contract power) when only the 5A input type wattmeter is used to 9.6 KW (about 2% of the contract power).

FIG. 4 is an electrical diagram of a third embodiment of the received power control device according to the present invention. In the figure, a commercial power supply 1, a disconnector 2, a circuit breaker 3, a private power generation facility 4, an instrument transformer (P
T) 5, current transformer for instrument (CT) 6, 5A input type wattmeter 7
Are the same as those shown in FIG.

In this embodiment, the 5A input type wattmeter 7
5A input-type watt-hour meter 15 for measuring the integrated received power amount is connected in parallel with the control unit 8b. 4 controls the governor of the generator. As the 5 A input type watt hour meter 15, 10
A 10,000-pulse electronic watt-hour meter that outputs 000 pulses is used. The received power amount is measured by the pulse output from the watt-hour meter 15, and the time interval T of the pulse is used as a control signal. The relationship between the average value of the time intervals of the pulses output from the 5A input type watt-hour meter 15 and the received power amount is as follows.

Power amount (KWh) Pulse time interval (second) 60 about 7.2 45 about 9.6 30 about 14.4 15 about 28.8 7.5 about 57.6 FIG. The configuration is shown.

Reference numeral 91 denotes a judgment circuit for judging whether the output value from the 5A input type wattmeter 7 is equal to or larger than the set value I or smaller than the set value J. When the output value is equal to or larger than the set value I, an H level signal is sent to the terminal a. And outputs an L-level signal in the following cases. When the value is less than the set value J, an H-level signal is output to the terminal b. Otherwise, an L-level signal is output. 92 is a pulse time interval measuring circuit for measuring the time interval T of the pulse output from the 5A input type wattmeter 15, 93
Is a comparator circuit that outputs a signal at H level when the pulse time interval T is less than the set time a, and outputs a L level signal otherwise. 94 is an H level signal when the pulse time interval T is more than the set time b. In the case of, a comparison circuit for outputting an L-level signal, and 95 and 96 are OR circuits.

Next, a case in which a power receiving contract is made under the same conditions as in the above-described embodiment, that is, under the conditions of a receiving voltage of 6.6 KV, a contract power of 500 KW, and a privately generated power of 300 KW will be described.

The set times a and b of the comparison circuits 93 and 94 are each set to 29 seconds (based on a design idea that the dead zone is set to 7.5 KW and control for a constantly changing load is to be executed at least once every 60 seconds. The received power is 15 KW) and 57 seconds (corresponding to 7.5 KW).
Further, the control by the 5A input type wattmeter 7 is a backup when the time control by the 5A input type watt hour meter 15 cannot be made in time, and the set values I and J are respectively 4.8, for example.
mA (equivalent to 60 KW) and 4.1 mA (7.5 KW)
(Equivalent to).

In this embodiment, the control device 8b has 5
The output of the A-input wattmeter 7 and the output of the 5A-input wattmeter 15 are always input, and the output of the 5A-input wattmeter 7 is 4.8 mA or more, that is, the received power is 60 KW or more, or the 5A-input power When the output of the meter 15 is 15 kWh or more, a command to increase the output of the generator
And the output of the 5A input type wattmeter 7 is increased to 4.
When the received power is less than 1 mA, that is, when the received power is less than 7.5 kW or the output of the 5 A input type watt-hour meter 15 is less than 7.5 kWh, a command to reduce the output of the generator is output, and control is performed to avoid the risk of reverse power flow. ing.

In this embodiment, except for the case where a very rapid load change occurs, the control range of the 5A input type watt hour meter is used. This is determined at the corresponding 15 KWh, which can be greatly reduced as compared with the conventional minimum purchased power of 45 KW described with reference to FIG. In the present embodiment, 15 KWh as the power amount is considered to correspond to the average power amount of 15 KW, so that the minimum purchased power can be reduced to about 3% of the contracted power amount (500 KW).

The comparison circuit 9 for determining the minimum purchased power
The reference value for the comparison of No. 3 (29 seconds in the above embodiment) is determined by the timing at which the output increase / decrease command of the generator is output in accordance with the fluctuation of the local load.

Since the 5A input type watt-hour meter 15 used in this embodiment has been conventionally used for measuring the amount of received power, its signal can be used for controlling the amount of received power in the present invention. In this embodiment, the ammeter with contact output of the second embodiment is not required.

FIG. 6 is an electric diagram of a fourth embodiment of a control apparatus for received power according to the present invention which can be applied to a power receiving contract with "reverse power flow". In FIG. The instrument 3, the private power generation facility 4, the instrument transformer (PT) 5, and the instrument current transformer (CT) 6 are the same as those shown in FIG.

In this embodiment, a 5A input type wattmeter 7a capable of measuring both the received power and the reverse power flow is used.
The input-type watt-hour meter 15a and the 5A-input-type watt-hour meter 15b for measuring the integrated power amount of the reverse power flow are connected, and the control device 8c outputs the output of the 5A-input-type wattmeter 7a and the two 5A-input-type power amounts. The governor of the generator of the private power generation facility 4 is controlled based on the outputs of the total 15a and 15b. 5A input type wattmeter 7a is 0 to ± 1000 W (commercial power supply side conversion 0 to ±
The output for power of 1200 KW) is 0 ± 5V. The 5A input watt-hour meters 15a and 15b include:
As in the case of the above-described fourth embodiment, a 10,000-pulse electronic watt-hour meter that outputs 10,000 pulses per 1 KWh of electric power on the secondary side is used, and the time intervals T ₁ and T _{1 of the} pulses output from each are used. ₂ is used as a control signal.

FIG. 7 shows a circuit configuration of the control device 8c.

Reference numeral 101 denotes a judgment circuit for judging whether the output value from the 5A input type wattmeter 7a is equal to or more than the set value K or less than the set value L.
A level signal is output, and when it is less than the set value L, an H level signal is output to the terminal b. 102a is the pulse time interval measuring circuit for measuring a time interval T ₁ of the pulse output from 5A input energy meter 15a, 102b measures the time interval T ₂ of the pulse output from 5A input energy meter 15b pulse time interval measurement circuit, 103 is 5A input energy meter 15a of pulses output from the H level at time interval T ₁ is set time c, the other comparison circuit outputs an L level signal when the, 104 comparator circuit, 105 and 106 OR circuit 5A input energy meter 15b H level when the following time interval T ₂ is also set time d of the pulse output from, for outputting an L level signal at all other times It is.

Next, the case of the same conditions as in the fourth embodiment will be described.

Set times c and d of comparison circuits 103 and 104
Is based on a design philosophy of wanting to execute control for constantly changing loads at least once every 36 seconds.
6 seconds (corresponding to at least 12 KW of power receiving or reverse power flow power). The control by the 5A input power meter 7a is as follows.
This is a backup when the time control by the 5A input type watt-hour meter 15 is not enough, and the set values K and L are set to, for example, 0.2 V (corresponding to 48 KW).

In this embodiment, the control device 8c has 5
The output of the A-input wattmeter 7a and the outputs of the two 5A-input wattmeters 15a and 15b are always input, and the
The output of the input type wattmeter 7a is + 0.2V or more, that is, the received power is 48KW or more, or the 5A input type watt hour meter 15a
Is greater than 12 kWh, a command to increase the output of the generator is output to increase the power generated by the in-house
The output of the input type wattmeter 7a is less than -0.2 V, that is, the reverse power flow is less than 12 kW, or the 5A input type watt hour meter 15
When the output of b is less than 12 KWh, a command to reduce the output of the generator is output, and control is performed so that the reverse power flow does not increase any more.

Also in this embodiment, the minimum purchased power is set as a reference value for comparison in the comparison circuit 103 or 104 because the control range is of the 5A input type watt hour meter except when a very rapid load change occurs. 1 for seconds
2 KWh, which can be greatly reduced as compared with the minimum purchased power of 48 KW in the case of the conventional "with reverse power flow" described with reference to FIG. This is the contracted energy (5
00 KW).

The comparison circuit 1 for determining the minimum purchased power
Reference value for comparison of 03 and 104 (36 seconds in the above embodiment)
Is determined according to the timing at which the output increase / decrease command of the generator is output in accordance with the fluctuation of the load on the premises.

FIG. 8 is an electric system diagram of a fifth embodiment of the received power control device according to the present invention, which is a further improvement of the fourth embodiment in the case of "with reverse power flow" shown in FIG. In the figure,
Commercial power supply 1, disconnector 2, circuit breaker 3, private power generation equipment 4, instrument transformer (PT) 5, instrument current transformer (CT) 6, 5A
The input wattmeters 7a are the same as those shown in FIG.

In this embodiment, a 1A input type power meter 10 for measuring the amount of received power in parallel with a 5A input type wattmeter 7a capable of measuring both the received power and the reverse power flow is used to measure the power amount of the reverse power flow. A 1A input wattmeter 10a to be measured is connected, and a 5A contact output ammeter 11 is connected between the 5A input wattmeter 7a and the 1A input wattmeter 10, and switching from the ammeter 11 is performed. A switching contact 12 to be turned on and off by a signal S and a bypass contact 13 are provided. The control device 8d receives the signal from the switching contact 12, the signal from the 5A input type power meter 7a, and the signals from the two 1A input type power meters 10 and 10a, and governs the private power generation facility 4 according to a sequence described later. Control.

The 5A input type wattmeter 7a is 0 to ± 1000 W
The output for electric power (0 to ± 1200 KW on the commercial power source side) is 0 to ± 5 V. The 1A input watt-hour meters 10 and 10a output 0 to +200 W (commercial power supply side conversion: 0 to +240 KW) and 0 to -200 W (commercial power supply side conversion: 0 to -240 KW) of output power of 4 to 20 respectively.
mA. The wattmeter errors are 2% for the normal class and 1% for the precision class. In addition, 5A type ammeter with contact output 11
Is the same as that used in the first embodiment. In the circuit configuration shown in FIG.
A switching signal S (indicated by a broken line in FIG. 1) that is turned off when the state A or less continues for one minute or more is output.

FIG. 9 shows a circuit configuration of the control device 8d.

Reference numeral 110 denotes a terminal b when the output value from the 5A input type wattmeter 7a is equal to or larger than the set value M or smaller than the set value N.
Circuit which outputs an H level signal to
12, an AND circuit; and 113, an inverting circuit. 114 and 115 are 1A input type wattmeters 10 and 10 respectively.
This is a determination circuit that outputs an H-level signal when the output value from a exceeds the set value O or the set value P or more, for example, after 5 seconds. 116 and 118 are AND circuits, 11
7, 119 are OR circuits.

In this embodiment, the control device 8d has 5
The output of the A-input wattmeter 7a, the outputs of the two 5A-input wattmeters 10 and 10a, and the signal from the switching contact 12 are always input.

Next, the same conditions as in the second embodiment, that is, receiving voltage 6.6 KV, contract power 500 kW, private power 300
A case in which a power receiving contract is made under the condition of “with reverse power flow” in KW will be described.

When the current value of the ammeter 11 with a 5A contact output is 1 A or more, a switching signal S for turning on is output and the switching contact 12 is turned on. As a result, an H level signal is supplied to the control device 8d via the switching contact 12, so that the outputs of the judgment circuits 114 and 115 are cut off, and only the output of the judgment circuit 110 is controlled by the governor of the generator of the private power generation facility 4. Will be sent to That is, 5A
If the output value of the input type wattmeter 7a is equal to or greater than the set value M, the AND circuit 111 is turned on, and an output increase command is output to the generator via the OR circuit 117. If the output value is less than the set value N, the AND circuit 112 is turned on. Then, an output reduction command is output to the generator via the OR circuit 119. On the other hand, when the output value of the 5A input type power meter 7 does not satisfy the above condition, that is, when the set values M to N
When it is within the range, neither the output increase command nor the output decrease command of the generator is output.

At this time, a 5A type ammeter 1 with a contact output is used.
Since the switching signal S from 1 also turns on the bypass contact 13, the current of 1 A or more is applied to the 1 A input type power meters 10 and 10.
Since the current flows by bypassing “a”, there is no influence on the power meters 10 and 10a.

However, when the current value of the 5A type ammeter 11 with a contact output becomes 0.9 A or less, the switching signal S to be turned on so far is switched to a switching signal to be turned off. As a result, an L level signal is given to the control device 8d via the switching contact 12, so that the output of the judgment circuit 110 is cut off and the output of the judgment circuit 114 or 115 is changed to the output of the generator of the private power generation equipment 4. Be sent to the governor.
That is, when the output value of the 1A input-type power meter 10 measuring the received power amount is equal to or greater than the set value O or the set value P,
When the time continues for more than one second, the AND circuit 116 conducts, and an output increase command is output to the generator via the OR circuit 117.
In addition, a 1A input-type wattmeter 1 for measuring the amount of reverse flow power
If the output value of 0a is greater than or equal to the set value O or P,
If it continues for more than one second, the AND circuit 118 conducts, and an output reduction command is output to the generator via the OR circuit 119.
On the other hand, when the output values of the 1A input type watt meters 10 and 10a do not satisfy the above conditions, neither the output increase command nor the output decrease command of the generator is output.

Now, here, the 1A input type wattmeters 10, 10
Focusing on the error of a, the error of 2% for the normal class is ± 4.8K
W, which is 1/5 of the error of the wattmeter 7a. That is, the minimum purchased power can be reduced from ± 48 KW to ± 4.8 KW when only the 5 A input type wattmeter is used.

In this case, the set value P of the judgment circuits 114 and 115 is (4.8 KW / 15 KW) × 1 mA + 4 mA =
Although it is 4.32 mA, a timer (in this case, 5 seconds) is provided to avoid frequent control operations.
Further, in order to improve controllability, a set value O is provided outside the set value P (for example, a set value of 4.6 mA).

Since the present embodiment can be controlled by the current signal as compared with the second embodiment, the accuracy does not decrease even if the distance between the power receiving point and the private power generation equipment is long.

Although a wattmeter and a watt-hour meter are used in the above embodiment, in the present invention, it is not necessary to be able to visually measure the power value or the power amount value, and it is sufficient to take out the data as data. Therefore, a transducer can be used instead of a power meter or a watt hour meter.

[0070]

According to the present invention, for a substantial part of the system interconnection operation between the commercial power supply system and the private power generation equipment, the received power or the power is measured by a small-range power meter or a pulse-type watt-hour meter connected in parallel to the existing power meter. Since the reverse power flow power is measured, the error due to the power meter can be kept small, and the minimum purchased power can be reduced.
Extremely economical grid connection becomes possible.

Since the pulse-type watt-hour meter has been used for measuring the integrated power amount, the error power can be minimized by simply processing the output signal without adding a new meter, thereby minimizing the power purchase. The power can be reduced.

[Brief description of the drawings]

FIG. 1 is an electrical diagram of a first embodiment of a control device for received power according to the present invention.

FIG. 2 shows a circuit configuration of an ammeter with a contact output used in the first embodiment shown in FIG.

FIG. 3 shows a circuit configuration of a control device in the first embodiment shown in FIG.

FIG. 4 is an electric system diagram of a third embodiment of a control device for received power according to the present invention.

FIG. 5 shows a circuit configuration of a control device in the third embodiment shown in FIG.

FIG. 6 is an electrical system diagram of a fourth embodiment of the control apparatus for received power according to the present invention.

FIG. 7 shows a circuit configuration of a control device according to the fourth embodiment shown in FIG.

FIG. 8 is an electric system diagram of a fifth embodiment of the control apparatus for received power according to the present invention.

FIG. 9 shows a circuit configuration of a control device according to the fifth embodiment shown in FIG.

FIG. 10 is an electrical system diagram of an example of a conventional received power control device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 Disconnector 3 Circuit breaker 4 Private power generation equipment 5 Instrument transformer 6 Instrument current transformer 7 5A input type power meter 8, 8a, 8b, 8c, 8d Control device 10, 10a 1A input type power meter 11 5A type ammeter with contact output 12 Switching contact 13 Bypass contact 15, 15a, 15b 5A input type watt hour meter 81, 84, 91, 101, 110, 114, 115
Judgment circuit 92, 102a, 102b Pulse time interval measurement circuit 93, 94, 103, 104 Comparison circuit

Claims (12)

[Claims] A first power meter connected to the commercial power supply system via an instrument transformer and an instrument current transformer, wherein the first power meter is connected to the commercial power supply system via an instrument current transformer; A second wattmeter connected in parallel with the first wattmeter and having a smaller rated current and a smaller measurement range than the first wattmeter, and a current value of the current transformer for the second wattmeter Switching means for outputting a different switching signal when the current is larger than the rated current and when the current is smaller than the rated current of the second power meter. The received power is measured based on the output of the first power meter, and when the current value of the current transformer for the instrument is smaller than the rated current of the second power meter, the second power is measured based on the switching signal. Measuring means for measuring the received power based on the output of the meter, A control device for controlling the privately generated power based on the received power measured by the means. 2. The received power control device according to claim 1, wherein said switching means is a current meter with a contact output having a rated current equal to the rated current of said first wattmeter. 3. The second power meter has a bypass circuit having a bypass contact turned on by the switching signal when a current value of the instrument current transformer is larger than a rated current of the second power meter. The control device for received power according to claim 2. 4. The switching means outputs a switching signal when the current value of the current transformer power meter is smaller than the rated current of the second power meter for a predetermined time or more.
Or the control device for receiving power according to 3. 5. The received power control device according to claim 1, wherein the first power meter and the second power meter are power meters that can measure received power and received power of reverse flow. 6. An interconnecting system operation system between a commercial power supply system and a private power generation facility, comprising: a power meter connected to the commercial power supply system via an instrument transformer and an instrument current transformer;
A pulse-type watt-hour meter connected in parallel with the watt-hour meter and having a rated current equal to the rated current of the watt-meter and outputting a number of pulses proportional to the measured integrated power amount; and outputting from the watt-hour meter A control device for receiving power, comprising: a measuring means for measuring a time interval of a pulse; and a control device for controlling private power generation based on the time interval of the pulse measured by the measuring means. 7. The control device, when the time interval of the pulse measured by the measuring means is smaller than a first predetermined value, outputs a command to increase the output of the private power generation facility. 7. The received power control device according to claim 6, wherein when the value is larger than a predetermined value of 2, a command to reduce the output of the private power generation facility is output. 8. An interconnected system operation system between a commercial power supply system and a private power generation facility, wherein the received power and the reverse power flow are connected to the commercial power supply system via an instrument transformer and an instrument current transformer. A power meter connected in parallel with the power meter and having a rated current equal to the rated current of the power meter and outputting a number of pulses proportional to the measured integrated power amount. Pulse-type watt-hour meter and a second pulse-type watt-hour meter for measuring power of reverse power flow, and first and second units for measuring time intervals of pulses output from the first and second watt-hour meters, respectively. And a control device for controlling the private power generation based on the time intervals of the pulses measured by the first and second measurement devices. 9. The controller outputs an instruction to increase the output of the private power generation facility when the time interval of the pulse measured by the first measuring means is smaller than a predetermined value, and measures the output by the second measuring means. The power receiving control device according to claim 8, wherein when the time interval between the pulses is smaller than the predetermined value, a command to reduce the output of the private power generation facility is output. 10. An interconnected system operation system between a commercial power supply system and a private power generation facility, wherein the received power and reverse power flow connected to the commercial power supply system via an instrument transformer and an instrument current transformer. A first wattmeter for measuring power;
A second wattmeter for measuring the received power and a third wattmeter for measuring the power of the reverse power flow which are connected in parallel with the wattmeter and have a smaller rated current and a smaller measurement range than the first wattmeter; Switching means for outputting different switching signals when the current value of the current transformer is larger than or smaller than the rated current of the second and third power meters; and When the rated current of the wattmeter is larger than the rated current of the wattmeter, self-generated power is controlled based on the output of the first wattmeter based on the switching signal, and the current value of the
And a control device for controlling private power generation based on the output of the second wattmeter or the output of the third wattmeter based on the switching signal when the current is smaller than the rated current of the wattmeter. Power control device. 11. The received power control device according to claim 10, wherein said switching means is a current meter with a contact output having a rated current equal to the rated current of said first wattmeter. 12. The switching device according to claim 11, wherein the switching unit outputs a switching signal when a current value of the current transformer for the instrument is smaller than a rated current of the second and third power meters for a predetermined time or more. Control device for received power.