JPS598208Y2 - Primary converter for reactive power meter - Google Patents

Description

[Detailed description of the invention] The present invention relates to a primary converter for a reactive wattmeter, and in particular, a reactive wattmeter suitable for measuring reactive power and reactive energy in a three-phase, three-wire power system. This relates to a primary converter for use.

BACKGROUND ART Conventionally, in order to measure the amount of reactive power in a three-phase three-wire power system, a method defined as the C-3 method in the JIS standard is usually used.

This C-3 method uses an integrating wattmeter to indicate the amount of reactive power in a three-phase, three-wire power system, especially in the case of an unbalanced load.The circuit connection is shown in Figure 1 of the attached drawings. It's something like this.

This C-3 system uses one phase shift transformer 1 and two integrating wattmeters 2 and 3.

The phase shift transformer 1 is a type-connected autotransformer,
Line voltage E1 and E between power lines L1, L2 and L3
A voltage proportional to 90' shifted phase of wattmeter 2 is applied to voltage coils 2B and 3B of each integrating wattmeter 2 and 3, respectively.

On the other hand, a current proportional to the current I1 flowing through the power line L1 flows to the current wire 2A of the integrating wattmeter 2, and a current proportional to the current I1 flowing through the power line L3 flows to the current wire 3A of the integrating wattmeter 3. It has become.

In this case, the sum of the indicated values of integrating wattmeters 2 and 3 is
This shows the amount of reactive power in this power system.

In the C-3 method that has been generally adopted,
In addition to requiring a special phase-shifting transformer, the amount of reactive power is indicated by an indicator, and instantaneous monitoring is required at remote monitoring stations, which have become popular in recent years. It is not suitable for transmitting reactive power or reactive energy amount as measurement data.

In view of the above-mentioned points, the purpose of this invention is to make it possible to measure reactive power in a three-phase three-wire power system without using a special phase-shifting transformer, and to make it possible to measure long-distance transmission. It is an object of the present invention to provide a primary converter for a reactive power meter, which makes it possible to obtain suitable measurement results.

Next, the present invention will be described in detail with reference to FIG. 2 of the accompanying drawings regarding an embodiment of the present invention.

FIG. 2 is a circuit diagram schematically showing an embodiment of a device for measuring the amount of reactive power in a three-phase three-wire power system using the primary converter of the present invention.

Reference numeral 10 designates the primary converter main part according to the invention, which consists of two transformers T1 and T2.

The transformer T1 and the transformer T2 have the same specifications, and the transformer T1 has a primary winding 11 and two secondary windings 13 and 1.
4, and the transformer T2 also has a primary winding 12 and a 2
It has two secondary windings 15 and 16.

If the number of turns of the primary windings 11 and 12 is α, the number of turns of the secondary windings 13 and 15 should be 2Kα, and the number of turns of the secondary windings 14 and 16 should be Kα (here, K is a constant).

One end of the primary winding 11 is connected to the input terminal P1, the other end of the primary winding 11 and one end of the primary winding 12 are connected to the input terminal P2, and the other end of the primary winding 12 is connected to the input terminal P2. , input terminal P3
It is connected to the.

On the other hand, one end of the secondary winding 13 is connected to the output terminal S2, and the other end is connected to one end of the secondary winding 16.
The other end is connected to a terminal So connected to OV.

One end of the secondary winding 14 is connected to the output terminal S1, the other end is connected to one end of the secondary winding 15, and the other end of the secondary winding 15 is connected to the terminal So connected to O■. has been done.

Since the primary converter main section 10 has such a structure, the input terminals P1, P2, and P3 are connected to the first
Each power line Ll, L2, and L of the three-phase three-wire power system in the diagram
3, a voltage proportional to the phase of the line voltages E1 and E2 shifted by 90' is applied to the output terminals S.3 and S.3. -S. Approximately output to S2-So.

In this example, the conversion outputs occurring at output terminals S1 and S2 are multipliers IC1 and IC1, respectively.
1' is applied to one input.

The other inputs of the multipliers IC1 and IC1' are connected to a current transformer CT1 that detects the current 11 flowing in the power line L1 and the current 3 flowing in the power line L3 of the power system shown in FIG.
and the outputs of CT2 are added, respectively.

Multipliers ■C1 and IC1' multiply their two inputs together, and integrators ■C2 and ■C' respectively.
Output to 2.

Integrators ■C2 and ■C'2 respectively integrate them and output them to adder ■C3.

Adder ■C2 adds these integral values and outputs a signal representing the amount of reactive power in the three-phase three-wire power system.

Amplifier ■C4 amplifies the output signal of adder ■C3,
It is for outputting to the output terminal 20 a signal suitable for subsequent signal use, for example, for shaking an indicator or for distant transmission.

As mentioned above, according to the primary converter for a reactive power meter of the present invention, it is possible to indicate the amount of reactive power in a three-phase three-wire power system without using a special phase-shifting transformer or the like as in the past. I can do it,
Furthermore, you can freely specify instantaneous reactive power values or integrated reactive power amounts as needed, and by using an analog multiplier etc. as a multiplier, you can convert them into electrical signals suitable for long-distance transmission. It is also easy to express values.

[Brief explanation of the drawing]

Figure 1 of the attached drawings is a schematic diagram for explaining the method for measuring the amount of reactive power in the conventional Sanwa three-wire power system, and Figure 2 is a schematic diagram of a three-phase three-wire system using the primary converter of the present invention. FIG. 1 is a circuit diagram schematically showing an embodiment of a device for measuring reactive power amount of a power system. L1, L2, L3...Power line, 10...
・Main part of primary converter, T1, T2...Transformer,
11.12... Primary winding, 13, 14, 15.
16... Secondary winding, P1, P2, P3...
...Input terminal, S1, S2...Output terminal, CT
1, CT2...Current transformer, IC, ,■C'1・
...Multiplier, IC2, ■C'2...Integrator, ■C3...Adder, ■C4...Amplifier, 20... ...Output terminal.

Claims (1)

[Scope of utility model registration request] It comprises first, second and third human power terminals, first and second output terminals, and first and second transformers of the same specification, each transformer having a primary winding and a first and second output terminal. It has one secondary winding and a second secondary winding, the number of turns of the first secondary winding is twice the number of turns of the second secondary winding, and the number of turns of the first secondary winding is twice that of the second secondary winding. One end of the primary winding of the transformer is connected to a first input terminal, and the other end of the primary winding of the first transformer and one end of the primary winding of the second transformer are connected to a second input terminal. the other end of the primary winding of the second transformer is connected to the third input terminal, the first secondary winding of the first transformer and the second The secondary winding of
The second secondary winding of the first transformer and the first secondary winding of the second transformer are connected in series between the output terminals of the second transformer. 1. A primary converter for a reactive wattmeter, wherein the first, second, and third input terminals are connected to respective power lines of a three-phase three-wire power system.